A lead alloy, its preparation method and application

Abstract

This invention relates to the field of metallic materials technology, specifically disclosing a lead alloy, its preparation method, and its applications. The alloy provided by this invention, by mass percentage, comprises the following chemical composition: Sb 2.5%-3.5%, Cu 0.01%-0.02%, Sn 0.04%-0.1%, As≤0.03%, Zn≤0.0015%, Bi≤0.02%, Cd≤0.003%, Ni≤0.005%, with the balance being Pb and unavoidable impurities. This invention uses copper instead of the traditional nucleating agent arsenic and specifies the content and ratio of antimony, tin, and copper. The alloy components work together to refine the grain size. Compared with existing cast-welded alloys, the lead alloy provided by this invention has lower electrical resistance, better hardness and tensile strength, and is environmentally friendly, showing promising application prospects.

Description

Technical Field

[0001] This invention relates to the field of metallic materials technology, and in particular to a lead alloy, its preparation method, and its application. Background Technology

[0002] With the rapid development of the national economy and the continuous improvement of living standards, the demand for storage batteries is increasing, and consequently, environmental awareness is becoming stronger. Currently, most solder alloys contain arsenic. The addition of arsenic to lead alloys can refine grains and increase the hardness of the lead alloy. However, arsenic-containing lead alloys also present some problems. For example, arsenic is a highly toxic substance, and arsenic-containing lead alloys may release trace amounts of arsenic, especially when the alloy is corroded or worn, seriously endangering human health. Furthermore, arsenic-containing alloys may cause water and soil pollution during production, use, and disposal. Therefore, providing an arsenic-free lead alloy that simultaneously possesses low resistivity, high tensile strength, and high hardness is of great significance. Summary of the Invention

[0003] To address the problems of high resistivity, poor tensile strength, and poor hardness in existing lead alloys, this invention provides a lead alloy, its preparation method, and its applications.

[0004] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows:

[0005] The first aspect of the present invention provides a lead alloy, which, by mass percentage, is composed of the following chemical composition: Sb 2.5%-3.5%, Cu 0.01%-0.02%, Sn 0.04%-0.1%, As ≤0.03%, Zn ≤0.0015%, Bi ≤0.02%, Cd ≤0.003%, Ni ≤0.005%, with the balance being Pb and unavoidable impurities.

[0006] During the preparation of arsenic-containing alloys, arsenic, as one of the most toxic substances, easily forms oxides and volatilizes, which has a significant impact on human health and the environment. Therefore, it is of great significance to find a new metallic element to replace arsenic without affecting the performance of the alloy and to reduce the environmental pollution caused by lead alloys during production and use.

[0007] Compared to existing technologies, the lead alloy provided by this invention contains antimony, which forms a uniform dispersed phase, strengthening the crystal structure of the lead alloy and thus improving its hardness and tensile strength; tin improves the alloy's ductility; furthermore, this invention uses copper instead of the traditional nucleating agent arsenic and limits the content and ratio of antimony, tin, and copper. The alloys work together to refine the grain size. Compared with existing cast and welded alloys, the lead alloy provided by this invention has lower electrical resistance, better hardness and tensile strength, and is environmentally friendly, showing good application prospects.

[0008] A second aspect of the present invention provides a method for preparing the above-mentioned lead alloy, comprising the following steps:

[0009] S1. Under an inert gas atmosphere, add 70-75% reduced lead, heat to 300℃-400℃, then add slag-forming agent to react and obtain the first lead liquid;

[0010] S2. Elemental copper is added to the first lead liquid at 600℃-700℃ and smelted to obtain the second lead liquid;

[0011] S3. At 600℃-750℃, the remaining reduced lead, antimony master alloy and elemental tin are added to the second lead liquid for smelting to obtain the lead alloy.

[0012] The lead alloy preparation method provided by this invention first controls the smelting environment to be inert, which can reduce the smelting temperature and thus reduce energy consumption. By controlling the smelting environment and reducing the smelting temperature, the oxidation of copper, antimony and tin can also be significantly reduced, and the alloying between metals can be accelerated, thereby reducing the loss rate of lead alloy and increasing the yield of lead alloy. The alloy prepared by the lead alloy preparation method provided by this invention has uniform composition, good performance, and the process is simple, easy to operate, and suitable for mass production.

[0013] Preferably, in S1, the arsenic content in the reduced lead is 0.2%-0.3%.

[0014] Preferably, in S1, the mass ratio of arsenic to slag-forming agent in the reduced lead is (1.5-3.5):1.

