Electrode insulating layer, electrode assembly, electrode and preparation method thereof

Abstract

The invention discloses an electrode insulating layer, an electrode assembly, an electrode and a preparation method thereof. The electrode insulating layer is a ceramic film layer arranged on the surface of a metal inner electrode through a sputtering process. The ceramic film layer is used as the electrode insulating layer, and due to the characteristics of high temperature resistance, high wear resistance, corrosion resistance, high breakdown voltage and high resistance of a ceramic material, the service life of the electrode can be effectively ensured; and the ceramic film layer is arranged on the surface of the metal inner electrode through a coating process, so that a gap between the metal inner electrode and the ceramic film layer can be effectively reduced, discharge between the gaps is reduced, the purpose of discharging at a lower voltage is achieved, and the energy utilization rate is further improved.

Description

Technical Field

[0001] The invention relates to the field of glow discharge, and in particular to an electrode insulating layer, an electrode assembly, an electrode and a preparation method thereof. Background Art

[0002] The plasma generated by gas discharge can effectively kill pathogens and degrade most organic gases. It has been applied and promoted in the fields of air disinfection and odor treatment. The plasma discharge commonly used in the field of air purification is mostly corona discharge. Corona discharge is only generated on the electrode surface and the density of active components in the plasma is small, so the air purification effect is limited. Glow discharge has been mentioned more in recent years. It can form a discharge channel between two electrodes. The density of high-energy electrons and active components in its plasma is high, and the air purification effect is better than corona discharge. However, the formation of stable glow discharge is mostly achieved in low pressure and rare gas environments; there are few technologies that can form stable glow discharge under atmospheric pressure, and there are problems such as low discharge efficiency and stability. For example, in Chinese patent application CN114845456A, it relies on a dual high-voltage power supply mode to maintain a stable glow discharge, and the discharge efficiency is not high; for another example, in Chinese patent application CN103731968A, it uses multiple needle electrodes and a ground electrode to generate glow discharge, but its multiple needle electrodes cannot discharge at the same time. Only one needle electrode is in a discharge state at each moment, and the discharge efficiency and stability are not high.

[0003] At present, a carbon fiber spiral glow discharge electrode is disclosed, which adopts a method of arranging spirally wound carbon fibers on a metal inner electrode and arranging an insulating layer between the metal inner electrode and the carbon fibers to achieve the purpose of stable glow discharge under atmospheric pressure. The micro discharge formed by this structural design forms a strong electric field in a local space, creating electric field conditions for the formation of atmospheric pressure air glow discharge. Therefore, the above structure can form a relatively stable glow discharge at a relatively low voltage, and the low-temperature plasma formed by it has a good effect in treating formaldehyde and other pollutants (TVOC) in the air, and has a strong application prospect in the field of air purification.

[0004] In order for the carbon fiber spiral glow discharge electrode to show good results during the research process, it is necessary to ensure the low dielectric constant of the insulating layer and the electret property (high resistance) of the charge, so that the glow discharge under atmospheric pressure can be more effectively achieved at a lower discharge voltage. PTFE (polytetrafluoroethylene) theoretically has extremely high breakdown resistance, and its breakdown field strength is as high as 200KV / mm. Therefore, PTFE is routinely used as the insulating layer of the spiral glow discharge during the research process.

[0005] However, in the actual application and promotion stage, the use of PTFE has the following problems:

[0006] 1. In the actual PTFE production and molding process, due to bubbles, impurities, uniformity of insulation thickness, process cost, etc., the breakdown field strength measured in this device can only reach about 20KV / mm. At individual impurities and bubble points, if the local field strength generated by discharge is too high, local point breakdown under low voltage is likely to occur;

[0007] 2. To achieve stable glow discharge at low voltage, the PTFE insulation layer needs to be very thin, generally less than 0.5mm, and mostly around 0.2mm. However, PTFE has creep characteristics and poor electrical corrosion resistance. The electrode winding area overlaps with the discharge area, so as the discharge time goes on, the insulation layer in the discharge area will become thinner and thinner. Combined with the defects of the PTFE product itself, it is difficult for the product to achieve the ideal service life of more than three years.

[0008] 3. The metal inner electrode and the insulating layer PTFE are not completely tightly fitted (PTFE as a coating can achieve fitting, but the insulation properties of the PTFE coating are worse), so when the voltage is loaded and discharged, the internal metal inner electrode and PTFE will discharge in the gap. The internal discharge amplifies the probability of the insulating layer being damaged, greatly reducing the service life of the product.

