A wind tunnel flow passage inner wall painting method based on a ship coating film process

Abstract

A kind of wind tunnel flow passage inner wall painting method based on ship coating process, its steps are: step 1, substrate pretreatment;Step 2, primer coating;Step 3, intermediate coating;Step 4, putty leveling;Step 5, topcoat coating;Step 6, post-processing and quality detection;The present application follows the core process of ship coating process and mature epoxy coating system, without developing new coating material and construction technology, the procurement cost, construction cost is reduced by 30%-50% compared with special wind tunnel coating;And construction personnel can rely on the mature experience of ship coating to carry out operation, reduce construction difficulty and training cost, shorten construction period.Performance adaptation, meet the demand of wind tunnel;Maintenance is convenient, long service life, and strong universality, adapt to a variety of substrates.

Description

Technical Field

[0001] This invention relates to the field of wind tunnel duct maintenance and coating technology, and in particular to a method for coating the inner wall of a wind tunnel duct based on ship coating technology. Background Technology

[0002] Wind tunnels are core equipment for aerodynamic performance testing in fields such as aerospace and automotive engineering. The surface quality of the inner wall of the wind tunnel directly affects airflow stability, testing accuracy, and equipment lifespan. The inner wall of the wind tunnel is constantly subjected to high-speed airflow, temperature variations, and humid condensation. Therefore, the coating must possess high adhesion, high abrasion resistance, high gloss, low volatility, and corrosion resistance. Furthermore, the surface must be extremely smooth and uniform, free of protrusions, pinholes, and drips, to avoid disturbing the flow field and causing testing errors.

[0003] Currently, the coating of the inner wall of wind tunnel flow channels mostly adopts special aerospace-grade coatings or customized industrial coatings. Although such coatings can meet the requirements, they have problems such as high cost, long procurement cycle, complex construction process and high maintenance difficulty, making them unsuitable for large-scale application scenarios such as medium and low speed wind tunnels and industrial wind tunnels.

[0004] Marine coating technology, through long-term engineering practice, has formed a mature complete process system of "surface pretreatment - primer - intermediate coat - topcoat". The core epoxy coating has advantages such as high adhesion, water and moisture resistance, fluid erosion resistance, and corrosion resistance, which highly overlaps with the core requirements of wind tunnel flow channel inner wall coating. However, the original design intention of marine coating technology is to meet the anti-corrosion and anti-fouling requirements of ship outer plates. Directly applying it to the inner wall of wind tunnel flow channels will result in problems such as substandard surface roughness, coating volatiles polluting the airflow, and surface defects affecting the flow field, making it unsuitable for the special requirements of wind tunnel flow channels.

[0005] Therefore, how to optimize mature and low-cost ship coating processes to meet the requirements of wind tunnel flow channel inner wall coating, and provide a cost-effective, mature, and performance-compliant wind tunnel flow channel inner wall coating method, has become an urgent technical problem to be solved in this field. Summary of the Invention

[0006] This invention addresses the technical shortcomings of existing wind tunnel flow channel inner wall coating methods, such as high cost, complex processes, and the inability of ship coating processes to directly adapt to the requirements of wind tunnel flow channels. Instead, it provides a wind tunnel flow channel inner wall coating method based on ship coating processes. By specifically optimizing ship coating processes, it retains the advantages of maturity, low cost, and high reliability, while meeting the special requirements of wind tunnel flow channel inner walls for high gloss, low volatility, wear resistance, and erosion resistance, thus achieving efficient coating and long-term stable use of wind tunnel flow channel inner walls.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A method for coating the inner wall of a wind tunnel flow channel based on ship coating technology, comprising the following steps:

[0009] Step 1. Substrate pretreatment: Select appropriate pretreatment methods for the substrates of the inner wall of the wind tunnel flow channel. Steel substrates are sandblasted to Sa2.5 grade, and concrete substrates are mechanically ground until there is no sand and the flatness error is ≤2mm / m. Both are degreasing and dust removal treatment. The construction environment temperature is controlled at 5~35℃ and the relative humidity is ≤85%. The surface temperature of the substrate is more than 3℃ higher than the ambient dew point.

[0010] Step 2. Primer coating: Select marine-grade epoxy zinc-rich primer, apply using airless spraying process, use cross-spraying method, cure at room temperature, cure time ≥24h, after curing, the dry film thickness of the primer is controlled at 60~80μm, and is measured using a dry film thickness gauge.

