金属基底污染程度对防锈油膜电化学不均匀性的影响

INFLUENCE OF SALT CONTAMINATION ON INHOMOGENEITY OF RUST PREVENTIVE OIL FILM

采用丝束电极研究了金属基底污染程度对防锈油膜电化学不均匀性的影响。研究表明 ,基底金属表面受氯化钠污染的程度会影响防锈油膜腐蚀电位及油膜极化电阻分布的不均匀性及其分布规律。随着污染程度的增加 ,防锈油膜腐蚀电位服从不连续二项分布 ,防锈油膜阳极极化电阻Ra 从对数正态分布到指数分布转变为不连续二项分布 ,防锈油膜阴极极化电阻Rc 服从对数正态分布。进一步研究表明 ,基底污染将促进防锈油膜的腐蚀电位和油膜阳极极化电阻的不均匀分布 ,但有利于油膜阴极极化电阻的均匀分布。

On the basis of our previous studies, the salt contamination of the substrate surface, one of factor influencing the inhomogeneity of temporarily protective oil coatings, is investigated by wire beam electrode technique. It has been found that salt contamination of the substrate produces a great influence on the heterogeneous distributions of corrosion potential and polarization resistance. With increasing extent of contamination, the corrosion potentials of oil coatings follow a discontinuous binomial probability distribution. The R a of oil coatings transforms from a lognormal probability distribution to an exponential probability distrbiution and finally to a discontinuous binomial probability distribution. The R c of oil coatings follows a lognormal probability distribution. Further studies have shown that salt contamination of the substrate makes the distribution of corrosion potential and R a of oil coating more inhomogeneous, however, it makes R c of oil coating more homogeneous. Wire beam electrode technique is a useful tool to study the process of underfilm corrosion and evaluate the influence of contamination of oil coatings on the distribution of corrosion potential and polarization resistance.