Surface treatment method of copper-silver alloy wire

Abstract

The present invention discloses a surface treatment method for a copper-silver alloy wire, belonging to the field of alloy processing technology. This method pre-deposits a layer of metallic nickel on the surface of the copper-silver alloy wire as an intermediate bonding layer, then electroplates and composites a layer of graphene oxide to form a sandwich structure, and finally heat-treats the surface graphene oxide to form reduced graphene oxide. This surface treatment method can significantly improve the electrical conductivity of the copper-silver alloy wire. Furthermore, due to the provision of the intermediate bonding layer and the special heat treatment process, the interlayer bonding strength between the surface reduced graphene oxide, the intermediate nickel metal layer, and the copper-silver alloy wire as a whole is high, preventing material peeling or shedding during product transportation or use.

Description

Technical Field

[0001] The present invention relates to the technical field of alloy processing, and in particular to a surface treatment method for a copper-silver alloy wire. Background Art

[0002] Copper-silver alloys have excellent electrical conductivity, softening resistance, and basic mechanical properties, and are widely used in electronics, aviation, transportation, and other fields. However, compared with pure copper alloys, copper-silver alloys have lower electrical conductivity. Therefore, people have tried to modify copper-silver alloys to improve their overall conductivity efficiency.

[0003] Graphene is a non-metallic material with high electrical conductivity. Therefore, researchers have already applied graphene to alloy modification to prepare composite materials, achieving some success in the laboratory. However, these materials cannot be mass-produced in factories. The main reason is that the graphene in these materials can only effectively improve the material's conductivity after forming a complete connection path between the layers. However, since there is no chemical bond and almost no solid solution between graphene and alloy materials, especially copper-based materials, this effect is difficult to achieve under factory production conditions. Furthermore, graphene and alloy materials have no wettability, resulting in a low bond strength between the two, making it easy for them to peel or even fall off during transportation or use. Summary of the Invention

[0004] To address the shortcomings of the prior art, the present invention provides a surface treatment method for copper-silver alloy wire. This method involves pre-depositing a layer of metallic nickel as an intermediate bonding layer on the copper-silver alloy wire surface, then electroplating a composite layer of graphene oxide to form a sandwich structure, and finally heat-treating the surface graphene oxide to form reduced graphene oxide. This surface treatment method significantly improves the electrical conductivity of the copper-silver alloy wire. Furthermore, due to the provision of the intermediate bonding layer and the specialized heat treatment process, the interlayer bonding strength between the surface reduced graphene oxide, the intermediate nickel metal layer, and the copper-silver alloy wire as a whole is high, preventing material peeling or shedding during product transportation or use.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A surface treatment method for a copper-silver alloy wire comprises the following steps:

[0007] (1) After cleaning the copper-silver alloy wire to be treated, a nickel metal layer is deposited on the surface; the current density of the nickel metal layer during electroplating is ≥4 mA / cm 2 ;

[0008] (2) electroplating and depositing a graphene oxide layer on the nickel metal layer;

[0009] (3) The copper-silver alloy wire after the nickel metal layer and the graphene oxide layer are deposited is pre-treated at 350-450°C in a reducing atmosphere, and then subjected to a second-stage heat preservation treatment at 800-950°C in an inert atmosphere, thereby completing the surface treatment.

[0010] In traditional graphene-alloy composite materials, since the graphene component layers are not continuous, a complete pathway cannot be formed, and the conductivity of the material is not greatly improved. Once produced under factory production conditions, the conductivity of the resulting product will further decrease due to the decrease in component uniformity. On the other hand, since carbon-based materials and metal-based materials themselves do not have wettability, even if the two are combined by methods such as electroplating, the bonding strength is not high, and it is extremely easy to peel off or fall off under the action of external forces. In order to solve the above technical problems, the technical solution of the present invention proposes a new method of combining graphene and copper-silver alloy. First, a nickel metal layer is pre-deposited on the surface of the copper-silver alloy wire, and then a graphene oxide layer is deposited on the surface of the nickel metal layer by electroplating. As a derivative of graphene, graphene oxide can be hydrolyzed because it contains oxygen-containing groups and can be deposited by electroplating in an electroplating solution. Since it has high dispersibility in the electroplating solution, the graphene oxide layer after electroplating has a highly continuous layered structure. At the same time, there is no need to consider the ion repulsion and uneven deposition caused by the different ionic electrical properties when graphene oxide is electroplated together with other raw materials. Subsequently, a specific two-stage heat treatment is performed. During this heat treatment, the oxygen-containing functional groups of the graphene oxide are removed and the sp2 hybrid atomic structure identical to pure graphene is formed. The structure of the reduced graphene oxide layer formed is still uniformly distributed and coherent, so free electrons can fully form pathways in the layer structure, effectively improving the conductivity of the copper-silver alloy wire. On the other hand, the nickel metal layer will form a solid solution with the copper-silver alloy wire and couple with the reduced graphene oxide to form chemical bonds, greatly improving the bonding strength and stability between the layers. Without pre-setting the nickel metal layer as an intermediate layer or without performing the specific two-stage heat treatment, the above-mentioned effects cannot be achieved. At the same time, the bonding strength of the graphene layer construction method of the scheme described in the present invention is far superior to existing products that use methods such as deposition and laser induction to directly generate graphene on the nickel metal layer.

