Preparation method of high-thermal-conductivity aluminum alloy

Abstract

The invention belongs to the technical field of aluminum alloy material preparation, and particularly relates to a preparation method of a high-thermal-conductivity aluminum alloy. In order to effectively solve the problem of insufficient heat dissipation performance of the aluminum alloy, the invention discloses a powder shot blasting strategy of the aluminum alloy, the strategy is based on a shot blasting technology, copper powder, silver powder, graphene and other high-thermal-conductivity powder are added to implement surface modification, and the powder and an aluminum matrix form metallurgical bonding by means of short-circuit diffusion, so that the heat dissipation performance of the aluminum alloy is improved. The problem of interface mismatching of a traditional heat-conducting coating is solved. Meanwhile, the thermal conductivity is improved through the high thermal conductivity layer and the electronic skin effect, the mechanical property is strengthened based on fine grain strengthening, the corrosion resistance is improved through a gradient nano structure formed on the surface layer, and finally the thermal conductivity, the strength and the corrosion resistance of the aluminum alloy are synchronously improved.

Description

Technical Field

[0001] This invention belongs to the field of aluminum alloy material preparation technology, specifically relating to a method for preparing a high thermal conductivity aluminum alloy. Background Technology

[0002] Aluminum alloys possess advantages such as lightweight, high thermal conductivity, low cost, and excellent corrosion resistance, making them widely used in applications requiring heat dissipation, such as automotive radiators, air conditioning condenser pipes, and server heat sinks. Commonly used heat dissipation aluminum alloys include Al-Si cast aluminum alloys, 3-series wrought aluminum alloys, and 6-series wrought aluminum alloys. However, the strength of heat dissipation aluminum alloys is not high, generally failing to exceed 200 MPa. Increasing strength by increasing wall thickness or adding reinforcing ribs not only increases component weight but may also reduce heat dissipation performance. Furthermore, in corrosive media and under long-term use, aluminum alloy heat sinks are prone to pitting corrosion and stress corrosion fatigue cracks, leading to perforation, shortened service life, and decreased reliability. Furthermore, the thermal conductivity of aluminum alloys has inherent limitations, typically ranging from 130 to 200 W / (m·K) (see: Kentaro F. Lunn, Diran Apelian. Thermal and Electrical Conductivity of Aluminum Alloys: Fundamentals, structure-property relations, and pathways to enhance conductivity[J]. Materials Science and Engineering: A, 2025, 924: 147766.), which is insufficient to meet the needs of applications requiring high heat dissipation. Higher-cost aluminum-based composite heat sinks or copper-based heat sinks are necessary to meet these requirements.

[0003] Currently, strategies for improving the thermal conductivity of aluminum alloys mainly include three categories: alloying, heat treatment, and thermally conductive coatings. Alloying and heat treatment can improve the intrinsic thermal conductivity of aluminum alloys, but the improvement is limited and constrained by the inverse relationship between performance and thermal conductivity. Furthermore, adjusting the composition requires a series of process optimizations, making practical implementation difficult. While thermally conductive coatings can improve the heat dissipation of aluminum alloys, the significant interface between the coating and the substrate can lead to coating peeling over long-term use due to the mismatch in their thermal expansion coefficients. Although cast aluminum alloys can reduce the production cost of radiators, they are prone to metallurgical porosity, a defect that hinders the market acceptance of cast aluminum alloy radiators.

[0004] To address the aforementioned issues, there is an urgent need to develop a novel strategy to improve the thermal conductivity of aluminum alloys, thereby effectively resolving the pain point of insufficient heat dissipation performance of aluminum alloys. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, this invention proposes a powder shot peening strategy for aluminum alloys. This strategy employs shot peening technology and adds powders with high thermal conductivity (metal powder, ceramic powder, etc.) during the shot peening process to modify the surface of the aluminum alloy, thereby achieving a simultaneous improvement in the thermal conductivity, strength, and corrosion resistance of the aluminum alloy.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: This invention provides a method for preparing a high thermal conductivity aluminum alloy, the method comprising the following steps: S1. First, sand the surface of the aluminum alloy sample with sandpaper, clean it with ethanol to remove surface oxides, and ensure that the surface is flat; then, perform ultrasonic cleaning on the sanded sample to remove surface oil and other residues; finally, apply high thermal conductivity powder to the surface of the aluminum alloy sample to obtain better results after treatment. S2. Pour the shot peening pellets into a sealed bag containing high thermal conductivity powder and shake it thoroughly to mix with the high thermal conductivity powder. S3. Add a certain amount of high thermal conductivity powder into the shot peening chamber, and use the shot peening pellets mixed with the high thermal conductivity powder to perform shot peening on the sample whose surface is coated with the high thermal conductivity powder, and thus obtain the desired result.

