Three-layer composite material with liquid copper as core material and its production process and application

Abstract

The present application relates to a kind of liquid copper as core material three-layer composite and its production process and its application, production process includes the following steps: start rolling mill and make two strip materials pass through roll gap, the strip material includes the inner wall of outer wall facing the rolling mill and the inner wall of the side opposite to the rolling mill, the inner wall of two strip materials is covered with copper layer, liquid copper is casted between the inner wall of two strip materials by casting nozzle, liquid copper is cast-rolled composite with the strip material through the rolling mill to form the three-layer composite, and the liquid copper is pure copper or copper alloy.The scheme can avoid the formation of shrinkage and shrinkage and other defects in the bonding surface, so it has better interface bonding strength and thermal conductivity coefficient;Continuous brittle intermetallic compound is inhibited to be generated, so that brittle intermetallic compound is uniformly dispersed in the bonding surface, and the bonding strength and toughness of the composite material are improved by crack deflection and bridging mechanism.

Description

Technical Field

[0001] This invention relates to the field of metal composite material preparation, and in particular to a three-layer composite material with liquid copper as the core material, its production process, and its application. Background Technology

[0002] In his paper (Zhao Ridong, Jiao Zishuai, Yan Meng, et al. Study on solid-liquid-solid casting-rolling composite preparation process of 4343 / 3003 / 4343 aluminum alloy brazed plate [J]. Hot Working Technology, 2024, 53(17):122-126.), Zhao Ridong proposed a solid-liquid-solid composite preparation process for preparing composite plates. After the core material is melted into a liquid state, it is fed into the roll gap together with the cladding strips on both sides. Under the high temperature and high pressure of the casting-rolling process, a firm bond is achieved between the core material and the cladding. However, this method is only suitable for the preparation of composite materials in which both the core material and the cladding are aluminum. If it is applied to the preparation of composite materials in which the core material and the cladding material are different, many technical problems will be encountered. When the core material and cladding material are different (e.g., copper / aluminum, copper / titanium), a brittle layer may form. This brittle layer is prone to fracture under stress, leading to delamination. Furthermore, if the wettability of the core and cladding materials is poor (copper has poor wettability with aluminum, titanium, and steel), the liquid core material cannot adequately fill the surface gaps of the cladding material to form a physically interlocking structure in the intense heat exchange environment of casting and rolling. In summary, the process of producing three-layer composite materials using liquid copper as the core material via casting and rolling presents many unresolved problems.

[0003] Therefore, it is necessary to propose a three-layer composite material with liquid copper as the core material, its production process, and its application. Summary of the Invention

[0004] Based on this, it is necessary to propose a three-layer composite material with liquid copper as the core material, its production process, and its application.

[0005] The first aspect of the present invention provides a production process for a three-layer composite material using liquid copper as the core material, characterized by comprising the following steps: starting a rolling mill to allow two strips to pass through a roll gap, the strips comprising an outer wall facing the rolling mill and an inner wall facing away from the rolling mill, both inner walls of the two strips being covered with a copper layer, liquid copper being poured into the space between the inner walls of the two strips through a casting nozzle, the liquid copper being cast and rolled together with the strips through the rolling mill to form the three-layer composite material, wherein the liquid copper is pure copper or a copper alloy.

[0006] The above-mentioned scheme pre-defines a copper layer on the inner wall of the strip. This copper layer acts as a buffer layer, preventing the direct formation of continuous brittle intermetallic compounds (such as CuTi) when the liquid copper comes into contact with the strip in the casting zone. After the copper layer and liquid copper come into contact, rapid heat conduction occurs, causing the copper layer to heat up to the semi-solid temperature and form semi-solid copper. Under rolling pressure, the semi-solid copper can uniformly fill the micro-gaps on the surface of the strip to form a continuous contact interface. The small volume shrinkage of the semi-solid copper after cooling can avoid defects such as shrinkage cavities and porosity at the bonding surface. Therefore, it has better interfacial bonding strength and thermal conductivity. In the rolling zone, the solid phase of the semi-solid copper restricts the continuous contact between the liquid phase and the strip surface, causing the brittle intermetallic compounds formed at the interface to be discretely distributed. Under the subsequent rolling pressure, the discretely distributed brittle intermetallic compounds are further reduced and dispersed at the bonding surface. Through crack deflection and bridging mechanisms, the bonding strength and toughness of the composite material are improved.

