A tungsten trioxide coated magnetic metal absorbent, a preparation method and application thereof

Abstract

The application discloses a tungsten trioxide coated magnetic metal absorber and a preparation method and application thereof, and relates to the technical field of multi-spectrum compatible stealth materials. The method comprises the following steps: uniformly dispersing tungsten salt and a magnetic metal absorber in an aqueous solvent to obtain a dispersion liquid; heating the dispersion liquid in a water bath to 60-90 DEG C, adjusting the pH of the dispersion liquid to 1-3, and performing a reaction to obtain a pre-product; and treating the pre-product at 400-600 DEG C for 1-2 hours to obtain the tungsten trioxide coated magnetic metal absorber. The prepared absorber is powered, the tungsten trioxide coated on the outer layer is changed from colorless to blue, and the effect of compatible sky blue visible light stealth and radar stealth is realized.

Description

Technical Field

[0001] This invention relates to the field of multi-spectral compatible stealth materials technology, specifically to an absorber of magnetic metal coated with tungsten trioxide, its preparation method, and its application. Background Technology

[0002] With the continuous development of technology, single stealth technologies are no longer sufficient to meet modern stealth requirements. Visible light imaging guidance systems are becoming increasingly capable of detecting, tracking, and intercepting targets. The threats to target stealth are becoming more and more serious. Therefore, a new visible light stealth material that is compatible with radar absorption is needed.

[0003] Existing technologies disclose a stealth material system and its preparation method. Through the matching design of a structural absorbing layer and a camouflage net, a broadband radar-visible light stealth material is prepared. However, the camouflage net is easily physically damaged during aircraft flight, which can drastically reduce its optical stealth performance. Existing technologies also disclose a high-temperature resistant radar-infrared compatible stealth coating and its preparation method. This high-temperature resistant radar-infrared compatible stealth coating has a layered structure, comprising, from the inside out, a metal bonding layer, a ceramic absorbing layer, a patch resistive high-temperature periodic structure layer, a ceramic insulating layer, and an infrared low-emissivity frequency-selective surface layer. Its surface layer uses the noble metal Pt as filler or a Pt metal layer as the infrared low-emissivity layer, resulting in high cost. Summary of the Invention

[0004] To address the shortcomings of the aforementioned background technology, this invention addresses the problem that existing broadband optical stealth materials are susceptible to physical damage, leading to a sharp decline in their optical stealth performance. This invention provides a tungsten trioxide-coated magnetic metal absorber compatible with both visible light and radar stealth, along with its preparation method and applications. The method involves dispersing magnetic metal absorber powder in a solution containing tungsten salt, adjusting the pH of the dispersion to allow tungsten ions to precipitate on the surface of the magnetic metal absorber, followed by heat treatment to convert it into tungsten trioxide, resulting in a tungsten trioxide-coated magnetic metal absorber. Tungsten trioxide is an electrochromic material; when an electric current is applied, electrons enter the tungsten trioxide lattice, altering its redox state and changing its band structure, thereby changing its light absorption and reflection characteristics, and its color changes from colorless to blue. The tungsten trioxide-coated magnetic metal absorber, under the influence of an electric current, changes the color of the outer tungsten trioxide coating from colorless to blue, thus achieving a sky-blue visible light stealth effect compatible with radar stealth.

[0005] The first objective of this invention is to provide a method for preparing a tungsten trioxide-coated magnetic metal absorbent, comprising the following steps:

[0006] Tungsten salt and magnetic metal absorbent are uniformly dispersed in an aqueous solvent to obtain a dispersion.

[0007] The dispersion was heated in a water bath to 60–90°C, and the pH of the dispersion was adjusted to 1–3 to carry out the reaction, thereby obtaining the preproduct.

[0008] The preproduct is treated at 400-600℃ for 1-2 hours to obtain tungsten trioxide-coated magnetic metal absorber.

[0009] Preferably, the mass ratio of the tungsten salt to the magnetic metal absorbent is (1-5):(2-50).

[0010] Preferably, the magnetic metal absorber includes one or more of the following: iron-silicon-aluminum powder, iron-silicon-chromium powder, iron-nickel powder, iron-nickel-molybdenum powder, and carbonyl iron powder.

