JPH0150065B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to lead-acid batteries, and is directed to electrode members such as poles and grids constituting the lead-acid batteries.

Although lead-acid batteries are highly reliable products that can be said to be technically complete, one problem is that they are heavy. The reason for this is primarily that the electrode member is made of a lead alloy, which is a metal with a high specific gravity, and a sulfuric acid solution, which is a liquid with a high specific gravity. Also,
Although lead alloys have excellent corrosion resistance and good corrosion resistance in sulfuric acid solutions, their disadvantage is that they have relatively low strength. As far as corrosion resistance is concerned, pure lead is the best, but because of this strength problem, lead-antimony alloys containing antimony are exclusively used.
Even so, its tensile strength is only about 5 kg/mm ² at most. On the other hand, when large lead-acid batteries are installed and moved, large stress may be applied to their output terminals, and this and the low strength of lead alloys have led to failures.

As a countermeasure against low strength, attempts have already been made to create a composite structure of the output terminal, for example, by coating the surface of the copper core with a lead alloy. However, since copper has almost no solubility in lead, the composite boundary does not necessarily have an electrically or chemically stable metal bonding layer.
Therein lies the problem of instability in the reliability of product performance.

That is, since it is a lead-acid battery, it is desirable that the core metal in the composite structure has high conductivity, and in that sense, in addition to the above-mentioned copper or copper alloy, aluminum and aluminum alloy can be used. Even in pure metal form, these strengths far exceed those of lead alloys, and the use of alloys further increases the guarantee of strength. However, copper shows almost no solubility for lead, and although aluminum has some solubility for lead, it is difficult to create a sufficient diffusion layer through so-called casting treatment to form a metallic bond at the composite boundary. do not have.

The object of the present invention is to make the boundary layer in this composite structure a stable metal bonding layer, thereby achieving higher strength and further weight reduction.

In the present invention, as a means to solve these problems, the first
As shown in Figure 0, the thickness of the metal bonded to the surface of the core metals 3 and 5 by the intermediate layer alloy bath prepared in advance.
It is characterized in that an intermediate alloy layer of about 10 to 200 μm is formed (8), and a lead or lead alloy layer is further formed (9) thereon to be metallically bonded to the intermediate alloy layer. The reason why the intermediate layer thickness is not 200μm or more is that if it is thicker, there will be problems such as electrical resistance changes.
This is because if it is less than m, the bonding may sometimes be insufficient. Furthermore, the intermediate layer is formed using the intermediate layer alloy bath at a temperature in a coagulable state.

Here, the quasi-liquid state is specified as a temperature condition in which solid-liquid coexistence range is below the liquidus temperature and above the solidus temperature in the phase diagram of the alloy system. In addition, in this solid-liquid coexistence range, it is generally accepted empirically that fluidity rapidly loses when the solid phase ratio exceeds 30 wt%, but even when the solid phase ratio exceeds 30 wt%, strong stirring of the liquid When given action, fluidity is restored again,
It is known that a so-called pseudo-liquid state occurs.
At this temperature, diffusion proceeds slowly, making it easy to control the thickness of the diffusion layer. In addition, even if materials such as lead-copper alloys exhibit almost no solubility with each other at room temperature, by utilizing the quasi-liquid state of lead-copper alloys, a thin coating layer can be formed as an intermediate layer on the surface of the copper core metal. It is possible.

To explain with a specific example, first, when copper or a copper alloy is used as the core metal, a lead-copper alloy bath containing 30 to 80 wt% of lead is prepared. The Pb-Cu alloy phase diagram is the first
As shown in the figure, it has a monocrystalline reaction, and has a wide range of solid-liquid coexistence phases over about 600°C, with a liquidus line of 990°C and a solidus line of 327°C in the above composition range.

Although the fluidity rapidly decreases from around 800°C, the fluidity is restored by stirring and the quasi-liquid property is maintained up to around 700°C. If a copper or copper alloy mandrel is inserted into the bath in this state, an intermediate layer with a concentration gradient of copper and lead will automatically be formed on its surface, and when lead or lead alloy is poured in the final process. ,
Metallic bonding occurs in the boundary layer.

