Preparation method of high-purity aluminum wire for vacuum coating, high-purity aluminum wire and application thereof

Abstract

The present application relates to the technical field of high-purity aluminum preparation, in particular to a preparation method of high-purity aluminum wire for vacuum coating, high-purity aluminum wire and application thereof, the number and size of the second phase are reduced by controlling the content of metal impurities in the high-purity aluminum wire, the hydrogen content in the aluminum liquid is ≤0.10 mL / 100g through degassing treatment, and the impurity content in the high-purity aluminum wire is less; the thickness of the oxide film on the surface of the aluminum wire and the grain size are controlled by controlling the roughing and finishing temperature, and intermediate annealing treatment is not performed to avoid the thickening of the oxide film on the surface of the aluminum wire; the strength and surface quality of the aluminum wire are improved through drawing and wire scraping treatment; the above-mentioned performance improvement reduces the splashing phenomenon of the aluminum wire in the evaporation process, the composite aluminum film obtained through vacuum evaporation has excellent performance, the square resistance in the TD direction is ≤29 mΩ / sq, the surface roughness Sa is ≤0.18 μm, the tensile strength is ≥215 MPa, and the pinhole rate is ≤0.02 ea / m 2 , the adhesion is measured by pasting the surface of the aluminum film with 3M adhesive tape, and there is no aluminum foil falling off.

Description

Technical Field

[0001] This invention relates to the field of high-purity aluminum preparation technology, specifically to a method for preparing high-purity aluminum wire for vacuum coating, the high-purity aluminum wire and its applications. Background Technology

[0002] In recent years, the development of new energy vehicles has been rapid, leading to increasingly stringent requirements for battery safety. The composite material used for the positive electrode current collector in new energy batteries employs a sandwich structure, consisting of a central polymer material and two metal stacked layers on either side, typically produced using vacuum deposition. Vacuum-deposited composite current collector aluminum films offer significant advantages, including higher safety performance, melting upon overheating to prevent explosions, and excellent weight reduction (48.1% weight reduction compared to traditional aluminum films). However, factors such as splashing during the deposition process can easily create pinholes, affecting the surface quality of the composite current collector aluminum film and limiting its application range.

[0003] During vacuum evaporation, aluminum wire transitions from a solid state onto the evaporation boat, becoming a liquid state, and then undergoes thermal diffusion from the liquid state into a gaseous state. Evaporation involves three states: solid, liquid, and gas. When the fine solid particles are subjected to energy by the heated gaseous state, splashing occurs. In addition to the material and state of the evaporation boat and the evaporation process, the purity of the aluminum wire, the size and quantity of the compound, the surface quality, and the thickness of the oxide film also directly affect splashing, thus influencing the splashing and causing excessive pinholes in the aluminum film. Summary of the Invention

[0004] To address the problems in the existing technology where high impurity content, large size of intermetallic compounds, and poor surface quality cause splashing during aluminum wire evaporation, affecting the surface quality and performance of the composite current collector aluminum film, this invention provides a method for preparing high-purity aluminum wire for vacuum coating, the high-purity aluminum wire, and its applications.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] A method for preparing high-purity aluminum wire for vacuum coating includes the following steps:

[0007] (1) Add aluminum ingots to a smelting furnace to melt them into molten aluminum. Transfer the molten aluminum to a holding furnace for degassing. The gas pressure inside the furnace is 0.3-1.0 MPa. Introduce Ar gas into the molten aluminum to obtain molten aluminum with a hydrogen content ≤0.10 mL / 100 g.

[0008] (2) The aluminum liquid obtained in step (1) is continuously cast using a casting machine at a casting temperature of 700-730℃ to obtain a billet. The oxide film on the surface of the billet is removed by scraping, and the billet is rolled at an initial rolling temperature of 400-450℃ and a final rolling temperature of 280-320℃ to obtain a high-purity aluminum wire rod.

[0009] (3) The high-purity aluminum wire rod obtained in step (2) is subjected to 6-10 coarse drawing, 1-3 fine drawing and 2-3 scraping processes to obtain high-purity aluminum wire for vacuum coating.

[0010] Furthermore, in step (1), continuous casting employs zoned automatic water pressure control.

[0011] Furthermore, the diameter of the high-purity aluminum wire rod described in step (2) is 8-10 mm.

[0012] Furthermore, the rolling speed in step (2) is 2-5 m / s.

[0013] Furthermore, in step (3), the diameter of the aluminum wire after coarse drawing is 2.6-2.8 mm, the diameter of the aluminum wire after fine drawing is 2.1-2.2 mm, and the diameter of the aluminum wire after scraping is 1.8-2.0 mm.

