How can an ultra-thin coating improve corrosion resistance?
The nanocrystalline coating process alters the nucleation and growth of thermal oxides – yielding an oxide surface that is more dense and adherent, even though it is thin. The composition of the surface oxide also changes. This oxidation layer improves the corrosion resistance not only by reducing surface imperfections and voids (as demonstrated with the nickel surfaces shown below) but also by increasing the surface chromium/iron ratio of many alloys. For 410 stainless steel, the surface Cr/Fe ratio of untreated and oxidized alloy is 0.03. After Minimox™ solution treatment and oxidation, the Cr/Fe ratio is 5.7. The composition of the protective layer is primarily a function of the alloy, not the coating material. There is no chromium in the solution.
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