A method for producing a composite wire or strip and use thereof

Abstract

The application provides a preparation method and application of a composite metal wire or strip, and relates to the technical field of composite metal processing. Specifically, a metal tube is prepared, and an isometric metal column is inserted into the metal tube; the assembled composite blank is subjected to rotary swaging; the blank after rotary swaging is subjected to annealing rolling to obtain a composite metal strip; or the blank after rotary swaging is subjected to wire drawing to obtain a composite metal wire; and for the strip, the cross-sectional perimeter, the diameter after rotary swaging and the first pass reduction of the annealing rolling satisfy a specific proportional relationship. The application can be used for preparing a composite wire for bonding or a sandwich structure strip for brazing, and can effectively overcome the defects of conventional composite methods such as hot rolling, diffusion, extrusion and explosion, which cannot be considered in terms of product quality, production efficiency and cost, and has good applicability and designability.

Description

Technical Field

[0001] The present invention relates to the technical field of composite metal processing, and in particular to a preparation method and application of a composite metal wire or strip. Background Art

[0002] Metal composites are formed by combining two or more metal materials with different properties through various processes (such as hot-rolling, diffusion bonding, extrusion bonding, and explosive bonding). These composites typically combine the advantages of both metals, achieving complementary performance and meeting application requirements that cannot be achieved by a single metal alone. For example, stainless steel and carbon steel can be combined to achieve both high strength and corrosion resistance; aluminum and copper can be combined to create lightweight composites with excellent thermal conductivity; and silver and copper can be combined to create sandwich composites that effectively relieve joint stress. Metal composites can also reduce the amount of one metal used. For example, while some precious metals (such as platinum, silver, and gold) possess excellent physical and chemical properties but are expensive, combining them with other common metals (such as steel and aluminum) can significantly reduce production costs while maintaining material performance. Metal composites are widely used not only in traditional fields such as machinery, automotive, and chemical engineering, but are also increasingly showing great potential in high-tech fields such as aerospace and electronics. However, conventional composite processes have their own limitations.

[0003] Hot-rolled lamination requires preheating the composite material, then applying a certain amount of pressure through rolling equipment to deform the two or more materials and bond them together. However, this method is limited by the rolling equipment and is difficult to achieve for multi-layer or ultra-multi-layer composite strips. Furthermore, the multi-layer materials are prone to deviation during the rolling process, requiring mechanical fixation of the multi-layered materials. High-temperature preheating of the materials can easily lead to oxidation at the material interface, resulting in a weak bonding at the rolling interface. The outer metal is prone to cracking during the rolling process, making the production process difficult to control and resulting in low yields.

[0004] Diffusion bonding is an improvement on hot-rolled bonding, concentrating the blank fixation and preheating steps in a vacuum diffusion furnace to reduce interfacial oxidation. However, the size of the composite material is limited by the furnace, resulting in low production efficiency. Furthermore, the equipment is expensive and the production investment is high.

[0005] Extrusion lamination involves heating metals to a plastic state at high temperatures and then extruding them to form composite materials. However, differences in metal fluidity can result in the head and tail of the extruded composite material appearing as a single metal or exhibiting uneven lamination. Furthermore, hot extrusion requires specialized equipment and extrusion dies, resulting in high costs.

[0006] Explosive cladding uses explosive energy to accelerate two metal materials into a composite material. This allows for joining different metal types, especially those with significantly different chemical properties. However, the use of explosive energy makes the process dangerous and poses a significant safety risk. Furthermore, the surface finish of the joint is not smooth, requiring further treatment.

[0007] In view of this, the present invention is proposed to provide a new metal cladding method to effectively improve the defects of the above-mentioned conventional metal cladding methods. Summary of the Invention

[0008] The first purpose of the present invention is to provide a method for preparing composite metal wire or strip, which mainly involves rotary forging two nested metal raw materials, and then preparing wire-shaped or strip-shaped composite metal materials through wire drawing or rolling. It can effectively solve the defects of conventional composite methods such as hot rolling composite, diffusion composite, extrusion composite, and explosive composite in terms of finished product quality, production efficiency, cost, etc.

