Effect of carbon on the microstructure and sliding wear performance of CoCrMo matrix composites from room temperature to 1000 °C

Abstract This work aimed to fabricate the CoCrMo matrix composites with different carbon contents, and the carbon content was optimized to achieve the good mechanical and tribological properties from room temperature to 1000 °C. Four composites containing different carbon content (0, 0.3 wt.%, 0.6 wt.% and 1 wt.%) were fabricated by powder metallurgy technology. Microstructure and tribological properties were studied. Friction behaviors were conducted on a disc-on-ball tribotester rubbing against Si3N4 ball. The carbon greatly improved the wear resistance of CoCrMo matrix composites due to the strengthening effect of carbides (Cr7C3 and Mo3Co3C) and the dense oxides film. However, the friction coefficient slightly increased. There was a critical value of carbon content for hardness and high-temperature friction and wear behaviors. The composite with 0.6 wt.% carbon had the most favorable tribological behaviors from RT to 1000 °C. Four composites showed different friction mechanisms.