ELEVATED-TEMPERATURE WEAR MAPS OF X40 AND MAR-M247 ALLOYS

Self-mated wear tests of X40 (Cobalt-base alloy) and Mar-M247 (Nickel base alloy) were conducted under unlubricated sliding conditions using a pin-on-disk tester. Wear maps were constructed for both alloys over the temperature range of room temperature to 1173 K at relatively low sliding speed. Microstructural and chemical information has been obta ined by using various microscopies, an X-ray diffractometer, and an X- ray photo-electron spectroscopy. They show that the wear resistance of X40 is superior to that of Mar-M247 at room temperature due to the lo wer concentration of metallic state elements and higher concentration of Cr2O3 and Co(OH)(2) at the surface of X40. The degradation in the w ear resistance of X40 at about 500 K was attributed to the decrease in Cr2O3 and Co(OH)(2) concentrations at the surface.