Brazing plate and preparation method and preparation device thereof

Abstract

The present invention relates to the technical field of brazing materials, and in particular, to a brazing plate and a preparation method and a preparation device thereof. The preparation method of the brazing plate comprises the following steps: S1. Take two brazing strips of required size and specification and a substrate strip of required size and specification; S2. Make the substrate strip pass through the brazing agent liquid and the bonding metal liquid in sequence at a uniform speed, and the substrate strip coming out of the bonding metal liquid is overlapped with the two brazing strips, and the substrate strip is located between the two brazing strips. The overlapped strips are rolled and welded once and then rolled up to obtain a rolled brazing plate. The method of the present invention only requires one rolling and brazing to obtain a brazing plate, and the rolling deformation is small, the temperature is low, the requirements for the rolling mill are low, the energy consumption is low, the efficiency is high, continuous production can be realized, and there are few defects and a high yield rate.

Description

Technical Field

[0001] The invention relates to the technical field of brazing materials, and in particular to a brazing plate and a preparation method and a preparation device thereof. Background Art

[0002] The brazing plate is composed of the base material of the core and the brazing filler metal layers of the upper and lower surfaces. The three are overlapped in a certain thickness ratio and fixed by mechanical riveting or spot welding, and then made by the first large deformation hot rolling compound and subsequent multiple hot rolling and cold rolling. For example, the aluminum brazing plate is composed of the aluminum alloy base material of the core and the brazing filler metal layers of the upper and lower surfaces, and is mainly used for furnace welding of various aluminum heat exchangers and a complete set of aluminum assemblies.

[0003] At present, in the production process of brazing plates, before the first hot rolling and lamination, the substrate material and the brazing material layer need to be mechanically riveted or spot welded. Mechanical riveting has insufficient tension, and it is easy to crack during the large deformation hot rolling and lamination process; spot welding fixation is easy to seal gas and slag inside, forming defects. Regardless of mechanical riveting or spot welding fixation, gas will be sealed inside during the first hot rolling and lamination process, resulting in a large number of pores and defects, and even leading to the problem of partial lamination failure.

[0004] More importantly, the existing preparation method requires a deformation rate of up to 30% for the first hot rolling composite, which relies on large plastic deformation rolling composite. Small deformation cannot rely on plastic deformation composite. The thickness of the three-layer composite plate is required to be as high as about 20 mm, and it needs to undergo multiple rolling and annealing (8-10 passes). The preparation efficiency is extremely low, and there is no efficient preparation method and device. In addition, since the deformation rate of the first hot rolling is as high as 30%, the rolling mill is required to be high, and the rolling mill is easily damaged and has high energy consumption. If only the three-layer composite plate that is close to the finished product after the first deformation is rolled, although the required thickness can be achieved in one process, the composite effect between the brazing material layer and the basic material is not good, it is easy to crack, and rolling cannot be completed. In addition, the traditional method cannot achieve continuous production and has a low output.

[0005] In order to solve the above-mentioned shortcomings, it is urgent to develop a method for manufacturing brazing plates by low-temperature rolling brazing and an integrated continuous manufacturing device.

[0006] In view of this, the present invention is proposed. Summary of the invention

[0007] The first purpose of the present invention is to provide a method for preparing a brazing plate, so as to solve the technical problems that the traditional method has large deformation in the first hot rolling, requires multiple rolling and annealing, has high requirements for the rolling mill, has low efficiency, and cannot achieve continuous production. The method of the present invention can be obtained by only one rolling brazing, and has small rolling deformation, low temperature, low requirements for the rolling mill, low energy consumption, high efficiency, can achieve continuous production, and has few product defects and high yield rate.

[0008] The second object of the present invention is to provide a brazing plate, which is prepared by the method for preparing the brazing plate as described above.

[0009] The third object of the present invention is to provide a brazing plate preparation device, which is suitable for the brazing plate preparation method as described above. The device of the present invention has a simple structure, can realize the continuous production of brazing plates, and can significantly improve production efficiency.

