用XPS研究了1Cr18Ni9不锈钢表面氧化膜的组分与结构。实验表明膜中的Cr/Fe约为体内的3倍,并在组分和价态上具有不均匀的三层结构;表面层的主要成分为Cr,Fe的含氧氢氧化物;中间层的主要成分为Cr,Fe的氧化物;而过渡层则主要由金属状的Fe和少量Fe,Cr的氧化物组成。当阳极氧化膜用Na_2MoO_4溶液处理后,发现在整个氧化膜中都有Mo存在,其含置约为2％。表面层与中间层统称为阻挡层,它是不锈钢抗腐蚀的主要壁垒。过渡层介于阻挡层和基体之间,在这区域中有透过阻挡层进来的少量的氧存在。根据氧化膜中间层中Cr,Fe的氧化程度和过渡层中氧的含量与透入深度,讨论了阳极氧化膜与其它钝化膜(硝酸钝化膜和自然钝化膜)在抗腐蚀性能上差异的原因。
The XPS has been used to study the composition and structure of the oxide film on stainless steel. The film was formed in the transpassive region during the anodic polarization in H_2SO_4 and after a treatment with Na_2MoO_4. It has been found that the ratio of Cr to Fe in the film is about three times higher than that in the bulk. The analysis of the valence states showed that the distribution of each constituent in the film is not uniform. The film has a three-layer structure.The outer layer is rich in OH~- and the middle layer consists mainly of Cr_2O_3 and Fe_2O_3, while the rest of the layer up to the interface contains the Fe~(2+) and Fe~0. The Mo ions have been found throughout the film. The possible mechanism for passivation of the anodic polarization in the transpassive region was discussed and a comparison was made with other oxide films.
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