Insulation failure and insufficient thermal management in electrical and electronic equipment threaten their safe and stable operation and restrict development toward high power and high integratio...

Oriented Boron Nitride Nanosheet Films for Thermal Management and Electrical Insulation in Electrical and Electronic Equipment

Electrically insulating boron nitride (BN) nanosheets possess thermal conductivity similar to and thermal and chemical stabilities superior to those of electrically conductive graphenes. Currently the production and application of BN nanosheets are rather limited due to the complexity of the BN binary compound growth, as opposed to massive graphene production. Here we have developed the original strategy "biomass-directed on-site synthesis" toward mass production of high-crystal-quality BN nanosheets. The strikingly effective, reliable, and high-throughput (dozens of grams) synthesis is directed by diverse biomass sources through the carbothermal reduction of gaseous boron oxide species. The produced BN nanosheets are single crystalline, laterally large, and atomically thin. Additionally, they assemble themselves into the same macroscopic shapes peculiar to original biomasses. The nanosheets are further utilized for making thermoconductive and electrically insulating epoxy/BN composites with a 14-fold increase in thermal conductivity, which are envisaged to be particularly valuable for future high-performance electronic packaging materials.

Biomass-directed synthesis of 20 g high-quality boron nitride nanosheets for thermoconductive polymeric composites

聚合物电介质在使用过程中表面会积聚大量的电荷, 导致局部电场畸变、闪络、爆炸和设备损坏等问题. 由于造成电荷积聚的聚合物载流子深陷阱的主要构成目前仍不清楚, 这一瓶颈问题目前仍未得到有效解决. 本文基于开尔文探针力显微镜(KPFM)和磁力显微镜(MFM)观测了纳米微区聚合物自由基的电荷行为, 发现自由基表现出深陷阱的特性. 第一性原理计算发现出现自由基后的体系中存在深能级缺陷态. 微观和宏观的电荷测量表明, 清除自由基后的聚合物表面电荷量显著减少, 这为聚合物电介质在诸多领域中的安全使用提供了有效的材料改性方案. 本文首次揭示了电介质中的自由基是深陷阱, 为后续关于聚合物电介质的电荷特性方面的研究提供了重要的理论指导. 

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Basic reason for the accumulation of charge on the surface of polymer dielectrics

A critical review of the preparation strategies of thermally conductive and electrically insulating polymeric materials and their applications in heat dissipation of electronic devices

Ultrafast battery heat dissipation enabled by highly ordered and interconnected hexagonal boron nitride thermal conductive composites

This paper describes the addition of ZnO nanoparticles to epoxy resin at concentrations of 20, 25, and 30wt%, and the application of this ZnO/epoxy coating to the surface of an epoxy insulator. This coating significantly suppresses the charge accumulation on the surface of the insulator, reduces the number of charge speckles, and increases the flashover voltage. These effects are enhanced as the doping concentration of ZnO nanoparticles increases. Through isothermal surface potential decay tests, we find that the ZnO/epoxy coating introduces numerous shallow traps, which help to dissipate the surface charge. Analysis shows that the ZnO/epoxy coating promotes surface charge dissipation through its nonlinear conductivity. The nonlinear characteristics of the 30wt%-doped samples are 55.3% greater than those of the 20wt%-doped samples. The coating adapts to the external electric field and can achieve the effect of a uniform electric field. This article analyzes the feasibility of using ZnO/epoxy coatings to suppress the accumulation of charge on insulator surfaces, and provides a feasible solution for practical engineering applications.

Cheng Liu

Papers

Nano ZnO/epoxy coating to promote surface charge dissipation on insulators in DC gas-insulated systems

Oriented Boron Nitride Nanosheet Films for Thermal Management and Electrical Insulation in Electrical and Electronic Equipment