Corrosion Resistance of Mg(OH)₂/Mn(OH)₂ Hydroxide Film on ZK60 Mg Alloy

This study aims to prepare hydroxide films on the surface of ZK60 magnesium alloy to improve the corrosion resistance of the latter. The hydroxide films were fabricated with a facile hydrothermal method using Mg(NO3)2 and Mn(NO3)2 aqueous solutions. The treatment temperature was maintained at 353 K, while the treatment time was 6 h, 12 h, and 24 h. X-ray diffraction (XRD) and Fourier transform-infrared (FT-IR) spectroscopy demonstrated that the films were composed of a mixture of Mg(OH)2 and Mn(OH)2. As revealed by scanning electron microscopy (SEM), each film grew from an incomplete lamellar structure to a thick lamellar structure at changing treatment times. The corrosion current density of the 12 h film sample immersed in a simulated body fluid (SBF) reached 3.07 × 10−7 A·cm−2, which was approximately two orders of magnitude lower than that of the ZK60 magnesium alloy substrate (3.04 × 10−5 A·cm−2). In addition, the hydrogen evolution experiment showed that, even after 168 h of immersion, the 12 h film sample could still provide protection for the substrate