Molecular Orbital Approach to the Design of Corrosion Resistant Zirconiuim Alloys for Nuclear Applications

核应用耐腐蚀锆合金的分子轨道方法设计

• 批准号: 07555500
• 负责人: MORINAGA Masahiko
• 金额: $ 1.28万
• 依托单位: Nagoya University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (A)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07555500/
• 关键词: Corrosion; Zirconiium alloys; Electronic structure; Molecular orbital method; Alloy design

The present study aims to elucidate corrosion mechanism of zirconium alloys in a fundamental manner, and also to get information for the design and development of new cladding materials which is in great demand for realizing higher burn-ups of nuclear fuels in the advanced reactors.A series of corrosion experiments were carried out with a variety of binary Zr-M alloys where M's are Ti, V,Cr, Mn, Fe, Co Ni, Cu and Sn. The auto-clave corrosion tests were performed under the steam conditions of 673 K and 10.3 MPa, and the corrosion time used was 259.2ks. The chemical composition and the electronic structure of the zirconia film formed on the specimen surface were investigated in details using the X-ray photoelectron spectroscopy (XPS). It was found that there was a clear difference in the XPS spectra between highly corrosion-resistant alloys and poorly corrosion-resistant alloys. Also, the observed corrosion resistance depended strongly on the alloying elements, and it changed periodically following the position of elements in the peridic table. Furthermore, it was shown that the alloying elements were not uniformly distributed in the zirconia film, but instead there was a concentrational gradient in it.In addition to these experiments, the DV-Xalpha molecular orbital calculations were performed. Simulated was the nature of the chemical bond between atoms in the zirconia. On the basis of these calculations as well as the experiments, a new model for the corrosion mechanism was proposed for zirconiium alloys. This will provide us a good indication for the design of highly corrosion-resistant zirconium alloys

本研究旨在从根本上阐明锆合金的腐蚀机理，并为先进反应堆中实现更高燃耗的新型包壳材料的设计和开发提供信息。使用多种二元Zr-M合金进行了一系列腐蚀实验，其中M为Ti、V、Cr、Mn、Fe、Co、Ni、Cu和Sn。高压釜腐蚀试验在673 K、10.3 MPa的蒸汽条件下进行，腐蚀时间为259.2ks。使用X射线光电子能谱（XPS）详细研究了样品表面形成的氧化锆膜的化学成分和电子结构。结果发现，高耐蚀合金和差耐蚀合金的XPS谱存在明显差异。此外，观察到的耐腐蚀性很大程度上取决于合金元素，并且它随着周期表中元素的位置而周期性变化。此外，结果表明，合金元素在氧化锆薄膜中的分布并不均匀，而是存在浓度梯度。除了这些实验之外，还进行了DV-Xα分子轨道计算。模拟的是氧化锆中原子之间化学键的性质。在这些计算和实验的基础上，提出了锆合金腐蚀机制的新模型。这将为我们设计高耐腐蚀锆合金提供良好的指导