Selected plasma nitriding methods usable for the thermo-chemical treatment of aircraft parts

The aim of the work was to review selected methods of plasma nitriding, which according to the authors might he used in the thermo-chemical treatment of aircraft parts. The introduction explains the nitriding process and presents the requirements on the thermo-chemical treatment of aircraft parts. Three methods of plasma nitriding have been described: Direct Current Plasma Nitriding (DCPN), Active Screen Plasma Nitriding (ASPN) and Low Pressure Nitriding in AEGD (Arc Enhanced Glow Discharge) plasma. While describing DCPN plasma nitriding method, authors drew attention to known problems, which occur in this process such as edge effect or hollow cathode effect. The Keller's model, the Marchand's model and the Walkowicz's model of nitriding process, which can be found in the literature, were also presented in this work. Another purpose of this work was to present hypotheses about the transportation of nitrogen during Active Screen Plasma Nitriding process and to show that in this nitriding method, defects typical for Direct Current Plasma Nitriding do not occur. While describing Low Pressure Nitriding in AEGD plasma, authors also presented the model of nitriding mechanism in this process, which shows four nitrogen diffusion paths (physisorption, chemisorption, adsorption ofNj, ion implantation). Examples of layers obtained by applying described nitriding methods were presented. The measurement ofnitrided layers confirmed that it is possible to obtain a layer without E film on the surface.