Influence of machining-induced residual stresses on the strength of ceramics

Micro- and macroscopic residual stresses, phase transformations and strength of machined ceramics were examined using X-ray diffraction techniques and bending tests. The results allow to separate the effects of damage processes and macroscopic residual stresses on the strength of ceramics and therefore to optimize the machining parameters. In the case of lapping of alumina and grinding of alumina and PSZ surface damage is the dominating effect on strength, whereas transformation-induced compressive surface stresses prevail against damage effects using severe lapping conditions for PSZ.