Low temperature vacuum brazing of aluminum matrix composites and method of brazing

Abstract

The present application relates to a kind of low-temperature vacuum brazing aluminum base composite material and its brazing method, low-temperature vacuum brazing aluminum base composite material includes core layer, brazing filler metal layer located the outside of the core layer and the metal copper deposition layer deposited in the outside of the brazing filler metal layer;The brazing filler metal layer is Al-Si-Mg alloy;The content of Cu element in the metal copper deposition layer is ≥99.0wt%;The binding force of the metal copper deposition layer and the brazing filler metal layer reaches the 0 level of GB / T9286-2021 paint and varnish grid test;The thickness of the metal copper deposition layer accounts for the thickness of the brazing filler metal layer and the metal copper deposition layer 0.5-2.0%;Brazing method includes steps: (1) vacuum environment adjustment;(2) brazing;(3) cooling sampling.The melting point of the low-temperature vacuum brazing aluminum base composite material of the present application is lower, and the brazing performance is excellent, while the corrosion resistance is excellent.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aluminum alloy laminated composite materials, and particularly relates to a low-temperature vacuum brazing aluminum-based composite material and a brazing method thereof. BACKGROUND

[0002] Aluminum alloy laminated composite materials with Al-Mn series alloy as a core layer and Al-Si series alloy as a skin material are widely used in the production and manufacturing of automobile heat exchangers (water tank, condenser, evaporator, oil cooler, etc.). With the increasing demand for automobile lightweight, automobile manufacturers and heat exchanger manufacturers have put forward higher requirements for the comprehensive performance of aluminum alloy laminated composite materials for automobile heat exchangers. On the basis of improving the mechanical properties of the materials, the thickness boundary of the materials is constantly explored in order to further reduce the weight of the heat exchanger, while improving or maintaining the corrosion resistance of the automobile heat exchanger and prolonging the service life of the automobile heat exchanger. The most critical step from the aluminum alloy laminated composite material to the aluminum heat exchanger is high-temperature (595-610℃) brazing, that is, the assembled aluminum heat exchanger assembly is heated to a temperature higher than the liquidus temperature of the Al-Si series skin material alloy and lower than the solidus temperature of the Al-Mn series core layer alloy in an inert gas environment (inert gas protection brazing) or a vacuum environment (vacuum brazing), and is kept warm. In this process, the skin material alloy undergoes melting-wetting-spreading-filling processes and forms welded joints under the influence of capillary action at various contact or near-contact positions of the aluminum heat exchanger assembly. The formation of these welded joints connects the various components of the aluminum heat exchanger to form a whole, and after cooling, a complete heat exchanger body is produced.

[0003] In the production process of automobile heat exchanger, vacuum brazing as the most commonly used brazing method of aluminum heat exchanger besides inert gas protection brazing has the following advantages: 1) the brazed parts are in vacuum condition during the whole brazing process, and there is no oxidation, carbon deposition and pollution metamorphism phenomenon; 2) the parts are uniformly heated during brazing, the internal thermal stress of the parts is small, and the deformation can be controlled to the minimum, which is especially suitable for the welding of precision products; 3) the low pressure existing around the metal matrix and the filler metal can remove the volatile gases and impurities released by the metal at the brazing temperature, so that the performance of the base metal can be improved; 4) components with narrow grooves, small transition platforms and blind holes, closed containers and complex shaped assemblies can be used without considering the corrosion and cleaning problems caused by the need to spray brazing agent on the surface of the heat exchanger before inert gas protection brazing. However, vacuum brazing also has its own shortcomings. Unlike inert gas protection brazing which can reach the target temperature at a relatively fast heating rate, the heating rate of vacuum brazing is relatively slow and the time is relatively long. In order to ensure that the inner and outer components of the automobile heat exchanger are uniformly heated, the holding time at the target temperature is also relatively long, which often leads to a longer time for the Al-Si(-Mg) series skin material to stay in the liquid phase after melting. These molten liquid phases will gradually diffuse into the core layer, forming a corrosion phenomenon. The occurrence of corrosion reduces the mechanical properties and corrosion resistance of the entire automobile heat exchanger, and severe corrosion can cause perforation, resulting in product scrap. This phenomenon is particularly prominent in the vacuum brazing process of large-scale engineering machinery aluminum heat exchanger.

[0004] In order to solve the corrosion problem of the above-mentioned aluminum heat exchanger material in the conventional vacuum brazing process, it is an inevitable trend for the industry to develop a corrosion-resistant aluminum alloy layered composite material for automobile heat exchanger which can be applied at a lower vacuum brazing temperature. It is also an urgent problem that needs to be solved by the raw material manufacturers of automobile heat exchanger.

[0005] In order to reduce the brazing temperature, the existing technology usually reduces the melting point of the filler metal by adding Cu element in the filler metal. Within a certain range, the melting point gradually decreases with the increase of Cu content, so as to reduce the brazing temperature. However, the existing technology such as adding 15-25% Cu element in the filler metal, the melting point of the filler metal is 460-500℃, and the vacuum brazing of aluminum alloy can be realized at 520-530℃. However, such alloy is prone to ingot cracking in conventional semi-continuous casting, with a high scrap rate, and it is difficult to realize industrialized stable production. Even if the low melting point of the filler metal layer is prepared, due to the high chemical potential of Cu element in the filler metal layer, the addition of Cu element will obviously increase the electrochemical potential of the filler metal. After brazing with other target aluminum alloy welding parts, the electrochemical potential of the filler metal layer is higher than that of the target welding part. In the corrosion medium, the original battery effect is formed, the welding part with lower electrochemical potential is preferentially corroded, thereby reducing the service life of the target welding part. SUMMARY

[0006] The present application aims to solve the problems in the prior art, and provides a low-temperature vacuum brazing aluminum-based composite material and a brazing method thereof, in particular, one of the purposes of the present application is to solve the problem that the addition of Cu element in the filler layer in the prior art causes casting and subsequent processing difficulties, and the second purpose of the present application is to improve the corrosion resistance of the low-temperature vacuum brazing aluminum-based composite material after brazing.

[0007] To achieve the above-mentioned purposes, the technical scheme adopted by the present application is as follows:

[0008] A low-temperature vacuum brazing aluminum-based composite material, comprising a core layer and a filler layer located outside the core layer, the filler layer being an Al-Si-Mg alloy, further comprising a copper deposition layer deposited outside the filler layer;

[0009] The content of Cu element in the copper deposition layer is ≥99.0wt%;

[0010] The bonding force between the copper deposition layer and the filler layer reaches 0 level of GB / T9286-2021 grid test of paint and varnish;

[0011] The thickness of the copper deposition layer accounts for 0.5-2.0% of the sum of the thickness of the filler layer and the copper deposition layer.

[0012] In the prior art, Cu is the preferred element for reducing the melting point of vacuum brazing filler metal, which can significantly reduce the melting point of the filler metal. Within a certain range, the melting point gradually decreases with the increase of Cu content. However, the effect of preparing low-melting-point alloy by adding Cu in the prior art is very limited, because after increasing the Cu element, brittle phases such as Al2Cu are generated in the alloy, which easily leads to cracking problems. Especially for Al-Si-Mg series filler metal for vacuum brazing, even if the addition amount of Cu does not exceed 1%, the Al-Si-Mg alloy ingot often cracks during the melting process. Even if the casting is successful, the existence of brittle phases such as Al2Cu in the subsequent rolling deformation process also easily causes material edge cracking, which seriously affects the material yield. Therefore, it is difficult to prepare low-melting-point vacuum brazing composite material by adding Cu element in the filler metal in industrial production.

[0013] The application breaks through the conventional design thinking of the prior art, in order to avoid the ingot cracking and subsequent rolling edge cracking caused by directly adding Cu elements into the brazing alloy, the Al-Si-Mg alloy brazing material layer + metal copper deposition layer is used to replace the traditional Al-Si-Mg-Cu low melting point brazing material layer; the Al-Si-Mg brazing material and other layers are first obtained into the aluminum-based layered composite coil with a target thickness and state through a hot rolling-cold rolling-annealing process, and then a certain thickness of the metal copper deposition layer is formed on the surface of the coil by using metal deposition methods such as electroplating, magnetron sputtering, electron beam deposition or arc evaporation; since the metal copper deposition layer is deposited on the surface of the composite material after the rolling is completed, the processing process avoids the processing cracking and high defect rate problem existing in the traditional Al-Si-Mg-Cu low melting point brazing material layer; when the composite material with the metal copper deposition layer on the surface is vacuum brazed in the vacuum brazing furnace, the Cu element diffuses to the brazing material layer during the heating process, the brazing material layer changes from the Al-Si-Mg system to the Al-Si-Mg-Cu system, and the melting point of the brazing material layer gradually decreases with the increase of the diffusion degree of the Cu element, so that the low-temperature vacuum brazing is realized.

[0014] The bonding force between the metal copper deposition layer and the brazing material layer reaches the 0 level of GB / T9286-2021 paint and varnish grid test; if the bonding force between the metal copper deposition layer and the aluminum base material cannot reach the 0 level, it will cause Cu diffusion difficulty, and low melting point brazing material cannot be obtained; the bonding force can be adjusted by conventional surface treatment and other methods to meet the requirements;

[0015] The thickness of the metal copper deposition layer accounts for 0.5-2.0% of the sum of the thickness of the brazing material layer and the metal copper deposition layer; when the thickness of the metal copper deposition layer accounts for less than 0.5%, the dissolved copper element in the brazing material layer has limited effect on the melting point reduction of the brazing material, and cannot meet the purpose of low melting point brazing; when the thickness of the metal copper deposition layer accounts for more than 2.0%, too much copper diffuses and melts into the brazing material layer, a large amount of Al2Cu or AlCuSi intermetallic compounds are formed in the brazing material layer after welding, which causes the corrosion resistance of the composite material to deteriorate, and too high proportion of the metal copper deposition layer, the copper cannot completely melt into the brazing material layer during the brazing process, and a layer of excess metal copper deposition layer is still left on the surface of the material, which causes the welding liquid to be unable to flow fully, and the weld length is significantly reduced.

