UO_2-ZrO_2固溶体的形成机理和微观结构演变分析  

Formation Mechanism and Microstructural Evolution of UO_2-ZrO_2 Solid Solution

作　　者：黄华伟 李刚[2] 洪震[2] 张安民[2] 张雨[3] 喻冲[3] 

机构地区：[1]中广核研究院有限公司,广东深圳518000 [2]泸州职业技术学院机械工程系,四川泸州646005 [3]中国核动力研究设计院反应堆燃料及材料重点实验室,四川成都610041

出　　处：《原子能科学技术》2017年第9期1633-1638,共6页Atomic Energy Science and Technology

基　　金：国家自然科学基金资助项目(21301164)

摘　　要：采用XRD谱和SEM图像研究了UO_2-ZrO_2芯块固溶体形成过程的离子扩散和化学转变规律。结果表明,ZrO_2扩散至UO_2界面与之发生反应较UO_2扩散至ZrO_2界面与之发生反应更容易。ZrO_2斜方向四方的同素异构转变有利于UO_2固溶体的形成。芯块的结构演变依赖于离子在UO_2与ZrO_2界面(U_xZr_(1-x))O_2和(Zr_yU_(1-y))O_2层的扩散和反应。离子半径和晶体结构的差异使得ZrO_2固溶于UO_2优于UO_2固溶于ZrO_2,导致芯块中的UO_2固溶体长大和ZrO_2固溶体逐渐减小。UO_2固溶体的形成主要是通过schottky缺陷,使Zr^(4+)离子置换U^(4+)离子。The mechanism of diffusion of ion and chemical transformation rule on the formation of solid solution for UO_2-ZrO_2 were investigated by XRD patterns and SEM micrographs.The results show that ZrO_2 with UO_2 diffuses and reacts more easily than UO_2 with ZrO_2.The phase transformation of ZrO_2 from monoclinic to tetragonal enhances the formation of UO_2 solid solution.The structural evolution of pellet depends on the process of the atoms diffusing across the（U_xZr_（1-x））O_2 and（Zr_yU_（1-y））O_2 layers and the reaction at the interface.The differences of cation radii and crystal structure result in that ZrO_2 can dissolve into UO_2 more than UO_2 into ZrO_2,which leads the for-mation of solid solution mainly depends on the growth of UO_2 solid solution,and the ZrO_2 solid solution decreases gradually during the sintering process.The formation of solid solution is mainly the substitution of Zr^（4＋）for U^（4＋）via the schottky defect.

关 键 词：扩散 固溶体 结构演变 

分 类 号：TQ174[化学工程—陶瓷工业]