[0009] In order to overcome the life problem caused by the above-mentioned insulating layer PTFE, it is possible to try to use alumina ceramic tubes instead of PTFE to achieve long-term stable operation of the product. However, the thickness of alumina ceramic tubes is generally 0.5mm to 10mm. Even if alumina ceramic tubes with a thickness of 0.5mm are used, they still have a high dielectric constant and a thicker insulating layer thickness. Therefore, in order to maintain stable discharge, it can only be achieved by increasing the discharge voltage. In this case, the plasma discharge has shifted from glow discharge to filamentary discharge, and the ozone content has increased significantly, increasing the difficulty of later applications; and there is still a gap problem between the metal electrode and the ceramic tube, and the low energy utilization efficiency caused by internal discharge still exists. In addition, due to the increase in discharge voltage, some new problems such as internal electrode heat release and discharge corrosion also appear. Summary of the invention

[0010] Therefore, the technical problem to be solved by the present invention is the defect of low energy utilization efficiency of the carbon fiber spiral glow discharge electrode in the prior art, thereby providing an electrode insulation layer, an electrode assembly, an electrode and a preparation method thereof that solve the above problem.

[0011] The electrode insulation layer is a ceramic film layer provided on the surface of the metal inner electrode through a coating process.

[0012] In the present invention, all ceramic films obtained by coating process can achieve the effect of improving energy utilization rate; for example: ceramic films obtained by coating process of aluminum nitride, silicon dioxide, silicon nitride and other materials. However, ceramic films made of silicon dioxide have problems such as large internal application, high brittleness, easy cracking, etc., and ceramic films made of aluminum nitride have problems such as high price and poor discharge effect. Therefore, the material of the ceramic film in the present invention is preferably silicon nitride.

[0013] To ensure the insulation and life of the ceramic film layer, the thickness of the ceramic film layer is ≥0.3μm, preferably ≥1μm, and more preferably 1-3μm. The present invention preferably uses a sputtering process to set a ceramic film layer on the surface of the metal inner electrode. Since the film thickness of the ceramic film layer prepared by magnetron sputtering is generally less than 1μm, and most of them are less than 0.3μm, the present invention preferably uses a radio frequency magnetron sputtering method to form a thicker, more uniform, and more insulating ceramic film layer on the surface of the metal inner electrode.

[0014] The present invention also provides an electrode assembly, comprising a metal inner electrode and an electrode insulating layer, wherein the electrode insulating layer is the above-mentioned ceramic film layer disposed on the surface of the metal inner electrode by a coating process.

[0015] As a preferred configuration, in order to avoid deformation of the substrate of the metal inner electrode itself and thus cause failure of the electrode insulation layer, the hardness of the metal inner electrode is ≥30HRC, preferably ≥50HRC; the modulus of the metal inner electrode is ≥150GPa, preferably ≥200GPa.

[0016] In order to simultaneously meet the above requirements of hardness, rigidity and conductivity, the material of the metal inner electrode includes at least one of tungsten steel, H13 die steel and stainless steel. If other substrates can meet the above requirements of hardness, rigidity and conductivity after being processed, they can also be substituted.

[0017] As any implementation method, the shape of the metal inner electrode is cylindrical. When the diameter of the metal inner electrode is ≤3mm, the material of the metal inner electrode is tungsten steel; when the diameter of the metal inner electrode is ≥3mm, the material of the metal inner electrode is H13 mold steel.

[0018] The present invention also provides a method for preparing an electrode assembly, comprising:

[0019] obtaining a metal inner electrode;

[0020] A ceramic film layer is arranged on the surface of the metal inner electrode by using a coating process.

[0021] The coating process can be thermal spraying, plasma spraying, magnetron sputtering, etc. Compared with thermal spraying and plasma spraying, magnetron sputtering can achieve a super-full coating with low defects, which is conducive to the low-voltage realization of carbon fiber spiral glow discharge. That is, in order to make the prepared ceramic film layer have the advantages of being dense, uniform and having few defects, the coating process is preferably a magnetron sputtering process; and since the thickness limit of the ceramic film layer formed by the ordinary magnetron sputtering process can only be 0.3μm, and the ceramic film layer of radio frequency magnetron sputtering can exceed 0.3μm compared with ordinary magnetron sputtering, and the thickness of the ceramic film layer in the present invention is preferably 1μm or more, more preferably 1-3μm, so the coating process of the present invention is preferably a radio frequency magnetron sputtering process.

