Method for preparing high-density aluminum oxide coating by using suspension plasma spraying technology

Abstract

The invention discloses a method for preparing a high-density aluminum oxide coating by using a suspension plasma spraying technology, and relates to the technical field of suspension plasma spraying, and the method comprises the following steps: 1, carrying out sand blasting treatment on an upper electrode plate; sequentially carrying out high-pressure washing, compressed air blow-drying and drying operations; 2, the upper electrode plate is placed in a sulfuric acid solution to be subjected to hard anodic oxidation treatment; 3, a dry ice sand blasting process is adopted for pretreating the hole periphery area of the surface of the steel plate; step 4, injecting the aluminum oxide suspension into high-energy plasma flame flow through plasma spraying equipment; the aluminum oxide particles in the suspension are rapidly molten in the flame flow, then collide with the surface of the upper electrode plate at a high speed along with the plasma flow, and are rapidly cooled and solidified to form a layer of high-compactness aluminum oxide coating on the surface of the upper electrode plate. By optimizing the coating preparation process and parameters, the compactness and corrosion resistance of the coating are improved, the service life of equipment parts is prolonged, and the cost of a production enterprise is reduced.

Description

Technical Field

[0001] This invention relates to the field of suspension plasma spraying technology, and more specifically to a method for preparing a high-density aluminum oxide coating using suspension plasma spraying technology. Background Technology

[0002] Thin-film transistor (TFT) and organic light-emitting diode (OLED) displays are currently the mainstream display devices for terminal devices such as televisions, mobile phones, laptops, and desktop computers. Their production process involves multiple key processes, including masking, development, dry etching, and PECVD. Among these, dry etching, as the core step in patterning, directly affects the resolution and performance of the display. As the cost advantages of large-size display substrates become increasingly apparent, the demand for supporting large-size dry etching equipment continues to grow.

[0003] In dry etching processes, fluorinated process gases such as carbon tetrafluoride (CF4) and sulfur hexafluoride (SF6) are required to achieve precise etching of the substrate material. These gases are highly corrosive, and core components of dry etching equipment, such as the upper electrode plate, are mostly made of aluminum-based materials. Aluminum-based materials are prone to chemical reactions in a fluorinated gas environment, leading to surface corrosion and performance degradation of the components. This not only affects the etching process accuracy but also shortens the equipment's lifespan. Therefore, a protective coating with both corrosion resistance and insulation is needed on the surface of the components to prevent the fluorinated gases from contacting the substrate.

[0004] Al₂O₃ coatings are a preferred material for protective coatings on upper electrode plates due to their excellent chemical stability, insulation, and thermal conductivity. Currently, the industry mainly uses atmospheric plasma spraying (APS) technology to prepare alumina coatings, but this technology has significant limitations: on the one hand, APS technology is limited by equipment power, making it difficult to completely melt large-diameter alumina powder (usually tens of micrometers), resulting in high porosity (approximately 3.5%) within the coating; on the other hand, incompletely melted particles reduce the coating's density and hardness, making the coating insufficiently resistant to fluorine-containing gas corrosion.

[0005] The aforementioned defects directly lead to manufacturers having to frequently shut down and disassemble equipment to maintain or replace corroded parts. This not only increases equipment maintenance costs (including parts procurement costs and labor costs), but also causes a decrease in panel production efficiency due to downtime, making it impossible to meet the needs of large-scale production of large-size displays. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing a high-density aluminum oxide coating using suspended plasma spraying technology. The prepared aluminum oxide coating has better porosity, higher hardness, and stronger resistance to fluorine-containing gas corrosion, which can effectively extend the continuous use time of equipment, shorten the maintenance cycle, thereby improving panel production efficiency and reducing enterprise production costs.

[0007] To achieve the above objectives, the technical solution of this application is: a method for preparing a high-density aluminum oxide coating using suspension plasma spraying technology, comprising: Step 1: Perform sandblasting on the upper electrode plate; after sandblasting, perform high-pressure water washing, compressed air blowing and drying on the upper electrode plate in sequence. Step 2: The upper electrode plate after Step 1 is placed in a sulfuric acid solution for hard anodizing treatment to form an anodized transition layer with a certain thickness and bonding strength on its surface. Step 3: For the upper electrode plate after Step 2, the area around the holes on its surface is pretreated by dry ice sandblasting. Step 4: The prepared aluminum oxide suspension is injected into a high-energy plasma jet through a plasma spraying device; the aluminum oxide particles in the suspension melt rapidly in the jet and then impact the surface of the upper electrode plate at high speed with the plasma jet. After rapid cooling and solidification, a highly dense aluminum oxide coating is formed on the surface of the upper electrode plate.

