材料期刊网

采用摸拟缝隙的闭塞电池研究了0Cr18Ni9Ti 奥氏体不锈钢在3%氯化钠溶液中闭塞区内溶液的变化和 Cr(Ⅲ)存在的形态。当电流通过闭塞区时,随电量的增加,溶液的 pH 值迅速下降,Cl~-离子浓集。合金元素 Cr 是导致该体系中缝内阳极液低 pH 值的主要因素。用分光光度法和电化学分析法研究了阳极液,发现 Cr(Ⅲ)是以稳定而可溶的羟氯络合物形态存在于缝内闭塞液中,没有观察到 Cr(Ⅲ)因水解而形成的难溶 Cr(OH)_3沉淀物。根据上述实验结果推断:由于 Cl~-离子在缝内不锈钢表面的特性吸附,并进一步与膜中主要成份 Cr 形成可溶性的羟氯络合物而淡钝化膜遭到破坏,从而使腐蚀加剧。

A simulated crevice corrosion cell was used to study the anolyte within crevice of Steel Cr18Ni9Ti in 3% NaCl sulotion.As the anodic current increased the pH value decreased rapidly and the alloying element Cr was the main factor for the lowering of pH value of anolyte within crevice.It was found that the Cr(Ⅲ)existed in the form of stable soluble hydroxy-chloro-complexes in the occluded solution within crevice.The insoluble hydroxide Cr(OH)_3 precipitate was not observed.It was deduced that the passive film on the surface of the stainless steel within crevice was destroyed by the formation of hydroxy-chloro- complexes through a process of characteristic adsorption of Cl~- ions onto the passive film and then combination with Cr,which was the main component in the passive film.Thus corrosion inside crevice was accelerated.