The current status of SiC/SiC composites and their future prospects

SiC fiber-reinforced SiC matrix composites (SiC/SiC composites) are attractive structural materials for next-generation high-temperature applications, because the density of such a composite is only one third of the conventional heat-resistance one, and it has superior oxidation resistance due to the formation of SiO2 on the surface in the air at elevated temperatures. A research and development activity to realize high efficiency gas turbine materials and aerospace materials replaced CIC composites has been initiated. Continuous fiber-reinforced ceramic composites (CFCC), including SiC/SiC composites, should be showed to prevent crack propagation due to deflection and scattering of micro cracks initiated in the matrix around the interphase. As the crack-opening displacement (COD) is increased, the reinforced fibers should bridge the matrix and they will break after pull out. The apparent fracture resistance can be increased. As a result of this sequence of phenomena, the CFCC shows the better mechanical properties than that of the monolithic ceramics. Therefore, interpretation of the fracture mechanism at the interface between the fibers and the matrix is essential to improve mechanical properties. Currently, many efforts are being made to develop the advanced SiC/SiC composites from "state-of-the-art" materials by a number of research organizations, including universities, national institutes and industries in the world. In this paper, the current status of research and development of SiC/SiC composites is described together with our results of microstructure analysis using advanced microscopy, and future prospects are also discussed.