Crack deflection in ceramic laminates using porous interlayers

Ceramic laminates have been made from alternating layers of silicon carbide and silicon carbide containing a fugitive polymer, which can be pyrolysed to produce porous interlayers. It is shown that such interlayers can be use d to deflect cracks and that the volume fraction of porosity, due to the ad ded polymer, that is required to cause crack deflection is approximately 0. 4. A simple model has been developed which describes the fracture behaviour of porous solids and also predicts the volume fraction of porosity require d to give crack deflection in the laminate and which is in good agreement w ith experiment. (C) 1998 Elsevier Science Limited. All rights reserved.