Composite copper strip and preparation method thereof

Abstract

The invention provides a composite copper strip and a preparation method thereof.The method comprises the steps that (1) N layers of copper-based graphene foils are stacked and then subjected to primary composite rolling at the temperature of 500-1070 DEG C, a first composite rolled copper strip is obtained, and N is a positive integer larger than or equal to 2; and (2) the first composite rolled copper strip is subjected to a-pass secondary rolling at the temperature of 500-1070 DEG C or M layers of first composite rolled copper strips are stacked and then subjected to secondary composite rolling at the temperature of 500-1070 DEG C, M is a positive integer larger than or equal to 2, and a is a positive integer. According to the method, the excellent interface bonding degree between the copper-based graphene foil layers can be guaranteed, meanwhile, the intact material structure in the rolling process is guaranteed, the problem that the conductivity of the composite copper strip is low due to the defect of the material structure caused by a traditional rolling technology is solved, and therefore the conductivity of the composite copper strip is remarkably improved, and the service life of the composite copper strip is prolonged. Especially for a thick composite copper strip, it can be guaranteed that the composite copper strip has high conductivity, and the application range of the composite copper strip is widened.

Description

Technical Field

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

[0002] Copper and copper alloys have long been widely used as the main conductor materials for wires, motors and electronic packaging. The performance of wires has been developed to the greatest extent, and the improvement of their conductivity has reached its limit. Graphene has a unique hexagonal carbon atom grid structure and extremely high electron mobility, which makes it theoretically superior to pure copper in conductivity. High-quality, large-area graphene can be prepared on a large scale on the surface of a copper substrate through a chemical vapor deposition (CVD) process, and the thickness of the copper substrate can be reduced to a thickness of tens to tens of microns, such as 10 to 40 microns. This can increase the proportion of graphene in the material on a large scale and obtain the layered characteristics of current carrying along the in-plane direction of the graphene.

[0003] However, the application scope of single-layer copper-based graphene composites with a thickness of micron level is relatively limited. Multi-layer composites to form copper-based graphene composites can prepare composite materials with a scale of mm to cm, and give full play to graphene as a high conductivity enhancer to achieve high conductivity of copper-based materials, which is of great significance for energy conservation, emission reduction and the development of cutting-edge manufacturing industries.

[0004] The rolling composite method has low cost, high output, high dimensional accuracy, and relatively mature technology and equipment, making it easy to realize large-scale industrial production of multi-layer copper-based graphene composite materials.

[0005] However, the electrical conductivity of composite copper materials prepared by the current rolling process is generally not significantly improved. In particular, the electrical conductivity of thicker copper-based materials prepared by using more layers of copper-based graphene through a single composite rolling process is significantly lower. This defect seriously restricts the application of thick copper-based graphene composite materials.

[0006] At the same time, in order to obtain products with a certain thickness, under the premise of a certain graphene content, a large number of single-layer raw materials need to be unrolled, aligned and stacked at the same time to form a thick product. For example, a 4mm thick product requires more than 160 layers of independent 0.025mm copper foil for one stacking and compounding. The equipment used is highly complex, large in size, difficult to control, high in single batch cost and high in risk, which seriously restricts the production of thick-grade copper-based graphene composite materials. Summary of the invention

[0007] The present invention aims to solve one of the technical problems in the prior art at least to a certain extent. To this end, one object of the present invention is to provide a composite copper strip and a preparation method thereof.

[0008] In a first aspect of the present invention, the present invention provides a method for preparing a composite copper strip, the method comprising: (1) laminating N layers of copper-based graphene foil and then performing a composite rolling at 500-1070° C. to obtain a first composite rolled copper strip, where N is a positive integer greater than or equal to 2; (2) The first composite rolled copper strip is subjected to a secondary rolling at 500-1070° C. or M layers of the first composite rolled copper strip are stacked and then subjected to secondary composite rolling at 500-1070° C., where M is a positive integer greater than or equal to 2 and a is a positive integer.

[0009] According to the preparation method of the above-mentioned composite copper strip provided by the present invention, first, N layers of copper-based graphene foil are stacked and subjected to a composite rolling at 500-1070°C. Through the first composite rolling at the above temperature, the N layers of copper-based graphene foil can be preliminarily composited, which can effectively avoid defects in the material structure during the composite rolling process, while ensuring a good contact interface between each copper-based graphene foil layer.

[0010] The inventors found that although good interface contact can be formed by applying high pressure by only using one composite rolling, non-in-plane wrinkles and folding defects are generated at the interface due to the high pressure composite, which seriously affects the improvement of the electrical conductivity of the copper strip, especially for the preparation of thicker copper strips, the electrical conductivity of the thick copper strips is significantly lower.

