A conductive strong-plastic copper-aluminum composite material and its preparation method

Abstract

The present invention discloses a copper-aluminum composite material with strong plasticity for electrical conduction and a preparation method thereof. The material is prepared from pure copper and micro-alloyed aluminum by "casting + multi-pass finishing rolling", and the micro-alloyed aluminum is composed of the following elements in percentage by mass: Mg 0.2-1wt.%, Mn 0.2-1wt.%, Zr 0.2-1wt.%, and the remainder is Al and unavoidable impurity elements. The specific preparation process is as follows: copper plate pretreatment ‑‑preparation of semi-solid aluminum material ‑‑oxygen-free casting and rolling ‑‑multi-pass finishing rolling. The present invention can obtain a copper-aluminum layered composite material with high electrical conductivity and strong plasticity matching on the basis of not increasing the complexity and cost of the preparation process and the material cost, thereby facilitating the wider application of copper-aluminum layered composite materials in the fields of communications, photovoltaic power generation, new energy, etc.

Description

Technical Field

[0001] The invention relates to the technical field of copper-aluminum layered composite materials and preparation processes, in particular to a high-plasticity copper-aluminum composite material for electrical conduction and a preparation method thereof. Background Art

[0002] Copper has excellent electrical and thermal conductivity. However, my country's copper resources are limited, and its dependence on foreign countries is high. Reducing copper consumption is currently a hot topic. Copper-aluminum composite materials combine copper's excellent electrical conductivity and processing properties with aluminum's lightweight and low price. Combining excellent performance with cost-effectiveness, they are widely used in communications, photovoltaic power generation, and new energy fields. They can be used as 5G communication substrates, composite components for power batteries, photovoltaic circuit boards, photovoltaic MWT backplanes, copper-aluminum composite circuit boards for LED lighting, and transition bars for IGBT inverters in new energy power generation. This can effectively alleviate copper resource scarcity by using aluminum to save copper, while also reducing material costs and promoting product development.

[0003] The current preparation processes of copper-aluminum layered composite materials mainly include three categories: solid-solid composite process, solid-liquid composite process and liquid-liquid composite process. In the solid-solid composite process, the copper-aluminum interface is mainly mechanically meshed, and the interface bonding effect is poor. The degree of atomic diffusion at the liquid-liquid composite interface is large, and it is very easy to form a thick, brittle, and highly resistive compound, which damages the conductivity and mechanical properties of the material. The solid-liquid composite of solid copper and semi-solid aluminum can achieve good metallurgical bonding, and the process is simple and efficient. Compared with the solid-solid composite process and the liquid-liquid composite process, it has obvious advantages. The material obtained after solid-liquid composite also has the problem of general mechanical properties, such as the material is prone to delamination and fracture, and the material strength and toughness are not high. The mechanical properties of the material can be improved by adding an intermediate layer (such as Zn or Ni layer) at the copper-aluminum interface, but additional process equipment is required, which makes the process flow complicated and increases the cost.

[0004] Given that copper-aluminum layered composite materials are mainly used in the fields of communications and new energy batteries, there are also high requirements for the conductive properties of the materials. Although there is a "skin effect" when electric current flows in conductors, the conductive effect of the material is affected by the overall conductivity of the material, and the conductivity of the entire material depends on the conductivity of the matrix material itself and the proportion of the matrix material. The Chinese patent with announcement number 200810057668.4 improves the conductivity of the composite material by increasing the area percentage of the copper layer in the copper-aluminum composite material, but it cannot achieve the purpose of "saving copper with aluminum". In addition, the Chinese patent with application number 202211350449.1 improves the conductive properties of the composite material by combining copper and aluminum with silver electroplating on the surface, but the cost of silver material and electroplating process is too high.

