Aluminum-based brazing composite material and preparation method thereof

Abstract

The invention relates to an aluminum-based brazing composite material and a preparation method thereof. The method comprises the following steps: firstly depositing a metal oxide layer on the surface of a filler alloy layer of a composite aluminum plate by an ion beam vapor deposition method under vacuum conditions, and then continuing to deposit metal by an ion beam vapor deposition method under vacuum conditions to form a nickel metal outer layer; the prepared aluminum-based brazing composite material comprises a core layer and a brazing composite layer; the brazing composite layer comprises a nickel metal outer layer, a metal oxide layer and a filler alloy layer; the metal oxide layer is located between the filler alloy layer and the nickel metal outer layer; the filler alloy layer in the brazing composite layer is located on a side facing the core layer; the metal oxide layer is a layer structure made of metal oxide, and the metal oxide layer contains more than 30wt% of nickel oxide; the bonding strength between the nickel metal outer layer and the filler alloy layer reaches level 3 or above, and the weld length of the aluminum-based brazing composite material when brazing is performed by using a T-shaped pattern mold is greater than or equal to 30mm.

Description

Technical Field

[0001] The invention belongs to the technical field of aluminum brazing, and relates to an aluminum-based brazing composite material and a preparation method thereof. Background Art

[0002] Aluminum brazing uses aluminum and aluminum alloys with lower melting points than the parent metal as filler metal. Upon heating, the filler metal melts, while the weldment remains intact. The liquid aluminum filler metal wets the parent metal, filling gaps in the joint and interdiffusing with the parent metal, creating a tight and secure connection. Over 40 years have passed since aluminum heat exchangers began replacing all-copper heat exchangers in the 1970s. In particular, the development of the non-corrosive NOCOLOK brazing flux by Alcan in 1978 sparked a shift in automotive heat exchangers from traditional brazing methods like vacuum brazing to controlled atmosphere brazing (CAB), and this flux remains widely used today.

[0003] Currently, the brazing methods used by automotive heat exchanger manufacturers both domestically and internationally are primarily categorized as VB and CAB. VB brazing relies on the evaporation of magnesium from the brazing filler metal to break down the oxide film on the aluminum surface. Furthermore, the degassing effect of magnesium prevents oxidation during heating and promotes wettability of the molten brazing filler metal. The advantages of vacuum brazing (also known as VB brazing) are: ① It requires no flux, produces no harmful gases during heating, and requires no post-weld cleaning, resulting in no environmental pollution; ② it eliminates corrosion issues caused by flux residue and salts, resulting in a longer product lifespan; and ③ it produces a bright, aesthetically pleasing finish. However, it also has disadvantages, primarily high equipment cost, low efficiency, and complex maintenance. Regular removal of Mg vapors adhering to the furnace walls can compromise the furnace's vacuum level and heating efficiency. CAB brazing has become a predominant method for heat exchanger production. It uses an inert gas (primarily nitrogen) as a protective atmosphere and a fluoride-based, non-corrosive material as a brazing flux. The advantages of CAB welding are: ① low equipment cost and easy maintenance; ② wide joint clearances are permitted; ③ the flux adhered to the surface of the brazed parts is non-corrosive and non-hygroscopic, eliminating the need for cleaning, simplifying the process and reducing costs. However, there are some disadvantages: ① flux is insoluble in water, making flux application complex. Special heat exchangers still require manual secondary flux application and subsequent drying of the fluxed product; ② fluoride flux reacts with magnesium, placing strict requirements on the Mg content of the base metal or brazing filler metal, generally below 0.5 wt%, limiting its application to Mg-containing aluminum alloys such as 5xxx and 6xxx series; ③ the high operating temperature of the flux (above 570°C) prevents overburning of more than 50% of aluminum alloys from using this method; ④ the use of flux increases costs, reduces production efficiency, and worsens the working environment; ⑤ flux residue affects surface quality and may cause localized channel blockage, reducing heat transfer efficiency. In view of the disadvantages of the above two brazing methods, people are prompted to develop heat transfer brazing aluminum materials that do not require the application of flux and can be brazed in ordinary CAB brazing furnaces.

[0004] U.S. Patent No. 4,028,200 discloses a method for brazing aluminum components, wherein brazing occurs between two aluminum components or between an aluminum component and another metal component. The aluminum or aluminum alloy has a braze cladding layer that is electroplated with an alloy that promotes adhesion prior to brazing. Alternatively, the aluminum brazing cladding layer is replaced with an aluminum brazing foil coated with a braze-promoting alloy. The braze-promoting alloy includes nickel or cobalt, with a small amount of lead added, allowing nickel-lead or cobalt-lead to be used alone or in combination. The addition of lead improves the wettability of the composite alloy during the brazing cycle. However, it is conceivable that components using lead-containing braze-promoting layer materials face environmental issues during production and use.

[0005] A known technique discloses a brazing sheet product comprising a core material and a brazing filler material. The filler material comprises an aluminum cladding layer of an Al-Si alloy and a nickel layer thereon, the nickel layer being electroplated onto the surface of the aluminum cladding. The addition of at least one of Bi, Pb, Li, and Sb to the aluminum cladding improves wettability during brazing, while maintaining good brazing properties in the brazed product and its components without requiring the addition of lead to the nickel-containing layer. Electroplating to coat the surface of brazed aluminum with a brazing-promoting layer is believed to have certain drawbacks, such as low electroplating production rates and the need for wastewater treatment of nickel salts in the electroplating solution, which poses certain environmental concerns.

