Effects of load and hydrostatic pressure on tribological characteristics of Si3N4 ceramic at 120°C in water

The effects of load and hydrostatic pressure on the tribological characteristics of Si3N4 ceramic sliding on itself were investigated at 120° in water under the hydrostatic pressures of 0.2 and 10MPa. The friction coefficients and specific wear rates at 0.2MPa were larger than those at 10MPa. Both values increased with increasing the loads and saturated at about 60N under 0.2 and 10MPa, resulting in the appearance of the microfracture and production of H2 in addition to NH3. The mechanisms of the hydrothermal oxidation and microfracture of the Si3N4 ceramic are discussed.