Aluminum alloy composite material for fuel cell radiator and method for manufacturing the same

Abstract

The application discloses an aluminum alloy composite material for a fuel cell radiator, which comprises an outer brazing layer, a barrier layer, a core layer and an inner brazing layer; the core layer comprises the following components and has the following weight percentage: Si is less than or equal to 0.4%, Fe is 0.2-0.4%, Cu is 0.25-0.9%, Mn is 1.2-1.9%, Mg is 0.15-0.3%, Ti is 0.08-0.25%, the rest is Al and unavoidable impurities with a total amount less than 0.15%; the barrier layer does not contain Mg; the inner brazing layer is 4045 or 4343 alloy; the outer brazing layer is 4045 or 4343 alloy and is pre-embedded with brazing flux; the composite ratio of the outer brazing layer is 8-12%, the composite ratio of the inner brazing layer is 3.5-6.5%, and the composite ratio of the barrier layer is 15-25%. Through material structure design optimization, brazing performance is met, brazing flux use is reduced, brazing flux residue is less after brazing, the strict conductivity requirement of a fuel cell cooling liquid is met, and the safety of a fuel cell system is improved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of aluminum alloy manufacturing, in particular to an aluminum alloy composite material for a fuel cell radiator and a preparation method thereof. BACKGROUND

[0002] Hydrogen energy has the dual roles of clean secondary energy and efficient energy storage carrier. Hydrogen gas, as a medium for large-capacity seasonal energy storage, will play an important role in the process of energy transformation. Fuel cells are the best means of hydrogen energy utilization, and therefore, fuel cells are regarded as a sustainable technology.

[0003] Under normal operating conditions, the electrical efficiency of a fuel cell is 40% to 60%, and the remaining energy is transferred in the form of heat. From the perspective of waste heat utilization, good thermal management technology is necessary to improve the overall thermal-electric efficiency of the fuel cell. The heat source of the fuel cell mainly comes from the entropy heat of the oxidation-reduction reaction of hydrogen and oxygen, the irreversible electrochemical reaction heat, the Ohm heat of current transmission, and the latent heat of phase change of water. If the heat of the stack cannot be dissipated in time, the system temperature will continue to rise, leading to serious dry membrane phenomenon of the proton membrane and exacerbating the catalyst decay, and even local hot spots, which will cause irreversible damage to the membrane and lead to the generation of perforation, and direct contact between hydrogen and oxygen will bring serious safety hazards.

[0004] A fuel cell relies on a cooling system to remove heat. The cooling system of a fuel cell engine includes a radiator, a water pump, external pipelines and valves, and an internal cooling channel of the stack. During heat dissipation, the cooling liquid needs to flow through the high-potential bipolar plate. If the cooling liquid has high electrical conductivity, high-voltage electricity will be conducted to the outside through the cooling liquid, posing a risk of electric shock. Therefore, the cooling liquid has high requirements in terms of insulation. The main reason for the increase in the electrical conductivity of the cooling liquid is that the flux sprayed during the production of the radiator precipitates conductive ions during use. When the cooling liquid circulates in the radiator, the impurities in the cooling liquid will continuously increase, leading to an increase in the electrical conductivity of the cooling liquid, a decrease in the resistance value, and a decrease in the insulation performance. Frequent replacement of the cooling liquid not only reduces the convenience of using the vehicle, but also increases the cost of using the vehicle, and increases the safety risk of the vehicle. Therefore, in order to keep the electrical conductivity of the cooling liquid low, a deionizer needs to be installed in the cooling system to keep the electrical conductivity of the cooling liquid low.

[0005] The existing fuel cell radiator uses 3003 / 4xxx aluminum alloy brazing material with a traditional process. When the parts are brazed, a flux needs to be sprayed, resulting in excessive flux residue that is difficult to clean. The flux remaining in the weld inside and outside after welding will produce K + , K +The emergence of the system conductivity increases, reduces the safety of the whole vehicle system, and has a negative impact on the environment and the performance and quality of the final product, so it is usually necessary to flush for a long time (about 10 days) to reduce the conductivity to meet the use requirements, but during use, a small amount of residual flux in the material will flow out, thereby causing the conductivity to rise and increasing the safety risk.

[0006] In addition, the main material in the deionizer is adsorption resin, and the service life of the deionizer mainly depends on the ion precipitation amount in the fuel cell system. When the deionizer cannot exchange more anions and cations, the deionizer is invalid. Therefore, reducing the ion precipitation amount is of great significance to improve the service life of the deionizer, reduce the cost, and improve the safety factor. SUMMARY

[0007] In order to solve the above-mentioned deficiencies existing in the field, the present application aims to provide an aluminum alloy composite material for a fuel cell radiator and a preparation method thereof. Through material structure design optimization, the brazing performance is met while the flux usage is reduced, and the flux residue after brazing is less, so as to meet the stringent conductivity requirements of the fuel cell coolant and improve the safety of the fuel cell system.

[0008] According to an aspect of the present application, an aluminum alloy composite material for a fuel cell radiator is provided, comprising: an outer brazing layer, a barrier layer, a core layer, and an inner brazing layer.

[0009] The core layer is composed of Si≤0.4%, Fe 0.2-0.4%, Cu 0.25-0.9%, Mn 1.2-1.9%, Mg 0.15-0.3%, Ti 0.08-0.25%, the rest is Al and unavoidable impurities with a total amount less than 0.15%.

[0010] The barrier layer is composed of Mg;

[0011] The inner brazing layer is 4045 or 4343 alloy; the outer brazing layer is 4045 or 4343 alloy and is pre-embedded with flux;

[0012] The composite ratio of the outer brazing layer is 8-12%, the composite ratio of the inner brazing layer is 3.5-6.5%, and the composite ratio of the barrier layer is 15-25%.

[0013] According to some embodiments of the present application, the concentration of the pre-embedded flux is 1.0-2.5g / m 2 .

[0014] According to some embodiments of the present application, the barrier layer is 3003 alloy.

[0015] According to some embodiments of the present application, the core layer is a Mg-containing 3003 MOD alloy.

[0016] According to some embodiments of the present application, the thickness of the fuel cell radiator aluminum alloy composite material is 0.24-0.35 mm.

[0017] According to another aspect of the present application, a method for preparing a fuel cell radiator aluminum alloy composite material is also provided, comprising:

[0018] respectively manufacturing a core layer ingot, a barrier layer ingot, an outer brazing layer ingot and an inner brazing layer ingot;

[0019] respectively performing head-to-tail sawing and face milling on the core layer ingot, the barrier layer ingot, the outer brazing layer ingot and the inner brazing layer ingot;

[0020] respectively performing hot rolling on the milled barrier layer ingot, the outer brazing layer ingot and the inner brazing layer ingot according to a composite ratio;

[0021] preparing a pre-embedded brazing flux blank plate of the outer brazing layer;

[0022] respectively performing surface mechanical treatment on the outer brazing layer, the pre-embedded brazing flux blank plate, the barrier layer, the core layer and the inner brazing layer;

[0023] stacking the outer brazing layer, the pre-embedded brazing flux blank plate, the barrier layer, the core layer and the inner brazing layer in sequence, performing composite hot rolling to obtain a hot-rolled coil with a thickness of 5-8 mm;

[0024] performing cold rolling on the hot-rolled coil after cooling to room temperature to obtain a cold-rolled coil;

[0025] performing annealing on the cold-rolled coil, and the fuel cell radiator aluminum alloy composite material is obtained.

[0026] According to some embodiments of the present application, the preparation of the pre-embedded brazing flux blank plate of the outer brazing layer comprises:

[0027] mixing the brazing flux powder and the outer brazing layer powder uniformly and then performing hot isostatic pressing to obtain a hot isostatic pressing ingot;

[0028] performing milling and hot rolling on the hot isostatic pressing ingot, and the pre-embedded brazing flux blank plate of the outer brazing layer is obtained.