[0011] Step 3. Intermediate paint application: Select marine-grade epoxy thick-film intermediate paint or epoxy micaceous iron oxide intermediate paint, and apply using an airless spraying process. After each coat, perform preliminary sanding, cure at room temperature, and cure for ≥24 hours. The dry film thickness after curing is 120-150 μm.

[0012] Step 4. Putty leveling: After the intermediate paint has cured to the required standard, apply epoxy putty evenly to the surface in two coats. After the putty has cured, sand it with 800-1000 grit sandpaper until the surface roughness Ra≤6.3μm.

[0013] Step 5. Topcoat application: Select a high-solids smooth epoxy topcoat for wind tunnel use. After the putty is sanded to the required standard, apply 2-3 coats using an airless spraying process. The interval between each coat should be ≥8 hours. After curing, the dry film thickness of the topcoat should be controlled at 80-100μm.

[0014] Step 6. Post-treatment and quality inspection: After the topcoat is fully cured, wipe the inner wall surface of the flow channel with a clean, dry cloth to remove surface dust. For minor defects that appear locally, use topcoat to repair them locally and finely polish them. Inspect the surface quality, film thickness, adhesion, volatiles and erosion resistance to ensure that they meet the standards.

[0015] The specific steps of substrate pretreatment in step 1 are as follows:

[0016] 1.1. Substrate cleaning: For the substrate of the inner wall of the wind tunnel flow channel, first remove the floating dust, oil stains, rust layer, old coating and debris from the surface. For steel substrates, sandblasting is used and for concrete substrates, mechanical grinding is used.

[0017] 1.2. Rust removal / grinding grade control: Steel substrates are sandblasted to Sa2.5 grade, with no visible rust, scale and debris on the surface, revealing a uniform metallic luster; Concrete substrates are ground until the surface is free of sand and loose particles, with a flatness error ≤2mm / m;

[0018] 1.3. Surface cleaning: Wipe the substrate surface with a non-volatile cleaning agent specifically for marine coating to remove residual oil stains; then blow it with clean compressed air to remove surface dust;

[0019] 1.4. Environmental and Surface Condition Control: The ambient temperature during construction shall be controlled between 5 and 35°C, the relative humidity shall be ≤85%, and the surface temperature of the substrate shall be more than 3°C above the ambient dew point.

[0020] The specific steps for applying the primer in step 2 are as follows:

[0021] 2.1. Primer selection: Select a two-component epoxy zinc-rich primer for marine applications, with specifications consistent with the primer for the ship's outer plating;

[0022] 2.2. Primer preparation: Mix the main agent and hardener according to the specified ratio of the primer, stir thoroughly, let stand for 10-20 minutes to mature, and use within the activation period. The amount of thinner added should be ≤5%.

[0023] 2.3. Coating application: Airless spraying process is adopted, with spraying pressure controlled at 18-22MPa, gun distance at 30-50cm, and gun speed at a uniform speed of 20-30cm / s. Cross-spraying method is used. For the inner wall corners, welds, and joints of the flow channel, a pre-coat is applied by brushing before the overall spraying is carried out to ensure no missed areas.

[0024] 2.4. Primer curing: Curing at room temperature for ≥24 hours. After curing, the dry film thickness of the primer should be controlled between 60 and 80 μm. A dry film thickness gauge should be used to check the thickness, ensuring that the dry film thickness at more than 85% of the measuring points meets the standard, and the dry film thickness at the remaining measuring points is not less than 85% of the specified value.

[0025] The specific steps for applying the intermediate paint in step 3 are as follows:

[0026] 3.1. Selection of intermediate paint: Select two-component epoxy thick-film intermediate paint or epoxy micaceous iron oxide intermediate paint for marine applications, with specifications consistent with those of marine intermediate paint.

[0027] 3.2. Intermediate paint preparation: Mix the main agent and hardener according to the specified ratio, stir evenly, add non-volatile thinner (≤3%), adjust the viscosity, and use within the activation period;

[0028] 3.3. Coating Application: After the primer has cured to the required standard, airless spraying process is used for application, with the same application parameters as the primer. For concrete substrates or steel substrates with uneven surfaces, 1-2 intermediate coats are added. After each coat, preliminary sanding is performed to ensure that the coating surface is smooth and free of obvious protrusions.

[0029] 3.4. Intermediate Coating Curing: Curing at room temperature for ≥24 hours. After curing, the dry film thickness of the intermediate coating should be controlled at 120-150 μm, and the total dry film thickness should be controlled at 180-230 μm. The testing standards are the same as those for the primer.