[0011] Based on this, the inventor unexpectedly discovered that by performing a secondary rolling of the first composite rolled copper strip at 500-1070°C or stacking M layers of the first composite rolled copper strip at 500-1070°C for secondary composite rolling, the rolling pressure requirement can be effectively reduced through a secondary rolling or secondary composite rolling, so that good interface bonding is maintained between the layers, especially for thick copper strips, which can ensure that the product structure is consistent and has excellent electrical conductivity.

[0012] For example, the temperature of the N-layer copper-based graphene foil is 500°C, 600°C, 700°C, 800°C, 900°C, 1070°C, etc., or the range between any two of the above values; the temperature of the first composite rolled copper strip is 500°C, 600°C, 700°C, 800°C, 900°C, 1070°C, etc., or the range between any two of the above values.

[0013] It can be understood by those skilled in the art that in step (1), when N layers of copper-based graphene foil are stacked for a composite rolling, the thickness of the N layers of copper-based graphene foil used does not have to be exactly the same, and copper-based graphene foils of different thicknesses can be stacked for the first composite rolling. Similarly, in step (2), when M layers of the first composite rolled copper strips are stacked for a second composite rolling, the thickness of each first composite rolled copper strip can be the same or different.

[0014] In some embodiments of the present invention, annealing is performed after rolling. Specifically, annealing is performed after forming the strip of the first composite rolling, the second composite rolling or the second rolling to eliminate the metal structure refined by rolling and meet the requirements of the next processing or target application. For example, high temperature annealing is performed in a vacuum furnace or an inert atmosphere furnace, with a heating temperature of 250-600°C and a holding time of 10min-600min.

[0015] It should be noted that the traditional continuous composite production of graphene copper-based composite strips adopts hot rolling composite technology, and its production process includes five main steps: uncoiling, heating, rolling, cooling, and coiling. The present invention mainly improves the rolling process. For the parameter conditions of other processes, technical personnel in this field can choose according to actual conditions.

[0016] As an example, the unwinding process includes: the composite raw material is rolled on a metal cylinder, and an air shaft is used to connect a servo motor through a coupling to control the unwinding speed of the material coil to be no greater than a reference speed, so as to generate a preset tension on the unwinding metal foil; the unwinding tension is controlled by the real-time torque of the unwinding motor * the real-time coil diameter, or by a three-point beam test; the displacement of part of the unwinding copper foil layer is controlled by an S-type roller loop; the above-mentioned material coil and servo motor system are installed on a horizontal slide controlled and positioned by a stepper motor, so that the unwinding metal foil is aligned with the rolling line; the edge position of the unwinding metal foil is detected by a photoelectric sensor or a contact sensor to realize automatic centering and limit control; the material strip is riveted to the multi-layer metal foil strip by a single-layer or multi-layer metal lead belt, enters the coiler through the main rolling line, and pulls the multi-layer material strip through the belt; the tension of the unwinding multi-layer material strip is controlled by an S-type roller loop, and the rolling reference speed is stabilized; after unwinding, the neatly aligned multi-layer raw material is supported and transported by a horizontally movable stainless steel support belt, the thickness of the stainless steel support belt is 0.05~0.5mm, and the support belt is separated and independently recovered before heating.

[0017] As an example, the heating process includes: after uncoiling, multiple layers of raw materials are stacked and placed in a row to enter a single-temperature zone or multi-temperature zone heating furnace protected by argon or nitrogen. Due to the balance between the heating capacity in the furnace and the heat dissipation after leaving the furnace, the raw material temperature leaving the furnace is 400~1070℃, and the heating zone of the heating furnace and the composite rolling of the rolling mill form a closed area. The main rolling line entrance of the heating furnace and the main rolling line exit of the rolling section have a switchable protection structure; (1) through vacuum exhaust-argon / nitrogen filling and blowing cycle operation once or multiple times until the oxygen content in the furnace is lower than 0.1vol% and the positive pressure in the heating zone is maintained at 50-5000Pa; (2) at a heating rate of 5℃ / min, the furnace heating temperature is heated to 850~1070℃ and the rolling roller is heated to 400~950℃; (3) after the heating furnace is heated to the set temperature and the material strip is preheated, the coiler, rolling mill, uncoiling and support are started in sequence for rolling composite.

[0018] As an example, the rolling process includes: (1) the heated multi-layer raw material is bitten into the rolling roller; (2) the upper and lower rolling rollers are flat rollers or convex and concave rollers; (3) the surface linear speed of the rolling roller is the reference speed; (4) during rolling and compounding, in order to meet the requirements of compounding of multi-layer raw materials, the compounding speed is controlled below 50 mm / s; (5) the extension (reduction) rate of the first compounding is adjusted according to the number of compounding layers, and the more layers, the smaller the extension (reduction) rate; (6) the copper strip has front and rear tension during the rolling and compounding process.

