Ceramic-ceramic composite materials with improved friction and wear properties

Abstract

Dry friction and wear tests were performed with self-mated couples of SiC containing 50% TiC, Si 3N 4BN, SiCTiB 2 and Si 3N 4 with 32% TiN at room temperature and 400°C or 800°C. Under room temperature conditions, the friction coefficient of the couple SiCTiC/SiCTiC is only half of that of the couple SiC/SiC and the wear is one order of magnitude smaller. At 400°C, it exceeds the friction coefficient of SiC/SiC except at the highest sliding velocity of 3 m s −1. At lower sliding velocities the wear coefficient of SiCTiC/SiCTiC is lower than that of SiC/SiC. The couple Si 3N 4TiN/Si 3N 4TiN exhibits high friction coefficients under all test conditions. At room temperature the wear volume of the self-mated couples of Si 3N 4 and Si 3N 4TiN after a sliding distance of 1000 m is similar, but Si 3N 4TiN shows a running-in behaviour. At 800°C the wear coefficient of Si 3N 4TiN/Si 3N 4TiN is approximately two orders of magnitude smaller than that of Si 3N 4/Si 3N 4, and equal to those at room temperature. At 22°C the addition of BN reduces the friction of Si 3N 4. The wear coefficient is independent of sliding velocity and the self-mated couples showing running-in. Friction and wear increase with increasing temperature. The wear coefficient of SiCTiB 2 above 0.5 m s −1 at 400°C is advantageously near 10 −6 mm 3 (Nm) −1. With the other test conditions the wear behaviour is similar to SSiC.