[0007] Preferably, the high thermal conductivity powder is a powder with a thermal conductivity greater than 200 W / m·K and a powder diameter between 1 μm and 50 μm, including metal powder and ceramic powder. That is, it also includes other types of high thermal conductivity powders.

[0008] More preferably, the metal powder includes copper powder and silver powder, and the ceramic powder includes graphene, boron nitride, and diamond.

[0009] Preferably, the aluminum alloy includes cast aluminum alloy and wrought aluminum alloy (such as 6063 aluminum alloy).

[0010] Preferably, the shot peening pellets are made of metal, ceramic or glass, with a particle size between 0.1 mm and 3 mm.

[0011] Preferably, the shot peening technology used in the shot peening process includes pneumatic shot peening, ultrasonic shot peening, and laser shot peening.

[0012] Preferably, the shot peening temperature is from liquid nitrogen temperature (approximately -196°C) to 500°C.

[0013] Compared with the prior art, the beneficial effects of the present invention are: This invention proposes a powder peening modification strategy for aluminum alloys, which can simultaneously improve the thermal conductivity, mechanical strength, and corrosion resistance of aluminum alloys. This strategy is based on shot peening technology, adding high thermal conductivity powders during the shot peening process to modify the surface of the aluminum alloy. The selected high thermal conductivity powders include metal powders such as copper powder and silver powder, ceramic powders such as graphene, boron nitride, and diamond, as well as other types of high thermal conductivity powders. When modifying aluminum alloys using this strategy, the high thermal conductivity powders can form a metallurgical bond with the aluminum matrix under the action of short-circuit diffusion, effectively solving the interface mismatch problem of traditional thermally conductive coatings. Simultaneously, relying on the construction of a high thermal conductivity layer and the electron skin effect, this invention can significantly improve the thermal conductivity of aluminum alloys, breaking through their thermal conductivity limits. Based on the principle of fine grain strengthening, the mechanical properties of aluminum alloys treated by this powder peening process are greatly enhanced, with a particularly significant improvement in surface hardness. Moreover, a gradient nanostructure can be formed on the surface of the aluminum alloy after treatment, resulting in a simultaneous improvement in its corrosion resistance. Furthermore, if cast aluminum is used as the matrix, the multiple bombardments during the shot peening process can close the metallurgical pores inside the cast aluminum alloy, further improving the material's density and reliability. Attached Figure Description

[0014] Figure 1 Photos of 6063 aluminum alloys: untreated, copper powder peened, and graphene powder peened.

[0015] Figure 2 Infrared camera thermal images of untreated, copper powder-peened, and graphene powder-peened 6063 aluminum alloys heated on a 200℃ heating stage for 5 s. Compared with the untreated sample, the copper powder-peened and graphene powder-peened samples showed higher temperatures after 5 s heating, indicating that they have a faster thermal conductivity.

[0016] Figure 3 The graph shows a comparison of the thermal conductivity of 6063 aluminum alloy at room temperature (25℃) before and after shot peening with copper powder and graphene powder. It shows that the thermal conductivity of the material increased by more than 30% after shot peening.

[0017] Figure 4 The microhardness change of 6063 aluminum alloy after shot peening with copper powder is shown in the Vickers hardness-depth curve. Depth refers to the distance from the treated surface of the sample. The results show that shot peening increases the microhardness of the sample surface by more than 20%. Detailed Implementation

[0018] The specific embodiments of the present invention will be further described below. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0019] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, and the experimental materials used in the following embodiments are all available through conventional commercial channels.

[0020] This invention provides a method for preparing a high thermal conductivity aluminum alloy, the method comprising the following steps: (1) Sample preparation: The surface of the aluminum alloy sample was polished with silicon carbide sandpaper and then cleaned with anhydrous ethanol to remove surface oxides and ensure the surface is flat. The polished sample was ultrasonically cleaned to remove surface oil and other residues. Finally, high thermal conductivity powder was applied to the surface of the aluminum alloy sample to obtain better results after treatment.

[0021] (2) Powder mixing: Pour the shot peening pellets into a sealed bag containing high thermal conductivity powder and shake thoroughly to mix. The powder can be graphene powder, pure copper powder, diamond powder, boron nitride powder, or other powders with a thermal conductivity greater than 200 W / m·k.

