Geopolymer-based reversible color-changing high-temperature-resistant material as well as preparation and application thereof

Abstract

The invention relates to the technical field of high-temperature-resistant coatings, in particular to a geopolymer-based reversible color-changing high-temperature-resistant material as well as preparation and application thereof. The geopolymer-based reversible color-changing high-temperature-resistant material provided by the invention comprises the following components in parts by weight: 60 parts of metakaolin, 60 parts of an alkali activator, 30-150 parts of BiVO4 and 30 parts of water, the invention aims to provide an environment-friendly high-temperature-resistant inorganic reversible thermochromic coating by taking a geopolymer as a base material and taking BiVO4 as a pigment filler. A coating further prepared from the geopolymer-based reversible color-changing high-temperature-resistant material provided by the invention is crack-free, has excellent water resistance and wear resistance, is environment-friendly and non-toxic, does not decompose at high temperature, and has excellent reversible thermochromic property.

Description

Technical Field

[0001] The present invention relates to the technical field of high-temperature resistant coatings, and particularly relates to a geopolymer-based reversible color-changing high-temperature resistant material and its preparation and application. Background Art

[0002] Color-changing coating materials are a kind of special coating materials, which can affect the change of their own colors under the action of the surrounding environment. The environmental actions include electricity, heat, and force, etc., and these factors control the colors of the color-changing coatings. Coatings that can only change color unidirectionally are called irreversible color-changing coatings, while coatings that can achieve two-way reversible color change are called reversible color-changing coatings.

[0003] Color-changing coatings are divided into photochromic coatings, electrochromic coatings, thermochromic coatings, etc. according to the types of response media. Coatings that are affected by heat to change color are called thermochromic coatings. In many materials and compounds, thermochromism is a perceptible phenomenon, in which the change in color is a response to temperature changes within a corresponding range. This process involves thermally induced lattice expansion or ligand changes, molecular structure or coordination number. Thermochromic materials have excellent application prospects in various fields, including decorative daily necessities or toys, kitchen cookware for indicating cooking temperature, sensors for monitoring temperature changes, smart glass, anti-counterfeiting labels, coatings for aerospace, etc.

[0004] However, there are still some defects in the color-changing coating materials currently on the market. For example, the color-changing effects of some coatings are irreversible and only have a one-time color-changing function; some coatings have poor wear resistance and are easy to lose the basic properties of the coatings; some coatings contain toxic color-changing raw materials, threatening environmental sanitation and human health; some coatings will decompose and lose at medium and high temperatures, losing their coating protection function and color-changing ability.

[0005] Therefore, it is crucial to provide a technical solution that can solve the above technical problems. Summary of the Invention

[0006] In order to solve the above problems, the purpose of the present invention is to provide a geopolymer-based reversible color-changing high-temperature resistant material and its preparation and application. The geopolymer-based reversible color-changing high-temperature resistant material provided by the present invention includes the following components in parts by weight: 60 parts of metakaolin, 60 parts of alkali activator, 30 - 150 parts of BiVO4, and 30 parts of water; aiming to use geopolymer (metakaolin and alkali activator) as the base material and BiVO4 as the pigment and filler to provide an environmentally friendly high-temperature resistant inorganic reversible thermochromic coating. The coating further prepared by using the geopolymer-based reversible color-changing high-temperature resistant material provided by the present invention has no cracks, excellent water resistance, wear resistance, is environmentally friendly, non-toxic, does not decompose at high temperatures, and has excellent reversible thermochromic properties.

[0007] The purpose of the present invention can be achieved through the following technical solutions:

[0008] The first object of the present invention is to provide a geopolymer-based reversible color-changing high-temperature resistant material, comprising the following components in parts by weight:

[0009] 60 parts of metakaolin, 50 - 70 parts of alkali activator, 30 - 150 parts of BiVO4, 25 - 35 parts of a first solvent.

[0010] In an embodiment of the present invention, it comprises the following components in parts by weight:

[0011] 60 parts of metakaolin, 60 parts of alkali activator, 90 parts of BiVO4, 30 parts of a first solvent.

[0012] In an embodiment of the present invention, the first solvent is water.

[0013] In an embodiment of the present invention, the alkali activator comprises 49 - 51 wt% of a water glass solution, 3 - 5 wt% of a strong base, 0.4 - 0.6 wt% of a water reducing agent, and the balance is a second solvent;

[0014] The second solvent is water.

