Corrosion Resistance Of Super-hydrophobic Film Fabricated By One-step Method On Metal Substrate

Metal has been widely used because of their excellent physical and chemical properties, abundance in the crust and easy processing. However, most of metal is chemically active and easy to be corroded by oxygen in the air or other corrosive media. Surface treatment, which can effectively improve the metal corrosion resistance, is a widely application of anti-corrosion method. Inspired by the "lotus effect", super-hydrophobic surface is a new type of environmentally friendly surface treatment technology.In this paper, zinc, copper and aluminum, three kinds of commonly used metal, are employed as the substrate. Simple, efficient one-step methods for fabricating super-hydrophobic films on metal substrates are proposed respectively, corrosion resistance of the super-hydrophobic films are investigated as well.In50mL0.1M myristic acid ethanol solution that contains1mL0.4M CuCl2solution, super-hydrophobic films on zinc and copper substrates are successfully fabricated simultaneously by applying the zinc-copper galvanic deposition reaction in the above solution at35℃within24hours. The morphology and formation process as well as growth mechanism of the super-hydrophobic films are investigated through observing the SEM images of the films at different reaction time and the analysis of FT-IR and EDS. The open circuit potential (OCP), tafel curves, electrochemical impedance spectroscopy (EIS) are employed to investigate the corrosion resistance of the superhydrophobic films in3.5%NaCl solution. Experimental results show that the super-hydrophobic films have significantly improved the corrosion resistance of both zinc and copper. The corrosion current densities of zinc and copper decreased by three orders of magnitude respectively.In this part, a novel one-step anodic oxidation method for fabricating super-hydrophobic film on aluminum substrate is proposed. The film with a contact angle of157°was electrochemically grown at a constant potential of30V within1.5hours at room temperature in40mL0.1M myristic acid ethanol solution that containis2mL0.2M Al (NO3)3. SEM and FT-IR are applied to analyze the morphology and formation mechanism of the super-hydrophobic film. Corrosion resistance of the super-hydrophobic film and the film without "air tap" in3.5%NaCl solution are discussed by analyzing the electrochemical tests, the interface models for different films are proposed as well. The result shows that the super-hydrophobic film on aluminum substrate significantly improves the corrosion resistance of aluminum in the case of without "air tap" absence in NaCl solution. Aside from intensifying hydrophobicity, the air trapped in the film dramatically improves the anti-corrosion effect on the underlying aluminum. Without the help of air, the film itself can only present weak inhibition effect on aluminum corrosion. Finally, the stability and the reason for the failure of the obtained super-hydrophobic film in3.5%NaCl solution are studied.