Electrochemical Performance of Passive Film Formed on Ti-Al-Nb-Zr Alloy in Simulated Deep Sea Environments  

作　　者：Jing-Jing Dong Lin Fan Hai-Bing Zhang Li-Kun Xu Li-Li Xue 

机构地区：[1]College of Material Science and Chemical Engineering,Harbin Engineering University,145 Nantong Road,Nangang District,Harbin 150001,China [2]State Key Laboratory for Marine Corrosion and Protection,Luoyang Ship Material Research Institute,Wenhai Road,Jimo District,Qingdao 266237,China

出　　处：《Acta Metallurgica Sinica(English Letters)》2020年第4期595-604,共10页金属学报（英文版）

基　　金：This work was financially supported by the National Key Basic Research Program of China(Grant No.2017-JCJQ-ZD-024).

摘　　要：Titanium alloy Ti-Al-Nb-Zr has high specific strength and becomes a promising structural material used in the deep sea.The excellent corrosion resistance of the alloy is derived from the protective passive film formed on its surface.By now,full agreement on interpretation of the anti-corrosion performance of the film in marine environment,especially in the deep sea,has not been reached.In this work,the electrochemical performance of two-surface-state Ti-Al-Nb-Zr alloys which are treated by mechanical polishing and anodizing pre-passivation in the simulated shallow sea,1000 m and 3000 m deep sea environments,is investigated.By interpreting the electrochemical kinetic parameters,it is found that the dominant cathodic process becomes hydrogen evolution in simulated deep sea environments,but the reduction rate is restrained by high hydrostatic pressure,which arrests the passivation of the alloy.Assisted by X-ray photoelectron spectroscopy analysis,it is found that the passive film mainly consists of titanium oxides.There are intermediate oxides with non-stoichiometric ratio involved in the film formation due to the low dissolved oxygen concentration and low temperature.The results of Mott-Schottky and electrochemical impedance show that the film has n-type semiconducting property with oxygen vacancies as the main point defects.The anti-corrosion performance in simulated deep sea environments is one order of magnitude lower than that in the simulated shallow sea environment.However,from 1000 to 3000 m,the corrosion resistance is reduced very slightly.In the inner layers of the passive film and the passive film formed in simulated deep sea environments,the proportion of lowvalence titanium oxides is relatively high.The doping of low-valence titanium(Ti(Ⅱ) or Ti(Ⅲ)) results in a porous structure and ion permeability of the passive film,as well as relatively low corro sion resistance.

关 键 词：Titanium ALLOY OXIDE layer Marine environment Corrosion resistance Mott-Schottky 

分 类 号：TG174.4[金属学及工艺—金属表面处理]