A coating for surface treatment of a scroll plate, and a preparation method and a spraying process thereof

Abstract

The application discloses a coating for surface treatment of a scroll disc, a preparation method and a spraying process thereof, and relates to the technical field of coatings.The modified nano graphite powder is obtained by modifying the nano graphite powder after oxidation treatment through a silane coupling agent, and then combined with polyvinyl alcohol, nano PTFE particles, a dispersing agent, polyvinylpyrrolidone, a leveling agent and ethanol to prepare a high-performance coating for surface treatment of the scroll disc.The coating is sprayed onto the scroll disc through three main steps of preliminary spraying, respraying and final spraying under optimized process parameters by using a trace air pressure self-flowing spray gun and cooperating with a rotary turntable, so that the friction resistance of the scroll disc after spraying is greatly improved, and the service life of the scroll disc is greatly prolonged.

Description

Technical Field

[0001] This application relates to the field of organic synthesis technology, and in particular to a coating for surface treatment of vortex disks, its preparation method and spraying process. Background Technology

[0002] The scroll compressor is the core moving component of a scroll compressor, widely used in residential air conditioning, commercial refrigeration, automotive air conditioning, and heat pump systems. During operation, it undergoes high-speed, continuous relative rolling and sliding friction with its paired scroll, operating at consistently high temperatures while in contact with refrigerant, refrigeration oil, and small amounts of condensate. Therefore, surface treatment is often necessary, such as coating with high-performance paints. Consequently, the performance of the surface coating must meet stringent requirements, including high wear resistance, excellent temperature resistance, good oil and corrosion resistance, high dispersibility, and strong adhesion to the substrate. Furthermore, the spraying process for the coating used on the scroll compressor surface is also crucial, directly affecting the performance of the final scroll compressor surface coating. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this application provides a coating for the surface treatment of scroll disks, its preparation method, and spraying process. Modified nano-graphite powder is obtained by oxidizing nano-graphite powder and then modifying it with a silane coupling agent. This modified nano-graphite powder is then combined with polyvinyl alcohol, nano-PTFE particles, a dispersant, polyvinylpyrrolidone, a leveling agent, and ethanol to prepare a high-performance coating for scroll disk surface treatment. Using a micro-pressure self-flowing spray gun and a rotating turntable, under optimized process parameters, the coating is sprayed onto the scroll disk through three main steps: preliminary spraying, secondary spraying, and final spraying. This significantly improves the friction resistance of the scroll disk after coating, greatly extending its service life.

[0004] To achieve the above objectives, this application adopts the following technical solution:

[0005] In a first aspect, this application provides a coating for surface treatment of a vortex disk, the coating comprising polyvinyl alcohol, modified nano-graphite powder, nano-PTFE particles, dispersant, polyvinylpyrrolidone, leveling agent and ethanol; wherein the modified nano-graphite powder is obtained by oxidizing nano-graphite powder and then modifying it with a silane coupling agent.

[0006] The coating for surface treatment of scroll disks provided in this application possesses excellent wear resistance, a low coefficient of friction, and high adhesion, meeting the stringent working requirements of scroll disks. Furthermore, the coating system exhibits strong stability, with uniform dispersion of all components and no significant agglomeration, resulting in a smooth, defect-free coating surface after spraying. In addition, the coating demonstrates good environmental performance, with low emissions of volatile organic compounds (VOCs), meeting environmental protection requirements.

[0007] In the coating for surface treatment of vortex disks provided in this application, the presence of hydroxyl groups in the polyvinyl alcohol molecular chain promotes adsorption with the vortex disk substrate, and chemical bonding is generated between the coating and the substrate under the action of baking in the spraying process, ensuring strong adhesion between the coating and the substrate.

[0008] Modified nano-graphite powder is produced by oxidizing nano-graphite powder to introduce oxygen-containing active groups such as hydroxyl (-OH) and carboxyl (-COOH) groups onto its surface, resulting in oxidized nano-graphite powder, which increases its reactivity. Furthermore, one end of the silane coupling agent undergoes alkoxy hydrolysis to generate silanol (-Si-OH), which condenses with the oxygen-containing active groups on the surface of the oxidized nano-graphite powder to form chemical bonds, thereby introducing an amino-containing organic group at the other end. This significantly improves the compatibility of the prepared modified nano-graphite powder with components such as polyvinyl alcohol and ethanol. Combined with the use of a dispersant, this solves the problem of easy agglomeration of nano-graphite powder in the coating system of this application. Moreover, the prepared modified nano-graphite powder retains its layered structure with weak interlayer forces, allowing for slippage, thereby further improving the wear resistance and self-lubricating properties of the coating. In addition, the addition of nano-PTFE particles gives the coating a low surface energy, enabling the formation of a lubricating film on the coating surface, thereby further reducing frictional losses during the movement of the vortex disk.

[0009] In one possible implementation, the mass ratio of polyvinyl alcohol, modified nano-graphite powder, nano-PTFE particles, dispersant, polyvinylpyrrolidone, leveling agent and ethanol is (12-18):(1-3):(2-4):(0.3-1):(0.03-0.1):(1-3):(72-82).

[0010] This application optimizes the mass ratio of each component through experiments, so that the coating’s adhesion, wear resistance, lubricity and smoothness are balanced. Therefore, during use and construction, the coating has moderate fluidity, which is convenient for spraying and atomization, and will not cause the coating to sag or be insufficient in thickness due to excessive dilution.

[0011] In one possible implementation, the modified nano-graphite powder has an average particle size of 50-100 nm, and the nano-PTFE particles have an average particle size of 100-200 nm.

[0012] In one possible implementation, the dispersant comprises any one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium tetradecyl sulfate, and sodium octadecylbenzene sulfonate.

[0013] The dispersant used in this application exhibits good compatibility with the coating system and demonstrates excellent dispersion effects on components such as polyvinyl alcohol, modified nano-graphite powder, and nano-PTFE particles, resulting in a long shelf life and minimal sedimentation in the coating. This is because the dispersant molecules used in this application contain both hydrophobic and hydrophilic groups. The hydrophobic groups can be adsorbed onto the surfaces of components such as polyvinyl alcohol and modified nano-graphite powder through van der Waals forces, while the hydrophilic groups face the ethanol solvent. This results in a negatively charged surface on the polyvinyl alcohol and modified nano-graphite powder components, preventing them from agglomerating through electrostatic repulsion, thereby ensuring high overall dispersibility and stability of the coating system.

[0014] In one possible implementation, the leveling agent includes either a silicone-based leveling agent or an acrylate-based leveling agent.

