Modified discharge electrode of an ion wind generating device and method for modifying and use thereof

Abstract

This invention provides a modified discharge electrode for an ion wind generator, its modification method, and its application. The modified discharge electrode includes a needle-mesh electrode structure, wherein the needle tip surface of the modified discharge electrode is provided with a carbon nanotube layer and a protective layer located on the surface of the carbon nanotube layer. The modified discharge electrode provided by this invention, with its needle-mesh electrode structure undergoing dual modification of the needle tip surface with carbon nanotubes and a protective layer, exhibits good electrical and thermal conductivity, excellent heat dissipation, and reduced contact resistance between the needle tip and the discharge electrode. It also improves the energy conversion efficiency and stability of the ion wind generator.

Description

Technical Field

[0001] This invention belongs to the technical field of ion wind generating devices, and relates to a modified discharge electrode for ion wind generating devices, its modification method, and its application. Background Technology

[0002] Ionizing wind generators have wide applications in air purification, electrostatic dust removal, and gas transmission. Traditional ionizing wind generators use metal wires or metal meshes as discharge electrodes, but these structures are easily affected by the external environment, leading to unstable performance.

[0003] For example, CN204329183U discloses an ion wind generating device, including a housing with an air inlet and an air outlet. Inside the housing, along the direction from the air inlet to the air outlet, a wire electrode, a cylindrical electrode, and a flat electrode are arranged in sequence. The wire electrode is connected to the positive terminal of a DC power supply, the cylindrical electrode is grounded, and the flat electrode is connected to the negative terminal of a DC power supply. An ionization field is formed between the wire electrode and the cylindrical electrode, and an accelerating electric field is formed between the cylindrical electrode and the flat electrode.

[0004] Furthermore, needle-mesh discharge electrode structures have emerged, such as CN108870530A, which relates to an ion wind generating device and an indoor air conditioning unit. The ion wind generating device includes at least one discharge module for generating ion wind. Each discharge module includes: a mesh electrode extending perpendicular to the airflow direction of the ion wind generating device; a plurality of needle electrodes distributed downstream of the mesh electrode along the airflow direction of the ion wind generating device, with the tips of the needle electrodes pointing towards the mesh electrode; a needle holder for fixing the plurality of needle electrodes; and a shielding mesh disposed on the side of the needle holder opposite to the mesh electrode, with a gap formed between the shielding mesh and the needle holder to prevent the needle electrodes from discharging toward the side opposite to the mesh electrode.

[0005] The generation of ion wind originates from the principle of corona discharge: when a certain high voltage is applied between the needle electrode (i.e., the corona electrode) and the receiving electrode (i.e., the grid electrode), a forward corona discharge is generated. The gas near the tip of the needle electrode is ionized, forming hundreds of millions of ions. These ions combine with air molecules or dust particles, making them charged. Under the influence of the high-voltage electric field, they are rapidly attracted by the receiving electrode, maintaining their inertia and continuing to move, forming a beneficial ion wind. However, using a higher voltage also increases power consumption.

[0006] Therefore, how to improve the performance of corona discharge electrodes and enhance the energy conversion efficiency and stability of ion wind generators is an urgent technical problem to be solved. Summary of the Invention

[0007] The purpose of this invention is to provide a modified discharge electrode for an ion wind generator, its modification method, and its application. The modified discharge electrode provided by this invention features a needle-mesh electrode structure with a needle tip surface modified by both carbon nanotubes and a protective layer. This results in excellent electrical and thermal conductivity, good heat dissipation, reduced contact resistance between the electrode and the discharge electrode, and improved energy conversion efficiency and stability of the ion wind generator.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a modified discharge electrode for an ion wind generator, the modified discharge electrode comprising a needle-mesh electrode structure, wherein the needle tip surface of the modified discharge electrode is provided with a carbon nanotube layer and a protective layer located on the surface of the carbon nanotube layer.

