Method and apparatus for coating a graphite member

Claim 1

In a method of coating felts or mats of short graphite fibers for brushes in electric machines with thin layers of electrically highly conductive coating material from the vapor phase, the improvement comprising continuously pulling said felts or mats through etching and coating apparatus wherein said felts or mats are coated by steps comprising: (a) first subjecting the felts or mats to an etching treatment prior to the coating process by subjecting the felts or mats to a bombardment with ions of an inert gas; (b) then, without interruption, preparing a boundary layer of the coating material on the graphite member by ion plating, said ion plating comprising vapor deposition in the presence of a gas discharge plasma; (c) then stopping the development of the gas discharge plasma, required for ion plating, which continuing the vapor deposition of the same coating material on the felts or mats; and (d) subsequently applying a remaining layer of the same coating material by vapor deposition in a high vacuum alone.