Preparation and study of porous transition metal-doped coatings on electric vacuum ceramics for suppressing surface flashover

• The porous coating slows surface potential attenuation in 95 porcelain. • The deep trap energy level will be reduced from 0.88 eV to 0.96 eV. • The trap density will be reduced from 5.12 eV -1 m −3 to 2.36 eV -1 m −3 . • The surface resistivity decreased from 10 13 Ω to 10 11 Ω. Insulation failure caused by surface flashover is the main problem of high-voltage equipment. In this study, screen printing and solid-state sintering techniques were adopted to prepare Cr 2 O 3 -based composite coatings containing elements such as Cu, Mg, Mn, Ti, and Zn on the surface of alumina ceramics, in order to enhance their compressive resistance. SEM shows that Cr/Cu coating has the largest uniform porosity, AFM indicated that the roughness of the Cu 2 O coating was increased by 60 % compared with the control group. The SPD test shows the Cr/Cu coating has the slowest potential decay, with a deep trap level of 0.96 eV and density of 5.12 eV -1 m −3 , and a shallow trap level of 0.78 eV with a density of 2.36 eV -1 m −3 . By changing the surface and electrical properties of Al 2 O 3 ceramics to improve its flashover performance, it provides an effective strategy for vacuum insulation applications.