[0014] This invention also includes the following technical solutions:

[0015] A high-purity aluminum wire for vacuum coating has the following chemical composition by mass percentage: Al 99.92-99.98%, Fe≤0.005%, Si≤0.004%, Cu≤0.0001%, Mn≤0.0001%, Mg≤0.0002%, Cr≤0.0001%, Zn≤0.0001%, V≤0.0001%, Ti≤0.0008%, Bi≤0.0001%, with the balance being unavoidable impurities.

[0016] Furthermore, the aluminum wire has a surface roughness Sa≤0.2μm, an oxide film thickness≤100nm, a conductivity ≥64.2%IACS, and a tensile strength of 140-160MPa.

[0017] Furthermore, the aluminum wire contains an intermetallic compound AlFeSi phase, which is granular with a size ≤2μm.

[0018] This invention also includes the following technical solutions:

[0019] A composite current collector aluminum film is obtained by vacuum evaporation of high-purity aluminum wire used for vacuum coating.

[0020] Furthermore, the composite aluminum film exhibits a sheet resistance ≤29mΩ / sq in the TD direction, a surface roughness Sa≤0.18μm, a tensile strength ≥215MPa, and a pinhole rate ≤0.02ea / m. 2 The adhesion is achieved by using 3M tape to adhere the aluminum foil to the surface, with no aluminum foil falling off.

[0021] The mechanism involved in this invention is as follows:

[0022] Because the impurity elements in aluminum wire have high melting points, the second phase formed by these impurities is difficult to melt during vacuum evaporation, easily causing splashing and affecting the performance of the vacuum-deposited composite current collector aluminum film. When the Fe content in the aluminum wire does not exceed 0.005%, it mainly forms small granular AlFeSi phases, which are less prone to splashing during vacuum deposition. However, when the Fe content exceeds 0.005%, it easily forms large flocculent or blocky Fe phases, which are prone to splashing. Therefore, its content needs to be controlled below 0.005%. Si and Fe can form AlFeSi phases together, but the Si content affects the quantity and size of the AlFeSi phase. When the Si content exceeds 0.004%, the large quantity and size of the AlFeSi phase easily cause splashing during evaporation. The contents of Cu, Mg, Mn, Cr, Zn, and Ti need to be controlled below 100 ppm to avoid splashing.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] This invention reduces the quantity and size of the second phase by controlling the content of metallic impurities in high-purity aluminum wire. Degassing the molten aluminum ensures a hydrogen content ≤0.10mL / 100g, resulting in lower impurity content in the high-purity aluminum wire. Controlling the initial and final rolling temperatures controls the oxide film thickness and grain size on the aluminum wire surface, avoiding intermediate annealing to prevent oxide film thickening. Drawing and scraping processes improve the strength and surface quality of the aluminum wire. These performance improvements reduce spattering during the vapor deposition process. The composite aluminum film obtained by vacuum vapor deposition exhibits excellent properties, with a sheet resistance ≤29mΩ / sq in the TD direction, a surface roughness Sa ≤0.18μm, a tensile strength ≥215MPa, and a pinhole rate ≤0.02ea / m. 2 The adhesion is achieved by using 3M tape to adhere the aluminum foil to the surface, with no aluminum foil falling off. Attached Figure Description

[0025] The embodiments of the present invention will be further described below with reference to the accompanying drawings, wherein:

[0026] Figure 1 The second phase of the aluminum wire used for vacuum coating in Example 1 is shown;

[0027] Figure 2 The surface roughness of the aluminum wire used for vacuum coating in Example 1 is shown;

[0028] Figure 3 The oxide film thickness of the aluminum wire used for vacuum coating in Example 1 is shown. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0030] Example 1

[0031] A method for preparing high-purity aluminum wire for vacuum coating includes the following steps:

[0032] (1) Add aluminum ingots to a smelting furnace to melt them into molten aluminum. Transfer the molten aluminum to a holding furnace for degassing. The furnace pressure is 0.3 MPa. Introduce Ar gas into the molten aluminum to obtain molten aluminum with a hydrogen content of 0.10 mL / 100 g.

[0033] (2) The aluminum liquid obtained in step (1) is continuously cast at 700°C using a casting machine to obtain a billet. The oxide film on the surface of the billet is removed by scraping, and the billet is rolled. The initial rolling temperature is 400°C, the rolling speed is 3.5m / s, and the final rolling temperature is 300°C to obtain a high-purity aluminum wire rod with a diameter of 9.5mm.

[0034] (3) The high-purity aluminum wire rod obtained in step (2) is subjected to 7 coarse drawing to a diameter of 2.7 mm, 2 fine drawing to a diameter of 2.12 mm, and 2 scraping treatments to a diameter of 2.0 mm to obtain high-purity aluminum wire for vacuum coating.

