Improved surface flashover voltage of epoxy following polythiourea-assisted coating with high gas adsorption ability

Surface flashover as a well-known discharge phenomenon on the gas–solid interface can lead to the failure of power equipment. Although intensive studies have been devoted to improving the flashover voltage in gases, the perspective on exploiting gas characteristics has so far been ignored. We here directly utilize a polythiourea-assisted coating on epoxy to achieve beneficial gas adsorption and enhance the flashover voltage. The results show that the flashover voltage of the polythiourea-assisted epoxy is significantly improved in both N2 and SF6 compared with the blank epoxy. Combining the experimental and computational results, it is proved that the striking improvement in the flashover performance is attributed to the increased gas adsorption quantity resulting from the unique thiourea units in polythiourea. Although both esters in epoxy and thioureas in polythiourea act as active function sites for guest gases, polar thioureas not only lead to pronounced charge displacements but also own the larger density, which further enhances the adsorption energy and promotes the gas adsorption. The resulting increased gas adsorption quantity prevents the collision ionization effectively, thus improving the flashover voltage. Our research innovatively proposes a functional polythiourea-assisted coating that can enhance the flashover voltage by improving the gas adsorption ability.