[0010] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0011] A method for preparing a brazing plate comprises the following steps:

[0012] S1. Take two solder strips of the required size and a substrate strip of the required size;

[0013] S2. The substrate strip is passed through the flux liquid and the bonding metal liquid at a uniform speed, and the substrate strip from the bonding metal liquid is overlapped with the two solder strips, the substrate strip is located between the two solder strips, and the overlapped strip is rolled and welded once and then coiled to obtain;

[0014] The bonding metal liquid contains hydrogen-absorbing nanographene, and the hydrogen-absorbing nanographene is obtained by porous nanographene absorbing hydrogen.

[0015] Preferably, before the stacking, the method further comprises the steps of polishing, cleaning and drying the solder strip.

[0016] Preferably, the substrate strip is an aluminum alloy strip, and the aluminum alloy is any one of 3003 aluminum alloy, 6061 aluminum alloy, and 6063 aluminum alloy.

[0017] Preferably, before the substrate strip enters the flux liquid, the method further comprises the steps of polishing, rinsing and drying the substrate strip.

[0018] Preferably, the thickness ratio of the solder strip to the substrate strip is 0.08-0.22.

[0019] Preferably, the speed at which the substrate strip passes through the flux liquid and the bonding metal liquid is 20-30 mm / s.

[0020] Preferably, the flux liquid comprises rosin, zinc fluoroborate and alcohol.

[0021] Preferably, the mass ratio of the rosin, the zinc borate and the alcohol is 7-9:1-3:4-6.

[0022] Preferably, the bonding metal liquid further contains at least one of Sn, Sn-Ag-Cu alloy and Sn-Ag alloy.

[0023] Preferably, the temperature of the bonding metal liquid is 280-300°C.

[0024] Preferably, the mass percentage of the hydrogen absorbing nano-graphene to the bonding metal liquid is 3%-6%.

[0025] Preferably, the rolling welding temperature is 280-300°C.

[0026] And / or, the reduction during the rolling and welding is 5%-10% of the total thickness of the laminated strip.

[0027] A brazing plate is prepared by the method for preparing a brazing plate described in any one of the aforementioned embodiments.

[0028] A brazing plate preparation device is suitable for the brazing plate preparation method described in any one of the aforementioned embodiments, comprising a cleaning mechanism, a brazing flux liquid tank containing brazing flux liquid, a bonding metal liquid tank containing bonding metal liquid, a bonding mechanism, a rolling mill and a winding machine which are arranged in sequence, and a heating mechanism is provided at the bottom of the bonding metal liquid tank.

[0029] Preferably, the cleaning mechanism comprises polishing rollers, a water gun and an air gun which are located on both sides of the substrate strip and are sequentially arranged along the moving direction of the substrate strip.

[0030] Preferably, a first guide roller group is provided in the flux tank.

[0031] Preferably, a second guide roller group is provided in the bonding metal liquid tank.

[0032] Preferably, the laminating mechanism comprises two rollers with adjustable gaps, which are used to tightly fit the three-layer strips by rolling.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] (1) The method of the present invention is to dip the bonding metal liquid on the substrate strip and then bond it to the brazing strip to achieve physical bonding, and then achieve welding through a single rolling and welding process. Compared with the existing hot rolling and laminating method, there is no need for large deformation hot rolling and laminating, and only one rolling and brazing process is required to obtain the brazing plate, thereby eliminating the cumbersome rolling process and annealing process such as multiple hot rolling and cold rolling processes, and can achieve continuous production with high production efficiency, fewer product defects and high yield rate.

[0035] The bonding metal liquid of the present invention contains hydrogen-absorbing nanographene, which utilizes the large surface area and high porosity of the nanographene to physically absorb a large amount of hydrogen. At the moment of rolling and brazing, the gas is released to form a hydrogen atmosphere. Hydrogen is a reducing gas and can react with oxidized inclusions to avoid delamination and cracking of the brazing plate, thereby improving the welding effect of the substrate strip and the brazing material strip. At the same time, the hydrogen release process can also help to bring out the included gas in the weld to avoid the formation of pore defects. After the hydrogen is released, the nanographene can also play a role in strengthening the weld.

