Transcript Summary of coating integrity and planned testing

Summary of coating integrity and planned
testing
HCAT Program Review
August 2001
Toronto
Keith Legg 847-680-9420
Big bar tests at NAWC, PAX River
#6
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#6, R= -1, WC-Co 0.012”
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#2
Failed at 180 ksi
#2, R= -0.33, WC-Co 0.012”
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Test 1 180 ksi 20 cycle
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Failed at 200 ksi
R= -1, WC-Co 0.003”
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Passed 220 ksi
Very sensitive
to thickness.
Insensitive to R
Big bars not
much different
to small
Keith Legg 847-680-9420
Hill AFB re-optimization
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ThicknessPyrom T Dep rate R-ratio
0.005
220-230
-1.0
0.005
220-230
-1.0
0.015 220-230
-0.33
0.005
165-175
-0.5
0.010 165-175
0.5
0.1
0.005
165-175
0.5
-1.0
0.015 165-175
0.5
-0.5
0.005
165-175
0.5
-0.33
0.005
165-175
0.5
0.1
0.005
165-175
0.5
-1.0
0.005
165-175
0.5
0.1
0.015 165-175
0.5
0.1
0.005
165-175
0.5
-1.0
0.015 165-175
0.5
-0.5
0.005
???
0.2
-0.5
0.015 ???
0.25
-0.5
No Spall ksi Spall ksi
220
190
170
190
240
220
190
190
190
190
180
180
180
180
240
240
180
WC-Co looks good to 240 ksi,
R=-0.5
Note failures at higher substrate
T, lower dep rate
We can make 0.005”, 0.015”
WC-Co coatings that do not
spall at 240 ksi, R=-0.5
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WC-Co, 3 pts
WC-Co fail
No Spall ksi
Spalling Data
Spall ksi
300
250
Max stress, ksi
Ctg Matl
WC-Co
WC-Co
WC-Co
WC-Co
WC-CoCr
WC-Co
WC-Co
WC-Co
WC-CoCr
WC-CoCr
WC-Co
WC-Co
WC-CoCr
WC-Co
WC-Co
WC-Co
200
150
100
50
WC-CoCr
0
-1.1
-1.0
-0.9
-0.8
-0.7
-0.6
-0.5
-0.4
-0.3
-0.2
-0.1
0.0
0.1
R-ratio
Keith Legg 847-680-9420
0.2
Latest data from 40 specimens coated at Southwest
Aero, 0.003”, 100 cycles at each load to 240 ksi
Smax @
R=-0.5
M5-7, WC-CoCr full M5-17, WC-CoCr
patch
M5-28, WC-Co
patch
M5-37, WC-Co full
190
200
Subsurface*
Crack @ 51 cycles
Subsurface
Subsurface
None
None
210
Crack, no spalling
Crack @ 60 cycles
220
Crack, no spalling
Crack, no spalling
Crack @ 85 cycles,
some subsurface
Crack, no spalling
None
Subsurface &
bulging**
Same
230
Crack, no spalling
Crack, no spalling
240
Nf=3046 cycles,
spalling @ fracture
Nf=3004 cycles,
spalling @ fracture
Crack, some
bulging**
Nf=3368 cycles,
spalling
Same
Same
Crack @ 72 cycles,
Nf=3716 cycles
WC-CoCr survived to 240 ksi and exceed Nf
Does this mean WC-CoCr is not a lot more brittle than WC-Co?
Keith Legg 847-680-9420
Ogden ALC A-10 LG bend tests, R=-0.33
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0.010” WC-Co deposited at OO-ALC using new
parameters
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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
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spalled at low load - cause unknown
We can reach 240 ksi with thick coating
Is spalling very sensitive to thickness?
Keith Legg 847-680-9420
Conclusions to date
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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
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deposition conditions (how it is optimized)
coating thickness
Spalling appears not very sensitive to
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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
Keith Legg 847-680-9420
Work to be done
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Additional testing
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Process mapping
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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
Coatings can exceed requirements - let’s make sure we know
how to ensure they always do!
Consideration of rebuild options
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Ensure coating integrity through deposition control
Duplex coatings (alloy build-up, carbide cap)
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e.g. Long Beach Joe Kolek reported Tribaloy does not crack - is
it a good rebuild, or is NiAl better (cc sulfamate Ni)? Keith Legg 847-680-9420