[0006] A known method for manufacturing a brazed product includes applying a metal layer that allows for fluxless brazing to the surface of the brazed product, the brazed product comprising an aluminum alloy core and a clad brazing layer on the aluminum alloy core, the surface being clad with the brazing alloy, and pre-treating the surface prior to the application step. The metal layer comprises a material selected from nickel, a nickel alloy, iron, an iron alloy, titanium, a titanium alloy, cobalt, and a cobalt alloy, and the metal coating is applied by physical vapor deposition or chemical vapor deposition, and the metal coating is applied to the clad brazing layer without an adhesive layer. Vapor deposition offers two advantages over conventional electroplating methods: first, it avoids wastewater treatment, and second, it allows for a thinner nickel layer. However, this method shares the same problem as conventional electroplating: without the addition of wettability-enhancing elements such as lead and bismuth, the nickel metal exhibits poor adhesion to the aluminum alloy, significantly reducing brazing performance.

[0007] Therefore, it is of great significance to design an aluminum-based brazing composite material containing a nickel metal layer that does not require the addition of additional alloying elements such as Pb to improve wettability and can also ensure the brazing performance of the nickel-plated aluminum brazing composite material, has a simple preparation process, is suitable for existing plating technology, and has good environmental protection effects. Summary of the Invention

[0008] In order to solve the problems existing in the prior art, one of the objects of the present invention is to provide an aluminum-based brazing composite material, comprising a core layer and a brazing composite layer; the brazing composite layer comprises a nickel metal outer layer, a metal oxide layer and a filler alloy layer, and the metal oxide layer is located between the filler alloy layer and the nickel metal outer layer, thereby improving the adhesion between the filler alloy layer and the nickel metal outer layer; a second object of the present invention is to provide a method for preparing an aluminum-based brazing composite material, comprising first depositing a metal oxide layer on the surface of the filler alloy layer of a composite aluminum plate by an ion beam vapor deposition method, and then continuing to deposit metal to form a nickel metal outer layer.

[0009] To achieve the above object, the present invention adopts the following scheme:

[0010] An aluminum-based brazing composite material comprises a core layer and a brazing composite layer; the brazing composite layer comprises a nickel metal outer layer, a metal oxide layer and a filler alloy layer;

[0011] The metal oxide layer is located between the filler alloy layer and the nickel metal outer layer; the filler alloy layer is located on a side of the brazing composite layer facing the core layer.

[0012] The metal oxide layer is a layer structure made of metal oxide, specifically: the metal oxide layer is a nickel oxide layer, a nickel iron oxide layer (a mixture layer of nickel oxide and iron oxide), a nickel cobalt oxide layer (a mixture layer of nickel oxide and cobalt oxide) or a nickel iron cobalt oxide layer (a mixture layer of nickel oxide, iron oxide and cobalt oxide).

[0013] As the preferred technical solution:

[0014] As described above, the aluminum-based brazing composite material contains more than 30wt% of nickel oxide in the metal oxide layer (which can also be expressed as: the metal oxide layer is a nickel oxide layer, a nickel-iron oxide layer (a mixture layer of nickel oxide and iron oxide with a nickel oxide content of more than 30wt%), a nickel-cobalt oxide layer (a mixture layer of nickel oxide and cobalt oxide with a nickel oxide content of more than 30wt%), or a nickel-iron-cobalt oxide layer (a mixture layer of nickel oxide, iron oxide and cobalt oxide with a nickel oxide content of more than 30wt%)); the nickel content in the nickel metal outer layer is ≥99wt%.

[0015] Experimental comparisons have revealed that introducing a layered structure containing a metal oxide layer containing nickel oxide between the nickel metal outer layer and the filler alloy layer can improve the adhesion between the nickel metal outer layer and the filler alloy layer surface. This adhesion is beneficial for improving the brazing performance of aluminum-based brazing composite materials. When the nickel oxide content in the metal oxide layer reaches 30 wt% or more, the adhesion between the filler alloy layer and the nickel metal outer layer can be significantly improved. Too little nickel oxide does not achieve the desired effect, and therefore, nickel oxide is considered to be an effective substance for achieving improved adhesion. Since nickel is relatively expensive, when the nickel oxide content is sufficient, oxides such as iron oxide can also be used to reduce costs. The preferred metal oxide layer is a nickel oxide layer.

[0016] The aluminum-based brazing composite material as described above, wherein the core layer is a 3xxx series aluminum alloy containing Mn as a main alloying element or a 6xxx series aluminum alloy containing Mg and Si as main elements;

[0017] The filler alloy layer is a 4xxx series aluminum-silicon alloy.

[0018] As for the aluminum-based brazing composite material as described above, one side or both sides of the core layer in the aluminum-based brazing composite material are the brazing composite layers.

[0019] As described above, the aluminum-based brazing composite material has a total thickness of ≤6 mm, which can be 0.04-6.0 mm, and more preferably 0.2-0.8 mm; in the aluminum-based brazing composite material, the thickness of each filler alloy layer is 2-30% (preferably 5-20%) of the total thickness of the aluminum-based brazing composite material; the composite ratio of the filler alloy layer (that is, the percentage of its thickness to the total thickness) should not be too small, otherwise there will not be enough brazing material, and the weldment cannot be wetted during the brazing process; the composite ratio of the filler alloy layer should not be too large, otherwise it will cause the overall composite material to be too thick and the cost will increase.

[0020] In the aluminum-based brazing composite material as described above, the thickness of the nickel metal outer layer in each brazing composite layer is 5 to 1000 nm (preferably 20 to 50 nm), and the thickness deviation is ≤ 10%. A nickel metal outer layer that is too thick will increase the cost, while a nickel metal outer layer that is too thin will result in poor brazing effect.

