| CPC C25D 21/12 (2013.01) [C25D 5/06 (2013.01); C25D 17/005 (2013.01); C25D 17/28 (2013.01); C25D 5/18 (2013.01)] | 4 Claims |
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1. A film formation method for a metallic coating,
wherein the metallic coating is derived from metal ions and is formed on a surface of a substrate by disposing a solid electrolyte membrane between an anode and the substrate that serves as a cathode, pressing the substrate by the solid electrolyte membrane with a fluid pressure of an electrolyte that is disposed between the anode and the solid electrolyte membrane and contains the metal ions, and applying a voltage between the anode and the substrate in a state of pressing the substrate, the method comprises:
measuring an alternating current impedance between the anode and the substrate in a state where the solid electrolyte membrane is in contact with the substrate;
determining whether an imaginary component at a predetermined frequency of the alternating current impedance is equal to or more than a preliminarily set film-formable value or not, the imaginary component at the predetermined frequency indicating a contact state between the solid electrolyte membrane and the substrate, and a film formation becoming performable at the film-formable value;
when the imaginary component is equal to or more than the film-formable value in the determining, forming the metallic coating in a state where the substrate is pressed by the solid electrolyte membrane; and
when the imaginary component is smaller than the film-formable value in the determining, forming the metallic coating in a state where the pressing of the substrate by the solid electrolyte membrane is released to separate the solid electrolyte membrane from the substrate, the solid electrolyte membrane is re-tensioned with a constant tensile force, and subsequently, the substrate is pressed by the re-tensioned solid electrolyte membrane.
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