[0015] In one possible implementation, the silicone leveling agent includes any one of BYK-301, BYK-302, BYK-326, BYK-327, BYK-333, BYK-337, and BYK-342; and the acrylate leveling agent includes any one of BYK-350, BYK-352, BYK-354, BYK-355, BYK-356, BYK-361N, and BYK-381.

[0016] In this application, silicone-based leveling agents and acrylic-based leveling agents exhibit excellent compatibility with the coating system, do not affect the adhesion and wear resistance of the resulting coating, and produce a smooth and even coating surface free from defects such as spray marks, pinholes, and orange peel.

[0017] In one possible implementation, the silane coupling agent comprises any one or more of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, and 3-(2-aminoethyl)-aminopropyltrimethoxysilane.

[0018] The silane coupling agents used in this application all contain amino groups, which can undergo hydrogen bonding with the hydroxyl groups of polyvinyl alcohol in the coating, the oxygen-containing groups on the surface of modified nano-graphite powder, and the carbonyl groups in polyvinylpyrrolidone, thereby improving the compatibility of each component and avoiding obvious interface defects in the resulting coating.

[0019] Secondly, this application provides a method for preparing a coating for surface treatment of a vortex disk, which, in one possible implementation, includes the following steps:

[0020] Add nano-graphite powder to nitric acid with a mass concentration of 60-65%, and stir at a rate of 300-500 r / min for 15-30 min to form a mixture;

[0021] The mixture was then heated to 50-70℃, and a hydrogen peroxide solution with a mass concentration of 20-30% was added. The mixture was kept at this temperature for 2-4 hours to obtain the first reaction solution.

[0022] After cooling, deionized water was added to the first reaction solution for dilution, followed by centrifugation at 8000-10000 r / min for 10-20 min, and the first precipitate was collected.

[0023] The first precipitate was washed with deionized water until the pH reached 6.5-7.5, dried under vacuum at 60-80℃ for 8-12 hours, and passed through a 200-mesh sieve to obtain oxidized nano-graphite powder.

[0024] Oxidized nano-graphite powder was added to an ethanol-water mixture and sonicated for 30-60 minutes to obtain a dispersion.

[0025] While stirring, add silane coupling agent dropwise to the dispersion and continue stirring at 500-800 r / min for 2-4 h at 50-60℃ to obtain the second reaction solution;

[0026] The second reaction solution was centrifuged at a rate of 8000-10000 r / min for 15-30 min to obtain the second precipitate;

[0027] The second precipitate was washed 2-3 times with anhydrous ethanol, dried under vacuum at 70-90℃ for 6-10 hours, and passed through a 200-mesh sieve to obtain modified nano-graphite powder.

[0028] Add ethanol to the dispersion vessel, and add the dispersant while stirring at a rate of 200-400 r / min until completely dissolved. Then add modified nano-graphite powder and nano-PTFE particles, and stir at a rate of 400-600 r / min for 30-40 min. Then ultrasonically disperse for 30-60 min to obtain a nano-dispersion.

[0029] The nano-dispersion was heated to 50-60℃, and polyvinyl alcohol and polyvinylpyrrolidone were added sequentially while stirring at a rate of 400-600 r / min. Then the stirring rate was increased to 600-800 r / min and stirring was continued for 1-2 h to obtain the initial coating.

[0030] Then add leveling agent to the initial coating, stir at room temperature and a speed of 300-500 r / min for 20-40 min, and then filter through a 200 mesh filter to obtain the coating for vortex disk surface treatment.

[0031] In this application, the oxidation treatment of nano-graphite powder is sufficient, and the density of oxygen-containing active groups on its surface is increased, providing sufficient reaction sites for subsequent modification of silane coupling agent; the modified nano-graphite powder has excellent dispersibility in the coating system, without agglomeration, which promotes the compatibility of various components in the coating, and ultimately improves the wear resistance, temperature resistance, oil resistance and corrosion resistance of the obtained coating, and has a strong bonding force with the substrate.

[0032] In one possible implementation, during the dilution process of adding deionized water to the first reaction solution, the mass of the added deionized water is 3-5 times the mass of the first reaction solution.

[0033] In one possible implementation, the mass ratio of the nano-graphite powder, nitric acid, and hydrogen peroxide solution is (8-15):(60-70):(20-30); the mass ratio of the oxidized nano-graphite powder, the ethanol-water mixture, and the silane coupling agent is (10-20):(75-85):(1-5); and the volume ratio of ethanol to water in the ethanol-water mixture is (70-80):(20-30).

[0034] Thirdly, this application provides a coating spraying process for surface treatment of a scroll disk, comprising the following steps:

[0035] First, use round silicone strips of equal width and length to cover all surfaces of the vortex disk sealing groove;

[0036] Then, the coating for the surface treatment of the vortex disk is added to the micro-pressure self-flowing spray gun, and with the help of the rotating turntable, the bottom and spiral part of the vortex disk are initially sprayed at 100-140℃.

[0037] Next, place the pre-coated vortex plate into an oven at 140-160℃ and bake for 25-30 minutes.

[0038] Then, the temperature is lowered to 110-130℃, and the initially coated scroll plate is removed from the oven. In the same way, a second coating is carried out at 100-140℃ using a rotating turntable.

[0039] After recoating, the scroll plate is placed in an oven and baked at 280-300℃ for 25-30 minutes. Then, a final coating is applied at 80-100℃ to obtain the surface-treated scroll plate.

[0040] In the spraying process provided in this application, the vortex disk sealing groove is protected by a circular silicone strip in advance, thus preventing contamination by the paint and ensuring the sealing performance of the vortex disk. The micro-pressure self-flowing spray gun, combined with a rotating turntable, ensures that the coating thickness on the surface of the vortex disk is uniform, free from defects such as cracks, bubbles, and pinholes. Furthermore, the spraying temperature, baking temperature, and time are strictly controlled during the initial spraying, re-spraying, and final spraying processes, ensuring that the final coating is fully cured and meets the wear resistance standards. In addition, the step-by-step spraying and gradient temperature baking can alleviate the internal thermal stress of the coating, avoiding coating peeling, cracking, or other defects caused by a single thick coating or a sudden increase in temperature, which would affect the use of the vortex disk.

[0041] In one possible implementation, the initial spray coating has a thickness of 10-20 μm, the second spray coating has a thickness of 3-7 μm, and the surface-treated vortex disk has a coating thickness of 15-30 μm.

[0042] The coating thickness designed in this application meets the wear resistance requirements of the scroll plate, and will not cause excessive internal stress due to excessive thickness; moreover, the coating thickness distribution of each step of the multi-stage spraying is reasonable, avoiding defects such as sagging, bubbles, and cracking caused by a single coating being too thick or too thin.

