Aluminum foil material for heat exchanger and preparation method thereof

Abstract

The invention relates to the technical field of aluminum alloy processing, in particular to an aluminum foil material for a heat exchanger and a preparation method thereof.The aluminum foil material comprises, by mass percent, 0.25%-0.50% of iron, 0.10%-0.20% of silicon, 0.8%-1.3% of manganese, 0.8%-1.1% of zinc, 0.03%-0.05% of titanium, 0.08%-0.12% of zirconium, 0.2%-0.25% of rare earth elements, smaller than or equal to 0.03% of copper, smaller than or equal to 0.005% of magnesium and the balance aluminum and inevitable impurities. The total content of the non-removable impurities is not greater than 0.3%. The prepared aluminum foil material has high strength stability and corrosion resistance.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy processing technology, specifically to an aluminum foil material for heat exchangers and its preparation method. Background Technology

[0002] Heat exchangers, as core components for energy transfer, are widely used in critical fields such as air conditioning, refrigeration, automobiles, and power electronics. Among them, aluminum alloy heat sinks have long been considered the ideal material for manufacturing heat exchanger fins due to their excellent thermal conductivity, lightweight nature, ease of processing and forming, and relatively economical cost. In the structure of a heat exchanger, aluminum foil is mainly used to increase the heat exchange area by forming fins, promoting efficient heat transfer between hot and cold fluids. Its performance directly determines the heat exchange efficiency, service life, and operational reliability of the heat exchanger.

[0003] With the advancement of global energy conservation and emission reduction policies and the continuous improvement of energy efficiency standards, heat exchangers are developing towards thinner and denser designs to achieve maximum heat exchange efficiency within a limited space. This trend places more stringent demands on the performance of the basic materials of aluminum alloy heat sinks, especially their reliability during long-term service. The thickness of aluminum foil has gradually decreased from 0.15mm in the early days to 0.09mm or even thinner today, and the fin spacing has also shrunk from 2.5mm to less than 1.4mm. While this structural change improves heat exchange efficiency, it also makes the heat sinks more sensitive to corrosive environments; even minor corrosion damage can lead to a sharp decline in overall system performance.

[0004] Currently, aluminum foil materials used in heat exchangers mainly employ 3003 aluminum alloy and its improved versions as the base material system. These are typically 3xxx and 4xxx series aluminum alloy composite brazing plates, usually with AA3003 as the core material and AA4343 as the brazing alloy. However, facing increasingly complex and harsh operating environments, even the relatively high-performance 3003 aluminum alloy has revealed a series of problems. In practical applications, the high Cu content in the 3003 aluminum alloy, while extending the material's service life, leads to Cu diffusion during brazing, causing the precipitation of second phases such as CuAl2 and MnAl6 at grain boundaries. This results in Cu-depleted regions around the grain boundaries, increasing the aluminum alloy's susceptibility to intergranular corrosion and making it prone to intergranular corrosion. Invention patent CN112605147B discloses a high corrosion-resistant, low-potential heat exchanger finned aluminum foil and its manufacturing method. The aluminum foil is composed of the following components by mass percentage: Fe 0.40~0.50%, Si 0.12~0.20%, Cu≤0.03%, Mn≤0.01%, Mg≤0.005%, Zn 0.8~1.1%, Ti 0.025~0.05%, Zr≤0.03%, with the remainder being aluminum. This invention provides a continuous casting-rolling + cold rolling process for producing high-Zn heat exchanger finned aluminum foil, extending the service life of drawn aluminum tubes in air conditioning heat exchangers. However, its corrosion resistance is limited, and there is still room for improvement in its strength stability and application reliability under high-temperature environments.

[0005] Therefore, developing aluminum foil materials that combine high strength, stability, and corrosion resistance has become a key direction for overcoming traditional technological bottlenecks and meeting the needs of modern industrial applications. Summary of the Invention

[0006] To address the problems existing in the prior art, the present invention aims to provide an aluminum foil material for heat exchangers and a method for preparing the same. The aluminum foil material prepared by the present invention has high strength stability and corrosion resistance.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first aspect of the present invention provides an aluminum foil material for heat exchangers, the aluminum foil comprising the following components in 100% by mass: 0.25-0.50% iron, 0.10-0.20% silicon, 0.8-1.3% manganese, 0.8-1.1% zinc, 0.03-0.05% titanium, 0.08-0.12% zirconium, 0.2-0.25% rare earth elements, ≤0.03% copper, ≤0.005% magnesium, with the remainder being aluminum and unavoidable impurities.