[0021] The thickness of the metal oxide layer in each brazing composite layer is 3 to 20 nm (preferably 10 to 20 nm), and the thickness deviation is ≤ 10%. A metal oxide layer with too high a thickness will become an obstacle to the melting and wetting of the solder during brazing, while a metal oxide layer with too low a thickness will be difficult to achieve in processing.

[0022] In the aluminum-based brazing composite material as described above, the bonding strength between the nickel metal outer layer and the filler alloy layer is level 3 or above; the weld length of the aluminum-based brazing composite material when brazing using a T-type pattern is ≥30 mm (under the same conditions, the longer the weld, the better the brazing performance).

[0023] The present invention also provides a method for preparing the aluminum-based brazing composite material as described above, wherein a metal oxide layer is first deposited on the surface of the filler alloy layer of the composite aluminum plate by ion beam vapor deposition, and then a metal is continuously deposited by ion beam vapor deposition to form a nickel metal outer layer;

[0024] The ion beam vapor deposition method is performed under vacuum conditions.

[0025] In some existing studies, chemical nickel plating is often used to coat a nickel layer (equivalent to the nickel metal outer layer in the present invention) on the surface of the brazing material to improve the brazing performance of aluminum brazing composite materials. The thickness of the nickel layer obtained by this method is generally 1 to 2 μm. In order to reduce costs (nickel metal is relatively expensive), some products also use chemical plating to coat nano-scale nickel layers. When this type of coating is prepared to a size below 100 nm, the thickness deviation is often large.

[0026] To achieve a nickel metal layer of nanometer thickness, such as a nickel layer of 5 to 500 nm or 20 to 200 nm, conventional vapor deposition, arc evaporation, magnetron sputtering and other methods can obtain a metal oxide layer of uniform thickness compared to chemical plating.

[0027] By attaching a thin oxide film between the metal layer and the filler alloy, the adhesion between the metal layer and the aluminum alloy surface can be improved. This adhesion is beneficial to improving the brazing performance of the aluminum-based brazing composite material. It was found that the bonding effect is best when a nickel metal layer of uniform thickness is deposited on a metal oxide layer of uniform thickness. In particular, when the oxide film is deposited by vapor deposition, it has a better effect than arc evaporation and magnetron sputtering methods. This is because the oxide film is a high-energy, non-stable oxide layer formed under vacuum conditions. This oxide layer is easily transformed into a low-energy state when heated, especially at the brazing temperature (about 600°C). Atomic migration occurs from the oxide film atoms to the outermost nickel metal layer and the filler alloy layer, thereby improving the interfacial bonding strength between the nickel metal outer layer and the filler alloy layer.

[0028] The process of the composite aluminum plate adopts conventional process methods. For example, an optional method is to use traditional semi-continuous casting or continuous casting or continuous casting and rolling to respectively prepare the core layer and the filler alloy layer, and the core layer and the filler alloy layer are stacked in sequence according to the thickness of the composite ratio and then bonded and rolled, and then subjected to hot rolling, cold rolling, annealing and other processes to obtain a composite aluminum plate with target specifications and performance; another optional method is to use a composite casting method to obtain a composite ingot of the filler alloy layer and the core layer with a target composite ratio; and the composite ingot is then subjected to hot rolling, cold rolling, annealing and other processes to obtain a composite aluminum plate with target specifications and performance.

[0029] As the preferred technical solution:

[0030] In the above-mentioned method for preparing an aluminum-based brazing composite material, before depositing the metal oxide layer, the surface of the filler alloy layer of the composite aluminum plate is pretreated by ion etching, magnetron sputtering etching or glow discharge etching.

[0031] Pre-treating the surface of the filler alloy layer of the composite aluminum plate can not only effectively remove the aluminum oxide layer that affects the brazing effect, but also remove the surface oil residue and foreign particles, and help deposit a metal oxide layer or metal layer on the surface of the filler alloy layer of the composite aluminum plate. The formation of a nickel metal layer on the surface of the filler alloy layer can achieve flux-free brazing.

[0032] In the method for preparing an aluminum-based brazing composite material as described above, the process parameters for depositing the metal oxide layer are: ion beam application time of 3 to 30 minutes (preferably 5 to 10 minutes), beam current not exceeding 80 μA (preferably 50 to 60 μA), and voltage of 3 to 8 kV (preferably 5 to 7 kV);

[0033] The process parameters for depositing metal to form a nickel metal outer layer are: ion beam application time 8 to 1500 min (preferably 30 to 300 min), beam current not exceeding 80 μA (preferably 50 to 70 μA), and voltage 3 to 10 kV (preferably 6 to 8 kV).

[0034] The metal oxide layer is a metal oxide layer with a nanometer thickness and contains high-energy unstable nickel oxide.

[0035] The principle of the present invention is:

[0036] The present invention can improve the adhesion between the nickel metal outer layer and the filler alloy layer by attaching a thin metal oxide layer containing nickel oxide between the nickel metal outer layer and the filler alloy layer. This adhesion is beneficial to improving the brazing performance of the aluminum-based brazing composite material.

[0037] In particular, when the metal oxide layer is deposited by vapor deposition, the effect is better than that of arc evaporation and magnetron sputtering. This is because the layer is a high-energy non-stable oxide layer formed under vacuum conditions. When heated, especially at a brazing temperature of 600°C, the oxide layer is easily transformed into a low-energy state, and the metal oxide atoms migrate to the outermost nickel metal outer layer and the filler alloy layer, further improving the interfacial bonding strength between the nickel metal outer layer and the filler alloy layer. By introducing a metal oxide layer (i.e., a layer of nickel oxide, or one or two oxide film layers of nickel oxide and cobalt oxide or iron oxide) on the surface of the filler alloy layer by ion beam vapor deposition, and then using ion beam vapor deposition to deposit a nickel metal outer layer on the surface of the metal oxide layer, the brazing performance of the material is significantly improved. The introduction of a metal oxide layer containing nickel oxide was found to effectively improve adhesion, and this improvement in adhesion was found to help improve the wettability of the solder in subsequent brazing experiments. Therefore, the technical solution of this invention can ensure the brazing performance of the nickel-plated aluminum brazing composite material without the need to add additional alloying elements such as Pb to improve wettability.

