Wave band selective emission coating and preparation method thereof

Abstract

The invention discloses a wave band selective emission coating and a preparation method thereof, and belongs to the technical field of electromagnetic materials. In order to solve the technical problems that a traditional coating is difficult to realize low emission of 3-5 microns and high emission of 7-14 microns at the same time and cannot realize heat control and heat dissipation at the same time, the invention adopts a complex phase structure composed of a filler and a base material, selects submicron equiaxed crystal oxide with the particle size of 0.5-5 microns, and combines surface modification to realize uniform dispersion; the coating has low emissivity in a medium wave band, has high emissivity in a long wave band, and has high-temperature stability of 1000 DEG C or above. According to the invention, accurate regulation and control of infrared emission characteristics can be realized.

Description

TECHNICAL FIELD

[0001] The present application relates to a waveband selective emission coating and a preparation method thereof, and belongs to the technical field of electromagnetic materials. BACKGROUND

[0002] With the in-depth application of infrared thermal management technology in the field of high-end manufacturing and energy engineering, the dual-waveband partition coating with low emissivity in 3~5um and high emissivity in 7~14um has become the key material to solve the contradiction between directional heat control and efficient heat dissipation in complex scenarios, because it can accurately control the thermal radiation characteristics. For example, in the field of building thermal insulation, the sun-facing surface needs to resist the accumulation of solar radiation heat, while dissipating heat to the outside through infrared radiation. Traditional single emissivity coating cannot meet both requirements. If the overall emissivity is low, the heat cannot be effectively radiated; if the overall emissivity is high, the temperature will be out of control due to excessive heat absorption. Therefore, the coating must be designed with targeted emissivity: low emissivity in 3~5um to reduce the absorption of solar medium wave radiation; high emissivity above 7um to enhance long-wave infrared radiation heat dissipation, thereby efficiently radiating heat to the atmosphere and achieving effective heat dissipation of the building.

[0003] In addition, this technology can also be applied to industrial high-temperature kiln and other scenarios, playing an important role as an energy-saving coating: reducing heat dissipation in the furnace body through low emissivity in 3~5um, while achieving heat dissipation through high emissivity above 7um to protect the metal structure from damage due to overheating. Therefore, this technology has broad application prospects. SUMMARY

[0004] The purpose of the present application is to provide a waveband selective emission coating and a preparation method thereof, to solve the technical problem that existing coatings cannot simultaneously achieve directional heat control and efficient heat dissipation by balancing low emissivity in 3~5um and high emissivity in 7~14um, and to achieve precise control of emissivity in different infrared wavebands, while maintaining high-temperature stability and wide applicability.

[0005] To achieve the above-mentioned purpose, the present application adopts the following technical solutions.

[0006] A waveband selective emission coating, comprising a complex structure of fillers and binders; the fillers are oxides , A is one of Ce, Ti, Zr, and Hf, and is a sub-micron equiaxed crystal structure with a particle size of 0.5~5um; the binders are , and 2.5≤x≤3.

[0007] Further, the fillers account for 30%~60% of the total mass of the waveband selective emission coating.

[0008] Further, the thickness of the waveband selective emission coating is 0.5~3mm.

[0009] A method for preparing a waveband selective emission coating, comprising the following steps: (1) selecting a powder with a particle size of 0.1-5 μm, wherein A is one of Ce, Ti, Zr, Hf, and the powder is calcined to obtain a calcined powder; (2) ball-milling the calcined powder; (3) rotary-evaporating the ball-milled powder; (4) sieving the rotary-evaporated powder to obtain a powder with a particle size of 0.5-5 μm; (5) adding the powder to deionized water to form a suspension, adding 0.5-1% of the mass of the powder of polyvinylpyrrolidone to the suspension, and uniformly dispersing the obtained glue solution by magnetic stirring; (6) centrifuging the uniformly stirred glue solution, removing the supernatant, and drying to obtain a surface-modified powder; (7) adding the modified powder to 2.5≤x≤3 at a mass fraction of 30%-60%, and uniformly dispersing the obtained glue solution by magnetic stirring; (8) air-spraying the glue solution as raw material; (9) placing the sprayed coating in an oven to heat and solidify, cooling to room temperature, and obtaining a solidified layer; (10) heating the solidified coating for post-treatment, cooling to room temperature, and obtaining a waveband selective emission coating.

[0010] Further, the calcination condition in step (1) is: calcination at 800-1300 °C for 5-10 h.

