Superhydrophobic Dual-Layer Coating for Enhanced Corrosion Protection of Mg Alloy

Metal materials can be seen everywhere in our lives, and almost all of our food, clothing, housing and transportation cannot be separated from the use of metal. Metal materials often corrode due to environmental, biological, mechanical and other factors. Therefore, people protect the performance of metal devices and extend the service life of metal equipment by coating their surfaces.

The anti-corrosion coating needs to be able to effectively prevent the penetration of oxygen, water, ions, etc., prevent the progress of electrochemical reactions, and have acid and alkali resistance, friction resistance and excellent physical and mechanical properties.

Parylene coating has the functions of waterproof, moisture-proof, mildew-proof, anti-corrosion, anti-salt spray and high temperature resistance, and has a wide range of applications in aerospace, microelectronics, semiconductors, sensors, magnetic materials, medical equipment, cultural relics protection and other fields. At the same time, superhydrophobic coatings with micro-nano structures also have important applications in the fields of anti-fouling, self-cleaning and anti-corrosion. The use of MOFs to construct micro-and nanostructured superhydrophobic coatings to further improve the corrosion resistance of superhydrophobic coatings has become a research hotspot in recent years.

The research group of Professor Li Jian from Northwest Normal University prepared a superhydrophobic ZIF-8/PVDF/LDH (SZPL) double-layer coating on magnesium alloy by electrodeposition and dip coating, which consisted of the underlying layered double hydroxide (LDH) transition structure and top superhydrophobic zeolitic imidazolate framework-8 (ZIF-8) layer. the as-prepared SZPL double-layered coating showed robust superhydrophobic and self-cleaning properties, which could block the electrolyte invasion. Furthermore, the electrochemical tests demonstrated that the SZPL coating highly enhanced the corrosion protection ability of Mg alloys. It still has good anti-corrosion performance even after immersion for seven days. Moreover, the surface still exhibits excellent abrasion resistance after repeated sandpaper friction cycles. At the same time, the super-hydrophobic and ultra-low surface energy characteristics of the double-layer coating endow the coating with excellent self-cleaning performance and can effectively resist pollutants.

Such coatings offer a new strategy for fabricating excellent anticorrosive coatings with robust superhydrophobicity and self-cleaning performance on metal substrates.

references:

Xingxing Yin, Peng Mu, Qingtao Wang, Jian Li*.Superhydrophobic ZIF-8 based dual-layer coating for enhanced corrosion protection of Mg alloy,ACS Appl. Mater. Interfaces, 2020, DOI: 10.1021/acsami.0c09497