[0038] Beneficial effects

[0039] (1) An aluminum-based brazing composite material of the present invention, wherein the bonding strength between the nickel metal outer layer and the filler alloy layer is level 3 or above; and the weld length of the aluminum-based brazing composite material when brazing using a T-shaped pattern is ≥30 mm;

[0040] (2) The method for preparing an aluminum-based brazing composite material of the present invention can ensure that the deposited nickel metal outer layer and the metal oxide layer can be controlled within precise dimensional deviations. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 Schematic diagram of the T-type brazing specimen model;

[0042] Figure 2 This is a transmission electron microscope image of the aluminum-based brazing composite material prepared in Example 1;

[0043] Figure 3 This is a metallographic image of the weld cross section of the T-type specimen in Example 1;

[0044] Figure 4 Schematic diagram of the aluminum-based brazing composite material prepared in Example 1;

[0045] Figure 5 Schematic diagram of the aluminum-based brazing composite material prepared in Example 4;

[0046] Figure 6 Schematic diagram of the aluminum-based brazing composite material prepared in Example 5;

[0047] Figure 7 Schematic diagram of the aluminum-based brazing composite material prepared in Example 2;

[0048] Among them, 1-nickel metal outer layer, 2-metal oxide layer, 3-filler alloy layer, 4-core layer, 5-brazed composite layer, 6-intermediate layer, 7-anti-corrosion layer, 8-gasket I, 9-weld, 10-test product, 11-pad, 12-gasket II. DETAILED DESCRIPTION

[0049] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope limited by the appended claims of the application.

[0050] The testing method adopted in the present invention is as follows:

[0051] 1. The present invention rates the bonding strength between the nickel metal outer layer and the filler alloy layer according to the method of GB / T 9286-1998 "Paints and varnishes - Cross-cut test for paint films". The results are divided into 5 levels. The higher the level, the weaker the bonding strength between the film layer and the substrate.

[0052] 2. Use T-type sample model to evaluate the brazing performance of the material. The schematic diagram of T-type sample model is as follows Figure 1 As shown, according to Figure 1The aluminum-based brazing composite material was cut into 25mm×60mm specimens and placed flat on a test bench. A 25mm×60mm AA3003 alloy sheet was placed vertically on the aluminum-based brazing composite sheet, with the nickel metal outer layer facing upward. Together with the AA3003 alloy, the sheet was assembled into a T-shaped specimen. The gasket I8 was 50mm long (L1) and 1mm thick; the test piece 10 was 0.8mm thick; the backing rod 11 was 1mm in diameter; and the gasket II 12 was 60mm long (L2), 25mm wide (L3), and 2mm thick. The T-shaped specimen was placed in a 100mm-diameter quartz tube furnace under nitrogen for simulated brazing. The simulated brazing process involved heating to 600°C at a rate of 30°C / min, holding for 3 minutes, then removing the specimen and air-cooling it to room temperature to produce the simulated brazed sheet. The weld seam length of the T-shaped specimens was measured after brazing. The longer the weld length and the larger the cross-sectional area of the weld, the better the fluidity of the molten filler metal and the better the brazing performance of the material.

[0053] 3. Use transmission electron microscopy to measure the thickness and thickness deviation of the nickel metal outer layer and the metal oxide layer. Select two fields of view to measure the thickness of the nickel metal outer layer and the metal oxide layer. Randomly select five different positions in each field of view for thickness measurement. Obtain 10 sets of thickness values di for each nickel metal outer layer and metal oxide layer, and calculate the average value of the 10 sets of thickness values. That is, the thickness of the nickel metal outer layer and the thickness of the metal oxide layer. The thickness deviation is the percentage of the maximum difference between the 10 sets of thickness values and the average value as a percentage of the average value. The formula is: The thickness deviation indicates the uniformity of the thickness. The smaller the deviation, the better the thickness uniformity.

[0054] Example 1

[0055] A method for preparing an aluminum-based brazing composite material, comprising the following specific steps:

[0056] (1) A composite casting method is used to obtain a composite ingot of a filler alloy layer and a core layer with a target composite ratio; the composite ingot is then subjected to hot rolling, cold rolling, and annealing processes to obtain a composite aluminum plate with target specifications and performance;

[0057] Among them, the core layer is AA3003 aluminum alloy with Mn as the main alloying element;

[0058] The filler alloy layer is AA4045 aluminum alloy with Si as the main alloying element;

[0059] (2) pre-treating the filler alloy layer of the composite aluminum plate obtained in step (1) by ion etching to remove the aluminum oxide layer that affects the brazing effect, and at the same time remove the surface oil residue and foreign particles;

[0060] (3) At a pressure of 5×10－5 Under vacuum conditions of 1.5 Pa, a metal oxide layer composed of a mixture of 70 wt% nickel oxide and 30 wt% iron oxide is deposited on the surface of the filler alloy layer of the pretreated composite aluminum plate by ion beam vapor deposition; the thickness of the metal oxide layer is 3 nm, and the thickness deviation is 10%;

[0061] The process parameters for depositing the metal oxide layer by ion beam vapor deposition were: ion beam application time 5 min, beam current 50 μA, voltage 5 kV;

[0062] (4) At a pressure of 5×10 －5 Under a vacuum condition of 1.5 Pa, metal is further deposited on the surface of the metal oxide layer obtained in step (3) by ion beam vapor deposition to form a nickel metal outer layer with a thickness of 200 nm and a thickness deviation of 0.50%, thereby obtaining an aluminum-based brazing composite material; the nickel content in the nickel metal outer layer is 99 wt%;

[0063] The process parameters for depositing metal to form a nickel metal outer layer by ion beam vapor deposition are: ion beam application time 30 min, beam current 50 μA, and voltage 6 kV.

