Strength and residual stress of Mg-PSZ after grinding

Abstract

The influence of grinding with two grinding wheels, differing mainly in diamond-grain size, on the properties of Mg-PSZ was examined. The residual stress, the amount of monoclinic zirconia and the strength of the material were determined. From these measurements depth profiles were obtained for the phase content and the residual stress. The fracture surfaces were examined optically to estimate the critical flaw size. Material ground with “coarse” diamond grains was significantly weaker than that ground with “fine” diamond grains. “Coarse” diamond grains in the grinding wheel resulted in more residual stress and a thicker layer of transformed zirconia than when “fine” grains were in the wheel. This apparent discrepancy is explained with a model based on the occurrence of localized spots of tensile stress beneath the residual stress layer near grain boundaries. These spots are assumed to be larger in number and to contain higher tensile stresses after grinding with “coarse” grains.