Patent ID: 6946034

Claim:
An electron beam physical vapor deposition coating apparatus comprising: a coating chamber at an elevated temperature and a first subatmospheric pressure; a hood defining a coating region within the coating chamber; means for introducing gases into the coating region within the hood; an electron beam gun for projecting an electron beam into the coating region; a first aperture in a wall of the coating chamber through which the electron beam passes before entering the coating chamber; a second aperture in a wall of the hood through which the electron beam passes to enter the coating region from the coating chamber, the second aperture being sized so that the introducing means maintains the coating region at a second subatmospheric pressure greater than the first subatmospheric pressure within the coating chamber; and a second chamber within the coating chamber and enclosing the first aperture so as to separate the first aperture from the coating chamber and the coating region, such that the electron beam must pass through the first aperture and the second chamber before passing through the coating chamber, passing through the second aperture, and entering the coating region.