Study of the Effect of the Initial Nucleation Mechanism of Lead Anode Oxidation Film on Internal Stress in Chromic Acid Electrolyte

Abstract

Lead substrate anodes are widely used in the electroplating and electrolytic field. However, with the change of internal stress, the oxide films are gradually generated on the surface of lead anode. Their structure and stress properties were studied during the oxidation by means of Raman spectra, XRD, SEM. The result showed that the diffraction peaks of lead were mainly found at the initial oxidation stage. With increasing oxidation time, Pb diffraction peaks were weakened and the diffraction peaks of PbO/PbO2 strengthened remarkably. When the oxidation time was above 10 min, monoclinic PbCrO4 was also generated in the oxide film with \( {{{\text{CrO}}_{ 4}}^{ 2- }} \) ions solution as electrolyte. Raman spectra revealed that Raman peaks of PbO/PbO2 were gained. In addition, Raman peaks of PbCrO4 at 830–840 cm−1 were found using the \( {{{\text{CrO}}_{ 4}}^{ 2- }} \) ions as electrolyte. Based on the relationship of the internal stress of oxide film and Raman peaks shift, PbO/PbO2 induced obvious stress generation in \( {{{\text{CrO}}_{ 4}}^{ 2- }} \) ion electrolyte. The nucleation style of oxidation film was 3D progressive nucleation at first. After the peak current, it turned to be 3D instantaneous nucleation. In the oxidation process, the internal stress of PbO/PbO2.