[0036] (2) The device of the present invention has a simple structure and is powered by a coiler, so that the substrate strip passes through the flux liquid and the bonding metal liquid at a certain speed. The flux liquid and the bonding metal liquid are impregnated on the surface of the substrate strip, and the solder strip and the substrate strip are tightly bonded together by a bonding mechanism. After being rolled and welded by a roller mill, the device is wound by a coiler to obtain a rolled brazing plate. The continuous production of brazing plates and batch production can be realized, and the production efficiency and yield rate are high. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0038] Figure 1 A schematic diagram of a preparation device and preparation process of a brazing plate provided in an embodiment of the present invention;

[0039] Figure 2 A schematic diagram of the structure of a brazing plate provided in an embodiment of the present invention;

[0040] Figure 3 This is a product picture of the aluminum brazing plate prepared in Example 1 of the present invention;

[0041] Figure 4 This is a product defect diagram of the aluminum brazing plate prepared in Comparative Example 1 of the present invention;

[0042] Figure 5 This is a product defect diagram of the aluminum brazing plate prepared in Comparative Example 2 of the present invention;

[0043] Figure 6 This is a product defect diagram of the aluminum brazing plate prepared in Comparative Example 3 of the present invention.

[0044] Reference numerals:

[0045] 1-substrate strip; 2-cleaning mechanism; 21-polishing roller; 22-water gun; 23-air gun; 3-solder liquid tank; 31-first guide roller group; 4-bonding metal liquid tank; 41-heating mechanism; 42-second guide roller group; 5-laminating mechanism; 6-roller mill; 7-winding machine; 8-soldering strip; 9-brazing plate; 91-base material layer; 92-bonding metal layer; 93-soldering layer. DETAILED DESCRIPTION

[0046] The technical scheme of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, but it will be appreciated by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work, all belong to the scope of protection of the present invention. If the specific conditions are not indicated in the embodiments, they are carried out according to the normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0047] like Figure 1 As shown, the first aspect of the present invention provides a method for preparing a brazing plate, comprising the following steps:

[0048] S1. Take two solder strips of the required size and a substrate strip of the required size;

[0049] S2. The substrate strip is passed through the flux liquid and the bonding metal liquid at a uniform speed, and the substrate strip from the bonding metal liquid is overlapped with the two solder strips, and the substrate strip is located between the two solder strips. The overlapped strip is rolled and welded once and then rolled to obtain a brazing sheet in a roll;

[0050] The used bonding metal liquid contains hydrogen-absorbing nanographene, and the hydrogen-absorbing nanographene is obtained by porous nanographene absorbing hydrogen.

[0051] The method of the present invention firstly allows the substrate strip to pass through the brazing flux liquid and the bonding metal liquid at a uniform speed, immerses the substrate strip in the brazing flux liquid and the bonding metal liquid, and then achieves physical bonding between the brazing strip and the substrate strip by laminating, and obtains the brazing plate by rolling and welding in one pass. In the present invention, the brazing strip and the substrate strip are welded by bonding metal, and the brazing flux liquid plays a role of film removal and flow assistance, thereby improving the welding effect. The method of the present invention does not need to rely on large plastic deformation hot rolling compounding, has low requirements on the rolling mill, and is not easy to damage the rolling mill; and only one rolling pass is required to obtain the brazing plate. Compared with the traditional hot rolling compound method, it does not need complicated calendering processes and annealing processes such as multiple hot rolling and cold rolling, and the preparation efficiency can be improved by 8-10 times. In addition, the method of the present invention can realize the continuous production of the brazing plate, which is convenient for mass production of the brazing plate.

[0052] The method of the present invention does not require mechanical riveting or spot welding before rolling, and will not seal the gas inside. During rolling, the bonding metal liquid can squeeze out the gas, and it is not easy to form defects such as pores. The prepared brazing plate has a high yield rate.

[0053] The bonding metal liquid of the present invention contains hydrogen-absorbing nanographene, which utilizes the large surface area and high porosity of the nanographene to physically absorb a large amount of hydrogen. At the moment of rolling and brazing, the gas is released to form a hydrogen atmosphere. Hydrogen is a reducing gas and can react with oxidized inclusions to avoid delamination and cracking of the brazing plate, thereby improving the welding effect of the substrate strip and the brazing material strip. At the same time, the hydrogen release process can also help to bring out the included gas in the weld to avoid the formation of pore defects. After the hydrogen is released, the nanographene can also play a role in strengthening the weld.

