Fracture Mechanics and Microscopic Residual Stress Analyses of Al2O3-ZrO2/ZrO2 Laminate Ceramics

Brittleness is the greatest fault of ceramics and leads to their low structural reliability. In order to counteract this reliability lack, various processing approaches have been followed, among those approaches is the preparation of laminate materials. When a bending load is applied on a notched bar made of a sequence of Al2O3/ZrO2 and ZrO2 laminate, a tensile stress field is developed around the notch tip, which overlaps the residual stress field developed during fabrication. In this study, a quantitative stress analysis has been performed by piezo-spectroscopic methods to check how the residual stress field contributes to the macroscopic fracture resistance of the laminate material. The influence of the residual stress field on crack propagation is discussed in detail, in comparison with a fracture mechanics evaluation by stable-fracture in bending configuration, and found to be of a remarkable magnitude.