Corrosion of Diffusion Iron–zinc Coatings (Δ-Phase) in an Alkaline Medium

The corrosion behaviour of diffusion iron-zinc coatings of various thickness and chemical composition in an alkaline medium was studied, using gravimetric measurements, electrode potential measurement, scanning electron microscopy, X-ray spectral and diffraction analysis. The study of corrosion of metal alloys and coatings in alkaline media is of interest both from the point of view of corrosion protection of structures in aggressive alkaline solutions and from the point of view of using selective dissolution of components to obtain promising nanosized materials. Diffusion iron-zinc coatings were obtained using zinc powders, the particles of which were coated with a nanostructured porous zinc oxide layer. This approach can significantly improve the efficiency of the galvanizing process. It is shown in the work that the main component of the coatings is the delta-phase. Corrosion of the delta-phase in an alkaline medium is accompanied by the predominant dissolution of zinc. The minimum corrosion rate is observed for diffusion iron-zinc coatings formed by the delta-phase with a zinc content on the surface of similar to 90 at.% and thickness 50 mu m. Selective corrosion of diffusion iron-zinc coatings proceeds with the morphological development of the surface with the formation of numerous cracks and pores, which accelerates the corrosion process.