JP4502346B2

JP4502346B2 - Lead-based alloys for lead-acid batteries

Info

Publication number: JP4502346B2
Application number: JP2000324432A
Authority: JP
Inventors: 靖之根兵; 淳古川; 豊森; 智博平城
Original assignee: Toho Zinc Co Ltd; Furukawa Battery Co Ltd
Current assignee: Toho Zinc Co Ltd; Furukawa Battery Co Ltd
Priority date: 2000-10-24
Filing date: 2000-10-24
Publication date: 2010-07-14
Anticipated expiration: 2020-10-24
Also published as: JP2002134116A

Description

【０００１】
【発明の属する技術分野】
この発明は鉛蓄電池用鉛基合金に関し、特に合金の結晶粒を微細化してその耐食性と機械的強度を向上した鉛蓄電池用鉛基合金に関する。
【０００２】
【従来の技術】
従来、公知の鉛蓄電池用Ｐｂ合金は、主として機械的強度を重視しているために、Ｓｂを４．５〜８．０重量％の如く多量に配合したものが知られている。
【０００３】
しかしながら、この合金を鉛蓄電池の極板用基板に適用した場合は、上記Ｓｂが原因となって電池の自己放電を促進し、容量を低下するのみならず、充電完了状態や過充電状態において激しい水分解反応が生じ水の補給を必要とするものであった。この水の補給は、現在の鉛蓄電池の主流をなすメンテナンスフリー電池の極板用基板に対し、全く逆の作用をもたらすものである。
【０００４】
従って、Ｓｂを全く含有しない鉛基合金として、カルシウムが０．０４〜０．１０重量％、スズが０．８０〜２．００重量％、アルミニウムが０．０１〜０．０３重量％で残部が鉛である鉛蓄電池用基板合金が提案されている。
【０００５】
しかしながら、最近、特に自動車用ではボンネット内の温度が高温化する傾向にあるなど鉛蓄電池を取巻く環境はさらに厳しくなり、それに伴い高温条件下での基板格子、特に正極格子の更なる耐食性および機械的強度の向上が求められている。
【０００６】
【発明が解決しようとする課題】
この発明は、このような期待に応えるため、公知の鉛蓄電池用Ｐｂ−Ｃａ−Ｓｎ−Ａｌ合金に銀およびバリウムを添加することで、鋳造性を損なうことなく、耐食性および機械的強度の優れた鉛基合金を得ようとするものである。
【０００７】
【発明が解決するための手段】
この発明は、カルシウムが０．０４〜０．１０重量％、スズが０．８０〜２．
００重量％、アルミニウムが０．０１〜０．０３重量％、銀が０．０５〜０．１０重量％、バリウムが０．００５〜０．０１５重量％で、残部が鉛よりなる鉛蓄電池用鉛基合金である。
【０００８】
【発明の実施の形態】
この発明は、公知な鉛基合金に対してＡｇおよびＢａを添加するものであり、ＡｇおよびＢａを添加することによりＡｇおよびＢａが無添加の場合と比較して鋳造性を損なうこと無く、耐食性および機械的強度が向上するものである。
【０００９】
