Low-thermal-conductivity, high-emissivity infrared radiation coating, and preparation method and coating thereof

Abstract

The present application relates to the technical field of paint, especially to a kind of low thermal conductivity, high emissivity infrared radiation paint and its preparation method and coating.The paint includes the following mass parts of raw materials: deionized water 40-60 parts, modified lanthanum zirconate powder 25-45 parts, chromium oxide powder 2.5-7.5 parts, lanthanum oxide powder 2.5-7.5, thickening agent 2-4 parts, dispersing agent 0.3-0.7 parts, defoaming agent 0.1-0.3 parts, curing agent 0.2-0.5 parts, film-forming aid 0.5-2 parts;The preparation method of the paint is to add thickening agent to deionized water according to the proportion, stir to get a uniform viscous slurry liquid, add dispersing agent, defoaming agent, curing agent, film-forming aid, modified lanthanum zirconate powder, chromium oxide powder and lanthanum oxide powder to the liquid in turn, stir and disperse, to get infrared radiation paint.The present application has the advantages of low thermal conductivity and high emissivity at the same time, with high infrared emissivity in 0.8-25 μm wave band, and good heat exchange effect.

Description

Technical Field

[0001] This invention relates to the field of coating technology, and in particular to a low thermal conductivity, high emissivity infrared radiation coating, its preparation method, and the coating itself. Background Technology

[0002] In modern industry, the thermal insulation and thermal radiation performance of high-temperature equipment such as thermal equipment (e.g., industrial kilns) have a crucial impact on energy efficiency and equipment lifespan. While traditional thermal insulation coatings can meet insulation requirements to some extent, they are insufficient in terms of thermal radiation performance, especially in the infrared band, resulting in low heat exchange efficiency and making it difficult to achieve high-efficiency energy-saving effects.

[0003] Therefore, developing an infrared radiation coating with low thermal conductivity and high emissivity, and its preparation method, can not only effectively solve the problems existing in the current technology, but also meet the industrial demand for efficient heat insulation and thermal radiation performance, which has important practical significance and broad application prospects. In the existing technology, several techniques have been used to solve the problem of low thermal conductivity and high emissivity coatings. For example, Chinese Patent CN 118146660 A describes a functional high-temperature thermal protection coating with intrinsically low thermal conductivity and high emissivity. From a high-entropy perspective, it designs a high-emissivity, low-thermal-conductivity material. However, the high-entropy strategy requires complex chemical compositions and manufacturing costs and difficulties, especially since phase precipitation is prone to occur during coating preparation, affecting the performance of the ceramic coating. Chinese Patent CN 110229007 A describes a high-emissivity thermal insulation coating, composed of a thermal insulation transition layer and a high-emissivity coating. However, the two-layer structure has complex processes, and the thickness of each layer is difficult to control precisely, affecting thermal insulation and radiation performance. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned shortcomings of the prior art by proposing a low thermal conductivity, high emissivity infrared radiation coating, its preparation method, and the coating itself.

[0005] The present invention discloses a low thermal conductivity and high emissivity infrared radiation coating comprising the following raw materials in parts by weight: 40-60 parts deionized water, 25-45 parts modified lanthanum zirconate powder, 2.5-7.5 parts chromium oxide powder, 2.5-7.5 parts lanthanum oxide powder, 2-4 parts thickener, 0.3-0.7 parts dispersant, 0.1-0.3 parts defoamer, 0.2-0.5 parts curing agent, and 0.5-2 parts film-forming aid;

[0006] The specific preparation process of modified lanthanum zirconate powder is as follows: Lanthanum zirconate powder is added to a mixed solvent of anhydrous ethanol and cyclohexane, then lanthanum source, magnesium source and aluminum source solutions are added and stirred, then a modification solution is added to obtain a white suspension; then ultrasonic treatment is performed, and aging is carried out to obtain a gel. The obtained gel is calcined at 600-1000℃ to obtain modified lanthanum zirconate powder.

[0007] The modified solution includes one or more of strontium nitrate, copper nitrate, manganese nitrate, and nickel nitrate.

[0008] Furthermore, the mass ratio of anhydrous ethanol to cyclohexane in the mixed solvent is 1:(0.1~0.5).

[0009] Furthermore, the concentration of the modified solution is 2-3 mol / L, and its volume ratio with the mixed solvent is 1:(200~1000).

[0010] Furthermore, the molar concentration of lanthanum in the lanthanum source solution is 2-3 mol / L, and the volume ratio of the lanthanum source solution to the mixed solvent is 1:(10~400).

