Deposition of (Ti, Ru)O₂ and (Ti, Ru, Ir)O₂ oxide coatings prepared by sol–gel method on titanium

Titanium anodes activated by noble metal oxides possess a wide range of advantages and applications. Actually, coating of titanium anodes by highly conductive oxides of noble metals (Ru, Ir) dramatically increases the lifetime of these anodes. In this study, the binary coating consisting of Ti and Ru and the ternary coating consisting of Ti, Ru and Ir were prepared through sol–gel method. After coating of the titanium substrate, the corrosion behavior of coatings was studied by anodic polarization and cyclic voltammetry tests. The lifetime of anodes was determined using accelerated corrosion test. The morphology of coatings was examined by field emission scanning electron microscopy and atomic force microscopy. Phase analysis was done using X-ray diffraction. Results indicated that the microstructure of both coatings is similar to cracked mud consisting of islands separated by cracks, while the distribution of cracks in the ternary coating is more uniform in terms of morphology. The ternary coating is also more active in low overpotentials, while ability of load transfer in the ternary coating is reduced in high overpotentials.