WEAR AND FRICTION OF Y-TZP SPHERES RECIPROCATING AGAINST VARIOUS SIALON PLATES

The friction and wear characteristics of various Y-TZP sialon sliding systems were examined. These systems consisted of a Y-TZP sphere recip rocating against various sialon plates. The sialons differed in phase content and composition. They range from alpha-sialons to beta-sialons and include alpha-beta composites. The length of the wear tracks was 1 0 mm, the loads used were 2 and 8 N, the frequencies 1, 4 and 8 Hz a nd the humidity was controlled by flushing with dry nitrogen. The test s were continued for 8, 24 and 72 h at room temperature. The total ver tical displacement and the friction coefficient were measured continuo usly and sampled. Various additional measurements were performed after each test and the worn surfaces were observed microscopically. It was concluded that the alpha-beta composites show less wear than the alph a- and beta-sialons. It was also concluded that the amount of wear inc reases approximately linearly with load and increases significantly mo re than linearly with frequency. A wear mechanism was derived incorpor ating the measured data and the observations,