CHARACTERIZATION OF SIC FIBER (SCS-6) REINFORCED-REACTION-FORMED SILICON-CARBIDE MATRIX COMPOSITES

Silicon carbide fiber (SCS-6) reinforced-reaction-formed silicon carbi de matrix composites were fabricated using a reaction-forming process. Silicon-2 at. % niobium alloy was used as an infiltrant instead of pu re silicon to reduce the amount of free silicon in the matrix after re action forming. The matrix primarily consists of silicon carbide with a bimodal grain size distribution. Minority phases dispersed within th e matrix are niobium disilicide (NbSi2), carbon, and silicon. Fiber pu shout tests on these composites determined a debond stress of similar to 67 MPa and a frictional stress of similar to 60 MPa. A typical four -point flexural strength of the composite is 297 MPa (43.1 KSi). This composite shows tough behavior through fiber pullout.