Properties of Zr2ON2 film deposited on Mg-Gd-Zn alloy with Mg-Al hydrotalcite film by arc ion plating

• Mg-Al hydrotalcite film was in-situ grown on Mg-Gd-Zn alloy.
• Zr2ON2 film was deposited to seal the micro-cracks of the hydrotalcite film.
• The hydrotalcite film improved the cohesion of Zr2ON2 film to the substrate.
• The composite film exhibited good protection efficiency and mechanical properties.

A Mg-Al hydrotalcite/Zr2ON2 composite film was deposited on Mg-Gd-Zn alloy by arc ion plating in order to improve the corrosion resistance and mechanical properties. The corrosion current density of the composite film sample immersed in a simulated body fluid is approximately 2.725 × 10−6 A cm−2, which is approximately two orders of magnitude less than that of the substrate. During 120 h immersion tests, results have shown that samples coated with the composite film have low hydrogen evolution rate. Moreover, scratch tests and nano-indentation measurements show that the composite film samples have superior mechanical properties. Such results demonstrate that coating Mg-Al hydrotalcite/Zr2ON2 composite film on Mg-Gd-Zn alloy can provide not only good protection efficiency but also stable protection.