Nitriding of tool steel using dual DC/RFICP plasma process

Abstract

Abstract The nitriding process of AISI H13 tool steel samples using dual DC/RFICP source is reported. The aim was to explore the advantages of the process in improving the surface hardness of the material. The reactor incorporated a weakly ionized DC plasma source that provides continuous surface cleaning of the sample and a RFICP discharge source that supplies a highly reactive environment to enhance the kinetics of nitriding process. The gas mixture of Ar, H 2 and N 2 was used as plasma medium. The samples were nitrided for times ranging between 1 and 20 h by keeping the DC source at 300 V, RF power at 100 W and substrate temperature at 300 °C. The hardness profiles obtained revealed a significant improvement of the present method over conventional nitriding and some advantage over other plasma-assisted methods, especially in the comparatively lower process temperature. The evolution of the hardness could be related to the formation of CrN and Fe 4 N as confirmed by XRD and EPMA analysis. Abstract code: AO4