[0009] The second object of the present invention is to provide a use of the composite metal material produced by the method for producing the composite metal wire or strip in brazing or packaging.

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

[0011] A method for preparing a composite metal wire or strip comprises the following steps:

[0012] Prepare a metal tube, and insert metal pillars of equal height into the metal tube; wherein the metal tube comprises a first metal material, and the metal pillars comprise a second metal material;

[0013] performing rotary forging on a composite blank comprising the metal tube and the metal column;

[0014] Annealing and rolling the swaged blank to obtain a composite metal strip; or drawing the swaged blank to obtain a composite metal wire;

[0015] Wherein, the cross-sectional perimeter of the composite metal strip is S, the diameter of the billet after swaging is D, Δh is the first pass reduction of the annealing rolling, and the units of S, D, and Δh are the same, λ=48-53.8, satisfying:

[0016]

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] (1) The present invention proposes a method for preparing composite metal materials by rotary forging, creatively applying the rotary forging process to the preparation of composite materials, and utilizing the large deformation amount of rotary forging to achieve composite material without preheating, thereby reducing interface oxidation; at the same time, the rotary forging process continuously forges the outer metal, thereby refining the structure of the outer metal corresponding to the metal tube, thereby reducing the cracking of the outer metal during subsequent processing; at the same time, the present invention reduces the mechanical fixing link of the composite raw material by adopting a metal raw material with a plug-in structure similar to a hole rod; further, the present invention can achieve a substantial increase in the yield of the composite strip by customizing the parameters such as the diameter and inner diameter of the metal tube and the metal column, and the ratio of the inner and outer metal layers, and the length of the composite material is not limited, thereby greatly improving the production efficiency.

[0019] (2) The composite metal wire prepared by the present invention can be used as a composite wire for bonding, and the preparation method based on the present invention can reduce the amount of precious metal coating layer used, and obtain a precious metal outer layer with better coating tensile properties, and obtain a wire with a lower diameter; the composite metal strip has a structural feature similar to a sandwich, and can be used as a strip solder product after processing; it can be seen that the preparation method of the present invention has good practicality and a wide range of application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 A schematic diagram of a multi-metal composite swaging material of the present invention is provided;

[0022] Figure 2 Provides a microstructure diagram of the dissimilar metal interface after rotary forging in step 6 of Example 1;

[0023] Figure 3 Provides a microstructure diagram of the sandwich solder strip obtained in step 7 of Example 1 when the rolled thickness is 0.5 mm;

[0024] Figure 4 A cross-sectional view of the embodiment 1 after rotary forging in step 5 is provided;

[0025] Figure 5 A cross-sectional view of Comparative Example 1 is provided;

[0026] Figure 6 A physical picture of the finished strip of Example 1 is provided;

[0027] Figure 7 A physical picture of the finished strip of Comparative Example 1 is provided;

[0028] Figure 8 Provides a surface micrograph of Example 1;

[0029] Figure 9 A surface micrograph of Comparative Example 1 is provided;

[0030] Figure 10 Provided are microscopic images obtained by drawing of Example 4 and Comparative Example 2. DETAILED DESCRIPTION

[0031] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, but those skilled in the art will understand that the embodiments described below 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 regarded 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 conventional conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially. In addition, the terms "one", "1", "2" etc. are only used for descriptive purposes and should not be understood as indicating or suggesting relative importance.

[0032] The first aspect of the present invention is to provide a method for preparing a composite metal wire or strip. Specifically, the method mainly comprises the following steps:

[0033] (1) A metal tube is prepared, and metal columns of equal height are inserted into the metal tube; wherein the metal tube comprises a first metal material, and the metal columns comprise a second metal material.