[0007] Furthermore, the sum of the masses of the copper layers of the two strips is 'a', the casting mass of the liquid copper is 'b', and the ratio of 'a' to 'b' is 1:(5-10). By controlling the mass ratio of liquid copper to copper layers, it can be ensured that the copper layers can obtain sufficient heat from the liquid copper to transform into a semi-solid state; if the ratio is too high, the copper layers may completely melt into a liquid state, and if the ratio is too low, the copper layers may not completely transform into a semi-solid state.

[0008] Furthermore, the average thickness of the copper layer is 0.1-0.8 mm. If the thickness is too thin, the copper layer melts rapidly into a liquid state in the casting zone, at which point the liquid copper can quickly form a continuous brittle intermetallic compound with the strip surface; if the thickness is too thick, the copper layer may not be completely converted into a semi-solid state when entering the rolling zone, and the copper layer continues to inhibit the formation of brittle intermetallic compounds, affecting the metallurgical bonding between the core layer and the strip.

[0009] Furthermore, the copper layer is prepared by pouring a semi-solid copper paste onto the inner wall of the strip to solidify and form the copper layer. The semi-solid copper paste can form a tight bond with the strip, preventing the formation of pores or shrinkage cavities. Simultaneously, the solid particles in the semi-solid copper paste occupy the interface region, reducing the contact area between the liquid copper and the strip, thus suppressing the formation of continuous brittle intermetallic compounds. Furthermore, the copper layer obtained in this way has equiaxed grains, which can rapidly revert to a semi-solid copper containing equiaxed grains after heating to the semi-solid temperature, exhibiting better fluidity.

[0010] Furthermore, the solid fraction of the semi-solid copper paste is 40-60%. Using a semi-solid copper paste with a higher solid fraction can further suppress the formation of continuous brittle intermetallic compounds.

[0011] Furthermore, the inner wall of the strip is roughened to a roughness of 0.1-3 μm. This roughening process increases the contact area between the semi-solid copper and the strip, and provides a physical anchoring effect.

[0012] Furthermore, copper ingots or copper alloy ingots are heated to 50-120°C above the liquidus line to obtain liquid copper. The liquid copper is then degassed, slag removed, and deoxidized. The composition of the liquid copper is tested, and the qualified liquid copper is kept at a constant temperature. By controlling the temperature of the liquid copper, energy consumption can be reduced, and the heat exchange rate between the liquid copper and the copper layer can be controlled to prevent the copper layer from completely melting into a liquid state.

[0013] Furthermore, the parameters for the casting-rolling composite process are: continuous casting speed of 1-2 m / min and rolling pressure of 400,000 N-800,000 N. High-speed continuous casting can improve production efficiency, but it is also necessary to avoid excessively low casting rates that could lead to uneven solidification of molten copper and thus affect interfacial bonding. A higher rolling pressure is required to promote further breakup and dispersion of brittle intermetallic compounds.

[0014] Furthermore, the two strips are independently selected from any one of titanium strip, nickel strip, aluminum strip, titanium alloy strip, steel strip, nickel alloy strip, and aluminum alloy strip. This solution is applicable to the production of various composite materials, especially when the strip contains elements that readily form brittle intermetallic compounds with copper.

[0015] Furthermore, it includes an annealing step with the following parameters: 150-300℃, 0.5-12h. The annealing step can eliminate stress generated during casting and rolling, and promote interfacial atomic diffusion and metallurgical bonding.

[0016] A second aspect of the present invention provides a three-layer composite material prepared according to the above process, wherein the peel strength of the three-layer composite material is 170-300 N / mm.

