CERAMIC-CERAMIC COMPOSITE-MATERIALS WITH IMPROVED FRICTION AND WEAR PROPERTIES

Dry friction and wear tests were performed with self-mated couples of SiC containing 50% TiC0, Si3N4-BN, SiC-TiB2 and Si3N4 with 32% TiN at room temperature and 400-degrees-C or 800-degrees-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-degrees-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 Si3N4-TiN/Si3N4-TiN exhibits high friction coefficients under all test conditions. At room temperature the wear volume of the self-mated couples of Si3N4-TiN after a sliding distance of 1000 m is similar, but Si3N4-TiN shows a running-in behavior. At 800-degrees-C the wear coefficient of Si3N4-TiN/Si3N4-TiN is approximately two orders of magnitude smaller than that of Si3N4/Si3N4, and equal to those at room temperature. At 22-degrees-C the addition of BN reduces the friction of Si3N4. 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-TiB2 above 0.5 m s-1 at 400-degrees-C is advantegeously near 10(-6) mm3 (Nm)-1. With the other test conditions the wear behaviour is similar to SSiC.