Brazing composite board and preparation method and application thereof

Abstract

The invention relates to the technical field of brazing materials, in particular to a brazing composite board and a preparation method and application thereof. The brazing composite board comprises a core material layer and brazing filler metal layers located on the two sides of the core material layer, the contact face of the core material layer and the brazing filler metal layers is in a concave arc shape with the thin center and the thick edge, the side, close to the core material layer, of each brazing filler metal layer is in a convex arc shape with the thick center and the thin edge, and the convex arcs on the brazing filler metal layers are matched with the concave arcs on the core material layer. And the brazing filler metal layer contains 1.5%-3% of La. The core material layer and the brazing filler metal layer of the brazing composite plate are of a concave arc and convex arc mutual inlaying structure, the design effect that the center brazing filler metal layer is thick and the edge brazing filler metal layer is thin is achieved, in the furnace welding process, the brazing filler metal layer with the thick center is smelted slowly, loss of brazing filler metal liquid in the center of a workpiece can be restrained or reduced, and the brazing quality is improved; and a gelatinization component La is added into the brazing filler metal layer, so that the overflowing of brazing filler metal liquid in the furnace welding process can be inhibited.

Description

Technical Field

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

[0002] The brazed composite plate is composed of a core base material substrate and a surface brazing layer, and is commonly used for furnace welding of radiators or sealed shielding boxes of various specifications and a complete set of assemblies.

[0003] At present, when the radiator is brazed, the brazing plate used is a layer of conventional brazing material pressed on the surface of the base material substrate, which can be either single-sided or double-sided. After the base material is cut and processed and assembled into a complete workpiece, the brazing flux is sprayed on the surface of the brazing plate, and it can be brazed in the furnace after drying. However, due to the large size of the large base station radiator (more than 1 meter long and more than 0.6 meters wide), the edge temperature of the workpiece is high and the center temperature is low when entering the furnace for welding, resulting in a large amount of brazing liquid on the surface of the composite plate to flow to the edge, resulting in less or no brazing liquid in the center of the workpiece, affecting the brazing quality of the radiator. In addition, the fluidity of the surface brazing material of the existing brazed composite plate is usually good. For example, the aluminum-silicon brazing material on the surface of the aluminum-brazed composite plate has serious overflow during brazing and is easy to block the flow channel. In addition, the joint strength of the existing brazed composite plate after brazing is low, and a layer of brazing flux needs to be sprayed before brazing for welding, which not only increases the process and affects the brazing efficiency, but also the sprayed brazing flux layer is easy to knock off during the subsequent manual assembly process, affecting the stability of the welding quality.

[0004] In order to solve the above-mentioned shortcomings, it is urgently necessary to develop a brazing composite plate for a radiator and a preparation method thereof to achieve high-reliability brazing of the radiator.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] The first object of the present invention is to provide a brazing composite plate to solve the technical problem that when brazing large-sized workpieces, the existing brazing composite plate has less or no brazing liquid in the center of the workpiece and the brazing liquid overflows seriously. The present invention improves the structure of the brazing composite plate, increases the amount of brazing material in the center of the brazing composite plate, and adds a gelatinized component La to the brazing material layer, thereby suppressing the brazing material overflow.

[0007] The second object of the present invention is to provide a method for preparing the brazing composite plate as described above. The preparation process of the present invention is simple and easy to operate.

[0008] The third object of the present invention is to provide a brazing composite plate as described above or a brazing composite plate prepared by the method for preparing the brazing composite plate as described above for use in radiator brazing.

[0009] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0010] A brazing composite plate comprises a core material layer and brazing filler metal layers on both sides of the core material layer, wherein the contact surface between the core material layer and the brazing filler metal layer is in a concave arc shape with a thin center and thick edges, and the side of the brazing filler metal layer adjacent to the core material layer is in a convex arc shape with a thick center and thin edges, the convex arc on the brazing filler metal layer is matched with the concave arc on the core material layer, and the brazing filler metal layer contains 1.5%-3% La by mass percentage.

[0011] A method for preparing the brazed composite plate as described above comprises the following steps:

[0012] S1. Take a core substrate and a brazing material metal plate of the required size and specifications, and process concave arcs on both sides of the core substrate. The brazing material metal plate contains La, and a convex arc is processed on one side of the brazing material metal plate to match the concave arc;

[0013] S2. stacking two processed brazing metal plates and one processed core substrate together, so that the core substrate is located between the two brazing metal plates, and the convex arc on the brazing metal plate is embedded in the concave arc on the core substrate, and fixed as a whole by spot welding to obtain a metal composite block;

[0014] S3. The metal composite block is subjected to multiple hot rolling and cutting to obtain a brazing composite plate.

