Effect of laser treatment of unalloyed steel on the efficiency of benzotriazole as a corrosion inhibitor in a neutral medium

• S.M. Reshetnikov^1,2, T.A. Pisareva¹, E.V. Kharanzhevsky¹, F.Z. Gil’mutdinov² and E.M. Borisova¹

¹ Federal State Budgetary Educational Institution of Higher Education “Udmurt State University”, Universitetskaya st., 1, bldg. 1, 426034 Izhevsk, Udmurt Republic, Russian Federation
² Federal State Budgetary Institution of Science “Udmurt Federal Research Center of the Ural Branch of the Russian Academy of Sciences”, Tatiana Baramzina st., 34, 426067 Izhevsk, Udmurt Republic, Russian Federation

Abstract: The effect of laser irradiation on the corrosion-electrochemical behavior of samples made of low-carbon unalloyed steel in borate buffer solution at pH 7.4 was studied. The modes of laser irradiation were determined (laser irradiation power 20 W; pulse frequency 100 kHz; line width of the trajectory of the laser beam 50 nm; scanning speed 350 (sample 2), 200 (sample 3), or 300 (sample 4) mm/s) ensuring the transition of steel to a passive state and a decrease in the overall rate of anodic dissolution of the metal. Laser irradiation of the samples was carried out in the air atmosphere. After laser treatment, some samples were studied in the same solution with addition of benzotriazole as a corrosion inhibitor. This inhibitor was chosen due to the fact that, like other azoles, it can be present in solution in the form of the initial molecules as well as in protonated form. It has been found that the nanoscale phases created by laser treatment decrease the surface oxidation rate under anodic polarization due to facilitation of transition to the passive state and thus favor an increase in the inhibitor efficiency. The results of XPS and microscopic studies show that laser surface treatment results in the formation of various types of adsorption centers. The assumption is substantiated that the adsorption centers after laser irradiation can be represented by various forms of iron oxides, including nonstoichometric, chemisorbed oxygen, as well as areas of nonoxidized (zero-valent) iron. Depending on the type of adsorption centers, benzotriazole molecules or possible protonation products can be adsorbed with formation of adsorption bonds of various nature.

Keywords: laser treatment, protective layers, corrosion, corrosion inhibitors, benzotriazole

Int. J. Corros. Scale Inhib., 2020, 9, no. 3, 1113-1120 PDF (445 K)
doi: 10.17675/2305-6894-2020-9-3-21

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