[0054] In some specific embodiments of the present invention, before the solder tape is superimposed on the substrate tape, the steps of polishing, cleaning and drying the solder tape are also included to ensure that the solder tape is clean.

[0055] In some specific embodiments of the present invention, the substrate strip is an aluminum alloy strip, and the aluminum alloy is any one of 3003 aluminum alloy, 6061 aluminum alloy, and 6063 aluminum alloy.

[0056] In some specific embodiments of the present invention, before the substrate strip enters the flux liquid, the steps of polishing, rinsing and drying the substrate strip are also included to ensure that the substrate strip is clean.

[0057] In some specific embodiments of the present invention, the thickness ratio of any solder strip to the substrate strip is 0.08-0.22, for example, it can be any point value among 0.08, 0.09, 0.10, 0.12, 0.15, 0.18, 0.20, 0.22 or a range value consisting of any two point values.

[0058] In some specific embodiments of the present invention, the speed at which the substrate strip passes through the flux liquid and the bonding metal liquid is 20-30 mm / s, for example, it can be any point value among 20 mm / s, 22 mm / s, 25 mm / s, 28 mm / s, 30 mm / s or a range value composed of any two point values; too slow a speed will lead to low production efficiency, and too fast a speed will lead to uneven impregnation and too small an impregnation amount. Therefore, it is necessary to reasonably control the speed at which the substrate strip passes through the flux liquid and the bonding metal liquid.

[0059] In some specific embodiments of the present invention, the flux liquid used includes rosin, zinc borofluoride and alcohol. The flux liquid has the function of removing the film and aiding the flow, thereby improving the welding effect.

[0060] In some specific embodiments of the present invention, the mass ratio of rosin, zinc borate and alcohol in the flux liquid used is 7-9:1-3:4-6, for example, it can be any point value among 7:1:4, 7:2:4, 7:3:4, 7:1:5, 7:2:5, 7:3:5, 7:1:6, 7:2:6, 7:3:6, 8:1:4, 8:2:4, 8:3:4, 8:1:5, 8:2:5, 8:3:5, 8:1:6, 8:2:6, 8:3:6, 9:1:4, 9:2:4, 9:3:4, 9:1:5, 9:2:5, 9:3:5, 9:1:6, 9:2:6, and 9:3:6, or a range value consisting of any two point values. The flux component is a soft flux component, which matches the melting temperature of the bonding metal. The ratio is set within the above range to obtain better activity so that it has a higher defilming and flow-aiding effect in the range of 280-300°C.

[0061] In some specific embodiments of the present invention, the bonding metal liquid used also contains at least one of Sn, Sn-Ag-Cu alloy, and Sn-Ag alloy. The metal component in the bonding metal liquid of the present invention uses Sn or Sn alloy with a low melting point, and the temperature required during rolling and welding is low, which can achieve low-temperature rolling brazing.

[0062] In addition, Sn, Sn-Ag-Cu, and Sn-Ag in the bonding metal liquid are low-melting alloys, which can diffuse and fuse with the aluminum-silicon solder layer, reduce the melting temperature of the aluminum-silicon solder, and form a low-melting solder in situ; at the same time, the low-melting alloy can hinder the Si element in the aluminum-silicon solder from diffusing into the core material in large quantities, thereby maintaining the accuracy of the solder matrix composition; if there is no bonding metal, Si will diffuse into the core material in large quantities, resulting in a low Si content in the solder and a high melting point of the solder.

[0063] In some specific embodiments of the present invention, the temperature of the bonding metal liquid is 280-300°C, for example, it can be any point value among 280°C, 285°C, 290°C, 295°C, 300°C, or a range value consisting of any two point values. The purpose of controlling the temperature is to ensure that the metal is in a molten state, so that the bonding metal liquid can be evenly immersed in the surface of the substrate strip during the uniform movement of the substrate strip, thereby facilitating the continuous production of the brazing plate.

