Method for reducing hydrogen content in high-purity aluminum cast ingot

Abstract

The invention relates to a method for reducing the hydrogen content in a high-purity aluminum ingot, which comprises the following steps: (1) machining the surface of an aluminum raw material to remove oxide inclusions to obtain a pretreated aluminum material; (2) smelting the pretreated aluminum material obtained in the step (1) to obtain a smelting solution; and (3) degassing the smelting solution obtained in the step (2), standing, and sequentially casting and cooling to obtain the high-purity aluminum cast ingot. According to the method provided by the invention, the hydrogen content in the cast ingot can be effectively reduced by pretreating the raw materials and adjusting the smelting process, so that the quality and the performance of the product are finally improved.

Description

Technical Field

[0001] The invention relates to the technical field of metal smelting, and in particular to a method for reducing the hydrogen content in a high-purity aluminum ingot. Background Art

[0002] High-purity aluminum (purity ≥99.9999%) has good physical and chemical properties and is widely used in electronic aluminum foil, electronic guide wires, high-purity alumina powder, aviation aluminum alloys, target materials and other fields.

[0003] The production process of high-purity aluminum is complicated, and the purity of aluminum needs to be improved through refining and purification technology. In the process of producing high-purity aluminum ingots, one of the key issues currently existing is to control the hydrogen content in the aluminum melt. Due to the chemical reaction between water vapor and molten aluminum, the aluminum melt will absorb a certain amount of hydrogen during the production process, and the generated hydrogen is easily absorbed by the aluminum liquid through adsorption and diffusion mechanisms. In addition, oxide inclusions in the aluminum liquid will also hinder the escape of gas, thereby increasing the solubility of hydrogen in the aluminum liquid.

[0004] The increase of hydrogen content in aluminum ingots will not only reduce the casting performance of aluminum, but also cause the ingot to be loose and porous, affecting the mechanical properties of the ingot and may ultimately affect the reliability of the product. In addition, the increase of hydrogen content will also cause peeling and blistering on the surface of the ingot, affecting the appearance of the ingot and subsequent processing. During the heat treatment process, the hydrogen may be redistributed, resulting in secondary porosity inside the ingot, further reducing the strength and ductility of the material.

[0005] CN110923465A discloses a method for reducing the hydrogen content in aluminum-lithium alloy casting. In this method, the aluminum-lithium alloy is isolated from the atmosphere through argon protection, thereby reducing the absorption of hydrogen by reaction with humid air during smelting, transmission and filtration, thereby achieving the effect of controlling the hydrogen content and oxide inclusions. However, the purity requirement of high-purity aluminum is higher than that of aluminum alloy, and the composition and content thereof need to be more finely controlled. Therefore, the above method is not suitable for the smelting preparation process of high-purity aluminum.

[0006] Therefore, providing a preparation method that can reduce the hydrogen content in high-purity aluminum ingots, thereby ensuring the quality and performance of high-purity aluminum, is a technical problem that needs to be solved in the current field. Summary of the invention

[0007] In view of the above problems, the purpose of the present invention is to provide a method for reducing the hydrogen content in high-purity aluminum ingots. Compared with the prior art, the method provided by the present invention can effectively reduce the hydrogen content in the ingot by pretreating the raw materials and adjusting the smelting process, thereby ultimately improving the quality and performance of the product.

[0008] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0009] The present invention provides a method for reducing the hydrogen content in a high-purity aluminum ingot, the method comprising the following steps:

[0010] (1) machining the surface of the aluminum raw material to remove oxide inclusions to obtain a pretreated aluminum material;

[0011] (2) melting the pretreated aluminum material obtained in step (1) to obtain a molten liquid;

[0012] (3) The molten liquid obtained in step (2) is degassed, then allowed to stand, and then cast and cooled in sequence to obtain a high-purity aluminum ingot.

[0013] In the present invention, the purity of aluminum in the high-purity aluminum ingot is ≥99.9999%.

[0014] In the present invention, the surface oxide inclusions of the aluminum raw material are firstly eliminated by machining, which can prevent the oxide inclusions from hindering the gas from escaping from the aluminum liquid during smelting, help release hydrogen, and reduce the hydrogen content of the ingot; then, by controlling the smelting conditions during the smelting process, such as the smelting temperature and time, the degree of oxidation and hydrogen absorption of the aluminum liquid can be controlled to reduce the hydrogen content; finally, the gas content in the metal liquid is reduced in the degassing stage, and the absorption of hydrogen by the aluminum liquid is avoided by controlling the standing time. In summary, the method provided by the present invention can effectively reduce the hydrogen content in the ingot, thereby ultimately improving the quality and performance of the product.

