High-adhesion vanadium dioxide coating and preparation method thereof

Abstract

The invention discloses a high-adhesion vanadium dioxide coating and a preparation method thereof.The method comprises the following steps that PVP is dissolved in deionized water, heating and stirring are conducted, then sodium carboxymethyl cellulose is added, and heating and stirring are conducted in vacuum to obtain a polymer colloidal solution; adding vanadium dioxide nano-powder into the colloidal solution, then adding sodium silicate powder, then adding a silane coupling agent, and stirring and mixing; and the stirred solution is subjected to ultrasonic treatment and vacuum standing, and the high-adhesion vanadium dioxide coating solution is obtained. Sodium carboxymethyl cellulose and sodium silicate are added in the coating preparation process, a solid-colloid-liquid mixed system is formed by optimizing the solid-liquid ratio, a coating solution can be automatically uniform in sedimentation, and the binding force to a matrix is increased through surface modification on colloid, so that the bonding force between the coating solution and the matrix is improved; therefore, the adhesive force of the VO2 coating on the substrate is obviously enhanced, and the stripping and cracking phenomena of the coating are effectively prevented.

Description

Technical Field

[0001] The invention relates to the field of functional coating materials, and in particular to a high-adhesion vanadium dioxide coating and a preparation method thereof. Background Art

[0002] Vanadium dioxide (VO2) is a functional material with phase change properties. It undergoes a phase change from semiconductor to metal at about 68°C, accompanied by significant changes in its optical and electrical properties. This property makes VO2 have important potential in applications such as smart energy-saving windows, temperature control materials, and smart optical devices. VO2 coatings can adjust light transmittance, reflectivity, and absorption of infrared radiation, effectively reducing the energy consumption of buildings or devices. Therefore, it has received widespread attention in the fields of smart energy-saving building materials, thermal management coatings, etc.

[0003] However, a major challenge facing VO2 materials in practical applications is the lack of adhesion of the coating. When VO2 coatings are applied to various substrate materials (such as glass, aluminum, stainless steel, etc.), they often have poor adhesion, especially under large changes in ambient temperature or mechanical stress, the coating is prone to peeling or cracking. This greatly limits the actual service life and application range of VO2 coatings.

[0004] In order to solve this problem, the existing technology mainly enhances the adhesion of VO2 coating through the following methods:

[0005] Surface pretreatment: Physical or chemical treatment of the substrate surface (such as sandblasting, plasma cleaning, chemical etching, etc.) is performed to increase the roughness or surface energy of the substrate to enhance the bonding strength between the coating and the substrate. However, this method not only increases the complexity of the process, but may also affect the physical properties of the substrate material.

[0006] Adding binders: Adding organic or inorganic binders to the VO2 coating to enhance the mechanical strength and adhesion of the coating. Commonly used binders include organic polymer materials such as polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP), or inorganic substances such as sodium silicate. Although these binders can improve the adhesion of the coating, their dosage and proportion are difficult to control accurately, and the binders are prone to degradation under high temperature or long-term exposure, resulting in a decrease in coating performance.

[0007] Doping modification: By doping other functional materials in the VO2 coating, such as metal oxides or silane coupling agents, the adhesion of the coating and its mechanical and thermal stability can be improved. Although doping modification can improve the performance of the VO2 coating to a certain extent, it often requires a complex material preparation process, and the doping elements may affect the phase change characteristics of VO2, thereby reducing its actual application effect.

[0008] In addition, the leveling properties of VO2 coatings are also an important factor affecting their adhesion. Poor leveling of the coating will lead to uneven coating surface, uneven thickness or local aggregation, which will affect the optical properties and mechanical strength of the coating. In the prior art, although the leveling properties of the coating can be improved to a certain extent by adjusting the coating process or adding dispersants, these methods often cannot obtain stable coating quality when coating on a large area, and there are still problems of insufficient adhesion and poor coating surface quality.

[0009] In summary, the existing technology still has many deficiencies in improving the adhesion and leveling properties of VO2 coatings. In particular, maintaining the uniformity and phase change properties of the coating while improving the adhesion of the coating is a difficult problem in the technical field. Therefore, developing a simple process that can significantly improve the adhesion of the VO2 coating and improve its leveling properties and coating uniformity has important research value and application prospects. Summary of the invention

[0010] The purpose of the present invention is to provide a high-adhesion vanadium dioxide coating and a preparation method thereof, which has simple steps, is easy to operate, has low cost and has good coating adhesion.

[0011] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0012] In a first aspect, the present invention provides a method for preparing a high-adhesion vanadium dioxide coating, comprising the following steps:

[0013] Step 1, dissolving 0.5-3% PVP by mass in deionized water, heating and stirring, then adding 0.01-0.1% sodium carboxymethyl cellulose by mass of water, heating and stirring in vacuum to obtain a polymer colloid solution;

[0014] Step 2, adding 1-3% of the mass of vanadium dioxide nanopowder to the colloidal solution, then adding sodium silicate powder, the mass ratio of vanadium dioxide to sodium silicate is 1:(0.1-1), adding 0.001-0.005% of the mass of the total solution silane coupling agent, stirring and mixing;

[0015] Step three, subjecting the stirred solution to ultrasonic treatment and allowing it to stand in vacuum for 6 to 12 hours to obtain a high-adhesion vanadium dioxide coating solution.

