SiC基体结构及其对C/SiC复合材料性能的影响研究

Study on the Structure of SiC Matrix and Its Effect on the Properties of C/SiC Composites

采用聚碳硅烷作为前驱体,在800、1000、1200℃下烧结得到SiC基体,研究了温度对SiC基体密度、结晶程度的影响。结果表明基体随着温度的提高,基体密度提高,结晶程度逐渐提高,Si含量比例升高。在800℃时,基体密度为2.30 g/cm^(3),所得基体结构接近无定型态,在1000和1200℃下的密度分别为2.50和2.56 g/cm^(3),晶粒尺寸分别为2.6和4.1 nm。再以聚碳硅烷为前驱体,以碳纤维织物为增强体,采用PIP工艺制备C/SiC复合材料,热解最高温度同样为800、1000、1200℃,得到三组C/SiC复合材料,对复合材料进行了力学性能测试和断口微观结构观察,分析了基体结构对复合材料力学性能的影响。研究结果表明,在一定范围内提高热解温度,有利于改善基体特性和提高复合材料的致密化效率,从而使复合材料的力学性能有所提升,特别是弯曲、层间剪切和压缩性能提高作用明显。

SiC matrix was obtained by sintering polycarbonsilane at 800,1000,1200℃,and the effect of temperature on the density and crystallization degree of SiC was studied.With the increase of temperature,the crystallization degree,the density of the matrix and the proportion of Si increases.At 800℃,the density of the matrix is 2.30 g/cm^(3),and the matrix structure is close to the amorphous state.At 1000℃and 1200℃,the densities of the matrix are 2.50 and 2.56 g/cm^(3),and the grain sizes are 2.6 and 4.1 nm,respectively.C/SiC composites are prepared by PIP process with polycarbosilane as precursor and carbon fiber fabric as reinforcement,the maximum pyrolysis temperatures in the whole pyrolysis process are also 800,1000 and 1200℃.The effect of matrix structure on the mechanical behavior of the composites is studied by mechanical properties test and microstructures observation.The results show that increasing the pyrolysis temperature in a certain range is beneficial to improve the properties of the matrix and the matrix’s densification efficiency,which make the mechanical performance of the material improved,and especially has obvious effect on improving the bending strength,interlaminar shear strength and compression strength of C/SiC composites.