[0043] In one possible implementation, during the entire spraying process, the air pressure of the micro-pressure self-flowing spray gun is 0.4-0.6 MPa, the gas used in the spray gun is nitrogen, and the gas flow rate is 200-400 mL / min; the rotation speed of the turntable is 300-500 r / min.

[0044] Through optimized design of parameters such as air pressure and gas flow rate, the coating atomization effect is good, the spraying is uniform, and there is no local accumulation or missed spraying. At the same time, the gas used in the spray gun is nitrogen, which can avoid unnecessary oxidation and degradation of the coating during high-temperature spraying and ensure the stability of the coating performance. The adaptation of the turntable speed can further ensure that the bottom of the scroll plate and the spiral part can be sprayed evenly.

[0045] Beneficial technical effects:

[0046] In the coating for surface treatment of vortex disks provided in this application, the presence of hydroxyl groups in the polyvinyl alcohol molecular chain promotes adsorption with the vortex disk substrate, and chemical bonding is generated between the coating and the substrate under the action of baking in the spraying process, ensuring strong adhesion between the coating and the substrate.

[0047] The modified nano-graphite powder is produced by oxidizing nano-graphite powder to introduce oxygen-containing active groups such as hydroxyl (-OH) and carboxyl (-COOH) groups onto its surface, thus obtaining oxidized nano-graphite powder and increasing its reactivity. Furthermore, one end of the silane coupling agent undergoes alkoxy hydrolysis to generate silanol (-Si-OH), which condenses with the oxygen-containing active groups on the surface of the oxidized nano-graphite powder to form chemical bonds, thereby introducing an amino-containing organic group at the other end. This significantly improves the compatibility of the prepared modified nano-graphite powder with components such as polyvinyl alcohol and ethanol. Combined with the use of a dispersant, this solves the problem of easy agglomeration of nano-graphite powder in the coating system of this application. Moreover, the prepared modified nano-graphite powder retains its layered structure with weak interlayer forces, allowing for slippage and further enhancing the wear resistance and self-lubricating properties of the coating. In addition, the addition of nano-PTFE particles gives the coating a lower surface energy, enabling the formation of a lubricating film on the coating surface, thereby further reducing frictional losses during the movement of the vortex disk.

[0048] Furthermore, in the spraying process provided in this application, the vortex disk sealing groove is protected by a circular silicone strip in advance, thus preventing it from being contaminated by the paint and ensuring the sealing performance of the vortex disk. By using a micro-pressure self-flowing spray gun in conjunction with a rotating turntable, the coating thickness sprayed on the surface of the vortex disk is uniform, free from defects such as cracks, bubbles, and pinholes. Moreover, the spraying temperature, baking temperature, and time are strictly controlled during the initial spraying, re-spraying, and final spraying processes, ensuring that the final coating is fully cured and meets the wear resistance standards. In addition, the step-by-step spraying and gradient temperature baking can alleviate the internal thermal stress of the coating and avoid coating peeling, cracking, or other defects caused by a one-time thick coating or a sudden increase in temperature, which would affect the use of the vortex disk. Attached Figure Description

[0049] Figure 1 This is a schematic diagram of the preparation process of the coating for the surface treatment of the vortex disk provided in this application.

[0050] Figure 2 This is a physical image of the coating for surface treatment of a vortex disk provided in Embodiment 3 of this application.

[0051] Figure 3 This is a schematic diagram of the coating process for surface treatment of a scroll plate provided in this application. Detailed Implementation

[0052] To facilitate understanding of the content described in this application, the technical solutions described herein are further explained below with reference to specific embodiments; however, this application is not limited thereto. All equivalent transformations or simple substitutions made based on the substantive content of this application should fall within the protection scope of this application.

[0053] The singular forms “for,” “or,” “a,” “any,” and “the” used in this application are intended to include the plural forms unless the context clearly indicates otherwise.

[0054] The following will describe in detail, with reference to different embodiments, a method for preparing a coating for surface treatment of a vortex disk provided in this application, and the spraying process of the coating for surface treatment of a vortex disk obtained in each embodiment.

[0055] Example 1

[0056] like Figure 1 As shown, a method for preparing a coating for surface treatment of a vortex disk includes the following steps:

[0057] 1. Add nano-graphite powder to 60% nitric acid and stir at 300 r / min for 15 min to form a mixture;

[0058] 2. The mixture was then heated to 50°C, a 20% hydrogen peroxide solution was added, and the mixture was kept at this temperature for 2 hours to obtain the first reaction solution.

[0059] In steps 1-2 above, the mass ratio of nano-graphite powder, nitric acid, and hydrogen peroxide solution is 8:70:22;

[0060] 3. After cooling, add 3 times the mass of deionized water to the first reaction solution for dilution, then centrifuge at 8000 r / min for 10 min and collect the first precipitate;

[0061] 4. Wash the first precipitate with deionized water until the pH reaches 6.5, dry it under vacuum at 60°C for 8 hours, and pass it through a 200-mesh sieve to obtain oxidized nano-graphite powder.

[0062] 5. Add the oxidized nano-graphite powder to an ethanol-water mixture with a volume ratio of 70:30 and sonicate for 30 minutes to obtain a dispersion.

[0063] 6. While stirring, add 3-aminopropyltrimethoxysilane dropwise to the dispersion and continue stirring at 500 r / min for 2 h at 50 °C to obtain the second reaction solution;

[0064] In steps 5-6 above, the mass ratio of oxidized nano-graphite powder, ethanol-water mixture and 3-aminopropyltrimethoxysilane is 10:85:5;

[0065] 7. Centrifuge the second reaction solution at 8000 r / min for 15 min to obtain the second precipitate;

[0066] 8. The second precipitate was washed twice with anhydrous ethanol, dried under vacuum at 70°C for 6 hours, and passed through a 200-mesh sieve to obtain modified nano-graphite powder.

[0067] 9. Add ethanol to the dispersion vessel, and add sodium dodecyl sulfate while stirring at a rate of 200 r / min until completely dissolved. Then add modified nano-graphite powder with an average particle size of 50 nm and nano-PTFE particles with an average particle size of 100 nm. Stir at a rate of 400 r / min for 30 min, and then ultrasonically disperse for 30 min to obtain a nano-dispersion.

[0068] 10. Heat the nano-dispersion to 50°C, and add polyvinyl alcohol and polyvinylpyrrolidone sequentially while stirring at a rate of 400 r / min. Then increase the stirring rate to 600 r / min and continue stirring for 1 h to obtain the initial coating.

[0069] 11. Then add silicone leveling agent BYK-301 to the initial coating, stir for 20 minutes at room temperature and 300 r / min, and then filter through a 200 mesh filter to obtain the coating for vortex disk surface treatment.

