DE2656876A1 - HIGH STRENGTH LEAD ALLOY AND ACCUMULATOR PLATES MANUFACTURED FROM THEM - Google Patents

Description

«Τ -u TT ί τ Möhlstrasse 37

GlODe-Union Inc., D-8000 Munich 80

Milwaukee, Wise, V.St.A. Tel.:089/982085-87

Telex: 0529802 hnkld telegrams: ellipsoid

1 5 DEC. 1976

High strength lead alloy and accumulator plates made from it

The invention relates to a new high strength lead alloy. An alloy according to the invention is particularly suitable as a plate and / or cover (lead) material for
Acid accumulators make certain of their properties
however, they are also attractive for use in other applications where high strength lead is required.

In acid accumulators, lead alloys containing antimony are typically used as the main component. The antimony in particular has a greater influence on the physical properties of lead. Antimony thus contributes in particular to increasing the strength and / or improving other physical properties of lead, which makes the production of the accumulators easier in various ways.

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In the case of accumulator plates, it is particularly important that the plates or grids have a normal Able to withstand handling during the accumulator manufacture and operation.

Recently, accumulators have been developed which have a minimal, if any, at most Maintenance, namely only an addition of water to maintain the electrolyte level, require. In the case of accumulators of this type, it is customary either to seal the accumulators or for the filling openings Use vent ports by the end user cannot be easily removed. Since in such accumulators the need for filling is avoided is to be, one must choose a lead alloy system in which the electrolyte supply over the intended life (of the respective accumulator) does not noticeably decrease. The presence of antimony results in acid accumulators in typically to excessive gas formation, especially when charging or overcharging. This will ultimately affects the quality of the electrolyte. In addition, excessive gas formation is reduced or in Batteries that are out of service, provided they are completely sealed or sealed, are undesirable. Usual Alloys for this type of accumulator contain calcium instead of antimony. In the case of calcium alloys, this is Gas formation reduced. Examples of suitable lead / calcium alloys see U.S. Patents 3,920,473, 3,881,953, 3,287,165, 2,794,707, 2,159,124 and 1,703,212.

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A disadvantage of the lead / calcium system is that its alloys usually do not have mechanical properties comparable to those of lead / antimony alloys. Since the accumulator industry is constantly striving to have accumulator plates with a smaller cross-section than the have known accumulator plates, produce the strength of the lead / calcium plate alloys is a limiting factor for the panel construction or construction. Lead / calcium systems are also known to have the property of growing or puffing up mechanically. When the bloating in an accumulator is excessive adjacent parts can be short-circuited so that either the accumulator no longer works or at least its capacity is greatly reduced. The puffing up can become excessive even with minor changes in the alloy composition.

Another disadvantage of conventional alloys is the limited reusability of lead waste due to reduced Processing stability. For example, the melting of the waste causes excessive foam lift-off, resulting in a loss of calcium in the alloy. So must the remelted waste readjusted to bring the alloy composition back to the desired range prior to casting bring. Finally, it comes with lead / calcium alloys while mechanically moving the molten alloy (both the original alloy and in the remelted waste) to an increased foam lift-off, so that protective measures are taken, e.g. covered crucibles must be provided.

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Strontium has also been used as an alloy component in lead alloys. For example, from the US-PS 1,158,672 a lead alloy containing several alkaline earth metals, including calcium, barium, strontium and magnesium, known for use in projectiles. From US Pat. No. 2,013,487 a lead / strontium / tin alloy is for use became known in accumulators. A lead / strontium alloy is disclosed in US Pat. No. 2,040,078, and US Pat 2 170 650 a lead / calcium / barium / strontium alloy is known. However, all known strontium-containing lead alloys allow protection against foam lifting and Processing stability when remelting and with regard to high strength leave a lot to be desired.

The invention was now based on the object of an improved lead alloy for use in acid accumulators and to create other fields of application, which are characterized by excellent physical and / or electrochemical properties and in particular can be remelted without any noticeable change in its composition.

The subject of the invention is thus a lead / strontium alloy, Consisting of 0.01 to 2% by weight of strontium, 0.1 to 5.0% by weight of 96% by weight tin, 0.005 to 0.1% by weight of 96% aluminum, 0 to 0.25% 96% copper and the remainder lead.