[0035] In this embodiment, the high-purity aluminum wire used for vacuum coating has the following chemical composition by mass percentage: Al 99.98%, Fe 0.003%, Si 0.002%, Cu 0.0001%, Mn 0.0001%, Mg 0.0002%, Cr 0.0001%, Zn 0.0001%, V 0.0001%, Ti 0.0008%, Bi 0.0001%, with the balance being unavoidable impurities.

[0036] Example 2

[0037] A method for preparing high-purity aluminum wire for vacuum coating includes the following steps:

[0038] (1) Add aluminum ingots to a smelting furnace to melt them into molten aluminum. Transfer the molten aluminum to a holding furnace for degassing. The furnace pressure is 1.0 MPa. Introduce Ar gas into the molten aluminum to obtain molten aluminum with a hydrogen content of 0.09 mL / 100 g.

[0039] (2) The aluminum liquid obtained in step (1) is continuously cast at 730°C using a casting machine to obtain a billet. The oxide film on the surface of the billet is removed by scraping, and the billet is rolled. The initial rolling temperature is 380°C, the rolling speed is 3.2m / s, and the final rolling temperature is 310°C to obtain a high-purity aluminum wire rod with a diameter of 10.0mm.

[0040] (3) The high-purity aluminum wire rod obtained in step (2) is subjected to 8 coarse drawing to a diameter of 2.8 mm, 3 fine drawing to a diameter of 1.95 mm, and 2 scraping treatments to a diameter of 1.8 mm to obtain high-purity aluminum wire for vacuum coating.

[0041] In this embodiment, the high-purity aluminum wire used for vacuum coating has the following chemical composition by mass percentage: Al 99.92%, Fe 0.005%, Si 0.004%, Cu 0.0001%, Mn 0.0001%, Mg 0.0002%, Cr 0.0001%, Zn 0.0001%, V 0.0001%, Ti 0.0008%, Bi 0.0001%, with the balance being unavoidable impurities.

[0042] Example 3

[0043] The difference from Example 1 is that the initial rolling temperature is 420°C and the final rolling temperature is 310°C.

[0044] Example 4

[0045] The difference from Example 1 is that the high-purity aluminum wire rod is subjected to 7 coarse drawing processes to a diameter of 2.6 mm.

[0046] Example 5

[0047] The difference from Example 1 is that the high-purity aluminum wire rod is precision drawn to a diameter of 2.2mm.

[0048] Example 6

[0049] The difference from Example 1 is that the high-purity aluminum wire rod is subjected to three wire scraping processes to a diameter of 1.9 mm.

[0050] Comparative Example 1

[0051] The difference from Example 1 is that the high-purity aluminum wire used for vacuum coating has the following chemical composition by mass percentage: Al 99.75%, Fe 0.06%, Si 0.05%, Cu 0.0015%, Mn 0.002%, Mg 0.0002%, Cr 0.001%, Zn 0.001%, V 0.001%, Ti 0.01%, Bi 0.001%, with the balance being unavoidable impurities.

[0052] Comparative Example 2

[0053] A method for preparing high-purity aluminum wire for vacuum coating includes the following steps:

[0054] (1) Add aluminum ingots to a smelting furnace to melt them into molten aluminum. Transfer the molten aluminum to a holding furnace for degassing. The furnace pressure is 0.1 MPa. Introduce Ar gas into the molten aluminum to obtain molten aluminum with a hydrogen content of 0.17 mL / 100 g.

[0055] (2) The aluminum liquid obtained in step (1) is continuously cast at 730°C using a casting machine to obtain a billet. The billet is then rolled at an initial rolling temperature of 500°C, a rolling speed of 2.2 m / s, and a final rolling temperature of 350°C to obtain a high-purity aluminum wire rod with a diameter of 10.0 mm.

[0056] (3) The high-purity aluminum wire rod obtained in step (2) is coarsely drawn four times to a diameter of 5.2 mm, annealed at 450°C for 2 hours, then finely drawn three times to a diameter of 2.2 mm and scraped twice to a diameter of 2.0 mm to obtain high-purity aluminum wire for vacuum coating.

[0057] In this comparative example, the chemical composition of the high-purity aluminum wire used for vacuum coating is the same as that in Example 2.

[0058] The properties of the high-purity aluminum wires for vacuum coating prepared in each embodiment and comparative example are shown in Table 1.

[0059] Table 1

[0060]

[0061] The high-purity aluminum wires prepared using the above embodiments and comparative examples were subjected to vacuum coating, with a coating vacuum degree higher than 10. -3 Pa, the substrate is 6μm PET, and a 1μm composite current collector aluminum film is deposited on the upper and lower surfaces of the PET. The performance of the resulting composite aluminum film in the TD direction is tested, and the results are shown in Table 2. The adhesion is achieved by sticking 3M tape to the surface of the aluminum film. If no aluminum foil falls off, it indicates that the adhesion meets the requirements.

