The wear mechanisms of Si-based ceramics are examined in terms of speed and load. The results are presented in wear maps which reveal different regimes of wear. This paper examines the effects of normal force and shear force on Si-based ceramic wear in the different wear regimes. In the mild wear regime, the wear processes are dominated by microabrasion and subsurface cracks. The severe wear regime is dominated by microfracture and tensile cracks on the surface. At still higher loads, surface cracks and gross fracture occur. The presence and the effects of third-body particles on the wear mechanisms are also discussed.Presented at the 50th Annual Meeting in Chicago, Illinois May 14–19, 1995