Investigation on Surface Insulation Strength of Machinable Ceramic Material under Pulsed Voltage in Vacuum

Ceramic material has been widely used as insulator in vacuum. Their high hardness and brittle property brings some difficulty in the application. A new kind of machinable ceramic was invented recently. The ceramic can be machined easily and accurately after being sintered, which provides the possibility of making the insulator with fine and complicated configuration. However, the insulating strength across the surface of the machinable ceramic is not known clearly. The paper studies the surface insulation performance and flashover phenomena under pulsed excitation in vacuum. The ceramic samples with different crystallization parameters are tested under the vacuum level of 10^-4Pa. For the comparison, the Al₂O₃ ceramic and glass slice is also tested with the same method. The microcosmic patterns of their surface are observed. The surface insulation performance is evaluated primarily. The flashover characteristic and mechanism across the machinable ceramic is discussed