基于皮肤伤口修复机制构建C/C复合材料表面自愈合抗氧化涂层研究

In order to address a series of problems for Si-based coating on carbon/carbon composites, including cracking because of mismatch of CTE, poor thermal shock and oxidation resistance in wide temperature range, a novel idea which based on the mechanism of skin wound healing for preparing self-healing of anti-oxidation coating has been designed. Details for the novel idea are as follows: first, the Si nanawires coated with SiC film (Si/SiC co-axial nanowires) are designed and introduced in the coating. Then, the Si/SiC co-axial nanowires and ZrB2 could efficiently heal the defects of cracks and holes in the coating by various toughening mechanisms including the toughening effect of nanowires and melt flow properties of Si driving by the high temperature compressive stress, as well as the high temperature oxidation expansion and scarring effect of ZrB2, so as to achieve of long-life and wide temperature range protection for C/C composites under high and low temperature alternating environment. To investigate the novel coating, the preparation technology and formation mechanism of self-healing silicon-based ceramic coatings will be systematically investigated. Meantime, the synergistic effects of Si/SiC co-axial nanowires and self-healing phase (ZrB2) on the microstructure, phase composition and distribution of the coatings will be illuminated. In addition, the relationship between the microstructure and oxidation resistance of the coatings will be established, revealing the mechanism of self-toughening and flow healing. Ultimately, these studies lay the foundation for the wide temperature range anti-oxidation application of the coating in aerospace industry.

针对碳/碳（C/C）复合材料表面硅基陶瓷涂层因热膨胀失配易开裂、抗热震与宽温域防护性能差的难题，提出一种基于皮肤伤口修复机制构建自愈合抗氧化涂层的新思路，即首先通过在硅基陶瓷涂层中引入涂覆SiC薄膜的Si纳米线（Si/SiC同轴纳米线），利用纳米线增韧作用和高温压应力驱使下Si的熔融流动特性，以及在涂层中引入的ZrB2高温氧化膨胀结疤效应，有效愈合涂层中的裂纹与孔隙等缺陷，实现涂层在高低温交变苛刻环境下对C/C复合材料的宽温域长寿命防护。系统研究自愈合硅基陶瓷涂层的制备工艺条件和形成机理，阐明Si/SiC同轴纳米线与自愈合ZrB2相协同改性对涂层微观形貌、相组成与分布的影响规律，确立涂层微观结构与防氧化性能之间的关系，揭示其自增韧与流动愈合机理，为将其应用于航空航天领域宽温域防氧化奠定基础。

陶瓷涂层脆性大易开裂，高低温交变环境中易产生裂纹而失效和涂层中孔隙、裂纹等缺陷愈合能力不足等问题导致陶瓷涂层热防护效果下降。针对以上问题，本项目提出一种基于皮肤伤口修复机制构建自愈合抗氧化涂层的新思路，即向涂层中引入含自愈合相的核壳结构纳米线或引入ZrB2等具有愈合能力和氧化膨胀特性的物相实现陶瓷涂层韧性和自愈合性能的同步提升。主要成果如下：.1、开发出一系列核壳结构纳米线，包括SiC@SiO2nw、Al-SiC@SiO2nw和SiC@SiO2@TiO2nw。通过控制系统中前驱体浓度、沉积时间和催化剂种类实现了高长径比和尺寸厚度均匀的核壳结构纳米线的可控制备。.2、利用化学气相沉积技术成功制备SiC@SiO2nw、Al-SiC@SiO2nw和SiC@SiO2@TiO2nw增韧SiC涂层，核壳结构可通过增加涂层内界面数量和纳米线拔出等机制实现涂层韧性的提高，从而提升涂层抗热震性能。Al和Ti元素可通过降低SiO2粘度有效提升涂层的自愈合性能。.3、引入PyC-SiC双层界面相后，涂层中存在纳米线多级拔出现象，抗冲击-烧蚀性能明显提升，与仅引入PyC界面相相比，线烧蚀率和质量烧蚀率明显下降。烧蚀过程中SiC@PyC@SiCnw/HfC涂层在氧化层破损处会生成具有自愈合性能的Hf-Si-O玻璃，有利于涂层抗烧蚀性能的提升。.4、采用气相渗硅工艺制备了ZrB2-SiC-Si涂层。借助涂层氧化生成ZrSiO4/ZrO2体积膨胀产生的压应力抑制裂纹扩展和以ZrSiO4/ZrO2为镶嵌相的致密高阻氧Zr-Si-O玻璃层的协同作用，表面形成的ZrSiO4颗粒钉扎SiO2玻璃层能抑制氧气的扩散，并与涂层形成多相镶嵌结构，阻碍裂纹扩展。.5、借助自愈合相的愈合作用和ZrB2的氧化膨胀特性开发出多种自愈合涂层体系。TiB2和SiB6均可促进涂层中产生硼硅酸盐玻璃等低熔点相实现缺陷快速愈合。ZrSiO4/ZrO2体积膨胀及钉扎作用和硼硅酸盐玻璃相的愈合作用可实现减小裂纹尺寸的同时快速愈合裂纹等缺陷。.项目研究过程中，共发表17篇SCI收录学术论文，培养硕士生5名，博士生6名，授权发明专利4件，获教育部自然科学一等奖，申请人获批国家杰出青年基金。

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