この発明の鉛蓄電池用鉛基合金は、カルシウムが０．０４〜０．１０重量％、
スズが０．８０〜２．００重量％、アルミニウムが０．０１〜０．０３重量％、
銀が０．０１〜０．１０重量％、バリウムが０．００５〜０．０１５重量％、残部が鉛である。
【００１０】
Ａｇの配合量を０．０５〜０．１０重量％に限定した理由は、これが０．０５重量％未満では上記の耐食性および機械的強度向上の効果が薄く、また０．１０重量％を超えても上記効果が顕著に向上せず、経済上この範囲に留めることが好ましい。同様に、Ｂａの配合量を０．００５〜０．０１５重量％に限定した理由も、これが０．００５重量％未満では上記効果が薄く、また０．０１５重量％を超えても上記効果が顕著に向上しないためである。
【００１１】
この発明においてＣａを添加するのは機械的強度を向上させるためであるが、その配合量を０．０４〜０．１０重量％に限定した理由は０．０４重量％未満の場合にはその効果が薄く、また０．１０重量％を超えても低い鋳造温度で良好な鋳造品を得ることが難しく、逆に鋳造温度を高くすると酸化してＣａの損失量が多くなるためである
Ｓｎを添加するのは、合金の湯流れ性や機械的強度を向上させるためであるが、その配合量を０．８０〜２．００重量％に限定した理由は、０．８０重量％未満の場合にはその効果が薄く、２．００重量％を超えた場合にはＳｎ量の増加とともに耐食性が劣り好ましくない。
【００１２】
Ａｌを添加する理由は、溶湯の酸化によるＣａの損失を防止しするためであるが、その配合量を０．０１〜０．０３重量％に限定した理由は、０．０１重量％未満の場合にはその効果が薄く、０．０３重量％を超えた場合には上記の効果が顕著にあらわれないためである。
【００１３】
この発明における鉛基合金は上記の配合としたことによって、前記の公知な鉛基合金に対して鋳造性をほとんど損なわないため重力鋳造や連続鋳造に適している。
【００１４】
即ち、公知な鉛基合金にＡｇを添加することにより、耐食性、機械的強度に優れた基板格子を用いた鉛蓄電池を得ることができる。また、Ａｇはその添加によりＳｎ分子の合金表面への拡散を抑制する作用があるので、合金表面でのＳｎ酸化による腐食を防止するとともに、合金の結晶粒を微細化させるため耐食性および機械的強度を向上させることが可能である。
【００１５】
【実施例】
以下にこの発明の実施例を示す。
【００１６】
表１に示す組成になる本発明合金を使用して、耐食性、耐力（０．２％）や伸びといった機械的強度および鋳造性を測定して、その鉛蓄電池用基板合金としての適性を評価した。耐食性や機械的強度を評価するのに使用した試料は厚さ１．５ｍｍ、幅１５ｍｍの鋳造材である。この鋳造材を所望の大きさに切断して種々の特性評価の試験片とした。
【００１７】
作成した試験片を歪み速度１．７×１０^−３／秒で室温において引張試験を行
ない、耐力（０．２％）と伸びを測定した。
また、鋳造性を評価するために一定温度条件下で複雑な樹枝状の鋳型を使用し、そこに湯を流し完全に湯が回り込んだものを１００として指数で評価した。これらの結果を第１表に併記した。実際の基板鋳造においては鋳造指数が９３以上であれば鋳造性に問題はない。また、公知の鉛蓄電池用Ｐｂ−Ｃａ−Ｓｎ−Ａｌ合金の改良という意味で０．２％耐力は４８ＭＰａ以上、伸びは５．０％以下であることが望ましいと考えた。
【００１８】
【表１】