[0030] The specific steps for leveling with putty in step 4 are as follows:

[0031] 4.1. Putty selection: Use two-component epoxy putty;

[0032] 4.2. Putty application: After the intermediate paint has cured to the required standard, apply epoxy putty evenly to the surface. The thickness of the putty should be adjusted according to the flatness of the steel or concrete substrate, with a total thickness not exceeding 0.6mm. Apply in two coats, each coat being 0.2 to 0.3mm thick, with an interval of 8 to 12 hours between coats. Ensure that the surface is free of depressions and pores after application.

[0033] 4.3. Putty Sanding: After the putty has cured, dry sand it with 800-1000 grit fine sandpaper until the surface is smooth and flat, without scratches or bumps, and the surface roughness Ra≤6.3μm. For high-precision wind tunnel channels, sand it to Ra≤3.2μm.

[0034] The specific steps for topcoat application in step 5 are as follows:

[0035] 5.1. Topcoat selection: Select a high-solids, smooth epoxy topcoat specifically designed for wind tunnels;

[0036] 5.2. Topcoat preparation: Mix the main agent and hardener according to the specified ratio, stir evenly, add ≤2% non-volatile thinner to ensure the topcoat concentration, improve the surface gloss, and use within the activation period;

[0037] 5.3. Coating application: After the putty is sanded to the required standard, airless spraying process is used for application. The spraying pressure is controlled at 20-25MPa, the gun distance is 35-45cm, the gun speed is uniform, and cross-spraying is used. 2-3 thin coats are applied, and the interval between each coat is ≥8h to avoid defects such as sagging and orange peel.

[0038] 5.4. Topcoat curing: Curing at room temperature, with a total curing time of ≥48h. After curing, the dry film thickness of the topcoat is controlled at 80~100μm. The total dry film thickness of the entire coating is: 300~350μm for steel channels and 280~330μm for concrete channels.

[0039] The beneficial effects of this invention are: This invention utilizes the core process of ship painting and a mature epoxy coating system, eliminating the need to develop new coating materials and construction techniques. Procurement and construction costs are reduced by 30%–50% compared to dedicated wind tunnel coatings. Furthermore, construction personnel can leverage their mature experience in ship painting to reduce construction difficulty and training costs, and shorten the construction cycle. Performance adaptability meets wind tunnel requirements: Through targeted optimization, it eliminates the contaminating and low-gloss antifouling paints and ordinary polyurethane topcoats used in ship painting. It adds a fine leveling and sanding process using putty, improving the surface smoothness of the coating and controlling the volatile content. This results in a coating with high adhesion, high wear resistance, erosion resistance, corrosion resistance, and low volatility, fully meeting the requirements for the inner wall of wind tunnel flow channels. It is adaptable to medium- and low-speed wind tunnels, industrial wind tunnels, and can even be further optimized for high-precision, high-speed wind tunnels. Maintenance is convenient and service life is long: The adopted... The epoxy coating system exhibits strong stability, moisture resistance, and aging resistance, with a smooth and easy-to-clean surface. During subsequent maintenance, only localized repairs are needed on damaged areas using the coating process of this invention, eliminating the need for a complete recoating process. This extends the service life of the wind tunnel's inner wall and reduces maintenance costs. It also boasts strong versatility and adaptability to various substrates: This invention optimizes pretreatment and coating details for two common wind tunnel substrates—steel and concrete—making it widely applicable to the coating of various wind tunnel inner walls. Its versatility and wide applicability meet the needs of mainstream steel materials in environmental wind tunnels. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the structure of the present invention;

[0041] Figure 2 This is a process flow diagram of the present invention;

[0042] Figure 3 This is a partial schematic diagram showing the putty leveling and topcoat application details of the present invention;

[0043] In the diagram: 1-Substrate; 2-Primer; 3-Intermediate coat; 4-Putty; 5-Topcoat;

[0044] The following will describe in detail, with reference to the accompanying drawings, embodiments of the invention. Detailed Implementation

[0045] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0046] A method for coating the inner wall of a wind tunnel flow channel based on ship coating technology, comprising the following steps:

[0047] Step 1. Substrate Pretreatment: For the inner wall substrate 1 of the wind tunnel flow channel, select an appropriate pretreatment method. Steel substrate 1 is sandblasted to Sa2.5 grade, and concrete substrate 1 is mechanically ground until no sand is visible and the flatness error is ≤2mm / m. Both substrates undergo degreasing and dust removal treatment. The ambient temperature is controlled at 5~35℃, and the relative humidity is ≤85%. The surface temperature of substrate 1 is at least 3℃ higher than the ambient dew point. Specific steps are as follows:

[0048] 1.1. Substrate cleaning: For the substrate 1 of the inner wall of the wind tunnel flow channel, first remove the floating dust, oil stains, rust layer, old coating and debris from the surface. Among them, the steel substrate 1 is sandblasted and the concrete substrate 1 is mechanically ground.

