不同先驱体制备C/SiC复合材料及其浸渍行为

采用先驱体浸渍裂解工艺(PIP工艺)制备C/SiC复合材料,研究了不同先驱体对复合材料浸渍行为的影响(三种先驱体分别为固态聚碳硅烷(PCS(s))、液态聚碳硅烷Ⅰ(PCS-Ⅰ(l))和液态聚碳硅烷Ⅱ(PCS-Ⅱ(l)),制备的三种复合材料体系分别为C/SiC-0、C/SiC-Ⅰ和C/SiC-Ⅱ)。结合C/SiC复合材料的力学性能以及不同裂解周期C/SiC复合材料的微观形貌,研究了不同先驱体制备的C/SiC复合材料对碳纤维织物浸渍行为的影响。研究结果表明:C/SiC-Ⅰ复合材料的室温弯曲强度最高,达到336 MPa。不同裂解周期的微观形貌显示, C/SiC-0复合材料内部孔隙分布于碳纤维束间; C/SiC-Ⅰ复合材料内部较致密,孔隙分布均匀; C/SiC-Ⅱ复合材料基体和束丝内部都存在孔隙,说明三种聚碳硅烷浸渍液对C/SiC复合材料有不同的浸渍效果。凝胶渗透色谱(GPC)的分析结果显示,由于浸渍液的分子量不同,大分子无法浸渍到碳纤维束丝内部,会造成裂解后的复合材料束内SiC基体较少,造成其力学性能较低。

Effect of Precursors on Impregnation Behaviors of C/SiC Composites

In order to investigate the influence of precursors on impregnation behaviors of C/SiC composites, C/SiC composites (C/SiC-0,C/SiC-Ⅰand C/SiC-Ⅱ) prepared with three different precursors (solid polycarbosilane, PCS(s)), liquid polycarbosilane PCS-Ⅰ(l) and PCS-Ⅱ(l)) were prepared via precursor infiltration and pyrolysis (PIP) method. Impregnation behaviors of different precursors were studied to mainly focuse on the combination of mechanical properties as well as microstructures of C/SiC composites with different PIP cycles. Results showed that C/SiC-Ⅰ composites exhibited the highest flexural strength of 336 MPa. The microstructures of C/SiC composites showed that the internal pores of C/SiC-0 composites were distributed between carbon fiber bundles, C/SiC-I composites were dense and the pores were evenly distributed. The pores of C/SiC-II composites were inside carbon fiber bundles and SiC matrix. Gel permeation chromatography (GPC) results showed that due to the difference of molecular weights of the impregnating solution, the macromolecules cannot impregnated into the carbon fiber bundles, which resulted in the lack of SiC matrix and degradation of mechanical properties for the composites after PIP cycles.