Apr 16, 2013 - In a Partial Fulfillment of the Requirements for the Degree of .... The activation energy (Ea) values for the corrosion of coated C.S by ... was (71.936) kJ.mol-1 obtained when C.S coated by SiC in ...... Compression of the electric double ..... bonding strength of charging agent-adsorbed coarse Ti particles ...
Republic of Iraq Ministry of Higher Education & Scientific Research University of Baghdad College of Science Department of Chemistry
Corrosion and Corrosion Protection Studies of Carbon Steel alloy in Seawater using; Zirconia, Silicon Carbide and Alumina Nanoparticles A thesis Submitted to the College of Science In a Partial Fulfillment of the Requirements for the Degree of Master of Science in Physical Chemistry By
Haider Abdulkareem Yousif B.Sc. (Chemical Science) 2012 Supervised by
Prof. Dr. Khulood Abed Saleh
2014 A.D.
1435 A.H.
بِسْمِ اللَّهِ الرََّحْمَنِ الرََّحِيمِ ﴿ يُْؤيِت ا ْيْل ْكمَةَ مَنْ يَشَاءُ وَمَ ْن ت ا ْيْل ْكمَةَ فَقَ ْد أ يُوِتَ خَ ْْياً َكيثْيًا يُْؤ َ ومَا ي َّذ َّكر يإالَّ أُولُو ْاْلَلْبَ ي اب ﴾ َ َ ُ اّلل العلي ي العظيم ص َد َق َّ ُ َ (سورة البقرة /اآلية )962
Supervisor Certification I certify that this thesis “Corrosion and Corrosion Protection Studies of Carbon Steel alloys in Saline Water using; Zirconium Oxide, Silicon Carbide and Alumina Nanoparticles’’, was prepared under my supervision at Chemistry Department, College, University of Baghdad, in partial fulfillment of the requirements for the degree of Master of Science in Chemistry (Physical chemistry).
Signature: Prof. Dr. Khulood Abed Saleh (Supervisor) Date:
/
/ 2014
In view of the available recommendations, I forward this thesis for debate by Examining Committee.
Signature: Prof. Dr. Suaad Mohammed Hussein Head of Chemistry Department Date:
/ / 2014
Linguistic Certification This is to certify that I have read the thesis entitled,’’ Corrosion and
Corrosion Protection Studies of Carbon Steel alloys in Seawater using; Zirconia, Silicon Carbide and Alumina Nanoparticles’’, and corrected the linguistic mistakes I found. Therefore, this thesis is qualified for debate.
Signature: Name: Prof. Dr. Ahlam Jameel Abdulghani Date:
/ /2014
Scientific Evaluation Report This is to certify that I have read the thesis entitled, “Corrosion and
Corrosion Protection Studies of Carbon Steel alloy in Seawater using; Zirconia, Silicon Carbide and Alumina Nanoparticles’’, and corrected the scientific mistakes I found. The thesis is, therefore, qualified for debate.
Signature: Name: Prof. Dr. Ahlam Jameel Abdulghani Date: / /2014
Committee Certificate We certify that we read this thesis, “Corrosion and Corrosion Protection Studies of Carbon Steel alloys in Saline Water using; Zirconium Oxide, Silicon Carbide and Alumina Nanoparticles’’, and as examining committee examined the student (Haider Abdulkareen yousif) in its contents, and that in our opinion it is adequate (Excellent) with standing as a thesis for the degree of Master of Science in Physical Chemistry. Signature: Asst. Prof. Dr. AbdulKareem Mohammed Ali (Chairman) College of Science University of Baghdad Date: / / Signature: Asst. Prof. Dr. Rana Afif Majed (Member)
Signature: Lect. Dr. Wadah Naji Jasim (Member)
Date:
Date:
/ /
/ /
Signature: Prof. Dr. Khulood Abed Saleh (Supervisor) Date:
/ /
Approved by the council of the College of Science / University of Baghdad: Asst. Prof. Dr. Fadial Abed Rasin Dean of College of Science University of Baghdad Date: / /
اإلهـــداء اىل من بلغ الرسالة وأدى األمانة ..ونصح االمة ..اىل نيب الرمحة ونور العاملني ..سيدان حممد صلى هللا عليه وسلم. إىل...من امحل أمسه بكل افتخار اىل ...من كان ومل يزل معلمي عند جهلي وقدويت يف حيايت إىل ...من حصد األشواك عن دريب ليمهد يل طريق العلم (والدي) إىل ...بسمة احلياة وسر الوجود اىل ...من اليكل اللسان ابلدعاء هلا وفاءا اىل ...رفيقة دريب اليت مل تتخلى عين أبدا وببسمة إىل ...نبع التضحية واحلنان (والديت)
حيدر
In the name of Allah, the moat gracious, the most merciful All praises be due to Allah, the Sustainer of the entire world, the Origin of science and wisdom, and may Allah’s mercy and peace be upon our leader, Mohammad, his family and companions. I would like to express my sincere gratitude to my supervisor Prof. Dr. Khulood Abed Saleh for her continuous support in my M.Sc. study, and also for her patience, motivation, enthusiasm, and immense knowledge. Her guidance has helped me during the time of research and writing of this thesis. I could not have imagined having a better advisor and mentor for my M.Sc. study. My special thanks and sense of gratitude are due to my family; my father, my mother, lovely brothers and sister (Rowida). Iam glad to acknowledge the staff and teachers of Department of Chemistry in College of Science, University of Baghdad, especially Dr. AbdulKareem alsamaraei and Raed Abd Shaker. And I should extend my thanks to the staff of IHEC, especially Abass Reja, Also, my thanks go to all friends whom supported me during my study, especially Omar, Mustafa, Saed, Fadhel and Malek and all the people who have given help and are not mentioned.
Haider
Abstract Abstract Corrosion and corrosion protection of carbon steel (C.S) alloy in seawater (3.5% NaCl) was achieved in this thesis. Three types of nanoparticles (NPs) were used to protect C.S the first silicon carbide (SiC), second alumina (Al2O3) and the third zirconium oxide (ZrO2) nanoparticles (NPs). Electrophoretic deposition (EPD) technique was applied to coating the C.S surface. Different polyacrylic acid (PAA) percentage (0.1- 1)% were added to the suspension solution of coating by the three types of NPs, to improve the protection efficiency (PE%) for the coated C.S surfaces. The corrosion rate with respect to uncoated and coated C.S with the three above NPs were measured. Different corrosion parameters were obtained; corrosion current density (icorr), corrosion potential (Ecorr), cathodic and anodic Tafel slopes (bc,ba), protection efficiency (PE%), polarization resistance (Rp) and the surface porosity (P%). The effect of temperatures (298-328)K on the corrosion of uncoated and coated C.S by the three NPs in presence and absence of PAA were also investigated and therefore activation energy (E a) and preexponential factor (A) were calculated. Thermodynamic parameters ΔG, ΔH and ΔS for all corrosion processes were obtained. Coated C.S were analysed using atomic force microscopy (AFM) to detect the morphology of surface and the particles size of coat layers which range from 60-103 nm, which greater than the starting particles. The corrosion current densities (icorr) were increased generally with increasing temperatures for all cases and icorr reduced after coated C.S by different NPs in absence and presence PAA, therefore icorr reduced from 168.88 µA.cm-2 to 19.45, 28.71 and 30.2 µA.cm-2 for C.S coated by SiC, ZrO2 and Al2O3 respectively at 298K.While the Ecorr shifted to more active potential after coated by different NPs excepting when C.S coated by SiC in presence of (0.25%) PAA in coating solution suspension where Ecorr shifted to noble direction. The protection efficiency (PE%) of all coated C.S in absence and presence of PAA showed noteworthy degree of enhancement and the PE% ranged between (85 to 99.65)% for SiC , (69 to 91)% for ZrO2 and (77 to 87.9)% for Al2O3. The surface porosity (P%) were increased with increasing temperatures for all cases. The activation energy (Ea) values for the corrosion of coated C.S by different NPs lead to higher values than Ea for uncoated C.S and the highest value was (71.936) kJ.mol-1 obtained when C.S coated by SiC in presence of (0.25%) PAA. The free energy (ΔG) Values for the corrosion of coated C.S generally more negatively than uncoated and the values of enthalpy (ΔH) for the corrosion of coated C.S by ZrO2 and Al2O3 were less negatively than uncoated C.S while coated C.S by SiC lead to more negatively ΔH values. i
List of content No. of Item
Subject Abstract List of Content Tables List Figures List Symbols List
Page No. i ii v vii xi
Chapter One – Introduction 1.1 1.2 1.3 1.3.1 1.3.2 1.3.3 1.3.4 1.3.5 1.3.6 1.3.7 1.4 1.4.1 1.4.2 1.4.3 1.4.4 1.5 1.6 1.7 1.7.1 1.7.2 1.7.3 1.7.4 1.7.5 1.8 1.8.1 1.8.2
Corrosion Forms of Corrosion Corrosion Measurement Techniques Polarization curves Linear Polarization Resistance Open Circuit Potential Decay Electrochemical Impedance Measurement Electrochemical Noise Measurement Weight Loss Measurement Thermometric method (Mylius) Measurement Basic of Polarization curve Activation Polarization Concentration Polarization Combined Polarization Resistance Polarization Tafel extrapolation Cyclic Potentiondynamic Curve Corrosion Protection & Control cathodic and anodic control Corrosion Inhibitors Protective coatings Cathodic protection Anodic protection Concepts of Electrophoretic Deposition Electrophoretic Deposition mechanism Suspensions Suitable for EPD ii
1 1 3 3 3 3 4 4 4 5 5 6 9 11 12 13 15 16 16 17 17 19 20 20 22 23
1.8.3 1.8.3.1 1.8.3.2 1.8.3.3 1.8.4 1.8.5 1.9 1.9.1 1.9.2 1.9.3 1.10 1.11
Application of Electrophoretic Deposition Coatings Fibre reinforced ceramic matrix composites Laminated and graded composites Advantages of Electrophoretic Deposition Disadvantages of Electrophoretic Deposition Nanomaterials Aluminum oxide Silicon Carbide Zirconium dioxide Literature Survey Aim of the Research
23 23 23 24 24 25 25 26 28 28 29 34
Chapter Two - Experimental Part 2.1 2.2 2.2.1 2.2.2 2.3 2.4 2.5 2.6 2.6.1 2.6.2 2.7 2.7.1 2.7.2 2.8 2.9
Experiments Part Chemicals and Instrumentation Chemicals and Materials Instruments The Corrosion Cell Sample Preparation Preparation of emulsion Electrophoresis of Deposition of emulsion (Coating Samples) Cathodic Method Anodic Method Test Techniques Open Circuit Potential Tafel Extrapolation Coated thickness calculations Atomic Force Microscopy (AFM)
35 35 35 37 37 39 39 40 41 41 42 42 42 42 43
Chapter Three - Result and Discussions 3.1 3.1.1 3.1.2 3.2 3.3
Corrosion behavior of Carbon Steel Corrosion test for uncoated carbon steel Thermodynamics and Kinetics of Corrosion The Surface Morphology AFM studies Spectral Measurements FTIR of PAA in coat iii
44 44 45 48 51
3.4 3.4.1 3.4.2 3.4.3 3.4.4 3.5 3.6 3.6.1 3.6.2 3.6.3 3.7
Corrosion Protectiveness Study Corrosion Protection of C.S by SiC NPs coating Corrosion Protection of C.S by ZrO2 NPs coating Corrosion Protection of C.S by Al2O3 NPs coating General comparison between different coated and protection methods Cyclic Potentiodynamic Curves The Effect of Polyacrylic Acid (PAA) on the plating Corrosion Protection of C.S coated by ZrO2 & PAA Corrosion Protection of C.S coated by SiC & PAA Corrosion Protection of C.S coated by Al2O3 & PAA General Comparison of Protection Coated
53 54 59 64 67 69 70 71 76 82 88
Chapter Four - Conclusion and Further suggest 4.1 4.2
Conclusion Further Suggest References Appendix
92 93 94 103 ملخص البحث
iv
Tables List NO.
NO. of Table
Name of Table
1 2 3 4 5
(1.1) (2.1) (2.2) (2.3) (3.1)
6
(3.2)
7
(3.3)
8
(3.4)
9
(3.5)
10
(3.6)
11
(3.7)
12
(3.8)
13
(3.9)
14
(3.10)
15
(3.11)
16
(3.12)
17
(3.13)
18
(3.14)
Corrosion Types. Chemical composition for C.S. Chemical materials. The instruments used in this study. Corrosion parameter of uncoated C.S alloy in 3.5% NaCl at different Temperatures. The thermodynamic parameter at different temperatures for uncoated C.S in 3.5% NaCl solution. Corrosion kinetic parameter for C.S coated with SiC NPs alloys in 3.5% NaCl at different times. Corrosion kinetic parameter C.S coated with SiC NPs in 3.5% NaCl at different temperatures. The thermodynamic parameter at different temperatures for C.S coated with SiC in 3.5% NaCl solution. Corrosion kinetic parameters for C.S coated with ZrO2 in 3.5% NaCl at different times at 298K. Corrosion kinetic parameters C.S coated with ZrO2 alloys in 3.5% NaCl at different temperatures. The thermodynamic parameter at different temperatures for C.S coated with ZrO2 in 3.5% NaCl solution. Corrosion kinetic parameters for C.S coated with Al2O3 in 3.5% NaCl at different times at 298K. Corrosion kinetic parameters Carbon Steel coated with Al2O3 alloys in 3.5% NaCl at different temperatures. The thermodynamic parameter at different temperatures for C.S coated with Al2O3 in 3.5% NaCl solution. The thermometric and kinetic parameter comparison between uncoated and coated C.S with different NPs. Corrosion kinetic parameters for coated Carbon Steel by ZrO2 in presence of PAA at different conc. in 3.5% NaCl at the temperatures range (298-328)K. The thermodynamic parameter at different temperatures for v
19
(3.15)
20
(3.16)
21
(3.17)
22
(3.18)
C.S coated by ZrO2 in presence PAA in different concentration in 3.5% NaCl . Corrosion kinetic parameters for the corrosion of coated Carbon Steel with SiC in presence of different PAA% in 3.5% NaCl at the temperatures range (298-328)K. The thermodynamic parameter at different temperatures for C.S coated by SiC in presence PAA in different concentration in 3.5% NaCl . Corrosion kinetic parameters for the corrosion of C.S Steel with Al2O3 in presence of different PAA% in 3.5% NaCl at the temperatures range (298-328)K. The thermodynamic and kinetic parameters at different temperatures for C.S coated by Al2O3 in presence PAA in different concentration in 3.5% NaCl .
