Spraying method for high-temperature molten salt corrosion resistant coating

Abstract

The invention discloses a spraying method for a high-temperature molten salt corrosion resistant coating. The spraying method comprises the following steps that S1, a sample is placed on a rotating target; s2, fixing the position of a nozzle on the spray gun; s3, the coating is poured into a gravity feeding groove; s4, an air pressure valve on the spray gun is pressed down, and coating suspension liquid is sprayed; s5, after the coating of the sample is covered, waiting for drying; and S6, the spray gun is cleaned. The method is used for solving the problem that the spraying thicknesses of the stainless steel test pieces resistant to high-temperature molten salt corrosion are inconsistent.

Description

Technical Field

[0001] The invention relates to a spraying technology, and more particularly to a spraying method for a coating resistant to high-temperature molten salt corrosion. Background Art

[0002] Spraying technology is usually used for spraying or brushing large surfaces, and different types of sprayers have been developed depending on the purpose and application. Low-pressure (conventional) air spray, mainly side-type gravity sprayers also known as air atomizing sprayers, is the oldest type of air sprayer and is usually used for automotive painting or small surface coating, however, this low-pressure air spray method is not suitable for thick coating applications. Spray atomization prevents the coating material from entering tight corners and surface pores, so it is not recommended for coating of complex structures. Airless / high-pressure spraying, this method is mainly used for anti-corrosion coatings / paints, and the coating liquid is separated by the pressure difference created by passing high-pressure liquid through a small nozzle hole. This causes a fine mist to hit the surface at a high speed, which can more easily enter corners and surface pores than conventional (low-pressure) spraying.

[0003] In summary, spraying is a process of atomizing a coating liquid / paste / paint and then flowing it onto the target surface for coating deposition. The advantages of using carbon-based materials in coatings include good mechanical and thermal stability, high melting point, airtightness, liquid state, low chemical reactivity, and reduced coating thickness. Commonly used carbon-based coatings include graphite, graphene, graphene oxide, carbon nanotubes, as well as traditional coatings and graphene-based self-healing coatings. Summary of the invention

[0004] In view of the defects existing in the prior art, the purpose of the present invention is to provide a spraying method for a high-temperature molten salt corrosion resistant coating, which is used to solve the problem of inconsistent spraying thickness of stainless steel specimens resistant to high-temperature molten salt corrosion.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A spraying method for a high-temperature molten salt corrosion resistant coating comprises the following steps:

[0007] S1. Place the sample on the rotating target;

[0008] S2, fix the position of the nozzle on the spray gun;

[0009] S3, pouring the coating into the gravity feed tank;

[0010] S4, pressing the air pressure valve on the spray gun to spray the coating suspension;

[0011] S5. After the coating of the sample is completed, wait for drying;

[0012] S6, cleaning the spray gun.

[0013] Preferably, the sample is 304, 304L, 316, 316L, 312 or 347 stainless steel plate.

[0014] Preferably, the diameter of the rotating target is 20 cm±0.5 cm, and the rotation speed is 1 rpm to 5 rpm.

[0015] Preferably, the distance between the rotating target and the spray gun is 10 cm to 20 cm;

[0016] The included angle between the rotating target and the spray gun is 90°.

[0017] Preferably, the air pressure of the spray gun is 1 bar to 5 bar.

[0018] Preferably, the coating has 2 to 6 layers, and the waiting time for drying is 8 to 10 minutes.

[0019] Preferably, the cleaning of the spray gun specifically comprises the following steps:

[0020] S61, emptying the contents of the gravity feed tank, adding distilled water and spraying it onto the paper, and then disconnecting the spray gun from the hose position;

[0021] S62, after the graphite powder in the spray gun is washed away, rinse the spray gun with warm water;

[0022] S63, connecting the spray gun to the hose again, and starting the compressor, adding distilled water to the gravity feed tank and spraying it on the paper until there is no graphite powder in the nozzle. If there are still black spots on the paper, repeat step S62;

[0023] S64, adding ethanol to the gravity feed tank and spraying it onto the paper until the spray gun is completely dry.

