Electron-beam heating of ceramics to moderate temperature at fore-vacuum pressure

Abstract

We have studied the electron-beam heating of ceramic targets (AlN, ZrO2, and Al2O3) in the fore-vacuum pressure range (2–5 Pa) to temperatures below their phase transformation temperatures (melting, evaporation; < 1700 0C). It is shown that in this temperature range, conductive heat transfer through the lower face plays a dominant role in the thermal balance of the ceramic target; heat transfer by thermal conduction through the gas, and by thermal radiation play no significant role in heat removal from the target. Mass-to-charge analysis of the ion composition of the beam plasma, generated by the electron beam itself, shows that even at these moderate temperatures, intense sublimation of low melting point volatile components of the ceramic target occurs. Depositing on the substrate surface, these components may negatively affect the coating parameters and properties. Our investigations indicate the necessity of taking special measures to minimize the effect of ceramic target volatile components prior to their intense evaporation during the deposition of protective and functional coatings.