[0049] 1.2. Rust removal / grinding grade control: Steel substrate 1 is sandblasted to Sa2.5 grade, with no visible rust, scale and debris on the surface, revealing a uniform metallic luster; Concrete substrate 1 is ground until the surface is free of sand and loose particles, and the flatness error is ≤2mm / m;

[0050] 1.3. Surface cleaning: Wipe the surface of substrate 1 with a non-volatile cleaning agent specifically for marine coating to remove residual oil stains; then blow it with clean compressed air to remove surface dust, ensuring that the surface of substrate 1 is free of oil stains, dust, and impurities;

[0051] 1.4. Environmental and Surface Condition Control: The ambient temperature during construction shall be controlled between 5 and 35°C, and the relative humidity shall be ≤85%. The surface temperature of substrate 1 shall be more than 3°C above the ambient dew point to avoid condensation and rust formation on the surface of substrate 1 or to avoid affecting the adhesion of the coating. This control standard follows the requirements for marine coating environment.

[0052] Step 2. Primer Coating: Marine-grade epoxy zinc-rich primer 2 is selected and applied using an airless spraying process with a cross-spraying method. It is cured at room temperature for ≥24 hours. After curing, the dry film thickness of primer 2 is controlled at 60–80 μm and measured using a dry film thickness gauge. Specific steps are as follows:

[0053] 2.1. Primer selection: Marine two-component epoxy zinc-rich primer 2 is selected. This primer has high adhesion, corrosion resistance and erosion resistance. It is consistent with the specifications of marine outer plating primer 2. Lead-containing primers for marine ballast tanks are abandoned to avoid volatile pollution.

[0054] 2.2. Primer preparation: Mix the main agent and hardener according to the ratio specified in Primer 2, stir thoroughly, let stand for 10-20 minutes to mature, use within the activation period, and add ≤5% of the thinner;

[0055] 2.3. Coating application: Airless spraying process is adopted, with spraying pressure controlled at 18-22MPa, gun distance at 30-50cm, and gun speed at a uniform speed of 20-30cm / s. Cross-spraying method is used. For the inner wall corners, welds, and joints of the flow channel, a pre-coat is applied by brushing before the overall spraying is carried out to ensure no missed areas.

[0056] 2.4. Primer curing: Curing at room temperature for ≥24 hours. After curing, the dry film thickness of primer 2 should be controlled between 60 and 80 μm. A dry film thickness gauge should be used to check the dry film thickness at more than 85% of the measuring points to ensure that the dry film thickness meets the standard, and the dry film thickness at the remaining measuring points is not less than 85% of the specified value.

[0057] Step 3. Intermediate Coating: Select marine-grade epoxy thick-film intermediate paint 3 or epoxy micaceous iron oxide intermediate paint 3, and apply using an airless spraying process. After each coat, perform preliminary sanding, and cure at room temperature for ≥24 hours. The cured dry film thickness is 120-150 μm. Specific steps are as follows:

[0058] 3.1. Selection of intermediate paint: Select two-component epoxy thick-film intermediate paint 3 or epoxy micaceous iron oxide intermediate paint 3 for marine applications. It has good filling properties, abrasion resistance and interlayer adhesion, and is consistent with the specifications of marine intermediate paint 3.

[0059] 3.2. Intermediate paint preparation: Mix the main agent and hardener according to the specified ratio, stir evenly, add non-volatile thinner (≤3%), adjust the viscosity, and use within the activation period;

[0060] 3.3. Coating Application: After the primer 2 has cured to the required standard, airless spraying process is used for application, and the application parameters are the same as those for primer 2. For concrete substrate 1 or steel substrate 1 with uneven surface, 1 to 2 intermediate coats 3 are added. After each coat, preliminary sanding is performed to ensure that the coating surface is flat and without obvious protrusions.