[0022] The optimization of the surface finish Ra of the inner electrode is to ensure the uniformity of the insulating layer when the coating process is adopted, so as to achieve the purpose of stable insulation; the higher the value of the surface finish Ra, the lower the probability of preparing a uniform insulating layer. When the surface finish Ra reaches more than 0.5μm, it will have a relatively serious impact on the uniformity of the insulating layer. In order to ensure the insulation stability of the ceramic film layer, the surface finish Ra of the metal inner electrode in the present invention is ≤0.5μm, preferably ≤0.2μm.

[0023] In order to prevent tungsten steel or H13 mold steel from rusting under micro-current, the unplated areas need to be potted to form an insulating layer, and a conventional potting glue that isolates air and water vapor can be used. The potting glue can be ordinary polyurethane potting glue or epoxy potting glue. That is, the area on the metal inner electrode not covered with the electrode insulation layer in the present invention is also provided with an insulating layer.

[0024] An electrode comprises the electrode insulating layer or the electrode assembly mentioned above.

[0025] The technical solution of the present invention has the following advantages:

[0026] 1. The electrode insulation layer provided by the present invention is a ceramic film layer disposed on the surface of the metal inner electrode by a sputtering process. In the present invention, a ceramic film layer is used as the electrode insulation layer. Due to the high temperature resistance, high wear resistance, corrosion resistance, high breakdown voltage, and high resistance of the ceramic material, the application life of the electrode can usually be effectively guaranteed; and the ceramic film layer is disposed on the surface of the metal inner electrode by a coating process, which can effectively reduce the gap between the metal inner electrode and the ceramic film layer, reduce the discharge between the gaps, and achieve the purpose of discharging at a lower voltage, thereby improving energy utilization.

[0027] 2. The electrode insulation layer provided by the present invention is preferably made of silicon nitride (Si3N4). Silicon nitride is resistant to high temperatures and corrosion. Except for hydrofluoric acid, the silicon nitride film is almost unaffected by any acid or alkali, and it also has good resistance to Na +At the same time, silicon nitride has extremely high hardness and good wear resistance and scratch resistance. The above comprehensive properties make it have a long service life even in a thinner case. In terms of electrical properties, the dielectric constant of silicon nitride is about 6-8, which is much higher than PTFE's 2, but lower than alumina ceramics' 10. Silicon nitride also has extremely high pressure resistance, and its breakdown field strength is about 10 7 V / cm, resistivity up to 10 17 Ωcm, which can fully meet the electrical performance requirements of glow discharge for the insulating layer.

[0028] 3. The electrode assembly provided by the present invention adopts a ceramic film layer as the electrode insulating layer. When the thickness of the ceramic film layer reaches 1 μm or more, it has the problems of high rigidity and certain internal stress. Therefore, the present invention further optimizes the hardness and modulus of the metal inner electrode, and selects a metal inner electrode composed of a material with high hardness (hardness HRC ≥ 50) and large modulus (modulus ≥ 200 GPa) to avoid deformation of the metal inner electrode causing damage to the ceramic film and causing failure of the insulating layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 is a schematic structural diagram of the electrode assembly of the present invention;

[0031] Figure 2 It is a schematic diagram of the structure of the electrode in the present invention;

[0032] Reference numerals:

[0033] 1-Metal inner electrode, 2-Electrode insulation layer, 3-Carbon fiber. DETAILED DESCRIPTION

[0034] The following examples are provided for a better understanding of the present invention, but are not intended to limit the best mode of implementation, nor to limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0035] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

[0036] Example 1

[0037] An electrode is a carbon fiber spiral glow discharge electrode, such as Figure 1 and Figure 2 As shown, it includes a metal inner electrode, an electrode insulating layer and a spirally wound carbon fiber.

[0038] The diameter of the metal inner electrode in this embodiment is 2 mm, and the material is tungsten steel, with a hardness of 80 HRC and a modulus of 530 GPa.

[0039] The thickness of the electrode insulating layer in this embodiment is 2 μm, and the material is silicon nitride.