[0011] Preferably, the tungsten salt includes one or more of sodium tungstate, potassium tungstate, and ammonium tungstate.

[0012] Preferably, the pH of the dispersion is adjusted using dilute hydrochloric acid with a mass fraction of 1% to 10% or dilute sulfuric acid with a mass fraction of 1% to 10%.

[0013] The second objective of this invention is to provide an absorbent for magnetic metals coated with tungsten trioxide.

[0014] The third objective of this invention is to provide an absorbent of tungsten trioxide-coated magnetic metal for electromagnetic absorption.

[0015] The fourth objective of this invention is to provide a microwave absorbing coating comprising a magnetic metal absorber coated with tungsten trioxide; the microwave absorbing coating uses a resin as a matrix.

[0016] Preferably, the resin is one or more selected from epoxy resin, polyurethane resin, silicone resin, acrylic resin, and alkyd resin.

[0017] The fifth objective of this invention is to provide a method for preparing a microwave absorbing coating, comprising the following steps:

[0018] The resin and diluent are mixed, and after the resin solution is evenly dispersed, tungsten trioxide-coated magnetic metal absorber is added. The mixture is then ground in a grinder to obtain a microwave absorbing coating.

[0019] The microwave absorbing coating is sprayed onto the surface of the substrate and cured in an oven to obtain the microwave absorbing coating.

[0020] The mass ratio of resin, diluent, and tungsten trioxide-coated magnetic metal absorber is (10-70):(10-100):(30-90).

[0021] The diluent is xylene, acetone, or tetrahydrofuran;

[0022] The curing temperature is 80~300℃, and the curing time is 1~24h.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] This invention provides a tungsten trioxide-coated magnetic metal absorbent, its preparation method, and its application. The method involves dispersing magnetic metal absorbent powder in a solution containing tungsten salt, adjusting the pH of the dispersion to allow tungsten ions to precipitate on the surface of the magnetic metal absorbent, and then heat-treating it to convert it into tungsten trioxide, thus obtaining a tungsten trioxide-coated magnetic metal absorbent. When an electric current is applied, the tungsten trioxide coating on the outer layer changes from colorless to blue, thereby achieving the effect of sky-blue visible light stealth and radar stealth compatibility. Attached Figure Description

[0025] Figure 1 The images show SEM images of iron-silicon-chromium powder (a) and tungsten trioxide-coated iron-silicon-chromium powder (b) from Example 1.

[0026] Figure 2 The images show SEM images of iron-silicon-aluminum powder (a) and tungsten trioxide-coated iron-silicon-aluminum powder (b) from Example 2.

[0027] Figure 3 SEM images of iron-nickel powder (a) and tungsten trioxide-coated iron-nickel powder (b) from Example 3.

[0028] Figure 4 The graphs show the real part (a), imaginary part (b), real part (c), and imaginary part (d) of the dielectric constant of the iron-silicon-chromium powder and the tungsten trioxide-coated iron-silicon-chromium powder in Example 1.

[0029] Figure 5 The graphs show the real part (a), imaginary part (b), real part (c), and imaginary part (d) of the dielectric constant of iron-silicon-aluminum powder and tungsten trioxide-coated iron-silicon-aluminum powder in Example 2.

[0030] Figure 6 The graphs show the real part (a), imaginary part (b), real part (c), and imaginary part (d) of the dielectric constant of the iron-nickel powder and the tungsten trioxide-coated iron-nickel powder in Example 3.

[0031] Figure 7 The coating (a) prepared using tungsten trioxide-coated iron-silicon-chromium powder as the absorbent in Example 1 and the coating (b) prepared using tungsten trioxide-coated iron-silicon-chromium powder as the absorbent under energized conditions are shown.

[0032] Figure 8 The coating (a) prepared using tungsten trioxide-coated iron-silicon-aluminum powder as the absorbent in Example 2 and the coating (b) prepared using tungsten trioxide-coated iron-silicon-aluminum powder as the absorbent under energized conditions are shown.

[0033] Figure 9The coating (a) prepared using tungsten trioxide-coated iron-nickel powder as the absorbent in Example 3 and the coating (b) prepared using tungsten trioxide-coated iron-nickel powder as the absorbent under energized conditions are shown. Detailed Implementation

[0034] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below in conjunction with specific embodiments and accompanying drawings. However, the embodiments described are not intended to limit the present invention.