vi
Figures List No. 1 2
No. Of Fig. (1.1) (1.2)
3
(1.3)
4 5
(1.4) (1.5)
6
(1.6)
7
(1.7)
8
(1.8)
9
(1.9)
10
(1.10)
11
(1.11)
12
(1.12)
13 14 15 16 17 18 19 20 21 22
(1.13) (1.14) (1.15) (2.1) (2.2) (2.3) (2.4) (2.5) (2.6) (2.7)
23
(3.1)
Name Of Figure Mylius cell. Activation-polarization curve of a hydrogen electrode. Current vs. overpotential polarization plot of the ferric/ferrous ion reaction on palladium showing both the anodic and cathodic branches of the resultant current behavior. Concentration polarization during hydrogen reduction. Combined polarization. Polarization curves for anode and cathode reactions showing contributions for activation polarization, η A, concentration polarization ηC, and resistance polarization ηR. Experimental polarization curves for iron immersed in hydrochloric acid of various concentrations. Polarization Tafel plot. The autocatalytic process occurring in a corrosion pit Anodic control, cathodic control, mixed control, and ohmic control in a corrosion process. Schematic Electrophoretic Deposition mechanism. Schematic illustration of structural dimensionally of nanomaterials with expected properties. Crystalline structure of Alumina. Crystalline structure of Silicon Carbide. Crystalline structure of Zirconium dioxide. Set up the corrosion cell and three electrodes. Complete system set up for polarization measurements. Carbon Steel samples. Mixed the emulsion solution by Ultrasonic. Complete system of EPD technique. The C.S specimens coated by using EPD technique. Schematic illustration of an Atomic Force Microscope (AFM) The polarization curves of uncoated carbon steel with different temperatures. vii
24 25
(3.2) (3.3)
26
(3.4)
27
(3.5)
28
(3.6)
29
(3.7)
30
(3.8)
31
(3.9)
32 33 34 35
(3.10) (3.11) (3.12) (3.13)
36
(3.14)
37
(3.15)
38
(3.16)
39 40
(3.17) (3.18)
41
(3.19)
42
(3.20)
43
(3.21)
44 45
(3.22) (3.23)
Arrhenius plot,logicorr Vs 1/T for uncoated C.S in 3.5% NaCl. Plot of -∆G Vs T for uncoated C.S in 3.5% NaCl. 2D and 3D views of AFM image of SiC without PAA applied on carbon steel. 2D and 3D views of AFM image of SiC with PAA applied on carbon steel 2D and 3D views of AFM image of ZrO2 without PAA applied on carbon steel. 2D and 3D views of AFM image of ZrO2 with PAA applied on carbon steel. 2D and 3D views of AFM image of Al2O3 without PAA applied on carbon steel. 2D and 3D views of AFM image of Al2O3 with PAA applied on carbon steel. FT-IR spectra of PAA. FT-IR spectra of SiC deposition on C.S in presence PAA. FT-IR spectra of ZrO2 deposition on C.S in presence PAA. FT-IR spectra of Al2O3 deposition on C.S in presence PAA. The relationship between PE% and times for coated C.S by SiC NPs at 298K. Polarization curves for C.S coated with SiC at different temperatures as compared with the polarization curves of uncoated C.S. Effect of temperatures on the corrosion potential (Ecorr) of C.S coated with SiC NPs. Arrhenius Plot, coated C.S with SiC NPs in 3.5% NaCl. Plot of -∆G Vs T for C.S coated with SiC in 3.5% NaCl. Relationship between PE% and times (min) for coated C.S by ZrO2 at 298K. Polarization curves of carbon steel coated with ZrO 2 in different temperatures and compared with the polarization curves of uncoated C.S . Effect of temperature on the corrosion potential (Ecorr) of C.S coated with ZrO2 NPs in 3.5% NaCl. Plot of logicorr Vs 1/T for C.S coated with ZrO2 in 3.5% NaCl. Plot of -∆G Vs T for C.S coated with ZrO2 in 3.5% NaCl. viii
46
(3.24)
47
(3.25)
48
(3.26)
49
(3.27)
50
(3.28)
51
(3.29)
52
(3.30)
53
(3.31)
54
(3.32)
55
(3.33)
56
(3.34)
57
(3.35)
58
(3.36)
59
(3.37)
60
(3.38)
61
(3.39)
Relationship between PE% and times (min) for coated C.S by Al2O3 NPs at 298K. Polarization curves of carbon steel coated with Al2O3 in different temperatures as compared with the polarization curves of uncoated C.S. Plot of logIcorr Vs 1/T for C.S coated with Al 2O3 in 3.5% NaCl . Plot of -∆G Vs T for C.S coated with Al2O3 in 3.5% NaCl. The relation between protection efficiency (PE%) and temperature for coated C.S with different NPs. The relation between corrosion current density (i corr) and temperature for coated C.S with different NPs Schematic of a polarization curve showing critical potentials and metastable pitting region. Cyclic polarization curves of carbon steel in artificial 3.5%NaCl at 298K for uncoated vs coated C.S by a) SiC NPs, b) ZrO2, c) Al2O3 and d) all NPs. Relation between thickness (µm) and concentrations of PPA coating by ZrO2 and PAA at 5 min. Polarization curves for coated Carbon Steel by ZrO2 NPs in 3.5% NaCl in the presence of PAA a)added 0.1% of PAA , b) added 0.25%, c) added 0.5% and d) added 1%. Protection efficiency Vs. PAA % for C.S coated by ZrO2 in 3.5% NaCl . Plot of logicorr Vs 1/T for the corrosion of C.S coated by ZrO2 at presence PAA in different conc. in 3.5% NaCl . ∆G Vs. T for the corrosion of coated C.S by ZrO2 in presence of PAA in different conc. in 3.5% NaCl. Relation between thickness and PAA% during (5) minutes time of coating by SiC. Polarization curves for coated Carbon Steel with SiC NPs in 3.5% NaCl in the presence of PAA a) added 0.1% of PAA, b) added 0.25%, c) added 0.5% and d) added 1%. Protection efficincy Vs. PAA% for the corrosion of coated C.S with SiC in 3.5% NaCl . ix
62
(3.40)
63
(3.41)
64
(3.42)
65
(3.43)
66
(3.44)
67
(3.45)
68
(3.46)
69
(3.47)
70
(3.48)
71
(3.49)
72
(3.50)
73
(3.51)
74
(3.52)
∆G Vs. T for the corrosion of coated C.S by SiC in presence of different PAA& in 3.5% NaCl. Variation of the Gibbs free energies (ΔG) with temperatures for coated the corrosion of C.S by SiC in presence PAA in 3.5% NaCl. logicorr Vs 1/T for the corrosion for Carbon steel coated by SiC in presence different PAA% in 3.5% NaCl. Relation between thickness and PPA% after (6) minutes coating time with Al2O3. Polarization curves for coated Carbon Steel by Al 2O3 NPs in 3.5% NaCl in presence of PAA a)added 0.1% of PAA , b) added 0.25%, c) added 0.5% and d) added 1%. Protection efficiency Vs. PAA% for C.S coated by Al 2O3 C.S in 3.5% NaCl . ∆G Vs. T for coated C.S by Al2O3 at presence of different PAA% in 3.5% NaCl. logicorr Vs 1/T for Carbon steel coated by Al2O3 in presence of different PAA% in 3.5% NaCl. Unprotected alloy in comparison with the coated protection types at 298 K. Relationships between the protection efficiencies (PE%) of C.S coated with SiC NPs , and temperature (T). Relationships between the protection efficiencies (PE%) of C.S coated with ZrO2 NPs , and temperature (T). Relationships between the protection efficiencies (PE%) of C.S coated with Al2O3 NPs , and temperature (T). The comparison between PE% for C.S alloys after protected by different NPs at 298K.
x
Symbols List SYMBOLS
MEANING
SCC OCP LPR EIS C.R ɳ R.N Hads E Eo Eo ia ic io iapp ηT ηc ηR ηA I
Stress Corrosion Cracking Open Circuit Potential Linear Polarization Resistance Electrochemical impedance spectroscopy Corrosion Rate Overvoltage Reaction Number Hydrogen atoms adsorbed on metal surface Electrode Potential (the half-cell potential) The standard half-cell potential Electrode potential for zero current flow The anodic current density A.cm-2 The cathodic current density A.cm-2 Exchange current density A.cm-2 The applied current density A.cm-2 Total overvoltage. Concentration polarization. The resistance polarization Activation polarization The current in (mA .cm-2) Symmetry factor
R n T F ba bc
Gas constant (J.mol-1.K-1) Equivalent electron Temperature in K Faradays constant (C.mol-1) Anodic Tafel constant (V.decade-1) Cathodic Tafel constant (V.decade-1) Corrosion current density (A.cm-2) Corrosion potential (mV) Penetration loss The limiting diffusion current density The diffusion coefficient of the reaction ions Protection efficiency percentage
icorr Ecorr P.L iL D PE%
xi
aoxid ared R icorr(uncoated.) icorr(coated.) PVD CVD EPD 0-D 1-D 2-D 3-D D.C Ζ RE WE CE Wt Mwt
V N C.S nm mV μA /cm2 g/m2 d mm/y NPs W min L r d W.L
The activity of oxidized species The activity of reduced species The resistance in ohms(Ω) The corrosion current density without coated (A.cm-2) The corrosion current density with coated (A.cm-2) Physical Vapor Deposition Chemical Vapor Deposition Electrophoretic Deposition Zero dimension One dimension Two dimension Three dimension Direct current Zeta potential Reference electrode Working electrode Counter electrode Weight of the material (g). Molecular weight of the material (g/mol). Density of the material (g/cm3). The required volume (ml). Number of moles (mol). Carbon Steel Nanometer Mili volt Micro amper per square centimeter Gram per meter in day Millimeter per year Nanoparticles Watt Minutes Liter Radius of carbon steel Thickness of nanoparticles coated Weight Loss xii
P.L PAA SiC V Al2O3 ZrO2 Tm Ti AE NPs RP P% AFM FTIR
Penetration Loss Polyacrylic acid Silicon Carbide Volume of nanoparticles coated Alumina Zirconium Oxide Maximum temperature Initial temperature Auxiliary electrode Nanoparticles Polarization resistance Porosity percentage Atomic Force Microscope Fourier Transform Infrared Spectroscopy
xiii
Introduction
Chapter One
Introduction
Chapter One
Introduction 1.1 Corrosion Corrosion is defined as the destruction or deterioration and consequent loss of metals or alloys through chemical or electrochemical attack by the surrounding environment. The primary factors that initiate corrosion on metals are atmospheric, air, water and also conducting surface of the metal. Egs: Rusting of iron, green scales are formed on copper vessels Corrosion of metallic materials can be divided into two main groups. a. Wet corrosion, where the corrosive environment is water with dissolved species. The liquid is an electrolyte and the process is typically electrochemical. b. Dry corrosion, where the corrosive environment is a dry gas. Dry corrosion is also frequently called chemical corrosion [1,2]. Electrochemical corrosion is the dissolution of a metal through the oxidation process. Oxidation and reduction chemical reactions occur simultaneously and are interdependent. Corrosion only occurs at the site of the oxidation reaction. Oxidation involves the loss of electrons; reduction involves the gain of electrons. The electron transfer between oxidation and reduction reaction site establishes the electrical current required for electrochemical corrosion [3].
1.2 Forms of Corrosion The main forms of corrosion which grouped according to appearance of the corroded surface are shown in table (1.1)
No. 1
Type Uniform (General) corrosion
Table (1.1): Corrosion types. Characteristic All areas of the metal corrode at the same (or similar) rate.
[4]
1
Image[5]
Chapter One 2
Localized corrosion
5
Erosion corrosion
Introduction
Certain areas of the metal surface corrode at higher [4] rate than others due to “heterogeneities” in the metal. The environment or in the geometry of the structure as a whole. Attack can range from being slightly localized to pitting. 3 Highly localized attack at Pitting corrosion specific area resulting in [4] small pits that penetrate into the metal and may lead to perforation. 4 Selective One component of an alloy dissolution (usually the most active) is corrosion selectively removed from [4] an alloy.
[4]
6
Stress Corrosion Cracking (SCC) [2]
7
Galvanic Corrosion [5] .
Localized attack or fracture due to the synergistic action of a mechanical factor and corrosion. It is defined as crack formation due to simultaneous effects of static tensile stresses and corrosion. The tensile stresses may originate from external load, centrifugal forces or temperature changes, or they may be internal stresses induced by cold working, welding or heat treatment. It occurs when two metals with different electrochemical potentials are in contact in the same solution.
2
Chapter One
Introduction
1.3 Corrosion Measurement Techniques Corrosion measurement is the quantitative method by the practice of measuring the corrosivity of process stream conditions by the use of "probes" which are inserted into the process stream and which are continuously exposed to the process stream condition [6]. A wide variety of corrosion measurement techniques exists, including:
1.3.1 Polarization Curves Polarization is the change in the potential of an electrode from the equilibrium value, an important research tool in investigations of a variety of electrochemical phenomenon. Such measurements permit studies of the reaction mechanism and the kinetics of corrosion phenomenon and metal deposition. In spite of their wide applicability and extensive use, considerable uncertainty in the interpretation of polarization measurements still exists. Some of the uncertainties include the proper method of plotting data and the correct interpretation of "breaks" in polarization curves. Abrupt changes in slope of overvoltage vs. log current have been given considerable significance in the past few years [7].
1.3.2 Linear Polarization Resistance The LPR technique is based on complex electro-chemical theory. For purposes of industrial measurement applications, it is simplified to a very basic concept. In fundamental terms, a small voltage (or polarization potential) is applied to an electrode in solution. The current needed to maintain a specific voltage shift (typically 10 mV) is directly related to the corrosion on the surface of the electrode in the solution. By measuring the current, a corrosion rate can be derived[8].
1.3.3 Open Circuit Potential Decay One of the simplest electrochemical tests available, measuring the open circuit potential (OCP), also referred to as the equilibrium potential or corrosion potential. The OCP is by definition the electrical potential difference between two conductors in specific electrolyte with zero current flow between them. Monitoring OCP over time can provide vital information about the system being studied. Providing information about when system has reached a
3
Chapter One
Introduction
steady state and when transitions between different states, such as a passive and transpassive behavior will occur. Properties of the oxide formed on the test electrode can be evaluated by monitoring of the OCP which typically results in a positive shift in the OCP, inductive of the formation of a passive film (i,e.a surface oxide protecting the metal from further oxidation) . The formation of porous oxide films, which can hinder but not prevent further oxidation, typically results in a decrease in the OCP [9].
1.3.4 Electrochemical Impedance Measurement Electrochemical impedance spectroscopy (EIS), like LPR, uses the polarization of electrodes to measure corrosion rates. This is by analogy to conventional spectroscopy, in which the system displays a response at a characteristic frequency to an applied perturbation; plots of imaginary part of the impedance vs. the logarithm of the frequency produce a peak [10,11]. The applied frequency is about 0.1 Hz to 100 kHz with more than one frequency required to obtain useful data. Typically, two frequencies are used; however, full frequency measurements may be used, producing the best data to identify the corrosion processes taking place [12].
