FRICTIONAL CHARACTERISTICS OF CERAMICS UNDER WATER-LUBRICATED CONDITIONS

Friction experiments were conducted on four kinds of ceramics (SiC, Si 3N4. Al2O3 and ZrO2) against themselves in water under different conta ct pressures and sliding velocities. The variations of friction coeffi cients as a function of sliding distance, and the effects of mean cont act pressure and sliding velocity on friction coefficients were shown. Friction coefficients lower than 0.03 were observed under a certain c ombination of mean contact pressure and sliding velocity for each mate rial. The friction coefficient suddenly increased when the mean contac t pressure was above a threshold value, which depended on both sliding velocity and the material of sliding pairs. SiC had a higher threshol d value than the other three ceramics at every sliding velocity invest igated.