Composition optimization of chromium carbide based solid lubricant coatings for foil gas bearings at temperatures to 650 C. Final contractor report
A test program to determine the optimum composition of chromium carbide based solid lubricant coatings for compliant gas bearings is described. The friction and wear properties of the coatings are evaluated using a foil gas bearing test apparatus. The various coatings were prepared by powder blending, then plasma sprayed onto Inconel 718 test journals and diamond ground to the desired coating thickness and surface finish. The journals were operated against preoxidized nickel-chromium alloy foils. The test bearings were subjected to repeated start/stop cycles under a 14 kPa (2 psi) bearing unit load. The bearings were tested for 9000 start/stop cycles or until the specimen wear reached a predetermined failure level. In general, the addition of silver and eutectic to the chromium carbide base stock significantly reduced foil wear and increased journal coating wear. The optimum coating composition, PS212 (70 wt% metal bonded Cr3C2, 15 wt% Ag, 15% BaF2/CaF2 eutectic), reduced foil wear by a factor of two and displayed coating wear well within acceptable limits. The load capacity of the bearing using the plasma-sprayed coating prior to and after a run-in period was ascertained and compared to polished Inconel 718 specimens.
- Research Organization:
- Case Western Reserve Univ., Cleveland, OH (USA)
- OSTI ID:
- 6096822
- Report Number(s):
- N-87-26233; NASA-CR-179649; E-3681; NAS-1.26:179649
- Country of Publication:
- United States
- Language:
- English
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Effects of silver and Group II fluorides addition to plasma sprayed chromium carbide high temperature solid lubricant for foil gas bearings to 650/sup 0/C
Effects of silver and group II fluoride solid lubricant additions to plasma-sprayed chromium carbide coatings for foil gas bearings to 650 C
Related Subjects
CHROMIUM CARBIDES
TRIBOLOGY
GAS BEARINGS
SOLID LUBRICANTS
CHEMICAL COMPOSITION
EXPERIMENTAL DATA
FRICTION
PROTECTIVE COATINGS
SILVER ADDITIONS
WEAR
ALLOYS
BEARINGS
CARBIDES
CARBON COMPOUNDS
CHROMIUM COMPOUNDS
COATINGS
DATA
INFORMATION
LUBRICANTS
NUMERICAL DATA
SILVER ALLOYS
TRANSITION ELEMENT COMPOUNDS
360203* - Ceramics
Cermets
& Refractories- Mechanical Properties