[0029] According to some embodiments of the present application, the hot rolling temperature is 500±10℃, and the holding time is 12-24h.

[0030] According to some embodiments of the present application, the temperature of the composite hot rolling is 500±10℃, and the holding time is 12-24h.

[0031] According to some embodiments of the present application, the annealing temperature is 230-270℃, and the holding time is 2-3h.

[0032] Compared with the prior art, the present application at least includes the following beneficial effects:

[0033] The present application provides an aluminum alloy composite material for fuel cell radiators, which is designed by optimizing the material structure to meet the brazing performance while reducing the use of brazing flux, so as to achieve less residual brazing flux after brazing, meet the stringent conductivity requirements of the fuel cell coolant, and improve the safety of the fuel cell system. At the same time, the manufacturing cost of the material is moderate, the strength is higher than that of the traditional 3003 / 4xxx material, and the material can be mass-produced, which has good economic effect and popularization value.

[0034] The composite material of the present application is designed as 4 layers, the outer brazing layer is pre-embedded with brazing flux, the core material alloy contains an appropriate amount of Mg element, and a 3003 barrier layer is introduced to block the influence of the Mg element in the core material on the brazing flux. During the brazing process of the material, no additional brazing flux needs to be sprayed, which reduces the use and residue of the brazing flux; the inner side of the pipe material does not need to be sprayed with brazing flux, and brazing is achieved by breaking the oxide film through the Mg element, which improves the cleanliness of the pipeline and avoids the dissolution of the brazing flux in the coolant to produce K + , which increases the conductivity of the coolant; during the working process of the water tank, no brazing flux is exuded from the inner side of the pipe material, which effectively controls the rebound of the conductivity, thereby ensuring the stability of the conductivity of the coolant system, improving the safety of the cooling system, and prolonging the service life of the fuel cell cooling water tank.

[0035] The present application provides a preparation method of an aluminum alloy composite material for fuel cell radiators, which adopts a pre-embedded brazing flux design, cancels the brazing flux pre-spraying process, includes the preparation of a slurry of brazing flux and water, brazing flux coating or spraying, and drying process, shortens the production process, improves the production efficiency of the radiator water tank, and thus can reduce the total cost of the product.

[0036] The present application prepares an aluminum alloy composite material for fuel cell radiators with pre-embedded brazing flux on the outer brazing layer by traditional preparation methods of aluminum alloy heat exchanger composite materials such as melting, hot rolling, cold rolling, and annealing, which has no special requirements for manufacturing equipment capacity and manufacturing process, the product quality is easy to control, the performance is stable, the yield is high, and has the advantages of cost suitability and marketization promotion. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 FIG. 1 is a structural schematic diagram of the aluminum alloy composite material for fuel cell radiators of the present application.

[0038] Figure 2 FIG. 3 is a schematic diagram of the pipe material section prepared by the composite material of the present application.

[0039] Figure 3 FIG. 4 is a metallographic picture of the pipe material joint weld section after brazing of the example embodiment of the present application.

[0040] Figure 4 Microstructure of the tube-to-fin joint after brazing for the example embodiment of the present application.

[0041] Figure 5 Microstructure of the tube-to-fin joint after brazing for the example comparative example 1 of the present application.

[0042] Figure 6 Microstructure of the tube-to-fin joint after brazing for the example comparative example 3 of the present application.

[0043] Figure 7 Mg diffusion scanning electron microscope analysis of the outer surface of the tube after brazing for the example comparative example 5 of the present application. DETAILED DESCRIPTION

[0044] The technical solutions of the present application will be described clearly and completely below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0045] It is particularly pointed out that similar replacements and changes made for the present application are obvious to those skilled in the art, and they are considered to be included in the present application. The related personnel can obviously make changes or appropriate changes and combinations to the methods and applications described herein without departing from the content, spirit and scope of the present application, to realize and apply the technology of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments of the present application.

[0046] Unless otherwise specified, the present application is carried out under conventional conditions or the conditions recommended by the manufacturer. The raw materials or excipients used, and the reagents or instruments used, unless otherwise specified, are conventional products that can be obtained commercially.

[0047] The present application will be described in detail below.

[0048] The fuel cell radiator aluminum alloy composite material of the present application has a thickness of 0.24-0.35 mm and has a four-layer structure (see FIG. 1) Figure 1 ), which is an outer brazing layer, a barrier layer, a core layer and an inner brazing layer.

[0049] The core layer uses 3003MOD alloy containing Mg, and the main components are Si≤0.4% (mass fraction, the same below), Fe 0.2-0.4%, Cu 0.25-0.9%, Mn 1.2-1.9%, Mg 0.15-0.3%, Ti 0.08-0.25%, and the rest is Al and unavoidable impurities with a total amount less than 0.15%. Among them, the Mn and Cu elements of the core layer can be solid-solved into the aluminum matrix after brazing, improving the mechanical properties after brazing, Ti can refine the grain and improve the corrosion resistance of the alloy, the core layer contains Si and Mg elements, and Mg2Si dispersed phase can be precipitated after brazing to improve the strength.

[0050] The outer brazing layer uses 4045 or 4343 alloy, mainly for brazing.

[0051] The heat sink product is usually brazed by controlled atmosphere brazing (CAB), which needs to spray flux to break the oxide film. When the material is mainly used as a heat sink water tank pipe (the cross-sectional morphology is shown in Figure 2 ), the inner side of the pipe does not need to be sprayed with flux, and Mg is used to eliminate the harmful effects of oxygen and water vapor in the environment, and at the same time, it penetrates into the surface layer of the base material, together with the diffused Si, to make the surface layer form an Al-Si-Mg alloy with low melting point and melt, thereby destroying the combination of the surface oxide film and the base material, allowing the molten filler metal to wet the base material, spread along the base material under the film, and float the surface film to remove it, thereby realizing brazing. The cooling liquid flows inside the pipe, and the elimination of flux penetration can avoid the influence of flux penetration on the electrical conductivity of the cooling liquid, keeping the electrical conductivity stable. It should be noted that the usual flux-free material is designed as a two-layer 4XXX filler metal layer, the outer filler metal layer does not contain Mg, and the inner filler metal layer contains about 0.15% Mg, which is used to break the oxide film and realize flux-free brazing. Because both filler metal layers contain a high amount of Si element, the material has poor plasticity, and the composite and manufacturing are difficult. In the present application, Mg element is added to the core material, and the Mg element content is reasonably designed, so that flux-free brazing can be realized with only one filler metal layer, simplifying the material structure, reducing the process difficulty and manufacturing cost.

[0052] The outer side of the pipe needs to be brazed with the fin, and the brazing quality requirement is high, which is different from the brazing layer on the inner side of the pipe. The outer side of the pipe is pre-embedded with flux, and the pre-embedded flux concentration is 1.0-2.5 g / m 2 , which is much lower than the normal flux concentration requirement of normal flux spraying (normal flux concentration is about 8-10 g / m 2 ). The use of pre-embedded flux eliminates the flux pre-spraying process, shortens the production process, and reduces the cost. When the pre-embedded flux concentration is less than 1 g / m 2 , the brazing equipment gap, brazing process, etc. are required to be higher, and the brazing qualified rate is low; when the flux concentration is higher than 2.5 g / m 2At this time, the pre-embedding process of the brazing agent is difficult to implement, production is inconvenient, and manufacturing and economic costs are increased.

[0053] Since the core material contains Mg elements, the Mg elements will diffuse to the surface of the aluminum alloy during brazing, and the Mg elements will react with the brazing agent, thereby causing the brazing agent to fail. Therefore, a barrier layer is needed to block the diffusion of the Mg elements to the outside brazing layer. The barrier layer can be made of 3003 alloy, which can block the diffusion of the Mg elements to the outside surface of the pipe material while having a certain strength.