[0008] In some embodiments of the present invention, the aluminum foil comprises the following components in 100% by weight: 0.30% iron, 0.12% silicon, 1.15% manganese, 0.95% zinc, 0.035% titanium, 0.11% zirconium, 0.23% rare earth elements, 0.03% copper, 0.005% magnesium, with the remainder being aluminum and unavoidable impurities.

[0009] A second aspect of the present invention provides a method for preparing aluminum foil material for heat exchangers, comprising the following steps: S1: Ingredients: Prepare ingredients according to the above components and mass percentages; S2: Smelting and refining: Smelt the ingredients from step S1 to obtain aluminum alloy melt. When the melt temperature reaches 730-750℃, add functional refining agent for refining treatment. After standing for 10-15 minutes, remove the slag from the surface of the aluminum alloy melt and cast it into an ingot. S3: Hot rolling: The ingot from step S2 is cut and milled, then homogenized and annealed at 600-620℃ for 15-24 hours and cooled, and then hot rolled to obtain a hot-rolled plate with a total hot rolling deformation of ≥85%; S4: Cold rolling: The hot-rolled plate from step S3 is cold-rolled with a total cold rolling reduction of 70-75%, and then annealed at 400-420℃ for 3-5 hours to obtain the finished alloy. S5: Anneal the finished alloy from S4 again at 300-340℃ for 1-3 hours, and then slit it using a slitting machine to obtain the aluminum foil material for the heat exchanger. In some embodiments of the present invention, the rare earth element is one or more of cerium, samarium, and yttrium.

[0010] In some embodiments of the present invention, the rare earth element is a mixture of cerium, samarium and yttrium in a mass ratio of 5:(1-2):(1-3).

[0011] This invention constructs a high-temperature stable framework through the synergistic construction of manganese-zirconium and rare earth elements. Zirconium may form a highly thermally stable Al3Zr nanophase, while yttrium may further dissolve in Al3Zr to form an Al3(Zr,Y) phase, further enhancing stability. These nanophases precipitate during homogenization annealing and subsequent heat treatment, hindering grain boundary movement and dislocation motion, forming a composite strengthening phase network with higher thermal stability than traditional Al-Mn alloys. Furthermore, compared to existing technologies that sacrifice zinc for corrosion resistance, the preferred rare earth elements cerium, samarium, and yttrium in this invention achieve deep melt purification, fundamentally eliminating pitting corrosion initiation sites and improving bulk corrosion resistance. On the other hand, they promote the formation of a denser, more adhesive rare earth oxide film on the aluminum surface. Yttrium further refines the grains, increases grain boundary area, effectively suppresses severe pitting corrosion, and improves corrosion uniformity, collectively enhancing corrosion resistance.

[0012] In some embodiments of the present invention, the functional refining agent comprises material A and material B. Material A comprises the following raw materials in parts by weight: 40-55 parts Na3AlF6, 10-15 parts magnesium carbonate, 8-12 parts potassium fluorozirconate, 25-30 parts aluminum fluoride, 10-12 parts potassium fluoroaluminate, 5-10 parts graphite powder, and 10-20 parts titanium diboride. Material B is composed of hexafluoroethane, titanium dioxide, yttrium fluoride, and cerium fluoride in a weight ratio of 5:1.5-2:0.3-0.5:0.5-1.

[0013] In some embodiments of the present invention, the mass ratio of material A to material B is (2.5-3):1.

[0014] In some embodiments of the present invention, the amount of the functional refining agent added is 0.1-0.5% of the mass of the aluminum alloy melt.

[0015] In some embodiments of the present invention, the preparation steps of the functional refining agent are as follows: (1) Take part of Na3AlF6 from material A and yttrium fluoride and cerium fluoride from material B, dry them at 200-250℃ for 2-4 hours, then heat them to 700-750℃ and treat them with stirring for 0.5-1 hours. Quickly transfer them to a preheated metal mold, cool them, crush them and sieve them to obtain the pre-melted material. (2) After crushing and sieving the remaining raw materials, mix them thoroughly, add the pre-melted material from step (1) and mix for 20-40 minutes, then treat at 90-100℃ for 1-3 hours, sieve and cool to obtain the functional refining agent.

[0016] In some embodiments of the present invention, in step (1), the amount of Na3AlF6 added is 2-4 times the total mass of yttrium fluoride and cerium fluoride.