[0019] As an example, the winding and curling process includes: (1) the winding reel is fixed on a horizontally movable slide, and a photoelectric sensor or a contact sensor detects the edge position of the metal strip before winding to achieve uniform curling of the coiled metal strip; (2) the winding speed is not less than the reference speed, and a preset tension is generated on the wound metal strip; the winding tension is controlled by the real-time torque of the winding motor * the real-time winding diameter, or by a three-point beam test; the tension and speed of the composite strip are stabilized by an S-shaped roller loop.

[0020] Those skilled in the art can understand that, the primary composite rolling is the process of stacking and rolling N layers of copper-based graphene foil to form a copper strip; the secondary composite rolling refers to the composite rolling of stacking and re-coiling two or more layers of copper strips formed by the primary composite rolling; the secondary rolling is the process of repeatedly rolling the copper strip formed by the primary composite rolling or the secondary composite rolling; a secondary rolling is a secondary rolling performed a times, for example, a is 2, and the copper strip formed by the primary composite rolling or the secondary composite rolling is first subjected to the first secondary rolling, and then immediately subjected to the second secondary rolling.

[0021] In some embodiments of the present invention, a composite rolling process includes coil uncoiling preparation, tubular furnace heating, coil rolling speed determination, and roll rolling.

[0022] As an example, the preparation for uncoiling a coil includes: first, a 0.2mm thick stainless steel lead tape is passed through the closed working area surrounded by the heating furnace and the rolling mill, the lead tape outlet is connected to the coiler, and the other end is riveted together with the coil heads of N coils. The N coils are uncoiled and stacked on the self-driven stainless steel support belt.

[0023] As an example, determine the rolling speed of the material coil: heat the tubular furnace, calculate the running speed of the raw material in the tubular furnace according to the temperature of the tubular furnace and the heating cycle and working section length of the tubular furnace required for uniformly heating the N-layer copper-based graphene foil material to the preset temperature, and use 90% of this running speed as the speed for subsequent rolling and compounding, that is, under the stretching of the lead belt and the support of the support belt, pass the raw material through the tubular heating furnace at the rolling and compounding speed, and the temperature of the raw material reaches the preset temperature (rolling temperature) when it comes out of the furnace.

[0024] As an example, roller rolling: after the leader tape carries the head of the raw material through the roller gap formed by the rollers heated to a preset temperature, the roller gap is adjusted to deform the raw material, and under the action of high temperature and pressure, a first composite rolled copper strip is formed.

[0025] Further, for example, when the value of N is 20 and the temperature of a composite rolling is 850°C, the tubular furnace can be heated to 850°C at a heating rate of 5°C / min. According to the heating cycle required for the 20 layers of copper-based graphene foil materials to be uniformly heated to 850°C obtained from the experiment and the length of the working section of the tubular furnace, the running speed of the raw material in the tubular furnace is calculated, and 90% of this running speed is used as the speed of subsequent rolling composite, and the speed is calculated to be 6mm / s. That is, under the stretching of the lead belt and the support of the support belt, the raw material passes through the tubular heating furnace at a speed of 6mm / s, and the raw material temperature is 850°C when it comes out of the furnace; further, after the lead belt carries the raw material head through the roller gap formed by the roller heated to 850°C, the roller gap is adjusted to press down the 20 layers of copper-based graphene foil materials, and the first composite rolled copper strip is formed under the action of high temperature and pressure.

[0026] In some embodiments of the present invention, the reduction rate of the N-layer copper-based graphene foil after the one-time composite rolling is 0-10%, preferably 0-5%. For example, the reduction rate is 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc., or a range between any two of the above values. By controlling the reduction rate of the N-layer copper-based graphene foil after the one-time composite rolling to be within the above range, a horizontally continuous layered interface structure (such as Figure 1 As shown, the reduction rate of a composite rolling pass is 4%, flat), avoiding the formation of wrinkles and folding defects (such as Figure 2 As shown, the reduction rate of one composite rolling pass is 12%, wrinkles). It should be noted that the reduction rate = (thickness of N layers of copper-based graphene foil - thickness of the first composite rolled copper strip) / thickness of N layers of copper-based graphene foil.

[0027] In some embodiments of the present invention, the secondary rolling is to raise the temperature of the first composite rolled copper strip to a set temperature, and then set the rolling speed under inert gas protection, and achieve a set deformation rate under a certain pressure. For example, in the secondary rolling, the temperature of the first composite rolled copper strip is 950°C, argon gas is used to protect the copper strip from oxidation, the rolling speed is about 8mm / s, and the reduction rate is 8%.

[0028] In some embodiments of the present invention, the thickness of a single layer of the copper-based graphene foil is 5 μm-100 μm, preferably 15 μm-50 μm.

