Influence of hydrothermal carbon interphase on mechanical properties of Cf/SiBCN mini-composites after high-temperature treatment

To investigate the influence of hydrothermal carbon (HTC) interphase on the high-temperature performances of Cf/SiBCN composites, the mechanical properties of Cf/SiBCN mini-composites with HTC interphase and without interphase after high-temperature treatment at 1400–1600°C were studied. The results indicate that, with the increase in heat treatment temperature, Cf/SiBCN mini-composites show a decrease in integrity and interfacial bonding, and the mini-composites with HTC interphase show better integrity and more suitable interfacial bonding. With the introduction of HTC interphase, the corresponding mini-composites show higher tensile strength and work of fracture (WOF) at all temperatures. After heat treatment at 1400 and 1500°C, the tensile strength and the WOF of the mini-composites with HTC interphase are 4.5, 2.6 times and 14.8, 4.3 times higher than the mini-composites without interphase, respectively. After heat treatment at 1600°C, although the mechanical properties of the two mini-composites are comparable, due to the erosion of the fibers and the collapse of the matrix, the tensile strength and the WOF of the mini-composites with HTC interphase are still 2.0 times and 1.7 times higher than the mini-composites without interphase, respectively. Therefore, the HTC interphase is promising to be used to improve the high-temperature performances of Cf/SiBCN composites.