Corrosion inhibition of galvanized steel by amino-tris(methylenphosphonic) acid complexes

• G.V. Redkina and A.S. Rozhkov

Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31-4, Leninsky prospect, 119071 Moscow, Russia

Abstract: The present work investigates the protective efficiency of galvanized steel against atmospheric corrosion by thin films formed on its surface from aqueous solutions of amino-tris(methylenephosphonic) acid complexes with divalent and trivalent metal cations (ATMPMe). The feasibility of corrosion protection of galvanized steel using aqueous ATMPMe solutions was demonstrated, particularly for complexes with rare-earth metal cations (Ce³⁺ and Y³⁺). Optimal conditions for the formation of protective films on zinc coatings from amino-tris(methylenephosphonate) solutions were determined (10 mM solution, 30 min treatment at 50℃ followed by drying at 60℃), which ensured maximum protective efficiency. The influence of the nature of the complex-forming cation in ATMPMe on the corrosion inhibition efficiency of galvanized steel was studied. It was established that, generally, the protective properties of phosphonate films improve with decreasing solubility of the complex-forming cation hydroxides and increasing complex stability. The highest anticorrosion efficiency was demonstrated by the films formed from ATMPCe and ATMPY solutions, which reduced the corrosion rate of galvanized steel in a chloride‑containing solution by 11.4 and 7.5 times, respectively. The high protective properties of these films were also confirmed by seawater spray tests and in a humid atmosphere with periodic moisture condensation. The results obtained in this study indicate the promise of using aqueous solutions of ATMP complexes with rare-earth metals, especially with Ce³⁺ and Y³⁺, in the development of environmentally safe alternatives to traditional chromate passivation for the protection of galvanized steel against atmospheric corrosion.

Keywords: galvanized steel, corrosion inhibitor, phosphonic acid, phosphonate

Int. J. Corros. Scale Inhib., 2026, 15, no. 2, 525-553
doi: 10.17675/2305-6894-2026-15-2-28

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