Preparation method of constant-radiance ultrathin coating for wide-temperature-range air atmosphere

Abstract

The invention relates to a preparation method of a constant-radiance ultrathin coating for a wide-temperature-range air atmosphere, which comprises the following steps: dispersing aluminum oxide particles in an alcohol solution as a radiation layer raw material, spraying the radiation layer raw material on the surface of a material coated with a high-temperature-resistant paste adhesion layer, and naturally drying to obtain the ultrathin coating. The adhesive layer and the radiation layer are combined, so that the surface of a tested sample can be effectively coated with a very small thickness, and on the premise that the surface state and physicochemical properties of a to-be-tested object are not changed, the fixed radiance is kept under the condition of continuous temperature change in the range from room temperature to high temperature in an air atmosphere and can be kept consistent with the plastic deformation state of the material surface. And the application temperature range and the application atmosphere of an infrared temperature control means in a variable-temperature mechanical property test are widened.

Description

Technical Field

[0001] The present invention relates to a technology in the field of infrared radiation coatings, in particular to a method for preparing an ultra-thin coating with a constant emissivity for air atmospheres in a wide temperature range. Background Art

[0002] In the wide temperature range variable temperature mechanical property test, it is often necessary to perform accurate temperature measurement without interfering with the surface state and physicochemical properties of the sample to be tested. Infrared temperature measurement, as a non-contact temperature measurement method, can be effectively applied to this type of test environment. Under normal circumstances, the infrared temperature measurement equipment monitors the radiation energy of the sample at a certain distance to determine the surface temperature of the sample being measured. The size of the infrared radiation energy is not only related to the temperature, but also affected by the emissivity of the sample surface material. In order to achieve accurate measurement, the emissivity value must be measured before infrared temperature measurement or a coating with stable emissivity must be applied on the sample surface. The former often uses contact temperature measurement to obtain the actual temperature of the object to be measured, and uses an infrared thermometer to measure the temperature and adjust the emissivity until the displayed temperature is consistent with the actual temperature. The emissivity value measured by this method changes with temperature and is not suitable for variable temperature testing under a wide temperature range. At the same time, most materials have high-temperature oxidation and other phenomena in air atmosphere, and their actual emissivity values ​​also change with the heating path. The latter often uses materials with high and stable emissivity values ​​as surface coatings, and sets the emissivity of the infrared thermometer to this stable value. In order to ensure good adhesion of the coating, organic matrix materials are often mixed, and a hard and brittle coating is formed by energy field-assisted spraying or heating curing, which makes the coating unable to plastically deform with the surface of the material. At the same time, some coating materials oxidize and denature at around 600°C, no longer maintaining stable radiation performance, and are not suitable for infrared temperature measurement at higher temperatures in air atmosphere. In addition, in order to ensure the accuracy of mechanical property test results, the coating should be as thin as possible. Summary of the invention

[0003] In view of the shortcomings of existing coatings that are difficult to follow the deformation of the surface of the test sample and cannot be used in the field of mechanical performance testing and cannot be used in long-term high-temperature environments, the present invention proposes a method for preparing a constant emissivity ultra-thin coating for a wide temperature range air atmosphere. By combining an adhesive layer and a radiation layer, it can be effectively coated on the surface of the test sample with a very small thickness. On the premise of not changing the surface state and physicochemical properties of the object to be tested, it maintains a fixed emissivity under continuous temperature changes from room temperature to high temperature in an air atmosphere, and can be consistent with the plastic deformation state of the material surface. It broadens the application temperature range and applicable atmosphere of infrared temperature control means in variable temperature mechanical performance testing.

[0004] The present invention is achieved through the following technical solutions:

[0005] The invention relates to a method for preparing a constant emissivity ultra-thin coating for air atmosphere in a wide temperature range, wherein aluminum oxide particles are dispersed in an alcohol solution as a raw material for a radiation layer, and the solution is sprayed on the surface of a material coated with a high-temperature resistant paste adhesive layer, and the ultra-thin coating is obtained after natural drying.

[0006] The alcohol solution is a 75% alcohol aqueous solution.

[0007] The particle size of the aluminum oxide particles is 1 μm.

[0008] The adhesive layer material does not change in properties at high temperatures and maintains high viscosity, and is preferably a non-metallic high-temperature grease.

[0009] In the dispersion, the mass ratio of aluminum oxide powder to 75% alcohol solution is 1:1.5 to 1:2.

[0010] The dispersion is preferably carried out by ultrasonic dispersion for 10 to 20 minutes to make the aluminum oxide particles uniformly dispersed.

[0011] The coating means: applying the adhesive layer material on the cleaned and dusted surface, and repeatedly spreading it with a brush or a scraper to make the thickness of the adhesive layer reach 10 to 20 μm.

[0012] The spraying is carried out using, but not limited to, atomizing equipment such as an airbrush, and the spraying pressure is 0.2-0.5 MPa.

