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

Abstract

Ceramic material has been widely used as insulator in vacuum. Their high hardness and brittle property brings some di‹culty 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 withˆne and complicated conˆguration. The paper studies its surface insulation performance and ‰ashover phenomena under pulsed excitation in vacuum. The ceramic samples with diŠerent crystallization parameters are tested under the vacuum level of 10-4 Pa. The machinable ceramic behaves better surface insulation performance than comparative the Al 2 O 3 and glass sample. The eŠect of crystallization level on the trap density and ‰ashover current is also presented. After ‰ashover shots many times, the surface microscopic patterns of diŠerent samples are observed to investigate the damage status, which can be explained by the thermal damage mechanism.

Influence of Surface Carburization of Machinable Ceramics on Its Pulsed Flashover Characteristics in Vacuum

“…One group serves as the control group, the other 4 groups are placed in glucose solution (with concentration of 10%, 20%, 30% and 40%, respectively) for 1h. After that, all the samples are heated to 250 o C and the glucose is decomposed and the color of MCs turns black [13] .…”

“…Recently, our group has invented a novel low-melting temperature machinable glass ceramic (shortened as machinable ceramic, MC), which is void-free complex material of micro crystal and glass phase. The MC material can be machined just like metal with continuous straps of cutting swarf [13] , and also shows good surface electric withstanding performance in vacuum [14] . It is considered that the MC is suitable for vacuum insulation with more nice profile, having the advantage of both traditional inorganic and organic materials such as ceramics and polymers.…”