The control mechanism of micron and nano SiO2/epoxy composite coating on surface charge in epoxy resin

Charge accumulation on the surface of epoxy resin affects the insulation performance under DC voltage. In order to illustrate the effect of surface coating on the characteristics of surface charge accumulation in epoxy resin, micron and nano SiO>sub>2/epoxy composite coatings were deposited on the surface of epoxy resin by spraying, and the charge accumulation on the surface was studied by the electrostatic probe method. The surface trap parameters were analyzed by the method of isothermal surface potential decay combining with the carrier mobility and cross-section morphology of samples, the transport characteristics of surface charge and the respective control mechanism of coating layer were studied. The results suggest that the surface charge mainly accumulates near the electrodes, the main source of charges is injected from the electrodes. The surface charges near the anode are caused by charge trapping, and the surface charges near the cathode are caused by the adsorption due to the normal electric field. Surface charge accumulation can be suppressed by increasing the shallow trap density and carrier mobility on the surface of material, which is available by coating with micron and nano SiO
₂
/epoxy composites. It was found that, surface charge of epoxy resin could be suppressed effectively by coating of micron SiO
₂
particles with content of 1~3 wt%, or nano SiO
₂
particles with content of 3 wt%.