原位HfC纳米线增韧化学气相共沉积HfC-SiC抗氧化烧蚀梯度复合涂层研究

In order to improve the oxidation and ablation resistance of carbon/carbon (C/C)composites above 1700℃, HfC nanowire porous layer was prepared on C/C composites by catalyst-activated chemical vapor deposition, then HfC nanowire porous layer was filled by the compositional gradient HfC-SiC ultra-high temperature ceramic coating materials, the in-situ HfC nanowire-toughened HfC-SiC gradient multilayer coating could be obtained. HfC nanowires and gradient stucture can release the mismatch of the coefficient of thermal expansion between the coating and C/C matrix, avoid the cracking and debonding of the coating, the oxidation and ablation resistance of coating can be improved. The relationship between the preparation process conditions and the microstructure, distribution and yield of nanowires and the microstructure and properties of the coating were investigated. The optimized preparation process conditionsand the formation mechanism of nanowires and coating can be obtained. The effect mechnism of the different ceramics and nanowires and the toughen mechnism of nanowires can be obtained. The relationship between the ceramic distribution and ratio, the microstructure and feild of nanowires and the microstructure and properties of the coating can be established. The oxidation and damage mechanism of C/C composites with the ablation resistance coating under different service environment can be obtained. The above research can lay a theoretical foundation for the application of this kind of ultra-high temperature ceramic coating under high temperature, high speed air flow erosion environment.

本项目针对炭/炭(C/C)复合材料1700℃以上高温氧化烧蚀难题，提出采用催化辅助化学气相沉积工艺在C/C表面原位生长HfC纳米线多孔层，然后采用化学气相共沉积工艺将呈成分梯度的HfC-SiC涂层材料填充于纳米线多孔层，获得原位HfC纳米线增韧HfC-SiC梯度复合涂层。旨在缓解HfC-SiC陶瓷涂层与C/C基体之间的热膨胀失配，避免涂层的开裂与剥落，提高陶瓷涂层的抗氧化烧蚀性能。着重研究化学气相沉积工艺条件与纳米线微观结构形貌、分布和产量以及涂层微观结构及性能之间的关系规律，获得纳米线及涂层的制备工艺条件和形成机理，阐明涂层各陶瓷组元、纳米线的作用机制及纳米线的增韧机理，确立陶瓷组分分布比例、纳米线结构形貌和产量与陶瓷涂层微观结构及性能之间的关系，揭示带有涂层的C/C在不同服役环境下的氧化烧蚀及损伤机理，为拓展此类超高温陶瓷涂层在高速气流冲刷环境下的应用奠定理伦基础。

本项目针对C/C复合材料1700℃以上高温氧化烧蚀难题，提出采用催化辅助化学气相沉积工艺在C/C表面原位生长HfC纳米线多孔层，然后采用化学气相共沉积工艺将呈成分梯度的HfC-SiC涂层材料填充于纳米线多孔层，获得原位HfC纳米线增韧HfC-SiC梯度复合涂层。旨在缓解HfC-SiC陶瓷涂层与C/C基体之间的热膨胀失配，避免涂层的开裂与剥落，提高陶瓷涂层的抗氧化烧蚀性能。完成了(1)催化辅助CVD原位生长HfC纳米线工艺规律及其生长机理；(2)化学气相共沉积制备HfC-SiC梯度复合涂层工艺规律；(3)HfC纳米线对HfC-SiC涂层的影响规律及纳米线增韧机理；(4)带有涂层C/C复合材料的微观结构、性能表征及氧化烧蚀机理等方面的研究内容。获得了催化辅助CVD工艺条件与所制备纳米线结构形貌、分布和产量以及涂层微观结构及性能的影响规律，揭示了纳米线及涂层的形成机理。通过纳米线的引入，有效缓解了HfC-SiC涂层热应力开裂的趋势，提高了涂层的抗氧化烧蚀性能。HfC纳米线增韧陶瓷涂层防护温度可达2000℃以上，氧乙炔条件下烧蚀120s，质量烧蚀率和线烧蚀率分别仅为0.57mg/s和-0.35μm/s。揭示了HfC纳米线在涂层中的增韧机理及纳米线增韧涂层的氧化烧蚀及损伤机理。该项目的研究结果可为拓展此类超高温陶瓷涂层在超高温高速气流冲刷环境下的应用奠定理论基础。.本项目理论研究结果，发表SCI论文30篇，申请发明专利5项，授权2项，培养研究生5名。以部分研究结果为重要支撑，获得2020年教育部技术发明一等奖（耐高温抗氧化碳/碳复合材料多尺度强韧化机理与应用基础）及2018年国防创新团队奖，项目负责人张雨雷教授入选第三批中组部“万人计划”青年拔尖人才及2020年陕西青年科技奖。