[0017] The above three-layer composite material has high interfacial bonding strength.

[0018] The third aspect of the present invention provides an application of the above-mentioned three-layer composite material, which is applied to the fields of new energy, electronic information, intelligent equipment, aerospace, medical and health care, or military industry.

[0019] Specifically, the new energy sector includes new energy vehicles, batteries, electrochemical energy storage systems, photovoltaic power generation equipment, and wind power equipment, more specifically such as battery terminals, battery casings, battery covers, heat sinks, copper and aluminum busbars, and power pipes; the electronics and information sector includes 3C electronics, semiconductor components and production equipment, and communication systems; the smart device sector includes robots, intelligent transportation vehicles, and computer systems; the aerospace sector includes drones, helicopters, and satellite systems; and the healthcare sector includes medical equipment and instruments.

[0020] It is understandable that the above-mentioned composite materials, when applied to the above-mentioned fields, can meet the requirements of these fields for high strength, corrosion resistance, or high thermal conductivity. Attached Figure Description

[0021] Figure 1 The image shows the metallographic diagram of the composite material from Example 1.

[0022] Figure 2 The image shows the metallographic diagram of the composite material in Comparative Example 1. Detailed Implementation

[0023] To facilitate understanding of this application, a more complete description will be provided below. This application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0024] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of the application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. In the description of this application, "several" means at least one, such as one, two, etc., unless otherwise explicitly specified.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0026] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0027] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0028] Unless otherwise specified, the percentage content mentioned in this application refers to mass percentage for solid-liquid mixtures and solid-phase-solid mixtures, and volume percentage for liquid-phase-liquid mixtures.

[0029] Unless otherwise specified, all percentage concentrations mentioned in this application refer to the final concentration. The final concentration refers to the proportion of the added component in the system after the addition of that component.

[0030] Unless otherwise specified, the temperature parameters in this application may be either constant temperature processing or processing within a certain temperature range. The constant temperature processing allows temperature fluctuations within the precision range controlled by the instrument.

[0031] The term "particle" as used in this application, or a substance with a defined particle size distribution, is not necessarily spherical in shape; it may be irregular and can be either primary or secondary particles. The particle size of irregular particles is calculated as the average of their maximum and minimum diameters.

[0032] Example 1: This example provides a method for preparing a three-layer composite material based on liquid copper.

[0033] S1: Smelting: Melting copper ingots at 1200℃ to obtain liquid copper.

[0034] S2: Degassing, slag removal, and deoxidation of liquid copper.

[0035] S3: Test the alloy composition of liquid copper to ensure it meets the design values ​​(Cu≥99.9%, total impurities≤0.1%), and transfer the qualified liquid copper to the next process.

[0036] S4: Stand: Keep the liquid copper at 1200℃ for 15 minutes (depending on the composition of copper or copper alloy, they may have different melting points. For example, the liquidus of pure copper is 1083℃. Liquid copper can be heated to 50-120℃ above its liquidus line according to the liquidus line of different metals).

[0037] S5: Titanium Strip Pretreatment: The inner walls (i.e., the surface of the titanium strip facing away from the rolling process, or the interface between the titanium strip and the liquid copper) of two titanium strips (1.5 mm thick, 100 mm wide) are roughened to a roughness of 3 μm. The roughening process is mechanical texturing; in other embodiments, chemical texturing or laser texturing may also be used. Then, air cutting is performed to remove metal dust adhering to the material surface. A semi-solid slurry (3 kg by mass, 60% solid fraction) is divided into two equal parts and uniformly poured onto the inner walls of the two titanium strips. Cooling is then performed to form a copper layer with a thickness of 0.8 mm. The titanium strips are preheated to 200°C.

[0038] S6: Casting and Rolling Composite: One end of each of the two titanium strips is wound onto two unwinding machines, and the other end of each titanium strip contacts the surface of two rolls. The mill is started so that the two strips pass through the roll gap. Liquid copper is poured into the inner wall of the two strips through the casting nozzle. The liquid copper (total pouring amount 30kg) is cast and rolled together with the strips to form a three-layer composite material. The continuous casting speed is 1m / min, the composite width is 100mm, the composite thickness is 10mm, the rolling pressure is 600000N, the roll temperature is 100℃, the rolling tension is 15000N, and the rolls are cooled by water.