【００１９】
表１より明らかなように、本発明鉛蓄電池用鉛基合金によれば公知の鉛蓄電池用Ｐｂ−Ｃａ−Ｓｎ−Ａｌ合金に、ＡｇおよびＢａを本発明で規定した範囲で添加することにより、従来の鉛基合金に比して０．２％耐力の向上および伸びの著しい低下が確認された。
【００２０】
また、規定量のＡｇとＢａを配合させても鋳造指数が９３を下回ることがないので鋳造性に問題の無いことが分かった。ただし、Ｂａを規定量超えて配合すると鋳造性が大幅に低下する。
【００２１】
さらに、Ａｇのみを添加したものに比べＢａを添加したものは伸びが大きく、０．２％耐力についてはＢａのみを添加したものに比べＡｇを添加したものは逆に低い値を示すが、ＡｇとＢａ両方を規定量配合すると伸びを低下させるとともに、０．２％耐力を向上させることができる。
【００２２】
耐食性は、比重１．２８０（２０℃）、温度６０℃の希硫酸中で７２０時間陽極酸化させた後に試料の単位面積当たりの腐食減量を測定することにより評価し、その結果を第１図にＡｇ含有量と腐食減量の関係、第２図にＢａ含有量と腐食減量の関係、第３図にＡｇ及びＢａ含有量と腐食減量の関係として示している。
【００２３】
第１図から明らかなように公知の鉛蓄電池用Ｐｂ−Ｃａ−Ｓｎ−Ａｌ合金にＡｇを規定量含有することにより腐食減量を大幅に低下させることができるが、規定量を超えても大幅な腐食減量の低下は望めない。
【００２４】
また、第２図からＢａも規定量を含有すると腐食減量を低下させることができるが、０．０１５重量％を超えると効果が極めて薄くなり、過剰に含有すると逆に悪化させる。
【００２５】
また、第３図よりＡｇのみを含有させたものより、Ｂａを規定量配合させたもののほうが腐食減量を低下させることができる。ただし、規定量を超えてＢａを含有させるとＡｇのみを配合させたものより耐食性が劣る。
【００２６】
また、Ａｇの含有量を０．１０重量％から０．１５重量％に増加させても０．２％耐力の向上および伸びの低下がほとんどないだけでなく、耐食性の向上も見られないためコストを上げるだけであまり好ましくない。
【００２７】
以上のように、公知の鉛蓄電池用Ｐｂ−Ｃａ−Ｓｎ−Ａｌ合金に銀の含有量を０．０５〜０．１０重量％、バリウムの含有量を０．００５〜０．０１５重量％とした本発明合金は鋳造性が問題の無いレベルに維持されているので連続鋳造や重力鋳造に適している。また、伸びの低下や０．２％耐力の向上、さらには腐食減量の大幅な低減により、従来の鉛基合金を基板に用いた鉛蓄電池と比して更なる寿命向上が期待できる。
【００２８】
【発明の効果】
以上詳述したように、本発明の鉛蓄電池用鉛基合金をメンテナンスフリー用鉛蓄電池の極板基板に適用すれば、基板の腐食量を著しく抑制し長寿命の鉛蓄電池を得るなど工業上有益である。
【図面の簡単な説明】
【図１】鉛蓄電池用鉛基合金にけるＡｇ含有量と腐食減量との関係を示す線図。
【図２】鉛蓄電池用鉛基合金にけるＢａ含有量と腐食減量との関係を示す線図。
【図３】鉛蓄電池用鉛基合金にけるＡｇおよびＢａ含有量と腐食減量との関係を示す線図。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lead-base alloy for lead-acid batteries, and more particularly to a lead-base alloy for lead-acid batteries in which the crystal grains of the alloy are refined to improve the corrosion resistance and mechanical strength.
[0002]
[Prior art]
Conventionally, known Pb alloys for lead-acid batteries have been known to contain a large amount of Sb such as 4.5 to 8.0% by weight because the mechanical strength is mainly emphasized.
[0003]
However, when this alloy is applied to an electrode plate substrate for a lead-acid battery, the Sb promotes the self-discharge of the battery and reduces the capacity, and it is severe in a fully charged or overcharged state. A water splitting reaction occurred, requiring water replenishment. This replenishment of water has a completely opposite effect on the substrate for electrode plates of maintenance-free batteries, which is the mainstream of current lead-acid batteries.
[0004]
Therefore, as a lead-based alloy containing no Sb, calcium is 0.04 to 0.10% by weight, tin is 0.80 to 2.00% by weight, aluminum is 0.01 to 0.03% by weight, and the balance is A lead-acid battery substrate alloy that is lead has been proposed.
[0005]
Recently, however, the environment surrounding lead-acid batteries has become more severe, such as in automobiles, where the temperature inside the hood tends to increase. As a result, further corrosion resistance and mechanical properties of substrate grids, particularly positive grids, under high temperature conditions have become more severe. There is a need for improved strength.
[0006]
[Problems to be solved by the invention]
In order to meet this expectation, the present invention has excellent corrosion resistance and mechanical strength by adding silver and barium to a known Pb-Ca-Sn-Al alloy for lead-acid batteries without impairing castability. It is intended to obtain a lead-based alloy.
[0007]
[Means for Solving the Invention]
In the present invention, calcium is 0.04 to 0.10% by weight, and tin is 0.80 to 2.
Lead for lead-acid batteries consisting of 00% by weight, aluminum 0.01-0.03% by weight, silver 0.05-0.10% by weight , barium 0.005-0.015% by weight , the balance being lead It is a base alloy.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, Ag and Ba are added to a known lead-based alloy. By adding Ag and Ba, the corrosion resistance is not deteriorated as compared with the case where Ag and Ba are not added. In addition, the mechanical strength is improved.
[0009]
The lead-based alloy for a lead storage battery according to the present invention has a calcium content of 0.04 to 0.10% by weight,
