Preparation method of copper conductor surface protection layer and copper cable

Abstract

The invention provides a preparation method of a copper conductor surface protection layer and a copper cable, and relates to the technical field of cable preparation. The preparation method comprises the following steps: S1, preparing a water solution from sodium nitrate, hydrogen peroxide and sodium bismuthate in a molar ratio of 1: (1-4): (0.01-0.03); and S2, taking the pretreated copper wire as a positive electrode, taking an inert electrode as a negative electrode, and electrifying in the aqueous solution for a set time to obtain the surface protection layer of the copper wire. And meanwhile, after the single wires are stranded, the alternating current resistance of the stranded cable copper conductor is greatly reduced because the surface of each independent single wire is provided with a uniform copper oxide coating.

Description

Technical Field

[0001] The present invention relates to the technical field of cable preparation, and particularly relates to a method for preparing a surface protective layer of a copper wire and a copper wire. Background Art

[0002] Disclosing the information of this background art section is only intended to enhance the overall understanding of the present invention, and it is not necessarily regarded as an admission or an implication in any form that this information constitutes the prior art already known to those of ordinary skill in the art.

[0003] With the continuous construction and development of offshore wind power, the demand for cables used in offshore wind power, submarine connections, and cross-sea and cross-ocean transmissions has also increased significantly. Such products operate in harsh offshore or nearshore environments for a long time. The corrosion and damage of cables caused by changes in temperature, humidity, salinity, airflow, and microorganisms are particularly serious. At the same time, for long-length ultra-high voltage transmission lines, the line losses caused by the AC resistance of the conductors cannot be ignored. Summary of the Invention

[0004] In view of the current technical status, the purpose of the present invention is to provide a method for preparing a surface protective layer of a copper wire and a copper wire. A dense oxide film is coated on the surface of the copper wire by physical and chemical techniques to prevent the occurrence of oxidation reaction corrosion without affecting other properties, and to reduce the AC resistance of the conductor, thereby improving the comprehensive performance of the cable.

[0005] To achieve the above purpose, the present invention is realized through the following technical solutions:

[0006] A method for preparing a surface protective layer of a copper wire, the steps include:

[0007] S1. Prepare an aqueous solution with sodium nitrate, hydrogen peroxide, and sodium bismuthate in a molar ratio of 1:(1 - 4):(0.01 - 0.03) as raw materials;

[0008] S2. Use the pretreated copper wire as the positive electrode and the inert electrode as the negative electrode, and energize for a set time in the aqueous solution to obtain a surface protective layer on the copper wire.

[0009] In the second aspect, a copper wire obtained by the method for preparing a surface protective layer of a copper wire as described above.

[0010] In the third aspect, a copper cable includes a plurality of copper wires twisted together and obtained by the method for preparing a surface protective layer of a copper wire as described above.

[0011] The beneficial effects of the present invention are as follows:

[0012] The preparation method of the present invention is simple to operate, low in cost, has good repeatability, can greatly improve the corrosion resistance and oxidation resistance of copper wires. At the same time, after single-wire stranding, due to the uniform copper oxide coating on the surface of each independent single wire, the AC resistance of the stranded cable copper conductor is greatly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The accompanying drawings forming a part of this invention are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0014] Figure 1 It is the macroscopic photograph of the sample prepared in Example 1.

[0015] Figure 2 It is the scanning photograph of the sample prepared in Example 1.

[0016] Figure 3 It is the XRD detection result diagram of the branches of the sample prepared in Example 1.

[0017] Figure 4 It is the scanning electron microscope image of the sample prepared in Example 3 after 2000 h of salt spray corrosion resistance. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] It should be noted that the following detailed description is exemplary and is intended to provide further illustration of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0019] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0020] One or more specific embodiments of the present invention provide a method for preparing a surface protection layer for a copper wire, and the steps include:

[0021] S1. Prepare an aqueous solution with sodium nitrate, hydrogen peroxide and sodium bismuthate in a molar ratio of 1:(1-4):(0.01-0.03) as raw materials;

[0022] S2. Use the pre-treated copper wire as the positive electrode and the inert electrode as the negative electrode, and energize for a set time in the aqueous solution to obtain a surface protection layer on the copper wire.

[0023] Under the action of current, sodium bismuthate will improve the oxidation ability of the system. The obtained protective layer includes nano-copper oxide particles, which have excellent corrosion resistance and oxidation resistance, and can withstand 2000 h of 3.5% salt spray without any change.

[0024] Optionally, in S1, the molar concentration of the sodium nitrate is (0.1-2) mol / L.

