Oxygen evolution anodes have been increasingly used in industrial electroplating lines, replacing soluble metal anodes such as zinc and tin plate electrodes. The most typical example of the oxygen evolution anodes in such applications is an IrO2-Ta2O5 coated titanium electrode, which is prepared by thermal decomposition of a precursor solution containing metal salts on a titanium substrate. The IrO2-Ta2O5/Ti electrode has some favorable properties for oxygen evolution in acidic media as frequently used for electrogalvanizing and electrotinning; high catalytic activity, dimensional stability, negligible contamination into a plating bath, and a low consumption rate of the coating layer. However, the durability of the IrO2-Ta2O5/Ti electrode had been inadequate to a requirement for use in a high-speed electroplating line. This was attributable to the accelerated degradation of the electrode induced by electrolysis with high current densities more than 1 A cm" . We have investigated the degradation mechanism by analyses of structural and compositional changes of the coating layer, and from the results, the key technologies to prolong the lifetime have been deduced. In this paper, a recent progress of IrO2-Ta2O5/Ti electrodes, developed by us, in terms of durability is presented. The results on the electrode's lifetime in laboratory-scale cells and commercial electrogalvanizing lines are shown.
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