Influence of Cr/sub 2/O/sub 3/ and MnO additives on the surface properties of alumina insulators

Alumina insulators containing 95wt% Al/sub 2/O/sub 3/ were doped with Cr/sub 2/O/sub 3/ and MnO(MnCO/sub 3/). The properties of the doped samples were measured and compared with those of the original alumina insulators. Better surface performances of the samples doped with proper Cr/sub 2/O/sub 3/ and MnO were obtained while the bulk properties have hardly been changed. After doping the sample showed a lower SEE (secondary electron emission) coefficient, a lower surface resistivity and a higher surface flashover voltage in vacuum. Meanwhile, some points regarding the effects of manganese and chromium doping on the properties of alumina insulators were also briefly discussed.