[0011] Furthermore, the molar ratio of lanthanum, magnesium, and aluminum in the lanthanum source, magnesium source, and aluminum source solutions is 1:1:11.

[0012] Furthermore, the lanthanum source is one or more of lanthanum nitrate, lanthanum chloride, lanthanum acetate, and lanthanum sulfate; the magnesium source is one or more of magnesium nitrate, magnesium chloride, and magnesium sulfate; and the aluminum source is one or more of aluminum nitrate, aluminum chloride, and aluminum sulfate.

[0013] Furthermore, the dispersant is sodium tripolyphosphate; the thickener includes, but is not limited to, bentonite and Suzhou clay; the defoamer is polyether-modified silicone oil; and the curing agent is vinyltriamine.

[0014] A method for preparing a low thermal conductivity, high emissivity infrared radiation coating as described above involves adding a thickener to deionized water according to a specified ratio, stirring to obtain a uniform, viscous slurry-like liquid, and then sequentially adding a dispersant, defoamer, curing agent, film-forming aid, modified lanthanum zirconate powder, chromium oxide powder, and lanthanum oxide powder to the liquid, stirring and dispersing to obtain the infrared radiation coating.

[0015] A coating is prepared by applying the above-mentioned low thermal conductivity, high emissivity infrared radiation coating to the surface of a substrate, drying it for a period of time, and then heating it to 900-1600℃ and holding it at that temperature for 8-10 hours.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] (1) In this invention, low thermal conductivity lanthanum zirconate powder is modified by lanthanum, magnesium and aluminum sources, and then calcined to form La2Zr2O7@LaMgAl 11 O 19 The core-shell structure, along with the addition of a modified solvent (one or more of strontium nitrate, copper nitrate, manganese nitrate, and nickel nitrate), allows for in-situ modification of La₂Zr₂O₇@LaMgAl during calcination. 11 O19 LaMgAl on the surface 11 O 19 Doping is performed to form doped LaMgAl 11 O 19 This invention utilizes modified La2Zr2O7 powder as a filler to create an infrared radiation coating that combines low thermal conductivity with high emissivity. The coating exhibits high infrared emissivity in the 0.8–25 μm wavelength range, resulting in excellent thermal radiation and high heat exchange efficiency. Specifically, its thermal conductivity is 0.7–0.9 W / (m·K), its emissivity in the 0.75–2.5 μm range is 0.91–0.96, and its emissivity in the 2.5–25 μm range is greater than 0.95. This emissivity can be used for thermal insulation and improving heat exchange efficiency, thereby achieving energy savings.

[0018] (2) In the calcination modification of La2Zr2O7, the modifier can dope La2Zr2O7 to form a doped La2Zr2O7 intermediate layer. The doped La2Zr2O7 intermediate layer has extremely low intrinsic thermal conductivity, and the multilayer interface formed by the doped La2Zr2O7 intermediate layer, the La2Zr2O7 core, and the LaAlO3 shell can enhance phonon scattering and further reduce thermal conductivity. On the other hand, the present invention uses a mixed solvent of anhydrous ethanol and cyclohexane to adsorb organic groups on the surface of La2Zr2O7 particles. During the modification process, the solvent forms a water-in-oil (continuous phase is oil phase, dispersed phase is water phase) uniform dispersion system, so that a uniform LaMgAl layer is formed on the surface of La2Zr2O7 particles. 11 O 19 Shell, LaMgAl 11 O 19 The shell can be formed by the element La to form a diffusion layer. Both methods can enhance the bonding force between the interfaces, improve the bonding force and thermal stability of the core-shell interface, and improve the service life of the infrared radiation coating of the present invention.

[0019] (3) The coating of the present invention contains chromium oxide powder and lanthanum oxide powder, which react in situ during the heat treatment of the coating to form LaCrO3, which is uniformly dispersed between the modified La2Zr2O7 particles and forms a La element diffusion layer with the surface of the modified La2Zr2O7, generating a diffusion layer network structure, which enhances the bonding strength between the coating and the substrate; at the same time, LaCrO3 has good corrosion resistance and, as a corrosion-resistant reinforcing phase of the coating, can improve the stability of the coating's service performance.

