Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Cell enclosure structure – e.g. – housing – casing – container,...
Reexamination Certificate
1998-10-30
2001-10-09
Kalafui, Stephen (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Cell enclosure structure, e.g., housing, casing, container,...
C429S179000, C420S569000
Reexamination Certificate
active
06300007
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The field of invention is lead-acid storage batteries. More particularly, it relates to an improved alloy for producing side terminals for these batteries.
2. Background Art
A lead alloy commonly used to make terminals for lead-acid storage batteries is composed of 2.75-3.25% antimony, 0.05-0.20% arsenic, 0.15-0.40% tin, 400-600 ppm copper, less than 30 ppm sulfur and less than 20 ppm selenium. Actual composition specifications for the referenced alloy are those placed into the caster, rather than the finished bushing composition. When parts were produced by gravity casting at temperatures typically above 800° F., this necessitated the use of grain refiners (Cu, S, and/or Se) for suitable metallurgical structure. When parts are produced via a die casting process typically at temperatures below 800° F., such grain refiners (Cu, S, and/or Se) form dross and are reduced or completely lost from the finished part. Unwanted reductions in other alloying elements can occur as dross forms. Drossing losses are an expense that is figured into the bushing cost.
Side terminal bushing properties that are important to safety and functional performance are nut rotation, weldability, weld torque, age hardening, and corrosion resistance. Particularly in hot climate areas which accelerate corrosion processes, improved corrosion resistance is desirable for extended product life and performance. A hypothesis of corrosion sensitivity was developed, which involves the composition of the bushing alloy, welding temperatures (particularly at the lead-to-poly interface), and catalytic or protective interaction of alloy components in the degradation of polypropylene container, and associated lead alloy corrosion due to the interaction of polypropylene decomposition products and lead alloys.
Thus, there is a need for an improved alloy for manufacturing terminals in lead-acid storage batteries.
The objects of the invention therefore include:
a. providing an alloy for manufacturing terminals for lead-acid storage batteries which have reduced drossing during die casting operations;
b. providing an alloy of the foregoing type which reduces material losses and cost of recycling;
c. providing an alloy of the foregoing type which has improved composition stability due to reduced pull-out of alloy components;
d. providing an alloy of the foregoing type which has improved compatibility with polypropylene at elevated temperatures by reducing copper, which catalytically oxidizes polypropylene and increasing tin, which provides anti-oxidant protection to polypropylene;
e. providing an alloy of the foregoing type which has improved grain refinement for the terminal weld joint;
f. providing an alloy of the foregoing type which has improved intrinsic corrosion resistance;
g. providing an alloy of the foregoing type which has improved corrosion resistance when assembled into a finished battery.
h. providing an alloy of the foregoing type which has improved tolerance to high temperature welding conditions; and
i. providing an alloy of the foregoing type which retains minimum void volume, acceptable nut rotation torque, weld torque, and weld current range.
BRIEF SUMMARY OF THE INVENTION
The shortcomings of the prior art and the objects of the invention are accomplished in one aspect by an alloy for use in casting a lead-acid battery terminal which is composed of antimony which is present in the range of about 2.5-4.75%; arsenic present in the range of about 0.15-0.35%; and tin present in the range of about 0.2-0.6%, the percentages being based upon the total weight of the lead-based alloy. Copper is present in the range of about 0-200 ppm, and sulfur is present in the range of about 0-40 ppm. The balance of the alloy is essentially lead.
In a preferred embodiment, antimony is present in the alloy in the range of about 2.75-3.25%; arsenic is present in the range of 0.18-0.28%; and tin is present in the range of about 0.20-0.35%, the percentages being based upon the total weight of the lead-based alloy. Copper is present in the range of about 0-100 ppm, and sulfur is present in the range of about 0-40 ppm. The balance of the alloy is essentially lead.
In a more preferred embodiment, antimony is present in the alloy in an amount of about 3.0%; arsenic is present in an amount of about 0.2%; and tin is present in an amount of about 0.3%. Copper is present in an amount of less than about 50 ppm and sulfur is present in an amount of less than about 15 ppm. Such copper and sulfur ranges are background concentrations which are typically found in smelted lead.
In an alternative embodiment, copper and sulfur are not present in the alloy above such typical background concentrations and the alloy further includes selenium in a range of about 40-90 ppm.
In another aspect, there is a side terminal for a lead acid storage battery comprising a fastening member and a bushing surrounding the nut member. The bushing is molded into a side wall of the battery and is composed of an alloy comprising about 2.5-4.75% antimony; about 0.15-0.35% arsenic; and about 0.2-0.6% tin. Copper is present in the range of about 0-200 ppm, and sulfur is present in the range of about 0-40 ppm. The balance is essentially lead.
In another preferred embodiment, the fastening member of the side terminal is a nut and the side terminal is connected to a wall of a lead-acid storage battery which has a container composed of polypropylene.
In the description, reference is made to the accompanying drawings which form a part hereof, and in which there is shown by way of illustration preferred embodiments of the invention. Such embodiments do not necessarily represent the full scope of the invention. Therefore, reference is made to the claims herein for interpreting the scope of the invention.
REFERENCES:
patent: 3377259 (1968-04-01), Phillips
patent: 3673152 (1972-06-01), Minagawa et al.
patent: 3879217 (1975-04-01), Peters
patent: 5508125 (1996-04-01), Bantz et al.
patent: 8100996 (1982-10-01), None
patent: 0855753 A1 (1998-07-01), None
patent: 1401479 (1975-07-01), None
patent: 1 439 887 (1976-06-01), None
patent: 04 002055 (1992-01-01), None
patent: WO 95/26052 (1995-09-01), None
English Translation of Brazilian Patent Application No. 8100996 (Oct. 1982).
English Translation of Japanese Patent Application No. 04 002055 (Jan. 1992).
G.W. Vinal, A General Treatise on the Physics and Chemistry of Secondary Batteries and their Engineering Applications, Storage Batteries, 4th ed., 1955, pp. 15-18.
Kallup, B.E.; Berndt, D.; Selenium—An Important Additive For Lead-Acid Battery Alloys, Proc. Electrochem. Soc. (1984), 84-14 (Adv. Lead-Acid Batteries), 214-23.
Gillian, W.F., Trends in Lead/Acid Battery Alloy Use and Metallurgy, J. Powers Sources (1987), 19(2-3), 133-42.
Osawa, Z., Ishizuka, T., Catalytic Action of Metal Salts in Autoxidation and Polymerization. X. The Effect of Various Metal Stearates on the Thermal Oxidation of 2,6,10,14-Tetramethylpentadecane, Journal of Applied Polymer Science, vol. 17, pp. 2897-2907 (1973).
Matisova, Rychla, L., Rychly, J., Vavrekova, M., Thermo-Oxidation of Polypropylene in the Presence of PbO, Polymer Degradation and Stability vol. 2, pp. 187-202 (1980).
ASTM Test Method D3895 (1980); Standard Test Method for Oxidative Induction Time of Polyolefins By Thermal Analysis1, Secs. 1-10 and A1.1-A1.3.6.
Maier, C., Calafut, T., Polypropylene: The Definitive User's Guide and Databook, Plastics Design Library, 1998, Section 3.3.
Hansen Christian P.
Klebanov Lena N.
Schaeffer Charles J.
Trischan Glenn M.
Wynn David A.
Crepeau Jonathan
Johnson Controls Technology Company
Kalafui Stephen
Quarles & Brady LLP
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