[0005] In summary, in order to promote the better application of copper-aluminum layered composite materials in the fields of communications and new energy, it is urgently necessary to improve the conductivity and mechanical properties of copper-aluminum layered composite materials and develop a low-cost conductive strong plastic copper-aluminum layered composite material and preparation method. Summary of the Invention

[0006] The purpose of the present invention is to improve the electrical conductivity and strong plasticity of copper-aluminum layered composite plates without increasing the complexity of the process, equipment cost and raw material cost, and to provide a strong plastic copper-aluminum layered composite material for conductivity and a preparation method thereof.

[0007] The purpose of the present invention is achieved through the following technical solutions:

[0008] The present invention provides a high-plasticity copper-aluminum layered composite material for electrical conduction, which is prepared from pure copper and semi-solid micro-alloyed aluminum through "casting and rolling + multi-pass finishing rolling".

[0009] Preferably, the microalloyed aluminum comprises the following elemental composition by weight: Mg 0.2-1 wt.%, Mn 0.2-1 wt.%, Zr 0.2-1 wt.%, with the balance being Al and unavoidable impurities, with the sum of these components being 100%. Furthermore, the addition of Si to the microalloyed aluminum composition, particularly in amounts exceeding 0.5%, significantly reduces the electrical conductivity of the aluminum alloy.

[0010] The present invention also provides a method for preparing a conductive, highly plastic copper-aluminum layered composite material, which mainly comprises the following steps:

[0011] S1. Copper plate pretreatment

[0012] Alkaline-wash and degrease the (1-2 mm) copper plate to remove the surface oxides of the copper surface to be composited, and then preheat the copper plate to 250-350°C;

[0013] S2. Preparation of semi-solid aluminum material

[0014] High-purity aluminum, pure magnesium, Al-Zr master alloy, and Al-Mn master alloy are weighed according to the mass percentage of each component in the micro-alloyed aluminum. The pure aluminum is first heated to 730-750°C to completely melt, and then argon gas is introduced to refine it. After deslagging, pure magnesium, Al-Zr, and Al-Mn master alloys are added. The mixture is allowed to stand and the melt temperature is adjusted to 670-700°C to obtain semi-solid micro-alloyed aluminum.

[0015] S3, oxygen-free casting and rolling

[0016] Under a protective gas atmosphere, semi-solid micro-alloyed aluminum is uniformly poured on the surface of the copper plate and cast-rolled to obtain a cast-rolled copper-aluminum composite plate;

[0017] S4, multi-pass finishing rolling

[0018] The cast-rolled copper-aluminum composite plate is subjected to multiple passes of finish rolling.

[0019] As an embodiment of the present invention, in step S1, the copper surface to be composited is polished with a steel brush to remove surface oxides, which is conducive to interface metallurgical composite.

[0020] As an embodiment of the present invention, in step S2, the refining time is 0.5-1 h, giving the impurities enough time to react.

[0021] As an embodiment of the present invention, in step S2, the standing time is 0.2-0.4 h to ensure that the impurities are settled as much as possible.

[0022] As an embodiment of the present invention, the protective gas used in the oxygen-free casting in step S3 is argon or nitrogen.

[0023] As an embodiment of the present invention, in step S3, the copper-aluminum composite plate is controlled to be 5-8 mm.

[0024] As an embodiment of the present invention, in step S3, the linear speed of the casting roller is 1-3 m / min, and the rolling pressure is 10*10 6 N-15*10 6 N, can avoid both insufficient rolling force and excessive rolling force that will cause the copper layer to break.

[0025] As an embodiment of the present invention, in step S4, the finishing roller linear speed is 1-3 m / min, the rolling pressure is 5*10 6 N-10*10 6 N, can avoid both insufficient rolling force and excessive rolling force that will cause the copper layer to break.

[0026] As an embodiment of the present invention, in step S4, the thickness of the copper-aluminum composite plate is controlled by multi-pass finishing rolling to be 2-4mm, wherein the thickness of the copper layer is 0.3-0.7mm. The present invention adopts cast rolling and rolling, and the cast rolling process is relatively short, and does not generate too many intermetallic compounds, especially the brittle hard phase AlCu. The rolling force of the rolling process is also limited to the diffusion effect of the interface atoms, and the formation of intermetallic compounds is also limited. And the appropriate thickness intermetallic compound can achieve good interface bonding. Therefore, the copper-aluminum composite plate is controlled to be 5-8mm.