[0070] In steps 9-11 above, the mass ratio of polyvinyl alcohol, modified nano-graphite powder, nano-PTFE particles, sodium dodecyl sulfate, polyvinylpyrrolidone, BYK-301 and ethanol is 12:2:3:0.5:0.05:2:80.45.

[0071] like Figure 3 As shown, the spraying process of the coating for the surface treatment of the vortex disk prepared above includes the following steps:

[0072] 1) First, use circular silicone strips of equal width and length to cover all surfaces of the vortex disk sealing groove;

[0073] 2) Then, the coating material for the surface treatment of the vortex disk is added to the micro-pressure self-flowing spray gun, and with the help of the rotating turntable, the bottom and spiral part of the vortex disk are initially sprayed at 100°C. The thickness of the coating formed by the initial spraying is 10μm.

[0074] 3) Next, place the pre-coated vortex plate into an oven at 140℃ and bake for 25 minutes;

[0075] 4) Then cool down to 110℃, take the initially sprayed vortex plate out of the oven, and use a rotating turntable to spray it again at 100℃. The thickness of the coating formed by the second spraying is 3μm.

[0076] 5) Place the re-coated vortex disk into an oven and bake at 280℃ for 25 minutes. Then, perform a final coating at 80℃ to obtain a surface-treated vortex disk with a coating thickness of 15μm.

[0077] Throughout the entire spraying process, the air pressure of the micro-pressure self-flowing spray gun is 0.4 MPa, the gas used in the spray gun is nitrogen, and the gas flow rate is 200 mL / min; the rotation speed of the turntable is 300 r / min.

[0078] Example 2

[0079] like Figure 1 As shown, a method for preparing a coating for surface treatment of a vortex disk includes the following steps:

[0080] 1. Add nano-graphite powder to 65% nitric acid and stir at 500 r / min for 30 min to form a mixture;

[0081] 2. The mixture was then heated to 70°C, a 30% hydrogen peroxide solution was added, and the mixture was kept at this temperature for 4 hours to obtain the first reaction solution.

[0082] In steps 1-2 above, the mass ratio of nano-graphite powder, nitric acid, and hydrogen peroxide solution is 15:60:25;

[0083] 3. After cooling, add 5 times the mass of deionized water to the first reaction solution for dilution, then centrifuge at 10000 r / min for 20 min and collect the first precipitate;

[0084] 4. Wash the first precipitate with deionized water until the pH reaches 7.5, dry it under vacuum at 80°C for 12 hours, and pass it through a 200-mesh sieve to obtain oxidized nano-graphite powder.

[0085] 5. Add the oxidized nano-graphite powder to an ethanol-water mixture with a volume ratio of 80:20 and sonicate for 60 minutes to obtain a dispersion.

[0086] 6. While stirring, add 3-aminopropyltriethoxysilane dropwise to the dispersion, and continue stirring at 800 r / min for 4 h at 60 °C to obtain the second reaction solution;

[0087] In steps 5-6 above, the mass ratio of oxidized nano-graphite powder, ethanol-water mixture and 3-aminopropyltriethoxysilane is 20:76:4;

[0088] 7. Centrifuge the second reaction solution at 10000 r / min for 30 min to obtain the second precipitate;

[0089] 8. The second precipitate was washed three times with anhydrous ethanol, dried under vacuum at 90°C for 10 hours, and passed through a 200-mesh sieve to obtain modified nano-graphite powder.

[0090] 9. Add ethanol to the dispersion vessel, and add sodium dodecylbenzenesulfonate while stirring at a rate of 400 r / min until completely dissolved. Then add modified nano-graphite powder with an average particle size of 100 nm and nano-PTFE particles with an average particle size of 200 nm. Stir at a rate of 600 r / min for 40 min, and then ultrasonically disperse for 60 min to obtain a nano-dispersion.

[0091] 10. Heat the nano-dispersion to 60°C, and add polyvinyl alcohol and polyvinylpyrrolidone sequentially while stirring at a rate of 600 r / min. Then increase the stirring rate to 800 r / min and continue stirring for 2 hours to obtain the initial coating.

[0092] 11. Then add the acrylic leveling agent BYK-350 to the initial coating, stir for 40 minutes at room temperature and a speed of 500 r / min, and then filter through a 200 mesh filter to obtain the coating for the surface treatment of the vortex disk.

[0093] In steps 9-11 above, the mass ratio of polyvinyl alcohol, modified nano-graphite powder, nano-PTFE particles, sodium dodecylbenzenesulfonate, polyvinylpyrrolidone, BYK-350 and ethanol is 16.9:3:4:1:0.1:3:72.

[0094] like Figure 3 As shown, the spraying process of the coating for the surface treatment of the vortex disk prepared above includes the following steps:

[0095] 1) First, use circular silicone strips of equal width and length to cover all surfaces of the vortex disk sealing groove;

[0096] 2) Then, the coating material for the surface treatment of the vortex disk is added to the micro-pressure self-flowing spray gun, and with the help of the rotating turntable, the bottom and spiral part of the vortex disk are initially sprayed at 140°C. The thickness of the coating formed by the initial spraying is 12μm.

[0097] 3) Next, place the pre-coated vortex plate into an oven at 160℃ and bake for 30 minutes;

[0098] 4) Then cool down to 130℃, take the pre-sprayed vortex plate out of the oven, and spray it again at 140℃ using a rotating turntable. The thickness of the coating formed by the second spraying is 5μm.

[0099] 5) Place the re-coated vortex disk into an oven and bake at 300℃ for 30 minutes. Then, perform a final coating at 100℃ to obtain a surface-treated vortex disk with a coating thickness of 20μm.

[0100] Throughout the entire spraying process, the air pressure of the micro-pressure self-flowing spray gun is 0.6 MPa, the gas used in the spray gun is nitrogen, and the gas flow rate is 400 mL / min; the rotation speed of the turntable is 500 r / min.

[0101] Example 3

[0102] like Figure 1 As shown, a method for preparing a coating for surface treatment of a vortex disk includes the following steps:

[0103] 1. Add nano-graphite powder to 62% nitric acid and stir at 400 r / min for 20 min to form a mixture;

[0104] 2. The mixture was then heated to 60°C, a 25% hydrogen peroxide solution was added, and the mixture was kept at this temperature for 3 hours to obtain the first reaction solution.

