氧化物基热密封材料的高温弹性模量与变形行为研究

Based on an idea that the elastic deformation might depend mainly on self-deformation of components and interfacial binding force among them at elevated temperature for thermal seal materials,it's investigated that elstic modulus and deformation at elevated temperature in a way of adjusting microstructures,which was different from those thinking of it in terms of interatomic binding traditionally. A set of device designed is used to determined compression-recover behaviour at elevated temperature for different thermal seal materials, and the relationship among temperature,load,loading time and deformation is studied. Conbining the analysis of microstructure in various of seal materials, the effects of self-deformation of components, interfacial form and interatomic binding on elastic deformation are analysed. As a results, it will be making clear what is the main factor and the effect order to influence high-teperature elastic modulue,and finding out intrinsic propesties of elastic modulus and change regulation of elastic deformation at elevated temperature for oxide-based thermal seal materials, as a basis of design and application of thermal seal materials.

针对热密封材料的高温弹性变形，提出材料组元（颗粒、纤维、气孔等）分布、自身变形和组元间结合状态是其主要影响因素的设想，区别于以原子间结合为主导进行弹性模量计算或模型分析的传统方法，在低应力、高温状态下，研究微结构形式变化对材料弹性模量及其变形规律的影响。基于不同氧化物基热密封材料体系，通过设计高温压缩-回弹动态试验装置，结合高温力学性能测试，研究温度-载荷-时间-变形关系；结合不同条件下的材料结构分析，获得高温状态弹性变形与组元自身变形、界面结合变化、原子间结合等因素的相互关系，弄清不同温度下弹性变形的控制因素或制约次序，探索氧化物基热密封类材料高温弹性模量本质及其弹性变形规律，为国家先进航天器热密封设计和应用提供依据。

耐高温隔热材料是飞行器热防护系统的重要组成部分。高超声速飞行器在穿越大气层过程中会遭遇高温极端环境，机身表面的高温隔热组件会因热膨胀而产生极大应力。这种热应力会导致隔热组件开裂，从而引发隔热系统的热密封失效，进而严重威胁飞行器的安全飞行。针对上述热密封失效问题，基于莫来石纤维材料为主，兼顾氧化铝-氧化锆非晶陶瓷和莫来石涂层-莫来石编织材料三类典型的氧化物基热密封材料，研究了材料温度-载荷-变形的关系，结合不同条件下的材料结构分析,阐明了不同温度状态弹性变形与组元自身变形、界面结合变化、原子间结合等因素的相互关系。研究表明，莫来石纤维基陶瓷，其弹性模量主要取决于结点结合强度、纤维体积分数和纤维长径比，莫来石原子间作用力只通过影响纤维不同温度下的纤维自身变形起到微弱的影响；非晶氧化铝-氧化锆陶瓷变形的两种重要机制是剪切带和结构致密化，其中剪切带在非晶陶瓷变形中起到绝对主导作用，其形成原因是由于自由体积为剪切应力作用下大量原子的定向跃迁提供了足够的空间，随后形成剪切转变区域；莫来石-莫来石编织材料的弹性变形主要取决于编织体的编织体积分数和编织方式。这些氧化物基热密封材料不同温度范围的弹性本质及其变形规律，为国家先进航天器热密封设计和应用提供依据。