Processing and mechanical properties of a silicon carbide platelet/alumina matrix composite

Abstract

Abstract This paper presents an integrated study of the processing and mechanical properties of a SiC platelet/alumina composites. The major goal was to investigate the potential application of plate-like particles in toughening ceramic matrices. In the processing part of the study, the microstructures were found to possess preferred platelet orientation, with the platelets tending to lie parallel to each other after hot-pressing. In the mechanical property part of the study, Young's modulus, fracture toughness, flexural strength, and R-curve behavior were measured as a function of platelet content. It was determined that the preferred orientation did not lead to significant elastic anisotropy but it did lead to toughness anisotropy. Indeed the platelets led to a decrease in fracture toughness for crack propagating parallel to the platelet faces. In addition, it was found that the platelets also led to a strength decrease compared to the alumina. The optimum properties were a Young's modulus of 421 GPa, fracture toughness of 7·1 MPa√m, and a flexural strength of 480 MPa at SiC volume fraction of 0·3. Overall, it was concluded that with controlled processing SiC platelets are strong candidates for reinforcing ceramic matrices but that further development is needed.