[0064] In some specific embodiments of the present invention, hydrogen-absorbing nanographene is obtained by porous nanographene absorbing hydrogen, which specifically includes the following steps: using hydrogen to discharge the air in a container, then placing the nanographene in the container, continuously introducing hydrogen from the bottom of the container, and exhausting the gas from the top. The volume of the nanographene expands during the process of absorbing hydrogen, and the volume can expand to 30-40 times the original volume after being fully absorbed.

[0065] In some specific embodiments of the present invention, the mass percentage of hydrogen absorbing nano-graphene in the bonding metal liquid is 3%-6%, for example, it can be any point value among 3%, 4%, 5%, 6% or a range value consisting of any two point values.

[0066] When the content of hydrogen-absorbing nano-graphene is less than 3%, the amount of hydrogen released is too small to expel the air at the welding point to form a reducing atmosphere, resulting in poor welding. When the content is higher than 6%, the content of hydrogen-absorbing nano-graphene at the welding point is too high (equivalent to less tin-based bonding metal), affecting the welding strength. In addition, too much nano-graphene increases the brittleness of the welding point, affecting the bonding strength.

[0067] In some specific embodiments of the present invention, the rolling and welding temperature is 280-300°C, for example, it can be any point value among 280°C, 285°C, 290°C, 295°C, and 300°C, or a range value consisting of any two point values. The rolling and welding temperature is determined according to the melting temperature of the bonding metal liquid; the rolling temperature of the traditional hot rolling composite method needs to reach 400-500°C. The method of the present invention can achieve low-temperature rolling and welding, which can reduce energy consumption.

[0068] In some specific embodiments of the present invention, the amount of reduction during rolling and welding is 5%-10% of the total thickness of the solder strip and the substrate strip with the bonding metal liquid adhered to the surface after overlapping. For example, it can be any point value among 5%, 6%, 7%, 8%, 9%, 10% or a range value composed of any two point values. The method of the present invention only requires one rolling, and the rolling deformation is small. Compared with the traditional hot rolling composite method, the plastic deformation of the first hot rolling is significantly reduced, the requirements for the rolling mill are reduced, the energy consumption can be reduced, and the rolling mill is not easily damaged.

[0069] A second aspect of the present invention provides a brazing plate, which is prepared by the method for preparing a brazing plate according to any one of the aforementioned embodiments, such as Figure 2 As shown, the brazing plate 9 prepared by the present invention includes a substrate layer 91, bonding metal layers 92 located on both sides of the substrate layer 91, and a brazing material layer 93 located outside the two metal bonding layers.

[0070] like Figure 1 As shown, the third aspect of the present invention provides a brazing plate preparation device, which is suitable for the brazing plate preparation method described in any one of the aforementioned embodiments, comprising a cleaning mechanism 2, a brazing flux liquid tank 3 containing brazing flux liquid, a bonding metal liquid tank 4 containing bonding metal liquid, a bonding mechanism 5, a rolling mill 6 and a winding machine 7, which are arranged in sequence along the moving direction of the substrate strip 1. A heating mechanism 41 is provided at the bottom of the bonding metal liquid tank 4, which is used to heat the material in the bonding metal liquid tank 4 to make the bonding metal in a molten state to achieve impregnation.

[0071] The present invention provides an integrated device for preparing brazing plates, which can realize continuous production of brazing plates. A coiler 7 provides a power source to drive a substrate strip 1 to move. After being cleaned by a cleaning mechanism 2, the substrate strip passes through a brazing agent liquid and a bonding metal liquid in sequence at a uniform speed, so that the brazing agent liquid and the bonding metal liquid adhere to the surface of the substrate strip 1, and then overlaps with a brazing material strip 8. A brazing plate 9 is obtained by rolling and welding. The coiler 7 is used to coil the obtained brazing plate 9 to realize continuous production, with high production efficiency and high yield.

[0072] In some specific embodiments of the present invention, the cleaning mechanism 2 includes a polishing roller 21, a water gun 22 and an air gun 23 located on both sides of the substrate strip 1 and arranged in sequence along the moving direction of the substrate strip 1. The substrate strip 1 passes between the upper and lower polishing rollers 21, and after polishing, it is rinsed by the upper and lower water guns 22 and then blown dry by the air gun 23, thereby completing the cleaning process.