[0064] like Figure 2 and Figure 4 As shown, the aluminum-based brazing composite material with a total thickness of 0.8 mm includes a core layer 4 and a brazing composite layer 5; the brazing composite layer 5 includes a nickel metal outer layer 1, a metal oxide layer 2 and a filler alloy layer 3 (the thickness of which is 20% of the total thickness of the aluminum-based brazing composite material); the bonding strength between the nickel metal outer layer 1 and the filler alloy layer 3 is level 2; Figure 3 As shown, the weld length of the aluminum-based brazing composite material is 35 mm when brazing using a T-type pattern.

[0065] Comparative Example 1

[0066] A method for preparing an aluminum-based brazing composite material is basically the same as that of Example 1, except that the treatment in step (3) is not performed, and metal is directly deposited on the surface of the filler alloy layer of the pretreated composite aluminum plate by ion beam vapor deposition to form a nickel metal outer layer, thereby preparing an aluminum-based brazing composite material.

[0067] The aluminum-based brazing composite material has a bonding strength of a nickel metal outer layer and a filler alloy layer of level 4; and the length of a weld seam of the aluminum-based brazing composite material when brazing is performed using a T-shaped model is 22 mm.

[0068] Compared with Example 1, the bonding strength and weld length of Comparative Example 1 are smaller than those of Example 1. This is because when the metal oxide layer containing the nickel oxide layer is not provided, excellent bonding strength cannot be obtained, which further affects the brazing effect.

[0069] Comparative Example 2

[0070] A method for preparing an aluminum-based brazing composite material is basically the same as that of Example 1, except that in step (3), a metal oxide layer made of a mixture of 20 wt% nickel oxide and 80 wt% iron oxide is deposited.

[0071] The bonding strength between the nickel metal outer layer and the filler alloy layer of the prepared aluminum-based brazing composite material is level 4; the weld length of the aluminum-based brazing composite material when brazing is performed using a T-type model is 25 mm.

[0072] Compared with Example 1, the bonding strength and weld length of Comparative Example 2 are smaller than those of Example 1. This is because when the nickel oxide content in the metal oxide layer is less than 30wt%, the effect of improving the bonding strength between the nickel metal outer layer and the filler alloy layer is not prominent, and the increase in weld length is not significant.

[0073] Comparative Example 3

[0074] A method for preparing an aluminum-based brazing composite material is basically the same as that in Example 1, except that in step (4), ion beam vapor deposition is used to further deposit metal on the surface of the metal oxide layer to form a pure iron metal outer layer (iron content is 99wt%).

[0075] The bonding strength between the pure iron metal outer layer and the filler alloy layer of the prepared aluminum-based brazing composite material is level 3; the weld length of the aluminum-based brazing composite material when brazing is performed using a T-type model is 21 mm.

[0076] Compared with Example 1, the bonding strength and weld length of Comparative Example 3 are smaller than those of Example 1. This is because changing the metal outer layer to pure iron cannot achieve the same effect as pure nickel, and the use of pure nickel for the outer layer is irreplaceable.

[0077] Comparative Example 4

[0078] A method for preparing an aluminum-based brazing composite material is basically the same as that in Example 1, except that in step (4), ion beam vapor deposition is used to further deposit metal on the surface of the metal oxide layer to form a pure cobalt metal outer layer (cobalt content is 99wt%).

[0079] The bonding strength between the pure cobalt metal outer layer and the filler alloy layer of the prepared aluminum-based brazing composite material is level 3; the weld length of the aluminum-based brazing composite material when brazing is performed using a T-type model is 19 mm.

[0080] Compared with Example 1, the bonding strength and weld length of Comparative Example 4 are smaller than those of Example 1. This is because changing the metal outer layer to pure cobalt cannot achieve the same effect as pure nickel, and the use of pure nickel for the outer layer is irreplaceable.

[0081] Example 2

[0082] A method for preparing an aluminum-based brazing composite material, comprising the following specific steps:

[0083] (1) A composite ingot is obtained by a composite casting method and is composed of a filler alloy layer, a core layer, and an anti-corrosion layer with a target composite ratio, wherein the filler alloy layer and the anti-corrosion layer are respectively located on both sides of the core layer; the composite ingot is then subjected to hot rolling, cold rolling, and annealing processes to obtain a composite aluminum plate with target specifications and performance;

[0084] Among them, the core layer is 6063 aluminum alloy with Mg and Si as the main alloying elements;

[0085] The filler alloy layer is a 4343 aluminum-silicon alloy with Si as the main alloying element;

[0086] The anti-corrosion layer is 7072 aluminum-zinc alloy with Zn as the main alloying element;

[0087] (2) using magnetron sputtering etching to pre-treat the surface of the filler alloy layer of the composite aluminum plate obtained in step (1) to remove the aluminum oxide layer that affects the brazing effect, and at the same time remove the surface oil residue and foreign particles;

[0088] (3) At a pressure of 5×10 －5 Under vacuum conditions of 1.5 Pa, a metal oxide layer composed of a mixture of 32 wt% nickel oxide, 60 wt% iron oxide, and 8 wt% cobalt oxide was deposited on the surface of the filler alloy layer of the pretreated composite aluminum plate by ion beam vapor deposition; the thickness of the metal oxide layer was 5 nm, and the thickness deviation was 1%.