[0029] In some embodiments of the present invention, N is a positive integer not less than 4, preferably N is a positive integer greater than 20, and more preferably N is a positive integer of 21-40. For example, N is 4, 10, 21, 25, 30, 40, etc., or a range between any two of the above values. The inventors found that when the number of layers of the copper-based graphene foil used is large, for example, the number of layers is greater than 20, the conventional rolling process cannot guarantee a suitable reduction rate, or even if the reduction rate is appropriate, it is easy to cause material tissue defects, thereby reducing the conductivity of the composite copper strip. When the present invention prepares a copper strip with a large number of copper-based graphene foils, it not only effectively avoids the generation of tissue defects, but also has good contact between the layers, further ensuring that the thicker grade copper strip has a higher conductivity.

[0030] In some embodiments of the present invention, after the second rolling of the a pass, the reduction rate of the N-layer copper-based graphene foil is 3%-50%, preferably 10%-30%. For example, the reduction rate is 5%, 10%, 12%, 15%, 18%, 20%, 25%, 30%, 40%, 50%, etc., or a range between any two of the above values. By controlling the reduction rate of the N-layer copper-based graphene foil within the above range, good interface bonding (such as Figure 3 As shown, the overall reduction rate is 20%, flat and well-compounded), avoiding poor interface bonding (such as Figure 4 As shown, the overall reduction rate is 2%, flatness and poor lamination). It should be noted that the reduction rate = (thickness of N layers of copper-based graphene foil - thickness of the copper strip obtained after a secondary rolling) / thickness of N layers of copper-based graphene foil.

[0031] Preferably, a is a positive integer of 1-5.

[0032] It should be noted that the reduction rate of the material in each secondary rolling of a pass does not have to be the same. The technical personnel in this field can adjust the specific reduction rate of each pass according to actual conditions. It is only necessary to control the reduction rate of the N-layer copper-based graphene foil to be 3%-50% after the secondary rolling of a pass.

[0033] In some embodiments of the present invention, after stacking the M layers of the first composite rolled copper strips, a second composite rolling is performed at 500-1070°C. After the second composite rolling, the reduction rate of the M×N layers of copper-based graphene foil is 3%-30%, preferably 5%-15%. For example, the reduction rate is 5%, 10%, 12%, 15%, 20%, 30%, etc., or a range between any two of the above values. By controlling the reduction rate of the copper-based graphene foil of the M×N layers within the above range, a good interface bonding between the two layers can be formed (such as Figure 5 As shown, the reduction rate is 6%, M is 2, flatness and good composite), avoiding delamination at the interface (such as Figure 6As shown, the reduction rate is 2%, the center of the interface of the copper strip is delaminated, M is 2, flatness, and poor composite). It should be noted that the reduction rate = (M×N layers of copper-based graphene foil thickness - copper strip thickness obtained after secondary composite rolling) / M×N layers of copper-based graphene foil thickness. For the secondary composite rolling using multiple layers of first composite rolled copper strips stacked, the thickness of each layer of the first composite rolled copper strip does not have to be exactly the same.

[0034] Those skilled in the art can understand that the equipment and process used in the secondary composite rolling can be the same as those used in the primary composite rolling, and the specific process parameters are adjusted according to actual conditions.

[0035] Preferably, M is a positive integer of 2-5, preferably 2.

[0036] In some embodiments of the present invention, the method further comprises: performing b-pass secondary rolling on the first copper strip obtained by stacking M layers of the first composite rolled copper strips and performing secondary composite rolling.

[0037] Preferably, during the secondary rolling in pass b, the temperature of the first copper strip is 850-1070°C.

[0038] Preferably, b is a positive integer of 1-3.

[0039] Preferably, after the second rolling of the b-pass, the reduction rate of the M×N layers of copper-based graphene foil is 5%-50%, and more preferably 10%-30%. It should be noted that the reduction rate = (thickness of the M×N layers of copper-based graphene foil - thickness of the copper strip obtained after the second rolling of the b-pass) / thickness of the M×N layers of copper-based graphene foil.

[0040] In some embodiments of the present invention, the method further comprises: stacking M layers of the first composite rolled copper strips and performing secondary composite rolling to obtain K layers of the first copper strips, and then performing secondary composite rolling to obtain a second copper strip, and performing c-pass secondary rolling on the second copper strip. It can be understood by those skilled in the art that, for the preparation of a thicker copper strip, the above-mentioned multiple secondary composite rolling process can be used to increase the thickness of the copper strip, and finally the conductivity of the final copper strip is optimized by the c-pass secondary rolling process.

[0041] Preferably, K is a positive integer of 2-5, preferably 2.

[0042] Preferably, c is a positive integer of 1-3.

