Preparation method of nanoscale silicon dioxide coating

The invention discloses a preparation method of a nanoscale silicon dioxide coating, comprising the following steps: sufficiently drying superfine silicon dioxide at high temperature until water molecules attached to the surface completely volatilize; adding the dried superfine silicon dioxide to absolute ethyl alcohol as a solvent and then performing ultrasonic dispersion, so as to obtain a mixedsolution; adding a silane coupling agent to the mixed solution according to a certain proportion, heating and stirring under the protection of nitrogen until the reaction is sufficient; centrifugingand separating, filtering, washing and drying the mixed solution after complete reaction, so as to obtain silane coupling agent graft modified silicon dioxide, and dissolving the graft modified silicon dioxide by using a mixed solution of absolute ethyl alcohol and N, N-dimethylformamide (DMF) in a certain proportion, and putting into an electrostatic sprayed liquid storage chamber; in a static field with rated current of