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引用本文:蒋全通,杨黎晖,路东柱,张杰,段继周,侯保荣.典型海洋大气环境中AZ80镁合金电偶腐蚀行为研究.海洋与湖沼,2020,51(4):899-908.
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典型海洋大气环境中AZ80镁合金电偶腐蚀行为研究
蒋全通1,2,3, 杨黎晖1,2,3, 路东柱1,2,3, 张杰1,2,3, 段继周1,2,3, 侯保荣1,2,3
1.中国科学院海洋研究所 海洋环境腐蚀与生物污损重点实验室 青岛 266071;2.青岛海洋科学与技术试点国家实验室 海洋腐蚀与防护开放工作室 青岛 266237;3.中国科学院海洋大科学研究中心 青岛 266071
摘要:
镁合金作为最轻的金属结构材料,具有比强度高、比刚度高、减震性能好、电磁屏蔽等优点。随着海洋强国战略的实施,先进镁合金结构材料逐步在海洋装备上开始应用。已列装的新型高强AZ80镁合金,通过与QBe1.7铍青铜紧固件连接,共同构成整体在典型海洋大气环境中服役。在高盐、高湿的海洋环境环境中,镁合金与电位更正的QBe1.7铍青铜偶接后,极易发生电偶腐蚀。电位相对更负的高强AZ80镁合金,作为电偶腐蚀的阳极被加速溶解。本研究对高强AZ80镁合金电偶腐蚀样品经过12个月青岛海洋大气暴露试验,发现空白对照组、电偶1组(紧固件铍青铜直径Ψ=10mm)和电偶2组(紧固件铍青铜直径Ψ=20mm)的平均腐蚀速率分别为108.1071、133.8929、173.6250g/(m2·a)。电偶对表面的主要腐蚀产物为:Mg(OH)2、MgSO4和MgCl2。空白样品、电偶1组和电偶2组平均腐蚀深度分别为:0.175、0.330、0.315mm/a。样品中部腐蚀深度最大,边部腐蚀深度则相对较小。不同样品在青岛试验站的腐蚀产物对基体保护能力的量度(n值)分别为1.1337、1.1378、1.0895,表明随着暴露时间的延长,试样在海洋大气环境中的腐蚀速率会加快,试样表面的腐蚀产物对基体根本起不到保护作用。通过灰色关联分析法,计算了青岛海洋大气腐蚀站点的环境因素与AZ80镁合金腐蚀深度和腐蚀失重之间的关联度,结果表明:青岛海洋大气环境因素对高强AZ80镁合金空白样品腐蚀失重影响前三位分别为:SO42- > 非水溶性 > 硫酸盐转化率;对电偶1组样品影响前三位的环境因素分别为:SO2 > 硫酸盐转化率 > NO2;对电偶2组样品影响前三位的环境因素分别为:水溶性降尘 > SO2 > NH3。对比电偶对2组和1组,唯一的差别是电偶对的面积比,但决定镁合金腐蚀速度的大气成分完全不同,相关机制会在未来工作中详细研究。
关键词:  典型海洋环境  高强AZ80镁合金  电偶腐蚀
DOI:10.11693/hyhz20200300102
分类号:TG178
基金项目:国家自然科学基金,51501181号;基金委国家重大科研仪器研制项目,41827805号。
THE GALVANIC CORROSION OF HIGH-STRENGTH AZ80 Mg ALLOYS IN TYPICAL MARINE ENVIRONMENT
JIANG Quan-Tong1,2,3, YANG Li-Hui1,2,3, LU Dong-Zhu1,2,3, ZHANG Jie1,2,3, DUAN Ji-Zhou1,2,3, HOU Bao-Rong1,2,3
1.CAS Key Laboratory of Marine Environmental Corrosion and Bio-fouling, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China;2.Open Studio for Marine Corrosion and Protection, Pilot National Laboratory for Marine Science and Technology(Qingdao), Qingdao 266237, China;3.Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China
Abstract:
Magnesium alloys are the lightest metallic materials, featuring excellent properties, such as high specific strength, high specific stiffness, good creep resistance, excellent damping performance, and high heat-conductivity. Due to the requirement of lightweight, magnesium alloys have been widely used in the transportation, weapon manufacture, and aerospace fields. With the rapid development of ocean exploration in the world, magnesium structural materials are gradually served in typical marine environments. To extend the life of Mg alloy, the galvanic corrosion property of high-strength AZ80 alloys were studied. Results show that the weight loss rate of the AZ80 galvanic couple (diameter=2cm) was the highest, while that of the blank control sample was the lowest. With the prolonging of exposure periods, the weight loss rate increased. However, the galvanic acceleration effect firstly increased, and then decreased. The corrosion behavior of AZ80Mg/QBe1.7 Cu alloy galvanic couples in typical marine environment was investigated. The high strength AZ80 magnesium alloy blank sample, diameter=1cm, diameter=2cm galvanic couple corroded in the atmospheric environment after 12 months, the average corrosion rate is 108.1071, 133.8929, and 173.6250g/(m2·a), respectively. The corrosion products were consisted of mainly Mg(OH)2, MgSO4, and MgCl2. The depth of blank sample, diameter=1cm, diameter=2cm galvanic couples was 0.175, 0.330, and 0.315mm/a, respectively. The corrosion depths in the center were larger than the edge. This was because that beryllium copper bar was near the center of AZ80 Mg alloy, which accelerated the corrosion process. Galvanic current range was limited, so the corrosion degree of edge was mainly caused by self-corrosion of Mg alloy. The corrosion kinetic parameter of different samples was 1.1337, 1.1378, and 1.0895, respectively. With the prolonging of exposure periods, the corrosion rate increased, the corrosion products did not protect the Mg alloy. The correlation between the atmospheric pollutants and corrosion depth (weight loss rate) was calculated by grey correlation analysis method. The correlation order between atmospheric pollutants and weight loss rate of the blank control sample was:SO42- > water-insoluble > sulfate conversion rate. The correlation order between atmospheric pollutants and weight loss rate of the sample (diameter=1cm) was:sulfate conversion > SO2 > NO2; that of the sample (diameter=2cm) was:water-soluble dust > NH3 > SO2. The only difference between the galvanic couples was the contact area. However, the atmospheric composition that determines the corrosion rate of magnesium alloy was completely different. Therefore, the relevant mechanism will be studied in detail in our future work.
Key words:  typical marrine environment  high-strength AZ80 magnesium alloy  galvanic corrosion
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