Abstract: The chemical nature of depleted uranium is very active and susceptible to oxidation in nature environment. CrN_x 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 CrN_x films were characterized by SEM, XRD, XPS, and polarization curves (E/I). The results show that, phase structure of CrN_x 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, CrN_x 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 CrN_x film by unbalanced magnetron sputtering, the corrosion resistance of depleted uranium is effectively improved.

Key words: delepted uranium, unbalanced magnetron sputtering, CrN_x film, N₂ flow, corrosion resistance