[0011] Further, the ball-milling condition in step (2) is: a ball-milling machine speed of 200-400 r / min, a ball-milling time of 20-30 h, an ethanol ball-milling medium, a mass ratio of the powder to the medium of 1:3-1:2, and a mass ratio of the grinding balls to the powder of 4:1-5:1.

[0012] Further, the rotary-evaporation condition in step (3) is: a rotary-evaporation temperature of 80-85 °C, and a rotary-evaporation time of 1-2 h.

[0013] Further, the mass ratio of the powder to water in the suspension in step (5) is 1:3-1:4, and the stirring condition is: a stirring speed of 300-400 rpm, and a stirring time of 3-5 h.

[0014] Further, the centrifugation condition in step (6) is: a centrifugation speed of 2000-3000 r / min, and a centrifugation time of 3-5 min.

[0015] Furthermore, the stirring conditions in step (7) are: stirring speed of 300~400 rpm and stirring time of 3~5 h.

[0016] Furthermore, the spraying conditions in step (8) are: spraying pressure of 2~4MPa, spraying distance of 20~30cm, and spray gun nozzle diameter of 0.5~2mm.

[0017] Further, the curing conditions in the oven in step (9) are as follows: first, keep the oven at room temperature for 20~30h and control the humidity at 30%~50%; then, raise the temperature to 80~120℃ at 2~5℃ / min and keep it at 1~3h; then raise the temperature to 160~200℃ at 2~5℃ / min and keep it at 2~4h.

[0018] Further, the post-heating treatment conditions in step (10) are: heating to 600~800℃ at a heating rate of 5~10℃ / min and holding for 2~5h.

[0019] The present invention has achieved the following beneficial effects.

[0020] 1. This invention employs... As an adhesive, polyvinylpyrrolidone is used for surface modification, which enables the filler particles to be uniformly dispersed in the base material and achieve strong adhesion, thereby improving the structural density and overall stability of the coating.

[0021] 2. This invention utilizes particles with a diameter of 0.5~5μm. The filler enhances the scattering effect in the 3-5μm band based on the Mie scattering principle, thereby significantly reducing the emissivity in this band, while also combining... Intrinsic high emission characteristics of materials above 7μm and The infrared transparency enables the coating to achieve selective emission performance with low emission in the 3~5μm band and high emission in the 7~20μm band. The average emissivity in the 3~5μm band is less than 0.25, and the average emissivity in the 7~20μm band is not less than 0.7.

[0022] 3. This invention employs and It forms a stable multiphase structure, with both phases exhibiting good compatibility and high-temperature stability, and a temperature resistance exceeding 1000℃. The coating maintains structural and phase stability under high-temperature environments, meeting the application requirements of building energy conservation, high-temperature kiln energy conservation, and other applications. Attached Figure Description

[0023] Figure 1 A physical image of the band-selective emission coating prepared in Example 1; Figure 2 A photograph of the band-selective emission coating prepared in Example 2; Figure 3This is a physical image of the band-selective emission coating prepared in Example 3. Detailed Implementation

[0024] To make the various technical features, advantages, or effects of the present invention more apparent and understandable, detailed descriptions are provided below through embodiments.

[0025] Example 1: A method for preparing a band-selective emission coating.

[0026] (1) Select particles with a diameter of 0.1 μm The powder was calcined at 800℃ for 5 hours to obtain the calcined powder.

[0027] (2) The calcined powder was ball-milled at a speed of 200 r / min for 20 h. The ball milling medium was ethanol, the mass ratio of powder to medium was 1:3, and the mass ratio of grinding balls to powder was 4:1.

[0028] (3) The ball-milled powder was subjected to rotary evaporation at a temperature of 80°C for 1 hour.

[0029] (4) The rotary evaporated powder is sieved to obtain powder with a particle size of 0.5 μm.

[0030] (5) Add the powder to deionized water to form a suspension. The mass ratio of powder to water is 1:3. Add 0.5% of the powder mass of polyvinylpyrrolidone to the suspension. Disperse the obtained liquid evenly by magnetic stirring. The stirring speed is 300 rpm and the stirring time is 3 hours.

[0031] (6) Centrifuge the well-stirred adhesive solution at a speed of 2000 r / min for 3 min, remove the supernatant, dry it, and obtain the surface-modified powder.

[0032] (7) Add the modified powder at a mass fraction of 30%. The obtained adhesive solution was dispersed evenly by magnetic stirring at a speed of 300 rpm for 3 hours.

[0033] (8) The adhesive liquid is used as raw material for air spraying. The spraying pressure is 2MPa, the spraying distance is 20cm, and the nozzle diameter of the spray gun is 0.5mm.

