Hot rolling preparation process for low-voltage anode foil of aluminum electrolytic capacitor

Abstract

The invention discloses a hot rolling preparation process for a low-voltage anode foil of an aluminum electrolytic capacitor, relates to the field of preparation of low-voltage anode foils, and aims to solve the problem that the service life of the low-voltage anode foil is relatively short due to the fact that the surface of the existing low-voltage anode foil is easy to corrode when the existing low-voltage anode foil is used in a special environment due to relatively poor uniformity in the prior art. The low-voltage anode foil hot rolling preparation process comprises the following steps: S1, raw material selection: adopting a high-purity aluminum ingot of which the purity is greater than or equal to 99.995% as a main raw material, and adding three trace elements of copper, magnesium and silicon; s2, mixing and stirring; s3, smelting and refining; S4, semi-continuous casting; s5, carrying out homogenization treatment; and S6, a hot rolling process, a large-small-large reduction strategy is adopted, the total reduction of hot rolling is controlled between 78% and 89%, a high-purity aluminum ingot is used as a main raw material, the addition amount of trace elements such as copper, magnesium and silicon is accurately controlled, and fine hot rolling, cold rolling and foil rolling processes are combined, so that the mechanical property and corrosion resistance of the material are enhanced, and the service life of the material is prolonged. And the problem that the low-voltage anode foil is easy to corrode in a special environment is effectively solved.

Description

Technical Field

[0001] The invention relates to the field of low-voltage anode foil preparation, in particular to a hot-rolling preparation process for low-voltage anode foil for aluminum electrolytic capacitors. Background Art

[0002] Low-voltage anode foil is an important component of electrolytic capacitors, specifically aluminum foil materials used as anodes. This aluminum foil undergoes a series of precise processing techniques, including etching and anodizing, and is ultimately transformed into a chemical foil with specific functions. In electrolytic capacitors, the main function of low-voltage anode foil is to store charge, and its performance directly affects the capacity, loss, and service life of the capacitor. According to the voltage classification standard, the operating voltage range of low-voltage anode foil is usually between 7.7V and 170V, and it is suitable for various low-voltage electronic devices. Its unique sponge-like corrosion morphology, after a finely controlled corrosion process, greatly increases the surface area of ​​the aluminum foil, thereby increasing the electrostatic capacity of the capacitor. In addition, low-voltage anode foil also has good conductivity and chemical stability, and can maintain stable performance in harsh working environments. In the capacitor manufacturing process, the quality and technical level of low-voltage anode foil have a decisive influence on the performance of the capacitor. Therefore, when selecting low-voltage anode foil, it is necessary to strictly consider its material composition, processing technology, and performance parameters to ensure the quality and reliability of the capacitor.

[0003] The existing low-voltage anode foil has poor uniformity and is easily corroded when used in special environments, resulting in a low service life of the low-voltage anode foil. Therefore, the market urgently needs to develop a hot-rolled preparation process for low-voltage anode foil for aluminum electrolytic capacitors to help people solve the existing problems. Summary of the invention

[0004] The purpose of the present invention is to provide a hot rolling preparation process for low-voltage anode foil of aluminum electrolytic capacitors to solve the problem that the existing low-voltage anode foil has poor uniformity and is easily corroded when used in special environments, resulting in a short service life of the low-voltage anode foil.

[0005] To achieve the above object, the present invention provides the following technical solution: a hot rolling preparation process for low-voltage anode foil of aluminum electrolytic capacitor, characterized in that the hot rolling preparation process for low-voltage anode foil comprises the following steps:

[0006] S1 raw material selection, using high-purity aluminum ingots with a purity of ≥99.995% as the main raw material and adding three trace elements of copper, magnesium and silicon;

[0007] S2: Mixing and stirring, refining the high-purity aluminum ingot into particles through a crushing device, and then evenly mixing the copper, magnesium, silicon raw materials with the granular aluminum raw materials through a stirring device;

[0008] S3 smelting and refining, adding the mixed raw materials into a high-frequency induction smelting furnace, mixing the main material with trace elements for smelting, and using flotation, filtration, and inert gas purging to remove impurities in the solution during smelting;

