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Effect of current density and perchloric acid concentration on the formation of lead anodes in sulphuric acid baths
Author(s) -
Ragheb A.,
Machu W.,
Boctor W. H.
Publication year - 1972
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/maco.19720230206
Subject(s) - perchloric acid , lead dioxide , current density , chemistry , anode , ion , inorganic chemistry , diffusion , yield (engineering) , porosity , sulfate , materials science , electrode , metallurgy , organic chemistry , thermodynamics , physics , quantum mechanics
At. appr. 1.66 volts and relatively low current densities PbO 2+ ions are able to diffuse through the pores of the lead dioxide layer being formed and may be oxidised directly to yield PbO 2 . In the presence of perchloric acid in the sulfate is formed in the pores of the lead dioxide layer at perchloric acid concentration exceeding 0.1 N. When formation adjuvants — which, on principle, are desirable — are used, certain concentrations must not be exceeded therefore. In addition, it is necessary to maintain the current density around 0.45 ma/cm 2 because only under such conditions the porosity of the lead dioxide layer is sufficient for the diffusion of Pb 2+ ions. The possibility of a direct oxidation of Pb 2+ ions. is shown in terms of the calculated current consumption in the different formation stages.