Corrosion by carbonaceous gases, carburization and metal dusting, and methods of prevention†

Exposure of metallic materials to carbonaceous gases can lead to (i) carburization, i.e. internal carbide formation causing embrittlement and failure especially at high temperatures of cracking tubes for olefine production, (ii) metal dusting, a disintegration of metals to a dust of carbon and fine metal particles, occurring at intermediate temperatures, e.g. in synthesis gas for ammonia or methanol production or in direct reduction of iron ores, and (iii) coking, the carbon deposition which is an annoying phenomenon in many processes. The mechanisms of these phenomena are well understood now and they can be suppressed or effectively retarded either by the presence of some sulphur in the process gases and/or by a protective dense oxide scale. This review describes the mechanisms and kinetics of corrosion by carbonaceous gases and the fundamentals of prevention.