Mechanical characterization of Al2O3/ZrO2 hybrid laminates

Significant residual stresses due to the thermal expansion mismatch were found in the Al3O3/Ce-ZrO2 laminated composites investigated in this study. The residual stresses were measured by evaluating the difference in indentation crack length, with and without the residual stresses. The obtained residual stress values are in good agreement with the calculated residual stresses from the measured coefficients of thermal expansion and elastic constants. The laminated structure was found to give rise to an increase in indentation strength compared to monolithic alumina. This apparent increase in fracture toughness can be explained as the effect of the compressive residual stress in the outer Al2O3 layer and can be controlled by changing the relative layer thickness. I;or the size scale studied here, the zirconia-based layers did not appear to play a major role in the final failure process. (C) 1998 Elsevier Science Limited. All rights reserved.