1996 Volume 45 Issue 6 Pages 350-357
Effect of Cr and Si contents in the ferritic stainless steels on the occurrence of reddish brown oxide scale in the kerosene-combustion atmospheres has been studied in the O2+H2O+Ar mixed gases and the combustion portions of kerosene heaters. Furthermore, their effects have been studied in detail by the observation and analysis of the produced oxide scales. In the results, the oxidation behaviour of Cr steels in the O2+H2O+Ar mixtures showed good coincidence with those in the kerosene heaters. Namely, Cr and Si show good effect to prevent the formation of the reddish brown oxide scale. It was found that this good effect can be attained by increasing Cr and Si in the steel following a condition Cr(%)+4Si(%)≥27. When a reddish brown oxide scale occurs, (Cr, Fe)3O4 as well as (Cr, Fe)2O3 was produced in the initially formed oxide scale. In order to prevent the formation of the reddish-brown oxide scale, it was found that the initially formed oxide scale must be M2O3 type which can be attained by the highly Cr-enriched scale (Cr/Fe ratio≥3). Furthermore, Si may enrich Cr in the scale and prevent the oxidation of Fe.