[0016] As a preferred technical solution:

[0017] The low-temperature vacuum brazing aluminum-based composite material as described above, the sum of the thickness of the filler layer and the deposited copper layer accounts for 5-15% of the total thickness of the low-temperature vacuum brazing aluminum-based composite material; when the thickness accounts for less than 5%, the filler layer cannot produce enough molten filler to fill the weld during brazing, resulting in poor welding; when the thickness accounts for more than 15%, the excess molten filler is easy to cause corrosion of the core layer (when the composite material also includes an intermediate layer, the intermediate layer will also be corroded), reducing the strength and corrosion resistance of the composite material after brazing, in addition, the excess filler is easy to form a "climbing" phenomenon on the surface of the aluminum heat exchanger, affecting the appearance of the product, and even the excess filler is easy to cause blockage at the flow channel opening of the aluminum heat exchanger, affecting the heat exchange performance of the aluminum heat exchanger.

[0018] The low-temperature vacuum brazing aluminum-based composite material as described above, the content of Si element in the filler layer is 7.5-12.0wt%; when the content of Si element is less than 7.5wt%, the liquidus temperature of the filler alloy is relatively high, and the difference between the solidus and liquidus temperatures is large, which is not conducive to the flow of the filler alloy; when the content of Si element is greater than 12wt%, the filler alloy is easy to generate coarse primary silicon phase during solidification, hindering the flow of the molten filler alloy.

[0019] The low-temperature vacuum brazing aluminum-based composite material as described above, the content of Mg element in the filler layer is 0.8-2.0wt%; when the content of Mg element is less than 0.8wt%, too little Mg element is difficult to fully break through the oxide film on the surface of the material during vacuum brazing, the brazing material filling effect is poor, and an effective weld cannot be formed, resulting in poor brazing of the product; when the content of Mg element is greater than 2.0wt%, not only is the filler material prone to edge cracking during rolling deformation, reducing the yield, but also too much Mg element will volatilize into the furnace cavity of the vacuum furnace during brazing, adhering to the furnace wall and heating belt, increasing the cleaning cost and reducing the service life of the equipment.

[0020] The low-temperature vacuum brazing aluminum-based composite material as described above, the core layer is a 3XXX series Al-Mn alloy (such as 3003 aluminum alloy) or a 6XXX series Al-Mg-Si alloy (such as 6063 aluminum alloy).

[0021] The low-temperature vacuum brazing aluminum-based composite material as described above, an intermediate layer is further provided between the core layer and the filler layer;

[0022] The intermediate layer is an Al-Zn alloy;

[0023] The content of Zn element in the intermediate layer is not less than 1wt%;

[0024] The thickness of the intermediate layer accounts for more than 5% of the total thickness of the low-temperature vacuum brazing aluminum-based composite material.

[0025] The diffusion of the copper deposition layer during the brazing temperature rising process is the reason for realizing the transformation from the Al-Si-Mg system to the Al-Si-Mg-Cu system, and further changes the melting characteristics of the original filler layer, so that it can melt at a lower temperature; however, the diffusion of the Cu element will also cause the electrochemical potential of the filler layer to rise, resulting in a decrease in the corrosion resistance of the composite material; further, the present application proposes a method for improving the problem of the decrease in corrosion resistance caused by the diffusion of the Cu element, that is, an intermediate layer is arranged between the core layer and the filler layer;

[0026] The intermediate layer is an Al-Zn alloy; the saturated vapor pressure of Zn is relatively high, and during the vacuum brazing process, Zn will diffuse to the surface of the material, and this process is often considered to destroy the oxygen film breaking effect of the Mg element; through sufficient experimental exploration, the inventors have found that reasonable control of the Zn element content in the intermediate layer and the thickness of the intermediate layer to adjust the diffusion capacity of the Zn element can avoid the adverse effects on the oxygen film breaking effect of the Mg element, and a good welding effect can be achieved; a diffusion layer with a Zn content from high to low is formed between the intermediate layer and the filler layer, that is, while the Cu element with a relatively high electrochemical potential diffuses to the filler layer, the Zn element with a relatively low electrochemical potential in the intermediate layer also diffuses to the filler layer, thereby neutralizing the problem of the relatively high electrochemical potential caused by the introduction of the Cu element in the filler layer;

[0027] During the brazing process, the intermediate layer at the lower layer of the filler layer and the copper deposition layer at the upper layer of the filler layer diffuse Zn element and Cu element to the filler layer respectively, so that the filler layer is transformed into a filler layer containing Cu and Zn elements; the present application neutralizes the increase in the electrochemical potential of the filler layer after welding caused by the Cu element by introducing the Zn element, which is different from directly preparing an Al-Si-Mg-Zn filler layer; the Zn element needs to go through the double hindrance of the intermediate layer and the filler layer to diffuse from the intermediate layer to the surface of the material, which slows down the diffusion speed of the Zn element, thereby retaining more Zn elements in the intermediate layer and the filler layer;

[0028] The content of the Zn element in the intermediate layer is not less than 1wt%; since the saturated vapor pressure of Zn is relatively high, when the content of the Zn element is less than 1wt%, Zn will diffuse from the aluminum material to the furnace cavity during the vacuum brazing process, and the functional effect of the intermediate layer cannot be achieved;

[0029] The thickness of the intermediate layer accounts for more than 5% of the total thickness of the low-temperature vacuum brazed aluminum-based composite material; when the thickness of the intermediate layer accounts for less than 5%, Zn can diffuse to the surface of the material during the brazing process, and there is no Zn remaining in the intermediate layer.

[0030] The low-temperature vacuum brazing aluminum-based composite material as described above, the content of Zn element in the intermediate layer is not higher than 10wt%; when the content of Zn element is higher than 10wt%, with the increase of the content of Zn, the Zn remaining in the intermediate layer does not increase obviously, so the content of Zn is preferably not higher than 10wt%.

[0031] The low-temperature vacuum brazing aluminum-based composite material as described above, the thickness of the intermediate layer accounts for 20% or less of the total thickness of the low-temperature vacuum brazing aluminum-based composite material; when the thickness of the intermediate layer is greater than 20%, the too high thickness of the intermediate layer is not conducive to the rolling composite and reduces the material yield.

[0032] The low-temperature vacuum brazing aluminum-based composite material as described above, the filler layer of the low-temperature vacuum brazing aluminum-based composite material melts when the brazing temperature reaches 559-565 DEG C; after brazing, the length of the weld of the low-temperature vacuum brazing aluminum-based composite material is 22-35mm, the salt spray corrosion resistance is 4-18 days, and the corrosion potential is-640 to-725mV.

[0033] The present application provides a brazing method of the low-temperature vacuum brazing aluminum-based composite material as described above, comprising the following steps:

[0034] (1) Vacuum environment adjustment: the low-temperature vacuum brazing aluminum-based composite material is placed in a vacuum brazing furnace for brazing, and the vacuum environment in the furnace is adjusted to ≤10 -3 Pa;

[0035] (2) Brazing: the temperature is raised to 580-585 DEG C, and the holding time is 25-30min; the brazing temperature is set to 580-585 DEG C, the molten filler layer flows and fills the weld under the capillary action, and then an ideal welding joint is obtained; too high temperature can cause the melting of the filler to be more serious, and when the low-temperature vacuum brazing aluminum-based composite material contains an intermediate layer, the Zn diffusion driving force of the intermediate layer increases, which is not conducive to the retention of Zn; too low temperature can cause the filler to not melt completely, and the flowability of the filler is insufficient, resulting in poor welding; the holding time is set to 25-30min, when the low-temperature vacuum brazing aluminum-based composite material contains an intermediate layer, too long time can cause the diffusion and volatilization of Zn to be more serious, which is not conducive to the retention of Zn, resulting in that the high potential caused by Cu cannot be balanced; too short holding time can not make the outer layer Cu diffuse into the filler sufficiently, the reduction of the melting point of the filler is limited, the filler cannot melt at the set temperature, fill the weld, and then a full enough welding joint cannot be formed;

[0036] Alternatively, first, the temperature is raised to 500-540 DEG C, and the temperature is kept for 45-90 min, then the temperature is raised to 580-585 DEG C, and the temperature is kept for 5-15 min; 580-585 DEG C is the temperature range for realizing brazing, if brazing is directly carried out at the temperature, a longer brazing time is needed, so that the Cu element is fully diffused to the brazing filler layer, thereby effectively completing brazing; however, when the low-temperature vacuum brazing aluminum-based composite material contains an intermediate layer, at a high temperature above 580 DEG C, the brazing filler melts, causing the diffusion and volatilization of the Zn element to intensify with the prolongation of the holding time; the present application obtains the best brazing procedure through the study of the diffusion of Cu and Zn at different temperatures: after the first temperature rise to 500-540 DEG C and the temperature is kept for 45-90 min, the Cu element is fully diffused to the brazing filler layer at this temperature, and since the brazing filler has not melted at this temperature, at the same time, a certain thickness of the Cu layer is still left on the surface of the brazing filler, which has a positive effect on hindering the diffusion and volatilization of Zn to the surface; the second temperature rise is to 580-585 DEG C, and the temperature is kept for 5-15 min; after the first stage of temperature rise and holding, a large amount of Cu element has diffused to the brazing filler layer, therefore, compared with the high-temperature brazing procedure, the equivalent brazing effect can be obtained in a shorter time at this stage, and the volatilization amount of the Zn element is significantly reduced, finally resulting in better corrosion resistance; the relatively long time of keeping the temperature at 500-540 DEG C is to further promote the diffusion of Cu to the brazing filler layer, with the intensification of the diffusion of Cu to the brazing filler layer, the Al-Si brazing filler layer gradually changes into an Al-Si-Cu brazing filler layer, and the melting point of the brazing filler layer is lowered accordingly; keeping the temperature below 500 DEG C, the diffusion speed of Cu is limited, and keeping the temperature above 540 DEG C, although the diffusion of Cu can be promoted, the volatilization speed of Zn is significantly increased, which is not conducive to the retention of Zn;

[0037] (3) Cooling sampling: after the furnace temperature drops to 300 DEG C, the furnace door is opened, and the sample is taken out.

