应用XPS,SEM,EDAX及电化学技术,考察了经电化学表面改性处理的18-8不锈钢钝化膜的化学组分、结构及表面缺陷状态的特征,探讨了改性钝化膜的高度耐腐蚀的原因及其机制。结果表明,改性钝化膜中结合水相对含量增加,有利于形成无定形结构的钝化膜表面层,膜中高价铬含量提高,CrO_3与Cr_2O_3共存组成稳定的耐蚀阻挡层,而CrO_4~(2-)使得钝化膜表面层具有阳离子选择性,可排斥侵蚀性阴离子,起到缓蚀作用。此外,改性钝化膜表面物理缺陷组分和状态的变化,使原为腐蚀活性的物理缺陷转变为对腐蚀非活性或对腐蚀比较不敏感,即钝化膜表面趋于均一化。因此,改性的不锈钢钝化膜具有很强的抗局部破坏和耐腐蚀能力。
The XPS,SEM, EDAX and electrochemical techniques were used to examine the characteristics of the chemical composition, structure and surface microscopic heterogeneity of the passive film on 18-8 stainless steel treated by a new electrochemical appreach. It was evident that the relative content of bound water and Cr species with high valence increased in the modified passive film. The modification of the physical defects on surface was observed after the electrochemical surface treatment. The nature and mechanism of the extremely high corrosion resistance of the modified passive film was discussed.
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