[0054] Since the mechanical properties of the brazing layer and the barrier layer alloy are not as good as those of the core material alloy, under the same core material alloy, the larger the composite ratio of the brazing layer and the barrier layer, the worse the mechanical properties of the composite material. Therefore, it is desirable to reasonably design the composite ratio of the brazing layer and the barrier layer under the condition of ensuring brazing quality and effectively preventing the diffusion of Mg elements to the surface of the material.

[0055] The composite ratio of the outer brazing layer of the aluminum alloy composite material of the present application is 8-12%, and the composite ratio of the inner brazing layer is 3.5-6.5%. The composite ratio of the brazing layer is asymmetrically designed, and reducing the composite ratio of the inner brazing layer can reduce the risk of pipe blockage caused by solder accumulation.

[0056] The composite ratio of the barrier layer is designed to be 15-25%. When the composite ratio of the barrier layer is less than 15%, the thickness of the barrier layer is less than the diffusion depth of the Mg elements after brazing, and part of the Mg elements can still diffuse to the outer brazing layer, which cannot completely block the destruction of the brazing agent by Mg during brazing. When the composite ratio of the barrier layer is higher than 25%, although the barrier layer can effectively block the destruction of the brazing agent in the outer brazing layer by Mg, the composite ratio of the core layer which mainly plays a strengthening role is correspondingly reduced, thereby reducing the overall strength of the material.

[0057] The preparation method of the aluminum alloy composite material for the fuel cell radiator of the present application comprises:

[0058] (1) The elements of the core layer, the barrier layer, the outer brazing layer, and the inner brazing layer are respectively prepared according to the element composition, and the core layer ingot, the barrier layer ingot, the outer brazing layer ingot, and the inner brazing layer ingot are obtained by feeding, melting, electromagnetic stirring, slagging, refining, degassing, and semi-continuous casting;

[0059] (2) Sawing and milling: the core layer ingot, the barrier layer ingot, the outer brazing layer ingot, and the inner brazing layer ingot are sawed and milled according to the specification requirements: the sawing length is 100-300 mm; and the milling amount is 10-15 mm;

[0060] (3) Heating and hot rolling: the barrier layer ingot, the outer brazing layer ingot and the inner brazing layer ingot treated by sawing and milling are respectively subjected to hot rolling treatment according to the composite ratio (i.e. the percentage of the thickness of each layer to the total thickness) of the aluminum alloy composite material for fuel cell radiators, and are rolled to the target thickness to obtain the barrier layer hot-rolled plate, the outer brazing layer hot-rolled plate and the inner brazing layer hot-rolled plate; the hot rolling temperature is selected to be 500±10°C, and the heating time is 12-24h;

[0061] (4) Preparation of pre-embedded brazing agent brazing layer blank plate: the brazing agent powder (such as potassium fluoroaluminate brazing agent powder) and aluminum-silicon alloy (4045 or 4343) powder are uniformly mixed and then subjected to hot isostatic pressing to obtain a hot isostatic pressing ingot, which is subjected to milling and hot rolling to obtain a pre-embedded brazing agent brazing layer blank plate with a desired thickness;

[0062] (5) Surface mechanical treatment: the surfaces of the outer brazing layer hot-rolled plate, the pre-embedded brazing agent brazing layer blank plate, the barrier layer hot-rolled plate and the inner brazing layer hot-rolled plate are polished to expose the fresh metal color and remove the surface oxide layer;

[0063] (6) Composite hot rolling: the outer brazing layer hot-rolled plate, the pre-embedded brazing agent brazing layer blank plate, the barrier layer hot-rolled plate, the core layer ingot after milling and the inner brazing layer hot-rolled plate are stacked in the above-mentioned order, and are subjected to composite hot rolling to a thickness of 5-8mm, and are coiled to obtain a hot-rolled coil;

[0064] (7) Cold rolling: the hot-rolled coil is cooled to room temperature and is subjected to multi-pass cold rolling to a finished product thickness of 0.24-0.35mm,

[0065] (8) Annealing: the cold-rolled coil is annealed at 230-270°C for 2-3h to obtain a finished product in an incomplete annealing state, thereby obtaining the aluminum alloy composite material for fuel cell radiators, the material undergoes incomplete recrystallization, retains the fibrous deformation structure of cold rolling, eliminates part of the processing stress, and has certain strength and plasticity, which can ensure the subsequent pipe processing and assembly strength.

[0066] Example 1

[0067] The aluminum alloy composite material for fuel cell radiators of the present application is prepared, wherein the core layer has a chemical composition of Si 0.08%, Fe 0.3%, Cu 0.7%, Mn 1.5%, Mg 0.23%, Ti 0.15%, and the balance of Al and unavoidable impurities with a total amount of less than 0.15%. The barrier layer is 3003 aluminum alloy, the inner brazing layer is 4343 aluminum alloy, the outer brazing layer is 4343 aluminum alloy, and the pre-embedded brazing agent concentration of the outer brazing layer is 1.5g / m 2 .

[0068] (1) According to the element composition of the core alloy, the barrier layer alloy, the outer brazing layer alloy and the inner brazing layer alloy, respectively, the ingredients are prepared, and after melting, electromagnetic stirring, skimming, refining, degassing and semi-continuous casting, the core layer ingot, the barrier layer ingot and the inner and outer brazing layer ingots with a specification of 450mmx1290mmx7000mm are obtained;

[0069] (2) Sawing and milling: according to the specification requirements, the head and tail of each ingot is sawed and milled: the sawing length is 200mm; the core layer and the barrier layer ingot are milled by 10mm; the inner and outer brazing layer ingots are milled by 12mm.

[0070] (3) Heating and hot rolling: the barrier layer and the inner and outer brazing layer ingots treated by sawing and milling are heated at 500±10℃ for 13h, and rolled to the calculated thickness according to the composite ratio, the barrier layer is rolled to 132mm, the outer brazing layer is rolled to 56mm, and the inner brazing layer is rolled to 33mm.

[0071] (4) Preparation of pre-embedded brazing agent brazing layer blank plate: the potassium fluoroaluminate (KAlF4) brazing agent powder and 4343 powder are uniformly mixed and then hot isostatic pressed to obtain a hot isostatic pressed blank ingot, which is milled and hot rolled to obtain a 4343 pre-embedded brazing agent brazing layer blank plate with a thickness of 10mm;

[0072] (5) Surface mechanical treatment: the surface of the barrier layer, the 4343 pre-embedded brazing agent brazing layer blank plate, the outer brazing layer hot rolled plate and the inner brazing layer hot rolled plate is polished to expose the fresh metal color and remove the surface oxide layer;

[0073] (6) Composite hot rolling: the above-mentioned outer brazing layer hot rolled plate, pre-embedded brazing agent brazing layer blank plate, barrier layer hot rolled plate, milled core layer ingot and inner brazing layer hot rolled plate are stacked in the above-mentioned order, and composite hot rolling and coiling are carried out to obtain a hot rolled coil with a thickness of 8mm;

[0074] (7) Cold rolling: after the hot rolled coil is cooled to room temperature, it is cold rolled in multiple passes to a finished thickness of 0.30mm,

[0075] (8) Annealing: the cold rolled coil is annealed at 250℃ for 3h to obtain a finished product in an incomplete annealing state, thereby obtaining an aluminum alloy composite material for fuel cell heat sinks.

[0076] The thickness of the aluminum alloy composite material is 0.3mm, the composite ratio of the outer brazing layer with pre-embedded brazing agent is 10%, the composite ratio of the barrier layer is 20%, and the composite ratio of the inner brazing layer is 5%; the yield strength R p 0.2 of the composite plate is 170MPa, the tensile strength R m is 205MPa, and the elongation A 50 after breaking is 9.3%.