[0010] The needle-mesh electrode structure provided by this invention is a conventional structure in ion wind generating devices. Its specific connection relationship and structural type can be adapted to meet actual needs.

[0011] The modified discharge electrode structure of this invention is stable, featuring a dual-modification structure of carbon nanotube layer and protective layer (nanomaterial modification). The carbon nanotubes have a high aspect ratio, exhibiting excellent conductivity, mechanical strength, and chemical stability. When coated on the electrode tip, they can give the discharge electrode a smaller radius of curvature, enhancing the local electric field strength. The protective layer improves the electrode surface morphology, increasing the stability of the discharge electrode. Simultaneously, the low work function of the material in the protective layer and the high aspect ratio of the carbon nanotubes result in good electrical and thermal conductivity, leading to excellent heat dissipation, enhanced oxidation resistance, and reduced contact resistance with the discharge electrode. Furthermore, it alters the microstructure of the electrode surface, affecting the electric field distribution near the discharge electrode, significantly reducing the turn-on voltage, increasing wind speed, and decreasing the generated ozone concentration, thereby improving the energy conversion efficiency and stability of the ion wind generator.

[0012] In this invention, if a protective layer is not provided on the surface of the carbon nanotube layer, it is impossible to protect the carbon nanotube coating, increase the conductivity of the discharge electrode, and reduce the contact resistance between the carbon nanotube layer and the discharge electrode. On the other hand, if the modification is purely a protective layer, it is impossible to achieve the goal of giving the discharge electrode a smaller radius of curvature and enhancing the local electric field strength. That is, in this invention, the dual modification structure of the carbon nanotube layer and the protective layer is indispensable, and the order cannot be changed. Once changed, it is impossible to modify the discharge electrode of the ion wind generator to have good conductivity and thermal conductivity, good heat dissipation, reduce the contact resistance between the discharge electrode and the discharge electrode, and improve the energy conversion efficiency and stability of the ion wind generator.

[0013] Preferably, the diameter of the carbon nanotubes is <5nm, such as 1nm, 2nm, 3nm, 4nm or 4.5nm.

[0014] Preferably, the length of the carbon nanotube is 5~15μm, such as 5μm, 8μm, 10μm, 13μm or 15μm.

[0015] In this invention, by controlling the diameter and length of carbon nanotubes, the stability of the nano-coating can be better increased and the discharge electrode can have a smaller radius of curvature, thereby enhancing the local electric field strength.

[0016] Preferably, the material in the protective layer includes a metallic compound and / or a non-metallic compound.

[0017] The material of the protective layer in this invention has high chemical and thermal stability.

[0018] Preferably, the metal compound includes any one or a combination of at least two of titanium dioxide, aluminum nitride, or aluminum oxide.

[0019] Preferably, the non-metallic compound includes any one or a combination of at least two of silicon dioxide, silicon nitride, boron nitride, or silicon carbide.

[0020] Preferably, the needles in the needle-mesh electrode structure include tungsten needles.

[0021] In this invention, the needles in the needle-mesh electrode structure are made of tungsten, which can better achieve high-temperature stability, excellent electrical conductivity, enhanced mechanical strength and wear resistance, as well as good chemical stability.

[0022] Preferably, the mass ratio of the carbon nanotubes to the material of the protective layer is (0.4~0.7):1, for example, 0.4:1, 0.5:1, 0.6:1 or 0.7:1, etc.

[0023] In this invention, if the mass ratio of carbon nanotubes to the mass of the protective layer material is too large, i.e., too many carbon nanotubes, the discharge resistance will increase; if the mass ratio is too small, i.e., too few carbon nanotubes, the electrode discharge effect will be affected.

[0024] In a second aspect, the present invention provides a method for modifying the modified discharge electrode of the ion wind generating device as described in the first aspect, the modification method comprising the following steps:

[0025] The tip surface of the unmodified discharge electrode is brought into contact with carbon nanotube sol and sintered. Then the tip is brought into contact with the protective layer sol again and heat-treated to obtain the modified discharge electrode of the ion wind generator.