[0038] As a preferred technical solution:

[0039] The brazing method as described above, in step (1), 1-5g of pure magnesium sheet or magnesium block is simultaneously put into the furnace; the addition of 1-5g of pure magnesium sheet can neutralize oxygen and water vapor in the furnace gas, and reduce the consumption of Mg element in the material.

[0040] The brazing method as described above, in step (1), the vacuum degree in the furnace is first reduced to 10 -3 Pa, the heating program is automatically started, and the furnace body starts heating; when the temperature rises to 200-250 DEG C, the temperature is kept for a certain time, and then the vacuum is extracted to restore the vacuum degree in the furnace to 10 -3 Pa, and then brazing is carried out again; the water vapor on the sample and the auxiliary tooling evaporates at 200-250 DEG C, so the vacuum degree in the furnace rises, and therefore the vacuum needs to be extracted to restore the vacuum degree to 10 -3Pa, the length of the holding time depends on the recovery time of the vacuum degree in the furnace, and this operation is beneficial to avoiding the environmental oxygen enrichment problem caused by the environmental water vapor (water vapor is decomposed into hydrogen and oxygen under a low vacuum environment), thereby facilitating the diffusion of Cu.

[0041] Advantages:

[0042] The corrosion-resistant low-temperature vacuum brazing aluminum-based composite material for an automobile heat exchanger can not only realize good welding under a low temperature in a vacuum environment, but also has obviously improved corrosion resistance compared to a conventional Al-Si-Mg system as a composite material for a filler material, and the corrosion resistance is improved by more than 120% after a SWAAT seawater circulating salt mist corrosion test. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 is a schematic diagram of the corrosion-resistant low-temperature vacuum brazing aluminum-based composite material of the present application;

[0044] Figure 2 is a schematic diagram of the corrosion-resistant low-temperature vacuum brazing aluminum-based composite material of the present application;

[0045] Figure 3 is a schematic diagram of the distribution of Cu and Zn elements in the corrosion-resistant low-temperature vacuum brazing aluminum-based composite material of the present application during the brazing heating process;

[0046] Figure 4 is a schematic diagram of a T-shaped sample tool;

[0047] In the drawings, 1 is a core layer, 2 is an intermediate layer, 3 is a filler material layer, 4 is a copper deposition layer, 5 is a 3003 alloy, and 6 is a sample to be tested. DETAILED DESCRIPTION

[0048] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present application and are not used to limit the scope of the present application. In addition, it should be understood that after reading the content taught by the present application, those skilled in the art can make various modifications or changes to the present application, and these equivalent forms also fall within the scope of the appended claims of the present application.

[0049] The test methods for some properties in the following examples and comparative examples are as follows:

[0050] (1) Length of the weld: as shown in Figure 4As shown, the sample 6 to be tested was cut into a size of 23 mm x 58 mm, placed on the upper part of the 2 mm thick 25 mm x 60 mm 3003 alloy 5, and then a piece of 1 mm thick 25 mm x 55 mm 3003 alloy 5 was vertically placed on the upper part of the fin material, the other end was padded and fixed with a steel wire with a diameter of 1 mm, so that the distance from the contact point of the vertical 3003 alloy 5 to the steel wire of the sample 6 to be tested was kept at 50 mm, and a cross section like an inverted "T" type tool sample was made, which was referred to as T type sample; after brazing, the length of the weld was counted, the longer the weld, the better the flowability of the welding fluid, and the better the brazing performance;

[0051] (2) Corrosion potential: according to ASTM G 69-2012 (Standard Test Method for Measurement of Corrosion Potentials of Aluminum Alloys) standard, using a Swiss Wanhao Autolab PGSTAT302N electrochemical workstation, the sample to be tested was placed in 1 mol / L NaCl aqueous solution, 9 ml of 30% H2O2 was added before starting, and the data of 50 min, 55 min and 60 min were counted, and the average value of the three data was taken as the corrosion potential;

[0052] (3) Salt spray corrosion resistance days: according to ASTM G 85-2011 (Standard Practice for modified Salt Spary (Fog) Testing) standard, sea salt solution was prepared according to ASTM D-1141, so that 42 g of sea salt solute was contained in 1 liter of solution; a Singleton SCCH22 type salt spray corrosion test box made in the United States was used for testing, the salt spray box was equipped with a timer, and a cycle test of 90 min immersion in an environment with a relative humidity higher than 98% and then 30 min of salt spray was performed; the sample to be tested was sampled every 1 day, and the cross section of the sample to be tested was observed, and when the first cross section perforation was found, the number of days was recorded as the salt spray corrosion resistance days;

[0053] (4) Melting temperature: a German Nicer STA 449F5 synchronous thermal analyzer was used to characterize the melting temperature of the sample to be tested during brazing, the temperature curve of the DSC was consistent with the brazing process used in the examples and comparative examples, the atmosphere was inert atmosphere, and the peak value point of the adjacent endothermic peak on the left side of the maximum endothermic peak was taken as the melting point of the brazing filler layer of the sample to be tested.

[0054] In the following examples:

[0055] The core layer alloy component is not limited, and a suitable alloy system is selected according to specific performance requirements. For example, the aluminum alloy can typically contain 0.05-1.5wt% of Si element, 0.02-1.0wt% of Fe element, 0-1.0wt% of Cu element, 0-2.0wt% of Mn element, 0-2.0wt% of Mg element, 0-4.0wt% of Zn element, 0-0.2wt% of Ti element, and 0-0.2wt% of Zr element.

[0056] In the following examples: the heating rate is 10℃ / min, the general heating rate is 10-20℃, the heating is fast, and the change of the rate does not obviously affect the final result.

[0057] When the low-temperature vacuum brazing aluminum matrix composite contains an intermediate layer, the preparation method comprises the following steps:

[0058] (1) According to the alloy formula, the core layer alloy, the intermediate layer alloy and the filler layer alloy are respectively melted and cast, a 35-ton semi-continuous casting furnace is used to cast a ingot with a thickness of 400mm, a width of 1450mm and a height of 7000mm, and the 10mm wide surface of the ingot is milled to remove the segregation layer on the surface of the ingot, thereby obtaining a 380×1450×7000mm ingot;

[0059] (2) The intermediate layer alloy ingot and the filler layer alloy ingot are respectively hot-rolled to the target thickness, specifically: the intermediate layer alloy ingot obtained in step (1) and the filler layer alloy ingot obtained in step (1) are heated to 480-500℃ and kept for 8-16h, then a single-stand double-coiling hot-rolling machine is used for multi-pass hot-rolling, and after rolling to the target thickness, online shearing is performed to obtain intermediate layer alloy hot-rolled plates and filler layer alloy hot-rolled plates with the target specifications;

[0060] (3) The core layer alloy, the intermediate layer alloy and the filler layer alloy are hot-rolled and combined, specifically: the single or double sides of the 380×1450×7000mm core layer alloy ingot obtained in step (1) are respectively placed with the intermediate layer alloy hot-rolled plates and the filler layer alloy hot-rolled plates obtained in step (2), a steel belt is used for packaging and fixing, the steel belt packaged ingot to be combined is sent into an annealing furnace and heated to 480-500℃ and kept for 9-16h, then the furnace is discharged, the steel belt is cut off, and the high-temperature ingot to be combined is sent into a hot-rolling machine for multi-pass hot-rolling to a thickness of 5-7mm, and then the hot-rolled plate is wound to obtain a target thickness layered hot-rolled coil;

[0061] (4) The layered hot-rolled coil is cold-rolled to a target thickness cold-rolled coil;

[0062] (5) The cold-rolled coil is annealed, specifically: the cold-rolled coil is heated to 350-400℃ and kept for a certain time, and the keeping time depends on the weight of the cold-rolled coil, the greater the weight of the cold-rolled coil, the longer the keeping time.