1.3.5 Electrochemical Noise Measurement The electrochemical noise method measures changes in the electric potential and current between freely corroding electrodes. Highly sensitive instrumentation is required as the fluctuations are on such a small scale. Three electrodes are needed to simultaneously measure both the potential and current noise. Different corrosion processes will produce different noise signatures. This data may be used to identify pit initiation and growth before visible detection [12].
1.3.6 Weight Loss Measurement The simplest way of measuring the corrosion rate of a metal is to expose the sample to the test medium (e.g. seawater) and measure the loss of weight of the material as a function of time. Although these tests are simple, there is no simple way to extrapolate the results to predict the lifetime of the system under investigation. Moreover, some corrosion processes occur with no significant mass change (e.g. pitting corrosion) making them difficult to detect by gravimetric methods[13]. The calculated corrosion rate (C.R) obtained from plotted ∆Wt./(g) against time/min.. 4
Chapter One
Introduction
1.3.7 Thermometric method (Mylius) Measurement Mylius made use of the thermometric method for determining the corrosion rates of metal alloys. Applied the Mylius method as a rapid technique for investigation of certain corrosion protection efficiency. According to this method , a piece of metal of specificed area is dropped into a definite volume of corrosion solution (e.g. hydrochloric acid) and the variation of the temperature of the thermally isolated system is followed as a function of time as shown in figure (1.1). The temperature rises during the course of the reaction to attain a maximum value [14]. The reaction number R.N. is defined as: 𝑇𝑚−𝑇𝑖 o C.min-1 𝑡
𝑅𝑒𝑎𝑐𝑡𝑖𝑜𝑛 𝑁𝑢𝑚𝑏𝑒𝑟 (𝑅. 𝑁) =
…….(1.1)
Where Tm and Ti are the maximum and initial temperatures respectively, and t is time taken to reach Tm. Thermometer
Solution
Sample
Fig. 1.1- mylius cell.
1.4 Basic of Polarization Curves Electrochemical polarization (usually refer to simply as “polarization”) is the change in electrode potential due to the flow of a current [15]. There are three types of polarization: 1. Activation polarization is polarization caused by a slow electrode reaction.
5
Chapter One
Introduction
2. Concentration polarization is polarization caused by concentration changes in reactants or products near an electrode surface. 3. Ohmic polarization is polarization caused by IR drops in solution or across surface films, such as oxides (or salts). The degree of polarization is defined as the overvoltage (or over potential) ɳ given by the following equation: ɳ= E – Eo………… (1.2) Where E is the electrode potential for some condition of current flow (the half-cell potential) and Eo is the electrode potential for zero current flow (also called the open-circuit potential, corrosion potential, or rest potential).Note that the electrode potential of zero current flow Eo should not be confused with the standard electrode potential Eo, which plays a prominent role in corrosion thermodynamics [15]. Anodic polarization is the displacement of the electrode potential in the positive direction so that the electrode acts more anodic [16, 17], this Polarization may occur at the activation polarization only. Cathodic polarization is the displacement of the electrode potential in the negative direction that the electrode acts more cathodic [16, 17], this Polarization may occur at the activation and concentration polarizations. The current applied to cause the departure from equilibrium is the net rate of reaction thus: iapp=Σia - Σic ........ (1.3) Where: ia , ic and iapp are the anodic, cathodic and applied current density respectively.
l.4.1 Activation Polarization When some steps in the half-cell reaction control the rate of charge (electron) flow, the reaction is said to be under activation or charge transfer control [18]. The most important example is that hydrogen ion reduction at a cathode [19]. 2H+ + 2e-
H2........... (1.4)
6
Chapter One
Introduction
The corresponding polarization term is called hydrogen overvoltage. Activation polarization refers to electrochemical reactions which are controlled by a slow step in the reactions sequence .The species must first be adsorbed or attached to the surface before the reaction can proceed according to (step 1 in figure (1.2)). Following this, electron transfer (step 2) must occur, resulting in a reduction of the species [8]. 2H+ +2e-
2Hads ............ (1.5)
Where (Hads) represents hydrogen atom adsorbed on the metal surface. This relatively rapid reaction (1.4) is followed by a combination of adsorbed hydrogen atoms to form hydrogen molecules as shown in (step 3) H2 ……...(1.6)
2Hads
This reaction is relatively slow, and its rate determines the value of hydrogen over voltage on platinum [19]. Two hydrogen molecules then combine to form a bubble of hydrogen gas (step 4) as shown in Figure (1.2). The speed of reaction of hydrogen ions will be controlled by the slowest of these steps [20,21] . The controlling slow step of H+ discharge is not always the same but varies with metal current density and environment [19-21]. Solution 2 3
4
2 3
Fig. 1.2- Activation-polarization curve of a hydrogen electrode.
The following theory explains the basic mathematics that may then be used to extract exchange current density from the results obtained. A general 7
Chapter One
Introduction
representation of the polarization of an electrode supporting one specific reaction is given in the Butler-Volmer equation (1.7) that quantifies the kinetics of the electrochemical corrosion [22]. 2.303 ( 𝐸−𝐸𝑐𝑜𝑟𝑟 )
iapp = icorr { exp[
𝑏𝑐
2.303 ( 𝐸−𝐸𝑐𝑜𝑟𝑟 )
] - exp[
𝑏𝑎
] } ….. (1.7)
Where: iapp , icorr , bc , ba, E and Ecorr are applied current density, corrosion current density, the anodic, cathodic Tafel constant, Electrode Potential and Corrosion potential respectively. The exchange current density is a fundamental characteristic that can be defined as the rate of oxidation or reduction of the electrode at equilibrium expressed in terms of current. The presence of two polarization branches in a single reaction expressed in equation is illustrated in the following figure (1.3) for the polarization of a palladium electrode immersed in a solution containing similar concentrations of ferric (Fe3+) and ferrous (Fe2+) ions with a completely reversible reaction (1.8) : Fe+2 ……..(1.8)
Fe+3 + e-
Fig. 1.3- Current vs. overpotential polarization plot of the ferric/ferrous ion reaction on palladium showing both the anodic and cathodic branches of the resultant current behavior.
8
Chapter One
Introduction
When c is cathodic, i.e. negative, the second term in the Butler-Volmer equation becomes negligible and the cathodic current density (ic) can be expressed by a simpler equation (1.9) and its logarithm: 2.303 ( 𝐸−𝐸𝑐𝑜𝑟𝑟 )
For cathodic reaction ic = icorr exp[ 𝜂𝐶 =
2.303𝑅𝑇 𝛼𝑛𝐹
𝛽𝑐
] ………. (1.9)
𝑖
log ( 𝑐 ) ……… (1.10) 𝑖𝑜
bc =−2.303
𝑅𝑇 𝛼𝑛𝐹
………….(1.11)
Where ηC, α , R, n, T, F, ia, and ic, are concentration polarization, symmetry factor, gas constant, equivalent electron, temperature, Faradays constant. anodic ,and cathodic current density respectively, i o exchange current density. Similarly, when a is anodic, i.e. positive, the first term in the ButlerVolmer equation becomes negligible and the anodic current density (i a) can be expressed by equation and its logarithm, with ba obtained by plotting a vs. logi. 2.303 ( 𝐸−𝐸𝑐𝑜𝑟𝑟 )
For anodic reaction ia = icorr exp[ 𝜂𝐴 =
2.303𝑅𝑇 𝛼𝑛𝐹
ba =2.303
𝛽𝑎
] ……… (1.12)
𝑖
log ( 𝑎 ) ……… (1.13) 𝑖𝑜
𝑅𝑇 𝛼𝑛𝐹
………….(1.14)
Where ηA is activation polarization, ba and bc are constants of a given metal environment and are both dependent on temperature. The exchange current density io represents the current density equivalent to the equal forward and reverse reactions at the electrode at equilibrium [19].
1.4.2 Concentration Polarization Concentration polarization refers to electrochemical reactions which are controlled by the diffusion in the electrolyte. It is the slowing down of a reaction due to an insufficiency of the desired species or an excess of unwanted species at the electrode. This type of polarization occurs at the cathode when reaction rate or the cathode current is so large that the substance being reduced cannot reach the cathode at a sufficiently rapid rate.
9
Chapter One
Introduction
Since the rate of reaction is determined by the slowest step, the diffusion rate will be the rate determining step [19]. For the case of hydrogen evolution, any change in the system which increases the diffusion rate will decrease the effects of concentration polarization and hence increases reaction rate. Thus, increasing the velocity of agitation of the corrosive media will increase rate only if the cathodic process is controlled by concentration polarization agitation will have no influence on corrosion rate as shown in figure (1.4) [19].
Fig. 1.4- Concentration polarization during hydrogen reduction.
At very high reduction rate, the region adjacent to the electrode surface will become depleted of ions. If the reduction rate is increased further, a limiting rate will be reached which is determined by the diffusion rate of ions to the electrode surface. This limited rate is the limiting diffusion current density iL. It represents the maximum rate of reduction possible for a given system, the expressing of this parameter is [19,23]. iL =
𝐷𝑛𝐹𝐶𝑏 𝛿
………….. (1.15)
Where iL is the limiting diffusion current density, D is the diffusion coefficient of the reaction ions, Cb is the concentration of the reacting ions in the bulk solution, and δ is the thickness of the diffusion layer. Combining the laws governing diffusion with Nernst equation yield [20, 21]. 𝑅𝑇
𝑎𝑜𝑥𝑖𝑑
𝑛𝐹
𝑎𝑟𝑒𝑑
E=Eo+2.303 1og
10
................(1.16)
Chapter One
Introduction
Where E is the half-cell potential, Eo the standard half-cell potential, n is the number of electrons transferred, aoxid and ared are the concentrations of oxidized and reduced species. Equation (1.16) be developed as equation (1.17) [19]. Eo - E= ηC=
2.303𝑅𝑇 𝑛𝐹
𝑖
log (1- ) ………..(1.17) 𝑖𝐿
1.4.3. Combined (Mixed) Polarization Both activation and concentration polarization usually occur at an electrode. At low reaction rates activation polarization usually controls, while at higher reaction rates concentration polarization becomes controlling [24]. The total polarization of an electrode is the sum contributions of activation polarization and concentration polarization equation (1.18) figure (1.5) shows the combined polarization. [18,25] ηT= ηA + ηc ............... (1.18) Where, ηT : total cathodic overvoltage. ηA : activation polarization. ηC : concentration polarization .
Fig. 1.5- Combined polarization.
11
Chapter One
Introduction
1.4.4 Resistance Polarization An additional overpotential, the resistance polarization ηR, is required to overcome the ohmic resistance of the electrolyte and any insoluble product film on the surface of the metal. This overpotential is defined by Ohms law as [26]. ηR =IR ………… (1.19) Where I is the current in (mA) and R is the resistance, in ohms (Ω), of the electrolyte path between anode and cathode and is directly proportional to the path length. This polarization refers to electrochemical reaction, which works under conditions lead to drop in potential of the electrolyte surrounding the electrode or through the reaction product. In typically corrosion processes, the anode and cathode are immediately adjacent to each other so that resistance polarization makes only a minor contribution to the overall polarization, as indicated in figure (1.6).
Fig. 1.6 - Polarization curves for anode and cathode reactions showing contributions for activation polarization, ηA, concentration polarization ηC, and resistance polarization ηR
At the corrosion potential, the rate of hydrogen evolution is equal to the rate of the metal dissolution, and this point corresponds to the corrosion rate of the system expressed in terms of current density. Tafel constants must be calculated from both the anodic and cathodic portions of the Tafel plot. The unit of the Tafel constants is V/decade.
12
Chapter One
Introduction
1.5 Tafel extrapolation The Tafel extrapolation method can be used to determine the corrosion rate of a metal when metallic dissolution is under activation control. The most common application is for metals immersed in de-aerated acid solutions for which the anodic reaction is M
Mn+ + ne-……….. (1.20)
and the cathodic reaction . 2H+ + 2e-
H2…………… (1.21)
De-aeration of the solution restricts the cathodic reaction io hydrogen evolution alone, rather than also including the cathodic reduction of oxygen. Also in de-aerated acid solutions oxide films initially present on the metal surface are dissolved by the acid solution route to attainment of the steadystate, open-circuit potential. Thus, the sole anodic reaction is the dissolution of the bare metal surface. Figure (1.7) shows experimental anodic and cathodic polarization curves for iron immersed in HCl solutions of various concentrations [27]. These curves were obtained after a steady-state, open-circuit potential had been first obtained. If a well-defined Tafel region exists, as in figure (1.7), the anodic and cathodic Tafel regions can be extrapolated back to zero overvoltage. The intersection of the anodic and cathodic Tafel slopes gives the corrosion potential Ecorr and the corrosion current density icorr, as indicated in figure (1.7). The basis for the Tafel extrapolation method stems from Eq. (1.7). When E= Ecorr, then i = icorr. The contribution of the back reaction to the forward reaction is usually negligible for overvoltages ranging from 60 to 120 mV. That is, Linear Tafel regions are usually observed for overvoltages 59-120 mV away from the opencircuit potential.
13
Chapter One
Introduction
Fig. 1.7- Experimental polarization curves for iron immersed in hydrochloric acid of various concentrations (which are indicated on the figure) [27].
A typical corrosion plot consists of an anodic and a cathodic branch, the intersection of these branches can be projected on the X and Y-axes to give us the icorr and the Ecorr values as shown in figure (1.8).
Fig. 1.8- polarization Tafel plot.
14
Chapter One
Introduction
1.6 Cyclic Potentiodynamic Curves The most dangerous type of corrosion is the pitting corrosion because always the material body seems in good appearance, but in fact, it is suffering from pitting defects, so pitting is defined as “localized accelerated dissolution of metals that occurs as a result of a breakdown of the protective passive film on the metal/ alloy surface”. In an aggressive environment, typically containing halide ions, pits initiate and grow in an autocatalytic manner, where the local environment within the pits becomes more aggressive because of the decrease in pH and increase in chloride concentration [28]. The critical pitting potential will, in general, decrease with concentration of chloride ions, but will increase with the concentration of inhibiting oxy – anions such as, OH-1, SO-24 ,NO-3 and CrO-24 [24]. The mechanism of pitting corrosion is illustrated schematically in Figure (1.9). It shows a metal M is being pitted by an aerated sodium chloride solution, rapid dissolution occurs within the pit, while oxygen reduction takes place on adjacent surfaces. This process is self-stimulating and self -propagating. The rapid dissolution of metal within the pit tends to produce an excess of positive charge in this area, resulting in the migration of chloride ions to maintain electroneutrality. Thus, in the pit, there is a high concentration of MCl and, as a result of hydrolysis, a high concentration of hydrogen ions. Both hydrogen and chloride ions stimulate the dissolution of most metal and alloys, and the entire process accelerates with time [29].