[0040] In this embodiment, the diameter of the single filament of the helically wound carbon fiber is 7 μm, the number of filaments is 1000, the distance between adjacent spirals is 2.5 mm, and the number of winding turns is 36 turns.

[0041] The formation process of the above electrodes is as follows:

[0042] Step 1, obtaining the above-mentioned metal inner electrode;

[0043] Step 2: The metal inner electrode is processed by an over-polishing process so that its surface finish Ra is not less than 0.2 μm;

[0044] Step 3: Use radio frequency magnetron sputtering technology to coat the surface of the metal inner electrode to obtain a silicon nitride ceramic film layer with a thickness of 2 μm.

[0045] Step 4, winding carbon fiber in the silicon nitride ceramic film layer area to form a spirally wound carbon fiber, and connecting a high voltage power supply to one end of the metal inner electrode;

[0046] Step 5: The area on the surface of the metal inner electrode where the silicon nitride ceramic film layer is not formed is potted. The potting treatment is: the uncoated area is sealed with polyurethane potting glue to isolate air and water vapor to prevent the metal inner electrode from rusting under micro-current.

[0047] The electrode loading voltage prepared in this embodiment is about 600V, and the continuous discharge time exceeds 120 hours without abnormality.

[0048] Example 2

[0049] An electrode is a carbon fiber spiral glow discharge electrode, comprising a metal inner electrode, an electrode insulating layer and spirally wound carbon fibers.

[0050] The metal inner electrode in this embodiment has a diameter of 3 mm and is made of stainless steel with a hardness of 35 HRC and a modulus of 180 GPa.

[0051] The thickness of the electrode insulating layer in this embodiment is 2 μm, and the material is silicon nitride.

[0052] In this embodiment, the diameter of the single filament of the helically wound carbon fiber is 7 μm, the number of filaments is 1000, the distance between adjacent spirals is 2.5 mm, and the number of winding turns is 36 turns.

[0053] The formation process of the above electrodes is as follows:

[0054] Step 1, obtaining the above-mentioned metal inner electrode;

[0055] Step 2: The metal inner electrode is processed by an over-polishing process so that its surface finish Ra is not less than 0.2 μm;

[0056] Step 3: Use radio frequency magnetron sputtering technology to coat the surface of the metal inner electrode to obtain a silicon nitride ceramic film layer with a thickness of 2 μm.

[0057] Step 4: Wind carbon fiber in the silicon nitride ceramic film layer area to form a spirally wound carbon fiber, and connect a high voltage power supply to one end of the metal inner electrode.

[0058] The electrode loading voltage prepared in this embodiment is about 800V, and the continuous discharge time exceeds 120 hours without abnormality.

[0059] Although stainless steel can be used in this embodiment, there is a probability of risk, mainly due to insufficient hardness. The integrity of the coating is guaranteed under the condition of gentle handling, but under the condition of frequent external force collisions, there is a probability of damage, resulting in insulation layer breakdown.

[0060] Example 3

[0061] An electrode is a carbon fiber spiral glow discharge electrode, comprising a metal inner electrode, an electrode insulating layer and spirally wound carbon fibers.

[0062] The diameter of the metal inner electrode in this embodiment is 5 mm, and the material is H13 mold steel, with a hardness of 53HRC and a modulus of 210GPa.

[0063] The thickness of the electrode insulating layer in this embodiment is 2 μm, and the material is silicon nitride.

[0064] In this embodiment, the diameter of the single filament of the helically wound carbon fiber is 7 μm, the number of filaments is 1000, the distance between adjacent spirals is 2.5 mm, and the number of winding turns is 36 turns.

[0065] The formation process of the above electrodes is as follows:

[0066] Step 1, obtaining the above-mentioned metal inner electrode;

[0067] Step 2: The metal inner electrode is processed by an over-polishing process so that its surface finish Ra is not less than 0.2 μm;

[0068] Step 3: Use radio frequency magnetron sputtering technology to coat the surface of the metal inner electrode to obtain a silicon nitride ceramic film layer with a thickness of 2 μm.

[0069] Step 4, winding carbon fiber in the silicon nitride ceramic film layer area to form a spirally wound carbon fiber, and connecting a high voltage power supply to one end of the metal inner electrode;

[0070] Step 5: The area on the surface of the metal inner electrode where the silicon nitride ceramic film layer is not formed is potted. The potting treatment is: the uncoated area is sealed with polyurethane potting glue to isolate air and water vapor to prevent the metal inner electrode from rusting under micro-current.

