Effect of Base Lead Composition on Metallurgical Properties of Maintenance‐Free Battery Alloys

Abstract

The effects of trace element additions on the microstructure and age-hardening properties of Pb-Ca and P b -C a -S n alloys for maintenance-free batteries are reported. A specific laboratory casting procedure duplicating grid solidification conditions and the solidification-cast property relationships upon which it is based are discussed. It was found that bismuth, antimony, copper, and silver in amounts typical of high bismuth primary and refined secondary base leads have little or no influence on microstructure in Pb-0.085Ca and P b -0.085Ca-0.8Sn. The addition of trace elements increased the early hardness of Pb-0.085Ca-0.8Sn but had no effect in Pb-0.085Ca. * Electrochemical Society Active Member. ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 129.173.72.87 Downloaded on 2014-12-26 to IP

Casting and Properties of Grid Alloys for Maintenance‐Free Batteries

“…The fibrous dendritic morphology within grains as previously described (3,8) was commonly observed. Breakdown of this structure into s t u b b y -a r m e d branched dendrites was also found (Fig.…”

“…The addition of tin (Fig. 2c and 2d) to P b -C a alloys results in an increase in grain size to approximately that of the base lead alone (3). Variations in tin level influence grain size, but not as significantly as w h e n tin is first added to Pb-Ca.…”

“…The etching procedure used was more effective in removing the cold-worked surface layer formed during polishing than the standard acetic acid etchants. Many of the small, irregular grains and rows of grains in structures observed in the literature can be shown to violate Euler's law for the distribution of grain edges, corners, faces, and bodies in a space-fitting aggregate of polyhedral bodies (3,11), and are therefore artifacts.…”

“…Because of the limited number of data points, the "T Statistic" method was employed with a 90% level of significance procedure. The test was performed at half-day intervals up to three days after casting, as differences between alloys of various trace element contents had been found previously to be significant only for a few days after casting (3).…”

“…Recently, the effects of trace elements in typical commercial base leads on certain metallurgical and electrochemical properties of Pb-Ca and Pb-Ca-Sn alloys have been investigated (3,4). At the compositions studied, it was found that typical levels of bismuth, antimony, copper, and silver did not significantly affect the microstructure or hydrogen evolution rate under cathodically polarized conditions.…”