Tribological Behaviour of Structural Si-Based Ceramics in Fretting Tests at Room Temperature

The friction and wear behaviour of SiC, Si 3 N 4 and SiC/Si 3 N 4 composite ceramics were investigated with oscillating sliding (gross slip fretting) at room temperature. The influence of counter body material and the humidity of the surrounding air was studied with a ball-on-disc configuration with different ball materials (1000Cr6, Al 2 O 3 SiC and Si 3 N 4 ). The effect of RH on friction is marginal with exception of SiC (low friction) as counter body material. The wear behaviour, however, is strongly affected by humidity, showing inverse trends for different counter body materials. Consequently, the wear behaviour of a tribo couple can be improved by selecting an adequate mating material. The results reveal the necessity to control RH in tribological tests. For estimation of the performance of tribo couples under varying environmental conditions, a variation of RH is required. In tribo couples with single phase SiC, either as ball or disc, the tribological behaviour of the system is dominated by SiC. The friction behaviour of the composite material is in between the behaviour of the two single phase materials, Si 3 N 4 and SiC, whereas the wear behaviour is very similar to that of single phase Si 3 N 4 .