Research progress on the preparation and corrosion resistance of layered double hydroxides film on aluminum alloys

Aluminum alloys have excellent properties such as low density and high strength-to-weight ratio. However, the negative standard electrode potential of aluminum leads to a more active chemical property and is prone to corrode; as a result, the poor corrosion resistance extremely limits the widespread application of aluminum. Therefore, it is necessary to take appropriate measures to improve the poor corrosion resistance of aluminum alloys. The chromate passivation technology is one of the most effective and mature aluminum alloy surface treatment technologies, and even if the formed passivation film is very thin, it can still greatly enhance the corrosion resistance of aluminum alloys and provide corrosion protection. However, Cr (VI) and its derivatives are highly toxic and carcinogenic, and they are harmful to the environment and the human body. As environmental awareness increases and the government strictly limits the use and emission of chromate, it is necessary to develop new treatments that are environmentally friendly and non-toxic to improve the corrosion resistance of aluminum alloys. The fabrication process of layered double hydroxides (LDHs) film is simple, and the morphology of the LDHs film can be controlled by adjusting the experimental parameters. The prepared LDHs film also has good corrosion resistance and anions exchange performance. Therefore, reports of in-situ growth LDHs film on the surface aluminum alloys have gradually increased in recent years. In this paper, we introduced a variety of methods for preparing LDHs film, such as ordinary hydrothermal, urea hydrolysis, and hexamethylenetetramine hydrolysis methods, and summarized the effects of different experimental conditions on the morphology and corrosion resistance of LDHs the films. Several commonly used modification methods and principles, such as the preparation of superhydrophobic films and self-healing films, were discussed in detail and the limitations of the current research were discussed. Finally, the focus of future research and development were described.