Corrosion behavior of Ti-Al-N/Ti-Al duplex coating on AZ31 magnesium alloy in NaCl aqueous solution

摘要

In this study, Ti-Al-N/Ti-Al duplex coating was deposited on AZ31 magnesium alloy by magnetron sputtering with a Ti/Al composite target. Scanning electron microscopy and Auger electron spectroscopy were applied to investigate the morphology and elemental concentration of the obtained coating, respectively. The top layer was Ti-Al-N film with a Ti: Al:0:N ratio of 0.32:0.84:0.08:1, and the bottom layer was Ti-Al film with a Ti:0:Al ratio of 1.94:0.12:1. Each layer of this coating presented a developed columnar structure. The polarization test and immersion test were used to investigate corrosion behavior of the coated sample in 3.5 wt. percent NaCl aqueous solution. The results showed that this duplex coating could protect the substrate effectively in NaCl aqueous solution. Nevertheless, several through-thickness micropores in the coating finally induced the failure of the coated AZ31 in the immersion test.