Copper-aluminum bimetallic composite material and preparation method thereof

Abstract

The invention belongs to the technical field of bimetallic composite materials, and provides a copper-aluminum bimetallic composite material and a preparation method thereof. The method comprises the following steps: coating an aluminum material with a copper strip, sealing through continuous electron beam welding, carrying out continuous equal channel angular extrusion on the copper-aluminum bimetallic material, carrying out heat treatment on the deformed copper-aluminum bimetallic material, and then carrying out extended extrusion or drawing to obtain the copper-aluminum bimetallic composite material. Aluminum is used for replacing part of copper, the overall weight of the material is reduced on the premise that the high conductivity of pure copper is kept, copper resources are saved, and the production cost is reduced. After ECAP extrusion, the strength performance of the material is improved by 3-5 times; after heat treatment, work hardening disappears, and subsequent machining treatment is facilitated; after expansion extrusion, the copper-aluminum bimetallic material is processed into a copper-aluminum bimetallic bar; and after further rolling and drawing, a bimetal plate or an ultra-fine grain wire is formed, and the material is restrained by a roller and a die hole to form an accurate size and a smooth surface.

Description

Technical Field

[0001] The present invention relates to the technical field of bimetallic composite materials, and in particular to a copper-aluminum bimetallic composite material and a preparation method thereof. Background Art

[0002] Aluminum is the most abundant metal element in the earth's crust. In contrast, copper resources are relatively rare in the earth's crust and are more expensive. With the rapid development of industry, the requirements for comprehensive resource utilization are getting higher and higher. Since the price and density of aluminum are about one-third of copper, using aluminum to replace part of copper can not only maintain the high conductivity of copper, but also significantly reduce the cost of products, achieve lightweight products, and reduce the consumption of copper resources. Therefore, replacing copper with aluminum has significant economic and social benefits.

[0003] Copper-aluminum bimetallic composite materials are made by combining copper and aluminum under high pressure through a specific process to form a composite structural material that combines the advantages of both metals. This material combines the excellent thermal and electrical conductivity and easy processing of copper with the light weight, easy welding and cost-effectiveness of aluminum. Due to the "skin effect", the electrical conductivity of copper-aluminum bimetallic is almost equivalent to that of pure copper. These characteristics make copper-aluminum bimetallic show great application potential in industries such as power transmission, electronic packaging and transportation, especially in situations where lightweight and efficient conductive materials are required.

[0004] Patent 201020140078.0 discloses a copper-aluminum bimetallic composite plate, which is formed by connecting a copper panel, a resin layer and an aluminum substrate. This method has low cost, good texture and high economic benefits. However, the method uses a resin layer to connect the copper plate and the aluminum plate, which greatly reduces its conductivity, limiting its application in power transmission and other aspects. Patent 201010300694.2 discloses a production process for a copper-aluminum bimetallic composite plate strip, which uses aluminum liquid to directly pour on the copper plate to achieve metallurgical bonding of copper and aluminum. However, the excessively high aluminum liquid temperature not only causes corrosion of the copper plate and destroys the organization and mechanical properties of the copper plate, but also due to the surface tension of the aluminum liquid, it is difficult to form an aluminum layer of uniform thickness on the copper plate, and its practical application is very limited.

[0005] Therefore, it is of great significance to study a method for preparing a copper-aluminum bimetallic composite material with excellent mechanical properties and electrical conductivity. Summary of the invention

[0006] The purpose of the present invention is to provide a copper-aluminum bimetallic composite material and a preparation method thereof in order to overcome the deficiencies of the prior art.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] The present invention provides a method for preparing a copper-aluminum bimetallic composite material, comprising the following steps:

[0009] 1) Wrapping the copper strip on the aluminum material along the length direction and sealing it by continuous electron beam welding to obtain the copper-aluminum bimetallic initial material;

[0010] 2) the copper-aluminum bimetallic initial material is subjected to continuous equal channel angular extrusion to obtain a deformed copper-aluminum bimetallic material;

[0011] 3) annealing the deformed copper-aluminum bimetallic material to obtain a heat-treated copper-aluminum bimetallic material;

[0012] 4) The copper-aluminum bimetallic material after heat treatment is expanded, extruded or drawn to obtain a copper-aluminum bimetallic bar or a copper-aluminum bimetallic rod.

