DE3042011A1 - LEAD-ANTIMONE WALL ALLOY - Google Patents

Abstract

1. Application of a lead-antimony-alloy consisting of 0.1 to 3.5% by weight antimony, 0.01% to 0.1% by weight tellurium, rest lead with impurities subject to its production and containing in case one or more of the additions 0.001 to 0.008% by weight sulfur, 0.005 to 0.035% by weight selenium, 0.005 to 0.5% by weight tin, 0.005 to 0.1% by weight silver, 0.01 to 0.4% by weight arsenic and 0.01 to 0.05% by weight bismuth for the production of rolled and heat treated sheet metal and strips having a high structure stability for manufacturing strip plates for storage batteries by cutting.

Description

METALLGESELLSCHAFT 11/06/198

Aktiengesellschaft -DRQ / GKP-

Reuterweg 14
6000 Frankfurt / Main 1

Prov. No. 864-0 M

Wrought lead-antimony alloy

The invention relates to a 31ei antimony wrought alloy of Composition 0.10 to 3.50 wt.% Antimony, remainder lead, with production-related impurities, preferably for the production of grids for the electrodes of lead-acid batteries.

Lead-antimony alloys are used for the grids of most lead-acid batteries, with the trend towards alloys with a low antimony content "goes (DE-PS 21 51 733, DE-AS 24 39 729). Antimony influences the electrochemical behavior of the lead accumulator in that it is at the Corrosion of the positive grid is released and deposited on the surface of the negative electrode. This lowers the hydrogen overvoltage and the self-discharge as well as the water consumption increases.

On the other hand, the antimony in the positive grids improves the properties of the positive electrodes in the case of cyclic Stress on the lead accumulator. It prevents blowdown the positive ground from the grids so that an accelerated decrease in capacitance is avoided.

In terms of low self-discharge and diminished Maintenance effort of the lead-acid battery becomes a reduction aimed at the antimony content.

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However, the lowering of the antimony content leads to increased processing difficulties of the lead-antimony alloy. In particular, however, the casting properties are impaired.
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In order to overcome the difficulties in processing the low-antimony lead cast materials, further alloy components are added to them. So reduce arsenic levels of 0.02 up to 0.50 wt.% the metal losses through oxidation during casting and at the same time increase hardness and creep resistance the antimony-lead alloy.

Copper additions of 0.01 to 0.10% by weight reduce the metal losses by oxidation during casting and support the grain-refining effect if the alloy is still 0.002 up to 0.012% by weight of sulfur are added.

For the processing of such alloys, additions of 0.005 to 0.100% by weight selenium are used as foundry auxiliaries suitable for refining the Kora. With the alternatively usable Satisfactory grain refinement of the cast structure is also possible with the addition of sulfur.

An addition of 0.002 to 0.500% by weight of tin has the task of protecting the static melts from oxidation when they are moving Melting delay the onset of stronger scratches and improving the leakage behavior of the grids.

The grids of electrodes for lead accumulators made from the above-described low-antimony lead alloys show self-discharge security, maintenance-free and Cycle stability.

The more the antimony content of the lead alloy is reduced the more precisely must the contents of other alloy additives such as copper, arsenic, sulfur, selenium, etc. be adjusted will. Furthermore, a thermal improvement is the one designed for processing the antimony-rich lead alloys Molds required. These disadvantages can be avoided by starting with the low-antimony lead alloys of rolled thin sheets and strips - by metal-cutting shaping processes such as stretching, punching or the like can be processed into grids for the electrodes of lead batteries (DE-OS 29 07 227). By This manufacturing process results in an increase in the energy density due to the weight reduction of the individual grids.

A major disadvantage of the low-antimony lead alloys However, it can be seen in the fact that in the case of strong plastic deformation this is associated with rapid recrystallization suffer with a discontinuous structural segregation, making their good mechanical and corrosion-chemical Properties are lost. A restoration of these positive properties is therefore only possible through a hardening treatment of the deformed material. The problem here is that the deformed material tends to secondary recrystallization to a great extent during homogenization, so that after homogenization the structure is very coarse-grained and therefore very susceptible to corrosion.

