LAUSR

Abstract A novel hydrophobic passivation coating was fabricated on the surface of electrolytic manganese by stearic acid (SA) and oleic acid diethanolamide (ODEA). ODEA, which forms micelles in aqueous solution, can promote largely dissolution of insoluble stearic acid to form stable passivation solution. A series of influence parameters were investigated and the optimized process conditions were as follows: the concentration of SA and ODEA were 3 g/L and 10 g/L, respectively; and the immersion time was 5 min. Under the optimized condition, the anti-corrosion properties of the coating were characterized by electrochemical impedance spectroscopy and polarization test. The results showed that the corrosion potential and corrosion current density decreased obviously, and the polarization resistance at 0.01 Hz increased from 20.89 to 467.74 Ohm cm2. FT-IR spectroscopy and Gaussian calculations showed that SA and ODEA simultaneously acted on the surface of manganese to form a hydrophobic coating, which increased the contact angle from 41° to 113°.