[0011] Preferably, the specific steps of cleaning the copper-silver alloy wire in step (1) are as follows:

[0012] The copper-silver alloy was washed with alcohol and hydrochloric acid in sequence, and then ultrasonically treated in alcohol.

[0013] More preferably, the alcohol is ethanol, and the volume concentration of the hydrochloric acid is 25-35%.

[0014] More preferably, the ultrasonic treatment time is 5 to 10 minutes.

[0015] By using alcohol to treat the surface oil of the copper-silver alloy wire, using hydrochloric acid to treat the surface oxide, and finally removing the residue through ultrasonic cleaning, it can be ensured that the subsequent nickel metal layer and graphene oxide layer are evenly and tightly deposited on the surface of the copper-silver alloy wire.

[0016] Preferably, the nickel metal layer is deposited by electroplating.

[0017] More preferably, the nickel metal layer is deposited using an electroplating solution comprising water, a nickel source and a pH adjuster.

[0018] More preferably, the nickel source comprises hydrated nickel sulfate, and the pH adjuster comprises boric acid.

[0019] More preferably, the mass ratio of the water volume to the nickel source and the pH adjuster is 100 mL: (8-20) g: (1-2.5) g.

[0020] More preferably, the current density of the nickel metal layer during electroplating is 4-20 mA / cm 2 , the deposition time is 1~6min.

[0021] Preferably, the concentration of graphene oxide in the electroplating solution used for electroplating and depositing the graphene oxide layer in step (2) is 0.5-2 g / L.

[0022] More preferably, the planar particle size of the graphene oxide is 10-30 μm.

[0023] More preferably, the electroplating solution is prepared by placing graphene oxide powder into water and subjecting it to ultrasonic stirring to obtain the electroplating solution.

[0024] More preferably, the voltage during the electroplating deposition of the graphene oxide layer is 3-10 V, and the time is 10-60 s.

[0025] More preferably, the voltage during the electroplating deposition of the graphene oxide layer is 5-7V.

[0026] During the electroplating deposition process of the graphene oxide layer, the voltage setting has a certain influence on the density, thickness and uniform dispersion of the formed layer. After optimization, the bonding strength and conductivity of the composite layer corresponding to the final reduced graphene oxide layer obtained by electroplating using the above voltage setting can be maintained at a better level.

[0027] Preferably, when the graphene oxide layer is electroplated, the copper-silver alloy wire after the nickel metal layer is deposited is used as the anode, and the annular inert electrode is used as the cathode, and the distance between the two electrodes is 1-3 cm.

[0028] Preferably, in step (3), the time for the first stage heat preservation treatment and / or the second stage heat preservation treatment is 5 to 60 minutes.

[0029] More preferably, the heating rate during the first-stage heat preservation treatment and / or the second-stage heat preservation treatment is 5-10° C. / min.

[0030] Preferably, the mass content of silver in the copper-silver alloy wire is 0.01-20 wt %.

[0031] The present invention provides a surface treatment method for a copper-silver alloy wire. This method involves pre-depositing a layer of metallic nickel as an intermediate bonding layer on the copper-silver alloy wire surface, then electroplating a composite layer of graphene oxide to form a sandwich structure, and finally heat-treating the surface graphene oxide to form reduced graphene oxide. This surface treatment method can significantly improve the electrical conductivity of the copper-silver alloy wire. Furthermore, due to the provision of the intermediate bonding layer and the special heat treatment process, the interlayer bonding strength between the surface reduced graphene oxide, the intermediate nickel metal layer, and the copper-silver alloy wire as a whole is high, preventing material peeling or shedding during product transportation or use. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a scanning electron microscope image of the copper-silver alloy wire described in Example 1 of the present invention after depositing a nickel metal layer.

