严俊,高思宇,杨钟毓,李思功,王占伟,彭振驯,薛佳祥,廖业宏.涂层厚度对Cr涂层锆合金包壳高温蒸汽氧化动力学及微观机制的影响[J].表面技术,2024,53(12):147-157, 251.
YAN Jun,GAO Siyu,YANG Zhongyu,LI Sigong,WANG Zhanwei,PENG Zhenxun,XUE Jiaxiang,LIAO Yehong.Influence of Coating Thickness on High-temperature Steam Oxidation Kinetics and Mechanisms of Cr-coated Zr Alloy Cladding[J].Surface Technology,2024,53(12):147-157, 251 |
| 涂层厚度对Cr涂层锆合金包壳高温蒸汽氧化动力学及微观机制的影响 |
| Influence of Coating Thickness on High-temperature Steam Oxidation Kinetics and Mechanisms of Cr-coated Zr Alloy Cladding |
| 投稿时间：2023-07-12 修订日期：2024-03-19 |
| DOI：10.16490/j.cnki.issn.1001-3660.2024.12.012 |
| 中文关键词: 涂层锆合金 高温蒸汽氧化 涂层厚度 氧化动力学 氧化机制 |
| 英文关键词:coated Zr alloy cladding high-temperature steam oxidation coating thickness oxidation kinetics oxidation mechanism |
| 基金项目: |
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| Author | Institution |
| YAN Jun | Institute for Nuclear Fuels and Materials, China Nuclear Power Technology Research Institute Co., Ltd., Guangdong Shenzhen 518000, China |
| GAO Siyu | Institute for Nuclear Fuels and Materials, China Nuclear Power Technology Research Institute Co., Ltd., Guangdong Shenzhen 518000, China |
| YANG Zhongyu | Institute for Nuclear Fuels and Materials, China Nuclear Power Technology Research Institute Co., Ltd., Guangdong Shenzhen 518000, China |
| LI Sigong | Institute for Nuclear Fuels and Materials, China Nuclear Power Technology Research Institute Co., Ltd., Guangdong Shenzhen 518000, China |
| WANG Zhanwei | Institute for Nuclear Fuels and Materials, China Nuclear Power Technology Research Institute Co., Ltd., Guangdong Shenzhen 518000, China |
| PENG Zhenxun | Institute for Nuclear Fuels and Materials, China Nuclear Power Technology Research Institute Co., Ltd., Guangdong Shenzhen 518000, China |
| XUE Jiaxiang | Institute for Nuclear Fuels and Materials, China Nuclear Power Technology Research Institute Co., Ltd., Guangdong Shenzhen 518000, China |
| LIAO Yehong | Institute for Nuclear Fuels and Materials, China Nuclear Power Technology Research Institute Co., Ltd., Guangdong Shenzhen 518000, China |
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| 中文摘要: |
| 目的 研究涂层厚度对Cr涂层锆包壳高温蒸汽氧化行为的影响规律及其微观机制，为耐事故锆包壳表面涂层优化设计提供理论依据。方法 以锆合金包壳为基体材料，采用磁控溅射工艺制备纯金属Cr涂层，目标厚度设计值为10、15、20 μm 3类。采用高温蒸汽氧化设备开展试验，氧化温度为1 200 ℃，等温氧化时间为500~3 000 s，系统研究模拟反应堆失水事故(LOCA)工况下涂层厚度对该材料体系高温蒸汽氧化行为及氧化动力学的影响。试验后，通过X射线衍射仪、场发射扫描电子显微镜及能谱仪等表征各样品氧化膜微结构特征、氧化层厚度、元素分布及物相组成等，基于氧化膜层厚度构建Cr涂层氧化动力学模型，同步探讨涂层原始厚度对其高温蒸汽氧化-失效微观机理的影响。结果 涂层厚度为10 μm时，其对锆合金基体保护作用有限，等温氧化2 000 s时其表面Cr2O3氧化膜和残余Cr涂层已完全丧失保护功能，锆合金基体被连续氧化。涂层厚度为15 μm时，第一阶段，生成保护性能较好的Cr2O3氧化膜，Cr涂层的氧化行为满足抛物线规律;第二阶段，Cr涂层的氧化行为发生转变，氧化膜及其残余涂层保护性能衰退，但锆合金基体始终未被氧化。涂层厚度为20 μm时，Cr涂层的氧化行为满足抛物线规律，但氧化行为未发生转变，表面氧化膜及残余Cr涂层保护性能较好。结论 Cr涂层厚度增加可在一定程度上提升其抗高温蒸汽氧化性能，进而提高反应堆事故工况下燃料包壳抵御事故的能力，从而在一定程度上延长不干预时间。 |
| 英文摘要: |
