硅酸盐学报

用先驱体转化法制备连续SiC纤维,在聚碳硅烷(polycarbosilane,PCS)纤维热解过程中有明显的质量损失和收缩,造成了纤维的弯曲,从而影响了SiC纤维的单丝强度和束丝拉伸性能。为避免纤维弯曲,施加一定的张力对预氧化PCS纤维进行热解。结果表明:张力对于纤维的热解过程,特别是对纤维的伸缩过程有很大的影响。通过施加适当的张力,烧成后的SiC纤维平直,丝间的平行度明显改善,单丝强度和束丝拉伸性能均有提高,纤维的晶粒尺寸有一定的增加。加张力烧成中较佳张力为每束丝0.049～0.147N,SiC纤维的单丝强度达1.42GPa,提高20%左右。

Preparation of polymer-derived SiC fibers involves a pyrolysis process, in which obvious mass loss and shrinkage are (usually) observed. As a result there are much bending, which lowers the tensile strength of SiC fibers obtained. To avoid this bending, a process for pyrolysis of cured polycarbosilane (PCS) fibers under tension was studied. Results indicate that the effect of tension on the pyrolysis process is great, especially on the flexing process of cured PCS fibers. By applying a certain tension during pyrolysis the obtained SiC fibers are straight and parallel to each other. The tensile strength of the SiC fibers and the crack loads of SiC yarns are much improved and the crystal size of the fibers is increased. The optimum tensile strength of about 1.42 GPa is obtained by using the tension of (0.049—)0.147 N per yarn during pyrolysis and the tensile strength of SiC fibers is increased 20%.