ZPCC-Zn-Al-LDH surface bilayer; toward designing a durable self-healable nano-structured film with the utmost corrosion resistance

Abstract

BackgroundDesigning thin films with utmost corrosion resistance stability and long-term metal protection from corrosive species attacks is the main idea of this work. Zinc phosphate conversion films are greatly exploited for improving the anticorrosion properties and surface preparation prior to organic coating application. Layered double hydroxide (LDH) thin films consist of a dense layer and a plate-shaped part, which perform the functions of the barrier and ion exchange, respectively. MethodsA bilayer conversion coating composed of a modified zinc phosphate layer and LDH crystals was fabricated on mild steel and then loaded with a glutamate corrosion inhibitor. These coatings were characterized by FE-SEM, XRD, FT-IR, and XPS methods. Significant findingsEIS results showed that log |Z|0.01 Hz reached its maximum value (6.14 Ω cm2) for the conversion coating sample loaded with inhibitor. Also, the active properties of the polyester organic coating with the introduced primer were ameliorated insofar as the total resistance of the scratched coating was obtained at around 115 KΩ cm2 after 48 h of exposure to the salty solution.