[0105] In steps 1-2 above, the mass ratio of nano-graphite powder, nitric acid, and hydrogen peroxide solution is 10:65:25;

[0106] 3. After cooling, add 4 times the mass of deionized water to the first reaction solution for dilution, then centrifuge at 9000 r / min for 15 min and collect the first precipitate;

[0107] 4. Wash the first precipitate with deionized water until the pH reaches 7.0, dry it under vacuum at 70°C for 10 hours, and pass it through a 200-mesh sieve to obtain oxidized nano-graphite powder;

[0108] 5. Add the oxidized nano-graphite powder to an ethanol-water mixture with a volume ratio of 75:25 and sonicate for 45 minutes to obtain a dispersion.

[0109] 6. While stirring, add 3-(2-aminoethyl)-aminopropyltrimethoxysilane dropwise to the dispersion, and continue stirring at 55°C and a rate of 650 r / min for 3 h to obtain the second reaction solution;

[0110] In steps 5-6 above, the mass ratio of oxidized nano-graphite powder, ethanol-water mixture and 3-(2-aminoethyl)-aminopropyltrimethoxysilane is 19:80:1;

[0111] 7. Centrifuge the second reaction solution at 9000 r / min for 20 min to obtain the second precipitate;

[0112] 8. The second precipitate was washed twice with anhydrous ethanol, dried under vacuum at 80°C for 8 hours, and passed through a 200-mesh sieve to obtain modified nano-graphite powder.

[0113] 9. Add ethanol to the dispersion vessel, and add sodium tetradecyl sulfate while stirring at a rate of 400 r / min until completely dissolved. Then add modified nano-graphite powder with an average particle size of 80 nm and nano-PTFE particles with an average particle size of 150 nm. Stir at a rate of 500 r / min for 35 min, and then ultrasonically disperse for 45 min to obtain a nano-dispersion.

[0114] 10. Heat the nano-dispersion to 55°C, and add polyvinyl alcohol and polyvinylpyrrolidone sequentially while stirring at a rate of 500 r / min. Then increase the stirring rate to 700 r / min and continue stirring for 1.5 h to obtain the initial coating.

[0115] 11. Then add the silicone leveling agent BYK-326 to the initial coating, stir for 30 minutes at room temperature and a speed of 400 r / min, and then filter through a 200-mesh filter to obtain the coating for vortex disk surface treatment. A sample image is shown below. Figure 2 As shown;

[0116] In steps 9-11 above, the mass ratio of polyvinyl alcohol, modified nano-graphite powder, nano-PTFE particles, sodium tetradecyl sulfate, polyvinylpyrrolidone, BYK-326 and ethanol is 14:2:3:0.7:0.07:2:78.23.

[0117] like Figure 3 As shown, the spraying process of the coating for the surface treatment of the vortex disk prepared above includes the following steps:

[0118] 1) First, use circular silicone strips of equal width and length to cover all surfaces of the vortex disk sealing groove;

[0119] 2) Then, the coating material for the surface treatment of the vortex disk is added to the micro-pressure self-flowing spray gun, and with the help of the rotating turntable, the bottom and spiral part of the vortex disk are initially sprayed at 120°C. The thickness of the coating formed by the initial spraying is 15μm.

[0120] 3) Next, place the pre-coated vortex plate into an oven at 150℃ and bake for 25 minutes;

[0121] 4) Then cool down to 120℃, take the initially sprayed vortex plate out of the oven, and use a rotating turntable to spray it again at 120℃. The thickness of the coating formed by the second spraying is 6μm.

[0122] 5) Place the re-coated vortex disk into an oven and bake at 290℃ for 25 minutes. Then, perform a final coating at 90℃ to obtain a surface-treated vortex disk with a coating thickness of 25μm.

[0123] Throughout the entire spraying process, the air pressure of the micro-pressure self-flowing spray gun is 0.5 MPa, the gas used in the spray gun is nitrogen, and the gas flow rate is 300 mL / min; the rotation speed of the turntable is 400 r / min.

[0124] Example 4

[0125] like Figure 1 As shown, a method for preparing a coating for surface treatment of a vortex disk includes the following steps:

[0126] 1. Add nano-graphite powder to 61% nitric acid and stir at 350 r / min for 25 min to form a mixture;

[0127] 2. The mixture was then heated to 55°C, a 22% hydrogen peroxide solution was added, and the mixture was kept at this temperature for 2.5 hours to obtain the first reaction solution.

[0128] In steps 1-2 above, the mass ratio of nano-graphite powder, nitric acid, and hydrogen peroxide solution is 12:68:20;

[0129] 3. After cooling, add 3.5 times the mass of deionized water to the first reaction solution for dilution, then centrifuge at 8500 r / min for 18 min and collect the first precipitate;

[0130] 4. Wash the first precipitate with deionized water until the pH reaches 6.8, dry it under vacuum at 65°C for 9 hours, and pass it through a 200-mesh sieve to obtain oxidized nano-graphite powder;

[0131] 5. Add the oxidized nano-graphite powder to an ethanol-water mixture with a volume ratio of 72:28 and sonicate for 35 minutes to obtain a dispersion.

[0132] 6. While stirring, add 3-(2-aminoethyl)-aminopropyltrimethoxysilane dropwise to the dispersion, and continue stirring at 550 r / min for 2.5 h at 52 °C to obtain the second reaction solution;

[0133] In steps 5-6 above, the mass ratio of oxidized nano-graphite powder, ethanol-water mixture and 3-(2-aminoethyl)-aminopropyltrimethoxysilane is 12:83:5;

[0134] 7. Centrifuge the second reaction solution at 8500 r / min for 25 min to obtain the second precipitate;

[0135] 8. The second precipitate was washed three times with anhydrous ethanol, dried under vacuum at 75°C for 7 hours, and passed through a 200-mesh sieve to obtain modified nano-graphite powder.

[0136] 9. Add ethanol to the dispersion vessel, and add sodium octadecylbenzenesulfonate while stirring at a rate of 400 r / min until completely dissolved. Then add modified nano-graphite powder with an average particle size of 60 nm and nano-PTFE particles with an average particle size of 200 nm. Stir at a rate of 450 r / min for 32 min, and then ultrasonically disperse for 40 min to obtain a nano-dispersion.

[0137] 10. Heat the nano-dispersion to 58°C, and add polyvinyl alcohol and polyvinylpyrrolidone sequentially while stirring at a rate of 450 r / min. Then increase the stirring rate to 650 r / min and continue stirring for 2 hours to obtain the initial coating.

[0138] 11. Then add the acrylic leveling agent BYK-354 to the initial coating, stir for 25 minutes at room temperature and a speed of 350 r / min, and then filter through a 200 mesh filter to obtain the coating for the surface treatment of the vortex disk.