[0077] Example 2

[0078] An aluminum alloy composite material for fuel cell radiators according to the present application is prepared, wherein the core layer has a chemical composition of Si 0.05%, Fe 0.25%, Cu 0.5%, Mn 1.7%, Mg 0.18%, Ti 0.10%, the balance being Al and unavoidable impurities in a total amount of less than 0.15%. The barrier layer is 3003 aluminum alloy, the inner brazing layer is 4045 aluminum alloy, the outer brazing layer is 4045 aluminum alloy, and the pre-embedded flux concentration of the outer brazing layer is 1.0 g / m 2 .

[0079] (1) The core layer alloy, the barrier layer alloy, the outer brazing layer alloy, and the inner brazing layer alloy are respectively prepared by batching, melting, electromagnetic stirring, skimming, refining, degassing, and semi-continuous casting to obtain core layer ingots, barrier layer ingots, and inner and outer brazing layer ingots each having a size of 450 mm x 1290 mm x 7000 mm;

[0080] (2) Sawing and milling: the core layer ingots, the barrier layer ingots, and the inner and outer brazing layer ingots are sawed and milled at the head and tail according to the size requirements: the sawing length is 200 mm; the core layer and the barrier layer ingots are milled by 15 mm; and the inner and outer brazing layer ingots are milled by 15 mm.

[0081] (3) Heating and hot rolling: the barrier layer and the inner and outer brazing layer ingots subjected to sawing and milling are heated at 500 ± 10°C for 15 h, and are rolled to the calculated thickness according to the composite ratio: the barrier layer is rolled to 167 mm, the outer brazing layer is rolled to 43 mm, and the inner brazing layer is rolled to 27 mm.

[0082] (4) Pre-embedded flux brazing layer blank preparation: the potassium fluoroaluminate (KAlF4) flux powder and the 4045 powder are uniformly mixed and then hot isostatic pressed to obtain a hot isostatic pressed blank ingot, which is milled and hot rolled to obtain a 4045 pre-embedded flux brazing layer blank with a thickness of 10 mm;

[0083] (5) Surface mechanical treatment: the surfaces of the barrier layer plate, the 4045 pre-embedded flux brazing layer blank, the outer brazing layer hot rolled plate, and the inner brazing layer hot rolled plate are polished to expose the fresh metal color and remove the surface oxide layer;

[0084] (6) Composite hot rolling: the above-mentioned outer brazing layer hot rolled plate, pre-embedded flux brazing layer blank, barrier layer hot rolled plate, milled core layer ingot, and inner brazing layer hot rolled plate are stacked in the above-mentioned order, and are subjected to composite hot rolling and coiling to obtain a hot rolled coil with a thickness of 8 mm.

[0085] (7) Cold rolling: the hot-rolled coil is cooled to room temperature and then cold-rolled in multiple passes to a finished thickness of 0.24 mm,

[0086] (8) Annealing: the cold-rolled coil is annealed at 240°C for 3h to obtain a finished product in an incomplete annealing state, thereby obtaining the aluminum alloy composite material for fuel cell radiators.

[0087] The aluminum alloy composite material has a thickness of 0.24 mm, an outer brazing layer pre-embedded with flux at a composite ratio of 8%, a barrier layer at a composite ratio of 25%, and an inner brazing layer at a composite ratio of 4%. The yield strength R p 0.2 of the composite sheet is 162 MPa, the tensile strength R m is 193 MPa, and the elongation A 50 after fracture is 8.6%.

[0088] Example 3

[0089] The aluminum alloy composite material for fuel cell radiators of the present application is prepared, wherein the core layer has a chemical composition of Si 0.1%, Fe 0.25%, Cu 0.9%, Mn 1.3%, Mg 0.25%, Ti 0.2%, and the balance of Al and unavoidable impurities with a total amount of less than 0.15%. The barrier layer is 3003 aluminum alloy, the inner brazing layer is 4045 aluminum alloy, the outer brazing layer is 4343 aluminum alloy, and the outer brazing layer has a pre-embedded flux concentration of 2.5 g / m 2 .

[0090] (1) The core layer alloy, the barrier layer alloy, the outer brazing layer alloy, and the inner brazing layer alloy are respectively prepared by batching, melting, electromagnetic stirring, slagging, refining, degassing, and semi-continuous casting to obtain core layer ingots, barrier layer ingots, outer brazing layer ingots, and inner brazing layer ingots with a specification of 450 mm x 1290 mm x 7000 mm;

[0091] (2) Sawing and milling: the core layer ingots, the barrier layer ingots, the outer brazing layer ingots, and the inner brazing layer ingots are sawed and milled at the head and tail according to the specification requirements: the sawing length is 300 mm; the core layer and the barrier layer ingots are milled by 15 mm; the inner brazing layer ingots and the outer brazing layer ingots are milled by 15 mm.

[0092] (3) Heating and hot rolling: the barrier layer, the outer brazing layer, and the inner brazing layer ingots after sawing and milling are heated at 500±10°C for 15h, and are rolled to the calculated thickness according to the composite ratio: the barrier layer is rolled to 94 mm, the outer brazing layer is rolled to 60 mm, and the inner brazing layer is rolled to 38 mm.

[0093] (4) Pre-embedded brazing flux brazing layer blank plate preparation: uniformly mix KAlF4 flux powder and 4343 powder, then hot isostatic pressing to obtain a hot isostatic pressing blank ingot, milling and hot rolling the hot isostatic pressing blank ingot to obtain a 4343 pre-embedded brazing flux brazing layer blank plate with a thickness of 15 mm;

[0094] (5) Surface mechanical treatment: grinding the surfaces of the barrier layer hot-rolled plate, the 4343 pre-embedded brazing flux brazing layer blank plate, the outer side brazing layer hot-rolled plate and the inner side brazing layer hot-rolled plate to expose fresh metal color and remove surface oxide layers;

[0095] (6) Composite hot rolling: stacking the above-mentioned outer side brazing layer hot-rolled plate, the pre-embedded brazing flux brazing layer blank plate, the barrier layer hot-rolled plate, the milled core layer ingot and the inner side brazing layer hot-rolled plate in the above-mentioned order, composite hot rolling and coiling to obtain a hot-rolled coil with a thickness of 6 mm;

[0096] (7) Cold rolling: cold rolling the hot-rolled coil through multiple passes after cooling to room temperature, and rolling to a finished product thickness of 0.32 mm,

[0097] (8) Annealing: annealing the cold-rolled coil at 240°C for 3 h to obtain a finished product in an incomplete annealing state, thereby obtaining an aluminum alloy composite material for fuel cell radiators.

[0098] The aluminum alloy composite material has a thickness of 0.32 mm, a pre-embedded brazing flux outer side brazing layer composite ratio of 12%, a barrier layer composite ratio of 15%, and an inner side brazing layer composite ratio of 6%; the composite plate has a yield strength R p 0.2 of 186 MPa, a tensile strength R m of 217 MPa, and an elongation A 50 of 7.8%.

[0099] Comparative Example 1

[0100] The preparation steps and the compositions of each layer are the same as in Example 1, except that no barrier layer is provided.

[0101] An aluminum alloy composite material for fuel cell radiators is prepared, wherein the core layer has a chemical composition of Si 0.08%, Fe 0.3%, Cu 0.7%, Mn 1.5%, Mg 0.23%, Ti 0.15%, the remainder being Al and unavoidable impurities with a total amount of less than 0.15%; the inner side brazing layer is 4343 aluminum alloy, the outer side brazing layer is 4343 aluminum alloy, and the pre-embedded brazing flux concentration of the outer side brazing layer is 1.5 g / m 2 .

