Property Research Of C/C-SiC Composite

C/C-SiC composite named as carbon fiber reinforced carbon silicon carbide binary matrix composites,is a new high-temperature structural and functional materials,and have the characteristics of low density,excellent oxidation resistance, corrosion resistance and good friction properties. A series of C/C-SiC composites are prepared by chemical vapor infiltration method (CVI) in this paper,and the influence of perform densities, porosity, content of SiC, environment on properties is studied. Mechanics properties, calorifics properties, friction properties of composites are analyzed, and antioxidation properties are briefly studied. The conclusions are shown as below:High properties C/C-SiC composites could be prepared by chemical vapor infiltration method. With the increasing of preform density, final porosity of samples decreases clearly. The composites are almost densified completely when the preform density is 1.51g/cm~3. The SiC content in samples decrease as the preform density increases.The mechanical properties including flexural strength, shear strength, toughness of composites depend mainly on the porosity and SiC content of samples. SiC could not form framework for sample with low-density, resulting that the mechanics properties are not good. Also, the low SiC content for sample with high density could not strengthen the sample. Therefore, the mechanics properties of sample with preform density of 1.21g/cm~3 are the best.The higher the composite's density, the lower it's porosity, and the bigger it's coefficient of heat conductivity. With the increasing of SiC contente, the coefficient of heat conductivity and thermal diffusivity are lowered visibly.With the increasing of content of SiC, the sample's coefficient of thermal expansion at the same temperature distinctly increase when the density of sample is high, which could be attribute to the effect of SiC content. When the density of sample is low, the sample's coefficient of thermal expansion is low, which may mainly because of the effect of porosity.In friction experiment, SiC particles bear mostly the brake pressure as hard phase which could disperse effectively the brake pressure and avoid micro-area pressure concentration to obscission of SiC and fish tail dualization if the SiC content is proper. The more micro-cut, the higher the frictional coefficient will be. When the mass percent of SiC is more than 40%, SiC act as self-lubrication phase, lowering the frictional coefficien. The frictional coefficient of samples in damp...