The role of electronic structures of passive film in corrosion resistance of transition-metal based alloys

钝化膜电子结构在过渡金属基合金耐蚀性中的作用

• 批准号: 08650827
• 负责人: EZAKI Hisakazu
• 金额: $ 1.22万
• 依托单位: Suzuka National College of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08650827/
• 关键词: Transition Metal based alloy; Titanium alloy; Photoelectrochemistry; Anodic polarization; Photocurrent; Passive film; Electronic structure; Corrosion; 遷移金属

The purpose of this study is to clarify the relations between corrosion resistance of transition-metal based alloys and electronic structures of passive films formed on them. In this study, attention was focused on the passive films of Ti alloys. The electronic states of passive films were examined for Ti and Ti alloys containing 5at% of 3d (V,Cr, Mn, Fe, Co, Ni, and Cu), 4d (Nb and Mo) and 5d (Ta) with the photoelectrochemical technique. In addition, the electronic structures of passive films were calculated by using the molecular orbital calculation method. The calculation results on the electronic structures of passive films were compared with the experimental results.The positive photocurrent was observed when the passive film of each alloy was exposed to the light. This means that the passive films of Ti alloys have the characteristics of n-type semi-conductor. Such characteristics did not change in accordance with the alloying elements. The shape of photocurrent spectra obtained … More by changing the wave-length of incident light also did not change in accordance with alloying elements. The measured band-gap of passive films was about 4. OeV.In contrast to the above fact, the flat-band potential which represents the degree of band bending changed largely depending on the alloying elements. The flat-band potential decreased by the addition of Co, Cu, Nb and Ta, whereas it increased by the addition of Fe and Mo. It was found that the current density necessary for the passivation of alloy, which is a measure of the corrosion resistance of alloy, was well related to the flat-band potential of alloy. The alloy with less-noble flat-band potential has a small current density for the passivation. The values of calculated band-gap of the passive films were in good agreement with those obtained in the experiments. However, there was no obvious relation between the flat-band potential and the calculated Fermi energy level which was expected to be responsible for the band-bending. Further theoretical consideration would be necessary in this regard. Less

本研究的目的是阐明过渡金属基合金的耐蚀性与其上形成的钝化膜的电子结构之间的关系。本文主要研究钛合金表面的钝化膜。用光电化学方法研究了Ti及含5at%的3d（V，Cr，Mn，Fe，Co，Ni，Cu），4d（Nb，Mo）和5d（Ta）的Ti合金钝化膜的电子态。此外，采用分子轨道计算方法计算了钝化膜的电子结构。对钝化膜电子结构的计算结果与实验结果进行了比较，发现每种合金的钝化膜在光照下均出现正光电流。这表明钛合金钝化膜具有n型半导体特性。这些特性不随合金元素的变化而变化。得到了光电流谱的形状 ...更多信息 通过改变入射光的波长也不改变合金元素。钝化膜的禁带宽度约为4。与上述事实相反，表示能带弯曲程度的平带电位随合金元素的变化很大。Co、Cu、Nb、Ta的加入降低了合金的平带电位，而Fe、Mo的加入则提高了合金的平带电位。结果表明，合金钝化所需的电流密度与合金的平带电位有很好的相关性。具有较低惰性平带电位的合金具有较小的钝化电流密度。钝化膜的禁带宽度计算值与实验值吻合较好。然而，平带势和费米能级之间没有明显的关系，这是预期负责带弯曲。在这方面有必要进行进一步的理论考虑。少