【作者】 吴敏；

【导师】 李国栋；

【作者基本信息】 中南大学 ， 材料科学与工程， 2013， 硕士

【摘要】 为提高C/C复合材料抗烧蚀性能,满足航天航空领域高温及超高温环境使用要求,本文采用包埋法和化学气相沉积法制备了结构复合的ZrC/ZrC复合涂层、结构与成分复合的ZrC/TaC复合涂层,探索了C/C复合材料高温抗烧蚀涂层的制备技术。采用包埋法和CVD法制备了ZrC/ZrC复合涂层,分析了涂层的组织结构特征,并研究了复合涂层的抗烧蚀性能。包埋法制备的ZrC内涂层具有内层致密、外层多孔的双层结构特征,与CVDZrC外涂层相互镶嵌融合,形成机械互锁结构,增强了界面结合强度。复合涂层经过30s烧蚀后,结构完整,表面为多孔ZrO2。包埋多孔ZrC层可极大减缓和释放在烧蚀产生的强热震和热应力,提高复合涂层的抗热震性、结构稳定性以及烧蚀可靠性。采用化学气相共沉积法在不同ZrCl4/TaCl5质量比下制备了ZrC/TaC复合涂层,并研究了其抗烧蚀性能。ZrC/TaC复合涂层均由碳化物颗粒堆积而成,具有成分波动的自组织多层结构特征。烧蚀60s后,ZrCl4/TaCl5比为4：1、2：1、1：1时复合涂层的产物均为ZrO2和TaZr2.75O8,质量烧蚀率和线烧蚀率分别为0.3×10-4g·s-1和0.5×10-4mm·s-1、0.6×10-4g·s-1,和7.5×10-4mm·s-1、-0.2×10-4g·s-1和1.0×10-4mm·s-1,抗烧蚀性能明显优于单一ZrC涂层与ZrC/ZrC复合涂层。多层结构可显著降低气流对内部涂层及基体的热冲击,减缓内部涂层的氧化速率。TaC的存在有助于涂层在烧蚀中形成致密氧化物层和氧化物熔体,有效提高涂层在高速高压气流下的抗冲刷能力。适量的TaC有利于提高ZrC/TaC复合涂层的抗烧蚀性能。图48幅,表10个,参考文献87篇。更多还原

【Abstract】 In order to improve the ablation resistance performance of carbon/carbon (C/C) composites and meet the high and ultra-high temperature requirements of the aerospace field, ZrC/ZrC and ZrC/TaC composite coatings were successfully prepared by pack cementation and chemical vapor deposition (CVD).ZrC/ZrC composite coating was prepared by pack cementation and CVD, the microstructure and the ablation properties of the coating was investigated. The inner coating prepared by pack cementation method has a double structure of the inner dense layer and the outer porous layer; the CVD outer coating forms columnar crystal structure with convex cellular surface morphology. The porous layer and the CVD layer are mutually embedded and merged to form a mechanical interlocking structure, thus enhancing the interface bonding strength between the coatings.After30s ablation, the ablated coating has intact structure, the surface generates a porous ZrO2layer. The embedding porous ZrC layer can greatly ease and release strong thermal shock and thermal stress in the ablation process, improve the ZrC/ZrC coating’s thermal shock resistance, structural stability and reliability of the ablation.The ZrC/TaC coating was co-deposited in different ZrCl4/TaCl5ratio by CVD, the ablation properties were investigated. The coating accumulated with carbide particles has self-organized multilayer structural characteristic with composition fluctuation. After60s ablation, products are ZrO2and TaZr2.75O8, the mass and linear ablation rates of the coating prepared at4:1、2:1、1:1ZrCl4/TaCl5ratio are0.3×10-4g·s-1and0.5×10-4mm·s-1,0.6×10-4g·s-1and7.5×10-4mm·s-1、-0.2×10-4g·s-1and1.0×10-4mm·s-1, respectively. The multilayer structure can decrease the thermal shock of the internal coating and substrate because of the high temperature and high pressure environment, slowing down the oxidation rate of the internal coating. The existence of the TaC contribute to the coating to form a dense oxide layer and oxide melts in the ablation, which can withstand the flushing action of the high speed and high pressure air flow, avoiding the coating failure quickly. The amount of TaC can improve the ablation resistance of the ZrC/TaC composite coating.更多还原