先驱体法梯度折射率陶瓷微球的制备及红外阻隔机理研究

高温下辐射传热在材料内部传热中占很大比例，发展新型高效红外阻隔材料，通过微观尺度上对材料结构的调控，实现高效阻隔辐射传热，是提高材料高温隔热性能的重要途径。本项目采用先驱体转化法获得具有梯度折射率结构的陶瓷微球，利用其特有的光学性质实现高效抗红外辐射；并将其作为气凝胶的遮光剂，提高气凝胶高温隔热性能。重点探索梯度折射率微珠的颗粒尺寸、组成分布、梯度结构形式等在微观尺度上的调控技术，探讨梯度折射率微珠的微观结构形成过程、演变规律及其析晶动力学，建立微珠的梯度结构形式与其遮光性能之间的联系，分析其红外阻隔机理并构建遮光剂阻隔红外辐射特性预测模型。在此基础上探索梯度结构微珠对气凝胶复合材料的高温性能的影响规律，研究其界面耦合机制和高温隔热机制。本项目的研究为梯度折射率介质的构建及其红外阻隔机制提供理论基础，同时对开发高效红外阻隔材料，提高气凝胶等材料的高温隔热性能具有重要理论和实践意义。

Modifying the microscopic structure to achieve efficient thermal radiation shielding and developing a new and efficient infrared insulation material is an important way to improve thermal insulation properties of materials at high temperature, when the radiative heat transfer dominates. In this research we proposed to investigate ceramic microspheres with a gradient refractive index structure via precursor method. The microspheres with highly active anti-infrared radiation at high temperature can be obtained, and they will get unique optical and high temperature resistance properties. The particles could be adopted as opacifiers to improve high temperature insulating performance of aerogel. We will investigate the main factors on the gradient structure and established crystallization kinetics model by adjusting the reactants ratio, the aging and pyrolysis process parameters, the microspheres size, the distribution of composition gradient, and the crystallization process. The relationship between the gradient structure of the microspheres and the opacifying performance will be established though testing the opacifying capability of the microspheres, and the infrared insulation mechanism will be further studied. Then, the interfacial interaction between the microspheres and aerogel matrix will be also studied to explore the mechanism of high temperature insulation of the composites. The research provided a theoretical basis for the optimal design of structure and performance of infrared insulation materials. Meanwhile, the research gained an important theoretical significance to improve the high-temperature thermal insulating performance of aerogel.