[0034] (9) Place the sprayed coating in an oven for curing. The curing process is to keep it at room temperature for 20 hours, control the humidity at 30%, then raise the temperature to 80°C at 2°C / min and keep it at 80°C for 1 hour, raise the temperature to 160°C at 2°C / min and keep it at 160°C for 2 hours, and then cool it to room temperature with the oven.

[0035] (10) The cured coating was post-treated by heating it to 600°C at a heating rate of 5°C / min, holding it at that temperature for 2 hours, and then cooling it to room temperature in the furnace to obtain a band-selective emission coating.

[0036] The prepared band-selective emission coating showed an average emissivity of 0.21 in the 3-5 μm range and 0.75 in the 7-20 μm range, with a bonding strength of 2.4 MPa.

[0037] Example 2: A method for preparing a band-selective emission coating.

[0038] (1) Select particles with a diameter of 5 μm The powder was calcined at 1300℃ for 10 hours to obtain the calcined powder.

[0039] (2) The calcined powder was ball-milled. The ball mill speed was 400 r / min, the ball milling time was 30 h, the ball milling medium was ethanol, the mass ratio of powder to medium was 1:2, and the mass ratio of grinding balls to powder was 5:1.

[0040] (3) The ball-milled powder was subjected to rotary evaporation at a temperature of 85°C for 2 hours.

[0041] (4) The rotary evaporated powder is sieved to obtain powder with a particle size of 5 μm.

[0042] (5) Add the powder to deionized water to form a suspension. The mass ratio of powder to water is 1:4. Add 1% of the powder mass of polyvinylpyrrolidone to the suspension. Disperse the obtained liquid evenly by magnetic stirring. The stirring speed is 400 rpm and the stirring time is 5 h.

[0043] (6) Centrifuge the well-stirred adhesive solution at a speed of 3000 r / min for 5 min, remove the supernatant, dry it, and obtain the surface-modified powder.

[0044] (7) Add the modified powder at a mass fraction of 60%. The obtained adhesive solution was dispersed evenly by magnetic stirring at a speed of 400 rpm for 5 hours.

[0045] (8) The adhesive liquid is used as raw material for air spraying. The spraying pressure is 4MPa, the spraying distance is 30cm, and the nozzle diameter of the spray gun is 2mm.

[0046] (9) Place the sprayed coating in an oven for curing. The curing process is to keep it at room temperature for 30 hours, control the humidity at 50%, then raise the temperature to 120°C at 5°C / min and keep it at 120°C for 3 hours, raise the temperature to 200°C at 5°C / min and keep it at 200°C for 4 hours, and then cool it to room temperature with the oven.

[0047] (10) The cured coating was post-treated by heating it to 800°C at a heating rate of 10°C / min, holding it at that temperature for 5 hours, and then cooling it to room temperature in the furnace to obtain a band-selective emission coating.

[0048] The prepared band-selective emission coating showed an average emissivity of 0.25 in the 3-5 μm range and 0.74 in the 7-20 μm range, with a bonding strength of 2.1 MPa.

[0049] Example 3: A method for preparing a band-selective emission coating.

[0050] (1) Select particles with a diameter of 3 μm The powder was calcined at 1000℃ for 8 hours to obtain the calcined powder.

[0051] (2) The calcined powder was ball-milled and crushed. The ball mill speed was 300 r / min, the ball milling time was 25 h, the ball milling medium was ethanol, the mass ratio of powder to medium was 1:2, and the mass ratio of grinding balls to powder was 5:1.

[0052] (3) The ball-milled powder was subjected to rotary evaporation at a temperature of 83°C for 2 hours.

[0053] (4) The rotary evaporated powder is sieved to obtain powder with a particle size of 2 μm.

[0054] (5) Add the powder to deionized water to form a suspension. The mass ratio of powder to water is 1:4. Add 0.8% of the powder mass of polyvinylpyrrolidone to the suspension. Disperse the obtained liquid evenly by magnetic stirring. The stirring speed is 350 rpm and the stirring time is 4 h.

[0055] (6) Centrifuge the well-stirred adhesive solution at a speed of 2600 r / min for 4 min, remove the supernatant, dry it, and obtain the surface-modified powder.

[0056] (7) Add the modified powder at a mass fraction of 50%. The obtained adhesive solution was dispersed evenly by magnetic stirring at a speed of 350 rpm for 4 hours.

[0057] (8) The adhesive liquid is used as raw material for air spraying. The spraying pressure is 3MPa, the spraying distance is 26cm, and the nozzle diameter of the spray gun is 1mm.