[0024] The spraying method for a high-temperature molten salt corrosion resistant coating provided by the present invention can meet the test method of the "National Solar Thermal Industry Technology Innovation Strategic Alliance Standard (T / CSTA 19-2021)", and it is necessary to ensure that the tested stainless steel plate coating is uniform, dense, and has strong adhesion to ensure that the coating adheres to the metal surface. The spraying method of the present invention is mainly used for water-based coatings. The formula of the coating will include graphite particles with a particle size in the micron range. As the main component of the anti-corrosion coating, the graphite particles can be uniformly adhered to the stainless steel substrate. The suspension medium is water, which is safe and environmentally friendly, has no volatile organic gas VOC that pollutes the environment, and is easy to construct. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic flow diagram of the spraying method of the present invention;

[0026] Figure 2 Schematic diagram of the SEM surface image of the sample in Example 1 of the spray coating method of the present invention;

[0027] Figure 3 It is a schematic diagram of the SEM surface image of the sample in Example 2 of the spraying method of the present invention. DETAILED DESCRIPTION

[0028] In order to better understand the above technical solution of the present invention, the technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0029] Combination Figure 1 As shown, a spraying method for a high-temperature molten salt corrosion resistant coating provided by the present invention comprises the following steps:

[0030] S1. Place the sample on the rotating target;

[0031] S2, fix the position of the nozzle on the spray gun;

[0032] S3, pouring the coating into the gravity feed tank;

[0033] S4. Press the air pressure valve on the spray gun to spray the coating suspension;

[0034] S5. After the sample is coated, wait for it to dry;

[0035] S6. Clean the spray gun.

[0036] The sample is 304, 304L, 316, 316L, 312 or 347 stainless steel plate, preferably 347 stainless steel plate.

[0037] The purpose of the rotating target is to move the sample at a constant rotation speed while spraying the coating solution, thereby positioning the sample and controlling the deposition rate.

[0038] The diameter of the rotating target is 20 cm±0.5 cm, and the rotation speed is 1 rpm to 5 rpm, preferably 2 rpm to 4 rpm.

[0039] Placement of the spray gun: The distance between the rotating target and the spray gun is 10 cm to 20 cm, preferably 15 cm; the angle between the rotating target and the spray gun is 90°.

[0040] For best results, position the air pressure valve towards the operator before pressing it to move the needle backwards. This is to prevent the build-up of graphite particles in the spray gun nozzle, which can cause the spray gun to clog; stop spraying the coating suspension once all samples have been coated. The sample can be left rotating while it dries. It takes about 10 minutes to touch dry.

[0041] The air pressure is controlled by an air compressor, and the air pressure of the spray gun is 1 bar to 5 bar. The air pressure is controlled by an air compressor to control the amount of solution sprayed onto the stainless steel base material.

[0042] The coating is 2 to 6 layers, that is, the best time to rotate the sprayer is 1 to 3 minutes. The waiting time for drying is 8 to 10 minutes.

[0043] The cleaning of the spray gun specifically includes the following steps:

[0044] S61. Empty the contents of the gravity feed tank, add distilled water and spray onto the paper, then disconnect the spray gun from the hose.

[0045] S62. After the graphite powder in the spray gun is washed away, rinse the spray gun with warm water;

[0046] S63, connect the spray gun to the hose again, start the compressor, add distilled water to the gravity feed tank and spray on the paper until there is no graphite powder in the nozzle. If there are still black spots on the paper, repeat step S62;

[0047] S64. Add ethanol to the gravity feed trough and spray onto the paper until the spray gun is completely dry.

[0048] The spraying method of the present invention is used to test the carbon-based high temperature molten salt corrosion resistant coating of stainless steel in solar salt, and can reduce the inconsistency of the coating thickness of different slurries to produce a uniform coating with a well-controlled microstructure on the metal surface.

