烧蚀产物ZrO2对ZrC改性C/C复合材料烧蚀的影响

采用ZrOCl₂溶液浸渍法把含锆组元引入碳纤维预制体, 结合热梯度化学气相渗透、高温石墨化工艺制备了ZrC改性C/C复合材料. 用氧乙炔烧蚀测试材料的烧蚀性能, XRD测试材料烧蚀前后的物相组成, 采用SEM观察材料的微观形貌. 烧蚀结果表明：随着烧蚀次数的增加, 若每次烧蚀后不去除ZrO₂, 材料的线、质量烧蚀率呈先增加后减小的趋势, 最后趋于稳定; 若每次烧蚀后去除ZrO₂, 材料的线、质量烧蚀率均呈增大的趋势. 产物ZrO₂的蒸发吸收了材料烧蚀表面的热量, 减缓了火焰对烧蚀表面的冲蚀, 材料的线烧蚀率减小, 然而, ZrO₂的蒸发会增加材料的质量损失速度, 导致材料的质量烧蚀率增大.

Effect of ZrO2 from the Oxidation of ZrC on Ablation of ZrC Modified Carbon/Carbon Composites

Zirconium-containing carbon fiber preform was prepared by ZrOCl₂ aqueous solution impregnation. ZrC modified carbon/carbon (C/C) composites were obtained by a series of procedures combined with densification by thermal gradient chemical vapor infiltration (TCVI) and high-temperature graphitization. The ablation properties were tested in an oxyacetylene torch. The phase composition and morphology of the composites were investigated by XRD and SEM, respectively. Results show that, with increasing ablation times, the linear and mass ablation rates increase firstly and then decrease, remain constant finally when ZrO₂ is not removed after each ablation. Meanwhile, the linear and mass ablation rates increase with the ablation time in case of removing ZrO₂ after each ablation. The evaporation of ZrO₂ will absorb heat and relieve erosion from oxyacetylene flame on the ablated surface of the specimen, and also accelerate the mass loss of the specimen, which leads to the decrease of the linear ablation rate and increase of mass ablation rate of the composites.