[0022] (3) Shot peening: The sample is shot peened using shot pellets mixed with high thermal conductivity powder. Shot peening techniques include pneumatic shot peening, ultrasonic shot peening, and laser shot peening. The treatment temperature can be room temperature, high temperature, or low temperature. The shot peening material can be metal, ceramic, or glass pellets. After completion, a high thermal conductivity and high strength aluminum alloy is obtained.

[0023] To fully and clearly present the technical solution and significant advantages of the present invention, the present invention will be described in detail below with reference to specific embodiments.

[0024] Example: This embodiment provides a method for preparing a high thermal conductivity and high strength 6063 aluminum alloy, specifically including the following steps: (1) Pretreatment of the sample: The sample used is commercially available 6063 aluminum alloy. The sample is cut into round pieces with a thickness of 1 mm and a diameter of 25 mm. It is polished with 600-mesh silicon carbide sandpaper for about 1 min. The polished sample is then ultrasonically treated with anhydrous ethanol for 10 min and dried. Finally, graphene powder (particle size about 7~10 μm) or pure copper powder (particle size about 45 μm) is evenly coated on the surface of the sample.

[0025] (2) Pretreatment of shot peening: Select carbon steel shot with a diameter of 3 mm, pour the shot peening shot into a sealed bag containing graphene or pure copper powder, and shake it thoroughly to mix it evenly with the graphene or pure copper powder.

[0026] (3) Ultrasonic shot peening of the sample: The ultrasonic shot peening device was model JY-P20, manufactured by Suzhou SONIC. The workpiece was attached to the bottom of the adjustable sample rod with adhesive tape, and its height was adjusted according to the actual processing intensity. The shot peening parameters were set as follows: shot peening distance 20 mm, frequency 20 kHz, amplitude 7 μm, shot peening time 5 min, and temperature room temperature (25℃). Before the shot peening process began, a certain amount of graphene or pure copper powder was added to the shot peening chamber. The sample surface to be treated was a circle with a diameter of 3 cm, and the amount of copper powder required was 1 g.

[0027] (4) After shot peening, the sample is removed and simply cleaned with anhydrous ethanol to obtain a 6063 aluminum alloy sample with high thermal conductivity and high strength. Figure 1 Tests showed that the microhardness of the outermost layer increased to 106 HV after treatment, a 32% increase compared to the untreated sample (measured at approximately 80 HV). Figure 4 Thermal conductivity increased by 23% (219.6 W / (m·K) for copper powder shot peening and 224.3 W / (m·K) for graphene powder shot peening); Figure 2 ,3). Among them, the thermal conductivity broke through the theoretical limit of aluminum alloy thermal conductivity (200 W / (m·K)).

[0028] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A method for preparing a high thermal conductivity aluminum alloy, characterized in that, Includes the following steps: S1. First, sand the surface of the aluminum alloy sample with sandpaper, clean it with ethanol to remove surface oxides, and ensure that the surface is flat; then, perform ultrasonic cleaning on the sanded sample to remove surface oil and other residues; finally, apply high thermal conductivity powder to the surface of the aluminum alloy sample. S2. Pour the shot peening pellets into a sealed bag containing high thermal conductivity powder and shake it thoroughly to mix with the high thermal conductivity powder. S3. Add a certain amount of high thermal conductivity powder into the shot peening chamber, and use the shot peening pellets mixed with the high thermal conductivity powder to perform shot peening on the sample whose surface is coated with the high thermal conductivity powder, and thus obtain the desired result.

2. The method for preparing a high thermal conductivity aluminum alloy according to claim 1, characterized in that, The high thermal conductivity powder is a powder with a thermal conductivity greater than 200 W / m·k and a powder diameter between 1μm and 50μm, including metal powder and ceramic powder.

3. The method for preparing a high thermal conductivity aluminum alloy according to claim 2, characterized in that, The metal powder includes copper powder and silver powder, and the ceramic powder includes graphene, boron nitride, and diamond.

4. The method for preparing a high thermal conductivity aluminum alloy according to claim 1, characterized in that, The aluminum alloys include cast aluminum alloys and wrought aluminum alloys.

5. The method for preparing a high thermal conductivity aluminum alloy according to claim 1, characterized in that, The shot peening pellets are made of metal, ceramic or glass, with a particle size between 0.1 mm and 3 mm.

6. The method for preparing a high thermal conductivity aluminum alloy according to claim 1, characterized in that, The shot peening techniques used in the shot peening process include pneumatic shot peening, ultrasonic shot peening, and laser shot peening.

7. The method for preparing a high thermal conductivity aluminum alloy according to claim 1, characterized in that, The shot peening treatment is performed at a temperature ranging from liquid nitrogen temperature to 500°C.

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