Aluminum alloy brazing material and method of making same, brazing sheet and heat sink

Abstract

The application provides an aluminum alloy brazing material and a preparation method thereof, a brazing sheet and a heat sink. The preparation method of the aluminum alloy brazing material comprises the following steps: mixing and processing aluminum alloy powder and brazing agent powder to obtain a mixture; and performing ball milling treatment on the mixture, so that the brazing agent powder is embedded in the aluminum alloy powder to obtain the aluminum alloy brazing material. In the application, the brazing agent is embedded in the aluminum alloy matrix, the interface bonding capacity of the brazing agent powder and the aluminum alloy powder can be improved, the welding performance of the prepared aluminum alloy brazing material is improved, the subsequent rolling process is reduced, the yield of the brazing sheet is improved, and the preparation cost is reduced.

Description

Technical Field

[0001] This application relates to the field of aluminum alloy brazing, and more particularly to an aluminum alloy brazing material and its preparation method, a brazing plate and a heat sink. Background Technology

[0002] Aluminum alloy brazing plates are widely used in products such as automotive radiators due to their advantages such as low cost, light weight, good heat dissipation and corrosion resistance. Their typical structure is a "sandwich" type, usually with 3-series, 1-series or 6-series aluminum alloys as the core material and 4-series aluminum alloys as the outer shell.

[0003] To further improve welding quality, existing technologies incorporate a composite plate with pre-embedded flux between the core material and the shell. This composite plate is typically formed by hot isostatic pressing of a mixture of flux powder and aluminum-silicon powder, designed to release flux during brazing to break down the oxide film, thereby reducing flux usage, preventing residual blockage, and improving flux distribution uniformity.

[0004] However, flux powder is prone to agglomeration when mixed with aluminum alloy powder, resulting in uneven distribution within the composite plate and potentially causing incomplete or missed soldering. Furthermore, the poor interfacial bonding between the flux powder and aluminum alloy powder affects the overall stability of the composite plate, making it susceptible to cracking during subsequent rolling and lamination processes, ultimately compromising the welding effect.

[0005] Therefore, developing an aluminum alloy brazing material with strong interfacial bonding between flux powder and aluminum alloy powder, and improving the welding performance of aluminum alloy brazing materials, is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] This application provides aluminum alloy brazing materials and their preparation methods, brazing plates, and heat sinks, which can improve the interfacial bonding ability between flux powder and aluminum alloy powder in aluminum alloy brazing materials, improve the welding performance of aluminum alloy brazing materials, and effectively overcome the defects of the prior art.

[0007] One aspect of this application provides a method for preparing an aluminum alloy brazing material, comprising the following steps: mixing aluminum alloy powder and flux powder to obtain a mixture; ball milling the mixture to embed the flux powder into the aluminum alloy powder, thereby obtaining the aluminum alloy brazing material.

[0008] According to one embodiment of this application, the mixing process includes: adding the aluminum alloy powder, the flux powder, and the liquid dispersion medium into a ball mill, and performing the mixing process without the action of grinding beads to obtain the mixture; wherein, during the mixing process, the rotation speed of the ball mill is 50 r / min to 200 r / min, the mixing time is 30 min to 60 min, and the liquid dispersion medium includes acetone and / or ethanol.

[0009] According to one embodiment of this application, the ball milling process includes: ball milling the mixture under the action of grinding balls to embed the flux powder into the aluminum alloy powder to obtain the aluminum alloy brazing material; wherein the particle size of the grinding balls is 5mm~10mm; and the ratio of the mass of the grinding balls to the total mass of the aluminum alloy powder and the flux powder in the mixture is (8~10):1.

[0010] According to one embodiment of this application, during the ball milling process under the action of the ball milling beads, the ball milling is stopped when the aluminum alloy powder in the mixture accounts for more than 90% of the amount of the aluminum alloy powder to form a sheet-like aluminum alloy matrix, and the aluminum alloy brazing material is obtained; wherein, the average sheet diameter of the sheet-like aluminum alloy matrix is ​​20µm~600µm.

[0011] According to one embodiment of this application, the ball milling process under the action of the grinding balls is carried out in a ball mill, the rotation speed of the ball mill is 50 r / min to 400 r / min, and the ball milling time is 30 min to 300 min.

[0012] According to one embodiment of this application, the particle size Dv50 of the aluminum alloy powder is 10μm~300μm; and / or, the particle size Dv50 of the flux powder is 20μm~80μm.

[0013] According to one embodiment of this application, the mass ratio of the flux powder to the sum of the masses of the flux powder and the aluminum alloy powder is 1% to 20%; and / or, the aluminum alloy powder includes aluminum silicon powder, wherein the silicon content in the aluminum silicon powder is 7% to 13% by mass percentage, and the oxygen content is less than or equal to 500 ppm; and / or, the flux powder includes fluoroaluminate flux, wherein the fluoroaluminate flux includes potassium fluoroaluminate.

[0014] In another aspect, this application provides an aluminum alloy brazing material, which is prepared according to the above-described method for preparing aluminum alloy brazing materials; the aluminum alloy brazing material includes an aluminum alloy matrix and a flux embedded in the aluminum alloy matrix, wherein the aluminum alloy matrix includes a sheet-like aluminum alloy matrix with an average sheet diameter of 20 μm to 600 μm.

[0015] According to one embodiment of this application, in the aluminum alloy matrix, the proportion of the sheet-like aluminum alloy matrix is ​​greater than or equal to 90%; and / or, in the aluminum alloy brazing material, the mass percentage of the flux is 1% to 20%; and / or, the aluminum alloy matrix includes aluminum silicon powder, and the silicon content in the aluminum silicon powder is 7% to 13% and the oxygen content is less than or equal to 500 ppm by mass percentage; and / or, the flux includes fluoroaluminate flux, and the fluoroaluminate flux includes potassium fluoroaluminate.

[0016] In another aspect of this application, a brazing board is provided, comprising a core layer, a pre-embedded flux layer present on at least one side of the core layer, and a shell layer present on the side of the pre-embedded flux layer opposite to the core layer, wherein the pre-embedded flux layer comprises an aluminum alloy brazing material prepared according to the above-described method for preparing aluminum alloy brazing materials or the above-described alloy brazing material.

[0017] According to one embodiment of this application, the thickness of the pre-embedded flux layer accounts for 1% to 15% of the thickness of the brazing plate; and / or, the thickness of the brazing plate is 0.05 mm to 4 mm; and / or, the pre-embedded flux layer is present on both opposite sides of the core layer.

