Inhibition of the corrosion of metals by additions of bicyclic triazolopyrimidine in neutral chloride solutions. Part 2

• M.O. Agafonkina¹, Yu.I. Kuznetsov¹, Kh.S. Shikhaliev² and N.P. Andreeva¹

¹ Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31-4, Leninsky prospect, 119071 Moscow, Russia
² Voronezh State University, Universitetskaya pl. 1, Voronezh, 394018, Russia

Abstract: The adsorption, passivation and anticorrosion properties of a bicyclic triazolopyrimidine – 2-methyl-5-phenyl-4,5,6,7-tetrahydro-[1,2,4]triazolo[1,5-α]pyrimidin-7-ol (MPTTP) – on copper and copper alloy MNZh5-1 in a neutral borate buffer with pH 7.4 were studied. Adsorption measurements were carried out on the reduced and oxidized surfaces of the metals. It was found that in the latter case, the adsorption of MPTTP occurs at lower concentrations than in the first. The obtained adsorption isotherms were calculated using the full Temkin isotherm equation. The values of the free energies of adsorption of MPTTP indicate the chemisorption interaction of its anion with the surface of copper or its alloy. The passivation capacity of MPTTP at 10 μmol/L manifests itself in the passivation of only the first peak of active dissolution of copper and MNZh5-1. Corrosion tests of copper and the alloy in an aqueous solution of 0.001 mol/L NaCl showed that the alloy is fully protected at 0.40 mmol/L, while copper is fully protected at 0.60 mmol/L. In a 0.010 mol/L aqueous solution of sodium chloride, both metals are fully protected from corrosion at 0.90 mmol/L of MPTTP.

Keywords: inhibition, copper, copper alloy, substituted pyrimidines, protective effect, free energy of adsorption, ellipsometry

Int. J. Corros. Scale Inhib., 2026, 15, no. 1, 263-277
doi: 10.17675/2305-6894-2026-15-1-13

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