[0035] The purpose of this invention is to provide a tungsten trioxide-coated magnetic metal absorber, its preparation method, and its application. This absorber, when energized, can achieve the effect of sky-blue visible light stealth and radar stealth compatibility.

[0036] To achieve the above objectives, the first aspect of the present invention provides a method for preparing a tungsten trioxide-coated magnetic metal absorbent, comprising the following steps:

[0037] Tungsten salt and magnetic metal absorbent are uniformly dispersed in an aqueous solvent to obtain a dispersion.

[0038] The dispersion was heated in a water bath to 60–90°C, and the pH of the dispersion was adjusted to 1–3 to carry out the reaction, thereby obtaining the preproduct.

[0039] The preproduct is treated at 400-600℃ for 1-2 hours to obtain tungsten trioxide-coated magnetic metal absorber.

[0040] This invention disperses magnetic metal absorber powder in a solution containing tungsten salt, adjusts the pH of the dispersion to allow tungsten ions to precipitate on the surface of the magnetic metal absorber, and then heat-treats it to convert it into tungsten trioxide, resulting in a tungsten trioxide-coated magnetic metal absorber. When an electric current is applied, the tungsten trioxide coating on the outer layer changes from colorless to blue, thus achieving the effect of sky-blue visible light stealth and radar stealth compatibility.

[0041] The mass ratio of the tungsten salt to the magnetic metal absorbent is (1-5):(2-50).

[0042] The magnetic metal absorbent includes one or more of the following: iron-silicon-aluminum powder, iron-silicon-chromium powder, iron-nickel powder, iron-nickel-molybdenum powder, and carbonyl iron powder.

[0043] The tungsten salt includes one or more of sodium tungstate, potassium tungstate, and ammonium tungstate.

[0044] The pH of the dispersion is adjusted using dilute hydrochloric acid or dilute sulfuric acid with a mass fraction of 1% to 10%.

[0045] An exemplary method for preparing a tungsten trioxide-coated magnetic metal absorber includes:

[0046] S1. Mix tungsten salt, magnetic metal absorbent, and deionized water to obtain a dispersion;

[0047] Specifically, tungsten salt is dissolved in deionized water, and a magnetic metal absorbent is added under ultrasonic dispersion to obtain a dispersion.

[0048] The mass ratio of tungsten salt, magnetic metal absorbent, and deionized water is (1-5):(2-50):(5-50). Maintaining this mass ratio within the specified range ensures successful coating of the magnetic metal absorbent with tungsten trioxide.

[0049] Tungsten salts include sodium tungstate, potassium tungstate, and ammonium tungstate. These tungsten salts serve as tungsten sources.

[0050] Magnetic metal absorbers include iron-silicon-aluminum powder, iron-silicon-chromium powder, iron-nickel powder, iron-nickel-molybdenum powder, carbonyl iron powder, etc. Using these magnetic metal absorbers ensures that the synthesized tungsten trioxide-coated magnetic metal absorber exhibits excellent microwave absorption performance.

[0051] S2. Under a water bath heating environment, adjust the pH of the dispersion and react for 24 hours to obtain the preproduct. Filter the preproduct and dry it under vacuum at 60°C.

[0052] The water bath heating temperature is between 60 and 90°C, which ensures that tungsten ions are stably deposited on the surface of the magnetic metal absorbent without precipitation or agglomeration.

[0053] The pH of the dispersion is adjusted using substances such as dilute hydrochloric acid and dilute sulfuric acid. Adjusting the pH with these acids allows tungsten ions to deposit on the surface of the magnetic metal absorber.

[0054] Adjusting the pH of the dispersion to between 1 and 3 can control the rate of tungsten ion deposition, preventing tungsten ions from being difficult to deposit or depositing too quickly, thus avoiding agglomeration.

[0055] S3. Heat-treat the dried pre-product for 1 hour, then grind it to obtain tungsten trioxide-coated magnetic metal absorber.

[0056] The heat treatment temperature is between 400℃ and 600℃. Heat treatment causes the tungstic acid coating the surface of the magnetic metal absorber to transform into tungsten trioxide.