0.80 to 2.00% by weight of tin, 0.01 to 0.03% by weight of aluminum,
Silver is 0.01 to 0.10% by weight, barium is 0.005 to 0.015% by weight , and the balance is lead.
[0010]
The reason why the amount of Ag is limited to 0.05 to 0.10% by weight is that if the amount is less than 0.05% by weight , the above-mentioned effects of improving the corrosion resistance and mechanical strength are small, and the amount exceeds 0.10% by weight. However, the above effect is not remarkably improved, and it is preferable to keep within this range from an economic viewpoint. Similarly, the reason why the amount of Ba is limited to 0.005 to 0.015% by weight is that the above effect is weak when the amount is less than 0.005 % by weight, and the above effect is remarkable even when the amount exceeds 0.015% by weight. It is because it does not improve.
[0011]
In this invention, Ca is added to improve the mechanical strength, but the reason for limiting the blending amount to 0.04 to 0.10% by weight is the effect when it is less than 0.04% by weight. Sn is added because it is difficult to obtain a good cast product at a low casting temperature even if it is thin and exceeds 0.10% by weight, and conversely, if the casting temperature is raised, it is oxidized and the loss of Ca increases. The reason for this is to improve the molten metal flowability and mechanical strength of the alloy, but the reason for limiting the blending amount to 0.80 to 2.00% by weight is less than 0.80% by weight. The effect is thin, and when it exceeds 2.00% by weight, the corrosion resistance is inferior with an increase in Sn content, which is not preferable.
[0012]
The reason for adding Al is to prevent loss of Ca due to oxidation of the molten metal, but the reason for limiting the blending amount to 0.01 to 0.03% by weight is less than 0.01% by weight. This is because the effect is thin, and when the amount exceeds 0.03% by weight, the above effect does not appear remarkably.
[0013]
The lead-based alloy in the present invention is suitable for gravity casting and continuous casting because it has the above-mentioned composition and hardly impairs castability with respect to the known lead-based alloy.
[0014]
That is, by adding Ag to a known lead-based alloy, a lead storage battery using a substrate grid having excellent corrosion resistance and mechanical strength can be obtained. In addition, Ag has the effect of suppressing the diffusion of Sn molecules to the alloy surface by its addition, so that corrosion due to Sn oxidation on the alloy surface is prevented and corrosion resistance and mechanical strength are used to refine the crystal grains of the alloy. It is possible to improve.
[0015]
【Example】
Examples of the present invention will be described below.
[0016]
Using the alloy of the present invention having the composition shown in Table 1, the mechanical strength such as corrosion resistance, proof stress (0.2%) and elongation, and castability were measured, and its suitability as a lead storage battery substrate alloy was evaluated. . The sample used for evaluating corrosion resistance and mechanical strength is a cast material having a thickness of 1.5 mm and a width of 15 mm. The cast material was cut into a desired size to obtain test pieces for various characteristics evaluation.
[0017]
The prepared specimen was subjected to a tensile test at room temperature at a strain rate of 1.7 × 10 ⁻³ / sec, and the yield strength (0.2%) and elongation were measured.
In addition, in order to evaluate the castability, a complex dendritic mold was used under a constant temperature condition, and hot water was poured into the mold, and 100 was evaluated as an index. These results are also shown in Table 1. In actual substrate casting, if the casting index is 93 or more, there is no problem in castability. In addition, in terms of improving a known Pb—Ca—Sn—Al alloy for lead-acid batteries, it was desirable that the 0.2% proof stress is 48 MPa or more and the elongation is 5.0% or less.
[0018]
[Table 1]