[0013] Preferably, in step 1), the diameter of the copper-aluminum bimetallic material is 10 to 50 mm, the outer layer of the copper-aluminum bimetallic material is a copper strip, the core is an aluminum material, and the aluminum material is pure aluminum or an aluminum alloy.

[0014] Preferably, the thickness of the outer copper strip is 0.8 to 3 mm.

[0015] Preferably, the path of the continuous equal channel angular extrusion in step 2) is path A, path Ba, path Bc or path C, the number of continuous equal channel angular extrusion passes is ≥2, the deformed copper-aluminum bimetallic material is an ultrafine crystal rod or ultrafine crystal rod, and nanocrystalline rods or nanocrystalline rods are obtained after high-pass deformation.

[0016] Preferably, in the continuous equal channel angular extrusion in step 2), the radius of the extrusion wheel is 180-220 mm, the speed of the extrusion wheel is 0.5-1.0 rad / s, the inner angle of the die is 90-135°, and the outer angle of the die is 30-60°.

[0017] Preferably, the annealing temperature in step 3) is 350-420° C., and the annealing time is 1.5-2.5 h.

[0018] Preferably, in step 4), the expanded extrusion obtains a copper-aluminum bimetallic bar, which is then rolled to obtain a copper-aluminum bimetallic composite plate, with a rolling deformation of 25 to 75%.

[0019] Preferably, the drawing die in step 4) is a conical die, the die angle of the conical die is 12-15°, the deformation amount of drawing is 20-35%, and the lubricant used for drawing is a mixture of graphite and engine oil.

[0020] The present invention also provides a copper-aluminum bimetallic composite material prepared by the preparation method of the copper-aluminum bimetallic composite material.

[0021] The beneficial effects of the present invention include:

[0022] The present invention uses aluminum to replace part of copper, which reduces the overall weight of the material while maintaining the high conductivity of pure copper, saves copper resources, and reduces production costs. After ECAP extrusion, the grains of the rod material are refined to a structure of tens of microns to hundreds of nanometers, and the material strength is increased by 3 to 5 times; after heat treatment, the work hardening disappears, which is convenient for subsequent processing and treatment, and it is further drawn into a high-strength rod material; after extended extrusion, the copper-aluminum bimetallic material is processed into a copper-aluminum bimetallic bar; or the ultrafine-grained rod material is rolled to obtain a micro-nanocrystalline high-strength plate. During the drawing process, the material is constrained by the roller and the die hole to form a precise size and a smooth surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the copper-aluminum bimetallic rod / bar of the present invention;

[0024] Figure 2 It is a schematic diagram of ECAP extrusion of the present invention;

[0025] Figure 3 Schematic diagram of each path of ECAP extrusion of the present invention;

[0026] Figure 4 It is a drawing schematic diagram of the present invention;

[0027] Figure 5 Schematic diagram of extended extrusion of the present invention, wherein a is the temperature field, b is the characteristic point temperature, c is the flow velocity field in the longitudinal cross section, d is the distribution of the flow velocity field and the flow velocity extrusion zone, e is the stress field, and f is the strain field;

[0028] Figure 6 It is a rolling schematic diagram of the present invention;

[0029] Figure 7 This is the EBSD tissue distribution diagram of the copper-aluminum bimetallic after ECAP of the present invention. DETAILED DESCRIPTION

[0030] The present invention provides a method for preparing a copper-aluminum bimetallic composite material, comprising the following steps:

[0031] 1) Wrapping the copper strip on the aluminum material along the length direction and sealing it by continuous electron beam welding to obtain the copper-aluminum bimetallic initial material;

[0032] 2) the copper-aluminum bimetallic initial material is subjected to continuous equal channel angular extrusion to obtain a deformed copper-aluminum bimetallic material;

[0033] 3) annealing the deformed copper-aluminum bimetallic material to obtain a heat-treated copper-aluminum bimetallic material;

[0034] 4) The copper-aluminum bimetallic material after heat treatment is expanded, extruded or drawn to obtain a copper-aluminum bimetallic bar or a copper-aluminum bimetallic rod.

