Influence of Al(No₃)₃ on the morphology of black chromium coating on AISI 304 steel

Abstract

Stainless steel is one of the most popular construction materials in the energy and manufacturing industry due to its low cost. In aggressive environments, stainless steel lends itself to local types of corrosion, which in just a few days destroy constructions without noticeable structural changes. In many cases, it is hard to identify such a corrosion on early stages of expansion. Generally, it shows up when the construction has already been badly damaged. To increase corrosion resistance and durability of stainless steel it is reasonable to apply black chromium coating on its surface1,2. Black chromium coatings represent chromium oxide layers, which, as we have previously investigated, have in their composition CrO₃, Cr₃O4, Cr2O₃₃. The black chromium layers produced by electroplating, in comparison to other types of black coatings, have excellent wear resistance, rigidity and durability. Also, black chromium is thought to be a high temperature coating with high solar selectivity because black chromium has low luminous reflectivity4,5.