Studies on the structure and composition of Si-N-C fibers containing boron at high temperature

The composition and structure of Si-N-C fibers containing boron as well as their changes at high temperature are studied in this paper. The IR, XPS, EA, XRD and SEM analytical results show that Si-N-C fibers containing boron treated at 1250°C comprise Si, N, C, O and B and are amorphous, while the structures of fibers pyrolysed up to 1800°C are converted into α-SiC crystal, and B exists in the fibers in the form of B-N bonds at high temperature. The Si-N-C fibers containing boron have smooth surface and small crystalline - size in comparison with the fibers without boron, which indicates that the incorporation of boron leads to the improvement of the microstructure of fibers at high temperature.