Preparing corrosion-resistant layered double hydroxide coating on magnesium alloy under mild condition

Hydrothermally prepared layered double hydroxide (LDH) coating is unfavorable to large-size magnesium alloy parts. Herein, PO43−- and OH−-intercalated MgAl-LDH coatings with good corrosion resistance and strong adhesion were first prepared under relatively mild conditions. The optimal coating displays an exceptionally low corrosion current density (5.68 nA cm−2), a high charge transfer resistance (831.3 kΩ cm2), and negligible morphological variation without visual corrosion after 15 days of neutral salt spray exposure. The superior long-term protection is attributed to the intelligent release of PO43− and formed phosphate depositions with extremely low solubility product constant to effectively self-repair the micro-defects.