Chromia scale adhesion on 430 stainless steel: Effect of different surface treatments

In the context of solid oxide fuel cell (SOFC) applications, the adhesion strength and failure location of chromia scale that developed on 430 stainless steel after various surface modifications prior to oxidations between 600 and 800 °C were evaluated. Results demonstrated that the tensile strength and nature of adhesion of the oxide/alloy interface on 430 stainless steel can be compromised by polishing, but can be improved by reducing surface impurities, increasing surface roughness and applying a coating that contains a reactive element, such as Y-nitrate. Optimally, a combination of firing in a reducing atmosphere and applying a thin yttrium nitrate coating was found to be especially effective. These findings identify surface modification techniques that improve scale adhesion for Cr2O3-forming metallic interconnects whether independently or beneath a protective coating.