Improving wear resistance and corrosion resistance of AZ31 magnesium alloy by DLC/AlN/Al coating

A novel protective coating, consisting of three layers (top: diamond-like carbon, middle: aluminum nitride, bottom: aluminum), was deposited on the surface of AZ31 magnesium alloy layer by layer. Nano-indenter, electrochemical system and tribological tester were performed to investigate the hardness, wear resistance and corrosion resistance of the coated AZ31 magnesium alloy, respectively. The DLC/AlN/Al coating improved the magnesium alloyʹs surface hardness and reduced its friction coefficient, which consequently induced a great improvement of the magnesium alloyʹs wear resistance. Furthermore, the corrosion resistance of the AZ31 magnesium alloy with the DLC/AlN/Al coating was also enhanced with the corrosion current density decreasing from 2.25 × 10−5 A/cm2 to 1.28 × 10−6 A/cm2 in a 3.5 wt.% NaCl solution.