Development of Reaction Sintered Silicon Carbide Matrix Composite and Tensile Strength Properties

Dense silicon carbide matrix composite reinforced by Hi-Nicalon® with BN or BN/SiC coating was fabricated by slurry impregnation of carbon and SiC and subsequent reaction sintering with molten Si. The optimum sintering condition was investigated and the effect of BN layer thickness on the tensile strength at room temperature was evaluated. The composite which was uni-directionally reinforced by 30vol% fibers with BN/SiC coating of 1.0/0.3μm thickness and sintered at 1693K for 0.3ks showed Young's modulus of 242GPa, the ultimate tensile strength of 556MPa and the failure elongation of 0.9%. The ultimate tensile strength showed a good agreement with the prediction from in situ fiber strength via fracture mirror size.