JP4093749B2

JP4093749B2 - Lead-based alloys for lead-acid batteries

Info

Publication number: JP4093749B2
Application number: JP2001352048A
Authority: JP
Inventors: 靖之根兵; 淳古川; 智博平城; 豊森
Original assignee: Toho Zinc Co Ltd; Furukawa Battery Co Ltd
Current assignee: Toho Zinc Co Ltd; Furukawa Battery Co Ltd
Priority date: 2001-11-16
Filing date: 2001-11-16
Publication date: 2008-06-04
Anticipated expiration: 2021-11-16
Also published as: JP2003151563A

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、極板格子に使用したときに優れた格子耐食性を示すとともに、重力鋳造や連続鋳造にも適する鉛蓄電池用鉛基合金に関する。
【０００２】
【従来技術】
従来、公知の鉛蓄電池用Ｐｂ基合金は、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質量％の如く多量に含有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、容量が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質量％、スズが０．６０〜２．００質量％、アルミニウムが０．０１〜０．０３質量％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て公知の鉛蓄電池用Ｐｂ−Ｃａ−Ｓｎ−Ａｌ合金の改良を行ったもので、この従来の合金にＢａとＢｉを含有することにより鉛蓄電池の格子基板に使用したときに、耐食性を示すとともに機械的強度が向上する鉛蓄電池用鉛基合金を得ようとするものである。
【０００７】
【課題を解決するための手段】
この発明は、カルシウムが０．０３〜０．１０質量％、スズが０．６０〜２．００質量％、アルミニウムが０．０１〜０．０３質量％、バリウムが０．００１〜０．０１質量％、ビスマスが０．０５〜０．１２５質量％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、公知な鉛蓄電池用合金にＢａとＢｉを含有したものである。ここで公知な鉛合金とは、Ｃａが０．０４〜０．１０質量％、Ｓｎが０．６０〜２．００質量％、アルミニウムが０．０１〜０．０３質量％で残部が鉛の合金である。上記の本発明の鉛基合金は、耐食性とともに機械的強度が優れているうえに、高温下に長時間曝されても機械的強度の低下が少ないといった特徴がある。
【０００９】
この発明でＢｉを含有するのは耐食性および機械的強度を向上させるためであるが、その含有量を０．０５〜０．１２５質量％に限定した理由は、これが０．０５質量％未満では上記効果が十分でなく、また０．１２５質量％を超えても上記効果の著しい向上がみられないためである。
【００１０】
Ｂａを含有するのはＢｉを含有する目的と同様で耐食性および機械的強度を向上させるためで、その含有量は０．００１〜０．０１質量％である。Ｂａの含有量が０．００１質量％未満では上記効果が十分でなく、また０．０１質量％を超えてもその効果はそれ程でない。
【００１１】
Ｃａを含有するのは機械的強度を向上するためで、その含有量を０．０３〜０．１０質量％とする。Ｃａの含有量が０．０３質量％未満の場合はＣａを含有したことによる効果は少なく、また０．１０質量％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。なお、公知の鉛蓄電池用鉛合金よりＣａ量を少なくしてもＢａおよびＢｉを添加しているために十分な機械的強度が得られた。
【００１２】
Ｓｎを含有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０．６０〜２．００質量％に限定したのは、０．６０質量％未満の場合はその効果が少なく、また２．００質量％を超えた場合は結晶粒が粗大化して粒界腐食が進む。Ａｌの含有は溶湯の酸化によるＣａの損出を防止するためと機械的強度を向上させるためで、その含有量を０．０１〜０．０３質量％とする。これが０．０１質量％未満の場合は効果が少なく、またこれが０．０３質量％を超えた場合はドロスとして析出し易くなる。
【００１３】
【実施例】
実施例１〜８および従来例、比較例
表１に従来例、比較例、本発明実施例の各合金の組成を示した。これらの合金の伸び、耐力（０．２％），クリープおよび耐食性といった機械的特性を測定して鉛蓄電池用基板合金としての適性を評価した。この試験に供したサンプルは厚さ１．５mm、幅１５mmの鋳造材である。この鋳造材を所定の大きさに切断して試験片とした。
【００１４】
【表１】

