Surface flashover performance of machinable glass ceramics material in vacuum

Glass ceramics with the composition of 55% (mass fraction, the same below) SiO₂-6% B₂O₃-8.5% (K₂O-Li₂O)-11.5% Al₂O₃-4.5% ZnO-9.5% MgO-5% F prepared from the parent glass were melted at 1350°C for 2 h, annealed at 500°C and crystallized at 650-750°C for 2 hours. To study how the crystallization process affects the surface flashover performance of glass ceramics under high voltage in vacuum, the samples were examined by X-ray powder diffraction to analyze the component phase. The micro-structures of the samples were observed by scanning electron microscopy. The glass ceramics were also compared with alumina ceramics. The results show that the material has better surface flashover performance than alumina ceramics. Increasing the temperature at the same heating time, the flashover voltage of the material falls. Glass ceramics have better flashover performance along the surface after crystallization at 650°C for 2 h.