[0009] S4 semi-continuous casting, after refining, the raw materials are cast into shape by a vibration casting device. During casting, electromagnetic stirring is used to optimize the internal structure of the ingot, reduce segregation and pores, and strictly control parameters such as casting speed and cooling water volume;

[0010] S5 homogenization treatment: after the ingot is cast, it is placed in a homogenization device for high-temperature homogenization to ensure that the alloy elements are fully diffused. While the ingot is homogenized, nitrogen or argon is filled into the homogenization device to make the ingot be homogenized under the protection of nitrogen or argon;

[0011] S6 hot rolling process, hot rolling the ingot with hot rolling equipment, and adopting the "large-small-large" reduction strategy: the initial pass adopts a larger reduction of ≥16%, the mid-term pass reduces the reduction by ≤10%, and the final pass increases the reduction again by ≥12%. The total hot rolling reduction is controlled between 78% and 89%, which is completed in 22 to 25 passes;

[0012] S7 cold rolling and foil rolling are carried out at room temperature, with the total reduction rate controlled between 22% and 28% to maintain the surface finish of the plate and strip. After cold rolling, a high-precision foil rolling mill is used for foil rolling, and the final foil thickness is controlled between 0.08mm and 0.10mm;

[0013] S8 annealing, annealing the foil after foil rolling under nitrogen or argon protection, and cooling it by forced air cooling or water mist cooling rapid cooling technology;

[0014] S9 surface treatment, first use environmentally friendly etching solution to micro-etch the surface of the foil to increase the surface area, and then form a dense oxide film on the surface of the foil by electrolysis.

[0015] Preferably, in the S1 raw material, the copper addition amount is 0.02%-0.12%, the magnesium addition amount is 0.01%-0.1%, and the silicon addition amount is 0.04%-0.25%.

[0016] Preferably, in the S5 homogenization treatment, the homogenization treatment temperature is set to 595° C. to 615° C., and the insulation time is 9 to 11 hours.

[0017] Preferably, in the S6 hot rolling process, the hot rolling inlet temperature of the hot rolling device is maintained at 425°C to 435°C, and the hot rolling device outlet temperature is not lower than 350°C.

[0018] Preferably, a high-efficiency water-based lubricant is used in the S6 hot rolling process, and an intelligent spray cooling device is simultaneously adopted.

[0019] Preferably, the foil rolling in the S7 cold rolling and foil rolling adopts a high-precision foil rolling mill, accurately controlling the roller gap ≤ 0.012 mm and the rolling speed ≤ 1000 m / min, and achieving a thickness uniformity of ≤ ± 2.5%.

[0020] Preferably, in the S8 annealing, the annealing temperature is selected from 365° C. to 380° C., and the holding time is 7 to 10 hours to eliminate work hardening.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) In this invention, high-purity aluminum ingots are used as the main raw material, and the addition of trace elements such as copper, magnesium, and silicon is precisely controlled to effectively improve the composition distribution of the material. Combined with fine hot rolling, cold rolling and foil rolling processes, especially the "large-small-large" reduction strategy used in the hot rolling process, the microstructure of the material is further optimized, and the uniformity and density of the low-voltage anode foil are significantly improved. This optimization not only reduces the defects and pores inside the material, but also enhances the mechanical properties and corrosion resistance of the material, thereby effectively solving the problem that the existing low-voltage anode foil is prone to corrosion and has a short service life under special environments.

[0023] (2) In the invention, in the hot rolling process, the present invention adopts a high-efficiency water-based lubricant and an intelligent spray cooling device. The application of these innovative technologies not only reduces the friction loss and energy consumption during the rolling process, but also optimizes the microstructure of the material, such as grain refinement and uniform organization. The optimization of these microstructures helps to improve the mechanical properties and surface quality of the low-voltage anode foil, further extending the service life of the capacitor. At the same time, by accurately controlling the reduction amount and temperature during the hot rolling process, the material properties are precisely regulated, meeting the high performance requirements of the capacitor for the low-voltage anode foil.

