Copper-aluminum composite board and preparation method thereof

Abstract

The invention relates to a copper-aluminum composite plate and a preparation method thereof, and belongs to the technical field of metal composite materials. The preparation method comprises the following steps: S1, carrying out microstructuring treatment on the surface of a copper plate to form a rough structure formed by micron-sized pits and bulges on the surface of the copper plate to obtain a microstructured copper plate; s2, depositing a zinc intermediate layer on the surface of the microstructured copper plate through a magnetron sputtering technology to obtain a galvanized copper plate; s3, the zinc middle layer of the galvanized copper plate is attached to the aluminum plate, and the copper-aluminum composite plate is obtained through hot pressing, rolling and heat treatment in sequence; the copper-aluminum composite board has excellent interface bonding strength and toughness.

Description

Technical Field

[0001] This invention belongs to the field of metal composite materials technology, and particularly relates to a copper-aluminum composite plate and its preparation method. Background Technology

[0002] Copper and aluminum are two important metallic materials, each with its own excellent properties. Copper has excellent electrical and thermal conductivity and corrosion resistance, but it has the disadvantages of high density and high cost. Aluminum, on the other hand, has the advantages of low density, low cost and light weight, but its electrical and thermal conductivity and corrosion resistance are slightly inferior to copper. By combining copper and aluminum through composite technology, the advantages of both can be fully utilized to achieve the goals of material lightweighting, copper resource conservation and production cost reduction. At the same time, it endows composite materials with excellent comprehensive performance, making them widely used in many fields such as heat exchangers, battery connecting plates, and building decoration.

[0003] Existing copper-aluminum composite technologies include rolling composite, explosive composite, and brazing. However, these technologies generally have certain limitations: First, the interfacial bonding strength is insufficient. Copper-aluminum composite plates prepared by traditional hot rolling or cold rolling methods have weak interfacial bonding, which easily leads to cracking and peeling during subsequent processing or use. Second, the interfacial brittle compound layer is too thick. Copper and aluminum undergo diffusion reactions under high temperature conditions to generate intermetallic compounds such as CuAl2 and CuAl. These compounds are hard and brittle, and an excessively thick intermetallic compound layer will seriously reduce the interfacial toughness and bonding strength, thus becoming the source of crack initiation. Third, the yield is low and the process is complex. Explosive composite is not only costly and dangerous, but the process is also difficult to control precisely. Some advanced composite processes have the disadvantages of lengthy processes and high energy consumption.

[0004] Therefore, developing a method for preparing copper-aluminum composite plates that can effectively suppress interfacial oxidation, precisely control the growth of brittle compound layers, and thus obtain high and stable interfacial bonding strength remains a key problem that urgently needs to be solved in this field. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a copper-aluminum composite plate and its preparation method, wherein the copper-aluminum composite plate possesses excellent interfacial bonding strength and toughness.

[0006] The first objective of this invention is to provide a method for preparing a copper-aluminum composite plate, comprising the following steps: S1. Microstructure the surface of the copper plate to form a rough structure consisting of micron-level pits and protrusions, thus obtaining a microstructured copper plate. S2. A zinc intermediate layer is deposited on the surface of the microstructured copper plate described in S1 by magnetron sputtering technology to obtain a galvanized copper plate. S3. The zinc interlayer of the galvanized copper plate described in S2 is bonded to the aluminum plate, and then subjected to hot pressing, rolling and heat treatment in sequence to obtain the copper-aluminum composite plate.

[0007] In one embodiment of the present invention, in S1, the microstructuring process is selected from laser texturing and / or electrochemical etching.

[0008] In one embodiment of the present invention, the process parameters of the laser texturing process are as follows: power of 95W-105W, scanning speed of 480mm / s-520mm / s, and line spacing of 48μm-52μm; And / or, the process parameters for electrochemical etching are as follows: the anode is a copper plate, the cathode is a stainless steel plate, the electrolyte is a 9.5wt%-10.5wt% phosphoric acid solution, and the etching is carried out at 0.48A / dm² at 15℃-30℃. 2 -0.52A / dm 2 The DC current density etching process lasts for 110s-130s.