[0071] The electrode loading voltage prepared in this embodiment is about 850V, and the continuous discharge time exceeds 120 hours without abnormality.

[0072] Example 4

[0073] An electrode is a carbon fiber spiral glow discharge electrode, comprising a metal inner electrode, an electrode insulating layer and spirally wound carbon fibers.

[0074] The diameter of the metal inner electrode in this embodiment is 2 mm, and the material is tungsten steel, with a hardness of 80 HRC and a modulus of 530 GPa.

[0075] The electrode insulating layer in this embodiment has a thickness of 1 μm and is made of silicon nitride.

[0076] In this embodiment, the diameter of the single filament of the helically wound carbon fiber is 7 μm, the number of filaments is 1000, the distance between adjacent spirals is 2.5 mm, and the number of winding turns is 36 turns.

[0077] The formation process of the above electrodes is as follows:

[0078] Step 1, obtaining the above-mentioned metal inner electrode;

[0079] Step 2: The metal inner electrode is processed by an over-polishing process so that its surface finish Ra is not less than 0.2 μm;

[0080] Step 3: Use radio frequency magnetron sputtering technology to coat the surface of the metal inner electrode to obtain a silicon nitride ceramic film layer with a thickness of 1 μm.

[0081] Step 4, winding carbon fiber in the silicon nitride ceramic film layer area to form a spirally wound carbon fiber, and connecting a high voltage power supply to one end of the metal inner electrode;

[0082] Step 5: The area on the surface of the metal inner electrode where the silicon nitride ceramic film layer is not formed is potted. The potting treatment is: the uncoated area is sealed with polyurethane potting glue to isolate air and water vapor to prevent the metal inner electrode from rusting under micro-current.

[0083] The electrode prepared in this embodiment has a loading voltage of about 500 V, and the continuous discharge time exceeds 120 hours without abnormality.

[0084] Example 5

[0085] An electrode is a carbon fiber spiral glow discharge electrode, comprising a metal inner electrode, an electrode insulating layer and spirally wound carbon fibers.

[0086] The diameter of the metal inner electrode in this embodiment is 2 mm, and the material is tungsten steel, with a hardness of 80 HRC and a modulus of 530 GPa.

[0087] The thickness of the electrode insulating layer in this embodiment is 3 μm, and the material is silicon nitride.

[0088] In this embodiment, the diameter of the single filament of the helically wound carbon fiber is 7 μm, the number of filaments is 1000, the distance between adjacent spirals is 2.5 mm, and the number of winding turns is 36 turns.

[0089] The formation process of the above electrodes is as follows:

[0090] Step 1, obtaining the above-mentioned metal inner electrode;

[0091] Step 2: The metal inner electrode is processed by an over-polishing process so that its surface finish Ra is not less than 0.2 μm;

[0092] Step 3: Use radio frequency magnetron sputtering technology to coat the surface of the metal inner electrode to obtain a silicon nitride ceramic film layer with a thickness of 3 μm.

[0093] Step 4, winding carbon fiber in the silicon nitride ceramic film layer area to form a spirally wound carbon fiber, and connecting a high voltage power supply to one end of the metal inner electrode;

[0094] Step 5: The area on the surface of the metal inner electrode where the silicon nitride ceramic film layer is not formed is potted. The potting treatment is: the uncoated area is sealed with polyurethane potting glue to isolate air and water vapor to prevent the metal inner electrode from rusting under micro-current.

[0095] The electrode loading voltage prepared in this embodiment is about 800V, and the continuous discharge time exceeds 120 hours without abnormality.

[0096] Example 6

[0097] An electrode is a carbon fiber spiral glow discharge electrode, comprising a metal inner electrode, an electrode insulating layer and spirally wound carbon fibers.

[0098] The diameter of the metal inner electrode in this embodiment is 2 mm, and the material is tungsten steel, with a hardness of 80 HRC and a modulus of 530 GPa.

[0099] The thickness of the electrode insulating layer in this embodiment is 5 μm, and the material is silicon nitride.

[0100] In this embodiment, the diameter of the single filament of the helically wound carbon fiber is 7 μm, the number of filaments is 1000, the distance between adjacent spirals is 2.5 mm, and the number of winding turns is 36 turns.

