Synergistic effect of graphene and β-Si3N4 whisker enables Si3N4 ceramic composites to obtain ultra-low friction coefficient

This work aimed to further enhance the tribological properties of Si3N4-based ceramics by introducing β-Si3N4 whisker (β-Si3N4w) into multilayer graphene (MLG)/Si3N4 ceramics to inhibit the reduction in the hardness of ceramic matrix induced by MLG. Therefore, the Si3N4 ceramics containing 1 wt% MLG and 1–5 wt% β-Si3N4w were prepared. The tribological properties of specimens at room temperature were evaluated using a ball-disk rotating tribo-tester. The coefficient of friction (COF) and wear resistance of MLG/β-Si3N4w/Si3N4 ceramic composites (MwSNCC) were analyzed. The existence of MLG and β-Si3N4w enabled the dry sliding COF of MwSNCC to notably reduce to 0.04–0.07, which was 89.43–95.40% lower than that of monolithic Si3N4 ceramics, and the wear resistance was enhanced by 33–62.40%.