Research Of C/C-SiC Composites Used Precursor Infiltration Pyrolysis

C/C-SiC composites, carbon fiber reinforced cabon silicon carbide binary matrix composites, is a new high temperature structure and function materials, having the characteristics of low density, excellent oxidation resistance, corrosion resistance and good friction properties. In this study, C/C-SiC composites are prepared by precursor infiltration pyrolysis, and the influence of infiltration concentration, times and preform densities on C/C-SiC composites' densities and mechanical properties are studied. Thermal behaviores of C/C-SiC composites are also analyzed in brief. The conclusions are shown as the following:Analysis of statics and dynamics of test shows that the liquid with large surface tension and small viscosity and preform with large porosity should be selected for achieving good wetting effect, which could make the infiltration easier. The theory and experiment result indicates that the precursor condensation model could explain the relation of the density of composites to cycle times and maceration extract concentration much exactly.The decomposition of Polycarbosilane mainly occurs between 300 and 1000℃. and the amorphous SiC from the decomposition of polycarbosilane will crystallize into SiC crystal at 1000-1300℃. The productivity from polycarbosilane is 60%, and SiC is the mainly product.When the cycle times are the same, the density of sample nearly all achieve to the maximum for different preform densities when the maceration extract concentration is 50%, no matter how different the perform densities are. The flexural strength of the composites increases as the decomposition temperature, and the composites prepared in1600℃ have the best over-all properties.When maceration extract concentration is 50%, decomposition temperature is 1600℃, the properties of composites with preform density of 1.21 g/cm³are the best, while those with perform density of 1.51 g/cm³ are the worst.The composites using pressed infiltration have higher densities than that using vacuum infiltration. Pressed infiltration can enhance the mechanics properties of the C/C-SiC composites effectively. When preform density is 0.80 g/cm³, the final density , flexural strength, shearing strength, and the fracture toughness of the C/C-SiC composite reaches to 1.95 g/cm³, 323 MPa, 33.45 MPa, and 14.37 MPa·m^1/2,...