[0015] Application of the brazing composite plate as described above or the brazing composite plate prepared by the method for preparing the brazing composite plate as described above in radiator brazing.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] (1) The core material layer and the brazing material layer of the brazed composite plate provided by the present invention are in a structure in which concave and convex arcs are inlaid with each other, thereby achieving a design effect in which the central brazing material layer is thick and the edge brazing material layer is thin. During the furnace welding process, the thicker central brazing material layer melts slowly and has a large amount of material, which can inhibit or reduce the loss of brazing material liquid at the center of the workpiece to a certain extent, thereby improving the brazing quality.

[0018] (2) The solder layer of the present invention contains the highly active element La, which can easily form lanthanum oxide with a high specific gravity and disperse in the solder liquid, thereby increasing the viscosity of the solder liquid and inhibiting the solder liquid from flowing. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] 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.

[0020] Figure 1 A schematic diagram of the structure of a brazed composite plate provided in an embodiment of the present invention;

[0021] Figure 2 A schematic diagram of the processing process of a concave arc and a convex arc provided in an embodiment of the present invention;

[0022] Figure 3 A schematic diagram of the final rolling process of a brazed composite plate provided in an embodiment of the present invention;

[0023] Figure 4 The morphology comparison diagram of the central position of the brazing composite plate brazing parts in different embodiments and comparative examples of the present invention is shown in Figure 1, wherein A is the sample of comparative example 3, B is the sample of embodiment 1, and C is the sample of comparative example 5;

[0024] Figure 5 This is a solder flow morphology diagram of the surface of the die-cast aluminum alloy brazed by the brazed composite plate in Comparative Example 2 of the present invention;

[0025] Figure 6 This is a surface morphology of the die-cast aluminum alloy brazed with the brazed composite plate in Comparative Example 4 of the present invention.

[0026] Reference numerals:

[0027] 1- solder layer; 2- core material layer; 3- flux layer; 4- concave arc brush; 5- handle; 6- convex arc scraper; 7- motor. DETAILED DESCRIPTION

[0028] 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 understood 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 are within the scope of protection of the present invention. If specific conditions are not specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0029] like Figure 1As shown, the first aspect of the present invention provides a brazing composite plate, comprising a core material layer 2 and a brazing material layer 1 located on both sides of the core material layer 2, the contact surface between the core material layer 2 and the brazing material layer 1 is in a concave arc shape with a thin center and thick edges, and the side of the brazing material layer 1 adjacent to the core material layer 2 is in a convex arc shape with a thick center and thin edges, the convex arc on the brazing material layer 1 is matched with the concave arc on the core material layer 2, and the brazing material layer 1 contains 1.5%-3% La by mass.

[0030] The present invention designs the core material layer 2 and the solder layer 1 of the brazed composite plate into a complex structure with concave and convex arcs embedded in each other, achieving a design effect of thicker central solder and thinner edge solder layer. During the furnace welding process, the central solder layer is thicker and requires more melting heat. Even if the solder liquid is lost, part of the solder will be retained, which can inhibit or reduce the loss of solder liquid at the center of the workpiece to a certain extent and improve the brazing quality. The present invention also adds a highly active rare earth element La to the solder layer to make the solder liquid paste-like. La is easily oxidized to form lanthanum oxide (density 6.51g / cm 3 ), the density is much greater than the density of the solder liquid (about 2.7g / cm 3 ), will be dispersed in the solder liquid in large quantities, thereby increasing the viscosity of the solder liquid, inhibiting the overflow of the solder liquid, reducing the loss of the solder liquid, and avoiding blockage of the flow channel.

[0031] If the La content in the solder layer is too low, the diffusion inhibition effect will be poor. If the La content is too high, the viscosity of the solder liquid will be too high and the fluidity of the solder will be too poor, which will affect the brazing effect. Therefore, the La content in the solder layer needs to be reasonably controlled. In some embodiments, typically but not restrictively, for example, the mass percentage of La in the solder layer can be any point value among 1.5%, 2%, 2.5%, 3%, or a range value composed of any two point values.

[0032] In some specific embodiments of the present invention, the thickness of the single-sided solder layer 1 at the center accounts for 10%-12% of the total thickness of the brazed composite plate, for example, it can be any point value among 10%, 10.5%, 11%, 11.5%, 12% or a range value consisting of any two point values; the thickness of the edge of the single-sided solder layer 1 accounts for 5%-8% of the total thickness of the brazed composite plate, for example, it can be any point value among 5%, 6%, 7%, 8% or a range value consisting of any two point values; and there is an arc transition between the edge and the center.

[0033] Controlling the convex arc size of the solder layer within the above range can achieve better brazing effect. If the center thickness is too small and the edge thickness is too large, it will be difficult to inhibit the loss of solder liquid in the center. On the contrary, if the center thickness is too large and the edge thickness is too small, it will lead to excessive solder in the center and weld nodules. After the concave arc of the core material layer is filled with solder liquid, excess solder liquid will flow to the periphery, causing serious overflow and affecting the brazing effect.