[0015] The optimal amount of slag-forming agent can remove arsenic to a level that does not affect the alloy's properties.

[0016] Preferably, in S1, the slag-forming agent is a mixture of sodium hydroxide and sodium nitrate.

[0017] Preferably, in S1, the mass ratio of sodium hydroxide to sodium nitrate in the slag-forming agent is (2-6):1.

[0018] The optimal amounts of sodium hydroxide and sodium nitrate can effectively reduce the arsenic content in the alloy while ensuring that the alloy's performance is not affected.

[0019] Preferably, in S1, the reaction time is 15 min to 20 min.

[0020] Preferably, in S1, the arsenic content of the first lead solution is ≤0.03%.

[0021] Preferably, in S1, after the reaction is completed, it is also necessary to remove the lead slag on the surface of the first lead liquid.

[0022] Preferably, in S1, the inert gas is nitrogen.

[0023] Preferably, in S2, the melting time is 5-10 minutes.

[0024] Preferably, in step S2, the elemental copper is added in 3-4 portions, with each addition being 25%-34%.

[0025] Preferably, in S3, the melting time is 2-3 minutes.

[0026] Preferably, in S3, the antimony master alloy is a composite alloy of lead and antimony.

[0027] A third aspect of the present invention provides the application of the above-mentioned lead alloy in lead-acid batteries. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0029] Example 1

[0030] This embodiment provides a lead alloy, which, by mass percentage, is composed of the following chemical composition: Sb 3.5%, Cu 0.01%, Sn 0.1%, As ≤ 0.03%, Zn ≤ 0.0015%, Bi ≤ 0.02%, Cd ≤ 0.003%, Ni ≤ 0.005%, with the balance being Pb and unavoidable impurities;

[0031] This embodiment also provides a method for preparing the above-mentioned lead alloy, including the following steps:

[0032] S1. Under a nitrogen atmosphere, add 75% reduced lead, heat to 400℃, then add a slagging agent and react for 15 minutes to obtain the first lead liquid, with an arsenic content ≤0.03%; wherein, the mass ratio of arsenic to slagging agent in the reduced lead is 1.5:1, the slagging agent is a mixture of sodium hydroxide and sodium nitrate with a mass ratio of 6:1, and the arsenic content in the reduced lead is 0.2%-0.3%;

[0033] S2. Remove the lead slag from the surface of the first lead liquid, and add elemental copper to the first lead liquid at 700℃ and smelt for 5 minutes to obtain the second lead liquid; wherein, the elemental copper is added in 3 parts, with addition amounts of 33%, 33% and 34% respectively;

[0034] S3. At 600℃, the remaining reduced lead, antimony master alloy and elemental tin are added to the second lead liquid and smelted for 2 minutes to obtain lead alloy.

[0035] Example 2

[0036] This embodiment provides a lead alloy, which, by mass percentage, is composed of the following chemical composition: Sb 2.5%, Cu 0.02%, Sn 0.04%, As ≤ 0.03%, Zn ≤ 0.0015%, Bi ≤ 0.02%, Cd ≤ 0.003%, Ni ≤ 0.005%, with the balance being Pb and unavoidable impurities;

[0037] This embodiment also provides a method for preparing the above-mentioned lead alloy, including the following steps:

[0038] S1. Under a nitrogen atmosphere, add 70% reduced lead, heat to 300℃, then add a slagging agent and react for 20 minutes to obtain the first lead liquid, with an arsenic content ≤0.03%; wherein, the mass ratio of arsenic to slagging agent in the reduced lead is 3.5:1, the slagging agent is a mixture of sodium hydroxide and sodium nitrate with a mass ratio of 2:1, and the arsenic content in the reduced lead is 0.2%-0.3%;

[0039] S2. Remove the lead slag from the surface of the first lead liquid, and add elemental copper to the first lead liquid at 600℃ and smelt for 10 minutes to obtain the second lead liquid; wherein, the elemental copper is added in 4 batches, each batch being 25%;

[0040] S3. At 750°C, the remaining reduced lead, antimony master alloy and elemental tin are added to the second lead liquid and smelted for 3 minutes to obtain a lead alloy.

