Modification of Surface Nanothin Layers and Electrochemical Behavior of Carbon Steel in Aqueous Media Containing Nickel Complex of Nitrilotrismethylenephosphonic Acid

The effect of the chelate complex compound Na[NiN(CHPO)]·11HO on the composition, surface concentration profile and corrosion-electrochemical behavior of the 20 steel in a borate buffer solution at pH = 7.4 and natural aeration was studied using the potentiodynamic method, X-ray photoelectron spectroscopy and scanning electron microscopy of the surface with microanalysis. The studied compound is a corrosion inhibitor; the best protective effect achieved at a concentration of 0.5 mmol/dm. The mechanism of the inhibitory action of this inhibitor is discussed. Slowing down the anodic dissolution of iron is due to the formation of a nickel-doped layer of Fe-NiO oxides with a thickness of 10–20 nm on the steel surface. The mechanism of action of the studied corrosion inhibitor differs sharply from the mechanism of action of the previously studied inhibitors Na[CuN(CHPO)]·13HO and Na[ZnN(CHPO)]·13HO.