Abstract
Some significant factors for chemical corrosion of lead-covered telegraphic cable were studied experimentally from the viewpoint of electrochemistry. Corrosion and polarization potential of the lead which is immersed in manhole water or other various corrosive media were measured.
(1) The chemical species (especially anionic) contained in manhole water seem to have something to do with the potential behavioors, and some of them tend to form the protective films. Therefore, it seems more important that this factor should be considered chemically than electrolytically.
(2) The heterogeneous potential distribution on the surface, caused by the ununiformities in micro or macro structures and in their surface differential aerations, were observed. The maximum difference of potential caused by local cell was about 100mV, which was enough to induce the local current leading to anodic corrosion. For example, it appears between the fresh surface and oxidized film. But no anodic acceleration occurred at the contact of lead-cover with the steel pipe used for protection of cables.
(3) From the results above mentioned, some practical informations for preventing corrosion on the lead are proposed concerning the suitable conditions and materials of cable construction.
