An online preparation method for carbon nanotube electrodes

Abstract

The present invention discloses an on-line preparation method for a carbon nanotube electrode, comprising the following steps: Step 1, mounting the carbon nanotube electrode on a holding mechanism provided on the Z-axis connecting seat of a three-coordinate moving platform; Step 2, sleeving a liquid film mechanism provided in an electrodeposition tank onto the carbon nanotube electrode; Step 3, adding a solution of KMnO4 / KClO3 / H2SO4 in a certain proportion at the closed loop of the liquid film mechanism, connecting the carbon nanotube electrode to the positive pole of a power source, connecting the liquid film mechanism to the negative pole of the power source, and performing electrochemical anodization treatment on the carbon nanotube electrode. By performing electrochemical anodization treatment on the surface of the carbon nanotube electrode, impurities remaining on all or partial positions on the surface of the carbon nanotube electrode during the production process can be accurately and effectively removed on-line, carbon chains are broken and hybridized, and the proposed carbon nanotube electrode is used for electrolytic cutting of difficult-to-machine materials, improving the processing efficiency, and ultimately improving the shape accuracy and surface quality of the parts made of the difficult-to-machine materials being processed.

Description

Technical Field

[0001] The present invention belongs to the fields of nanotechnology and precision engineering, and particularly relates to a method for on-line preparation of carbon nanowire electrodes. Background Art

[0002] Compared with natural fibers and traditional chemical fibers, carbon nanowire electrodes are composed of countless single-walled or multi-walled carbon nanotubes that are disordered, continuous, tight, and intertwined, and are significantly different in terms of material and structure.

[0003] The unique assembled structural characteristics of carbon nanowire electrodes endow the fiber interior with a rich interfacial structure. Carbon nanowire electrodes have higher thermal conductivity and mechanical strength than currently developing graphene fibers and polymer artificial fibers, and also have the lightweight and weavability that conventional carbon fibers do not have, facilitating high-performance finishing. Compared with conventional metal wire electrodes, such as copper wires, molybdenum wires, stainless steel wires, etc., they have higher strength, stronger tensile properties, better surface properties, wider applicability, longer working life, lower material cost, less energy loss, and less pollution to the natural environment. Electrochemical cutting uses a micron-scale conductive wire or filament as a tool to remove conductive workpiece materials based on the principle of metal electrochemical anodic dissolution, and processes complex ruled surface components through multi-axis linkage of the wire electrode. Electrochemical cutting inherits many advantages of electrochemical machining and is particularly suitable for machining parts with high surface quality requirements for difficult-to-machine materials. Using a conductive wire as the tool cathode in electrochemical cutting can avoid the complex cathode design and flow field design of conventional electrochemical forming machining, greatly shortening the machining preparation time; using a wire electrode as the tool electrode, the influence of the electrolyte flow field characteristics on the machining accuracy is relatively simple, and it is easier to achieve high-precision machining.

[0004] In electrochemical wire cutting, it is often encountered that difficult-to-machine metal materials with complex material composition, high strength, and high hardness, such as metallic glasses, amorphous alloys, superalloys, etc., are processed. Conventional metal conductive wires are prone to phenomena such as adhesion of electrolysis products, short-circuit discharge in the machining gap, and collision and bending of the metal wire with the workpiece, which affect the original electrical conductivity and mass transfer performance of the metal wire, resulting in unstable electrochemical cutting and poor machining quality. Therefore, there is an urgent need to prepare a new material conductive wire electrode as the tool cathode for electrochemical cutting of difficult-to-machine materials, which can improve the mass transfer efficiency in the electrochemical cutting gap, improve the machining efficiency, and ultimately improve the shape accuracy and surface quality of metallic glass material parts.

[0005] During the production process of carbon nanotube electrodes, impurities are likely to remain, resulting in carbon chain breakage and hybridization, as well as destructive defects such as carbon nanotube bending, slipping, and voids. Before electrolytic cutting, the carbon nanotube electrodes also need to be subjected to electrochemical anodization and electrodeposition treatments. A metal layer is electrodeposited on a local position of the carbon nanotube electrode, while other positions of the carbon nanotube electrode are reserved for electrolytic cutting processing. However, during the electrodeposition process, due to the poor hydrophilicity of the outer wall of the carbon nanotube electrode itself and the large amount of capillary impurities on the surface, when the electrodeposition solution coats its surface, the layer fracture phenomenon is relatively serious, resulting in poor quality. In addition, during electrolytic cutting processing, multiple clamping is likely to cause damage and destruction to the carbon nanotube electrode, affecting its original performance. Therefore, there is an urgent need to find a method to quickly and accurately remove the impurities remaining in the production process, carbon chain breakage and hybridization, as well as destructive defects such as carbon nanotube bending, slipping, and voids at any position on the surface of the carbon nanotube electrode before electrolytic cutting processing, with only one clamping. Summary of the Invention

[0006] The purpose of the present invention is to provide an on-line preparation method for carbon nanotube electrodes to solve the problems existing in the prior art.