[0139] In steps 9-11 above, the mass ratio of polyvinyl alcohol, modified nano-graphite powder, nano-PTFE particles, sodium octadecylbenzenesulfonate, polyvinylpyrrolidone, BYK-354 and ethanol is 18:1:2:0.3:0.03:1:77.67.

[0140] like Figure 3 As shown, the spraying process of the coating for the surface treatment of the vortex disk prepared above includes the following steps:

[0141] 1) First, use circular silicone strips of equal width and length to cover all surfaces of the vortex disk sealing groove;

[0142] 2) Then, the coating material for the surface treatment of the vortex disk is added to the micro-pressure self-flowing spray gun, and with the help of the rotating turntable, the bottom and spiral part of the vortex disk are initially sprayed at 110°C. The thickness of the coating formed by the initial spraying is 20μm.

[0143] 3) Next, place the pre-coated vortex plate into an oven at 145℃ and bake for 24 minutes;

[0144] 4) Then cool down to 115℃, take the initially sprayed vortex plate out of the oven, and spray it again at 110℃ using the same rotating turntable. The thickness of the coating formed by the second spraying is 7μm.

[0145] 5) Place the re-coated vortex disk into an oven and bake at 285℃ for 28 minutes. Then perform a final coating at 85℃ to obtain the surface-treated vortex disk. The coating thickness of the surface-treated vortex disk is 30μm.

[0146] Throughout the entire spraying process, the air pressure of the micro-pressure self-flowing spray gun is 0.6 MPa, the gas used in the spray gun is nitrogen, and the gas flow rate is 350 mL / min; the rotation speed of the turntable is 450 r / min.

[0147] Example 5

[0148] like Figure 1 As shown, a method for preparing a coating for surface treatment of a vortex disk includes the following steps:

[0149] 1. Add nano-graphite powder to 64% nitric acid and stir at 450 r / min for 18 min to form a mixture;

[0150] 2. The mixture was then heated to 65°C, a 28% hydrogen peroxide solution was added, and the mixture was kept at this temperature for 3.5 hours to obtain the first reaction solution.

[0151] In steps 1-2 above, the mass ratio of nano-graphite powder, nitric acid, and hydrogen peroxide solution is 14:62:24;

[0152] 3. After cooling, add 4.5 times the mass of deionized water to the first reaction solution for dilution, then centrifuge at 9500 r / min for 15 min and collect the first precipitate;

[0153] 4. Wash the first precipitate with deionized water until the pH reaches 7.2, dry it under vacuum at 75°C for 11 hours, and pass it through a 200-mesh sieve to obtain oxidized nano-graphite powder.

[0154] 5. Add the oxidized nano-graphite powder to an ethanol-water mixture with a volume ratio of 78:22 and sonicate for 50 minutes to obtain a dispersion.

[0155] 6. While stirring, add 3-aminopropyltrimethoxysilane dropwise to the dispersion, and continue stirring at 750 r / min for 3.5 h at 58 °C to obtain the second reaction solution;

[0156] In steps 5-6 above, the mass ratio of oxidized nano-graphite powder, ethanol-water mixture and 3-aminopropyltrimethoxysilane is 20:75:5;

[0157] 7. Centrifuge the second reaction solution at 9500 r / min for 28 min to obtain the second precipitate;

[0158] 8. The second precipitate was washed twice with anhydrous ethanol, dried under vacuum at 85°C for 9 hours, and passed through a 200-mesh sieve to obtain modified nano-graphite powder.

[0159] 9. Add ethanol to the dispersion vessel, and add sodium dodecyl sulfate while stirring at a rate of 350 r / min until completely dissolved. Then add modified nano-graphite powder with an average particle size of 100 nm and nano-PTFE particles with an average particle size of 180 nm. Stir at a rate of 550 r / min for 38 min, and then ultrasonically disperse for 55 min to obtain a nano-dispersion.

[0160] 10. Heat the nano-dispersion to 55°C, and add polyvinyl alcohol and polyvinylpyrrolidone sequentially while stirring at a rate of 550 r / min. Then increase the stirring rate to 750 r / min and continue stirring for 1.5 h to obtain the initial coating.

[0161] 11. Then add silicone leveling agent BYK-337 to the initial coating, stir for 35 minutes at room temperature and 450 r / min, and then filter through a 200 mesh filter to obtain the coating for vortex disk surface treatment.

[0162] In steps 9-11 above, the mass ratio of polyvinyl alcohol, modified nano-graphite powder, nano-PTFE particles, sodium dodecyl sulfate, polyvinylpyrrolidone, BYK-337 and ethanol is 12.45:1:2:0.5:0.05:2:82.

[0163] like Figure 3 As shown, the spraying process of the coating for surface treatment of the vortex disk prepared above includes the following steps:

[0164] 1) First, use circular silicone strips of equal width and length to cover all surfaces of the vortex disk sealing groove;

[0165] 2) Then, the coating material for the surface treatment of the vortex disk is added to the micro-pressure self-flowing spray gun, and with the help of the rotating turntable, the bottom and spiral part of the vortex disk are initially sprayed at 130°C. The thickness of the coating formed by the initial spraying is 16μm.

[0166] 3) Next, place the pre-coated vortex plate into an oven at 155℃ and bake for 22 minutes;

[0167] 4) Then cool down to 125℃, take the initially sprayed vortex plate out of the oven, and use a rotating turntable to spray it again at 130℃. The thickness of the coating formed by the second spraying is 6μm.

[0168] 5) Place the re-coated vortex disk into an oven and bake at 290℃ for 25 minutes. Then, perform a final coating at 95℃ to obtain the surface-treated vortex disk. The coating thickness of the surface-treated vortex disk is 27μm.

[0169] Throughout the entire spraying process, the air pressure of the micro-pressure self-flowing spray gun is 0.4 MPa, the gas used in the spray gun is nitrogen, and the gas flow rate is 400 mL / min; the rotation speed of the turntable is 350 r / min.

[0170] Example 6

[0171] like Figure 1 As shown, a method for preparing a coating for surface treatment of a vortex disk includes the following steps:

[0172] 1. Add nano-graphite powder to 63% nitric acid and stir at 420 r / min for 20 min to form a mixture;

[0173] 2. The mixture was then heated to 60°C, a 25% hydrogen peroxide solution was added, and the mixture was kept at this temperature for 3 hours to obtain the first reaction solution.

[0174] In steps 1-2 above, the mass ratio of nano-graphite powder, nitric acid, and hydrogen peroxide solution is 10:60:30;

[0175] 3. After cooling, add 4 times the mass of deionized water to the first reaction solution for dilution, then centrifuge at 9000 r / min for 16 min and collect the first precipitate;

[0176] 4. Wash the first precipitate with deionized water until the pH reaches 7.0, dry it under vacuum at 70°C for 10 hours, and pass it through a 200-mesh sieve to obtain oxidized nano-graphite powder;

[0177] 5. Add the oxidized nano-graphite powder to an ethanol-water mixture with a volume ratio of 74:26 and sonicate for 40 minutes to obtain a dispersion.

