Foil-shaped brazing filler metal for copper-steel brazing, preparation method of foil-shaped brazing filler metal and copper-steel dissimilar metal joint

Abstract

The invention relates to the technical field of brazing materials, in particular to foil-shaped brazing filler metal for copper-steel brazing, a preparation method of the foil-shaped brazing filler metal and a copper-steel dissimilar metal joint. The foil-shaped brazing filler metal comprises copper-based brazing filler metal and a metal net-shaped framework embedded in the copper-based brazing filler metal, and the metal net-shaped framework is formed by weaving nickel wires and nickel-plated tungsten wires. The foil-shaped brazing filler metal is prepared from, by mass, 15.26%-22.89% of Ni, 3.3%-9.62% of W, 3.5%-8% of Ag, 2.8%-4.8% of Mn, 1.4%-4% of Zn, 1.05%-1.6% of Si and the balance Cu. A layer of brazing filler metal brazing flux paste is uniformly pressed and coated on the surface of the metal net-shaped framework, brazing filler metal foil is obtained through ultrasonic frequency induction cladding after preheating, and then the foil-shaped brazing filler metal embedded with the metal net-shaped framework is obtained through polishing and shaping. The brazing filler metal foil can achieve low-temperature welding of a copper-steel connector, and the obtained connector is high in strength and good in high-temperature resistance.

Description

Technical Field

[0001] This invention relates to the field of brazing materials technology, and more specifically, to a foil-shaped brazing filler metal for copper-steel brazing, its preparation method, and a copper-steel dissimilar metal joint. Background Technology

[0002] Copper-steel dissimilar metal joints have been widely used in weaponry, energy, aerospace, nuclear industry and general industrial fields due to their excellent high-temperature strength, electrical conductivity, thermal conductivity and oxidation resistance.

[0003] In applications such as mortars, copper-steel dissimilar metal joints require high-temperature resistance, needing to operate continuously at approximately 880°C without softening. Simultaneously, the welding temperature must not exceed 1000°C to prevent the copper base material from softening due to overheating, which would affect the overall mechanical properties. Currently, commonly used brazing filler metals for copper-steel dissimilar metal connections mainly include copper-based, silver-based, and nickel-based brazing filler metals. Among them, silver-based brazing filler metals have a relatively low melting temperature of about 665-850℃, which is beneficial for low-temperature welding, but it is difficult to meet the high-temperature service conditions. Copper-based brazing filler metals have a slightly higher melting temperature, such as Cu40MnNi with a melting temperature of 950-960℃, but the total content of Mn and Ni is as high as 60%, resulting in poor processing performance and difficulty in forming. Nickel-based brazing filler metals such as Ni82CrSiB have a relatively high melting temperature (980-1000℃), and their high-temperature strength can meet the application requirements, but their welding temperature is relatively high (1050-1180℃), which is too close to the melting point of copper base material (1083℃), which can easily lead to excessive softening of the copper base material and fail to meet the actual application requirements.

[0004] Therefore, there is an urgent need to develop a new type of brazing material that can enable brazing of dissimilar metals such as copper and steel at lower temperatures and can be used stably for a long time under high temperature conditions.

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

[0006] The first objective of this invention is to provide a foil-shaped brazing filler metal for copper-steel brazing. The foil-shaped brazing filler metal includes a copper-based brazing filler metal and a three-dimensional metal mesh skeleton embedded in the copper-based brazing filler metal. The three-dimensional metal mesh skeleton is woven from nickel wire and nickel-plated tungsten wire. This brazing filler metal foil can achieve copper-steel welding at temperatures below 1000°C, and the resulting weld joint has excellent joint strength and high-temperature resistance.

[0007] A second objective of this invention is to provide a method for preparing the foil-shaped brazing filler metal for copper-steel brazing as described above.

[0008] A third objective of this invention is to provide a copper-steel dissimilar metal joint, which is obtained by brazing using the copper-steel brazing foil as described above.

[0009] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: A foil-shaped brazing filler metal for copper-steel brazing includes a copper-based filler metal and a metal mesh skeleton embedded inside the copper-based filler metal. The metal mesh skeleton is woven from nickel wire and nickel-plated tungsten wire. By mass percentage, the foil-shaped filler metal includes Ni 15.26%-22.89%, W 3.3%-9.62%, Ag 3.5%-8%, Mn 2.8%-4.8%, Zn 1.4%-4%, Si 1.05%-1.6%, with the balance being Cu.

[0010] Preferably, the metal mesh skeleton accounts for 20%-30% of the mass of the foil-shaped brazing filler metal; by mass percentage, the copper-based brazing filler metal comprises Ag 5.0%-10.0%, Mn 4%-6%, Zn 2%-5%, Si 1.5%-2.0%, with the balance being Cu.

[0011] Preferably, the mass ratio of Ni to W in the metal mesh skeleton is 1.6-5.06:1.

[0012] Preferably, in the metal mesh skeleton, the ratio of the number of nickel-plated tungsten wires to the number of nickel wires is 1:1-2.

