DYNAMIC THERMAL INFRARED STEALTH COMPOSITE MATERIAL BASED ON DUAL PHASE CHANGE AND PREPARATION METHOD THEREOF

Abstract

A dynamic thermal infrared stealth composite material based on dual phase change is a VO.sub.2/mica-based phase change thermal storage thin layer composite material composed of a VO.sub.2 nanoparticle coating and a mica-based phase change thermal storage thin layer, wherein the mica-based phase change thermal storage thin layer consists of stearic acid and a vanadium-extracted mica substrate in a mass ratio of 3-5:5-7. The composite material based on dual phase change is prepared by extracting vanadium from vanadium mica using a roasting and acid leaching process to prepare VO.sub.2 nanoparticles and a vanadium-extracted mica, embedding a phase change functional body into the vanadium-extracted mica as a support substrate to prepare a mica-based phase change thermal storage thin layer, and coating the VO.sub.2 nanoparticles on the mica-based phase change thermal storage thin layer. The dynamic thermal infrared stealth composite material can synergistically reinforce thermal infrared stealth performance.

Claims

1. A dynamic thermal infrared stealth composite material based on a dual phase change, comprising a VO.sub.2 nanoparticle coating and a mica-based phase change thermal storage thin layer, wherein the mica-based phase change thermal storage thin layer consists of stearic acid and a vanadium-extracted mica a mass ratio of 3-5:5-7.

2. The dynamic thermal infrared stealth composite material according to claim 1, wherein in the dynamic thermal infrared stealth composite material, the VO.sub.2 nanoparticle coating has a thickness of 0.1-0.5 mm.

3. The dynamic thermal infrared stealth composite material according to claim 1, wherein the dynamic thermal infrared stealth composite material based on dual phase change is produced by coating VO.sub.2 nanoparticles on the mica-based phase change thermal storage thin layer, wherein the dynamic thermal infrared stealth composite material simultaneously regulates and controls infrared emissivity and temperature, and the dynamic thermal infrared stealth composite material synergistically reinforces thermal infrared stealth performance.

4. A method for preparing the dynamic thermal infrared stealth composite material according to claim 1, comprising the following steps: step 1: preparing the mica-based phase change thermal storage thin layer by mixing the stearic acid and the vanadium-extracted mica in the mass ratio of 3-5:5-7 to obtain a mixture, placing the mixture in a reaction vessel with a vacuum device, ultrasonically heating the mixture at 80-95° C. under a vacuum condition for 25-30 min to obtain a mica-based phase change thermal storage composite material, and then pressing the mica-based phase change thermal storage composite material, to obtain the mica-based phase change thermal storage thin layer; and step 2: preparing a VO.sub.2/mica-based phase change thermal storage thin layer composite material by mixing a dispersing solvent and VO.sub.2 nanoparticles, and ultrasonically stirring to obtain a spin-coating solution with uniformly dispersed VO.sub.2 nanoparticles, spin coating the mica-based phase change thermal storage thin layer obtained in step 1 as a spin-coating substrate with the spin-coating solution, and drying at room temperature, to obtain the VO/mica-based phase change thermal storage thin layer composite material after multiple times of the spin coating.

5. The method according to claim 4, wherein the vanadium-extracted mica in step 1 and the VO.sub.2 nanoparticles in step 2 are prepared according to the following method: crushing a vanadium mica by ball milling to obtain a crushed vanadium mica, and then roasting the crushed vanadium mica in a microwave for 1 h at a predetermined high-temperature to obtain a roasted clinker; mixing sulfuric acid as a leaching solution and the roasted clinker at a liquid-solid ratio of 2-3:1 ml/g with stirring to obtain a mixed solution, leaching the mixed solution at a leaching temperature of 90-95° C. for 10-12 h to obtain a leached solution, and filtering the leached solution to obtain a vanadium-containing leachate and the vanadium-extracted mica; washing the vanadium-extracted mica and drying for use; and adjusting a pH of the vanadium-containing leachate to 2.0-2.5, and after oxidation, adsorption, desorption, and purification, adding an ammonium salt for precipitation to form ammonium metavanadate, filtering, washing, and drying the ammonium metavanadate; and adding a reducing agent to the ammonium metavanadate as a reaction raw material and stirring, and then reacting the ammonium metavanadate with the reducing agent at a reaction temperature of 180-200° C. for 12-48 h by using a hydrothermal method to obtain a primary product of VO.sub.2, and annealing the VO.sub.2 to obtain the VO.sub.2 nanoparticles.

