Microstructure and mechanical performance of SiCf/BN/SiC mini-composites oxidized at elevated temperature from ambient temperature to 1500 °C in air

SiCf/BN/SiC mini-composites comprising single tow SiC fibre-reinforced SiC with chemical vapour deposited (CVD) BN interface layers were fabricated. The mechanical performance and binding strength of the composites and the fibre/interface for the oxidized SiCf/BN/SiC mini-composite samples (oxidation at 1000, 1200, 1300, 1400 and 1500 degrees C in air for two hours) were investigated by tensile tests and fibre push-out tests, respectively. The value of oxidation mass change was also measured. Some unusual phenomena for the SiCf/BN/SiC minicomposites oxidized at 1000 degrees C were discovered in this work. The tensile strength reached a maximum value, and the mass gain rate showed as a singular negative value, while the shear strength between the fibre and the matrix was moderate. Scanning electron microscopy, energy dispersive spectrometry, infrared spectroscopy and X-ray diffraction characterization methods were used to reveal the microstructural evolution and investigate the unusual phenomenon during oxidation procedures. This work will provide guidance for predicting the service life of SiCf/BN/SiC composite materials and may enable these materials to become a backbone for thermal structure systems in aerospace applications.