Effect of Cetyltrimethylammonium Bromide Additives on Etched Tunnel Formation of Aluminum Foils

In this study, cetyltrimethylammonium bromide (CTAB) additive was introduced to adjust the tunnel etching behavior of aluminum foil. The distribution and growth of etched tunnels in solutions with and without CTAB additive of various concentrations were thoroughly investigated. Compared to the etched tunnels obtained in solutions without CTAB, those obtained in solutions with 1 wt% CTAB had obviously improved distribution and increased length, resulting in an enhancement of the specific surface area. These effects can be attributed to the improvement of wettability between aluminum surface and solution, which is helpful to increase the contact area and facilitate the mass transfer within tunnels. This work exhibits a facile way to improve the tunnel etching behavior of aluminum foil, showing a potential engineering value in industrial production.