[0178] 6. While stirring, add 3-aminopropyltriethoxysilane dropwise to the dispersion, and continue stirring at 700 r / min for 3 h at 55 °C to obtain the second reaction solution;

[0179] In steps 5-6 above, the mass ratio of oxidized nano-graphite powder, ethanol-water mixture and 3-aminopropyltriethoxysilane is 15:82:3;

[0180] 7. Centrifuge the second reaction solution at a rate of 9000 r / min for 22 min to obtain the second precipitate;

[0181] 8. The second precipitate was washed three times with anhydrous ethanol, dried under vacuum at 80°C for 8.5 hours, and passed through a 200-mesh sieve to obtain modified nano-graphite powder.

[0182] 9. Add ethanol to the dispersion vessel, and add sodium dodecylbenzenesulfonate while stirring at a rate of 300 r / min until completely dissolved. Then add modified nano-graphite powder with an average particle size of 50 nm and nano-PTFE particles with an average particle size of 150 nm. Stir at a rate of 500 r / min for 40 min, and then ultrasonically disperse for 50 min to obtain a nano-dispersion.

[0183] 10. Heat the nano-dispersion to 56°C, and add polyvinyl alcohol and polyvinylpyrrolidone sequentially while stirring at a rate of 500 r / min. Then increase the stirring rate to 700 r / min and continue stirring for 2 hours to obtain the initial coating.

[0184] 11. Then add the acrylic leveling agent BYK-361N to the initial coating, stir for 30 minutes at room temperature and a speed of 400 r / min, and then filter through a 200 mesh filter to obtain the coating for the surface treatment of the vortex disk.

[0185] In steps 9-11 above, the mass ratio of polyvinyl alcohol, modified nano-graphite powder, nano-PTFE particles, sodium dodecyl sulfate, polyvinylpyrrolidone, BYK-361N and ethanol is 15:2.2:3.2:0.6:0.06:1.8:77.14.

[0186] like Figure 3 As shown, the spraying process of the coating for surface treatment of the vortex disk prepared above includes the following steps:

[0187] 1) First, use circular silicone strips of equal width and length to cover all surfaces of the vortex disk sealing groove;

[0188] 2) Then, the coating material for the surface treatment of the vortex disk is added to the micro-pressure self-flowing spray gun, and with the help of the rotating turntable, the bottom and spiral part of the vortex disk are initially sprayed at 125°C. The thickness of the coating formed by the initial spraying is 14μm.

[0189] 3) Next, place the pre-coated vortex plate into an oven at 150℃ and bake for 27 minutes;

[0190] 4) Then cool down to 120℃, take the initially sprayed vortex plate out of the oven, and use a rotating turntable to spray it again at 125℃. The thickness of the coating formed by the second spraying is 4μm.

[0191] 5) Place the re-coated vortex disk into an oven and bake at 295℃ for 24 minutes. Then perform a final coating at 90℃ to obtain the surface-treated vortex disk. The coating thickness of the surface-treated vortex disk is 23μm.

[0192] During the entire spraying process, the air pressure of the micro-pressure self-flowing spray gun is 0.4 MPa, the gas used in the spray gun is nitrogen, and the gas flow rate is 300 mL / min; the rotation speed of the turntable is 500 r / min.

[0193] Comparative Example 1

[0194] This comparative example provides a method for preparing a coating for surface treatment of a vortex disk and its spraying process. The difference from Example 1 is that the nano-graphite powder is not modified in this comparative example, but the other process parameters and operating steps are exactly the same as in Example 1.

[0195] Comparative Example 2

[0196] This comparative example provides a method for preparing a coating for the surface treatment of a scroll plate and its spraying process. The difference between this comparative example and Example 3 is that the coating for the surface treatment of a scroll plate prepared in this comparative example is not sprayed in stages using a micro-pressure self-flowing spray gun in conjunction with a rotating turntable. Other process parameters and operating steps are exactly the same as in Example 3.

[0197] Comparative Example 3

[0198] This comparative example provides a method for preparing a coating for surface treatment of a vortex disk and its spraying process. The difference between this comparative example and Example 6 is that the nano-graphite powder is not modified, and the coating is not sprayed in stages using a micro-pressure self-flowing spray gun in conjunction with a rotating turntable. Other process parameters and operating steps are exactly the same as in Example 6.

[0199] The adhesion, salt spray resistance, and abrasion resistance of the coatings on the surface of the vortex disks after spraying in each embodiment and comparative example were tested, and the test results are shown in Table 1.

[0200] Table 1. Test results of coatings prepared in the examples and comparative examples.

[0201]

[0202] As shown in Table 1, the coatings prepared in Examples 1-6 are generally superior to those in Comparative Examples 1-3.

[0203] The main reason is that in the coating for surface treatment of vortex disks provided in this application, the presence of hydroxyl groups in the polyvinyl alcohol molecular chain promotes adsorption with the vortex disk substrate, and under the action of baking in the spraying process, chemical bonds are generated between the coating and the substrate, ensuring strong adhesion between the coating and the substrate.

[0204] The modified nano-graphite powder is produced by oxidizing nano-graphite powder to introduce oxygen-containing active groups such as hydroxyl (-OH) and carboxyl (-COOH) groups onto its surface, thus obtaining oxidized nano-graphite powder and increasing its reactivity. Furthermore, one end of the silane coupling agent undergoes alkoxy hydrolysis to generate silanol (-Si-OH), which condenses with the oxygen-containing active groups on the surface of the oxidized nano-graphite powder to form chemical bonds, thereby introducing an amino-containing organic group at the other end. This significantly improves the compatibility of the prepared modified nano-graphite powder with components such as polyvinyl alcohol and ethanol. Combined with the use of a dispersant, this solves the problem of easy agglomeration of nano-graphite powder in the coating system of this application. Moreover, the prepared modified nano-graphite powder retains its layered structure with weak interlayer forces, allowing for slippage and further enhancing the wear resistance and self-lubricating properties of the coating. In addition, the addition of nano-PTFE particles gives the coating a lower surface energy, enabling the formation of a lubricating film on the coating surface, thereby further reducing frictional losses during the movement of the vortex disk.