| Metal chromium is widely used as an antioxidant material because it is easy to develop a protective oxide scale in oxidizing environments. As a result, Cr has been extensively studied for use as a coating material for nuclear fuel cladding.The Cr-coated Zr alloy cladding is one of the most promising accident tolerant fuel (ATF) products for full engineering applications, due to its outstanding high-temperature steam oxidation resistance, satisfactory resistance to corrosion and fretting wear, and higher technological maturity and economic efficiency, less difficult engineering application. In this work, a Zr alloy cladding with outer diameter of 9.5 mm and wall thickness of 0.57 mm was used as the substrate to prepare Cr coatings by magnetron sputtering techniques. The target thickness of Cr coatings was set to 10, 15, and 20 μm with well control of thickness variations along the Zr alloy tube axis. High-temperature steam oxidation tests were conducted by synchronous thermogravimetric analyzer at 1 200 ℃ for oxidation time ranging from 500 s up to 3 000 s. The work aims to systematically study the effect of Cr coating thickness on the oxidation behavior, oxidation kinetics and microscopic mechanisms under hypothetical loss of coolant accident conditions for nuclear reactor. The microstructural characteristics including oxide thickness, element distribution, and phase composition were analyzed by energy dispersive X-ray spectroscopy (EDS), field emission scanning electron microscopy (SEM), and X-ray diffraction (XRD). The oxidation kinetics of Cr coatings based on Cr2O3 oxide thickness were constructed, and the effects of Cr coating thickness on high-temperature oxidation and failure mechanisms were also explored. A three-layer structure (Cr2O3, Cr, Zr-Cr from outside to inside) was formed. Interdiffusion at the coating and substrate interface resulted in the formation of a continuous Zr-Cr layer on the order of micrometer in thickness. It was shown that the protective effect on the Zr substrate was limited at a coating thickness of 10 μm. The protectiveness of Cr2O3 oxide scale and residual Cr coatings were completely lost for 2 000 s, which the substrate was oxidized. At a coating thickness of 15 μm, in the first stage, the oxidation kinetic of coatings followed a parabolic law with protectiveness, and the oxidation rate constant was 0.038 04 μm2/s. In the second stage, the oxidation kinetics shifted, and the protectiveness of Cr2O3 oxide and residual Cr coatings degraded, owing to the redox reaction between Zr and Cr2O3 oxide, and the development of grain boundaries ZrO2 particles within the residual Cr coating. Nevertheless, the oxide scale and coatings after degradation during 2 000 and 3 000 s could still hinder the oxidation of the Zr substrate to a certain extent. At a coating thickness of 20 μm, the overall oxidation kinetic of coatings always obeyed the parabolic law without transformation, and the oxide scale and residual coating were protective, in which the oxidation rate constant was 0.049 62 μm2/s. The results of this study show that the Cr-coated Zr cladding with the thickness of 15 and 20 μm exhibits the most promising behavior with an improved resistance to high temperature steam oxidation. These experimental results could provide data support and theoretical basis for the optimal design of coatings for ATF cladding. |
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