Evolution and controlling of defects during the preparation of continuous high-temperature resistant SiC(Al) fibers

Continuous high-temperature resistant SiC(Al) fibers were prepared by polymer-derived method using polyaluminocarbosilane (PACS) as the precursor. The formation and evolution of defects formed in the preparation of continuous high-temperature resistant SiC(Al) fibers were investigated by analyzing continuous PACS green fibers, cured products, pyrolysis process and continuous SiC(Al) fibers. The results showed that there were two major types of defects in the continuous PACS green fibers: pits and inclusion. These defects were difficult to be eliminated during the next processes. Other new defects may form during the preparation process under improper conditions, especially during the pyrolysis and sintering processes. The properties of the fibers are greatly affected by the defects. The formation of defects could be reduced to prepare high performance SiC(Al) fibers if effective measures are taken according to the formation mechanism of defects.