Fig. 1.9 - The autocatalytic process occurring in a corrosion pit.
15
Chapter One
Introduction
1.7 Corrosion Protection and Control Corrosion of a metal is a natural spontaneous process, by which metal is converted into a more stable compound so that corrosion control is more realistic than corrosion prevention. The method used to control corrosion is as follows:
1.7.1 Cathodic and Anodic Control Corrosion reactions can be classified as being under anodic, cathodic, or mixed control. When polarization occurs mostly at the local anodes, the corrosion reaction is said to be under anodic control. This situation is illustrated in figure (1.10)(a), in which small changes in the current density result in larger changes in the anode potential rather than in the cathode potential. An experimental example is passivation of various metals by chromate inhibitors. When polarization occurs mostly at the local cathodes, as shown in figure (1.10)(b), the corrosion reaction is under cathodic control. An example is the corrosion of iron in natural waters, where the cathodic reaction given by occurs under diffusion control.
Fig. 1.10- (a) Anodic control, (b) cathodic control, (c) mixed control, and (d) ohmic control in a corrosion process.
16
Chapter One
Introduction
It is common for polarization to occur to some degree at both local anodes and cathodes, in which case the corrosion process is under mixed control, as in figure (1.10)(c). If there is a large IR drop between local anodes and local cathodes, as in figure (1.10)(d), then the corrosion reaction is under resistance or ohmic control. Examples include the corrosion of metals in organic media, or where there is a porous insulating coating covering a metal surface [17], or in narrow crevices or stress-corrosion cracks, within which IR drops can exist. Most corrosion reactions are under cathodic or mixed control, and anodic control is less common.
1.7.2 Corrosion Inhibitors Corrosion of metallic surfaces can be reduced or controlled by the addition of chemical compounds to the corrodent. This form of corrosion control is called inhibition and the compounds added are known as corrosion inhibitors. These inhibitors will reduce the rate of either anodic oxidation or cathodic reduction, or both. The inhibitors themselves form a protective film on the surface of the metal. It has been postulated that the inhibitors are adsorbed into the metal surface either by physical adsorption or chemosorption [12]. Physical adsorption is the result of electrostatic attractive forces between the organic ions and the electrically charged metal surface. Chemosorption is the transfer, or sharing of the inhibitor molecule's charge to the metal surface, forming a coordinate-type bond. The adsorbed inhibitor reduces the corrosion rate of the metal surface either by retarding the anodic dissolution reaction of the metal, or by the cathodic evolution of hydrogen, or both [12]. Inhibitors can be used at pH values of acid from near neutral to alkaline. They can be classified in many different ways according to: 1. Their chemical nature (organic or inorganic substances) 2. Their characteristics (oxidizing or nonoxidizing compounds) 3. Their technical field of application (pickling, descaling, acid cleaning cooling water systems, and the like).
1.7.3 Protective Coatings Corrosion of metal can be controlled by isolating them from the corrosive atmosphere. This can be done by covering the metal (base metal) with a layer of another metal or nanomaterial compounds. Tangents are drawn to the anodic and cathodic regions of the Tafel curve, the intersection of these provide the
17
Chapter One
Introduction
values of Ecorr and icorr when projected on the corresponding axes Protection efficiency is calculated by eq. (1.22) [30]. PE% =
𝑖𝑐𝑜𝑟𝑟 (𝑢𝑛𝑐𝑜𝑎𝑡𝑒𝑑) − 𝑖𝑐𝑜𝑟𝑟 ( 𝑐𝑜𝑎𝑡𝑒𝑑) 𝑖𝑐𝑜𝑟𝑟 (𝑢𝑛𝑐𝑜𝑎𝑡𝑐𝑑)
* 100 ......... (1.22).
where icorr(uncoated) and icorr(coated) are corrosion current densities without and with coated, respectively determined by extrapolation of cathodic and anodic Tafel lines. There are several methods used for surface modification of materials. The following techniques are few used for applying coating on metals: The Principal types of coatingapplied on the metal surface are: a. Electroplating: metals and alloys can be plated on a conducted substrate that acts as a cathode. Ceramics and plastics need to be treated before they can be electroplated. The metal cations are suspended in solution and reduced by an external current passing through the electrolyte. The cation concentration, both temperature and current density determine the deposition rate [31]. b. Electroless plating: the process of deposition of metal ions from electrolyte solution onto the substrate, when no electric current is involved and the plating is a result of chemical reactions occurring on the surface of the substrate [32]. c. Hot dipping: designates the coating application process of immersing a metal substrate in a molten metal bath, which is usually aluminum, zinc, tin, or lead. Since the applied coating consists of a molten metal, the melting temperature of the metal coating should be relatively low [12]. d. Physical Vapor Deposition (PVD): the process involving vaporization of the coating material in vacuum, transportation of the vapor to the substrate and condensation of the vapor on the substrate surface [33]. The process proceeds atomistic ally and mostly involves no chemical reactions. The thickness of the deposits can vary from angstroms to millimeters [34].
18
Chapter One
Introduction
e. Chemical Vapor Deposition (CVD): The process, in which the coating is formed on the hot substrate surface placed in an atmosphere of a mixture of gases, as a result of chemical reaction or decomposition of the gases on the substrate material [32]. f. Thermal spraying: Deposition of the atomized metal at high temperature and delivered to the substrate surface in a high velocity gas stream [32]. g. Electrophoretic Deposition: (EPD) is a simple method for the formation of a coating on an electrode using a stable suspension in a direct current (DC) field [33]. EPD is a two-step process: (1) charged particles suspended in a liquid migrate toward an electrode under the influence of an electric field (electrophoresis) and (2) the particles deposit on the electrode, forming a relative dense and even film [35]. EPD methodology is one of a choice in application of this work and will be discussed in more details in section (1.8). h. Sol Gel: The sol gel process is a wet-chemical technique for die fabrication of materials (typically metal oxide) starting either from solution or colloidal particles to produce an integrated network (gel) [36]. Sol-Gel methods are the wide range of accessible shapes, which include fine powders, fibers, thin films, xerogels, and aerogels [37].
1.7.4 Cathodic protection Cathodic protection involves the application of a direct current (DC) from an anode through the electrolyte to the surface to be protected. This is often thought of as overcoming the corrosion currents that exist on the structure. That is not really what happens as there is no flow of electrical current (electrons) through the electrolyte. There is, of course, a flow of ionic current in the electrolytes [38]. Cathodic protection eliminates the potential differences between the anodes and cathodes on the corroding surface. A potential difference is then created between the cathodic protection anode and the structure such that the cathodic protection anode is of a more negative potential than any point on the structure surface. Thus, the structure becomes the cathode of a new corrosion cell. The
19
Chapter One
Introduction
cathodic protection anode is allowed to corrode; the structure, being the cathode, does not corrode [38].
1.7.5 Anodic protection Anodic protection is a potential-control electrochemical technique suitable for preventing corrosion of a metal in aggressive environments, such as sulfuric acid .In this technique, the metal to be protected must exhibit passivity at relatively low current density, so that the passive current density (i p) is at least one order of magnitude lower than the corrosion current density (i corr). Care must be exercise, in selecting a material that shows a wide enough passive potential range. Furthermore, anodic protection is normally used when coatings and cathodic protection methods do not provide adequate protection against corrosion [22]. Anodic protection involves passivation of the metal to be protected. A passive film forms on the surface of the metal with the application of an electrical current. Once this film is formed, it acts to protect the metal from dissolution, and the film itself is nearly insoluble in the environment which it formed. Passivation causes metals to become very non-reactive and consequently very resistant to corrosion.
1.8 Concepts of Electrophoretic Deposition Electrophoretic deposition (EPD) is a colloidal process wherein materials are shaped directly from a stable suspension by an applied electric field [39]. EPD is an effective method to fabricate thin and thick coatings on conductive substrates [40]. EPD involves two processes, one well understood (electrophoresis) [41,42] and one less so (deposition). Electrophoresis is the motion of charged particles in a suspension under the influence of an electric field. Deposition is the coagulation of particles to a dense mass [43,44]. Coagulation due to increase of electrolyte concentration around the particles [45]. Cataphoresis is positively charged particles deposit on the cathode. Anophoresis is negatively charged particles deposit on the anode [46,47].
20
Chapter One
Introduction
Electrophoresis was discovered in 1809 by Reuss of Moscow University. Many processes based on electrophoretic deposition have been described [48,49]. It was first used in a practical application in 1933 to deposit thoria particles on a platinum cathode as an emitter for electron tube applications [48], EPD has been employed for the processing of functional and composite ceramics, layered and functionally graded materials, thin films, high performance ceramic and composite coatings and biomaterials and also for the deposition of nanoparticles and carbon nanotubes to produce advanced nanostructured materials [50,51]. Electrophoretic deposition differs from electrochemical deposition in several aspects. First, the deposit by electrophoretic deposition method need not be electrically conductive. Secondly, nanosized particles in colloidal dispersions are typically stabilized by electrostatic or electrosteric mechanisms[52]. Good forming techniques should have three major capabilities: ability (1) to produce a dense and homogeneous green body, (2) to produce complicated shapes effectively and easily, and (3) to allow flexibility in microstructural manipulation [53]. Several investigations have been carried out to describe the effect of the suspension’s composition and the EPD process parameters such as pH, voltage, amount of stabilizer used, and depositon time on the yield, deposition rate [54]. These are some of different parameters affect the EPD process: 1. Parameters related to the properties of the suspensions: solvent properties, potential and conductivity, solid content in the suspension [55]. 2. Parameters related to the electrical properties of the fibers: electrical conductivity, surface charge of the fibers at working pH [55]. 3. Parameters related to the process: applied voltage, time, EPD cell configuration [56]. 4. Parameters related to the geometry of the deposition system, i.e. the distance between electrodes or the electrode surface, can affect the quality of the deposition [55].
21
Chapter One
Introduction
1.8.1 Electrophoretic Deposition mechanism Electrophoretic deposition (EPD) is a simple method for the formation of a coating on an electrode using a stable suspension in a direct current (DC) field[33,57]. Cathodic or anodic films can be obtained depending on particle charge [58]. EPD is a two-step process: shown in figure (1.11): 1. An electric field is applied between two electrodes and charged particles suspended in a suitable solvent move toward the oppositely charged electrode (electrophoresis) [55] and, 2. The particles accumulate on the deposition electrode surface forming a homogeneous film (deposition) [55]. After EPD, the films are only physically bonded to the substrate and permanent chemical adhesion must be affected by suitable heat treatment (firing or sintering) is needed to densify the deposit [55]. EPD can produce thin and thick films of very consistent thickness, even on irregularly shaped substrates, with very short deposition times [59]. It is essential to formulate stable suspensions in order to obtain dense films with homogeneous microstructures [60]. Accumulated particles then deposit due to the pressure exerted by those incoming and in the outer layers [39]. Deposition occurs only on conducting surfaces', however non conductive substrates can be infiltrated by using EPD [61].
+
-
stainless steel electrode
C.S
Fig. 1.11- Schematic Electrophoretic Deposition mechanism.
22
Chapter One
Introduction
l.8.2 Suspensions Suitable for EPD Difficulties in the EPD process can be classified into the following four categories: particles do not deposit; layers do not thicken; the quality of layers is poor; and the layers crack. These are mostly caused by problems with the method used for preparing the suspensions. Generally, suspensions suitable for the EPD process require the following: a. The particle surfaces are charged (If the particles are not charged, they do not migrate by the applied electric field). b. Particles are well dispersed (Coagulated suspensions result in low-density deposited bodies). c. Suspensions contain excess ions (Ions other than the charged particles lower the transport number of the particles. Compression of the electric double layer reduces the stability of the slurry). d. Particles have a high adhesion ability.(Binders can be added as necessary). Normal colloidal processes often involve aqueous solvents because of their lower cost and environmental load, and ease in controlling dispersion and coagulation [62-65].
l.8.3 Application of Electrophoretic Deposition EPD has been used successfully for many applications over the years, including its high versatility for application with different materials and combinations of materials. There are many application of this method: 1.8.3.1 Coatings
EPD of coatings has already gained a world - wide acceptance in industry e.g. automotive or appliance plants .Current interest in the fabrication of wear and abrasion resistant coatings is focused on the developing of metal / ceramic[54,66]. An electrophoretic deposition (EPD) method has been developed for the deposition of nanostructured films. It was shown that the stabilization and charging of the nanoparticles in suspensions [58]. 1.6.2.2. Fibre Reinforced Ceramic Matrix Composites
Electrophoretic deposition (EPD) is a simple and cost-effective method for fabrication of high-quality fibre reinforced ceramic matrix composites. In this application, EPD is used to infiltrate preforms with tight two- or threedimensional fibre architectures using nanosized ceramic particles. A recent comprehensive review article reveals the great variety of conducting and non-
23
Chapter One
Introduction
conducting fibre and matrix combinations that have been explored, including SiC, carbon, and oxide ceramic fibre architecture and silica, borosilicate glass, stainless steel, alumina, zirconia, mullite hydroxyapatite, SiC and Si 3N4 matrices [67]. 1.8.3.3 Laminated and Graded Composites
EPD has been used to fabricate ceramic laminated composites and graded materials [66]. Efforts are devoted to the development of EPD fabrication approaches for laminated ceramic composites , in particular in the system ZrO2/Al2O3 due to high fracture resistance of these structures [68].
1.8.4 Advantages of Electrophoretic Deposition Electrophoretic Deposition has several advantages over the conventional and latest deposition processes : Low cost and industrial applicability, as it involves little modification of existing electroplating technologies. EPD is a flexible, capable of rapid deposition rates (seconds to minute)[46]. The process parameters can be easily tailored to get the desired microstructure. Simple operation, as the electro deposition parameters can be easily tailored to meet the required crystal grain size, microstructure and chemistry of products. Versatility, as the process can produce a wide variety of pore free materials and coatings. Process can also be operated at room temperature and pressure. Large dimensions [69]. Ability to produce compositions unattainable by other techniques. No post deposition treatment. Metals, alloys and polymers can be deposited by using this process.
1.8.5 Disadvantages of Electrophoretic Deposition EPD coatings must be dandified after deposition, and this involves heating the coated metal implant to temperatures in excess of 800 ◦C [46].