[0007] To achieve the above purpose, the present invention provides the following technical solution: An on-line preparation method for carbon nanotube electrodes, comprising the following steps:

[0008] Step 1: Install the carbon nanotube electrode on the holding mechanism provided on the Z-axis connecting seat of the three-coordinate moving platform.

[0009] Step 2: Put the liquid film mechanism provided in the electrodeposition tank onto the carbon nanotube electrode.

[0010] Step 3: Add a KMnO4 / KClO3 / H2SO4 solution at the closed loop of the liquid film mechanism, connect the carbon nanotube electrode to the positive pole of the power supply, and connect the liquid film mechanism to the negative pole of the power supply to perform anodization treatment on the carbon nanotube electrode.

[0011] Step 4: Start the Z-axis movement of the three-coordinate moving platform to drive the carbon nanotube electrode to move up and down in the liquid film mechanism.

[0012] Step 5: Stop the Z-axis movement of the three-coordinate moving platform, remove the KMnO4 / KClO3 / H2SO4 solution at the closed loop of the liquid film mechanism, remove the anodized carbon nanotube electrode from the holding mechanism, put an insulating tube on the anodized carbon nanotube electrode, then reinstall the carbon nanotube electrode with the insulating tube on the holding mechanism, add an electrodeposition solution at the closed loop of the liquid film mechanism, connect the carbon nanotube electrode to the negative pole of the power supply, and connect the liquid film mechanism to the positive pole of the power supply to perform electrodeposition on the non-insulated part of the carbon nanotube electrode, and then start the Z-axis movement of the three-coordinate moving platform.

[0013] Preferably, in the first and second steps, the electroplating tank and the three-coordinate moving platform are both installed on the air-floating platform, and the electroplating tank is located on the side of the three-coordinate moving platform.

[0014] Preferably, in the first step, the holding mechanism includes a coupling connected to the Z-axis connecting seat of the three-coordinate moving platform. The coupling is inserted into the electroplating tank and connected to a fixing frame. A first connecting post penetrates through the top of the fixing frame and is connected to the positive electrode of the power supply through the first connecting post. The lower end of the first connecting post is connected to a first pressing piece. A pressing screw rod is screwed to the bottom of the fixing frame, and the top of the pressing screw rod is connected to a second pressing piece. The carbon nanotube electrode is pressed between the first pressing piece and the second pressing piece.

[0015] Preferably, in the third step, the composition ratio of the KMnO4 / KClO3 / H2SO4 solution is 0.01 - 5.0 mol / L KMnO4, 0.05 - 2.0 mol / L KClO3, and 0.5 - 5.0 mol / L H2SO4.

[0016] Preferably, in the fifth step, the middle part, or the upper part, or the lower part of the carbon nanotube electrode can be sleeved into the insulating tube.

[0017] Preferably, in the second, third, and fourth steps, the liquid film mechanism includes a connecting shaft connected to one side of the inner wall of the electroplating tank. One end of the connecting shaft is connected to a support frame. Two moving blocks are arranged in the support frame. A second connecting post is connected to the moving block. One of the second connecting posts is connected to the negative electrode of the power supply. A sliding opening is arranged at the lower part of one side of the support frame. A liquid film ring is connected to one side of the moving block and the liquid film ring penetrates through the sliding opening. A sleeve opening is arranged on the corresponding inner side of the liquid film ring and the sleeve opening sleeves the carbon nanotube electrode.

[0018] Preferably, a sliding rod penetrates through the moving block, and both ends of the sliding rod are respectively connected to both sides of the inner wall of the support frame. Springs are sleeved at both ends of the sliding rod, and the springs elastically support the moving block until the moving blocks are in mutual contact.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] (1) Through the liquid film mechanism filled with the KMnO4 / KClO3 / H2SO4 solution and moving up and down reciprocally, the surface of the carbon nanotube electrode is subjected to electrochemical anodization treatment, which can accurately and effectively remove the impurities remaining on the surface of the carbon nanotube electrode, all or part of the positions during the production process, carbon chain breakage and hybridization, and damage defects such as carbon tube bending, slipping, and voids;

