Characterization of residual compressive stresses in layered ceramics by positron annihilation spectroscopy

Microstructural characterization of stress states of alumina layers subjected to residual compressive stresses was performed by positron annihilation spectroscopy (PAS). Al2O3–t-ZrO2 three layered samples were appropriately designed and processed by sequential slip casting with symmetric structure. The zirconia contents inside the core layer were selected in order to generate compressive stresses of variable intensity in the outer Al2O3 layers. PAS results highlighted a correlation between positron annihilation parameters and microstructural changes related to the generation of residual stresses.