Tribological behavior of W 2C nano-particle reinforced Si 3N 4 matrix composite

Abstract

W 2C nano-particle reinforced Si 3N 4 matrix composite was fabricated by sintering tungsten solution-infiltrated porous Si 3N 4, and the microstructures, sliding wear and micro-tribological behaviors of W 2C–Si 3N 4 composite and sulphided W 2C–Si 3N 4 composite were studied. By incorporating the W 2C nano-particles into the grain boundary phases of Si 3N 4, not only the mechanical properties, but also the tribological behaviors were improved. The W 2C–Si 3N 4 composite showed the lower friction resistance compared with the Si 3N 4, and the W 2C particles had an effect to prevent the wear debris from adhering to the wear scar. After sulphide treatment, the nano-meter sized WS 2 particles were observed from the surface of W 2C–Si 3N 4 composite. The average friction coefficient and specific wear rate of the sulphided W 2C–Si 3N 4 composite were 0.41 and 5.6×10 −6 mm 3/Nm, under dry condition, 34, 47% lower than those for the Si 3N 4, respectively. The micro-tribological behavior of sulphided W 2C–Si 3N 4 composite was evaluated using the lateral force modulation friction force microscope, and the WS 2 particles with very low friction resistance were confirmed from the surface. The formation of the solid lubricant WS 2 on the surface of the W 2C–Si 3N 4 composite lowered both the friction coefficient and specific wear rate, and exhibited self-lubricated behavior during the sliding wear.