[0013] The coating thickness obtained after spraying is 25 to 30 μm. Technical Effects

[0014] The present invention uses a paste-like high-temperature resistant material as an adhesive layer, so that the coating can be plastically deformed with the surface without deformation resistance. At the same time, the optimal thickness and matching ratio of the aluminum oxide radiation layer and the non-metallic high-temperature resistant adhesive layer are explored to obtain a radiation coating with aluminum oxide as the single radiation material, which can provide good thermal stability, surface adhesion and stable radiation performance at a very small thickness. The coating does not need to be cured and can be plastically deformed with the surface of the material without deformation resistance. It is effectively used in mechanical testing in air environments at room temperature to 1200°C. When the temperature is measured using an infrared temperature measuring device with a spectral range of 8 to 14μm, the emissivity value of the coating is between 0.91 and 0.93. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a flow chart of the present invention;

[0016] Figure 2 This is a schematic diagram of the sample clamping position during the emissivity test;

[0017] Figure 3 This is a schematic diagram of the emissivity test platform;

[0018] Figure 4 Schematic diagram of the relationship between emissivity value and temperature. DETAILED DESCRIPTION

[0019] This embodiment relates to a method for preparing a constant emissivity ultra-thin coating for air atmosphere in a wide temperature range, comprising:

[0020] Step 1, prepare the radiation layer raw material: according to the mass ratio of 1:2, the pure aluminum oxide powder with a particle size of 1 μm is uniformly mixed with 75% alcohol solution, and ultrasonically dispersed for 10 minutes to make the aluminum oxide particles uniformly dispersed in the alcohol solution.

[0021] Step 2: Apply adhesive layer: Clean the surface of the sample to be tested with water and high-purity alcohol respectively, and wipe with dust-free absorbent paper to remove residual liquid. Blow the surface clean with an air gun. Apply YAMATE FG-50 non-metallic high-temperature anti-seizure grease on the surface of the sample to be tested, and use a clean silicone scraper to apply it repeatedly until the surface of the sample to be tested is evenly covered with a layer of anti-seizure grease with a thickness of 10 to 15 μm.

[0022] Step 3, spraying the radiation layer: Pour the prepared coating material into the U-speed S-120 airbrush, keep the tip of the airbrush 100mm away from the surface of the sample to be tested and aim at the test point perpendicular to the surface, spray at a pressure of 0.5MPa for 2s. Then let the sample stand for 10min to wait for the alcohol solution to evaporate completely.

[0023] The emissivity of the coating of the present invention was determined by a specific actual experiment. The coating of the present invention was prepared on one side of a 1.5 mm thick titanium alloy and a 2 mm thick steel sample, and a K-shaped thermocouple was welded at the center of the other side. The sample was placed in a Figure 2 Place the test fixture with a heating furnace as shown in the figure with the coated surface facing outward. Use the Optris CT3 infrared thermometer to face the sample at a vertical distance of 100 mm from the sample surface, so that the laser of the Optris CT3 infrared thermometer is focused on the center of the coated surface. Then turn off the heating furnace and slowly increase the temperature. There is a narrow window on the front of the furnace body to facilitate the thermometer to directly measure the surface temperature of the sample. During the test, when the temperature of the heating furnace is stable within a fixed value of ±1°C for more than 5 minutes, the temperature of the heating furnace and the sample is considered stable. Then continuously adjust the emissivity value in the infrared thermometer until the temperature shown by the infrared thermometer is consistent with the thermocouple temperature. The emissivity value changes with temperature as shown in the figure below: Figure 4 shown.

[0024] The coating prepared in this embodiment can maintain a fixed emissivity value for a long time in an air atmosphere at any temperature within the range of room temperature to 1200°C. After testing, when the surface of the tested sample has the coating prepared in this embodiment, the temperature is measured using an infrared temperature measuring device with a spectral range of 8 to 14 μm, and its emissivity value is 0.92.

[0025] Compared with the prior art, the coating of the present invention is made of high-radiation material with good high-temperature stability and can The coating of the present invention uses a paste-like high-temperature resistant material that does not need to be cured as an adhesive layer, and defines the optimal thickness ratio of the adhesive layer and the radiation layer, so that the coating can deform without resistance with the surface of the material without cracking, and is therefore suitable for the field of high-temperature mechanical testing.

[0026] The above-mentioned specific implementation can be partially adjusted in different ways by those skilled in the art without departing from the principle and purpose of the present invention. The protection scope of the present invention shall be based on the claims and shall not be limited by the above-mentioned specific implementation. Each implementation scheme within its scope shall be subject to the constraints of the present invention.

Claims

1. A method for preparing an ultra-thin coating with a constant emissivity for air atmosphere in a wide temperature range, characterized in that: Alumina particles are dispersed in an alcohol solution as the raw material of the radiation layer, and sprayed on the surface of the material coated with a high-temperature resistant paste adhesive layer, and an ultra-thin coating is obtained after natural drying.

2. The method for preparing the ultra-thin coating with constant emissivity for wide temperature range air atmosphere according to claim 1, characterized in that: The adhesive layer material is non-metallic high-temperature grease.

3. The method for preparing the ultra-thin coating with constant emissivity for wide temperature range air atmosphere according to claim 1, characterized in that: In the dispersion, the mass ratio of aluminum oxide powder to 75% alcohol solution is 1:1.5 to 1:

2.

4. The method for preparing the ultra-thin coating with constant emissivity for wide temperature range air atmosphere according to claim 1, characterized in that: The dispersion is carried out by ultrasonic dispersion for 10 to 20 minutes to make the aluminum oxide particles dispersed evenly.

5. The method for preparing the ultra-thin coating with constant emissivity for wide temperature range air atmosphere according to claim 1, characterized in that: The coating means: applying the adhesive layer material on the cleaned and dusted surface, and repeatedly spreading it with a brush or a scraper to make the thickness of the adhesive layer reach 10 to 20 μm.

6. The method for preparing the ultra-thin coating with constant emissivity for wide temperature range air atmosphere according to claim 1, characterized in that: The spraying adopts atomizing equipment, and the spraying pressure is 0.2-0.5MPa.

7. The method for preparing the ultra-thin coating with constant emissivity for wide temperature range air atmosphere according to claim 1 or 6, characterized in that: The coating thickness obtained after spraying is 25-30 μm.

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