Effect of N2Flow on Microstructure and Properties of CrN_x Film Prepared by Unbalanced Magnetron Sputtering on the Surface of Depleted Uranium

The chemical nature of depleted uranium is very active and susceptible to oxidation in nature environment.CrNx films were prepared by unbalanced magnetron sputtering ion plating at different N2 flow on the surface of depleted uranium to improve its corrosion resistance.The surface morphology,phase structure,chemical state and corrosion behavior of CrNx films were characterized by SEM,XRD,XPS,and polarization curves(E/I).The results show that,phase structure of CrNx film prepared at 10 sccm N2 flow is composed primarily of the bcc α-Cr.With the increasing of N2 flow,the phase structures transform to HCP-Cr2N and fcc CrN,which preferred orientation transforms from Cr(110) to Cr2N(111) and CrN(200).When N2 flow increases from 10 sccm to 50 sccm,the Cr2p3/2 XPS peaks move toward high binding energy side,the content of metal Cr decreases and the content of nitride chromium increases.When N2 flow increases to 30 sccm,CrNx film has fine grain and better density,its corrosion potential increases to 550 mV and corrosion current density decreases two orders of magnitude.After deposited CrNx film by unbalanced magnetron sputtering,the corrosion resistance of depleted uranium is effectively improved.