Alloys or metallic compositions – Lead base – Alkali – alkaline earth metal or magnesium containing
Patent
1982-12-28
1985-06-25
Rutledge, L. Dewayne
Alloys or metallic compositions
Lead base
Alkali, alkaline earth metal or magnesium containing
420569, 420590, 429245, C22C 1110, C22C 103
Patent
active
045253277
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to new alloys for manufacturing electrode supports for lead storage cells and more particularly to lead-antimony based alloys containing less than 4% by weight of antimony.
The electrode supports must have good mechanical and chemical characteristics. The addition of antimony imparts very advantageous properties to lead. Besides mechanical characteristics, alloys rich in antimony have good castability. Further, antimony promotes the fixing of the active paste on the supports during cycling.
On the other hand, antimony, which tends to go into solution during the operation of the storage cell, promotes support corrosion and the phenomenon of self-discharge and also reduces the hydrogen-releasing overvoltage.
It is therefore necessary to reduce the antimony content. The addition of a new substance should make it possible to maintain or even to improve the properties of an alloy of reduced antimony content.
The invention provides a lead based alloy containing between 0.05% and 4% antimony and which is intended to be made into lead storage cell electrode supports, characterized in that said alloy contains no barium and contains magnesium, the magnesium content lying between 0.02% and 0.3%.
According to a preferred embodiment of the invention, the alloy contains about 1.8% antimony and 0.15% magnesium.
Additives such as tin, arsenic, copper and sulphur which are generally used in lead-antimony alloys for manufacturing electrode supports and which are designed in particular to improve the castability of these alloys as well as their mechanical strength may also be include in the lead-antimony-magnesium alloy.
Thus, the alloy in accordance with the invention may contain, by weight:
0.05% to 0.3% tin and more especially 0.10% tin in the case where the antimony content is close to 1.8% and the magnesium content is 0.15%;
0.05% to 0.5% arsenic and more especially 0.15% arsenic in the case where the antimony content is close to 1.8% and the magnesium content is 0.15%.
about 0.075% copper;
about 0.006% sulphur;
It is essential for the lead-antimony-magnesium alloy in accordance with the invention, which is intended to produce electrode supports for lead storage cells, to contain no barium. Although the insertion of barium into a ternary lead-antimony-magnesium alloy may increase its resistance to creep, it is observed that such alloys have defects which make them unsuitable for the uses claimed by the Applicant.
Thus, such alloys which contain barium, e.g. those described in French Pat. No. 2 056 237 filed on Feb. 24th, 1970, are difficult to produce because the barium becomes oxidized in the casting bath and are unsuitable since the presence of barium in such alloys gives rise during manufacture to a non-homogeneous structure in the alloy which entails the danger of cracking and during use to high mass corrosion which results in a limited operating life.
More precisely, a lead alloy A in accordance with the invention containing 1.8% antimony and 0.15% magnesium is compared with a lead alloy B containing 1.8% antimony, 0.15% magnesium and 1% barium.
Corrosion measured by potentiometric scanning between 0.6 V and 1.6 V compared with a mercurous sulphate electrode shows that the alloy B is corroded twice as much as the alloy A.
Also, crystallographic examination shows that the alloy B has a rough structure whose grains are of varying sizes, the ratio being 1 to 10 (dimension of the grains 100 to 1000 microns with an average of about 400 microns) while the alloy A has a regular structure which is much finer, the grains having substantially the same dimension, i.e. about 40 microns.
The rough and non-homogeneous structure of the alloy B causes cracking of the electrode supports during manufacture.
Further, during use in sulphuric acid, intergranular corrosion causes cracking which greatly reduces operating life.
In accordance with the invention, because of the difference in density between lead and magnesium and of the danger of forming intermediate compounds of low solubility (PbMg.sub.2 and
REFERENCES:
patent: 484084 (1892-10-01), Bottome
patent: 2061267 (1936-11-01), Downing et al.
patent: 3637440 (1972-01-01), Foerster et al.
patent: 4159908 (1979-07-01), Rao et al.
patent: 4253871 (1981-03-01), Dalibard et al.
Bardin Roland
Counioux Jean-Jacques
Mack Joel
Compagnie Europeenne d'Accumulateurs
McDowell Robert L.
Rutledge L. Dewayne
LandOfFree
Lead-antimony-magnesium alloys for storage cell supports and met does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Lead-antimony-magnesium alloys for storage cell supports and met, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Lead-antimony-magnesium alloys for storage cell supports and met will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-553960