Solution-processed nanocoating of Ca${}_2$Nb${}_3$O${}_{10}$ and polydopamine for anticorrosion on magnesium alloy

2D materials have exhibited great potential for applications in anticorrosion nanocoatings. However, the nanocoating of prefocused graphene shows "corrosion-promoting activity" due to its high conductivity. Metal oxide nanosheets obtained by delaminating layered oxides have been another attractive candidate. This study demonstrates a water-based Ca${}_2$Nb${}_3$O${}_{10}$ (CNO) ink spray coated on magnesium alloys to form a continuous coating without complex functionalization and structural control. The composite coating of Ca${}_2$Nb${}_3$O${}_{10}$ (CNO) and polydopamine (PDA) is fabricated by combining spray- and dip-coating methods. The surface composition and microstructure of the as-prepared coatings are characterized by X-ray diffractometry, Fourier transform infrared, X-ray photoelectron spectroscopy, scanning electron microscopy, and energy-dispersive spectrometry. The anticorrosion performance of the composite coating is evaluated by potentiodynamic polarization, electrochemical impedance spectroscopy, and salt spray tests. The electrochemical results show that the CNO/PDA heterostructure coating provides an enhanced corrosion inhibition efficiency (99.62%) with a corrosion current density of 5.49 × 10${}^{-7}$ A cm${}^{-2}$, three orders of magnitude lower than bare AZ31. The immersion tests before and after heat treatment and salt spray tests indicate that the composite coating has good stability and long-term anticorrosion performance. Solution-processed nanocoating and extensible materials design provide a green and facile route to anticorrosion nanotechnology for industrial demands. (© 2024 Wiley‐VCH GmbH)