In order to resolve low strength fracture of SiC filament caused by its surface defect,the SiC filament is coated by carbon with chemical vapor deposition method. For carbon coat and non-carbon coat SiC filament, their crystal structure and surface morphology are to be characterized with X-ray diffraction and SEM respectively. Their tensile strength is tested. The result shows that SiC filament is composed of ?SiC, whose (111) direction is the preferred orientation. The surface of carbon coat SiC filament is smooth and dense with less surface defect. The depth value of surface defects is effectively reduced. Compared to the strength of SiC filament without carbon coat, strength of SiC filament with carbon coat is increased for nearly one-third. Therefore, the carbon coat reduces surface defect, which increases the tensile strength of SiC filament greatly.%针对SiC纤维的表面缺陷引起的低强度断裂问题,采用CVD技术对SiC纤维进行了C涂层.利用了XRD和SEM分别对无C涂层SiC纤维和C涂层SiC纤维的晶体结构和表面形貌进行了表征,对比了其抗拉强度.结果表明SiC由-SiC晶体组成,在(111)晶面方向上择优生长.涂C后SiC纤维表面光滑致密,表面缺陷较少,有效地降低了表面缺陷深度a值;涂C后SiC纤维的拉伸强度比无C涂层的抗拉强度增加了620MPa.因此,C涂层可以降低SiC纤维的表面缺陷,从而使SiC纤维的抗拉强度增加到2870MPa.
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