Regulation of interfacial chemistry by coupled reaction–diffusion processes in the electrolyte: A stiff solution dynamics model for corrosion and passivity of metals

• A stiff solution dynamics model to study local chemistry near a corroding metal.
• Time evolution of concentrations of metal ions, hydroxyl complexes, H+ and OH− ions.
• Time of onset of passivity for Fe and Zn presented for 3 experimental conditions.
• On Zn passivity sets in at much shorter time scales compared to Fe.
• Good physical insight gained into corrosion and passivity of metals.

In this paper we advance a stiff solution dynamics [SSD] model to study the regulation of local chemistry near a corroding metal by reaction and diffusion processes in the electrolyte. Using this model we compute the detailed space–time dynamics of the concentrations of metal ions, its hydroxy complexes, H+ and OH− ions near the corroding metal. The time for the onset of passivity for Fe and Zn is presented for free corrosion condition, different impressed currents and initial pH values. The theory advanced provides much physical insight into corrosion and passivity of metals and motivate spectro-electrochemical studies.