Electrochemical behaviour of sputter-coated titanium films on AZ31 magnesium alloy

Abstract

Lightweight magnesium-based structural alloy AZ31 is normally prone to high corrosion in an aqueous environment. A detailed study is reported in this work on AZ31 Mg alloy coated with Ti thin films of different thicknesses by DC sputtering to investigate the capability of Ti coating to prevent corrosion of AZ31 under an aqueous environment similar to seawater. Ti films have been fabricated to 50, 100 and 150 nm thicknesses. Utilising grazing incidence-XRD and SEM, the films’ structure and microstructure were studied. The films were amorphous. Due to corrosion, interesting micro-structures evolved. Corrosion inhibition characteristics of the Ti films were characterised by electrochemical techniques such as potentiodynamic polarisation and impedance spectroscopy. Ti films with 100 nm and 150 nm thickness show a good inhibition capability. The corrosion mechanism was investigated using XPS and X-ray energy dispersive spectra.