PECULIARITIES OF INNER ELECTROLYSIS DURING ELECTROPLATING OF METALS PRONE TO PASSIVATION

The deposition of metal platings using the inner electrolysis method t akes place at the expense of the dissolution of anode made of a metal, which is more electronegative than the metal substrate. The passivati on of metal substrate in the plating electrolyte violates popular opin ion; for example, in this work, we propose the use of copper as the an ode for the silver plating of steel. The investigation of steel behavi or in a nitrate silvering electrolyte showed that steel is passive bot h without current and during the electrolytical silver deposition. In the Fe\AgNO3, HNO3, methionine\Cu(NO3)2, HNO3\Cu system, copper appear s to be about 0.3 V more electronegative than iron, in contrast to met al standard potential series. The anode and cathode shorting through t he outer circuit results in the copper dissolution in the anode chambe r and the silver deposition on steel in the cathode chamber. Corrosion of passive steel proceeds with a rate of about 10(-5) A/cm2 and does not inhibit its adhesion with the silver deposit.