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本文研究了两种非晶硅酸铝纤维经热处理产生的莫来石晶相(3Al_2O_3·2SiO_2),纤维截面上Al~(+3)、Si~(+4)和O~(-2)分布变化规律,以及它对纤维预制体真空过滤成型性的影响,并阐明其机理。结果表明:晶体化热处理后,非晶纤维出现占重量约50％的莫来石相,其余为非晶相;晶体化过程中,纤维截面上距表面约400A的薄层内,伴随人Al~(+3),Si~(+4)和O~(-2)分布变化,表面薄层富集Si~(+4),即SiO_2。这些变化,为单根纤维抗拉强度下降三分之二左右的原因;经热处理、机械打断和湿过程处理后,纤维的平均长度明显降低,环状预制体自由形成表面的粗糙度Ra急剧下降,内表面光滑圆整,真空过滤成型性比原始纤维好得多。
In this paper, the morphology of the as-prepared mullite (3Al 2 O 3 .2SiO 2), the Al ~ (+3), Si ~ (+4) and O ~ (-2) The variation law and the effect of vacuum filtration on the fiber filterability of the fiber preform, and clarifies its mechanism. The results show that the amorphous fiber shows about 50% of mullite phase and the rest is amorphous phase after crystallization heat treatment. During the crystallization process, (+3), Si ~ (+4) and O ~ (-2), the surface thin layer enriched Si ~ (+4), namely SiO_2. These changes are the reasons why the tensile strength of a single fiber is reduced by about two-thirds. The average length of the fibers decreases obviously after the heat treatment, the mechanical interruption and the wet process, and the roughness Ra of the free-formed surface of the annular preform is sharp Decline, the inner surface is smooth and round, vacuum filtration forming much better than the original fiber.