Electrochemical AC Etching of Aluminum Foils in Hydrochloric Acid Electrolytes

A study has been made of the effects of frequency and bath temperature on the pit size, etched morphology of 99.98% Al foil AC etched in 1.5 M HCl solution. At a certain frequency value, f sub M , porous and homogeneous etched layers were developed. Below f sub M , the foils were macro-thinned and above f sub M , they showed very irregular etched morphology. The etch pit size decreased with increasing etching frequency. The frequency effect on the etched morphology could be explained using galvanodynamic voltametry polarization curves.