Abstract: High-temperature resistant continuous SiC fibers were prepared by polymer-derived method using precursor polyaluminocarbosilane(PACS). The evolutions of the fibers structure and tropism during the preparation and its effect on the properties of the fibers were investigated. The results show that the evolutions of structure of continuous cured PACS fibers included four stages: crosslinking among the molecules of the fibers(≤600 ℃), basically inorganic transformation(600—800 ℃), completely inorganic transformation(800—1300 ℃), crystallization and redistribution of the structure(1300—1800 ℃). The tropism of the fibers changed with the evolutions of the structure. Continuous PACS fibers had the weak tropism along the fiber axis and it was evolved to the products prepared at 1300 ℃. The fibers transformed from anisotropic to isotropic state at 1500 ℃. The properties of continuous SiC fibers were affected greatly by the evolutions of the structure and tropism.

Key words: High-temperature resistant continuous SiC fibers, Tropism, Polymer-derived method, Polyaluminocarbosilane