Effect of tantalum film on corrosion behaviour of AA6061 aluminium alloy in hydrochloric acid- and chloride-containing solutions

The present work is concerned with the corrosion resistance of AA6061 aluminium alloys with tantalum films in hydrochloric acid- and chloride-containing solutions. The tantalum films were produced by magnetron sputtering at different sputtering times (50 and 120 min). The films' morphologies were observed by metallographic microscope and scanning electron microscope with energy dispersion spectrum. It is shown in this paper that with longer sputtering time, the film's thickness increased, but it became less dense. The corrosion behaviour was characterised by potentiodynamic polarisation, scanning electrochemical microscopy analysis and an immersion experiment. These investigations revealed that the corrosion resistance of AA6061 aluminium alloy in chloride ions medium and hydrochloric acid was significantly improved after deposition of a tantalum film. Specifically, samples deposited for 50 min exhibited the best corrosion resistance in hydrochloric acid, while samples deposited for 120 min showed best corrosion resistance in sodium chloride solution.