Grinding Mechanisms and Strength Degradation for Ceramics

This paper presents a critical review and evaluation of our fundamental knowledge of the grinding mechanisms for ceramic materials and their influence on the finished surface and mechanical properties. Two main research approaches are identified: a “machining” approach and an “indentation fracture mechanics” approach. The machining approach has typically involved measurement of the grinding forces and specific energy coupled with microscopic observations of the surface morphology and grinding detritus. Any proposed mechanisms of abrasive-workpiece interaction must be consistent with the magnitude of the specific energy and its dependence on the grinding conditions. The “indentation fracture mechanics” approach assumes that the damage produced by grinding can be modeled by the idealized flaw system produced by a sharp indentor. Indentation of a ceramic body is considered to involve elastic/plastic deformation with two principal crack systems propagating from the indentation site: lateral cracks which lead to material removal and radial/median cracks which cause strength degradation. Each of these approaches provides important insight into grinding behavior and strength degradation, but each has its shortcomings. Further efforts to develop a fundamental model for grinding of ceramics would benefit from the integration of both of these approaches.