短碳纳米管/氧化铝结构吸波材料的制备及其高温电磁性能研究

This project bases on carbon nanotubes(CNTs) reinforced alumina ceramic composites synthesized by hydrothermal crystallization. The CNTs will be shortened to investigate the relationship between the aspect ratios and treatment processes, and the optimized parameters for interface treatment and high-performance composites will be discussed. The effects of shortening process for CNTs on the strength, flexibility, thermal stability and resistance will be studied and related enhancement mechanism will be discussed. The electrical conductivity, high-temperature dielectric properties and microwave absorption performance will be evaluated to investigate the temperature- and frequency-dependent dielectric and microwave absorption characters in such dielectric-dominating composites. The balance between the treatment process and filler loading will be taken into account to achieve enhanced microwave absorption coupled with reinforced mechanic properties, resulting in high performance structural-functional composites. The research achievements will establish the academic and experimental foundations for the applications of CNTs in high-temperature microwave absorption field, providing new feasible research thoughts for design of heat-resistant invisible materials, promoting the research and development of high-temperature microwave absorbing materials, realizing the technological progress of key materials in cruise missile and aircraft with ultrahigh mach, supporting the medium and long-term development of composite materials with a collection of invisible, heat-resistant and structural functions. Meanwhile, the research will also be conducive to the development of science and creativity of technology in the fields of electromagnetic interference shielding technology, electromagnetic compatible technology, information security technology and so on. It is exhibited the research has fine social efficiency.

基于水热结晶法制备碳纳米管增强氧化铝复合材料。通过研究碳纳米管"剪短"处理工艺与长径比的响应关系以及界面相的可控制备工艺，探寻稳定性好的材料复合工艺；研究"剪短"后碳纳米管对基体材料强度、韧性、耐热性和隔热性的影响规律，探索该材料体系的增韧机理和热学行为特性；研究复合材料的导电性、高温介电和吸波特性，探索介电型吸波材料高温微波介电性能随温度和频率的响应本质和演变规律。在此基础上，通过调节碳纳米管吸波剂的微处理工艺和添加量协调复合材料结构力学性能和微波吸收性能的关系，实现其结构与吸波功能一体化。研究成果将为碳纳米管在高温吸波领域的应用研究奠定理论和实验基础，促进高温吸波材料研发，实现超高马赫巡航导弹及飞行器关键材料技术进步，支撑隐身/防热/结构一体化的复合材料的中长期发展。同时，本项研究还有利于电磁屏蔽与防护技术、电磁兼容技术、信息安全技术等领域科学发展和技术创新，具有一定的社会效益。

本项目采用水热法制备了短碳纳米管/氧化铝结构吸波材料。并完成了碳纳米管的“剪短”处理及分散性研究；水热法制备短碳纳米管/氧化铝陶瓷复合材料的工艺研究；短碳纳米管对氧化铝基体力学性能的影响规律及机理研究；短碳纳米管/氧化铝复合材料高温抗氧化性及导热性能研究以及短碳纳米管/氧化铝复合材料高温电磁性能研究。得出结论：混酸浸泡72h处理后，碳纳米管长径比有效减小，且絮状团聚结构打开。复合材料断裂时，碳纳米管被拔出，大幅提升了碳纳米管/陶瓷基复合材料力学性能。相同碳管含量下，温度的升高也有利于提升复合材料的复介电参数，随着碳管含量的增加，复合材料的微波反射率都有增大的趋势，但随着温度的升高，复合材料的吸波性能有下降的趋势。另外当碳管质量分数为5%和7%，温度低于150℃时制备的复合材料在整个X波段都具有低于-10dB的微波反射率。因此，说明碳纳米管/氧化铝陶瓷复合材料具有良好的吸波应用前景，可推广应用于高温环境下的材料隐身。

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