[0034] As a preferred embodiment, the inner diameter of the metal tube is slightly larger than the diameter of the metal column; in some optional embodiments, the difference between the inner diameter of the metal tube and the diameter of the metal column is between 0.02 mm and 0.3 mm.

[0035] As a more preferred embodiment, the inner diameter of the metal tube is 3 mm to 8 mm, and the thickness of the metal tube is 1 mm to 2 mm. In a further preferred embodiment, the inner diameter of the metal tube is 5 mm, and the thickness of the metal tube is 1.5 mm.

[0036] As a preferred embodiment, there are two situations for the ratio of the diameter of the metal column to the diameter of the metal tube:

[0037] When preparing composite metal wires, the ratio of the diameters is not limited, and any diameter combination can be used to obtain any coated wire;

[0038] When preparing a composite metal strip, the ratio of the diameter of the metal column to the diameter of the metal tube is 0.5 to 0.9, including but not limited to any one of 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9 or a numerical range consisting of any two of them.

[0039] It is worth noting that, considering the thickness of the intermediate layer of the finished product corresponding to the metal column, the lower limit of the ratio is set at 0.5 to ensure that the intermediate layer thickness accounts for more than 25%. This is to prevent the outer metal from reacting completely during the subsequent brazing operation of the strip, thus playing a stress relief role. At the same time, since the strip has an outer layer-inner layer-outer layer cladding structure after rotary forging, it may be necessary to shear to remove part or one side of the outer layer metal, so the yield rate after such shearing also needs to be considered. The upper limit of the ratio is set at 0.9 to ensure that there is enough metal A to form a metallurgical bond with the workpiece and metal B to achieve a brazing connection during brazing.

[0040] As a preferred embodiment, the metal tube and the metal column are coaxially arranged, which can also be understood as the pipeline of the metal tube is in the center of the metal tube; in some other optional embodiments, the metal tube and the metal column can be non-coaxially arranged, and the pipeline of the metal tube is not in the center of the metal tube. In this case, an asymmetric multi-metal strip can be obtained, or a composite metal wire with a thickness emphasis on the coating layer can be obtained, but the product application fields obtained by this type of embodiment are relatively small and will not be elaborated in the present invention.

[0041] In a preferred embodiment, prior to this step, one or both of the metal tube and the metal column are polished or cleaned to remove surface oil, oxides, etc., before assembling the two. In some optional embodiments, the cleaning includes but is not limited to water washing, sand washing, ultrasonic washing, acid washing, organic solvent washing, etc.

[0042] As a preferred embodiment, matching interlocking structures are provided on the inner curved surface of the metal tube and the curved surface of the metal column to improve the bonding ability between the interfaces of dissimilar metals and improve the bonding strength after swaging; it should be noted that the inner curved surface is the inner pipeline side wall of the metal tube; in some more preferred embodiments, the interlocking structure includes but is not limited to a threaded structure, a keyway structure, a grid structure, etc.; in some more preferred embodiments, the inner curved surface of the metal tube and the curved surface of the metal column are the contact surfaces of the two, and the interlocking structure is distributed on all the contact surfaces or at both ends of the contact surfaces, that is, those skilled in the art can adaptively adjust the distribution of the interlocking structure on the contact surface according to the bonding ability of dissimilar metals.

[0043] As a preferred embodiment, the method for preparing the metal tube includes the following steps: preparing a cylindrical ingot comprising the first metal material, and then drilling a circular through-hole on the bottom surface of the cylindrical ingot to obtain the metal tube. It can also be understood that the pipeline structure of the metal tube is the aforementioned circular through-hole. As another preferred embodiment, when the aforementioned process of obtaining a solid ingot and then drilling a hole is not adopted, the aperture position can be reserved in a mold when casting the first metal material and obtaining the cylindrical ingot, and the metal tube can be cast in one go.