[0101] The formation process of the above electrodes is as follows:

[0102] Step 1, obtaining the above-mentioned metal inner electrode;

[0103] Step 2: The metal inner electrode is processed by an over-polishing process so that its surface finish Ra is not less than 0.2 μm;

[0104] Step 3: Use radio frequency magnetron sputtering technology to coat the surface of the metal inner electrode to obtain a silicon nitride ceramic film layer with a thickness of 5 μm.

[0105] Step 4, winding carbon fiber in the silicon nitride ceramic film layer area to form a spirally wound carbon fiber, and connecting a high voltage power supply to one end of the metal inner electrode;

[0106] Step 5: The area on the surface of the metal inner electrode where the silicon nitride ceramic film layer is not formed is potted. The potting treatment is: the uncoated area is sealed with polyurethane potting glue to isolate air and water vapor to prevent the metal inner electrode from rusting under micro-current.

[0107] The electrode loading voltage prepared in this embodiment is about 900V, and the continuous discharge time exceeds 120 hours without abnormality.

[0108] Example 7

[0109] An electrode is a carbon fiber spiral glow discharge electrode, comprising a metal inner electrode, an electrode insulating layer and spirally wound carbon fibers.

[0110] The diameter of the metal inner electrode in this embodiment is 2 mm, and the material is tungsten steel, with a hardness of 80 HRC and a modulus of 530 GPa.

[0111] The thickness of the electrode insulating layer in this embodiment is 0.3 μm, and the material is silicon nitride.

[0112] In this embodiment, the diameter of the single filament of the helically wound carbon fiber is 7 μm, the number of filaments is 1000, the distance between adjacent spirals is 2.5 mm, and the number of winding turns is 36 turns.

[0113] The formation process of the above electrodes is as follows:

[0114] Step 1, obtaining the above-mentioned metal inner electrode;

[0115] Step 2: The metal inner electrode is processed by an over-polishing process so that its surface finish Ra is not less than 0.2 μm;

[0116] Step 3: Use a common magnetron sputtering process to coat the surface of the metal inner electrode to obtain a silicon nitride ceramic film layer with a thickness of 0.3 μm.

[0117] Step 4, winding carbon fiber in the silicon nitride ceramic film layer area to form a spirally wound carbon fiber, and connecting a high voltage power supply to one end of the metal inner electrode;

[0118] Step 5: The area on the surface of the metal inner electrode where the silicon nitride ceramic film layer is not formed is potted. The potting treatment is: the uncoated area is sealed with polyurethane potting glue to isolate air and water vapor to prevent the metal inner electrode from rusting under micro-current.

[0119] The electrode loading voltage prepared in this embodiment is about 350-400V, and the continuous discharge time exceeds 120 hours without abnormality. The 0.3μm ceramic film layer in the present invention is too thin, and the uniformity of the coating process is very high. In this case, low-voltage discharge can be achieved, but the yield of samples that can be continuously discharged for more than 120 hours prepared by the existing process is not high.

[0120] Example 8

[0121] An electrode is a carbon fiber spiral glow discharge electrode, comprising a metal inner electrode, an electrode insulating layer and spirally wound carbon fibers.

[0122] The diameter of the metal inner electrode in this embodiment is 2 mm, and the material is tungsten steel, with a hardness of 80 HRC and a modulus of 530 GPa.

[0123] The thickness of the electrode insulating layer in this embodiment is 2 μm, and the material is silicon dioxide.

[0124] In this embodiment, the diameter of the single filament of the helically wound carbon fiber is 7 μm, the number of filaments is 1000, the distance between adjacent spirals is 2.5 mm, and the number of winding turns is 36 turns.

[0125] The formation process of the above electrodes is as follows:

[0126] Step 1, obtaining the above-mentioned metal inner electrode;

[0127] Step 2: The metal inner electrode is processed by an over-polishing process so that its surface finish Ra is not less than 0.2 μm;

[0128] Step 3: Use radio frequency magnetron sputtering technology to coat the surface of the metal inner electrode to obtain a silicon dioxide ceramic film layer with a thickness of 2 μm.

