Effect of WS2 particle size on mechanical properties and tribological behaviors of Cu-WS2 composites sintered by SPS

The mechanical properties and tribological behaviors of Cu-WS2 composites fabricated by spark plasma sintering (SPS) using two different WS2 particle sizes of 0.6 and 5.0 mu m and Cu powders as raw materials were investigated. The results indicate that the bending strength and tribological behavior of Cu-WS2 composites are greatly affected by the size of WS2 particles. The bending strength of Cu-WS2 composites with the WS2 particle size of 5.0 mu m is 292.2 MPa. As the size of WS2 particle decreases to 0.6 mu m, the bending strength also decreases to 181.5 MPa. Moreover, as the WS2 particle size decreases from 5.0 to 0.6 mu m, the wear rate of Cu-WS2 composite sharply increases from 2.99x10(-14) to 6.13x10(-14) m(3)/(N.m) and its friction coefficient increases from 0.158 to 0.172. The size of WS2 particle (5.0 mu m) plays an important role in forming transfer film formed on the counter-face. The sample with 5.0 mu m WS2 particle forms smoother and more continuous transfer film, which results in a low wear rate and friction coefficient of the Cu-WS2 composites.