[0015] In the present invention, the shape of the aluminum raw material is not particularly limited, and it can be any ingot that can be machined.

[0016] Preferably, the purity of the aluminum raw material in step (1) is ≥99.999%, for example, it can be 99.999%, 99.9991%, 99.9992%, 99.9993%, 99.9994% or 99.9995%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0017] Preferably, the purity of the high-purity aluminum ingot is ≥99.9999%, for example, it can be 99.9999%, 99.99991%, 99.99992%, 99.99993%, 99.99994% or 99.99995%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0018] Preferably, the machining in step (1) comprises: cutting the surface of the aluminum raw material with a disc cutter.

[0019] Preferably, the cutting removal thickness is 0.5-1.5 mm, for example, it can be 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm or 1.5 mm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0020] Preferably, the rotation speed of the disc cutter in step (1) is 900-1000 r / min, for example, it can be 900 r / min, 910 r / min, 920 r / min, 930 r / min, 940 r / min, 950 r / min, 960 r / min, 970 r / min, 980 r / min, 990 r / min or 1000 r / min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0021] Preferably, the feed rate of the disc cutter in step (1) is 1750-1850 mm / min, for example, it can be 1750 mm / min, 1760 mm / min, 1770 mm / min, 1780 mm / min, 1790 mm / min, 1800 mm / min, 1810 mm / min, 1820 mm / min, 1830 mm / min, 1840 mm / min or 1850 mm / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0022] In the present invention, by optimally controlling parameters such as cutting thickness, rotation speed and feed rate, the oxide inclusions on the surface of the raw material can be effectively removed, thereby preventing them from hindering the escape of hydrogen from the aluminum liquid, reducing the absorption of hydrogen by the aluminum liquid, and further reducing the hydrogen content of the ingot.

[0023] Preferably, the smelting temperature in step (2) is 710-760°C, for example, it can be 710°C, 715°C, 720°C, 725°C, 730°C, 735°C, 740°C, 745°C, 750°C, 755°C or 760°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0024] In the present invention, by preferably controlling the smelting temperature within a specific range, the absorption of hydrogen by the aluminum liquid can be further controlled to reduce the hydrogen content.

[0025] Preferably, the smelting time in step (2) is 12-14 h, for example, it can be 12 h, 12.2 h, 12.5 h, 12.8 h, 13 h, 13.2 h, 13.5 h, 13.8 h or 14 h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0026] In the present invention, by preferably controlling the smelting time within a specific range, that is, controlling the residence time of the aluminum liquid at a high temperature, the degree of oxidation of the aluminum liquid can be reduced, and the time of its contact with hydrogen can be reduced, thereby reducing its intake amount and achieving the effect of reducing the hydrogen content.

[0027] Preferably, the degassing in step (3) adopts a mixed atmosphere.

[0028] Preferably, the mixed atmosphere comprises a mixture of argon and chlorine.

[0029] Preferably, the volume ratio of argon and chlorine is (8-10):1, for example, it can be 8:1, 8.2:1, 8.5:1, 8.8:1, 9:1, 9.2:1, 9.5:1, 9.8:1 or 10:1, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0030] Preferably, the purity of the argon and chlorine gases is independently ≥ 99.999%, for example, 99.9991%, 99.9992%, 99.9993%, 99.9994% or 99.9995%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0031] In the present invention, by preferably using a mixed gas of argon and chlorine for degassing and controlling the volume ratio of argon and chlorine within a specific range, the reaction can be made more stable, the amount of slag generated is small, and the slag is powdery and not easily covered by the melt, further reducing the possibility of the co-existence of hydrogen and oxides and reducing the hydrogen content.

[0032] Preferably, the standing time in step (3) is 30-50 min, for example, 30 min, 32 min, 35 min, 38 min, 40 min, 42 min, 45 min, 48 min or 50 min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0033] In the present invention, the alumina inclusions increase in size after degassing and generally sink to the bottom of the furnace within 10-20 minutes. The present invention preferably controls the standing time within a specific range, which can further avoid excessive absorption of hydrogen.