[0018] Another aspect of this application provides a heat sink including the aforementioned brazing plate.

[0019] This application provides aluminum alloy brazing materials and their preparation methods, brazing plates, and heat sinks. First, aluminum alloy powder and flux powder are mixed, and then the resulting mixture is ball-milled to embed the flux powder into the aluminum alloy powder, forming an aluminum alloy brazing material with an aluminum alloy matrix and flux embedded within it. By embedding the flux into the aluminum alloy matrix, an embedded morphology is formed between the two powders, which helps avoid problems such as flux powder agglomeration and uneven distribution of flux in the composite plate during the mixing process, thus preventing incomplete soldering and missed soldering. Simultaneously, the embedded morphology also improves the interfacial bonding between the flux powder and the aluminum alloy powder, reducing cracking during subsequent rolling, increasing the yield of the brazed plate, and lowering manufacturing costs. Attached Figure Description

[0020] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0021] Figure 1 This is a SEM image of the aluminum alloy brazing material prepared in Example 1 of this application;

[0022] Figure 2 SEM image of the aluminum alloy brazing material prepared in Comparative Example 1 of this application;

[0023] Figure 3 This is a metallographic image of the brazing plate prepared in Example 1 of this application.

[0024] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concepts of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0025] To enable those skilled in the art to better understand the solutions of this application, a further detailed description of this application is provided below. The specific embodiments listed below are merely descriptions of the principles and features of this application; the examples are only for explaining this application and are not intended to limit its scope. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application.

[0026] Currently, coating the surface of the brazing board with flux (such as Noclock flux) and using inert gas shielded brazing (CAB brazing) is the dominant technology in the passenger car and commercial vehicle radiator industry. This technology mainly works by melting the flux during the brazing heating process, breaking the oxide film on the surface, promoting the wetting and flow of the solder, and forming a good weld bead.

[0027] However, uneven flux application on the surface of brazing boards often results in poor soldering in areas with insufficient flux, while areas with excessive flux have residue. This not only wastes flux and increases costs, but the residual flux can also clog component channels. For example, due to the complex internal structure of heat sinks, especially in narrow areas that are difficult to clean, flux residue can easily clog channels, affecting the heat sink's heat dissipation efficiency and causing corrosion. Furthermore, products such as new energy vehicles have increasingly stringent requirements regarding potassium ion concentration due to factors such as Noclock flux residue. Typically, products require at least 2-3 days of multiple rinsing after brazing to meet OEM requirements; therefore, flux residue can also affect subsequent production processes.

[0028] To eliminate the influence of residual flux, it is also possible to avoid applying flux to the surface of the brazing board. Instead, the oxide film on the surface of the aluminum alloy can be broken by the elements such as Mg, Sr, and Li on the brazing board itself, thereby promoting the wetting and flow of the brazing filler metal. However, this method results in poor brazing performance and has limited application.

[0029] Aluminum alloy brazing plates typically consist of a core material and a shell layer covering the core material. Both the core material and the shell layer are made of aluminum alloy. By placing a composite plate (or pre-embedded flux layer) between the core material and the shell layer, the problems of uneven flux coating and flux residue can be overcome to some extent. This composite plate is usually formed by mixing a certain amount of flux powder and aluminum alloy powders such as aluminum silicon powder, and then forming it through hot isostatic pressing or other molding methods. This is equivalent to pre-embedding the flux inside the composite plate. During brazing, the composite plate melts and releases the flux, breaking the oxide film on the surface of the aluminum alloy.

[0030] However, flux powder tends to agglomerate when mixed with aluminum alloy powder, resulting in uneven distribution of flux powder in the composite plate. This can easily lead to problems such as incomplete soldering and missed soldering. At the same time, the flux powder particles and aluminum alloy material particles exist independently. After hot isostatic pressing and other forming processes, the interfacial bonding ability between the two in the composite plate is poor, affecting the stability and other properties of the resulting aluminum alloy brazing material. For example, it can easily cause cracking between the brazing plate, core material, and shell layer during the composite rolling process, thus affecting the welding effect.

[0031] Therefore, there is an urgent need to develop an aluminum alloy brazing material with strong interfacial bonding between flux powder and aluminum alloy powder, to improve the welding performance of aluminum alloy brazing materials and overcome the above-mentioned defects.

[0032] In view of this, the present application also provides a method for preparing aluminum alloy brazing material, comprising the following steps: mixing aluminum alloy powder and flux powder to obtain a mixture; ball milling the mixture to embed the flux powder into the aluminum alloy powder to obtain aluminum alloy brazing material.

[0033] According to the inventors' research, in the preparation process of the above-mentioned aluminum alloy brazing material, the aluminum alloy powder and the flux powder are first mixed (or premixed). This mixing process is carried out without grinding balls. That is, after mixing the aluminum alloy powder and the flux powder, a preliminary uniform mixing is performed without grinding balls. On the one hand, under the mild premixing conditions without grinding balls, the flux powder and the aluminum alloy powder can freely interpenetrate and mix with each other, avoiding problems such as powder agglomeration or uneven distribution caused by the violent collision of grinding balls during direct ball milling. At the same time, the mixing process before ball milling allows the powder to generate fresh surfaces due to friction and collision during the premixing process. These fresh surfaces have higher activity, which helps the flux powder to embed into the aluminum alloy powder during the subsequent ball milling process, forming an aluminum alloy brazing material with an aluminum alloy matrix and flux embedded in the aluminum alloy matrix.

[0034] In this process, aluminum alloy powder is used to form the aluminum alloy matrix, and flux powder is used to form the flux embedded in the aluminum alloy matrix. Through the above-mentioned mixing and ball milling processes, the flux powder is embedded in the aluminum alloy powder. The two powders form an embedded structure, which avoids problems such as flux powder agglomeration and uneven distribution in the subsequently formed pre-embedded flux layer during the mixing process. This avoids phenomena such as incomplete soldering and missed soldering. At the same time, the embedded structure between the two powders can also improve the interfacial bonding ability between the flux powder and the aluminum alloy powder. In the process of preparing brazed plates by rolling aluminum alloy brazing material with aluminum alloy core material and shell layer, film cracking can be reduced, the yield of brazed plates can be increased, and the manufacturing cost can be reduced.

