Corrosion behavior of mild steel in aqueous solutions of ammonium nitrate and urea

• G.E. Gornostaeva, D.B. Vershok and Yu.I. Kuznetsov

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

Abstract: The corrosion-electrochemical behavior of St3 mild steel in urea and ammonium nitrate (UAN) solutions at various concentrations of total nitrogen (28 and 32% N), as well as in vapors above the solutions and along the waterline of the aqueous and vapor-gas phases has been studied. It has been found that UAN-28 is more corrosive to this steel than UAN-32. Increasing the temperature of the solutions from 20 to 50°C significantly increases the steel corrosion rate. At the same duration of tests, if the elevated temperature is maintained throughout the experiment, the corrosion rate in the case of total and half-way immersion in UAN solutions is lower than if the sample is exposed at 50°C only for the first 15 h with a subsequent temperature decrease to 20°C. In UAN-28 and UAN-32 solutions, the corrosion rate slows down over time in all the temperature and time ranges studied and in all the three zones: in the liquid bulk, in saturated vapors above the solution, and along the waterline of the liquid and vapor-gas phases.

Keywords: mild steel, corrosion, liquid mineral fertilizers, urea ammonium nitrate fertilizer, UAN

Int. J. Corros. Scale Inhib., 2024, 13, no. 3, 1817-1830
doi: 10.17675/2305-6894-2024-13-3-27

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