[0035] In the present invention, the diameter of the copper-aluminum bimetallic material in step 1) is preferably 10 to 50 mm, more preferably 15 to 40 mm, and more preferably 20 to 30 mm; the outer layer of the copper-aluminum bimetallic material is a copper strip, and the core is an aluminum material, the aluminum material is preferably pure aluminum or an aluminum alloy, and the aluminum material is preferably an aluminum rod or an aluminum rod.

[0036] In the present invention, according to production cost control or conductivity requirements, the thickness of the outer copper strip is preferably 0.8 to 3 mm, more preferably 1 to 2.5 mm, and even more preferably 1.5 to 2 mm.

[0037] In the present invention, the coating in step 1) is preferably a continuous coating process.

[0038] In the present invention, the path of the continuous equal channel angular extrusion in step 2) is preferably path A, path Ba, path Bc or path C, and the number of continuous equal channel angular extrusion passes is preferably ≥2, further preferably 3 to 5 times, and more preferably 4 times; the deformed copper-aluminum bimetallic material is preferably an ultrafine crystal rod or an ultrafine crystal rod, and nanocrystalline rods or nanocrystalline rods are obtained after high-pass deformation.

[0039] The copper-aluminum bimetallic initial material is subjected to continuous equal channel angular extrusion to precisely combine the outer copper layer and the inner aluminum layer.

[0040] In the present invention, the deformation path of continuous equal channel angular pressing (C-ECAP) is selected according to the initial structure and grain size of the material, as well as the target grain size or orientation. The deformation path is preferably path A, path Ba, path Bc or path C. After continuous equal channel angular pressing, ultrafine crystal rods and ultrafine crystal rods with highly bonded interfaces are formed, and nanocrystalline rods or nanocrystalline rods are obtained after high-pass deformation.

[0041] In the present invention, in the continuous equal channel angular extrusion of step 2), the radius of the extrusion wheel is preferably 180-220 mm, more preferably 190-210 mm, and more preferably 200 mm; the speed of the extrusion wheel is preferably 0.5-1.0 rad / s, more preferably 0.6-0.9 rad / s, and more preferably 0.7-0.8 rad / s, the inner angle of the die is preferably 90-135°, more preferably 100-120°, and more preferably 105-115°, and the outer angle of the die is preferably 30-60°, more preferably 35-55°, and more preferably 45-50°.

[0042] In the present invention, the temperature of the annealing treatment in step 3) is preferably 350-420°C, more preferably 370-400°C, more preferably 380-390°C, and the annealing treatment time is preferably 1.5-2.5h, more preferably 2h.

[0043] In the present invention, the low-stress copper-aluminum bimetallic material is obtained by annealing.

[0044] In the present invention, the copper-aluminum bimetallic bar is obtained by the extended extrusion in step 4, and the copper-aluminum bimetallic bar is rolled to obtain a copper-aluminum bimetallic composite plate, and the rolling deformation is preferably 25-75%, more preferably 35-70%, and more preferably 45-65%.

[0045] In the present invention, the drawing die in step 4) is preferably a conical die, the die angle of the conical die is preferably 12-15°, more preferably 13-14°, the deformation amount of drawing is preferably 20-35%, more preferably 25-30%, and more preferably 30-32%; the lubricant used for drawing is preferably a mixture of graphite and engine oil; the engine oil can be conventional mechanical lubricating oil in the field.

[0046] In the present invention, the copper-aluminum bimetallic rod material is obtained by drawing.

[0047] In the present invention, a layer of lubricant mixed with graphite and engine oil is preferably applied to the die before drawing.