[0073] In some specific embodiments of the present invention, a first guide roller group 31 is provided in the flux liquid tank 3, and its function is to guide the substrate strip 1 so that the substrate strip 1 is immersed in the flux liquid.

[0074] In some specific embodiments of the present invention, a second guide roller set 42 is provided in the bonding metal liquid tank 4 to guide the substrate strip 1 so that the substrate strip 1 is immersed in the bonding metal liquid.

[0075] In some specific embodiments of the present invention, the laminating mechanism 5 includes two rollers (a pair of rollers) with adjustable gaps, and the function of the rollers is to apply pressure F to the surfaces of the superimposed strips so that the three layers of strips are closely fitted.

[0076] The device provided by the present invention can realize the continuous production of the brazing plate 9. When using the device, the two brazing material strips 8 are first cleaned and dried for standby use, the substrate strip 1 is taken and passed through the upper and lower polishing rollers 21, passed between the upper and lower nozzles of the high-pressure water gun 22 and the high-pressure air gun 23, immersed in the brazing liquid in the brazing liquid tank 3 through the first guide roller group 31, and then immersed in the bonding metal liquid in the bonding metal liquid tank 4 through the second guide roller group 42, and then overlapped with the upper and lower brazing material strips 8 in sequence, passed between the two rollers of the bonding mechanism 5, and passed through the roller gap of the rolling mill 6 to enter the winding machine 7; then turn on the roller heating switch, turn on the heating mechanism 41 under the bonding metal liquid tank 4, when the temperature reaches the preset temperature, adjust the roller pressure to the preset pressure, turn on the power of the winding machine 7, the integrated device starts to work, and continuously performs rolling brazing, and the brazing plate 9 can be continuously wound up.

[0077] The embodiments of the present invention will be described in detail below in conjunction with examples, but those skilled in the art will appreciate that the following examples are only used to illustrate the present invention and should not be considered to limit the scope of the present invention. If specific conditions are not specified in the examples, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be obtained commercially. The following examples are all implemented using the device provided by the present invention.

[0078] Example 1

[0079] S1. Take two solder strips with dimensions of 500 mm in width, 0.1575 mm in thickness and any length. The solder strips are composed of 87.7% Al, 10% Si, 0.3% Cu and 2% Zn by mass percentage. Polish, clean and dry them for later use. Take a 3003 aluminum alloy strip with the same length and width as the solder strip and a thickness of 1.68 mm.

[0080] S2. The 3003 aluminum alloy strip is polished with a polishing roller, washed with a high-pressure water gun and blown dry with a high-pressure air gun to obtain a cleaned 3003 aluminum alloy strip, and then passes through a flux liquid and a bonding metal liquid at a temperature of 280°C at a uniform speed of 20 mm / s in sequence, and the thickness of a single bonding metal liquid layer is 0.0525 mm. The 3003 aluminum alloy strip coming out of the bonding metal liquid is overlapped with two clean brazing strips in the order of "brazing strip-3003 aluminum alloy strip-brazing strip", and after being rolled and laminated by a laminating mechanism, it passes through a roller gap at a temperature of 280°C, and is rolled and welded according to a reduction amount of 5% of the total thickness of the laminated strip to obtain an aluminum brazing plate with a thickness of 2 mm, which is then rolled to obtain a rolled aluminum brazing plate;

[0081] The flux liquid used is a mixture of rosin, zinc fluoroborate and alcohol, wherein the mass ratio of rosin, zinc fluoroborate and alcohol is 8:1:5;

[0082] The bonding metal liquid used is 3wt% of hydrogen-absorbing nanographene and the balance is Sn; wherein the preparation method of the hydrogen-absorbing nanographene is as follows: hydrogen is introduced from the bottom of a container, an exhaust hole is provided at the top, and after the air in the container is exhausted, nanographene with a particle size of 5nm is placed on the bracket at the top of the container, and hydrogen is continuously introduced during the process, and the hydrogen flow rate is 50ml / min. After adsorption for 30min, hydrogen-absorbing nanographene with a particle size of 150nm is obtained.

