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Summary of coating integrity and planned testing

Summary of coating integrity and planned testing. HCAT Program Review August 2001 Toronto. Big bar tests at NAWC, PAX River. #6, R= -1, WC-Co 0.012” Failed at 180 ksi #2, R= -0.33, WC-Co 0.012” Test 1 180 ksi 20 cycle Failed at 200 ksi R= -1, WC-Co 0.003” Passed 220 ksi. #6.

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Summary of coating integrity and planned testing

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  1. Summary of coating integrity and planned testing HCAT Program Review August 2001 Toronto

  2. Big bar tests at NAWC, PAX River • #6, R= -1, WC-Co 0.012” • Failed at 180 ksi • #2, R= -0.33, WC-Co 0.012” • Test 1 180 ksi 20 cycle • Failed at 200 ksi • R= -1, WC-Co 0.003” • Passed 220 ksi #6 Very sensitive to thickness. Insensitive to R #2 Big bars not much different to small

  3. WC-Co looks good to 240 ksi, R=-0.5 Note failures at higher substrate T, lower dep rate Hill AFB re-optimization • We can make 0.005”, 0.015” WC-Co coatings that do not spall at 240 ksi, R=-0.5 WC-Co, 3 pts WC-Co fail WC-CoCr

  4. S @ M5-7, WC-CoCr full M5-17, WC-CoCr M5-28, WC-Co M5-37, WC-Co full max patch patch R=-0.5 190 Subsurface* Subsurface None None 200 Crack @ 51 cycles Subsurface None Subsurface & bulging** 210 Crack, no spalling Crack @ 60 cycles Crack @ 85 cycles, Same some subsurface 220 Crack, no spalling Crack, no spalling Crack, no spalling Same 230 Crack, no spalling Crack, no spalling Crack, some Same bulging** 240 Nf=3046 cycles, Nf=3004 cycles, Nf=3368 cycles, Crack @ 72 cycles, spalling @ fracture spalling @ fracture spalling Nf=3716 cycles Latest data from 40 specimens coated at Southwest Aero, 0.003”, 100 cycles at each load to 240 ksi WC-CoCr survived to 240 ksi and exceed Nf Does this mean WC-CoCr is not a lot more brittle than WC-Co?

  5. Ogden ALC A-10 LG bend tests, R=-0.33 • 0.010” WC-Co deposited at OO-ALC using new parameters • 500 cycles at loads to 190 ksi • ultrasonic tests showed no delamination • 50 cycles at loads >190 ksi • no spalling at 240 ksi (yield) • coating spalled at 256 ksi (>yield) • 0.015” WC-Co • spalled at low load - cause unknown We can reach 240 ksi with thick coating Is spalling very sensitive to thickness?

  6. Conclusions to date • WC-Co and WC-CoCr can both exceed commercial requirements for OEM coatings (0.003”) • WC-Co can exceed Air Force (land-based aircraft) requirements for rebuild coatings • Spalling appears most sensitive to • deposition conditions (how it is optimized) • coating thickness • Spalling appears not very sensitive to • sample diameter (details of coating morphology) • R ratio (once you get interface cracking it does not need a big push to delaminate) WC-Co looking likely to work for all but high-bend parts

  7. Work to be done • Additional testing • Additional samples and big bar tests at NAWC • New samples and big bar tests at Metcut and AFRL • Bend tests to examine D/T ratios at Hill • Additional A-10 bend tests at Hill • Bending fatigue of large cylinders at Goodrich • Process mapping • Coatings can exceed requirements - let’s make sure we know how to ensure they always do! • Consideration of rebuild options • Ensure coating integrity through deposition control • Duplex coatings (alloy build-up, carbide cap) • e.g. Long Beach Joe Kolek reported Tribaloy does not crack - is it a good rebuild, or is NiAl better (cc sulfamate Ni)?

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