[0026] The preparation method provided by this invention involves obtaining carbon nanotubes on the needle tip surface and then sintering them. This solidifies the carbon nanotubes and gives the discharge electrode a smaller radius of curvature. Further heat treatment after obtaining the protective layer can further fuse with the carbon nanotubes, protecting the carbon nanotube coating. Moreover, the preparation method provided by this invention is simple to operate, has high practical value and economic benefits, can effectively control the uniformity and stability of the coating, and is suitable for large-scale production.

[0027] In this invention, without sintering and heat treatment, it is impossible to solidify the nanomaterial coating, and the protective layer cannot be fused with the carbon nanotube coating, thus affecting the lifespan and performance of the nanocoating.

[0028] Preferably, the needles in the unmodified discharge electrode are first cleaned.

[0029] Preferably, the preparation of the carbon nanotube sol includes: mixing carbon nanotubes with an organic solvent, grinding, and stirring.

[0030] Preferably, the concentration of carbon nanotubes in the carbon nanotube sol is 4~70 mg / mL, such as 4 mg / mL, 5 mg / mL, 10 mg / mL, 20 mg / mL, 30 mg / mL, 40 mg / mL, 50 mg / mL, 60 mg / mL or 70 mg / mL.

[0031] Preferably, the organic solvent includes ethyl cellulose and / or terpineol.

[0032] In this invention, the sol in the protective layer can be adapted to different materials.

[0033] Preferably, the sintering includes performing a first sintering and a second sintering in sequence.

[0034] In this invention, the first sintering serves to dry the carbon nanotube sol, removing the organic solvents. The subsequent second sintering improves the adhesion strength and stability of the carbon nanotube coating. Without the second sintering, the coating will have poor adhesion, insufficient bonding strength, instability, and impaired functionality, leading to the risk of the carbon nanotube coating peeling off. Furthermore, the uncured carbon nanotube coating may release uncured components or volatile organic compounds, posing potential risks to human health or the environment. Moreover, the subsequent sintering process in this invention is carried out in at least two steps, and furthermore, multiple sintering steps can be performed.

[0035] Preferably, the temperature of the first sintering is 180~250℃, such as 180℃, 200℃, 230℃ or 250℃.

[0036] Preferably, the sintering time is 5 to 10 minutes, such as 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, or 10 minutes.

[0037] Preferably, the temperature of the secondary sintering is 320~380℃, such as 320℃, 330℃, 340℃, 350℃, 360℃, 370℃ or 380℃.

[0038] Preferably, the secondary sintering time is 25-35 min, such as 25 min, 26 min, 27 min, 28 min, 29 min, 30 min, 31 min, 32 min, 33 min, 34 min, or 35 min.

[0039] In this invention, if the secondary sintering temperature is too low, it will not be conducive to the complete curing of the coating and will result in insufficient bonding strength between the coating and the substrate. If the temperature is too high, it will cause the carbon nanotube structure to be destroyed, causing it to lose its original shape and properties, and will damage or deform the substrate material, causing it to lose its original shape and properties.

[0040] Preferably, the heat treatment includes performing a first heat treatment and a second heat treatment in sequence.

[0041] In this invention, the primary heat treatment serves to dry the protective layer, while the secondary heat treatment further enhances the adhesion strength and stability of the protective coating. Without the secondary heat treatment, the protective coating would have poor adhesion and poor bonding with the carbon nanotube coating. Furthermore, the heat treatment process in this invention involves at least two steps, and can further include multiple steps.

[0042] Preferably, the temperature of the primary heat treatment is 150~170℃, such as 150℃, 160℃ or 170℃.

[0043] Preferably, the duration of the heat treatment is 5 to 15 minutes, such as 5 minutes, 8 minutes, 10 minutes, 13 minutes, or 15 minutes.