[0009] In one embodiment of the present invention, in S1, the roughness Ra of the microstructured copper plate surface roughening structure is 1.0 μm-5.0 μm; the roughening structure is designed to increase the actual contact area during the composite process and provide mechanical interlocking sites for the interface material.

[0010] In one embodiment of the present invention, in S2, the process parameters of the magnetron sputtering technology are as follows: applying 1.5 W / cm² to the zinc target. 2 -4W / cm 2 The DC power density is controlled by applying a DC bias voltage of -50V to -70V to the copper plate, with a deposition time of 5.5min to 11min. By controlling the DC power density, the deposition rate can be precisely controlled, avoiding excessive internal stress or columnar crystal growth caused by excessively fast deposition rate, thus ensuring the uniformity of the coating. By applying a DC bias voltage to the copper plate, some ions are guided to bombard the growing coating, which can improve the density of the coating and its adhesion to the substrate.

[0011] In one embodiment of the present invention, in S2, the thickness of the zinc interlayer is 50nm-500nm. The zinc interlayer has the dual function of diffusion barrier and activator, which can effectively inhibit the rapid formation of thick and brittle intermetallic compound layer when copper and aluminum are in direct contact.

[0012] In one embodiment of the present invention, in S3, the hot pressing is carried out under a protective atmosphere, and the specific process parameters are as follows: temperature is 400℃-450℃, pressure is 50MPa-150MPa, and time is 30min-90min. This stage promotes the zinc intermediate layer to undergo eutectic reaction and interdiffusion with copper and aluminum respectively, thereby achieving the initial metallurgical bonding between the two. At the same time, hot pressing under a protective atmosphere can fundamentally avoid the oxidation of the interface during the heating process, providing a reliable guarantee for obtaining a pure and strong metallurgical bonding interface.

[0013] In one embodiment of the present invention, in S3, the rolling process parameters are as follows: temperature is 350℃-420℃, and reduction rate is 30%-60%.

[0014] In one embodiment of the present invention, in S3, the heat treatment is divided into two stages: the first stage is to hold at 250℃-300℃ for 1h-3h to promote full diffusion of interface atoms and stabilize the bonding interface; the second stage is to hold at 150℃-200℃ for 2h-5h to release the stress generated during the processing.

[0015] A second objective of this invention is to provide a copper-aluminum composite plate prepared by the method described above.

[0016] The technical solution of the present invention has the following advantages compared with the prior art: (1) The preparation method described in this invention not only increases the effective contact area between copper and aluminum by microstructuring the surface of the copper plate, but also gives them a mechanical interlocking effect, thereby significantly improving the physical bonding force of the interface.

[0017] (2) The preparation method of the present invention introduces a zinc interlayer into the copper plate and the aluminum plate. The zinc interlayer can form a solid solution or a low melting point eutectic with copper and aluminum respectively, thereby reducing the temperature and energy barrier required for bonding. At the same time, it can act as a buffer layer to effectively inhibit the direct diffusion of copper and aluminum to form thick and brittle copper-aluminum intermetallic compounds. Compared with conventional zinc interlayer, nanoscale zinc interlayer has better conductivity, which can improve the overall conductivity of copper-aluminum composite plate. Moreover, the interface continuity and density of the interlayer are better, which is conducive to further improving the physical bonding strength of the interface.

[0018] (3) The preparation method described in this invention optimizes the process parameters of hot pressing and rolling, and combines them with the subsequent two-stage heat treatment process. This ensures sufficient atomic diffusion to achieve high-strength bonding at the interface, and effectively controls the growth of the brittle layer and the retention of residual stress, so that the final product has both high bonding strength and good toughness.

[0019] (4) The preparation method described in this invention has the advantages of simple process, low cost and easy industrial application, and can effectively control the interface oxidation phenomenon and the formation of intermetallic compounds. Attached Figure Description

[0020] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein: Figure 1 SEM image of the interface of the copper-aluminum composite plate prepared in Example 1 of the present invention; Figure 2 This is a SEM image of the interface of the copper-aluminum composite plate prepared in Comparative Example 1 of the present invention. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0022] In this invention, unless otherwise stated, the copper plate used in the embodiments of this invention is a T2 pure copper plate and the aluminum plate is a 1060 pure aluminum plate. Before use, the surfaces of the copper plate and aluminum plate to be laminated are first polished with 400# sandpaper, then placed in acetone for 15 minutes of ultrasonic cleaning, and finally dried with cold air for later use.

