An ATO-coated silver powder composite, a preparation method thereof and an infrared stealth coating

Abstract

An ATO-coated silver powder composite material is provided, comprising ATO and silver powder. The ATO is coated on the surface of the silver powder in the form of a coating layer with a thickness of 3–5 nm. The silver powder is in flake form with a diameter of 6–20 μm and a thickness of 0.1 μm–0.2 μm. The mass ratio of ATO to silver powder ranges from (5:95) to (20:80). The diameter of the silver powder is 8–12 μm. The ATO powder is antimony-doped tin oxide, wherein the antimony doping content is 1–20% by mass. The composite material is obtained by stirring and mixing surface-treated silver powder with an ATO coating liquid. It has infrared emissivity, low optical gloss, and low reflectivity. As a low-emissivity filler, its application in infrared stealth coatings can effectively reduce the amount of optical pigments / dyes used, achieving compatibility with visible light stealth, resulting in an ultra-low emissivity coating compatible with optical-infrared camouflage.

Description

Technical Field

[0001] This invention relates generally to the field of camouflage and stealth materials technology, and specifically to an ATO-coated silver powder composite material and its preparation method, and an infrared stealth coating. Background Technology

[0002] In future information warfare, modern high-tech reconnaissance methods, characterized by multi-directional, deep-penetration, all-weather, wide-band, and high-resolution capabilities, play a crucial role in modern warfare. Modern reconnaissance technologies include optical observation, infrared reconnaissance, radar reconnaissance, and multi-band reconnaissance, among which infrared reconnaissance technology is one of the most widely used and effective. The rapid development of infrared reconnaissance technology has presented new threats to military targets, while infrared camouflage aims to alter or reduce the infrared or thermal radiation characteristics of a target, reducing the probability of detection by the enemy and thus improving the survivability of military targets.

[0003] Silver powder, as a functional, highly conductive filler, can form a continuous conductive network in film-forming materials, exhibiting excellent conductivity and infrared shielding properties. However, as a metallic powder, it possesses a distinct metallic luster and extremely high reflectivity in the visible, infrared, and radar bands. While this high reflectivity is beneficial for reducing the emissivity of the coating, it hinders the control of the visible light band. If applied to visible-infrared stealth coatings, large amounts of pigments or dyes need to be added to control the coating's color and spectrum. Furthermore, conductivity decreases and emissivity increases over time; therefore, its application in visible-infrared stealth coatings is significantly limited.

[0004] Antimony-doped tin oxide (ATO) semiconductor pigments are novel, multifunctional, transparent, antistatic, and conductive materials. Their conductivity lies between that of traditional semiconductors and metals, exhibiting low resistance, stable chemical properties, and high visible light transmittance and infrared reflectivity. Furthermore, ATO semiconductor pigments possess excellent weather resistance, resistance to strong acids, strong alkalis, and mechanical wear, making them a high-performance low-emissivity infrared material. However, the infrared emissivity of single ATO nanoparticles in the 8–14 μm wavelength range is only around 0.65–0.8, which is insufficient to meet the requirements for preparing low-emissivity coatings. Summary of the Invention

[0005] The technical problem to be solved by this invention is to address the shortcomings of the prior art by providing an ATO-coated silver powder composite material, its preparation method, and an infrared stealth coating based on the ATO-coated silver powder composite material. This invention uses ATO to coat silver powder, and its application in coating components yields an ultra-low emissivity coating compatible with both optical and infrared camouflage. Compared to single ATO semiconductor pigments, the ATO-coated silver powder composite material of this invention achieves a lower infrared emissivity, resulting in better infrared stealth performance. Compared to single silver powder fillers, it has advantages such as low gloss, low reflectivity, and stable chemical properties. Using it as a low-emissivity filler in infrared stealth coatings effectively reduces the amount of optical pigments / dyes used, achieving compatibility with visible light stealth, resulting in an ultra-low emissivity coating compatible with both optical and infrared camouflage. Furthermore, the preparation process is simple, environmentally friendly, and suitable for mass production.

[0006] The technical solution of the present invention is an ATO-coated silver powder composite material, wherein the composite material includes ATO and silver powder, wherein the ATO is coated on the surface of the silver powder in the form of a coating layer, and the thickness of the ATO coating layer is 3-5 nm; the silver powder is in flake form, with a diameter of 6-20 μm and a thickness of 0.1 μm-0.2 μm; and the mass ratio of ATO to silver powder is in the range of (5:95) to (20:80).