[0063] (6) cold rolling coil unwinding and copper plating, using a conventional PVD device line for copper plating, the device line is divided into three chambers, the first chamber has a vacuum degree of not less than 1.0x10 -1 Pa, the second chamber has a vacuum degree of not less than 1.0x10 -2 Pa, and the third chamber has a vacuum degree of not less than 5.0x10 -3 Pa, and the target thickness of the copper deposition layer is obtained by adjusting the beam current and the strip speed;

[0064] When the low-temperature vacuum brazing of the aluminum-based composite material does not contain an intermediate layer, the preparation method comprises the following steps:

[0065] (1) according to the alloy formula, respectively melt and cast the core layer alloy and the filler layer alloy, using a 35-ton semi-continuous casting furnace, a cast ingot with a thickness of 400 mm, a width of 1450 mm, and a height of 7000 mm is obtained, and each of the wide surfaces of the cast ingot is milled by 10 mm to remove the segregation layer on the surface of the cast ingot, thereby obtaining a cast ingot with a size of 380x1450x7000 mm;

[0066] (2) hot rolling the filler layer alloy cast ingot to a target thickness, specifically, the filler layer alloy cast ingot obtained in step (1) is heated to 480-500℃ and kept for 8-16h, then the cast ingot is subjected to multi-pass hot rolling by using a single-stand double-coiler hot rolling machine, and after being rolled to the target thickness, online shearing is performed to obtain a hot-rolled plate of the filler layer alloy with a target specification;

[0067] (3) hot rolling the core layer alloy and the filler layer alloy, specifically, the single or double surfaces of the 380x1450x7000 mm core layer alloy cast ingot obtained in step (1) are respectively placed with the hot-rolled plate of the filler layer alloy obtained in step (2), the steel belt is used for packaging and fixing, the packaged cast ingot to be compounded is sent into an annealing furnace, heated to 480-500℃ and kept for 9-16h, then taken out of the furnace, the steel belt is cut off, and the high-temperature cast ingot to be compounded is sent into a hot rolling machine for multi-pass hot rolling to a thickness of 5-7mm, and then coiled to obtain a layered composite hot-rolled coil with a target thickness;

[0068] (4) cold rolling the layered composite hot-rolled coil to a target thickness cold-rolled coil;

[0069] (5) annealing the cold-rolled coil, specifically, the cold-rolled coil is heated to 350-400℃ and kept for a certain time, and the keeping time depends on the weight of the cold-rolled coil, the greater the weight of the cold-rolled coil, the longer the keeping time;

[0070] (6) cold rolling coil unwinding and copper plating, using a conventional PVD device line for copper plating, the device line is divided into three chambers, the first chamber has a vacuum degree of not less than 1.0x10 -1 Pa, the second chamber has a vacuum degree of not less than 1.0x10 -2Pa, the third-stage chamber vacuum degree is not less than 5.0*10 -3 Pa, the third-stage chamber vacuum degree is not less than 5.0*10

[0071] Example 1

[0072] A preparation method of a low-temperature vacuum brazing aluminum matrix composite material, the steps are as follows:

[0073] (1) According to the alloy formula, the core layer alloy, the intermediate layer alloy and the filler layer alloy are respectively melted and cast, a 35-ton semi-continuous casting furnace is used to cast a ingot with a thickness of 400mm, a width of 1450mm and a height of 7000mm, and each of the wide faces of the ingot is milled by 10mm to remove the segregation layer on the surface of the ingot, thereby obtaining a ingot with a size of 380*1450*7000mm;

[0074] (2) The intermediate layer alloy ingot obtained in step (1) and the filler layer alloy ingot obtained in step (1) are heated to 480℃ and kept for 8h, and then a single-stand double-coiling hot rolling mill is used for multi-pass hot rolling of the ingots, and after rolling to a target thickness of 47.5mm, online shearing is performed to obtain intermediate layer alloy hot rolled plates and filler layer alloy hot rolled plates of a target specification;

[0075] (3) The intermediate layer alloy hot rolled plate and the filler layer alloy hot rolled plate obtained in step (2) are placed on one side of the 380*1450*7000mm core layer alloy ingot obtained in step (1), and a steel strip is used for packaging and fixing, and the steel strip packaged ingot is sent into an annealing furnace and heated to 480℃ and kept for 9h, then taken out of the furnace, the steel strip is cut off, and the high-temperature ingot to be compounded is sent into a hot rolling mill for multi-pass hot rolling to a target thickness of 5mm, and then wound to obtain a target thickness layered composite hot rolling coil;

[0076] (4) The layered composite hot rolling coil is cold rolled to a target thickness of 0.2mm, and each coil weighs 5000Kg;

[0077] (5) The cold rolled coil is heated to 350℃ and kept for 2h;

[0078] (6) The cold rolled coil is unwound and plated with copper, a conventional PVD device line is used for copper plating, and the device line is divided into three chambers, the first-stage chamber vacuum degree is 1*10 -1 Pa, the second-stage chamber vacuum degree is 7*10 -2 Pa, the third-stage chamber vacuum degree is 5*10 -3 Pa, the third-stage chamber vacuum degree is not less than 5.0*10

[0079] The final prepared low-temperature vacuum brazing aluminum matrix composite material is as shown in Figure 2As shown, the low-temperature vacuum brazing aluminum-based composite material is composed of a core layer 1, an intermediate layer 2 located outside the core layer, a brazing filler layer 3 located outside the intermediate layer, and a copper deposition layer 4 deposited outside the brazing filler layer; the bonding force between the copper deposition layer 4 and the brazing filler layer 3 reaches the 0 level of GB / T9286-2021 Crosshatch Test for Paint and Varnish;

[0080] The core layer 1 is composed of 0.2wt% of Si element, 0.6wt% of Fe element, 0.9wt% of Cu element, 1.8wt% of Mn element, 0.2wt% of Mg element, 0.02wt% of Ti element, and the balance of Al element and inevitable impurities;

[0081] The intermediate layer 2 is an Al-Zn alloy, and the content of Zn element is 1wt%;

[0082] The brazing filler layer 3 is an Al-Si-Mg alloy, and the content of Si element is 7.5wt%, and the content of Mg element is 0.8wt%;

[0083] The content of Cu element in the copper deposition layer 4 is 99wt%;

[0084] The thickness of the intermediate layer accounts for 5% of the total thickness of the low-temperature vacuum brazing aluminum-based composite material, the thickness of the copper deposition layer 4 accounts for 0.5% of the sum of the thicknesses of the brazing filler layer 3 and the copper deposition layer 4, and the sum of the thicknesses of the brazing filler layer 3 and the copper deposition layer 4 accounts for 5% of the total thickness of the low-temperature vacuum brazing aluminum-based composite material.

[0085] The brazing method of the above-mentioned low-temperature vacuum brazing aluminum-based composite material has the following steps:

[0086] (1) Vacuum environment adjustment: place the low-temperature vacuum brazing aluminum-based composite material into a vacuum brazing furnace for brazing, and adjust the vacuum environment in the furnace to 1x10 -3 Pa; 1g of pure magnesium sheet or magnesium block is also placed in the furnace;

[0087] (2) Brazing: first heat to 500℃, hold for 45min, then heat to 584℃, hold for 5min;

[0088] (3) Cooling and sampling: after the furnace temperature drops to 300℃, open the furnace door and take out the sample.

[0089] The brazing filler layer of the low-temperature vacuum brazing aluminum-based composite material melts when the brazing temperature reaches 565℃; after brazing, the length of the weld of the low-temperature vacuum brazing aluminum-based composite material is 27mm, the salt spray corrosion resistance is 6 days, the corrosion potential is-699mV, and the distribution of Cu and Zn elements during the brazing heating process is as shown in Figure 3 .

[0090] Example 2

[0091] A low-temperature vacuum brazing aluminum-based composite material, substantially the same as embodiment 1, except that there is no intermediate layer.

[0092] A method for preparing a low-temperature vacuum brazing aluminum-based composite material, substantially the same as embodiment 1, except that the corresponding operation of preparing the intermediate layer is omitted.

[0093] A brazing method of a low-temperature vacuum brazing aluminum-based composite material, substantially the same as embodiment 1, except that the low-temperature vacuum brazing aluminum-based composite material used is the low-temperature vacuum brazing aluminum-based composite material of embodiment 2.

[0094] The filler layer of the low-temperature vacuum brazing aluminum-based composite material melts when the brazing temperature reaches 564℃; after brazing, the length of the weld of the low-temperature vacuum brazing aluminum-based composite material is 22mm, the salt spray corrosion resistance is 4 days, and the corrosion potential is -650mV.

[0095] Embodiment 3

[0096] A method for preparing a low-temperature vacuum brazing aluminum-based composite material, the steps being as follows:

[0097] (1) According to the alloy formula, the core layer alloy, the intermediate layer alloy and the filler layer alloy are respectively melted and cast, a 35-ton semi-continuous casting furnace is used to cast a ingot with a thickness of 400mm, a width of 1450mm and a height of 7000mm, and each of the wide faces of the ingot is milled by 10mm to remove the segregation layer on the surface of the ingot, thereby obtaining a 380×1450×7000mm ingot;

[0098] (2) The intermediate layer alloy ingot obtained in step (1) and the filler layer alloy ingot obtained in step (1) are heated to 485℃ and kept for 9h, and then a single-stand double-coiling hot rolling mill is used to hot roll the ingots in multiple passes to a target thickness of 47.5mm, and then online shearing is performed to obtain intermediate layer alloy hot rolled plates and filler layer alloy hot rolled plates of the target specification;

[0099] (3) The intermediate layer alloy hot rolled plate and the filler layer alloy hot rolled plate obtained in step (2) are placed on a single side of the 380×1450×7000mm core layer alloy ingot obtained in step (1), and a steel strip is used for packaging and fixing, and the steel strip packaged ingot is sent into an annealing furnace and heated to 483℃ and kept for 10h, then taken out of the furnace, the steel strip is cut off, and the high-temperature ingot to be compounded is sent into a hot rolling mill and hot rolled in multiple passes to a target thickness of 5.5mm, and then wound to obtain a target thickness layered composite hot rolled coil;

[0100] (4) The layered composite hot rolled coil is cold rolled to a target thickness of 0.6mm, and each coil weighs 5000Kg;

[0101] (5) The cold rolled coil is heated to 355℃ and kept for 2h;

[0102] (6) Cold rolling coil unwinding and copper plating, using a conventional PVD device line for copper plating, the device line is divided into three chambers, the first chamber has a vacuum degree of 0.8x10 -1 Pa, the second chamber has a vacuum degree of 0.6x10 -2 Pa, and the third chamber has a vacuum degree of 0.4x10 -3 Pa, by adjusting the beam current to 957mA and the tape speed to 0.5m / min, a metal copper deposition layer with a target thickness of 500mm is obtained.

