Preparation of layered double hydroxide films with corrosion resistance and self-healing properties on Al–Si–Cu alloys using steam coating and immersion processes

Low-carbonization and energy saving are required to mitigate global warming . In the automotive industry, weight reduction is required to improve fuel efficiency and driving performance. Al is commonly used to reduce the weight of automotive parts. However, the corrosion resistance of Al alloys is not so high, so they require surface treatment. In this study, MoO 4 2 − -intercalated Mg–Al layered double hydroxide (LDH) films with corrosion resistance and self-healing properties were prepared on a die-cast Al–Si–Cu alloy through steam coating and immersion. The prepared films were characterized via X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), and Fourier-transform infrared spectroscopy (FT-IR), among others. The XRD patterns showed that LDH films were successfully prepared on the Al–Si–Cu substrates. The FT-IR spectra revealed that MoO 4 2− ions were intercalated in the LDH film interlayer. The self-healing properties of the LDH films were also investigated. A self-healing film formed over the damaged area of a MoO 4 2− -intercalated LDH film in a 5.0 wt% NaCl aqueous solution for 72 h. XRD pattern and EDS analyses showed that the MoO 3 film formed as a self-healing film. The formation mechanism of this MoO 3 film was also discussed. The corrosion resistance of the LDH films prepared through different immersion times in a 5.0 wt% NaCl aqueous solution was also evaluated via polarization curve measurements. The corrosion resistance of the self-healing films were also evaluated by potentiodynamic polarization curve and electrochemical impedance spectroscopy (EIS) measurements. • MoO 4 2− -intercalated Mg–Al LDH film was prepared on ADC12 using steam coating. • The damaged area of the LDH film was recovered. • The corrosion resistance of the recovered film was good.