氧化物乏燃料电解还原过程中的腐蚀与选材研究

Material Development and Corrosion Study in Electrolytic Reduction Process of Spent Oxide Fuel

  • 摘要: 为探索电解还原过程中不同结构材料的耐腐蚀性能,以及低浓度Li2O对材料腐蚀行为的影响,本文研究了Haynes C276、Inconel 600、Incoloy 800和SS 316 4种材料在650 ℃ LiCl-Li2O熔盐和氩气气氛中的腐蚀行为,采用X射线衍射、场发射扫描电镜和能谱分析技术对界面腐蚀产物和形貌进行了分析。结果表明,4种材料均出现了合金元素的选择性溶解和不同程度晶界腐蚀现象,其耐氧化性能表现为Haynes C276>Inconel 600>Incoloy 800>SS 316。在Li2O浓度(质量分数)1%~3.5%范围内,Li2O的作用主要表现为对氧化膜的锂化破坏效应。随着Li2O浓度的升高,Inconel 600合金的氧化腐蚀程度显著加剧,氧化层厚度从2~3 μm急剧增加到150 μm。

     

    Abstract: In order to explore the corrosion resistance of different structural materials in the process of electrolytic reduction and the effect of low concentration of Li2O on the corrosion behavior of materials, the corrosion behavior of Haynes C276, Inconel 600, Incoloy 800 and SS 316 in LiCl-Li2O molten salt under the condition of Ar atmosphere and 650 ℃ was studied. The corrosion product and morphology were characterized by X-ray diffraction, scanning electron microscope and energy dispersive spectrometer techniques. The results indicate that all tested alloys exhibit selective dissolution of active alloy elements and different degrees of grain boundary attacks. The resistance to oxidation ranks in the order of Haynes C276>Inconel 600>Incoloy 800>SS 316. In the concentration (mass fraction) range of 1%-3.5%Li2O, the detrimental effect of Li2O by forming lithium chromium or nickel oxides are more pronounced. With the increase of Li2O concentration, the oxidation corrosion of Inconel 600 is significantly enhanced, resulting in the increase of oxidation layer thickness from 2.3 μm up to 150 μm.

     

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