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、20μm 3类。采用高温蒸汽氧化设备开展试验,氧化温度为1200℃,等温氧化时间为500~3000 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10μm时,其对锆合金基体保护作用有限,等温氧化2000 s时其表面Cr_(2)O_(3)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15μm时,第一阶段,生成保护性能较好的Cr_(2)O_(3)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20μm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。
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 20μm with well control of thickness variations along the Zr alloy tube axis.High-temperature steam oxidation tests were conducted by synchronous thermogravimetric analyzer at 1200℃for oxidation time ranging from 500 s up to 3000 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 Cr_(2)O_(3)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(Cr_(2)O_(3),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 10μ
作者
严俊
高思宇
杨钟毓
李思功
王占伟
彭振驯
薛佳祥
廖业宏
YAN Jun;GAO Siyu;YANG Zhongyu;LI Sigong;WANG Zhanwei;PENG Zhenxun;XUE Jiaxiang;LIAO Yehong(Institute for Nuclear Fuels and Materials,China Nuclear Power Technology Research Institute Co.,Ltd.,Guangdong Shenzhen 518000,China)
出处
《表面技术》
EI
CAS
CSCD
北大核心
2024年第12期147-157,251,共12页
Surface Technology
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
coated Zr alloy cladding
high-temperature steam oxidation
coating thickness
oxidation kinetics
oxidation mechanism
