Effects of load on tribological properties of B₄C and B₄C-SiC ceramics sliding against SiC balls

Pressureless sintered B4C and B4C-SiC ceramics were subjected to tests of dry sliding against SiC balls at 5 N, 10 N and 20 N. The effects of load on the respective tribological properties of B4C and B4C-SiC ceramics were studied. Meanwhile, the tribological properties and friction, wear mechanisms of B4C and B4C-SiC ceramics at different loads were compared. Both the friction coefficient and wear rate of B4C ceramics first decreased and then increased with increases in load, while both the friction coefficient and wear rate of B4C-SiC ceramics increased with increases in load. At low load, the B4C-SiC ceramics showeda lower friction coefficient and wear rate. At intermediate load, the B4C ceramics showed a lower friction coefficient, and no difference between the wear rates of B4C and B4C-SiC ceramics was apparent. At high load, the B4C ceramics showed a lower friction coefficient, while the B4C-SiC ceramics showed a lower wear rate. With increases in load from 5 N to 20 N for the B4C ceramics, the wear mechanism changed from adhesive wear to delamination and spalling of tribofilm; for the B4C-SiC ceramics, meanwhile, the wear mechanism changed from surface polishing and mild abrasion to micro-fracture.