Influence of cryogenic temperatures on DC surface flashover characteristics of BNNS-based epoxy nanocomposites

Epoxy resin (EP) is widely used in cryogenic and high-temperature superconductivity related fields for its excellent low-temperature mechanical properties. However, the strong electric field can cause flashing along the surface of EP, which further leads to the destruction of the construction. Herein, to improve the reliability of the insulation structure at cryogenic temperatures, the Boron Nitride Nanosheets (BNNS) Based Epoxy Nanocomposites with improved electrical insulation properties have been prepared. The changes in surface flashover characteristics at 10 temperatures from 10 K to 299 K were detailed studied. Meanwhile, the trap distribution characteristics of composite materials were studied, and the mechanism of BNNS on the surface flashover of composites was analyzed. The results show that the addition of BNNS has a negative effect on improving surface flashover strength at 10 K, and the BNNS content of 1 wt% to 3 wt% BNNS can achieve higher flashover strength of composites at other temperatures. Moreover, unlike pure epoxy resin, the flashover strength of the composites increases first and then decreases with the temperature decrease, which has a maximum point.