[0020] (4) The low thermal conductivity and high emissivity infrared radiation coating prepared by the coating of the present invention has both heat insulation and radiative heat exchange functions. The production process is simple, requiring no complex component control and multi-layer coating design, and it is easy to achieve large-scale industrial production. The coating is suitable for thermal equipment, boilers and other equipment, and can play a role in energy saving and efficiency improvement. Attached Figure Description

[0021] Figure 1 A scanning electron microscope image of the modified lanthanum zirconate powder prepared in Example 1;

[0022] Figure 2 The image shown is a scanning electron microscope (SEM) image of the coating prepared in Example 2. Detailed Implementation

[0023] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0024] Example 1

[0025] Preparation of low thermal conductivity, high emissivity infrared radiation coating

[0026] Thickener was added to deionized water according to the specified ratio, and the mixture was stirred at high speed for 3 hours to obtain a homogeneous viscous slurry liquid. Dispersant, defoamer, film-forming aid, modified lanthanum zirconate powder, chromium oxide powder, and lanthanum oxide powder were added to the liquid in sequence, and the mixture was stirred at high speed to disperse the mixture, thereby obtaining an infrared radiation coating with modified lanthanum zirconate powder as filler. The infrared radiation coating with modified lanthanum zirconate powder as filler was coated onto the surface of the inner lining of an industrial kiln and dried for a period of time. Then, the temperature was raised to 1600℃ and held for 8 hours to prepare the coating.

[0027] The infrared radiation coating with modified lanthanum zirconate powder as filler comprises the following raw materials in parts by weight: 50 parts deionized water, 40 parts modified zirconium oxide powder, 7.5 parts chromium oxide powder and 7.5 parts lanthanum oxide powder, 4 parts thickener, 0.5 parts dispersant, 0.1 parts defoamer, 0.2 parts curing agent, and 0.3 parts film-forming aid.

[0028] The specific preparation process of modified lanthanum zirconate powder is as follows: Lanthanum zirconate powder is added to a mixed solvent of anhydrous ethanol and cyclohexane, then lanthanum source, magnesium source and aluminum source solution are added and stirred, then a modification solution is added to obtain a white suspension; then ultrasonic treatment is performed, and the suspension is aged for 12 hours to obtain a gel. The obtained gel is calcined at 900℃ to obtain modified lanthanum zirconate powder.

[0029] The mass ratio of anhydrous ethanol to cyclohexane in the mixed solvent is 1:0.2.

[0030] The modified solution is composed of strontium nitrate and manganese nitrate, with a concentration of 2 mol / L, a molar ratio of strontium to manganese of 1:1, and a volume ratio of the modified solution to the mixed solvent of 1:600.

[0031] The lanthanum source is lanthanum nitrate, the magnesium source is magnesium nitrate, and the aluminum source is aluminum nitrate. The molar ratio of lanthanum, magnesium, and aluminum is 1:1:11.

[0032] The concentration of the lanthanum source solution was 2 mol / L, and the volume ratio of the lanthanum source solution to the mixed solvent was 1:80.

[0033] The dispersant is sodium tripolyphosphate; the thickener is bentonite; the defoamer is polyether-modified silicone oil; and the curing agent is vinyltriamine.

[0034] The coating's thermal conductivity was measured to be 0.79 W / (m·K); at 1000℃, the emissivity was 0.94 for the 0.75~2.5μm region and 0.95 for the 2.5~25μm region; the coating's bonding strength was 10.2 MPa.

[0035] Figure 1 Here is a scanning electron microscope (SEM) image of the modified zirconium oxide powder prepared in Example 1; from Figure 1 It can be seen that the modified zirconia powder has a core-shell structure.

[0036] Example 2

[0037] Preparation of low thermal conductivity, high emissivity infrared radiation coating

[0038] Thickener was added to deionized water according to the specified ratio, and the mixture was stirred at high speed for 3 hours to obtain a homogeneous viscous slurry liquid. Dispersant, defoamer, film-forming aid, modified lanthanum zirconate powder, chromium oxide powder, and lanthanum oxide powder were added to the liquid in sequence, and the mixture was stirred at high speed to disperse the mixture, thereby obtaining an infrared radiation coating with modified lanthanum zirconate powder as filler. The infrared radiation coating with modified lanthanum zirconate powder as filler was coated onto the surface of the inner lining of an industrial kiln and dried for a period of time. Then, the temperature was raised to 1500℃ and held for 8 hours to prepare the coating.

[0039] The infrared radiation coating with modified zirconia powder as filler comprises the following raw materials in parts by weight: 45 parts deionized water, 45 parts modified lanthanum zirconate powder, 2.5 parts chromium oxide powder and 2.5 parts lanthanum oxide powder, 3 parts thickener, 0.5 parts dispersant, 0.1 parts defoamer, 0.2 parts curing agent, and 1.3 parts film-forming aid.