[0015] In an embodiment of the present invention, the metakaolin D 50 is 0.68 - 0.70 μm, preferably, the metakaolin D 50 is 0.695 μm;

[0016] The water glass solution comprises 25 - 45 wt% of silicon dioxide and 10 - 15 wt% of sodium oxide, and the balance is a third solvent;

[0017] The third solvent is water;

[0018] The strong base is selected from one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, or barium hydroxide;

[0019] The water reducing agent is selected from one or more of polycarboxylate water reducing agents, naphthalene-based superplasticizers, amino sulfonate-based superplasticizers, melamine-based and modified melamine-based superplasticizers, or lignosulfonate-based water reducing agents.

[0020] The second object of the present invention is to provide a preparation method of a geopolymer-based reversible color-changing high-temperature resistant material, comprising the following steps:

[0021] (S1) Mix the alkali activator evenly and then carry out heat preservation treatment;

[0022] (S2) Mix the metakaolin with the heat-preserved alkali activator prepared in step (S1) to obtain a geopolymer;

[0023] (S3) Mix 60 parts of BiVO4 with water to obtain a pigment and filler solution;

[0024] (S4) Add the pigment and filler solution prepared in step (S3) to the geopolymer prepared in step (S2), and mix well to obtain a geopolymer-based reversible color-changing high-temperature resistant material.

[0025] In one embodiment of the present invention, in step (S1), during the heat preservation treatment, the temperature is 40 - 50 °C and the time is 18 - 30 h.

[0026] In one embodiment of the present invention, in step (S2), during the mixing process, the rotation speed is 600 - 900 rpm and the time is 12 - 24 h;

[0027] Preferably, in step (S2), during the mixing process, the rotation speed is 750 rpm and the time is 18 h;

[0028] In step (S3), the mixing is ultrasonic dispersion mixing, and the time is 20 - 60 min;

[0029] Preferably, in step (S3), the mixing time is 30 min;

[0030] In step (S4), during the mixing process, the rotation speed is 600 - 900 rpm and the time is 20 - 40 min;

[0031] Preferably, in step (S3), the mixing time is 30 min.

[0032] The third object of the present invention is to provide an application of a geopolymer-based reversible color-changing high-temperature resistant material in the preparation of a coating.

[0033] In one embodiment of the present invention, it includes the following steps:

[0034] Coat the geopolymer-based reversible color-changing high-temperature resistant material onto a substrate, and then perform gradient temperature rising curing treatment.

[0035] In one embodiment of the present invention, the substrate is selected from one of a metal plate, a ceramic plate, a composite plate, or a graphite electrode plate;

[0036] In one embodiment of the present invention, the gradient temperature rising curing treatment includes a first curing treatment, a second curing treatment, and a third curing treatment;

[0037] During the first curing treatment, the temperature is 40 - 60 °C and the time is 8 - 16 h;

[0038] During the second curing treatment, the temperature is 60 - 80 °C and the time is 8 - 16 h;

[0039] During the third curing process, the temperature is 80 - 100 °C and the time is 8 - 16 h.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] (1) During the setting and hardening process of geopolymers, severe volume shrinkage occurs, which easily leads to cracking, and this is a major drawback of geopolymer materials. The geopololymer-based reversible color-changing high-temperature-resistant material provided by the present invention adds BiVO4, improving the dry shrinkage cracking resistance of geopolymer materials; the addition of pigments and fillers in the present invention fills the voids between geopolymers, combines with geopolymers as a whole, and at the same time disperses the stress generated between molecules during the hardening process of geopolymer materials, reducing the volume change caused during the dehydration of the coating and preventing crack generation, greatly improving the dry shrinkage cracking resistance of geopolymer coating materials.

[0042] (2) In the present invention, geopolymer becomes a powerful base material for greatly improving the mechanical properties of BiVO4 pigments. While maintaining the excellent thermochromic properties of BiVO4 itself, it improves the wear resistance and water resistance of the pigments.

[0043] (3) Although the BiVO4 color-changing layer sprayed with ordinary absolute ethanol is high-temperature-resistant and has good color performance, ethanol does not have a protective effect, and the pigment layer is extremely easy to lose. Although the coating protected by the silicone coating has excellent color performance at room temperature, after exceeding 200 °C, the coating decomposes and turns black, losing the basic performance of the coating. First, the geopolymer base material has excellent physical and chemical properties, ensuring the basic performance of the coating, such as mechanical strength, hardness, adhesion, and acid, alkali, and salt resistance; second, the color of the geopolymer curing base material after film formation is light white, which will not cover the color displayed by the color-changing base material and does not affect the color-changing characteristics of the pigments and fillers. After the coating is cured, the color-changing base material can still have the color-changing effect.

