C/C复合材料ZrB2-SiC涂层的微观结构及烧蚀性能研究

Microstructure and Ablation Performance of ZrB2-SiC Coating on C/C Composites

采用包埋法在密度为1.63g/cm^3的C/C复合材料上制备了不同ZrB2含量的ZrB2-SiC复相陶瓷涂层,考察了不同配比包埋粉料对涂层微观结构和抗烧蚀性能的影响。结果表明,当包埋粉料中ZrB2质量分数为50%时,涂层ZrB2含量最多,氧乙炔烧蚀60s时,其线烧蚀率、质量烧蚀率最低,分别为5.3×10^-4mm/s和2.1×10^-3g/s;在烧蚀过程中,SiC氧化产物SiO2发生了相变,形成玻璃态,吸收大量热量。玻璃态的SiO2相包裹着ZrO2相,使得在烧蚀过程中,有效降低了烧蚀火焰冲击对ZrO2造成的损失,ZrO2导热系数低,是一种优异的热障材料,从而降低了复合材料烧蚀率。

ZrB2-SiC coating with different ZrB2 content was prepared on C/C composites with density of 1.63 g/cm3 by packcementation,and the effect of different proportion of pack-cementation powder on the microstructure and ablation resistance of the coating was investigated.The results showed that when the mass fraction of ZrB2 in the pack-cementation powder was 50%,the content of ZrB2 in the coating was the most,and after oxyacetylene ablation 60 s,the linear ablation rate and mass ablation rate were the lowest,which were 5.3×10^-4 mm/s and 2.1×10^-3 g/s respectively.During the ablation process,SiO2,the oxidation product of SiC forms glassy phase and absorbs a lot of heat.The ZrO2 phase is surrounded by glassy SiO2 phase,which can effectively reduce the loss of ZrO2 caused by ablation flame impact in the process of ablation.ZrO2 is an excellent thermal barrier material with low thermal conductivity,thus reducing the ablation rate of composite materials.