JPS5910420B2 - Lead-based alloy for storage battery electrode plates - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention primarily relates to a substrate alloy for electrode plates for lead-acid batteries.

Conventionally, lead-antimony alloys or lead-antimony-arsenic alloys, in which a small amount of antimony is added to lead, have been used for grid substrates for lead-acid batteries. Although it has the necessary strength as a substrate, antimony is eluted in the electrolyte and deposits on the surface of the cathode plate, and this precipitation promotes self-discharge and reduces capacity. Near the completion of charging and in overcharged conditions, the current flow rate is large, which causes the water in the electrolyte to easily decompose, causing so-called gashing, resulting in a drop in the level of the electrolyte in the cell. Grid boards that have these drawbacks, such as the need to constantly check the battery liquid head level and replenish water as necessary, are replaced by recently developed maintenance-free battery grid boards that do not require water replenishment. There were some shortcomings, such as being unsuitable for this purpose.

For this reason, lead-calcium alloys, lead-calcium-tin alloys, or lead-calcium-arsenic alloys are used for the grid substrates of maintenance-free batteries, but these alloys are less effective than lead-antimony alloys. Although the self-discharge rate and the current value at the completion of charging are small, the grain size is large, so in the electrolyte, localized corrosion from grain boundaries takes priority over uniform → corrosion from the alloy surface ( '-G has the disadvantage of shortening the life of the battery.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to maintain better castability, strength, self-discharge rate, current value at the time of charging completion, etc. than the above-mentioned conventional products,
The present invention provides a lead-based alloy for storage batteries that has high corrosion resistance, which in turn can extend the overcharge life of the battery.
0.03-0.2% calcium and 0.1-1.5% by weight
It is characterized by consisting of tin in the weight percent, arsenic in the range of 0.1 to 1.5 weight percent, and the balance lead.

- Next, the reasons for adding the alloy components constituting the alloy of the present invention and the reasons for their limitations will be explained.

Calcium is an element that primarily works to increase mechanical strength, and the reason for limiting its addition amount to the above range is that 0.0
If it is less than 3%, no effect of increasing mechanical strength will be obtained, and if it exceeds 0.2%, castability will decrease, embrittlement will become significant, and costs will increase. .

Furthermore, arsenic is an element that does not easily cause self-discharge even if it precipitates on the cathode plate side, and it also improves the castability of the alloy of the present invention and improves corrosion resistance by making the crystal structure finer and suppressing intergranular corrosion. The reason for limiting the amount added to the above range is that if it is less than 0.1%, little effect on castability or corrosion resistance will be obtained, and if it exceeds 1.5%, no improvement in corrosion resistance will be seen. This is because the embrittlement of the alloy does not accumulate and the cost increases. Tin mainly affects castability and mechanical properties; if the content is less than 0.1%, no improvement in castability can be obtained, and if it exceeds 1.5 (L), no mechanical strength can be obtained.

Next, examples of the alloy of the present invention will be described. After adding arsenic and a lead-calcium master alloy to molten lead to obtain the alloy composition shown in Table 1 (./F6l to 27%), a lattice substrate with a thickness of about 1.3 cm was formed using a casting machine. This was used as a sample for an automobile battery test, a sample for a corrosion resistance test, and a sample for a death test and a tensile test.

Yield strength%. 2 is the value obtained when a tensile test is performed on a product that has been aged at room temperature for 3 days after casting, and the corrosion weight loss is the value obtained when it is corroded for 1000 hours at a current density of 2.5 A/Dm2 in an electrolytic solution with a specific gravity of 1.260. It is. The current value during overcharging is 2.350± for each cell at 50°C for the above battery when a 12V40AH battery for an automobile is made using the above grid board.
The current value was measured after overcharging at a constant voltage of 0.005V.

The results of these measurements are shown in Table 1. Table 2 shows the results of tests conducted in the same manner as on the conventional grid substrates made of lead-antimony alloys (Taki 28-33). 1st
According to the results shown in the table, the present invention alloy has a low current value of 40 to 60 mA during overcharging, which indicates that the present invention alloy has a low self-discharge rate and low water loss. .

Further, the corrosion weight loss of the alloy of the present invention is 20 to 35%, and the corrosion resistance is much better than that of conventional alloys, and the corrosion resistance and yield strength are also good. As is clear from the above results, the alloy of the present invention can keep the self-discharge rate and the current value at the completion of charging low while maintaining good castability, mechanical strength, and corrosion resistance due to the above composition. It can be used for grid substrates, straps, intercell connectors, pole columns, etc. of lead-acid batteries, and is particularly suitable for grid substrates for maintenance-free batteries.

Claims (1)

[Claims] 1 0.03-0.2% calcium and 0.1-1
．． A lead-based alloy for storage battery electrode plates, characterized by comprising 5% by weight of tin, 0.1 to 1.5% by weight of arsenic, and the balance lead.