Electron Microscopy and Microanalysis of the Fiber, Matrix and Fiber/Matrix Interface in SiC Based Ceramic Composite Material for Use in a Fusion Reactor Application

Abstract

Composite materials are engineered materials made from two or more constituent materials. They have significantly different physical or chemical properties which remain separate and distinct on a macroscopic level within the finished structure. The advantage of composite material is that they exhibit the best qualities of their components or constituents and often some qualities that neither constituent possesses. The properties that can be improved by forming a composite material are strength, stiffness, corrosion resistance, wear resistance, weight, thermal insulation, thermal conductivity, etc. Composite materials can be classified and characterized into four commonly accepted types; (1) fibrous composite materials that consist of fibers in a matrix, (2) laminated composite materials that consist of layers of various materials, (3) particulate composite materials that are composed of particles in a matrix and (4) the combination of some or all the first three types (Jones, 1999). According to the matrix phase the composites are divided into three groups; (1) metal matrix composites (MMCs), (2) polymer matrix composites (PMCs) and (3) ceramic matrix composites (CMCs). Ceramic materials in general have very attractive properties e.g.: high strength and high stiffness at very high temperatures, chemical inertness and low density. In the presence of flaws (surface or internal) they are prone to catastrophic failures. Ceramic materials can be toughened by incorporating fibers and thus exploit the attractive high-temperature strength and environmental resistance of ceramic materials without risking a catastrophic failure (Chawla, 1987). According to the basics written above, a monolithic silicone carbide (SiC) was used as a matrix phase, which has been recognized as one of the most promising structural materials for many thermo-mechanical applications because of its excellent hightemperature strength and modulus, good oxidation resistance, high hardness, low specific weight and low density (Xin-Bo & Hui, 2005; Xin-Bo et al., 2000; She et al., 1999). The problem with monolithic SiC is its low thermal shock resistance, which leads to cracking and catastrophic failure of the material. Thermal shock resistance and crack propagation can 6