[0129] Step 4, winding carbon fiber in the silicon nitride ceramic film layer area to form a spirally wound carbon fiber, and connecting a high voltage power supply to one end of the metal inner electrode;

[0130] Step 5: The area on the surface of the metal inner electrode where the silicon nitride ceramic film layer is not formed is potted. The potting treatment is: the uncoated area is sealed with polyurethane potting glue to isolate air and water vapor to prevent the metal inner electrode from rusting under micro-current.

[0131] The electrode prepared in this embodiment has a loading voltage of about 600 V. Silicon dioxide has large internal stress and relatively low hardness. Even if it is prepared by radio frequency magnetic control, the formed insulating layer has insulation properties, but it is difficult to last for 120 hours at 600 V and is easily burned during continuous discharge.

[0132] Example 9

[0133] An electrode is a carbon fiber spiral glow discharge electrode, comprising a metal inner electrode, an electrode insulating layer and spirally wound carbon fibers.

[0134] The diameter of the metal inner electrode in this embodiment is 2 mm, and the material is tungsten steel, with a hardness of 80 HRC and a modulus of 530 GPa.

[0135] The thickness of the electrode insulating layer in this embodiment is 2 μm, and the material is aluminum nitride.

[0136] In this embodiment, the diameter of the single filament of the helically wound carbon fiber is 7 μm, the number of filaments is 1000, the distance between adjacent spirals is 2.5 mm, and the number of winding turns is 36 turns.

[0137] The formation process of the above electrodes is as follows:

[0138] Step 1, obtaining the above-mentioned metal inner electrode;

[0139] Step 2: The metal inner electrode is processed by an over-polishing process so that its surface finish Ra is not less than 0.2 μm;

[0140] Step 3: Use radio frequency magnetron sputtering technology to coat the surface of the metal inner electrode to obtain an aluminum nitride ceramic film layer with a thickness of 2 μm.

[0141] Step 4, winding carbon fiber in the silicon nitride ceramic film layer area to form a spirally wound carbon fiber, and connecting a high voltage power supply to one end of the metal inner electrode;

[0142] Step 5: The area on the surface of the metal inner electrode where the silicon nitride ceramic film layer is not formed is potted. The potting treatment is: the uncoated area is sealed with polyurethane potting glue to isolate air and water vapor to prevent the metal inner electrode from rusting under micro-current.

[0143] The electrode loading voltage prepared in this embodiment is about 600 V. Aluminum nitride has large internal stress, relatively low hardness, and high rigidity. Even if it is prepared by radio frequency magnetic control, the insulation of the formed insulating layer does not meet the application standard.

[0144] Example 10

[0145] An electrode is a carbon fiber spiral glow discharge electrode, comprising a metal inner electrode, an electrode insulating layer and spirally wound carbon fibers.

[0146] The diameter of the metal inner electrode in this embodiment is 2 mm, and the material is tungsten steel, with a hardness of 80 HRC and a modulus of 530 GPa.

[0147] The thickness of the electrode insulating layer in this embodiment is 2 μm, and the material is silicon nitride.

[0148] In this embodiment, the diameter of the single filament of the helically wound carbon fiber is 7 μm, the number of filaments is 1000, the distance between adjacent spirals is 2.5 mm, and the number of winding turns is 36 turns.

[0149] The formation process of the above electrodes is as follows:

[0150] Step 1, obtaining the above-mentioned metal inner electrode, the surface finish Ra of the metal inner electrode is 0.3 μm;

[0151] Step 2: Use radio frequency magnetron sputtering technology to coat the surface of the metal inner electrode to obtain a silicon nitride ceramic film layer with a thickness of 2 μm.

[0152] Step 3, winding carbon fiber in the silicon nitride ceramic film layer area to form a spirally wound carbon fiber, and connecting a high voltage power supply to one end of the metal inner electrode;

[0153] Step 4: The area on the surface of the metal inner electrode where the silicon nitride ceramic film layer is not formed is potted. The potting treatment is: the uncoated area is sealed with polyurethane potting glue to isolate air and water vapor to prevent the metal inner electrode from rusting under micro-current.

[0154] The electrode loading voltage prepared in this embodiment is about 600V, and the continuous discharge time exceeds 120 hours without abnormality.

[0155] Comparative Example 1

[0156] An electrode is a carbon fiber spiral glow discharge electrode, comprising a metal inner electrode, an electrode insulating layer and spirally wound carbon fibers.