[0102] (1) According to the element composition of the core alloy, the outer brazing layer alloy and the inner brazing layer alloy, ingredients are prepared respectively, and then the core ingot and the inner and outer brazing layer ingots with a specification of 450mmx1290mmx7000mm are obtained after melting, electromagnetic stirring, skimming, refining, degassing and semi-continuous casting;

[0103] (2) Sawing and milling: each ingot is sawed and milled according to the specification requirements: the sawing length is 200mm; the core ingot is milled by 10mm; the inner and outer brazing layer ingots are milled by 12mm.

[0104] (3) Heating and hot rolling: the inner and outer brazing layer ingots treated by sawing and milling are heated at 500±10℃ for 13h, and then rolled to the calculated thickness according to the composite ratio, the outer brazing layer is rolled to 40mm, and the inner brazing layer is rolled to 25mm.

[0105] (4) Preparation of pre-embedded brazing agent brazing layer blank plate: the potassium fluoroaluminate (KAlF4) brazing agent powder and 4343 powder are uniformly mixed and then hot isostatic pressed to obtain a hot isostatic pressed blank ingot, which is milled and hot rolled to obtain a 4343 pre-embedded brazing agent brazing layer blank plate with a thickness of 10mm;

[0106] (5) Surface mechanical treatment: the surface of the 4343 pre-embedded brazing agent brazing layer blank plate, the outer brazing layer hot rolled plate and the inner brazing layer hot rolled plate is polished to expose the fresh metal color and remove the surface oxide layer;

[0107] (6) Composite hot rolling: the above-mentioned outer brazing layer hot rolled plate, pre-embedded brazing agent brazing layer blank plate, milled core ingot and inner brazing layer hot rolled plate are stacked in the above-mentioned order, and then composite hot rolled and coiled to obtain a hot rolled coil with a thickness of 8mm;

[0108] (7) Cold rolling: the hot rolled coil is cooled to room temperature and then cold rolled in multiple passes to a finished thickness of 0.30mm,

[0109] (8) Annealing: the cold rolled coil is annealed at 250℃ for 3h to obtain a finished product in an incomplete annealing state, thereby obtaining an aluminum alloy composite material for fuel cell radiators.

[0110] The thickness of the aluminum alloy composite material is 0.3mm, the composite ratio of the outer brazing layer with pre-embedded brazing agent is 10%, and the composite ratio of the inner brazing layer is 5%; the yield strength R p 0.2 of the composite plate is 202MPa, the tensile strength R m is 233MPa, and the elongation A 50 after fracture is 8.3%.

[0111] Comparative Example 2

[0112] The preparation step and the composition of each layer are the same as those of Example 2, except that no barrier layer is provided and the core layer does not contain Mg element.

[0113] An aluminum alloy composite material for fuel cell radiators is prepared, wherein the chemical composition of the core layer is Si 0.05%, Fe 0.25%, Cu 0.5%, Mn 1.7%, Ti 0.10%, the rest being Al and unavoidable impurities with a total amount less than 0.15%. The inner brazing layer is 4045 aluminum alloy, the outer brazing layer is 4045 aluminum alloy, and the pre-embedded flux concentration of the outer brazing layer is 1.0 g / m 2 .

[0114] (1) The core alloy, the outer brazing layer alloy and the inner brazing layer alloy are respectively prepared according to the element composition, and then the core ingot and the inner and outer brazing layer ingots with a specification of 450 mm x 1290 mm x 7000 mm are obtained after melting, electromagnetic stirring, slagging, refining, degassing and semi-continuous casting;

[0115] (2) Sawing and milling: the core ingot and the inner and outer brazing layer ingots are sawed and milled according to the specification requirements: the sawing length is 200 mm; the core ingot is milled by 15 mm; the inner and outer brazing layer ingots are milled by 15 mm.

[0116] (3) Heating and hot rolling: the inner and outer brazing layer ingots treated by sawing and milling are heated at 500±10°C for 15 h, and then rolled to the calculated thickness according to the composite ratio, the outer brazing layer is rolled to 29 mm, and the inner brazing layer is rolled to 20 mm.

[0117] (4) Pre-embedded flux brazing layer blank plate preparation: the potassium fluoroaluminate (KAlF4) flux powder and 4045 powder are uniformly mixed and then hot isostatic pressed to obtain a hot isostatic pressed ingot, the hot isostatic pressed ingot is milled and hot rolled to obtain a 4045 pre-embedded flux brazing layer blank plate with a thickness of 10 mm;

[0118] (5) Surface mechanical treatment: the surface of the 4045 pre-embedded flux brazing layer blank plate, the outer brazing layer hot rolled plate and the inner brazing layer hot rolled plate is polished to expose the fresh metal color and remove the surface oxide layer;

[0119] (6) Composite hot rolling: the outer brazing layer hot rolled plate, the pre-embedded flux brazing layer blank plate, the milled core ingot and the inner brazing layer hot rolled plate are stacked in the above order, and then composite hot rolled and coiled to obtain a hot rolled coil with a thickness of 8 mm;

[0120] (7) Cold rolling: the hot rolled coil is cooled to room temperature and then cold rolled by multiple passes to a finished thickness of 0.24 mm,

[0121] (8) Annealing: the cold-rolled coil is kept at 240°C for 3h to obtain the finished product in an incomplete annealing state, thereby obtaining the aluminum alloy composite material for fuel cell radiators.

[0122] The thickness of the aluminum alloy composite material is 0.24mm, the composite ratio of the outer brazing layer with pre-embedded brazing flux is 8%, and the composite ratio of the inner brazing layer is 4%; the yield strength R p 0.2 of the composite plate is 203MPa, the tensile strength R m is 229MPa, and the elongation A 50 after fracture is 9.1%.

[0123] Comparative Example 3

[0124] The preparation steps and the compositions of the layers are the same as those of Example 3, except that the pre-embedded brazing flux concentration is less than 1%.

[0125] An aluminum alloy composite material for fuel cell radiators is prepared, wherein the chemical composition of the core layer is Si 0.1%, Fe 0.25%, Cu 0.9%, Mn 1.3%, Mg 0.25%, Ti 0.2%, and the rest is Al and unavoidable impurities with a total amount less than 0.15%; the barrier layer is 3003 aluminum alloy, the inner brazing layer is 4045 aluminum alloy, the outer brazing layer is 4343 aluminum alloy, and the pre-embedded brazing flux concentration of the outer brazing layer is 0.8g / m 2 .

[0126] (1) The core layer alloy, the barrier layer alloy, the outer brazing layer alloy, and the inner brazing layer alloy are respectively prepared according to the element compositions, and then the core layer ingot, the barrier layer ingot, the outer brazing layer ingot, and the inner brazing layer ingot with a specification of 450mmx1290mmx7000mm are obtained after melting, electromagnetic stirring, slagging, refining, degassing, and semi-continuous casting;

[0127] (2) Sawing and milling: the core layer ingot, the barrier layer ingot, the outer brazing layer ingot, and the inner brazing layer ingot are sawed and milled according to the specification requirements: the sawing length is 300mm; the core layer and the barrier layer ingot are milled by 15mm; the inner brazing layer ingot and the outer brazing layer ingot are milled by 15mm.

[0128] (3) Heating and hot rolling: the barrier layer, the outer brazing layer, and the inner brazing layer ingots after sawing and milling are heated at 500±10°C for 15h, and then rolled to the calculated thickness according to the composite ratio: the barrier layer is rolled to 94mm, the outer brazing layer is rolled to 67mm, and the inner brazing layer is rolled to 38mm.

