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CN-122025423-A - Preparation method of aluminum powder sintered foil based on thermal expansion coefficient adaptation

CN122025423ACN 122025423 ACN122025423 ACN 122025423ACN-122025423-A

Abstract

The invention relates to the technical field of aluminum electrolytic capacitor anode foil manufacturing, in particular to a preparation method of aluminum powder sintered foil based on thermal expansion coefficient adaptation. The invention mainly selects oxides with the thermal expansion coefficient difference of more than or equal to 10 multiplied by 10 ‑6 /DEG C according to the thermal expansion coefficient difference of aluminum powder and different oxides and the physical/chemical inertia under sintering treatment, uniformly mixes the screened oxides with aluminum powder, a binder and a solvent to form aluminum powder slurry, coats the aluminum powder slurry on the aluminum foil to obtain coated aluminum foil, and carries out sintering treatment on the coated aluminum foil under protective atmosphere to obtain the aluminum powder sintered foil with excellent mechanical properties. According to the invention, by adding the oxide with low thermal expansion coefficient, the shrinkage difference of aluminum and the oxide is utilized to induce uniform microcrack network to release stress, so that the problems of poor bending strength, reduced specific volume, complex process and poor environmental protection in the prior art are solved.

Inventors

  • CHEN ZHAO
  • YANG CHUNYI

Assignees

  • 安路密能(扬州)科技有限公司

Dates

Publication Date
20260512
Application Date
20260212

Claims (8)

  1. 1. The preparation method of the aluminum powder sintered foil based on the thermal expansion coefficient adaptation is characterized by comprising the following steps of: Selecting an oxide with the thermal expansion coefficient difference of more than or equal to 10 multiplied by 10 -6 /DEG C according to the thermal expansion coefficient difference of aluminum powder and different oxides and the physical/chemical inertia under sintering treatment; Uniformly mixing the screened oxide with aluminum powder, a binder and a solvent to form aluminum powder slurry, and coating the aluminum powder slurry on an aluminum foil to obtain a coated aluminum foil; And sintering the coated aluminum foil in a protective atmosphere to obtain the aluminum powder sintered foil with the adaptive thermal expansion coefficient.
  2. 2. The preparation method of the aluminum powder sintered foil based on the thermal expansion coefficient adaptation, which is characterized by comprising the steps of treating at 100-200 ℃ for 1-5 h, continuously heating to 400-450 ℃ for 1-6 h, and continuously heating to 500-600 ℃ for 1-100 h.
  3. 3. The preparation method of the aluminum powder sintered foil based on the thermal expansion coefficient adaptation as claimed in claim 1, wherein the aluminum powder slurry is prepared by mixing the following raw materials in percentage by mass: 45% -70% of aluminum powder, 0.5% -5% of oxide, 1% -10% of binder, 15% -53.5% of solvent and 100% of total.
  4. 4. The method for producing a sintered aluminum powder foil based on thermal expansion coefficient adaptation according to claim 3, wherein the particle size of the aluminum powder is 1 μm to 10 μm and the particle size of the oxide is 0.05 μm to 2 μm.
  5. 5. The method for producing an aluminum powder sintered foil based on the thermal expansion coefficient adaptation according to claim 1, wherein the thermal expansion coefficient of the aluminum powder is larger than that of the oxide.
  6. 6. The method for producing a sintered aluminum powder foil based on the thermal expansion coefficient adaptation according to claim 1 or 5, wherein the oxide is at least one of SiO 2 、Al 2 TiO 5 、TiO 2 and ZrO 2 .
  7. 7. The preparation method of aluminum powder sintered foil based on thermal expansion coefficient adaptation according to claim 1, wherein the binder is any one of methylcellulose, polyethylene glycol, polyvinyl alcohol and polypyrrolidone, and the solvent is any one of water, ethanol and N-methylpyrrolidone.
  8. 8. The preparation method of the aluminum powder sintered foil based on the thermal expansion coefficient adaptation, which is disclosed in claim 1, is characterized in that the protective atmosphere is nitrogen or argon, and the flow rate of the protective atmosphere is 5L/min-50L/min.