[0089] The process parameters for depositing the metal oxide layer were: ion beam application time 10 min, beam current 56 μA, voltage 6 kV;

[0090] (4) At a pressure of 5×10 －5 Under a vacuum condition of 1.5 Pa, metal is further deposited on the surface of the metal oxide layer prepared in step (3) by ion beam vapor deposition to form a nickel metal outer layer with a thickness of 400 nm and a thickness deviation of 0.20%; the nickel content of the nickel metal outer layer is 99.1 wt%;

[0091] The process parameters for depositing metal to form the nickel metal outer layer are: ion beam application time 150 min, beam current 56 μA, voltage 7 kV;

[0092] like Figure 7As shown, the aluminum-based brazing composite material with a total thickness of 0.04 mm includes a core layer 4, an anti-corrosion layer 7 (the thickness is 8% of the total thickness of the aluminum-based brazing composite material) and a brazing composite layer 5; the brazing composite layer 5 includes a nickel metal outer layer 1, a metal oxide layer 2 and a filler alloy layer 3 (the thickness is 10% of the total thickness of the aluminum-based brazing composite material); the bonding strength between the nickel metal outer layer 1 and the filler alloy layer 3 is level 3; the weld length of the aluminum-based brazing composite material when brazing using a T-type pattern model is 31 mm.

[0093] Example 3

[0094] A method for preparing an aluminum-based brazing composite material, comprising the following specific steps:

[0095] (1) The core layer and two filler alloy layers were prepared using a conventional semi-continuous casting method;

[0096] Among them, the core layer is 6060 aluminum alloy with Mg and Si as the main alloying elements;

[0097] The filler alloy layer is 4043 aluminum alloy with Si as the main alloying element;

[0098] (2) stacking the filler alloy layer, the core layer, and the filler alloy layer in this order, performing bonding rolling, and then hot rolling, cold rolling, and annealing to obtain a composite aluminum plate with target specifications and performance;

[0099] (3) Ion etching is used to pre-treat the surface of a filler alloy layer of the composite aluminum plate to remove the aluminum oxide layer that affects the brazing effect, and at the same time remove the surface oil residue and foreign particles;

[0100] (4) At a pressure of 5×10 －5 Under vacuum conditions of 1.5 Pa, a metal oxide layer composed of a mixture of 60 wt% nickel oxide and 40 wt% iron oxide was deposited on the surface of the filler alloy layer of the pretreated composite aluminum plate by ion beam vapor deposition; the thickness of the metal oxide layer was 9 nm, and the thickness deviation was 2%.

[0101] The process parameters for depositing the metal oxide layer by ion beam vapor deposition were: ion beam application time 25 min, beam current 60 μA, voltage 8 kV;

[0102] (5) At a pressure of 5×10 －5 Under a vacuum condition of 1.5 Pa, metal is further deposited on the surface of the metal oxide layer obtained in step (4) by ion beam vapor deposition to form a nickel metal outer layer with a thickness of 5 nm and a thickness deviation of 10%, thereby obtaining an aluminum-based brazing composite material; the nickel content in the nickel metal outer layer is 99.3 wt%;

[0103] The process parameters for depositing metal to form a nickel metal outer layer by ion beam vapor deposition are: ion beam application time 8 min, beam current 60 μA, and voltage 3 kV.

[0104] An aluminum-based brazing composite material with a total thickness of 0.1 mm was prepared, comprising a filler alloy layer, a core layer, and a brazing composite layer; the brazing composite layer comprised a nickel metal outer layer, a metal oxide layer, and a filler alloy layer (the thickness of which was 30% of the total thickness of the aluminum-based brazing composite material); the bonding strength between the nickel metal outer layer and the filler alloy layer was level 2; and the weld length of the aluminum-based brazing composite material when brazing was performed using a T-type pattern was 35 mm.

[0105] Example 4

[0106] A method for preparing an aluminum-based brazing composite material, comprising the following specific steps:

[0107] (1) The core layer and two filler alloy layers are prepared separately using a conventional continuous casting method;

[0108] Among them, the core layer is 3203 aluminum alloy with Mn as the main alloying element;

[0109] The prepared filler alloy layer is a 4047 aluminum alloy with Si as the main alloying element;

[0110] (2) stacking the filler alloy layer, the core layer, and the filler alloy layer in this order, performing bonding rolling, and then hot rolling, cold rolling, and annealing to obtain a composite aluminum plate with target specifications and performance;

[0111] (3) Magnetron sputtering etching is used to pre-treat the surface of a filler alloy layer of the composite aluminum plate to remove the aluminum oxide layer that affects the brazing effect, and at the same time remove the surface oil residue and foreign particles;

[0112] (4) At a pressure of 5×10 －5 Under vacuum conditions of 1.5 Pa, a metal oxide layer composed of a mixture of 78 wt% nickel oxide and 22 wt% iron oxide was deposited on the surface of the filler alloy layer of the pretreated composite aluminum plate by ion beam vapor deposition; the thickness of the metal oxide layer was 12 nm, and the thickness deviation was 1.5%;

[0113] The process parameters for depositing the metal oxide layer by ion beam vapor deposition were: ion beam application time 3 min, beam current 70 μA, voltage 3 kV;

[0114] (5) At a pressure of 5×10 －5 Under a vacuum condition of 1.5 Pa, metal is further deposited on the surface of the metal oxide layer obtained in step (4) by ion beam vapor deposition to form a nickel metal outer layer with a thickness of 50 nm and a thickness deviation of 2%; the nickel content of the nickel metal outer layer is 99.4 wt%;

[0115] The process parameters for depositing metal to form the nickel metal outer layer by ion beam vapor deposition are: ion beam application time 1500 min, beam current 70 μA, voltage 4 kV;

[0116] (6) Repeat steps (3) to (5) on the surface of another filler alloy layer of the composite aluminum plate obtained in step (5) to obtain an aluminum-based brazing composite material.

