Method for improving internal quality of cast high-purity aluminum alloy

Abstract

The invention relates to a method for improving the internal quality of a cast high-purity aluminum alloy, which comprises the following steps: (1) carrying out first smelting on a high-purity aluminum raw material, and then adding alloy components for second smelting to obtain a high-purity aluminum alloy melt; (2) the high-purity aluminum alloy melt obtained in the step (1) is sequentially subjected to refining, grain refining, filtering and semi-continuous casting, and an optimized high-purity aluminum alloy cast ingot is obtained; the step (2) of grain refinement comprises the steps that the aluminum alloy casting waste is subjected to extrusion and surface treatment, and obtained regenerated fine filaments are fed into a refined high-purity aluminum alloy melt. According to the method, the regenerated fine filaments are immersed into the high-purity aluminum alloy melt to serve as a refiner, the regenerated waste can be properly utilized, grains can be refined on the premise that components are not polluted, internal defects are reduced, and the method is suitable for industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloy casting, and particularly relates to a method for improving the internal quality of cast high-purity aluminum alloy. Background Art

[0002] High-purity aluminum alloy has excellent electrical conductivity, good process compatibility, high purity and interface characteristics, etc., and is the main material for metal interconnections in integrated circuit manufacturing. With the continuous improvement of the integration degree of integrated circuits, the requirements for the electromigration resistance and stress migration resistance of the metal interconnections therein are gradually increasing. Facing the market demand, high-purity aluminum alloy needs to continuously develop in the direction of higher purity, finer grains and more uniform tissue structure.

[0003] CN113249600A discloses a method for manufacturing an aluminum alloy with high toughness and a method for removing impurities and slag. By adding an aluminum-titanium alloy with an addition amount of 0.15-0.35% into the aluminum alloy liquid in two steps, in the first step, 0.1-0.2% of Al-5Ti-1B alloy wire is evenly added into the aluminum alloy liquid and immediately subjected to stirring and melting treatment while degassing and filtering treatment is carried out. The extracted gas levels the surface of the aluminum alloy liquid, and then the remaining Al-5Ti-1B alloy wire accounting for 0.1-0.2% of the total weight of the raw materials is evenly added into the aluminum alloy liquid for stirring and melting treatment, comprehensively refining the aluminum alloy liquid while reducing the presence of coarse long flaky phases in the structure. At the same time, the six surfaces of the aluminum alloy ingot are coated with an evenly distributed inorganic adhesive.

[0004] CN107058770A discloses a casting and processing process for a hard 1090 aluminum alloy for anodic oxidation, and the steps are as follows: putting electrolytic aluminum liquid with an aluminum purity of 99.90-99.92% into a melting furnace, adding 1090 aluminum alloy cold material with a mass ratio of not less than 20%, and controlling the melting temperature at 710-725°C; after melting is completed, refining is carried out, and the refining temperature is controlled at 700-710°C, and refining is completed within 45 minutes, and the refining agent is hexachloroethane; after refining is completed, slab ingot casting is carried out. During casting, an Al-Ti-C grain refiner is added in front of the stirring degassing box in a double-wire feeding manner, and temperature compensation is carried out at the end of the chute to ensure that the casting temperature is stable at 690-700°C.

[0005] The above methods use Al-Ti-B or Al-Ti-C grain refiners to refine grains, but they will introduce redundant alloy elements, thereby reducing the alloy purity. Therefore, it is necessary to refine grains and improve the internal quality of aluminum alloy on the premise of saving costs and not contaminating the components.

[0006] During the casting process of high-purity aluminum alloy, due to factors such as the environment, equipment stability, and casting parameters, waste materials will inevitably be generated. If the internal quality of the aluminum alloy ingot can be improved while properly utilizing waste materials for regeneration, it is of great significance for sustainable development and resource utilization. Summary of the Invention

[0007] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a method for improving the internal quality of cast high-purity aluminum alloy, which can refine the grains and reduce the occurrence probability of internal defects, while saving costs.

[0008] To achieve the purpose of this invention, the following technical solutions are adopted:

[0009] The present invention provides a method for improving the internal quality of cast high-purity aluminum alloy, and the method includes the following steps:

[0010] (1) First, melt the high-purity aluminum raw material, and then add alloy components for second melting to obtain a high-purity aluminum alloy melt;

[0011] (2) The high-purity aluminum alloy melt obtained in step (1) is successively subjected to refining, grain refinement, filtration, and semi-continuous casting to obtain an optimized high-purity aluminum alloy ingot;

[0012] The step of grain refinement in step (2) includes: extruding and surface-treating the aluminum alloy casting waste, and feeding the obtained recycled fine wire material into the refined high-purity aluminum alloy melt.