[0007] Furthermore, the diameter of the silver powder is 8-12 μm; the ATO powder is antimony-doped tin oxide, wherein the mass fraction of antimony doping content is 1-20%, preferably 1-15%.

[0008] This invention also provides a method for preparing the above-mentioned ATO-coated silver powder composite material, comprising the following steps:

[0009] S1. Surface treatment of silver powder: Weigh organic acid, add distilled water to dilute to obtain an organic acid solution with a mass fraction of 10-25%; then add 5-10% of thickener by mass of organic acid solution to adjust the solution viscosity to obtain a first mixed solution; weigh silver powder and add it to the above first mixed solution and mechanically stir to disperse it; take out the stirred and dispersed silver powder and wash it with distilled water and alcohol in sequence, filter it and set it aside;

[0010] S2, Preparation of ATO coating solution: Mix the coupling agent with an aqueous solution of ethanol, then add ATO powder and stir until homogeneous to form a second mixed solution; add ammonia solution dropwise to the second mixed solution to adjust the pH value to 10-12, and then let it stand;

[0011] S3. Preparation of ATO-coated silver powder composite material: Add the silver powder treated in step S1 to the solution obtained in step S2, stir at low speed, let stand, rinse with deionized water, filter and dry to obtain the ATO-coated silver powder composite material.

[0012] Furthermore, in step S1 above: the mass ratio of organic acid to silver powder is 1:5 to 1:20; the stirring and dispersion is carried out under constant temperature conditions of 40 to 60°C for 30 to 45 minutes; the thickener is one of polyvinylpyrrolidone, hydroxymethyl cellulose, and hydroxyethyl cellulose; the organic acid is one or more of oleic acid, acetic acid, butyric acid, and hexanoic acid.

[0013] Furthermore, in step S2 above: the aqueous solution of ethanol is prepared by mixing ethanol and distilled water at a mass ratio of 1:1; the mass ratio of ATO powder to the volume ratio of the aqueous solution of ethanol is 1:5 to 1:10.

[0014] The volume ratio of the coupling agent to the aqueous ethanol solution is 1:1 to 1:2; the concentration of the ammonia solution is 0.5 mol / L; the standing temperature is 30 to 40°C and the time is 5 min; the coupling agent is one or more of the following: silane coupling agent KH550, KH560, KH570, tetraethyl orthosilicate, and tetrabutyl titanate.

[0015] Furthermore, in step S3 above: the ratio of silver powder to ATO powder is calculated according to the mass ratio of silver powder raw material in step S1 and ATO powder in step S2 as (2.5~5):1; the stirring speed of low-speed stirring is 25~50 r / min, the stirring time is 30 min; the standing time is 6 h; and the drying temperature is 60℃.

[0016] The present invention also provides an infrared stealth coating, comprising the ATO-coated silver powder composite material, wherein the infrared stealth coating comprises the following raw material components by weight: film-forming substance: 30-35; ATO-coated silver powder composite material: 10-20; pigment paste: 0-30; thickener: 2.5-5; dispersant: 2-4; defoamer: 1.5-3; solvent: 20-30.

[0017] Furthermore, the film-forming substance in the infrared stealth coating is one of waterborne polyurethane resin, waterborne acrylic resin, and waterborne silicone-modified acrylic resin; the solvent is deionized water; and the pigment paste is one or more of titanium white paste, chrome green paste, cobalt blue paste, 192 red paste, medium chrome yellow paste, and aniline black paste.

[0018] Compared with the prior art, the present invention, employing the above technical solution, has the following technical effects:

[0019] 1. In the ATO-coated silver powder composite material provided by the present invention, the thickness of the ATO coating layer is only 3-5 nm, which has minimal impact on the dispersion performance, conductivity and emissivity of the silver powder, and can effectively reduce the gloss and spectral reflectivity of the silver powder surface; compared with single ATO semiconductor pigment, the composite material has lower emissivity, achieving better infrared stealth effect; compared with single silver powder filler, it has advantages such as low gloss, low reflectivity and stable chemical properties, and can be used as a low emissivity filler in infrared stealth coatings.

