抗空间环境损伤的聚铝硅氮烷基涂层的制备及性能研究

It has been recognized that the atomic oxygen (AO), which is predominant component in low Earth orbit (LEO) environment, is one of the most important factors that cause degradation and failure of exterior polymeric parts of the spacecraft. So protection for polymeric surfaces is needed to make them durable in LEO environment. The investigation of AO erosion effect and protective technology of spacecraft materials has aroused more and more attention in recent years. The polyaluminasilazane (PASZ) preceramic polymer with the excellent thermal stability, oxidation resistance and corrosion resistance is considered to be a promising candidate as coating materials to protect space materials from AO erosion. Liquid-phased PASZ precursors will be synthesized by designation of coating composition and optimization of the process. Smooth and compact polyaluminasilazane-based coatings with good adhesion and crack-free will be prepared on polyimide substrates by dip-coating and spin-coating process. The erosion effect of AO, VUV, thermal cycle on the resultant coatings will be extensively investigated in the LEO environment ground-based simulator. A series of advanced analytical techniques will be used to characterize the chemical structure and compositions of the coatings after exposed in LEO simulation conditions. The correlations of chemical structure and composition of the coatings with their erosion resistance in space environment will be clarified. The erosion mechanism of the material and the formation and failure mechanism of the inert layer on the surface of the coatings will be explored. Then the models of the synergistic effect and protective performance degradation of the materials in space environment will be established. It will facilitate the understanding of the micro-mechanisms of material erosion processed in LEO space environment. This project aims to reveal the erosion rule of the class of polysilazane polymer in the LEO environment, and furthermore, to lay a theoretical foundation for the development of a novel self-healing coating system in LEO environment. The research is of great importance to promote the development of spacecraft with long-life and high-reliability.

近地轨道以原子氧为主的空间环境是导致航天器外露聚合物基材料失效的主要因素。为保证航天器的正常运行，必须对材料表面进行防护。新型聚铝硅氮烷先驱体聚合物具有优异的抗氧化和耐腐蚀性能，在原子氧防护涂层方面有很好的应用前景。本项目拟通过涂层成分设计和合成工艺优化制备聚铝硅氮烷基涂层；利用空间环境模拟装置研究原子氧/紫外/热循环对涂层的损伤效应。运用各种表征手段，系统分析涂层表面氧化层的成分、形貌、组织、结构，探索涂层的结构和成分与抗侵蚀性能之间的关系；探讨空间环境对材料的协同效应作用机制及惰性层的形成和失效机理；建立空间环境综合效应与防护性能退化模型，从而加深对空间环境中材料侵蚀过程微观机制的理解。本项目旨在揭示聚硅氮烷类聚合物在空间环境中的侵蚀规律，为发展抗空间环境损伤具有自愈性能的新涂层体系奠定理论基础。研究内容对于促进国家长寿命高可靠航天器的发展具有重要意义。

原子氧是低地轨道空间中对航天器外露材料危害性最大的环境因素。空间材料的原子氧效应严重影响了低地球轨道航天器的性能和寿命，是近年来国内外空间环境效应研究领域的热点课题之一。为保证航天器的正常运行，必须对材料表面进行防护。新型聚铝硅氮烷先驱体聚合物具有优异的抗氧化和耐腐蚀性能，在原子氧防护涂层方面有很好的应用前景。本项目以聚硅氮烷基涂层材料为研究对象，利用空间环境模拟装置，通过微天平，SEM，XPS，FTIR等分析测试手段研究了材料的原子氧侵蚀效应。系统分析了涂层表面氧化层的成分、形貌、组织、结构，探索涂层的化学结构和成分与抗侵蚀性能之间的关系；探讨空间环境对材料的协同效应作用机制及惰性层的形成和失效机理；建立空间环境综合效应与防护性能退化模型。通过聚硅氮烷与异丙醇铝反应合成了聚铝硅氮烷，将聚铝硅氮烷在Kapton表面制备防护涂层，利用原子氧模拟设备对防护效果进行研究。通过仪器分析检测，结果表明聚铝硅氮烷作为防护涂层具有良好的原子氧抵抗性能，主要由于防护涂层与原子氧作用后形成了SiO2/Al2O3复合氧化层，与基体相比，原子氧侵蚀系数下降了2个数量级。通过氨解二氯硅烷合成了聚硅氮烷，利用浸渍-提拉法将聚硅氮烷在聚酰亚胺表面制备涂层并进行了原子氧暴露实验，分析结果表明，该聚硅氮烷防护涂层能够对Kapton起到很好的防护作用。该防护涂层在暴露过程中能够形成SiO2氧化层，对基底形成良好的保护作用，10 h的原子氧暴露结果表明，原子氧侵蚀系数降低了2个数量级。利用全氢聚硅氮烷（PHPS），在Kapton表面制备了防护涂层，在原子氧模拟设备中进行原子氧暴露后，结果表明PHPS涂层能够有效提高Kapton的抗原子氧侵蚀性能，由于PHPS能够较快的生成SiO2氧化层，原子氧侵蚀系数降低了约3个数量级。本项目将为发展原子氧防护涂层新体系提供一种途径，为空间选材奠定理论基础。