Influences of Coating Cycles and Composition on the Properties of Dimensionally Stable Anode for Cathodic Protection

Abstract

Properties of the anode for cathodic protection need low overvoltage for oxygen evolution and high corrosion resistance. It is well known that DSA (Dimensionally Stable Anode) has been the best anode ever since. DSA is mainly composed of RuO2, IrO2, ZrO2, Co2O3, and also Ta2O5, TiO2, MnO2 are added to DSA for better corrosion resistance. The lifetime of DSA for cathodic protection is also one of the very important factors. RuO2, IrO2, RhO2, ZrO2 are well used for life extension, and many researches are focused on life extension by lowering oxygen evolution potential and minimizing dissolution of oxide coatings. This work aims to evaluate the influence of constituents of MMO and coating cycles and ZrO2 coating on the electrochemical properties and lifetime of DSA electrodes. From the results of lifetime assessment in the anodes coated with single component, RuO2 coating was more effective and showed longer lifetime than IrO2 coating. Also, an increased coating cycle and an electrochemically coated ZrO2 could enhance the lifetime of a DSA.