Even when aluminum is used as the mandrel, an alloy system having a monotectic reaction can be used, and in the present invention, a Pb-2n alloy system is specified. The phase diagram is shown in FIG. 2, and here, too, an intermediate layer is formed under a pseudo-liquid state by stirring the liquid in the solid-liquid coexistence temperature range of about 419°C to 327°C. However, in this case, the zinc concentration in the lead-zinc alloy is preferably 10 to 5 wt%. The reason for this is that the solubility of bad lead in aluminum is extremely high as shown in Figure 3, and the diffusion rate is also high. Therefore, when the zinc concentration is high, the aluminum core metal melts even at relatively low temperatures due to contact with the zinc melt. This is because it becomes difficult to manage the formation of the intermediate layer.

When using an aluminum core, it is also possible to use an alloy system that does not have a monotectic reaction. That is, the present invention focuses on zinc and tin, which are elements that easily form alloy layers with aluminum, lead, and their alloys, and specifies a Zn-Sn alloy as an intermediate alloy. Its phase diagram is shown in Figure 4, and it has been experimentally confirmed that the solid-liquid coexistence region is wide in terms of tin content, and that it is easy to combine with aluminum or its alloys in a quasi-liquid state. % is used,
If the solution is stirred at 350 to 300°C to give it pseudo-liquid properties and the liquid is brought into contact with a core metal made of aluminum or its alloy, the core metal will not be severely damaged by melting and the outermost layer of lead or lead will melt. An intermediate layer that easily bonds with the alloy layer can be formed on its surface. For reference, the Pb-Sn alloy phase diagram is shown in Figure 5.
Since lead and tin have mutual solubility, the presence of this intermediate layer facilitates metal bonding with the outermost lead or lead alloy layer.

FIG. 6 schematically shows the means for obtaining the above-mentioned pseudo-liquid state and the method of forming an intermediate layer on the core metal. 3 itself is rotated and stirred, and this is easy to apply to the production of pole columns. Method b is a method in which an iron stirring rod 4 is placed separately in the metal bath 2 in the crucible 1 for stirring, and then the pole mandrels 3 and the grid mandrels 5 are immersed therein. Although the heating furnace is not shown in the figure, the alloy bath 2 and the crucible 1 that is its container are shown.
is installed in a heating furnace controlled at a target temperature.
In addition, the metal connective tissue can be verified by observation using a metallurgical microscope.

Example 1 After melting an alloy consisting of 60 wt% Pb and 40 wt% Cu at 1100°C, the temperature was lowered to 850°C in the solid-liquid coexistence region and heated for 1 minute with a pure copper pole guard as shown in Figure 6a. The mixture was stirred to create a quasi-liquid state, and a Pb-Cu alloy intermediate layer was formed and adhered to the surface of the pole guard metal. FIG. 7 shows the intermediate layer thus obtained and a microscopic structure diagram (X100) of the boundary portion when it is cast with a Pb-Sb alloy. In the figure, 3a is
6 is a Pb--Cu alloy intermediate layer formed on the pole-column guard 3a of Cu, and 7 is the outermost layer of Pb--Sb alloy.

Example 2 After melting an alloy consisting of 90wt% Pb and 10wt% Zn, the temperature was lowered to 380°C in the solid-liquid coexistence region to form pure aluminum.
Using an Al pole guard, the material was stirred for 1 minute in the same manner as in Example 1 to obtain a quasi-liquid state, and a Pb--Zn alloy intermediate layer was formed and adhered to the surface of the pole guard. 8th
The figure shows the intermediate layer obtained in this way and its
The microscopic structure of the boundary area when cast with Pb-Sb alloy is shown. In the figure, 3b is an Al pole pole mandrel, and 6' is a Pb-shaped pole mandrel formed on the pole pole mandrel 3b.
Zn alloy intermediate layer.

Example 3 After melting an alloy consisting of 50 wt% Zn and 50 wt% Sn, the temperature was lowered to 320°C, which is the solid-liquid coexistence region, and then
Stir with stirring rod 4 as shown in Figure b to obtain a quasi-liquid state, and immerse pure aluminum poles and lattice guards for 1 minute to form a Zn-Sn alloy intermediate layer on their surfaces. I let it happen. After this, Pb
-A bonded boundary layer as shown in FIG. 9 was obtained by casting with Sb alloy. In the figure, 5a is an Al lattice mandrel, 6'' is a pole column, and a Zn--Sn alloy intermediate layer formed on the lattice mandrels 3b and 5a.

