Mullite/zirconia laminate composites for high temperature application

Mullite/zirconia laminate composites were studied for a better understandin g of crack formation and crack propagation behavior at the interface of lam inates. The laminate composites were fabricated by tape casting method and hot-pressing. It was demonstrated that the thermal mismatch stress was clos ely related to the crack formation and crack deflection behavior in the mul lite/zirconia laminate composites. Two kinds of cracks were observed in zir conia layers; one is channel cracks in layers subjected to tensile stress, the other is the edge cracks in layers subjected to compressive stress. Amo ng three forms of zirconia (monoclinic, tetragonal, cubic) tetragonal zirco nia was effective to deflect the crack at the interface due to the stress i nduced tetra-mono phase transformation. (C) 2000 Published by Elsevier Scie nce Ltd. All rights reserved.