摘要
在反应堆失水事故发生时,锆包壳在高温水蒸气中会发生剧烈氧化,并释放氢气,从而引发严重的氢爆事故。通过Cr涂层能显著提高锆包壳的抗蒸汽氧化能力,涂层表面的Cr2O3膜能够显著抑制氧原子向锆基体扩散。在Cr涂层与Zr基体之间插入微弧氧化(MAO)绝缘中间缓冲层,能够抑制Cr/Zr互扩散,以及避免发生Cr/Zr电偶腐蚀。介绍了锆表面MAO膜及MAO/Cr基复合膜的制备工艺及膜层组织的结构特点,重点总结它们在900~1200℃蒸汽环境中的氧化动力学曲线,以及涂层结构、成分演变规律的研究现状,分析Al、Si合金元素对MAO/Cr基复合膜高温氧化行为的影响,还简要介绍MAO/Cr基复合膜的高能离子辐照效应,最后指出一些问题及后续研究方向。MAO膜及MAO/Cr基复合膜具有良好的抗蒸汽氧化性能,但MAO膜在1100℃以上环境中会失去保护能力,而MAO/Cr基复合膜在1200℃蒸汽环境中仍具有较高的防护性能。MAO绝缘中间层能够抑制Cr、Zr互扩散。将Al、Si合金元素添加到Cr层中,能够进一步提高MAO/Cr复合膜的抗氧化能力,Al2O3和Zr2Si阻挡层的形成分别是MAO/CrAl和MAO/CrAlSi复合膜抗高温氧化能力高的主要原因。
Zirconium alloys have been used as reactor structural materials such as fuel claddings in light water reactors(LWRs)owing to their low neutron capture cross section,good mechanical performance and corrosion resistance.However,the fuel claddings will undergo severe high-temperature steam oxidation under the loss-of-coolant accident(LOCA)condition,and the hydrogen released from oxidation of Zr with water vapor might also trigger severe hydrogen explosion accidents.In recent years,accident tolerant fuel(ATF)has been proposed to reduce the steam oxidation rate and widen the safety margin under normal operation condition.One of the most important ATF concepts is to develop the steam oxidation-resistant coatings on Zr cladding.Up to now,the Cr has been considered to be a potential coating material for Zr cladding,because a dense Cr2O3 layer can be formed to significantly suppress oxygen diffusion inwards.An insulating MAO interlayer between the Cr layer and Zr substrate can be designed to suppress the Cr/Zr inter-diffusion in the high-temperature steam and the galvanic corrosion between Cr layer and Zr substrate in high-temperature lithium borate solution under normal operation condition.The work aims to introduce the preparation process and microstructure of both the MAO coating and MAO/Cr composite coating on Zr and its alloys.The present advances about the oxidation kinetics curves,the evolution of microstructure and composition of these coatings in 900-1200℃steam environment were emphasized,and the effect of Al and Si alloying elements on the high-temperature oxidation behavior of MAO/Cr-based composite coating was analyzed.Furthermore,the high energy ion irradiation effect for MAO/Cr-based composite coating was also briefly introduced.Finally,the future research topics about MAO/Cr-based composite coatings were suggested.It is found that the MAO coating and MAO/Cr-based composite coating on Zr alloys have excellent steam oxidation resistance.However,the MAO coating will fail above 1100℃,while the MAO/Cr composite coating still keeps excellent steam oxidation resistance at 1100℃.In addition,the MAO insulating interlayer between the Cr layer and Zr substrate can suppress the Cr and Zr inter-diffusion in high-temperature environment.The addition of Al and Si elements in the Cr outer layer can further improve the oxidation resistance of MAO/Cr coating,which is ascribed to the formation of Al2O3 barrier layer in MAO/CrAl composite coating and Zr2Si barrier layer in MAO/CrAlSi composite coating,respectively.
作者
薛文斌
李鑫
王利娇
柴璐琪
周茜
王兴平
徐驰
金小越
杜建成
XUE Wenbin;LI Xin;WANG Lijiao;CHAI Luqi;ZHOU Qian;WANG Xingping;XU Chi;JIN Xiaoyue;DU Jiancheng(Key Laboratory of Beam Technology of Ministry of Education,Beijing Normal University,Beijing 100875,China;Institute of Radiation Technology,Beijing Academy of Science and Technology,Beijing 100875,China;Innovation Center of Nuclear Materials for National Defense Industry,Beijing 102413,China;School of Materials Science and Engineering,Lanzhou Jiaotong University,Lanzhou 730070,China)
出处
《表面技术》
北大核心
2025年第15期1-23,共23页
Surface Technology
基金
国家自然科学基金(12405329)
核材料创新基金(ICNM-2022-YZ-02,ICNM-2020-YZ-04)
射线束技术教育部重点实验室开放研究基金(BEAM2024G03)。
关键词
微弧氧化
锆包壳
蒸汽氧化
Cr基复合膜
互扩散
microarc oxidation
zirconium fuel claddings
steam oxidation
Cr-based composite coatings
inter-diffusion
