Hydrotalcite conversion coating on Mg alloy and its corrosion resistance

A magnesium–aluminum layered double hydroxide (Mg–Al LDH) film was fabricated on a Mg alloy substrate by a hydrothermal crystallization method, based on an interface reaction between hydrotalcite slurry and Mg alloy. Magnesium–aluminum layered double hydroxide with carbonate intercalation was obtained by synthesis involving separate nucleation and aging steps, where the Mg–Al LDH film was formed in the aging process. The LDH film was uniform and compact. The film was characterized by XRD, SEM, EDS techniques to study the structure, phase purity and morphology, respectively. Polarization measurements and electrochemical impedance spectroscopy (EIS) showed that the LDH film could effectively protect Mg alloy from corrosion. The cross cutting showed that the adhesion between the film and the substrate was very strong which enhances its potential for practical application.