[0013] Preferably, the diameter of the nickel wire is 0.1-0.15 mm.

[0014] Preferably, the diameter of the nickel-plated tungsten wire is 0.1-0.15 mm.

[0015] Preferably, the nickel wire has the same diameter as the nickel-plated tungsten wire.

[0016] Preferably, the pores in the metal mesh skeleton are round or square holes with a diameter of 0.5-1 mm and a spacing of 0.6-1.15 mm.

[0017] The method for preparing foil-shaped brazing filler metal for copper-steel brazing according to any one of the foregoing embodiments includes the following steps: S1. Take nickel-plated tungsten wire and nickel wire and weave them into a mesh. The length and width of the mesh are consistent with the width of the required foil-shaped brazing filler metal to obtain a metal mesh skeleton. S2. Take copper-based brazing filler metal powder, mix it with flux and water in a certain proportion to form a gel-like substance for later use; S3. Clean the metal mesh skeleton, uniformly press the adhesive onto the upper and lower surfaces of the metal mesh skeleton, perform induction cladding after preheating, and polish to obtain the foil-shaped brazing filler metal.

[0018] Preferably, the copper-based brazing filler metal powder in step S2 has a particle size of 200-300 mesh.

[0019] Preferably, the copper-based brazing filler metal powder in step S2 is obtained by vacuum atomization of raw materials for copper-based brazing filler.

[0020] Preferably, the mass ratio of the copper-based brazing filler metal powder, the flux, and the water in step S2 is 8:2-3:1-2.

[0021] Preferably, the flux in step S2 includes at least one of FB102, FB103, and FB104.

[0022] Preferably, in step S3, the cleaning process includes sandblasting.

[0023] Preferably, in step S3, the preheating temperature is 150-300℃ and the preheating time is 15-30 minutes.

[0024] Preferably, in step S3, the induction cladding is ultrasonic induction cladding, and the temperature of the induction cladding is 950-1000℃.

[0025] Preferably, in step S3, the polishing is performed using a wool brushing wheel.

[0026] A copper-steel dissimilar metal joint is obtained by brazing using a foil-shaped brazing filler metal for copper-steel brazing as described in any of the preceding embodiments.

[0027] Preferably, the brazing includes any one of gas-shielded brazing, induction brazing, and vacuum brazing.

[0028] Preferably, the brazing temperature is 950-1000℃.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The copper-steel brazing foil-shaped brazing filler metal provided by the present invention includes a copper-based brazing filler metal and a metal mesh skeleton embedded in the copper-based brazing filler metal. At the brazing temperature, the low melting elements Ag, Zn and Mn in the copper-based brazing filler metal dissolve and diffuse into the base material, and the high melting element Cu reacts with the nickel wire in the metal mesh. The nickel wire diffuses into the brazing seam, while the tungsten wire in the metal mesh does not melt and remains in the brazing seam to form a skeleton, thereby improving the joint strength and high temperature resistance, and realizing low-temperature brazing and high-temperature application of dissimilar metals such as copper and steel.

[0030] (2) The foil-shaped brazing filler metal embedded with a three-dimensional metal mesh skeleton proposed in this invention not only significantly improves the brazing filler metal connection strength, but also efficiently absorbs thermal stress through the metal skeleton formed in the brazing seam, thereby enhancing the service stability and reliability of the joint under high temperature and high stress conditions.

[0031] (3) The present invention uses a three-dimensional metal mesh as a base, and a layer of brazing flux mixture paste is uniformly pressed onto its surface. Brazing metal foil is obtained by ultrasonic induction cladding, and finally the brazing metal foil with an embedded three-dimensional metal mesh skeleton is obtained by drawing wheel shaping. The present invention provides a new technical idea for the preparation of brittle brazing metal foil. Attached Figure Description

[0032] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of the structure of the foil-shaped solder provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the preparation process of the foil-shaped solder provided in an embodiment of the present invention; Figure 3 A topographical view of the brazed joint provided in an embodiment of the present invention; Figure 4 These are morphological images of the copper-steel joints brazed with foil brazing filler metal in Embodiment 1, Comparative Example 1, and Comparative Example 5 of the present invention, showing their high-temperature resistance performance. Figure 5 The image shows the wetting morphology and energy dispersive spectroscopy (EDS) results of the copper-based brazing filler metal on a copper plate in Example 1 of this invention. Detailed Implementation

[0034] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0035] like Figure 1As shown, the first aspect of the present invention provides a foil-shaped brazing filler metal for copper-steel brazing, comprising a copper-based brazing filler metal and a metal mesh skeleton embedded inside the copper-based brazing filler metal, the metal mesh skeleton being woven from nickel wire and nickel-plated tungsten wire; by mass percentage, the foil-shaped brazing filler metal for copper-steel brazing comprises Ni 15.26%-22.89%, W 3.3%-9.62%, Ag 3.5%-8%, Mn 2.8%-4.8%, Zn 1.4%-4%, Si 1.05%-1.6%, with the balance being Cu.

