A process for preparing a coated surface of a tribological system

Disclosed is a method for producing a wear-resistant surface of a workpiece of aluminum or an aluminum alloy by electrolysis by the wear-resistant surface by plasma electrolytic oxidation (PEO) or plasma electrolytic deposition (PED) is produced in a bore of the workpiece, comprising at least the steps : Providing the workpiece which has at least one bore, medium-tight sealing of both the top and the bottom of the hole with an upper closure element and a lower closure element, and simultaneous introduction of a central hollow cathode in which at least one hole, Introducing the electrolyte through the central hollow cathode in the bore, causing a continuous electrolyte flow in an annular space between a wall of the bore and an outer diameter of the central hollow cathode, and Discharging the electrolyte and produced during the electrolysis gas, wherein the electrolyte from above through the central hollow cathode is passed introduced toward the lower closure element in the bore is deflected at the lower closure element in its flow direction and along the wall in the annular space in toward the upper closure element flows, and is discharged together with the gas produced above, and wherein the gas formed during the electrolysis is collected in a collecting chamber which is disposed on the upper closure element and above the bore, the gas from the plenum is discharged continuously. In addition, a coating apparatus is shown which is suitable for implementing the method.