N2，CO2，O2与铀初期反应动力学研究

采用微压PVT方法测定了323K下N2、CO2和O2在清洁铀表面的饱和吸附量及反应概率,对比分析了3种活性气体的反应活性及动力学性质。结果表明,N2、CO2和O2同呈吸附量(覆盖度)趋近一个极大值,反应概率随吸附量增加而减少的特征;反应活性强弱关系为O2>CO2>N2,饱和吸附量关系为NO2≈2.4NCO2≈7NN2。气体与铀的初期反应动力学进程依赖于表面产物层组成和厚度对分子解离和粒子扩散过程的影响,铀氮化物和铀碳化物(或含氧碳化物)较铀氧化物对气体反应动力学进程具有更强的阻抑效应。

Initial Reaction Kinetics of Uranium with N2, CO2 and O2

The saturation capacity and reaction probability of N2,CO2 and O2 adsorption on clean uranium surface at 323 K were quantitatively measured by the low pressure PVT method,and their reactivity and kinetics property were compared and analyzed.Results show that N2,CO2 and O2 exhibit the common reaction characteristics of adsorbed gas amount (coverage) approaching a maximum value and reaction probability decreasing with a rise in adsorbed gas amount.The reactivity ordering of gases with uranium is O2>CO2>N2 and saturation capacity follows the relation of NO2≈2.4NCO2≈7NN2.The initial reaction kinetics relies on the impacts of both product layer composition and thickness on the molecular dissociation and dissociative particles diffusion process,and the uranium nitride,carbide or oxycarbide have a stronger repression effect than uranium oxide on the above process.