LDH enhanced multifunctional durable superhydrophobic anti-corrosion coating with self-healing, anti-fouling and anti-icing properties

Abstract

Inspired by nature, a rough surface with micro-nano structure was constructed on Mg alloy by combining etching and in-situ growth layered double hydroxide (LDH). Then the mixture of low surface energy substances methyltrimethoxysilane (MTMS) and hexadecyltrimethoxysilane (HDTMS) was used for surface grafting. The composite coating thus prepared had superhydrophobicity, and the water contact angle (CA) was 157° and the sliding angle (SA) was< 10°. Under the impact of 0.44 m/s water droplets, the obtained composite coating maintained superhydrophobicity. The excellent water repellency endowed the composite coating with anti-fouling capability against contaminants such as mud and ink, as well as anti-icing properties. MTMS enhanced the ordering of HDTMS long-chain alkanes, forming a denser silane network that improved the corrosion resistance, chemical stability and mechanical stability of the coating. The coating reduced the corrosion current density of Mg alloy by 5 orders of magnitude, and it also showed self-repair performance. After soaking in 3.5 wt% NaCl solution for 14 days, the |Z|_0.01HZ was still in a high order of magnitude (above 10⁵). The CA was still as high as 150° (SA<10°) after being exposed to air or immersing in NaCl solution for 30 days, or 50 cycles of sandpaper abrasion or 90 cycles of tape peeling. This method provided a new idea for creating a superhydrophobic multifunctional coating on the surface of Mg alloy, which integrated long-term anti-corrosion, self-repairing properties, self-cleaning, anti-icing and chemical/mechanical durability, having broad application prospects in various industrial fields.