【摘要】 采用化学气相渗透（chemical vapor infiltration,CVI）方法,在具有2.5D浅交弯联结构的SiC纤维管状编织体上预沉积SiC-PyC-SiC多层界面（PyC即Pydrolytic carbon,热解碳）,再利用CH₃SiCl₃-H₂-Ar体系对其进行化学气相渗透SiC增密,制备管状SiC_f/SiC复合材料,研究SiC_f/SiC复合材料的物相组成、微观结构、轴向压缩、径向压溃以及环向拉伸等力学性能及其断口形貌。结果表明:SiC_f/SiC复合材料主要由SiC纤维、SiC-PyC-SiC复合界面以及SiC基体组成。SiC-PyC-SiC复合界面中,PyC界面厚度为400⁵00 nm,SiC界面厚度为700⁸00 nm,SiC基体主要为β-SiC相。SiC_f/SiC复合材料的密度为2.50².58 g/cm³,开孔率为7.70%⁹.10%,轴向抗压强度为53.2 MPa,径向压溃强度为38.18 MPa。轴向压缩时表现为与水平方向成45°方向的剪切破坏,径向压溃时表现为形成4个塑性铰后发生分瓣破坏,断口处明显观察到纤维拔出现象,但拔出不长,表现出"假塑性"特征。SiC_f/SiC复合材料的环向抗拉强度为12.8 MPa,其断口相对较平整,纤维拔出不明显,表现为脆性破坏。更多还原

【Abstract】 The tubular SiC_f/SiC composite materials were prepared by depositing SiC-PyC-SiC multi-interlayers on the SiC fibers with 2.5 D curved shallow-crossing linking structure densified with SiC matrix using CH₃SiCl₃-H₂-Ar system by chemical vapor infiltration（CVI）. The phase composition, microstructure, axial compression, radial crushing and circumferential tension and fracture morphology of SiC_f/SiC composites were investigated. The results show that SiC_f/SiC composites are mainly composed of SiC fiber, SiC-PyC-SiC multi-interlayers and SiC matrix. In the SiC-PyC-SiC multi-interlayers, the thickness of PyC interlayers is 700-800 nm, the thickness of SiC interface is 400-500 nm, and SiC matrix is mainly β-SiC phase. After densification, the density of SiC_f/SiC composites is 2.50-2.58 g/cm³, and the porosity is 7.70%-9.10%. The axial compressive strength of SiC_f/SiC composites is 53.2 MPa, and the radial crushing strength is 38.18 MPa. Compression is expressed as a shear failure in the 45° direction with the horizontal plane while it is broken into pieces during crushing test.The fiber pull-out phenomenon can be observed obviously at the fracture,but the pull-out is not long and exhibits a typical pseudo ductility feature.The circumferential tensile strength of SiC composites is 12.8 MPa.The fracture is relatively flat,and the phenomenon of fiber pull-out is not obvious,which indicates that it is brittle fracture.更多还原