Corrosion inhibition of copper and its alloy MNZh5-1 by salts of succinic and alkenylsuccinic acids in chloride solution

• M.O. Agafonkina, I.A. Kuznetsov, Yu.I. Kuznetsov and N.P. Andreeva

A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninskii pr. 31, 119071 Moscow, Russian Federation

Abstract: The adsorption, protective and passivating effect of sodium salts of succinic, itaconic and a blend of alkenylsuccinic acids (SKAP-25) on the oxidized surface of copper and copper–nickel alloy MNZh5-1 in neutral buffer and chloride solutions was studied. The adsorption of sodium succinate and itaconate is adequately described by the full Temkin isotherm equation with the value of the free energy of adsorption (–ΔG_a⁰) on oxidized copper at E=0.0 V being 77.4 and 65.4 kJ/mol, respectively. The values of (–ΔG_a⁰) for these corrosion inhibitors on the pre-oxidized MNZh5-1 alloy electrode are 89.3 and 58.3 kJ/mol, respectively. Such values of (–ΔG_a⁰) suggest chemisorption interaction of these organic anions with the oxidized surface of copper and its alloy. Corrosion tests of copper and alloy MNZh5-1 in solutions for 7 days showed that a formulation of SKAP with the sodium salt of 2-mercaptobenzothiazole with a 7.1:1.0 mass ratio of the components was the best corrosion inhibitor.

Keywords: copper, MNZh5-1 alloy, dicarboxylates, adsorption, neutral chloride media, ellipsometry, Temkin isotherm

Int. J. Corros. Scale Inhib., 2021, 10, no. 4, 1606-1620
doi: 10.17675/2305-6894-2021-10-4-14

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