The surface composition of steels oxidised in carbon depositing atmospheres

✍ Scribed by J.E. Castle; M.J. Durbin

• Publisher: Elsevier Science
• Year: 1975
• Tongue: English
• Weight: 1012 KB
• Volume: 13
• Category: Article
• ISSN: 0008-6223
• DOI: 10.1016/0008-6223(75)90253-5

✦ Synopsis

The deposition of carbon onto steel surfaces from hydrocarbon rich atmospheres is a considerable industrial nuisance and has been the subject of many previous studies. It is well known that both the reaction kinetics and morphology of the deposit are dependant on the composition of the steel. Generally it is observed that nickel enhances and chromium retards deposition. Many authors ascribe this differing behaviour to the catalytic properties of the individual metals or their oxides. We report here an 'in situ' XPS examination of the composition of the oxide layers on nickel steel and chromium steel substrates, as they develop during the course of nucleation and deposition of carbon from carbon dioxide containing acetone. In virtually all cases the substrate on which carbon deposition occurred was magnetite (Fe,O,). We could find no evidence fof the escape of the underlying nickel or chromium into the carbon deposit during the early stages of reaction.

However, as observed by earlier workers the deposits eventually acquired their characteristic morphologies and were then rich in the alloying elements. We conclude that the alloying elements are more important in determining the resistance of the magnetite layer to disruption by the growing carbon.