氟离子对ZTi60钛合金损伤钝化膜生长过程的影响  

Effect of Fluorine Ions on Film Growth of ZTi60 Titanium Alloy Scratched Surface

作　　者：赵平平 宋影伟[2] 杨丽景 宋振纶 ZHAO Pingping;SONG Yingwei;YANG Lijing;SONG Zhenlun(Key Laboratory of Advanced Marine Materials,Ningbo Institute of Materials Technology and Engineering,Chinese Academy of Sciences,Ningbo 315201,China;Key Laboratory of Nuclear Materials and Safety Assessment,Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China)

机构地区：[1]中国科学院宁波材料技术与工程研究所海洋关键材料重点实验室,宁波315201 [2]中国科学院金属研究所核用材料与安全评价重点实验室,沈阳110016

出　　处：《中国表面工程》2024年第6期226-235,共10页China Surface Engineering

基　　金：国家重点研发计划(2022YFB3808800)。

摘　　要：钛合金由于具有优异的耐蚀性,被广泛应用于海洋工程领域。然而,材料在海洋环境下服役条件恶劣,容易遭受严重的腐蚀破坏。钛合金使用时面临的腐蚀破坏都与钝化膜密切相关,尤其是表面划伤后钝化膜受损引起的局部腐蚀。目前,破损区钝化膜在氟离子F^(-)介质中的演化规律尚不清楚。因此,利用电极划伤装置,对比ZTi60钛合金在中性含F^(-)的3.5%Na Cl溶液中,完整膜层与划伤区域钝化膜生长的动力学过程。结果表明:完整膜层与划伤钝化膜的载流子密度N_(D)皆随F^(-)浓度的增加而增加,这表明钝化膜的生长速率随着F^(-)浓度的增加逐渐增大。对于完整钝化膜,膜层的生长是由氧空位V_(o)的生成反应决定的。相同F^(-)浓度下,电场强度随着膜厚的增加而逐渐增大,供体迁移变得困难,膜生长速度减慢。对于划伤钝化膜,受损钝化膜的划伤区域储存更多的变形能,膜层中的缺陷密度远远高于其他区域,划伤区域氧空位V_?的消耗速率成为膜层生长的速率控制步骤。在钝化膜再钝化过程中,F^(-)与溶解氧对钝化膜中氧空位V_?的消耗反应存在竞争机制,其过程受溶液中F^(-)的含量控制。通过探讨F^(-)与溶解氧的交互作用对损伤钝化膜再钝化过程的影响规律,为钛合金表面在复杂环境中的安全使用提供了理论依据。Titanium alloys are widely used in marine engineering due to their excellent corrosion resistance.However,the service conditions in marine environments are extremely harsh,and the used materials are vulnerable to severe corrosion.Corrosion damage to titanium alloys is closely related to passive films,such as the local corrosion caused by the scratching of the passive film on the surface.Currently,the effect mechanism of scratched passive film on the corrosion process of titanium alloys remains unclear.Therefore,by combining the scratching electrode test and an electrochemical analysis,the corrosion behavior of the ZTi60 titanium passive film after scratching was studied in 3.5wt.%Na Cl with different fluorine ion concentrations.The results indicate that,regarding the intact surface of ZTi60,there is an obvious dependent relationship between the R_(b) and F^(-) concentrations.The R_(b) values first decrease sharply with an increase in the F^(-) concentration.Then,there is a turning point for the slope when the F^(-) concentration is more than 50 mmol/L.The rate of decrease of R_(b) becomes slight,compared with that below 50 mmol/L.This value is related to the critical F^(-) concentration.When the F^(-) concentration is lower than the critical concentration,the passive films could resist F^(-) ,whereas when the F^(-) concentration is higher than the critical concentration,the oxygen vacancies in the passive film could be occupied by F^(-) and the fluorine-titanium complex are formed by the binding between F^(-) and Ti^(4+)in the film lattice.According to the M-S results,the N_(D) values increase with an increasing F^(-) concentration,which responds to the growth rate of the passive film at different F^(-) concentrations.Based on the point defect model,the growth of the intact film is determined by the generation of oxide vacancies _oV,and the rate of film growth becomes faster at higher F^(-) concentrations,which results in an increasing trend of N_(D) with an increasing F^(-) concentration.Under the same F^(-) con

关 键 词：钛合金 表面划伤 Mott-Schottky曲线 氟离子浓度 载流子密度 

分 类 号：TG172[金属学及工艺—金属表面处理]