Anodic Plasma Nitriding in Hollow Cathode (HCAPN)

Abstract

Abstract A study of a proposed plasma nitriding system, exploiting the hollow cathode effect, with treated part biased to anodic potential (Anodic Plasma Nitriding in Hollow Cathode – HCAPN) is presented. The aim of the study was to investigate the differences and similarities with conventional Active Screen Plasma Nitriding (ASPN). At the same time, the experimental results i. e. optical and scanning electron microscopy study of white and diffusion layer along with micro-hardness measurements are presented. Furthermore, the ammonia formation during the nitriding process was studied at different temperatures. We showed that the amount of ammonia reaches a maximum value at 700 K and at higher temperatures the amount of ammonia gradually decreases. This indicates that at the higher temperatures more and more of the formed ammonia dissociates (decomposes) on the hot surfaces of the sample and cathode, transferring the nitrogen to these surfaces, as in the case of classic gas nitriding.