Coating substrates, esp. gas turbine blades, in vacuum chamber - by electron beam evapn. of molten alloy contg. metals with different vapour pressures

摘要

The evapn. crucible is charged continuously, and has a large surface area exposed to focused electron beams which are periodically deflected in accordance with a pattern. At least one electron beam is periodically subjected to a skip frequency of max. 10, esp. max. 5 Hz to deflect the beam onto different surface zones (a) of the molten alloy, and then driven along a line raster in each zone (a) at min. 100, esp. min. 300 Hz. Zones (a) are pref. rectangular. Zones (a) have a total of 10-80%, esp. 70-30% of the bath surface; and the process is used esp. for coating turbine blades with an alloy (b) resisting oxidn. and corrosion. Alloy (b) is esp. CoCrAlY, or NiCoCrAlY. Homogeneous coatings (b) can be obtd. on a large number of substrates located in a vacuum chamber above the evaporator.