[0057] A second aspect of the present invention provides an absorbent of magnetic metal coated with tungsten trioxide.

[0058] The third aspect of this invention provides the application of a tungsten trioxide-coated magnetic metal absorber in electromagnetic absorption.

[0059] A fourth aspect of the present invention provides a microwave absorbing coating comprising a magnetic metal absorber coated with tungsten trioxide; the microwave absorbing coating uses a resin as a matrix.

[0060] The resin is one or more of epoxy resin, polyurethane resin, silicone resin, acrylic resin, and alkyd resin.

[0061] The fifth aspect of this invention provides a method for preparing a microwave absorbing coating, comprising the following steps:

[0062] Q1. Mix the resin with the diluent. After the resin solution is evenly dispersed, add the tungsten trioxide-coated magnetic metal absorber and grind it in a grinder to obtain the microwave absorbing coating.

[0063] The mass ratio of resin, diluent, and tungsten trioxide-coated magnetic metal absorber is (10-70):(10-100):(30-90).

[0064] The grinding mill rotates at 40–80 r / min, and the grinding time is 2–4 h.

[0065] The diluent is xylene, acetone, or tetrahydrofuran.

[0066] Q2. Spray the microwave absorbing coating onto the surface of the substrate and cure it in an oven to obtain the microwave absorbing coating.

[0067] Specifically, the base material is tinplate, titanium alloy, etc.;

[0068] The coating thickness is 0.5mm to 2mm;

[0069] The curing temperature is 80~300℃, and the curing time is 1~24h. Specifically, when the resin is silicone resin, the curing temperature is 240℃ / 1h; when the resin is epoxy resin, the curing temperature is 80℃ / 24h; when the resin is polyamide resin, the curing temperature is 80℃ / 24h; when the resin is acrylic resin, the curing temperature is 80℃ / 24h; and when the resin is alkyd resin, the curing temperature is 120℃ / 24h.

[0070] It should be noted that, unless otherwise specified, the experimental methods used in this invention are all conventional methods; and the reagents and materials used, unless otherwise specified, are all commercially available.

[0071] Example 1

[0072] S1. Dissolve 3g of sodium tungstate in 15g of deionized water and stir thoroughly to ensure complete dissolution of the sodium tungstate. Then add 10g of iron-silicon-chromium powder to the sodium tungstate solution and stir thoroughly to obtain a dispersion.

[0073] S2. Place the dispersion in a water bath, adjust the temperature to 60℃, stir and keep warm for 20 min, then add dilute hydrochloric acid dropwise to adjust the pH of the dispersion to 2, react for 24 h to obtain the preproduct, filter the preproduct and vacuum dry at 60℃.

[0074] S3. Heat-treat the dried pre-product at 500℃ for 1 hour, then grind it to obtain tungsten trioxide-coated iron-silicon-chromium absorbent.

[0075] like Figure 1 The image shows SEM images of iron-silicon-chromium powder (a) and tungsten trioxide-coated iron-silicon-chromium powder (b). From... Figure 1 As can be seen in (a), the iron-silicon-chromium powder has a smooth surface and is evenly dispersed. Figure 1 In (b), tungsten trioxide successfully coated iron, silicon, and chromium powders, which agglomerated together and had a smooth surface.

[0076] like Figure 4 As shown, in the 8–12 GHz frequency band, compared with the uncoated iron-silicon-chromium absorber (FeSiCr), the dielectric constant and permeability of the tungsten trioxide-coated iron-silicon-chromium absorber (FeSiCr@WO3) change little, and the absorption performance is not damaged.

[0077] Q1. Mix 30g of silicone resin with 70g of xylene. After the silicone resin solution is evenly dispersed, add 70g of tungsten trioxide-coated iron-silicon-chromium absorber. Grind in a grinder at a speed of 60r / min for 2h to obtain a microwave absorbing coating.

[0078] Q2. Spray the microwave absorbing coating onto the surface of the tinplate, cure it in an oven at 240°C for 1 hour, and obtain the microwave absorbing coating with a coating thickness of 1.5 mm.

