High-temperature mechanical properties and interfacial microstructure of novel layered C_sf/SiBCN composites

To achieve low-temperature densification of short carbon fiber reinforced mechanical alloyed SiBCN composites (C_sf/MA-SiBCN) and fill the research gap of high-temperature mechanical properties of C_sf/MA-SiBCN composites, C_sf/SiBCN composites containing both polymer derived SiBCN (PDCs-SiBCN) and MA-SiBCN were prepared by the densification of C_sf/MA-SiBCN composites at 1100 °C via the repeated polymer infiltration and pyrolysis (PIP) process. Unlike traditional hot-pressed C_sf/MA-SiBCN composites, the as-prepared C_sf/SiBCN composites exhibit 2D layered structure and short carbon fibers are evenly distributed in the matrix. On this basis, mechanical properties and microstructural evolution were fully studied from room temperature (RT) to 1600 °C. The strength of 7th PIP-ed composites at RT increases by 55.9 % compared with that of C_sf/MA-SiBCN composites because of higher density (2.00 ± 0.01 g/cm³) and lower porosity (4.14 % ± 0.28 %). At 1400 °C, the strength of C_sf/SiBCN composites shows slightly higher value compared with the strength at RT. At 1600 °C, some SiC crystals and pores are observed in the interfacial region, and thus C_sf/SiBCN composites show nonbrittle fracture behavior at 1600 °C with a strength retention ratio of 41.8 %.