[0034] In some specific embodiments of the present invention, the brazing material layer 1 also contains 1%-2% Zr by mass percentage. For example, the mass percentage of Zr can be any value among 1%, 1.2%, 1.5%, 1.8%, 2%, or a range consisting of any two values. Zr can form a large amount of Al in the alloy. 3 Zr and ZrSi phases are dispersed in the matrix, playing a role of solid solution strengthening and aging strengthening, improving the strength of the brazed joint of the brazed composite plate; if the Zr content is too low, the strengthening effect is not good, and if the Zr content is too high, the material brittleness will increase and the processing performance will decrease.

[0035] In some specific embodiments of the present invention, the core material layer 2 is an aluminum alloy core material, for example, it can be any one of 3003 alloy, 6061 alloy or 6063 alloy; the brazing material layer 1 contains the following components by mass: 8.0-10 parts of Si, 1.5-3.0 parts of La, 1.0-2.0 parts of Zr, and 80-90 parts of Al. For the aluminum alloy core material, an aluminum silicon-based brazing material suitable for aluminum alloy brazing is selected, and the pasting element La and the strengthening element Zr are added to inhibit the overflow of the brazing material during furnace welding and improve the strength of the brazing joint; the brazing plate is suitable for the brazing of die-cast aluminum alloy radiators. In other embodiments, the core material and brazing material composition of other materials can also be selected according to the different materials of the brazed workpieces. For example, for a stainless steel radiator, a stainless steel core material can be used.

[0036] In some embodiments, typically but not limiting, for example, in the solder layer 1, the mass fraction of Si can be any point value among 8.0 parts, 8.5 parts, 9 parts, 9.5 parts, 10 parts, or a range value consisting of any two point values; the mass fraction of La can be any point value among 1.5 parts, 2.0 parts, 2.5 parts, 3.0 parts, or a range value consisting of any two point values; the mass fraction of Zr can be any point value among 1.0 parts, 1.2 parts, 1.5 parts, 1.8 parts, 2.0 parts, or a range value consisting of any two point values; the mass fraction of Al can be any point value among 80 parts, 82.5 parts, 85 parts, 87.5 parts, 90 parts, or a range value consisting of any two point values.

[0037] In some specific embodiments of the present invention, a brazing agent layer 3 is provided on one side of the brazing material layer 1 away from the core material layer 2. The brazing agent layer is integrated with the composite plate and is not easily knocked off, thus eliminating the process of spraying the brazing agent during furnace welding and improving the brazing efficiency.

[0038] In some specific embodiments of the present invention, the components of the flux layer used include potassium fluoroaluminate, cesium fluoroaluminate and potassium fluoroborate.

[0039] In some specific embodiments of the present invention, the mass ratio of potassium fluoroaluminate, cesium fluoroaluminate and potassium fluoroborate in the flux layer used is 10:1-3:0.5-1. For example, it can be any point value among 10:1:0.5, 10:1:0.8, 10:1:1, 10:2:0.5, 10:2:0.8, 10:2:1, 10:3:0.5, 10:3:0.8, 10:3:1, or a range value consisting of any two point values.

[0040] In some specific embodiments of the present invention, a plurality of grooves are evenly distributed on the surface of the solder layer 1 away from the core material layer 2, and the solder forming the solder layer 3 is located in the grooves. The purpose of providing the grooves is, first, to accommodate the solder, and second, to roughen the surface of the solder layer 1, increase the contact area between the solder layer 1 and the solder, increase the bonding force between the solder layer 1 and the solder layer 3, and prevent the solder layer 3 from falling off.

[0041] In some specific embodiments of the present invention, the groove depth on the surface of the solder layer 1 is 30-50μm, for example, it can be any point value among 30μm, 35μm, 40μm, 45μm, 50μm, or a range value consisting of any two point values; the spacing between two adjacent grooves is 3-8mm, for example, it can be any point value among 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, or a range value consisting of any two point values.

[0042] A second aspect of the present invention provides a method for preparing the brazed composite plate as described above, comprising the following steps:

[0043] S1. Take the core substrate and the brazing material metal plate of the required size, and process the concave arcs on both sides of the core substrate. The brazing material metal plate contains La, and a convex arc is processed on one side of the brazing material metal plate to match the concave arc on the core substrate;

[0044] S2. Lay two processed brazing metal plates and a processed core substrate together in the order of "brazing metal plate-core substrate-brazing metal plate", so that the core substrate is located between the two brazing metal plates, and the convex arc on the brazing metal plate is embedded in the concave arc on the core substrate, and fixed as a whole by spot welding to obtain a metal composite block;

[0045] S3. The metal composite block obtained in step S2 is subjected to multiple hot rolling and cutting to obtain a brazing composite plate.

[0046] The method of the present invention has a simple preparation process and is easy to operate. Concave arcs are processed on both side surfaces of the core material substrate, and a convex arc matching the concave arc is processed on one side surface of the brazing metal plate. During the assembly process, the convex arc on the brazing metal plate is embedded in the concave arc of the core material substrate. After hot rolling, a brazing composite plate with a thick core brazing layer and a thin edge brazing layer can be obtained. This structure can inhibit or reduce the loss of brazing liquid at the center of the workpiece. The used brazing metal plate contains a pasting component La, which can increase the viscosity of the brazing liquid and inhibit the overflow of the brazing liquid. The two work together to improve the brazing quality of the workpiece.

