碳酸丙烯酯基纳米液体介质脉冲击穿特性及其改性机理

Propylene carbonate, due to its great permittivity, high dielectric insulating strength and wide range of environmental adaption, has a great potential in improving the compact level of pulse power system as a kind of high energy storage density liquid dielectric. However, continuous improvements in the insulating strength and energy storage density of liquid dielectric have been restricted by traditional processing technology, which constrains the development of propylene carbonate based pulsed power system with high power and compact structure. This project puts forward a new idea that the nano-particle modifying technology should be used to enhance the energy storage performance of base liquid, which will achieve interdisciplinary integration between pulse power technology and nano-materials science. Firstly, the stable and reliable propylene carbonate based nano-fluids with double energy storage density will be obtained with the help of microscopic analysis method in the microsecond regime. Secondly, the key problem of nano-fluids’ environmental adaptability can be explored and solved, so nano-fluids based pulse forming line will operate without maintenance. These efforts set a solid technical foundation of nano-fluids’ application in compact pulse power system. Finally, the effect of nano-particles on the space charge distribution and trap reconstruction in base liquid will be investigated by pulse electro-acoustic technique and thermally stimulated current method. Based on the liquid band model and basic effect of nano-material, the possible mechanism leading to the enhanced insulating strength of nano-fluids can be presented, which will explain the effect of nano-particles with different parameters on the dielectric breakdown performances of base liquid and further enrich the nano-fluids’ breakdown theory.

碳酸丙烯酯具有介电常数大、绝缘强度高、环境适应范围广等优点，作为高储能密度液体介质，在提高脉冲功率系统的紧凑化程度方面潜力巨大。然而受限于传统处理工艺，其绝缘强度与储能密度难以持续提高，极大地约束了碳酸丙烯酯基脉冲功率系统的紧凑化发展。本项目提出将纳米掺杂技术应用于提高碳酸丙烯酯脉冲储能特性，实现脉冲功率技术与纳米材料科学的交叉融合。项目组将借助微观分析手段，研制出稳定可靠的碳酸丙烯酯基纳米液体，并将其创新性地应用到微秒脉冲储能中，实现基液储能密度提高一倍；探索并解决纳米液体环境适应性的关键难题，实现纳米液体基脉冲形成线的免维护运行，为纳米液体应用于紧凑脉冲功率系统奠定坚实的技术基础；通过对纳米液体的空间电荷、陷阱特性进行测量，基于液体能带模型和纳米材料基本效应，建立纳米掺杂提高基液脉冲绝缘强度的物理模型，解释纳米粒子不同参数影响基液脉冲击穿特性的实验规律，丰富纳米液体击穿理论。

脉冲功率技术的重要发展方向是高功率和结构紧凑，核心和关键就是提高储能密度。碳酸丙烯酯具有介电常数大、绝缘强度高、环境适应范围广等优点，在提高脉冲功率系统的紧凑化程度方面潜力巨大。然而，现有的液体介质由于受传统处理工艺的限制，储能密度与耐压稳定性很难再持续提高，极大地约束了脉冲功率技术的发展。项目组通过对各种性质的纳米粒子改性碳酸丙烯酯展开微秒脉冲击穿实验研究，获取了纳米液体的脉冲击穿强度随纳米材料、体积分数和粒径变化的实验规律，得到了纳米液体微秒脉冲击穿的最佳参数，在此基础上，对所获得最佳参数的纳米粒子进行表面修饰，确保纳米液体的长期稳定保持；对碳酸丙烯酯/纳米改性碳酸丙烯酯预击穿过程中流注的产生、传播与截止进行了系统的研究；对TiO2纳米粒子改性碳酸丙烯酯脉冲绝缘特性的机理进行了实验研究，包括纳米粒子改性基液空间电荷、陷阱分布，建立了纳米改性碳酸丙烯酯能带模型与电场电机械应力模型，并对纳米液体正负极性脉冲击穿特性进行了分析；建立了纳米液体介质精纯与真空灌注脉冲形成线一体化处理系统，进行了碳酸丙烯酯与纳米液体脉冲形成线的实验调试和耐压测试研究，运用液体分子膜置换的方式可有效提高纳米液体电阻率；在此基础上，运用离子交换方式可将纳米液体电阻率进一步提高，且便于集成到纳米液体真空灌注形成线设备中；与碳酸丙烯酯基脉冲形成线相比，体积分数为1500 ppm的TiO2纳米改性碳酸丙烯酯脉冲形成线绝缘强度提高60%，最大储能密度提高150%以上，并具有更大的耐压稳定性；搭建了以碳酸丙烯酯基纳米液体为储能介质的脉冲功率源，并与微波源展开联试。总体而言，项目组通过运用纳米掺杂的方式改性碳酸丙烯酯，显著提升液体介质脉冲绝缘性能，研制出高储能密度纳米液体介质，进一步满足高功率微波技术对脉冲功率技术紧凑化的要求，展现出良好的应用前景。