Description

Preparation method of aluminum powder sintered foil based on thermal expansion coefficient adaptation Technical Field The invention relates to the technical field of aluminum electrolytic capacitor anode foil manufacturing, in particular to a preparation method of aluminum powder sintered foil based on thermal expansion coefficient adaptation. Background The traditional aluminum powder sintered foil is generally prepared by adopting an aluminum powder sintering process, and a three-dimensional network interpenetrating structure is formed by virtue of sintering necks formed among aluminum powder particles, so that the aluminum powder sintered foil can be used as an aluminum electrode foil to be applied to assembling an aluminum electrolytic capacitor. Although the traditional aluminum powder sintered foil has higher tensile strength of 18-25 MPa due to the three-dimensional network interpenetrating structure, under the repeated bending working condition, stress is easily concentrated on a sintered neck, so that the bending resistance is poor, the bending times of 90 degrees are generally less than 30 times, and the severe requirements of high reliability and long service life on the high bending strength of the anode foil of the aluminum electrolytic capacitor are difficult to meet. In the prior art, the bending performance of aluminum powder sintered foil is tried to be improved mainly by regulating and controlling the grain size distribution of the aluminum powder, optimizing the sintering process or adding a pore-forming agent. For example, patent application CN120954888a improves bending performance to a certain extent by adjusting the particle size distribution of aluminum powder to optimize stacking and connection state, but introducing large particle size aluminum powder significantly reduces the effective particle number and contact point per unit volume, typically resulting in a reduction of 15% -25% in foil specific volume. The patent application CN119252669A adopts a sectional sintering method, and the growth of a sintering neck is regulated and controlled by precisely controlling the multi-section heating rate, so that the bending performance is improved to a certain extent, but the method has the advantages of complex process, narrow process window, extremely high requirements on equipment and control precision, large mass production difficulty and difficulty in realizing industrialization. Patent application CN120149066A decomposes to form pores by adding ammonium bicarbonate pore-forming agent to release stress, improves bending performance to a certain extent, but the decomposition process can produce Volatile Organic Compounds (VOCs) pollution, has environmental protection hidden danger, and residual impurities can possibly introduce insulation defects, thereby affecting the electrical property of the foil. Disclosure of Invention The invention provides a preparation method of aluminum powder sintered foil based on thermal expansion coefficient adaptation, which aims to solve the problems of poor bending strength, reduced specific volume, complex process or poor environmental protection in the prior art. According to the invention, a microcrack network is induced by a Coefficient of Thermal Expansion (CTE) adaptation principle, so that the bending strength of the aluminum powder sintered foil is remarkably improved on the premise of not reducing specific volume, being simple in process and environment-friendly and free of VOCs, and meanwhile, the requirements of high bending strength, high specific volume and green production are met. In order to achieve the above object, the technical scheme of the present invention is as follows. The invention provides a preparation method of aluminum powder sintered foil based on thermal expansion coefficient adaptation, which comprises the following steps: According to the difference of the thermal expansion coefficients of aluminum powder and different oxides and the physical/chemical inertia under sintering treatment, the oxide with the thermal expansion coefficient difference of more than or equal to 10 multiplied by 10 -6/DEG C is preferred, the screened oxide, aluminum powder, a binder and a solvent are uniformly mixed to form aluminum powder slurry, the aluminum powder slurry is coated on the aluminum foil to obtain coated aluminum foil, and the coated aluminum foil is subjected to sintering treatment under a protective atmosphere to obtain the aluminum powder sintered foil with the thermal expansion coefficient being adapted. Preferably, the sintering treatment method comprises the steps of treating for 1-5 hours at 100-200 ℃, continuously heating to 400-450 ℃ for 1-6 hours, and continuously heating to 500-600 ℃ for 1-100 hours. Preferably, the protective atmosphere is nitrogen or argon, and the flow rate of the protective atmosphere is 5L/min-50L/min. In the invention, the heat preservation time of the sintering treatment is adjusted according to