(1.National Key Laboratory of Advanced Composites, AECC Beijing Institute of Aeronautical Materials, Beijing 100095, China; 2.Aviation Key Laboratory of Science and Technology on Advanced Corrosion and Protection for Aviation Materials, AECC Beijing Institute of Aeronautical Materials, Beijing 100095, China)

Abstract: SiC_f/SiC composites were made by using precursor infiltration and pyrolysis (PIP) combined with melt infiltration  method. Firstly,SiC_f/SiC composites were fabricated by using PIP method with different types of interphases. SiC_f/SiC composites, with BN/SiC dual-layer interphase, have the bending strength of 373±71 MPa, and the density and porosity are 2.351 g/cm³ and 15%, respectively. SiC_f/SiC composites, with PyC interphase, have the bending strength of 717±59 MPa, and the density and porosity are 2.263 g/cm³ and 21%, respectively. After the melting infiltration process, the bending strengths of the materials are 291±42 MPa and 320±134 MPa, respectively. Also, the densities of the materials are 2.504 g/cm³and 2.496 g/cm³, respectively, while the porosities of the materials are decreased to 7% and 6%, respectively. Results showthat interphases playan important role in the strength of the material. The combined process can decrease the porosity of the composites but also decrease the mechanical strength of the material, and the extent is relevant to the type of the interphases.
Key words: ceramic matrix composites; silicon carbide fiber; melt infiltration; precursor infiltration and pyrolysis; silicon carbide