8YSZ陶瓷在模拟压水堆水环境中的耐腐蚀性能  

Anticorrosion Performance of 8YSZ Ceramics in Simulated Aqueous Environment of Pressurized Water Reactor

作　　者：范武刚[1] 曹雄[2] 周响[2] 李玲[2] 赵冠楠 张兆泉[1] FAN Wugang;CAO Xiong;ZHOU Xiang;LI Ling;ZHAO Guannan;ZHANG Zhaoquan(Shanghai Institute of Ceramics,Chinese Academy of Sciences,Shanghai 200050,China;Shanghai Nuclear Engineering Research and Design Institute Co.,Ltd.,Shanghai 200233,China)

机构地区：[1]中国科学院上海硅酸盐研究所,上海200050 [2]上海核工程研究设计院股份有限公司,上海200233

出　　处：《无机材料学报》2024年第7期803-809,共7页Journal of Inorganic Materials

基　　金：国家重大科技专项基金(2017ZX06002004)。

摘　　要：8%(摩尔分数)Y_(2)O_(3)稳定ZrO_(2)(8YSZ)陶瓷具有优异的氧离子电导率和低热导率,在燃料电池、热障涂层、隔热等领域都有重要应用。然而它作为压水堆的堆内隔热或结构材料,在事故条件下的水腐蚀机制和耐腐蚀性能目前尚不明晰。本研究在350℃/17.4 MPa,0.3μg/L溶解氧(DO)的动水循环模拟压水堆水环境中,系统考察了8YSZ陶瓷的质量、物相、显微结构、力学性能以及溶液成分随腐蚀时间的变化,并探讨了腐蚀机制。研究发现8YSZ陶瓷的质量随腐蚀时间的延长先增大后减小,并会受表面粗糙度的影响。增重归因于水分子进入陶瓷后形成了Zr–OH和Y–OH团簇,而失重是由金属阳离子析出和晶粒溶解所导致的。物相分析显示立方结构的8YSZ腐蚀后未往四方相或单斜相转变,这与四方相或部分稳定的氧化锆的相变失效不同。表面及断面形貌变化显示水分子可沿缺陷或微裂纹进入陶瓷内部,破坏晶界,使受腐蚀影响区域由穿晶断裂变为沿晶断裂。腐蚀前后8YSZ陶瓷的压缩强度和抗弯强度未明显改变,而维氏硬度略有降低,这与陶瓷表层形成的大量腐蚀坑有关。表面抛光样品腐蚀1050 h时的单位表面积的质量变化率为–0.108×10^(–3)mg·cm^(–2)·h^(–1),腐蚀坑深度仅为30.8μm。这些结果表明8YSZ陶瓷具有优良的耐水腐蚀性能,有望用于压水堆内的隔热或结构材料。8%(molar fraction)Y_(2)O_(3)stabilized ZrO_(2)(8YSZ)ceramics have important applications in fuel cells,thermal barrier coatings,as well as thermal insulation due to their excellent oxygen ionic conductivity and low thermal conductivity.However,their corrosion resistance to water and their behaviors as thermal insulation or structural material in pressurized water reactors during accidents are not fully understood.This study systematically examined the mass,crystal phase,microstructure,mechanical properties,and solution composition of 8YSZ ceramics over time in a dynamic water environment at 350℃/17.4 MPa with 0.3μg/L dissolved oxygen,aiming to simulate a pressurized water reactor environment.It is found that the mass of 8YSZ ceramics increases firstly and then decreases with corrosion duration time.The mass change is influenced by the surface roughness.The weight gain is attributed to the formation of Zr-OH and Y-OH clusters by the entry of water molecules into the ceramics,whereas the weight loss is caused by the metal cations leaching and the dissolution of grains.Phase analysis demonstrates that the cubic 8YSZ after corrosion does not undergo any phase transformation towards tetragonal or monoclinic phases,which is different from the degradation mechanism of tetragonal or partially stabilized zirconia.Changes in surface and cross-section morphology indicate that water molecules enter the interior of the ceramics along defects or microcracks,producing grain boundary damage and changing the fracture mode in the corrosion-affected region from transgranular to intergranular fracture.Compressive and flexural strengths of this ceramics after corrosion do not change significantly,while the Vicker’s hardness decreases slightly,which are related to the formation of pits in the surface layer.As a consequence,depth of the corrosion pit after 1050 h is only 30.8μm,and the mass change rate of per unit surface area is-0.108×10^(-3)mg·cm^(-2)·h^(-1),consolidating excellent water corrosion resistance of 8YSZ ceramic.

关 键 词：8YSZ陶瓷 亚临界水 腐蚀行为 微观结构 力学性能 

分 类 号：TQ174[化学工程—陶瓷工业]