Discussion of cementite layer formation and sooting

Received 12 May 2010; received in revised form 4 July 2010; accepted 5 July 2010. published online 15 July 2010.
Corrected Proof

A thermodynamic explanation was recently proposed for the formation of massive layers of cementite without any graphite by gas carburization of steels at 550°C if the gas contains NH3. That explanation is now criticized. It is proposed that a kinetic factor, based on the difficulty of precipitating graphite inside a solid matrix, may contribute to the inhibition of metal dusting in the presence of NH3.

Keywords: Cementite, Graphitization, Carburization, Thermodynamics

Department of Materials Science and Engineering, KTH (Royal Institute of Technology), SE-100 44 Stockholm, Sweden

Corresponding author. Tel.: +46 8 790 8389; fax: +46 8 100 411.

PII: S1359-6462(10)00465-3

doi:10.1016/j.scriptamat.2010.07.013