24
Chapter One
Introduction
1.9 Nanomaterials Nanomaterial is defined as any material that has unique or novel properties due to Nano scale (1-100 nm) structuring nanomaterial exhibit interesting electrical, optical and magnetic properties in addition to high catalytic activity[70]. The photocatalytic performances mainly depend on structural dimensionality of nanomaterials. However, the structural dimensionality has a significant impact on the properties of nanomaterials show in Figure (1.12). For example, spherical NPs with zero dimensionality has a large specific surface area, resulting in a higher rate of photocatalytic decomposition of organic pollutants [71]. One-dimensional fibers or tubes make the short distance for charge carrier diffusion and therefore, they have advantages like less recombination, lightscattering properties and fabrication of self-standing nonwoven mats. Zero-and one-dimensional structures have been well developed [72]. It is well known nanosheets have two-dimensional and smooth surfaces with high adhesion [73], whereas three-dimensional quantum dotes may have high carrier mobility as a result of their interconnecting structure and can be used in environmental decontamination.
Fig. 1.12- Schematic illustration of structural dimensionally of nanomaterials with expected properties. 25
Chapter One
Introduction
Nanomaterials have a higher distortion of surface structure than bulk materials due to their inherent lattice strain. As a result, the surface modifications of NPs are more beneficial than the modification of bulk particles [74]. In the past twelve years, those nanomaterials have different toxicity profiles compared with larger materials because of their small size and also their high reactivity. Capping is the coating of one semiconductor or metal nanomaterial on the surface of another semiconductor or metal nanoparticle [75].
1.9.1 Aluminum oxide nanoparticles Aluminum oxide is a chemical compound of aluminum and oxygen with the chemical formula Al2O3 show in figure (1.13). Where there are two types of nano-Al2O3,( α-phase nano-Al2O3 and γ-phase Al2O3). α-phase Al2O3 is phase stability, high hardness, materials with high dimensional stability, it is widely used in a variety of plastics, rubber, ceramics, refractory products for reinforcement toughening, in particular, significantly to improve the ceramic density, finish, thermal fatigue resistance, fracture toughness, creep resistance and wear resistance. γ-phase nano-Al2O3 is with small size, high activity and low melting temperature, it can be used for producing synthetic sapphire with the method of thermal melting techniques; the γ -phase nano-Al2O3 with large surface area and high catalytic activity, it can be made into microporous spherical structure or honeycomb structure of catalytic materials. These kinds of structures can be excellent catalyst carriers. If used as industrial catalysts, they will be the main materials for petroleum refining, petrochemical and automotive exhaust purification. In addition, the γ -phase nano-Al2O3 can be used as analytical reagent. Alumina Nanoparticles Application:
In integrate circuit base boards
Transparent ceramics, high-pressure sodium lamps, and EP-ROM window In YAG laser crystals As cosmetic fillers Single crystal, ruby, sapphire, sapphire, and yttrium aluminum garnets
26
Chapter One
Introduction
High-strength aluminum oxide ceramic and C substrates Packaging materials, cutting tools, high purity crucible, winding axle, and furnace tubes Polishing materials, glass products, metal products, semiconductor materials Plastic, tape, and grinding belts Paint, rubber, plastic wear-resistant reinforcement, and advanced waterproof materials Catalyst, catalyst carrier, analytical reagents Vapor deposition materials, special glass, fluorescent materials, composite materials and resins
Fig. 1.13- Crystalline structure of Alumina
1.9.2 Silicon Carbide nanoparticles Silicon carbide (SiC) nanoparticles exhibit characteristics like high thermal conductivity, high stability, high purity, good wear resistance and a small thermal expansion co-efficient. These particles are also resistant to oxidation at high temperatures. Silicon belongs to Block P, Period 3 while carbon belongs to Block P, Period 2 of the periodic table. An important point to be noted about their storage is that they must be kept away from moisture, heat and stress [76]. The applications of silicon carbide nanoparticles are given below:
27
Chapter One
Introduction
As a high grade refractory material, special material for polishing abrasive, various ceramic parts, textile ceramics and high frequency ceramics Manufacture of rubber tires Manufacture of grinding material having a high hardness Making of sealing valves that withstand high temperatures Resistance heating element manufacture Used in modifying the strength of alloys High temperature spray nozzle manufacture Mirror coatings for high ultraviolet environments.
Fig. 1.14- Crystalline structure of Silicon Carbide.
1.9.3 Zirconium dioxide nanoparticles Zirconium oxide nanoparticles (ZrO2) are available in the form of nanodots, nanofluids and nanocrystals having a white surface area. They are often doped with yttrium oxide, calcium or magnesia. Zirconium is a Block D, Period 5 element and oxygen is a Block P, Period 2 element. Zirconium oxide is also known as zirconia, zirconium, zircosol and zirconic anhydride. The applications of zirconium oxide nanoparticles are given below:
28
Chapter One
Introduction
in ceramics for making ceramic pigments, porce lain glaze, etc. In making artificial jewellery. In making abrasive, insulating and fire-retarding materials. The powder exhibits pyrooptical properties, hence used for optical storage, light shutters and stereo television glasses.
Fig. 1.15 - Crystalline structure of Zirconium dioxide.
1.10 Literature Survey Several researchers studied the protection of the metals by using electrophoresis deposition in many applications. Review of many previously published works is presented here. The synthesis of Al2O3/SiC/ZrO2 functionally graded material (FGM) in bio-implants (artificial joints) by electrophoretic deposition (EPD). A suitable suspension that was based on 2-butanone was applied for the EPD of Al2O3/SiC/ZrO2, and a pressureless sintering process was applied as a presintering. Hot isostatic pressing (HIP) was used to densify the deposit, with beneficial mechanical properties after 2 h at 1800 ◦C in Ar atmosphere[77]. Electrophoretic deposition (EPD) is one of the colloidal processes during in ceramic production and has gained significant interest because of the high versatility of its use with different materials including nanoparticles and its cost-effectiveness requiring simple equipment. Of the major parameters for ceramic processing involving the EPD, preparation of the suspensions and application methods of electric fields are particularly important factors that
29
Chapter One
Introduction
affect the microstructure. At the beginning of this review, we introduce the fundamental aspects of the EPD processing. We then focus on the following four points: (1) the stability of the Pb(Zr,Ti)O 2 /ethanol suspension by the addition of phosphate esters and its influence on the subsequent EPD process, (2) the stability of a TiO2/(2-propanal+2.4-pentanedione) suspension, which is a suspension without dispersants, (3) the film performance of the pulsed direct current EPD using an aqueous suspension, and (4) the laminated textured ceramics by EPD in a strong magnetic field [78]. The Corrosion protection effectiveness of Alumina(Al2O3,50nm)and Zinc oxide (ZnO,30nm) nanoparticales were studied on carbon steel and 316 stainless steel alloys in seawater (3.5%NaCl)at four temperatures: (20,30,40,50 OC)using three electrodes potentiostat. An average corrosion protection efficiencies of 65 %and 80% was achieved using Al 2O3 NP's on carbon steel and stainless steel samples respectively, and it seems that no effect of rising temperature on the performances of the coated layers. While ZnO NP'S showed protection efficiency around 65% for the two alloys and little effected by temperature rising on the performanes of the coated layers. The morphology of the coated spesiemses was examined by Atomic force microscope [79]. Nickel coatings have been deposited by an electroless method on SiC powder particles. Three different SiC powder grades, in terms of average particle size, were chosen, i.e. 8, 14 and 70 µm. The coating process was performed in few steps consisting of the SiC powder cleaning by acetone, its sensitization by HCl aqueous solution containing Sn 2+, followed by its activation by HCl aqueous solution containing Pd 2+, and finally— hydrometallurgical nickel deposition using aqueous solution containing Ni2+, as a nickel carrier. The influence of the deposition conditions on the coating layer properties was studied. The thickness, morphology and microstructure of the layers were controlled by the growth conditions. SEM and digital image analyzing techniques were used for those purposes. Since the Ni-coated SiC powders were produced as reinforcement for Al matrix composites, their compatibility as compared with the uncoated SiC powders was also controlled by metallography [80]. Layered ceramics are being prepared by different forming methods such as slip or tape casting, dip coating, etc. Microlaminate materials have been also prepared by electrophoretic deposition _EPD, but usually from non-aqueous suspensions. In this work, the preparation of Al 2O3/ZrO2 layered ceramics from 30
Chapter One
Introduction
aqueous suspensions is described. The growth of the deposit thickness can be controlled in order to design laminar ceramics either as coatings or as selfsupported deposits, with a few thick layers, reducing warping effects, and avoiding environmental problems [81]. Electrophoretic deposition (EDP) is gaining increasing attention both in science and industry, due to novel applications in the processing of advanced ceramic materials and ceramic coatings. Electrophoretic deposition has become very interesting because this method has allowed the formation of thin films or multilayer films of controlled thickness and morphology, enabling the formation of films on substrates of complex geometry, aimed for different applications. This study reviewed the mechanism of electrodeposition of ceramic coatings (alumina and boehmite coatings) on metal surfaces, as well as the determination of the optimal deposition parameters (applied voltage, deposition time, electrodeposition bath temperature, suspension concentration) in order to control the thickness and morphology of deposited films. It was shown that coatings of maximum thickness, low porosity and good adhesion were obtained at lower deposition voltages and for longer deposition times [82]. Electrophoretic deposition behaviour of aqueous suspensions of ZrO 2 with carboxylic acid additives were studied in comparison with conventional pH adjustment. It was found that citric acid imparted negative zeta-potential values and electrosteric stabilization to particles in suspensions at all pH levels. The examination of additions of carboxylic acids to ZrO 2 suspensions revealed that these reagents cause a sharp drop in zeta-potential at distinct addition levels, which correspond to surface saturation of the particles with negatively charged carboxylate groups. Adsorption cross sections of citric acid, EDTA and oxalic acid were evaluated from these results, showing that both citric acid and EDTA coordinate to ZrO2 surfaces by two carboxylate groups while oxalic acid is coordinated by one group [83]. The electrophoretic deposition of materials is reviewed. Numerous applications of electrophoretic deposition are described, including production of coatings, free-standing objects, and laminated or graded materials, infiltration of porous materials, and fabrication of woven fiber preforms.In discussing the kinetics of the process, primary attention is given to the relation between the evolution of the current and the electric field strength [84].
31
Chapter One
Introduction
The effects of acids (monochloroacetic, dichloracetic, trichloroacetic and sulfuric acids) and bases (diethanolamine, triethanolamine, piperidine) on electrophoretic mobility and electrophoretic deposition (EPD) of particles of amphoteric Al2O3 and ZrO2 in anhydrous 2-propanol were studied. It was found that the _-potential of Al2O3 and ZrO2 particles had in acidic and alkaline 2-propanol media opposite charge to that in aqueous medium. This phenomenon was explained by the low dissociation constants of acids and bases in 2-propanol. This enables electrosteric stabilization of Al 2O3 and ZrO2 particles by acid anions and base cations. Similar electrophoretic behaviour of Al2O3 and ZrO2 particles in 2-propanolic dispersions stabilized by monochloroacetic allowed the preparation of compact, regular layered laminates with high cohesion at the interface of layers [85]. ZrO2 toughened Al2O3 (Al2O3/ZrO2) ceramic layers with required thickness were prepared by electrophoretic deposition (EPD) method using ethanol suspensions with stabilizing agent of polyethyleneimine (PEI) under constantvoltage mode. The deposition of Al2O3/ZrO2 ceramic powders occurred on the titanium alloy cathode. A stable suspension with 1wt% PEI in ethanol at pH 5 was prepared in terms of the zeta potential and sedimentation of the suspension. The effects of the suspension concentration, applied voltage, deposition time and processing method of titanium alloy cathode on the coating thickness and morphology were investigated. The deposition layers on titanium alloys with smooth surfaces and thickness of 0.35–1.2 mm could be obtained by adjusting the aforementioned parameters. In addition, after being sintered at 1500°C for 3 h in air atmosphere, ZrO 2 toughened Al2O3 ceramic layers became smooth and dense [86]. The electrophoresis of Titanium dioxide (TiO2) nanoparticles during electrophoretic deposition (EPD) technique was studied. This research was focusing on the effect of pH on the deposition behaviour of Titanium dioxide (TiO2) nanoparticles during electrophoretic deposition (EPD) technique. The ceramic substrates were prepared by using commercial ceramic filter. The TiO2 suspension were prepared by using non-aqueous solvent of alcohol and been characterized using Zeta sizer Nano series. The EPD was performed at 5V pulse-DC for 10 minutes. The deposited TiO2 were then been analyzed by using Field Scanning Electron Microscopy (FE-SEM). It was identified that the IEP was at pH 2.36 and cathodic deposition were observed at all pH except for pH 2. This study has achieved its objective where the different behaviour
32
Chapter One
Introduction
of TiO2 nanoparticles deposit was identified respected to vary pH. Future works will directed to increased the stability of TiO 2 suspension by using poly(acrylic acid) (PAA) for the same goal [87].
The synergistic effect between suspension particles and charging agent was investigated in addition to study the effect of three commercially-available cationic charging agents; aluminium (III) chloride (AlCl 3), polyethyleneimine (PEI) and poly (diallyldi-methylammonium chloride) (PDADMAC) on the EPD of coarse Ti particles onto steel. Surface microstructure, deposit yield, electrophoretic mobility and electrical conductivity were used to characterize Ti particles and obtained Ti deposit. The key finding of the present study is the bonding strength of charging agent-adsorbed coarse Ti particles deposits predominantly controlled their deposit yield [88].
33
Chapter One
Introduction
1.11 Aim of the Research The main areas of concern in the present research include the following: Study the corrosion behavior of the C.S alloy in seawater (3.5% NaCl) at four temperatures in range 298-328K. The results have the Tafel slops, the corrosion current densities and the corrosion potentials. The thermodynamic feasibility have judged from the free energy, enthalpy and entropy of the corrosion process of the C.S in the seawater (3.5% NaCl).The dependence of the corrosion current densities on temperature, activation energy (Ea) and Arrhenius factor (A) for the corrosion process were measured. Study of protection C.S alloy by coating with (SiC, ZrO2 and Al2O3) NPs using EPD technique , and corrosion protection for C.S alloy in seawater (3.5% NaCl) at four temperatures in the 298-328K compared with the corrosion behavior of uncoated (unprotected) C.S alloy. Study using polyacrylic acid as stabilizing agent in suspension solution of NPs used for coated C.S alloys to estimate the corrosion protection. Measurement of the surface porosity percentage (P%) for coating alloy on C.S by NPs for all cases. Study the surface morphologies of coated layers, using Atomic Force Microscope (AFM) technique.
