Growth and passivation of aluminum etch tunnels at on-off controlling direct current in 6 wt.% HCI solution

作     者：WANG Mei HE Yedong 

作者机构：Beijing Key Laboratory for Corrosion Erosion and Surface Technique University of Science and Technology Beijing Beijing 100083 China 

出 版 物：《Rare Metals》 (稀有金属（英文版）)

年 卷 期：2008年第27卷第2期

页      面：205-209页

核心收录：

学科分类：081704[工学-应用化学] 0806[工学-冶金工程] 08[工学] 0817[工学-化学工程与技术] 0805[工学-材料科学与工程（可授工学、理学学位）] 0703[理学-化学] 0702[理学-物理学] 

基　　金：This study was financially supported by Beijing Education Commission China 

主　　题：aluminum electrolytic capacitor tunnel length growth passivation on-off controlling current 

摘      要：Growth and passivation of tunnels within Al foil by on-off controlling DC etching in 6 wt.% HCI solution has been investigated. It was found that, in a given etchant solution at a special temperature, the longest tunnel length was only a function of the turn-on interval of DC. The potential of Al foil broke at on-off controlling DC by the result from anode polarization curves and potential-time （E-t） responding curves. When DC was switched on, the potential increased abruptly over pitting potential, leading to nucleation of pits at the surface and the growth of tunnels at special length. When DC was switched off, the potential decreased rapidly to a passive value, leading to stoppage of nucleation and death of tunnels. By this way, the longest tunnel length can be controlled and a non-piercing layer can be obtained. Hence, etching of Al foil at this current is beneficial for maintaining a good mechanical strength.