Tribological behavior of W2C nano-particle reinforced Si3N4 matrix composite

W2C nano-particle reinforced Si3N4 matrix composite was fabricated by sintering tungsten solution-infiltrated porous Si3N4, and the microstructures, sliding wear and micro-tribological behaviors of W2C–Si3N4 composite and sulphided W2C–Si3N4 composite were studied. By incorporating the W2C nano-particles into the grain boundary phases of Si3N4, not only the mechanical properties, but also the tribological behaviors were improved. The W2C–Si3N4 composite showed the lower friction resistance compared with the Si3N4, and the W2C particles had an effect to prevent the wear debris from adhering to the wear scar. After sulphide treatment, the nano-meter sized WS2 particles were observed from the surface of W2C–Si3N4 composite. The average friction coefficient and specific wear rate of the sulphided W2C–Si3N4 composite were 0.41 and 5.6×10−6 mm3/Nm, under dry condition, 34, 47% lower than those for the Si3N4, respectively. The micro-tribological behavior of sulphided W2C–Si3N4 composite was evaluated using the lateral force modulation friction force microscope, and the WS2 particles with very low friction resistance were confirmed from the surface. The formation of the solid lubricant WS2 on the surface of the W2C–Si3N4 composite lowered both the friction coefficient and specific wear rate, and exhibited self-lubricated behavior during the sliding wear.