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Carbonization of epoxy resin under high voltage discharge or exposure to high temperatures results in insulation failure. Herein, multiscale spherical boron nitride (SBN) epoxy resin is developed with improved anticarbonization properties. The thermal conductivity, thermostability, dielectric performances, volume resistivity, breakdown strength, and flame retardancy of the epoxy-SBN composites were studied. The thermal conductivity, thermostability, volume resistivity, and breakdown strength of epoxy-SBN composites are higher than that of pure resin, with a ratio of high thermal conductivity of 24 and a volume resistivity of ∼10. The AC breakdown voltage of the epoxy-30SBN composites was as high as 29.96 kV/mm. In addition, epoxy-30SBN composites possess minimal carbonization surface area under high-voltage discharge. Increased thermal conductivity, lower mass loss rate, high flame resistance, and inhibited charge carrier migration contribute to the improved carbonization resistance of the arc. Densified SBN networks in epoxy resin act as a dense barrier to achieve anticarbonization under high voltage stress or high-temperature exposure. Therefore, epoxy-SBN composites are promising candidates for application in next-generation high-voltage devices to ensure electrical safety.
Wang et al. (Mon,) studied this question.