The investigation of surface corrosion of Fe3C in H2SO4 solution and the role of thiophene as an inhibitor by ReaxFF molecular dynamics

N Farzi and MH Hydarifar and ME Izadi, MATERIALS CHEMISTRY AND PHYSICS, 283, 125984 (2022).

DOI: 10.1016/j.matchemphys.2022.125984

The ReaxFF Molecular Dynamics were used in this research to investigate the molecular detail of Fe3C corrosion in sulfuric acid solution in the presence and absence of thiophene as an inhibitor. The results indicate that sulfuric acid is a weaker corrosive agent than hydrochloric acid. It was shown that the surface of Fe3C lattice remains intact in the presence of thiophene molecules. Moreover, the thiophene molecules affect the mechanism of hydrolysis and dissociation of the sulfuric acid molecules. It was inferred that the thickness of the passive layer at 298 K is more than that at 333 K, due to the more hydration of sulfuric acid molecules and reduction of the effective number of diffusing water molecules into the Fe3C lattice at 333 K. The recognized H8SO6, H7SO6, and H6SO5 species at 333 K justifies the role of sulfuric acid as a dehydrating agent. The investigation of 2D-RDF plots in the layers next to the Fe3C surface has shown that the binding of oxygen atoms to the iron atoms of Fe3C surface increases with time.

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