[0021] (2) It can also enhance the morphological characteristics of the surface micro-texture and the surface nano-scale roughness, improve the hydrophilicity and uniformity, ensure good contact performance with the metal layer, and avoid the occurrence of fracture phenomena in the metal electroplating layer;

[0022] (3) The carbon nanotube electrode is used for electrolytic cutting of difficult-to-machine materials, significantly improving the mass transfer efficiency in the machining gap, enhancing the machining efficiency, and ultimately improving the shape accuracy and surface quality of the parts made of difficult-to-machine materials. Description of the Drawings

[0023] Figure 1 It is a schematic view of the main view of the present invention with a partial section;

[0024] Figure 2 For Figure 1 an enlarged structural schematic view at position a;

[0025] Figure 3 It is a schematic view of the left view of the support frame of the present invention with a partial section;

[0026] Figure 4 It is a partial schematic view of the liquid film ring of the present invention;

[0027] Figure 5 It is a schematic view of mass transfer in the electrolytic machining of the carbon nanotube electrode of the present invention;

[0028] Figure 6 It is a schematic view of mass transfer in the electrolytic machining with a metal tungsten wire as the wire electrode;

[0029] Figure 7 It is a comparison chart of the electrolytic machining efficiency of the carbon nanotube electrode and the metal tungsten wire of the present invention;

[0030] Figure 8 It is a SEM image of the fine slit on the part machined by the carbon nanotube electrode of the present invention;

[0031] Figure 9 It is a SEM image of the fine slit on the part machined with a metal tungsten wire as the wire electrode;

[0032] Figure 10 It is a SEM image of the surface quality of the part machined by the carbon nanotube electrode of the present invention;

[0033] Figure 11 It is a SEM image of the surface quality of the part machined with a metal tungsten wire as the wire electrode.

[0034] In the figure: 1 air-floating platform, 2 electroplating tank, 3 three-coordinate moving platform, 4 coupling shaft, 6 fixing frame, 7 first connecting post, 8 first pressing piece, 9 pressing screw rod, 10 second pressing piece, 12 connecting shaft, 13 support frame, 14 moving block, 15 sliding rod, 16 spring, 17 second connecting post, 18 sliding opening, 19 liquid film ring, 20 sleeve opening, 21 carbon nanotube electrode, 26 metal tungsten wire, 23 workpiece made of difficult-to-machine material, 24 bubbles, 25 solid products. Detailed Embodiments

[0035] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0036] Refer to Figure 1 、 Figure 2 、 Figure 3 and Figure 4 , a method for on-line preparation of a carbon nanotube electrode, comprising the following steps:

[0037] Step 1: Install a carbon nanotube electrode on the holding mechanism provided on the Z-axis connecting seat of the three-coordinate moving platform 3. The holding mechanism includes a coupling shaft 4 flange-connected to the Z-axis connecting seat of the three-coordinate moving platform 3. The coupling shaft 4 is inserted into the electro-deposition tank 2 and connected with a fixing frame 6. The coupling shaft 4 and the fixing frame 6 are an integral part, and the material is polytetrafluoroethylene. The fixing frame 6 is of a U-shaped plate structure. A first connecting post 7 is slidably inserted through a through hole provided at the top of the fixing frame 6 and connected to the positive electrode of the power supply through the first connecting post 7. The lower end of the first connecting post 7 is connected with a first pressing piece 8. The first connecting post 7 and the first pressing piece 8 are an integral part. A pressing screw rod 9 is screwed at the bottom of the fixing frame 6, and the top of the pressing screw rod 9 is connected with a second pressing piece 10. The pressing screw rod 9 and the second pressing piece 10 are an integral part. When the pressing screw rod 9 is locked, the carbon nanotube electrode is pressed between the first pressing piece 8 and the second pressing piece 10, stabilizing the vertical state of the carbon nanotube electrode;

[0038] Step 2: Put the liquid film mechanism provided in the electro-deposition tank 2 on the carbon nanotube electrode. Both the electro-deposition tank 2 and the three-coordinate moving platform 3 are screwed to the air-floating platform 1, and the electro-deposition tank 2 is located on the right side of the three-coordinate moving platform 3;

[0039] Step 3: Add a KMnO4 / KClO3 / H2SO4 solution into the closed loop of the liquid film mechanism. Connect the carbon nanotube electrode to the positive electrode of the power supply and the liquid film mechanism to the negative electrode of the power supply, and perform anodization treatment on the carbon nanotube electrode. The component ratio of the KMnO4 / KClO3 / H2SO4 solution is 2.5 mol / L KMnO4, 1.8 mol / L KClO3, 4 mol / L H2SO4. The power supply voltage is supplied by a 15V power supply. And a positive and negative conversion switch is connected to the output line of the power supply, and the output end of the positive and negative conversion switch is connected to the first connecting post 7 and the second connecting post 17, and the positive and negative poles can be changed according to the positive and negative poles of the anodization treatment and the electro-deposition treatment;

