C/C多孔体热处理温度对C/C-SiC复合材料微观结构和热学性能的影响

摘要

以针刺网胎无纬布为预制体,采用化学气相渗透(CVI)、压力浸渍树脂/炭化(PIC)及反应熔体浸渗法(RMI)等组合工艺快速制备C/C-SiC复合材料.研究了C/C多孔体的高温热处理温度对C/C-SiC复合材料微观结构和热学性能的影响,结果表明:多孔体经高温热处理后密度有所减小而孔隙率增大;相较于1800℃热处理,多孔体经2200℃热处理后制备的C/C-SiC复合材料密度更大(ρ =2.12g/cm3),孔隙率更低(η=2.7％),SiC基体含量更高(ω=41.11％);C/C-SiC复合材料的比热容和平均热膨胀系数随着温度的升高而增大,而热扩散系数和导热系数随着温度的升高不断减小;多孔体经2200℃热处理后制备的C/C-SiC复合材料X-Y向具有更大的导热系数和更小的热膨胀系数,其室温下的导热系数为83.120W/(m·K),室温～1000℃的平均热膨胀系数为1.608×10-6/℃.%The C/C-SiC composites were fabricated by the combination of chemical vapor infiltration,resin impregnation/carbonization and reactive melt infiltration.The effects of heat treatment temperature (HTT) of C/C porous preform on microstructure and thermal properties of C/C-SiC composites were investigated.The results show that the density of C/C porous preform decreases and the porosity increases after HTT.Compared with 1800℃,C/C-SiC composites prepared by HTT at 2200℃ have higher density (ρ =2.12g/cm3) and lower porosity (η =2.7％),and the content of SiC (ω =41.11％) is higher.The specific heat capacity and the average coefficient of thermal expansion (CTE) of C/C-SiC composites increase with the increase of temperature,while the thermal diffusion coefficient and thermal conductivity decrease with the increase of temperature.The C/C-SiC composites prepared by HTT at 2200℃ have higher thermal conductivity and smaller thermal expansion coefficient,and the thermal conductivity at RT is 83.120W/(m·K),the CTE at RT～1000℃ is 1.608 × 10-6/℃.