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The microstructure and oxidation behavior of the N-doped modified layers on uranium surface prepared by pulsed laser irradiating
摘要： The N-doped modi?ed layer on uranium surface was prepared by pulsed laser irradiating in nitrogen atmosphere. The results of microstructure characterised by XRD, AES and XPS show that it is a composite layer with a gradual transition structure from UO2-xNy and uranium oxy-nitride (UNxOy) to UN and eventually to uranium from surface to interior. Initial oxidation behavior after sputtering for di?erent time illustrates that UNxOy with U 4f7/2 BE at 379.6 eV is inert under oxygen exposure. Further, the thermal stability study shows that the modi?ed layer exhibits excellent ability to prevent the O atoms from di?using into the interior at 423 K. Moreover, the corrosion protective properties of the N-doped modi?ed layers before and after thermal treatment were evaluated through potentiodynamic polarization tests. The results show that the N-doped modi?ed layer improved the corrosion protective properties of metallic uranium. The self-corrosive potential and self-corrosive current of the N-doped modi?ed layer are ?5.75 × 10?2 V vs. SCE and 1.37 × 10?7 A/cm2, while the values of metallic uranium were ?5.67 × 10?1 V vs. SCE and 8.08 × 10?7 A/cm2. After thermal treatment, its values are ?8.57 × 10?2 V vs. SCE and 4.83 × 10?8 A/cm2, indicating that the corrosion resistance of the N-doped modi?ed layer was further improved.
关键词： Corrosion resistance,N-doped modi?ed layer,UNxOy,Microstructure,Pulsed laser irradiating
更新于2025-09-16 10:30:52
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The preparation and properties of the C-doped modified layers on uranium surfaces by pulsed laser irradiating
摘要： The C-doped modi?ed layer on uranium surface was prepared by pulsed laser irradiating in methane atmosphere. The microstructure of the obtained layer was characterised by X-ray diffraction (XRD), Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). The results show that the obtained layer is a composite layer with a gradual transition structure from UO2/free carbon to UO2-x/UCxOy/free carbon to UC1-xOy/UC, and eventually to metallic U. To investigate the oxidation mechanism of the C-doped modi?ed layer, initial oxidation behavior of O-rich surface and O-poor surface obtained after sputtering for 7 min and 60 min were studied by XPS. And the results illustrate that UCxOy with U 4f7/2 binding energy at 379.5 eV in the O-rich region is more resistant to oxidation than UC1-xOy/UC under oxygen exposure. Free carbon is distributed in the surface layer of C-doped modi?ed layer prepared by pulsed laser irradiating, and the free carbon is also formed after oxidation of UC1-xOy, UC and UCxOy at room temperature. We speculate that the aggregation of free carbon increases the ability to prevent the inward diffusion of O atoms. Moreover, the results of the potentiodynamic polarization tests show that the C-doped modi?ed layer improved the corrosion protective properties of metallic U. The self-corrosive potential and self-corrosive current of the C-doped modi?ed layer are ?1.47 × 10?1 V vs. SCE and 9.46 × 10?8 A/cm2, respectively, while the values of metallic U are ?5.67 × 10?1 V vs. SCE and 8.08 × 10?7 A/cm2, respectively.
关键词： Microstructure,Uranium oxy-carbide,Pulsed laser modi?cation,Oxidation behavior,Uranium C-Doped modi?ed layer
更新于2025-09-11 14:15:04