高辐射涂层的柔性化设计及其机理

High emissivity coating on ceramic fiber rigid insulation tiles is one of the most important factor for security service of hypersonic reusable launch vehicles because of its both effects of re-radiate heat away to reduce surface temperature and thermal shock resistance to keep stable performance at temperature shifts up to 1500℃. Being aimed at actual national needs and existed problem in this research areas, a new method to make traditional glass-based coating flexible is advanced in this project. Based on MoSi2-borosilicate glass coating system, a preformed  weblike polygon cracking was prepared in initiative coating by controlling drying conditions, which was subsequently filled with a precursor component of mullite whisker, and a sort of flexible snakeskin-like coating was formed with scalelike glass coating connected by whisker interfaces by suitable heat treatment. It would be investigated for component adjusting and process controlling to form aforementioned coating structure. By analyzing microcosmic growth pattern of the whisker in the cracks and the mechanism to make coating macroscopic flexibility, a new method was advanced to make brittle glass based coating flexible. As a result, a sort of coating with high emissivity, eminent temperature tolerance and thermal shock resistance would be prepared to meet the need of developing new generation advanced defense-related weaponry and equipment in our country.

陶瓷纤维刚性隔热瓦表面的高辐射涂层兼备辐射散热降低表面温度和抵抗循环热冲击维持结构完整的双重效果，是高超声速、可重复使用类飞行器安全服役的可靠保障。结合国内在此研究领域存在的问题和实际需求，本项目提出一种使传统玻璃基涂层柔性化的新方法，使其在维持高辐射率基础上，提高抗热冲击性，适应新一代飞行器长时高速的服役环境。基于“二硅化钼/硼硅酸盐玻璃”涂层体系，通过控制干燥工艺在初始涂层表面形成网状龟裂纹，在裂纹缝隙中设置莫来石晶须生长组分，经热处理形成玻璃态鳞片涂层与晶须界面构成具有柔性特征的“蛇皮”类涂层结构。研究实现该涂层结构的组成调整和工艺控制条件，分析晶须在缝隙中生长及其对涂层宏观柔性化的机制，探索玻璃态脆性涂层实现柔性化的新方式，制备耐高温、抗热冲击、安全可靠的高辐射涂层，满足我国新一代国防武器装备在安全服役等方面的研发亟需，为更广泛耐高温无机类玻璃基脆性涂层的柔性化提供新思路。

陶瓷纤维刚性隔热瓦表面的高辐射涂层兼备辐射散热降低表面温度和抵抗循环热冲击维持 .结构完整的双重效果，是高超声速、可重复使用类飞行器安全服役的可靠保障。结合国内在此研究领域存在的问题和实际需求，本课题研究了一种使传统玻璃基涂层柔性化的新方法，使其在维持高辐射率基础上，提高抗热冲击性，适应新一代飞行器长时高速的服役环境。主要研究内容包括“鳞片状MoSi2-硼硅酸盐玻璃涂层的制备与结构控制”，“纤维增强鳞片状MoSi2-玻璃基涂层的制备与力学性能研究”，“溶胶基MoSi2系免烧防热涂层的制备和性能研究”及“MoSi2-硼硅酸盐玻璃基高发射率梯度涂层的制备和力学性能研究”，完成了针对先进飞行器热防护系统的高辐射涂层，以“二硅化钼/硼硅酸盐”玻璃态涂层体系为基础，通过控制涂层干燥形成龟裂纹获得类似“蛇皮”的“鳞片”结构，并在鳞片间隙中设置莫来石晶须和纤维的组织结构，制备具有柔性特征且具有优良的抗热冲击性的高辐射涂层，并探讨柔性化机理的研究目标。.研究结果表明：（1）利用料浆法与溶胶凝胶法相结合，可以在纤维基体上制备具有裂纹网络的鳞片状以MoSi2为辐射剂的硼硅玻璃（BSG）涂层；料浆中的骨料颗粒级配对涂层结构起决定性作用；具有连贯小裂纹网络的涂层具有更高的结合强度、更好的抗损伤性能和抗热冲击性能。（2）在涂层中引入陶瓷纤维，可以有效的减小裂纹网络中裂纹宽度和裂纹面积，结合其在鳞片间的桥联作用进一步提高了涂层的抗接触损伤和抗热震性。（3）涂层中加入惰性骨料可以降低涂层收缩率，减小涂层与基体间的应力，调整裂纹结构进一步提高涂层的抗热震性。（4）具有多孔界面层和致密表面层的双层梯度 MoSi2-硼硅酸盐玻璃涂层，具有更高的承载能力，并且避免了辐射状裂纹的产生和扩展。使其具有最优异的抗热震性。具有梯度界面结构的双层梯度涂层表现出更高的界面结合强度。