[0044] As a preferred embodiment, the first metal material includes one of a silver-based material, gold, and silver; the melting point of the silver-based material is ≤720°C, and it is a low-melting-point silver-based material. The silver-based material includes but is not limited to AgCuZnNiCd, AgCuZnNiSn, AgCuZnNiCdCe, AgCuZnNiCdRE, etc.

[0045] As a more preferred embodiment, when preparing composite metal wire, the first metal material is one of gold or silver; when preparing composite metal strip, the first metal material is the above-mentioned silver-based material. At this time, the main application scenario of the composite metal strip is brazing filler metal for brazing.

[0046] As a further preferred embodiment, in order to take into account the cost, melting temperature and processing performance of the solder, the mass percentage ratio of the melting point reducing element to the silver element in the silver-based material is 1 to 2.3, wherein the melting point reducing element includes but is not limited to copper, zinc, tin, etc.; it can be understood that the limitation on the amount of the melting point reducing element here is based on the consideration that the amount of the precious metal Ag needs to be guaranteed to be the lowest, and on the other hand, it is based on the consideration that when the content of the melting point reducing element is too high, extremely brittle phases are easily generated, such as (Ag, Cu)5Zn8, etc., which affect the mechanical properties of the composite metal strip.

[0047] As a preferred embodiment, the second metal material includes one or more of copper, nickel, molybdenum, copper-nickel alloy or copper-manganese alloy, and the copper can be single crystal copper metal or foam copper.

[0048] As a preferred embodiment, the metal column also includes a third metal material; structurally, the second metal material is evenly coated on the outside of the third metal material, and the third metal material is at the axis, and the two are coaxially arranged; it should be noted that the second metal material can be completely coated on the third metal material or partially coated.

[0049] In some more preferred embodiments, the third metal material also includes one or more of copper, nickel, molybdenum, and a copper-nickel alloy, but the third metal material and the second metal material are not identical in metal composition. Those skilled in the art can adapt the amount of the third metal material based on the metal composition requirements of the target product.

[0050] like Figure 1 The figure shows the situation when the third metal material is contained. Figure 1 In the figure, A metal, B metal, and C metal represent the first, second, and third metal materials respectively. It can be seen that the three are coaxially nested and are A, B, and C from the outside to the inside. Correspondingly, in Figure 1 A schematic diagram of the longitudinal interface of the composite wire or composite strip prepared when the third metal material is present is also given.

[0051] As a preferred embodiment, the wetting angle of the first metal material on the second metal material is less than 20°, so as to ensure that the first metal material has good wetting properties on the second metal material, and then the two can achieve good metallurgical bonding after subsequent rotary forging.

[0052] As a preferred embodiment, the linear expansion coefficient of the second metal material is 4*10 -6 ℃ -1 ~15*10 -6 ℃ -1 .

[0053] As a preferred embodiment, the melting point of the first metal material is lower than that of the second metal material; thus, at the brazing temperature, metal A melts, wets the base material and metal B, and connects the base materials; metal B does not melt, but with the help of the good plasticity of metal B, plastically deforms under the stress of the weld joint, thereby relieving stress.

[0054] (2) The composite blank including the metal tube and the metal column is subjected to rotary forging.

[0055] As a preferred embodiment, in the rotary swaging, the surface reduction ratio of the first pass is 30% to 50%, including but not limited to any one of 30%, 32%, 35%, 38%, 40%, 42%, 45%, 48%, and 50%, or a range consisting of any two of these. The lower limit of 30% for the first pass is to allow the inner and outer metals to generate sufficient deformation heat to achieve metallurgical bonding of the two metals; the upper limit of 50% is set to prevent failure of the outer metal due to excessive deformation at room temperature.

[0056] As a preferred embodiment, in the rotary forging, except for the first pass, the surface reduction ratio of each rotary forging pass can be selected arbitrarily, and is not strictly limited in the present invention. The reference value is any one of 10%, 20%, 30%, 40%, 50%, 60%, 70% or a numerical range composed of any two of them.

