On the use of platinized and activated titanium anodes in some electrodeposition processes

Substitution of classical lead anodes containing 6–8% of antimony, 4–6% of tin or 0.75–1.00% of silver in the zinc electrowinning and hard chromium plating bath with platinized and activated titanium anodes is discussed in this paper. Depending on the type of electrochemical processes, the main effects of this substitution are as follows: smaller electrical energy consumption, better current efficiency, increased cell capacity, smaller electrode gap, higher purity of the deposit and savings in manpower and chemicals. Ti/Pt, Ti/Pt-IrO₂, Ti/RuO₂, Ti/Pt-IrO₂-MnO₂, Ti/Pt-IrO₂-PbO₂, Ti/Pt-IrO₂-RuO₂, Ti/MnO₂, Ti/RuO₂-MnO₂ and Ti/PbO₂ coated titanium anodes have been tested in synthetic as well as in industrial electrolytes. At working current densities some activated titanium anodes showed lower overpotential than the lead anode. These electrodes have continued to perform in this way during a one-year test in synthetic and industrial electrolytes so far. No signs of corrosion of the electrodes have been noticed during the test. Received: 31 January 1997 / Accepted: 28 May 1997