[0023] In this invention, unless otherwise stated, the roughness Ra involved in the embodiments of this invention is measured by a surface profilometer.

[0024] In this invention, unless otherwise stated, during the magnetron sputtering process involved in the embodiments of this invention, the sample holder revolves at a rotational speed of 8 rpm. Example 1

[0025] The copper-aluminum composite plate and its preparation method in this embodiment specifically include the following steps: S1. Laser roughening treatment is performed on the surface of the copper plate to be composited. The power is set to 100W, the scanning speed is 500mm / s, and the line spacing is 50μm. This forms a rough structure on the surface of the copper plate consisting of micron-level pits and protrusions, resulting in a microstructured copper plate with a roughness Ra of about 2.5μm. S2. A zinc intermediate layer with a thickness of about 200 nm was deposited on the surface of a microstructured copper plate using magnetron sputtering technology. High-purity argon was used as the sputtering gas, the working pressure was 0.4 Pa, the DC power density of the zinc target was set to 3 W / cm², the copper plate was kept at room temperature during the sputtering process, and a DC bias voltage of -70 V was applied to the copper plate. The deposition time was 9 min to obtain a galvanized copper plate. S3. Adhere the zinc interlayer of the galvanized copper sheet to the corresponding aluminum sheet, place them in a stainless steel vacuum bag, and evacuate to 5×10. -3 After Pa, it is sealed by argon arc welding; then it is placed in a hot press furnace, argon gas is introduced as a protective atmosphere, and the temperature is raised to 420℃ at a rate of 10℃ / min, and held at 100MPa pressure for 60min to obtain the composite billet; S4. The composite billet is rolled in a single pass at 400℃ with a reduction rate of 50%. After rolling, it is first held at 280℃ for 2 hours to complete the first stage of heat treatment, and then held at 180℃ for 4 hours to complete the second stage of heat treatment. It is then cooled in the furnace to obtain the copper-aluminum composite plate. Example 2

[0026] The copper-aluminum composite plate and its preparation method in this embodiment specifically include the following steps: S1, Same as Example 1; S2. A zinc intermediate layer with a thickness of about 80 nm was deposited on the surface of a microstructured copper plate using magnetron sputtering technology. High-purity argon was used as the sputtering gas, the working pressure was 0.4 Pa, and the DC power density of the zinc target was set to 2 W / cm². During the sputtering process, the temperature of the copper plate was controlled to be below 60°C by a circulating water cooling system. At the same time, a DC bias voltage of -50 V was applied to the copper plate. The deposition time was 7 min to obtain a galvanized copper plate. S3. Adhere the zinc interlayer of the galvanized copper sheet to the corresponding aluminum sheet, place them in a stainless steel vacuum bag, and evacuate to 5×10. -3 After Pa, the material is sealed by argon arc welding; then it is placed in a hot press furnace, argon gas is introduced as a protective atmosphere, and the temperature is raised to 400℃ at a rate of 10℃ / min, and held at 120MPa pressure for 60min to obtain the composite billet. S4. The composite billet is rolled in a single pass at 380℃ with a reduction rate of 40%. After rolling, it is first held at 280℃ for 2 hours to complete the first stage of heat treatment, and then held at 180℃ for 4 hours to complete the second stage of heat treatment. It is then cooled in the furnace to obtain the copper-aluminum composite plate. Example 3

