Mechanisms of friction and wear of metals against ceramics in vacuum

Abstract

For the combinations of five kinds of metallic pin and five kinds of ceramic disk (Al 2O 3, ZrO 2, SiC, Si 3N 4, TiC), a friction and wear test was carried out under unlubricated condition in a vacuum, at a sliding speed of 0.136–0.226 m/s, and under a constant load of 5.0 N. A topographical analysis was also performed on the micro-asperities of the wear surfaces to estimate the behavior of the wear particles, the degree of surface damage and the wear rate. As a result, the following observations were found, (1) a WC pin had the smallest wear rate for TiC, ZrO 2 and Al 2O 3 disks. For SiC and Si 3N 4 disks, the wear rates of each mating Ag and SUS303 pins became small. (2) When the wear particles of pin are transferred to the disks, the greater the amount of the transferred particles, the greater the wear rate of pin becomes. (3) The greater the mean depth of micro-grooves on both pin and disk surfaces, the greater the wear rate becomes. The wear rates of a pin and a disk also depend on the depth of mean line and the tip radius of asperities on a counterface. (4) The mean coefficient of friction increases with an increase in the equivalent depth of mean line.