[0062] Table 2

[0063]

[0064] This invention reduces the quantity and size of the second phase by controlling the content of metallic impurities in high-purity aluminum wire. Degassing the molten aluminum ensures a hydrogen content ≤0.10mL / 100g, resulting in lower impurity content in the high-purity aluminum wire. Controlling the initial and final rolling temperatures controls the oxide film thickness and grain size on the aluminum wire surface, avoiding intermediate annealing to prevent oxide film thickening. Drawing and scraping processes improve the strength and surface quality of the aluminum wire. These performance improvements reduce spattering during the vapor deposition process. The composite aluminum film obtained by vacuum vapor deposition exhibits excellent properties, with a sheet resistance ≤29mΩ / sq in the TD direction, a surface roughness Sa ≤0.18μm, a tensile strength ≥215MPa, and a pinhole rate ≤0.02ea / m. 2 The adhesion is achieved by using 3M tape to adhere the aluminum foil to the surface, with no aluminum foil falling off.

[0065] The foregoing descriptions have outlined some exemplary embodiments of the present invention. It is understood that these embodiments are merely illustrative and do not constitute a limitation on the scope of protection of the present invention. Features in these embodiments can be rearranged in suitable ways, and the resulting solutions remain within the scope of protection claimed by the present invention. All other embodiments obtained by those skilled in the art based on the foregoing embodiments without inventive effort, i.e., all modifications, equivalent substitutions, and improvements made within the spirit and principles of this application, fall within the scope of protection claimed by the present invention.

Claims

1. A method for preparing high-purity aluminum wire for vacuum coating, characterized in that, Includes the following steps: (1) Add aluminum ingots to a smelting furnace to melt them into molten aluminum. Transfer the molten aluminum to a holding furnace for degassing. The furnace pressure is 0.3-1.0 MPa. Introduce Ar gas into the molten aluminum to obtain molten aluminum with a hydrogen content ≤0.10 mL / 100 g. (2) The aluminum liquid obtained in step (1) is continuously cast using a casting machine at a casting temperature of 700-730℃ to obtain a billet. The oxide film on the surface of the billet is removed by scraping, and the billet is rolled at a rolling temperature of 400-450℃ and a final rolling temperature of 280-320℃ to obtain a high-purity aluminum wire rod. (3) The high-purity aluminum wire rod obtained in step (2) is subjected to 6-10 coarse drawing, 1-3 fine drawing and 2-3 scraping processes to obtain high-purity aluminum wire for vacuum coating. The chemical composition of the high-purity aluminum wire, by mass percentage, includes: Al 99.92-99.98%, Fe ≤0.005%, Si ≤0.004%, Cu ≤0.0001%, Mn ≤0.0001%, Mg ≤0.0002%, Cr ≤0.0001%, Zn ≤0.0001%, V ≤0.0001%, Ti ≤0.0008%, Bi ≤0.0001%, with the balance being unavoidable impurities; the surface roughness Sa of the high-purity aluminum wire is ≤0.2 μm, the oxide film thickness is ≤100 nm, the conductivity is ≥64.2% IACS, and the tensile strength is 140-160 MPa; the high-purity aluminum wire contains the intermetallic compound AlFeSi phase, which is granular with a size ≤2 μm.

2. The method for preparing high-purity aluminum wire for vacuum coating according to claim 1, characterized in that, In step (2), continuous casting adopts zoned automatic water pressure control.

3. The method for preparing high-purity aluminum wire for vacuum coating according to claim 1, characterized in that, The diameter of the high-purity aluminum wire rod mentioned in step (2) is 8-10 mm.

4. The method for preparing high-purity aluminum wire for vacuum coating according to claim 1, characterized in that, The rolling speed in step (2) is 2-5 m / s.

5. The method for preparing high-purity aluminum wire for vacuum coating according to claim 1, characterized in that, In step (3), the diameter of the aluminum wire after coarse drawing is 2.6-2.8 mm, the diameter of the aluminum wire after fine drawing is 2.1-2.2 mm, and the diameter of the aluminum wire after scraping is 1.8-2.0 mm.

6. A high-purity aluminum wire for vacuum coating prepared by any one of the methods described in claims 1-5.

7. A composite current collector aluminum film vacuum-deposited using the high-purity aluminum wire for vacuum coating as described in claim 6.

8. The composite current collector aluminum film according to claim 7, characterized in that, The composite aluminum film exhibits a sheet resistance ≤29 mΩ / sq in the TD direction, a surface roughness Sa≤0.18 μm, a tensile strength ≥215 MPa, and a pinhole rate ≤0.02 ea / m. 2 The adhesion is achieved by using 3M tape to adhere the aluminum foil to the surface, with no aluminum foil falling off.

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