[0043] In some embodiments of the present invention, after the K layers of the first copper strips are stacked and subjected to secondary composite rolling, the reduction rate of the K×M×N layers of the copper-based graphene foil is 3%-30%, preferably 5%-15%. It should be noted that the reduction rate = (thickness of the K×M×N layers of copper-based graphene foil - thickness of the copper strip obtained after secondary composite rolling) / thickness of the K×M×N layers of copper-based graphene foil. When the K layers of the first copper strips are stacked and subjected to secondary composite rolling, the thickness of each layer of the first copper strip may not be exactly the same.

[0044] In some embodiments of the present invention, when the K layer and the first copper strip are stacked and subjected to secondary composite rolling, the temperature of the K layer and the first copper strip is 500-1070°C, preferably 850-1070°C.

[0045] In some embodiments of the present invention, after the second copper strip undergoes the c-pass secondary rolling, the reduction rate of the K×M×N layers of the copper-based graphene foil is 5%-50%, preferably 10%-30%. It should be noted that the reduction rate = (thickness of the K×M×N layers of copper-based graphene foil - thickness of the copper strip obtained after the c-pass secondary rolling) / thickness of the K×M×N layers of copper-based graphene foil.

[0046] In some embodiments of the present invention, during the secondary rolling of the c pass, the temperature of the second copper strip is, and the temperature of the first copper strip of the K layer is 500-1070°C, preferably 850~1070°C.

[0047] In a second aspect of the present invention, a composite copper strip is provided, and the composite copper strip is prepared by the above method, so that the composite copper strip has a perfect structure and high electrical conductivity.

[0048] Preferably, the thickness of the composite copper strip is 0.1 mm-20 mm, preferably 0.2 mm-10 mm, more preferably 0.5 mm-5 mm.

[0049] Preferably, the electrical conductivity of the composite copper strip is greater than 98% IACS, preferably 103% IACS-120% IACS, and more preferably 113% IACS-120% IACS. It should be noted that IACS is the international standard electrical conductivity of annealed copper at 20 degrees, that is, 58E6 S / m or 17.241nΩ·m.

[0050] The present invention has at least the following beneficial effects: The preparation method of the present invention can ensure excellent interface bonding between each layer of copper-based graphene foil, thereby significantly improving the electrical conductivity of the composite copper strip; on the other hand, it ensures the integrity of the material structure during the rolling process, overcomes the problem of low electrical conductivity of the composite copper strip caused by material structure defects caused by the traditional rolling process, thereby significantly improving the electrical conductivity of the composite copper strip, especially for thicker composite copper strips, it can ensure that the composite copper strip has a higher electrical conductivity, and broaden the application range of the composite copper strip. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the 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 creative work.

[0052] Figure 1 is a cross-sectional metallographic image of a first composite rolled copper strip obtained by a single hot composite rolling process according to an embodiment of the present invention; Figure 2 This is a cross-sectional metallographic diagram of a copper strip obtained by a single hot composite rolling process with a too large reduction ratio; Figure 3 is a cross-sectional metallographic image of the composite copper strip obtained after secondary rolling in pass a of the embodiment of the present invention; Figure 4 This is a cross-sectional metallographic diagram of a composite copper strip obtained by a too small reduction ratio of the secondary rolling in the a pass of the present invention; Figure 5 is a cross-sectional metallographic diagram of a composite copper strip obtained after secondary composite rolling according to an embodiment of the present invention; Figure 6 This is a cross-sectional metallographic diagram of a composite copper strip obtained by the secondary composite rolling with a too small reduction ratio according to the present invention; Figure 7 This is a metallographic image of the overall wrinkle defect characteristics of the composite copper strip after line splitting in Comparative Example 2 of the present invention; Figure 8 The cross-sectional metallographic image of the local wrinkles and composite defect characteristics of the composite copper strip of comparative example 3 of the present invention; Fig. 9 Photos of overall wrinkles and folding defects of the composite copper strip of Comparative Example 4 of the present invention. DETAILED DESCRIPTION

[0053] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making any creative work shall fall within the scope of protection of the present invention.

[0054] Example 1 This embodiment provides a composite copper strip, and the specific preparation process is as follows: (1) Material preparation: Copper-based graphene foil material roll, the inner diameter of the roll is 76 mm, the outer diameter is 200 mm, the total length is 1000 meters, and the number of rolls is 20. The thickness of a single-layer copper-based graphene foil material is 35 μm and the width is 40 mm.

[0055] (2) Unwinding and stacking N = 20 coils to obtain 20 layers of copper-based graphene foil material, heating the N = 20 layers of copper-based graphene foil material to 850° C., and rolling the N = 20 layers of copper-based graphene foil material with a roller at 850° C. so that the reduction rate of the N = 20 layers of copper-based graphene foil material is 5%, thereby obtaining a first composite rolled copper strip.

