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 obtained 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 lower concentration of metallic state elements and higher concentration of Cr2O3 and Co(OH)(2) at the surface of X40. The degradation in the wear resistance of X40 at about 500 K was attributed to the decrease in Cr2O3 and Co(OH)(2) concentrations at the surface.