[0083] The aluminum brazing plate prepared in this embodiment is subjected to only one continuous low-temperature rolling brazing and laminating process. Compared with the conventional method, the production efficiency is increased by about 8-10 times, and there is no problem of pore deficiency and local inability to laminarize in the prepared aluminum brazing plate. Figure 3 shown.

[0084] Example 2

[0085] Embodiment 2 is similar to Embodiment 1, except that:

[0086] In step S1, the thickness of the solder strip is 0.163 mm, and the composition of the solder strip is Al 88%, Si 12% by mass, and the thickness of the 3003 aluminum alloy strip is 1.78 mm;

[0087] In step S2, the speed at which the 3003 aluminum alloy strip passes through the flux liquid and the bonding metal liquid at a uniform speed is 25 mm / s;

[0088] The mass ratio of rosin, zinc borofluoride and alcohol in the flux liquid used is 7:2:4;

[0089] The bonding metal liquid used is 5wt% hydrogen-absorbing nanographene and the balance SnAgCu alloy (by mass percentage, the composition is Sn 96.5%, Ag 3%, Cu 0.5%), the thickness of a single bonding metal layer is 0.032mm, and the temperature of the bonding metal liquid is 290°C;

[0090] The rolling and welding temperature is 290°C, and the rolling reduction is 8% of the total thickness of the laminated strip, obtaining an aluminum brazing plate with a thickness of 2 mm.

[0091] The remaining process conditions are the same as those in Example 1.

[0092] The aluminum brazing plate prepared in this embodiment undergoes only one continuous low-temperature rolling brazing compounding process, and has high preparation efficiency. In addition, the prepared aluminum brazing plate does not have the problems of lack of pores and local inability to compound.

[0093] Example 3

[0094] Embodiment 3 is similar to Embodiment 1, except that:

[0095] In step S1, the thickness of the solder strip is 0.166 mm, and the composition of the solder strip is Al 92% and Si 8% by mass, and the thickness of the 3003 aluminum alloy strip is 1.867 mm;

[0096] In step S2, the 3003 aluminum alloy strip passes through the flux liquid and the bonding metal liquid at a uniform speed of 30 mm / s;

[0097] The mass ratio of rosin, zinc borofluoride and alcohol in the flux liquid used is 9:3:6;

[0098] The bonding metal liquid used is 6wt% of hydrogen-absorbing nanographene and the balance of SnAg alloy (by mass percentage, the composition is Sn 96.5%, Ag 3.5%), the thickness of a single bonding metal layer is 0.011mm, and the temperature of the bonding metal liquid is 300°C;

[0099] The rolling and welding temperature is 300°C, and the rolling reduction is 10% of the total thickness of the laminated strip, obtaining an aluminum brazing plate with a thickness of 2 mm.

[0100] The remaining process conditions are the same as those in Example 1.

[0101] The aluminum brazing plate prepared in this embodiment undergoes only one continuous low-temperature rolling brazing compounding process, and has high preparation efficiency. In addition, the prepared aluminum brazing plate does not have the problems of lack of pores and local inability to compound.

[0102] Comparative Example 1

[0103] Comparative Example 1: Aluminum brazing sheet was prepared by conventional method, and the specific steps were as follows:

[0104] Raw materials: 3003 alloy rectangular blocks with dimensions of 400mm×500mm×20mm, two pieces of solder skin rectangular blocks with dimensions of 400mm×500mm×1.6mm, the solder skin composition is the same as the solder strip composition in Example 1;

[0105] After the above three are stacked and fixed by resistance spot welding according to "brazing skin-3003 aluminum alloy-brazing skin", the total thickness is 23.2mm, the deformation of the first hot rolling must be 30%, the reduction is 7mm, and the total thickness after rolling and compounding is 16.2mm. From 16.2mm to the finished product thickness of 2mm, multiple hot rolling and cold rolling are required during the period, which requires about 10 rolling processes (16.2-14.5-12-10-8.0-6.0-5.5-4.5-3.5-2.8-2.0), and annealing is required in the middle (annealing temperature 490℃, each annealing takes about 40min), and it takes about 10h to roll to the finished product, which is extremely inefficient and requires 3 workers to complete the rolling.