The solution to this problem is, according to the invention, that the low-antimony lead alloy mentioned at the beginning is still 0.01 to 0.10 wt.% Tellurium are added.

In addition, the lead alloy can contain 0.001 to 0.008% by weight of sulfur or 0.005 to 0.035% by weight of selenium, which are

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serve to improve the quality of the cast raw material, be added. However, depending on how the process is carried out, these components can be dispensed with, since they are the ones that stabilize the structure Effect of the tellurium is not impaired in any way.

It may be useful to add 0.005 to 1.0% by weight of tin, 0.005 to 0.5% by weight of silver and / or 0.01 to 0.05 wt.% bismuth to improve the cycle stability of the batteries produced and 0.01 to 0, M-O % By weight of arsenic to accelerate the increase in strength after the homogenization.

In the lead alloy composed according to the invention and the grids of the electrodes of

Lead accumulators are maintenance-free, self-discharge security, cycle stability of the batteries and good workability of the alloy · combined in an optimal way.
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The invention is explained in more detail below using an exemplary embodiment:

An ingot of a low-antimony lead alloy (% by weight) of the composition Pb, 0.96 Sb and 0.07 2 Te was made at 1 mm rolled and hardened. As a result, a very fine-grained (diameter 0.05 to 0.10 mm) homogeneously segregated Structure set.

The macro hardness of this material reached a few hours

ο after the heat treatment values of up to 10 kp / mm and s steadily increase in the further course of the aging process, so that after
was achieved.

after the heat treatment values up to 10 kp / mm and increased

A macro hardness of 13 to 14 kp / mm after just one week

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For the tensile strength O (N / mm) values from 50 to found to be 80, while the elongation at break was 30 to M-O%.

The expanded metal grids made from the strip pretreated in this way were assembled to starter batteries after pasting with negative electrodes and then Battery-tested with the result that there was only a minimal self-discharge, more than 300 charge / discharge cycles were maintained and practically maintenance-free was guaranteed. After the test, the cells were removed and the electrodes examined with a light microscope. In the process, an area that was barely measurable with a light microscope became more extensive Corrosion removed on the positive mass carriers.

Further advantages can be seen in the fact that the appropriate choice of antimony, arsenic and tellurium contents provides optimal properties for the use of the grid for electrodes of lead-acid batteries. It can vary depending on the Manufacturing conditions hardness values are achieved that are considerably higher than those of commercially available cast grids. A problem-free further processing of the sheets and strips to mass carriers is through the 5 ensures sufficient elongation at break. There is also a reduction in strength and corrosion resistance not during the subsequent formation and maturation of the mass carriers due to brief exposure to temperature given. This is achieved in particular through the high structural stability brought about by the addition of tellurium. A special Advantage of the low-antimony lead-antimony-tellurium alloy according to the invention consists in the fact that the sheets and strips produced from it are also used in chemical apparatus engineering and in Construction can be used.

Claims (7)

PATENT CLAIMS 1. Wrought lead-antimony alloy with a composition of 0.10 to 3.50% by weight of antimony, the remainder being lead, with production-related impurities, preferably for the production of grids for the electrodes of lead batteries, characterized by a tellurium content of 0.01 to 0, 10% by weight. 2. Wrought lead-antimony alloy according to claim 1, characterized by a sulfur content of 0.001 to 0.008% by weight. 3. Wrought lead-antimony alloy according to Claims 1 or 2, characterized by a selenium content of 0.005 to 0.035% by weight. U. Wrought lead-antimony alloy according to one or more of claims 1 to 3, characterized by a tin content of 0.005 to 0.500% by weight. 5. Wrought lead-antimony alloy according to one or more of claims 1 to 4, characterized by a silver content of 0.005 to 0.10% by weight. 6. Wrought lead-antimony alloy according to one or more of claims 1 to 5, characterized by an arsenic content of 0.01 to 0.40% by weight. 7. Wrought lead-antimony alloy according to one or more of claims 1 to 6, characterized by a bismuth content of 0.01 to 0.05% by weight.