[0033] Figure 2 This is a scanning electron microscope layer of the copper-silver alloy wire described in Example 1 of the present invention after depositing a nickel metal layer and a graphene oxide layer, wherein the left side is the graphene oxide layer and the right side is the nickel metal layer.

[0034] Figure 3 This is a scanning electron microscope image of the copper-silver alloy wire after surface treatment described in Example 1 of the present invention. DETAILED DESCRIPTION

[0035] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments and comparative examples. Its purpose is to understand the content of the present invention in detail, rather than to limit the present invention. All other embodiments obtained by those of ordinary skill in the art without making creative work premise all fall within the protection scope of the present invention. The experimental reagents and instruments involved in the implementation of the present invention are all conventional common reagents and instruments unless otherwise specified.

[0036] Example 1

[0037] An embodiment of a surface treatment method for a copper-silver alloy wire according to the present invention comprises the following steps:

[0038] (1) A copper-silver alloy wire to be treated with a silver content of 2.1 wt% and a diameter of 3 mm was cleaned with ethanol and 30% volume concentration hydrochloric acid in sequence, then ultrasonically treated in ethanol for 10 min, dried, and then a nickel metal layer was deposited on the surface by electroplating, cleaned, and dried. Figure 1 As shown; During the deposition process, a copper-silver alloy wire is placed in the electroplating solution 1 as the anode, and a ring of pure nickel is used as the cathode and the anode is located at the center of the cathode. 2 The electroplating solution 1 was prepared by mixing 100 mL of ultrapure water, 16 g of nickel sulfate hexahydrate, and 1.2 g of boric acid;

[0039] (2) Electroplating and depositing a graphene oxide layer on the nickel metal layer, and drying it, such as Figure 2 As shown; during the electroplating deposition, a copper-silver alloy wire with a nickel metal layer deposited thereon is used as an anode and placed in an electroplating solution 2, a ring-shaped platinum electrode is used as a cathode and the anode is located at the center of the cathode, the distance between the anode and the cathode is 2 cm, the voltage during deposition is set to 3 V, and deposition is performed for 40 seconds; the electroplating solution 2 is obtained by dispersing 0.08 g of graphene oxide with a planar particle size of 20 μm (produced by Shenzhen Suiheng Technology Co., Ltd.) in 100 mL of ultrapure water and ultrasonically stirring for 10 minutes to form a stably dispersed suspension;

[0040] (3) The copper-silver alloy wire after the nickel metal layer and the graphene oxide layer were deposited was placed in a tube furnace, and the temperature was raised to 420°C at 8°C / min in a hydrogen atmosphere for a first heat preservation treatment for 10 minutes, and then the atmosphere was changed to an argon atmosphere, and the temperature was raised to 900°C at 8°C / min for a second heat preservation treatment for 20 minutes, thus completing the surface treatment. Figure 3 shown.

[0041] Example 2

[0042] The embodiment of the surface treatment method of a copper-silver alloy wire described in the present invention is different from Example 1 only in that the voltage during the electroplating deposition of the graphene oxide layer in step (2) is 5V.

[0043] Example 3

[0044] The embodiment of the surface treatment method of a copper-silver alloy wire described in the present invention is different from Example 1 only in that the voltage during the electroplating deposition of the graphene oxide layer in step (2) is 7V.

[0045] Example 4

[0046] The embodiment of the surface treatment method of a copper-silver alloy wire described in the present invention is different from Example 1 only in that the voltage during the electroplating deposition of the graphene oxide layer in step (2) is 10V.

[0047] Example 5

[0048] The embodiment of the surface treatment method of a copper-silver alloy wire of the present invention is different from the embodiment 1 only in that the current density of the nickel deposition is 4 mA / cm 2 .

[0049] Example 6

[0050] The embodiment of the surface treatment method of a copper-silver alloy wire of the present invention is different from the embodiment 1 only in that the current density of the nickel deposition is 10 mA / cm 2 .