[0040] The specific preparation process of the modified lanthanum zirconate powder is as follows: Zirconia powder is added to a mixed solvent of anhydrous ethanol and cyclohexane, then lanthanum source, magnesium source and aluminum source solution are added and stirred, then a modification solution is added to obtain a white suspension; then ultrasonic treatment is performed, and the suspension is aged for 12 hours to obtain a gel. The obtained gel is calcined at 900℃ to obtain modified lanthanum zirconate powder.

[0041] The mass ratio of anhydrous ethanol to cyclohexane in the mixed solvent is 1:0.4.

[0042] The modified solution is strontium nitrate with a concentration of 2 mol / L, and the volume ratio of the modified solution to the mixed solvent is 1:800.

[0043] The lanthanum source is lanthanum nitrate, the magnesium source is magnesium nitrate, and the aluminum source is aluminum nitrate. The molar ratio of lanthanum, magnesium, and aluminum is 1:1:11.

[0044] The volume ratio of the lanthanum source solution to the mixed solvent is 1:80.

[0045] The dispersant is sodium tripolyphosphate; the thickener is bentonite; the defoamer is polyether-modified silicone oil; and the curing agent is vinyltriamine.

[0046] The coating's thermal conductivity was measured to be 0.9 W / (m·K). At 1000℃, the emissivity was 0.92 for the 0.75–2.5 μm region and 0.96 for the 2.5–25 μm region. The coating's adhesion strength was 9.5 MPa.

[0047] Figure 2 The image shows a scanning electron microscope (SEM) image of the coating prepared in Example 2. Figure 2 It can be seen that the coating structure is dense and the coating is well bonded to the substrate.

[0048] Example 3

[0049] Preparation of low thermal conductivity, high emissivity infrared radiation coating

[0050] Thickener was added to deionized water according to the specified ratio, and the mixture was stirred at high speed for 3 hours to obtain a homogeneous viscous slurry liquid. Dispersant, defoamer, film-forming aid, modified lanthanum zirconate powder, chromium oxide powder, and lanthanum oxide powder were added to the liquid in sequence, and the mixture was stirred at high speed to disperse the mixture, thereby obtaining an infrared radiation coating with modified lanthanum zirconate powder as filler. The infrared radiation coating with modified lanthanum zirconate powder as filler was coated onto the surface of the inner lining of an industrial kiln and dried for a period of time. Then, the temperature was raised to 1500℃ and held for 8 hours to prepare the coating.

[0051] The infrared radiation coating with modified zirconia powder as filler comprises the following raw materials in parts by weight: 45 parts deionized water, 40 parts modified lanthanum zirconate powder, 5 parts chromium oxide powder and 5 parts lanthanum oxide powder, 3 parts thickener, 0.5 parts dispersant, 0.1 parts defoamer, 0.2 parts curing agent, and 1.2 parts film-forming aid.

[0052] The specific preparation process of the modified lanthanum zirconate powder is as follows: Zirconia powder is added to a mixed solvent of anhydrous ethanol and cyclohexane, then lanthanum source, magnesium source and aluminum source solution are added and stirred, then a modification solution is added to obtain a white suspension; then ultrasonic treatment is performed, and the suspension is aged for 12 hours to obtain a gel. The obtained gel is calcined at 900℃ to obtain modified lanthanum zirconate powder.

[0053] The mass ratio of anhydrous ethanol to cyclohexane in the mixed solvent is 1:0.1.

[0054] The modified solution consists of strontium nitrate, copper nitrate, and nickel nitrate, with a concentration of 2 mol / L. The molar ratio of strontium, copper, and nickel is 1:1:1, and the volume ratio of the modified solution to the mixed solvent is 1:500.

[0055] The lanthanum source is lanthanum nitrate, the magnesium source is magnesium nitrate, and the aluminum source is aluminum nitrate. The molar ratio of lanthanum, magnesium, and aluminum is 1:1:11.

[0056] The volume ratio of the lanthanum source solution to the mixed solvent is 1:80.

[0057] The dispersant is sodium tripolyphosphate; the thickener is bentonite; the defoamer is polyether-modified silicone oil; and the curing agent is vinyltriamine.

[0058] The coating's thermal conductivity was measured to be 0.85 W / (m·K); at 1000℃, the emissivity was 0.95 for the 0.75~2.5μm region and 0.96 for the 2.5~25μm region; the coating's bonding strength was 12.6 MPa.