[0079] like Figure 7 As shown, a coating is prepared using tungsten trioxide-coated iron-silicon-chromium as an absorbent. Without electricity, it is as follows: Figure 7 As shown in (a), the coating is black because the iron-silicon-chromium absorbent is black; when the applied voltage is 15V, as... Figure 7 The coating shown in (b) turns dark blue and the color is uneven. This is because the tungsten trioxide coating is thin and the bottom layer is a black iron-silicon-chromium absorbent. The blue color is darker and the absorbent is unevenly distributed in the coating, resulting in uneven color of the coating when electricity is applied.

[0080] Example 2

[0081] S1. Dissolve 4g of potassium tungstate in 25g of deionized water and stir thoroughly to ensure complete dissolution of potassium tungstate. Then add 14g of iron-silicon-aluminum powder to the potassium tungstate solution and stir thoroughly to obtain a dispersion.

[0082] S2. Place the dispersion in a water bath, adjust the temperature to 60℃, stir and keep warm for 20 min, then add dilute hydrochloric acid dropwise to adjust the pH of the dispersion to 2, react for 24 h to obtain the preproduct, filter the preproduct and vacuum dry at 60℃.

[0083] S3. Heat-treat the dried pre-product at 500℃ for 1 hour, then grind it to obtain tungsten trioxide-coated iron-silicon-aluminum absorbent.

[0084] like Figure 2 The image shows SEM images of iron-silicon-aluminum powder (a) and tungsten trioxide-coated iron-silicon-aluminum powder (b). Figure 2 The iron-silicon-chromium powder in (a) is uniformly dispersed and has a smooth surface. Figure 2 (b) Tungsten trioxide coated iron-silicon-aluminum powder with a rough surface.

[0085] like Figure 5 As shown, in the 8–12 GHz frequency band, compared with the uncoated iron-silicon-aluminum absorber (FeSiAl@WO3), the dielectric constant and permeability of the tungsten trioxide-coated iron-silicon-aluminum absorber (FeSiAl@WO3) change little, and the absorption performance is not damaged.

[0086] Q1. Mix 30g of alkyd resin with 70g of xylene. After the alkyd resin solution is evenly dispersed, add 70g of tungsten trioxide-coated iron-silicon-aluminum absorbent. Grind in a grinder at a speed of 60r / min for 2h to obtain a microwave absorbing coating.

[0087] Q2. Spray the microwave absorbing coating onto the surface of the titanium alloy, cure it in an oven at 120°C for 24 hours, and obtain the microwave absorbing coating with a coating thickness of 1.5 mm.

[0088] like Figure 8 As shown, a coating is prepared using tungsten trioxide-coated iron-silicon-aluminum as an absorbent. Without electricity, it is as follows: Figure 8 As shown in (a), the coating is black because the iron-silicon-aluminum absorbent is silver-black; when the applied voltage is 15V, as Figure 8 The coating shown in (b) turns dark blue and the color is uneven. This is because the tungsten trioxide coating is thin and the bottom layer is a silver-black iron-silicon-aluminum absorbent, which is darker blue. In addition, the absorbent is unevenly distributed in the coating, resulting in uneven color of the coating when electricity is applied.

[0089] Example 3

[0090] S1. Dissolve 6g of potassium tungstate in 27g of deionized water and stir thoroughly to ensure complete dissolution of potassium tungstate. Then add 13g of iron-nickel powder to the potassium tungstate solution and stir thoroughly to obtain a dispersion.

[0091] S2. Place the dispersion in a water bath, adjust the temperature to 60℃, stir and keep warm for 20 min, then add dilute hydrochloric acid dropwise to adjust the pH of the dispersion to 2, react for 24 h to obtain the preproduct, filter the preproduct and vacuum dry at 60℃.

[0092] S3. Heat-treat the dried pre-product at 500℃ for 1 hour, then grind it to obtain tungsten trioxide-coated magnetic metal absorber.

[0093] like Figure 3 The image shows SEM images of iron-nickel powder (a) and tungsten trioxide-coated iron-nickel powder (b). From... Figure 3 (a) The iron-nickel powder is uniformly dispersed and has a smooth surface. Figure 3 In (b), tungsten trioxide-coated iron-nickel powder agglomerates together with a smooth surface.