[0035] Therefore, the method for preparing aluminum alloy brazing material provided in this application can improve the interfacial bonding ability between the flux in the aluminum alloy brazing material and the aluminum alloy matrix. This not only helps to improve the welding performance of the aluminum alloy brazing material, but also helps to improve the performance of the aluminum alloy brazing material. Specifically, in the process of preparing a brazing plate by rolling aluminum alloy brazing material with aluminum alloy core material and shell layer, film cracking can be reduced, the yield of brazing plate can be increased, and the preparation cost can be reduced.

[0036] Specifically, the aluminum alloy powder and the flux powder can be mixed and ball-milled sequentially in a liquid dispersion medium. That is, in the preparation process, the mixture also includes a liquid dispersion medium, which is used to disperse the flux powder and the aluminum alloy powder, so that the two are dispersed evenly. This helps to make the flux powder more evenly embedded in the aluminum alloy powder and improve the dispersion uniformity of the flux in the obtained aluminum alloy brazing material.

[0037] In some embodiments, the liquid dispersion medium includes acetone and / or ethanol. Acetone and / or ethanol mainly serve as grinding aids and dispersants, effectively reducing material viscosity and preventing powder agglomeration during grinding, thereby improving ball milling efficiency and ensuring that flux can be more uniformly embedded in the aluminum alloy matrix. In addition, the liquid dispersion medium can also help dissolve some surface impurities, further promoting the mixing and bonding of powders.

[0038] Specifically, the above-mentioned mixing process can be carried out under an inert atmosphere. In some embodiments, the above-mentioned mixing process includes: adding aluminum alloy powder, flux powder and liquid dispersion medium into a ball mill, and mixing them without the action of grinding beads to obtain a mixture.

[0039] During the above mixing process, the rotational speed of the ball mill can be 50 r / min to 200 r / min, for example, a range of 50 r / min, 100 r / min, 150 r / min, 200 r / min, or any combination thereof. The mixing time (i.e., the premixing time) can be 30 min to 60 min, for example, a range of 30 min, 40 min, 50 min, 60 min, or any combination thereof. Under the premixing conditions within the above range, the aluminum alloy powder and the flux powder can be mixed more uniformly, which helps to generate more fresh surfaces in the powder and facilitates the embedding of the flux into the aluminum alloy powder. This results in an embedded morphology between the two powders, further improving the interfacial bonding force between the flux and the aluminum alloy matrix in the resulting aluminum alloy brazing material.

[0040] Generally, aluminum alloy powder has better ductility than flux powder. Therefore, in the ball milling process, the highly ductile aluminum alloy powder can act as a ball milling aid to a certain extent. Thus, no additional grinding aids need to be added during the ball milling process.

[0041] In some embodiments, the ball milling process is performed under an inert atmosphere. Using an inert atmosphere during ball milling prevents oxidation or other unwanted chemical reactions of the flux and aluminum alloy substrate under severe impact.

[0042] Specifically, the ball milling process is carried out in the presence of grinding balls. That is, the ball milling process includes: milling the mixture under the action of grinding balls to embed the flux powder into the aluminum alloy powder, thereby obtaining an aluminum alloy brazing material.

[0043] The particle size of the grinding balls can be 5mm to 10mm, for example, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm or any combination thereof. Using grinding balls with a particle size of 5mm to 10mm for ball milling can better embed the flux into the aluminum alloy matrix, forming an embedded morphology between the two powders.

[0044] Furthermore, the mass ratio of the grinding balls to the aluminum alloy powder in the mixture to the total mass of the flux powder can be (8~10):1. For example, it can be a range of 8:1, 9:1, 10:1, or any combination thereof. When the mass ratio of the aluminum alloy powder to the total mass of the flux powder is (8~10):1, the flux can be better embedded in the aluminum alloy matrix, forming an intercalation pattern between the two powders.

[0045] In some embodiments, the ball milling process, performed by the action of the grinding balls, is carried out in a ball mill. During this process, the rotational speed of the ball mill is 50 r / min to 400 r / min, for example, a range consisting of 50 r / min, 100 r / min, 200 r / min, 300 r / min, 400 r / min, or any combination thereof. The ball milling time is 30 min to 300 min, for example, a range consisting of 30 min, 100 min, 150 min, 200 min, 250 min, 300 min, or any combination thereof.

[0046] During the ball milling process, the above mixture is ball milled under the action of the ball milling beads. When the ball milling parameters are within the above range, it is more conducive to the efficient embedding of the flux powder into the aluminum alloy powder, while avoiding problems such as particle breakage or uneven mixing, and further optimizing the performance of the obtained aluminum alloy brazing material.

[0047] In this embodiment, the aluminum alloy powder used can be spherical particles. After the above-mentioned mixing and ball milling treatment, it forms sheet-like particles, which form a sheet-like aluminum alloy matrix. At the same time, the flux is embedded in the sheet-like aluminum alloy matrix to obtain an aluminum alloy brazing material.

[0048] In some embodiments, during the ball milling process under the action of the grinding balls (i.e., during the ball milling process described above), the ball milling continues until the aluminum alloy powder in the mixture accounts for more than 90% of the total amount and forms a sheet-like aluminum alloy matrix. The ball milling is then terminated to obtain an aluminum alloy brazing material.

[0049] Specifically, the sheet-like aluminum alloy matrix can be observed using a scanning electron microscope (SEM), and the proportion of the formed sheet-like aluminum alloy matrix can be detected. More specifically, the mixture during the ball milling process can be monitored using an SEM at any area of ​​1000 µm. 2 In the field of view, aluminum alloy powder, accounting for over 90% of the total quantity, transforms from spherical particles into plate-like particles, thus obtaining the aluminum alloy brazing material. During ball milling, the impact and grinding force of the milling beads force the aluminum alloy powder to undergo plastic deformation, gradually extending from initial spherical particles into plate-like particles. This morphological change significantly increases the specific surface area of ​​the powder, providing favorable conditions for flux embedding into the aluminum alloy matrix. Scanning electron microscopy is the tool for observing this morphological change. It can clearly present the transformation process of aluminum alloy powder from spherical particles to plate-like particles, as well as the thickness of the plate-like particles. Through scanning electron microscopy analysis, the proportion of particles becoming plate-like can be quantitatively calculated.

[0050] Specifically, the aluminum alloy powder is spherical particles, which may include primary particles in the form of spherical particles. Due to its good ductility, during the ball milling process of mixing with flux, the spherical particles are easily squeezed into sheet-like particles, which can better embed the flux into them, thereby forming the aluminum alloy brazing material provided in the embodiments of this application.