[0061] 3.4. Intermediate Coating Curing: Curing at room temperature for ≥24 hours. After curing, the dry film thickness of intermediate coating 3 should be controlled at 120-150 μm, and the total dry film thickness should be controlled at 180-230 μm. The testing standards are the same as those for primer 2.

[0062] Step 4. Putty leveling: After the intermediate paint 3 has cured to the required standard, evenly apply epoxy putty 4 to its surface in two coats. After putty 4 has cured, sand it with 800-1000 grit sandpaper until the surface roughness Ra ≤ 6.3μm; the specific steps are as follows:

[0063] 4.1. Putty selection: Two-component epoxy putty 4 is selected, which has good leveling properties, wear resistance, no volatiles, and good adhesion to primer 2, intermediate paint 3 and topcoat 5.

[0064] 4.2. Putty application: After the intermediate paint 3 has cured to the required standard, apply epoxy putty 4 evenly to its surface. The thickness of the putty should be adjusted according to the flatness of the steel substrate 1 or concrete substrate 1, and the total thickness should not exceed 0.6mm. Apply in 2 coats, each coat being 0.2 to 0.3mm thick, with an interval of 8 to 12 hours between coats to ensure that the surface is free of depressions and pores after application.

[0065] 4.3. Putty Sanding: After putty 4 has cured, dry sand it with 800-1000 grit fine sandpaper until the surface is smooth and flat, without scratches or bumps, and the surface roughness Ra≤6.3μm. For high-precision wind tunnel channels, sand it to Ra≤3.2μm.

[0066] Step 5. Topcoat application: Select wind tunnel-specific high-solids smooth epoxy topcoat 5. After sanding putty 4 to the required standard, apply 2-3 coats using an airless spraying process, with an interval of ≥8 hours between each coat. After curing, control the dry film thickness of topcoat 5 to 80-100μm. Specific steps are as follows:

[0067] 5.1. Topcoat selection: High-solids smooth epoxy topcoat 5 for wind tunnel use is selected. This topcoat 5 has high hardness, high wear resistance, high gloss, low volatility, moisture resistance and easy cleaning properties. It has good compatibility with marine epoxy coating system and abandons the antifouling paint (containing toxic agents and self-polishing components) and ordinary polyurethane topcoat 5 commonly used in ships.

[0068] 5.2. Topcoat preparation: Mix the main agent and hardener according to the specified ratio, stir evenly, add ≤2% non-volatile thinner to ensure the topcoat concentration is 5, improve the surface gloss, and use it up within the activation period;

[0069] 5.3. Coating application: After the putty 4 is sanded to the standard, airless spraying process is used for application. The spraying pressure is controlled at 20-25MPa, the gun distance is 35-45cm, the gun speed is uniform, and cross-spraying is used. 2-3 thin coats are applied, and the interval between each coat is ≥8h to avoid defects such as sagging and orange peel.

[0070] 5.4. Topcoat curing: Curing at room temperature, with a total curing time of ≥48h. After curing, the dry film thickness of the topcoat 5 is controlled at 80~100μm. The total dry film thickness of the entire coating is: 300~350μm for steel channels and 280~330μm for concrete channels.

[0071] Step 6. Post-treatment and Quality Inspection: After topcoat 5 is fully cured, wipe the inner wall surface of the flow channel with a clean, dry cloth to remove surface dust. For minor defects, use topcoat 5 for local repair and fine sanding. Inspect the surface quality, film thickness, adhesion, volatile matter, and erosion resistance to ensure compliance with standards. Specific inspection indicators are as follows:

[0072] (1) Surface quality: The inner wall surface of the flow channel is smooth and uniform, without drips, pinholes, bubbles, cracks, or missed coatings, and the surface roughness Ra≤6.3μm (high-precision wind tunnel≤3.2μm);

[0073] (2) Film thickness test: The film thickness was tested using a dry film thickness gauge. The total dry film thickness at more than 85% of the measuring points met the standard, and the thickness at the remaining measuring points was not less than 85% of the specified value.

[0074] (3) Adhesion test: The cross-cut test was used. The coating adhesion was ≥ Grade 1, with no peeling or flaking.

[0075] (4) Volatile matter detection: The coating surface has no obvious odor, and the volatile matter content meets the requirements of the wind tunnel testing environment (≤0.1g / m²·24h).

[0076] (5) Abrasion resistance test: The coating was subjected to simulated high-speed airflow (flow velocity ≥ 50 m / s) for 24 hours. The coating showed no wear, no peeling, and no dust generation.

