Shot Peening - A New Method for Improving Mechanical Properties of Structural Ceramics

Shot peening is commonly used to modify material surface layers and improve the strength of metal components. As it occurred the same technique can be applied for brittle ceramics. High compressive stresses up to 2.4 GPa were introduced into near surface region of alumina and zirconia ceramics by ultrasonic shot peening maintaining its surface integrity. Dependence between diameter of tungsten balls, treatment time (at constant mass of balls in the housing and vibration amplitude) and level of compressive stress introduced was determined for both ceramics with nano and micrograins. Coarser grained ceramics was found to be more sensible to structural changes responsible for stress creation than the smaller one. High microplastic deformation in shot peened surface layer of ceramics was observed by X-ray diffraction. An increase of hardness and surface resistance to fracture with increasing level of compressive stress was found.