[0013] The method for improving the internal quality of cast high-purity aluminum alloy provided by the present invention immerses the recycled fine wire material obtained by treating the qualified aluminum alloy casting waste into the high-purity aluminum alloy melt as a grain refiner. It can not only save costs and properly utilize recycled waste materials, but also refine the grains and reduce internal defects without polluting the composition, and is suitable for industrial production.

[0014] Preferably, the purity of the high-purity aluminum raw material in step (1) is ≥4N5, for example, it can be 4N5, 5N or 6N, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0015] Preferably, the purity of the alloy components in step (1) is ≥5N, for example, it can be 5N, 6N or 7N, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0016] Preferably, the alloy components in step (1) include pure silicon and / or pure copper.

[0017] Preferably, the preheating temperature of the crucible used for the first melting in step (1) is 80 - 245°C, and the preheating time is 1 - 2h.

[0018] The preheating temperature of the crucible used in the first smelting in step (1) is 80 - 245 °C. For example, it can be 80 °C, 100 °C, 150 °C, 200 °C or 245 °C, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0019] The preheating time of the crucible used in the first smelting in step (1) is 1 - 2 h. For example, it can be 1 h, 1.2 h, 1.5 h, 1.8 h or 2 h, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0020] Preferably, the temperature of the first smelting in step (1) is 700 - 750 °C. For example, it can be 700 °C, 710 °C, 720 °C, 730 °C or 750 °C, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0021] Preferably, in step (1), the first smelting is carried out until the high-purity aluminum raw material is completely melted into a liquid state.

[0022] Preferably, the temperature of the second smelting in step (1) is 700 - 750 °C. For example, it can be 700 °C, 710 °C, 720 °C, 730 °C or 750 °C, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0023] Preferably, the time of the second smelting in step (1) is 10 - 50 min. For example, it can be 10 min, 20 min, 30 min, 40 min or 50 min, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0024] During the second smelting process, samples are taken for chemical composition analysis and the time is controlled within 10 - 50 min, and a high-purity aluminum alloy melt with qualified composition can be obtained. It should be noted that the alloy composition is not limited in the present invention, and those skilled in the art can make adaptive adjustments according to the actual process and target products.

[0025] Preferably, the rotation speed of the on-line degassing device used in the refining in step (2) is 200 - 550 r / min. For example, it can be 200 r / min, 300 r / min, 420 r / min, 430 r / min, 450 r / min, 500 r / min or 550 r / min, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable, and preferably it is 420 - 450 r / min.

[0026] Preferably, the argon flow rate of the on-line degassing device used in the refining in step (2) is 2 - 8 m 3 / h. For example, it can be 2 m 3 / h, 3m 3 / h, 5m 3 / h, 6m 3 / h or 8m 3 / h, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0027] Preferably, the refining time in step (2) is 1 - 3h, for example, it can be 1h, 1.5h, 2h, 2.5h or 3h, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0028] Preferably, the extruded slender wire material has a diameter of 15 - 17mm, for example, it can be 15mm, 15.5mm, 16mm, 16.5mm or 17mm, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0029] Preferably, the surface treatment includes alkali washing, acid washing and polishing treatments carried out in sequence.

[0030] The alkali washing and acid washing can remove the stains on the surface of the slender wire material, and the polishing treatment can remove the oxide layer on the surface of the slender wire material, thereby obtaining a refined recycled fine wire material. The reagents used for alkali washing and acid washing are subject to being able to remove the stains on the surface of the slender wire material, and no special requirements are made in the present invention; the way of polishing treatment is subject to being able to remove the oxide layer on the surface of the slender wire material, and no special requirements are made in the present invention.

[0031] Preferably, the wire feeding speed of the recycled fine wire material is 61.5 - 307.2mm / min, for example, it can be 61.5mm / min, 100mm / min, 150mm / min, 200mm / min, 250mm / min or 307.2mm / min, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0032] Preferably, the mass ratio of the recycled fine wire material to the refined high-purity aluminum alloy melt is (2 - 5):100, for example, it can be 2:100, 2.5:100, 3:100, 4:100 or 5:100, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0033] Preferably, the filtration in step (2) is carried out through a filtration device, and a ceramic filter plate is provided in the filtration device.

