Effects of pyrocarbon interphase on microstructure and properties of C/SiBCN composites

Abstract

C/SiBCN composites are expected to have widespread application in aerospace applications due to the excellent high-temperature stability. However, the interfacial reactions between the carbon fibers and the SiBCN matrix at high temperatures have significantly limited the practical application of these composites in the aerospace field. In this paper, different thicknesses of pyrocarbon (PyC) interphase (0.1 μm, 0.25 μm, and 0.5 μm) were introduced by chemical vapor deposition (CVD) process. The interface bonding of C/SiBCN composites with 0.1 μm and 0.25 μm interphase was relatively weak and the composites with 0.5 μm interphase exhibited strong interface bonding strength. After heat treatment at 1600 °C, the mechanical properties of the C/SiBCN composites with the 0.5-μm-thick interphase was maintained at 131 MPa, and at 105 MPa even after heat treatment at 1900 °C, which indicated their excellent high-temperature mechanical properties. In short, 0.5-μm-thick PyC interphase can effectively improve the interfacial reaction of the C/SiBCN composites, which contributed to the application of the composites in high temperature environment.