[0036] The copper-steel brazing foil of the present invention has an embedded three-dimensional metal mesh skeleton, which not only significantly improves the connection strength of the brazing filler metal, but also enhances the service stability and reliability of the joint under high temperature and high stress conditions by efficiently absorbing thermal stress through the metal skeleton formed in the brazing seam. Furthermore, at the brazing temperature, the low melting elements Ag, Zn, and Mn in the copper-based brazing filler metal dissolve and diffuse into the base material, while the high melting element Cu reacts with the nickel wire in the metal mesh, and the nickel wire diffuses into the brazing seam. Meanwhile, the tungsten wire in the metal mesh does not melt and remains in the brazing seam to form a skeleton (W has a melting point as high as 3410 degrees and good high temperature resistance), thereby improving the joint strength and high temperature resistance, and enabling low-temperature brazing and high-temperature applications of dissimilar metals such as copper and steel.

[0037] In some embodiments, typically but not limitingly, for example, in the foil brazing filler metal for copper-steel brazing, the mass percentage of Ni can be any one value or a range of any two values ​​from 15.26%, 18%, 20%, 22.89%; the mass percentage of W can be any one value or a range of any two values ​​from 3.3%, 5%, 8%, 9.62%; the mass percentage of Ag can be any one value or a range of any two values ​​from 3.5%, 5%, 6%, 7%, 8%; the mass percentage of Mn can be any one value or a range of any two values ​​from 2.8%, 3%, 3.5%, 4%, 4.5%, 4.8%; the mass percentage of Zn can be any one value or a range of any two values ​​from 1.4%, 2%, 3%, 4%; and the mass percentage of Si can be any one value or a range of any two values ​​from 1.05%, 1.2%, 1.4%, 1.6%.

[0038] In some specific embodiments of the present invention, the metal mesh skeleton accounts for 20%-30% of the mass of the foil-like brazing filler metal for copper-steel brazing. For example, it can be any one value or a range of any two values ​​from 20%, 22%, 25%, 28%, and 30%. By mass percentage, the copper-based brazing filler metal comprises Ag 5.0%-10.0%, Mn 4%-6%, Zn 2%-5%, and Si. The mass percentage of Ag in copper-based brazing filler metal is typically 1.5%-2.0%, with the balance being Cu. However, this is not a limiting rule; for example, in copper-based brazing filler metals, the mass percentage of Ag can be any one of 5%, 6%, 8%, or 10%, or a range of any two values. The mass percentage of Mn can be any one of 4%, 4.5%, 5%, 5.5%, or 6%, or a range of any two values. The mass percentage of Zn can be any one of 2%, 3%, 4%, or 5%, or a range of any two values. The mass percentage of Si can be any one of 1.5%, 1.6%, 1.8%, or 2.0%, or a range of any two values. In foil-type brazing filler metals for copper-steel brazing, if the proportion of the metal mesh skeleton is too small and the proportion of the copper-based filler metal is too large, the joint strength and high-temperature resistance will decrease. If the proportion of the metal mesh skeleton is too large and the proportion of the copper-based filler metal is too small, less brazing filler metal will be formed during brazing, making it impossible to form an effective metallurgical joint.

[0039] In some specific embodiments of the present invention, the mass ratio of Ni to W in the metal mesh skeleton is 1.6-5.06:1. For example, it can be any one value or a range of any two values ​​from 1.6:1, 2:1, 3:1, 4:1, to 5.06:1. If the ratio is too high, the W content will be too low, resulting in a decrease in high-temperature resistance; if the ratio is too low, the Ni content will be too low, resulting in less Ni dissolving and diffusing into the joint, thus weakening the strengthening effect on the joint.

[0040] In some specific embodiments of the present invention, the ratio of nickel-plated tungsten wire to nickel wire in the metal mesh skeleton is 1:1-2, for example, 1:1 or 1:2.

[0041] In some specific embodiments of the present invention, the diameter of the nickel wire in the metal mesh skeleton is 0.1-0.15 mm. For example, it can be any one value or a range of any two values ​​among 0.1 mm, 0.12 mm, 0.14 mm, and 0.15 mm.

[0042] In some specific embodiments of the present invention, the diameter of the nickel-plated tungsten wire in the metal mesh skeleton is 0.1-0.15 mm. For example, it can be any single value or a range of any two values ​​among 0.1 mm, 0.12 mm, 0.14 mm, and 0.15 mm.

[0043] In some specific embodiments of the present invention, the nickel wire and the nickel-plated tungsten wire in the metal mesh skeleton have the same wire diameter, and the woven mesh has a uniform thickness.

[0044] In some specific embodiments of the present invention, the pores in the metal mesh skeleton are round or square holes with a diameter of 0.5-1 mm. For example, it can be any single value or a range of any two values ​​among 0.5 mm, 0.6 mm, 0.8 mm, and 1 mm. When the mesh is square, the diameter usually refers to the side length. The hole spacing (the distance between the centers of two adjacent holes) is 0.6-1.15 mm. For example, it can be any single value or a range of any two values ​​among 0.6 mm, 0.8 mm, 1 mm, and 1.15 mm.

