Effect of the Structure of Lead(II) Nitrilo-tris-Methylenephosphonic Acid Complexes on the Formation of a Protective Layer of Corrosion Inhibitor on a Surface of Carbon Steel

Abstract

The interaction between two complex compounds of lead(II) with nitrilo-tris-methylene phosphonic acid (NTP) that differ in structure and a surface of 20 steel is studied via X-ray spectroscopy. It is shown that the chemical interaction between one of these complex compounds and the steel surface does not result in the formation of a stable protective film. In contrast, interaction with the second complex leads to the formation of a strong protective layer with covalent bonding of atoms (Pb, Fe)–O–P and to a subsequent transition of iron from the oxidized state to the metal. The complexes of lead(II) with NTP display different thermochemical behaviors.