[0019]
As is clear from Table 1, according to the lead-based alloy for lead-acid batteries of the present invention, by adding Ag and Ba to the known Pb-Ca-Sn-Al alloy for lead-acid batteries in the range specified in the present invention, It was confirmed that the yield strength was improved by 0.2% and the elongation was significantly reduced as compared with conventional lead-based alloys.
[0020]
It was also found that there was no problem in castability because the casting index did not fall below 93 even when the prescribed amounts of Ag and Ba were blended. However, when Ba is blended in excess of the specified amount, the castability is significantly lowered.
[0021]
Furthermore, the addition of Ba is larger than the addition of only Ag, and the 0.2% proof stress of the addition of Ag is lower than that of the addition of Ba. When a prescribed amount of both Ba and Ba is blended, the elongation is lowered and the 0.2% proof stress can be improved.
[0022]
Corrosion resistance was evaluated by measuring the weight loss per unit area of the sample after anodizing in dilute sulfuric acid at a specific gravity of 1.280 (20 ° C.) and a temperature of 60 ° C. for 720 hours, and the results are shown in FIG. The relationship between Ag content and corrosion weight loss, FIG. 2 shows the relationship between Ba content and corrosion weight loss, and FIG. 3 shows the relationship between Ag and Ba content and corrosion weight loss.
[0023]
As is clear from FIG. 1, the corrosion weight loss can be greatly reduced by containing a specified amount of Ag in a known lead-battery Pb-Ca-Sn-Al alloy. Decrease in corrosion weight loss cannot be expected.
[0024]
Further, from FIG. 2, Ba also can reduce the corrosion weight loss if it contains the specified amount, but if it exceeds 0.015% by weight, the effect becomes extremely thin, and if it contains excessively, it worsens conversely.
[0025]
Further, as shown in FIG. 3, corrosion weight loss can be reduced by adding a prescribed amount of Ba rather than containing only Ag. However, when Ba is contained exceeding the specified amount, the corrosion resistance is inferior to that in which only Ag is blended.
[0026]
Further, increasing the Ag content from 0.10% by weight to 0.15% by weight not only improves the 0.2% proof stress and decreases the elongation, but also shows no improvement in corrosion resistance. Just raising the value is not very desirable.
[0027]
As described above, the known Pb-Ca-Sn-Al alloy for lead-acid batteries has a silver content of 0.05 to 0.10 wt% and a barium content of 0.005 to 0.015 wt%. The alloy of the present invention is suitable for continuous casting and gravity casting because its castability is maintained at a level where there is no problem. In addition, due to a decrease in elongation, an improvement in 0.2% proof stress, and a significant reduction in corrosion weight loss, a further improvement in life can be expected as compared with a lead storage battery using a conventional lead-based alloy as a substrate.
[0028]
【The invention's effect】
As described in detail above, when the lead-based alloy for lead-acid batteries of the present invention is applied to the electrode plate substrate of a maintenance-free lead-acid battery, the corrosion amount of the substrate is remarkably suppressed and a long-life lead-acid battery is obtained, which is industrially beneficial. It is.
[Brief description of the drawings]
FIG. 1 is a diagram showing the relationship between Ag content and corrosion weight loss in lead-based alloys for lead-acid batteries.
FIG. 2 is a diagram showing the relationship between Ba content and corrosion weight loss in a lead-based battery lead-based alloy.
FIG. 3 is a diagram showing the relationship between Ag and Ba content and corrosion weight loss in a lead-base battery lead-acid alloy.

Claims

0.04 to 0.10% by weight of calcium, 0.80 to 2.00% by weight of tin, 0.01 to 0.03% by weight of aluminum, 0.050 to 0.10% by weight of silver , and barium A lead-based alloy for lead-acid batteries, 0.005 to 0.015% by weight , the balance being lead.