[0051] In some embodiments, the particle size Dv50 of the aluminum alloy powder is 10μm to 300μm, for example, a range of 10μm, 20μm, 30μm, 40μm, 100μm, 200μm, 300μm or any combination thereof. By using aluminum alloy powder with this particle size range, it is more suitable for the above-mentioned mixing-ball milling process, so that the flux powder is embedded in the aluminum alloy powder. Specifically, the aluminum alloy powder generates more active surfaces during the mixing process, and is easier to stretch and plastically deform during the subsequent ball milling process. Based on the synergistic effect of these two processes, the flux powder is more easily embedded in the aluminum alloy powder.

[0052] In some embodiments, the Dv50 particle size of the flux powder is 20 μm to 80 μm, for example, a range of 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, or any combination thereof. When the particle sizes of the aluminum alloy powder and the flux powder are within the above range, the flux powder can be better embedded in the aluminum alloy powder, forming an intercalation morphology between the two powders.

[0053] In the embodiments of this application, the particle size Dv50 of the aluminum alloy powder and the flux powder can be controlled by conventional methods, and there are no special limitations on this.

[0054] Specifically, aluminum alloy powder and flux powder can each be independently produced as primary particles.

[0055] In some embodiments, the mass ratio of flux powder to the sum of the mass of flux powder and aluminum alloy powder is 1% to 20%, for example, a range of 1%, 2%, 3%, 5%, 10%, 15%, 20%, or any combination thereof. By controlling the ratio of flux powder to aluminum alloy powder within this range, it is more conducive to the flux being embedded in the aluminum alloy powder, while also improving the welding performance and structural stability of the resulting aluminum alloy brazed board.

[0056] In some embodiments, the aluminum alloy powder includes aluminum silicon powder, wherein the silicon content in the aluminum silicon powder is 7% to 13% by mass, for example, a range of 7%, 8%, 9%, 10%, 11%, 12%, 13%, or any combination thereof. Using aluminum silicon powder facilitates flux embedding within the aluminum silicon powder, improving the interfacial bonding between the two. It also helps the resulting aluminum alloy brazing material exhibit better melt flowability at brazing temperatures and aids in removing the oxide film from the aluminum alloy, thus improving the welding effect.

[0057] Furthermore, the oxygen content in aluminum-silicon powder can be less than or equal to 500 ppm by mass percentage, and further less than or equal to 200 ppm. Using aluminum-silicon powder with low oxygen content helps to improve the welding effect of the resulting aluminum alloy brazing material in subsequent applications.

[0058] In some specific embodiments, the silicon content in the aluminum silicon powder is 7% to 13% by mass, and the oxygen content is less than or equal to 500 ppm, which helps to further improve the welding performance of the obtained aluminum alloy brazing material.

[0059] It is important to note that, in addition to the elements mentioned above, the aluminum-silicon powder may also contain iron and one or more impurity elements. Impurity elements may include one or more of magnesium, chromium, and copper. By mass percentage, the iron content in the aluminum-silicon powder is less than or equal to 0.2%, the content of a single impurity element is less than or equal to 0.15%, and the total content of impurity elements is less than or equal to 0.15%.

[0060] In some embodiments, the flux powder includes fluoroaluminate flux, specifically potassium fluoroaluminate. Using this flux helps to embed it into the aluminum alloy powder through the above preparation process, improving the stability and welding performance of the resulting aluminum alloy brazing material. In particular, when potassium fluoroaluminate is used, its reaction activity time in the molten state is short, and it can quickly dry and fail, making it especially suitable for brazing aluminum alloys in a high-purity nitrogen-protected furnace. At the same time, the flux powder also helps to improve the wettability of the liquid flux to the aluminum alloy matrix, ensuring that it embeds into the aluminum alloy matrix and forms a strong interfacial bond.

[0061] In this application, the flux powder used can be a conventional flux, such as potassium fluoroaluminate flux, which can be commercially available Noclock flux powder.

[0062] Specifically, in the above preparation process, the mixing and ball milling processes can be carried out in the same ball mill. Specifically, aluminum alloy powder, flux powder, and liquid dispersion medium can be added to the ball mill and mixed without the action of grinding balls to obtain a mixture. Then, grinding balls are added to the ball mill for ball milling, so that the flux powder is embedded in the aluminum alloy powder, resulting in aluminum alloy brazing material. Using the same ball mill not only achieves flux embedding in the aluminum alloy powder but also facilitates operation.

[0063] This application also provides an aluminum alloy brazing material, including an aluminum alloy matrix and a flux embedded in the aluminum alloy matrix, wherein the aluminum alloy matrix includes a sheet-like aluminum alloy matrix.

[0064] In this embodiment, the flux is embedded in the aluminum alloy matrix, forming an embedded shape between the two powders, instead of the powder made by mixing the two powders in the prior art. This avoids problems such as flux powder agglomeration and uneven distribution in the composite plate during the mixing process, and avoids the phenomena of false soldering and missing soldering. At the same time, the embedded shape between the two powders can also improve the interfacial bonding ability between the flux powder and the aluminum alloy powder, so that cracking is reduced in the subsequent rolling process, the yield of brazed plates is increased, and the manufacturing cost is reduced.

[0065] Specifically, the aluminum alloy brazing material is granular, and its macroscopic state is powder. It can be understood that in the aluminum alloy brazing material, the flux is embedded in the aluminum alloy matrix, which is the dominant structure of the aluminum alloy brazing material particles. The shape of the aluminum alloy brazing material particles is basically the same as the shape of the aluminum alloy matrix that forms the particles. The aluminum alloy matrix includes sheet-like aluminum alloy matrix, that is, the aluminum alloy brazing material includes aluminum alloy brazing material particles with a sheet-like structure (i.e., sheet-like aluminum alloy brazing material particles).

[0066] Specifically, "sheet-like" refers to sheet-like particles with a certain thickness. The aluminum alloy matrix is ​​composed of sheet-like particles, which helps the flux to embed in the aluminum alloy matrix and improves the bonding strength between the two.

[0067] Specifically, the proportion of sheet-like aluminum alloy matrix in the aluminum alloy matrix is ​​greater than or equal to 90%, that is, in the aluminum alloy brazing material, the proportion of sheet-like aluminum alloy matrix particles to the total number of aluminum alloy matrix particles is greater than or equal to 90%. Correspondingly, in the aluminum alloy brazing material, the proportion of sheet-like aluminum alloy brazing material particles to the total number of aluminum alloy brazing material particles is greater than or equal to 90%.