[0027] The copper-aluminum composite plate and its preparation method in this embodiment specifically include the following steps: S1. Electrochemical etching treatment is performed on the copper plate surface to be laminated. The anode is a copper plate, the cathode is a stainless steel plate, and the electrolyte is a 10wt% phosphoric acid solution. The etching is carried out at 25℃ with an electrochemical etching rate of 0.5A / dm². 2 The copper plate was etched with DC current density for 120s to form a rough structure consisting of micron-sized pits and protrusions on the surface of the copper plate. After rinsing with deionized water and drying, a microstructured copper plate with a roughness Ra of about 3.2μm was obtained. S2. A zinc intermediate layer with a thickness of about 150 nm was deposited on the surface of a microstructured copper plate using magnetron sputtering technology. First, high-purity argon was used as the sputtering gas, and the copper plate surface was bombarded with argon ions for 5 minutes at a working gas pressure of 0.4 Pa and an RF bias voltage of 80 W. Then, the working gas pressure was adjusted to 0.5 Pa, the argon flow rate was maintained at 30 sccm, the DC power density of the zinc target was set to 2 W / cm², the copper plate was kept at room temperature during sputtering, and a DC bias voltage of -60 V was applied to the copper plate. The deposition time was 10 minutes to obtain a zinc-plated copper plate. S3. Adhere the zinc interlayer of the galvanized copper sheet to the corresponding aluminum sheet, place them in a stainless steel vacuum bag, and evacuate to 5×10. -3 After Pa, it is sealed by argon arc welding; then it is placed in a hot press furnace, argon gas is introduced as a protective atmosphere, and the temperature is raised to 430℃ at a rate of 10℃ / min, and held at 80MPa pressure for 75min to obtain the composite billet; S4. The composite billet is rolled in a single pass at 380℃ with a reduction rate of 55%. After rolling, it is first held at 260℃ for 2.5h to complete the first stage of heat treatment, and then held at 170℃ for 5h to complete the second stage of heat treatment. It is then cooled in the furnace to obtain the copper-aluminum composite plate. Comparative Example 1

[0028] The process is basically the same as in Example 1, except that no zinc intermediate layer is deposited. Comparative Example 2

[0029] It is basically the same as Example 1, except that laser texturing is not performed. Comparative Example 3

[0030] It is basically the same as Example 1, except that it is not hot-pressed under a protective atmosphere. Test Example 1

[0031] The copper-aluminum composite plates prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to the following tests: (1) Interface bonding strength: According to GB / T 6396-2008 "Test methods for mechanical and technological properties of composite steel plates", shear test was adopted; (2) The interface morphology was observed and the thickness of the intermetallic compound layer was measured using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS); Specific test results are as follows: Figures 1-2 As shown in Table 1: Table 1

[0032] from Figures 1-2As shown in Table 1, the interfacial bonding strength of the copper-aluminum composite plates prepared in the examples is not less than 120 MPa, and the thickness of the intermetallic compound (IMC) layer is less than 2.2 μm. The interface is smooth, the bonding is dense, and there are no obvious defects. This is because the examples adopted a synergistic process of "microstructuring treatment of copper plate surface + magnetron sputtering zinc interlayer + protective atmosphere hot pressing + rolling + two-stage heat treatment": microstructuring treatment increases the contact area between copper and aluminum and forms mechanical interlocking sites; the nanoscale zinc interlayer inhibits the direct diffusion of copper and aluminum to form thick and brittle IMC; the protective atmosphere avoids interface oxidation; and the optimized hot pressing, rolling, and heat treatment processes not only ensure sufficient atomic diffusion to achieve metallurgical bonding, but also control the growth of the IMC layer and residual stress, ultimately achieving a unity of high bonding strength and good toughness.

[0033] Comparing Example 1 and Comparative Example 1, it can be seen that the interfacial bonding strength of Comparative Example 1 is only 50 MPa, far lower than the 120 MPa of Example 1, and the thickness of the interfacial IMC layer exceeds 8 μm, with obvious cracks and oxide inclusions. This is because Comparative Example 1 did not deposit a zinc interlayer. Copper and aluminum directly contacted each other during hot pressing and rolling, and a rapid diffusion reaction occurred, generating a large amount of thick and brittle intermetallic compounds such as CuAl2 and CuAl. These compounds easily become the source of crack initiation and propagation. At the same time, the lack of buffering and activation effect of the zinc interlayer led to a significant decrease in interfacial bonding strength, and the direct contact caused accelerated interfacial oxidation, further deteriorating the bonding quality.