34
Experimental Part
Chapter Two
Experimental Part
2.1 Experiments Part The experimental section can be divided into four parts ; 1. Corrosion tests for carbon steel (C.S) specimens in seawater (3.5% NaCl) solutions at temperatures ranged (298- 328)K by using potentiostate . 2. Coating processes of the specimens with SiC , Al2O3 , ZrO2 NPs using EPD to determine the corrosion resistance rate in seawater (3.5% NaCl). 3. Effect of stabilizing agent Polyacrylic acid (PAA) in ethanol suspension solution in EPD technique. 4. Structure studies by atomic force microscopy (AFM)
2.2 Chemicals and Instrumentation 2.2.1 Chemicals and Materials: Carbon Steel (C45) was used as metallic materials with chemical composition as described in the table (2.1) Many chemical were used in this work include some regents which are listed in table (2.2) with their purity and origin, Nanoparticles also used to apply coating include alumina, silicon carbide and zirconia with their properties are listed in Appendix C1 to C3.
Table (2.1): Chemical composition for C.S . Grade C45
%C
% Si
% Mn
%S
%P
% Ni
% Cr
%Mo, Cr+Ni
0.42-0.50
ZrO2 with (0.25%) PAA > ZrO2 with (0.1%) PAA > ZrO2 with (1%) PAA> ZrO2 only
95 90 85
PE%
ZrO2 + (0.1%) PAA 80
ZrO2 + (0.25%) PAA ZrO2 + (0.5%) PAA
75
ZrO2 + (1%) PAA
70
ZrO2 without PAA 65
60 295
300
305
310
315
320
325
330
T/K
Fig. 3.50 - Relationships between the protection efficiencies (PE%) of C.S coated with ZrO2 NPs , and temperature (T).
3. With Al2O3 NPs coating of C.S alloys, highest PE% (86%) was obtained by coated the alloy by Al2O3 in presence (0.5%) PAA. Both Al2O3 with (0.25 and 1) % PAA coated were dependent on temperature, but other coated independent on temperature, as shown in figure (3.51).
90
Chapter Three
Results and Discussions
88 86 84
PE%
82
Al2O3 + (0.1%) PAA
80
Al2O3 + (0.25%) PAA Al2O3 + (0.5%) PAA
78 76
Al2O3 + (1%) PAA
74 72 70 295
300
305
310
315
320
325
330
T/K
Fig. 3.51 - Relationships between the protection efficiencies (PE%) of C.S coated with Al2O3 NPs , and temperature (T).
The protection efficiency which were presented in figures (3.42-3.44) and tables (3.11, 3.13 and 3.15) may appear to be contradicting in certain cases. Protection efficiency (PE%) for C.S alloys were highest (close to 100%) when C.S alloys was protected by SiC in presence (0.25%) PAA.Figure (3.52) show the comparison between PE% for C.S alloys after protected by different NPs at 298K. SiC+0.25 PAA, 99.65 100
Highest value
Lower value
Al2O3, 82.1 80
PE%
60 40 20 0
Protection Types
Fig. 3.52 - Comparison between PE% for C.S alloys after protected by different NPs at 298K.
91
Conclusion and Further suggest
Conclusion and Further suggest
Chapter Four
Chapter Four Conclusion and Further suggest 4.1 Conclusions Certain conclusions can be derived from the results and discussions that have been presented in the thesis and these may be summarized as in the following points: 1. The AFM images detection The Particles size increase after coated by different NPs in all cases. 2. The Electrophoretic Deposition (EPD) technique was successfully applied to coat C.S by SiC, ZrO2& Al2O3 nanoparticles. 3. The perfect time for coated C.S by SiC and ZrO2 NPs was 5 minutes but the perfect time for coated C.S by Al2O3 NPs was 6 minutes. 4. The protection efficiency of coated by SiC and Al2O3 NPs unaffected by temperatures but the protection efficiency for coated C.S by ZrO2 NPs affected. 5. Added PAA in the suspension solution act as stabilizing agent and create NPs coated more smooth and resistant to heat. 6. The rate of corrosion increased with increasing temperatures ranged from 298 to 328 K. After coated by NPs, Two important trends are evident. Firstly , the corrosion potential shifted toward more active value in coated carbon steel with NPs , Secondly, the corrosion current densities were significant reduced with coated by NPs. 7. The protected by coated with SiC NPs without PAA was more resistant to corrosion comparison with the other protected by coated NPs (Al 2O3, ZrO2). 8. PAA increased the protection when added in suspension solution of coated. Adding (0.25%) PAA in suspension solution of SiC NPs lead to highest protection efficiency. 9. The polarization resistance RP decreases with temperature increase, because RP inversely proportional with corrosion current density icorr. 10.The surface porosity percentage P% , generally increase with temperature increase , and adding different PAA% increase the P% because P% depended on RP and Ecorr . 11.The extents of corrosion of the various coated C.S alloys by NPs (SiC, Al2O3 or ZrO2) in seawater (3.5% NaCl) over the experimental 92
Conclusion and Further suggest
Chapter Four
temperature range and the effectiveness of the methods used for their protection may be judged on: i. Thermodynamic grounds from the respective thermodynamic parameters, which are based mainly on the corrosion potentials and their dependencies on temperature. ii. Kinetic aspects which are based on the values of the corrosion current densities and their dependencies on temperature. The protection efficiency of each protection mean depends also on the values of corrosion current density in various cases in comparison with the case where the protection mean is absent. 12.The thermodynamic studies shows after protect C.S alloys by coated with (SiC, Al2O3 or ZrO2) NPs, the negative value of ΔS decreased, and with SiC NPs become more disorder. In addition, the corrosion process was exothermic process for uncoated and coated with (SiC, Al2O3 or ZrO2) NPs.
4.2 Suggest for Further Research: It is worthwhile to forward some suggestions for the extension of the present work in future as in the following: 1. The present work has concentration on only C.S alloys coated by (SiC, Al2O3 and ZrO2) NPs. It is necessary to cover other alloys. 2. Studying the corrosion protection of the same alloys and technique of coated with different NPs. 3. Stabilizing the suspension solution of coated by using different polyacrylic acid (PAA) and by use other polymers, specially conductive polymers. 4. The corrosion of C.S alloy, which have been subjected to the present investigation, was appreciate mainly in seawater (3.5%NaCl). It would be desirable to replace the seawater (3.5% NaCl) which was selected for the present researched by other corrosive medium. 5. Studying the corrosion condition effect on deposition layer by using electrophoretic deposition (EPD) such as temperature of emulsion, voltage, solvent type.
93
References
References 1. Frame Project Team, 1999,”A Guide To Corrosion Protection” Cracking Down on Corrosion, American Iron and Steel Institute, 2000 Town Center, Suite 320, Southfield, MI, 48075-1199. 2. Einar B., 2004,”Corrosion and protection–Engineering materials and Processes’’, Springer-Verlag London Limited, Vol.1, pp: 156. 3. Mohammad, H., 2006 ,Ph.D. Thesis, ’’Modeling of Pipeline Corrosion Control By Cathodic Protection’’, Department of Production Engineering and Metallurgy, University of Technology, iraq. 4. Shreir L. , 2010, “ Corrosion”, Metal / Environment Reaction ,Head of department of metallurgy and materials, city of London polytechnic, Vol. 1, pp 1:3–1:15. 5. Horst C., Tetsuya Saito, Leslie Smith, 2006, “Springer Handbook of Materials Measurement Methods”, pp. 614. 6. “Introduction to Corrosion Monitoring”, Metal Samples Company, http://www.alspi.com/corrosion-intro. 7. LOGAN K., 1954, “Corrosion”, Vol.10, pp. 206. 8. Zaki A., 2006, ’’Principles of Corrosion Engineering and Corrosion Control’’, Elsevier Science & Technology Books, Vol.90, pp. 2. 9. Ahmad Q., 2010, M.Sc thesis, ‘’Physical Investigation of Corrosion Protection of Polymer Coated Steel in Concrete’’, University of Baghdad, College of Science, Physics Department. 10.Smyth C., 1955, “Dielectric Behavior and Structure”, Chapter 1 and 2, McGraw-Hill, New York, NY. 11.McCaffetry E. , Parvdic V., and Zettlemoyer A., 1970, “Modern Aspects of Electrochemistry”, Transactions of the Faraday Society, Vol.66, pp.1720. 12.Benjamin D. and Richard A., 2006, ‘’ Corrosion Prevention and Control: A Program Management Guide for Selecting Materials’’, Alion Science and Technology, Vol.246, pp. 79. 13.Zarrok H., Oudda H., Zarrouk A., Salghi R., Hammouti B., Bouachrine M., 2011, “Weight Loss Measurement and Theoretical Study of New Pyridazine Compound as Corrosion Inhibitor for C38 Steel in Hydrochloric Acid Solution” Der Pharma Chemica, Vol. 3, pp.576-590. 14.Ismail A., El-Kot A., 1991, “An insight into further limitation of use of thermometric method for determination of corrosion inhibition efficiency of Zn in Hudrochloric acid silution”, Asian journal chemistry, Vol.3, No.4, pp.432-439. 15.McCaffetry E., 2009, “Introduction to corrosion science”, Springer science, New York.
94
References 16.Pierre R., 2000,’’Handbook of Corrosion Engineering’’, The McGrawHill Companies, Inc. , pp. 265. 17.Uhlig H., 1985, ‘’Corrosion and Corrosion Control’’ 3rd edition, John Wiley, New York. 18.Denny A., 1996, ‘’Principle and Prevention of Corrosion ‘’, USA Prentice Hall, Upper Saddle River, Second Edition. 19.Fontana M. and Green M., 1984,’’ Corrosion Engineering’’, International Student Edition, Mc Graw Hill, pp. 178. 20.Fontana M. and Green M. , 1986 ,‘’Corrosion Engineering ‘’, McGrawHill book Co., third edition, pp. 213. 21.Shrier L., 2000, ‘’Corrosion Metal / Environment reactions’’, printed and bound in Great Britain, Butterworth Hejne Mann, 3 rd, Reprinted, Vol.1, pp. 326. 22.Nestor P., 2004, ’’ Electrochemistry and Corrosion Science’’, Kluwer Academic Publishers, pp. 1-10. 23.Marker, J., Chgnon, N., 1999, ‘’Inspecting System for Leaks, Pits and Corrosion ‘’, National Research Counical Canada, Published in Journal AWWA, Vol. 91, No.7, pp.36-45. 24.Fontana M. and Green M., 1978, ’’Corrosion Engineering’’, 2nd edition, McGraw-Hill, N.Y. USA. pp.2. 25.Shyne J. and Scheible H., 1963, “Modern Electroplating” edited by P. A. Lowenheim (John Wiley and Sons, New York, 1963), pp: 714. 26.Yasir M., 2010, M.Sc. Thesis,’’ The Use of Al-Zn Alloys as Sacrificial Anodes to Protect Buried Steel Pipes’’, Department of Production Engineering and Metallurgy, University of Technology. 27. McCaffony E. and Hackerman N., 1972, “Kinetics of Iron Corrosion in Concentrated Acidic Chloride Solutions” Journal of Electrochemical Society, Vol.119, pp.999–1009. 28.Steigerwald, R., 1968, “Electrochemistry of Corrosion”, Corrosion, Vol. 24, No. 1, pp. 1-10. 29.Ghalib A., 2007, M.Sc. Thesis, “Identification of polarization parameters for cathodic protection by using neural network’’ ,Production and Metallurgy Engineering Department, University of Technology, Iraq. 30.Ghanbari A., Attar M., Mahdavian M., 2009,’’ Acetylacetonate Complexes as New Corrosion Inhibitors in Phosphoric Acid Media: Inhibition and Synergism Study’’, Progress in Color, Colorants and Coatings Journal, Vol. 2, pp.115-122. 31.Elizabeth M. and Mary J., 1987, ‘’ASM international Metals Handbook’’, Corrosion, Vol. 13, pp.772–785. 95
References 32.Geetanjali P., 2010, M.Sc. Thesis,’’ Synthesis of Ultrafine Dispersed Coating by Electrodeposition’’, National Institute of Technology, Rourkela. 33.Tang F., Uchikoshi T., Suzuki T., and Sakka Y., 2004, “Alignment of TiO2 Particles by Electrophoretic Deposition in a High Magnetic Field”, Materials Research Bulletin, Vol. 39, No. 14-15, pp.2147-2154. 34.Guozhong C., 2004, ‘’Nanostructures & Nanomaterials Synthesis, Properties and Applications’’, World Scientific Printers, Singapore. 35.Kaya C., Kaya F., Su B., 2005, “Structural and Functional Thick Ceramics Coating by Electrophoretic Deposition”, Surface and Coatings Technology, Vol. 191, pp.303–310. 36.Ahmad A., 2011, M.Sc. Thesis,’’Nanotechnology Principles and Applications’’, Dajlah. 37.Cora L., Stacy D., Nathalie M. , 2010,’’ Novel Materials through NonHydrolytic Sol-Gel Processing: Negative Thermal Expansion Oxides and Beyond’’, Materials, Vol. 3, pp.2567-2587. 38.Uhlig H. and revie R. , 2011, " UHLIG’S CORROSION HANDBOOK" ,CANMET Materials Technology Laboratory, Vol.3, pp.1001. 39.Fukada Y., Nagarajan N., Mekky W., Bao Y., Kim H., Nicholson P., 2004, “Electrophoretic deposition—mechanisms, myths and materials”, Journal of Materials Science, Vol. 39, pp:787– 801. 40.Ning W., Hong L., Jianbao L., 2006,’’ Electrophoretic Deposition and Optical Property of Titania Nanotubes Films’’, Thin Solid Films, Vol.2, pp.496. 41.Bose G., 1745, “Abstract of a letter from Monsieur De Bozes”, Philosophical Transactions of the Royal Society, Vol. 43, pp.419. 42.Sarkar P. and Nicholson P., 2002, “Electrophoretic Deposition: Mechanisms, Kinetic and Application to Ceramics”, Journal of the American Ceramic Society, Vol. 79. 43.Mohd F. Abdul R. and Zulkarnain Z., 2007,’’Electrophoretic Deposition and Characterization of Copper Selende Thin Films’’, The Malaysian Journal of Analytical Sciences, Vol. 11, No. 1, pp. 324-330. 44.Belaroui K., Rapillard G., Bowen P., 2002,’’Nano Crystalline Coating by Electrophoresis Deposition ‘’, Key Engineering Materials, pp:206213. 45.Guy A., Kim V. and Jef V., 2005,’’ Electrophoretic Deposition as a Novel Near Net Shaping Technique for Functionally Graded Biomaterials’’, Materials Science Forum, Vols. 492-493, pp. 213-218. 46.Wei M., Ruys A. and Milthorpe B., 2005,’’ Precipitation of Hydroxyapatite Nanoparticles: Effects of Precipitation Method on 96