[0008] In another implementation of the present invention, the sandblasting medium used in step one is silicon carbide sand SiC#80, the pressure during the sandblasting process is controlled at 0.33-0.37MPa, and the surface roughness Ra of the upper electrode plate after sandblasting is in the range of 3-3.5μm.

[0009] In another implementation of the present invention, the pressure of the high-pressure water washing in step one is set to 1900-2100 psi, and the distance between the high-pressure nozzle and the upper electrode plate is maintained at 28-32 cm during the water washing operation; the pressure of the compressed air drying operation is 0.7-0.9 MPa; the temperature conditions of the drying operation are 115-125°C, and the drying duration is 1.5-2.5 hours.

[0010] In another implementation of the present invention, the thickness of the anodic oxide transition layer formed on the surface of the upper electrode plate in step two is 45-55 μm.

[0011] In another implementation of the present invention, the dry ice particles used in the dry ice blasting in step three have a particle size of 0.4-0.55 mm, and the working pressure during the dry ice blasting process is adjusted to 58-62 psi.

[0012] In another implementation of the present invention, the raw materials for preparing the aluminum oxide suspension in step four include aluminum oxide powder, ultrapure water, and a surfactant, wherein the particle size of the aluminum oxide powder is D. 50 =1.0μm, purity >99.9%, conductivity of ultrapure water >18.2MΩ, and the surfactant is polyacrylamide (PAM).

[0013] In another embodiment of the present invention, the preparation process of the aluminum oxide suspension is as follows: first, aluminum oxide powder is mixed with ultrapure water, and after thorough stirring, a suspension with an aluminum oxide mass fraction of 26-29% is formed. Then, a surfactant with a mass fraction of 0.4-0.6%wt is added to the suspension, and stirring is continued until the surfactant is completely dissolved.

[0014] In another implementation of the present invention, the plasma spraying equipment in step four is a 100HE type plasma spraying equipment.

[0015] In another implementation of the present invention, the specific process parameters for plasma spraying in step four are as follows: argon flow rate 115-120 SLPM, nitrogen flow rate 55-57 SLPM, hydrogen flow rate 52-53 SLPM, spray gun power 120-125 KW, water circulation flow rate 240-260 ml / min, spraying voltage 320-340 V, spray gun moving speed 1400-1600 mm / s, spraying distance 72-74 mm, aluminum oxide suspension injection flow rate 32-34 mL / min, and cooling gas pressure 2-3 Bar.

[0016] In another embodiment of the present invention, the high-density aluminum oxide coating has the following performance parameters: coating thickness 100-110μm, coating roughness 2.5-3μm, porosity ≤0.8%, Vickers hardness Hv0.2 of 575-580, and breakdown voltage >6KV.

[0017] By adopting the above technical solution, the present invention can achieve the following technical effects: 1. This invention uses a suspension of small-particle-size alumina powder as raw material, which can achieve more thorough melting in a high-energy plasma flame. When the molten alumina particles impact the substrate surface at high speed with the plasma stream, they can form more numerous and more uniformly spread flat particles, resulting in a tighter bond between coating layers and a significant reduction in porosity. The porosity of coatings prepared by traditional atmospheric plasma spraying (APS) technology is about 3.5%, while the porosity of the coating of this invention is only about 0.8%. The lower porosity combined with higher coating hardness greatly improves the coating's resistance to corrosion by fluorine-containing gases, effectively isolates corrosive gases from contact with the aluminum substrate, and extends the protection cycle of components.

[0018] 2. This invention directly uses small-diameter aluminum oxide powder to prepare suspensions without additional granulation steps, simplifying the raw material pretreatment process and reducing intermediate processing costs. At the same time, small-diameter powder has higher melting efficiency, improving raw material utilization during spraying and further reducing material loss and overall costs in the coating preparation stage.

[0019] 3. The aluminum oxide coating prepared by the present invention covers the upper electrode plate (such as the upper electrode plate), which can achieve an average machine working time of 5-6 times that of traditional APS coated parts in panel manufacturing enterprises, significantly extending the service life of the parts; directly reducing the frequency and cycle of equipment downtime maintenance, reducing the labor and time costs of disassembling and replacing parts, and ultimately improving the operating efficiency of equipment in the panel production process, helping enterprises reduce overall production costs. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the cross-sectional microstructure and porosity (0.77%) of the aluminum oxide coating; Figure 2 The image shows the microhardness test results of the aluminum oxide coating (Hv0.2=577). Figure 3 This is a diagram showing the surface condition of a cut sample of the upper electrode plate of a TFT-LCD after spraying. Detailed Implementation

