Threshold strength evaluation on an Al2O3-ZrO2 multilayered system

The fracture behaviour of an alumina-zirconia multilayered ceramic obtained by slip casting has been evaluated and compared to monolithic alumina taken as a reference. It is found that the laminated system exhibits an apparent fracture toughness K-apt,K-c, calculated experimentally (SEPB) and analytically with a weight function approach, higher than twice the value determined for the monolithic material. Additionally, the experimental rupture tests accomplished indicate the existence of a threshold strength in the multilayer. The increase in K-apt,K-c in the laminate, associated with a pronounced R-curve behaviour, is discussed in terms of the high compressive stresses in the internal layers and their effect on the effective driving force for crack extension. (c) 2006 Elsevier Ltd. All rights reserved.