[0024] (3) In the present invention, through strict annealing and surface treatment processes, the work hardening phenomenon is eliminated and the plasticity of the material is restored. At the same time, a dense oxide film is formed on the surface of the foil. This film not only improves the corrosion resistance of the low-voltage anode foil, but also enhances its wettability with the electrolyte. This improvement in wettability helps the capacitor to store and release charges more effectively during the charging and discharging process, thereby improving the electrostatic capacity and stability of the capacitor. In addition, this dense oxide film also plays a role in protecting the substrate, further extending the service life of the low-voltage anode foil. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A preparation flow chart of a hot rolling preparation process for a low-voltage anode foil for an aluminum electrolytic capacitor according to the present invention; DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0027] See also Figure 1 , an embodiment provided by the present invention: a hot rolling preparation process for low-voltage anode foil of aluminum electrolytic capacitor, characterized by comprising the following steps:

[0028] S1 Raw material selection: High-purity aluminum ingots with a purity of ≥99.995% are used as the main raw material, and three trace elements of copper, magnesium and silicon are added. The addition amount of copper is 0.02%-0.12%, the addition amount of magnesium is 0.01%-0.1%, and the addition amount of silicon is 0.04%-0.25%. This raw material ratio not only improves the corrosion resistance, strength and processability of the material, but also lays a solid foundation for the optimization of subsequent processes;

[0029] S2 Mixing and stirring: The high-purity aluminum ingot is refined into particles by a crushing device, and then the copper, magnesium, silicon raw materials and the granular aluminum raw materials are mixed evenly by an efficient stirring device;

[0030] S3 smelting and refining: adding the mixed raw materials into a high-frequency induction melting furnace, mixing the main material with trace elements for smelting, and using flotation, filtration, and inert gas purging to remove impurities in the solution during smelting to improve the purity of the alloy;

[0031] S4 semi-continuous casting: The refined raw materials are cast into shape through a vibration casting device. During casting, electromagnetic stirring is used to optimize the internal structure of the ingot, reduce segregation and pores, and at the same time, parameters such as casting speed and cooling water volume are strictly controlled to ensure the quality of the ingot;

[0032] S5 Homogenization treatment: The ingot is placed in the homogenization device for high-temperature homogenization treatment. The homogenization treatment temperature is set at 595°C to 615°C and the holding time is 9 to 11 hours to ensure that the alloy elements are fully diffused and the uniformity and stability of the material are improved. At the same time, nitrogen or argon is filled into the homogenization device during the homogenization process to make the ingot undergo homogenization treatment under the protection of nitrogen or argon to prevent oxidation;

[0033] S6 hot rolling process: the ingot is hot rolled by a hot rolling device, the hot rolling inlet temperature of the hot rolling device is maintained at 425℃ to 435℃, and the hot rolling device outlet temperature is not less than 350℃, to ensure that the material has good plasticity and deformation ability, and adopt a "large-small-large" reduction strategy, that is, a larger reduction of ≥16% is used in the initial pass to promote grain refinement, the reduction is reduced by ≤10% in the mid-term pass to maintain the stability of the plate shape, and the reduction is increased again by ≥12% in the final pass to optimize the surface quality. The total hot rolling reduction is controlled between 78% and 89%, which is completed in 22 to 25 passes. At the same time, high-efficiency water-based lubricants are used in the hot rolling process to reduce friction and energy consumption, and intelligent spray cooling devices are used simultaneously to adjust the cooling intensity in real time according to the rolling temperature to avoid overheating and resulting in coarsening of the structure;

[0034] S7 cold rolling and foil rolling: cold rolling and foil rolling are carried out at room temperature, with the total reduction rate controlled between 22% and 28% to maintain the surface finish of the plate and strip. After cold rolling, a high-precision foil rolling mill is used for foil rolling, with the roll gap ≤0.012mm and the rolling speed ≤1000m / min precisely controlled to achieve thickness uniformity ≤±2.5%, and the final foil thickness is controlled between 0.08mm and 0.10mm;

[0035] S8 annealing: anneal the rolled foil under nitrogen or argon protection, the annealing temperature is selected from 365℃ to 380℃, and the holding time is 7 to 10 hours to eliminate work hardening and restore the plasticity of the material. The fast cooling technology of forced air cooling or water mist cooling is used to cool the foil to avoid grain growth.