[0044] Preferably, the temperature of the secondary heat treatment is 320~380℃, such as 320℃, 330℃, 340℃, 350℃, 360℃, 370℃ or 380℃.

[0045] Preferably, the duration of the secondary heat treatment is 25 to 35 minutes, such as 25 minutes, 26 minutes, 27 minutes, 28 minutes, 29 minutes, 30 minutes, 31 minutes, 32 minutes, 33 minutes, 34 minutes, or 35 minutes.

[0046] In this invention, if the temperature of the secondary heat treatment is too low, it will affect the complete curing of the coating and result in insufficient bonding strength between the coating and the carbon nanotube coating. If the temperature is too high, it will cause damage to the carbon nanotube structure in the protective layer and result in surface defects of the titanium dioxide coating, thus affecting the electrode discharge effect.

[0047] Preferably, the contact method includes dipping.

[0048] As a preferred technical solution, the modification method includes the following steps:

[0049] The tip surface of the cleaned, unmodified discharge electrode is dipped in carbon nanotube sol and sintered at 180-250°C for 5-10 minutes, followed by a second sintering at 320-380°C for 25-35 minutes. After the second sintering, the tip is dipped in protective layer sol again and heat-treated at 150-170°C for 5-15 minutes, followed by a second heat treatment at 320-380°C for 25-35 minutes to obtain the modified discharge electrode of the ion wind generator.

[0050] Thirdly, the present invention provides an ion wind generating device, the ion wind generating device comprising the modified discharge electrode as described in the first aspect.

[0051] The ion wind generator provided by this invention, whose discharge module employs the modified discharge electrode provided by this invention, has broad application prospects and significant application value in fields such as air purification, electrostatic dust removal, and gas transmission. For example, in the field of air purification, the ion wind generator of this invention can effectively remove bacteria, viruses, and harmful substances from the air; in the field of electrostatic dust removal, the ion wind generator of this invention can effectively remove dust and pollutants from industrial waste gas; and in the field of gas transmission, the ion wind generator of this invention can be used to accelerate gas flow and transmission.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] The modified discharge electrode structure of this invention is stable, featuring a dual-modification structure of carbon nanotube layer and protective layer (nanomaterial modification). The carbon nanotubes have a high aspect ratio, exhibiting excellent conductivity, mechanical strength, and chemical stability. When coated on the electrode tip, they can give the discharge electrode a smaller radius of curvature, enhancing the local electric field strength. The protective layer improves the electrode surface morphology, increasing the stability of the discharge electrode. Simultaneously, the low work function of the material in the protective layer and the high aspect ratio of the carbon nanotubes result in good electrical and thermal conductivity, leading to excellent heat dissipation, enhanced oxidation resistance, and reduced contact resistance with the discharge electrode. Furthermore, it alters the microstructure of the electrode surface, affecting the electric field distribution near the discharge electrode, significantly reducing the turn-on voltage, increasing wind speed, and decreasing the generated ozone concentration, thereby improving the energy conversion efficiency and stability of the ion wind generator. Detailed Implementation

[0054] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0055] Example 1

[0056] This embodiment provides a modified discharge electrode for an ion wind generator. The modified discharge electrode has a needle-mesh electrode structure. The needle tip surface of the modified discharge electrode is provided with a carbon nanotube layer and a TiO2 layer located on the surface of the carbon nanotube layer (the mass ratio of carbon nanotube to TiO2 is 0.5:1).

[0057] The modification method for the modified discharge electrode is as follows:

[0058] (1) Carbon nanotube sol and TiO2 sol were prepared;

[0059] Carbon nanotube sol: CNTs with a purity >90%, a diameter of less than 5nm, and a length of 10μm are dissolved in ethyl cellulose and terpineol organic slurry at a mass ratio of 1 / 20. The mixture is continuously ground in a mortar to make it uniform, and then magnetically stirred for 4 hours to obtain carbon nanotube sol.