[0027] As one embodiment of the present invention, the multi-pass finishing rolling is performed 3-5 times at room temperature.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1) The copper-aluminum layered composite material described in the present invention improves the electrical conductivity and mechanical properties of the aluminum matrix through microalloying, thereby improving the electrical conductivity and mechanical properties of the composite material as a whole. The presence of 0.2-1wt.% magnesium can significantly improve the strength of the aluminum alloy while preventing excessive decrease in plasticity. Zirconium and aluminum can form ZrAl3 compounds, which can hinder recrystallization, refine grains, stabilize grain boundaries, and increase the strength and plasticity of the alloy. 0.2-1wt.% zirconium and manganese can both form stable solid solutions with aluminum, delaying grain boundary dissolution and solid solution hardening of aluminum alloys, and improving the electrical conductivity of the alloy. If too little magnesium is added, it will not have a strengthening effect; if too little zirconium and manganese are added, they will not have the effect of refining grains and improving electrical conductivity; if too much is added, solute agglomeration will cause the material's plasticity to decrease excessively.

[0030] 2) After casting and rolling, multiple passes of finishing rolling are performed. First, the rolling force further promotes the bonding of the copper-aluminum interface. Second, compared with the copper layer, the thickness of the aluminum layer is reduced at a greater rate, which increases the proportion of the copper layer and improves the electrical conductivity. Third, large plastic deformation increases the dislocation density and dislocation entanglement, thereby improving the strength of the composite material.

[0031] 3) Compared with other methods of enhancing the conductivity and strength of copper-aluminum composite materials, the preparation method adopted in the present invention does not add other complex processes (such as electroplating, hot-dip plating, etc.) and does not add more precious metals (such as Ag, Ti, rare earth metals, etc.), saving material costs and equipment costs, ensuring the simplicity and efficiency of the preparation process, and achieving the effect of improving the conductivity and strong plasticity of the copper-aluminum composite material. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0033] Figure 1 Schematic diagram of the preparation process of the high-strength and plastic copper-aluminum layered composite material for electrical conduction of the present invention. DETAILED DESCRIPTION

[0034] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several variations and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0035] Example 1

[0036] This embodiment relates to a method for preparing a high-strength and plastic copper-aluminum layered composite material for electrical conduction, such as Figure 1 As shown, including:

[0037] S1. Copper plate pretreatment

[0038] Alkaline-wash and degrease the 1mm copper plate, and polish the copper surface to be composited with a steel brush to remove surface oxides, and then preheat the copper plate to 300℃;

[0039] S2. Preparation of semi-solid aluminum material

[0040] High-purity aluminum, pure magnesium, Al-Mn master alloy, and Al-Zr master alloy are weighed according to the specific gravity of 0.4wt.% Mg, 0.4wt.% Mn, 0.2wt.% Zr, and the balance being aluminum. The pure aluminum is first heated to 730°C for complete melting, and then argon is introduced into it for refining for 0.5h. After removing the slag, pure magnesium, Al-Zr, and Al-Mn master alloy are added, and the mixture is allowed to stand for 0.2h. The melt temperature is adjusted to 670°C to obtain semi-solid microalloyed aluminum.

[0041] S3, oxygen-free casting and rolling

[0042] In a protective gas atmosphere (argon or nitrogen, argon is used in this embodiment), the semi-solid aluminum material is evenly poured on the surface of the copper plate and cast and rolled. The roller linear speed is 2m / min and the rolling pressure is 10*10 6 N, to obtain the cast-rolled copper-aluminum composite plate, and control the copper-aluminum composite plate to 7mm;

[0043] S4, multi-pass finishing rolling

[0044] At room temperature, the cast copper-aluminum composite plate was finished rolled three times with a roller speed of 2m / min and a rolling pressure of 5*10 6 N, control the thickness of the copper-aluminum composite plate to 4mm, of which the thickness of the copper layer is 0.7mm.