[0129] (4) Pre-embedded brazing flux brazing layer blank plate preparation: uniformly mix KAlF4 flux powder and 4343 powder, then hot isostatic pressing to obtain a hot isostatic pressing blank, and then milling and hot rolling to obtain a 4343 pre-embedded brazing flux brazing layer blank plate with a thickness of 8 mm;

[0130] (5) Surface mechanical treatment: grinding the surfaces of the barrier layer hot-rolled plate, the 4343 pre-embedded brazing flux brazing layer blank plate, the outer side brazing layer hot-rolled plate, and the inner side brazing layer hot-rolled plate to expose fresh metal color and remove the surface oxide layer;

[0131] (6) Composite hot rolling: stacking the above-mentioned outer side brazing layer hot-rolled plate, the pre-embedded brazing flux brazing layer blank plate, the barrier layer hot-rolled plate, the milled core layer ingot, and the inner side brazing layer hot-rolled plate in the above-mentioned order, and then composite hot rolling and coiling to obtain a hot-rolled coil with a thickness of 6 mm;

[0132] (7) Cold rolling: after the hot-rolled coil is cooled to room temperature, it is cold-rolled in multiple passes to a finished thickness of 0.32 mm,

[0133] (8) Annealing: annealing the cold-rolled coil at 240°C for 3 h to obtain a finished product in an incomplete annealing state, thereby obtaining an aluminum alloy composite material for fuel cell radiators.

[0134] The aluminum alloy composite material has a thickness of 0.32 mm, a pre-embedded brazing flux outer side brazing layer composite ratio of 12%, a barrier layer composite ratio of 15%, and an inner side brazing layer composite ratio of 6%; the yield strength R p 0.2 of the composite plate is 182 MPa, the tensile strength R m is 214 MPa, and the elongation A 50 after fracture is 7.2%.

[0135] Comparative Example 4

[0136] The preparation steps and the compositions of each layer are the same as those of Example 3, except that the pre-embedded brazing flux concentration is greater than 2.5%.

[0137] An aluminum alloy composite material for fuel cell radiators is prepared, wherein the core layer has a chemical composition of Si 0.1%, Fe 0.25%, Cu 0.9%, Mn 1.3%, Mg 0.25%, Ti 0.2%, the remainder being Al and unavoidable impurities with a total amount of less than 0.15%. The barrier layer is 3003 aluminum alloy, the inner side brazing layer is 4045 aluminum alloy, the outer side brazing layer is 4343 aluminum alloy, and the pre-embedded brazing flux concentration of the outer side brazing layer is 3.0 g / m 2 .

[0138] (1) According to the element composition of the core alloy, the barrier layer alloy, the outer brazing layer alloy and the inner brazing layer alloy, respectively, the ingredients are prepared, and after melting, electromagnetic stirring, slagging, refining, degassing and semi-continuous casting, the core layer ingot, the barrier layer ingot, the outer brazing layer ingot and the inner brazing layer ingot with a specification of 450mmx1290mmx7000mm are obtained;

[0139] (2) Sawing and milling: the core layer ingot, the barrier layer ingot, the outer brazing layer ingot and the inner brazing layer ingot are sawed and milled according to the specification requirements: the sawing length is 300mm; the core layer and the barrier layer ingot are milled by 15mm; the inner brazing layer ingot and the outer brazing layer ingot are milled by 15mm.

[0140] (3) Heating and hot rolling: the barrier layer, the outer brazing layer and the inner brazing layer ingot treated by sawing and milling are heated at 500±10℃ for 15h, and rolled to the calculated thickness according to the composite ratio: the barrier layer is rolled to 94mm, the outer brazing layer is rolled to 57mm, and the inner brazing layer is rolled to 38mm.

[0141] (4) Preparation of pre-embedded brazing agent brazing layer blank plate: the potassium fluoroaluminate (KAlF4) brazing agent powder and 4343 powder are mixed uniformly and then hot isostatic pressed to obtain a hot isostatic pressed ingot, which is milled and hot rolled to obtain a 4343 pre-embedded brazing agent brazing layer blank plate with a thickness of 18mm;

[0142] (5) Surface mechanical treatment: the surfaces of the barrier layer hot rolled plate, the 4343 pre-embedded brazing agent brazing layer blank plate, the outer brazing layer hot rolled plate and the inner brazing layer hot rolled plate are polished to expose fresh metal color and remove the surface oxide layer;

[0143] (6) Composite hot rolling: the above-mentioned outer brazing layer hot rolled plate, pre-embedded brazing agent brazing layer blank plate, barrier layer hot rolled plate, milled core layer ingot and inner brazing layer hot rolled plate are stacked in the above-mentioned order, and then composite hot rolled and coiled to obtain a hot rolled coil with a thickness of 6mm;

[0144] (7) Cold rolling: the hot rolled coil is cooled to room temperature and then cold rolled in multiple passes to a finished thickness of 0.32mm,

[0145] (8) Annealing: the cold rolled coil is annealed at 240℃ for 3h to obtain a finished product in an incomplete annealing state, thereby obtaining an aluminum alloy composite material for fuel cell heat sinks.

[0146] The thickness of the aluminum alloy composite material is 0.32mm, the composite ratio of the outer brazing layer with pre-embedded brazing agent is 12%, the composite ratio of the barrier layer is 15%, and the composite ratio of the inner brazing layer is 6%; the yield strength R p 0.2 of the composite plate is 182MPa, and the tensile strength R m211 MPa, elongation A after break 50 8.3%.

[0147] Comparative Example 5

[0148] The preparation step and the composition of each layer are the same as those of Example 1, except that the composite ratio of the barrier layer is less than 15%.

[0149] An aluminum alloy composite material for fuel cell radiators is prepared, wherein the chemical composition of the core layer is Si 0.08%, Fe 0.3%, Cu 0.7%, Mn 1.5%, Mg 0.23%, Ti 0.15%, and the balance is Al and unavoidable impurities with a total amount of less than 0.15%. The barrier layer is 3003 aluminum alloy, the inner brazing layer is 4343 aluminum alloy, the outer brazing layer is 4343 aluminum alloy, and the pre-embedded flux concentration of the outer brazing layer is 1.5 g / m 2 .

[0150] (1) The core layer alloy, the barrier layer alloy, the outer brazing layer alloy, and the inner brazing layer alloy are respectively prepared according to the element composition, and after melting, electromagnetic stirring, slagging, refining, degassing, and semi-continuous casting, core layer ingots, barrier layer ingots, and inner and outer brazing layer ingots with a specification of 450 mm x 1290 mm x 7000 mm are obtained;

[0151] (2) Sawing and milling: each ingot is sawed and milled according to the specification requirements: the sawing length is 200 mm; the core layer and the barrier layer ingots are milled by 10 mm; and the inner and outer brazing layer ingots are milled by 12 mm.

[0152] (3) Heating and hot rolling: the barrier layer and the inner and outer brazing layer ingots after sawing and milling are heated at 500±10°C for 13 h, and rolled to the calculated thickness according to the composite ratio: the barrier layer is rolled to 57 mm, the outer brazing layer is rolled to 47 mm, and the inner brazing layer is rolled to 29 mm.

[0153] (4) Pre-embedded flux brazing layer blank preparation: the potassium fluoroaluminate (KAlF4) flux powder and 4343 powder are uniformly mixed and then hot isostatic pressed to obtain a hot isostatic pressed ingot, which is milled and hot rolled to obtain a 4343 pre-embedded flux brazing layer blank with a thickness of 10 mm;

[0154] (5) Surface mechanical treatment: the surfaces of the barrier layer, the 4343 pre-embedded flux brazing layer blank, the outer brazing layer hot rolled plate, and the inner brazing layer hot rolled plate are polished to expose the fresh metal color and remove the surface oxidation layer;

[0155] (6) Hot rolling: the outer brazing layer hot-rolled plate, the pre-embedded brazing flux brazing layer blank plate, the barrier layer hot-rolled plate, the milled core layer ingot and the inner brazing layer hot-rolled plate are stacked in the above order, and are hot-rolled and coiled to obtain a hot-rolled coil with a thickness of 8 mm;

[0156] (7) Cold rolling: the hot-rolled coil is cooled to room temperature and is cold-rolled in multiple passes to a finished thickness of 0.30 mm,

[0157] (8) Annealing: the cold-rolled coil is annealed at 250°C for 3 h to obtain a finished product in an incomplete annealing state, thereby obtaining an aluminum alloy composite material for fuel cell radiators.