[0205] Furthermore, in the spraying process provided in this application, the vortex disk sealing groove is protected by a circular silicone strip in advance, thus preventing it from being contaminated by the paint and ensuring the sealing performance of the vortex disk. By using a micro-pressure self-flowing spray gun in conjunction with a rotating turntable, the coating thickness sprayed on the surface of the vortex disk is uniform, free from defects such as cracks, bubbles, and pinholes. Moreover, the spraying temperature, baking temperature, and time are strictly controlled during the initial spraying, re-spraying, and final spraying processes, ensuring that the final coating is fully cured and meets the wear resistance standards. In addition, the step-by-step spraying and gradient temperature baking can alleviate the internal thermal stress of the coating and avoid coating peeling, cracking, or other defects caused by a one-time thick coating or a sudden increase in temperature, which would affect the use of the vortex disk.

[0206] In contrast, Comparative Example 1 did not modify the nano-graphite powder, thus failing to improve its compatibility with components such as polyvinyl alcohol and ethanol; consequently, it could not be used in conjunction with a dispersant to address the issue of easy agglomeration in the coating system of this application. Therefore, the adhesion, salt spray resistance, and abrasion resistance of the coating on the sprayed vortex disk surface were inferior to those of Example 1.

[0207] Although the nano-graphite powder was modified in Comparative Example 2, the coating was not sprayed in stages using a micro-pressure self-flowing spray gun and a rotating turntable. As a result, the coating thickness was uneven. Furthermore, the lack of staged spraying led to insufficient curing of the coating and difficulty in alleviating internal thermal stress, which easily resulted in defects. Ultimately, the adhesion, salt spray resistance, and abrasion resistance of the coating on the vortex disk surface were inferior to those of Example 3, but overall better than Comparative Example 1.

[0208] In Comparative Example 3, neither the nano-graphite powder was modified nor was the coating applied in stages using a micro-pressure self-flowing spray gun in conjunction with a rotating turntable. For the same reasons as Comparative Examples 1 and 2, the adhesion, salt spray resistance, and abrasion resistance of the final coated vortex disk surface were inferior to those of Example 6, and also inferior to those of Comparative Examples 1 and 2.

[0209] The above results demonstrate and describe the basic principles and main features of this application, as well as its advantages.

[0210] Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this application. Various changes and modifications can be made to this application without departing from the spirit and scope thereof, and all such changes and modifications fall within the scope of this application as claimed. The scope of protection of this application is defined by the equivalents of the appended claims.

Claims

1. A coating for surface treatment of a scroll disk, characterized in that, The coating comprises polyvinyl alcohol, modified nano-graphite powder, nano-PTFE particles, dispersant, polyvinylpyrrolidone, leveling agent, and ethanol; the modified nano-graphite powder is obtained by oxidizing nano-graphite powder and then modifying it with a silane coupling agent; the mass ratio of polyvinyl alcohol, modified nano-graphite powder, nano-PTFE particles, dispersant, polyvinylpyrrolidone, leveling agent, and ethanol is (12-18):(1-3):(2-4):(0.3-1):(0.03-0.1):(1-3):(72-82); The coating spraying process includes the following steps: First, use round silicone strips of equal width and length to cover all surfaces of the vortex disk sealing groove; Then, the coating for the surface treatment of the vortex disk is added to the micro-pressure self-flowing spray gun, and with the help of the rotating turntable, the bottom and spiral part of the vortex disk are initially sprayed at 100-140℃. Next, place the pre-coated vortex plate into an oven at 140-160℃ and bake for 25-30 minutes. Then, the temperature is lowered to 110-130℃, and the initially coated scroll plate is removed from the oven. In the same way, a second coating is carried out at 100-140℃ using a rotating turntable. After recoating, the scroll plate is placed in an oven and baked at 280-300℃ for 25-30 minutes. Then, a final coating is applied at 80-100℃ to obtain the surface-treated scroll plate.

2. The coating for surface treatment of a scroll disk according to claim 1, characterized in that, The dispersant includes any one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium tetradecyl sulfate, and sodium octadecylbenzene sulfonate.

3. The coating for surface treatment of a scroll disk according to claim 1, characterized in that, The leveling agent includes any one of silicone-based leveling agents and acrylate-based leveling agents.

4. The coating for surface treatment of a scroll disk according to claim 1, characterized in that, The silane coupling agent includes any one or more of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, and 3-(2-aminoethyl)-aminopropyltrimethoxysilane.

5. The coating for surface treatment of a scroll disk according to claim 1, characterized in that, The initial spray coating has a thickness of 10-20 μm, the second spray coating has a thickness of 3-7 μm, and the coating thickness of the surface-treated vortex disk is 15-30 μm.

6. The coating for surface treatment of a scroll disk according to claim 1, characterized in that, Throughout the spraying process, the air pressure of the micro-pressure self-flowing spray gun is 0.4-0.6 MPa, the gas used is nitrogen, and the gas flow rate is 200-400 mL / min; the rotation speed of the turntable is 300-500 r / min.

7. A method for preparing a coating for surface treatment of a vortex disk according to any one of claims 1-6, characterized in that, include: Nano-graphite powder is added to nitric acid and stirred to form a mixture; The mixture was then heated, hydrogen peroxide solution was added, and the reaction was maintained at this temperature to obtain the first reaction solution. After cooling, deionized water was added to the first reaction solution for dilution, followed by centrifugation to collect the first precipitate; The first precipitate was washed with deionized water, dried under vacuum, and sieved to obtain oxidized nano-graphite powder. Oxidized nano-graphite powder was added to an ethanol-water mixture and then ultrasonicated to obtain a dispersion. While stirring, silane coupling agent was added dropwise to the dispersion, and stirring was continued to obtain a second reaction solution; The second reaction solution was centrifuged to obtain the second precipitate; The second precipitate was washed with anhydrous ethanol, dried under vacuum, and sieved to obtain modified nano-graphite powder. Ethanol was added to the dispersion vessel, and the dispersant was added while stirring until completely dissolved. Then, modified nano-graphite powder and nano-PTFE particles were added, stirred, and then ultrasonically dispersed to obtain a nano-dispersion. The nano-dispersion was heated, and polyvinyl alcohol and polyvinylpyrrolidone were added sequentially while stirring. The stirring rate was then increased and stirring was continued to obtain the initial coating. Then, a leveling agent is added to the initial coating, stirred, and filtered to obtain a coating for the surface treatment of the vortex disk.

8. A method for preparing a coating for surface treatment of a scroll disk according to claim 7, characterized in that, The mass ratio of the nano-graphite powder, nitric acid, and hydrogen peroxide solution is (8-15):(60-70):(20-30); the mass ratio of the oxidized nano-graphite powder, ethanol-water mixture, and silane coupling agent is (10-20):(75-85):(1-5); and the volume ratio of ethanol to water in the ethanol-water mixture is (70-80):(20-30).

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