High-temperature corrosion inhibitors for steel in acid solutions: Current state of the art – a review

• Ya.G. Avdeev

Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31-4, Leninsky prospect, 119071 Moscow, Russia

Abstract: Literature data on inhibitor protection of various steels in high-temperature solutions of hydrochloric, sulfuric, phosphoric, and organic acids are summarized and analyzed. Definitions for the concept of high-temperature corrosion of steels in acid solutions and high-temperature corrosion inhibitors (HTCIs) for metals in these media are given. Based on the analysis of the temperature (t) dependence of the protective efficiency of corrosion inhibitors for steels, it is concluded that high-temperature acid solutions can be defined as media with t≥80°C. Accordingly, HTCIs in these solutions are defined as substances that effectively inhibit steel corrosion under such conditions. Experimental data on the steel corrosion in high-temperature acid solutions are reviewed. It is noted that in the absence of corrosion protection, steels may corrode in such media at extremely high rates (exceeding 1 kg/(m²·h)). The data on the protection of steels in acid solutions (t≥80°C) by acetylene compounds, unsaturated carbonyl compounds, azomethines, Mannich bases, triazoles, and several other compounds are discussed. The use of multicomponent inhibitors rather than individual chemical compounds is shown to be the most promising approach for protecting steels in such media. The role of polymer transformations of HTCIs in the protective mechanism is considered. The formation of HTCI protective film on the steel surface may occur either through polymerization of unsaturated organic compounds present in the inhibitor formulation or through the formation of polymeric complexes from molecules of heterocyclic organic compounds—components of the inhibitor—with Fe(II) cations generated during steel corrosion. The bibliography includes 140 references.

Keywords: steel, acid corrosion, corrosion inhibitors, high-temperature corrosion inhibitors, hydrochloric acid, sulfuric acid, acetylene compounds, unsaturated carbonyl compounds, azomethines, Mannich bases, triazoles

Int. J. Corros. Scale Inhib., 2026, 15, no. 3, 201-229
doi: 10.17675/2305-6894-2026-15-3-8

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