6. The method according to claim 5, wherein the predetermined temperature is 800-900° C.

7. The method according to claim 5, wherein the reducing agent is at least one selected from the group consisting of oxalic acid, formic acid, ethanol, amines, and hydroquinone.

8. The method according to claim 5, wherein the annealing the VO.sub.2 to obtain the VO.sub.2 nanoparticles is carried out at an annealing temperature of 500-550° C. for 5-8 h.

9. The method according to claim 4, wherein in step 1, the pressing of the mica-based phase change thermal storage composite material is carried out at a pressing pressure of 10-16 MPa.

10. The method according to claim 4, wherein in step 2, the dispersing solvent is at least one selected from the group consisting of distilled water and ethanol.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] FIG. 1 is grayscale images of the products prepared in Example 1 and Comparative Example 1 obtained by infrared thermographic camera.

[0028] FIG. 2 is grayscale images of the products prepared in Example 2 and Comparative Example 1 obtained by infrared thermographic camera.

[0029] FIG. 3 is grayscale images of the products prepared in Example 3 and Comparative Example 1 obtained by infrared thermographic camera.

[0030] As can be seen from FIG. 1, in the infrared stealth performance test, the temperature of sample 1 prepared in Example 1 (T.sub.1=56.4° C.) is closer to the environmental temperature (T.sub.E=54.5° C.) than the temperature of sample 0 prepared in Comparative Example 1 (T.sub.0=63.3° C.), indicating that the prepared dual phase change material has a better ability of adjusting temperature and infrared emissivity, and can rapidly adapt to the environmental background temperature, and thus has better infrared stealth performance.

[0031] As can be seen from FIG. 2, in the infrared stealth performance test, the temperature of sample 2 prepared in Example 2 (T.sub.2=59.8° C.) is closer to the environmental temperature (T.sub.E=60.4° C.) than the temperature of sample 0 prepared in Comparative Example 1 (T.sub.0=67.4° C.), indicating that the prepared dual phase change material has a better ability of adjusting temperature and infrared emissivity, and can rapidly adapt to the environmental background temperature, and thus has better infrared stealth performance.

[0032] As can be seen from FIG. 3, in the infrared stealth performance test, the temperature of sample 3 prepared in Example 3 (T.sub.3=58. PC) is closer to the environmental temperature (T.sub.E=57.6° C.) than the temperature of sample 0 prepared in Comparative Example 1 (T.sub.0=64.2° C.), indicating that the prepared dual phase change material has a better ability of adjusting temperature and infrared emissivity, and can rapidly adapt to the environmental background temperature, and thus has better infrared stealth performance.

DETAILED DESCRIPTION

[0033] The present invention is further described in detail below with reference to specific examples, but it is not intended to merely limit the scope of the present invention to the following examples.

Example 1

[0034] 1 kg of a vanadium mica was crushed to a particle size at a millimeter scale by ball-milling, and then roasted in microwave for 1 h at a temperature of 850° C. to obtain a roasted clinker. Sulfuric acid as a leaching solution was mixed with the roasted clinker at a liquid-solid ratio of 2:1 ml/g with stirring, and reacted at a leaching temperature of 95° C. for 12 h, to obtain a vanadium-containing leachate and a vanadium-extracted mica. The vanadium-extracted mica was washed and dried for use. The pH of the leachate was adjusted to 2.0. Sodium chlorate was added for oxidation, and saturated resin was added for adsorption, desorption and purification. An ammonium salt was then added for precipitation to form ammonium metavanadate, and then filtered, washed, and dried. 0.8 ml/L of an oxalic acid reducing agent solution was added dropwise to the ammonium metavanadate and stirred for 10 min, and then reacted at a reaction temperature of 180° C. for 12 h by using a hydrothermal method, to obtain a primary product of vanadium dioxide (VO.sub.2), which was further annealed at 550° C. for 6 h to obtain the final VO.sub.2 nanoparticles.

[0035] Stearic acid and the vanadium-extracted mica were mixed in a mass ratio of 3:7, and then placed in an Erlenmeyer flask reaction vessel with a vacuum device. After evacuating to −0.05 MPa, the resulting mixture was ultrasonically heated at 80° C. for 25-30 min. Then, the evacuation was stopped, and air was allowed to return to the vessel. After cooling, a mica-based phase change thermal storage composite material was obtained. The phase change thermal storage composite material was further pressed in a mold with a diameter of 2 mm at a pressure of 10 MPa, to obtain a mica-based phase change thermal storage thin layer.