[0017] Furthermore, this invention incorporates a preferred refining agent during the preparation of aluminum foil materials, which helps improve the high-temperature stability, corrosion resistance, and uniform mechanical properties of the aluminum foil materials. The applicant speculates that the addition of the functional refining agent allows the aluminum alloy melt to be purified while simultaneously pre-constructing precursors of the strengthening phase and seeds of the refining phase within its interior. In particular, this invention, through partial pretreatment with Na3AlF6 and yttrium fluoride and cerium fluoride, not only improves its wettability with aluminum but also promotes a more stable, uniform, and highly active "release" of these substances within the aluminum melt. This synergistic effect is further enhanced, enabling subsequent homogenization, hot rolling, annealing, and other processes to more fully and efficiently achieve a comprehensive improvement in the performance of the aluminum foil materials.

[0018] Compared with the prior art, the present invention has the following beneficial effects: (1) The aluminum foil material prepared by the present invention has high strength stability and corrosion resistance.

[0019] (2) Based on the synergistic optimization of the element ratio and preparation process of aluminum foil material, the present invention adds functional refining agent to improve the metallographic structure of the alloy and the morphology and distribution homogeneity of the precipitated strengthening phase. At the same time, it constructs a high-temperature stable skeleton and effectively purifies harmful impurities, making it have better strength stability and corrosion resistance, which significantly improves the applicability of aluminum foil material in the field of heat exchangers. Detailed Implementation

[0020] The present invention will be described below with reference to specific embodiments. It should be noted that the following embodiments are examples of the present invention and are used only to illustrate the invention, not to limit it. Other combinations and various modifications within the scope of the present invention can be made without departing from its spirit or scope.

[0021] The compounds and related reagents used in the following examples and comparative examples are all commercially available.

[0022] Unless otherwise specified, the post-processing steps such as "crushing" and "sieving" used below are routine operations for those skilled in the art, and can be selected according to actual operation.

[0023] Preparation Example 1 The functional refining agent consists of component A and component B. Component A contains the following raw materials in parts by weight: 650 parts Na3AlF, 12 parts magnesium carbonate, 10 parts potassium fluorozirconate, 28 parts aluminum fluoride, 11 parts potassium fluoroaluminate, 8 parts graphite powder, and 15 parts titanium diboride. Component B is composed of hexafluoroethane, titanium dioxide, yttrium fluoride, and cerium fluoride in a weight ratio of 5:1.7:0.4:0.8.

[0024] The mass ratio of material A to material B is 2.8:1.

[0025] The preparation steps of the functional refining agent in this preparation example are as follows: (1) Take part of Na3AlF6 from material A and yttrium fluoride and cerium fluoride from material B, dry them at 230°C for 3 hours, then heat them to 730°C and treat them with stirring for 0.8 hours. Quickly transfer them to a preheated metal mold, cool them, crush them and pass them through an 80-mesh sieve to obtain the pre-melted material. The amount of Na3AlF6 added is 3 times the total mass of yttrium fluoride and cerium fluoride. (2) Crush the remaining raw materials, pass them through a 100-mesh sieve and mix them thoroughly. Add the pre-melted material from step (1) and mix for 30 minutes. Then treat at 95°C for 2 hours, pass through a 60-mesh sieve and cool to obtain the functional refining agent.

[0026] Preparation Example 2 The specific preparation steps of the functional refining agent are the same as those in Preparation Example 1, except that the amount of Na3AlF6 added in step (1) is 33 parts by weight.

[0027] Preparation Example 3 The functional refining agent consists of component A and component B. Component A contains the following raw materials in parts by weight: 650 parts Na3AlF, 12 parts magnesium carbonate, 10 parts potassium fluorozirconate, 28 parts aluminum fluoride, 11 parts potassium fluoroaluminate, 8 parts graphite powder, and 15 parts titanium diboride. Component B is composed of hexafluoroethane, titanium dioxide, yttrium fluoride, and cerium fluoride in a weight ratio of 5:1.7:0.4:0.8.

[0028] The mass ratio of material A to material B is 2.8:1.

[0029] The preparation steps of the functional refining agent in this preparation example are as follows: Take the raw materials of material A and material B, crush them, pass them through a 100-mesh sieve, mix them thoroughly for 30 minutes, then treat them at 95℃ for 2 hours, pass them through a 60-mesh sieve, and cool them to obtain the functional refining agent.

[0030] Preparation Example 4 The specific preparation steps for the functional refining agent are the same as in Preparation Example 1, except that potassium fluorozirconate is not added in this preparation example.

