Pb-based composites materials for grids of acid battery
Résumé
Newlead-based materials that should use as acid battery electrodes were synthesised by metallurgy powder. The effect of experimental conditions as well as temperature, applied stress, grain size and volume fraction of ceramic additive on the sintering process has been characterized. The higher densification rate, i.e. about 98% of the theoretical value, was reached when 0.5 vol.% of titanium dioxide was added to lead powder. It clearly appeared that the best mechanical properties were reached when the sintered materials were elaborated. The hardness value (about 14 HV) of Pb/0.5 vol.%TiO2 composite slightly fluctuated for long time of treatment at room temperature. From compression tests performed at lower stress (1.4MPa), the creep rate, measured in stationary conditions, of sintered lead was lower of two order of magnitude with regards to that of as-cast lead. The electrochemical corrosion of sintered materials in simulated overcharge conditions was achieved from weight loss measurements and i = f(t) curves. By pumping the electrolyte solution, the residual open porosity of sintered materials led to a severe intergranular corrosion and, consequently, to the grain scaling off.