材料期刊网

<正> 铝及其合金是海洋工程中的常用材料之一。铝在海水中全面腐蚀率极小,约0.03～0.05mm/a,孔蚀是其主要破坏形式。铝设备在海水中的使用寿命取决于耐孔蚀性能。 对铝的蚀孔生长,前人做了一些工作,考察了诸如电位、电流、时间及某些离子对蚀孔生长速度的影响;进行了一些动力学的研究。蚀孔生长过程中孔内Cl~-浓度升高和pH降低,已得到公认,但目前见到的数据极少。闭塞区内溶液的变化对铝孔蚀的影响研究

Characteristics of pit growth on aluminium were investigated in seawater by methods of electrochemical kinetics, analysis of solution in localized corrosion region, metallography and scanning electron microscope. The changes in pH value and the concentration of chloride ion inside pits were measured, the pitting processes were traced by television microscope. Results showed that the composition of anodic solution within a pit changed a great deal from the bulk solution, and that pits developed along a certain orientation and hydrogen was released in the pit, the rate of pit growth increased with the increase of applied potential or temperature. The cause of escaping hydrogen and its effect were discussed. It was thought that the pit growth were characterized by selfcatalysis and gradually decreased in the later stage.