[0044] (4) In the present invention, both the geopolymer base material and the BiVO4 base material are environmentally friendly and non-toxic, and have good compatibility. The combination of the two improves their respective disadvantages of being easily lost and easily cracked, while maintaining their respective advantages. Without adding other fillers, the formulation and production method are simple, and the combined coating has excellent performance in all aspects. Description of the Drawings

[0045] Figure 1 XRD patterns of the coatings prepared in Examples 1 - 5 and Comparative Example 1;

[0046] Figure 2 Schematic diagrams of the water contact angles of the coatings prepared in Examples 1 - 5 and Comparative Example 1;

[0047] Figure 3 Thermochromic characterization diagrams of the coatings prepared in Examples 1 - 5

[0048] Figure 4 Schematic diagram of the hardness of the coatings prepared in Examples 1-5. Detailed implementation manners

[0049] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0050] In the following embodiments, unless otherwise specified, the reagents used are all commercially available reagents, and the detection means and methods used are all conventional detection means and methods in the art.

[0051] In the following embodiments, sodium silicate is a mixture of silicon dioxide, sodium oxide and water, and the mass ratio of silicon dioxide, sodium oxide and water is 30:13.5:56.5; the polycarboxylate superplasticizer is purchased from Dongguan Aoda Environmental Protection New Materials Co., Ltd. (powder dispersant AD8030); metakaolin is prepared by the following method: ultrafine kaolin is calcined at 650 °C for 2 h and ground to 4000 mesh.

[0052] Example 1

[0053] This example provides a preparation method of a geopolymer-based reversible color-changing high-temperature resistant material and coating, which specifically includes the following steps:

[0054] (S1) Mix 50 parts of sodium silicate, 4 parts of sodium hydroxide, 0.5 part of polycarboxylate superplasticizer and 5.5 parts of water, and then keep warm at 45 °C for 24 h to obtain an alkali activator;

[0055] (S2) Add the alkali activator prepared in step (S1) and 60 parts of metakaolin into a blender, and stir at a speed of 750 rpm for 18 h to obtain a geopolymer;

[0056] (S3) Ultrasonically disperse 30 parts of BiVO4 and 30 parts of water for 30 min to obtain a pigment and filler solution;

[0057] (S4) Add the pigment and filler solution prepared in step (S3) into the geopolymer prepared in step (S2), and stir at a speed of 750 rpm for 30 min to obtain a geopolymer-based reversible color-changing high-temperature resistant material.

[0058] Brush the geopolymer-based reversible color-changing high-temperature resistant material prepared in this example on the surface of a copper plate, keep it warm at 50 °C for 12 h, then transfer it to 70 °C and keep it warm for 12 h, and finally transfer it to 100 °C and keep it warm for 12 h to form a coating with a thickness of 1-2 mm on the surface of the copper plate (its XRD pattern is as shown in Figure 1 shown, the water contact angle is as shown in Figure 2 b, the thermal color change characterization is as shown in Figure 3 shown, and the hardness is as shown in Figure 4 shown).

[0059] Example 2

[0060] This example provides a preparation method of a geopolymer-based reversible color-changing high-temperature resistant material and coating, which specifically includes the following steps:

[0061] (S1) Mix 50 parts of water glass, 4 parts of sodium hydroxide, 0.5 part of polycarboxylate superplasticizer, and 5.5 parts of water, and then keep it at 45 °C for 24 h to obtain an alkali activator;

[0062] (S2) Add the alkali activator prepared in step (S1) and 60 parts of metakaolin into a blender, and stir at a speed of 750 rpm for 18 h to obtain a geopolymer;

[0063] (S3) Ultrasonically disperse 60 parts of BiVO4 and 30 parts of water for 30 min to obtain a pigment and filler solution;

[0064] (S4) Add the pigment and filler solution prepared in step (S3) into the geopolymer prepared in step (S2), and stir at a speed of 750 rpm for 30 min to obtain a geopolymer-based reversible color-changing high-temperature resistant material.