[0025] Optionally, in S1, the molar concentration of the sodium nitrate is 0.2 mol / L or 1 mol / L.

[0026] Optionally, in S1, the aqueous solution is at room temperature to prevent the decomposition of hydrogen peroxide.

[0027] Optionally, in S2, the pretreatment is electrolytic polishing to obtain good surface quality, so that a uniform and dense protective layer can be formed on the surface of the copper wire in step S2.

[0028] Optionally, in S2, the raw materials for preparing the electrolytic polishing solution used in the electrolytic polishing include phosphoric acid, oxalic acid and acetic acid with a molar ratio of (1-50):(2-10):(50-100); among them, due to the low dissociation characteristics of acetic acid, it can adjust the surface quality obtained by electrolytic polishing through the self-limitation of oxide dissolution. Phosphoric acid and oxalic acid can react with metals or their oxides on the surface to generate salts with high viscosity. These salts form viscous films in supersaturated solutions, which contribute to the flatness and smoothness of the surface during the electrolytic polishing process to improve the surface quality of the polished sample.

[0029] Optionally, in S2, the concentration of phosphoric acid in the electrolytic polishing solution is (0.01-0.5) mol / L.

[0030] Optionally, in S2, the electrolytic polishing is carried out for 3-15 min.

[0031] Optionally, in S2, the inert electrode is a graphite electrode or a platinum electrode.

[0032] Optionally, in S2, the electrification process is: electrify for 10-30 min under constant voltage or constant current conditions.

[0033] Optionally, it further includes step S3: after taking out the copper wire, wash it and dry it.

[0034] One or more specific embodiments of the present invention provide a copper cable, which includes a plurality of copper wires twisted together and obtained by the preparation method of the copper wire surface protective layer described above.

[0035] Due to the high adhesion between the protective layer and the internal copper wire, it can resist the mechanical deformation and damage caused by the stranding process. After the stranding is completed, the copper wire surface protective layer still has a high resistance, thereby greatly reducing the AC resistance of the cable copper conductor.

[0036] Example 1

[0037] A preparation method of a surface protection layer for a copper wire, the diameter of the copper wire is 6 mm, and the purity is 99.75%.

[0038] The steps include:

[0039] S0. Prepare an electrolytic polishing solution with a phosphoric acid concentration of 0.01 mol / L, an oxalic acid concentration of 0.1 mol / L, and an acetic acid concentration of 0.5 mol / L. Electrolytically polish the copper wire with a current of 0.02 A and a temperature of 25 °C to complete the pretreatment of the copper wire.

[0040] S1. Dissolve sodium nitrate, hydrogen peroxide, and sodium bismuthate in water. The concentration of sodium nitrate in the solution is 1 mol / L, the concentration of hydrogen peroxide is 2 mol / L, and the concentration of sodium bismuthate is 0.01 mol / L.

[0041] S2. Use the pretreated copper wire as the positive electrode and a high-purity graphite electrode as the negative electrode. Pass an electric current in the solution prepared in S1 in a constant voltage mode for 20 min, and control the voltage at 3 V. During the electrolysis process, control the temperature of the liquid in the electrolytic cell at 20 °C to obtain a surface protection layer on the copper wire.

[0042] S3. Wash and dry the copper wire.

[0043] The macroscopic physical picture of the copper wire with the surface protection layer obtained is as Figure 1 shown. It can be seen that the surface presents a uniform and bright black color.

[0044] Perform metallographic inspection on the range of the protection layer to obtain a metallographic picture as Figure 2 shown: The color of the surface is relatively uniform, indicating that the obtained coating structure is uniform.

[0045] Perform XRD inspection on the range of the protection layer to obtain the results as Figure 3 shown.

[0046] Perform XRF analysis on the surface protection layer on the copper wire surface to obtain the results shown in Table 1. It can be seen that the main component is copper oxide.

[0047] Table 1 XRF analysis results

[0048] Substance name Normalized content % CuO 99.25 NiO 0.015 SrO 0.0985 <![CDATA[Fe2O3]]> 0.0602 CaO 0.022 <![CDATA[K2O]]> 0.03 <![CDATA[SO3]]> 0.06 <![CDATA[P2O5]]> 0.046 <![CDATA[SiO2]]> 0.2 <![CDATA[Al2O3]]> 0.077

[0049] Example 2

[0050] A preparation method of a surface protection layer for a copper wire, the diameter of the copper wire is 2 mm, and the copper content is 99.75%.

