Study on surface electrical performance of machinable ceramics for high voltage electro-vacuum insulation

There are some special requests for the insulating materials for high voltage electro-vacuum devices. Traditionally alumina ceramics and polymers are widely used, but both of them show some disadvantages such as difficulty of being manufactured to some complex shape due to the restriction of die arrangement, or lower mechanical and heat-resistant properties. The paper reports a newly invented low-melting temperature machinable glass ceramic (MC) for remedy these problems. The influence of crystallization preparation parameters (temperature and time) on its basic mechanical and electrical properties is investigated, such as bending strength, dielectric parameters, and desorbed gases, revealing its advantages suitable for vacuum utilization. Moreover, different metal oxides (Cu₂O and Cr₂O₃) with low secondary electron emission (SEE) yield are doped into MC, and a better surface electrical withstanding capability is achieved.