[0057] As a preferred embodiment, the diameter range of the composite blank is 3.7mm to 30mm (which can also be understood as the diameter of the metal tube); the diameter range of the blank after rotary forging is 2mm to 16mm, that is, the following parameter D satisfies: D≤16mm.

[0058] (3) Annealing and rolling the swaged blank to obtain a composite metal strip; or drawing the swaged blank to obtain a composite metal wire; wherein the cross-sectional perimeter of the composite metal strip is S, the diameter of the swaged blank is D, Δh is the first pass reduction of the annealing and rolling, and the units of S, D, and Δh are the same, λ = 48 to 53.8, and the following conditions are satisfied:

[0059]

[0060] It should be noted that the units of the above parameters are not limited in this invention; the rationality of the formula is satisfied when all parameters are expressed in the same units. Typically, S, D, and Δh are all expressed in mm, and λ is an empirical coefficient and is dimensionless. In actual production, the above empirical formula can be used to determine the final swaging diameter of the composite material based on the target product size, eliminating the need for extensive rolling tests to determine the desired diameter.

[0061] As a preferred embodiment, in the present invention, Δh / D is the diameter reduction rate of the outer metal corresponding to the metal tube under the first pressing pass, and the value range of Δh / D is 0.17 to 0.23.

[0062] As a preferred embodiment, the wire drawing adopts conventional room temperature wire drawing, and the ambient temperature of the room temperature is 20°C to 30°C.

[0063] As a preferred embodiment, the annealing temperature of the annealing rolling is 450° C. to 580° C., and the annealing time of the annealing rolling is 0.5 h to 1.5 h. In the present invention, no limitation is imposed on the diameter reduction ratio of each pass of the annealing rolling.

[0064] As a preferred embodiment, the wire drawing speed is 60m / min to 300m / min.

[0065] As a preferred embodiment, the thickness of the composite metal strip is 0.1 mm to 0.5 mm, and the width of the composite metal strip is 3 mm to 22 mm.

[0066] As a preferred embodiment, the diameter of the composite metal wire is 20 μm to 100 μm.

[0067] As a preferred embodiment, after this step, the composite metal strip or composite metal wire is further cleaned to remove impurities or oxides introduced during this process. In some optional embodiments, the cleaning includes but is not limited to water washing, sand washing, ultrasonic cleaning, acid cleaning, organic solvent washing, etc.

[0068] As an optional embodiment, when preparing a composite metal strip, this step also includes: slitting to remove both sides of the composite metal strip, generally cutting off the portion that does not contain the second metal material, for application in specific scenarios such as brazing.

[0069] The second aspect of the present invention is to provide a use of a composite metal material produced by the method for preparing a composite metal wire or strip as described in the first aspect in brazing or packaging; including but not limited to the use of the composite metal wire or strip produced by the first aspect as a composite bonding wire in packaging, or as a composite solder in brazing, specifically including but not limited to bonding wire or solder products produced by the preparation method of the first aspect, or the use method of the product produced based on the preparation method of the first aspect in a specific field, etc.; it is worth noting that when including the composite metal wire or strip produced as described in the first aspect, any product or method can be regarded as an embodiment of this aspect.

[0070] Example 1

[0071] Step 1: First, prepare a rod-shaped low-melting-point silver-based solder with a composition of BAg50CuZnNiCd and a cross-sectional diameter of 7.3 mm;

[0072] Step 2: Use a lathe to drill a circular through hole with a diameter of 3.9 mm in the center of the BAg50CuZnNiCd solder;

[0073] Step 3: Prepare a copper rod with a cross-sectional diameter of 3.88 mm;

[0074] Step 4: Use sandpaper, alcohol, etc. to polish and clean the surface of the copper rod;

[0075] Step 5: inserting the copper rod into the through hole of the silver-based solder to obtain a composite blank;

[0076] Step 6: Place the composite blank into a rotary swaging device for diameter reduction. The first pass reduction rate is 32.4%. The diameter of the composite material after the first pass of rotary swaging is 6 mm. Continue rotary swaging to obtain a composite wire with a final diameter of 5 mm.

