Study on the efficiency of benzotriazole and mercaptobenzothiazole as corrosion inhibitors of some high-alloy steels in neutral environment

• S.G. Bystrov¹, S.M. Reshetnikov^1,2, Е.М. Borisova², Т.А. Pisareva² and V.Ya. Bayankin¹

¹ Udmurt Federal Research Center of the Ural Branch of the Russian Academy of Sciences, 132 Kirova Str., 426000 Izhevsk, Russian Federation
² Udmurt State University, 1 Universitetskaya Str., 426034 Izhevsk, Russian Federation

Abstract: The efficiency of benzotriazole (BTA) and mercaptobenzothiazole (MBT) as corrosion inhibitors of a number of high-alloy steels in a neutral borate buffer solution has been studied. As shown by the results of potentiodynamic and XPS studies the steels under study (30Kh13, 14Kh17N2, 03Kh18N11) are initially in passive state, which causes rather a low rate of their anodic dissolution. Addition of these inhibitors at concentrations of 0.3, 0.5 and 1.0 mmol/L further reduces the anodic dissolution current of the samples in the passive region. At the same time, BTA is usually more efficient as an inhibitor than MBT. XPS studies have shown that both inhibitors are capable of adsorption on the surface of the samples of the steels studied, including that on partially oxidized surface chromium atoms, as well as on the surface iron atoms that having features of an oxidized state. MBT particles form more efficient surface complexes comprising sulfur. The assumption is made that the sulfur atom of MBT forms surface compounds with partially oxidized chromium and iron atoms that are part of the non-stoichiometric oxides of these elements comprising oxygen atoms. Thus, under the conditions studied, BTA and MBT inhibitors favor an improvement of the passivating (protective) properties of the surface of the high-alloy steels tested.

Keywords: high-alloy steels, corrosion inhibitors, chemical composition and structure of surface layers

Int. J. Corros. Scale Inhib., 2022, 11, no. 2, 647-658
doi: 10.17675/2305-6894-2022-11-2-13

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