[0045] like Figure 2 As shown, a second aspect of the present invention provides a method for preparing a foil-shaped brazing filler metal for copper-steel brazing as described in any of the foregoing embodiments, comprising the following steps: S1. Take nickel-plated tungsten wire and nickel wire and weave them into a mesh. The width of the mesh is consistent with the length and width of the required foil-shaped brazing filler metal to obtain a metal mesh skeleton. S2. Take copper-based brazing metal powder, mix it with flux and water in a certain proportion to form a gel-like substance (brazing metal flux paste) for later use; S3. Clean the metal mesh skeleton, apply the adhesive evenly to the upper and lower surfaces of the metal mesh skeleton, perform induction cladding after preheating, and polish to obtain foil-shaped brazing filler metal for copper-steel brazing.

[0046] This invention uses a three-dimensional metal mesh as a base, uniformly coating a layer of brazing filler metal and flux mixture onto its surface. After preheating to remove moisture, brazing filler metal foil is obtained through ultrasonic induction cladding. Finally, polishing and shaping are used to obtain a foil-shaped brazing filler metal with an embedded three-dimensional metal mesh skeleton, providing a new technical approach for the preparation of brittle brazing filler metal foil. The foil-shaped brazing filler metal mesh prepared by this invention has copper-based brazing filler metal as both the filling material in the pores and the external coating material, achieving full contact between the metal mesh and the copper-based brazing filler metal. The synergistic effect of the metal mesh skeleton and the copper-based brazing filler metal enables low-temperature brazing and high-temperature applications of copper-steel dissimilar metal joints.

[0047] In some specific embodiments of the present invention, the particle size of the copper-based brazing filler metal powder in step S2 is 200-300 mesh. For example, it can be any one value or a range of any two values ​​among 200 mesh, 220 mesh, 250 mesh, 280 mesh, and 300 mesh.

[0048] In some specific embodiments of the present invention, the copper-based brazing metal powder in step S2 is obtained by vacuum atomization of the raw material of copper-based brazing metal; the temperature of vacuum atomization is 980-1050℃, for example, it can be any one value or a range of any two values ​​among 980℃, 1000℃, 1020℃, and 1050℃.

[0049] In some specific embodiments of the present invention, the mass ratio of copper-based solder powder, flux and water in step S2 is 8:2-3:1-2. For example, it can be any one value or a range of any two values ​​from 8:2:1, 8:2:2, 8:3:1, 8:3:2. To avoid introducing impurities, distilled water is used as an example.

[0050] In some specific embodiments of the present invention, the flux in step S2 includes at least one of FB102, FB103, and FB104.

[0051] In some specific embodiments of the present invention, the cleaning process in step S3 includes sandblasting, the purpose of which is to remove oxide scale and oil stains from the surface of the metal mesh skeleton.

[0052] In some specific embodiments of the present invention, in step S3, the preheating temperature is 150-300°C, for example, it can be any one value or a range of any two values ​​among 150°C, 200°C, 250°C, and 300°C; the preheating time is 15-30 min, for example, it can be any one value or a range of any two values ​​among 15 min, 20 min, 25 min, and 30 min.

[0053] In some specific embodiments of the present invention, in step S3, the induction cladding is ultrasonic induction cladding, and the induction cladding temperature is 950-1000℃. For example, it can be any one value or a range of any two values ​​among 950℃, 960℃, 980℃, and 1000℃.

[0054] In some specific embodiments of the present invention, in step S3, polishing is performed using a wool brushing wheel.

[0055] A third aspect of the present invention provides a copper-steel dissimilar metal joint, which is obtained by brazing using a foil-shaped filler metal for copper-steel brazing as described in any of the foregoing embodiments.

[0056] In some specific embodiments of the present invention, brazing includes any one of gas-shielded brazing, induction brazing, and vacuum brazing.

[0057] In some specific embodiments of the present invention, the brazing temperature is 950-1000℃, for example, it can be any one value or a range of any two values ​​among 950℃, 960℃, 980℃, and 1000℃; the brazing temperature does not exceed 1000℃, which meets the low-temperature brazing requirements of copper-steel joints; at the same time, the resulting joint can withstand high temperature of 880℃ and can be used stably for a long time under high temperature conditions.