[0077] Example 1

[0078] Coating of the inner wall of steel wind tunnel flow channels (mainstream material for environmental wind tunnels)

[0079] This embodiment focuses on the mainstream steel welded wind tunnel flow channel of environmental wind tunnels, and adopts the coating method of the present invention. The specific steps are as follows:

[0080] 1. Substrate pretreatment: Remove floating dust, oil stains and welding spatter from the inner wall of the steel flow channel, and sandblast to Sa2.5 grade to expose a uniform metallic luster; wipe the surface with a non-volatile cleaning agent for marine painting to remove residual oil stains, and blow away dust with clean compressed air (oil-free and water-free); the construction environment temperature is 25℃, the relative humidity is 65%, and the steel surface temperature is 4℃ higher than the dew point.

[0081] 2. Primer application: Select marine epoxy zinc-rich primer 2 (two-component, main agent: hardener = 4:1), stir evenly and mature for 15 minutes, add 3% marine coating-specific non-volatile thinner; airless spraying, pressure 20MPa, gun distance 40cm, cross-spraying, pre-coat one coat at the edges and corners; cure at room temperature for 24 hours, dry film thickness 70μm, and the test meets the standard.

[0082] 3. Intermediate paint application: Select marine epoxy thick-film intermediate paint 3 (two-component, main agent: hardener = 5:1), stir evenly, add 2% marine coating-specific non-volatile thinner; airless spraying, parameters are the same as primer 2; cure at room temperature for 24 hours, dry film thickness 130μm, total dry film thickness 200μm, and the test meets the standards.

[0083] 4. Putty leveling: Select epoxy putty 4, apply with a thickness of 0.3mm, and cure at room temperature for 12 hours; dry sand with 800-grit sandpaper until the surface roughness Ra=4.5μm, and the surface is smooth and free of scratches.

[0084] 5. Topcoat application: Select wind tunnel-specific high-solids smooth epoxy topcoat 5 (two-component, main agent: hardener = 3:1), stir evenly, do not add thinner; airless spraying, pressure 22MPa, gun distance 40cm, two thin coats, 10h interval; room temperature curing for 48h, dry film thickness 90μm, total dry film thickness 310μm.

[0085] 6. Post-processing and testing: Wipe the surface with a dry cloth and repair minor pinholes; test the surface roughness Ra=4.2μm, the film thickness meets the standard at 88% of the test points, the adhesion is grade 1, the volatile content is 0.08g / m²·24h, and there is no wear after 24h of simulated high-speed airflow (60m / s), which meets the requirements for use in the steel flow channel of the environmental wind tunnel.

[0086] Example 2:

[0087] Coating of the inner wall of concrete wind tunnel flow channel

[0088] This embodiment focuses on the coating method of the present invention for concrete wind tunnel flow channels. The specific steps are as follows:

[0089] 1. Substrate pretreatment: Mechanically grind the inner wall of the concrete flow channel to remove loose sand and particles, repair surface depressions, and grind until the flatness error is ≤1.5mm / m; wipe the surface with a special non-volatile cleaning agent and blow away dust with clean compressed air; the construction environment temperature is 20℃, the relative humidity is 70%, and the concrete surface temperature is 3.5℃ higher than the dew point.

[0090] 2. Primer application: Marine-grade epoxy zinc-rich primer 2 (two-component) was selected, mixed and cured for 12 minutes, and 4% non-volatile thinner was added; airless spraying was carried out at a pressure of 18MPa and a gun distance of 35cm, with one pre-coat applied to the edges and corners; the coating was cured at room temperature for 24 hours, and the dry film thickness was 65μm, which met the test standards.

[0091] 3. Intermediate Coating: Marine-grade epoxy micaceous iron oxide intermediate paint 3 (two-component) was selected, with 3% non-volatile thinner added after mixing; airless spraying, parameters are the same as primer 2, with one additional intermediate paint 3 (2 coats in total); room temperature curing for 24 hours / coat, single coat dry film thickness 70μm, total dry film thickness 140μm (intermediate paint 3), total dry film thickness of primer 2 + intermediate paint 3 205μm, and the test results met the standards.

[0092] 4. Putty leveling: Use epoxy putty No. 4, apply in 2 coats, with a total thickness of 0.4mm, cure at room temperature for 12 hours per coat, and the total curing time is ≥24 hours; dry sand with 1000-grit sandpaper until the surface roughness Ra=3.8μm, and the surface is flat and without depressions.

