EFFECT OF INITIATIVE PITTING ON AC ETCHING OF ALUMINUM FOIL IN HYDROCHLORIC ACID
铝箔在HCl中交流电腐蚀的起始成孔效应

The initiative pits induced by 50 Hz alternating currents in a 5.5 mol/L HCl and its effect on the further etching behavior of high purity aluminum in the same solution were investigated with csanning electron microscopy and the W t curves. Pits covered with thinner film of corrosion product may formed by AC current pre etching and then they are facilely propagated due to a further follow up AC etching. However without pre etching, a general AC etching smaller pits covered with thicker and black film produced, and thus the pits may be enclosed.