Initial corrosion behavior and mechanism of 7B04 aluminum alloy under acid immersion and salt spray environments  

作　　者：Yangguang ZHANG Yueliang CHEN Yong ZHANG Guixue BIAN Chenguang WANG Andong WANG 

机构地区：[1]Naval Aviation University Qingdao Campus,Qingdao 266041,China

出　　处：《Chinese Journal of Aeronautics》2022年第1期277-289,共13页中国航空学报（英文版）

基　　金：co-supported by the China Postdoctoral Science Foundation(No.2019M653929);the Green Innovation Science;Technology Plan of Colleges;Universities in Shandong Province,China(No.2020KJA014).

摘　　要：The initial corrosion behavior and mechanism of 7B04 aluminum alloy under acid immersion and salt spray environments(pH=3.5)are studied by Scanning Electron Microscope(SEM),optical microscope,Fourier Transform Infrared Spectroscopy(FT-IR),X-Ray Diffraction(XRD),potentiodynamic polarization,Electrochemical Impedance Spectroscopy(EIS),and Scanning Kelvin Probe(SKP).The results show that pitting corrosion occurs at the initial corrosion stage,and the potential difference between the second phase particles is the main cause of pitting.Pitting pits on different locations gradually expand and coalesce with the proceeding of corrosion.The main components of corrosion products are Al_(2)O_(3),Al(OH)_(3),and AlCl_(3),and the generation rate of the corrosion product layer under the salt spray environment is larger than that under acid immersion environment.Under both environments,the Volta potential distribution first disperses and then concentrates,while the charge transfer resistance first decreases and then increases with the corrosion time.The Volta potential gradually shifts in a positive direction,indicating that corrosion products have an inhibitory effect on corrosion.After the same corrosion time,the corrosion product layer resistance and the expectation of the Volta potential of the salt spray sample are higher than those of the immersion sample.Comparatively,the corrosion current density for the salt spray sample is significantly lower than the immersion sample,which indicates that the thicker the corrosion product layer,the stronger the inhibition of corrosion reaction.

关 键 词：7B04 aluminum alloy Acid salt spray Corrosion mechanism Corrosion products ELECTROCHEMISTRY Scanning Kelvin probe 

分 类 号：V252.2[一般工业技术—材料科学与工程] V267[航空宇航科学与技术—航空宇航制造工程]