[0041] Example 3

[0042] This embodiment provides a lead alloy, which, by mass percentage, is composed of the following chemical composition: Sb 3%, Cu 0.015%, Sn 0.06%, As ≤ 0.03%, Zn ≤ 0.0015%, Bi ≤ 0.02%, Cd ≤ 0.003%, Ni ≤ 0.005%, with the balance being Pb and unavoidable impurities;

[0043] This embodiment also provides a method for preparing the above-mentioned lead alloy, including the following steps:

[0044] S1. Under a nitrogen atmosphere, add 72% reduced lead, heat to 350℃, then add a slagging agent and react for 18 minutes to obtain the first lead liquid, with an arsenic content ≤0.03%; wherein, the mass ratio of arsenic to slagging agent in the reduced lead is 3:1, the slagging agent is a mixture of sodium hydroxide and sodium nitrate with a mass ratio of 4:1, and the arsenic content in the reduced lead is 0.2%-0.3%;

[0045] S2. Remove the lead slag from the surface of the first lead liquid, and add elemental copper to the first lead liquid at 650℃ and smelt for 8 minutes to obtain the second lead liquid; wherein, the elemental copper is added in 4 batches, each batch being 25% of the total amount.

[0046] S3. At 700℃, the remaining reduced lead, antimony master alloy and elemental tin are added to the second lead liquid and smelted for 2 minutes to obtain lead alloy.

[0047] Comparative Example 1

[0048] The difference between this comparative example and Example 1 is as follows:

[0049] It is composed of the following chemical components by mass percentage: Sb 3.5%, Sn 0.1%, As≤0.03%, Zn≤0.0015%, Bi≤0.02%, Cd≤0.003%, Ni≤0.005%, with the balance being Pb and unavoidable impurities;

[0050] The remaining steps are the same as in Example 1.

[0051] Comparative Example 2

[0052] The difference between this comparative example and Example 1 is as follows:

[0053] It is composed of the following chemical components by mass percentage: Sb 3.5%, Cu 0.05%, Sn 0.1%, As≤0.03%, Zn≤0.0015%, Bi≤0.02%, Cd≤0.003%, Ni≤0.005%, with the balance being Pb and unavoidable impurities;

[0054] The remaining steps are the same as in Example 1.

[0055] The resistance of the lead alloys provided in Examples 1-3 and Comparative Examples 1-2 was tested using a DC low-resistance tester; the tensile properties of the lead alloys were tested using a universal testing machine at a speed of 20 mm / min; and the hardness was tested using a Vickers hardness tester, with a test force of 0.1 kgf and a test force holding time of 10 s. Specific test results are shown in Table 1.

[0056] Table 1

[0057]

[0058]

[0059] As shown in Table 1, the lead alloys provided in Examples 1-3 of this invention, by selectively limiting the content and ratio of antimony, tin, and copper, result in lead alloys with lower electrical resistance, better hardness, and tensile strength. The tensile strength can reach 21 MPa, and the hardness can reach 17.1 at 29d. The alloys prepared by the method provided by this invention have uniform composition, good performance, and the process is simple, easy to operate, and suitable for mass production.

[0060] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A lead alloy, characterized in that, consists of, by mass percent: Sb 2.5%, Cu 0.02%, Sn 0.04%, As ≤0.03%, Zn ≤0.0015%, Bi ≤0.02%, Cd ≤0.003%, Ni ≤0.005%, the balance being Pb and unavoidable impurities.

2. A method of producing the lead alloy as claimed in claim 1, characterized in that The method comprises the following steps: S1, under an inert gas atmosphere, adding 70-75% of reduced lead, heating to 300-400°C, then adding a slagging agent to react, obtaining a first lead liquid; S2, adding elemental copper to the first lead liquid at 600-700°C to smelt, obtaining a second lead liquid; S3, adding the remaining reduced lead, antimony master alloy and elemental tin to the second lead liquid at 600-750°C to smelt, obtaining the lead alloy.

3. The method of producing a lead alloy according to claim 2, wherein In S1, the content of arsenic in the reduced lead is 0.2-0.3%.

4. The method of producing a lead alloy according to claim 2, characterized by, In S1, the mass ratio of arsenic in the reduced lead to the slagging agent is (1.5-3.5):

1.

5. The method of producing a lead alloy according to claim 2, wherein The slagging agent is a mixture of sodium hydroxide and sodium nitrate.

6. The method of producing a lead alloy according to claim 5, characterized by, The mass ratio of sodium hydroxide to sodium nitrate in the slagging agent is (2-6):

1.

7. The method of producing a lead alloy according to claim 2, wherein In S1, the reaction time is 15-20 min; and / or In S1, the content of arsenic in the first lead liquid is ≤0.03%.

8. The method of producing a lead alloy according to claim 2, wherein In S2, the smelting time is 5-10 min.

9. The method of producing a lead alloy according to claim 2, wherein In S2, the elemental copper is added in 3-4 portions, and each portion is 25-34%.

10. Use of the lead alloy of claim 1 in a lead-acid storage battery.

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