贫铀表面激光氮化层的结构和氧化动力学研究

Investigation of structure and oxidation kinetics of uranium nitride by X-ray diffraction

摘要:

为了研究激光氮化对金属铀表面结构和性质的影响,利用X射线衍射结合原位高温反应器,研究了不同激光氮化工艺后的贫铀表面结构,并对不同温度下UN的氧化过程进行了原位XRD实验分析,获得了相应条件下的氧化动力学曲线。结果显示,激光扫描速率对贫铀表面氮化层的相结构有显著影响,较快的扫描速率能够获得单一的UN结构,较慢的扫描速率将获得UN和U₂N₃的双相混合层。氧化动力学实验表明,表面激光氮化制备的UN层对基材有很好的保护作用,能够显著降低金属铀的氧化腐蚀速率。较低的温度下UN层的氧化非常缓慢,温度升至180℃以上时氧化速率明显加快,其氧化动力学曲线与贫铀有明显差异,文中对此现象和氮化层的氧化机制进行了分析和讨论。

Abstract:

In order to study the effect of pulsed laser nitriding on uranium, the crystal structure and oxidation kinetics of nitride layer were investigated using X-ray diffraction and in situ reactor chamber. The experimental results indicate that the crystal structure of nitride is affected by the scanning speed of pulsed laser remarkably. The UN is the sole nitride at lower scanning speed; the mix structure of UN and U₂N₃ will achieve at higher scanning speed. The oxidation kinetics of uranium is slow in the extreme when the surface is covered with a layer of UN. The oxidation kinetics and oxidation mechanism of nitride are analyzed and discussed in this paper.