[0077] Step 7: annealing the composite wire at 550° C. for 1 h, and rolling the composite wire to obtain a strip with a thickness of 0.3 mm and a width of 10 mm;

[0078] Step 8: Clean the surface of the composite solder material to remove impurities introduced during rolling or drawing;

[0079] Step 9: Observe the width of the pure metal (copper layer) on both sides of the strip through a stereo microscope, and cut off the copper portion to obtain a sandwich solder strip with a width of 7.8 mm. The solder of this embodiment can be used for brazing cemented carbide and polycrystalline diamond materials.

[0080] like Figure 2 The figure shows the microstructure of the dissimilar metal interface after rotary forging in step six of this embodiment; Figure 3 The thickness cross-section microstructure diagram of the sandwich solder strip obtained in step 7 of this embodiment when the rolling thickness is 0.5 mm is provided. Figure 3 From top to bottom, there is silver solder layer-copper layer-silver solder layer, and the corresponding thicknesses are 169.13μm, 187.13μm, and 142.76μm, respectively.

[0081] from Figure 2 、 3 It can be seen that after forging, the silver solder and copper have achieved a good bond with no obvious gap. From the material microstructure, it can be seen that the outer layer of silver-based solder after rotary forging has a fine and uniform structure, and there is no obvious agglomeration of the compound (the compound size is mostly less than 10μm), which is conducive to the subsequent wire drawing process. During the subsequent rolling process of the composite strip, it was found that the thickness of the composite material is uniform, the position of the middle layer metal is stable, and there is no deviation of the inner layer metal.

[0082] Example 2

[0083] It is basically the same as Example 1, except that the copper rod in step 3 is replaced by a nickel rod.

[0084] Example 3

[0085] Step one, first prepare the component of BAg50CuZnNiCd rod-shaped low melting point silver-based filler metal, the cross-sectional diameter is 23mm;

[0086] Step two, using a lathe, drill a circular through hole with a diameter of 16.2mm in the center of the BAg50CuZnNiCd filler metal;

[0087] Step three, configure a pure copper rod with a cross-sectional diameter of 16mm;

[0088] Step four, polish and clean the surface of the red copper rod using sandpaper, alcohol and the like;

[0089] Step five, insert the copper rod into the through hole of the silver-based filler metal to obtain a composite blank;

[0090] Step six, put the composite blank into the rotary forging equipment for reducing the diameter, the first pass reduction rate is 36%, and the diameter of the composite material after the first pass rotary forging is 18.4mm; then continue to rotary forging to obtain a composite wire with a final diameter of 16mm;

[0091] Step seven, further anneal and roll the composite wire to obtain a wide strip with a thickness of 0.5mm and a width of 21mm;

[0092] Step eight, clean the surface of the composite filler material to remove impurities introduced during rolling or wire drawing;

[0093] Step nine, observe the width of the pure metal (copper layer) on both sides of the strip by a body microscope, and cut off the pure copper part to obtain a sandwich filler strip with a width of 11.2mm.

[0094] For the above embodiments 1-3, taking the cross-sectional circumference of the composite metal strip as S, the diameter of the blank after rotary forging in step six as D, and Δh as the first pass reduction of annealing and rolling in step seven, the statistical values in Table 1 are as follows. Based on Table 1, it is known that

[0095]

[0096] the empirical formula.

[0097] Table 1

[0098]

[0099] As can be seen from Table 1, the S 经验值 calculated by the empirical formula provided by the present application is very close to the S 实际值 measured from the actual product obtained in embodiments 1 and 3, and the difference between them is very small, basically meeting the universal conclusion provided by the empirical formula.