[0065] Brush the geopolymer-based reversible color-changing high-temperature resistant material prepared in this example on the surface of a copper plate, keep it at 50 °C for 12 h, then transfer it to 70 °C for 12 h, and finally transfer it to 100 °C for 12 h to form a coating with a thickness of 1 - 2 mm on the copper plate surface (its XRD pattern is as shown in Figure 1 shown, the water contact angle is as shown in Figure 2 c, the thermal color change characterization is as shown in Figure 3 shown, and the hardness is as shown in Figure 4 shown).

[0066] Example 3

[0067] This example provides a preparation method of a geopolymer-based reversible color-changing high-temperature resistant material and coating, which specifically includes the following steps:

[0068] (S1) Mix 50 parts of water glass, 4 parts of sodium hydroxide, 0.5 part of polycarboxylate superplasticizer, and 5.5 parts of water, and then keep it at 45 °C for 24 h to obtain an alkali activator;

[0069] (S2) Add the alkali activator prepared in step (S1) and 60 parts of metakaolin into a blender, and stir at a speed of 750 rpm for 18 h to obtain a geopolymer;

[0070] (S3) Ultrasonically disperse 90 parts of BiVO4 and 30 parts of water for 30 min to obtain a pigment and filler solution;

[0071] (S4) Add the pigment and filler solution prepared in step (S3) to the geopolymer prepared in step (S2), and stir at a speed of 750 rpm for 30 min to obtain a geopolymer-based reversible thermochromic and high-temperature resistant material.

[0072] Brush the geopolymer-based reversible thermochromic and high-temperature resistant material prepared in this example on the surface of a copper plate, keep it at 50 °C for 12 h, then transfer it to 70 °C for 12 h, and finally transfer it to 100 °C for 12 h to form a coating with a thickness of 1 - 2 mm on the copper plate surface (its XRD pattern is as shown in Figure 1 shown, the water contact angle is as shown in Figure 2 d, the thermochromic characterization is as shown in Figure 3 shown, and the hardness is as shown in Figure 4 shown).

[0073] Example 4

[0074] This example provides a preparation method of a geopolymer-based reversible thermochromic and high-temperature resistant material and a coating, which specifically includes the following steps:

[0075] (S1) Mix 50 parts of water glass, 4 parts of sodium hydroxide, 0.5 part of polycarboxylate water reducer, and 5.5 parts of water, and then keep it at 45 °C for 24 h to obtain an alkali activator;

[0076] (S2) Add the alkali activator prepared in step (S1) and 60 parts of metakaolin to a blender, and stir at a speed of 750 rpm for 18 h to obtain a geopolymer;

[0077] (S3) Ultrasonically disperse 120 parts of BiVO4 and 30 parts of water for 30 min to obtain a pigment and filler solution;

[0078] (S4) Add the pigment and filler solution prepared in step (S3) to the geopolymer prepared in step (S2), and stir at a speed of 750 rpm for 30 min to obtain a geopolymer-based reversible thermochromic and high-temperature resistant material.

[0079] Brush the geopolymer-based reversible thermochromic and high-temperature resistant material prepared in this example on the surface of a copper plate, keep it at 50 °C for 12 h, then transfer it to 70 °C for 12 h, and finally transfer it to 100 °C for 12 h to form a coating with a thickness of 1 - 2 mm on the copper plate surface (its XRD pattern is as shown in Figure 1 shown, the water contact angle is as shown in Figure 2 e, the thermochromic characterization is as shown in Figure 3 shown, and the hardness is as shown in Figure 4 shown).

[0080] Example 5

[0081] This embodiment provides a preparation method of a geopolymer-based reversible color-changing high-temperature resistant material and coating, which specifically includes the following steps:

[0082] (S1) Mix 50 parts of water glass, 4 parts of sodium hydroxide, 0.5 part of polycarboxylate water reducer, and 5.5 parts of water, and then keep it at 45 °C for 24 h to obtain an alkali activator;

[0083] (S2) Add the alkali activator prepared in step (S1) and 60 parts of metakaolin into a blender, and stir at a speed of 750 rpm for 18 h to obtain a geopolymer;

[0084] (S3) Ultrasonically disperse 150 parts of BiVO4 and 30 parts of water for 30 min to obtain a pigment and filler solution;

[0085] (S4) Add the pigment and filler solution prepared in step (S3) into the geopolymer prepared in step (S2), and stir at a speed of 750 rpm for 30 min to obtain a geopolymer-based reversible color-changing high-temperature resistant material.

