Structural parts in gas turbines undergo fretting wear, and as clearances open up, it turns into impact wear. Uncoated cobalt-based substrates that are used in such applications show poor resistance to fretting/impact damage and undergo extensive/unacceptable level of degradation. Commonly used substrate materials such as uncoated cobalt-based materials show poor resistance to fretting/impact wear. This study is focused on assessing the performance of high velocity oxyfuel (HVOF) tungsten carbide (WC) coatings and sintered tungsten carbide inserts as potential solutions for mitigating this issue. Sintered WC12Co with grain size range from 0.2 μm to 4.5 μm and HVOF coating with composition of WC–17%Co was tested. It was found that the HVOF coatings performed better than sintered material and the behavior was attributed to the hard WC particles surrounded by the higher volume fraction of cobalt binder. In the HVOF coating, the normal load was better accommodated by the decarburized WC but a fairly tough binder-surrounding matrix. An additional factor is that the sintered WC had significant volume fraction of undesirable W2C phase, which apparently underwent fracture during the test, thus showing an inferior behavior compared to the HVOF WC coating.

References

References
1.
Morral
,
F. R.
,
Habraken
,
L.
,
Coutsouradis
,
D.
,
Drapier
,
J. M.
, and
Urbain
,
M.
,
1969
, “
Microstructure of Cobalt-Base High-Temperature Alloys
,”
Met. Eng. Q.
,
9
(
2
), pp.
1
16
.
2.
Massalski
,
T. B.
,
Okamoto
,
H.
,
Subramanian
,
P. R.
, and
Kacprzak
,
L.
,
1990
, “
Binary Alloy Phase Diagrams
,”
ASM Int.
,
2
(
2
), pp.
1214
1215
.
3.
Sims
,
C. T.
, and
Hagel
,
W. C.
,
1972
,
The Super Alloys
, Vol.
2
,
Wiley
,
New York
, pp.
145
174
.
4.
Upadhyaya
,
G. S.
,
1999
,
Cemented Tungsten Carbides: Production, Properties and Testing
,
William Andrew Publishing
,
Indian Institute of Technology, Kanpur, India
, Chap. 2.
5.
Dorfman
,
M. R.
,
Kushner
,
B. A.
,
Nerz
,
J.
, and
Rotolico
,
A. J.
,
1989
, “
A Technical Assessment of High-Velocity Oxygen-Fuel Versus High-Energy Plasma Tungsten Carbide–Cobalt Coatings for Wear Resistance
,”
12th International Conference on Thermal Spraying
, pp.
291
302
.
6.
Niemi
,
K.
,
Vuoristo
,
P.
,
Mantyla
,
T.
,
Barbezat
,
G.
, and
Nicoll
,
A. R.
,
1992
, “
Abrasion Wear Resistance of Carbide Coatings Deposited by Plasma and High Velocity Combustion Processes
,”
International Thermal Spray Conference Exposition
,
Orlando, FL
, pp.
685
689
.
7.
Nerz
,
J.
,
Kushner
,
B.
, and
Rotolico
,
A.
,
1990
, “
Effects of Deposition Methods on the Physical Properties of Tungsten Carbide 12 wt. % Cobalt Thermal Spray Coatings
,”
Protective Coatings: Processing and Characterization
,
R. M.
Yazici
, ed.,
The Minerals, Metals and Materials Society
,
Warrendale, PA
, pp.
135
143
.
8.
Villiers Lovelock
,
H. L.
,
Richter
,
P. W.
,
Benson
,
J. M.
, and
Young
,
P. M.
,
1998
, “
Parameter Study of HP/HVOF Deposited WC-Co Coatings
,”
J. Therm. Spray Technol.
,
7
(
1
), pp.
97
107
.
9.
Chu
,
H. S.
,
Liu
,
K. S.
, and
Yeh
,
J. W.
,
2000
, “
An In Situ Composite of Al (Graphite, Al4C3) Produced by Reciprocating Extrusion
,”
Mater. Sci. Eng. A
,
277
(
1–2
), pp.
25
32
.
10.
Bayer
,
R. G.
,
1994
,
Mechanical Wear Prediction and Prevention
,
Marcel Dekker
,
New York
, pp.
90
91
.
11.
Schwetzke
,
R.
, and
Kreye
,
H.
,
1998
, “
Microstructure and Properties of Tungsten Carbide Coatings Sprayed With Various HVOF Spray Systems
,”
15th International Thermal Spray Conference
,
Nice, France
, pp.
187
192
.
12.
Guilemany
,
J. M.
,
Dosta
,
S.
,
Nin
,
J.
, and
Miguel
,
J. R.
,
2005
, “
Study of the Properties of WC-Co Nanostructured Coatings Sprayed by High-Velocity Oxyfuel
,”
J. Therm. Spray Technol.
,
14
(
3
), pp.
405
413
.
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