Performance Testing of HVOF Coatings and Comparison with Hard Chrome Plate (HCP)

Transcription

1 Performance Testing of HVOF Coatings and Comparison with Hard Chrome Plate (HCP) HCAT/CHCAT Meeting December 14, 2000 by David Lee Deloro Stellite Co. Inc. - Stellite Coatings Div.

2 Program Participants Deloro Stellite Co. Inc. Deloro Stellite Ltd., Swindon, England Simon Rose Colin Arrow Deloro Stellite USA Jim Wu Damodaran Raghu Kathy Schlegelmeltch David Lee The Welding Institute (TWI) UK Carole Reigner A. J. Sturgeon

3 DELORO STELLITE CO. INC St. Louis, USA Shanghai Stellite, PRC Deloro Stellite Ltd. UK Deloro Stellite Inc. Canada Microfusione Stellite Stellite Coatings. USA Deloro Stellite GmbH, Germany Hettiger Stellite

4 DELORO STELLITE CO. INC. Hardfacing Consumables Powder, Wires, Rods Custom hardfacing Powder metallurgy Components MIM Parts PTA and HVOF Equipment Cast Components

5 Alloys Evaluated WC/10Co/4Cr - JK120H WC/17Co - JK117 WC/12Ni - JK6189 Cr 3 C 2 /25NiCr - JK135 CoCrW (6) - JK576 NiCrMo (C) -JK591H HCP - APTICOTE 100N

6 HVOF PROCESSES Process 1 Hydrogen Fuel Process 2 Hydrogen Fuel Process 3 Liquid Fuel

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8 Substrate Materials BS EN S355 J2G3.14% carbon Steel (AISI 1018) Bond Strength, Met, wear, corrosion BS grade 316S11 Bond Strength BS grade 416 Bond Strength After High Temperature Exposure

9 Bond Strength ASTM C633 Coating Properties Micro (300g DPH) and Macro (15N) Hardness Values Microstructure Analysis Porosity, Oxides and Coating Defects Density Measurement (for wear test) ASTM B328

10 Wear Performance Evaluation Abrasive Wear - ASTM G65 Low Stress Dry Sand Rubber Wheel Metal to Metal Sliding Wear - ASTM G99 Pin-on-Disk Weight Loss/Gain of Coating and Ball (AISI 52100) Coefficient of Friction

11 Corrosion Performance Electrochemical Polarization - ASTM G61 Artificial Seawater ph of 8.2 1M H 2 SO 4 Salt Spray (Fog) ASTM B day exposure 5wt % NaCl Atomized Solution Bond Test on Specimens After Exposure

12 JK117 JK135 JK6189 JK120H Cr Plate JK576 JK591H T-400 WC/17C0 Cr 3 C 2 /NiCr WC/12Ni WC/Co/Cr HCP CoCrW NiCrMo CoMoCrSi Microhardness, Average DPH [300g] Macrohardness, Average 15N (Rc) (60) Estimated Porosity, As Sprayed, % <.5 <1 <1 <.5 <2 <1 <1 Bond Strength, Average KPSI (per ASTM 633) After Salt Fog Exposure, Average KPSI After Seal and Salt Fog Exposure, Average KPSI After High Temp. Exposure, Average KPSI 11.9< Estimated coverage, LB/Ft / Estimated Deposit Efficiency <1 60 Est. Surface Finish, Microinch AA -As Sprayed Ground and Lapped <2 <2 <2 <1 4 4 Maximum Coating Thickness, Inches Unknown As-sprayed on cylindrical shapes.187< 0.04< 0.04< Unknown Maximum Coating Thickness, Inches* As-sprayed on flat or irregular shapes.187< Unknown Maximum Service Temperature, of Coating Density, g/cm Abrasive Wear Resistance (ASTM G65) mm 3 loss 30 LB load, 2000 revolutions Slideing Wear (Pin on Disk ASTM G99) AISI Steel Ball, mm 3 Loss of Coating -, or + Loss of Ball Average Steady State Friction Coeficient Wear Track Width using 440-C Steel Ball, microns Breakaway Friction Coeficient Steady State Friction Coeficient Solid Particle Erosion (ASTM G76) Corrosion Tests 50 micron Alumina, 90 o and at Steady State, mg/g M H 2 SO 4 Rest Potential (mvsce) Current (ma/cm 2 potential = 100mVsce 1.53E E E E E-01 Current (ma/cm 2 potential = 250mVsce 1.56E E E E E-01 Current (ma/cm 2 potential = 400mVsce 1.77E E E E E-01 Pitting No but Rust Stain No Yes No, but Lines? Yes Obsevered Ring (Outside Test Area) Yes Yes No No, but Lines? No Artificial Sea Water (5% NACl) Rest Potential (mvsce) Current (ma/cm 2 potential = 100mVsce 1.30E E E E E-01 Current (ma/cm 2 potential = 250mVsce 2.23E E E E E-03 Current (ma/cm 2 potential = 400mVsce 4.61E E E E E-03 Pitting No but Rust Stain No Yes No, but Lines? Yes

