摘要
用恒温热重法测定了表面经化学气相渗 SiC 的碳布层叠和碳毡抗氧化碳/碳复合材料在1300℃、空气中的氧化失重速率,并研究其高温氧化行为。氧化动力学测定结果表明,碳布层叠和碳毡抗氧化碳/碳材料在1300℃空气中1h 的平均氧化失重速率分别为0.024和0.033g/m^2·s。两种材料的氧化失重速率随氧化时间延长而减小。研究表明,材料表面 SiC 涂层中的微裂纹缺陷作为环境中氧的快速扩散通道,使得涂层底部基体的碳发生氧化。在达到稳态后,氧化速率限制过程为反应气体和产物气体通过 SiC 涂层底部气体边界层的扩散过程。
Two kinds of siliconized reinforced carbon-carbon composite,laminatedcarbon based and carbon felt based,were oxidized in air at 1300℃ in a thermobalance.Theaverage mass loss rates of the laminated carbon based and carbon felt based composite oxi-dized at 1300℃ in air for lh were 0.024 and 0.033g/m^2.s,respectively.The mass loss ratesof the two kinds coompósite decreased with exposure time.It was shown that the substratecarbon were oxidized by the oxygen transported from the micro-cracks in the surface SiCcoating.The oxidation rate limiting process was proposed as the diffusion of the gaseousspecies through gas boundary layer at the interface of the silicon carbide and substrate.
