Characterization and corrosion resistance of a composite layered double hydroxides film on Mg–4Zn alloy in Hank's solution. (September 2021) - Chen, Jun
Abstract: The layered double hydroxides (LDHs) films are promising bioactive coatings for magnesium (Mg) alloys. Here, a film of composite LDHs has been prepared using a two-step in situ growth method on Mg–4Zn alloy. This film is found to provide excellent initial protection to the Mg–4Zn alloy in Hank's solution. During long-term immersion, layers of corrosion products mainly consisting of Mg/Ca–PO4 3- /HPO4 2− are deposited on top of both the bare alloy and the LDHs film, which can enhance the barrier effect and produce a self-healing effect. As a result, filiform corrosion occurs on the substrate but corrosion is not particularly severe even after 12 days of immersion. In the case of the coated sample, except for local pit corrosion at several active places, most areas remain integral even after immersion for 18 days. Graphical abstract: Image 1 Highlights: A film of composite LDHs was prepared using a two-step in situ growth method on Mg–4Zn alloy. This biologic coating is very compact and uniform, which can provide effective protection for long time. The corrosion mechanism was proposed based on the corrosion measurement and surface analysis. Corrosion products layers formed in SBF can enhance the barrier effect and produce a self-healing effect.