Effect of high temperature oxidation on mechanical and electromagnetic interference shielding effectiveness of Ti3SiC2 modified SiCf/BN/SiBCN composites

SiCf/BN/SiBCN composites were prepared through the technique of polymer infiltration pyrolysis (PIP). To enhance the electromagnetic interference (EMI) shielding effectiveness (SE), 20 wt% of Ti3SiC2 was incorporated into the composites. The study investigated the influence of different oxidation temperatures (1300 °C, 1400 °C, and 1500 °C) on both the mechanical properties and EMI SE of the composites. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were utilized to analyze the phase and microstructure of the composites, while characterizing their mechanical properties and EMI SE. The outcomes revealed a decline in the mechanical properties of the composites following high temperature oxidation, with the formation of SiO2 and TiO2 as the main oxidation products. Notably, an oxide layer formed on the material's surface at 1400 °C acted as a barrier to oxygen diffusion, facilitating self-healing of pores and cracks and thereby enhancing material protection. Moreover, the material oxidized at 1400 °C demonstrated a remarkable synergy between impedance matching and electromagnetic loss, resulting in the optimum EMI SE. The EMI SE of this material was 6.35% higher than the total shielding effectiveness at room temperature and effectively shielded 99.88% of electromagnetic waves.