The formation of alumina coating on ferritic steels

P91 and UNS 430 ferritic stainless steels have been extensively employed in power plants and fuel cell industries. However, their oxidation resistance deteriorates at temperatures above 600°C. In this research, attempts have been made to apply aluminum oxide coatings on P91 and UNS 430 stainless steels through pack cementation and subsequent oxidation. The formation of alumina coatings on ferritic steels is described and the characterization of the coating layer is presented. Furthermore, the oxidation resistance of the coated samples will be discussed. The protective layer mitigated the outward diffusion of elements from the substrate and the coated samples showed relatively good oxidation resistance, after oxidation at high temperatures. Copyright © 2007 MS&T'07®.