[0103] The finally prepared low-temperature vacuum brazed aluminum-based composite material is composed of a core layer, an intermediate layer located outside the core layer, a filler layer located outside the intermediate layer, and a metal copper deposition layer deposited outside the filler layer; the bonding force between the metal copper deposition layer and the filler layer reaches 0 level of GB / T9286-2021 grid test for paints and varnishes.

[0104] The core layer is composed of 0.2wt% of Si element, 0.6wt% of Fe element, 0.9wt% of Cu element, 1.8wt% of Mn element, 0.2wt% of Mg element, 0.02wt% of Ti element, and the balance of Al element and inevitable impurities.

[0105] The intermediate layer is an Al-Zn alloy, and the content of Zn element is 4wt%;

[0106] The filler layer is an Al-Si-Mg alloy, the content of Si element is 8wt%, and the content of Mg element is 0.9wt%;

[0107] The content of Cu element in the metal copper deposition layer is 99.2wt%;

[0108] The thickness of the intermediate layer accounts for 12% of the total thickness of the low-temperature vacuum brazed aluminum-based composite material, the thickness of the metal copper deposition layer accounts for 0.6% of the sum of the thicknesses of the filler layer and the metal copper deposition layer, and the sum of the thicknesses of the filler layer and the metal copper deposition layer accounts for 7% of the total thickness of the low-temperature vacuum brazed aluminum-based composite material.

[0109] The brazing method of the above-mentioned low-temperature vacuum brazed aluminum-based composite material has the following steps:

[0110] (1) Vacuum environment adjustment: placing the low-temperature vacuum brazed aluminum-based composite material into a vacuum brazing furnace for brazing, adjusting the vacuum environment in the furnace to 1.1x10 -3 Pa; 2g of pure magnesium sheet or magnesium block is also placed in the furnace;

[0111] (2) Brazing: first heating to 520℃, holding for 60min, then heating to 580℃, holding for 8min;

[0112] (3) Cooling sampling: after the furnace temperature is reduced to 300 DEG C, open the furnace door, and take out the sample.

[0113] The filler layer of the low-temperature vacuum brazing aluminum-based composite material melts when the brazing temperature reaches 563 DEG C; after brazing, the length of the weld of the low-temperature vacuum brazing aluminum-based composite material is 30 mm, the salt spray corrosion resistance is 13 days, and the corrosion potential is -705 mV.

[0114] Example 4

[0115] A preparation method of a low-temperature vacuum brazing aluminum-based composite material, comprising the following steps:

[0116] (1) According to the alloy formula, the core layer alloy, the intermediate layer alloy and the filler layer alloy are respectively melted and cast, a 35-ton semi-continuous casting furnace is used to cast a ingot with a thickness of 400 mm, a width of 1450 mm and a height of 7000 mm, and the wide surface of the ingot is milled by 10 mm to remove the segregation layer on the surface of the ingot, thereby obtaining a ingot with a size of 380*1450*7000 mm;

[0117] (2) The intermediate layer alloy ingot obtained in step (1) and the filler layer alloy ingot obtained in step (1) are heated to 489 DEG C and kept for 10 h, and then a single-stand double-coiling hot rolling mill is used for multi-pass hot rolling of the ingots to a target thickness of 63.3 mm, and then online shearing is performed to obtain intermediate layer alloy hot rolled plates and filler layer alloy hot rolled plates of the target specification;

[0118] (3) The double sides of the 380*1450*7000 mm core layer alloy ingot obtained in step (1) are respectively placed with the intermediate layer alloy hot rolled plates and the filler layer alloy hot rolled plates obtained in step (2), and the steel belt is used for packaging and fixing, and the steel belt packaged composite ingot is sent into an annealing furnace and heated to 485 DEG C and kept for 11 h, then taken out, and the steel belt is cut off, and the high-temperature composite ingot is sent into a hot rolling mill for multi-pass hot rolling to a target thickness of 5.9 mm, and then wound to obtain a target thickness layered composite hot rolling coil;

[0119] (4) The layered composite hot rolling coil is cold rolled to a cold rolling coil with a target thickness of 0.6 mm, and each coil weighs 5000 Kg;

[0120] (5) The cold rolling coil is heated to 360 DEG C and kept for 2 h;

[0121] (6) The cold rolling coil is unwound and copper plated, and a conventional PVD device line is used for copper plating, and the device line is divided into three chambers, the first chamber has a vacuum degree of 6*10 -1 Pa, the second chamber has a vacuum degree of 5*10 -2 Pa, and the third chamber has a vacuum degree of 3*10 -3Pa, the target thickness of the deposited copper layer is 500 mm by adjusting the beam current to 957 mA and the tape speed to 0.5 m / min.

[0122] The finally prepared low-temperature vacuum brazed aluminum-based composite material is composed of a core layer, an intermediate layer located outside the core layer, a filler layer located outside the intermediate layer, and a deposited copper layer deposited outside the filler layer; the bonding force between the deposited copper layer and the filler layer reaches 0 level of GB / T9286-2021 grid test for paints and varnishes.

[0123] The core layer is composed of 0.2wt% of Si element, 0.6wt% of Fe element, 0.9wt% of Cu element, 1.8wt% of Mn element, 0.2wt% of Mg element, 0.02wt% of Ti element, and the balance of Al element and inevitable impurities.

[0124] The intermediate layer is an Al-Zn alloy, and the content of Zn element is 8wt%;

[0125] The filler layer is an Al-Si-Mg alloy, and the content of Si element is 8.6wt%, and the content of Mg element is 1.1wt%;

[0126] The content of Cu element in the deposited copper layer is 99.5wt%;

[0127] The thickness of the intermediate layer accounts for 16% of the total thickness of the low-temperature vacuum brazed aluminum-based composite material, the thickness of the deposited copper layer accounts for 0.7% of the sum of the thicknesses of the filler layer and the deposited copper layer, and the sum of the thicknesses of the filler layer and the deposited copper layer accounts for 9% of the total thickness of the low-temperature vacuum brazed aluminum-based composite material.

[0128] The brazing method of the above-mentioned low-temperature vacuum brazed aluminum-based composite material has the following steps:

[0129] (1) Vacuum environment adjustment: place the low-temperature vacuum brazed aluminum-based composite material into a vacuum brazing furnace for brazing, and adjust the vacuum environment in the furnace to 1.2×10 -3 Pa; 2g of pure magnesium sheet or magnesium block is also placed in the furnace;

[0130] (2) Brazing: the temperature is raised to 580℃, and the temperature is maintained for 25min;

[0131] (3) Cooling and sampling: after the furnace temperature drops to 300℃, the furnace door is opened, and the sample is taken out.

[0132] The filler layer of the low-temperature vacuum brazed aluminum-based composite material melts when the brazing temperature reaches 563℃; after brazing, the length of the weld of the low-temperature vacuum brazed aluminum-based composite material is 29mm, the salt spray corrosion resistance is 15 days, and the corrosion potential is-715mV.

[0133] Example 5

[0134] A method for preparing a low-temperature vacuum brazed aluminum matrix composite material, which is substantially the same as that in Embodiment 4, except that the brazing in step (2) in the brazing method of the low-temperature vacuum brazed aluminum matrix composite material is as follows: first heated to 510℃ and kept for 50 min, then heated to 580℃ and kept for 8 min.

[0135] Before brazing, the melting point of the low-temperature vacuum brazed aluminum matrix composite material is 566℃; after brazing, the length of the weld of the low-temperature vacuum brazed aluminum matrix composite material is 27 mm, the salt spray corrosion resistance is 18 days, and the corrosion potential is -725 mV.

[0136] Embodiment 6

[0137] A method for preparing a low-temperature vacuum brazed aluminum matrix composite material, which is substantially the same as that in Embodiment 4, except that the vacuum environment adjustment in step (1) in the brazing method of the low-temperature vacuum brazed aluminum matrix composite material is as follows: the low-temperature vacuum brazed aluminum matrix composite material is placed in a vacuum brazing furnace for brazing, and the vacuum environment in the furnace is adjusted to 1.2×10 -3 Pa; 2g of pure magnesium sheet or magnesium block is simultaneously placed in the furnace; when the vacuum degree in the furnace is first reduced to 10 -3 Pa, the heating program is automatically started, and the furnace body starts to heat; when the temperature rises to 200℃, it is kept for 45 min; after the vacuum degree in the furnace is restored to 10 -3 Pa again, brazing is performed.

[0138] The brazing filler layer of the low-temperature vacuum brazed aluminum matrix composite material melts when the brazing temperature reaches 562℃; after brazing, the length of the weld of the low-temperature vacuum brazed aluminum matrix composite material is 30 mm, the salt spray corrosion resistance is 14 days, and the corrosion potential is -711 mV.

