Protection of chromium-nickel steel in hydrochloric acid solution by a substituted triazole

• Ya. G. Avdeev¹, D. S. Kuznetsov², M. V. Tyurina¹, A. Yu. Luchkin² and M. A. Chekulaev¹

¹ K. E. Tsiolkovsky Kaluga state university, 248023 Kaluga, Russian Federation
² A. N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninskii pr. 31, Moscow, 119071 Russian Federation

Abstract: The corrosion of chromium-nickel steel 12Kh18N10T in 2.0 M HCl (t = 20–100°C) was studied using mass loss, potentiometric, and polarization methods. Efficient steel protection under these conditions can be achieved by inhibitors such as triazole derivative IFKhAN 92, alone or in combination with hexamethylenetetramine in a molar component ratio of 1 : 4. The proposed mixed inhibitor often protects steel 12Kh18N10T in HCl solutions in a broad temperature range, 20–100°C, more efficiently than IFKhAN-92 alone at the same concentrations. The triazole in question and its blend with urotropine ensure metal protection in acid solutions for at least 8 h. Since for IFKhAN-92 alone and its blend with urotropine the corrosion inhibition coefficients grow with an increase in temperature, at least to t = 100°C, they should be attributed to so-called “high-temperature inhibitors of acid corrosion”. The presence of inhibitors of interest in the solution considerably increases the fraction of diffusion control in the corrosion process, as indicated by the significant decrease in effective activation energy in the presence of these compounds. Steel corrosion occurs in the active dissolution region both in background and inhibited acid solutions. The corrosion potential of steel is more positive in solutions containing inhibitors because they predominantly slow down the anodic reaction. Addition of IFKhAN-92 or its mixture with urotropine to an HCl solution hinders considerably the electrode reactions on steel in the entire temperature range studied. In this case, the cathodic and anodic current densities decrease with time, while the inhibition coefficients of electrode reactions either increase or remain nearly constant. The corrosion potentials decrease with time in the presence of the additives in question at t = 20–60°C, which suggests that hindrance of the cathodic reaction is predominantly improved due to adsorption of inhibitors. It has been shown that the efficient inhibition of stainless steel corrosion in HCl solution by addition of IFKhAN-92 or IFKhAN-92 + urotropine results from strong hindrance of both electrode reaction on the metal by these inhibitors, which becomes stronger in time and remains in effect as the temperature increases.

Keywords: acid corrosion, corrosion inhibitors, stainless steel, triazoles

Int. J. Corros. Scale Inhib., 2015, 4, no. 1, 1-14 PDF (395 K)
doi: 10.17675/2305-6894-2015-4-1-001-014

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