Amending the polarization curves of the Q345 in NaHCO₃ solution through the method of equidistance voltage

The polarization curves of the Q345 were measured in NaHCO₃ solution, and the concentration is 6 mmol/L, 3 mmol/L and 1.5 mmol/L respectively. The anodic polarization curves were amended by means of equidistance voltage. By this way, the influence of the solution resistance to the measurement was eliminated. By the modified results, the kinetic parameters, such as b_a and I_corr could be got easily. Comparing with the results from EIS, under the effect of the polarization, because of the shifting of the iron concentration near the electrode surface and the movement speed of the ions is much fast under the effect of the electric field, solution resistance is less than the resistance at the corrosion potential. Furthermore, the R_sol that calculated by the method of equidistance voltage is reasonable for the calculation range, but it can not be extended to the whole range of the measurement. Otherwise, a big error will be aroused. Being the effect of diffusion process, this method is not suitable for cathodal course.