[0139] Embodiment 7

[0140] A method for preparing a low-temperature vacuum brazed aluminum matrix composite material, the steps are as follows:

[0141] (1) According to the alloy formula, the core layer alloy, the intermediate layer alloy and the brazing filler layer alloy are respectively melted and cast, a 35-ton semi-continuous casting furnace is used to cast a ingot with a thickness of 400 mm, a width of 1450 mm and a height of 7000 mm, and each of the wide faces of the ingot is milled by 10 mm to remove the segregation layer on the surface of the ingot, obtaining a ingot with a size of 380×1450×7000 mm;

[0142] (2) the intermediate layer alloy ingot obtained in step (1) and the filler layer alloy ingot obtained in step (1) are heated to 490℃ and kept for 11h, then the ingots are hot rolled by a single stand double-coiling hot rolling mill in multiple passes, and after being rolled to a target thickness of 63.3mm, the hot-rolled plates of the intermediate layer alloy and the filler layer alloy with the target specification are obtained by on-line shearing;

[0143] (3) the double faces of the 380x1450x7000mm core layer alloy ingot obtained in step (1) are respectively placed with the intermediate layer alloy hot-rolled plate and the filler layer alloy hot-rolled plate obtained in step (2), the steel belt is used for packaging and fixing, the steel belt packaged ingot to be compounded is sent into an annealing furnace and heated to 489℃ and kept for 12h, then the steel belt is cut off, the high-temperature ingot to be compounded is sent into a hot rolling mill and hot rolled in multiple passes to a target thickness of 6mm, and then the layered composite hot-rolled coil with the target thickness is obtained by coiling;

[0144] (4) the layered composite hot-rolled coil is cold-rolled to a cold-rolled coil with a target thickness of 0.8mm, and each coil weighs 5000Kg;

[0145] (5) the cold-rolled coil is heated to 365℃ and kept for 2h;

[0146] (6) the cold-rolled coil is uncoiled and plated with copper, a conventional PVD device line is used for copper plating, the device line is divided into three chambers, the first chamber has a vacuum degree of 0.5x10 -1 Pa, the second chamber has a vacuum degree of 0.5x10 -2 Pa, and the third chamber has a vacuum degree of 4x10 - 3 Pa, by adjusting the beam current to 1626mA and the belt speed to 0.5m / min, a copper deposition layer with a target thickness of 1000mm is obtained.

[0147] The finally prepared low-temperature vacuum brazing aluminum-based composite material is composed of a core layer, an intermediate layer located outside the core layer, a filler layer located outside the intermediate layer, and a copper deposition layer deposited outside the filler layer; the bonding force between the copper deposition layer and the filler layer reaches 0 level of GB / T9286-2021 grid test for paints and varnishes;

[0148] The core layer is composed of 0.2wt% of Si element, 0.6wt% of Fe element, 0.9wt% of Cu element, 1.8wt% of Mn element, 0.2wt% of Mg element, 0.02wt% of Ti element, and the balance of Al element and inevitable impurities;

[0149] The intermediate layer is an Al-Zn alloy, and the content of Zn element is 10wt%;

[0150] The brazing filler metal layer is an Al-Si-Mg alloy, the content of Si element is 9.4wt%, and the content of Mg element is 1.5wt%;

[0151] The content of Cu element in the copper deposition layer is 99.6wt%;

[0152] The thickness of the intermediate layer accounts for 20% of the total thickness of the low-temperature vacuum brazed aluminum-based composite material, the thickness of the copper deposition layer accounts for 1.1% of the sum of the thicknesses of the brazing filler metal layer and the copper deposition layer, and the sum of the thicknesses of the brazing filler metal layer and the copper deposition layer accounts for 10% of the total thickness of the low-temperature vacuum brazed aluminum-based composite material.

[0153] The brazing method of the above low-temperature vacuum brazed aluminum-based composite material has the following steps:

[0154] (1) Vacuum environment adjustment: the low-temperature vacuum brazed aluminum-based composite material is placed in a vacuum brazing furnace for brazing, and the vacuum environment in the furnace is adjusted to 1×10 -3 Pa; 3g of pure magnesium sheet or magnesium block is simultaneously placed in the furnace;

[0155] (2) Brazing: the temperature is raised to 583℃, and the temperature is maintained for 28min;

[0156] (3) Cooling and sampling: after the furnace temperature drops to 300℃, the furnace door is opened, and the sample is taken out.

[0157] The brazing filler metal layer of the low-temperature vacuum brazed aluminum-based composite material melts when the brazing temperature reaches 559℃; after brazing, the length of the weld of the low-temperature vacuum brazed aluminum-based composite material is 35mm, the salt spray corrosion resistance is 16 days, and the corrosion potential is -722mV.

[0158] Example 8

[0159] A low-temperature vacuum brazed aluminum-based composite material is basically the same as that in Example 7, except that the content of Zn element in the intermediate layer is 0.8wt%.

[0160] The brazing conditions are the same as those in Example 7, the brazing filler metal layer of the low-temperature vacuum brazed aluminum-based composite material melts when the brazing temperature reaches 561℃; after brazing, the length of the weld of the low-temperature vacuum brazed aluminum-based composite material is 27mm, the salt spray corrosion resistance is 8 days, and the corrosion potential is -705mV.

[0161] Comparing Example 7 with Example 8 can see that because the saturated vapor pressure of Zn is relatively high, when the content of Zn element is less than 1wt%, Zn will completely diffuse from the aluminum material to the furnace cavity during vacuum brazing, and cannot play the functional effect of the intermediate layer.

[0162] Example 9

[0163] A low-temperature vacuum brazing aluminum-based composite material substantially the same as Example 7, except that the thickness of the intermediate layer accounts for 3% of the total thickness of the low-temperature vacuum brazing aluminum-based composite material.

[0164] The brazing conditions are the same as in Example 7. The filler layer of the low-temperature vacuum brazing aluminum-based composite material melts at a brazing temperature of 560°C. After brazing, the length of the weld of the low-temperature vacuum brazing aluminum-based composite material is 26 mm, the salt spray corrosion resistance is 5 days, and the corrosion potential is -685 mV.

[0165] Comparing Example 7 with Example 9 shows that when the thickness of the intermediate layer accounts for less than 5%, Zn can diffuse to the surface of the material during brazing, resulting in insufficient Zn to neutralize the potential, and the corrosion resistance of the material is severely reduced.

[0166] Example 10

[0167] A method for preparing a low-temperature vacuum brazing aluminum-based composite material, comprising the following steps:

[0168] (1) According to the alloy formula, the core layer alloy and the filler layer alloy are separately cast, a 35-ton semi-continuous casting furnace is used to cast an ingot with a thickness of 400 mm, a width of 1450 mm, and a height of 7000 mm, and the 10 mm wide surface of the ingot is milled to remove the segregation layer on the surface of the ingot, obtaining a 380×1450×7000 mm ingot;

[0169] (2) The filler layer alloy ingot obtained in step (1) is heated to 494°C and held for 12 h, then a single-stand double-coiling hot rolling mill is used for multi-pass hot rolling, and after rolling to a target thickness of 42.2 mm, online shearing is performed to obtain a hot-rolled plate of the filler layer alloy with a target specification;

[0170] (3) The hot-rolled plate of the filler layer alloy obtained in step (2) is placed on one side of the 380×1450×7000 mm core layer alloy ingot obtained in step (1), and a steel strip is used for packaging and fixing. The steel strip packaged ingot is sent to an annealing furnace, heated to 490°C and held for 13 h, then taken out of the furnace, the steel strip is cut off, and the high-temperature ingot to be compounded is sent to a hot rolling mill for multi-pass hot rolling to a target thickness of 6.3 mm, then wound to obtain a layered composite hot-rolled coil with a target thickness;

[0171] (4) The layered composite hot-rolled coil is cold-rolled to a target thickness of 0.2 mm, and each coil weighs 5000 Kg;

[0172] (5) The cold-rolled coil is heated to 390°C and held for 2 h;

[0173] (6) The cold-rolled coil is unwound and copper plated, a conventional PVD device line is used for copper plating, the device line is divided into three chambers, the first chamber has a vacuum degree of 7×10-1 Pa, the vacuum degree of the second stage chamber is 1×10 -2 Pa, the vacuum degree of the third stage chamber is 5×10 -3 Pa, the target thickness of the deposited copper layer is 250 mm by adjusting the beam current to 623 mA and the tape speed to 0.5 m / min.

[0174] The finally prepared low-temperature vacuum brazed aluminum-based composite material is composed of a core layer 1, a filler layer 3 located outside the core layer 1, and a deposited copper layer 4 deposited outside the filler layer 3, as shown in the figure; the bonding force between the deposited copper layer and the filler layer reaches 0 level of GB / T9286-2021 grid test for paints and varnishes. Figure 1

[0175] The core layer is composed of 0.2wt% of Si element, 0.6wt% of Fe element, 0.9wt% of Cu element, 1.8wt% of Mn element, 0.2wt% of Mg element, 0.02wt% of Ti element, and the balance of Al element and inevitable impurities.

[0176] The filler layer is an Al-Si-Mg alloy, the content of Si element is 10.6wt%, and the content of Mg element is 1.9wt%.

[0177] The content of Cu element in the deposited copper layer is 99.7wt%.