[0086] Brush the geopolymer-based reversible color-changing high-temperature resistant material prepared in this embodiment on the surface of a copper plate, keep it at 50 °C for 12 h, then transfer it to 70 °C for 12 h, and finally transfer it to 100 °C for 12 h to form a coating with a thickness of 1 - 2 mm on the copper plate (its XRD pattern is as shown in Figure 1 , the water contact angle is as shown in Figure 2 f, the thermochromic characterization is as shown in Figure 3 , and the hardness is as shown in Figure 4 ).

[0087] Comparative Example 1

[0088] This comparative example provides a preparation method of a geopolymer-based material and coating, which specifically includes the following steps:

[0089] (S1) Mix 50 parts of water glass, 4 parts of sodium hydroxide, 0.5 part of polycarboxylate water reducer, and 5.5 parts of water, and then keep it at 45 °C for 24 h to obtain an alkali activator;

[0090] (S2) Add the alkali activator prepared in step (S1) and 60 parts of metakaolin into a blender, and stir at a speed of 750 rpm for 18 h to obtain a geopolymer;

[0091] (S3) Add 30 parts of water into the geopolymer prepared in step (S2), and stir at a speed of 750 rpm for 30 min to obtain a geopolymer-based reversible color-changing high-temperature resistant material.

[0092] The geopolymer-based reversible color-changing high-temperature resistant material prepared in this comparative example was brush-coated on the surface of a copper plate, kept at 50 °C for 12 h, then transferred to 70 °C for 12 h, and finally transferred to 100 °C for 12 h to form a coating with a thickness of 1-2 mm on the copper plate surface (its XRD pattern is as shown in Figure 1 , and the water contact angle is as shown in Figure 2 a).

[0093] It can be found through Figure 1 that after the addition of BiVO4, characteristic peaks of bismuth vanadate appeared in the coating, and the peak intensity gradually increased. The broad peak of the geopolymer at 20° to 40° still existed after doping 30 parts of BiVO4, but the intensity of the broad peak became smaller. Until 90 parts of BiVO4 were doped, the broad peak disappeared, indicating that the peak intensity of BiVO4 far exceeded the characteristic peak of metakaolin (geopolymer); at the same time, the angle of the characteristic peak did not shift left or right, and the composition of the geopolymer and BiVO4 did not change, which indicated that the geopolymer and BiVO4 were well mixed, and the compatibility of the coating material was very good. As the doping ratio of BiVO4 increased, the proportion of the geopolymer decreased linearly.

[0094] It can be found through Figure 2 that the contact angles of all coating samples are less than 90°, indicating that the surfaces of the coatings are hydrophilic, which is in line with the hydrophilic characteristics of the geopolymer. Further, after adding different proportions of BiVO4 to the coating, the water contact angle of the coating first increased from 13.56° to 22.35° and then decreased to 9.80°, indicating that the addition of BiVO4 below 90 parts improved the surface hydrophilicity of the coating. Water molecules are not easily introduced into the interior of the coating, reducing the possibility of water molecules replacing sodium ions and causing the coating to powder and peel off, which can also represent the improvement and enhancement of the water resistance of the coating.

[0095] It can be found through Figure 3 that the samples with different proportions of BiVO4 added all showed a thermochromic effect. When heated from room temperature to 400 °C, the color gradually changed from bright yellow to brick red, and when cooled to room temperature, the color returned to that before heating. The thermochromic effect and reversible color-changing behavior of the samples were excellent. For the samples with different amounts of BiVO4 added, the color-changing effects were slightly different. The thermochromic effect of the coating doped with 30 parts of BiVO4 was obvious, but the reversibility was poor. After cooling to room temperature, it lost its original bright yellow color performance, and the coating became gray and dull; the reversible color-changing effect of the coating doped with 60 parts of BiVO4 was good, but the color was darker. The colors of the coatings doped with 90 parts, 120 parts, and 150 parts of BiVO4 were brighter. All samples showed different reversible differences and had a strong dependence on temperature changes. At the same time, they had excellent high-temperature resistance and no volatilization of toxic and harmful substances.

[0096] Hardness is an important basis for measuring the quality of coatings. Coatings with high hardness have good wear resistance. By Figure 4 It can be found that as the content of BiVO4 gradually increases, the hardness grade of the coating reaches 8H when the content of BiVO4 is 60 parts, and then tends to be stable. The hardness of the coating is closely related to its internal structure and compactness. The addition of an appropriate proportion of BiVO4 fills the pores in the geopolymer, making the internal structure of the coating more compact and improving the wear resistance of the coating.

