Effects of atmosphere on the tribological properties of a chromium carbide based coating for use to 760/sup 0/C

Conference · Thu Jan 01 04:00:00 EST 1987

OSTI ID:6805715

DellaCorte, C; Sliney, H E

The coating contains bonded chromium carbide as the wear resistant ''base stock'' to which the lubricants silver and barium fluoride/calcium fluoride eutectic are added. It has been denoted as NASA PS200. Potential applications for the PS200 coating are cylinder wall/piston ring couples for Stirling engines and foil bearing journal lubrication. Friction and wear studies were performed in helium, hydrogen, and moist air at temperatures from 25 to 760/sup 0/C. Specimens tested in hydrogen, a reducing environment, exhibited the best tribological properties. Friction and wear increased in helium and air but are still within acceptable limits for intended applications. As the test atmosphere becomes less reducing, the coating experiences a higher concentration level of chromic oxide at the sliding interface which increases both the friction and wear. Beneficial silver transfer from the parent coating to the counterface material is less effective in air than in helium or hydrogen. There may be a direct relationship between chromic oxide level present at the sliding interface and the friction coefficient.

• Research Organization: National Aeronautics and Space Administration, Cleveland, OH (USA). Lewis Research Center
• DOE Contract Number: AI01-86CE50162
• OSTI ID: 6805715
• Report Number(s): DOE/NASA/50194-44; NASA-TM-88894; CONF-870510-2; ON: DE87003289
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360203* -- Ceramics
Cermets
& Refractories-- Mechanical Properties
AIR
ALKALINE EARTH METAL COMPOUNDS
ATMOSPHERES
BARIUM COMPOUNDS
BARIUM FLUORIDES
CALCIUM COMPOUNDS
CALCIUM FLUORIDES
CALCIUM HALIDES
CARBIDES
CARBON COMPOUNDS
CHROMIUM CARBIDES
CHROMIUM COMPOUNDS
COATINGS
ELEMENTS
FLUIDS
FLUORIDES
FLUORINE COMPOUNDS
FRICTION
GASES
HALIDES
HALOGEN COMPOUNDS
HELIUM
HYDROGEN
LUBRICANTS
METALS
MOISTURE
NONMETALS
RARE GASES
SILVER
SPRAYED COATINGS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
TRIBOLOGY
WEAR