[0039] S7: Initial cutting: Cut off the excess copper on both sides (it can be remelted after cleaning and drying).

[0040] S8: Finish rolling: Finish rolling to obtain a composite material with a thickness of 5 mm, at a temperature of 200℃;

[0041] S9: Precision cutting: Cut off the overflow material on both sides of the precision rolling and recycle it;

[0042] S10: Annealing: Annealing temperature 150℃, holding time 12 hours;

[0043] S11: Grinding: Grinding is used to remove the oxide scale from the upper and lower surfaces of the composite material, resulting in a three-layer composite material.

[0044] Example 2: This example provides a method for preparing a three-layer composite material based on liquid copper. The difference between this example and Example 1 is that the total mass of the copper layer is 6 kg, that is, the ratio of the total mass of the copper layer of the two strips to the mass of the liquid copper casting is adjusted to 1:5, the thickness of the corresponding copper layer is adjusted to 0.4 mm, and the temperature of the liquid copper is adjusted to 1140℃.

[0045] Example 3: This example provides a method for preparing a three-layer composite material based on liquid copper. The difference between this example and Example 1 is that the solid fraction of the semi-solid copper paste is 40%.

[0046] Example 4: This example provides a method for preparing a three-layer composite material based on liquid copper. The difference between this example and Example 1 is that the roughness of the inner wall of the strip is adjusted to 0.1 μm.

[0047] Example 5: This example provides a method for preparing a three-layer composite material based on liquid copper. The difference between this example and Example 1 is that the continuous casting speed is 2m / min and the rolling pressure is 800000N.

[0048] Example 6: This example provides a method for preparing a three-layer composite material based on liquid copper. The difference between this example and Example 1 is that the strip is replaced with a steel strip, which is 304 stainless steel, and the rolling pressure is 500,000 N and the rolling tension is 7,000 N.

[0049] Example 7: This example provides a method for preparing a three-layer composite material based on liquid copper. The difference between this example and Example 1 is that the strip is replaced with nickel strip, the rolling pressure is 600,000 N, and the rolling tension is 10,000 N.

[0050] Example 8: This example provides a method for preparing a three-layer composite material based on liquid copper. The difference between this example and Example 1 is that the strip is replaced with a titanium alloy strip. The titanium alloy grade is TC4 and the rolling pressure is 800000N.

[0051] Comparative Example 1: This comparative example provides a method for preparing a three-layer composite material based on liquid copper. The difference between this comparative example and Example 1 is that the inner wall of the strip is not covered with a copper layer.

[0052] Comparative Example 2: This comparative example provides a method for preparing a three-layer composite material based on liquid copper. The difference between this comparative example and Example 1 is that the ratio of the total mass of the copper layer to the mass of the liquid copper casting is adjusted to 1:20.

[0053] Tensile and peel specimens for metals were cut from the three-layer composite materials in the above examples and comparative examples according to the requirements of GB / T228-2002. Peel specimens were prepared by wire cutting according to GB / T 2791-1995. Tensile and peel tests were performed on a universal testing machine (model CMT5105). The test results are shown in Table 1.

[0054] Table 1: Test results of interfacial bonding strength and elongation in the examples and comparative examples

[0055] project Peel strength (N / mm) Elongation (%) Example 1 297 29.3 Example 2 253 27.1 Example 3 231 23.6 Example 4 207 21.8 Example 5 286 25.4 Example 6 195 18.9 Example 7 277 26.5 Example 8 245 22.1 Comparative Example 1 152 15.7 Comparative Example 2 161 16.3