[0031] Example 1 An aluminum foil material for heat exchangers comprises the following components in 100% by mass: 0.30% iron, 0.12% silicon, 1.15% manganese, 0.95% zinc, 0.035% titanium, 0.11% zirconium, 0.23% rare earth elements, 0.03% copper, 0.005% magnesium, with the remainder being aluminum and unavoidable impurities, the total content of which is not greater than 0.3%.

[0032] The method for preparing aluminum foil material for heat exchangers in this embodiment includes the following steps: S1: Ingredients: Ingredients are prepared according to the above composition and mass percentage, wherein the rare earth elements are a mixture of cerium, samarium and yttrium, and the mass ratio of the three is 5:1.5:2.

[0033] S2: Smelting and refining: The ingredients in step S1 are smelted to obtain aluminum alloy melt. When the melt temperature reaches 740℃, 0.3% of the mass of the aluminum alloy melt is added for refining. After standing for 12 minutes, the slag on the surface of the aluminum alloy melt is removed and cast into ingots. S3: Hot rolling: The ingot from step S2 is cut and milled, then homogenized and annealed at 610℃ for 20 hours, then water-cooled, and then hot-rolled to obtain a hot-rolled plate with a total hot-rolling deformation ≥85%; S4: Cold rolling: The hot-rolled plate from step S3 is cold-rolled with a total cold rolling reduction of 72%, and then annealed at 410°C for 4 hours to obtain the finished alloy. S5: Anneal the finished alloy from S4 again at 320℃ for 2 hours, and then slit it using a slitting machine to obtain aluminum foil material for heat exchangers.

[0034] The functional refining agent was obtained from Preparation Example 1.

[0035] Example 2 An aluminum foil material for heat exchangers comprises the following components in 100% by mass: 0.25% iron, 0.10% silicon, 0.8% manganese, 0.8% zinc, 0.03% titanium, 0.08% zirconium, 0.2% rare earth elements, 0.03% copper, 0.005% magnesium, with the remainder being aluminum and unavoidable impurities, the total content of which is not greater than 0.3%.

[0036] The method for preparing aluminum foil material for heat exchangers in this embodiment includes the following steps: S1: Ingredients: Ingredients are prepared according to the above composition and mass percentage, wherein the rare earth elements are a mixture of cerium, samarium and yttrium, and the mass ratio of the three is 5:1.5:2.

[0037] S2: Smelting and refining: The ingredients in step S1 are smelted to obtain aluminum alloy melt. When the melt temperature reaches 730℃, 0.3% of the mass of the aluminum alloy melt is added for refining treatment. After standing for 15 minutes, the slag on the surface of the aluminum alloy melt is removed and cast into ingots. S3: Hot rolling: The ingot from step S2 is cut and milled, then homogenized and annealed at 600℃ for 24 hours, then water-cooled, and then hot-rolled to obtain a hot-rolled plate with a total hot-rolling deformation ≥85%; S4: Cold rolling: The hot-rolled plate from step S3 is cold-rolled with a total cold rolling reduction of 72%, and then annealed at 400°C for 5 hours to obtain the finished alloy. S5: Anneal the finished alloy from S4 again at 300℃ for 3 hours, and then slit it using a slitting machine to obtain aluminum foil material for heat exchangers.

[0038] The functional refining agent was obtained from Preparation Example 1.

[0039] Example 3 An aluminum foil material for heat exchangers comprises the following components in 100% by mass: 0.50% iron, 0.20% silicon, 1.3% manganese, 1.1% zinc, 0.05% titanium, 0.12% zirconium, 0.25% rare earth elements, 0.03% copper, 0.005% magnesium, with the remainder being aluminum and unavoidable impurities, the total content of which is not greater than 0.3%.

[0040] The method for preparing aluminum foil material for heat exchangers in this embodiment includes the following steps: S1: Ingredients: Ingredients are prepared according to the above composition and mass percentage, wherein the rare earth elements are a mixture of cerium, samarium and yttrium, and the mass ratio of the three is 5:1.5:2;

[0041] S2: Smelting and refining: The ingredients in step S1 are smelted to obtain aluminum alloy melt. When the melt temperature reaches 750℃, 0.3% of the mass of the aluminum alloy melt is added for refining treatment. After standing for 10 minutes, the slag on the surface of the aluminum alloy melt is removed and cast into ingots. S3: Hot rolling: The ingot from step S2 is cut and milled, then homogenized and annealed at 620℃ for 15 hours, then water-cooled, and then hot-rolled to obtain a hot-rolled plate with a total hot-rolling deformation of ≥85%; S4: Cold rolling: The hot-rolled plate from step S3 is cold-rolled with a total cold rolling reduction of 72%, and then annealed at 420°C for 3 hours to obtain the finished alloy. S5: Anneal the finished alloy from S4 again at 340℃ for 1 hour, and then slit it using a slitting machine to obtain aluminum foil material for heat exchangers.