[0058] (9) Place the sprayed coating in an oven for curing. The curing process is to keep it at room temperature for 26 hours, control the humidity at 40%, then raise the temperature to 100°C at 3°C / min and keep it at 100°C for 2 hours, raise the temperature to 180°C at 3°C / min and keep it at 180°C for 3 hours, and then cool it to room temperature with the oven.

[0059] (10) The cured coating was post-treated by heating it to 700°C at a heating rate of 7°C / min, holding it at that temperature for 4 hours, and then cooling it to room temperature in the furnace to obtain a band-selective emission coating.

[0060] The prepared band-selective emission coating showed an average emissivity of 0.23 in the 3-5 μm range and 0.74 in the 7-20 μm range, with a bonding strength of 2.2 MPa.

[0061] Although the present invention has been disclosed above with reference to embodiments, it is not intended to limit the present invention. Appropriate modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention should be covered within the protection scope of the present invention, which is defined by the claims.

Claims

1. A band-selective emission coating, characterized in that, A multiphase structure consisting of filler and matrix; the filler is an oxide. A is one of Ce, Ti, Zr, and Hf, with a submicron equiaxed crystalline structure and a particle size of 0.5~5μm; the matrix is... , 2.5≤x≤3.

2. The band-selective emission coating as described in claim 1, characterized in that, The filler accounts for 30% to 60% of the total mass of the band-selective emission coating; the thickness of the band-selective emission coating is 0.5 to 3 mm.

3. A method for preparing a band-selective emission coating, characterized in that, Includes the following steps: (1) Select particles with a diameter of 0.1~5μm. Powder, where A is one of Ce, Ti, Zr, and Hf, is calcined to obtain calcined powder; (2) The calcined powder is ball-milled and crushed; (3) The ball-milled powder is subjected to rotary evaporation; (4) The rotary evaporated powder is sieved to obtain powder with a particle size of 0.5~5μm; (5) Add the powder to deionized water to form a suspension, and add 0.5-1% of the powder mass of polyvinylpyrrolidone to it, and disperse the obtained adhesive solution evenly by magnetic stirring; (6) Centrifuge the well-stirred adhesive solution, remove the supernatant and dry it to obtain the surface-modified powder; (7) Add the modified powder at a mass fraction of 30%~60%. In the range of 2.5≤x≤3, the obtained adhesive solution is evenly dispersed by magnetic stirring; (8) Using the adhesive as a raw material for air spraying; (9) Place the sprayed coating in an oven to heat and cure, then cool to room temperature to obtain the cured layer; (10) The cured coating is heated and then cooled to room temperature to obtain a band-selective emission coating.

4. The method as described in claim 3, characterized in that, The calcination conditions in step (1) are: calcination at 800~1300℃ for 5~10h.

5. The method as described in claim 3, characterized in that, The ball milling conditions in step (2) are as follows: the ball mill speed is 200~400 r / min, the ball milling time is 20~30 h, the ball milling medium is ethanol, the mass ratio of powder to medium is 1:3~1:2, and the mass ratio of grinding balls to powder is 4:1~5:

1.

6. The method as described in claim 3, characterized in that, The conditions for rotary evaporation in step (3) are: rotary evaporation temperature of 80~85℃ and rotary evaporation time of 1~2h.

7. The method as described in claim 3, characterized in that, In step (5), the mass ratio of powder to water in the suspension is 1:3 to 1:4; the stirring conditions are: stirring speed of 300 to 400 rpm and stirring time of 3 to 5 h.

8. The method as described in claim 3, characterized in that, The centrifugation conditions in step (6) are: centrifugation speed of 2000~3000 r / min and centrifugation time of 3~5 min; The stirring conditions in step (7) are: stirring speed of 300~400 rpm and stirring time of 3~5 h; The spraying conditions in step (8) are: spraying pressure of 2~4MPa, spraying distance of 20~30cm, and spray gun nozzle diameter of 0.5~2mm.

9. The method as described in claim 3, characterized in that, In step (9), the curing conditions in the oven are as follows: first, keep the oven at room temperature for 20-30 hours and control the humidity at 30%-50%; then, raise the temperature to 80-120℃ at 2-5℃ / min and keep it at 1-3 hours; then raise the temperature to 160-200℃ at 2-5℃ / min and keep it at 2-4 hours.

10. The method as described in claim 3, characterized in that, The post-heating treatment conditions in step (10) are: heat to 600-800℃ at a heating rate of 5-10℃ / min and keep warm for 2-5 hours.

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