[0040] Step 4: Start the Z-axis movement of the three-coordinate moving platform 3 to drive the carbon nanotube electrode to move up and down in the liquid film mechanism. During the process of driving the carbon nanotube electrode to reciprocate, anodization of the entire surface of the carbon nanotube electrode is realized, which not only improves the hydrophilicity of the outer wall of the carbon nanotube electrode itself, but also during the anodization treatment, the capillary impurities on the surface of the carbon nanotube electrode are peeled off during the anodic replacement process;

[0041] In Step Two, Step Three, and Step Four, the liquid film mechanism includes a connecting shaft 12 welded to the right inner wall of the electrodeposition tank 2. The left end of the connecting shaft 12 is welded with a support frame 13. Two moving blocks 14 are slidably arranged in the support frame 13. The top of the moving block 14 is connected to a second connecting post 17. The moving block 14, the second connecting post 17, and the liquid film ring 19 are an integral part. One of the second connecting posts 17 is connected to the negative electrode of the output of the power supply. A sliding opening 18 is provided at the lower left side of the support frame 13. The left side of the moving block 14 is connected with a liquid film ring 19. The liquid film ring 19 slidably penetrates through the sliding opening 18. A sleeve opening 20 is provided on the corresponding inner side of the liquid film ring 19. The sleeve opening 20 sleeves the carbon nanotube electrode. A sliding rod 15 is inserted into the moving block 14 and both ends of the sliding rod 15 are respectively connected to both sides of the inner wall of the support frame 13. Springs 16 are sleeved at both ends of the sliding rod 15. The springs 16 are of the compression and rebound type. The initial compression and rebound force of the springs 16 is 15 Newtons. And under the elastic support of the springs 16, the two liquid film rings 19 are mutually attached to form a closed-loop state. In this closed-loop state, the closed-loop part is the upper part of the joint between the sleeve opening 20 and the liquid film ring 19. During the anodization treatment and the electrodeposition treatment of the electrodeposition solution in Step Five, a complete liquid film can be formed on the outer surface of the carbon nanotube electrode, making the anodization treatment and the electrodeposition treatment on the surface of the carbon nanotube electrode more uniform.

[0042] Step Five: Stop the Z-axis movement of the three-coordinate moving platform 3. Remove the KMnO4 / KClO3 / H2SO4 solution inside the closed-loop part of the liquid film mechanism. Remove the anodized carbon nanotube electrode from the holding mechanism, and sleeve an insulating tube in the middle of the anodized carbon nanotube electrode. Then reinstall the carbon nanotube electrode sleeved with the insulating tube on the holding mechanism. Add an electrodeposition solution to the closed-loop part of the liquid film mechanism. The electrodeposition solution is selected according to the material of the electrodeposited metal layer. The carbon nanotube electrode is connected to the negative electrode of the power supply, and the liquid film mechanism is connected to the positive electrode of the output of the power supply. Electrodeposition is carried out on the non-insulated part of the carbon nanotube electrode. Then start the Z-axis movement of the three-coordinate moving platform 3. During the reciprocating movement of the Z-axis of the three-coordinate moving platform 3, electrodeposition is carried out on the surface of the carbon nanotube electrode. There is no electrodeposition layer on the part with the insulating tube. The thickness of the metal coating is controlled by adjusting the current density and time of electrodeposition. The greater the current density and the longer the time, the thicker the metal coating.

[0043] The carbon nanotube electrode 21 and the metal tungsten wire 22 are respectively used as tools for electrolytic cutting of difficult-to-machine materials 23. Through experiments, it is found that as Figure 5 and Figure 6 shown, compared with the metal tungsten wire 22, when using the carbon nanotube electrode 21, the bubbles 24 and the solid products 25 in the electrolytic cutting processing gap are significantly reduced, significantly improving the mass transfer efficiency in the processing gap.

[0044] As Figure 7As shown, under different voltage amplitude conditions, the use of carbon nanotube electrodes 21 significantly improves the processing efficiency of electrolytic cutting compared to tungsten metal wires 22.

[0045] As Figure 8 and Figure 9 shown, when machining a narrow slit with a width of 17 μm, the use of carbon nanotube electrodes 21 significantly improves the shape accuracy of parts made of difficult-to-machine materials 23 compared to tungsten metal wires 22.