[0058] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0059] Example 1 This embodiment provides a foil-shaped brazing filler metal for copper-steel brazing, comprising a copper-based filler metal and a metal mesh skeleton embedded within the copper-based filler metal. The metal mesh skeleton is woven from nickel-plated tungsten wire and pure nickel wire, and both the internal and external coatings of the mesh skeleton are made of copper-based filler metal. The mass ratio of nickel to tungsten in the metal mesh skeleton is Ni:W = 3.22:1; the metal mesh skeleton accounts for 20% of the mass of the foil-shaped filler metal. By mass percentage, the composition of the foil-shaped filler metal is: Ni 15.26%, W 4.74%, Ag 4%, Mn 3.2%, Zn 1.6%, Si 1.2%, with the balance being Cu. The mass percentages of each element in the copper-based filler metal layer are as follows: Ag 5.0%, Mn 4%, Zn 2%, Si 1.5%, with the balance being Cu. The nickel wires and nickel-plated tungsten wires in the metal mesh skeleton have the same diameter, both 0.1 mm, and the ratio of the diameter of the nickel-plated tungsten wire to the diameter of the pure tungsten wire in the core is 2:1; the ratio of the number of nickel-plated tungsten wires to nickel wires is 1:1; the metal mesh skeleton has square holes with a side length of 0.5 mm and a hole spacing of 0.6 mm.

[0060] The preparation method is as follows: S1. Assuming the brazing foil is 100mm wide and weighs 100kg, based on the mass ratio of the metal mesh skeleton to the copper-based brazing filler and the mass ratio of Ni to W, calculate the required metal mesh skeleton of 20kg and copper-based brazing filler of 80kg. Based on the Ni to W density ratio, take nickel-plated tungsten wire with a diameter of 0.1mm (nickel plating thickness of 0.025mm) and pure Ni wire (the ratio of the two is 1:1) and weave them into a metal mesh with a width of 100mm and a thickness of 0.2mm. S2. Weigh the Cu-based solder raw material according to the ratio, and atomize it in vacuum at 980℃ to form solder metal powder with a particle size of 200-300 mesh; take the solder metal powder, mix it with flux (FB102) and distilled water at a mass ratio of 8:2:1 to form a mixed gel-like substance of solder and flux for later use. S3. Take the metal mesh from step S1 and sandblast it to remove the surface oxide scale and oil stains. Apply the gel from step S2 evenly to the upper and lower surfaces of the metal mesh. Preheat it in a tunnel furnace at 150°C for 15 minutes. Then, clad it with a brazing filler metal foil at 950°C using ultrasonic induction welding. After polishing the brazing filler metal foil with a wool polishing wheel of a wire drawing machine, obtain a foil-shaped brazing filler metal containing a metal mesh skeleton.

[0061] Example 2 This embodiment provides a foil-shaped brazing filler metal for copper-steel brazing, comprising a copper-based filler metal and a metal mesh skeleton embedded within the copper-based filler metal. The metal mesh skeleton is woven from nickel-plated tungsten wire and pure nickel wire, and the internal and external coatings of the mesh skeleton are both made of copper-based filler metal. The mass ratio of nickel to tungsten in the metal mesh skeleton is Ni:W = 5.06:1; the metal mesh skeleton accounts for 20% of the mass of the foil-shaped filler metal; by mass percentage, the composition of the foil-shaped filler metal is Ni 16.7%, W 3.3%, Ag 8%, Mn 4.8%, Zn 4%, Si 1.6%, with the balance being Cu; the mass percentages of each element in the copper-based filler metal layer are as follows: Ag 10.0%, Mn 6%, Zn 5%, Si 2.0%, with the balance being Cu. The nickel wires and nickel-plated tungsten wires in the metal mesh skeleton have the same diameter, both 0.1 mm, and the ratio of the diameter of the nickel-plated tungsten wire to the diameter of the pure tungsten wire in the core is 2:1; the ratio of the number of nickel-plated tungsten wires to nickel wires is 1:2; the metal mesh skeleton has square holes with a side length of 1.0 mm and a hole spacing of 1.15 mm.

[0062] The preparation method is similar to that in Example 1, except that: In step S2, the temperature for vacuum atomization powder production is 990℃; the mass ratio of solder, flux (FB102), and distilled water is 8:3:2. In step S3, the preheating temperature is 180℃ and the preheating time is 20min; the induction cladding temperature is 960℃.

[0063] Example 3 This embodiment provides a foil-shaped brazing filler metal for copper-steel brazing, comprising a copper-based filler metal and a metal mesh skeleton embedded within the copper-based filler metal. The metal mesh skeleton is woven from nickel-plated tungsten wire and pure nickel wire, and both the interior and exterior cladding of the mesh skeleton are made of copper-based filler metal. The mass ratio of nickel to tungsten in the metal mesh skeleton is Ni:W = 1.6:1; the metal mesh skeleton accounts for 25% of the mass of the foil-shaped filler metal. By mass percentage, the composition of the foil-shaped filler metal is: Ni 15.38%, W 9.62%, Ag 3.75%, Mn 3%, Zn 1.5%, Si 1.125%, with the balance being Cu. The mass percentages of each element in the copper-based filler metal layer are as follows: Ag 5.0%, Mn 4%, Zn 2%, Si 1.5%, with the balance being Cu. The nickel wires and nickel-plated tungsten wires in the metal mesh skeleton have the same diameter, both 0.15 mm, and the ratio of the diameter of the nickel-plated tungsten wire to the diameter of the pure tungsten wire in the core is 1.5:1; the ratio of the number of nickel-plated tungsten wires to nickel wires is 1:1; the metal mesh skeleton has square holes with a side length of 0.5 mm and a hole spacing of 0.6 mm.

