Double glow plasma carburization on zirconium to improve surface hardness and wear resistance

Though some important progress in the excellent mechanical properties of zirconium alloys have been reported,their high surface hardness and good wear properties need to be explored further.In this work,a carburized layer was formed on the surface of commercially pure zirconium by a double glow plasma hydrogen-free carburizing technique.Commercial high-purity graphite was used as the carbon source material.X-ray diffraction(XRD),scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),Vickers hardness test,friction and wear test were used to characterize the samples carburized.The carburized layer could be clearly observed under a microscope.XRD patterns indicate that the zirconium carbide phase is formed in the carburized layer.The surface hardness of the sample increases significantly after carburization.Friction and wear tests results show that wear resistance and friction coefficient of zirconium are improved considerably after carburization.Surface plastic deformation is arrested to a low extent in contrast with pure zirconium because of the presence of ZrC phases during the wear test.The results may provide new insight into methods for surface strengthening of zirconium alloys.