大型超导磁体用导热树脂基绝缘材料及低温特性研究

Cryogenic insulating materials play important role in large-scale magnetic confinement nuclear fusion superconducting magnet. To ensure stable operation of superconducting magnet, insulating materials should meet the exceptional requirements in terms of mechanical, electrical and magnetic properties. Meanwhile, cryogenic thermal conductive properties cannot be ignored and should also be taken into consideration. Therefore, graphene oxide (GO) will be adopted to modified glass fiber/cyanate ester/epoxy composites in this project. Effects of the dispersion and interfacial bonding of GO in composites on cryogenic properties in terms of dielectric, mechanical and thermal conductive properties will be investigated. The relationship between “process-microstructure-property” of novel cryogenic insulating materials will be established to guide the material design so that Electrical insulating materials which exhibit excellent mechanical and thermal properties will be manufactured. The project could establish the basis for the novel insulating materials application in large scale superconducting magnet.

低温电绝缘材料是磁约束聚变堆大型超导磁体中关键材料。为保证聚变堆中超导磁体的安全可靠运行，绝缘材料除了需要满足特殊环境下的力、电、磁性能外，低温导热性能也是不容忽视和亟待解决的。为此，本项目拟采用氧化石墨烯对玻璃纤维增强氰酸酯/环氧树脂基复合材料进行掺杂改性，研究氧化石墨烯的分布及界面对纳米复合材料低温介电特性、力学性能及导热特性的影响规律，建立新型低温绝缘材料“工艺-微结构-材料性能”之间的关联，指导材料优化设计，发挥氧化石墨烯的优异性能，制备出在低温下具备高强高韧高导热率的电绝缘材料，为新型绝缘材料在大型超导磁体中应用奠定基础。

低温电绝缘材料是磁约束聚变堆大型超导磁体中关键材料。为保证聚变堆中超导磁体的安全可靠运行，绝缘材料除了需要满足特殊环境下的力、电、磁性能外，低温导热性能也是不容忽视和亟待解决的。本项目以调节环氧树脂基绝缘材料的热学性能为目标，选取低温环氧树脂为基体材料，以氧化石墨烯和氮化硼为导热填料，设计并制备了多种导热绝缘材料，研究了填料含量、尺寸、形貌及制备工艺对绝缘材料低温性能的影响。研究结果表明，当氧化石墨烯的加入量为0.5 wt.%时，复合材料在6 K温度下的导热性能提高190%。在10 wt%氮化硼纳米管填充量下，环氧树脂复合材料热导率达到1.6 W•m-1•K-1，是纯环氧树脂热导率的6.5倍，并具有低热膨胀系数。通过自组装及真空浸渍法制备的3D-BNNT-GONS改性环氧树脂复合材料，在11.6 vol%3D-BNNT-GONS填充量下，材料热导率达到4.5 W•m-1•K-1，比纯环氧树脂提高近20倍，并且保持高绝缘性。冷热循环过程中，材料具有高吸热散热效率，展现出优异的热处理性能。本研究工作为解决环氧树脂在低温工程应用中的低导热以及热膨胀不匹配问题提供了新思路，为大型超导磁体的发展奠定了材料基础，拓宽了环氧树脂的研究和应用领域。