It has been found that the pole columns and grids manufactured in this manner have improved strength and weight compared to conventional cast Pb-Sb alloys, are lighter in weight, and have good corrosion resistance. Also, in manufacturing, it has become easier to form a stable thin intermediate layer, and therefore the overall manufacturing has become easier.

As explained above, according to the present invention, a lightweight electrode member with sufficient strength and corrosion resistance can be obtained, and the manufacturing method thereof is simple, so that it has great industrial value.

[Brief explanation of drawings]

Figures 1 to 5 are alloy phase diagrams for explaining the main points of the present invention. Figure 1 is a Pb-Cu alloy phase diagram, Figure 2 is a Pb-Zn alloy phase diagram, and Figure 3 is a Pb-Zn alloy phase diagram. Al
-Zn alloy system phase diagram, FIG. 4 is a Zn-Sn alloy system phase diagram, and FIG. 5 is a Pb-Sn alloy system phase diagram. 6th
The figure is a schematic diagram showing a method of stirring an intermediate layer alloy bath in a solid-liquid coexistence region to make it pseudo-liquid, and attaching it to the surface of a core metal as an intermediate layer, in which a is a schematic diagram of an embodiment of the present invention. b indicates a state in which it is stirred by itself, and b indicates a state in which it is stirred with a stirring rod. Figure 7 is a boundary microstructure diagram when a Pb-Cu alloy is used as the intermediate layer according to this example, and Figure 8 is a Pb-Cu alloy as the intermediate layer.
- A microscopic diagram of the boundary area when using a Zn alloy, Figure 9 is a microscopic diagram of the boundary area when a Zn-Sn alloy is used as the intermediate layer, and Figure 10 is a schematic process flow diagram of the present invention. . 2 is a metal bath, 3 is a pole guard, 3a is a Cu pole guard, 3b is an Al pole guard, 4 is a stirring rod,
5 is a grid guard, 5a is an Al grid guard, 6 is a grid guard.
Pb-Cu alloy intermediate layer, 6' is Pb-Zn alloy intermediate layer,
6'' is a Zn-Sn alloy intermediate layer, 7 is a Pb-Sb alloy outermost layer, 8 is an intermediate alloy layer forming process, and 9 is a lead or lead alloy layer forming process.

Claims (1)

[Claims] 1 Core metals 3 and 5, and an intermediate alloy layer 6 on the outer layer thereof.
6', 6'', and further has a lead or lead alloy layer 7 on the outer layer thereof, wherein the core metals 3, 5 are made of copper or aluminum or their respective alloys, and the intermediate alloy layer 6, 6', 6'' are the mandrels 3,
5 and the lead or lead alloy layer 7. 2. By immersing the core metals 3, 5 in a lead-copper alloy bath 2, an intermediate alloy layer 6 is formed on the outer layer, and the core metals 3, 5 are made of copper or a copper alloy, and the lead metal alloys 3, 5 are made of copper or a copper alloy. - The copper alloy bath 2 contains 30 to 80 w% of lead and is in a quasi-liquid state, and the intermediate alloy layer 6
has a thickness of 10 to 200 μm, and then a lead or lead alloy layer 7 is formed on the outer layer of the intermediate alloy layer 6. A method for producing an electrode member for a lead-acid battery. 3 Core metals 3 and 5 are placed in zinc-lead or zinc-tin alloy bath 2
The intermediate alloy layers 6', 6'' are formed on the outer layer by immersion in the aluminum alloy, and the core metals 3, 5 are made of aluminum or an aluminum alloy.
The zinc-lead or zinc-tin alloy bath 2 contains 5
It contains ~20w% or 50~80w% of tin and is in a quasi-liquid state, and the thickness of the intermediate alloy layers 6', 6'' is as follows:
10 to 200 μm, and then forming a lead or lead alloy layer 7 on the outer layer of the intermediate alloy layers 6', 6''. A method for manufacturing an electrode member for a lead-acid battery.