GOOD AFTERNOON! Tercius Justusa, Priscila Gonçalvesa, Martin Seifertb, Sônia M. H. Probsta,. Günter Motzb, Aloisio N. Kleina a Federal University of Santa ...
GOOD AFTERNOON!
Tercius Justusa, Priscila Gonçalvesa, Martin Seifertb, Sônia M. H. Probsta, Günter Motzb, Aloisio N. Kleina Federal University of Santa Catarina, Mechanical Engineering Department, Materials Laboratory (LabMat), PO Box 476, Br88040-900 Florianópolis, Brazil b University of Bayreuth, Ceramic Materials Engineering (CME), D-95440 Bayreuth, Germany a
EVALUATION OF A POLYMER DERIVED CERAMIC (PDC) ENVIRONMENTAL COMPOSITE BARRIER COATING APPLIED ONTO SINTERHARDENING STEEL
Corrosion processes Metal and alloys in service (thermodynamic instable)
$2.6 trillion of the GDP NACE INTERNATIONAL
Manufacturing processes and Research
Oxides: Thermodynamic stable
Mining, Extractive metallurgy and Metallurgical processing
Oxide ores
3
1) Higher surface area 2) Increased free energy
SINTERED FERROUS METAL PARTS Dry corrosion
Wet corrosion
David Young – High temperature oxidation and corrosion of metals
D. R Gabe – corrosion and protection of sintered metal parts 4
BRAGECRIM PROJECT
• University of Bayreuth - CME (Ceramic Material Engineering) DrIng Günter Motz; • Federal University of Santa Catarina– LabMat - Prof. Dr.-Ing Aloisio Nelmo Klein.
Evaluation of a PDC barrier coating onto a sinter-hardening steel. 5
What are PDCs?
6
PDCS – POLYMER DERIVED CERAMICS PROCESSING
Ternary Systems SixCyNz Polysilazane Carbo-silicon-nitride 400°C
1400°C
Main by-products: Hydrogen, methane and ammonia gaseous release.
>1400°C
7
POLYMER DERIVED CERAMICS Intrinsic chemical and physical-chemical properties of the pure constituting phases: Exceptional oxidation and corrosion stability; Crystallization and creep resistance up to high temperatures;
Increasing % of fillers from figures a to c.
Organic – Inorganic transformation Mass loss up to 50% in weight Polymer - 1g/cm3 Ceramic - 2,3 to 2,8g/cm3
8
EXPERIMENTAL PROCEDURE pressing
1) Sintered Steel
%wt Chemical Composition (%wt) 97.4% Fe1.5Mo – Astaloy Mo Höganäs 2% Nickel – Epson Atmix 0.6% - Graphite 0.8% of lubricant (acrawax Lonza)
mixing
45 min. Sintering
600MPa
Heating rate – 5°C/min. Debinding – 500°C – 30min. Sintering – 1150°C – 60 min.
9
EXPERIMENTAL PROCEDURE 2) PDC Composite Coating Stirring
Stirring
Solvent: Dy-n-Butyl Ether Dispersant: Disperik Zirconium (25 %) (%vol 80) Boron silicate Glass (27.5%) Barium silicate Glass (27.5%) Polysilazane HTT1800 (amorphous SiCN ) Dicumilperoxide (free radical initiator)
Stirring
Spray Coating
Thermal Treatment Heating rate – 3°C/min. Nitrogen Atmosphere Time – 60min
10
COATING THERMAL TREATMENT TEMPERATURE Martin Günthner - Journal of the European Ceramic Society 31 (2011) 3003–3010
700°C 750°C 770°C 800°C Glass Tg (°C) Ta (°C) Ts (°C) Boron 440 570 680 Barium 612 770 850
Tg = vitreous transition Ta = softening temp. Ts = sealing temp 11
RESULTS AND DISCUSSION
12
SINTER HARDENING STEEL MICROSTRUCTURE After sintering: (1150°C) Bainite Retained austenite Martensite Pearlite
Density: *7,06 ± 0,03 g/cm3 Average Densification: *89,4 ± 0,4% *geometric method
97.4% Fe1.5Mo +2%Ni+0.6%C 13
SINTERED STEEL TOPOGRAPHIC CHARACTERIZATION Optical Interferometry Sa = 2,03µm Sq = 3,63µm
Ssk = -2,7 Sku = 12,37 Sp = 11,25µm Sv = 23,37µm Sz = 34,60µm
Ssk – Skewness < 1 peaks removed and presence of valleys Sku – Curtosys > 3 High peaks and deep valleys
Coating Thickness = 38μm Sz + standard deviation = 34.6 + 3.63 = 38.22μm Sz = Sp+Sv = maximum height 14
COATING/SINTERED STEEL INTERFACE CROSS SECTION (SEM – SE)
800°C
750°C 15
OXIDATION TEST RESULTS - BARRIER PROPERTIES
Qualitative method – Prussian Blue; Objective: set coating thermal treatment temperature Quantitative method – Accelerated oxidation Objective: Kinetics characterization 1) Test t (95% of significance) difference between average results 2) Coeficient of variation
16
PRUSSIAN BLUE
700°C
750°C
770°C
800°C
- Sintetic blue pigment - HCl (5 molar) - Potassium ferricyanide K3[Fe(CN)6] 3
𝐹𝑒
+ 𝐹𝑒 𝐶𝑁
↔ 𝐹𝑒
+ 𝐹𝑒(𝐶𝑁)
Coating termal treatment temperature: 770°C and 800°C
17
ACCELERATED OXIDATION Temperature: 450°C Atmosphere: ambient (dry oxidation) Glass Boron Barium
Tg (°C) 440 612
Group 1 2 3 Total
Ta (°C) 570 770
Ts (°C) 680 850
Sintered 3 3 3 9
Sintered – no coating Coated 770°C – coating thermal treated at 770°C Coated 800°C – coating thermal treated at 800°C
Mass Measurement 1 2 3 4 5 6 7
Coated 770°C 3 6 3 12
Time (hours) 0,5 1 2 5 20 60 100
Coated 800°C 3 6 4 13
For accelerated oxidation characterization the samples were completely coated
18
KINECTICS OF OXIDATION Sintered = 13,1mg/cm2
Coated 770°C = 9,46mg/cm2 Coated 800°C = 8mg/cm2
(Test T - 95%)
Coated 770°C
Coated 800°C CV < 10%
CV > 15%
Sintered steel without coating presented a parabolic oxide growing rate : Fe3O4 – parabolic oxidation Sintered steel coated and thermal treated at 700 and 800°C presented a behavior similar to the passivating metals at low temperature. 19
CONCLUSION I was possible to apply a PDC composite containing zirconium and glalss fillers onto a sinter-hardening steel. Coated samples presented 40% less mass gain when compared with uncoated samples. Its necessary to modify glass filler composition in order to achieve higher temperatures for coating thermal treatment.
20
AKNOWLEGMENT
THANK YOU!
21