ELECTROCHEMICAL-BEHAVIOR OF A PB ELECTRODE UNDER GALVANOSTATIC AND POTENTIOSTATIC CONDITIONS IN HOT ALKALINE-SOLUTION

Anodic oxide films formed on a Pb electrode galvanostatically and pote ntiostatically in 0.1 M NaOH + 0.1 M Na2SO4 solution at 80 degrees C h ave been investigated. Some results concerning the confirmation of ini tial formation of beta-PbO phase on the Pb electrode during galvanosta tic and potentiostatic anodization are described. When the Pb electrod e is galvanostatically anodized at 10 mA cm(-2) in 0.1 M NaOH + 0.1 M Na2SO4, initially beta-PbO phase forms. Further growth of alpha-PbO ta kes place only when the Pb surface is covered with beta-PbO layer. X-R ay diffraction and action spectral data clearly reveal that the format ion of beta-PbO phase takes place initially, followed by the formation of other phases. Analysis of the films formed by potentiostatic anodi zation at -0.6 V also confirms similar observations. These results dif fer from the general understanding that only alpha-PbO forms on a Pb e lectrode in alkaline conditions during its anodization.