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通过实验和理论分析论述了孔蚀保护电位E_p实质上是孔内外间电流的换向电位E_T。当外部电位负于E_T时,流向闭塞区的电流是阴极电流,导致闭塞区pH值上升,Cl~-外迁,发生再钝化。当闭塞区溶液的pH值下降至临界pH值时,E_T有一突降。E_T在数值上等于闭塞区开路电位与内外溶液间扩散电位之差。文中对采用滞后环曲线测量E_p的影响因素及重现性差的原因也作出了解释。
Through experimental and theoretical analysis, it is discussed that the hole erosion protection potential E_p is essentially the commutation potential E_T of current flowing in and out of the hole. When the external potential is lower than E_T, the current flowing to the occluded area is the cathode current, resulting in the increase of the pH of the occluded area and the re-passivation of Cl ~ -. When the occlusion zone solution pH dropped to the critical pH, E_T has a sudden drop. E_T is numerically equal to the difference between the open circuit potential in the occluded area and the diffusion potential between the inner and outer solutions. In this paper, the factors that affect the measurement of E_p using the hysteresis loop curve and the reason of poor reproducibility are also explained.