13 Coating Density, g/cm Density, g/cm WC/17C0 Cr3C2/NiCr WC/12Ni WC/Co/Cr HCP CoCrW

14 DPH (300g) Coating Hardness Values vs Volume Loss After 2000* Wheel Revolutions of Low Stress Sand Abrasion Tests per ASTM G Volume loss, mm 3 0 WC/17C0 Cr3C2/NiCr WC/12Ni WC/Co/Cr HCP Microhardness, Average AlloyDPH [300g] *Normalized Abrasive Wear Resistance (ASTM G65) mm3 loss 0

15 Average Steady State Friction Coeficient WC/17C0 Cr3C2/NiCr WC/12Ni WC/Co/Cr HCP CoCrW

16 Bond Strength As-Sprayed and Post Salt Fog Exposure Bond Strength, KPSI E Not Tested Not Tested E Too Corroded E/A E Not Tested Not Tested WC/17C0 Cr3C2/NiCr WC/12Ni WC/Co/Cr HCP CoCrW Alloy E E/C E E A Lifted during Salt Spray Lifted during Salt spray Failure Mode E- Epoxy C-Cohesive A-Adhesive Bond Strength, Average KPSI (per ASTM 633) After Salt Fog Exposure, Average KPSI After Seal and Salt Fog Exposure, Average KPSI

17 Bond Specimens after Salt Fog Exposure Cr 3 C 2 /NiCr As-sprayed Cr 3 C 2 /NiCr with Sealer Co/Cr/W As-sprayed

18 Bond Specimens after Salt Fog Exposure and Pulled WC/Co/Cr As-sprayed WC/Co/Cr with Sealer Cr 3 C 2 /NiCr with Sealer

19 Edge Corrosion, Possible Cause of Drop in Bond Strength

20 Cross-Section of As-Sprayed WC/Co/Cr vs Post Salt Spray As-Sprayed Post Salt Spray

21 Cross-Section of As-Sprayed Co/Cr/W vs Post Salt Spray As-Sprayed Post Salt Spray

22 WC/Co/Cr Sea Water Corrosion Test Results

23 Sea Water Polarization for HCP Sea Water H 2 SO 4

24 Sea Water Polarization for WC/Co/Cr Sea Water H 2 SO 4

25 Conclusions Abrasion Wear resistance of WC bearing alloys is 3-6 times that of HCP Salt spray exposure appears to affect bond strength of the HVOF coatings presented Sealing Cr 3 C 2 /NiCr is necessary for applications exposed to NaCl solutions

26 Conclusions Continued Corrosion of edges of HVOF coating may require sealing or corrosion resistant substrates be used for exposure to NaCl solutions Future study is underway to determine if the edges of the coatings better sealed can improve the coating bond strength after salt spray exposure