[0158] The aluminum alloy composite material has a thickness of 0.3 mm, the outer brazing layer with pre-embedded brazing flux has a composite ratio of 10%, the barrier layer has a composite ratio of 10%, and the inner brazing layer has a composite ratio of 5%; the yield strength R p 0.2 of the composite plate is 189 MPa, the tensile strength R m is 221 MPa, and the elongation A 50 after fracture is 9.0%.

[0159] Comparative Example 6

[0160] The preparation steps and the compositions of the layers are the same as in Example 1, except that the composite ratio of the barrier layer is greater than 25%.

[0161] An aluminum alloy composite material for fuel cell radiators is prepared, wherein the core layer has a chemical composition of Si 0.08%, Fe 0.3%, Cu 0.7%, Mn 1.5%, Mg 0.23%, Ti 0.15%, and the balance being Al and unavoidable impurities with a total amount of less than 0.15%; the barrier layer is 3003 aluminum alloy; the inner brazing layer is 4343 aluminum alloy; the outer brazing layer is 4343 aluminum alloy; and the pre-embedded brazing flux concentration of the outer brazing layer is 1.5 g / m 2 .

[0162] (1) The core layer alloy, the barrier layer alloy, the outer brazing layer alloy and the inner brazing layer alloy are respectively prepared according to the element compositions, and after melting, electromagnetic stirring, slagging, refining, degassing and semi-continuous casting, core layer ingots, barrier layer ingots and inner and outer brazing layer ingots with a specification of 450 mm x 1290 mm x 7000 mm are obtained;

[0163] (2) Sawing and milling: each ingot is sawed and milled according to the specification requirements: the sawing length is 200 mm; the core layer and the barrier layer ingot are milled by 15 mm; and the inner and outer brazing layer ingots are milled by 12 mm.

[0164] (3) Heating and hot rolling: the cast ingot of the barrier layer and the inner and outer brazing layers treated by sawing and milling is heated at 500±10°C for 13h, and rolled to the calculated thickness according to the composite ratio, the barrier layer is rolled to 228mm, the outer brazing layer is rolled to 66mm, and the inner brazing layer is rolled to 38mm.

[0165] (4) Preparation of pre-embedded brazing agent brazing layer blank plate: the KAlF4brazing agent powder and the 4343 powder are uniformly mixed and then hot isostatic pressed to obtain a hot isostatic pressed blank ingot, the hot isostatic pressed blank ingot is milled and hot rolled to obtain a 4343 pre-embedded brazing agent brazing layer blank plate with a thickness of 10mm;

[0166] (5) Surface mechanical treatment: the surfaces of the barrier layer, the 4343 pre-embedded brazing agent brazing layer blank plate, the outer brazing layer hot rolled plate and the inner brazing layer hot rolled plate are polished to expose the fresh metal color and remove the surface oxide layer;

[0167] (6) Composite hot rolling: the above-mentioned outer brazing layer hot rolled plate, pre-embedded brazing agent brazing layer blank plate, barrier layer hot rolled plate, core layer cast ingot after milling and inner brazing layer hot rolled plate are stacked in the above-mentioned order, and composite hot rolling and coiling are performed to obtain a hot rolled coil with a thickness of 8mm;

[0168] (7) Cold rolling: the hot rolled coil is cooled to room temperature and then cold rolled in multiple passes to a finished product thickness of 0.30mm,

[0169] (8) Annealing: the cold rolled coil is annealed at 250°C for 3h to obtain a finished product in an incomplete annealing state, thereby obtaining an aluminum alloy composite material for fuel cell radiators.

[0170] The aluminum alloy composite material has a thickness of 0.3mm, the outer brazing layer of the pre-embedded brazing agent has a composite ratio of 10%, the barrier layer has a composite ratio of 30%, and the inner brazing layer has a composite ratio of 5%; the yield strength R p 0.2 of the composite plate is 155MPa, the tensile strength R m is 185MPa, and the elongation A 50 after fracture is 9.3%.

[0171] Comparative Example 7

[0172] An aluminum alloy composite material for fuel cell radiators of the present application is prepared, wherein the core layer has a chemical composition of Si 0.08%, Fe 0.3%, Cu 0.7%, Mn 1.5%, Mg 0.45%, Ti 0.15%, and the balance of Al and unavoidable impurities with a total amount of less than 0.15%. The inner brazing layer is 4343 aluminum alloy, and the outer brazing layer is 4343 aluminum alloy. The pre-embedded brazing agent concentration of the outer brazing layer is 1.5g / m 2 .

[0173] (1) According to the element composition of the core alloy, the outer brazing layer alloy and the inner brazing layer alloy, ingredients are prepared respectively, and then the core ingot and the inner and outer brazing layer ingots with a specification of 450mmx1290mmx7000mm are obtained after melting, electromagnetic stirring, skimming, refining, degassing and semi-continuous casting;

[0174] (2) Sawing and milling: each ingot is sawed and milled according to the specification requirements: the sawing length is 200mm; the core ingot is milled by 10mm; the inner and outer brazing layer ingots are milled by 12mm.

[0175] (3) Heating and hot rolling: the inner and outer brazing layer ingots treated by sawing and milling are heated at 500±10℃ for 13h, and then rolled to the calculated thickness according to the composite ratio, the outer brazing layer is rolled to 40mm, and the inner brazing layer is rolled to 25mm.

[0176] (4) Preparation of pre-embedded brazing agent brazing layer blank plate: the KAlF4 brazing agent powder and 4343 powder are uniformly mixed and then hot isostatic pressed to obtain a hot isostatic pressed blank ingot, the hot isostatic pressed blank ingot is milled and hot rolled to obtain a 4343 pre-embedded brazing agent brazing layer blank plate with a thickness of 10mm;

[0177] (5) Surface mechanical treatment: the surface of the 4343 pre-embedded brazing agent brazing layer blank plate, the outer brazing layer hot rolled plate and the inner brazing layer hot rolled plate is polished to expose the fresh metal color and remove the surface oxide layer;

[0178] (6) Composite hot rolling: the above-mentioned outer brazing layer hot rolled plate, pre-embedded brazing agent brazing layer blank plate, milled core ingot and inner brazing layer hot rolled plate are stacked in the above-mentioned order, and then composite hot rolled and coiled to obtain a hot rolled coil with a thickness of 8mm;

[0179] (7) Cold rolling: the hot rolled coil is cooled to room temperature and then cold rolled by multiple passes to a finished thickness of 0.30mm,

[0180] (8) Annealing: the cold rolled coil is annealed at 250℃ for 3h to obtain a finished product in an incomplete annealing state, thereby obtaining an aluminum alloy composite material for fuel cell radiators.

[0181] The thickness of the aluminum alloy composite material is 0.3mm, the composite ratio of the outer brazing layer with pre-embedded brazing agent is 10%, and the composite ratio of the inner brazing layer is 5%; the yield strength R p 0.2 of the composite plate is 204MPa, the tensile strength R m is 236MPa, and the elongation A 50 after fracture is 8.1%.

[0182] Comparative Example 8

[0183] The fuel cell radiator aluminum alloy composite material of the present application is prepared, wherein the core layer has a chemical composition of Si 0.08%, Fe 0.3%, Cu 1.1%, Mn 2.2%, Mg 0.23%, Ti 0.15%, and the balance of Al and unavoidable impurities less than 0.15% in total. The inner brazing layer is 4343 aluminum alloy, and the outer brazing layer is 4343 aluminum alloy. The outer brazing layer has a pre-embedded brazing flux concentration of 1.5 g / m 2 .

