The Porosity of the Aluminum Surface Investigated by the Repetitive Oscillographic Method

Experiments are reported using a repetitive oscillographic method to investigate the anodic behavior of spectroscopically pure aluminum exposed to a variety of electrolytes including buffer solutions of pH 6, 7 and 8, sulfuric acid and sodium sulfate, nitric acid and sodium nitrate, hydrochloric acid and sodium chloride, acetic acid, oxalic acid and disodium hydrogen phosfate. The method permits determination of the part of the surface area covered by the passivating layer formed through anodic polarization. Results of tests in various electrolytes are reported. Authors postulate the repetitive oscillographic method in combination with the direct polarization method provides a means of testing among reactions occurring at a metal anode.