[0068] Specifically, the average sheet diameter of the sheet-like aluminum alloy matrix is ​​20µm to 600µm, for example, within the range of 20µm, 80µm, 100µm, 200µm, 300µm, 400µm, 500µm, 600µm, or any combination thereof. When the aluminum alloy matrix is ​​in the form of sheet-like particles, and the average sheet diameter of the sheet-like particles is within the above range, it is more conducive to the embedding of flux, further improving the interfacial bonding strength between the aluminum alloy matrix and the flux, and reducing cracking during subsequent rolling processes.

[0069] It should be noted that the sheet diameter of the sheet aluminum alloy substrate refers to the length of the longest part of the sheet aluminum alloy substrate.

[0070] In some embodiments, the flux content in the aluminum alloy brazing material is 1% to 20% by mass. For example, it can be a range of 1%, 2%, 3%, 5%, 10%, 15%, 20%, or any combination thereof. The aluminum alloy brazing material provided in this application includes a flux and an aluminum alloy matrix. This aluminum alloy brazing material is used to form a pre-embedded flux layer between the core aluminum alloy and the shell aluminum alloy on the surface of the core material. During brazing, the pre-embedded flux layer melts, releasing the flux and breaking down the oxide film on the surfaces of the core and shell aluminum alloys. When the flux content in the aluminum alloy brazing material is 1% to 20% by mass, it can better break down the oxide film on the surface of the aluminum alloy while avoiding excessive flux residue after welding.

[0071] In some embodiments, the aluminum alloy matrix includes aluminum silicon powder. In the preparation process of embedding flux into the aluminum alloy matrix, aluminum silicon powder is the most effective choice as the aluminum alloy matrix. Silicon can significantly lower the melting point of the aluminum alloy matrix, making it easier to melt and flow at the brazing temperature to fill the joint gap. Simultaneously, the oxide film of the aluminum silicon powder is relatively easy to remove, which creates favorable conditions for the embedding of flux into the aluminum alloy matrix.

[0072] In some embodiments, the mass percentage of silicon in the aluminum-silicon powder is 7% to 13%. For example, it is a range of 7%, 8%, 9%, 10%, 11%, 12%, 13%, or any combination thereof. When the mass percentage of silicon in the aluminum-silicon powder is within the above range, the resulting embedded layer melts and flows better at the brazing temperature, and its oxide film is easier to remove, resulting in a full weld.

[0073] As mentioned above, by mass percentage, the silicon content in aluminum silicon powder is 7%~13%, the iron content is less than or equal to 0.2%, the oxygen content is less than or equal to 500ppm, the content of a single impurity element is less than or equal to 0.15%, and the total impurity element content is ≤0.15%.

[0074] In some embodiments, the flux includes fluoroaluminate fluxes, specifically potassium fluoroaluminate fluxes.

[0075] In practice, the potassium fluoroaluminate flux used can be commercially available Noclock flux powder, because Noclock flux powder has a melting point of about 565℃~572℃, which matches the brazing temperature well. It has a short reaction activity time in the molten state and can quickly dry and fail, making it particularly suitable for brazing aluminum alloys in a high-purity nitrogen-protected furnace. At the same time, during application, Noclock flux powder can significantly improve the wettability of liquid flux to the aluminum alloy matrix, ensuring that it is embedded in the aluminum alloy matrix and forms a strong interfacial bond.

[0076] This application also provides a brazing board, comprising a core layer, a pre-embedded flux layer present on at least one side of the core layer, and a shell layer present on the side of the pre-embedded flux layer opposite to the core layer. The pre-embedded flux layer comprises the aforementioned aluminum alloy brazing material or an aluminum alloy brazing material prepared according to the aforementioned method for preparing aluminum alloy brazing materials. This brazing board has advantages corresponding to the aforementioned aluminum alloy brazing materials, which will not be elaborated further.

[0077] Aluminum alloy brazing material forms a pre-embedded flux layer, which is placed between the core layer and the shell layer to form a brazing plate. During brazing, the pre-embedded flux layer melts and releases flux to break the oxide film of the core layer and the shell layer, thereby reducing the amount of flux used, avoiding flux residue clogging the pipes, ensuring the uniformity of flux release, and improving the brazing quality.

[0078] In some embodiments, the thickness of the pre-embedded flux layer accounts for 1% to 15% of the thickness of the brazing plate, for example, a range consisting of 1%, 3%, 5%, 7%, 9%, 11%, 13%, 15%, or any two of these.

[0079] In some embodiments, the thickness of the brazing plate is 0.05 mm to 4 mm, for example, a range of 0.05 mm, 0.1 mm, 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm or any two of these.

[0080] When the thickness of the brazing plate and the proportion of the thickness of the pre-embedded flux layer to the thickness of the brazing plate are within the above range, the overall performance of the brazing plate is better.

[0081] In some embodiments, pre-embedded flux layers are present on both opposite sides of the core layer. The brazing board has a sandwich structure, specifically, it can be a three-layer structure prepared from core material, pre-embedded flux blank, and shell material, or a five-layer structure prepared from shell material, pre-embedded flux layer, core material, pre-embedded flux blank, and shell material. When pre-embedded flux layers are present on both opposite sides of the core layer, it is a five-layer structure prepared from shell material, pre-embedded flux layer, core material, pre-embedded flux layer, and shell material.

[0082] In this embodiment of the application, the method for preparing a brazing board may include the following steps: pressing an aluminum alloy brazing material into a pre-embedded flux blank; wherein, the aluminum alloy brazing material includes the above-mentioned aluminum alloy brazing material or the aluminum alloy brazing material prepared according to the above-mentioned method for preparing aluminum alloy brazing material; and combining the pre-embedded flux blank with a core material for forming a core layer and a shell material for forming a shell layer to obtain a brazing board.

[0083] In this embodiment of the application, when pressing aluminum alloy brazing material into a pre-embedded flux blank, the specific pressing method is not limited. For example, the pressing method may include one or more of the following: hot isostatic pressing, vacuum isostatic pressing, cold isostatic pressing, spray forming, etc.

