Performance and corrosion resistance mechanism of SA-Al composite hydrophobic coating on electrolytic manganese surface

Abstract

At present, the problem of chromium salt pollution is receiving increasing attention, and the discharge of chromium salt pollutants is strictly restricted. Therefore, the development of new chromium-free passivators is very important for the electrolytic manganese industry. In this paper, a simple dipping method was used to prepare a single stearic acid (SA) hydrophobic coating and Al3+ doped stearic acid (SA-Al) composite hydrophobic coating on electrolytic manganese surface. It is found that the composite coating can significantly compensate for the defects of a single SA coating and effectively inhibit the surface corrosion of electrolytic manganese. The coating was tested by electrochemistry and various characterization methods, and the results showed that the SA-Al composite coating has better corrosion resistance. Compared to manganese substrate, the corrosion inhibition efficiency of SA hydrophobic coating is 99.73%, while that of SA-Al composite hydrophobic coating can be as high as 99.90%. It is obvious that the corrosion resistance of SA-Al coating is higher than that of SA coating. Moreover, the surface morphology of SA-Al coating is smoother and more complete, and the complete coating morphology can play a better barrier to corrosive media. This also further shows that the composite coating has more excellent performance, and it will be of great significance to study the combination of organic and inorganic composite coatings.