In-situ monitoring of plasma enhanced nitriding processes using infrared absorption and mass spectroscopy

The active screen (AS) nitriding is an advanced technology for the plasma nitriding of steel components providing a number of advantages over conventional plasma nitriding. Developed in the last decade, the AS technology has found its industrial application, however the understanding of the fundamental mechanisms and their relationship is not complete. For the first time the mid infrared tunable diode laser absorption technique in combination with the quadruple mass spectrometry has been applied in this work. In-situ diagnostics of chemical phenomena in the N2–H2 plasmas under variation of the process conditions such as H2 to N2 gas ratio, process temperature and bias activation power provided valuable information about the concentration of active nitrogen species in the vicinity of the samplesʹ surfaces. The thickness of the compound layer representing the nitriding efficiency was used as a response to nitriding conditions for the evaluation of selected process parameters derived from the plasma diagnostic studies. A 1:1 gas mixture of the N2–H2 process gases seems to be most effective to get thick compound layers.