[0178] The thickness of the deposited copper layer accounts for 1.5% of the sum of the thicknesses of the filler layer and the deposited copper layer, and the sum of the thicknesses of the filler layer and the deposited copper layer accounts for 12% of the total thickness of the low-temperature vacuum brazed aluminum-based composite material.

[0179] The brazing method of the above-mentioned low-temperature vacuum brazed aluminum-based composite material has the following steps:

[0180] (1) Vacuum environment adjustment: place the low-temperature vacuum brazed aluminum-based composite material into a vacuum brazing furnace for brazing, and adjust the vacuum environment in the furnace to 1×10 -3 Pa; 3g of pure magnesium sheet or magnesium block is also placed in the furnace;

[0181] (2) Brazing: first heat to 535℃ and keep for 80min, then heat to 583℃ and keep for 12min;

[0182] (3) Cooling and sampling: after the furnace temperature drops to 300℃, open the furnace door and take out the sample.

[0183] The filler layer of the low-temperature vacuum brazed aluminum-based composite material melts when the brazing temperature reaches 564℃; after brazing, the length of the weld of the low-temperature vacuum brazed aluminum-based composite material is 27mm, the salt spray corrosion resistance is 4 days, and the corrosion potential is -650mV. ​

[0184] Example 11

[0185] A preparation method of a low-temperature vacuum brazing aluminum-based composite material, the steps are as follows:

[0186] (1) According to the alloy formula, the core layer alloy and the filler layer alloy are respectively melted and cast, a 35-ton semi-continuous casting furnace is used to cast a ingot with a thickness of 400 mm, a width of 1450 mm and a height of 7000 mm, and each of the wide surfaces of the ingot is milled by 10 mm to remove the segregation layer on the surface of the ingot, thereby obtaining a ingot with a size of 380×1450×7000 mm;

[0187] (2) After the filler layer alloy ingot obtained in step (1) is heated to 496℃ and kept for 13h, the ingot is subjected to multi-pass hot rolling by using a single-stand double-coiling hot rolling mill, and after being rolled to a target thickness of 42.2mm, the hot-rolled plate of the filler layer alloy with a target specification is obtained by online shearing;

[0188] (3) The hot-rolled plate of the filler layer alloy obtained in step (2) is placed on one side of the core layer alloy ingot obtained in step (1), and the steel belt is used for packaging and fixing, and the steel belt packaged ingot is sent into the annealing furnace and heated to 493℃ and kept for 14h, then taken out of the furnace, the steel belt is cut off, and the high-temperature ingot to be compounded is sent into the hot rolling mill for multi-pass hot rolling to a target thickness of 6.5mm, and then wound to obtain a target thickness layered composite hot-rolled coil;

[0189] (4) The layered composite hot-rolled coil is cold-rolled to a target thickness of 0.6mm, and each coil weighs 5000Kg;

[0190] (5) The cold-rolled coil is heated to 375℃ and kept for 2h;

[0191] (6) The cold-rolled coil is unwound and plated with copper, and the copper plating is carried out by using a conventional PVD device line, which is divided into three chambers, the first chamber has a vacuum degree of 6×10 -1 Pa, the second chamber has a vacuum degree of 8×10 -2 Pa, and the third chamber has a vacuum degree of 3×10 -3 Pa, the beam current is adjusted to 957mA and the belt speed is adjusted to 0.5m / min to obtain a copper deposition layer with a target thickness of 500mm.

[0192] The finally prepared low-temperature vacuum brazing aluminum-based composite material is composed of a core layer, a filler layer located on the outside of the core layer, and a copper deposition layer deposited on the outside of the filler layer; the bonding force between the copper deposition layer and the filler layer reaches level 0 of GB / T9286-2021 grid test for paints and varnishes;

[0193] The core layer is composed of 0.2 wt% of Si element, 0.6 wt% of Fe element, 0.9 wt% of Cu element, 1.8 wt% of Mn element, 0.2 wt% of Mg element, 0.02 wt% of Ti element, and the balance of Al element and inevitable impurities;

[0194] The filler layer is an Al-Si-Mg alloy, the content of Si element is 10.9 wt%, and the content of Mg element is 1.6 wt%;

[0195] The content of Cu element in the copper deposition layer is 99.9 wt%;

[0196] The thickness of the copper deposition layer accounts for 1.8% of the sum of the thicknesses of the filler layer and the copper deposition layer, and the sum of the thicknesses of the filler layer and the copper deposition layer accounts for 13% of the total thickness of the low-temperature vacuum brazed aluminum-based composite material.

[0197] The brazing method of the above-mentioned low-temperature vacuum brazed aluminum-based composite material has the following steps:

[0198] (1) Vacuum environment adjustment: place the low-temperature vacuum brazed aluminum-based composite material into a vacuum brazing furnace for brazing, and adjust the vacuum environment in the furnace to 1.2×10 -3 Pa; 4g of pure magnesium sheet or magnesium block is simultaneously placed in the furnace;

[0199] (2) Brazing: first heat to 540℃, keep for 90min, then heat to 585℃, keep for 15min;

[0200] (3) Cooling and sampling: after the furnace temperature drops to 300℃, open the furnace door and take out the sample.

[0201] The filler layer of the low-temperature vacuum brazed aluminum-based composite material melts when the brazing temperature reaches 562℃; after brazing, the length of the weld of the low-temperature vacuum brazed aluminum-based composite material is 30mm, the salt spray corrosion resistance is 4 days, and the corrosion potential is -643mV.

[0202] Example 12

[0203] A preparation method of a low-temperature vacuum brazed aluminum-based composite material has the following steps:

[0204] (1) According to the alloy formula, the core layer alloy and the filler layer alloy are respectively melted and cast, a 35-ton semi-continuous casting furnace is used to cast a ingot with a thickness of 400mm, a width of 1450mm, and a height of 7000mm, the wide surface of the ingot is milled by 10mm to remove the segregation layer on the surface of the ingot, and a ingot with a size of 380×1450×7000mm is obtained;

[0205] (2) the brazing filler alloy ingot obtained in step (1) is heated to 498 ℃ and kept for 15 h, and then the ingot is subjected to multi-pass hot rolling by using a single-stand double-coiling hot rolling mill, and after being rolled to a target thickness of 47.5 mm, the hot-rolled plate of the brazing filler alloy in the target specification is obtained by on-line shearing;

[0206] (3) the double sides of the 380 x 1450 x 7000 mm core alloy ingot obtained in step (1) are respectively placed with the hot-rolled plate of the brazing filler alloy obtained in step (2), the steel strip is used for packaging and fixing, the steel strip packaged ingot to be compounded is sent into an annealing furnace and heated to 495 ℃ and kept for 15 h, then taken out of the furnace, the steel strip is sheared off, and the high-temperature ingot to be compounded is sent into a hot rolling mill and subjected to multi-pass hot rolling to a target thickness of 6.8 mm, and then wound to obtain a target-thickness layered composite hot-rolled coil;

[0207] (4) the layered composite hot-rolled coil is cold-rolled to a target thickness of 0.6 mm, and each coil weighs 5000 Kg;

[0208] (5) the cold-rolled coil is heated to 380 ℃ and kept for 2 h;

[0209] (6) the cold-rolled coil is unwound and plated with copper, a conventional PVD device line is used for copper plating, the device line is divided into three chambers, the first chamber has a vacuum degree of 0.2 x 10 -1 Pa, the second chamber has a vacuum degree of 0.6 x 10 -2 Pa, and the third chamber has a vacuum degree of 3 x 10 - 3 Pa, by adjusting the beam current to 957 mA and the strip speed to 0.5 m / min, a target-thickness copper deposition layer of 500 mm is obtained.

[0210] The finally prepared low-temperature vacuum brazing aluminum-based composite material is composed of a core layer, a brazing filler layer located outside the core layer, and a copper deposition layer deposited outside the brazing filler layer; the bonding force between the copper deposition layer and the brazing filler layer reaches 0 level of GB / T9286-2021 Crosshatch Test for Paint and Varnish;

[0211] The core layer is composed of 0.2 wt% of Si element, 0.6 wt% of Fe element, 0.9 wt% of Cu element, 1.8 wt% of Mn element, 0.2 wt% of Mg element, 0.02 wt% of Ti element, and the balance of Al element and inevitable impurities;

[0212] The brazing filler layer is an Al-Si-Mg alloy, the content of Si element is 11.5 wt%, and the content of Mg element is 1.7 wt%;

[0213] The content of Cu element in the copper deposition layer is 99.3 wt%;

[0214] The thickness of the copper deposition layer accounts for 1.9% of the sum of the thicknesses of the brazing filler metal layer and the copper deposition layer, and the sum of the thicknesses of the brazing filler metal layer and the copper deposition layer accounts for 14% of the total thickness of the low-temperature vacuum brazed aluminum-based composite material.

[0215] The brazing method of the low-temperature vacuum brazed aluminum-based composite material is as follows:

[0216] (1) Vacuum environment adjustment: the low-temperature vacuum brazed aluminum-based composite material is placed in a vacuum brazing furnace for brazing, and the vacuum environment in the furnace is adjusted to 1.3 x 10 -3 Pa; 4g of pure magnesium sheet or magnesium block is simultaneously placed in the furnace;

[0217] (2) Brazing: the temperature is raised to 584℃, and the temperature is maintained for 29min;

[0218] (3) Cooling and sampling: after the furnace temperature drops to 300℃, the furnace door is opened, and the sample is taken out.

[0219] The brazing filler metal layer of the low-temperature vacuum brazed aluminum-based composite material melts when the brazing temperature reaches 563℃; after brazing, the length of the weld of the low-temperature vacuum brazed aluminum-based composite material is 29mm, the salt spray corrosion resistance is 4 days, and the corrosion potential is -645mV.

