Studies on the Kinetics of Carbon Deposit Formation on Nanocrystalline Iron Stabilized with Structural Promoters

The carburization of nanocrystalline iron was studied. The process was conducted at a constant temperature (620 °C) under varied partial pressures of methane and hydrogen (p CH4 = 0.67, 0.75, 1.00 bar) and also at p CH4 = 1.00 bar for various temperatures (T = 580, 620, 650 °C) to achieve various carburization degrees (n C/n Fe). The combined thermogravimetric analysis, X-ray diffraction, and scanning electron microscopy data were used to propose a model of carbon deposit formation, containing kinetic equations of the process. The kinetic equations can be used to determine the rate of deposit formation over Fe3C not covered with a carbon deposit, which is impossible in direct measurement.