[0084] Pressing aluminum alloy brazing materials into pre-embedded flux blanks using hot isostatic pressing (HIP) or vacuum hot pressing significantly improves the interfacial bonding between the flux and the aluminum alloy matrix, thereby reducing cracking during subsequent rolling, increasing yield, and lowering costs. HIP uses isostatic pressure to ensure uniform stress on the material, making it particularly suitable for complex-shaped blanks. Vacuum hot pressing, performed in a vacuum environment, effectively prevents oxidation and further improves interfacial quality. Both processes achieve material densification under high temperature and pressure, ensuring uniform flux embedding into the aluminum alloy matrix and forming a tightly bonded pre-formed blank.

[0085] For example, the hot isostatic pressing temperature is 450℃~520℃, the holding time is 4h~6h, and the pressure is 20 MPa~250MPa.

[0086] For example, the vacuum degree of vacuum hot pressing is 0.001 Pa ~ 0.01 Pa, the temperature is 450℃ ~ 520℃, the holding time is 10 min ~ 60 min, and the pressure is 50 MPa ~ 200 MPa.

[0087] In some embodiments, the process of combining a pre-embedded flux blank with a core material for forming a core layer and a shell material for forming a shell layer includes: stacking the core material, the pre-embedded flux blank, and the shell material and then sequentially performing hot rolling, cold rolling, and annealing treatments.

[0088] After stacking the core material, pre-embedded flux blank, and shell material in either a three-layer structure (core material-pre-embedded flux blank-shell material) or a five-layer structure (shell material-pre-embedded flux layer-core material-pre-embedded flux blank-shell material), the material is first hot-rolled. During hot rolling, the flux melts at high temperatures and flows and wets the surfaces of the core material and shell material under rolling pressure, achieving diffusion bonding between atoms. Then, cold rolling is performed to further densify the material and improve the bonding strength. Finally, annealing is performed to eliminate processing stress and optimize the microstructure and properties.

[0089] For example, the hot rolling temperature is 480℃~510℃ and the time is 8h~12h.

[0090] For example, the cold rolling temperature is room temperature.

[0091] For example, the annealing temperature is 300℃~350℃ and the time is 8h~15h.

[0092] This application also provides a heat sink, including the brazing plate described above or a brazing plate prepared according to the brazing plate preparation method described above. This heat sink has advantages corresponding to the aforementioned aluminum alloy brazing materials, which will not be elaborated further.

[0093] In this embodiment of the application, the radiator can be a heat dissipation device such as an automotive radiator.

[0094] The present application will be further described below through specific embodiments.

[0095] Example 1

[0096] 1. Preparation of aluminum alloy brazing materials

[0097] An aluminum-silicon powder with a silicon content of 10%, an iron content of 0.17%, an impurity element content of 0.05%, an oxygen content of 200 ppm, and a particle size Dv50 of 50 µm was selected; a Noclock (potassium fluoroaluminate) flux powder with a particle size Dv50 of 20 µm was also selected. The Noclock flux powder used was Solvay's NOCOLOK® Sil Flux - Extra Fine Grade 2:1.

[0098] Weigh 1000g of Noclock flux powder and 9000g of aluminum-silicon powder, mix them, and add 20mL of acetone to obtain a mixture. Place the mixture in a ball mill (model XQM-2) and ball mill under a nitrogen atmosphere. Specifically, premix first without grinding beads at a speed of 100r / min for 45min; then ball mill with grinding beads of 8mm particle size at a mass ratio of 9:1 (total mass of aluminum alloy powder to flux powder in the mixture), at a speed of 200rpm / min for 150min. The resulting aluminum alloy brazing material contains 10% flux by mass.

[0099] Weigh 1 mg of aluminum alloy brazing material as a sample and observe it using a scanning electron microscope: After firmly adhering the sample to the sample stage with conductive adhesive, use a dropper to blow away any loose powder. Set the voltage to 15 kV and observe it at any 1000 µm. 2The field of view was photographed to obtain a SEM image; the SEM image was opened with ImageJ software and statistical analysis was performed. It was found that 90% of the aluminum silicon powder changed from spherical particles to flake particles; at the same time, the average flake diameter of the flake aluminum silicon powder (i.e. aluminum alloy matrix) in the aluminum alloy brazing material was measured to be 30µm.

[0100] 2. Preparation of brazing plates

[0101] The obtained aluminum alloy brazing material was pressed into a pre-embedded flux blank using hot isostatic pressing (HIP). Specifically, a hollow sheath with a gas tube was made of pure aluminum, with external dimensions of 206×326×646mm and a pure aluminum thickness of 3mm. The prepared aluminum alloy brazing material was placed into the sheath, and a vacuum of 1Pa was applied. The HIP temperature was 500℃, the pressure was 100MPa, and the holding time was 6h. After milling off the surface sheath material, the material was hot-rolled to a 10mm sheet to obtain a 10mm pre-embedded flux blank.

[0102] The obtained pre-embedded flux blank, a 450mm thick 3003 aluminum alloy core with a milled surface, and a 40mm thick 4343 aluminum alloy shell with a milled surface are stacked in a three-layer structure of core material-pre-embedded flux blank-shell material. The core is heated to 490℃ and held for 10 hours to obtain a hot-rolled plate. Then it is cooled to room temperature to obtain a cold-rolled plate with a thickness of 1mm. Finally, the cold-rolled plate is held at 320℃ for 10 hours to obtain a 1mm thick brazing plate.

[0103] In this brazing board, the thickness of the pre-embedded flux layer accounts for 2% of the total thickness of the brazing board.

[0104] Referring to Example 1, aluminum alloy brazing materials and brazing plates of Examples 2-9 and Comparative Example 3 were prepared. The differences are shown in Tables 2 and 3, and the other conditions are the same as in Example 1. Among them, Comparative Example 3 did not perform a premixing (i.e., mixing treatment) process before ball milling, but directly performed the ball milling step.

[0105] Example 10

[0106] The difference from Example 1 is that, in the preparation process of the brazing board, a five-layer structure of shell material-embedded flux blank-core material-embedded flux blank-shell material is stacked, while the other conditions are the same as in Example 1.

[0107] Comparative Example 1

[0108] The difference from Example 1 is that after weighing the Noclock flux powder and aluminum-silicon powder, the ball milling step is not performed. Instead, the Noclock flux powder and aluminum-silicon powder are mixed at a low speed of 6 r / min on a powder mixer (model SYH) for 4 hours. The resulting mixed powder is the aluminum alloy brazing material. The other conditions are the same as in Example 1.