[0046] As Figure 10 and Figure 11 shown, by observing the microscopic surface of the parts, it is found that the use of carbon nanotube electrodes 21 significantly improves the surface quality of parts made of difficult-to-machine materials 23 compared to tungsten metal wires 22.

[0047] The above is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention.

Claims

1. A method for on-line preparation of a carbon nanotube electrode, characterized in that, It includes the following steps: Step 1: Install a carbon nanotube electrode on the holding mechanism provided on the Z-axis connecting seat of the three-coordinate moving platform (3). Step 2: Insert the liquid film mechanism provided in the electro-deposition tank (2) onto the carbon nanotube electrode. Step 3: Add a KMnO4 / KClO3 / H2SO4 solution at the closed loop of the liquid film mechanism. Connect the carbon nanotube electrode to the positive pole of the power supply and the liquid film mechanism to the negative pole of the power supply, and perform anodization treatment on the carbon nanotube electrode. Step 4: Start the Z-axis movement of the three-coordinate moving platform (3) to drive the carbon nanotube electrode to move up and down within the liquid film mechanism. Step 5: Stop the Z-axis movement of the three-coordinate moving platform (3). Remove the KMnO4 / KClO3 / H2SO4 solution at the closed loop of the liquid film mechanism. Remove the anodized carbon nanotube electrode from the holding mechanism, insert an insulating tube onto the anodized carbon nanotube electrode, and then reinstall the carbon nanotube electrode with the insulating tube onto the holding mechanism. Add an electro-deposition solution at the closed loop of the liquid film mechanism. Connect the carbon nanotube electrode to the negative pole of the power supply and the liquid film mechanism to the positive pole of the power supply, and perform electro-deposition on the part of the carbon nanotube electrode without the insulating tube. Step 6: Start the Z-axis movement of the three-coordinate moving platform (3) again.

2. The on-line preparation method of a carbon nanowire electrode according to claim 1, characterized in that: In Steps 1 and 2, both the electro-deposition tank (2) and the three-coordinate moving platform (3) are installed on the air-floating platform (1), and the electro-deposition tank (2) is located on the side of the three-coordinate moving platform (3).

3. The on-line preparation method of a carbon nanowire electrode according to claim 1, characterized in that: In Step 1, the holding mechanism includes a coupling shaft (4) connected to the Z-axis connecting seat of the three-coordinate moving platform (3). The coupling shaft (4) is inserted into the electro-deposition tank (2) and connected to a fixed frame (6). A first connecting post (7) penetrates through the top of the fixed frame (6) and is connected to the positive pole of the power supply through the first connecting post (7). The lower end of the first connecting post (7) is connected to a first pressing piece (8). A pressing screw rod (9) is screwed to the bottom of the fixed frame (6), and the top of the pressing screw rod (9) is connected to a second pressing piece (10). The carbon nanotube electrode is pressed between the first pressing piece (8) and the second pressing piece (10).

4. A method for on-line preparation of a carbon nanotube electrode according to claim 1, characterized in that: In Step 3, the component ratio of the KMnO4 / KClO3 / H2SO4 solution is 0.01 - 5.0 mol / L KMnO4, 0.05 - 2.0 mol / L KClO3, and 0.5 - 5.0 mol / L H2SO4.

5. The online preparation method of a carbon nanowire electrode according to claim 1, characterized in that: In Step 5, the middle part, or the upper part, or the lower part of the carbon nanotube electrode can be inserted into the insulating tube.

6. The on-line preparation method of a carbon nanotube electrode according to claim 1, characterized in that: In the second, third, and fourth steps, the liquid film mechanism includes a connecting shaft (12) connected to one side of the inner wall of the electrodeposition tank (2). One end of the connecting shaft (12) is connected to a support frame (13). Two moving blocks (14) are arranged in the support frame (13). A second connecting post (17) is connected to the moving block (14). One of the second connecting posts (17) is connected to the negative electrode of the power supply. A sliding opening (18) is provided at the lower part of one side of the support frame (13). A liquid film ring (19) is connected to one side of the moving block (14) and the liquid film ring (19) passes through the sliding opening (18). A sleeve opening (20) is provided on the corresponding inner side of the liquid film ring (19) and the sleeve opening (20) is sleeved on the carbon nanotube electrode.

7. The on-line preparation method of a carbon nanowire electrode according to claim 6, characterized in that: A sliding rod (15) is inserted into the moving block (14), and both ends of the sliding rod (15) are respectively connected to both sides of the inner wall of the support frame (13). Springs (16) are sleeved at both ends of the sliding rod (15), and the springs (16) elastically support the moving blocks (14) until the moving blocks (14) are in mutual contact.

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