[0045] Example 2

[0046] This embodiment relates to a method for preparing a high-strength and plastic copper-aluminum layered composite material for electrical conduction, such as Figure 1 As shown, including:

[0047] S1. Copper plate pretreatment

[0048] Alkaline-wash and degrease the 1mm copper plate, and polish the copper surface to be composited with a steel brush to remove surface oxides, and then preheat the copper plate to 300℃;

[0049] S2. Preparation of semi-solid aluminum material

[0050] High-purity aluminum, pure magnesium, Al-Mn master alloy, and Al-Zr master alloy were weighed according to the specific gravity of 0.4wt.% Mg, 0.4wt.% Mn, 0.6wt.% Zr, and the balance being aluminum. The pure aluminum was first heated to 730°C for complete melting, and then argon was introduced for refining for 0.5h. After slag removal, pure magnesium, Al-Zr, and Al-Mn master alloy were added, and the mixture was allowed to stand for 0.2h. The melt temperature was adjusted to 690°C to obtain semi-solid microalloyed aluminum.

[0051] S3, oxygen-free casting and rolling

[0052] In a protective gas atmosphere (argon or nitrogen, nitrogen is used in this embodiment), the semi-solid aluminum material is evenly poured on the surface of the copper plate and cast and rolled. The roller linear speed is 2m / min and the rolling pressure is 10*10 6 N, to obtain the cast-rolled copper-aluminum composite plate, and control the copper-aluminum composite plate to 7mm;

[0053] S4, multi-pass finishing rolling

[0054] At room temperature, the cast copper-aluminum composite plate was finished rolled four times with a roller speed of 2m / min and a rolling pressure of 5*10 6 N, control the thickness of the copper-aluminum composite plate to 3mm, of which the thickness of the copper layer is 0.6mm.

[0055] Example 3

[0056] This embodiment relates to a method for preparing a high-strength and plastic copper-aluminum layered composite material for electrical conduction, such as Figure 1 As shown, including:

[0057] S1. Copper plate pretreatment

[0058] Alkaline-wash and degrease the 1mm copper plate, and polish the copper surface to be composited with a steel brush to remove surface oxides, and then preheat the copper plate to 300℃;

[0059] S2. Preparation of semi-solid aluminum material

[0060] High-purity aluminum, pure magnesium, Al-Mn master alloy, and Al-Zr master alloy are weighed according to the specific gravity of 0.4wt.% Mg, 0.4wt.% Mn, 1wt.% Zr, and the balance being aluminum. The pure aluminum is first heated to 730°C for complete melting, and then argon is introduced into it for refining for 0.5h. After removing the slag, pure magnesium, Al-Zr, and Al-Mn master alloy are added, and the mixture is allowed to stand for 0.2h. The melt temperature is adjusted to 700°C to obtain semi-solid microalloyed aluminum.

[0061] S3, oxygen-free casting and rolling

[0062] In a protective gas atmosphere (argon or nitrogen, argon is used in this embodiment), the semi-solid aluminum material is evenly poured on the surface of the copper plate and cast and rolled. The roller linear speed is 2m / min and the rolling pressure is 10*10 6 N, to obtain the cast-rolled copper-aluminum composite plate, and control the copper-aluminum composite plate to 7mm;

[0063] S4, multi-pass finishing rolling

[0064] At room temperature, the cast copper-aluminum composite plate was finished rolled 5 times, with a roller speed of 2m / min and a rolling pressure of 5*10 6 N, control the thickness of the copper-aluminum composite plate to 2mm, of which the thickness of the copper layer is 0.4mm.

[0065] Comparative Example 1

[0066] The difference between this comparative example and Example 1 is that no Zr is added to the microalloyed aluminum.

[0067] Comparative Example 2

[0068] The difference between this comparative example and Example 1 is that only one finishing rolling was performed. The copper-aluminum layered composite material showed delamination and fracture, indicating that the copper-aluminum interface bonding effect was poor.