[0109] Comparative Example 2

[0110] The difference from Example 10 is that after weighing the Noclock flux powder and aluminum-silicon powder, the ball milling step is not performed. Instead, the Noclock flux powder and aluminum-silicon powder are mixed at a low speed of 6 r / min on a powder mixer (model SYH) for 4 hours. The resulting mixed powder is the aluminum alloy brazing material. The other conditions are the same as in Example 10.

[0111] In each embodiment and comparative example, the particle size Dv50 of aluminum alloy powder (aluminum silicon powder), the particle size Dv50 of flux powder, the rotation speed of the ball mill during premixing (premixing speed), the premixing time (premixing time), the rotation speed of the ball mill during ball milling (ball milling speed), the ball milling time, the particle size of the ball milling beads, and the total mass ratio of the ball milling beads to the aluminum alloy powder and flux powder in the mixture are shown in Table 2.

[0112] In each embodiment and comparative example, the average sheet diameter of the sheet aluminum alloy substrate, the mass percentage of flux in the aluminum alloy brazing material, the mass percentage of silicon in the aluminum silicon powder, the percentage of the thickness of the pre-embedded flux layer to the thickness of the brazing plate, and the thickness of the brazing plate are shown in Table 3.

[0113] The performance of the aluminum alloy brazing materials and brazing plates in each embodiment and comparative example was tested according to the following procedure.

[0114] 1. Morphological characterization test of aluminum alloy brazing materials

[0115] 1 mg of the aluminum alloy brazing material prepared in the examples and comparative examples was weighed as a sample and observed by scanning electron microscopy: the sample was firmly adhered to the sample stage with conductive adhesive and the powder that was not firmly adhered was blown away with a dropper. The voltage was set to 15 kV and the image was taken to obtain the SEM image. The average diameter of the sheet aluminum alloy matrix can be calculated by the number of sheet aluminum alloy substrates observed in the field of view of the scanning electron microscope and the diameter of each sheet aluminum alloy substrate obtained by combining the scale bar.

[0116] Figure 1 This is a SEM image of the aluminum alloy brazing material prepared in Example 1. Figure 2 SEM image of the aluminum alloy brazing material prepared in Comparative Example 1. Figure 2 As can be seen, in the aluminum alloy brazing material prepared in Comparative Example 1, the flux (potassium fluoroaluminate) and the aluminum alloy matrix (aluminum silicon powder) are directly mixed and then dispersed. Specifically, the flux (potassium fluoroaluminate) powder is dispersed on the surface of the aluminum alloy matrix (aluminum silicon powder), appearing as a coating of the flux (potassium fluoroaluminate) onto the aluminum alloy matrix (aluminum silicon powder), without any intercalation between them. Figure 1 It can be seen that in the aluminum alloy brazing material of Example 1, the aluminum alloy brazing material is mainly composed of sheet-like particles.

[0117] X-ray energy dispersive spectroscopy (EDS) was performed on the aluminum alloy brazing materials prepared in Examples 1 to 10. Specifically, the particles of the aluminum alloy brazing materials were tested by EDS. The results showed that the aluminum alloy brazing material particles not only contained elements such as aluminum (Al) and silicon (Si) from the aluminum alloy matrix, but also elements such as fluorine and potassium from the flux (potassium fluoroaluminate), proving that the flux was embedded in the aluminum alloy matrix.

[0118] The test results of Example 1 will be used as an example for a more detailed explanation. EDS is a qualitative method for identifying the types of elements in a material, but it cannot quantify the elemental composition of the material. The content of each element given below is only provided semi-quantitatively through EDS. Table 1 is a table of elemental distribution obtained by EDS testing of the aluminum alloy brazing material prepared in Example 1. As can be seen from Table 1, the elemental composition analysis of the test points on the aluminum alloy brazing material particles revealed that the composition of the test points was: 84.0% Al by mass, 1.0% Si by mass, 7.2% F by mass, and 7.8% K by mass. Among them, Al and Si elements come from the aluminum alloy matrix (aluminum silicon powder), and F and K elements come from the flux (potassium fluoroaluminate) embedded in the aluminum alloy matrix (aluminum silicon powder). This proves that the flux is embedded in the aluminum alloy matrix.

[0119] Table 1. Elemental distribution of aluminum alloy brazing materials in EDS semi-quantitative analysis.

[0120]

[0121] 2. Characterization Tests for Brazing Quality of Brazed Plates

[0122] The brazing plates prepared in the examples and comparative examples were overlapped with optical fins without pre-embedded flux layers and placed in a brazing furnace. The parameters were set as follows: oxygen content less than or equal to 50 ppm, brazing temperature of 610℃, and holding time of 10 min for brazing testing. After the brazing test, the samples were taken, polished, and observed under a microscope for metallographic images. The weld width was measured based on the metallographic images. The test results are shown in Table 4.

[0123] Taking Example 1 as an example, Figure 3 The image shows the metallographic structure of the brazed plate prepared in Example 1. Figure 3 The line segment 'w' of the double-headed arrow represents the weld width. Figure 3 As can be seen from the table, the brazed plate made from the aluminum alloy brazing material prepared in Example 1 has a large welding width, as recorded in Table 4, with a welding width of 1800 μm and excellent welding performance.

[0124] Table 2 Preparation conditions of aluminum alloy brazing materials

[0125]

[0126] Table 3 Relevant parameters of aluminum alloy brazing materials and brazing plates

[0127]

[0128] Table 4 Weld width test results

[0129]

[0130] As can be seen from Table 4, when the aluminum alloy brazing materials prepared in Comparative Examples 1 and 2 were used to prepare brazing plates, the composite structure formed by the core material, the pre-embedded flux blank, and the shell material cracked during the hot rolling process. Although the aluminum alloy brazing material prepared in Comparative Example 3 did not crack during the preparation of brazing plates, its welding performance was poor. As shown in Table 4, the welding width of the brazing plate was only 680 μm, which was much lower than that of Examples 1 to 10.

[0131] In contrast to Comparative Examples 1-3, Examples 1-10 involved mixing aluminum silicon powder and flux powder, pre-mixing them, and then ball milling them to embed the flux into the aluminum alloy matrix. This resulted in an embedded structure between the two powders, avoiding problems such as flux powder agglomeration and uneven distribution in the composite plate during the mixing process. This prevented incomplete soldering and missed soldering. Furthermore, the embedded structure also improved the interfacial bonding between the flux powder and the aluminum alloy powder, reducing cracking during subsequent rolling, increasing the yield of brazed plates, and lowering manufacturing costs.

