Metastable surface modification processes for corrosion and oxidation control

Abstract

This technical note discusses recent advances in the field of high energy surface alloying with particular reference to their non-stoichiometric solid state interaction and their corrosion resistance behaviour by electrochemical techniques. High energy treated surfaces undergo solid state interaction like diffusion, unconventional miscibility, solid solubility and non-stoichiometric compositions which impose a certain degree of metastability on the surface, which alters the electrode surfaces significantly. By introducing a high degree of surface metastability, it is possible to create scope for the physical and chemical properties of the electrodes. This transition of the interface from the metastable state to a stable state is normally accompanied by the formation of a stress free stable thin adherent and protective surface oxide layer. All these aspects are discussed in the present paper in the context of their corrosion resistance industrial usage, in particular to chloroalkali industrial applications. A generalised mechanism of protection of these high energy treated surfaces, is proposed based on surface metastability induced on the surface, as a result of the non-stoichiometry of solid state processing and its electrochemical interactions.