A diffusion model for simulation of bilayer growth (ε/γ′) of nitrided pure iron

The Law of Growth of Nitrided Layer in 31CrMoV9 Steel

“…The obtained activation energy for the nitriding process is somewhat lower than the value reported by Efe [5], of 150 kJ/mol for gas nitrided 31CrMoV9 steel, but is in excellent agreement with the value reported by Hernandez, et al [7], of 83.1 kJ/mol for gas-nitrided X38CrMoV5.1 steel, and with the value reported by Keedam, et al [8,9], of 77.9 kJ/mol for pure iron. On the contrary, the value of D 0 was found to be higher (7.46 × 10 −3 cm 2 /s) than that reported by Hernandez, et al [7] (1.03 × 10 −3 cm 2 /s) and by Keddam, et al [8,9] (6.6 × 10 −3 cm 2 /s). The observed differences between our results and the results by Efe [5] for the activation energy are probably due to the different nitriding conditions used.…”

Significant acceleration of nitriding kinetics in pure iron by pressurized gas treatment

“…On the basis of thermodynamics, the gas nitriding in flowing NH 3 gas can be viewed as the sum of the reactions [1][2][3]24,25] …”

“…It was reported that the atomic nitrogen is produced by dissociation of ammonia (NH 3 R ) on the metallic surface [1,25,26]. The relation between the nitriding pressure and the nitriding potential (K N ) can be derived from the following equations:…”

“…It has been established that there is a direct correlation between the nitriding potential and the phase composition in the nitrided iron surface [1][2][3]25]. The ε-Fe 2-3 N phase can nucleate and grow in the γ′-Fe 4 N grains when the nitriding potential exceeds the critical value (K N NK γ 0 =ε N ) [19,24].…”

Analysis of the growth of concomitant nitride layers produced by a post-discharge assisted process

“…This nitrogen potential is taken on the surface, which is in thermo-chemical equilibrium with the nitriding environment, and becomes a parameter, through which the nitriding process can be controlled [4][5][6][7][8][9][10][11][12][13][14].…”