[0020] 2. In the preparation method of ATO-coated silver powder composite material of the present invention, after the silver powder is etched by an etching solution with a certain viscosity prepared by organic acid and thickener, the oxide substances on the surface of the silver powder can be effectively removed slowly and uniformly to form an activation layer, which greatly promotes the adsorption and bonding of ATO powder after coupling agent treatment, and forms a uniform coating layer with consistent thickness; the preparation method is simple and environmentally friendly.

[0021] 3. Using ATO-coated silver powder composite material as a component in infrared stealth coatings can effectively reduce the amount of pigments or dyes used, achieve compatibility with visible light stealth, and obtain an ultra-low emissivity coating that is compatible with optical-infrared camouflage. Attached Figure Description

[0022] These and / or other aspects and advantages of the present invention will become clearer and more readily understood from the following detailed description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:

[0023] Figure 1 Here is a SEM image of the silver powder raw material in an embodiment of the present invention;

[0024] Figure 2 This is a SEM image of the ATO / silver powder composite material-1 in Example 1 of the present invention;

[0025] Figure 3 This is a TEM image of the ATO / silver powder composite material-1 in Example 1 of the present invention;

[0026] Figure 4 The spectral reflectance curves of the silver powder raw material in this embodiment and the ATO / silver powder composite material-1 in Example 1 are shown below.

[0027] Figure 5 The images show visible light photographs and infrared effects of the NG2427 infrared ultra-low emissivity coating obtained in Example 1 of this invention. Detailed Implementation

[0028] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] Example 1

[0030] 1. A method for preparing ATO semiconductor pigment-coated Ag powder, comprising the following steps:

[0031] S1: Surface treatment of silver powder: Accurately weigh 10g of oleic acid reagent, add 90g of distilled water to dilute and obtain a 10% oleic acid solution by mass; then add 5% hydroxymethyl cellulose solution by mass of the oleic acid solution as a thickener to adjust the solution viscosity; accurately weigh 50g of flake silver powder with a diameter of 8-12μm (the same silver powder raw material was used in all examples and comparative examples) and add it to the above mixed solution for mechanical stirring and dispersion. React at a constant temperature of 50℃ for 30min to remove impurities and deoxidize the surface of the silver powder. Take out the treated silver powder and wash it twice with distilled water and once with alcohol, filter and set aside.

[0032] S2: Preparation of ATO-coated silver powder composite material: Ethanol and distilled water were mixed at a mass ratio of 1:1 to prepare 100 ml of ethanol aqueous solution. 100 ml of KH560 silane coupling agent was added at a volume ratio of 1:1 to the ethanol aqueous solution. Then, 10 g of ATO powder with an antimony doping content of 5% by mass was added, and the mixture was stirred until homogeneous to form a mixed solution. Ammonia solution with a concentration of 0.5 mol / L was added dropwise to the mixed solution to adjust the pH to 10. The solution was then allowed to stand at 30℃ for 5 min for hydrolysis. The surface-treated silver powder was then added to the mixed solution, stirred at low speed for 30 min, and allowed to stand for 6 h. The solution was then removed, rinsed with deionized water, filtered, and dried in a 60℃ oven to obtain ATO / silver powder composite material-1 with a coating thickness of 3 nm. The SEM image of the silver powder raw material is shown in Figure 1. The SEM and TEM images of the obtained ATO / silver powder composite material-1 are shown in Figure 2. Figure 2 and Figure 3 As shown, the relevant performance parameters of the material are shown in Table 1.

[0033] 2. An infrared ultra-low emissivity coating compatible with optical camouflage and its preparation method, comprising the following steps:

[0034] S1: Weigh out the waterborne polyurethane resin, deionized water, ATO / silver powder composite material-1, aniline black and cobalt blue paste (mass ratio of 20:5), thickener, dispersant and defoamer in the following proportions of 30:20:20:25:5:3.5:1.5 and set them aside separately for later use.

[0035] S2: Add the weighed components from step S1 to the container sequentially and disperse them at high speed. Grind and disperse at 1000 rpm for 2 hours. Adjust the viscosity to 20–25 s to obtain a gray-NG2427 infrared ultra-low emissivity coating compatible with optical camouflage. Spray the coating onto a tinplate to form a 25–30 μm thick layer. The color coordinates and emissivity of the coating are shown in Table 2. Visible light photographs and infrared effects of the coating are shown in Table 2. Figure 5 .