【００１５】
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った際の結果を図１に、また耐力（０．２％）の結果を図２に示した。図１のサンプルは１００℃−１hrで時効したサンプル、図２は１００℃−１００hrで時効したサンプルである。
【００１６】
図１および図２より明らかなように、本発明の実施例になる鉛蓄電池用鉛基合金は従来例に比較して大幅な伸びの低下と過時効下において０．２％耐力の向上が確認された。そして、この効果はＢｉの含有量が０．０５〜０．１２５質量％の間でみられたが、０．０５質量％未満ではその効果はあまり認められず、また０．１２５質量％を超えてもその効果は顕著にみられなかった。
【００１７】
クリープ試験は１００℃環境下で１６．９Mpa の荷重をかけた状態で行ない、サンプルが破断するまでの時間で評価した。この結果を図３に示した。図３から明らかなように、耐クリープ性についても実施例のものは従来例と比べて明らかに向上している。そして、この効果はＢｉの含有量が０．０５〜０．１２５質量％の間でみられるが、Ｂｉの含有量が０．０５質量％未満ではほとんどその効果はみられず、また０．１２５質量％をこえてもその効果はそれほどでない。
【００１８】
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で評価した。その結果を図４に示した。図４から明らかなように、本発明の実施例の合金は従来例に比較して大幅な腐食の低下がみられるように、Ｂｉの含有が耐食性に大きく関与していると考えられる。しかし、この耐食性の効果は上記の機械的強度の場合と同様にＢｉ含有量が０．０５〜０．１２５質量％の範囲でみられることが分かる。
【００１９】
以上説明したように、公知な鉛蓄電池用Ｐｂ−Ｃａ−Ａｌ合金に、Ｂａを０．００１〜０．０１質量％、またＢｉを０．０５〜０．１２５質量％含有すると、伸びの低下や過時効時の０．２％耐力の向上、高温クリープ性の向上、耐食性の大幅な向上などが図られ、従来の鉛基合金を基板に用いた鉛蓄電池と比べて高温時の格子強度が向上し、その強度不足による破断やグロスを抑制できて、電池の一層の寿命向上が期待できるようになった。なお、各図の凡例中にＡｌの含有量の記載がないが全て０．０２％含有したものである。
【００２０】
【発明の効果】
以上説明したように、この発明の鉛蓄電池用鉛基合金をメインテナンスフリー用鉛蓄電池の極板基板に適用すれば、極板基板の腐食量を著しく抑制し長寿命の鉛蓄電池を得ることや生産性を一層向上させることができるようになる。
【図面の簡単な説明】
【図１】鉛蓄電池用鉛基合金にけるＢｉ含有量／質量 %と伸び／%（１００℃−１hr）の関係を示す線図。
【図２】鉛蓄電池用鉛基合金にけるＢｉ含有量／質量 %と０．２%耐力／Mpa（１００℃−１００hrs）の関係を示す線図。
【図３】鉛蓄電池用鉛基合金にけるＢｉ含有量／質量 %と破断時間／hoursの関係を示す線図。
【図４】鉛蓄電池用鉛基合金にけるＢｉ含有量／質量 %と腐食減量／mg／cm^２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 relates to a lead-base alloy for lead-acid batteries that exhibits excellent grid corrosion resistance when used in an electrode plate grid and is suitable for gravity casting and continuous casting.
[0002]
[Prior art]
Conventionally, known Pb-based alloys for lead-acid batteries have been known to contain Sb in a large amount, such as 4.5 to 8.0 % by mass , 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 above-mentioned Sb promotes the self-discharge of the battery, which not only reduces the capacity, but 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 mass , tin is 0.60 to 2.00 % by mass , aluminum is 0.01 to 0.03 % by mass , 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, especially in automobiles, where the temperature inside the bonnet tends to increase. As a result, further corrosion resistance and mechanical properties of substrate grids under high temperature conditions, particularly positive electrode grids, have become more severe. There is a need for improved strength.
[0006]
[Problems to be solved by the invention]
The present invention is an improvement of a known Pb-Ca-Sn-Al alloy for lead-acid batteries in response to such expectations, and by containing Ba and Bi in this conventional alloy, the lattice substrate of the lead-acid battery It is intended to obtain a lead-based alloy for a lead-acid battery that exhibits corrosion resistance and improved mechanical strength when used in a battery.
[0007]
[Means for Solving the Problems]
In this invention, calcium is 0.03 to 0.10 % by mass , tin is 0.60 to 2.00 % by mass , aluminum is 0.01 to 0.03 % by mass , and barium is 0.001 to 0.01 % by mass. % , Bismuth is 0.05 to 0.125% by mass , and the remainder is a lead-based alloy for a lead-acid battery made of lead.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, Ba and Bi are contained in a known lead-acid battery alloy. Here, known lead alloys are alloys in which Ca is 0.04 to 0.10 % by mass , Sn is 0.60 to 2.00 % by mass , aluminum is 0.01 to 0.03 % by mass , and the balance is lead. It is. The lead-based alloy of the present invention has the characteristics that it has excellent mechanical strength as well as corrosion resistance, and has a small decrease in mechanical strength even when exposed to a high temperature for a long time.
[0009]
The reason why Bi is contained in this invention is to improve the corrosion resistance and mechanical strength, but the reason for limiting the content to 0.05 to 0.125% by mass is the above when the content is less than 0.05 % by mass. This is because the effect is not sufficient, and even if it exceeds 0.125% by mass, the above effect is not significantly improved.
[0010]
The reason for containing Ba is to improve corrosion resistance and mechanical strength in the same manner as the purpose of containing Bi, and its content is 0.001 to 0.01% by mass . If the content of Ba is less than 0.001 % by mass , the above effect is not sufficient, and if it exceeds 0.01 % by mass, the effect is not so great.
[0011]
Ca is contained to improve mechanical strength, and its content is set to 0.03 to 0.10 % by mass . When the Ca content is less than 0.03 % by mass , the effect of containing Ca is small, and even when it exceeds 0.10 % by mass, it is difficult to obtain a good casting at a low casting temperature. When the casting temperature is raised, oxidation occurs and the amount of Ca loss increases. In addition, sufficient mechanical strength was obtained because Ba and Bi were added even if the amount of Ca was less than that of known lead alloys for lead-acid batteries.
[0012]
Sn is contained in order to improve the flowability and mechanical strength of the alloy, but the compounding amount is limited to 0.60 to 2.00 % by mass when it is less than 0.60 % by mass. Is less effective, and when it exceeds 2.00 % by mass, the crystal grains become coarse and intergranular corrosion proceeds. The content of Al is to prevent loss of Ca due to oxidation of the molten metal and to improve mechanical strength, and its content is set to 0.01 to 0.03 mass% . When this is less than 0.01 % by mass, the effect is small, and when it exceeds 0.03 % by mass , it tends to precipitate as dross.
[0013]
【Example】
Examples 1 to 8 and conventional examples and comparative examples Table 1 shows the compositions of the alloys of the conventional examples, comparative examples, and inventive examples. The mechanical properties such as elongation, yield strength (0.2%), creep and corrosion resistance of these alloys were measured to evaluate their suitability as lead alloy alloys for lead-acid batteries. The sample used for this test is a cast material having a thickness of 1.5 mm and a width of 15 mm. The cast material was cut into a predetermined size to obtain a test piece.
[0014]
[Table 1]