[0060] TiO2 sol: Mix a mixed solution of tetrabutyl titanate-anhydrous ethanol with a mixed solution of glacial acetic acid-concentrated hydrochloric acid, grind the sol solution continuously in a mortar until it is uniform, and then stir magnetically for 4 hours to obtain TiO2 sol.

[0061] (2) Dip the tip of the cleaned bare tungsten needle (cleaned with acetone, isopropanol and deionized water under ultrasonic conditions) into CNTs sol, put it into a box-type resistance furnace, dry it at 200°C for 10 minutes (first sintering), and then anneal it at 350°C for 30 minutes (second sintering). After cooling, take it out.

[0062] (3) Dip the needle tip into TiO2 sol again, put it into a box-type resistance furnace, dry it at 160°C (first heat treatment), then bake it at 350°C for 30 minutes (second heat treatment), and take it out after cooling to obtain the modified discharge electrode.

[0063] Example 2

[0064] This embodiment provides a modified discharge electrode for an ion wind generator. The modified discharge electrode has a needle-mesh electrode structure. The needle tip surface of the modified discharge electrode is provided with a carbon nanotube layer and a TiO2 layer located on the surface of the carbon nanotube layer (the mass ratio of carbon nanotube to TiO2 is 0.7:1).

[0065] The modification method for the modified discharge electrode is as follows:

[0066] (1) Carbon nanotube sol and TiO2 sol were prepared;

[0067] Carbon nanotube sol: CNTs with a purity >90%, a diameter less than 5nm, and a length of 12μm were dissolved in ethyl cellulose and terpineol organic slurry at a mass ratio of 1 / 20. The mixture was continuously ground in a mortar to make it uniform, and then magnetically stirred for 4 hours to obtain carbon nanotube sol.

[0068] TiO2 sol: Mix a mixed solution of tetrabutyl titanate-anhydrous ethanol with a mixed solution of glacial acetic acid-concentrated hydrochloric acid, grind the sol solution continuously in a mortar until it is uniform, and then stir magnetically for 4 hours to obtain TiO2 sol.

[0069] (2) Dip the tip of the cleaned bare tungsten needle (cleaned with acetone, isopropanol and deionized water under ultrasonic conditions) into CNTs sol, put it into a box-type resistance furnace, dry it at 250°C for 5 minutes (first sintering), and then anneal it at 370°C for 25 minutes (second sintering). After cooling, take it out.

[0070] (3) Dip the needle tip into TiO2 sol again, put it into a box-type resistance furnace, dry it at 170°C (first heat treatment), then bake it at 370°C for 25 minutes (second heat treatment), and take it out after cooling to obtain the modified discharge electrode.

[0071] Example 3

[0072] This embodiment provides a modified discharge electrode for an ion wind generator. The modified discharge electrode has a needle-mesh electrode structure. The needle tip surface of the modified discharge electrode is provided with a carbon nanotube layer and a TiO2 layer located on the surface of the carbon nanotube layer (the mass ratio of carbon nanotube to TiO2 is 0.4:1).

[0073] The modification method for the modified discharge electrode is as follows:

[0074] (1) Carbon nanotube sol and TiO2 sol were prepared;

[0075] Carbon nanotube sol: CNTs with a purity >90%, a diameter less than 5nm, and a length of 15μm are dissolved in ethyl cellulose and terpineol organic slurry at a mass ratio of 1 / 20. The mixture is continuously ground in a mortar to make it uniform, and then magnetically stirred for 4 hours to obtain carbon nanotube sol.

[0076] TiO2 sol: Mix a mixed solution of tetrabutyl titanate-anhydrous ethanol with a mixed solution of glacial acetic acid-concentrated hydrochloric acid, grind the sol solution continuously in a mortar until it is uniform, and then stir magnetically for 4 hours to obtain TiO2 sol.