[0036] Ethanol as a dispersing solvent and the VO.sub.2 nanoparticles obtained above were mixed at a liquid-solid ratio of 100:5 ml/g and ultrasonically stirred for 30 min to obtain a spin-coating solution with uniformly dispersed VO.sub.2 nanoparticles. The spin-coating solution was spin-coated onto the mica-based phase change thermal storage thin layer as a spin-coating substrate at a rotating speed of 2000 r/min, and dried at room temperature for 3 h. After multiple times of spin coating, a VO.sub.2/mica-based phase change thermal storage thin layer composite material coated with a VO.sub.2 nanoparticle coating of about 0.2 mm was obtained, which was marked as sample 1.

[0037] According to the criterion for evaluating infrared stealth, the infrared stealth performance was tested by using an infrared thermographic camera Fluke Thermography TiS50 as follows. The dual phase change material obtained above (sample 1) and a pure phase change material (sample 0) in Comparative Example 1 were charged into a glass mold and placed on a rectangular heating plate at 68-73° C. for a period of time. As shown in the grayscale images of FIG. 1, when the plate temperature was T.sub.B=69.5° C., and the environmental temperature was T.sub.E=54.5° C., sample 1 (T.sub.1=56.4° C.) had a temperature closer to the environmental temperature than sample 0 (T.sub.01=63.3° C.), and had a lower infrared emissivity. Therefore, the prepared dual phase change material had a better ability of adjusting temperature and infrared emissivity, and can rapidly adapt to the environmental background temperature, and thus had better infrared stealth performance.

Example 2

[0038] According to the same method and conditions as those in Example 1, a mica-based phase change thermal storage composite material was prepared (except that the mass ratio of stearic acid to a vanadium-extracted mica was changed into 4:6) and a mica-based phase change thermal storage thin layer was then obtained; VO.sub.2 nanoparticles were spin-coated with the same number of spin coating, and finally, a VO.sub.2/mica-based phase change thermal storage thin layer composite material was obtained, which was marked as sample 2.

[0039] According to the criterion for evaluating infrared stealth, the infrared stealth performance was tested by using an infrared thermographic camera Fluke Thermography TiS50 as follows. The dual phase change material obtained above (sample 2) and a pure phase change material (sample 0) in Comparative Example 1 were charged into a glass mold and placed on a rectangular heating plate at 68-73° C. for a period of time. As shown in the grayscale images of FIG. 2, when the plate temperature was T.sub.B=72.9° C., and the environmental temperature was T.sub.E=60.4° C., sample 1 (T.sub.2=59.8° C.) had a temperature closer to the environmental temperature than sample 0 (T.sub.02=67.4° C.), and had a lower infrared emissivity. Therefore, the prepared dual phase change material had a better ability of adjusting temperature and infrared emissivity, and can rapidly adapt to the environmental background temperature, and thus has better infrared stealth performance.

Example 3

[0040] According to the same method and conditions as those in Example 1, a mica-based phase change thermal storage composite material was prepared (except that the mass ratio of stearic acid to a vanadium-extracted mica was changed into 5:5) and a mica-based phase change thermal storage thin layer was then obtained; VO.sub.2 nanoparticles were spin-coated with the same number of spin coating, and finally, a VO.sub.2/mica-based phase change thermal storage thin layer composite material was obtained, which was marked as sample 3.

[0041] According to the criterion for evaluating infrared stealth, the infrared stealth performance was tested by using an infrared thermographic camera Fluke Thermography TiS50 as follows. The dual phase change material obtained above (sample 3) and a pure phase change material (sample 0) in Comparative Example 1 were charged into a glass mold and placed on a rectangular heating plate at 68-73° C. for a period of time. As shown in the grayscale images of FIG. 3, when the plate temperature was T.sub.B=71.6° C., and the environmental temperature was T.sub.E=57.6° C., sample 1 (T.sub.3=58.1° C.) had a temperature closer to the environmental temperature than sample 0 (T.sub.0=64.2° C.), and had a lower infrared emissivity. Therefore, the prepared dual phase change material had a better ability of adjusting temperature and infrared emissivity, and can rapidly adapt to the environmental background temperature, and thus had better infrared stealth performance.

Comparative Example 1

[0042] Stearic acid was used as a pure phase change material and pressed under the same pressure of 10 MPa as the mica-based phase change thermal storage thin layer to obtain a stearic acid thin layer, which was marked as sample 0.