References Electrophoretic Deposition’’, Materials Science: Materials in Medicine, Vol.16, pp.129-133. 47.Tan A., Soutar A. and Tan H., 2008, ‘’Electrophoretic Deposition (EPD) of Nano-Particulate Hybrid Coatings for Corrosion Protection’’, SIMTech technical Report, Vols. 9, No. 4. 48.Sarkar, P. and Nicholson, P., 1996, ‘’Electrophoretic Deposition (EPD): Mechanism, Kinetics and Application to Ceramics’’, J. Am. Ceram. Soc., Vol.79, No. 8, pp. 1987–2002. 49.Zhitomirsky I., 2000,’’Ceramic Films Using Cathodic Electrodeposition’’, The Minerals, Metals & Materials Society, Vol. 52, No.1. 50.Boccaccini, A., Cho, J., 2006,’’Electrophoretic Deposition of Carbon Nanotubes’’, Carbon, Vol. 44, No.16, pp. 3149-3160. 51.Kanamura, K. and Hamagami J., 2004, “Innovation of Novel Functional Material Processing Technique by Using Electrophoretic Deposition Process”, Solid State Ionics, Vol. 172, No. 1-4, pp. 1-628 . 52.Bharat Bhushan, 2006, “Handbook of Nanotechnology”, Springer Science, 2nd edition, pp.175. 53.Sarkar P., De D., Rho H., 2004,’’ Synthesis and Microstructural Manipulation of Ceramics by Electrophoretic Deposition’’, Vol.39, No. 3, pp.819. 54.Gani M., 1994, “Electrophoretic deposition. A Review”, industrial ceramics, Vol.14, p.163-174. 55.Narottam P., Aldo R., 2012, “Ceramics and Composites Processing Methods”, First Edition, pp:517. 56.Valeria D., Gonnelli R., Silvia B., 2005,’’ Synthesis of MgB2 Thick Films by Electrophoresis Technique:structural and Superconductive Characterization’’, Vol. 2 ,No.5, pp. 1662–1667. 57.Safaa M., 2006, M.Sc. Thesis, "A Study on Corrosion Behavior of Ductile Cast Iron Used Instead of Gray Cast Iron", Mechanical Engineering Department , Al-Rasheed College of Engineering and Science, University of technology, Iraq. 58.Kangmin W. and Zhitomirsky I., 2011, “Electrophoretic Deposition of Ceramic Nanoparticles”, Int. J. Appl. Ceram. Technol., Vol.8, pp.920– 927. 59.Besra L. and Liu M., 2007, “A Review on Fundamentals and Applications of Electrophoretic Deposition”, Progress in Materials Science, Vol. 52. 60.Lebrette S., Pagnoux C., and Abelard P., 2006, “Fabrication of Titania Dense Layers by Electrophoretic Deposition in Aqueous Media”, 97
References Journal of the European Ceramic Society, Vol. 26, No. 13, pp. 2727– 2734. 61.Aldo R. , Johann C. , Judith A. , 2006,’’ Electrophoretic Deposition of Carbon Nanotubes’’, Carbon, Vol. 44, pp. 3149–3160. 62.Ferrari, B. and Moreno, R, 1996, “The conductivity of aqueous Al2O3 slips for electrophoretic deposition”, Materials Letters, Vol.28, pp.353355. 63.Ferrari B., Moreno R., 1997, “Electrophoretic deposition of aqueous alumina”, Journal of the European Ceramic Society, Vol.17, pp.549556. 64.Fisher R., Fisher E., De P., and Roncari E., 1995, "Preparation of ceramic micro-laminate by electrophoresis in aqueous system ", Journal of Materials Science Letters, Vol.14, pp. 25-27. 65.Uchikoshi T., Ozawa K., Hatton B., Okuyama H., and Sakka Y., 2001, “Dense, bubble-free ceramic deposits from aqueous suspensions by electrophoretic deposition”, Journal of Materials Research, Vol.16, pp. 321-324. 66.Van O., Vandeperre L., 1999, “Electrophoretic Deposition of Materials’’, Annual Review of Materials Science, Vol.29, pp. 327-352. 67.Laxmidhar B. and Melini L. , 2007, “A review on fundamentals and applications of EPD”, Colloids and materials chemistry group, pp.50. 68.Maca K., Hadraba H. and Cihlar J., 2004, “Electrophoretic Deposition of Alumina and Zirconia: II. Two-Component Systems”, Ceramics International, Vol.30, No.6, pp. 853-863. 69.Johann C., Silke S., Judith A., 2008,’’ Nanostructured Carbon Nanotube/TiO2 Composite Coatings Using Electrophoretic Deposition (EPD)’’, Nanoparticle Research, Vol. 10, No. 1, pp. 1 - 86. 70.Muhammad Z, Mazhar M., 2011,’’ Synthesis of Nickel Nanoparticles in Silica by Alcogel Electrolysis’’, Nanoparticle Research, Vols. 13, No. 1, pp. 375-384. 71.Liu B., Nakata K., Sakai M., Saito H., Ochiai T. , Murakami T., Takagi K., and Fujishima A., 2011, “Mesoporous TiO2 core shell spheres composed of nanocrystals with exposed high-energy facets: facile synthesis and formation mechanism”, Journal of American Chemical Society, Vol. 27, No. 13, pp. 8500–8508. 72.Nakata K., Liu B., Ishikawa Y., Sakai M., Saito H., Ochiai T., Sakai H., Murakami T., Abe M., Takagi K., and Fujishima A., 2011, “Fabrication and photocatalytic properties of TiO 2 nanotube arrays modified with phosphate”, Journal of Chemistry Letters, Vol. 40, No. 10, pp. 1107– 1109. 98
References 73.Yao L., Haas T., Guiseppi-Elie A., Bowlin G., Simpson D., and Wnek G. , 2003, “Electrospinning and stabilization of fully hydrolyzed poly (vinyl alcohol) fibers” , Journal of Chemistry of Materials, Vol. 15, pp. 1860–1864. 74.Burda C., Lou Y., Chen X., Samia A., Stout J., and Gole J., 2003, “Enhanced nitrogen doping in TiO2 nanoparticles”, Journal of Nano Letters, Vol. 3, pp. 1049–1051. 75.Brayner R., Dahoumane S., Yepremian C., Djediat C., Meyer M., Coute A., and Fievet F., 2010, “ZnO nanoparticles: synthesis, characterization, and ecotoxicological studies”, Journal of American Chemical Society, Vol.26, No. 9, pp. 6522–6528. 76.2013, “Silicon Carbide (SiC) Nanoparticles, Properties and Applications”, AZoNano, Date Added: Apr 16, 2013 | Updated: Jul 11. 77.Askari E., Mehrali M., Metselaar I., Kadri N. and Rahman M., 2012, “Fabrication and mechanical properties of Al 2O3/SiC/ZrO2 functionally graded material by electrophoretic deposition”, Journal Of The Mechanical Behavior Of Biomedical Materials, Vol. 2, pp.144–150. 78.Yoshio S. and Tetsuo U., 2010, “Forming and Microstructure Control of Ceramics by Electrophoretic Deposition (EPD)”, KONA Powder and Particle Journal, No.28, pp. 74-90. 79.Rasha A., Abdulkareem M. and Ahlam M. , 2014, “Corrosion Protection Study of Carbon Steel and 316 Stainless Steel Alloys Coated by Nanoparticles”, Journal Baghdad for Science, Vol.11, No.1, pp. 7888. 80.Kretz F., Ga´csi Z., Kova´cs J. and Pieczonka T., 2004, “The electroless deposition of nickel on SiC particles for aluminum matrix composites”, Surface and Coatings Technology, Vol.180 –181, pp.575–579. 81.Ferrari B., Sanchez-Herencia A. and Moreno R., 1998, “Aqueous electrophoretic deposition of Al2O3/ZrO2 layered ceramics”, Materials Letters, Vol. 35, pp.370–374. 82.Mišković-Stanković V., 2012, “Electrophoretic Deposition Of Alumina And Boehmite Coatings On Metal Surfaces”, Macedonian Journal of Chemistry and Chemical Engineering, Vol. 31, No. 2, pp. 183–193. 83.Dorian A., Marco M., Cristina L. and Charles C. , 2012, “The Effects of Carboxylic Acids on the Aqueous Dispersion and Electrophoretic Deposition of ZrO2”, Journal of the European Ceramic Society, Vol.32,No.1, pp.235-244. 84.Omer O. and Luc J., 1999, “Electrophoretic Deposition of Materials”, Annual Review of Materials Research., Vol.29, pp.327–52.
99
References 85.Jaroslav C., Daniel D., Zora C. and Hynek H., 2013, ”Effect of acids and bases on electrophoretic deposition of alumina and zirconia particles in 2-propanol”, Journal of the European Ceramic Society, Vol.33, pp.1885–1892. 86.Chun-mei Y., Xian-chun C., Xiaoming L., Zhong-bing H., Ya-dong Y. and Guang-fu Y., 2011, “Electrophoretic deposition of Al2O3/ZrO2 layer with controllable thickness in ethanol medium”, Frontiers of Chemistry in China, Vol.6, No.2, pp.76–83. 87.Fitrah R., Noorsuhana M., 2013, “Deposition behavior of Titanium dioxide (TiO2) nanoparticles during electrophoretic deposition (EPD) technique - Effects of pH”, Business Engineering and Industrial Applications Colloquium, pp. 56 – 60. 88.Kok-Tee L. and Sorrell C., 2013, “Effect of cationic charging agent on the bonding strength of coarse Titanium particles deposited by electrophoretic deposition”, International Journal Institute of Materials Malaysia, Vol.1. 89.Frederic B. and Alain F., 1999, “Electrophoretic Deposition of Silicon Carbide”, Journal of the American Ceramic Society, Vol.82, No.8, pp.2001–2010. 90.Lessing P., Erickson A., Kunerth D., 2000, “Electrophoretic deposition [EPD] applied to reaction joining of silicon carbide and silicon nitride ceramics”, Journal of Materials Science, Vol.35, pp.2913–2925. 91.Kok-Tee L., Sorrell C., 2013, “Effect of Charging Agents on Electrophoretic Deposition of Titanium Particles”, Journal of the Australian Ceramic Society Vol.49, No.2, pp.104 – 112. 92.Vandeperre L., Bouyer F., Foissy A., Van Der B., 1998, “SiC-graphite laminates shaped by EPD“, The American Ceramic Society Bulletin, Vol.77 No.1, pp.53-5. 93.Aradilla Zapata, D., 2012, “Design, synthesis, characterization and development of novel organic conducting polymers with technological applications, in Departament d’enginyeria quimica”. Universitat Politecnica de catalunya: Barcelona. 94.Al-Shamma L., Jalal.M and Hikmat N., 1987, corrosion science, Vol.27, No.22. 95.Jalal M. and Y. Al-Hayderi, 1989, Bulletin of the Chemical Society of Japan, Vol.62, pp:1237. 96.Jsseling F., 1974, “The application of the polarization resistance method to the study of the corrosion behaviour of CuNi 10Fe in seawater”, Corrosion Science, Vol.14, No.2, pp.97-100.Karlsrue and
100
References Mansfeld F., 1981, 8th International Congress on Metallic Corrosion, Dechema, Germany, 6-11 Sep. . 97.Karlsrue and Mansfeld F., 1981, 8th International Congress on Metallic Corrosion, Dechema, Germany, 6-11 Sep. . 98.Murgulescu I. and Radovici O., 1961, 2nd International Congress on Metallic Corrosion, London, 10-15, Aprial,Butterwirths, London, pp.202-205. 99.Quraishi M., Sudhish K., 2009, “Poly(aniline-formaldehyde): A new and effective corrosion inhibitor for mild steel in hydrochloric acid”, Materials Chemistry and Physics, Vol.113, pp. 685–689. 100. Asan A., 2012, M.Sc. Thesis,” A Study in Protection of Corrosion by Using Nanoparticles (TiO2, SiO2) for Some Metals and Alloys “ ,College of Science for Women University of Baghdad. 101. Yao Z., Braidy N., Botton G.and Adronov A., 2003, “Polymerization from the surface of single-walled carbon nanotubes - preparation and characterization of nanocomposites”, Journal of the American Chemical Society, Vol.125, No.51, pp.16015. 102. Majumder M., Chopra N. and Hinds B., 2005, “Effect of tip functionalization on transport through vertically oriented carbon nanotube membranes“, Journal of the American Chemical Society, Vol.127, No.25, pp.9062. 103. Lorenzetti M., Eva P., Jordi S., Maria D., Janez K., Novak S., and Spomenka K., 2014, “Improvement to the Corrosion Resistance of TiBased Implants Using Hydrothermally Synthesized Nanostructured Anatase Coatings”, Materials, Vol.7, pp.180-194. 104. Kok-Tee L. and Sorrell C., 2011, “Electrophoretic Mobilities of Dissolved Polyelectrolyte Charging Agent and Suspended Noncolloidal Titanium during Electrophoretic Deposition”, Materials Science and Engineering: B, No.176, pp.369-381. 105. Masashi A., Teruhisa M., Kunitaka F. and Makoto K., 2010, “Preparation of Barium Titanate Nanoparticle Thin Films by the Electrophoretic Deposition Method Using Polyacrylic Acid as a Charge-Compensating Agent”, Key Engineering Materials, Vol.421422, pp.510-513. 106. Boulkroune M. and Chibani A., 2012, “2-Thiophene Carboxaldehyde as Corrosion Inhibitor for Zinc in Phosphoric Acid Solution”, Chemical Science Transactions, Vol.1, No.2, pp.355-364. 107. Bouanis F., Bentiss F., Traisnel M., Jama C., 2009, “Enhanced corrosion resistance properties of radiofrequency cold plasma
101
References nitrided carbon steel: Gravimetric and electrochemical results”, Electrochimica Acta, Vol.54, No.8, pp.2371. 108. El Ouali I., Hammouti B., Aouniti A., Ramli Y., Azougagh M., Essassi E. , Bouachrine M., 2010,” Thermodynamic characterisation of steel corrosion in HCl in the presence of 2-phenylthieno (3,2-b) quinoxaline”, Journal of Materials and Environmental Science,Vol.1, pp.1. 109. M. Behpour, S.M. Ghoreishi, N. Soltani, M. Salavati-Niasari, M. Hamadanian, A. Gandomi, 2008,” Electrochemical and theoretical investigation on the corrosion inhibition of mild steel by thiosalicylaldehyde derivatives in hydrochloric acid solution”, Corrosion Science, Vol.50, No.8, pp.2172. 110. Srimathi M., Rajalakshmi R., Subhashini S., 2010, “Polyvinyl alcohol–sulphanilic acid water soluble composite as corrosion inhibitor for mild steel in hydrochloric acid medium”, Arabian Journal of Chemistry. 111. Vashi, R., Champaneri V., 1997, “Chloro-substituted aniline as corrosion inhibitors for zinc in sulfamic acid”, Trans. SAEST, Vol.32, No.1, pp.5–14.
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Appendix
Appendix Appendix A Appendix A1 Tafel plots of uncoated Carbon steel specimen in 3.5% NaCl
At 298 K
At 308 K
At 318 K 103
Appendix
At 328 K Appendix A2 Tafel plots of coated carbon steel with SiC NPs in 3.5% NaCl.