[0077] (2) Dip the tip of the cleaned bare tungsten needle (cleaned with acetone, isopropanol and deionized water under ultrasonic conditions) into CNTs sol, put it into a box-type resistance furnace, dry it at 180°C for 10 minutes (first sintering), and then anneal it at 320°C for 30 minutes (second sintering). After cooling, take it out.

[0078] (3) Dip the needle tip into TiO2 sol again, put it into a box-type resistance furnace, dry it at 170°C (first heat treatment), then bake it at 320°C for 30 minutes (second heat treatment), and take it out after cooling to obtain the modified discharge electrode.

[0079] Example 4

[0080] The difference between this embodiment and Embodiment 1 is that the protective layer in this embodiment is boron nitride (BN), and the TiO2 sol is replaced with boron nitride (BN) sol in the preparation method.

[0081] The remaining modification methods and parameters are consistent with those in Example 1.

[0082] Example 5

[0083] The difference between this embodiment and Embodiment 1 is that the mass ratio of carbon nanotubes to TiO2 in this embodiment is 0.3:1.

[0084] The remaining modification methods and parameters are consistent with those in Example 1.

[0085] Example 6

[0086] The difference between this embodiment and Embodiment 1 is that the mass ratio of carbon nanotubes to TiO2 in this embodiment is 0.8:1.

[0087] The remaining modification methods and parameters are consistent with those in Example 1.

[0088] Example 7

[0089] The difference between this embodiment and embodiment 1 is that a secondary sintering process is not performed in step (2) of this embodiment.

[0090] The remaining modification methods and parameters are consistent with those in Example 1.

[0091] Example 8

[0092] The difference between this embodiment and embodiment 1 is that the secondary sintering temperature in step (2) of this embodiment is 300℃.

[0093] The remaining modification methods and parameters are consistent with those in Example 1.

[0094] Example 9

[0095] The difference between this embodiment and embodiment 1 is that the secondary sintering temperature in step (2) of this embodiment is 400℃.

[0096] The remaining modification methods and parameters are consistent with those in Example 1.

[0097] Example 10

[0098] The difference between this embodiment and embodiment 1 is that a secondary heat treatment process is not performed in step (3) of this embodiment.

[0099] The remaining modification methods and parameters are consistent with those in Example 1.

[0100] Example 11

[0101] The difference between this embodiment and embodiment 1 is that the temperature of the secondary heat treatment in step (2) of this embodiment is 300℃.

[0102] The remaining modification methods and parameters are consistent with those in Example 1.

[0103] Example 12

[0104] The difference between this embodiment and embodiment 1 is that the temperature of the secondary heat treatment in step (2) of this embodiment is 400℃.

[0105] The remaining modification methods and parameters are consistent with those in Example 1.

[0106] Comparative Example 1

[0107] The difference between this comparative example and Example 1 is that the discharge electrode in this comparative example is not modified in any way.

[0108] Comparative Example 2

[0109] The difference between this comparative example and Example 1 is that the modified discharge electrode in this comparative example does not have a protective TiO2 layer on the surface of the carbon nanotube layer, and step (3) is not performed in the preparation method.

[0110] The remaining modification methods and parameters are consistent with those in Example 1.

[0111] Comparative Example 3

[0112] The difference between this comparative example and Example 1 is that the tip surface of the modified discharge electrode in this comparative example is directly a TiO2 layer, and the preparation method does not include the process of dipping carbon nanotube sol in step (2).

[0113] The remaining modification methods and parameters are consistent with those in Example 1.

[0114] Comparative Example 4

[0115] The difference between this comparative example and Example 1 is that the modified discharge electrode in this comparative example has a TiO2 layer on the tip surface and a carbon nanotube layer on the surface of the TiO2 layer (i.e., the order is reversed).

[0116] In the preparation method, the order of steps (2) and (3) is adapted to be swapped.

