去膜金属表面最大反应电流与电位的关系

用划破电极的方法研究了无膜不锈钢在氯化物溶液中的反应电流i与电位E的关系,logi与E成直线关系,其斜率达几百毫伏。这一现象在其它材料/环境体系中也存在。分析和推导表明欧姆降、扩散及新鲜金属裸露过程中形成氧化膜都不是电流随电位上升缓慢的主要原因。从阴离子吸附于新鲜表面减小反应活性区面积的角度可以推出具有几百毫伏斜率的表观塔菲尔关系,由此可以推测阴离子吸附对电极反应的影响是表观塔菲尔斜率过大的主要原因。

THE RELATIONSHIP BETWEEN MAXIMUM CURRENT DENSITY ON BARE METAL SURFACE AND APPLIED POTENTIAL

The reaction current density on the surface of scratched stainless steel in chloride solution was studied as a function of applied potential. There is a linear relationship between log i and potential E with a slope of about hundreds of millivolts. This rule is followed not only by the stainless steel/electrolyte system studied in this work, but also by other alloy/environment systems. The detailed discussion shows that the ohmic resistance, diffusion and the oxide ifilm formed during generation of fresh metal surface, can not account for the apparent slow current density increase with applied potential. It has been shown, however, that such large slope arises mainly from adsorption of anions on the bare metal surface.