[0051] The steps include:

[0052] S0. Prepare an electrolytic polishing solution with a phosphoric acid concentration of 0.5 mol / L, an oxalic acid concentration of 0.02 mol / L, and an acetic acid concentration of 1 mol / L. Electrolytically polish the copper wire with a current of 0.025 A for 12 minutes at 20 °C to complete the pretreatment of the copper wire.

[0053] S1. Dissolve sodium nitrate, hydrogen peroxide, and sodium bismuthate in water. The concentration of sodium nitrate in the solution is 0.2 mol / L, the concentration of hydrogen peroxide is 0.8 mol / L, and the concentration of sodium bismuthate is 0.02 mol / L.

[0054] S2. Use the pretreated copper wire as the positive electrode and the inert electrode as the negative electrode. Pass an electric current in the solution prepared in S1 in a constant current mode for 10 minutes, and control the voltage at 0.002 A. During the electrolysis process, control the temperature of the liquid in the electrolytic cell at 25 °C to obtain a surface protection layer on the copper wire.

[0055] S3. Wash and dry the copper wire.

[0056] Example 3

[0057] Using the copper wire prepared in Example 1 as the raw material, a copper cable is prepared by a conventional stranding process. The corrosion resistance and antioxidant properties of the copper cable after stranding are detected. After 2000 hours of salt spray corrosion, there is no change on the surface.

[0058] After the salt spray corrosion, the conductivity of a single copper wire in the copper cable is detected to be 5.695×10 7 S / m, which is consistent with the detection data of the copper wire obtained in step S3 of Example 1 (the copper wire that has not been stranded and salt spray corroded).

[0059] The surface of the wire after salt spray corrosion is observed by scanning electron microscopy, and the result is as Figure 4 shown. The nanoscale structure of its coating remains intact, indicating that neither the mechanical stress brought by the conventional stranding process nor the salt spray corrosion environment can damage its structure, and the wire can still continue to withstand salt spray corrosion.

[0060] Example 4

[0061] Using the copper wire prepared in Example 2 as the raw material, a copper cable is prepared by a conventional stranding process. The corrosion resistance and antioxidant properties of the copper cable after stranding are detected. After 3000 hours of salt spray corrosion, there is no change on the surface.

[0062] After the salt spray corrosion, the conductivity of a single copper wire in the copper cable is detected to be 5.894×10 7 S / m, which is consistent with the detection data of the copper wire prepared in Example 2 (the copper wire that has not been stranded and salt spray corroded).

[0063] It can be seen that: due to the high adhesion between the protective layer and the internal copper wire, it can resist the mechanical deformation and damage brought by the stranding process, and the protective layer on the surface of the copper wire still has high corrosion resistance after stranding, thus greatly reducing the AC resistance of the cable copper conductor.

[0064] The above are only the preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A method for preparing a surface protective layer of a copper wire, characterized in that the steps Comprising: S1. Prepare an aqueous solution using sodium nitrate, hydrogen peroxide, and sodium bismuthate with a molar ratio of 1:(1 - 4):(0.01 - 0.03) as raw materials. S2. Use the pretreated copper wire as the positive electrode and an inert electrode as the negative electrode, and energize in the aqueous solution for a set time to obtain a surface protection layer on the copper wire.

2. The preparation method of the surface protection layer of the copper wire according to claim 1, wherein, In S1, the molar concentration of the sodium nitrate is (0.1 - 2) mol / L.

3. The preparation method of the surface protection layer of the copper wire as described in claim 1, characterized in that, The pretreatment is electrolytic polishing.

4. The method for preparing the surface protection layer of the copper wire according to claim 3, wherein ,, The preparation raw materials of the electrolytic polishing solution used for the electrolytic polishing include phosphoric acid, oxalic acid, and acetic acid with a molar ratio of (1 - 50):(2 - 10):(50 - 100).

5. The method for preparing the surface protection layer of the copper wire according to claim 4, wherein, The concentration of phosphoric acid in the electrolytic polishing solution is (0.01 - 0.5) mol / L.

6. The method for preparing the surface protection layer of the copper wire according to claim 1, characterized in that, In S2, the inert electrode is a graphite electrode or a platinum electrode.

7. The preparation method of the surface protection layer of the copper wire as described in claim 1, wherein, In S2, the energization process is: energize for 10 - 30 min under constant voltage or constant current conditions.

8. The preparation method of the surface protection layer of the copper wire as described in claim 1, characterized in that, Include step S3. Take out the copper wire, wash it, and dry it.

9. A copper wire obtained by the preparation method of the surface protection layer of a copper wire according to any one of claims 1 - 8.

10. A copper cable, characterized in that, Comprising a plurality of copper wires twisted together as described in claim 9.

Images