On improving the corrosion and growth resistance of positive Pb-acid battery grids by grain boundary engineering

A frequent failure mode of Starting-Lighting-Ignition (SLI) and other lead- acid batteries relates to weight loss and growth of positive electrode grid s, arising from intergranular corrosion/cracking and creep. The present inv estigation examines the impact of increasing the frequency of grain boundar ies having low-Sigma misorientations (Sigma less than or equal to 29), desc ribed by the Coincident Site Lattice (CSL) model. Such grain boundaries are known to be resistant to intergranular degradation phenomena. Electrode mi crostructures of various PbCaSn alloys processed to contain frequencies of special boundaries in excess of 50% exhibited significant reductions in wei ght loss and grid growth relative to both cast and rolled grid products. Mo difying the crystallographic structure of grain boundaries in Pb alloy batt ery grids thus provides an opportunity for extending the service life and/o r minimizing grid thicknesses (weight) and hence, material costs in battery production. (C) 1999 Elsevier Science S.A. All rights reserved.