Polytetrafluoroethylene composite material with high alternating-current breakdown field strength as well as preparation method and application thereof

The invention discloses a polytetrafluoroethylene composite material with high alternating-current breakdown field strength as well as a preparation method and application thereof. According to the method, polytetrafluoroethylene is used as a matrix, micron-scale and nano-scale boron nitride is used as filler, and the micro-nano boron nitride co-doped polytetrafluoroethylene composite sample is prepared through the steps of mixing, mould pressing, sintering, machining and the like. Polytetrafluoroethylene is modified by doping micro-nano boron nitride, and the optimal total mass fraction of doping is 7%. According to the method provided by the invention, the aggregation state structure of the polytetrafluoroethylene/boron nitride composite material is greatly changed, the trap parameters of the composite material are changed, the alternating current breakdown field intensity of the composite material is remarkably improved, and the method can be widely applied to the field of preparation of high-voltage circu