Patent ID: 8551317

Claim:
A method for providing an oxide coating on a cathode metal plate, comprising applying a direct current voltage in an electrolyte containing zirconium or aluminum between an insoluble anode and the cathode metal plate positioned opposite the anode, wherein the anode and the cathode are facing parallel each other with space therebetween, wherein the insoluble anode is a titanium plate coated with iridium oxide, wherein the cathode is a low carbon steel sheet, a nickel coated low carbon steel sheet, or a tin-coated low carbon steel sheet, and supplying gas into the electrolyte to coat the cathode with zirconium oxide or aluminum oxide, wherein the gas is oxygen, or a gas containing oxygen, wherein the gas is supplied through bubble generating means situated below or beside the space between the anode and cathode, wherein the gas is so supplied as to contact the cathode surface.