[0034] Comparing Example 1 and Comparative Example 2, it can be seen that the interfacial bonding strength of Comparative Example 2 is significantly lower than that of Example 1, the thickness of the interfacial IMC layer is significantly higher than that of Example 1, and the bonding tightness is insufficient. This is because Comparative Example 2 did not undergo laser roughening treatment on the copper plate, and the surface of the copper plate lacks the rough structure composed of micron-level pits and protrusions, resulting in a significant reduction in the actual contact area during the copper-aluminum composite process. The lack of mechanical interlocking effect significantly reduces the physical bonding force. Simultaneously, the flat surface is not conducive to the tight adhesion of the zinc interlayer to the copper plate, reducing the interfacial atomic diffusion channels and weakening the metallurgical bonding effect, ultimately leading to a decrease in bonding strength and difficulty in effectively constraining the growth of the IMC layer.

[0035] Comparing Example 1 and Comparative Example 3, it can be seen that the interfacial bonding strength of Comparative Example 3 is significantly lower than that of Example 1. The interface is prone to oxide inclusions and localized peeling, and the IMC layer is thicker. This is because Comparative Example 3 was not hot-pressed under a protective atmosphere. During the heating process, the copper plate, aluminum plate, and zinc interlayer easily react with oxygen in the air to form oxide inclusions at the interface, disrupting the continuity of the metallurgical bond. The presence of the oxide layer hinders the interdiffusion of copper, aluminum, and zinc atoms, resulting in a weak interfacial bond. Furthermore, the oxidation products exacerbate interfacial stress concentration, leading to disordered growth and uneven thickness of the IMC layer, ultimately reducing the interfacial bonding strength and the overall performance of the composite plate.

[0036] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a copper-aluminum composite plate, characterized in that, Includes the following steps: S1. Microstructure the surface of the copper plate to form a rough structure consisting of micron-level pits and protrusions, thus obtaining a microstructured copper plate. S2. A zinc intermediate layer is deposited on the surface of the microstructured copper plate described in S1 by magnetron sputtering technology to obtain a galvanized copper plate. S3. The zinc interlayer of the galvanized copper plate described in S2 is bonded to the aluminum plate, and then subjected to hot pressing, rolling and heat treatment in sequence to obtain the copper-aluminum composite plate.

2. The method for preparing the copper-aluminum composite plate according to claim 1, characterized in that, In S1, the microstructuring process is selected from laser texturing and / or electrochemical etching.

3. The method for preparing the copper-aluminum composite plate according to claim 2, characterized in that, The process parameters for the laser texturing process are as follows: power of 95W-105W, scanning speed of 480mm / s-520mm / s, and line spacing of 48μm-52μm; And / or, the process parameters for electrochemical etching are as follows: the anode is a copper plate, the cathode is a stainless steel plate, the electrolyte is a 9.5wt%-10.5wt% phosphoric acid solution, and the etching is carried out at 0.48A / dm² at 15℃-30℃. 2 -0.52A / dm 2 The DC current density etching process lasts for 110s-130s.

4. The method for preparing the copper-aluminum composite plate according to claim 1, characterized in that, In S1, the surface roughness Ra of the microstructured copper plate is 1.0 μm-5.0 μm.

5. The method for preparing the copper-aluminum composite plate according to claim 1, characterized in that, In S2, the process parameters of the magnetron sputtering technology are as follows: 1.5 W / cm² is applied to the zinc target. 2 -4W / cm 2 The DC power density is such that a DC bias voltage of -50V to -70V is applied to the copper plate, and the deposition time is 5.5min-11min.

6. The method for preparing the copper-aluminum composite plate according to claim 1, characterized in that, In S2, the thickness of the zinc interlayer is 50nm-500nm.

7. The method for preparing the copper-aluminum composite plate according to claim 1, characterized in that, In S3, the hot pressing is carried out under a protective atmosphere, and the specific process parameters are as follows: temperature is 400℃-450℃, pressure is 50MPa-150MPa, and time is 30min-90min.

8. The method for preparing the copper-aluminum composite plate according to claim 1, characterized in that, In S3, the rolling process parameters are as follows: temperature is 350℃-420℃, and reduction rate is 30%-60%.

9. The method for preparing the copper-aluminum composite plate according to claim 1, characterized in that, In S3, the heat treatment is divided into two stages: the first stage is to keep the temperature at 250℃-300℃ for 1h-3h, and the second stage is to keep the temperature at 150℃-200℃ for 2h-5h.

10. The copper-aluminum composite plate prepared by the method according to any one of claims 1-9.

Images