Abstract: In the electroplating of zinc diecastings with a copper layer, the electrolyte penetrates into the pores of the zinc diecasting. When the temperature is increased later, this leads to vaporization of the electrolyte liquid in the pores and to blistering or flaking of the copper layer. It is proposed that plating be carried out in two steps. In the first step, only a thin copper layer of less than 1 ?m is applied and the plated parts are then treated at a temperature which leads to vaporization of the electrolyte liquid. The thin copper layer is still sufficiently porous for the vapour to be able to escape. Only the solid constituents of the electrolyte remain. The copper layer is then thickened to a final thickness of from about 20 to 30 ?m. In this plating step, electrolyte liquid no longer penetrates into the pores of the zinc diecasting. The parts which are coated in this way display no blistering or flaking of the copper layer after storage at a temperature of 150° C.

Abstract: Cleaning device for a web-like or rib-like contact element (contact blade) of a car-body skid for a plant for cathodic dip electropriming, which comprises at least one cleaning element resiliently engageable on the contact blade and moving relative thereto, wherein for simple, careful and effective removal of impurities from the contact blade the cleaning element is knife-like or spatula-like in design and is displaceable along the contact blade over its entire length in the longitudinal direction of the contact blade.

Abstract: A workpiece surface is provided with a layer which is applied by a sputter-CVD process. An optimum hardness and sliding quality of the layer is obtained at a positive bias of the workpiece surface relative to the plasma. For tungsten carbide/carbon layer, an optimum layer quality is attainable at a bias of thirty-five volts. Besides tungsten carbide/carbon layers, also silicide/silicon layers can be produced if volatile silicon compounds are used as the reactive gas.