[0049] Example 1

[0050] The spraying method for the high temperature molten salt corrosion resistant coating of this embodiment 1 comprises the following steps:

[0051] 1) Prepare the spray station and place the 347 stainless steel sample on the rotating target, setting the rotation speed to 2 rpm;

[0052] 2) Fix the spray gun, control the distance between the spray gun nozzle and the rotating target to be 15 cm, the angle between the spray gun nozzle and the rotating target to be 90°, and set the air compressor pressure to 2.2 bar;

[0053] 3) Pour the coating suspension into the gravity feed tank of the spray gun, press the air pressure valve of the spray gun, and spray the coating suspension; rotate for 2 minutes, and stop spraying the coating suspension when all samples are coated. It takes about 10 minutes for the samples to be touch dry;

[0054] 4) Clean the spray gun and add distilled water to the gravity feed tank. Spray the distilled water on the paper to confirm that no graphite particles are left in the nozzle; add ethanol to the gravity feed tank. Spray the ethanol on the paper until the spray gun is completely dry.

[0055] like Figure 2 As shown, in the sample of Example 1, on a microscopic scale, carbon grains can be seen deposited on the alloy surface without any exposed areas.

[0056] Example 2

[0057] The spraying method for the high temperature molten salt corrosion resistant coating of this embodiment 2 comprises the following steps:

[0058] 1) Prepare the spray station and place the 347 stainless steel sample on the rotating target, setting the rotation speed to 1 rpm;

[0059] 2) Fix the spray gun, control the distance between the spray gun nozzle and the rotating target to be 12 cm, the angle between the spray gun nozzle and the rotating target to be 90°, and set the air compressor pressure to 2 bar;

[0060] 3) Pour the coating suspension into the gravity feed tank of the spray gun, press the air pressure valve of the spray gun, and spray the coating suspension; rotate for 5 minutes, and stop spraying the coating suspension when all samples are coated. It takes about 10 minutes for the samples to be touch dry;

[0061] 4) Clean the spray gun and add distilled water to the gravity feed tank. Spray the distilled water on the paper to confirm that no graphite particles are left in the nozzle; add ethanol to the gravity feed tank. Spray the ethanol on the paper until the spray gun is completely dry.

[0062] like Figure 3 As shown, in the sample of Example 2, on a microscopic scale, carbon grains can be seen deposited on the alloy surface without any exposed areas.

[0063] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present invention, and are not intended to limit the present invention. As long as they are within the spirit of the present invention, any changes or modifications to the above embodiments will fall within the scope of the claims of the present invention.

Claims

1. A spraying method for a high temperature molten salt corrosion resistant coating, characterized in that: The following steps are involved: S1. Place the sample on the rotating target; S2, fix the position of the nozzle on the spray gun; S3, pouring the coating into the gravity feed tank; S4, pressing the air pressure valve on the spray gun to spray the coating suspension; S5. After the coating of the sample is completed, wait for drying; S6, cleaning the spray gun.

2. The spraying method for high temperature molten salt corrosion resistant coating according to claim 1, characterized in that: The sample is 304, 304L, 316, 316L, 312 or 347 stainless steel plate.

3. The spraying method for high temperature molten salt corrosion resistant coating according to claim 1, characterized in that: The diameter of the rotating target is 20 cm±0.5 cm, and the rotation speed is 1 rpm to 5 rpm.

4. The spraying method for high temperature molten salt corrosion resistant coating according to claim 3, characterized in that: The distance between the rotating target and the spray gun is 10 cm to 20 cm; The included angle between the rotating target and the spray gun is 90°.

5. The spraying method for high temperature molten salt corrosion resistant coating according to claim 1, characterized in that: The air pressure of the spray gun is 1 bar to 5 bar.

6. The spraying method for high temperature molten salt corrosion resistant coating according to claim 1, characterized in that: The coating is 2 to 6 layers, and the waiting drying time is 8 to 10 minutes.

7. The spraying method for high temperature molten salt corrosion resistant coating according to claim 1, characterized in that: The cleaning of the spray gun specifically comprises the following steps: S61, emptying the contents of the gravity feed tank, adding distilled water and spraying it onto the paper, and then disconnecting the spray gun from the hose position; S62, after the graphite powder in the spray gun is washed away, rinse the spray gun with warm water; S63, connecting the spray gun to the hose again, and starting the compressor, adding distilled water to the gravity feed tank and spraying it on the paper until there is no graphite powder in the nozzle. If there are still black spots on the paper, repeat step S62; S64, adding ethanol to the gravity feed tank and spraying it onto the paper until the spray gun is completely dry.

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