合金690在高温充气氯化物溶液中的缝隙腐蚀行为

Crevice Corrosion Behavior of Alloy 690 in High-Temperature Aerated Chloride Solution.

作者信息

Ning Fangqiang, Tan Jibo, Zhang Ziyu, Wang Xiang, Wu Xinqiang, Han En-Hou, Ke Wei

机构信息

CAS Key Laboratory of Nuclear Materials and Safety Assessment, Liaoning Key Laboratory for Safety and Assessment Technique of Nuclear Materials, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China.

School of Materials Science and Engineering, Shandong University of Science and Technology, Qingdao 266590, China.

出版信息

Materials (Basel). 2022 Aug 7;15(15):5434. doi: 10.3390/ma15155434.

DOI:10.3390/ma15155434

PMID:35955369

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC9369497/

Abstract

Crevice corrosion behavior of Alloy 690 in high-temperature aerated chloride solution was studied using a self-designed crevice device. The SEM, EDS, XRD, and XPS analyses results indicated that the oxide films outside the crevice consisted of Ni-Cr oxides containing a small amount of hydroxides, and the oxide films on crevice mouth consisted of a (Ni,Fe)(Fe,Cr)O spinel oxides outer layer and a Cr(OH) inner layer, and the oxide films inside the crevice consisted of a α-CrOOH outer layer and a Cr(OH) inner layer. When crevice corrosion occurred, the hydrolysis of Cr led to the formation of Cr(OH) inside the crevice, and caused the pH value of crevice solution to decrease, and Cl migrated from outside the crevice into inside the crevice due to electrical neutrality principle and accumulation. When the water chemistry inside the crevice reached the critical value of active dissolution of metal, the active dissolution of metal inside the crevice occurred. In addition, (Ni,Fe)(Fe,Cr)O spinel oxides on the crevice mouth were formed by the deposition of metal ions migrated from inside the crevice. The mechanism of crevice corrosion and the formation mechanism of oxide films at different regions were also discussed.

摘要

采用自行设计的缝隙装置研究了690合金在高温充气氯化物溶液中的缝隙腐蚀行为。扫描电子显微镜（SEM）、能谱仪（EDS）、X射线衍射仪（XRD）和X射线光电子能谱仪（XPS）分析结果表明，缝隙外的氧化膜由含少量氢氧化物的Ni-Cr氧化物组成，缝隙口的氧化膜由（Ni,Fe）（Fe,Cr）O尖晶石氧化物外层和Cr（OH）内层组成，缝隙内的氧化膜由α-CrOOH外层和Cr（OH）内层组成。缝隙腐蚀发生时，Cr的水解导致缝隙内形成Cr（OH），使缝隙溶液的pH值降低，由于电中性原理和积累作用，Cl从缝隙外迁移到缝隙内。当缝隙内的水化学达到金属活性溶解的临界值时，缝隙内的金属发生活性溶解。此外，缝隙口的（Ni,Fe）（Fe,Cr）O尖晶石氧化物是由从缝隙内迁移过来的金属离子沉积形成的。还讨论了缝隙腐蚀机理以及不同区域氧化膜的形成机理。