High temperature tribological behaviors of aluminum matrix composites reinforced with solid lubricant particles

The AA6061-10wt.%B4C mono composite, AA6061-10wt.%B4C-Gr (Gr: graphite) hybrid composites containing 2 5, 5, and 7.5 wt.% Gr particles, and AA6061-10wt.%B4C-MoS2 hybrid composites containing 2 5, 5, and 7.5 wt.% MoS 2 particles were fabricated through stir casting. The dry sliding tribological behaviors of the mono composite and hybrid composites were studied as a function of temperature on high temperature pin-on-disc tribotester against EN 31 counterface. The wear rate and friction coefficient of the Gr-reinforced and MoS2 -reinforced hybrid composites decreased in the temperature range of 30-100 degrees C due to the combined lubrication offered by the wear protective layer and its solid lubricant phase. Scanning electron microscopy (SEM) observation of the worn pin surface revealed severe adhesion, delamination, and abrasion wear mechanisms at temperatures of 150, 200, and 250 degrees C, respectively. At 150 degrees C, transmission electron microscopy (TEM) observation of the hybrid composites revealed the formation of deformation bands due to severe plastic deformation and fine crystalline structure due to dynamic recrystallization.