The question was recently asked if rhenium needs a crucible liner for use in an electron beam evaporation system? And, if so, what would be the recommended liner?
Unfortunately, the answer isn’t quite so cut and dry.
Rhenium is a very poor electron beam evaporation material, requiring very high temperatures. It “spits” and “splatters”; resulting in very non-uniform resultant films with condensed rhenium “globules” formed on the surface. Rhenium will not react with the copper hearth in the electron beam source so it does not really require a liner. If it is desirable to utilize a liner, to lower the overall power requirements to the electron beam source, it is possible to insulate the evaporation material from the water cooled hearth by using an aluminum oxide crucible liner.
In any case, evaporation is generally less desirable than sputtering in most cases, depending on the equipment available.