An alloy according to the invention is obtained by conventional melting. Quantities of the desired alloys used for research purposes were selected in the laboratory Mother alloys with a higher content of the individual alloy components, when the ultimately desired alloy

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tion must have produced. A tin / aluminum mother alloy was made by dissolving the aluminum in either pure tin or a binary lead / tin alloy. Copper mother alloys were obtained by dissolving elemental copper in corrosive lead or ternary lead / tin / aluminum alloys. A lead / strontium binary alloy was purchased, but standard smelting techniques can also be used to make it. The specific alloy compositions were prepared by adding suitable quantities of the mother alloys to korrosionsfähigem lead at temperatures up to 55O ⁰ C. When alloying took place in air, excessive oxidation was avoided by adding first tin / aluminum mother alloys and then adding the strontium mother alloys. The order of addition is not critical if a gas shield is used to protect the crucible.

Table I below illustrates the mechanical properties of typical lead / calcium and lead / antimony alloys for acid accumulator plates. Contained in addition to the alloy components specified in the table the individual alloys in each case lead to the remainder. That makes up the rest of the alloys in Tables I and II Lead consists of industrially produced, primary or secondary, corrosive lead with melting-related lead Impurities. While pure lead would of course be most useful, it will be more understandable for those skilled in the art From an economic point of view, it is not justified to use this in acid accumulators.

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Table II shows a wide variety of lead alloys according to the invention Composition. The same criteria apply here as for the alloys in Table I. Let it be noted that in most cases the lead / strontium alloys have the same strength or better Have strength like (as) the calcium alloy. An investigation (the results of which are recorded in Table II are) also shows that after 24 hours or 14 days Aging the strontium alloy are usually superior to the calcium alloys and the strength properties of the lead / antimony alloys listed in Table I. reach.

As already mentioned, an alloy according to the invention has the following composition:

Strontium 0.01 to 2.0 wt. 96

Tin 0.1 to 5.0% by weight

Aluminum 0.005 to 0.1 wt. 96

Copper 0 to 0.25 wt. -96 and

Lead rest

The strontium content must not exceed 2% by weight, since larger amounts of strontium lead to inappropriately high liquidus temperatures to lead. With regard to acid accumulators, too, higher percentages of strontium are undesirable because they cause excessive precipitation of intermetallic compounds. This has poor corrosion properties to the rim. Furthermore, higher percentages of strontium lead to increased foam lift-off during the Air activation. Last but not least, the alloy

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become excessively expensive. On the other hand, at least 0.0 1% by weight of strontium is required to give the alloy the desired To give strength.

The upper limit of tin is 5% by weight, since the mechanical behavior no longer improves beyond this upper limit leaves. In addition, there is an increase in the temperatures used in accumulator plate casting Foam lifting. Finally, larger amounts of tin make the alloy inappropriately expensive. Below a tin content of 0.1% by weight, aging curing takes an inordinately long time. Furthermore, the protection against foam detachment is reduced.

Aluminum should be contained in the alloy in an amount of at least 0.005% by weight, since smaller amounts of aluminum do not provide adequate protection against foam lifting. With aluminum amounts of more than 0.1% by weight, no further amounts are achieved Advantages more, it can rather lead to processing difficulties due to the presence of primary aluminum in the alloy.

Copper can accelerate the aging hardening properties be added to the alloy. The upper limit for copper is 0.25% by weight, otherwise aging hardening and the liquidus temperature will be affected.

An alloy according to the invention has the following preferred composition:

0.05 to 0.3 wt% strontium 0.25 to 1.0 wt% tin

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0.01 to 0.1% by weight of aluminum 0.005 to 0.1% by weight of copper and Remainder lead.

The alloys according to the invention show a number of advantages over lead / calcium alloys. The invention Alloys have a very low tendency to foam lifting and excellent compositional stability, so that the crucible analysis must be repeated frequently and a new appointment can be dispensed with. As a rule, they have a higher yield strength and Swelling resistance combined with good ductility. This increases the workability and in particular the Improved vibration resistance under severe operating conditions. The alloys show in a typical way rapid aging hardening, so that panels made from it can be further treated within 16 hours, e.g. with a Paste can be coated. Furthermore, the alloys can typically be used at temperatures lower than than Lead / calcium alloys are cast, which results in the Frequency of mold lining reduced. Waste from the alloys can be remelted directly and used for casting be used by plates or accumulator bars or other parts. An electrochemical corrosion test of the alloys according to the invention shows that they are superior to antimony-containing lead alloys and calcium / lead alloys are equivalent. Finally, alloys according to the invention are particularly suitable for (accumulator) construction or construction with cast-on webs of the type described in US Pat. No. 3,087,005.

