High temperature stability of the matrix-fibre interface in a SiC/SiC composite

Abstract

The intrinsic brittleness, or low resistance to crack propagation, characteristic of most ceramic materials severely restricts their use and applications. There is great interest, and much research effort is being invested, in developing methods to improve the fracture toughness of ceramics. Amongst these methods the reinforcement of ceramic materials with high strength fibers is believed to offer great potential. The increase in toughness which can be achieved by means of fiber reinforcement arises from both crack deflection at the fiber-matrix interface and from bridging of the crack faces by unbroken fibers. The effectiveness of these processes depends strongly on the strength of the fiber-matrix interface. An efficient way of tailoring the strength of fiber-matrix interfaces in ceramic matrix composites is to form a thin layer of adequate shear strength around the fibers. The principal challenge is to identify a coating material, which has the necessary mechanical properties and is also stable in the working environment and at elevated temperatures. The thermal stability of fiber, matrix and interface should therefore be fully investigated. The purpose of this paper is to investigate the high temperature stability of the carbon coating interface, and its effect on mechanical properties, in a SiC fiber-SiC matrixmore » composite.« less