The reduction process of the anodic Pb(ii) oxide film on lead + bismuth alloy in sulfuric acid solution

✍ Scribed by Xia Shen-Jiang; Zhou Wei-Fang

• Publisher: Elsevier Science
• Year: 1995
• Tongue: English
• Weight: 583 KB
• Volume: 40
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(94)00281-5

✦ Synopsis

The anodic film studied was formed on Pb + 9at.%Bi at 0.9V (vs. Hg/Hg,S03 in 4.5 M H, SO, solution (25°C). The change of the phase composition of the anodic film during reduction at -0.91 V (vs. Hg/Hg,SO,) (slightly more positive than that of the reduction potential of PbSO,) was determined by X-ray diffraction (XRD). The experimental results show that the crystals of PbO.PbSO, and t-PbO in the anodic film can be reduced, but B&O, crystals cannot. However, B&O, crystals can be reduced when PbSO, crystals are cathodically reduced. The existence of bismuth in alloy increases the corrosion rate of lead. The current-time transient shows that the process of reduction is limited by three-dimensional growth of circular cones with progressive nucleation when the potential is stepped from 0.9 to -0.91 V for the anodic film on Pb + 9at.%Bi, but for a thicker film it is also controlled by ion transport through the film. The PbSO, film formed on Pb is denser than that on Pb + 9at.%Bi. The reduction process of the anodic film on Pb cannot be described by a simple nucleation and growth mechanism.

Key words: reduction process, anodic Pb(