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In addition to their usability for parts of acid accumulators, the lead alloys according to the invention are of course suitable also for use in other areas of application.

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Table I J ^

Composition (remainder lead) after 1 h after 24 h after 14 days oo

Sy * Su ** El *** Sy Su El Sy Su El -J

CD

1.24 2.21 21.3 1.30 2.15 16.7 2.78 3.83 15.7

A) Sn Approx Cu As 0.5 0.08 until
to
0.06 0.275 B) Sb Sn 09835 4.75 0.275 O CO
OO

2.00 5.85 31.6 2.78 6.39 29.0 4.50 6.37 15.6

% by weight composition

(Remainder: lead) Sr Sn Al Cu

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Table II El *** after
sy 24 hours
Su El after
sy 14 days
Su - - 2656876 < 13.2 - 1.77 - - - - - El 10.55 after
Sy * 1 h
Su ** 19.0 2.76 3.82 15.2 - 3.45 - 15.2 1.80 - 10.9 3.97 4.54 11.7 - 3.05 - 9.2 1.99 3.44 - 0.74 - - - 3.72 - 7.30 3.04 3.86 28.6 1.37 2.12 14.4 2.76 4.42 8.31 - - 35.4 1.02 1.78 26.2 2.46 4.22 11.00 0.96 1.95 41.0 1.30 2.27 36.8 3.02 4.56 9.39 0.80 1.70 27.3 2.89 3.65 14.0 3.80 4.04 5.10 0.89 1.95 18.6 3.44 4.13 11.5 3.70 4.37 8.65 1.68 2.79 33.6 2.78 3.50 10.4 4.08 3.82 1.65 2.50 22.4 1.49 2.20 12.8 3.47 4.25 1.19 2.40 19.7 1.54 2.33 17.7 3.71 1.02 1.91 23.4 3.07 3.60 7.0 3.50 1.24 1.96 16.4 3.06 3.57 4.7 3.82 1.22 2.38 1.71 2.68

CD CO 00 CO CTi

O CJ7 OO OO

3.05 0.96 1.05 0.94 0.31 0.51 0.94 0.68 0.52 0.31 0.25 0.45 0.5

0.056

0.1

0.025

0.05

0.1

0.075

0.05

0.025

0.025

0.05

0.05

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0.14 0.92 0.1 - 10 continuation Tabel II 0.2 1.14 0.06 0, 10 3.91 4.69 8.92 3.67 0.2 - - O, 10 3.02 - - 4.97 0.2 0.896 0.05 O, 057 - - 1.59 0.2 0.896 0.05 O, - - 4.82 S. 0.2 1.14 0.06 - - - 4.01 OO 4.13 - - 4.90 cn O cn

00 3.80 2.25 4.25 4.49 3.8 ^

oo * Sy = 0.2 $ yield strength in kg / mm ² - *

⁰⁰ ** Su = tensile strength '

*** El β 96-ual elongation at the yield point

Claims (4)

Claims Ί. High strength lead alloy, essentially consisting of the end: 0.01 to 2.0 wt% strontium 0.1 to 5.0 wt% tin 0.005 to 0.1 wt% aluminum, 0.0 to 0.25 wt% copper, and to the rest of the lead. 2. Lead alloy according to claim 1, consisting essentially of: 0.05 to 0.3 part by weight of strontium Ji 0.25 to 1.0 parts by weight-96 tin 0.01 to 0.1 wt -.% Of aluminum from 0.0 to 0.25 wt -.% Of copper and Remainder lead. 709835/0588 3. Lead alloy according to claims 1 or 2, consisting essentially of: 0.05 to 0.3 wt -.% Strontium 0.25 to 1.0 parts by weight-96 tin 0.01 to 0.1 parts by weight of 96 aluminum 0.005 to 0.1 part by weight of copper 96, and the balance lead . 4. Accumulator plate for lead-acid accumulators, made of a lead alloy according to one or more of the preceding claims. 709835/0588