[0048] The present invention also provides a copper-aluminum bimetallic composite material prepared by the preparation method of the copper-aluminum bimetallic composite material.

[0049] The copper-aluminum bimetallic composite material of the present invention is a copper-aluminum bimetallic composite rod, wire, bar, strip or plate.

[0050] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0051] Example 1

[0052] The thickness of the copper strip is 2 mm, and the diameter of the aluminum rod is 6 mm. The copper strip is coated with the aluminum rod by a continuous coating process, and then sealed by continuous electron beam welding to form a copper-aluminum bimetallic initial rod with a diameter of 10 mm. The copper-aluminum bimetallic initial rod is subjected to 4 passes of continuous equal channel angular extrusion (C-ECAP) according to deformation path A. The radius of the extrusion wheel of the press is 200 mm, the speed of the extrusion wheel is 0.5 rad / s, the inner angle of the die is 120°, and the outer angle is 60°, so as to obtain an ultrafine grained rod with a highly bonded interface. Then, the ultrafine grained rod is heat treated at a temperature of 370°C and a heat treatment time of 2 hours. Subsequently, the heat-treated copper-aluminum bimetallic rod is expanded and extruded to obtain a copper-aluminum bimetallic bar, and finally the copper-aluminum bimetallic bar is rolled at room temperature with a rolling deformation of 75% to obtain a copper-aluminum bimetallic sheet.

[0053] Example 2

[0054] The thickness of the copper strip is 2 mm, and the diameter of the aluminum rod is 6 mm. The copper strip is coated with the aluminum rod by a continuous coating process, and then sealed by continuous electron beam welding to form a copper-aluminum bimetallic initial rod with a diameter of 10 mm. The copper-aluminum bimetallic initial rod is subjected to 4 passes of continuous equal channel angular extrusion (C-ECAP) according to deformation path A. The radius of the extrusion wheel of the press is 200 mm, the speed of the extrusion wheel is 0.5 rad / s, the inner angle of the die is 120°, and the outer angle is 60°, to obtain an ultrafine-grained rod with a highly bonded interface. The ultrafine-grained rod is then heat treated at a temperature of 400°C and a heat treatment time of 1.5 h. Finally, the copper-aluminum bimetallic rod after heat treatment is drawn. Before drawing, a layer of lubricant with a thickness of 0.1 mm, which is a mixture of graphite and engine oil, is applied on the die (the graphite mass content in the lubricant is 1.5%). The deformation of each drawing pass is 20%, and the drawing die is a conical die with a die angle of 15° to obtain the copper-aluminum bimetallic rod.

[0055] Example 3

[0056] The thickness of the copper strip is 2.5 mm, and the diameter of the aluminum rod is 10 mm. The copper strip is coated with the aluminum rod by a continuous coating process, and then sealed by continuous electron beam welding to form a copper-aluminum bimetallic initial rod with a diameter of 15 mm. The copper-aluminum bimetallic initial rod is subjected to three passes of continuous equal channel angular extrusion (C-ECAP) according to the deformation path C. The radius of the extrusion wheel of the press is 210 mm, the speed of the extrusion wheel is 0.7 rad / s, the inner angle of the die is 105°, and the outer angle is 50°, so as to obtain a nanocrystalline rod with a highly bonded interface. Then, the nanocrystalline rod is heat treated at a temperature of 350°C and a heat treatment time of 2.5 h. Subsequently, the heat-treated copper-aluminum bimetallic rod is expanded and extruded to obtain a copper-aluminum bimetallic bar, and finally the copper-aluminum bimetallic bar is rolled at room temperature with a rolling deformation of 65% to obtain a copper-aluminum bimetallic sheet.

