Forming uniform oxide film on valve metal electrolytically - varying velocity of workpiece and maintaining constant voltage and current

摘要

An oxide film is formed on a value-metal foil by continuously drawing the foil through an electrolyte, applying a constant d.c. voltage between the electrolyte and the foil, sensing the forming current, and varying the drawing speed inversely with the forming current so as to maintain the forming current constant at a specific value. In the manufacture of electrolytic capacitors. Variations in foil etch ratio are compensated for so that the oxide thickness remains constant over the entire length of the foil. The d.c. voltage may be operated continuously at its max. output since the current and voltage are constant.