[0016] Preferably, in step 1, the heating temperature of the PVP and deionized water is 70-90° C., the stirring rate is 200-800 rpm, and the heating and stirring time is 3-4 h.

[0017] Preferably, in step 1, the vacuum heating temperature is 50-80° C., and the stirring rate is 200-800 rpm.

[0018] Preferably, in step 2, the reducing atmosphere comprises nitrogen and hydrogen, wherein the proportion of hydrogen in the total gas volume is 5-15%, and the calcination time is 1-5 hours.

[0019] Preferably, in step 2, the silane coupling agent is one or more of KH550, KH560, and KH570, and the stirring rate is 400-1000 rpm.

[0020] Preferably, in step three, the ultrasonic power is 500-2000W, and the ultrasonic time is 2-6h.

[0021] Furthermore, the preparation of the coating also includes a coating step, the coating method is one of casting, spraying, and spin coating, the coating thickness is 10 to 50 microns, the drying temperature after coating is 50 to 60° C., and the drying time is 6 to 24 hours.

[0022] In a second aspect, the present invention provides a high-adhesion vanadium dioxide coating prepared by the above preparation method.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. Significantly improve the adhesion of the coating: By adding sodium carboxymethyl cellulose and sodium silicate during the coating preparation process and optimizing the solid-liquid ratio, a solid-colloid-liquid mixed system is formed. Since the coating solution can be uniform by itself during sedimentation and the surface modification of the colloid increases the binding force to the substrate, the adhesion of the VO2 coating on the substrate is significantly enhanced, effectively preventing the peeling and cracking of the coating.

[0025] 2. Improve the leveling properties of the coating: By controlling the proportion of each component in the colloidal solution, the present invention optimizes the leveling properties of the VO2 coating, so that the coating can remain uniform when coated over a large area, thereby improving the surface quality of the coating.

[0026] 3. Simplified process, suitable for a variety of coating methods: The coating method adopted by the present invention is simple and the process parameters are easy to control. It is suitable for a variety of coating technologies such as casting, spraying, spin coating, etc. It is suitable for industrial production, low cost, and environmentally friendly.

[0027] 4. Wide range of applications: The high-adhesion VO2 coating of the present invention is not only suitable for smart energy-saving windows and temperature control equipment, but can also be used in many fields such as thermal management of electronic devices and dimming function of optical devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a bar chart comparing the minimum phase transition temperatures of the coatings prepared in Examples 1, 2, 3 and the comparative example. DETAILED DESCRIPTION

[0029] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] Example 1

[0031] Dissolve 1% PVP in deionized water, heat to 80°C and stir at 500rpm for 3 hours, then add 0.05% sodium carboxymethyl cellulose by weight of water. Heat the solution to 60°C under vacuum conditions and continue stirring for 2 hours to obtain a polymer colloidal solution. Add 2% vanadium dioxide nanopowder by weight of the solution to this colloidal solution, add sodium silicate powder at a mass ratio of vanadium dioxide to sodium silicate of 1:0.5, and add 0.003% silane coupling agent (select KH550) by weight of the total solution. Stir at a rate of 800rpm for 4 hours. The stirred solution is ultrasonically treated with an ultrasonic power of 1000W and an ultrasonic time of 4 hours. Then stand under vacuum conditions for 10 hours to obtain a high-adhesion vanadium dioxide coating solution.

[0032] The coating method is spin coating, and the coating thickness is 30 microns. After coating, it is dried at 50° C. for 12 hours to obtain a high-adhesion vanadium dioxide coating.

[0033] Example 2

[0034] Dissolve 2% PVP in deionized water, heat to 85°C and stir at 600rpm for 3.5 hours, then add 0.03% sodium carboxymethyl cellulose by weight of water. Heat the solution to 65°C under vacuum conditions and continue stirring for 3 hours to obtain a polymer colloidal solution. Add 1.5% of the solution mass of vanadium dioxide nanopowder to this colloidal solution, add sodium silicate powder at a mass ratio of vanadium dioxide to sodium silicate of 1:0.7, and add 0.002% of the total solution mass of silane coupling agent (select KH570). Stir at a rate of 700rpm for 3 hours. The stirred solution is ultrasonically treated with an ultrasonic power of 1500W and an ultrasonic time of 3 hours. Then stand for 8 hours under vacuum conditions to obtain a high-adhesion vanadium dioxide coating solution.

[0035] The coating method is spray coating, and the coating thickness is 40 microns. After coating, it is dried at 55° C. for 18 hours to obtain a high-adhesion vanadium dioxide coating.