[0100] Example 4

[0101] Step 1: First, prepare a pure silver rod with a diameter of 8 mm;

[0102] Step 2: Use a lathe to drill a circular hole with a diameter of 3.9 mm in the center of the sterling silver bar;

[0103] Step 3: Prepare a metal copper rod with a diameter of 3.88 mm;

[0104] Step 4: Use sandpaper, alcohol, etc. to polish and clean the surface of the copper rod;

[0105] Step 5: Insert the copper rod into the sterling silver rod;

[0106] Step 6: Place the composite blank into a rotary swaging device for diameter reduction. After the first rotary swaging, the diameter of the composite material is 6.5 mm, and the area reduction rate is 34%. Continue rotary swaging to obtain a composite wire with a final diameter of 5 mm.

[0107] Step 7: Clean the surface of the composite wire, and perform multiple passes of annealing and drawing to obtain an Ag-Cu composite bonding wire with a wire diameter of 20 μm.

[0108] Test Example 1

[0109] A commercially available copper-silver based solder prepared by hot-rolled composite was used as comparative example 1, and its performance was compared with that of Examples 1 to 3.

[0110] S1. Yield: Examples 1-3 were repeated 200 times, resulting in an average yield of 65%. The theoretical yield of the swaged composite material is related to the diameter of the inner metal layer. A larger inner metal diameter results in more sandwich structures being produced, and the yield is higher. However, the yield of sandwich brazing filler metals produced by conventional hot-rolled composite materials is typically less than 50%. This demonstrates the significant yield advantage of the present invention's preparation process.

[0111] S2. Interface bonding performance: The intermediate product after the rotary forging in step 5 of Example 1 was longitudinally cut to obtain a macroscopic physical image of the cross section, as shown in FIG. Figure 4 As shown in FIG, the composite interface obtained by rotary forging is tightly bonded, free of impurities, and free of oxidation slag. Figure 5 As shown, severe oxidation can be observed in the cross section.

[0112] At the same time, when preparing sandwich solder through the rotary forging process, the outer metal plays a covering role on the inner metal, and the inner and outer metals deform synchronously. However, during the rolling composite process, due to the different deformation resistance of the inner and outer metals, the inner metal deviates, which is unavoidable during hot rolling composite. Figure 6、 Figure 7 The actual pictures of the finished strips of Example 1 and Comparative Example 1 are provided respectively.

[0113] S3. Internal offset: The outer metal of the sandwich solder prepared by rotary forging process has a fine and uniform structure after rotary forging process, such as Figure 8 As shown in the microscopic image of the surface of the actual object in Example 1, the maximum grain size is 20.36μm. At this time, the outer metal processing performance is good and no edge cracking occurs during the rolling process. However, in Comparative Example 1, large-sized grains exist in the outer metal structure, and the grain size reaches 42.13μm. If the large-sized grains are distributed at the edge of the strip, edge cracking is likely to occur during the rolling process. Figure 9 shown.

[0114] S4. Welding test: Using the products of each embodiment and comparative example 1 as solder, high-frequency induction heating equipment was used to conduct welding experiments on cemented carbide (YG8) and steel (42CrMo). Three independent experiments were conducted for each example, and the shear strength of the joint was tested. The results are shown in Table 2.

[0115] Table 2

[0116]

[0117]

[0118] Test Example 2

[0119] A commercially available silver-copper bonding wire prepared by the drawing method was used as comparative example 2, and its performance was compared with that of example 4.

