Fracture toughness of alumina–zirconia composites

The toughening effect in the alumina–zirconia system was simulated by a simple model based on two concentric spheres and a crack in the matrix, near the interface of the inclusion. The effects due to the zirconia t → m phase transformation and the thermal stresses, which develop during the cooling stage of sintering, were also taken into account. The toughening effect was simulated imposing a temperature field both to the matrix and the inclusion and the analysis was carried out at different temperatures. The results of the simulation at room temperature were compared with the experimental data of fracture toughness obtained testing alumina–zirconia composites, containing different percentages of the oxides.