[0047] In some specific embodiments of the present invention, the thickness at the center of any solder metal plate with a convex arc accounts for 10%-12% of the total thickness of the metal composite block, for example, it can be any point value among 10%, 10.5%, 11%, 11.5%, 12% or a range value consisting of any two point values; the thickness at the edge of any solder metal plate with a convex arc accounts for 5%-8% of the total thickness of the metal composite block, for example, it can be any point value among 5%, 6%, 7%, 8% or a range value consisting of any two point values; and there is an arc transition between the edge and the center of the convex arc of the solder metal plate.

[0048] In some specific embodiments of the present invention, the brazing metal plate used in step S1 can be obtained by purchase or processing. In some embodiments, the processing method of the brazing metal plate used includes: weighing raw materials by mass, obtaining brazing metal foil of the required initial thickness through smelting, casting, and rolling, and cutting into brazing metal plates with the same length and width as the core substrate. The initial thickness of the brazing metal plate can be calculated based on the size of the core substrate and the ratio of the core thickness and edge thickness of the brazing layer to the total thickness of the entire brazed composite plate.

[0049] In some specific embodiments of the present invention, the core substrate is an aluminum alloy plate, such as any one of a 3003 alloy plate, a 6061 alloy plate or a 6063 alloy plate; the raw materials of the brazing metal plate include Al-20Si, Al-10La, Al-5Zr and Al.

[0050] like Figure 3 As shown, in some specific embodiments of the present invention, step S3 also includes the following steps:

[0051] Before the last hot rolling, the brazed composite plate is roughened by upper and lower wire brush rollers to form uniform grooves on its surface. The roughened composite plate passes through the semi-molten brazing flux liquid.

[0052] The purpose of roughening the surface of the composite plate to form grooves in the present invention is to increase the contact area between the solder layer on the surface of the composite plate and the solder liquid, and to increase the adhesion between the solder layer and the solder liquid. The purpose of controlling the solder liquid to be in a semi-molten state is to increase the viscosity of the solder liquid, and further increase the adhesion between the solder liquid and the solder layer. The solder liquid is filled in the grooves on the surface of the solder layer, and the solder liquid is not easy to fall off during the last hot rolling.

[0053] In some specific embodiments of the present invention, the speed at which the composite plate passes through the flux liquid is 5-10 mm / s, for example, it can be any point value among 5 mm / s, 6 mm / s, 7 mm / s, 8 mm / s, 9 mm / s, 10 mm / s or a range value consisting of any two point values.

[0054] In some specific embodiments of the present invention, the flux liquid used includes potassium fluoroaluminate, cesium fluoroaluminate and potassium fluoroborate, and the temperature of the flux liquid is 480-520°C, for example, it can be any point value among 480°C, 490°C, 500°C, 510°C, 520°C or a range value consisting of any two point values. The purpose of controlling the temperature is to make the flux in a semi-molten state. In other embodiments, other fluxes can also be selected, and for different fluxes, the temperature at which they are in a semi-molten state is also different.

[0055] like Figure 2 As shown, in some specific embodiments of the present invention, the concave arc on the core substrate is machined by a convex arc scraper 6, and the convex arc scraper 6 matches the concave arc on the core substrate. The specific steps include: installing the convex arc scraper 6 on a planer, starting the motor 7, driving the convex arc scraper 6 to rotate, and processing the concave arcs on the upper and lower surfaces of the core substrate respectively.

[0056] In some specific embodiments of the present invention, the method for preparing the convex arc on the brazing filler metal plate comprises the following steps:

[0057] The solder metal plate is fixed on the platform, and the etching liquid is dipped into the concave arc brush 4 and placed on the surface of the solder metal plate. The handle 5 is rotated to brush and etch the solder metal plate for multiple times until the size requirement is met. After washing, the solder metal plate with a convex arc on one side is obtained; wherein the concave arc brush 4 matches the convex arc on the solder metal plate, and the washing includes at least one of acid washing, water washing, and alcohol washing.

[0058] In some specific embodiments of the present invention, the etching solution used includes at least one of a sodium hydroxide aqueous solution, a potassium hydroxide aqueous solution or a sodium bicarbonate aqueous solution.

[0059] In some specific embodiments of the present invention, the mass concentration of the etching solution used is 3%-10%, for example, it can be any point value among 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or a range value consisting of any two point values.

[0060] The third aspect of the present invention provides an application of a brazing composite plate according to any one of the aforementioned embodiments or a brazing composite plate prepared by the method for preparing a brazing composite plate according to any one of the aforementioned embodiments in radiator brazing. For example, the aluminum brazing composite plate can be used for brazing of a die-cast aluminum alloy radiator.

