6005 A铝合金的表面损伤对其耐海水腐蚀性能的影响

以6005A铝合金商品实际产生的表面少缺陷、多缺陷试样,以及作为比较的完全去除商品表面膜的人工磨制的三种不同表面状态试样为研究对象,研究铝合金商品表面的实际损伤对其耐海水腐蚀性能的影响及其腐蚀电化学行为.通过场发射扫描电镜和激光共聚焦扫描显微镜对具有不同表面状态的6005A铝合金表面形貌和粗糙度进行了表征,表明铝合金商品实际产生的表面缺陷主要为划伤,体现在随着表面缺陷的增多,表面粗糙度Ra明显增大,表面粗糙度Ra大小可以定量描述表面损伤的严重程度.6005A铝合金在NaCl质量分数3.5％的模拟海水溶液中发生全面腐蚀和点蚀,表面缺陷越多,粗糙度越大,耐蚀性越差;电化学测试结果表明,表面缺陷越多,粗糙度越大,腐蚀电位越低,腐蚀电流密度越大,耐蚀性越差.6005A铝合金表面损伤对其耐海水腐蚀性能产生影响的原因为:表面损伤造成铝合金商品原表面膜被破坏,表面缺陷越多,粗糙度越大,表面膜的破坏和表面塑性变形越严重,铝元素会因为被活化而迅速溶解,有着更高的腐蚀速率,而缺陷较少表面有较为均匀致密的氧化膜,对基体有着较好的保护性.

Effect of surface damage on the corrosion resistance of 6005 A aluminum alloy in simu-lated seawater

A 6005A aluminum alloy was produced by an actual surface with less defects, multiple defect samples, and as-ground samples for the purpose of investigating the effect of aluminum alloy surface damage on corrosion resistance and its corrosion electro-chemical behavior in seawater. Scanning electron microscopy ( SEM) and confocal laser scanning microscopy ( CLSM) were employed in order to characterize the surface states of the 6005A aluminum alloy. The results show that the surface defects caused by aluminum alloy products consist mainly of scratches. With the increase of surface defects, an obvious increase in Ra is observed, and Ra could quantitatively describe the severity of surface damage. In simulated seawater, the 6005A aluminum alloy undergoes comprehensive cor-rosion and pitting;thereby, corrosion resistance deteriorates as the amount of defects increases. Electrochemical test results show that the larger the number of surface defects is, the greater are the roughness and lower corrosion potential. Additionally, the greater the corrosion current density is, the worse is the corrosion resistance. A 6005A aluminum alloy that has suffered surface damage and whose corrosion resistance was affected due to seawater can cause the following:the more surface defects are, the greater is the roughness and surface film damage;thereby, the plastic deformation of the surface becomes more serious. The protective layer of the oxide filmis re-duced, and the substrate has a higher corrosion rate. The passive film for the samples with less defects is more compact and uniform and could protect the substrate, while effectively reducing further corrosion.