Metal Dusting of Ferritic Fe-Ge in the Absence of Cementite

Abstract

Iron and an Fe-10 wt % Ge alloy were exposed at 680◦C to reducing, carbon-supersaturated CO-H2-H2O gas with ac=2.9. Iron grew a scale of Fe3C which slowly disintegrated to form cementite nanoparticles, while graphitic carbon deposited from the gas. The Fe-Ge alloy formed no Fe3C, and carbon deposited directly on the metal surface. As the graphite grew into the metal, nanoparticles of ferrite were dislodged from the surface into the carbon. Metal consumption was more rapid in the latter case.