[0034] Preferably, the liquid level height of the mold used for semi-continuous casting in step (2) is 10 - 35mm, for example, it can be 10mm, 15mm, 20mm, 30mm or 35mm, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0035] Preferably, the temperature of the semi - continuous casting in step (2) is 690 - 720 °C. For example, it can be 690 °C, 695 °C, 700 °C, 710 °C or 720 °C, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0036] Preferably, the speed of the semi - continuous casting in step (2) is 50 - 100 mm / min. For example, it can be 50 mm / min, 60 mm / min, 80 mm / min, 90 mm / min or 100 mm / min, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0037] Preferably, the cooling water flow rate of the semi - continuous casting in step (2) is 200 - 700 L / min. For example, it can be 200 L / min, 300 L / min, 500 L / min, 600 L / min or 700 L / min, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0038] Preferably, the cooling water temperature of the semi - continuous casting in step (2) is 10 - 30 °C. For example, it can be 10 °C, 15 °C, 20 °C, 25 °C or 30 °C, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] The method for improving the internal quality of cast high - purity aluminum alloy provided by the present invention immerses the regenerated fine wire material obtained by treating the qualified - composition aluminum alloy casting waste into the high - purity aluminum alloy melt as a grain refiner. It can not only save costs and properly utilize the regenerated waste, but also refine the grains and reduce internal defects without contaminating the composition, and is applicable to industrial production. Specific Embodiments

[0041] The technical solution of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0042] Example 1

[0043] This example provides a method for improving the internal quality of cast high - purity aluminum alloy, and the method includes the following steps:

[0044] (1) Place high-purity aluminum raw materials with a purity of 6N in a crucible preheated at 150 °C for 1.5 h, and conduct the first melting until the high-purity aluminum raw materials are completely liquid at a temperature of 720 °C. Then, add pure silicon and pure copper with a purity of 6N each for the second melting at a temperature of 720 °C for 30 min to obtain a high-purity aluminum alloy melt.

[0045] (2) The high-purity aluminum alloy melt obtained in step (1) is refined by an on-line degassing device with a rotation speed of 430 r / min and an argon flow rate of 5 m 3 / h for 2 h.

[0046] Extrude the aluminum alloy casting waste to obtain a slender wire with a diameter of 16 mm. Conduct alkali washing, acid washing, and polishing on the slender wire in sequence. Feed the obtained recycled fine wire into the refined high-purity aluminum alloy melt at a wire feeding speed of 200 mm / min. The mass ratio of the recycled fine wire to the refined high-purity aluminum alloy melt is 3:100.

[0047] Then, filter through a filtering device, and a ceramic filter plate is arranged in the filtering device; then, conduct semi-continuous casting on the filtered high-purity aluminum alloy melt at a temperature of 700 °C, a speed of 80 mm / min, a liquid level height of the mold of 20 mm, a cooling water flow rate of 500 L / min, and a cooling water temperature of 20 °C to obtain an optimized high-purity aluminum alloy ingot.

[0048] Example 2

[0049] This example provides a method for improving the internal quality of cast high-purity aluminum alloy, and the method includes the following steps:

[0050] (1) Place high-purity aluminum raw materials with a purity of 5N in a crucible preheated at 80 °C for 2 h, and conduct the first melting until the high-purity aluminum raw materials are completely liquid at a temperature of 700 °C. Then, add pure silicon and pure copper with a purity of 6N each for the second melting at a temperature of 700 °C for 50 min to obtain a high-purity aluminum alloy melt.

[0051] (2) The high-purity aluminum alloy melt obtained in step (1) is refined by an on-line degassing device with a rotation speed of 420 r / min and an argon flow rate of 2 m 3 / h for 3 h.

[0052] Extrude the aluminum alloy casting waste to obtain a slender wire with a diameter of 15 mm. Conduct alkali washing, acid washing, and polishing on the slender wire in sequence. Feed the obtained recycled fine wire into the refined high-purity aluminum alloy melt at a wire feeding speed of 61.5 mm / min. The mass ratio of the recycled fine wire to the refined high-purity aluminum alloy melt is 2:100.

[0053] Then, it is filtered through a filtering device, and a ceramic filter plate is provided in the filtering device; then, the filtered high-purity aluminum alloy melt is subjected to semi-continuous casting at a temperature of 690 °C, a speed of 100 mm / min, a liquid level height of the mold of 10 mm, a cooling water flow rate of 200 L / min, and a cooling water temperature of 10 °C to obtain an optimized high-purity aluminum alloy ingot.