[0036] Example 2

[0037] 1. A method for preparing ATO semiconductor pigment-coated Ag powder, comprising the following steps:

[0038] S1: Surface treatment of silver powder: Accurately weigh 5g of acetic acid reagent, add 80g of distilled water to dilute and obtain an acetic acid solution with a mass fraction of 20%; then add 6% polyvinylpyrrolidone solution as a thickener to adjust the solution viscosity; accurately weigh 50g of flake silver powder with a particle size of 6-10μm and add it to the above mixed solution for mechanical stirring and dispersion, react at a constant temperature of 50℃ for 30min to remove impurities and deoxidize the surface of the silver powder, take out the treated silver powder and wash it twice with distilled water and once with alcohol, filter and set aside.

[0039] S2: Preparation of ATO-coated silver powder composite material: Ethanol and distilled water were mixed at a mass ratio of 1:1 to prepare 100 ml of ethanol aqueous solution. 100 ml of KH550 silane coupling agent was added at a volume ratio of 1:1 for the ethanol aqueous solution. Then, 10 g of ATO powder with an antimony doping content of 1% by mass was added and stirred evenly to form a mixed solution. Ammonia solution with a concentration of 0.5 mol / L was added dropwise to the mixed solution to adjust the pH value to 10. The solution was then allowed to stand at 30℃ for 5 min for hydrolysis. The surface-treated silver powder was then added to the mixed solution and stirred at low speed for 30 min. After standing for 6 h, the solution was removed, rinsed with deionized water, filtered, and dried in a 60℃ oven to obtain ATO / silver powder composite material-2. The thickness of the coating layer in the material was 3 nm. The relevant performance parameters of the material are shown in Table 1.

[0040] 2. An infrared ultra-low emissivity coating compatible with optical camouflage and its preparation method, comprising the following steps:

[0041] S1: Weigh out waterborne epoxy resin, deionized water, ATO-coated silver powder composite material-2, various color pastes (192 red paste, medium chromium yellow paste and titanium white paste, in a mass ratio of 35:20:20:20:2.5:2:2, and set aside separately for later use.

[0042] S2: Add the components weighed in step S1 to the container in sequence, disperse them at high speed, and grind and disperse them at high speed at 800 rpm for 2 hours; adjust the viscosity to 20-25 s to obtain a sand-colored-SE2335 infrared ultra-low emissivity coating compatible with optical camouflage. Spray the coating onto a tinplate to form a 25-30 μm thick coating. The color coordinates and emissivity of the coating are shown in Table 2.

[0043] Example 3

[0044] 1. A method for preparing ATO semiconductor pigment-coated Ag powder, comprising the following steps:

[0045] S1: Surface treatment of silver powder: Accurately weigh 10g of acetic acid reagent, add 80g of distilled water to dilute and obtain a 20% acetic acid solution; then add 6% polyvinylpyrrolidone solution of the acetic acid solution as a thickener to adjust the solution viscosity. Accurately weigh 50g of flake silver powder with a particle size of 8-12μm and add it to the above mixed solution for mechanical stirring and dispersion. React at a constant temperature of 50℃ for 30min to remove impurities and deoxidize the surface of the silver powder. Take out the treated silver powder and wash it twice with distilled water and once with alcohol, filter and set aside.

[0046] S2: Preparation of ATO-coated silver powder composite material: Ethanol and distilled water were mixed at a mass ratio of 1:1 to prepare 100 ml of ethanol aqueous solution. 150 ml of tetrabutyl titanate coupling agent was added at a volume ratio of 1:1.5 to the ethanol aqueous solution. Then, 10 g of ATO powder with an antimony doping content of 10% by mass was added and stirred evenly to form a mixed solution. Ammonia solution with a concentration of 0.5 mol / L was added dropwise to the mixed solution to adjust the pH value to 10. Then, the solution was allowed to stand at 30℃ for 5 min for hydrolysis. The surface-treated silver powder was then added to the mixed solution, stirred at low speed for 30 min, and allowed to stand for 6 h. The solution was then removed, rinsed with deionized water, filtered, and dried in a 60℃ oven to obtain ATO-coated silver powder composite material-3. The thickness of the coating layer in the material is 4 nm. The relevant performance parameters of the material are shown in Table 1.