[0069] Comparative Example 3

[0070] The only difference between this comparative example and Example 1 is that the aluminum liquid pouring temperature is 710°C.

[0071] Performance Comparison

[0072] Table 1 Comparison of performance of copper-aluminum layered composite materials between examples and comparative examples

[0073]

[0074] As can be seen from Table 1, the layered composite materials prepared in Examples 1-3 have excellent electrical conductivity and strong plasticity matching, which shows that the preparation method provided by the present invention can prepare copper-aluminum layered composite materials with both high electrical conductivity and strong plasticity.

[0075] The above describes specific embodiments of the present invention. The present invention is not limited to the specific embodiments described above. Those skilled in the art may make various changes or modifications within the scope of the claims without affecting the essence of the present invention. The embodiments of this application and the features in the embodiments may be combined with each other in any manner unless there is a conflict.

Claims

1. A conductive, strong-plastic copper-aluminum layered composite material, characterized in that: The composite material is prepared from pure copper and semi-solid microalloyed aluminum through "casting and multi-pass finish rolling". The microalloyed aluminum includes the following elements in percentage by weight: Mg 0.2-1wt.%, Mn 0.2-1wt.%, Zr 0.2-1wt.%, and the balance is Al and unavoidable impurity elements, with the sum of these components being 100%.

2. A method for preparing a conductive, strong-plastic copper-aluminum layered composite material, characterized in that: The main steps are as follows: S1. Copper plate pretreatment Alkaline-wash and degrease the copper plate to remove the surface oxides of the copper surface to be composited, and then preheat to 250-350℃; S2. Preparation of semi-solid aluminum material According to the mass percentage of each component in claim 1, high-purity aluminum, pure magnesium, Al-Zr master alloy, and Al-Mn master alloy are weighed, the pure aluminum is first heated to 730-750° C. to completely melt, and then argon is introduced into it for refining. After deslagging, pure magnesium, Al-Zr and Al-Mn master alloys are added, and the mixture is allowed to stand and the melt temperature is adjusted to 670-700° C. to obtain semi-solid microalloyed aluminum; S3, oxygen-free casting and rolling Under a protective gas atmosphere, semi-solid micro-alloyed aluminum is uniformly poured on the surface of the copper plate and cast-rolled to obtain a cast-rolled copper-aluminum composite plate; S4, multi-pass finishing rolling The cast-rolled copper-aluminum composite plate is subjected to multiple passes of finish rolling.

3. The method for preparing the conductive strong plastic copper-aluminum layered composite material according to claim 2, characterized in that: In step S2, the refining time is 0.5-1 h; and the standing time is 0.2-0.4 h.

4. The method for preparing the conductive strong-plastic copper-aluminum layered composite material according to claim 2, characterized in that: In step S3, the thickness of the copper-aluminum composite plate is controlled to be 5-8 mm.

5. The method for preparing the conductive strong-plastic copper-aluminum layered composite material according to claim 2, characterized in that: The protective gas used in the oxygen-free casting in step S3 is argon or nitrogen.

6. The method for preparing the conductive strong-plastic copper-aluminum layered composite material according to claim 2, characterized in that: In step S3, the linear speed of the casting roller is 1-3 m / min, and the rolling pressure is 10*10 6 N-15*10 6 N.

7. The method for preparing the conductive strong-plastic copper-aluminum layered composite material according to claim 2, characterized in that: In step S4, the finishing roller linear speed is 1-3m / min, and the rolling pressure is 5*10 6 N-10*10 6 N.

8. The method for preparing the conductive strong-plastic copper-aluminum layered composite material according to claim 2, characterized in that: In step S4, the thickness of the copper-aluminum composite plate is controlled to be 2-4 mm by multiple passes of finishing rolling, wherein the thickness of the copper layer is 0.3-0.7 mm.

9. The method for preparing the conductive strong-plastic copper-aluminum layered composite material according to claim 2, characterized in that: In step S4, the multi-pass finishing rolling is performed 3-5 times at room temperature.

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