[0042] The functional refining agent was obtained from Preparation Example 1.

[0043] Example 4 An aluminum foil material for heat exchangers and its preparation method are described. The specific implementation method is the same as in Example 1, except that the functional refining agent is obtained from Preparation Example 2.

[0044] Example 5 An aluminum foil material for heat exchangers and its preparation method are described. The specific implementation method is the same as in Example 1, except that the functional refining agent is obtained from Preparation Example 3.

[0045] Example 6 An aluminum foil material for heat exchangers and its preparation method are described. The specific implementation method is the same as in Example 1, except that the functional refining agent is obtained from Preparation Example 4.

[0046] Comparative Example 1 An aluminum foil material for heat exchangers and its preparation method are described. The specific implementation method is the same as in Example 1, except that manganese and zirconium are not added.

[0047] Comparative Example 2 An aluminum foil material for heat exchangers and its preparation method are described. The specific implementation method is the same as in Example 1, except that manganese is not added.

[0048] Comparative Example 3 An aluminum foil material for heat exchangers and its preparation method are described. The specific implementation method is the same as in Example 1, except that zirconium is not added.

[0049] Comparative Example 4 An aluminum foil material for heat exchangers and its preparation method are described. The specific implementation method is the same as in Example 1, except that rare earth elements are not added.

[0050] Comparative Example 5 An aluminum foil material for heat exchangers and its preparation method are described. The specific implementation method is the same as in Example 1, except that cerium is not added.

[0051] Comparative Example 6 An aluminum foil material for heat exchangers and its preparation method are disclosed. The specific implementation method is the same as that in Example 1, except that the mass ratio of cerium, samarium and yttrium is 5:0.5:3.

[0052] Comparative Example 7 The aluminum foil material used in the heat exchanger of this comparative example is 3003 aluminum alloy, which is commonly used in heat exchangers.

[0053] Comparative Example 8 An aluminum foil material for heat exchangers and its preparation method are described. The specific implementation method is the same as in Example 1, except that no functional refining agent is added in step S2.

[0054] Performance testing The following tests were performed on the aluminum foil material samples obtained in each embodiment and comparative example: (1) Tensile strength: Standard tensile specimens were prepared according to GB / T228-2002, and tensile test was performed on an Instrom 30KN tensile testing machine at a tensile speed of 0.5mm / min. The measured length was 50mm. The tensile strength after brazing at 600℃ for 10min was measured. (2) Corrosion potential: Tested according to standard ASTM G69-97.

[0055] The test results are shown in Table 1: Table 1 As shown in Table 1, the aluminum foil materials prepared in Examples 1-3 have high strength and corrosion resistance, and are high-performance aluminum foil core materials. A comparison of the data from Example 4 and Example 1 shows that changing the amount of Na3AlF6 added in step (1) to replace yttrium fluoride and cerium fluoride during the preparation of the functional refining agent affected the effective rare earth content, thus impacting the strength and corrosion resistance of the aluminum foil materials to varying degrees. A comparison of the data from Example 5 and Example 1 shows that changing the preparation steps during the preparation of the functional refining agent resulted in poorer microstructure uniformity and a significant decrease in corrosion resistance. A comparison of the data from Example 6 and Example 1 shows that the absence of potassium fluorozirconate during the preparation of the functional refining agent led to a sharp reduction in grain boundary migration resistance at high temperatures, making the grains more prone to coarsening and significantly affecting tensile strength. A comparison of the data from Comparative Examples 1-6, Comparative Example 8, and Example 1 shows that the strength and corrosion resistance of the aluminum foil materials prepared in this application are affected by the raw material ratio. Selecting a raw material ratio within the specified range resulted in aluminum foil materials with high strength and good corrosion resistance. If the content of each element is outside the scope of protection of this application, or if some components are outside the formula, the strength and corrosion resistance of the aluminum foil material cannot achieve the expected results. A comparison of the data from Comparative Example 7 and Example 1 shows that, compared to the commonly used 3003 alloy for heat exchangers, the aluminum foil material prepared in this application represents a significant breakthrough in both strength and corrosion resistance, further improving its applicability in the field of heat exchangers.