[0220] Example 13

[0221] A preparation method of a low-temperature vacuum brazed aluminum-based composite material is as follows:

[0222] (1) According to the alloy formula, the core layer alloy and the brazing filler metal layer alloy are respectively melted and cast, a 35-ton semi-continuous casting furnace is used to cast a ingot with a thickness of 400mm, a width of 1450mm, and a height of 7000mm, and each of the wide faces of the ingot is milled by 10mm to remove the segregation layer on the surface of the ingot, thereby obtaining a ingot with a size of 380x1450x7000mm;

[0223] (2) The brazing filler metal layer alloy ingot obtained in step (1) is heated to 500℃ and maintained for 16h, and then a single-stand double-coiling hot rolling mill is used for multi-pass hot rolling, and after rolling to a target thickness of 47.5mm, online shearing is performed to obtain a hot-rolled plate of the brazing filler metal layer alloy with a target specification;

[0224] (3) The double faces of the 380x1450x7000mm core layer alloy ingot obtained in step (1) are respectively placed with the hot-rolled plates of the brazing filler metal layer alloy obtained in step (2), and a steel strip is used for packaging and fixing, and the steel strip packaged ingot is sent into an annealing furnace to be heated to 500℃ and maintained for 16h, and then taken out, and the steel strip is cut off, and the high-temperature ingot to be compounded is sent into a hot rolling mill for multi-pass hot rolling to a target thickness of 7mm, and then wound to obtain a target thickness layered composite hot-rolled coil;

[0225] (4) cold-rolling the layered composite hot-rolled coil to a cold-rolled coil with a target thickness of 0.8 mm, 5000 Kg per coil;

[0226] (5) heating the cold-rolled coil to 400℃ and holding for 2h;

[0227] (6) uncoiling the cold-rolled coil for copper plating, using a conventional PVD device line for copper plating, the device line being divided into three chambers, the first chamber having a vacuum degree of 0.5×10 -1 Pa, the second chamber having a vacuum degree of 0.5×10 -2 Pa, and the third chamber having a vacuum degree of 3×10 - 3 Pa, and by adjusting the beam current to 1626 mA and the tape speed to 0.5 m / min, a metal copper deposition layer with a target thickness of 1000 mm is obtained.

[0228] The finally prepared low-temperature vacuum brazed aluminum-based composite material is composed of a core layer, a filler layer located outside the core layer, and a metal copper deposition layer deposited outside the filler layer; the bonding force between the metal copper deposition layer and the filler layer reaches 0 level of the cross-hatch test for paints and varnishes according to GB / T9286-2021;

[0229] The core layer is composed of 0.2wt% of Si element, 0.6wt% of Fe element, 0.9wt% of Cu element, 1.8wt% of Mn element, 0.2wt% of Mg element, 0.02wt% of Ti element, and the balance of Al element and unavoidable impurities;

[0230] The filler layer is an Al-Si-Mg alloy, the content of Si element is 12wt%, and the content of Mg element is 2wt%;

[0231] The content of Cu element in the metal copper deposition layer is 99.8wt%;

[0232] The thickness of the metal copper deposition layer accounts for 2% of the sum of the thicknesses of the filler layer and the metal copper deposition layer, and the sum of the thicknesses of the filler layer and the metal copper deposition layer accounts for 15% of the total thickness of the low-temperature vacuum brazed aluminum-based composite material.

[0233] The brazing method of the above-mentioned low-temperature vacuum brazed aluminum-based composite material has the following steps:

[0234] (1) adjusting the vacuum environment: placing the low-temperature vacuum brazed aluminum-based composite material into a vacuum brazing furnace for brazing, and adjusting the vacuum environment in the furnace to 1×10 -3 Pa; 5g of pure magnesium sheet or magnesium block is also placed in the furnace;

[0235] (2) brazing: the temperature is raised to 585℃ and held for 30min;

[0236] (3) Cooling sampling: after the furnace temperature dropped to 300℃, open the furnace door, take out the sample.

[0237] The filler layer of the low-temperature vacuum brazing aluminum-based composite material melts at a brazing temperature of 559℃; after brazing, the weld length of the low-temperature vacuum brazing aluminum-based composite material is 35mm, the salt spray corrosion resistance is 4 days, and the corrosion potential is -640mV.

[0238] Comparative Example 1

[0239] A low-temperature vacuum brazing aluminum-based composite material, which is basically the same as Example 13, except that the thickness of the metal copper deposition layer accounts for 0.3% of the sum of the thickness of the filler layer and the metal copper deposition layer.

[0240] The filler layer cannot melt at all under the brazing conditions of Example 13, and further increasing the brazing temperature to 600℃, the filler layer only starts to melt at a brazing temperature of 571℃, which does not meet the requirements of low-temperature vacuum brazing.

[0241] Comparing Example 13 with Comparative Example 1, it can be seen that when the thickness of the metal copper deposition layer accounts for less than 0.5%, the dissolved copper element in the filler layer has limited effect on reducing the melting point of the filler, which cannot meet the purpose of low-melting-point brazing.

[0242] Comparative Example 2

[0243] A low-temperature vacuum brazing aluminum-based composite material, which is basically the same as Example 13, except that the thickness of the metal copper deposition layer accounts for 2.5% of the sum of the thickness of the filler layer and the metal copper deposition layer.

[0244] The filler layer of the low-temperature vacuum brazing aluminum-based composite material melts at a brazing temperature of 555℃ under the brazing conditions of Example 13; after brazing, the weld length of the low-temperature vacuum brazing aluminum-based composite material is 10mm, the salt spray corrosion resistance is 3 days, and the corrosion potential is 630mV.

[0245] Comparing Example 13 with Comparative Example 2, it can be seen that when the thickness of the metal copper deposition layer accounts for more than 2.0%, too much copper diffuses and melts into the filler layer, forming a large amount of Al2Cu or AlCuSi intermetallic compounds in the filler layer after brazing, which deteriorates the corrosion resistance of the composite material. In addition, too high a proportion of the metal copper deposition layer, copper cannot completely melt into the filler layer during brazing, and a layer of excess metal copper deposition layer remains on the surface of the material, which is also not conducive to the corrosion resistance of the entire corrosion material.

Claims

1. A low-temperature vacuum brazed aluminum-based composite material comprising a core layer and a brazing material layer located outside the core layer, the core layer being an aluminum alloy and the brazing material layer being an Al-Si-Mg alloy, characterized in that, A metal copper deposition layer is deposited outside the brazing filler metal layer; The content of Si element in the brazing filler metal layer is 7.5-12.0wt%, and the content of Mg element is 0.8-2.0wt%; The content of Cu element in the metal copper deposition layer is ≥99.0wt%; The bonding force between the metal copper deposition layer and the brazing filler metal layer reaches 0 level of GB / T9286-2021 Crosshatch Test for Paint and Varnish; The thickness of the metal copper deposition layer accounts for 0.5-2.0% of the sum of the thickness of the brazing filler metal layer and the metal copper deposition layer; The brazing filler metal layer of the low-temperature vacuum brazed aluminum-based composite material melts when the brazing temperature reaches 559-565℃.

2. The low temperature vacuum brazed aluminum matrix composite of claim 1, wherein, The sum of the thickness of the brazing filler metal layer and the metal copper deposition layer accounts for 5-15% of the total thickness of the low-temperature vacuum brazed aluminum-based composite material.

3. The low temperature vacuum brazed aluminum matrix composite of claim 1, wherein, An intermediate layer is further arranged between the core layer and the brazing filler metal layer; The intermediate layer is Al-Zn alloy; The content of Zn element in the intermediate layer is not less than 1wt%; The thickness of the intermediate layer accounts for more than 5% of the total thickness of the low-temperature vacuum brazed aluminum-based composite material.

4. The low temperature vacuum brazed aluminum matrix composite of claim 3, wherein, The content of Zn element in the intermediate layer is not more than 10wt%.

5. The low temperature vacuum brazed aluminum matrix composite of claim 3, wherein, The thickness of the intermediate layer accounts for less than 20% of the total thickness of the low-temperature vacuum brazed aluminum-based composite material.

6. A brazing method of a low-temperature vacuum brazing of an aluminum-based composite material according to any one of claims 1 to 5, characterized by, The steps include: (1) Vacuum environment adjustment: the low-temperature vacuum brazing aluminum-based composite material is placed into a vacuum brazing furnace for brazing, and the vacuum environment in the furnace is adjusted to ≤10 -3 Pa; (2) Brazing: the temperature is raised to 580-585℃, and the temperature is kept for 25-30min; or, the temperature is first raised to 500-540℃, and the temperature is kept for 45-90min, then the temperature is raised to 580-585℃, and the temperature is kept for 5-15min; (3) Cooling and sampling: after the furnace temperature is reduced to 300℃, the furnace door is opened, and the sample is taken out.

7. The brazing method according to claim 6, characterized by In step (1), 1-5g of pure magnesium sheet or magnesium block is simultaneously put into the furnace. In step (1), 1-5g of pure magnesium sheet or magnesium block is simultaneously put into the furnace.

8. The brazing method according to claim 6, characterized by, In step (1), the furnace vacuum is first reduced to 10 -3 Pa, the heating program is automatically started, the furnace is heated, and when the temperature rises to 200-250°C, the furnace is vacuumized for a certain time to restore the furnace vacuum to 10 -3 Pa, and then the brazing is performed.

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