[0117] The remaining modification methods and parameters are consistent with those in Example 1.

[0118] The discharge electrodes provided in Examples 1-12 and Comparative Examples 1-4 were subjected to performance tests under the following conditions:

[0119] Test Scenario: The electrode spacing was set to 15cm, with a copper mesh as the lower electrode and a needle electrode as the upper electrode. A 1-100kV electrostatic generator was used for power supply. Different tungsten needles were used with alligator clips to change the test conditions. The output voltage of the high-voltage power supply was adjusted until the first discharge phenomenon occurred, and the current voltage value was recorded as the turn-on voltage. A velocimeter was placed in the ion wind channel, as close as possible to the ion wind generator to minimize the influence of environmental factors. The velocimeter was started, and multiple measurements were taken. The measured wind speeds were recorded, and the average wind speed of the ion wind was calculated. The test results are shown in Table 1.

[0120] After a 48-hour continuous discharge test on the discharge electrodes with various test adjustments, surface wear and cracks were observed under a microscope. Based on the observed coating surface condition, the coatings of Example 7, Comparative Example 2, and Comparative Example 4 showed obvious cracks and partial peeling. The remaining electrodes were then subjected to a 72-hour continuous discharge test again. Only the surfaces of Examples 8, 10, 11, and 12 showed wear, while the surfaces of the remaining electrode needles remained almost unchanged from before the discharge.

[0121] Table 1

[0122]

[0123] The data results from Examples 1, 5, and 6 show that an excessively high mass ratio of carbon nanotubes to materials in the protective layer will increase the discharge resistance, while an excessively low mass ratio will affect the electrode discharge effect.

[0124] The data results from Examples 1 and 7-9 show that after obtaining the carbon nanotube layer, simply performing a single sintering and drying process without a second sintering will not achieve a firm adhesion of the carbon nanotube coating to the tungsten needle surface. If the temperature of the second sintering is too high, the carbon nanotube structure will be destroyed; if the temperature is too low, the coating will not be fully cured, resulting in low bonding strength with the tungsten needle surface.

[0125] The data results from Examples 1 and 10-12 show that after obtaining the protective layer, simply performing a heat treatment, i.e., drying, without a second heat treatment, cannot improve the adhesion strength and stability of the protective coating. If the temperature of the second heat treatment is too high, it will not be conducive to the curing of the coating surface, resulting in surface defects and affecting the discharge effect. If the temperature is too low, it will lead to insufficient bonding strength between the coating and the carbon nanotubes.

[0126] The data results from Example 1 and Comparative Example 1 show that without any modification to the discharge electrode, the performance of the discharge electrode in the ion wind generator cannot be improved.

[0127] The data from Example 1 and Comparative Examples 2-4 show that only by adopting the technical solution provided by this invention, namely, the dual modification of the carbon nanotube layer and the protective layer in a fixed order, can the discharge electrode simultaneously achieve good electrical and thermal conductivity, good heat dissipation, reduced contact resistance between the discharge electrode and the electrode, and improved energy conversion efficiency and stability of the ion wind generator. Changing any one of the conditions will not improve the performance of the discharge electrode.

[0128] In summary, the discharge electrode structure provided by this invention undergoes a multi-step sintering and heat treatment process during modification. The needle tip surface of its needle-mesh electrode structure is modified with both carbon nanotubes and a protective layer, resulting in good electrical and thermal conductivity, good heat dissipation, reduced contact resistance between the electrode and the discharge electrode, and improved energy conversion efficiency and stability of the ion wind generator.

