2. Principle of the nitriding reaction

2.1 Pseudo heterogeneous gas/solid equilibrium

The overall mechanism of nitrogen transfer during the nitriding reaction by the NH ₃ molecule is quite identical to that implemented during carbon transfer during the carburizing reaction by the CO molecule in a CO–H ₂ mixture, and depends on the transfer resistances R1 (gas-phase transport to the surface through the boundary layer) and R2 (chemical reaction at the surface) (Fig. 16