Defect control of SiC polycrystalline fiber synthesized from poly-aluminocarbosilane

SiC-polycrystalline fiber (Tyranno SA) shows excellent heat-resistance up to 2000 °C. Aiming to enlargement of the future application, increase in the mechanical strength of the fiber is eagerly required. Tyranno SA was produced via lots of heat-treatment procedure. This production process is very similar to that of carbon fiber containing decomposition and densification processes at high temperatures in inert gas atmosphere. As these production processes are accompanied by the gaseous by-products, it’s easy to remain pores in each filament along with some other defects. These pores would also become “defect” as well as both residual carbon and abnormal crystalline growth become remarkable defects. In this study, first, the relationship between the defect size and the tensile strength of SiC-polycrystalline fiber was obtained. From this result, it was clarified that the smaller the defect size became, the higher the strength became. By controlling the processes, smoother surface of SiC-polycrystalline fiber was obtained.