[0064] The preparation method is similar to that in Example 1, except that: The temperature for vacuum atomization powder production in step S2 is 1000℃; In step S3, the preheating temperature is 200℃ and the preheating time is 20min; the induction cladding temperature is 980℃.

[0065] Example 4 This embodiment provides a foil-shaped brazing filler metal for copper-steel brazing, comprising a copper-based filler metal and a metal mesh skeleton embedded within the copper-based filler metal. The metal mesh skeleton is woven from nickel-plated tungsten wire and pure nickel wire, and both the internal and external coatings of the mesh skeleton are made of copper-based filler metal. The mass ratio of nickel to tungsten in the metal mesh skeleton is Ni:W = 2.64:1; the metal mesh skeleton accounts for 25% of the mass of the foil-shaped filler metal. By mass percentage, the composition of the foil-shaped filler metal is: Ni 18.13%, W 6.87%, Ag 7.5%, Mn 4.5%, Zn 3.75%, Si 1.5%, with the balance being Cu. The mass percentages of each element in the copper-based filler metal layer are as follows: Ag 10.0%, Mn 6%, Zn 5%, Si 2.0%, with the balance being Cu. The nickel wires and nickel-plated tungsten wires in the metal mesh skeleton have the same diameter, both 0.15 mm. The ratio of the diameter of the nickel-plated tungsten wire to that of the pure tungsten wire in the core is 1.5:1. The ratio of the number of nickel-plated tungsten wires to nickel wires is 1:2. The metal mesh skeleton has square holes with a side length of 1.0 mm and a hole spacing of 1.15 mm.

[0066] The preparation method is similar to that in Example 1, except that: In step S2, the temperature for vacuum atomization powder production is 1050℃; the mass ratio of solder, flux (FB102), and distilled water is 8:3:2. In step S3, the preheating temperature is 250℃ and the preheating time is 25min; the induction cladding temperature is 1000℃.

[0067] Example 5 This embodiment provides a foil-shaped brazing filler metal for copper-steel brazing, comprising a copper-based filler metal and a metal mesh skeleton embedded within the copper-based filler metal. The metal mesh skeleton is woven from nickel-plated tungsten wire and pure nickel wire, and both the internal and external coatings of the mesh skeleton are made of copper-based filler metal. The mass ratio of nickel to tungsten in the metal mesh skeleton is Ni:W = 3.22:1. The metal mesh skeleton accounts for 30% of the mass of the foil-shaped filler metal. By mass percentage, the composition of the foil-shaped filler metal is: Ni 22.89%, W 7.11%, Ag 3.5%, Mn 2.8%, Zn 1.4%, Si 1.05%, with the balance being Cu. The mass percentages of each element in the copper-based filler metal layer are as follows: Ag 5.0%, Mn 4%, Zn 2%, Si 1.5%, with the balance being Cu. The nickel wires and nickel-plated tungsten wires in the metal mesh skeleton have the same diameter, both 0.1 mm, and the ratio of the diameter of the nickel-plated tungsten wire to the diameter of the pure tungsten wire in the core is 2:1; the ratio of the number of nickel-plated tungsten wires to nickel wires is 1:1; the metal mesh skeleton has square holes with a side length of 0.5 mm and a hole spacing of 0.6 mm.

[0068] The preparation method is similar to that in Example 1, except that: In step S2, the mass ratio of solder, flux (FB102), and distilled water is 8:3:2. In step S3, the preheating temperature is 280℃ and the preheating time is 25min; the induction cladding temperature is 1000℃.

[0069] Example 6 This embodiment provides a foil-shaped brazing filler metal for copper-steel brazing, comprising a copper-based filler metal and a metal mesh skeleton embedded within the copper-based filler metal. The metal mesh skeleton is woven from nickel-plated tungsten wire and pure nickel wire, and both the internal and external coatings of the mesh skeleton are made of copper-based filler metal. The mass ratio of nickel to tungsten in the metal mesh skeleton is Ni:W = 2.64:1. The metal mesh skeleton accounts for 30% of the mass of the foil-shaped filler metal. By mass percentage, the composition of the foil-shaped filler metal is: Ni 21.76%, W 8.24%, Ag 7%, Mn 4.2%, Zn 3.5%, Si 1.4%, with the balance being Cu. The mass percentages of each element in the copper-based filler metal layer are as follows: Ag 10.0%, Mn 6%, Zn 5%, Si 2%, with the balance being Cu. The nickel wires and nickel-plated tungsten wires in the metal mesh skeleton have the same diameter, both 0.15 mm. The ratio of the diameter of the nickel-plated tungsten wire to that of the pure tungsten wire in the core is 1.5:1. The ratio of the number of nickel-plated tungsten wires to nickel wires is 1:2. The metal mesh skeleton has square holes with a side length of 1.0 mm and a hole spacing of 1.15 mm.

