SLIDING MICROINDENTATION FRACTURE OF BRITTLE MATERIALS

The sliding indentation of ceramics by sharp rigid indenters is considered. A diamond conical indenter is used to scribe borosilicate and fused-silica glasses. The coefficient of friction and the median vent crack depth are measured. It is found that active lubricants are useful for controlling the friction and the vent crack depths. The principles of fracture are used to calculate stress intensity factors for surface-breaking cracks loaded by normal and frictional scribing forces. The implications of the results to the evolution of grinding-induced cracks in ceramics is discussed.