High-temperature wear behavior of micro- and ultrananocrystalline diamond films against titanium alloy

Abstract In the present study, we conducted tribological experiments to study the wear behavior of micro- (MCD) and ultrananocrystalline diamond (UNCD) films against titanium alloy at temperatures up to 700 °C. We found that at comparatively low temperatures (25–500 °C), the wear of diamond films is basically induced by the strong adhesion between diamond and titanium, which promotes the formation of Ti C bonds and detaches the carbon atoms from the diamond surface. When the temperature increases to 600 °C, oxygen starts to significantly etch the diamond films, producing gaseous CO/CO2 and causing more loss of carbon atoms. At 700 °C, the UNCD film is systematically etched by oxygen, and the film is dominated by WO3, with drastically decreased wear resistance. The MCD film still maintains certain wear resistance at 700 °C, but it is also severely etched by oxygen, with substantially shrunk MCD grains. This work provides significant insights into the high-temperature wear behavior of diamond films and the application of diamond-coated cutting tools for machining titanium alloy and other high-cutting-temperature materials.