[0157] The diameter of the metal inner electrode in this embodiment is 2 mm, and the material is tungsten steel, with a hardness of 80 HRC and a modulus of 530 GPa.

[0158] The thickness of the electrode insulation layer in this embodiment is 0.5 mm, and the material is PTFE.

[0159] In this embodiment, the diameter of the single filament of the helically wound carbon fiber is 7 μm, the number of filaments is 1000, the distance between adjacent spirals is 2.5 mm, and the number of winding turns is 36 turns.

[0160] The formation process of the above electrodes is as follows:

[0161] Step 1, obtaining the above-mentioned metal inner electrode;

[0162] Step 2: Cover the surface of the metal inner electrode with an electrode insulating layer made of PTFE.

[0163] Step 4: Wind carbon fiber on the electrode insulation layer to form a spirally wound carbon fiber, and connect a high voltage power supply to one end of the metal inner electrode.

[0164] The electrode prepared in this embodiment has a loading voltage of about 1.5 kV and a continuous discharge time of more than 60 hours, and there is a probability of breakdown and burning.

[0165] Comparative Example 2

[0166] An electrode is a carbon fiber spiral glow discharge electrode, comprising a metal inner electrode, an electrode insulating layer and spirally wound carbon fibers.

[0167] The diameter of the metal inner electrode in this embodiment is 2 mm, and the material is tungsten steel, with a hardness of 80 HRC and a modulus of 530 GPa.

[0168] The electrode insulating layer in this embodiment is an alumina ceramic tube with a thickness of 0.5 mm.

[0169] In this embodiment, the diameter of the single filament of the helically wound carbon fiber is 7 μm, the number of filaments is 1000, the distance between adjacent spirals is 2.5 mm, and the number of winding turns is 36 turns.

[0170] The formation process of the above electrodes is as follows:

[0171] Step 1, obtaining the above-mentioned metal inner electrode;

[0172] Step 2: Sleeve the alumina ceramic tube on the surface of the metal inner electrode.

[0173] Step 3: Wind carbon fiber in the alumina ceramic tube area to form a spirally wound carbon fiber, and connect a high voltage power supply to one end of the metal inner electrode.

[0174] The electrode loaded voltage prepared in this embodiment is about 2.5 kV, the ozone content is significantly increased, and the electrode has a more obvious heating phenomenon.

[0175] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. An electrode insulating layer, characterized in that: It is a ceramic film layer set on the surface of the metal inner electrode through a coating process.

2. The electrode insulating layer according to claim 1, characterized in that: The material of the ceramic film layer is silicon nitride.

3. The electrode insulating layer according to claim 1 or 2, characterized in that: The thickness of the ceramic film layer is ≥0.3 μm, preferably ≥1 μm, and more preferably 1-3 μm.

4. An electrode assembly, comprising a metal inner electrode and an electrode insulating layer, characterized in that: The electrode insulating layer is a ceramic film layer provided on the surface of the metal inner electrode by a coating process as described in any one of claims 1 to 3.

5. The electrode assembly according to claim 4, characterized in that: The hardness of the metal inner electrode is ≥30HRC, preferably ≥50HRC; the modulus of the metal inner electrode is ≥150GPa, preferably ≥200GPa.

6. The electrode assembly according to claim 5, characterized in that: The material of the metal inner electrode includes at least one of tungsten steel, H13 mold steel and stainless steel.

7. The electrode assembly according to claim 6, characterized in that: When the diameter of the metal inner electrode is ≤3mm, the material of the metal inner electrode is tungsten steel; when the diameter of the metal inner electrode is ≥3mm, the material of the metal inner electrode is H13 mold steel.

8. The method for preparing an electrode assembly according to any one of claims 4 to 7, characterized in that: include: obtaining a metal inner electrode; A ceramic film layer is arranged on the surface of the metal inner electrode by using a coating process.

9. The preparation method according to claim 8, characterized in that: The coating process is a sputtering process, preferably a radio frequency magnetron sputtering process; and / or, the surface finish Ra of the metal inner electrode is ≤0.5 μm, preferably ≤0.2 μm; And / or, an isolation layer is further provided on the area of ​​the metal inner electrode not covered with the electrode insulation layer.

10. An electrode, characterized in that: It comprises the electrode insulating layer according to any one of claims 1 to 3, or the electrode assembly according to any one of claims 4 to 7.

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