Strengthening of silicon nitride ceramics by shot peening

Shot peening is a common procedure for improving the static and cyclic strength of metal components by a combination of work hardening and the introduction of compressive stresses into the surface region. Recent investigations showed that high compressive stresses of more than 1 GPa can also be introduced in brittle ceramics such as alumina and silicon nitride under specific shot peening conditions. These stresses dramatically increase the near-surface strength. This paper compiles the current state of the art of shot peening for silicon nitride ceramics. Detailed information about the influence of shot peening on the residual stress state, dislocation density and damage are given. The effect of the residual stresses on the static and cyclic near-surface strength is quantified.