At 298 K
At 308 K
104
Appendix
At 318 K
At 328 K Appendix A3 Tafel plots of coated carbon steel with ZrO2 NPs in 3.5% NaCl.
At 298 K
105
Appendix Appendix A4 Tafel plots of coated carbon steel with Al2O3 NPs in 3.5% NaCl.
At 308 K
At 318 K
At 328 K
106
Appendix
At 298 K
At 308 K
At 318 K
107
Appendix
At 328 K Appendix A5 Tafel plots of coated carbon steel with SiC NPs in presence (0.1%) PAA in 3.5% NaCl.
At 298 K
At 308
At 318 K
At 328 K
108
Appendix Appendix A6 Tafel plots of coated carbon steel with SiC NPs in presence (0.25%) PAA in 3.5% NaCl.
At 298 K
At 308 K
At 318 K
At 328 K
Appendix A7 Tafel plots of coated carbon steel with SiC NPs in presence (0. 5%) PAA in 3.5% NaCl.
At 298 K
At 308 K
109
Appendix
At 318 K
At 328 K
Appendix A8 Tafel plots of coated carbon steel with SiC NPs in presence (1%) PAA in 3.5% NaCl.
At 298 K
At 308 K
At 318 K
At 328 K
110
Appendix Appendix A9 Tafel plots of coated carbon steel with ZrO2 NPs in presence (0.1%) PAA in 3.5% NaCl.
At 298 K
At 308 K
At 318 K
At 328 K
Appendix A10 Tafel plots of coated carbon steel with ZrO2 NPs in presence (0.25%) PAA in 3.5% NaCl.
At 298 K
At 308 K
111
Appendix
At 318 K
At 328 K
Appendix A11 Tafel plots of coated carbon steel with ZrO2 NPs in presence (0. 5%) PAA in 3.5% NaCl.
At 298 K
At 308 K
At 318 K
At 328 K
112
Appendix Appendix A12 Tafel plots of coated carbon steel with ZrO2 NPs in presence (1%) PAA in 3.5% NaCl.
At 298 K
At 308 K
At 318 K
At 328 K
Appendix A13 Tafel plots of coated carbon steel with Al2O3 NPs in presence (0.1%) PAA in 3.5% NaCl.
At 298 K
At 308 K
113
Appendix
At 318 K
At 328 K
Appendix A14 Tafel plots of coated carbon steel with Al2O3 NPs in presence (0.25%) PAA in 3.5% NaCl.
At 298 K
At 308 K
At 318 K
At 328 K
114
Appendix Appendix A15 Tafel plots of coated carbon steel with Al2O3 NPs in presence (0. 5%) PAA in 3.5% NaCl.
At 298 K
At 308 K
At 318 K
At 328 K
Appendix A16 Tafel plots of coated carbon steel with Al2O3 NPs in presence (1%) PAA in 3.5% NaCl.
At 298 K
At 308 K
115
Appendix
At 318 K
At 328 K
116
Appendix Appendix B Appendix B1 Particle size distribution AFM report of SiC without PAA on carbon steel
Granularity Cumulation Distribution Report Sample:SiC without PAA Line No.: lineno Instrument:CSPM
Code:Sample Code Grain No.:197 Date:2014-07-15
Avg. Diameter:60.51 nm
Diameter(nm) Volume(% Cumulation(% Diameter(nm) Volume(% Cumulation(% Diameter(nm) Volume(% Cumulation(% < ) ) < ) ) < ) )
40.00 45.00 50.00 55.00
4.06 11.17 7.61 11.17
4.06 15.23 22.84 34.01
60.00 65.00 70.00 75.00
16.24 15.74 7.61 10.15
117
50.25 65.99 73.60 83.76
80.00 85.00 90.00
7.61 5.58 3.05
91.37 96.95 100.00
Appendix Appendix B2 Particle size distribution AFM report of SiC with PAA on carbon steel
Granularity Cumulation Distribution Report Sample: SiC with 0.25% PAA Line No.:lineno Instrument:CSPM
Code:Sample Code Grain No.:81 Date:2014-07-15
Avg. Diameter:95.26 nm
Diameter(nm) Volume(% Cumulation(% Diameter(nm) Volume(% Cumulation(% Diameter(nm) Volume(% Cumulation(% < ) ) < ) ) < ) )
20.00 30.00 40.00 50.00 60.00
2.47 1.23 3.70 2.47 7.41
2.47 3.70 7.41 9.88 17.28
70.00 80.00 90.00 100.00 110.00
7.41 9.88 11.11 13.58 3.70
118
24.69 34.57 45.68 59.26 62.96
120.00 130.00 140.00 150.00 160.00
6.17 8.64 11.11 8.64 2.47
69.14 77.78 88.89 97.53 100.00
Appendix Appendix B3 Particle size distribution AFM report of ZrO2 without PAA on carbon steel
Granularity Cumulation Distribution Report Sample:ZrO2 without PAA Line No.:lineno Instrument:CSPM
Code:Sample Code Grain No.:274 Date:2014-07-15
Avg. Diameter:61.24 nm
Diameter(nm) Volume(% Cumulation(% Diameter(nm) Volume(% Cumulation(% Diameter(nm) Volume(% Cumulation(% < ) ) < ) ) < ) )
45.00 50.00 55.00 60.00
4.74 20.80 12.41 13.87
4.74 25.55 37.96 51.82
65.00 70.00 75.00 80.00
12.77 9.85 9.49 8.39
119
64.60 74.45 83.94 92.34
85.00 90.00 95.00
3.28 2.92 1.46
95.62 98.54 100.00
Appendix Appendix B4 Particle size distribution AFM report of ZrO2 with PAA on carbon steel
Granularity Cumulation Distribution Report Sample: ZrO2 with 0.5% PAA Line No.:lineno Instrument:CSPM
Code:Sample Code Grain No.:129 Date:2014-07-15
Avg. Diameter:103.58 nm
Diameter(nm) Volume(% Cumulation(% Diameter(nm) Volume(% Cumulation(% Diameter(nm) Volume(% Cumulation(% < ) ) < ) ) < ) )
70.00 80.00 90.00 100.00
11.63 13.95 12.40 17.05
11.63 25.58 37.98 55.04
110.00 120.00 130.00 140.00
8.53 7.75 5.43 7.75
120
63.57 71.32 76.74 84.50
150.00 160.00 170.00
6.20 7.75 1.55
90.70 98.45 100.00
Appendix Appendix B5 Particle size distribution AFM report of Al2O3 without PAA on carbon steel
Granularity Cumulation Distribution Report Sample:Al2O3 without PAA Line No.: lineno Instrument:CSPM
Code:Sample Code Grain No.:286 Date:2014-07-15
Avg. Diameter:66.80 nm
Diameter(nm) Volume(% Cumulation(% Diameter(nm) Volume(% Cumulation(% Diameter(nm) Volume(% Cumulation(% < ) ) < ) ) < ) )
50.00 55.00 60.00 65.00 70.00 75.00 80.00
13.64 21.33 13.99 12.59 6.64 5.59 5.24
13.64 34.97 48.95 61.54 68.18 73.78 79.02
85.00 90.00 95.00 100.00 105.00 110.00 115.00
5.24 2.45 2.80 2.45 2.80 1.40 0.35
121
84.27 86.71 89.51 91.96 94.76 96.15 96.50
120.00 125.00 135.00 140.00 150.00
1.05 0.70 1.05 0.35 0.35
97.55 98.25 99.30 99.65 100.00
Appendix Appendix B6 Particle size distribution AFM report of Al2O3 with PAA on carbon steel
Granularity Cumulation Distribution Report Sample: Al2O3 with 0.5% PAA Line No.:lineno Instrument:CSPM
Code:Sample Code Grain No.:181 Date:2014-07-15
Avg. Diameter:82.77 nm
Diameter(nm) Volume(% Cumulation(% Diameter(nm) Volume(% Cumulation(% Diameter(nm) Volume(% Cumulation(% < ) ) < ) ) < ) )
30.00 35.00 40.00 45.00 50.00 55.00 60.00
0.55 0.55 0.55 0.55 3.87 8.84 6.08
0.55 1.10 1.66 2.21 6.08 14.92 20.99
65.00 70.00 75.00 80.00 85.00 90.00 95.00
8.29 5.52 4.97 4.42 5.52 11.05 7.73
122
29.28 34.81 39.78 44.20 49.72 60.77 68.51
100.00 105.00 110.00 115.00 120.00 125.00 130.00
6.08 7.18 3.87 3.31 4.42 2.76 3.87
74.59 81.77 85.64 88.95 93.37 96.13 100.00
Appendix Appendix C Appendix C1 Properties of alumina nanoparticale.
No.
Property
1 2 3 4 5 6 7 8
Molecular formula Molecular Weight (g/mol) Appearance Density Boiling point Crystal structure Hardness (kg/mm2) Dielectric Strength (V/meter)
Al2O3 101.96 g mol−1 White solid 3.9 g/cm3 2977 °C (5.391 °F; 3.250 K) Trigonal 1440 16.9
Appendix C2 Properties of Silicon Carbide nanoparticale.
No.
Property
1 2 3 4 5 6 7 8
Molecular formula Molecular Weight (g/mol) Appearance Density melting point Crystal structure Hardness (kg/mm2) Dielectric Strength (V/meter)
SiC 40,1 light grey powder 3,22 g/cm3 2730°C hexagonal 2800 9.72
Appendix C3 Properties of zirconium oxide nanoparticale.
No.
Property
1 2 3 4 5 6 7 8
Molecular formula Molecular Weight (g/mol) Appearance Density Boiling point Crystal structure Hardness (kg/mm2) Dielectric Strength (V/meter)
123
ZrO2 231.891 g/mol white powder 5.68 g/cm3 4300 °C tetragonal 1100 2–10
اخلالصة: التأكل والحماية من التأكل لسب يكة حديد الفوالذ في ماء ال حر تحققت في هذه الرسبالة .استعملت ثالث أنواع من المواد النبانويبة لحمبايبة حديد الفوالذ وهي كربيد السببببببليكوك ي أوكسببببببيد االلمنيو او أوكسببببببيد الزركونيو النانوية باستخدا تقنية الترسيب بالهجرة االلكترونية لطالء سطح حديد الفوالذ .ودراسة تأثير إضافة تراكيز مختلفة من حامض ال ولي اكرليك في مدى يتراوح ( %)0-1.0في محلول الطالء و دراسة تأثير حامض ال ولي اكرليك على كفاءة الحماية. تم قياس سبببرعة التأكل بالنسبببية لحديد الفوالذ المطلي وال ير المطلي مل المواد النانوية ال.الث .جرى قيباس جهد التآكل ( )Ecorrو تيار التآكل ( )icorrو ميل تافل الكاثودي واالنودي ) (bc,baو كفاءة الحماية ( )٪PEو مقاومة االسببببتقطا ) (Rpومسببببامية السببببطح ومتابعة تأثير ت يير درجات الحرارة على كفاءة الحمبايبة لسبببببب با بك حبديد الفوالذ ال ير مطلية والمطلية بالمواد النانوية بوجود وعد وجود حامض ال ولي اكرليك في درجات حرارة تتراوح ما بين ( 882-892كلفن) .كما تم حسبببا طاقة التنشبببي ( )Eaوعامل التنشبببي )(Aوالمت يرات ال.رموديناميكة االن.ال ي ( )∆Hواالنتروبي ( )∆Sوالطاقة الحرة ( )∆Gلجميل عمليات التأكل. تم تحليل سببببطح حديد الفوالذ المطلي بواسببببطة AFMكشببببفت مورفولوجيا السببببطح اك حجم الدقا لط قة الطالء تراوحت من 01الى 018نانوميتر ،حيث كانت أك ر من الجزيئات ق ل الطالء. تزداد ك.بافبة تيب ار التبأكبل بزيبادة درجة الحرارة لجميل الحاالتي ك.افة تيار التأكل التزلت بعد الطالء بالمواد النانوية المختلفة في غيا ووجود حامض ال ولي اكرليك حيث التزل تيار من ( 002.22مايكرو ام ير لكل سبببنتمتر مربل الى 09.91و82.80و 81.8مايكرو ام ير لكل سبببنتمتر مربل للطالء بواسبببطة كربيد السليكوك و بواسطة أوكسيد الزركونيو و بواسطة أوكسيد االلمنيو على التوالي عند درجة حرارة 892كلفن .بينمبا جهبد التبأكل ا يح الى جهد اك.ر سببببببالب بعد الطالء بالمواد النانوية المختلفة عدا الطالء بواسطة كربيد السليكوك بوجود ( )0.25%من حامض ال ولي اكرليك ا يح نحو الجهود الن يلة. أظهرت كفاءة الحماية لجميل س ا ك حديد الفوالذ المطلية ب يا ووجود حامض ال ولي اكرليك درجة ك يرة من التعزيز ،وتراوحببت بين ( )%99.01-21للطالء بواسببببببطببة كربيببد السببببببليكوك و ()%90-09 للطالء بواسبببببطة أوكسبببببيد الزركونيو و ( )%28.9-88للطالء بواسبببببطة أوكسبببببيد االلمنيو .المسبببببامية السطحية تزداد مل يادة درجة الحرارة في جميل الحاالت. قيم طاقة التنشي لس ا ك حديد الفوالذ المطلية كانت اعلى من س ا ك حديد الفوالذ ال ير مطلية وكانت اعلى قيمة عند طالء سبب ا ك حديد الفوالذ بواسببطة كربيد السببليكوك بوجود ( )0.25%من حامض ال ولي اكرليك ( )80.980كيلوجول لكل مول .قيم الطاقة الحرة لسببببب ا ك حديد الفوالذ المطلية اعلى سبببببال ية من السبب ا ك ال ير مطلية و قيم االن.ال ي لسبب ا ك حديد الفوالذ المطلية بواسببطة أوكسببيد الزركونيو واوكسببيد االلمنيو اقل سال يه من الس ا ك ال ير مطلية لكن الس ا ك المطلية بواسطة كربيد السليكوك اك.ر سال ية.
جمهورية العراق وزارة التعليم العالي والبحث العلمي جامعة بغداد/كلية العلوم قسم الكيمياء
دراسة التأكل واحلماية من التأكل لسبائك من حديد الفوالذ يف ماء
البحر باستخدام دقائق أوكسيد الزركونيوم وكربيد السليكون واوكسيد االملنيوم النانوية
رسالة ماجستير مقدمه إلى كلية العلوم -جامعة بغداد وهي جزء من متطلبات نيل درجة الماجستير في الكيمياء الفيزيائية. تقدم بها:
حيدر عبدالكريم يوسف بإشراف:
أ.د .خلود عبد صاحل 1435 A.H
2014 A.D.
