5083铝合金在模拟海洋浪花飞溅区的局部腐蚀行为  

Localized Corrosion of 5083 Al-alloy in Simulated Marine Splash Zone

作　　者：毛英畅 祝钰 孙圣凯 秦真波 夏大海[1] 胡文彬[1] MAO Yingchang;ZHU Yu;SUN Shengkai;QIN Zhenbo;XIA Da-Hai;HUWenbin(School of Materials Science and Engineering,Tianjin University,Tianjin 300350,China)

机构地区：[1]天津大学材料科学与工程学院,天津300350

出　　处：《中国腐蚀与防护学报》2023年第1期47-54,共8页Journal of Chinese Society For Corrosion and Protection

基　　金：国家自然科学基金(52171077)。

摘　　要：搭建了模拟海洋浪花飞溅腐蚀测试装置,采用电化学阻抗谱(EIS)技术和形貌分析方法研究了5083铝合金在模拟浪溅区的局部腐蚀行为,并比较了其与全浸区腐蚀行为的差异性。实验结果表明:浪溅区由于冲刷作用腐蚀类型较为复杂,呈现孔蚀、晶间腐蚀与剥落腐蚀等多种局部腐蚀形态,且表面覆盖有大量腐蚀产物,局部腐蚀深度约40~80μm。全浸区仅存在分散分布的小蚀坑,深度约5μm,且多数起源于夹杂物处。夹杂物作为阴极相,附近的铝合金基体为阳极区发生溶解。浪花飞溅区蚀坑形状与水流方向有关,蚀坑下边缘在水流剪切力与腐蚀的共同作用下发生了层状剥落,导致蚀坑深度变化较缓,呈台阶状。EIS测试结果表明,浪溅区的极化电阻值约为全浸区的20%~50%,而有效电容值约为全浸区的2倍,表明浪溅区的腐蚀速度远大于全浸区。Besides seawater and marine atmosphere,the service environment of marine equipment such as ships and amphibious aircraft also involves wave splashing.In this work,a corrosion platform in simulated splash zone is constructed,which consists of a simulated splash device and an electrochemical sensor.The localized corrosion of 5083 Al-alloy in simulated splash zone is investigated by using open circuit potential(OCP)measurement,electrochemical impedance spectroscope(EIS)combined with morphology analyses.Experimental results indicate that,compared with the corrosion in the full immersion zone,the alloy suffer severe pitting corrosion,intergranular corrosion and exfoliation corrosion,with a corrosion depth about 40~80μm.The shape of the pits in the splash zone is closely related to the water flow direction.Under the joint action of the shear force of water flow and corrosion,lamellar exfoliation occurs at the bottom edge of the pit,resulting in a slow change in the depth of the pit with terraced inner walls.The high oxygen content and high seawater splash rate are the main cause of the high localized corrosion susceptibility in the splash zone.There are only scattered small pits of about 5μm in depth,in the full immersion zone,and most of them originate from inclusions,whilst the inclusion serves as the cathode phase and the surrounding aluminum alloy matrix behaves as anode and is dissolved.EIS fitting results by using the Measurement Model show that the polarization resistance of the 5083 Al-alloy in the splash zone is 20%-50%of that in the full immersion zone,while the effective capacitance is about twice as large as that of the full immersion zone,indicating that the corrosion rate of the splash zone is higher than that of the full immersion zone.A larger effective capacitance in the splash zone corresponds to a coarser surface on which the corrosion products are accumulated.

关 键 词：5083铝合金 浪花飞溅区 全浸区 局部腐蚀 电化学阻抗谱 

分 类 号：O646[理学—物理化学]