[0117] like Figure 5 As shown, an aluminum-based brazing composite material with a total thickness of 2 mm is prepared, including a core layer 4 and two brazing composite layers 5; each brazing composite layer 5 includes a nickel metal outer layer 1, a metal oxide layer 2 and a filler alloy layer 3 (the thickness of each filler alloy layer is 8% of the total thickness of the aluminum-based brazing composite material); the bonding strength between the nickel metal outer layer 1 and the filler alloy layer 3 is level 2; the weld length of the aluminum-based brazing composite material when brazing using a T-type pattern model is 38 mm.

[0118] Example 5

[0119] A method for preparing an aluminum-based brazing composite material, comprising the following specific steps:

[0120] (1) The core layer, filler alloy layer, intermediate layer, and anti-corrosion layer are respectively produced by conventional continuous casting and rolling methods;

[0121] Among them, the core layer is 6063 aluminum alloy with Mg and Si as the main alloying elements;

[0122] The middle layer is 1050 aluminum alloy;

[0123] The filler alloy layer is 4045 aluminum alloy with Si as the main alloying element;

[0124] The anti-corrosion layer is 7072 aluminum alloy with Zn as the main alloying element;

[0125] (2) After the anti-corrosion layer, core layer, intermediate layer and filler alloy layer are stacked in sequence, they are bonded and rolled, and then hot rolled, cold rolled and annealed to obtain a composite aluminum plate with target specifications and performance;

[0126] (3) pre-treating the surface of the filler alloy layer of the composite aluminum plate obtained in step (2) by glow discharge etching to remove the aluminum oxide layer that affects the brazing effect, and at the same time remove the surface oil residue and foreign particles;

[0127] (4) At a pressure of 5×10 －5Under vacuum conditions of 1.5 Pa, a metal oxide layer composed of a mixture of 36 wt% nickel oxide and 64 wt% cobalt oxide was deposited on the surface of the filler alloy layer of the composite aluminum plate by ion beam vapor deposition; the thickness of the metal oxide layer was 18 nm, and the thickness deviation was 0.9%.

[0128] The process parameters for depositing the metal oxide layer by ion beam vapor deposition were: ion beam application time 30 min, beam current 80 μA, voltage 4 kV;

[0129] (5) At a pressure of 5×10 －5 Under vacuum conditions of 1000 Pa, an ion beam vapor deposition method is used to continuously deposit metal on the surface of the metal oxide layer to form a nickel metal outer layer with a thickness of 1000 μm and a thickness deviation of 0.10%, thereby producing an aluminum-based brazing composite material; the nickel content in the nickel metal outer layer is 99.9 wt%;

[0130] The process parameters for depositing metal to form a nickel metal outer layer by ion beam vapor deposition are: ion beam application time 750 min, beam current 80 μA, and voltage 10 kV.

[0131] like Figure 6 As shown, an aluminum-based brazing composite material with a total thickness of 6 mm is prepared, including an anti-corrosion layer 7 (the thickness is 5% of the total thickness of the aluminum-based brazing composite material), a core layer 4, an intermediate layer 6 (the thickness is 5% of the total thickness of the aluminum-based brazing composite material) and a brazing composite layer; the brazing composite layer includes a nickel metal outer layer 1, a metal oxide layer 2 and a filler alloy layer 3 (the thickness is 2% of the total thickness of the aluminum-based brazing composite material); the bonding strength between the nickel metal outer layer 1 and the filler alloy layer 3 is level 3; the weld length of the aluminum-based brazing composite material when brazing using a T-type pattern model is 32 mm.

[0132] Example 6

[0133] A method for preparing an aluminum-based brazing composite material is basically the same as that of Example 1, except that the only difference is the deposition process of step (3). The metal oxide layer obtained in the final step (3) is a layer structure made of nickel oxide, and the thickness of the metal oxide layer is 3 nm, and the thickness deviation is 10%.

[0134] The bonding strength between the nickel metal outer layer and the filler alloy layer of the prepared aluminum-based brazing composite material is level 1; the weld length of the aluminum-based brazing composite material when brazing is performed using a T-type model is 41 mm.

[0135] Example 7

[0136] A method for preparing an aluminum-based brazing composite material is basically the same as that of Example 1, except that the only difference is the deposition process of step (3). The metal oxide layer obtained in the final step (3) is a metal oxide layer made of a mixture of 70wt% nickel oxide and 30wt% iron oxide. The thickness of the metal oxide layer is 50nm, and the thickness deviation is 0.1%.

[0137] The bonding strength between the nickel metal outer layer and the filler alloy layer of the prepared aluminum-based brazing composite material is level 2; the weld length of the aluminum-based brazing composite material when brazing is performed using a T-type model is 30 mm.

[0138] Example 8

[0139] A method for preparing an aluminum-based brazing composite material is basically the same as that of Example 1, except that the only difference is the deposition process of step (3). The metal oxide layer obtained in the final step (3) is a metal oxide layer made of a mixture of 70wt% nickel oxide and 30wt% iron oxide. The thickness of the metal oxide layer is 22nm, and the thickness deviation is 0.5%.

