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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

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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?

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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

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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

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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.

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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

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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

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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

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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

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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

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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.

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AKNOWLEGMENT

THANK YOU!

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