Development of superhydrophobic protective coatings through surface functionalization of porous MgO with transition metal salts of palmitic acid

Abstract

In this study, an innovative post-treatment approach for improving the corrosion resistance and hydrophobicity of AZ31 magnesium alloy is introduced. The process involves treating a porous MgO layer, generated through plasma-electrolytic oxidation, with ethanolic solutions of palmitic acid (PA) combined with either iron nitrate or cobalt nitrate. This treatment leads to the formation of PA-Fe and PA-Co, respectively, which effectively seal structural defects, thereby enhancing the corrosion resistance and hydrophobicity of the coating. Remarkably, the PA-Fe salt formation led to a substantial reduction in corrosion rates, with the corrosion current density of PA-Fe reaching 2.43 x 10-10 A/cm2, while PA-Co attained 3.63 x 10-9 A/cm2. Additionally, the coatings exhibited superhydrophobic properties, achieving a ∼ 173° contact angle for PA-Fe and a ∼ 168° contact angle for PA-Co. These findings highlight the long-term potential of this multifunctional post-treatment approach, which effectively seals defects and enhances hydrophobic properties. The innovative technique presented here has diverse applications in challenging environments and shows promise in addressing the corrosion challenges associated with magnesium alloys.