[0129] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A modified discharge electrode for an ion wind generator, characterized in that, The modified discharge electrode includes a needle-mesh electrode structure, wherein the needle tip surface of the modified discharge electrode is provided with a carbon nanotube layer and a protective layer located on the surface of the carbon nanotube layer. The mass ratio of the carbon nanotubes to the material of the protective layer is (0.4~0.7):1; The material in the protective layer includes a metal compound and / or a non-metal compound, wherein the metal compound includes any one or a combination of at least two of titanium dioxide, aluminum nitride, or aluminum oxide, and the non-metal compound includes any one or a combination of at least two of silicon dioxide, silicon nitride, boron nitride, or silicon carbide. The modified discharge electrode of the ion wind generator is prepared by the following method: The tip surface of the unmodified discharge electrode is brought into contact with carbon nanotube sol and sintered. Then the tip is brought into contact with the protective layer sol again and heat-treated to obtain the modified discharge electrode of the ion wind generator. The sintering includes a first sintering and a second sintering, and the heat treatment includes a first heat treatment and a second heat treatment.

2. The modified discharge electrode of an ion wind generating device according to claim 1, characterized in that The diameter of the carbon nanotubes is <5nm.

3. The modified discharge electrode of an ion wind generating device according to claim 1, characterized in that, The length of the carbon nanotubes is 5~15μm.

4. The modified discharge electrode of an ion wind generating device according to claim 1, characterized in that, The needles in the needle-mesh electrode structure include tungsten needles.

5. A method of modifying the discharge electrode of an ion wind generating device as defined in claim 1, characterized by The modification method includes the following steps: The tip surface of the unmodified discharge electrode is brought into contact with carbon nanotube sol and sintered. Then the tip is brought into contact with the protective layer sol again and heat-treated to obtain the modified discharge electrode of the ion wind generator. The sintering includes a first sintering and a second sintering, and the heat treatment includes a first heat treatment and a second heat treatment. The temperature of the first sintering is 180~250℃, the temperature of the second sintering is 320~380℃, the temperature of the first heat treatment is 150~170℃, and the temperature of the second heat treatment is 320~380℃.

6. The modification method of the modified discharge electrode of the ion wind generating device according to claim 5, characterized in that, First, clean the needles in the unmodified discharge electrode.

7. The modification method of the modified discharge electrode of the ion wind generating device according to claim 5, characterized by, The preparation of the carbon nanotube sol includes: mixing carbon nanotubes with an organic solvent, grinding, and stirring.

8. The modification method of the modification discharge electrode of the ion wind generating apparatus according to claim 5, characterized by, The concentration of carbon nanotubes in the carbon nanotube sol is 4~70 mg / mL.

9. The modification method of the modified discharge electrode of the ion wind generating device according to claim 7, characterized in that, The organic solvents include ethyl cellulose and / or terpineol.

10. The modification method of the modification discharge electrode of the ion wind generating apparatus according to claim 5, characterized by, The sintering time for one sintering cycle is 5-10 minutes.

11. The modification method of the modification discharge electrode of the ion wind generating apparatus according to claim 5, characterized by, The secondary sintering time is 25-35 minutes.

12. The modification method of the modification discharge electrode of the ion wind generating apparatus according to claim 5, characterized by, The duration of the heat treatment is 5-15 minutes.

13. The modification method of the modification discharge electrode of the ion wind generating apparatus according to claim 5, characterized by, The duration of the secondary heat treatment is 25-35 minutes.

14. The modification method of the modification discharge electrode of the ion wind generating apparatus according to claim 5, characterized by, The contact method includes dipping.

15. The modification method of the modification discharge electrode of the ion wind generating apparatus according to claim 5, characterized by, The modification method includes the following steps: The tip surface of the cleaned, unmodified discharge electrode is dipped in carbon nanotube sol and sintered at 180-250°C for 5-10 minutes, followed by a second sintering at 320-380°C for 25-35 minutes. After the second sintering, the tip is dipped in protective layer sol again and heat-treated at 150-170°C for 5-15 minutes, followed by a second heat treatment at 320-380°C for 25-35 minutes to obtain the modified discharge electrode of the ion wind generator.

16. An ion wind generating device, characterized by The ion wind generating device includes the modified discharge electrode as described in any one of claims 1-4.

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