Tribology of carbon layers fabricated from SiC exposed to different H-2/Cl-2 gas mixtures

Abstract

Silicon carbide-based ceramics are some of the best materials for tribological applications. However, their tribological properties still need to be improved for certain uses under severe conditions. In this study, carbon layers were produced by the exposure of ball and disc type SiCs to various compositions of chlorine-hydrogen gas mixtures at a temperature of 1000 degrees C for 20 firs. After the chlorination of the silicon carbide materials, the modified layers were characterized by XRD, Raman, and FE-SEM. The effect of the hydrogen gas content on the carbide-derived carbon (CDC) layers and their resulting tribological properties have been investigated. The tribological behaviors of the CDC layers were studied using a ball-on-disk tribometer. Silicon nitride and chlorinated silicon carbide balls were selected as the counterpart material. The results showed that the wear resistance and frictional coefficients of the surface-modified ball and disk-type SiCs were significantly improved compared to those of untreated silicon carbide specimens. Increasing the hydrogen content of the gas mixture improved the tribological performance of the resulting carbon layers. The use of a higher applied load also improved the tribological performance. The possible mechanisms responsible for the tribological properties of the carbon layers are discussed.