非平衡渗入条件下的电化学渗氢模型

Model of Electrochemical Hydrogen-Permeation in Nonequilibrium Entry Condition

提出非平衡渗入条件下的电化学渗氢数学模型,导出相应的渗氢电流暂态关系式。指出由稳态渗氢电流与试样厚度的关系可得表面渗入过程的动力学参数。讨论了阴极极化条件对氢扩散系数观测值的影响。

A mathematical model is proposed for the electrochemical hydrogen-permeation under the nonequilibrium entry condition, and the corresponding expressions for the permeation-current transients are derived. The new model is characterized by the boundary condition at the cathodic side of metal specimen, the so-called 'constant hydrogen concentration' and 'constant hydrogen flux' boundary conditions in the literature are considered as its special cases. It is pointed out that the kinetics of entry process can be determined by the relation between the steady-state permeation currents and the specimen thickness. The dependance of apparent values of hydrogen diffusion coefficient on the cathodic polarization is also discussed.