[0106] The preparation process of the brazing plate in this comparative example is complicated and inefficient, and pores, delamination and cracking are easily generated on the bonding surface. Figure 4 As shown, the left picture shows that the aluminum brazing plate prepared in this comparative example has strings of pores, and the right picture shows that some positions of the aluminum brazing plate prepared in this comparative example cannot be composited, the bonding surface is torn, and there are inclusions and contamination at the joint surface.

[0107] Comparative Example 2

[0108] Comparative Example 2 is similar to Example 1, except that the bonding metal liquid does not contain hydrogen-absorbing nanographene, and the other conditions are the same as those of Example 1.

[0109] like Figure 5 As shown, since this comparative example does not contain hydrogen-absorbing nanographene, hydrogen will not be released during pressing and welding, and the oxidized inclusions cannot be removed, resulting in partial delamination and cracking of the prepared aluminum brazing plate.

[0110] Comparative Example 3

[0111] Comparative Example 3 is similar to Example 1, except that the nanographene used in the bonding metal liquid is not subjected to hydrogen absorption treatment, and the other conditions are the same as those in Example 1.

[0112] like Figure 6 As shown, in this comparative example, the nanographene was not subjected to hydrogen absorption treatment. During pressing and welding, as in comparative example 2, hydrogen was not released, and oxidation inclusions could not be removed. The prepared aluminum brazing plate had local delamination and poor welding.

[0113] Although the present invention has been illustrated and described with specific embodiments, it should be appreciated that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced by equivalents without departing from the spirit and scope of the present invention. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention. Therefore, this means that all such replacements and modifications within the scope of the present invention are included in the appended claims.

Claims

1. A method for preparing a brazing sheet, characterized in that: The following steps are involved: S1. Take two solder strips of the required size and a substrate strip of the required size; S2. The substrate strip is passed through the flux liquid and the bonding metal liquid at a uniform speed, and the substrate strip from the bonding metal liquid is overlapped with the two solder strips, the substrate strip is located between the two solder strips, and the overlapped strip is rolled and welded once and then coiled to obtain; The thickness ratio of the solder strip to the substrate strip is 0.08-0.22; The bonding metal liquid contains hydrogen-absorbing nanographene, and the mass percentage of the hydrogen-absorbing nanographene in the bonding metal liquid is 3%-6%. The hydrogen-absorbing nanographene is obtained by porous nanographene absorbing hydrogen, and specifically comprises the following steps: using hydrogen to discharge the air in the container, and then placing the nanographene in the container, continuously introducing hydrogen from the bottom of the container, exhausting the gas from the top, and the volume of the nanographene expanding during the hydrogen absorption process, and the volume can expand to 30-40 times of the original after being fully absorbed; The temperature of the bonding metal liquid is 280-300°C; The temperature of the rolling welding is 280-300°C; The reduction during the rolling and welding is 5%-10% of the total thickness of the strip after lamination.

2. The method for preparing a brazing sheet according to claim 1, characterized in that: Contains at least one of the following characteristics: (1) Before the lamination, the method further comprises the steps of polishing, cleaning and drying the solder strip; (2) The substrate strip is an aluminum alloy strip, and the aluminum alloy is any one of 3003 aluminum alloy, 6061 aluminum alloy, and 6063 aluminum alloy; (3) Before the substrate strip enters the flux liquid, the substrate strip is further polished, rinsed and dried; (4) The speed at which the substrate strip passes through the flux liquid and the bonding metal liquid is 20-30 mm / s.

3. The method for preparing a brazing sheet according to claim 1, characterized in that: The flux liquid comprises rosin, zinc fluoroborate and alcohol.

4. The method for preparing a brazing sheet according to claim 3, characterized in that: The mass ratio of the rosin, the zinc borate fluoride and the alcohol is 7-9:1-3:4-6.

5. The method for preparing a brazing sheet according to claim 1, characterized in that: The bonding metal liquid also contains at least one of Sn, Sn-Ag-Cu alloy and Sn-Ag alloy.

6. A brazing plate, characterized in that: The brazing plate is prepared by the method for preparing the brazing plate according to any one of claims 1 to 5.

Images