Computational simulation of corrosion on stainless steels in chemical plants

Abstract

The main metals used in chemical plant industries are 316 stainless steel and mild steel. Critical information for their corrosion mechanism can be drawn from the potential free energy change evolved due to different elements interacting on the surface of the metal. In this project, computational chemistry is used to simulate atom interactions. The potential free energy surface changes are gathered and analyzed. The results show that oxygen provides large atom interaction for corrosion to react while elements like hydrogen and chlorine alone do not provide any obvious atom interaction. This is because oxygen gives rise to a negative potential free energy while hydrogen and chlorine both denote a positive potential free energy. Consequently when doubling the number of oxygen atoms, interaction energy increases by 3 folds. When hydrogen and chlorine are coupled up with oxygen respectively, atom interaction rises enough for potential free energy to be a negative value and corrosion takes place.