[0070] The preparation method is similar to that in Example 1, except that: The temperature for vacuum atomization powder production in step S2 is 1000℃; In step S3, the preheating temperature is 300℃ and the preheating time is 30min; the induction cladding temperature is 1000℃.

[0071] Comparative Example 1 Comparative Example 1 is similar to Example 1, except that the foil solder is entirely copper-based and does not contain a metal mesh skeleton. All other conditions are the same as in Example 1.

[0072] Comparative Example 2 The solder composition of Comparative Example 2 is Ni82CrSiB solder.

[0073] Comparative Example 3 Comparative Example 3 is similar to Example 1, except that the nickel-plated tungsten wire is replaced with nickel wire, the metal mesh skeleton is made of nickel wire, and all other conditions are the same as in Example 1.

[0074] Comparative Example 4 Comparative Example 4 is similar to Example 1, except that the tungsten wires in the metal mesh skeleton are not nickel-plated, the diameter of the tungsten wires is adjusted, and the mass ratio of Ni to W and the quantity ratio of tungsten wires to nickel wires are kept the same as in Example 1. All other conditions are the same as in Example 1.

[0075] Comparative Example 5 Comparative Example 5 is similar to Example 1, except that: in the metal mesh skeleton, the mass ratio of Ni to W is approximately 5.93:1, the thickness of the nickel plating layer is 0.02 mm, the ratio of the number of nickel wires to the number of nickel-plated tungsten wires is 4:1, and all other conditions are the same as in Example 1.

[0076] Comparative Example 6 Comparative Example 6 is similar to Example 1, except that: in the metal mesh skeleton, the mass ratio of Ni to W is about 1.03:1, the coating thickness is 0.02 mm, the ratio of the number of nickel wires to the number of nickel-plated tungsten wires is 1:6, and all other conditions are the same as in Example 1.

[0077] Comparative Example 7 Comparative Example 7 is similar to Example 1, except that the metal mesh skeleton accounts for 10% of the mass of the foil solder, and all other conditions are the same as in Example 1.

[0078] Comparative Example 8 Comparative Example 8 is similar to Example 1, except that the metal mesh skeleton accounts for 50% of the mass of the foil solder, and all other conditions are the same as in Example 1.

[0079] Comparative Example 9 Comparative Example 9 is similar to Example 1, except that the composition of the copper-based solder by mass percentage is: Ag 20%, Mn 4%, Zn 8%, Si 1.5%, with the balance being Cu. All other conditions are the same as in Example 1.

[0080] Test case The foil-shaped brazing filler metals used in the various embodiments and comparative examples of this invention were used for vacuum brazing of copper and 45# steel at a brazing temperature of 980℃ for 15 minutes. Five joints were welded for each type of brazing filler metal to make standard samples. The joint strength was tested according to GB / T 11363, and the average value was taken. Thirty joints were welded for each type of brazing filler metal, with five joints forming a batch. The high-temperature resistance performance was tested in batches (they were placed in a furnace at 880℃ for 2 hours, then removed and inverted at 90° to check whether the joints remelted or detached). The percentage of the number of joints that detached out out of the total number of high-temperature tests was calculated as the detachment rate.

[0081] The test results are shown in Table 1.

[0082] Table 1

[0083] From Table 1, Figure 3 , Figure 4It can be seen that, compared with the comparative examples, the copper-steel joints brazed with brazing filler metal in the examples have higher strength, especially the joint strength of Example 6, which reaches 325.5 MPa. Simultaneously, the joints brazed with brazing filler metal in the examples exhibit good high-temperature resistance, showing no remelting or detachment after the high-temperature test. Conversely, the joints in Comparative Example 1 all detached because the copper-based brazing filler metal in Comparative Example 1 had poor high-temperature resistance, resulting in thermal stress cracks at the brazing seam during the high-temperature test, and complete detachment after being inverted 90°. The brazing filler metal in Comparative Example 2 was nickel-based, with a high melting temperature; at a welding temperature of 980°, the filler metal could not melt, making effective welding impossible. The brazing filler metal in Comparative Example 3 had a completely nickel-based metal mesh skeleton without tungsten wire, leading to reduced high-temperature resistance and a 20% detachment rate. In Comparative Example 4, the tungsten wire was not nickel-plated, preventing the copper brazing filler metal and tungsten wire from forming a complete metallurgical bond. The yield rate during the brazing filler metal foil forming process was only 45%, and the internal welding rate of the joint was low, with internal voids and low strength. The brazing filler metal in Comparative Example 5 had an excessively low tungsten content. The high-temperature resistance of Comparative Example 6 is slightly poor, with a 10% detachment rate; the tungsten content in Comparative Example 6 is too high, and the nickel content is too low, resulting in less nickel dissolution and diffusion into the joint, which weakens the joint reinforcement. Although the joint has good high-temperature resistance, its strength is slightly low; the metal mesh skeleton content in Comparative Example 7 is low, and most of it is copper-based brazing alloy, resulting in poor joint strength and high-temperature resistance, with a detachment rate of 50%; the metal mesh skeleton content in Comparative Example 8 is high, and the brazing alloy content is low, resulting in less brazing alloy liquid formed during brazing, which cannot form an effective metallurgical joint; the copper-based brazing alloy in Comparative Example 9 has a high content of low-melting-point elements, which cannot completely diffuse into the base material during brazing, causing the low-melting-point phase to remelt, resulting in a 30% detachment rate of the joint.