[0093] 5. Topcoat application: Select wind tunnel-specific high-solids smooth epoxy topcoat 5, add 1% non-volatile thinner after mixing; airless spraying, pressure 20MPa, gun distance 45cm, 3 thin coats, 8h interval; room temperature curing for 48h, dry film thickness 85μm, total dry film thickness 290μm.

[0094] 6. Post-processing and testing: Wipe the surface with a dry cloth and repair local scratches; test the surface roughness Ra=3.6μm, the film thickness meets the standard at 90% of the test points, the adhesion is grade 1, the volatile content is 0.07g / m²·24h, and simulate high-speed airflow (55m / s) washing for 24h without wear and dust, which meets the requirements.

[0095] In the description of the invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention.

[0096] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of the invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0097] In this invention, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0098] The invention has been described above with reference to the accompanying drawings. Obviously, the specific implementation of the invention is not limited to the above-described manner. Any improvements made using the inventive concept and technical solution, or direct application to other situations without modification, are all within the scope of protection of the invention.

Claims

1. A method for coating the inner wall of a wind tunnel flow channel based on ship coating technology, characterized in that, The steps are as follows: Step 1. Substrate pretreatment: Select appropriate pretreatment methods for the substrate (1) of the inner wall of the wind tunnel flow channel. For steel substrate (1), sandblast to Sa2.5 grade. For concrete substrate (1), mechanically grind until there is no sand and the flatness error is ≤2mm / m. Both are degreasing and dust removal treatment. Control the construction environment temperature to 5~35℃ and the relative humidity to ≤85%. The surface temperature of substrate (1) is more than 3℃ higher than the ambient dew point. Step 2. Primer coating: Select marine epoxy zinc-rich primer (2), apply it using airless spraying process, use cross-spraying method, cure at room temperature, cure time ≥24h, after curing the primer (2) dry film thickness is controlled at 60~80μm, and the dry film thickness is measured by dry film thickness gauge. Step 3. Intermediate paint application: Select marine epoxy thick intermediate paint (3) or epoxy micaceous iron oxide intermediate paint (3), and apply it using an airless spraying process. After each coat, perform preliminary sanding, cure at room temperature, cure time ≥24h, and dry film thickness after curing is 120~150μm. Step 4. Putty leveling: After the intermediate paint (3) has cured to the standard, apply epoxy putty (4) evenly on its surface in 2 coats. After the putty (4) has cured, sand it with 800-1000 grit sandpaper until the surface roughness Ra≤6.3μm. Step 5. Topcoat application: Select wind tunnel-specific high-solids smooth epoxy topcoat (5). After the putty (4) is sanded to the standard, apply 2 to 3 coats using airless spraying process. The interval between each coat is ≥8h. After curing, control the dry film thickness of the topcoat (5) to 80 to 100μm. Step 6. Post-processing and quality inspection: After the topcoat (5) is fully cured, wipe the inner wall surface of the flow channel with a clean dry cloth to remove surface dust. For minor defects that appear locally, use the topcoat (5) to repair and finely polish them. Inspect the surface quality, film thickness, adhesion, volatiles and erosion resistance to ensure that the standards are met.

2. The method for coating the inner wall of a wind tunnel flow channel based on ship coating technology according to claim 1, characterized in that, The specific steps of substrate pretreatment in step 1 are as follows: 1.

1. Substrate cleaning: For the substrate (1) inside the wind tunnel flow channel, first remove the floating dust, oil stains, rust layer, old coating and debris from the surface. Among them, the steel substrate (1) is sandblasted and the concrete substrate (1) is mechanically ground. 1.

2. Rust removal / grinding grade control: Steel substrate (1) is sandblasted to Sa2.5 grade, with no visible rust, oxide scale and debris on the surface, and a uniform metallic luster is exposed; Concrete substrate (1) is ground until the surface is free of sand and loose particles, and the flatness error is ≤2mm / m; 1.

3. Surface cleaning: Wipe the surface of the substrate (1) with a non-volatile cleaning agent specifically for marine coating to remove residual oil stains; then blow it with clean compressed air to remove surface dust; 1.

4. Environmental and surface condition control: The ambient temperature during construction is controlled at 5-35℃, the relative humidity is ≤85%, and the surface temperature of the substrate (1) is more than 3℃ higher than the ambient dew point.