[0056] (3) The first composite rolled copper strip obtained in step (2) is further heated to 950° C., and subjected to three secondary rolling at 950° C. to obtain a composite copper strip. Argon is used to protect the first composite rolled copper strip from oxidation, the rolling speed is about 8 mm / s, and the reduction rates of the three secondary rollings are 15%, 20% and 24% respectively, that is, the thickness of the composite copper strip with N=20 after the three secondary rollings is 0.54 mm.

[0057] The conductivity of the flat wire cut from the composite copper strip after rolling was tested to be 117% IACS.

[0058] Example 2 This embodiment provides a composite copper strip, and the specific preparation process is as follows: (1) Material preparation: Copper-based graphene foil material roll, the inner diameter of the roll is 76 mm, the outer diameter is 200 mm, the total length is 1000 meters, and the number of rolls is 25. The thickness of a single layer of copper-based graphene foil material is 35 μm and the width is 40 mm.

[0059] (2) Unwinding and stacking N=25 coils to obtain N=25 layers of copper-based graphene foil material, heating the N=25 layers of copper-based graphene foil material to 850° C., and rolling the N=25 layers of copper-based graphene foil material with a roller at 850° C. so that the reduction rate of the N=25 layers of copper-based graphene foil material is 5%, thereby obtaining a first composite rolled copper strip.

[0060] (3) The first composite rolled copper strip obtained in step (2) is further heated to 950° C., and subjected to three secondary rolling at 950° C. to obtain a composite copper strip. Argon is used to protect the first composite rolled copper strip from oxidation, the rolling speed is about 8 mm / s, and the pass reduction rates of the three secondary rolling passes are 15%, 20% and 24% respectively, that is, the thickness of the composite copper strip with N=25 after the three secondary rolling passes is 0.68 mm.

[0061] The conductivity of the flat wire cut from the composite copper strip after rolling was tested to be 119% IACS.

[0062] Example 3 This embodiment provides a composite copper strip, and the specific preparation process is as follows: (1) Material preparation: Copper-based graphene foil material roll, the inner diameter of the roll is 76 mm, the outer diameter is 200 mm, the total length is 1000 meters, and the number of rolls is 40. The thickness of a single layer of copper-based graphene foil material is 18 μm and the width is 40 mm.

[0063] (2) Unwinding and stacking N = 40 coils to obtain N = 40 layers of copper-based graphene foil material, heating the N = 40 layers of copper-based graphene foil material to 850° C., and rolling the N = 40 layers of copper-based graphene foil material with a roller at 850° C. so that the reduction rate of the N = 40 layers of copper-based graphene foil material is 4%, thereby obtaining a first composite rolled copper strip.

[0064] (3) Repeating steps (1) to (2) for multiple times, the two N=40 first composite rolled copper strips obtained in step (2) are uncoiled and stacked through M=2 material coils and then composite rolled for a second time, the M=2 first composite rolled copper strips are heated to 950°C and rolled by a roller at 950°C; after the second composite rolling, the reduction rate of the M×N=80 layers of copper-based graphene foil is 8%, and the thickness of the composite copper strip is 1.32 mm.

[0065] The conductivity of the rolled composite copper strip slit flat wire was tested to be 109% IACS.

[0066] Example 4 This embodiment provides a composite copper strip, and the specific preparation process is as follows: (1) Material preparation: Copper-based graphene foil material roll, the inner diameter of the roll is 76 mm, the outer diameter is 200 mm, the total length is 1000 meters, and the number of rolls is 80. The thickness of a single-layer copper-based graphene foil material is 18 μm and the width is 40 mm.

[0067] (2) Unwinding and stacking N = 80 coils to obtain 80 layers of copper-based graphene foil material, heating the N = 80 layers of copper-based graphene foil material to 850° C., and rolling the N = 80 layers of copper-based graphene foil material with a roller at 850° C. so that the reduction rate of the N = 80 layers of copper-based graphene foil material is 3%, thereby obtaining a first composite rolled copper strip.

[0068] (3) The first composite rolled copper strip obtained in step (2) is further heated to 950° C., and subjected to three secondary rolling at 950° C. to obtain a composite copper strip. Argon is used to protect the first composite rolled copper strip from oxidation, the rolling speed is about 10 mm / s, and the reduction rates of the three secondary rollings are 13%, 20% and 24% respectively, that is, the thickness of the composite copper strip with N=80 after the three secondary rollings is 1.11 mm.

[0069] The conductivity of the flat wire cut from the composite copper strip after rolling was tested to be 108% IACS.