[0132] In contrast to Comparative Example 3, Examples 1 to 10 premixed the flux powder and aluminum alloy powder in a ball-free state before ball milling. On the one hand, in the gentle environment without grinding balls, the flux powder and aluminum alloy powder can freely interweave and mix with each other, avoiding powder agglomeration or uneven distribution caused by the violent collision of grinding balls at the beginning. On the other hand, the powder will generate fresh surfaces due to friction and collision during the premixing process. These fresh surfaces have high activity, which helps to embed the flux into the aluminum alloy matrix during the subsequent ball milling process.

[0133] Furthermore, compared to Examples 4 and 5, Examples 1 and 3, by further controlling the ball mill speed within the range of 50 r / min to 200 r / min and the premixing time within the range of 30 min to 60 min during the premixing process without grinding balls, are more conducive to the more uniform mixing of flux powder and aluminum alloy powder during the premixing process, and the generation of more active surfaces. This further enhances the interfacial bonding ability between the flux and the aluminum alloy matrix during subsequent ball milling, resulting in tighter embedding and thus further improving the welding performance of the brazed plate.

[0134] Furthermore, compared to Examples 6 to 9, Examples 1 to 3 further control the rotation speed of the ball mill within the range of 50 r / min to 400 r / min and the ball milling time within the range of 30 min to 300 min during the ball milling process under the action of the ball milling beads. This helps the flux to be embedded more efficiently into the aluminum alloy matrix, while avoiding excessive crushing or uneven mixing, thereby further improving the welding performance of the brazing board.

[0135] Furthermore, it can be seen that the aluminum alloy brazing materials prepared in Example 1 and Example 10 are the same, but the specific layered structures of the brazed plates prepared from the aluminum alloy brazing materials are different. Specifically, Example 1 has a three-layer structure of core layer-pre-embedded flux layer-shell layer, while Example 10 has a five-layer structure of shell layer-pre-embedded flux layer-core layer-pre-embedded flux layer-shell layer. Both have excellent welding performance, proving that the aluminum alloy brazing material provided in this application is suitable for various brazed plate structures.

[0136] Finally, it should be noted that other embodiments of this application will readily conceive of by those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and alterations may be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A method for preparing an aluminum alloy brazing material, characterized in that, Includes the following steps: Aluminum alloy powder and flux powder are mixed in a ball mill without grinding beads to obtain a mixture; The mixture is ball-milled in a ball mill with grinding beads to embed the flux powder into the aluminum alloy powder, thereby obtaining the aluminum alloy brazing material, which includes sheet-like aluminum alloy brazing material particles.

2. The method for preparing aluminum alloy brazing material according to claim 1, characterized in that, The mixing process includes: adding the aluminum alloy powder, the flux powder, and the liquid dispersion medium into a ball mill, and carrying out the mixing process without the action of grinding beads to obtain the mixture; wherein, during the mixing process, the rotation speed of the ball mill is 50 r / min to 200 r / min, the mixing time is 30 min to 60 min, and the liquid dispersion medium includes acetone and / or ethanol.

3. The method for preparing aluminum alloy brazing material according to claim 1, characterized in that, During the ball milling process, the particle size of the milling beads is 5mm~10mm; The ratio of the mass of the grinding ball to the total mass of the aluminum alloy powder and the flux powder in the mixture is (8~10):

1.

4. The method for preparing aluminum alloy brazing material according to claim 3, characterized in that, During the ball milling process, the ball milling continues until the aluminum alloy powder in the mixture accounts for more than 90% of the total amount, forming a sheet-like aluminum alloy matrix. The ball milling is then terminated to obtain the aluminum alloy brazing material. The average sheet diameter of the sheet-like aluminum alloy matrix is ​​20µm to 600µm.

5. The method for preparing aluminum alloy brazing material according to claim 3 or 4, characterized in that, During the ball milling process, the rotation speed of the ball mill is 50 r / min to 400 r / min, and the ball milling time is 30 min to 300 min.

6. The method for preparing aluminum alloy brazing material according to any one of claims 1-4, characterized in that, The particle size Dv50 of the aluminum alloy powder is 10μm~300μm; And / or, the particle size Dv50 of the flux powder is 20μm~80μm.

7. The method for preparing aluminum alloy brazing material according to any one of claims 1-4, characterized in that, The mass ratio of the flux powder to the sum of the masses of the flux powder and the aluminum alloy powder is 1% to 20%. And / or, the aluminum alloy powder includes aluminum silicon powder, and the silicon content in the aluminum silicon powder is 7% to 13% by mass, and the oxygen content is less than or equal to 500 ppm; And / or, the flux powder includes fluoroaluminate fluxes, and the fluoroaluminate fluxes include potassium fluoroaluminate.

8. An aluminum alloy brazing material, the aluminum alloy brazing material prepared according to the preparation method of the aluminum alloy brazing material according to any one of claims 1-7; the aluminum alloy brazing material includes an aluminum alloy matrix and a flux embedded in the aluminum alloy matrix, the aluminum alloy matrix including a sheet-like aluminum alloy matrix, the average sheet diameter of the sheet-like aluminum alloy matrix being 20μm~600μm.

9. The aluminum alloy brazing material according to claim 8, characterized in that, In the aluminum alloy matrix, the proportion of the sheet-like aluminum alloy matrix is ​​greater than or equal to 90%; And / or, in the aluminum alloy brazing material, the flux content is 1%~20% by mass; And / or, the aluminum alloy matrix includes aluminum silicon powder, and the silicon content in the aluminum silicon powder is 7% to 13% by mass, and the oxygen content is less than or equal to 500 ppm; And / or, the flux includes fluoroaluminate fluxes, and the fluoroaluminate fluxes include potassium fluoroaluminate.

10. A brazing plate, characterized in that, It includes a core layer, a pre-embedded flux layer present on at least one side of the core layer, and a shell layer present on the side of the pre-embedded flux layer opposite to the core layer, wherein the pre-embedded flux layer includes an aluminum alloy brazing material prepared according to the preparation method of aluminum alloy brazing material according to any one of claims 1-7 or the aluminum alloy brazing material according to claim 8 or 9.

11. The brazing plate according to claim 10, characterized in that, The thickness of the pre-embedded flux layer accounts for 1% to 15% of the thickness of the brazing plate. And / or, the thickness of the brazing plate is 0.05mm to 4mm; And / or, the pre-embedded flux layer is present on both opposite sides of the core layer.

12. A radiator, characterized in that, Includes the brazing plate as described in claim 10 or 11.

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