PROCESS FOR PRODUCING A CORROSION AND WEAR-RESISTANT OXIDE LAYER WITH LOCALLY REDUCED LAYER THICKNESS ON THE METAL SURFACE OF A WORKPIECE

摘要

PCT No. PCT/EP95/04544 Sec. 371 Date Aug. 21, 1997 Sec. 102(e) Date Aug. 21, 1997 PCT Filed Nov. 18, 1995 PCT Pub. No. WO96/17111 PCT Pub. Date Jun. 6, 1996The invention relates to a method to produce an oxide coating that protects against corrosion and wear on the metal surface of a workpiece, more specifically, for the metal surface of a body for accepting a valve, wherein with the use of a cathode, the workpiece, as an anode, is subjected to constant or pulsating direct current in an electrolyte, with an auxiliary anode, which is resistant to the electrolyte, being attached to the workpiece before the workpiece is dipped into the electrolyte, which discharges the anodizing current at locations where no anodized coating is required or only a limited anodized coating is required.