[0036] S9 surface treatment: First, the foil surface is micro-etched with an environmentally friendly etching solution. This step not only increases the surface area of ​​the foil and improves its wettability with the electrolyte, but also forms a dense oxide film on the foil surface by electrolysis. This oxide film not only further improves the corrosion resistance of the foil, but also significantly improves its electrochemical performance, providing a more reliable quality guarantee for the low-voltage anode foil of aluminum electrolytic capacitors.

[0037] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A hot rolling preparation process for low-voltage anode foil of aluminum electrolytic capacitor, characterized in that: The hot rolling process steps for preparing low-voltage anode foil are as follows: S1 raw material selection, using high-purity aluminum ingots with a purity of ≥99.995% as the main raw material and adding three trace elements of copper, magnesium and silicon; S2: Mixing and stirring, refining the high-purity aluminum ingot into particles through a crushing device, and then evenly mixing the copper, magnesium, silicon raw materials with the granular aluminum raw materials through a stirring device; S3 smelting and refining, adding the mixed raw materials into a high-frequency induction smelting furnace, mixing the main material with trace elements for smelting, and using flotation, filtration, and inert gas purging to remove impurities in the solution during smelting; S4 semi-continuous casting, after refining, the raw materials are cast into shape by a vibration casting device. During casting, electromagnetic stirring is used to optimize the internal structure of the ingot, reduce segregation and pores, and strictly control parameters such as casting speed and cooling water volume; S5 homogenization treatment: after the ingot is cast, it is placed in a homogenization device for high-temperature homogenization to ensure that the alloy elements are fully diffused. While the ingot is homogenized, nitrogen or argon is filled into the homogenization device to make the ingot be homogenized under the protection of nitrogen or argon; S6 hot rolling process, hot rolling the ingot with hot rolling equipment, and adopting the "large-small-large" reduction strategy: the initial pass adopts a larger reduction of ≥16%, the mid-term pass reduces the reduction by ≤10%, and the final pass increases the reduction again by ≥12%. The total hot rolling reduction is controlled between 78% and 89%, and is completed in 22 to 25 passes; S7 cold rolling and foil rolling are carried out at room temperature, with the total reduction rate controlled between 22% and 28% to maintain the surface finish of the plate and strip. After cold rolling, a high-precision foil rolling mill is used for foil rolling, and the final foil thickness is controlled between 0.08mm and 0.10mm; S8 annealing, annealing the foil after foil rolling under nitrogen or argon protection, and cooling it by forced air cooling or water mist cooling rapid cooling technology; S9 surface treatment, first use environmentally friendly etching solution to micro-etch the surface of the foil to increase the surface area, and then form a dense oxide film on the surface of the foil by electrolysis.

2. The hot rolling preparation process of low-voltage anode foil for aluminum electrolytic capacitor according to claim 1, characterized in that: In the S1 raw material selection, the copper addition amount is 0.02%-0.12%, the magnesium addition amount is 0.01%-0.1%, and the silicon addition amount is 0.04%-0.25%.

3. The hot rolling preparation process for low-voltage anode foil of aluminum electrolytic capacitor according to claim 1, characterized in that: In the S5 homogenization treatment, the homogenization treatment temperature is set at 595° C. to 615° C., and the insulation time is 9 to 11 hours.

4. The hot rolling preparation process for low-voltage anode foil of aluminum electrolytic capacitor according to claim 1, characterized in that: In the S6 hot rolling process, the hot rolling inlet temperature of the hot rolling device is maintained at 425°C to 435°C, and the hot rolling device outlet temperature is not less than 350°C.

5. The hot rolling preparation process for low-voltage anode foil of aluminum electrolytic capacitor according to claim 1, characterized in that: The S6 hot rolling process uses a high-efficiency water-based lubricant and simultaneously adopts an intelligent spray cooling device.

6. The hot rolling preparation process for low-voltage anode foil of aluminum electrolytic capacitor according to claim 1, characterized in that: The S7 cold rolling and foil rolling adopts a high-precision foil rolling mill to accurately control the roller gap ≤ 0.012 mm and the rolling speed ≤ 1000 m / min, achieving a thickness uniformity of ≤ ± 2.5%.

7. The hot rolling preparation process for low-voltage anode foil of aluminum electrolytic capacitor according to claim 1, characterized in that: In the S8 annealing, the annealing temperature is selected to be 365° C. to 380° C., and the holding time is 7 to 10 hours to eliminate work hardening.

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