Tian Fuqiang, Cao Jinmei, Li Yiming
School of Electrical Engineering, Beijing Jiaotong University, Beijing 100044, China.
State Grid Beijing Electric Power Company Maintenance Branch, Beijing 100089, China.
Nanomaterials (Basel). 2022 Jun 23;12(13):2155. doi: 10.3390/nano12132155.
As the main insulation of high-voltage motors, the poor mechanical and thermal conductivities of mica paper restrict the motor's technological advances. This paper prepared multilayer toughening mica composites with a highly ordered "brick-mud" stacking structure by mimicking the natural conch nacre structure. We investigated the mechanical, thermal, and breakdown properties by combined study of tensile strength, stiffness, thermal conductivity, and breakdown strength at varying mica and nanocellulose contents. The results show that thermal conductivity of the mica/chitosan composites were gradually enhanced with the increase in mica content and the composite shows the optimal synthetic performance at 50 wt% mica content. Further addition of the nanocellulose can extremely enhance the thermal conductivities of mica/chitosan composites. The composite with 5 wt% nanocellulose obtained the maximal thermal conductivity of 0.71 W/(m·K), which was about 1.7 times that of the mica/chitosan composite (0.42 W/(m·K)) and much higher than normal mica tape (0.20 W/(m·K)). Meanwhile, the breakdown strength and tensile strength of mica/chitosan/nanocellulose composite also demonstrated substantial improvement. The application of the mica/chitosan/nanocellulose composite is expected to essentially enhance the stator power density and heat dissipation ability of large-capacity generators and HV electric motors.
作为高压电机的主要绝缘材料，云母纸较差的机械和热导率限制了电机的技术进步。本文通过模仿天然海螺珍珠层结构，制备了具有高度有序“砖-泥”堆叠结构的多层增韧云母复合材料。我们通过对不同云母和纳米纤维素含量下的拉伸强度、刚度、热导率和击穿强度进行联合研究，来考察其机械、热和击穿性能。结果表明，云母/壳聚糖复合材料的热导率随着云母含量的增加而逐渐提高，且在云母含量为50 wt%时复合材料表现出最佳的综合性能。进一步添加纳米纤维素可极大地提高云母/壳聚糖复合材料的热导率。含有5 wt%纳米纤维素的复合材料获得了0.71 W/(m·K)的最大热导率，约为云母/壳聚糖复合材料（0.42 W/(m·K)）的1.7倍，远高于普通云母带（0.20 W/(m·K)）。同时，云母/壳聚糖/纳米纤维素复合材料的击穿强度和拉伸强度也有显著提高。云母/壳聚糖/纳米纤维素复合材料的应用有望从根本上提高大容量发电机和高压电动机的定子功率密度和散热能力。
