Effect of RuO2 in Corrosion Behavior of Ti anode in FFC-Cambridge Process for Titanium Metal Winning

The corrosion behavior of inert titanium anode with ruthenium oxide coating and without coating was studied in molten calcium chloride salt at 950˚C. The Titanium was coated with Ruthenium oxide by the thermal decomposition method. Then, these anodes was placed in the electrolysis cell via the FFC method and cathode was polarized relating to the reference electrode in constant potential value of -1.6v and its corrosion behavior by microscopic studies was investigated. The morphological studies were performed by SEM, the distribution of elements was studied by EDS method. Studies have shown that the coating on the anode, the thickness of the oxide layer formed on the surface of the anode to uncoated anode greatly reduced and the Ti/RuO2 anode made showed two different functions due to exposure to calcium chloride molten salt and during the electrolysis. Part of the coating because of reacting with the released chlorine of molten salt decomposition, was separated from the substrate surface and dissolved in the melt by forming a chloride compound. Also a part of ruthenium during electrolysis and because of diffusion, has penetrated into the titanium of substrate and the intermetallic compound has been formed. So by the time, the ruthenium oxide coating improves the corrosion resistance of the anode by penetrating into the titanium.