铜合金在中国南海深海环境下的腐蚀行为研究

CORROSION BEHAVIOR OF COPPER ALLOYS IN DEEP OCEAN ENVIRONMENT OF SOUTH CHINA SEA

通过实海暴露实验,研究了H62黄铜,QAl9-2铝青铜和QSn6.5-0.1锡青铜在中国南海海域800和1200 m深海环境下浸泡3 a的腐蚀行为.结果表明:H62黄铜的腐蚀速率最高,达到0.042 mm/a;QAl9-2铝青铜最低,仅为0.003 mm/a;QSn6.5-0.1锡青铜居中,约为0.004—0.007 mm/a.分析表明:随着水深的增加,H62黄铜的腐蚀速率呈线性降低;QAl9-2铝青铜和QSn6.5-0.1锡青铜的腐蚀速率随水深的增加先降低后升高,腐蚀速率的最小值出现在水深800—1200 m之间.采用SEM,EDS和XRD技术,进行了腐蚀形貌观察和腐蚀产物成分及相组成分析,结果表明:H62黄铜发生了严重的脱锌腐蚀,腐蚀产物由Cu,ZnO,Zn_5(OH)_8Cl_2H_2O和Cu(OH)_2H_2O组成,符合溶解-再沉积机制;QAl9-2铝青铜和QSn6.5-0.1锡青铜发生了脱成分(Al,Sn)腐蚀,QAl9-2铝青铜的腐蚀产物由Cu_2O和CuCl_2组成,QSn6.5-0.1锡青铜的腐蚀产物由Cu_2O,CuCl_2和Cu_2Cl(OH)_3组成.

The corrosion in deep ocean environment has been paied more and more attentions to the exploitation of marine resources. Different from shallow marine environments, deep ocean envi- ronments are specially characterized by high hydrostatic pressure, low temperature, variable dissolved oxygen content and pH value in deep ocean, etc.. So the corrosion behaviour of materials, such as ferrous and nonferrous metal and coatings, in deep ocean environments is different from that in shal- low marine environments. A number of researches have been carried out to investigate the corrosion behaviour of metals in natural deep ocean in a few developed countries. Such researches, however, began until 2008 in South China Sea. In this work, the corrosion behavior of H62 brass, QAI9-2 and QSn6.5-0.1 bronze in 800 and 1200 m deep ocean environments of South China Sea was studied using field tests. The results indicated that the corrosion rates of copper alloys decreased in the following order： H62 （0.042 mm/a） 〉 QSn6.5-0.1 （0.004--0.007 mm/a） 〉 QAI9 2 （0.003 mm/a）. The cor- rosion rate of H62 brass decreased linearly with the increase in depth. While the corrosion rates of QAI9-2 and QSn6.5-0.1 bronze decreased first and then increased with the increase in depth. The minimum value of corrosion rate occurred between 800-1200 m. The morphology and composition of corrosion products were investigated using SEM, EDS and XRD. The results demonstrated that the dezincification corrosion obeying solution-redeposition mechanism in H62 brass occurred. The corro- sion products were composed of Cu, ZnO, Zn5（OH）8CI2H20 and Cu（OH）2H20. And the dealloying corrosion in QAI9-2 and QSn6.5-0.1 bronze occurred. The corrosion products of QAI9 2 bronze consistof Cu20 and CuC12, and those of QSn6.5-0.1 bronze Cu20, CuC12 and Cu2CI（OH）3.