Some tribological properties of a carbon-derived Si3N4/SiC nanocomposite

Some tribological properties of a recently developed carbon derived Si3N4/SiC nanocomposite have been investigated in the contribution. The material was tested in the pin-on-disc configuration, with Si3N4 and diamond pins, under unlubricated sliding conditions. The investigated variables were load, sliding distance, and humidity. The measured friction coefficients at 50% humidity and by using a Si3N4 pin were in the range of 0.6–0.7 and 0.05–0.07 when using a diamond pin. The value of this coefficient in vacuum was of about 0.6. A reduction of humidity resulted in lower friction coefficients, but the wear resistance in vacuum was significantly lower than that in air. Increasing the testing temperature (up to 500 °C) increased both, the friction and wear coefficient values. The wear patterns on the Si3N4+SiC disc in the pin-on-disc test with Si3N4 ball revealed presence of the tribochemical reaction layers formed by SiO2. Mechanical fracture was the wear controlling mechanism in all tested conditions.