[0057] Example 4

[0058] The thickness of the copper strip is 2 mm, and the diameter of the aluminum rod is 16 mm. The copper strip is coated with the aluminum rod by a continuous coating process, and then sealed by continuous electron beam welding to form a copper-aluminum bimetallic initial rod with a diameter of 20 mm. The copper-aluminum bimetallic initial rod is subjected to 5 passes of continuous equal channel angular extrusion (C-ECAP) according to deformation path A. The radius of the extrusion wheel of the press is 190 mm, the speed of the extrusion wheel is 0.8 rad / s, the inner angle of the die is 115°, and the outer angle is 45°, so as to obtain an ultrafine grained rod with a highly bonded interface. Then the ultrafine grained rod is heat treated at a temperature of 360°C and a heat treatment time of 2 h. Finally, the heat-treated copper-aluminum bimetallic rod is drawn. Before drawing, a layer of lubricant mixed with graphite and engine oil is applied to the die. The deformation of the drawing is 30%, and the drawing die is a conical die with a die angle of 13° to obtain a copper-aluminum bimetallic rod.

[0059] The present invention uses aluminum to replace part of copper, which reduces the overall weight of the material while maintaining the high conductivity of pure copper, saves copper resources, and reduces production costs. After ECAP extrusion, the material grains are refined to a structure of tens of microns to hundreds of nanometers, and the material strength is increased by 3 to 5 times; after heat treatment, the work hardening disappears, which is convenient for subsequent processing; after extended extrusion, the copper-aluminum bimetallic material is processed into a copper-aluminum bimetallic bar; after further rolling and drawing, a bimetallic sheet or ultrafine grain wire is formed, and the material is constrained by the roller and the die hole to form a precise size and a smooth surface.

[0060] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a copper-aluminum bimetallic composite material, characterized in that: The following steps are included: 1) Wrapping the copper strip on the aluminum material along the length direction and sealing it by continuous electron beam welding to obtain the copper-aluminum bimetallic initial material; 2) the copper-aluminum bimetallic initial material is subjected to continuous equal channel angular extrusion to obtain a deformed copper-aluminum bimetallic material; 3) annealing the deformed copper-aluminum bimetallic material to obtain a heat-treated copper-aluminum bimetallic material; 4) The copper-aluminum bimetallic material after heat treatment is expanded, extruded or drawn to obtain a copper-aluminum bimetallic bar or a copper-aluminum bimetallic rod.

2. The preparation method according to claim 1, characterized in that: Step 1) The diameter of the copper-aluminum bimetallic material is 10 to 50 mm, the outer layer of the copper-aluminum bimetallic material is a copper strip, the core is an aluminum material, and the aluminum material is pure aluminum or an aluminum alloy.

3. The preparation method according to claim 1 or 2, characterized in that: The thickness of the outer copper strip is 0.8 to 3 mm.

4. The preparation method according to claim 3, characterized in that: Step 2) The path of the continuous equal channel angular extrusion is path A, path Ba, path Bc or path C, the number of continuous equal channel angular extrusion passes is ≥2, the deformed copper-aluminum bimetallic material is an ultrafine crystal rod or ultrafine crystal rod, and nanocrystalline rods or nanocrystalline rods are obtained after high-pass deformation.

5. The preparation method according to claim 4, characterized in that: In the continuous equal channel angular extrusion of step 2), the radius of the extrusion wheel is 180-220 mm, the speed of the extrusion wheel is 0.5-1.0 rad / s, the inner angle of the die is 90-135°, and the outer angle of the die is 30-60°.

6. The preparation method according to claim 4 or 5, characterized in that: Step 3) The annealing temperature is 350-420° C. and the annealing time is 1.5-2.5 h.

7. The preparation method according to claim 6, characterized in that: Step 4) The expanded extrusion obtains a copper-aluminum bimetallic bar, which is then rolled to obtain a copper-aluminum bimetallic composite plate, with a rolling deformation of 25 to 75%.

8. The preparation method according to claim 6, characterized in that: Step 4) The drawing die is a conical die, the die angle of the conical die is 12-15 degrees, the deformation of the drawing is 20-35%, and the lubricant used for drawing is a mixture of graphite and engine oil.

9. The copper-aluminum bimetallic composite material prepared by the method for preparing the copper-aluminum bimetallic composite material according to any one of claims 1 to 8.

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