Corrosion Inhibition of Stainless Steel in HCl Solution Using Newly Aniline and o-Anthranilic Acid Copolymer

This paper introduces copolymers of aniline and o-anthranilic acid with different ratio of aniline/o-anthranilic acid (r = 1, 2 and 3) as novel corrosion inhibitors for stainless steel in high-corrosive media. The synthesized polymers were characterized by Fourier-transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-Vis) and X-ray diffraction (XRD) techniques. After optimization of the aniline/o-anthranilic acid ratio, the inhibition efficiency of the best copolymer was measured for stainless steel in 2 M HCl solution. Electrochemical methods including potentiodynamic polarization and electrochemical impedance spectroscopy were used in different concentrations of copolymer. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to study the surfaces of the steel after exposed to test solution. It was found that the aniline and o-anthranilic acid copolymer with r = 3 can prevent the penetration of corrosive species into metal surface as protective film on the metal surface by physical and chemical adsorption.