[0094] like Figure 6 As shown, in the 8–12 GHz frequency band, compared with the uncoated iron-nickel absorber (FeNi), the dielectric constant and permeability of the tungsten trioxide-coated iron-nickel absorber (FeNi@WO3) change little, and the microwave absorption performance is not damaged.

[0095] Q1. Mix 30g of silicone resin with 70g of xylene. After the silicone resin solution is evenly dispersed, add 70g of tungsten trioxide-coated iron-nickel absorbent and grind in a grinder at a speed of 60r / min for 2h to obtain a microwave absorbing coating.

[0096] Q2. Spray the microwave absorbing coating onto the surface of the tinplate, cure it in an oven at 240°C for 1 hour, and obtain the microwave absorbing coating with a coating thickness of 1.5 mm.

[0097] like Figure 9 As shown, a coating is prepared using tungsten trioxide-coated iron-nickel as an absorbent. Without electricity, it is as follows: Figure 9 As shown in (a), the coating is black because the iron-nickel absorbent is grayish-black; when the applied voltage is 15V, as... Figure 9 The coating shown in (b) turns dark blue and the color is uneven. This is because the tungsten trioxide coating is thin and the bottom layer is a gray-black iron-nickel absorbent. The blue color is darker and the absorbent is unevenly distributed in the coating, resulting in uneven color of the coating when electricity is applied.

[0098] In summary, the present invention provides a tungsten trioxide-coated magnetic metal absorbent, its preparation method, and its application. The main process involves dispersing magnetic metal absorbent powder in a solution containing tungsten salt, adjusting the pH of the dispersion to allow tungsten ions to precipitate on the surface of the magnetic metal absorbent, and then heat-treating it to convert it into tungsten trioxide. This yields a tungsten trioxide-coated magnetic metal absorbent that can achieve sky-blue visible light stealth and radar stealth under electrical conditions.

[0099] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a microwave absorbing coating, characterized in that, Includes the following steps: S1. Dissolve 4g of potassium tungstate in 25g of deionized water and stir thoroughly to ensure complete dissolution of potassium tungstate. Then add 14g of iron-silicon-aluminum powder to the potassium tungstate solution and stir thoroughly to obtain a dispersion. S2. Place the dispersion in a water bath, adjust the temperature to 60℃, stir and keep warm for 20 min, then add dilute hydrochloric acid dropwise to adjust the pH of the dispersion to 2, react for 24 h to obtain the preproduct, filter the preproduct and vacuum dry at 60℃. S3. The dried pre-product was heat-treated at 500℃ for 1 hour, and then ground to obtain tungsten trioxide-coated iron-silicon-aluminum absorbent. Q1. Mix 30g of alkyd resin with 70g of xylene. After the alkyd resin solution is evenly dispersed, add 70g of tungsten trioxide-coated iron-silicon-aluminum absorbent. Grind in a grinder at a speed of 60r / min for 2h to obtain a microwave absorbing coating. Q2. Spray the microwave absorbing coating onto the surface of the titanium alloy, cure it in an oven at 120°C for 24 hours, and obtain the microwave absorbing coating with a coating thickness of 1.5 mm.

2. A method for preparing a microwave absorbing coating, characterized in that, Includes the following steps: S1. Dissolve 6g of potassium tungstate in 27g of deionized water and stir thoroughly to ensure complete dissolution of potassium tungstate. Then add 13g of iron-nickel powder to the potassium tungstate solution and stir thoroughly to obtain a dispersion. S2. Place the dispersion in a water bath, adjust the temperature to 60℃, stir and keep warm for 20 min, then add dilute hydrochloric acid dropwise to adjust the pH of the dispersion to 2, react for 24 h to obtain the preproduct, filter the preproduct and vacuum dry at 60℃. S3. The dried pre-product was heat-treated at 500℃ for 1 hour, and then ground to obtain tungsten trioxide-coated iron-nickel absorbent. Q1. Mix 30g of silicone resin with 70g of xylene. After the silicone resin solution is evenly dispersed, add 70g of tungsten trioxide-coated iron-nickel absorbent and grind in a grinder at a speed of 60r / min for 2h to obtain a microwave absorbing coating. Q2. Spray the microwave absorbing coating onto the surface of the tinplate, cure it in an oven at 240°C for 1 hour, and obtain the microwave absorbing coating with a coating thickness of 1.5 mm.

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