[0061] The embodiments of the present invention will be described in detail below in conjunction with the examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present invention and should not be considered as limiting the scope of the present invention. If no specific conditions are specified in the examples, the conditions are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be obtained commercially.

[0062] Example 1

[0063] This embodiment provides a brazing composite plate, which is a five-layer plate structure, including a core material layer, a brazing material layer located on both sides of the core material layer, and a brazing flux layer located outside the brazing material layer; the core material layer is 3003 alloy;

[0064] The core material layer is thick at the edge and thin at the center, and the upper and lower surfaces are in the shape of concave arcs. The solder layer is thick at the center and thin at the edge on the side adjacent to the core material layer, and is in the shape of a convex arc. The convex arc of the solder layer is completely embedded with the concave arc of the core material layer.

[0065] The flux layer is composed of potassium fluoroaluminate, cesium fluoroaluminate and potassium fluoroborate, and the mass ratio of potassium fluoroaluminate, cesium fluoroaluminate and potassium fluoroborate is 10:1:0.5;

[0066] The mass fractions of each element in the brazing material layer are as follows: 89.5 parts of Al, 8.0 parts of Si, 1.5 parts of La, and 1.0 parts of Zr;

[0067] The thickness of the single-sided solder layer at the center accounts for 10% of the total thickness of the entire brazed composite plate; the thickness of the single-sided solder layer at the edge accounts for 5% of the total thickness of the entire brazed composite plate, and there is an arc transition between the edge and the center.

[0068] The preparation method comprises the following steps:

[0069] S1. Given the size of the 3003 alloy plate as 400×400×20mm, the thickness of the edge of the single-sided solder layer accounts for 5% of the thickness of the entire composite plate, and the required thickness of the edge of the solder metal plate is calculated to be 1.11mm. According to the thickness of the center of the single-sided solder layer accounts for 10% of the thickness of the composite plate, the required thickness of the core of the solder metal plate is calculated to be 1.11mm+1.11mm=2.22mm (i.e., the initial thickness of the solder plate); weigh the solder raw materials Al-20Si, Al-10La, Al-5Zr, and Al by mass, and obtain a solder foil with a thickness of 2.22mm through smelting, casting, and rolling, and cut it into solder metal plates of 400×400×2.22mm;

[0070] Take a 3003 alloy plate of a given size, fix it on a workbench, install a convex arc scraper on a planer, and process concave arc surfaces on the upper and lower surfaces of the 3003 alloy plate, respectively, so that the thickness at the center of the 3003 alloy plate is 20-1.11×2=17.78mm;

[0071] Two cut brazing metal plates are fixed on the platform respectively, and a concave arc coarse brush is dipped in a 5% NaOH aqueous solution to rotate and brush and etch the brazing metal plates for many times until the thickness of the edge of the brazing metal plate is 1.11 mm. After pickling, water washing and alcohol cleaning, two brazing metal plates with convex arcs are obtained;

[0072] S2. The two brazing metal plates processed in step S1 are superimposed on the 3003 alloy plate in the order of "brazing metal plate-3003 alloy plate-brazing metal plate", and the convex arc of the brazing metal plate is embedded in the concave arc of the 3003 alloy plate, and the spot welding machine is used to fix them as a whole to obtain a metal composite block;

[0073] S3. The metal composite block obtained in step S2 is subjected to multiple hot rolling passes. Before the last rolling pass, it is roughened by upper and lower wire brush rollers to form uniform grooves with a groove depth of about 30 μm and a spacing of about 3 mm. The roughened composite plate is passed through a semi-molten flux liquid (480°C) at a speed of 5 mm / s, and after the last hot rolling and cutting, a brazing composite plate with a five-layer structure is obtained.

[0074] Example 2

[0075] This embodiment provides a brazing composite plate, which is a five-layer plate structure, including a core material layer, a brazing material layer located on both sides of the core material layer, and a brazing flux layer located outside the brazing material layer; the core material layer is 3003 alloy;

[0076] The core material layer is thick at the edge and thin at the center, and the upper and lower surfaces are in the shape of concave arcs. The solder layer is thick at the center and thin at the edge on the side adjacent to the core material layer, and is in the shape of a convex arc. The convex arc of the solder layer is completely embedded with the concave arc of the core material layer.

[0077] The flux layer is composed of potassium fluoroaluminate, cesium fluoroaluminate and potassium fluoroborate, and the mass ratio of potassium fluoroaluminate, cesium fluoroaluminate and potassium fluoroborate is 10:2:0.8;

[0078] The mass fractions of each element in the brazing material layer are as follows: Al 88.5 parts, Si 8.5 parts, La 1.8 parts, Zr 1.2 parts;

[0079] The thickness of the single-sided solder layer at the center accounts for 12% of the total thickness of the entire brazed composite plate; the thickness of the single-sided solder layer at the edge accounts for 8% of the total thickness of the entire brazed composite plate, and there is an arc transition between the edge and the center.

