Influence of SiC/epoxy Composite Coating on the Surface Charge Dissipation Characteristics of Insulators

The surface coating of SiC/epoxy nonlinear conductive materials is an effective method to suppress the charge accumulation at the gas-solid interface within DC GIS. In order to comprehensively evaluate the performance of SiC/epoxy composite coatings in accelerating charge dissipation, two electrode structures are employed, namely finger-shaped electrode(Case 1) and needle electrode(Case 2), to accumulate different initial charge distributions on the insulator sur-face. Subsequently, the dynamic distributions of surface charges over time are tested, and the influence of initial charge distribution patterns on the charge dissipation pathway is analyzed. Based on this, the mechanism of accelerating charge dissipation in SiC/epoxy composite coatings is elucidated. The results indicate that in Case 1, the surface charge dissipation process consists of two stages: "fast-slow, " with surface conduction being the dominant pathway for charge dissipation. In Case 2, the surface charge dissipation process undergoes three stages: "slow-fast-slow, " with gas-side charged particle neutralization being the dominant mode of surface charge dissipation. The difference in the self-built electric field distribution between the two cases results in variations in the dominant pathways of charge dissipation. Moreover, the SiC/epoxy composite coating primarily alters surface traps and surface conductivity to accelerate charge dissipation. This study contributes to understanding the influence of SiC/epoxy composite coatings on the charge dissipation characteristics on insulator surfaces, providing insights for the performance evaluation of nonlinear conductive coatings.