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.
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
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
DELORO STELLITE CO. INC. Hardfacing Consumables Powder, Wires, Rods Custom hardfacing Powder metallurgy Components MIM Parts PTA and HVOF Equipment Cast Components
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
HVOF PROCESSES Process 1 Hydrogen Fuel Process 2 Hydrogen Fuel Process 3 Liquid Fuel
Substrate Materials BS EN 10027-1 S355 J2G3.14% carbon Steel (AISI 1018) Bond Strength, Met, wear, corrosion BS 970-1 grade 316S11 Bond Strength BS 970-3 grade 416 Bond Strength After High Temperature Exposure
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
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
Corrosion Performance Electrochemical Polarization - ASTM G61 Artificial Seawater ph of 8.2 1M H 2 SO 4 Salt Spray (Fog) ASTM B117 10 day exposure 5wt % NaCl Atomized Solution Bond Test on Specimens After Exposure
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] 1124 875 980 1268 951 615 434 615-721 Macrohardness, Average 15N (Rc) 93.3 90.0 90.5 94.2 89.9 85.8 83 87-91 (60) Estimated Porosity, As Sprayed, % <.5 <1 <1 <.5 <2 <1 <1 Bond Strength, Average KPSI (per ASTM 633) 10 11.5 10.7 12.3 10.2 6.3 9.9 After Salt Fog Exposure, Average KPSI 0 9.3 10.2 0 0.8 After Seal and Salt Fog Exposure, Average KPSI 8.7 9.2 After High Temp. Exposure, Average KPSI 11.9< Estimated coverage, LB/Ft /. 010 1.3-1.5 0.6 1.3 1.4 0.45 120-150 0.5 Estimated Deposit Efficiency 48-60 53 48-50 <1 60 Est. Surface Finish, Microinch AA -As Sprayed 100-200 100-200 100-200 100-150 120-250.187+ 120-250 -Ground and Lapped <2 <2 <2 <1 4 4 Maximum Coating Thickness, Inches Unknown As-sprayed on cylindrical shapes.187< 0.04< 0.04< 0.015 0.03 1400 Unknown Maximum Coating Thickness, Inches* As-sprayed on flat or irregular shapes.187< 0.04 0.03 0.015 0.015 Unknown Maximum Service Temperature, of 1000 1800 800 1000 1500 1400 Coating Density, g/cm 3 12.8 5.7 13.1 12.7 6.8 7.2 Abrasive Wear Resistance (ASTM G65) mm 3 loss 30 LB load, 2000 revolutions 1.46 3.59 0.84 0.75 4.23 81.6 Slideing Wear (Pin on Disk ASTM G99) AISI 562100 Steel Ball, mm 3 Loss of Coating -, or + Loss of Ball +0.026-0.216 +0.067 +0.026 +0.112-0.408 Average Steady State Friction Coeficient 0.59 0.55 0.61 0.56 0.55 0.61 Wear Track Width using 440-C Steel Ball, microns 240 + 64 Breakaway Friction Coeficient.18 +.02 Steady State Friction Coeficient.75 +.06 Solid Particle Erosion (ASTM G76) Corrosion Tests 50 micron Alumina, 90 o and at Steady State, mg/g.40 +.03 1M H 2 SO 4 Rest Potential (mvsce) -179-276 -227-345 -173 Current (ma/cm 2 ) @ potential = 100mVsce 1.53E-01 1.89E-01 5.11E-03 8.30E-02 7.27E-01 Current (ma/cm 2 ) @ potential = 250mVsce 1.56E-01 1.77E-01 6.58.E-03 5.89E-02 5.06E-01 Current (ma/cm 2 ) @ potential = 400mVsce 1.77E-02 1.72E-01 7.51E-03 5.18E-01 5.18E-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) -451-411 -405-375 -284 Current (ma/cm 2 ) @ potential = 100mVsce 1.30E-02 6.09E-02 5.83E-03 1.99E-01 8.51E-01 Current (ma/cm 2 ) @ potential = 250mVsce 2.23E-02 6.58E-02 7.06E-03 2.25E-01 1.22E-03 Current (ma/cm 2 ) @ potential = 400mVsce 4.61E-01 8.66E-02 8.40E-03 1.30E-01 1.76E-03 Pitting No but Rust Stain No Yes No, but Lines? Yes
Coating Density, g/cm 3 14 12.8 13.1 12.7 12 10 Density, g/cm 3 8 6 5.7 6.8 7.2 4 2 0 WC/17C0 Cr3C2/NiCr WC/12Ni WC/Co/Cr HCP CoCrW
DPH (300g) 1400 1200 1000 800 600 400 200 Coating Hardness Values vs Volume Loss After 2000* Wheel Revolutions of Low Stress Sand Abrasion Tests per ASTM G-65 1124 1.46 875 3.59 980 1268 0.84 0.75 951 4.23 4.5 4 3.5 3 2.5 2 1.5 1 0.5 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
Average Steady State Friction Coeficient 0.62 0.61 0.61 0.61 0.6 0.59 0.59 0.58 0.57 0.56 0.55 0.55 0.56 0.55 0.54 0.53 0.52 WC/17C0 Cr3C2/NiCr WC/12Ni WC/Co/Cr HCP CoCrW
Bond Strength As-Sprayed and Post Salt Fog Exposure Bond Strength, KPSI 14 12 10 8 6 4 2 0 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
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
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
Edge Corrosion, Possible Cause of Drop in Bond Strength
Cross-Section of As-Sprayed WC/Co/Cr vs Post Salt Spray As-Sprayed Post Salt Spray
Cross-Section of As-Sprayed Co/Cr/W vs Post Salt Spray As-Sprayed Post Salt Spray
WC/Co/Cr Sea Water Corrosion Test Results
Sea Water Polarization for HCP Sea Water H 2 SO 4
Sea Water Polarization for WC/Co/Cr Sea Water H 2 SO 4
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
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