[0080] The preparation method is similar to that of Example 1, except that:

[0081] In step S1, given that the size of the 3003 alloy plate is 400×400×20 mm, the thickness of the edge of the single-sided brazing material layer accounts for 8% of the thickness of the entire composite plate, and the required thickness of the edge of the brazing material metal plate is calculated to be 1.9 mm. According to the thickness of the center of the single-sided brazing material layer accounting for 12% of the thickness of the composite plate, the required thickness of the core of the brazing material metal plate is calculated to be 2.856 mm (i.e., the initial thickness of the brazing material plate); the initial size of the brazing material metal plate is 400×400×2.856 mm;

[0082] The thickness of the 3003 alloy plate at the center after processing the concave arc is 20-0.956×2=18.088mm;

[0083] The thickness of the brazing metal plate at the edge after processing the convex arc is 1.9mm;

[0084] In step S3, the groove depth after roughening is about 40 μm, and the spacing is about 5 mm; the speed of the roughened composite plate passing through the flux liquid is 8 mm / s; the temperature of the flux liquid is 500° C.;

[0085] The remaining process conditions are the same as those in Example 1.

[0086] Example 3

[0087] This embodiment provides a brazing composite plate, which is a five-layer plate structure, including a core material layer, a brazing material layer located on both sides of the core material layer, and a brazing flux layer located outside the brazing material layer; the core material layer is 3003 alloy;

[0088] The core material layer is thick at the edge and thin at the center, and the upper and lower surfaces are in the shape of concave arcs. The solder layer is thick at the center and thin at the edge on the side adjacent to the core material layer, and is in the shape of a convex arc. The convex arc of the solder layer is completely embedded with the concave arc of the core material layer.

[0089] The flux layer is composed of potassium fluoroaluminate, cesium fluoroaluminate and potassium fluoroborate, and the mass ratio of potassium fluoroaluminate, cesium fluoroaluminate and potassium fluoroborate is 10:3:1;

[0090] The mass fractions of each element in the brazing material layer are as follows: 87.5 parts of Al, 9 parts of Si, 2.0 parts of La, and 1.5 parts of Zr.

[0091] The thickness of the single-sided solder layer at the center accounts for 10% of the total thickness of the entire brazed composite plate; the thickness of the single-sided solder layer at the edge accounts for 5% of the total thickness of the entire brazed composite plate, and there is an arc transition between the edge and the center.

[0092] The preparation method is similar to that of Example 1, except that:

[0093] In step S3, the depth of the roughened grooves is about 50 μm, and the spacing is about 8 mm; the speed at which the roughened composite plate passes through the flux liquid is 10 mm / s; and the temperature of the flux liquid is 520° C.;

[0094] The remaining process conditions are the same as those in Example 1.

[0095] Example 4

[0096] This embodiment provides a brazing composite plate, which is a five-layer plate structure, including a core material layer, a brazing material layer located on both sides of the core material layer, and a brazing flux layer located outside the brazing material layer; the core material layer is 3003 alloy;

[0097] The core material layer is thick at the edge and thin at the center, and the upper and lower surfaces are in the shape of concave arcs. The solder layer is thick at the center and thin at the edge on the side adjacent to the core material layer, and is in the shape of a convex arc. The convex arc of the solder layer is completely embedded with the concave arc of the core material layer.

[0098] The flux layer is composed of potassium fluoroaluminate, cesium fluoroaluminate and potassium fluoroborate, and the mass ratio of potassium fluoroaluminate, cesium fluoroaluminate and potassium fluoroborate is 10:1:0.5;

[0099] The mass fractions of each element in the brazing material layer are as follows: 85 parts of Al, 10 parts of Si, 3.0 parts of La, and 2.0 parts of Zr.

[0100] The thickness of the single-sided solder layer at the center accounts for 10% of the total thickness of the entire brazed composite plate; the thickness of the single-sided solder layer at the edge accounts for 5% of the total thickness of the entire brazed composite plate, and there is an arc transition between the edge and the center.

[0101] The preparation method is similar to that of Example 1, except that:

[0102] In step S3, the depth of the roughened grooves is about 50 μm, and the spacing is about 8 mm; the speed at which the roughened composite plate passes through the flux liquid is 10 mm / s; and the temperature of the flux liquid is 520° C.;

[0103] The remaining process conditions are the same as those in Example 1.

[0104] Example 5

[0105] This embodiment provides a brazing composite plate, which is a five-layer plate structure, including a core material layer, a brazing material layer located on both sides of the core material layer, and a brazing flux layer located outside the brazing material layer; the core material layer is 3003 alloy;

[0106] The core material layer is thick at the edge and thin at the center, and the upper and lower surfaces are in the shape of concave arcs. The solder layer is thick at the center and thin at the edge on the side adjacent to the core material layer, and is in the shape of a convex arc. The convex arc of the solder layer is completely embedded with the concave arc of the core material layer.

