Vapour-deposited coating using high deposition rates - providing a continuous coating of steel strip with aluminium

摘要

The process is for coating a substrate by evapn. of a material in which, during deposition, the min. technical distance is used between the substrate and the material but, when the process is interrupted, the distance is increased so a shielding screen can be inserted between the material and the substrate. The substrate is pref. fed at an angle above the evapn. crucible and the pref. appts. consists of an electron gun with magnetic guide and deflector units for the beam, used with a crucible mounted on rollers running on sloping rails so the crucible can be moved down the slope when it is necessary to insert the screen. Used for the vapour deposition, esp. of Al on moving steel strip, e.g. 400 mm wide. By using the min. distance between substrate and crucible, deposition rates are increased 50-75% and the variation in coating thickness reduced to 5-10% of the average coating thickness.