[0034] As a preferred technical solution of the present invention, the method comprises the following steps:

[0035] (1) machining the surface of an aluminum raw material with a purity of ≥99.999% to remove oxide inclusions, wherein the machining comprises cutting and removing a thickness of 0.5-1.5 mm from the surface of the aluminum raw material using a disc cutter to obtain a pretreated aluminum material, wherein the rotation speed of the disc cutter is 900-1000 r / min, and the feed rate of the disc cutter is 1750-1850 mm / min;

[0036] (2) smelting the pretreated aluminum material obtained in step (1) at 710-760° C. for 12-14 hours to obtain a molten liquid;

[0037] (3) Degassing the molten liquid obtained in step (2) by using a mixture of argon and chlorine, wherein the volume ratio of the argon and chlorine is (8-10):1, and the purity of the argon and chlorine is independently ≥99.999%, and then standing for 30-50 minutes, followed by casting and cooling in sequence to obtain a high-purity aluminum ingot.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] The method provided by the present invention can effectively reduce the hydrogen content in the ingot and avoid the generation of looseness and pores inside the ingot through pretreatment of aluminum raw materials and control of smelting process conditions, thereby improving the mechanical properties of the ingot and avoiding peeling and blistering on the surface of the ingot. Under optimal conditions, the hydrogen content in the ingot can be reduced to below 0.1ppm. DETAILED DESCRIPTION

[0040] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0041] Example 1

[0042] This embodiment provides a method for reducing the hydrogen content in a high-purity aluminum ingot, the method comprising the following steps:

[0043] (1) machining the surface of an aluminum raw material with a purity of 99.999% to remove oxide inclusions, wherein the machining comprises cutting and removing a thickness of 1 mm from the surface of the aluminum raw material using a disc cutter to obtain a pretreated aluminum material, wherein the rotation speed of the disc cutter is 950 r / min, and the feed rate of the disc cutter is 1800 mm / min;

[0044] (2) smelting the pretreated aluminum material obtained in step (1) at 730° C. for 13 hours to obtain a molten liquid;

[0045] (3) Degassing the molten liquid obtained in step (2) with a mixture of argon and chlorine, wherein the volume ratio of the argon and chlorine is 9:1, and the purity of the argon and chlorine is independently 99.999%, and then standing for 40 minutes, followed by casting and cooling in sequence to obtain a high-purity aluminum ingot.

[0046] Example 2

[0047] This embodiment provides a method for reducing the hydrogen content in a high-purity aluminum ingot, the method comprising the following steps:

[0048] (1) machining the surface of an aluminum raw material with a purity of 99.999% to remove oxide inclusions, wherein the machining comprises cutting and removing a thickness of 0.5 mm from the surface of the aluminum raw material using a disc cutter to obtain a pretreated aluminum material, wherein the rotation speed of the disc cutter is 900 r / min, and the feed rate of the disc cutter is 1850 mm / min;

[0049] (2) smelting the pretreated aluminum material obtained in step (1) at 710° C. for 14 hours to obtain a molten liquid;

[0050] (3) Degassing the molten liquid obtained in step (2) with a mixture of argon and chlorine, wherein the volume ratio of the argon and chlorine is 8:1, and the purity of the argon and chlorine is independently 99.999%, and then standing for 50 minutes, followed by casting and cooling in sequence to obtain a high-purity aluminum ingot.

[0051] Example 3

[0052] This embodiment provides a method for reducing the hydrogen content in a high-purity aluminum ingot, the method comprising the following steps:

[0053] (1) machining the surface of an aluminum raw material with a purity of 99.999% to remove oxide inclusions, wherein the machining comprises cutting and removing a thickness of 1.5 mm from the surface of the aluminum raw material using a disc cutter to obtain a pretreated aluminum material, wherein the rotation speed of the disc cutter is 1000 r / min, and the feed rate of the disc cutter is 1750 mm / min;

[0054] (2) smelting the pretreated aluminum material obtained in step (1) at 760° C. for 12 hours to obtain a molten liquid;

[0055] (3) Degassing the molten liquid obtained in step (2) with a mixture of argon and chlorine, wherein the volume ratio of the argon and chlorine is 10:1, and the purity of the argon and chlorine is independently 99.999%, and then standing for 30 minutes, followed by casting and cooling in sequence to obtain a high-purity aluminum ingot.

[0056] Example 4

[0057] This embodiment provides a method for reducing the hydrogen content in a high-purity aluminum ingot. The method is different from that in Embodiment 1 only in that the smelting temperature is 700°C.

[0058] Example 5

[0059] This embodiment provides a method for reducing the hydrogen content in a high-purity aluminum ingot. The method is different from that in Embodiment 1 only in that the smelting temperature is 770°C.

[0060] Example 6

[0061] This embodiment provides a method for reducing the hydrogen content in a high-purity aluminum ingot. The method is different from that in Embodiment 1 only in that the smelting time is 16 hours.

[0062] Example 7

[0063] This embodiment provides a method for reducing the hydrogen content in a high-purity aluminum ingot. The difference between the method and the method in Embodiment 1 is that the volume ratio of argon gas to chlorine gas is 7:1.