[0051] Comparative Example 1

[0052] A surface treatment method for a copper-silver alloy wire comprises the following steps:

[0053] (1) A copper-silver alloy wire to be treated with a silver content of 2.1 wt% and a wire diameter of 3 mm was cleaned with ethanol and 30% volume concentration hydrochloric acid in sequence, then ultrasonically treated in ethanol for 10 min and dried;

[0054] (2) electroplating a graphene oxide layer on the treated copper-silver alloy wire and drying it; during the electroplating deposition, the copper-silver alloy wire is placed in the electroplating solution as the anode, the annular platinum electrode is used as the cathode and the anode is located at the center of the cathode, the distance between the anode and the cathode is 2 cm, the voltage during deposition is set to 3 V, and the deposition is performed for 40 seconds; the electroplating solution is obtained by dispersing 0.08 g of graphene oxide with a plane particle size of 20 μm (produced by Shenzhen Suiheng Technology Co., Ltd.) in 100 mL of ultrapure water and ultrasonically stirring for 10 minutes to form a stably dispersed suspension;

[0055] (3) The copper-silver alloy wire after the graphene oxide layer is deposited is placed in a tubular furnace, and the temperature is raised to 420°C at 8°C / min in a hydrogen atmosphere for a first heat preservation treatment of 10 minutes. Then, the atmosphere is changed to an argon atmosphere, and the temperature is raised to 900°C at 8°C / min for a second heat preservation treatment of 20 minutes, thereby completing the surface treatment.

[0056] Comparative Example 2

[0057] A surface treatment method for a copper-silver alloy wire is provided, which differs from Example 1 only in that the copper-silver alloy wire after the nickel metal layer and the graphene oxide layer are deposited is not subjected to step (3).

[0058] Comparative Example 3

[0059] A surface treatment method for a copper-silver alloy wire comprises the following steps:

[0060] The copper-silver alloy wire to be treated with a silver content of 2.1 wt% and a wire diameter of 3 mm was cleaned with ethanol and 30% volume concentration hydrochloric acid in sequence, then placed in ethanol for ultrasonic treatment for 10 minutes, dried, and then placed in a tube furnace. The temperature was pre-heated to 420°C at 8°C / min in a hydrogen atmosphere for a first insulation treatment of 10 minutes, and then the atmosphere was changed to an argon atmosphere, and the temperature was raised to 900°C at 8°C / min for a second insulation treatment of 20 minutes to complete the surface treatment.

[0061] Comparative Example 4

[0062] A surface treatment method for a copper-silver alloy wire, which differs from Example 1 only in that the current density of the nickel deposition is 2 mA / cm 2 .

[0063] Effect Example 1

[0064] In order to verify the treatment effect of the surface treatment method of the copper-silver alloy wire of the present invention, the copper-silver alloy wire after surface treatment in each embodiment and comparative example was subjected to the following tests:

[0065] (1) Conductivity test: The conductivity is measured by the double-arm bridge method, using a domestic Applent AT512 precision resistance meter with a measuring range of 0.1μΩ-110MΩ and a test accuracy of 0.01%. The calculation formula is as follows:

[0066] ;

[0067] Where ρ is the resistivity, R is the measured resistance, S is the cross-sectional area of the sample, and L is the length of the sample. 2 ·m -1 ) is converted to the relative conductivity of the sample (IACS%);

[0068] (2) Layer bonding strength test: The bonding strength was tested by the pull-out method using a BGD500 digital display film and coating adhesion tester with a test range of <10 MPa. The test method was to select the same composition, parameters and steps as in each embodiment to prepare and test the coating on a copper-silver plate with a thickness of 2 mm and a size of 30*30 mm. The calculation formula is as follows:

[0069] ;

[0070] Where P is the bonding strength, F is the tensile force, and S is the force-bearing area.

[0071] The test results are shown in Table 1.

[0072] Table 1

[0073]

[0074] It can be clearly seen from Table 1 that the processing method of the copper-silver alloy wire of the present invention not only effectively improves the electrical conductivity of the copper-silver alloy wire, but also has high interlayer bonding strength and strong practicality. In addition, the method has low difficulty in preparing the liquid used in its implementation, low requirements on process equipment, and can be implemented on a factory scale. Figure 1 and 2 It can be seen that after the nickel metal layer is deposited on the copper-silver alloy wire and the graphene oxide layer is further deposited, the two-layer structure does not undergo obvious mixing, e.g. Figure 2 As shown, the left side is the graphene oxide layer, while the nickel particles of the nickel metal layer can be clearly observed on the right side, indicating that both exist in layered form. After heat treatment, Figure 3 As shown, it can be seen that the copper-silver alloy wire, the nickel metal layer and the reduced graphene oxide layer form a sandwich structure, and the folds and edges of the reduced graphene oxide layer are clear and complete, completely covering the copper-silver alloy wire and the nickel metal layer and having continuity. Such a structure ensures the overall high conductivity of the product and the bonding between high layers.