[0107] The flux layer is composed of potassium fluoroaluminate, cesium fluoroaluminate and potassium fluoroborate, and the mass ratio of potassium fluoroaluminate, cesium fluoroaluminate and potassium fluoroborate is 10:2:0.8;

[0108] The mass fractions of each element in the brazing material layer are as follows: 85 parts of Al, 10 parts of Si, 3.0 parts of La, and 2.0 parts of Zr.

[0109] The thickness of the single-sided solder layer at the center accounts for 10% of the total thickness of the entire brazed composite plate; the thickness of the single-sided solder layer at the edge accounts for 5% of the total thickness of the entire brazed composite plate, and there is an arc transition between the edge and the center.

[0110] The preparation method is similar to that of Example 1, except that:

[0111] In step S3, the depth of the roughened grooves is about 50 μm, and the spacing is about 8 mm; the speed at which the roughened composite plate passes through the flux liquid is 10 mm / s; and the temperature of the flux liquid is 520° C.;

[0112] The remaining process conditions are the same as those in Example 1.

[0113] Example 6

[0114] Example 6 is similar to Example 1, with the only difference being that the solder layer does not contain Zr, and the other conditions are the same as those of Example 1.

[0115] Example 7

[0116] Example 7 is similar to Example 1, except that it does not contain a flux layer, and the other conditions are the same as those of Example 1.

[0117] Comparative Example 1

[0118] Comparative Example 1 is similar to Example 1, except that the mass percentage of La in the solder layer is 1%, and the other conditions are the same as those in Example 1.

[0119] Comparative Example 2

[0120] Comparative Example 2 is similar to Example 1, except that the solder layer does not contain La, and the other conditions are the same as those of Example 1.

[0121] Comparative Example 3

[0122] Comparative Example 3 is similar to Example 1, except that the 3003 core material layer and the solder layer are not embedded with concave and convex arcs, but with a conventional planar structure. The thickness of the solder layer accounts for 10% of the total thickness of the composite plate. The other conditions are the same as Example 1.

[0123] Comparative Example 4

[0124] Comparative Example 4 is similar to Example 1, with the only difference being that a convex-concave arc embedded structure is provided between the 3003 core material layer and the solder layer, that is, convex arcs are provided on both side surfaces of the core material layer, and concave arcs are provided on the surface of the solder layer adjacent to the core material layer. The solder layer is thin in the center (the thickness on one side is 5% of the total thickness of the composite board) and thick at the edge (the thickness on one side is 10% of the total thickness of the composite board). The other conditions are the same as those in Example 1.

[0125] Comparative Example 5

[0126] Comparative Example 5 is similar to Example 1, except that the thickness of the single-sided solder layer at the center accounts for 15% of the total thickness of the composite plate, the thickness of the single-sided solder layer at the edge accounts for 3% of the total thickness of the composite plate, and the other conditions are the same as Example 1.

[0127] Test example

[0128] In order to investigate and compare the joint strength and flow characteristics of the brazed radiator brazed with the brazed composite plate in each embodiment of the present invention and each comparative example (tunnel furnace brazing, brazing furnace temperature 615°C, chain speed 300mm / min), the brazed composite plates in each embodiment and each comparative example were respectively used for furnace brazing of the die-cast aluminum alloy radiator, and one sample was welded for each composite plate. The shear strength of the joint was tested according to the method of standard GB / T11363-2008, and the degree of brazing filler metal flow on the surface of the die-cast aluminum alloy and whether there was brazing filler metal at the center of the radiator were observed. The results are shown in Table 1.

[0129] Table 1

[0130]

[0131]

[0132] It can be seen from the data in Table 1 that when the brazing composite plate is brazed to the die-cast aluminum alloy heat exchanger in the embodiment of the present invention, there is no overflow of the brazing filler metal, and there is brazing filler metal at the center of the workpiece, the brazing strength is high, and the brazing quality is good. It can be seen from the comparative examples of Example 1 and Example 6 that adding Zr element to the brazing filler metal layer can improve the shear strength of the joint; Comparative Example 2 does not contain the gelatinized component La, the brazing filler metal overflows seriously, there is brazing filler metal at the center, but the amount of brazing filler metal is small, and the shear strength of the joint is low; the gelatinized component La content in Comparative Example 1 is low, there is slight overflow, and the joint strength is higher than that of Comparative Example 2, but lower than that of the embodiment; Comparative Example 3 has a core The material layer and the solder layer are flat-plate-shaped. Compared with the embodiment, there is less solder at the center, and there is no solder in some areas of the center after brazing, which will reduce the quality of brazing. In comparative example 4, the core material layer and the solder layer are inlaid with convex and concave arcs. There is less solder at the center, and the convex arc on the core material layer makes it easier for the solder liquid to flow to the edge, resulting in most of the center of the workpiece having no solder. In comparative example 5, the depth of the concave arc on the core material layer is too large, and the center of the solder layer is too thick, resulting in too much solder at the center and a weld nodule. Moreover, due to the excessive amount of solder, the excess solder liquid will flow to the edge after the concave arc of the core is filled, resulting in serious overflow.

