Study of the kinetics of carburisation and nitriding of nanocrystalline iron

In the course of nitriding process of nanocrystalline iron that was promoted with aluminium and calcium oxides, nitrides such as Fe4N and Fe3-2N were created. In the process of carburisation, carbide Fe3C was created. The nanocrystalline iron nitriding and carburisation process rate was studied making use of the flow differential tubular reactor with thermogravimetric measurement of mass changes. Nitriding and carburisation process rates were limited by dissociative adsorption rate on the surface of iron and were dependent on the crystallite surface to crystallite volume ratio. Assuming the adsorption is the rate limiting step, the numerical simulations were performed. Theoretical considerations were compared with the experimental results of the iron nitriding or carburisation reaction. Kinetics and thermodynamic parameters of nitriding and carburisation were determined.