[0084] Figure 5 The image shows the wetting morphology and energy dispersive spectroscopy (EDS) results of the copper-based brazing filler metal on a copper plate in Example 1. The theoretical composition of the copper-based brazing filler metal is 5.0% Ag and 2% Zn. However, the EDS results at three points show that there is no Ag or Zn. This indicates that the low-melting-point elements Ag and Zn can completely diffuse into the base material without affecting the high-temperature resistance of the brazing filler metal.

[0085] Although the present invention has been illustrated and described with specific embodiments, it should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and scope of the present invention; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such substitutions and modifications that fall within the scope of the present invention are included in the appended claims.

Claims

1. A foil-shaped brazing material for copper-steel brazing, characterized by comprising, in mass %, The foil-shaped filler metal comprises a copper-based filler metal and a metal mesh skeleton embedded in the copper-based filler metal, the metal mesh skeleton is made of nickel wires and nickel-plated tungsten wires; the foil-shaped filler metal comprises, by mass percentage, Ni 15.26%-22.89%, W 3.3%-9.62%, Ag 3.5%-8%, Mn 2.8%-4.8%, Zn 1.4%-4%, Si 1.05%-1.6%, and the balance being Cu.

2. The foil-shaped brazing material for copper-steel brazing according to claim 1, characterized by The mass ratio of the metal mesh skeleton to the foil-shaped filler metal is 20%-30%; the copper-based filler metal comprises, by mass percentage, Ag 5.0%-10.0%, Mn 4%-6%, Zn 2%-5%, Si 1.5%-2.0%, and the balance being Cu.

3. The foil-shaped brazing material for copper-steel brazing according to claim 1, characterized by The mass ratio of Ni to W in the metal mesh skeleton is 1.6-5.06:

1.

4. The foil-shaped brazing material for copper-steel brazing according to claim 1, characterized by In the metal mesh skeleton, the number ratio of the nickel-plated tungsten wires to the nickel wires is 1:1-2.

5. The foil-shaped brazing material for copper-steel brazing according to any one of claims 1 to 4, characterized by, At least one of the following characteristics is satisfied: (1) the wire diameter of the nickel wires is 0.1-0.15 mm; (2) the wire diameter of the nickel-plated tungsten wires is 0.1-0.15 mm; (3) the wire diameters of the nickel wires and the nickel-plated tungsten wires are the same; (4) the pores in the metal mesh skeleton are circular or square, the pore diameter is 0.5-1 mm, and the pore spacing is 0.6-1.15 mm.

6. The method of producing a foil-shaped brazing material for copper-steel brazing as claimed in any one of claims 1 to 5, characterized in that, The method comprises the following steps: S1. weaving nickel wires and nickel-plated tungsten wires into a mesh, the width of the mesh being consistent with the length and width of the required foil-shaped filler metal, to obtain a metal mesh skeleton; S2. mixing and stirring copper-based filler metal powders, a brazing agent and water in a certain proportion to obtain a gel for standby; S3. cleaning the metal mesh skeleton, uniformly coating the gel on the upper and lower surfaces of the metal mesh skeleton, preheating, and then performing induction cladding, to obtain the foil-shaped filler metal.

7. The method of producing a foil-shaped brazing material for copper-steel brazing according to claim 6, characterized by, At least one of the following characteristics is satisfied in step S2: (1) the particle size of the copper-based filler metal powders is 200-300 mesh; (2) the copper-based filler metal powders are obtained by vacuum gas atomization of raw materials of the copper-based filler metal; (3) the mass ratio of the copper-based filler metal powders, the brazing agent and the water is 8:2-3:1-2; (4) the brazing agent comprises at least one of FB102, FB103 and FB104.

8. The method of producing a foil-shaped brazing material for copper-steel brazing according to claim 6 or 7, characterized in that, At least one of the following characteristics is satisfied in step S3: (1) the cleaning method comprises sand blasting; (2) the preheating temperature is 150-300℃, and the preheating time is 15-30 min; (3) the induction cladding is ultrasonic frequency induction cladding, and the induction cladding temperature is 950-1000℃; (4) the polishing is performed by a wool wire drawing wheel.

9. A copper-steel dissimilar metal joint, characterized by, The copper-steel brazing foil-shaped filler metal is used for brazing.

10. The copper-steel dissimilar metal joint of claim 9, wherein, At least one of the following characteristics is satisfied: (1) the brazing comprises any one of gas protection brazing, induction brazing and vacuum brazing; (2) the brazing temperature is 950-1000℃.

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