[0064] Example 8

[0065] This embodiment provides a method for reducing the hydrogen content in a high-purity aluminum ingot. The difference between the method and the method in Embodiment 1 is that the volume ratio of argon gas to chlorine gas is 12:1.

[0066] Example 9

[0067] This embodiment provides a method for reducing the hydrogen content in a high-purity aluminum ingot. The difference between the method and the method in Embodiment 1 is that the standing time is 60 minutes.

[0068] Example 10

[0069] This embodiment provides a method for reducing the hydrogen content in a high-purity aluminum ingot. The only difference compared with Embodiment 1 is that the mixed gas of argon and chlorine is not used for degassing, and the mixed gas of argon and chlorine is replaced by 99.999% argon.

[0070] The hydrogen content in the ingots prepared in Examples 1-10 was measured using an element analyzer. The results are shown in Table 1.

[0071] Table 1

[0072]

[0073]

[0074] From the data in Table 1, we can see that:

[0075] (1) It can be seen from the data of Examples 1-3 that the method provided by the present invention can reduce the hydrogen content in the ingot to below 0.1 ppm under optimal conditions.

[0076] (2) It can be seen from the data of Example 1, Examples 4-6 and Example 9 that the present invention can reduce the absorption of hydrogen by aluminum liquid by preferably controlling the melting temperature, melting time and standing time, thereby further reducing the hydrogen content in the ingot.

[0077] (3) It can be seen from the data of Example 1, Examples 7-8 and Example 10 that the present invention can make the reaction more stable and generate powdery slag by preferably using a mixed gas of argon and chlorine and controlling the volume ratio of argon and chlorine, thereby reducing the possibility of the co-existence of hydrogen and oxides and helping to further reduce the hydrogen content.

[0078] In summary, the method provided by the present invention can effectively reduce the hydrogen content in the ingot by pretreating the raw materials and adjusting the smelting process, thereby ultimately improving the quality and performance of the product.

[0079] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for reducing the hydrogen content in a high-purity aluminum ingot, characterized in that: The method comprises the following steps: (1) machining the surface of the aluminum raw material to remove oxide inclusions to obtain a pretreated aluminum material; (2) melting the pretreated aluminum material obtained in step (1) to obtain a molten liquid; (3) The molten liquid obtained in step (2) is degassed, then allowed to stand, and then cast and cooled in sequence to obtain a high-purity aluminum ingot.

2. The method according to claim 1, characterized in that The purity of the aluminum raw material in step (1) is ≥ 99.999%; Preferably, the purity of the high-purity aluminum ingot is ≥99.9999%.

3. The method according to claim 1 or 2, characterized in that: The machining in step (1) includes: cutting the surface of the aluminum raw material with a disc cutter; Preferably, the cutting removal thickness is 0.5-1.5 mm.

4. The method according to claim 3, characterized in that The rotation speed of the disc cutter in step (1) is 900-1000r / min.

5. The method according to claim 3, characterized in that: The feed rate of the disc cutter in step (1) is 1750-1850 mm / min.

6. The method according to any one of claims 1 to 5, characterized in that: The smelting temperature in step (2) is 710-760°C.

7. The method according to any one of claims 1 to 6, characterized in that: The smelting time in step (2) is 12-14 hours.

8. The method according to any one of claims 1 to 7, characterized in that: The degassing in step (3) adopts a mixed atmosphere; Preferably, the mixed atmosphere comprises a mixture of argon and chlorine; Preferably, the volume ratio of argon gas to chlorine gas is (8-10):1; Preferably, the purity of the argon gas and the chlorine gas is independently ≥ 99.999%.

9. The method according to any one of claims 1 to 8, characterized in that: The standing time in step (3) is 30-50 minutes.

10. The method according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: (1) machining the surface of an aluminum raw material with a purity of ≥99.999% to remove oxide inclusions, wherein the machining comprises cutting and removing a thickness of 0.5-1.5 mm from the surface of the aluminum raw material using a disc cutter to obtain a pretreated aluminum material, wherein the rotation speed of the disc cutter is 900-1000 r / min, and the feed rate of the disc cutter is 1750-1850 mm / min; (2) smelting the pretreated aluminum material obtained in step (1) at 710-760° C. for 12-14 hours to obtain a molten liquid; (3) Degassing the molten liquid obtained in step (2) by using a mixture of argon and chlorine, wherein the volume ratio of the argon and chlorine is (8-10):1, and the purity of the argon and chlorine is independently ≥99.999%, and then standing for 30-50 minutes, followed by casting and cooling in sequence to obtain a high-purity aluminum ingot.

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