[0022] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0025] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the accompanying drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0026] Please see Figure 1-3 This embodiment provides a method for preparing a high-density aluminum oxide coating using suspended plasma spraying technology, with the upper electrode plate, a core component of the dry etching equipment, as the processing object. Specifically, the method includes: Step 1: Perform sandblasting on the upper electrode plate; after sandblasting, perform high-pressure water washing, compressed air blowing and drying on the upper electrode plate in sequence. Sandblasting: Select the upper electrode plate to be treated, use silicon carbide sand (SiC#80) as the sandblasting medium, and perform sandblasting on the surface of the upper electrode plate using sandblasting equipment, controlling the sandblasting pressure to 0.35MPa; after sandblasting, test the surface roughness of the upper electrode plate to ensure that it reaches Ra3.5μm, in order to remove surface oxide scale and oil stains and optimize the surface bonding performance of the substrate.

[0027] High-pressure water washing: The upper electrode plate after sandblasting is subjected to high-pressure water washing. The water washing pressure is set to 2000psi, and the distance between the high-pressure nozzle and the upper electrode plate is adjusted to 30cm. The surface of the electrode plate is thoroughly rinsed to remove residual silicon carbide sand debris and dust.

[0028] Compressed air drying: Use compressed air at a pressure of 0.8MPa to blow clean the surface of the upper electrode plate after high-pressure water washing until there are no visible water stains on the surface, so as to avoid moisture residue affecting the subsequent drying effect.

[0029] Drying process: Place the dried upper electrode plate into an oven, set the oven temperature to 120℃, and continue drying for 2 hours; after drying, wait for the electrode plate to cool to room temperature and then take it out for use.

[0030] Step 2: The upper electrode plate after Step 1 is placed in a sulfuric acid solution for hard anodizing treatment to form an anodized transition layer with a certain thickness and bonding strength on its surface. Specifically, the thickness of the oxide layer is monitored in real time during the oxidation process, and an anodic oxide layer with a thickness of 50 μm is finally formed on the surface of the upper electrode plate. This oxide layer can improve the bonding strength between the subsequent aluminum oxide coating and the substrate, and at the same time initially enhance the corrosion resistance of the electrode plate. After oxidation, the surface of the electrode plate is cleaned to remove residual sulfuric acid solution, and then dried.

[0031] Step 3: For the upper electrode plate after Step 2, the area around the holes on its surface is pretreated by dry ice sandblasting. Specifically, dry ice particles with a diameter of 0.5mm are selected, and the dry ice blasting pressure is controlled at 60psi. The focus is on cleaning impurities and oxide layer residues around the holes to ensure that the surface condition around the holes meets the requirements of subsequent spraying.

[0032] Step 4: The prepared aluminum oxide suspension is injected into a high-energy plasma flame through a plasma spraying device; the aluminum oxide particles in the suspension melt rapidly in the flame and then collide with the upper electrode plate at high speed with the plasma flow. After rapid cooling and solidification, a highly dense aluminum oxide coating is formed on the surface of the upper electrode plate. The preparation method of aluminum oxide suspension is as follows: aluminum oxide powder with a particle size of 1μm and a purity of >99.9% is selected and mixed with ultrapure water with a conductivity of >18.2MΩ; the mixture is stirred thoroughly to form a suspension with an aluminum oxide mass fraction of 28%; then a surfactant (composed of polyacrylamide, PAM) with a mass fraction of 0.5%wt is added to the suspension, and stirring is continued until the surfactant is completely dissolved to obtain a uniform and stable aluminum oxide suspension.

[0033] The plasma spraying operation method is as follows: Equipment preparation: Turn on the 100HE plasma spraying equipment (preferably manufactured by Progressive Surface), check the sealing and operating status of each system (gas pipeline, water circulation, feeding device) to ensure that the equipment is working properly.

[0034] Parameter settings: The plasma spraying process parameters are set as follows: argon flow rate 117 SLPM, nitrogen flow rate 56 SLPM, hydrogen flow rate 52 SLPM, spray gun power 120KW, water circulation flow rate 250ml / min, spraying voltage 320V, spray gun moving speed 1500mm / s, spraying distance 73mm, aluminum oxide suspension injection flow rate 34mL / min, and cooling gas pressure 2Bar.

