A novel duplex plasma treatment combining plasma nitrocarburizing and plasma nitriding

In this study, a novel duplex treatment (DT) combining plasma nitrocarburizing (PNC) and plasma nitriding (PN) was primarily developed for AISI 1045 steel. The modified samples were investigated by optical microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), microhardness test, and pin-on-disk tribotest. The results showed that the nitriding efficiency was remarkably improved by DT, and the compound layer was much thicker than that treated by PNC or PN alone. Furthermore, higher cross-sectional microhardness and significant enhancement of wear resistance were achieved. The possible enhancement mechanism could be the phase transformation of gamma' to epsilon, and the reduced amount of cementite could be because of the activating and ionizing effect of the subsequent PN on cementite. (C) 2016 Elsevier Ltd. All rights reserved.