[0140] The bonding strength between the nickel metal outer layer and the filler alloy layer of the prepared aluminum-based brazing composite material is level 2; the weld length of the aluminum-based brazing composite material when brazing is performed using a T-type model is 32 mm.

[0141] Example 9

[0142] A method for preparing an aluminum-based brazing composite material is basically the same as that of Example 1, except that the only difference is the deposition process of step (3). The metal oxide layer obtained in the final step (3) is a metal oxide layer made of a mixture of 70wt% nickel oxide and 30wt% iron oxide. The thickness of the metal oxide layer is 20nm, and the thickness deviation is 0.5%.

[0143] The bonding strength between the nickel metal outer layer and the filler alloy layer of the prepared aluminum-based brazing composite material is level 2; the weld length of the aluminum-based brazing composite material when brazing is performed using a T-type model is 38 mm.

[0144] Example 10

[0145] A method for preparing an aluminum-based brazing composite material is basically the same as that of Example 1, except that the only difference is the deposition process of step (3). The metal oxide layer obtained in the final step (3) is a metal oxide layer made of a mixture of 70wt% nickel oxide and 30wt% iron oxide. The thickness of the metal oxide layer is 10nm, and the thickness deviation is 2%.

[0146] The bonding strength between the nickel metal outer layer and the filler alloy layer of the prepared aluminum-based brazing composite material is level 2; the weld length of the aluminum-based brazing composite material when brazing is performed using a T-type model is 39 mm.

[0147] Examples 1 and 7 to 10 prepared metal oxide layers of different thicknesses. The evaluation results showed that a thickness of 3 to 20 nm, more preferably 10 to 20 nm, was more suitable for obtaining excellent weld length. A metal oxide layer with too high a thickness would hinder the melting and wetting of the solder during brazing.

[0148] Example 11

[0149] A method for preparing an aluminum-based brazing composite material is basically the same as that in Example 1, except that in step (4), nickel is plated using an electroplating process to form a nickel metal outer layer.

[0150] In the prepared aluminum-based brazing composite material, the thickness of the nickel metal outer layer is 5nm, and the thickness deviation is 120%, and the bonding strength between the nickel metal outer layer and the filler alloy layer is level 3; the weld length of the aluminum-based brazing composite material when brazing is performed using a T-type pattern model is 30mm; compared with the vapor deposition method, the electroplating method is difficult to control the thickness deviation of the nickel metal outer layer to be very small, and when the nickel metal outer layer reaches the same level of thickness as the metal oxide layer, the thickness uniformity difference is too large, which will lead to poor adhesion between the nickel metal outer layer and the metal oxide layer, thereby affecting the weld length.

Claims

1. An aluminum-based brazing composite material, characterized by: It comprises a core layer (4) and a brazing composite layer (5); the brazing composite layer (5) comprises a nickel metal outer layer (1), a metal oxide layer (2) and a filler alloy layer (3); The metal oxide layer (2) is located between the filler alloy layer (3) and the nickel metal outer layer (1); the filler alloy layer (3) is located on a side of the brazing composite layer (5) facing the core layer (4); The metal oxide layer contains more than 30 wt% of nickel oxide; the nickel content in the nickel metal outer layer (1) is ≥99 wt%.

2. The aluminum-based brazing composite material according to claim 1, characterized in that: The core layer (4) is a 3xxx series aluminum alloy with Mn as the main alloying element or a 6xxx series aluminum alloy with Mg and Si as the main elements; The filler alloy layer (3) is a 4xxx series aluminum-silicon alloy.

3. The aluminum-based brazing composite material according to claim 1, characterized in that: One side or both sides of the core layer (4) in the aluminum-based brazing composite material are the brazing composite layers (5).

4. The aluminum-based brazing composite material according to claim 1, characterized in that: The total thickness of the aluminum-based brazing composite material is ≤6 mm; in the aluminum-based brazing composite material, the thickness of each filler alloy layer (3) is 2-30% of the total thickness of the aluminum-based brazing composite material.

5. The aluminum-based brazing composite material according to claim 4, characterized in that: The thickness of the nickel metal outer layer (1) in each brazing composite layer (5) is 5 to 1000 nm, and the thickness deviation is ≤10%; The thickness of the metal oxide layer (2) in each brazing composite layer (5) is 3-20 nm, and the thickness deviation is ≤10%.

6. The aluminum-based brazing composite material according to claim 1, characterized in that: The bonding strength between the nickel metal outer layer and the filler alloy layer is level 3 or above; the weld length of the aluminum-based brazing composite material when brazing is performed using a T-shaped model is ≥30 mm.

7. A method for preparing an aluminum-based brazing composite material according to any one of claims 1 to 6, characterized in that: A metal oxide layer (2) is first deposited on the surface of a filler alloy layer (3) of a composite aluminum plate by using an ion beam vapor deposition method, and then a metal is continuously deposited to form a nickel metal outer layer (1); The ion beam vapor deposition method is performed under vacuum conditions.

8. The method for preparing an aluminum-based brazing composite material according to claim 7, characterized in that: Before depositing the metal oxide layer (2), ion etching, magnetron sputtering etching or glow discharge etching is used to pre-treat the surface of the filler alloy layer (3) of the composite aluminum plate.

9. The method for preparing an aluminum-based brazing composite material according to claim 7, characterized in that: The process parameters for depositing the metal oxide layer (2) are: ion beam application time of 3 to 30 minutes, beam current not exceeding 80 μA, and voltage of 3 to 8 kV; The process parameters for depositing metal to form the nickel metal outer layer (1) are: ion beam application time of 8 to 1500 minutes, beam current not exceeding 80 μA, and voltage of 3 to 10 kV.

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