[0070] Example 5 This embodiment provides a composite copper strip, and the specific preparation process is as follows: The M×N=80-layer two-composite rolled copper strip obtained in step (3) of Example 3 was further heated to 950°C and subjected to two secondary rolling at 950°C to obtain a composite copper strip. Argon was used to protect the second composite rolled copper strip from oxidation, the rolling speed was about 10 mm / s, and the reduction ratios of the two secondary rollings were 20% and 24% respectively, that is, the thickness of the M×N=80 composite copper strip after the two secondary rollings was 1.10 mm.

[0071] The conductivity of the rolled composite copper strip slit flat wire was tested to be 118% IACS.

[0072] Example 6 This embodiment provides a composite copper strip, and the specific preparation process is as follows: (1) Step (3) of Example 3 is repeated multiple times, and the obtained K=2 second composite rolled copper strips with M×N=80 are subjected to secondary composite rolling by uncoiling and laminating K=2 material coils, and the K=2 second composite rolled copper strips are heated to 950°C and rolled by a roller at 950°C. After the secondary composite rolling, the reduction rate of K×M×N=160 layers of copper-based graphene foil is 15%, thereby obtaining a third composite copper strip.

[0073] (2) The third composite rolled copper strip obtained in step (4) is further heated to 950° C., and is subjected to three secondary rollings at 950° C. to obtain a composite copper strip. Argon is used to protect the third composite rolled copper strip from oxidation, the rolling speed is about 10 mm / s, and the reduction ratios of the three secondary rollings are 25%, 30% and 35% respectively, that is, after the three secondary rollings, the thickness of the K×M×N=160 composite copper strip is 1.87 mm.

[0074] The conductivity of the flat wire cut from the composite copper strip after rolling was tested to be 116% IACS.

[0075] Comparative Example 1 This comparative example provides a composite copper strip, and the specific preparation process is as follows: (1) The raw material is a copper-based graphene foil material roll with a thickness of 35 μm and a width of 40 mm. The inner diameter of the roll is 76 mm, the outer diameter is 200 mm, the total length is 100 meters, and the number of rolls is 20; (2) First rolling: at room temperature, the 20 layers of metal copper foil with graphene grown thereon are rolled in a manner such that the surfaces to be composited overlap each other until the reduction rate of the 20 layers of metal copper foil with graphene grown thereon is 8%, thereby obtaining a pre-composite metal copper-graphene billet having a thickness of 0.64 mm after cold rolling composite; (3) Second rolling: The pre-composite metal copper-graphene strip obtained by the first rolling was rolled under vacuum at 850°C, and the reduction rate of the 20-layer copper-based graphene foil was 13%, that is, the thickness after hot rolling was 0.61 mm.

[0076] The rolled strip was cut into flat wires, and the tested conductivity was 113% IACS.

[0077] Comparative Example 2 This comparative example provides a composite copper strip, and the specific preparation process is as follows: (1) The raw material is a copper-based graphene foil material roll with a thickness of 25 μm and a width of 40 mm. The inner diameter of the roll is 76 mm, the outer diameter is 200 mm, the total length is 100 meters, and the number of rolls is 80; (2) First rolling: At room temperature, 80 layers of metal copper foil grown with graphene are rolled in a manner such that the surfaces to be composited overlap each other until the reduction rate of the 80 layers of metal copper foil grown with graphene is 10%, thereby obtaining a pre-composite metal copper-graphene blank. The thickness after cold rolling composite is 1.80 mm, and the copper strip forms internal folding and wrinkling defects due to cold rolling defects; (3) Second rolling: The pre-composite metal copper-graphene strip obtained by the first rolling was vacuum rolled at 850°C, and the reduction rate of the 80-layer copper-based graphene foil was 12%, that is, the thickness after hot rolling was 1.76 mm.

[0078] After rolling, the strip is cut into flat wires, and the tested conductivity is 103% IACS. There are a lot of wrinkled interfaces, such as Figure 7 shown.

[0079] Comparative Example 3 This comparative example provides a composite copper strip, and the specific preparation process is as follows: (1) The raw material is a copper-based graphene foil material roll with a thickness of 25 μm and a width of 40 mm. The inner diameter of the roll is 76 mm, the outer diameter is 200 mm, the total length is 100 meters, and the number of rolls is 100; (2) First rolling: at room temperature, the 100 layers of metal copper foil grown with graphene are rolled in a manner such that the surfaces to be composited overlap each other until the reduction rate of the 100 layers of metal copper foil grown with graphene is 8%, thereby obtaining a pre-composite metal copper-graphene blank, the thickness of which after cold rolling composite is 1.66 mm, and the pre-composite strength is poor; (3) Second rolling: The pre-composite metal copper-graphene strip obtained by the first rolling was rolled under vacuum at 850°C, and the reduction rate of the 100-layer copper-based graphene foil was 14%, that is, the thickness after hot rolling was 1.55 mm.

[0080] After rolling, the strip is cut into flat wires, and the tested conductivity is 108% IACS. There are a few wrinkle boundaries, and the composite degree is poor. Figure 8 shown.

