Design and production of ceramic laminates with high mechanical resistance and reliability

A design and processing approach for high failure resistance and increased damage tolerance in laminated ceramic structures is presented. Layers of different compositions are stacked in order to develop a specific residual stress profile by the sintering process. The fracture toughness of the laminate is related to the residual stress. The fracture toughness behaviour can be tailored so that surface defects are forced to grow in a stable way before becoming critical. In this way a ceramic with a unique value of fracture strength is obtained. Laminates composed of alumina/mullite and alumina/zirconia layers have been designed and fabricated. These materials possess a strength of 700 MPa with a standard deviation of <4%. The strength is insensitive to surface damage and in good agreement with the design value.