[0036] Example 3

[0037] Dissolve 3% PVP in deionized water, heat to 90°C and stir at 800rpm for 4 hours, then add 0.1% sodium carboxymethyl cellulose by weight of water. Heat the solution to 80°C under vacuum conditions and continue stirring for 4 hours to obtain a polymer colloidal solution. Add 3% vanadium dioxide nanopowder by weight of the solution to this colloidal solution, add sodium silicate powder at a mass ratio of vanadium dioxide to sodium silicate of 1:1, and add 0.005% silane coupling agent (select KH560) by weight of the total solution. Stir at a rate of 1000rpm for 5 hours. The stirred solution is ultrasonically treated with an ultrasonic power of 2000W and an ultrasonic time of 6 hours. Then stand under vacuum conditions for 12 hours to obtain a high-adhesion vanadium dioxide coating solution.

[0038] The coating method is tape casting, and the coating thickness is 50 microns. After coating, it is dried at 60° C. for 24 hours to obtain a high-adhesion vanadium dioxide coating.

[0039] Comparative Example

[0040] Dissolve 1% PVP in deionized water, heat to 80°C and stir at 500rpm for 3 hours, then heat the solution to 60°C under vacuum and continue stirring for 2 hours to obtain a polymer solution. Add 2% of the solution mass of vanadium dioxide nanopowder, add sodium silicate powder at a mass ratio of vanadium dioxide to sodium silicate of 1:0.5, and add 0.003% of the total solution mass of silane coupling agent (select KH550). Stir at 800rpm for 4 hours.

[0041] The stirred solution was subjected to ultrasonic treatment at an ultrasonic power of 1000 W for 4 hours, and then allowed to stand under vacuum for 10 hours.

[0042] Figure 1 It is a comparative bar graph of the adhesion of the coatings prepared in Examples 1, 2, 3 and the comparative example.

[0043] like Figure 1 As shown, the test adopts the standard of GB5210-85 "Determination of Coating Adhesion" and uses the pull-off method to test. The test results show that Examples 1, 2, and 3 effectively improve the adhesion after forming a solid-colloid-liquid three-system, while the comparative example is a solid-liquid solution, and the final coating adhesion is low. In summary, the material prepared by the method provided by the present invention has high adhesion, and is therefore very suitable for use as a coating for various substrates.

[0044] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A method for preparing a high-adhesion vanadium dioxide coating, characterized in that: The leveling properties of the coating are improved by adjusting the solid-liquid volume and enhancing the adhesion, which specifically includes the following steps: Step 1, dissolving 0.5-3% PVP by mass in deionized water, heating and stirring, then adding 0.01-0.1% sodium carboxymethyl cellulose by mass of water, heating and stirring in vacuum to obtain a polymer colloid solution; Step 2, adding 1-3% of the mass of vanadium dioxide nanopowder to the colloidal solution, then adding sodium silicate powder, the mass ratio of vanadium dioxide to sodium silicate is 1:(0.1-1), adding 0.001-0.005% of the mass of the total solution silane coupling agent, stirring and mixing; Step three, subjecting the stirred solution to ultrasonic treatment and allowing it to stand in vacuum for 6 to 12 hours to obtain a high-adhesion vanadium dioxide coating solution.

2. The method for preparing a high-adhesion vanadium dioxide coating according to claim 1, characterized in that: In step 1, the heating temperature of the PVP and deionized water is 70-90° C., the stirring rate is 200-800 rpm, and the heating and stirring time is 3-4 hours.

3. The method for preparing a high-adhesion vanadium dioxide coating according to claim 1, characterized in that: In step 1, the vacuum heating temperature is 50-80° C., and the stirring rate is 200-800 rpm.

4. The method for preparing a high-adhesion vanadium dioxide coating according to claim 1, characterized in that: In step 2, the reducing atmosphere comprises nitrogen and hydrogen, wherein the proportion of hydrogen in the total gas volume is 5-15%, and the calcination time is 1-5 hours.

5. The method for preparing a high-adhesion vanadium dioxide coating according to claim 1, characterized in that: In step 2, the silane coupling agent is one or more of KH550, KH560, and KH570, and the stirring rate is 400 to 1000 rpm.

6. The method for preparing a high-adhesion vanadium dioxide coating according to claim 1, characterized in that: In step three, the ultrasonic power is 500-2000W, and the ultrasonic time is 2-6h.

7. A method for preparing a high-adhesion vanadium dioxide coating according to any one of claims 1 to 6, characterized in that: The preparation of the coating also includes a coating step, the coating method is one of casting, spraying, and spin coating, the coating thickness is 10 to 50 microns, the drying temperature after coating is 50 to 60° C., and the drying time is 6 to 24 hours.

8. A high-adhesion vanadium dioxide coating prepared by the preparation method according to any one of claims 1 to 7.

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