Effect of superficial residual stresses in abrasive wear resistance of Al2O3 /Al2O3+3Y-TZP multilayers

Multilayered composite specimens consisting of Al2O3 / Al2O3+ 3Y-TZP (A/AZ) layers with different compositions and thicknesses were prepared starting from ceramic sheets obtained by tape casting. Residual stresses arisen from mismatch in thermal expansion coefficient during sintering were evaluated using luminescence piezo-spectroscopy. The stress in the superficial A layer was found to be compressive, and its value depended on the ratio between thickness of A and AZ layer. The influence of the superficial compressive stress on the abrasive wear resistance was investigated using microscale ball cratering test; results were correlated with the superficial compressive stress and compared with a specimen of pure unstressed Al2O3 prepared both by lamination and by cold isostatic pressing. Experiments show an improvement of performances in the samples containing compressive residual stress in the surface.