[0059] Comparative Example 1

[0060] Without adding modified lanthanum zirconate powder, the coating was prepared in the same manner as in Example 1.

[0061] The coating's thermal conductivity was measured to be 2.8 W / (m·K); at 1000℃, the emissivity was 0.88 for the 0.75~2.5μm region and 0.93 for the 2.5~25μm region; the coating's bonding strength was 8.2 MPa.

[0062] Comparative Example 2

[0063] Without adding chromium oxide powder, the coating was prepared in the same manner as in Example 1.

[0064] The coating's thermal conductivity was measured to be 0.92 W / (m·K); at 1000℃, the emissivity was 0.92 for the 0.75~2.5μm region and 0.95 for the 2.5~25μm region; the coating's bonding strength was 7.2 MPa.

[0065] For any points not covered above, existing technologies shall apply.

[0066] Although specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them, without departing from the direction of the invention or exceeding the scope defined by the appended claims. Those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc., made to the above embodiments based on the technical essence of the present invention should be included within the protection scope of the present invention.

Claims

1. A low thermal conductivity, high emissivity infrared radiation coating, characterized in that, The raw materials include the following parts by weight: 40-60 parts deionized water, 25-45 parts modified lanthanum zirconate powder, 2.5-7.5 parts chromium oxide powder, 2.5-7.5 parts lanthanum oxide powder, 2-4 parts thickener, 0.3-0.7 parts dispersant, 0.1-0.3 parts defoamer, 0.2-0.5 parts curing agent, and 0.5-2 parts film-forming aid; The specific preparation process of modified lanthanum zirconate powder is as follows: Lanthanum zirconate powder is added to a mixed solvent of anhydrous ethanol and cyclohexane, then lanthanum source, magnesium source and aluminum source solutions are added and stirred, then a modification solution is added to obtain a white suspension; then ultrasonic treatment is performed, and aging is carried out to obtain a gel. The obtained gel is calcined at 600-1000℃ to obtain modified lanthanum zirconate powder. The modified solution includes one or more of strontium nitrate, copper nitrate, manganese nitrate, and nickel nitrate; The molar ratio of lanthanum, magnesium, and aluminum in the lanthanum source, magnesium source, and aluminum source solutions is 1:1:

11.

2. The low thermal conductivity, high emissivity infrared radiation coating as described in claim 1, characterized in that, In the mixed solvent, the mass ratio of anhydrous ethanol to cyclohexane is 1:(0.1~0.5).

3. The low thermal conductivity, high emissivity infrared radiation coating as described in claim 1, characterized in that, The concentration of the modified solution is 2-3 mol / L, and its volume ratio with the mixed solvent is 1:(200~1000).

4. The low thermal conductivity, high emissivity infrared radiation coating as described in claim 1, characterized in that, The molar concentration of lanthanum in the lanthanum source solution is 2-3 mol / L, and the volume ratio of the lanthanum source solution to the mixed solvent is 1:(10~400).

5. The low thermal conductivity, high emissivity infrared radiation coating as described in claim 1, characterized in that, The lanthanum source is one or more of lanthanum nitrate, lanthanum chloride, lanthanum acetate, and lanthanum sulfate; the magnesium source is one or more of magnesium nitrate, magnesium chloride, and magnesium sulfate; and the aluminum source is one or more of aluminum nitrate, aluminum chloride, and aluminum sulfate.

6. The low thermal conductivity, high emissivity infrared radiation coating as described in claim 1, characterized in that, The dispersant is sodium tripolyphosphate; the thickener includes one or two of bentonite and Suzhou clay; the defoamer is polyether-modified silicone oil; and the curing agent is vinyltriamine.

7. A method for preparing a low thermal conductivity, high emissivity infrared radiation coating as described in any one of claims 1-6, characterized in that, Thickener is added to deionized water according to the specified ratio, and the mixture is stirred to obtain a uniform viscous slurry liquid. Dispersant, defoamer, curing agent, film-forming aid, modified lanthanum zirconate powder, chromium oxide powder and lanthanum oxide powder are added to the liquid in sequence, and the mixture is stirred and dispersed to obtain the infrared radiation coating.

8. A coating, characterized in that; The low thermal conductivity, high emissivity infrared radiation coating as described in any one of claims 1-6 is applied to the surface of a substrate and dried for a period of time, and then heated to 900-1600°C and kept at that temperature for 8-10 hours to obtain the coating.

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