[0133] During the brazing process, since the brazed composite plates in Examples 1-6 contain a brazing flux layer, there is no need to spray the brazing flux, and the workpieces can be directly assembled for welding; the brazed composite plates in Example 7 need to be pre-sprayed with a uniform layer of brazing flux and dried before assembly and welding. Compared with Example 7, the composite plates containing the brazing flux layer in Examples 1-6 omit the brazing flux spraying and drying steps, and the brazing time of each workpiece can be saved by 20-30 minutes. The brazing flux layer is provided on the brazed composite plate, which improves the brazing efficiency.

[0134] like Figure 4 As shown, the surface of the central sample B in Example 1 has a layer of solder (bright metal), that is, there is solder at the center; the surface of the central sample A in the comparative example 3 is relatively smooth (at the red arrow), and is still the original color of die-cast aluminum, with almost no solder layer; the surface of the central sample C in the comparative example 5 has serious solder accumulation, forming a weld nodule, which affects the welding effect.

[0135] like Figure 5 As shown, in Comparative Example 2, the surface of the die-cast aluminum brazed with the brazed composite plate has serious brazing filler metal overflow, and a river-like overflowing brazing filler metal is formed around each boss.

[0136] like Figure 6 As shown, in Comparative Example 4, there is no brazing filler metal in most areas of the die-cast aluminum surface at the center of the brazing sample of the brazed composite plate.

[0137] 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 brazed composite plate, characterized in that: It includes a core material layer and solder layers located on both sides of the core material layer, the contact surface between the core material layer and the solder layer is in a concave arc shape, the side of the solder layer adjacent to the core material layer is in a convex arc shape, the convex arc on the solder layer is matched with the concave arc on the core material layer, and the solder layer contains 1.5%-3% La by mass percentage.

2. The brazed composite plate according to claim 1, characterized in that: Meet at least one of the following characteristics: (1) The thickness of the solder layer at the center on one side accounts for 10%-12% of the total thickness of the brazed composite plate, and the thickness of the edge of the solder layer on one side accounts for 5%-8% of the total thickness of the brazed composite plate, and there is an arc transition between the edge and the center; (2) The solder layer further contains 1% to 2% Zr by mass percentage; (3) The core material layer is an aluminum alloy core material, and the brazing material layer comprises the following components by mass: 8.0-10 parts of Si, 1.5-3.0 parts of La, 1.0-2.0 parts of Zr, and 80-90 parts of Al.

3. The brazed composite plate according to claim 1, characterized in that: A flux layer is provided on a side of the brazing material layer away from the core material layer.

4. The brazed composite plate according to claim 3, characterized in that: A plurality of grooves are evenly distributed on a surface of the brazing material layer on one side away from the core material layer, and the brazing agent forming the brazing agent layer is located in the grooves.

5. The method for preparing a brazed composite plate according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1. Take a core substrate and a brazing material metal plate of the required size and specifications, and process concave arcs on both sides of the core substrate. The brazing material metal plate contains La, and a convex arc is processed on one side of the brazing material metal plate to match the concave arc; S2. stacking two processed brazing metal plates and one processed core substrate together, so that the core substrate is located between the two brazing metal plates, and the convex arc on the brazing metal plate is embedded in the concave arc on the core substrate, and fixed as a whole by spot welding to obtain a metal composite block; S3. The metal composite block is subjected to multiple hot rolling and cutting to obtain a brazing composite plate.

6. The method for preparing a brazed composite plate according to claim 5, characterized in that: Step S3 also includes the following steps: The brazing composite plate is also subjected to a roughening treatment before the last hot rolling, and uniform grooves are processed on its surface. The composite plate after the roughening treatment passes through the semi-molten brazing agent liquid.

7. The method for preparing a brazed composite plate according to claim 6, characterized in that: The speed at which the composite plate passes through the flux liquid is 5-10 mm / s; And / or, the flux liquid comprises potassium fluoroaluminate, cesium fluoroaluminate and potassium fluoroborate, and the temperature of the flux liquid is 480-520°C.

8. The method for preparing a brazed composite plate according to claim 6, characterized in that: The method for preparing the convex arc on the solder metal plate comprises the following steps: The brazing material metal plate is fixed, and an etching solution is dipped into a concave arc brush to brush and etch the brazing material metal plate for multiple times until the size requirement is met, and the plate is then washed to obtain the brazing material metal plate.

9. The method for preparing a brazed composite plate according to claim 8, characterized in that: The etching solution includes at least one of a sodium hydroxide aqueous solution, a potassium hydroxide aqueous solution or a sodium bicarbonate aqueous solution; And / or, the mass concentration of the etching solution is 3%-10%.

10. Use of the brazing composite plate according to any one of claims 1 to 4 or the brazing composite plate prepared by the method for preparing the brazing composite plate according to any one of claims 5 to 9 in radiator brazing.

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