高温密封腻子材料设计及其粘弹性机制研究

For sealing of narrow gap and repairing of small cracks in thermal protection system of hypersonic vehicles, a sort of putty material consisted of organic–inorganic-fibers hybrid material as an adhesive and sealant in the patch/plug concept is investigated. It is expected that a better bond force is kept in both expending deformation and deforming recovery states by a basis study on the sticking and elastic performances. Based on pull-off of fibers from sticking matrix with a weak bond interface among them, volume expansion with the organic-inorganic transformation and oxiding reaction of adding component and viscous flow taking place in microstructure adjusting and reforming processes at elevated temperature, a series of special performances are designed and studied such as plasticity, viscoelasticity, volume expansion and thermal stability. The effects of components, temperature and load on microstructure, plasticity, volume expansion, stickness, deformation and.deformation recovery will be studied, revealing the innate character of stickness and deformation recovery. As a result, it will be making clear for the main factors to influence viscoelasticity, and finding out intrinsic propesties of viscoelasticity and variety regulation of elastic deformation under different temperature and loading conditions for this putty seal material, as a basis of new materials design in more application area related to jion, seal and repairing at elevated temperature.

针对高超声速飞行器热防护系统的缝隙密封和缺陷修复，提出一种“有机-无机-纤维”复合、介于糊状和可塑状之间的膏状胶粘类耐高温密封腻子材料，并针对其粘性、弹性特征开展基础研究，使其适于热胀或受力时产生变形、冷缩或撤载时变形恢复，并在变形和恢复双向状态维持较高的粘结力。基于纤维-胶态基体弱结合形成的纤维拔出效应、有机组分的常温粘结和可塑性效果、添加组分高温转化的体积膨胀，以及随温度变化材料微观结构调整和重建导致的粘性流动，使其呈现耐高温、粘弹性，兼备常温可塑性、低温微膨胀和高温体积稳定性；研究材料的微观结构、可塑性、体积膨胀、粘结强度、变形量和变形恢复随组分、温度的变化规律，揭示材料在不同温度、载荷条件下的粘结、变形特征及其调节、控制因素；阐明材料粘弹性的形成机理及其对材料宏观粘结强度、弹性变形和变形恢复的作用机制，为更广泛领域的高温粘接、密封和缺陷修复材料设计奠定基础。

针对高超声速飞行器热防护系统的缝隙密封和缺陷修复，研制了一种“有机-无机-纤维”复合、介于糊状和可塑状之间的膏状胶粘类耐高温密封腻子材料，并针对其粘性、弹性特征开展了基础和应用研究，使其适于热胀或受力时产生形变或撤载时形变恢复过程的结构调整，并在形变和形变恢复双向状态时维持较高的粘结力。基于纤维-胶态基体弱结合提供的纤维拔出效应、有机组分的常温粘结和可塑性效果、添加组分高温转化的体积膨胀，以及随温度变化材料微观结构调整和重建导致的粘性流动，使这种“腻子”呈现耐高温、粘弹性，兼备常温可塑性、低温微膨胀和高温体积稳定性；通过研究材料的微观结构、可塑性、体积膨胀、粘结强度、变形量和变形恢复随组分、温度的变化规律，揭示了材料在不同温度、载荷条件下的粘结、变形特征及其调节、控制因素。研究结果表明：通过环氧树脂与甲基硅树脂共混共聚，延长聚合物分子链，并形成互穿网络结构，提高聚合网络分解温度，与陶瓷转化温度形成交叉温区，补偿传统高温胶在 400℃到 600℃的“弱粘结阶段”，从室温到 1500℃各个温度热处理后的常温测试剪切强 度均高于9.29±0.56MPa，而从 室温到 800℃各个温度直接测试剪 切强度均高于 8.21±0.40MPa。并采用双变量（铝粉和碳化硼含量）控制，优化最佳填料配比，实现胶粘剂在1000℃以上粘结强度提升，保证其高温粘结强度。同时采用双变量（温度和固化剂含量）控制，优化固化工艺，实现高温腻子低温或室温固化，工艺 简单，安全，成本低廉。