On the mechanisms of diode plasma nitriding in N2–H2 mixtures under DC-pulsed substrate biasing

The results obtained by the author proved that in the conditions of investigated processes the nitriding intensity was influenced by three components of the gas-plasma atmosphere: nitrogen and hydrogen (supplied as the working gas mixture) as well as argon (used as a component of the atmosphere at the stage of initial heating of the substrates before nitriding). The revealed correlation between composition of supplied N2-H2 mixture and: nitrided layer structures, plasma resistance, degree of molecular nitrogen dissociation and concentration of nitrogen molecular ions N2+ shows that both ionized and neutral nitrogen particles participate directly in the nitriding process. The content of N2, H2 and Ar in the nitriding atmosphere determine characteristics of the discharge and relative concentration of nitrogen active species, thus nitriding ability of the individual nitriding processes. On the basis of obtained results, the author proposed the model of mechanisms of diode plasma nitriding taking into consideration intensity of different mechanisms at different nitriding temperatures. Materials used: Armco iron.