[0015]
FIG. 1 shows the results when the test pieces were subjected to a tensile test at room temperature at a strain rate of 1.7 × 10 ⁻³ / sec, and FIG. 2 shows the results of proof stress (0.2%). The sample in FIG. 1 is a sample aged at 100 ° C.-1 hr, and FIG. 2 is a sample aged at 100 ° C.-100 hr.
[0016]
As is clear from FIG. 1 and FIG. 2, the lead-based alloy for lead-acid batteries according to the examples of the present invention is confirmed to have a significant decrease in elongation and an improvement in 0.2% yield strength under overaging compared to the conventional examples. It was done. This effect was observed when the Bi content was 0.05 to 0.125% by mass , but less than 0.05% by mass, the effect was not recognized much, and exceeded 0.125% by mass. However, the effect was not noticeable.
[0017]
The creep test was performed in a state where a load of 16.9 MPa was applied in an environment of 100 ° C., and the time until the sample broke was evaluated. The results are shown in FIG . As is apparent from FIG. 3, the creep resistance of the example is clearly improved compared to the conventional example. And this effect is the Bi content is seen between 0.05 to 0.125 wt%, the content of Bi is little that effect is not observed is less than 0.05 wt%, also 0.125 The effect is not so much even if it exceeds mass% .
[0018]
The corrosion resistance was evaluated by measuring the weight loss per unit area of the sample after anodic oxidation in dilute sulfuric acid having a specific gravity of 1.280 (20 ° C.) and a temperature of 60 ° C. for 720 hours. The results are shown in FIG. As is apparent from FIG. 4, the alloy of the example of the present invention is considered to be greatly related to the corrosion resistance, as Bi is significantly reduced as compared with the conventional example. However, the effect of the corrosion resistance it can be seen that the Bi content as in the mechanical strength of the above can be seen in the range of 0.05 to 0.1 25% by weight.
[0019]
As described above, when a known Pb—Ca—Al alloy for lead-acid batteries contains 0.001 to 0.01 mass% Ba and 0.05 to 0.125 mass% Bi, Improved 0.2% proof stress when over-aged, improved high-temperature creep resistance, and drastically improved corrosion resistance, and improved lattice strength at high temperatures compared to conventional lead-acid batteries using lead-based alloys as substrates In addition, breakage and gloss due to insufficient strength can be suppressed, and further improvement in battery life can be expected. In addition, although there is no description of Al content in the legend of each figure, all are contained 0.02%.
[0020]
【The invention's effect】
As explained above, if 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 amount of corrosion of the electrode plate substrate is remarkably suppressed and a long-life lead-acid battery can be obtained or produced. The performance can be further improved.
[Brief description of the drawings]
FIG. 1 is a diagram showing the relationship between Bi content / mass % and elongation /% (100 ° C.-1 hr) in a lead-based alloy for a lead storage battery.
FIG. 2 is a diagram showing the relationship between Bi content / mass % and 0.2% proof stress / Mpa (100 ° C.-100 hrs) in a lead-based alloy for a lead storage battery.
FIG. 3 is a diagram showing the relationship between Bi content / mass % and rupture time / hours in a lead-based alloy for a lead storage battery.
FIG. 4 is a diagram showing the relationship between Bi content / mass % and corrosion weight loss / mg / cm ^{2 in} a lead-based alloy for a lead storage battery.

Claims

Calcium is 0.03-0.10 mass% , tin is 0.60-2.00 mass% , aluminum is 0.01-0.03 mass% , barium is 0.001-0.01 mass% , bismuth is A lead-based alloy for a lead-acid battery having a balance of 0.05 to 0.125% by mass , the balance being lead.