[0075] In contrast, the method in Comparative Example 1 lacks an intermediate nickel metal layer. Even though the graphene oxide layer is subsequently reduced, the reduced graphene oxide layer falls off directly due to the lack of wettability between the graphene oxide layer and the copper-silver alloy wire, resulting in almost no bonding strength between the two. In Comparative Example 2, although an intermediate nickel metal layer and a surface graphene oxide layer are provided, no subsequent heat treatment is performed. Consequently, the graphene oxide layer cannot be reduced, resulting in poor conductivity. Furthermore, no coupling occurs between the nickel metal layer and the graphene oxide layer, and even if it does not fall off, there is still almost no bonding strength between the layers. The copper-silver alloy wire in Comparative Example 3 undergoes only heat treatment without any surface treatment, resulting in a conductivity of less than 95%, which is the normal conductivity level achieved by heat-treated copper-silver alloy wire with this silver content in the prior art. In the scheme described in Comparative Example 4, the current density during electroplating of the nickel metal layer was too low. Since the thickness of the deposited nickel metal in this application scheme is only nanometers, the nickel content in the product is relatively low, which does not significantly affect the conductivity. However, if the deposition current density is too low, the deposited nickel metal layer will not enhance the bonding strength between the graphene oxide layer and the copper-silver alloy wire. Furthermore, the inventors have verified that the bonding strength achieved by the graphene layer construction method in the product of the present invention is far superior to existing products that directly grow graphene on the nickel metal layer using methods such as deposition and laser induction. This will not be further elaborated here.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the present invention.

Claims

1. A surface treatment method for a copper-silver alloy wire, characterized in that: The following steps are involved: (1) After cleaning the copper-silver alloy wire to be treated, a nickel metal layer is deposited on the surface; the current density of the nickel metal layer during electroplating is 4-10 mA / cm 2 ;; (2) electroplating and depositing a graphene oxide layer on the nickel metal layer; the voltage during the electroplating and depositing of the graphene oxide layer is 5 to 7 V; (3) The copper-silver alloy wire after the nickel metal layer and the graphene oxide layer are deposited is pre-treated at 350-450°C in a reducing atmosphere, and then subjected to a second-stage heat preservation treatment at 800-950°C in an inert atmosphere, thereby completing the surface treatment.

2. The surface treatment method of the copper-silver alloy wire according to claim 1, characterized in that: The specific steps of cleaning the copper-silver alloy wire in step (1) are as follows: The copper-silver alloy was washed with alcohol and hydrochloric acid in sequence, and then ultrasonically treated in alcohol.

3. The surface treatment method of the copper-silver alloy wire according to claim 1, wherein: The nickel metal layer is deposited by electroplating.

4. The surface treatment method of the copper-silver alloy wire according to claim 3, characterized in that: The electroplating solution used when the nickel metal layer is deposited by electroplating includes water, a nickel source and a pH adjuster.

5. The surface treatment method of the copper-silver alloy wire according to claim 4, characterized in that: The mass ratio of the water volume to the nickel source and the pH adjuster is 100 mL: (8-20) g: (1-2.5) g.

6. The surface treatment method of the copper-silver alloy wire according to claim 1, wherein: The deposition time of the nickel metal layer during electroplating is 1 to 6 minutes.

7. The surface treatment method of the copper-silver alloy wire according to claim 1, wherein: The concentration of graphene oxide in the electroplating solution used for electroplating and depositing the graphene oxide layer in step (2) is 0.5-2 g / L; the planar particle size of the graphene oxide is 10-30 μm.

8. The surface treatment method of the copper-silver alloy wire according to claim 1, wherein: The time for electroplating and depositing the graphene oxide layer is 10 to 60 seconds.

9. The surface treatment method of the copper-silver alloy wire according to claim 1, wherein: In the step (3), the time for the first stage heat preservation treatment and / or the second stage heat preservation treatment is 5 to 60 minutes.

10. The surface treatment method of the copper-silver alloy wire according to claim 1, wherein: The heating rate during the first-stage heat preservation treatment and / or the second-stage heat preservation treatment is 5-10°C / min.

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