关键词: 先驱体, 聚铝碳硅烷, 碳化硅纤维, 结构

Abstract: A ceramic fiber with the SiC(OAl) composition, named KD-A, was prepared by the melt-spinning of precursor polyaluminocarbosilane, air-curing, and pyrolizing at 1300℃.
The KD-A fiber was converted into SiC(Al) fiber, named KD-SA, by sintering at 1800℃. The composition and structure of the two kinds of
fibers were characterized by chemical element analysis, AES, SEM, XRD, RMS, and ²⁹Si, ¹³C, ²⁷Al MAS NMR. The compositions of KD-A
and KD-SA fibers are in the formula SiC_1.31O_0.25Al_0.018 and SiC_1.03O_0.013Al_0.024, respectively. The compositions of
KD-A and KD-SA fibers on the surface are different from that of inside of the fibers. The surfaces of KD-A and KD-SA fibers are smooth and even, and there are no
hole, crack and groove. KD-A fiber contains free carbon, small amount of β-SiC micro-crystal and aluminium embedded in an intergranular phase SiC_xO_y, which is
ascribed to a non-crystalline SiC fiber. KD-SA fiber containsa large number of β-SiC, a small amount of α-SiC and Al₂O₃,
which is ascribed to a crystalline SiC fiber with a nearly stoichiometric composition.

Key words: precursor, polyaluminocarbosilane, SiC fibers, structure