[0054] Example 3

[0055] This example provides a method for improving the internal quality of cast high-purity aluminum alloy. The method includes the following steps:

[0056] (1) Place high-purity aluminum raw materials with a purity of 4N5 in a crucible preheated at 245 °C for 1 h, perform the first melting until the high-purity aluminum raw materials are completely liquid at a temperature of 750 °C, and then add pure silicon and pure copper with a purity of 5N each for the second melting at a temperature of 750 °C for 10 min to obtain a high-purity aluminum alloy melt.

[0057] (2) The high-purity aluminum alloy melt obtained in step (1) is refined through an on-line degassing device with a rotation speed of 450 r / min and an argon flow rate of 8 m 3 / h for 1 h.

[0058] Extrude aluminum alloy casting waste to obtain slender wire materials with a diameter of 17 mm. Perform alkali washing, acid washing, and grinding treatments on the slender wire materials in sequence. Feed the obtained recycled fine wire materials into the refined high-purity aluminum alloy melt at a wire feeding speed of 307.2 mm / min. The mass ratio of the recycled fine wire materials to the refined high-purity aluminum alloy melt is 5:100.

[0059] Then, it is filtered through a filtering device, and a ceramic filter plate is provided in the filtering device; then, the filtered high-purity aluminum alloy melt is subjected to semi-continuous casting at a temperature of 720 °C, a speed of 50 mm / min, a liquid level height of the mold of 35 mm, a cooling water flow rate of 700 L / min, and a cooling water temperature of 30 °C to obtain an optimized high-purity aluminum alloy ingot.

[0060] Example 4

[0061] This example provides a method for improving the internal quality of cast high-purity aluminum alloy. The difference from Example 1 is that the crucible in step (1) is not preheated, and the rest are the same as in Example 1.

[0062] Example 5

[0063] This example provides a method for improving the internal quality of cast high-purity aluminum alloy. The difference from Example 1 is that except for adjusting the rotation speed of the on-line degassing device in step (2) to 200 r / min, the rest are the same as in Example 1.

[0064] Example 6

[0065] This example provides a method for improving the internal quality of cast high-purity aluminum alloy. The difference from Example 1 is that, except that the rotation speed of the on-line degassing device described in step (2) is adjusted to 550 r / min, the rest are the same as in Example 1.

[0066] Example 7

[0067] This example provides a method for improving the internal quality of cast high-purity aluminum alloy. The difference from Example 1 is that, except that the mass ratio of the recycled fine wire material to the refined high-purity aluminum alloy melt described in step (2) is adjusted to 1:100, the rest are the same as in Example 1.

[0068] Example 8

[0069] This example provides a method for improving the internal quality of cast high-purity aluminum alloy. The difference from Example 1 is that, except that the mass ratio of the recycled fine wire material to the refined high-purity aluminum alloy melt described in step (2) is adjusted to 7:100, the rest are the same as in Example 1.

[0070] Comparative Example 1

[0071] This comparative example provides a method for improving the internal quality of cast high-purity aluminum alloy. The difference from Example 1 is that the recycled fine wire material in step (2) is replaced with Al-5Ti-1B alloy wire of equal mass, and the rest are the same as in Example 1.

[0072] Comparative Example 2

[0073] This comparative example provides a method for improving the internal quality of cast high-purity aluminum alloy. The difference from Example 1 is that the slender wire material in step (2) is not subjected to alkali washing, acid washing, and grinding treatments, and the rest are the same as in Example 1.

[0074] Using the methods for improving the internal quality of cast high-purity aluminum alloy provided in Examples 1-8 and Comparative Examples 1 and 2, optimized high-purity aluminum alloy ingots are obtained. The optimized high-purity aluminum alloy ingot samples are detected by a scanning electron microscope, and the obtained grain sizes are shown in Table 1; the internal defect conditions are classified according to the number of feathery grains and bright grains, and the results are divided into "very few", "few", and "many", and the obtained results are shown in Table 1; the internal H content, O content, and impurity element content of the optimized high-purity aluminum alloy ingots are measured, and the obtained results are shown in Table 1.