[0056] Based on the data in Table 1 and Figures 1-2The results show that the peel strength and elongation of Examples 1-5 are better than those of Comparative Example 1. This is because the copper layer is pre-set on the inner wall of the strip, which acts as a buffer layer to prevent the liquid copper from directly forming a continuous brittle intermetallic compound (such as CuTi) when it comes into contact with the strip in the casting zone. After the copper layer and liquid copper come into contact, rapid heat conduction occurs, and the temperature rises to the semi-solid temperature to form semi-solid copper. Under rolling pressure, the semi-solid copper can uniformly fill the micro gaps on the surface of the strip to form a continuous contact interface. The small volume shrinkage of the semi-solid copper after cooling can avoid defects such as shrinkage cavities and porosity at the bonding surface. Therefore, it has better interfacial bonding strength and thermal conductivity. In the rolling zone, the solid phase of the semi-solid copper restricts the continuous contact between the liquid phase and the strip surface, so that the brittle intermetallic compound generated at the interface is discretely distributed. Under the action of subsequent rolling pressure, the discretely distributed brittle intermetallic compound is further reduced and dispersed at the bonding surface. The bonding strength and toughness of the composite material are improved through crack deflection and bridging mechanisms. Example 1 ( Figure 1 The bonding surface of the first example is tight, with less shrinkage cavities and porosity, and the thickness of the bonding layer is increased compared to Comparative Example 1; Comparative Example 1 ( Figure 2 The bonding surfaces of the two materials exhibit numerous shrinkage cavities and porosity. These differences result in the mechanical properties of Example 1 being significantly better than those of Comparative Example 1. In Comparative Example 2, the ratio of the total mass of the copper layer to the mass of the liquid copper casting was too low, causing the copper layer to completely melt into a liquid state, thus failing to produce the aforementioned effect. Examples 6-8 also achieved better results by replacing the strip with other materials, indicating that this solution is applicable to various strip materials.

[0057] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0058] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A production process for a three-layer composite material using liquid copper as the core material, characterized in that, The process includes the following steps: starting a rolling mill to allow two strips to pass through a roll gap, the strips comprising an outer wall facing the rolling mill and an inner wall facing away from the rolling mill, both inner walls of the strips being covered with a copper layer; heating copper ingots or copper alloy ingots to 50-120°C above the liquidus line to obtain liquid copper; pouring the liquid copper into the space between the inner walls of the two strips through a casting nozzle; the liquid copper being cast and rolled along with the strips through the rolling mill to form the three-layer composite material; the liquid copper being pure copper or a copper alloy; the sum of the masses of the copper layers of the two strips being 'a'; the mass of the poured liquid copper being 'b'; the ratio of 'a' to 'b' being 1:(5-10); the copper layer being prepared by pouring semi-solid copper slurry into the inner wall of the strips to solidify and form the copper layer; the average thickness of the copper layer being 0.1-0.8 mm.

2. The production process according to claim 1, characterized in that, The solid fraction of the semi-solid copper paste is 40-60%.

3. The production process according to claim 1, characterized in that, The inner wall of the strip is roughened to a roughness of 0.1-3 μm.

4. The production process according to claim 1, characterized in that, Copper ingots or copper alloy ingots are heated to 50-120°C above the liquidus line to obtain liquid copper. The liquid copper is then degassed, slag removed, and deoxidized. The composition of the liquid copper is tested, and the qualified liquid copper is kept at a constant temperature and allowed to stand.

5. The production process according to claim 1, characterized in that, The parameters for the casting-rolling composite are: continuous casting speed of 1-2 m / min and rolling pressure of 400000N-800000N.

6. The production process according to claim 1, characterized in that, The two strips are independently selected from any one of titanium strip, nickel strip, aluminum strip, titanium alloy strip, steel strip, nickel alloy strip and aluminum alloy strip.

7. The three-layer composite material prepared by the production process according to any one of claims 1-6, characterized in that, The peel strength of the three-layer composite material is 170-300 N / mm.

8. An application of the three-layer composite material as described in claim 7, characterized in that, The three-layer composite material can be applied to the fields of new energy, electronic information, intelligent equipment, aerospace, medical and health, or military industry.

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