3. The method for coating the inner wall of a wind tunnel flow channel based on ship coating technology according to claim 2, characterized in that, The specific steps for applying the primer in step 2 are as follows: 2.

1. Primer selection: Select a two-component epoxy zinc-rich primer for marine applications (2), with the same specifications as the marine outer plating primer (2); 2.

2. Primer preparation: Mix the main agent and hardener according to the ratio specified in primer (2), stir thoroughly, let stand for 10-20 minutes to mature, use within the activation period, and add ≤5% of the thinner; 2.

3. Coating application: Airless spraying process is adopted, with spraying pressure controlled at 18-22MPa, gun distance at 30-50cm, and gun speed at a uniform speed of 20-30cm / s. Cross-spraying method is used. For the inner wall corners, welds, and joints of the flow channel, a pre-coat is applied by brushing before the overall spraying is carried out to ensure no missed areas. 2.

4. Primer curing: Curing at room temperature, curing time ≥24h. After curing, the dry film thickness of the primer (2) is controlled at 60~80μm. It is tested by a dry film thickness gauge to ensure that the dry film thickness of more than 85% of the measuring points meets the standard, and the dry film thickness of the remaining measuring points is not less than 85% of the specified value.

4. The wind tunnel duct inner wall coating method based on ship coating technology according to claim 3, characterized in that, The specific steps for applying the intermediate paint in step 3 are as follows: 3.

1. Selection of intermediate paint: Select two-component epoxy thick intermediate paint (3) or epoxy micaceous iron oxide intermediate paint (3) for marine use, with the same specifications as the marine intermediate paint (3); 3.

2. Intermediate paint preparation: Mix the main agent and hardener according to the specified ratio, stir evenly, add non-volatile thinner (≤3%), adjust the viscosity, and use within the activation period; 3.

3. Coating construction: After the primer (2) has cured to the standard, airless spraying process is used for construction, and the construction parameters are the same as those for primer (2); For concrete substrate (1) or steel substrate (1) with uneven surface, add 1 to 2 intermediate paints (3), and perform preliminary sanding after each coating to ensure that the coating surface is flat and without obvious protrusions; 3.

4. Intermediate paint curing: Curing at room temperature, curing time ≥24h, after curing the intermediate paint (3) dry film thickness is controlled at 120~150μm, the total dry film thickness is controlled at 180~230μm, and the testing standard is the same as that of primer (2).

5. A method for coating the inner wall of a wind tunnel flow channel based on ship coating technology according to claim 4, characterized in that, The specific steps for leveling with putty in step 4 are as follows: 4.

1. Putty selection: Select two-component epoxy putty (4); 4.

2. Putty application: After the intermediate paint (3) has cured to the required standard, apply epoxy putty (4) evenly to its surface. The thickness of the putty should be adjusted according to the flatness of the steel substrate (1) or concrete substrate (1). The total thickness should not exceed 0.6 mm. Apply in two coats, each coat being 0.2 to 0.3 mm thick. The two coats should be applied 8 to 12 hours apart to ensure that the surface is free of depressions and pores after application. 4.

3. Putty sanding: After the putty (4) has cured, dry sand it with fine sandpaper of 800 to 1000 grit until the surface is smooth and flat, without scratches or protrusions, and the surface roughness Ra≤6.3μm. For high-precision wind tunnel channels, sand it until Ra≤3.2μm.

6. A method for coating the inner wall of a wind tunnel flow channel based on ship coating technology according to claim 5, characterized in that, The specific steps for topcoat application in step 5 are as follows: 5.

1. Topcoat selection: Select wind tunnel-specific high-solids smooth epoxy topcoat (5); 5.

2. Topcoat preparation: Mix the main agent and hardener according to the specified ratio, stir evenly, add ≤2% non-volatile thinner to ensure the concentration of topcoat (5), improve the surface gloss, and use it up within the activation period; 5.

3. Coating construction: After the putty (4) is sanded to the standard, airless spraying process is used for construction. The spraying pressure is controlled at 20-25MPa, the gun distance is 35-45cm, the gun speed is uniform, cross-spraying is used, and 2-3 thin coats are applied. The interval between each coat is ≥8h to avoid sagging and orange peel defects. 5.

4. Topcoat curing: Curing at room temperature, total curing time ≥ 48h, after curing, the dry film thickness of the topcoat (5) is controlled at 80~100μm, the total dry film thickness of the full coating: 300~350μm for steel flow channels, 280~330μm for concrete flow channels.

Images