EFFICIENCY OF CADMIUM COMPLEX OF NITRILO--METHYLENE PHOSPHONIC ACID AS AN INHIBITOR OF LOW-CARBON STEEL CORROSION IN NEUTRAL IODIDE-CONTAINING AQUEOUS MEDIA AND PECULIARITIES OF FORMATION OF PASSIVATING FILMS UNDER THESE CONDITIONS

Influence of the cadmium complex of nitrilo-tris-methylene phosphonic acid Na[Cd(HO)N(CHPO)]7HO on the corrosion-electrochemical behavior of low-carbon steel in neutral iodide-containing aqueous media is studied by the potentiodynamic method. The composition and structure of passivating films, spatial localization of the processes of interaction between the inhibitor and iron ions, accompanying processes and products of these interactions are studied by X-ray photoelectron spectroscopy with layer-by-layer etching. In the presence of 1.4 mmol/dm of I ions, Na[Cd(HO)N(CHPO)]7HO reduces the current density of anodic dissolution of the metal at the concentration 0.05–0.5 g/dm and stimulates corrosion at the concentration 1.0 g/dm and higher, the optimal concentration of the inhibitor is 0.2–0.5 g/dm.