[0120] When the comparative example 2 was drawn to a diameter of 3 mm and 1.3 mm, and when the step 7 of the embodiment 4 was drawn to a diameter of 3 mm and 1.3 mm, the outer layer of metallic silver was microscopically inspected, and the results were as follows: Figure 10 The four SEM images shown in FIG. 1 respectively correspond to the microstructure of the outer metal silver of Comparative Example 2 when the diameter is 3 mm and 1.3 mm on the left, and to the microstructure of the outer metal silver of Example 4 when the diameter is 3 mm and 1.3 mm on the right; Figure 10 It can be found that the grain size of the tissue after rotary forging is much smaller than that after traditional drawing, and the tissue is more uniform; after Example 4 is drawn to a diameter of 1.3 mm, the grain size contrast is more obvious, the grain size of the rotary forging tissue is significantly smaller than 50 μm, and the grain size of the drawing tissue is greater than 50 μm.

[0121] Although the present invention has been illustrated and described using specific embodiments, it should be appreciated that the above embodiments are merely intended to illustrate the technical solutions of the present invention rather than to limit them. 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 deviate from the essence of the corresponding technical solutions within the scope of the technical solutions of the embodiments of the present invention. Therefore, this means that all such replacements and modifications within the scope of the present invention are included in the appended claims.

Claims

1. A method for preparing a composite metal strip, characterized in that: The steps include: Prepare a metal tube, and insert metal pillars of equal height into the metal tube; wherein the metal tube comprises a first metal material, and the metal pillars comprise a second metal material; performing rotary forging on a composite blank comprising the metal tube and the metal column; Annealing and rolling the swaged blank to obtain a composite metal strip; Wherein, the cross-sectional perimeter of the composite metal strip is S, the diameter of the billet after swaging is D, Δh is the first pass reduction of the annealing rolling, and the units of S, D, and Δh are the same, λ=48~53.8, satisfying: The value range of Δh / D is 0.17~0.23; S, D, and Δh are all measured in mm, D≤16mm; In the rotary forging, the surface reduction ratio of the first rotary forging is 30% to 50%.

2. The method for preparing a composite metal strip according to claim 1, wherein: The difference between the inner diameter of the metal tube and the diameter of the metal column is 0.02 mm to 0.3 mm; And / or, when preparing the composite metal strip, the ratio of the diameter of the metal column to the outer diameter of the metal tube is 0.5-0.

9.

3. The method for preparing a composite metal strip according to claim 1, wherein: Providing matching engaging structures on the inner curved surface of the metal tube and the curved surface of the metal column; The engaging structure includes at least one of a thread structure, a keyway structure or a grid structure.

4. The method for preparing a composite metal strip according to claim 1, wherein: The first metal material includes one of a silver-based material, gold, and silver; wherein the melting point of the silver-based material is ≤720°C.

5. The method for preparing a composite metal strip according to claim 4, characterized in that: The mass percentage ratio of the melting point depressant element to the silver element in the silver-based material is 1-2.3, and the melting point depressant element includes copper, zinc or tin.

6. The method for preparing a composite metal strip according to claim 1, wherein: The metal pillar further comprises a third metal material, and the second metal material is different from the third metal material; The second metal material is evenly coated on the third metal material, and the third metal material is located at the axis of the metal column.

7. The method for preparing a composite metal strip according to claim 6, characterized in that: The second metal material and / or the third metal material includes one or more of copper, nickel, molybdenum, copper-nickel alloy or copper-manganese alloy.

8. The method for preparing a composite metal strip according to claim 1, wherein: The wetting angle of the first metal material on the second metal material is less than 20°; and / or, the melting point of the first metal material is lower than that of the second metal material; And / or, the linear expansion coefficient of the second metal material is 4*10 -6 ℃ -1 ~15*10 -6 ℃ -1 .

9. The method for preparing a composite metal strip according to claim 1, wherein: Before performing the rotary swaging, the method further includes: grinding or cleaning the metal tube and the metal column; After the rotary forging is performed, the method further comprises: cleaning the composite metal strip; The cleaning includes one or more of water washing, sand washing, ultrasonic washing, acid washing or organic solvent washing.

10. Use of the composite metal material prepared by the method for preparing a composite metal strip according to any one of claims 1 to 9 in brazing or packaging.

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