C/C复合材料SiC/SiO2涂层的制备及其抗氧化性能

摘要

为提高C/C复合材料的抗氧化性能,采用包埋法和低压化学气相法制备了SiC/SiO2涂层.借助XRD、SEM和EDS等测试手段分析了复合涂层的微观结构,并研究了其在l273、1773 K静态空气中的抗氧化性能.结果表明,包埋法制备的SiC涂层具有一定的浓度梯度.低压化学气相法制备的非晶Si02外涂层则有效地封堵了SiC内涂层的的裂纹和孔洞,并解决了SiC涂层在中温区(1073～1473 K)无法形成完整SiO2膜的问题.在l 273、1 773 K静态空气中经10h氧化后,涂层试样的质量损失率分别仅有4.97和0.36 mg/cm2,表现出良好的抗氧化性能.%In order to improve the oxidation resistance of the C/C composites, a SiC/SiO2 coating was prepared by pack cementation and low-pressure CVD. The microstructures of the multilayer coating were studied by XRD, SEM and EDS analyses, and then the oxidation resistance of the as-coated C/C composites was evaluated in ambient air at 1 273 K and 1 773 K. The results show that the SiC coating prepared by pack cementation has a compositional gradient. And the external amorphous SiO2 coating prepared by low-pressure CVD effectively seals the cracks and holes of the internal SiC coating. Furthermore, the problem that an integral SiO2 film can not be formed by the oxidation of SiC coating at medium temperature (1 073 to 1 473 K) also is solved. After oxidation in ambient air at 1 273 K and 1 773 K for 10 h, the mass losses of the as-coated C/C composites are only 4. 97 mg/cm2 and 0. 36 mg/cm2, respectively. The SiC/SiO2 coating shows excellent anti-oxidation property.