[0184] (1) The core layer alloy, the outer brazing layer alloy and the inner brazing layer alloy are respectively prepared by batching, melting, electromagnetic stirring, skimming, refining, degassing and semi-continuous casting to obtain core layer ingots and inner and outer brazing layer ingots with a specification of 450 mm x 1290 mm x 7000 mm;

[0185] (2) Sawing and milling: each ingot is sawed and milled according to the specification requirements: the sawing length is 200 mm; the core layer ingot is milled by 10 mm; and the inner and outer brazing layer ingots are milled by 12 mm.

[0186] (3) Heating and hot rolling: the inner and outer brazing layer ingots treated by sawing and milling are heated at 500±10°C for 13 h, and rolled to the calculated thickness according to the composite ratio, the outer brazing layer is rolled to 40 mm, and the inner brazing layer is rolled to 25 mm.

[0187] (4) Pre-embedded brazing flux brazing layer blank plate preparation: the potassium fluoroaluminate (KAlF4) flux powder and 4343 powder are uniformly mixed and then hot isostatic pressed to obtain a hot isostatic pressed ingot, which is milled and hot rolled to obtain a 4343 pre-embedded brazing flux brazing layer blank plate with a thickness of 10 mm;

[0188] (5) Surface mechanical treatment: the surface of the 4343 pre-embedded brazing flux brazing layer blank plate, the outer brazing layer hot rolled plate and the inner brazing layer hot rolled plate is polished to expose the fresh metal color and remove the surface oxide layer;

[0189] (6) Composite hot rolling: the above-mentioned outer brazing layer hot rolled plate, pre-embedded brazing flux brazing layer blank plate, milled core layer ingot and inner brazing layer hot rolled plate are stacked in the above-mentioned order, and then composite hot rolled and coiled to obtain a hot rolled coil with a thickness of 8 mm;

[0190] (7) Cold rolling: the hot rolled coil is cooled to room temperature and then cold rolled in multiple passes to a finished thickness of 0.30 mm,

[0191] (8) Annealing: the cold rolled coil is annealed at 250°C for 3 h to obtain a finished product in an incomplete annealing state, thereby obtaining the fuel cell radiator aluminum alloy composite material.

[0192] The thickness of the aluminum alloy composite material is 0.3 mm, the composite ratio of the outer brazing layer with the pre-embedded brazing agent is 10%, and the composite ratio of the inner brazing layer is 5%; the yield strength R p 0.2 is 224 MPa, the tensile strength R m is 252 MPa, and the elongation A 50 after fracture is 4.3%.

[0193] Experimental example

[0194] The performance of the composite material of the above examples and comparative examples is detected. Among them, Figure 3 is the metallographic picture of the pipe material joint weld section after brazing of the example embodiment of the present application. Figure 4 is the metallographic picture of the pipe material and fin connection weld after brazing of the example embodiment of the present application. Figure 5 is the metallographic picture of the pipe material and fin connection weld after brazing of the example comparative example 1 of the present application. Figure 6 is the metallographic picture of the pipe material and fin connection weld after brazing of the example comparative example 3 of the present application.

[0195] According to Figure 3 and Figure 5 , Figure 4 and Figure 6 , it can be seen that the barrier layer design of the present application is necessary and the thickness ratio design of the barrier layer is reasonable, and the pre-embedded brazing agent concentration is moderate, which ensures the brazability and good brazing quality, and takes into account the process difficulty and manufacturing cost. The alloy composition of the core material is reasonably designed, has the characteristics of high strength and good formability, and by adding a reasonable amount of Mg element to the core material, the inner side of the pipe material is brazed without brazing agent, eliminating the influence of the brazing agent on the electrical conductivity of the cooling liquid in the pipe.

[0196] Figure 7 is the Mg diffusion scanning electron microscope analysis of the outer surface of the pipe material after brazing of the example comparative example 5 of the present application. It can be seen that in the comparative example 5, because the composite ratio of the barrier layer is less than 15%, the Mg element cannot be completely blocked during brazing, the Mg element diffuses to the brazing layer and reacts with the brazing agent, which destroys the activity of the brazing agent, resulting in high virtual welding rate and poor brazing quality.

[0197] The pipe making and brazing results of the comparative examples are shown in Table 1:

[0198] Table 1 Pipe making and brazing of composite materials of each comparative example and example

[0199]

[0200] The above description of the embodiments is only used to help understand the method and its core idea of the application. It should be pointed out that, for those skilled in the art, some improvements and modifications can be made to the application without departing from the principles of the application, and these improvements and modifications also fall within the protection scope of the claims of the application.

Claims

1. An aluminum alloy composite material for fuel cell radiators, characterized by comprising an aluminum alloy substrate and a coating layer formed on the surface of the substrate, wherein the coating layer is formed of a material containing at least one of Si, Mg, and Zr. The application relates to a fuel cell radiator aluminum alloy composite material, which comprises an outer brazing layer, a barrier layer, a core layer and an inner brazing layer. The core layer is composed of Si<=0.4%, Fe 0.2-0.4%, Cu 0.25-0.9%, Mn 1.2-1.9%, Mg 0.15-0.3%, Ti 0.08-0.25%, the rest being Al and unavoidable impurities with a total amount less than 0.15%. The barrier layer is composed of 3003 alloy. The outer brazing layer is 4045 or 4343 alloy and is pre-embedded with brazing agent. The composite ratio of the outer brazing layer is 8-12%, the composite ratio of the inner brazing layer is 3.5-6.5%, and the composite ratio of the barrier layer is 15-25%. The barrier layer is 3003 alloy. The concentration of the brazing flux pre-embedded in the outer brazing layer is 1.0-2.5 g / m 2 .

2. The composite material of claim 1, wherein, The core layer is 3003MOD alloy containing Mg.

3. The composite material of claim 1, wherein, The thickness of the fuel cell radiator aluminum alloy composite material is 0.24-0.35mm.

4. The composite material according to any one of claims 1 to 3, characterized in that, The application also relates to a manufacturing method of the fuel cell radiator aluminum alloy composite material.

5. A method of producing the aluminum alloy composite material for fuel cell radiators as claimed in any one of claims 1 to 4, characterized by, The core layer ingot, the barrier layer ingot, the outer brazing layer ingot and the inner brazing layer ingot are respectively subjected to head-tail sawing and face milling. The barrier layer ingot, the outer brazing layer ingot and the inner brazing layer ingot are respectively subjected to hot rolling according to the composite ratio. The pre-embedded brazing agent blank plate of the outer brazing layer is prepared. The outer brazing layer, the pre-embedded brazing agent blank plate, the barrier layer, the core layer and the inner brazing layer are respectively subjected to surface mechanical treatment. The outer brazing layer, the pre-embedded brazing agent blank plate, the barrier layer, the core layer and the inner brazing layer are stacked in sequence and subjected to composite hot rolling to obtain a hot-rolled coil. The hot-rolled coil is cooled to room temperature and subjected to cold rolling to obtain a cold-rolled coil. The cold-rolled coil is subjected to annealing. The pre-embedded brazing agent blank plate of the outer brazing layer comprises the following steps: The brazing agent powder and the outer brazing layer powder are uniformly mixed and subjected to hot isostatic pressing to obtain a hot isostatic pressing ingot.

6. The production method according to claim 5, wherein The hot isostatic pressing ingot is subjected to milling and hot rolling. The hot rolling temperature of the hot rolling of the barrier layer ingot, the outer brazing layer ingot and the inner brazing layer ingot is 500+ / -10 DEG C, and the holding time is 12-24h. The temperature of the composite hot rolling is 500+ / -10 DEG C, and the holding time is 12-24h.

7. The preparation method according to claim 5, characterized in that, The annealing temperature is 230-270 DEG C, and the holding time is 2-3h.

8. The production method according to claim 7, characterized by, ​ 9. The production method according to claim 8, characterized by, ​

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