[0081] Comparative Example 4 This comparative example provides a composite copper strip, and the specific preparation process is as follows: (1) Material preparation: Copper-based graphene foil material roll, the inner diameter of the roll is 76 mm, the outer diameter is 200 mm, the total length is 1000 meters, the number of rolls is 100, the thickness of a single-layer copper-based graphene foil material is 18 μm, and the width is 40 mm.

[0082] (2) 100 coils are unrolled and stacked to obtain 100 layers of copper-based graphene foil materials. The 100 layers of copper-based graphene foil materials are heated to 850°C and rolled by a roller at 850°C, so that the reduction rate of the 100 layers of copper-based graphene foil materials is 28%, and a composite rolled copper strip is obtained. The thickness of the composite rolled copper strip is 1.30 mm. During the rolling, overall wrinkles and folding defects caused by high pressure are formed, such as Fig. 9 shown.

[0083] The rolled strip is cut into flat wires, and the tested conductivity is 102% IACS.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a composite copper strip, characterized in that: include: (1) laminating N layers of copper-based graphene foil and then performing a composite rolling at 500-1070° C. to obtain a first composite rolled copper strip, where N is a positive integer greater than or equal to 2; (2) The first composite rolled copper strip is subjected to a secondary rolling at 500-1070° C. or M layers of the first composite rolled copper strip are stacked and then subjected to secondary composite rolling at 500-1070° C., where M is a positive integer greater than or equal to 2 and a is a positive integer.

2. The method for preparing the composite copper strip according to claim 1, characterized in that: After the first composite rolling, the reduction rate of the N layers of the copper-based graphene foil is 0-10%, preferably 0-5%.

3. The method according to claim 1, characterized in that: The thickness of the single-layer copper-based graphene foil is 5 μm-100 μm, preferably 15 μm-50 μm; And / or, N is a positive integer not less than 4, preferably N is a positive integer greater than or equal to 20, and more preferably N is a positive integer of 21-40.

4. The method for preparing the composite copper strip according to claim 1, characterized in that: After the secondary rolling of the a pass, the reduction rate of the N layers of the copper-based graphene foil is 3%-50%, preferably 10%-30%; And / or, a is a positive integer from 1 to 5.

5. The method for preparing the composite copper strip according to claim 1, characterized in that: After the secondary composite rolling, the reduction rate of the M×N layers of the copper-based graphene foil is 3%-30%, preferably 5%-15%; And / or, M is a positive integer of 2-5, preferably 2.

6. The method for preparing the composite copper strip according to any one of claims 1 to 5, characterized in that: Also includes: The first copper strip obtained by stacking M layers of the first composite rolled copper strips and performing secondary composite rolling is subjected to b-pass secondary rolling; Preferably, during the secondary rolling of the b pass, the temperature of the first copper strip is 850-1070° C.; preferably, b is a positive integer of 1-3; Preferably, after the secondary rolling in the b-pass, the reduction rate of the M×N layers of the copper-based graphene foil is 5%-50%, more preferably 10%-30%.

7. The method for preparing the composite copper strip according to any one of claims 1 to 5, characterized in that: Also includes: The first composite rolled copper strips are stacked and subjected to secondary composite rolling to obtain K layers of first copper strips, which are then stacked and subjected to secondary composite rolling to obtain a second copper strip, and the second copper strip is subjected to c secondary rolling; Preferably, K is a positive integer of 2-5, preferably 2; Preferably, c is a positive integer of 1-3.

8. The method for preparing the composite copper strip according to claim 7, characterized in that: After the first copper strip of the K layer is stacked and subjected to secondary composite rolling, the reduction rate of the copper-based graphene foil of the K×M×N layer is 3%-30%, preferably 5%-15%; And / or, when the K layer and the first copper strip are stacked and subjected to secondary composite rolling, the temperature of the K layer and the first copper strip is 500-1070°C, preferably 850-1070°C.

9. The method for preparing the composite copper strip according to claim 7, characterized in that: After the second copper strip is subjected to c-pass secondary rolling, the reduction rate of the K×M×N layers of the copper-based graphene foil is 5%-50%, preferably 10%-30%; And / or, during the secondary rolling of the c-th pass, the temperature of the second copper strip is 500-1070°C, preferably 850-1070°C.

10. A composite copper strip, characterized in that: The composite copper strip is prepared by the method for preparing the composite copper strip according to any one of claims 1 to 9; Preferably, the thickness of the composite copper strip is 0.1 mm-20 mm, preferably 0.2 mm-10 mm, more preferably 0.5 mm-5 mm; Preferably, the electrical conductivity of the composite copper strip is greater than 98% IACS, preferably 103% IACS-120% IACS, and more preferably 113% IACS-120% IACS.

Images