[0047] 2. An infrared ultra-low emissivity coating compatible with optical camouflage and its preparation method, comprising the following steps:

[0048] S1 is prepared by weighing waterborne epoxy resin, ATO / silver powder composite material, deionized water, various color pastes (chrome green paste, 192 red paste, medium chrome yellow paste and aniline black paste, with a mass ratio of 7.5:2.5:13:2), thickener, dispersant, defoamer and deionized water in a mass ratio of 35:25:20:25:2.5:2.5:2. These are set aside separately for later use.

[0049] S2. Add the components weighed in step S1 to the container in sequence, disperse them at high speed, and grind and disperse them at high speed at 1000 rpm for 2 hours; adjust the viscosity to 20-25 s to obtain a medium green-MG1151 infrared ultra-low emissivity coating compatible with optical camouflage. Spray the coating onto a tinplate to form a 25-30 μm thick coating. The color coordinates and emissivity of the coating are shown in Table 2.

[0050] Table 1. Relevant performance parameters of silver powder and ATO-coated silver powder composite materials obtained in each embodiment.

[0051]

[0052] Table 2. Color coordinates and emissivity of the low emissivity visible-infrared stealth coatings obtained in each embodiment.

[0053]

[0054] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing an ATO-coated silver powder composite, characterized in that, It comprises the following steps: S1, surface treatment of silver powder: take organic acid, add distilled water to dilute to obtain an organic acid solution with a mass fraction of 10-25%; then add a thickening agent with a mass of 5-10% of the organic acid solution to adjust the viscosity of the solution to obtain a first mixed solution; take silver powder and add it to the first mixed solution, mechanically stir and disperse, the mass ratio of organic acid to silver powder is 1:5-1:20, take out the stirred and dispersed silver powder, wash it with distilled water and alcohol in turn, filter and reserve; The stirring and dispersing is carried out under constant temperature conditions of 40-60℃, and the time is 30-45 min; The thickening agent is one of polyvinylpyrrolidone, hydroxymethyl cellulose and hydroxyethyl cellulose; The organic acid is one or more of oleic acid, acetic acid, butyric acid and hexanoic acid; S2, preparation of ATO coating solution: mix a coupling agent with an aqueous ethanol solution, then add ATO powder and stir uniformly to form a second mixed solution; add ammonia solution drop by drop to the second mixed solution to adjust the pH value to 10-12, then stand still; The ATO powder is antimony-doped tin oxide, wherein the mass fraction of the doping content of antimony is 1-20%; The aqueous ethanol solution is prepared by mixing ethanol and distilled water in a mass ratio of 1:1; The mass of the ATO powder to the volume of the aqueous ethanol solution is 1:5-1:10; The volume ratio of the coupling agent to the aqueous ethanol solution is 1:1-1:2, and the concentration of the ammonia water is 0.5 mol / L; The standing temperature is 30-40℃, and the time is 5 min; The coupling agent is one or more of silane coupling agents KH550, KH560, KH570, tetraethyl orthosilicate and tetrabutyl titanate; S3, preparation of ATO-coated silver powder composite material: add the silver powder treated in step S1 to the solution obtained in step S2, the mass ratio of silver powder to ATO powder is (2.5-5):1 according to the mass ratio of the silver powder raw material in step S1 to the ATO powder in step S2, stir at low speed, stand still, take out, the stirring speed is 25-50 r / min, the stirring time is 30 min, and the standing time is 6 h; Rinse with deionized water, filter and dry, the drying temperature is 60℃, to obtain an ATO-coated silver powder composite material, which comprises ATO and silver powder, the ATO is in the form of a coating layer on the surface of the silver powder, the thickness of the ATO coating layer is 3-5 nm, the silver powder is in the form of a sheet, the diameter is 6-20 μm, and the thickness is 0.1 μm-0.2 μm, and the mass ratio of ATO to silver powder is (5:95)-(20:80).

2. The method for preparing an ATO-coated silver powder composite material according to claim 1, characterized in that, The mass fraction of the doping content of antimony in the ATO powder in S2 is 1-15%.

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