[0056] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. An aluminum foil material for heat exchangers, characterized in that, The aluminum foil contains the following components by weight percentage (100%): 0.25-0.50% iron, 0.10-0.20% silicon, 0.8-1.3% manganese, 0.8-1.1% zinc, 0.03-0.05% titanium, 0.08-0.12% zirconium, 0.2-0.25% rare earth elements, ≤0.03% copper, ≤0.005% magnesium, with the remainder being aluminum and unavoidable impurities, the total content of which is not greater than 0.3%.

2. The aluminum foil material for heat exchangers according to claim 1, characterized in that, The aluminum foil contains the following components in 100% by weight: 0.30% iron, 0.12% silicon, 1.15% manganese, 0.95% zinc, 0.035% titanium, 0.11% zirconium, 0.23% rare earth elements, 0.03% copper, 0.005% magnesium, with the remainder being aluminum and unavoidable impurities.

3. A method for preparing an aluminum foil material for a heat exchanger according to any one of claims 1 or 2, characterized in that, Includes the following steps: S1: Ingredients: Ingredients are prepared in accordance with the components and mass percentages described in any one of claims 1 or 2; S2: Smelting and refining: Smelt the ingredients from step S1 to obtain aluminum alloy melt. When the melt temperature reaches 730-750℃, add functional refining agent for refining treatment. After standing for 10-15 minutes, remove the slag from the surface of the aluminum alloy melt and cast it into an ingot. S3: Hot rolling: The ingot from step S2 is cut and milled, then homogenized and annealed at 600-620℃ for 15-24 hours and cooled, and then hot rolled to obtain a hot-rolled plate with a total hot rolling deformation of ≥85%; S4: Cold rolling: The hot-rolled plate from step S3 is cold-rolled with a total cold rolling reduction of 70-75%, and then annealed at 400-420℃ for 3-5 hours to obtain the finished alloy. S5: Anneal the finished alloy from S4 again at 300-340℃ for 1-3 hours, and then slit it using a slitting machine to obtain the aluminum foil material for the heat exchanger.

4. The method for preparing aluminum foil material for heat exchangers according to claim 3, characterized in that, The rare earth element is one or more of cerium, samarium, and yttrium.

5. The method for preparing aluminum foil material for heat exchangers according to claim 4, characterized in that, The rare earth elements are a mixture of cerium, samarium and yttrium, with a mass ratio of 5:(1-2):(1-3).

6. The method for preparing aluminum foil material for heat exchangers according to claim 4, characterized in that, The functional refining agent comprises component A and component B. Component A comprises the following raw materials in parts by weight: 40-55 parts Na3AlF6, 10-15 parts magnesium carbonate, 8-12 parts potassium fluorozirconate, 25-30 parts aluminum fluoride, 10-12 parts potassium fluoroaluminate, 5-10 parts graphite powder, and 10-20 parts titanium diboride. Component B is composed of hexafluoroethane, titanium dioxide, yttrium fluoride, and cerium fluoride in a weight ratio of 5:1.5-2:0.3-0.5:0.5-1.

7. The method for preparing aluminum foil material for heat exchangers according to claim 6, characterized in that, The mass ratio of material A to material B is (2.5-3):

1.

8. The method for preparing aluminum foil material for heat exchangers according to claim 6, characterized in that, The amount of the functional refining agent added is 0.1-0.5% of the mass of the aluminum alloy melt.

9. The method for preparing aluminum foil material for heat exchangers according to claim 6, characterized in that, The preparation steps of the functional refining agent are as follows: (1) Take part of Na3AlF6 from material A and yttrium fluoride and cerium fluoride from material B, dry them at 200-250℃ for 2-4 hours, then heat them to 700-750℃ and treat them with stirring for 0.5-1 hours. Quickly transfer them to a preheated metal mold, cool them, crush them and sieve them to obtain the pre-melted material. (2) After crushing and sieving the remaining raw materials, mix them thoroughly, add the pre-melted material from step (1) and mix for 20-40 minutes, then treat at 90-100℃ for 1-3 hours, sieve and cool to obtain the functional refining agent.

10. The method for preparing aluminum foil material for heat exchangers according to claim 9, characterized in that, In step (1), the amount of Na3AlF6 added is 2-4 times the total mass of yttrium fluoride and cerium fluoride.

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