纳米线构筑的SiC弹性陶瓷及其力/热行为研究

For the special demand for ceramic insulation of hypersonic aerocrafts, we first propose to prepare SiC elastic ceramics constructing of nanowires using carbon-bonded carbon fiber composites (CBCF) as framework through in-situ growth and self-assembly of nanowires by the method of precursor infiltration, pyrolysis, and gas phase reaction. Morphology and size of the nanowires are controlled by the precursor composition and structure; 3-D nanowire network structure with a certain strength, good elastic-plastic property, and high thermal insulation capability is obtained by introducing junctions among nanowires through control of the pyrolysis and gas phase reaction process. An innovative method for preparation of SiC elastic insulation with high performance has been established based on investigating formation of the nanowires, microstructure design and preparation of the elastomer, and its structure and properties under compressive stress and heat systematically; illustrating the main factors influencing structure and morphologies of the SiC nanowires, the dependence of elastic-plastic behavior on the microstructure, and the coordination among strength, elastic-plastic property and thermal insulation capability. This project provides thoughts to improve brittleness of ceramics. Although design and preparation of this material will face many problems, proposing and resolving the problems can certainly innovate in solving brittleness of ceramics to a certain degree.

针对高超声速飞行器对陶瓷隔热材料的特殊需求，首次提出以裂解碳连接碳纤维复合材料(CBCF)为骨架，采用前驱体浸渍、裂解和气相反应相结合的方法，通过SiC纳米线的原位生长及自组装，制备由纳米线构筑的SiC弹性陶瓷的新思路。通过控制前驱体的成分、结构，调整纳米线的尺寸及形貌；控制裂解及气相反应过程，在纳米线间引入结点，获得具有一定强度、良好弹塑性、优异隔热性能的三维网络结构。系统研究纳米线的形成过程，弹性陶瓷微结构设计、制备及其在力/热作用下结构、性能变化，阐明影响SiC纳米线结构及形貌的主要因素、SiC弹性陶瓷的弹塑性行为及其微观结构依赖性、材料强度-弹塑性-隔热性能协调等关键科学问题，建立一种制备高性能SiC弹性隔热材料的方法。本项目为改善陶瓷脆性提供了新的思路。当然，在这种理念指导下的材料设计及制备将面临许多问题，请相信，这些问题的提出和解决一定能够在一定程度上诱发解决陶瓷脆性的创新源头

本项目针对高超声速飞行器热防护结构对陶瓷隔热材料的特殊性能要求，提出利用纳米线的原位生长及自组装，制备具有弹性的轻质隔热陶瓷。按照项目任务书内容实施，具体研究了SiC纳米线的形成过程及影响因素，SiC弹性陶瓷的微观结构设计、制备及控制，SiC弹性陶瓷在力/热作用下微观结构、性能变化规律及控制，SiC弹性陶瓷强度、弹塑性、隔热性能的优化提升等4项研究内容，阐明了弹性陶瓷形成过程中影响SiC纳米线微观结构及形貌的主要因素，SiC弹性陶瓷的强度、弹塑性行为对其微观结构的依赖性，弹性陶瓷强度-弹性-隔热性能的协调等3个科学问题。最终建立了一种高性能SiC弹性陶瓷的类化学气相沉积制备方法，实现了大尺寸SiC弹性陶瓷的制备，并通过进一步的微观结构设计及优化，获得具有超级隔热性能的各向异性SiC纳米线弹性陶瓷气凝胶和具有拉伸回弹性的SiC纳米线弹性陶瓷气凝胶，同时还探索了其在催化剂载体、电磁波吸收、可吸入颗粒物过滤等领域的工程应用价值。项目研究成果，对于设计和制备高性能弹性陶瓷具有重要的指导意义，对进一步丰富和发展陶瓷材料韧化理论具有重要的科学意义。. 项目执行期间在Science Advances、ACS Nano、ACS Applied Materials & Interfaces、Small、Chemical Engineering Journal、Journal of Materials Science & Technology、Journal of the European Ceramic Society、Journal of the American Ceramic Society、The Journal of Physical Chemistry C等国际重要期刊发表论文27篇。在弹性陶瓷研究领域积极布局专利群组，目前已获得相关授权发明专利10件。培养了多名优秀青年教师、优秀博士、硕士研究生，其中2位青年教师成功晋升副教授。项目各项任务已圆满完成，实现了预期目标，收获了预期成果，达到了课题的总体设计。