Early Stages of the Oxidation of Chromium in  H 2 ‐  H 2 O  ‐  H 2 S  Gas Mixtures

Abstract

The oxidation of (100) and (110) orientations of Cr in gas mixtures was studied at 900°C with and . Specimens were analyzed primarily by SEM, TEM, and STEM. No sulfides were detected after one hour with . Sulfides were detected at the Cr/scale interface with . Two‐phase scales comprising and formed at . Preoxidation for two hours with was successful in preventing sulfur penetration for 20 hr. After 111 hr, however, the initial protective oxide was lost and the scale consisted of a mixture of and partially overgrown by .