[0075] Table 1

[0076]

[0077]

[0078] As can be seen from Table 1, by using the method provided by the present invention to improve the internal quality of cast high-purity aluminum alloy, a high-purity aluminum alloy ingot with refined grains and few internal defects can be obtained;

[0079] Comparing Example 1 with Examples 2 and 3, it can be seen that when the purity of the raw materials decreases, the impurity content in the ingot will increase accordingly; comparing Example 1 with Example 4, it can be seen that directly melting without preheating the crucible will cause the crucible to rupture and then contaminate the melt; comparing Example 1 with Examples 5 and 6, it can be seen that if the rotation speed of the on-line degassing device is too low, the inclusions cannot be removed thoroughly, which will increase the internal defects; if the rotation speed is too high, it will cause eddy current gas entrainment, which will entrain air into the melt and cause secondary pollution; comparing Example 1 with Examples 7 and 8, it can be seen that if the dosage of the recycled fine wire material is too low, it cannot play the role of grain refinement; if the dosage is too high, it will increase the internal defects, but it will provide more nucleation sites, thus being able to refine the grains; comparing Example 1 with Comparative Example 1, it can be seen that using the existing technology additive as a grain refiner will introduce extra alloying elements such as Ti and B, thus greatly increasing the impurity content; comparing Example 1 with Comparative Example 2, it can be seen that directly feeding the extruded fine wire material without surface treatment will cause pollution and increase the probability of internal defect generation.

[0080] In summary, the method provided by the present invention to improve the internal quality of cast high-purity aluminum alloy immerses the recycled fine wire material obtained by treating the qualified-component aluminum alloy casting waste into the high-purity aluminum alloy melt as a grain refiner, which can not only save costs and properly utilize the recycled waste, but also refine the grains and reduce internal defects without contaminating the components, and is suitable for industrial production.

[0081] The applicant declares that the above is only the specific implementation manner 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 any person skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A method for improving the internal quality of cast high-purity aluminum alloy, characterized in that, The method includes the following steps: (1) First, melt the high-purity aluminum raw material, and then add alloying components for a second melting to obtain a high-purity aluminum alloy melt; (2) The high-purity aluminum alloy melt obtained in step (1) is successively subjected to refining, grain refinement, filtration, and semi-continuous casting to obtain an optimized high-purity aluminum alloy ingot; The step of grain refinement in step (2) includes: extruding and surface-treating the aluminum alloy casting waste, and feeding the obtained recycled fine wire material into the refined high-purity aluminum alloy melt.

2. The method according to claim 1, wherein The purity of the high-purity aluminum raw material in step (1) is ≥4N5; Preferably, the purity of the alloying components in step (1) is ≥5N; Preferably, the alloying components in step (1) include pure silicon and / or pure copper.

3. The method according to claim 1 or 2, characterized in that, The preheating temperature of the crucible used for the first melting in step (1) is 80 - 245°C, and the preheating time is 1 - 2 h; Preferably, the temperature of the first melting in step (1) is 700 - 750°C; Preferably, in step (1), the first melting is carried out until the high-purity aluminum raw material is completely melted into a liquid state.

4. The method according to any one of claims 1 to 3, characterized in that, The temperature of the second melting in step (1) is 700 - 750°C; Preferably, the time of the second melting in step (1) is 10 - 50 min.

5. The method according to any one of claims 1 to 4, characterized in that The rotation speed of the on-line degassing device used for refining in step (2) is 200 - 550 r / min, preferably 420 - 450 r / min; Preferably, the argon flow rate of the on-line degassing device used in the refining in step (2) is 2-8 m 3 / h; Preferably, the time of refining in step (2) is 1 - 3 h.

6. The method according to any one of claims 1-5, characterized in that, The slender wire material obtained after extrusion has a diameter of 15 - 17 mm; Preferably, the surface treatment includes successive alkali washing, acid washing, and polishing treatments.

7. The method according to any one of claims 1-6, characterized in that, The wire feeding speed of the recycled fine wire material is 61.5 - 307.2 mm / min; Preferably, the mass ratio of the recycled fine wire material to the refined high-purity aluminum alloy melt is (2 - 5):

100.

8. The method according to any one of claims 1 to 7, characterized in that, The filtration in step (2) is carried out through a filtration device, and a ceramic filter plate is provided in the filtration device.

9. The method according to any one of claims 1 to 8, characterized in that, The liquid level height of the mold used for semi-continuous casting in step (2) is 10 - 35 mm; Preferably, the temperature of semi-continuous casting in step (2) is 690 - 720°C; Preferably, the speed of semi-continuous casting in step (2) is 50 - 100 mm / min.

10. The method according to any one of claims 1-9, characterized in that, The cooling water flow rate for semi-continuous casting in step (2) is 200 - 700 L / min; Preferably, the cooling water temperature for semi-continuous casting in step (2) is 10 - 30°C.

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