Influences of HF acid eroding treatment on surface insulation performances of machinable ceramics

Machinable ceramic, as a new kind of material that is composed of crystal phase and glass phase, has an excellent performance on machining and dielectric property. We prepared different machinable ceramic sample. The different glass-phase contents on surface of samples treated by hydrofluoric (HF) solutions of diverse concentrations affect their flashover characteristics in vacuum. The proportions of crystal to glass phase are measured by X-ray diffract meter (XRD), and their flashover characteristics are also investigated. It is found that the influences on flashover characteristics are closely associated with the concentrations of HF solutions; the higher concentration the HF solution is, the lower glass-phase content and better flashover characteristic samples will perform. The treatment on machinable ceramics by HF can partly erode the glass-phases of sample surface, which changes the flashover heights of free electrons and hence influences the surface insulation performances of machinable ceramics in vacuum.