[0035] Coating preparation: The prepared aluminum oxide suspension is injected into a high-energy plasma flame; after the aluminum oxide particles in the suspension melt in the flame, they are impacted at high speed by the plasma flow to the surface of the upper electrode plate; after rapid cooling and solidification, a high-density aluminum oxide coating is formed on the surface of the upper electrode plate.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for producing a highly dense aluminum trioxide coating layer using a suspended plasma spraying technique, characterized in that, The application relates to a method for preparing an upper electrode plate of a high-voltage capacitor. Step one: performing sand blasting treatment on the upper electrode plate; after the sand blasting treatment, sequentially performing high-pressure water washing, compressed air blowing and drying operations on the upper electrode plate; Step two: placing the upper electrode plate treated in step one into a sulfuric acid solution to perform hard anodic oxidation treatment, so as to form an anodic oxidation transition layer with a certain thickness and bonding force on the surface of the upper electrode plate; Step three: adopting dry ice sand blasting process to pretreat the surface hole surrounding area of the upper electrode plate treated in step two; Step four: injecting the prepared aluminum oxide suspension liquid into a high-energy plasma flame through plasma spraying equipment; the aluminum oxide particles in the suspension liquid are rapidly melted in the flame, and then are impacted onto the surface of the upper electrode plate at high speed along with the plasma flow, and a high-dense aluminum oxide coating is formed on the surface of the upper electrode plate after rapid cooling and solidification.

2. A method of preparing high density aluminum trioxide coating using suspension plasma spraying technique as claimed in claim 1 wherein, The sand blasting medium used in the sand blasting treatment in step one is SiC#80, the pressure control in the sand blasting process is 0.33-0.37 MPa, and the surface roughness Ra of the upper electrode plate after the sand blasting treatment is 3-3.5 mu m.

3. A method of preparing high density aluminum oxide coating using suspension plasma spraying as claimed in claim 1, wherein, The pressure of the high-pressure water washing in step one is set to be 1900-2100 psi, and the distance between the high-pressure nozzle and the upper electrode plate is kept to be 28-32 cm during the water washing operation; the pressure of the compressed air blowing in the compressed air blowing operation is 0.7-0.9 MPa; the temperature condition of the drying operation is 115-125 DEG C, and the drying duration is 1.5-2.5 hours.

4. The method of claim 1, wherein the high density aluminum oxide coating is prepared by a suspension plasma spraying technique. The thickness of the anodic oxidation transition layer formed on the surface of the upper electrode plate in step two is 45-55 mu m.

5. The method of claim 1, wherein the high density aluminum oxide coating is prepared by a suspension plasma spraying technique. The particle size of the dry ice used in the dry ice sand blasting in step three is 0.4-0.55 mm, and the working pressure in the dry ice sand blasting process is adjusted to be 58-62 psi.

6. The method of claim 1, wherein the high density aluminum oxide coating is prepared by a suspension plasma spraying technique. The raw materials for preparing the alumina trihydrate suspension in step four include alumina trihydrate powder, ultrapure water and surfactant, wherein the particle size of the alumina trihydrate powder is D 50 = 1.0 μm, the purity is > 99.9%, the conductivity of the ultrapure water is > 18.2 MΩ, and the component of the surfactant is polyacrylamide.

7. The method of making high density aluminum oxide coating using suspension plasma spraying as claimed in claim 1 or 6 wherein, The preparation process of the aluminum oxide suspension liquid is as follows: firstly, mixing aluminum oxide powder and ultrapure water, and then stirring to form an aluminum oxide suspension liquid with an aluminum oxide mass fraction of 26-29%, and then adding a surfactant with a mass fraction of 0.4-0.6%wt into the suspension liquid, and continuing to stir until the surfactant is completely dissolved.

8. The method of claim 1, wherein the high density aluminum oxide coating is prepared by a suspension plasma spraying technique. The plasma spraying equipment in step four is a 100HE type plasma spraying equipment.

9. The method of claim 1, wherein the high density aluminum oxide coating is prepared by a suspension plasma spraying technique. The process parameters of the plasma spraying in step four are as follows: argon flow rate 115-120 SLPM, nitrogen flow rate 55-57 SLPM, hydrogen flow rate 52-53 SLPM, spray gun power 120-125 KW, water circulation flow rate 240-260 ml / min, spraying voltage 320-340 V, spray gun moving speed 1400-1600 mm / s, spraying distance 72-74 mm, aluminum oxide suspension liquid injection flow rate 32-34 mL / min, and cooling gas pressure 2-3 Bar.

10. The method of claim 1, wherein the high density aluminum oxide coating is prepared by a suspension plasma spraying technique. The performance parameters of the high-dense aluminum oxide coating meet the following requirements: coating thickness 100-110 mu m, coating roughness 2.5-3 mu m, porosity <=0.8%, Vickers hardness Hv0.2=575-580, and breakdown voltage >6 KV.

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