高导热沥青基碳纤维及热疏导C/SiC-ZrC复合材料的微观结构与导热性能研究

Research on Microstructure and Thermal Conductivity of Highly Thermally Conductive Mesophase Pitch-Based Carbon Fibers and C/SiC-ZrC Composites

为了满足航空航天飞行器热结构部件对材料的耐温需求,需要提高陶瓷基复合材料的导热性能。传统聚丙烯腈基碳纤维增强C/SiC-ZrC陶瓷基复合材料在室温至1600℃范围内的热导率仅为8~18 W/(m·K)。采用高导热中间相沥青基碳纤维作为增强体和导热通道,制备出热疏导C/SiC-ZrC陶瓷基复合材料。该复合材料在宽温域范围内具有显著的高导热特性,当纤维体积分数约为60%时,沥青基碳纤维增强陶瓷基复合材料的室温热导率达到717 W/(m·K),随着温度升高,热导率逐渐降低,在1600℃时降低至140.1 W/(m·K),这种变化趋势主要是由于沥青基碳纤维在高温下声子热传导减弱导致的。

In order to meet the temperature resistance requirements of thermal structural components of aerospace vehicles,it is necessary to improve the thermal conductivity of ceramic matrix composites.The thermal conductivity of traditional polyacrylonitrile-based carbon fiber(Cf-PAN)reinforced C/SiC-ZrC ceramic matrix composites is around 8-18 W/(m·K)from room temperature to 1,600℃.Here we present a novel method,using mesophase pitch-based carbon fiber(Cf-MP),to fabricate a novel Cf-MP/SiC-ZrC composite which is highly thermally conductive within wide temperature range.When the volume fraction of Cf-MP is around 60%,the thermal conductivity of Cf-MP/SiC-ZrC composite reaches 717 W/(m·K)at room temperature and gradually decreases to 140.1 W/(m·K)at 1,600℃.Such variation tendency is basically interpreted to result from the weaken of phonon heat conduction of Cf-MP.