The cathodic modification behaviour of ruthenium additions to titanium in hydrochloric acid

Abstract The corrosion resistance of titanium in reducing environments can be improved by microalloying with platinum-group metals (PGMs). Palladium-containing titanium alloys are well known for their excellent corrosion resistance, but the significant increase in the price of palladium makes these alloys economically unfavourable. Little information is available on the basic mechanism by which ruthenium, the lowest cost PGM, improves the corrosion resistance of titanium. Although electrochemical studies indicated that palladium is a much more effective cathodic material than ruthenium, titanium–ruthenium alloys form a secondary phase that exhibits catalytic properties superior to those of pure ruthenium. As a result, ruthenium-containing titanium alloys compare well with palladium-containing titanium alloys.