碳纤维含量对Cf/SiO2复合材料组织与性能的影响

采用真空热压烧结工艺制备了碳纤维体积分数分别为20％、40％和60％的高致密Cf/SiO2复合材料，研究了碳纤维含量对其组织结构，力学性能、热膨胀特性和抗氧化性能的影响规律。结果表明：SiO2基体及20％Cf/SiO2复合材料中，SiO2仍保持非晶态，碳纤维含量为40％和60％时，SiO2发生部分析晶；Cf/SiO2复合材料的抗弯强度、断裂韧性和断裂应变，随碳纤维含量增加均呈现先降低后又增加的趋势，而弹性模量则先增后降；60％Cf/SiO2表现出明显伪塑性；碳纤维含量增大，使复合材料的热膨胀系数成倍增加，抗氧化性变差。

Effect of Carbon Fiber Content on Microstructure and Properties of Cf/SiO2 Ceramic Matrix Composite

Highly consensed SiO 2 matrix composites with various volume contents of short carbon fibers (C f), 20%, 40% and 60%, are prepared by vacuum hot pressing. Influence of carbon fiber content on microstructure, mechanical properties, thermal expansion coefficient and thermal oxidation resistance is investigated for the composites.Experimental results indicate that unreinforced SiO 2 matrix and the SiO 2 in its composite with 20% of carbon fibers keep uncrystallized, but the SiO 2 in composites with 40% and 60% of carbon fibers appears to crystallize partially. With increase of carbon fiber content,the bending strength, fracuture toughness and strain would decrease at first and then increase ,but the bending modulus is in the reverse.The composite with 60% of carbon fiber behaves like a pseudoplastic. Thermal expansion coefficient would increase by a few times,and thermal oxidation resistance would degrade with the increase of carbon fiber of composites.