[0097] Example 6

[0098] This example provides a preparation method of a geopolymer-based reversible color-changing high-temperature resistant material and coating, which specifically includes the following steps:

[0099] (S1) Mix 50 parts of water glass, 4 parts of sodium hydroxide, 0.5 part of polycarboxylate water reducer, and 5.5 parts of water, and then keep it warm at 40 °C for 30 h to obtain an alkali activator;

[0100] (S2) Add the alkali activator prepared in step (S1) and 60 parts of metakaolin into a blender, and stir at a speed of 900 rpm for 12 h to obtain a geopolymer;

[0101] (S3) Ultrasonically disperse 90 parts of BiVO4 and 30 parts of water for 20 min to obtain a pigment and filler solution;

[0102] (S4) Add the pigment and filler solution prepared in step (S3) into the geopolymer prepared in step (S2), and stir at a speed of 900 rpm for 20 min to obtain a geopolymer-based reversible color-changing high-temperature resistant material.

[0103] Brush the geopolymer-based reversible color-changing high-temperature resistant material prepared in this example on the surface of a copper plate, keep it warm at 40 °C for 16 h, then transfer it to 80 °C for 8 h, and finally transfer it to 100 °C for 8 h to form a coating with a thickness of 1 - 2 mm on the surface of the copper plate.

[0104] Example 7

[0105] This example provides a preparation method of a geopolymer-based reversible color-changing high-temperature resistant material and coating, which specifically includes the following steps:

[0106] (S1) Mix 50 parts of water glass, 4 parts of sodium hydroxide, 0.5 part of polycarboxylate water reducer, and 5.5 parts of water, and then keep it warm at 50 °C for 18 h to obtain an alkali activator;

[0107] (S2) Add the alkali activator prepared in step (S1) and 60 parts of metakaolin into a blender, and stir at a speed of 600 rpm for 24 h to obtain a geopolymer;

[0108] (S3) Ultrasonically disperse 90 parts of BiVO4 and 30 parts of water for 60 min to obtain a pigment and filler solution;

[0109] (S4) Add the pigment and filler solution prepared in step (S3) to the geopolymer prepared in step (S2), and stir at a speed of 600 rpm for 40 min to obtain a geopolymer-based reversible color-changing and high-temperature resistant material.

[0110] Brush the geopolymer-based reversible color-changing and high-temperature resistant material prepared in this example on the surface of a copper plate, keep it at 60 °C for 8 h, then transfer it to 80 °C for 8 h, and finally transfer it to 90 °C for 16 h to form a coating with a thickness of 1 - 2 mm on the copper plate surface.

[0111] Example 8

[0112] This example provides a preparation method for a geopolymer-based reversible color-changing and high-temperature resistant material and a coating, which specifically includes the following steps:

[0113] (S1) Mix 50 parts of water glass, 4 parts of sodium hydroxide, 0.5 part of polycarboxylate water reducer, and 5.5 parts of water, and then keep it at 45 °C for 20 h to obtain an alkali activator;

[0114] (S2) Add the alkali activator prepared in step (S1) and 60 parts of metakaolin to a mixer, and stir at a speed of 800 rpm for 16 h to obtain a geopolymer;

[0115] (S3) Ultrasonically disperse 90 parts of BiVO4 and 30 parts of water for 20 min to obtain a pigment and filler solution;

[0116] (S4) Add the pigment and filler solution prepared in step (S3) to the geopolymer prepared in step (S2), and stir at a speed of 750 rpm for 40 min to obtain a geopolymer-based reversible color-changing and high-temperature resistant material.

[0117] Brush the geopolymer-based reversible color-changing and high-temperature resistant material prepared in this example on the surface of a copper plate, keep it at 50 °C for 12 h, then transfer it to 60 °C for 16 h, and finally transfer it to 80 °C for 16 h to form a coating with a thickness of 1 - 2 mm on the copper plate surface.

[0118] The coatings prepared in Examples 6 - 8 have basically the same performance as the coating prepared in Example 3.

[0119] The above description of the embodiments is provided to enable those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative efforts. Therefore, the present invention is not limited to the above embodiments, and all improvements and modifications made by those skilled in the art without departing from the scope of the present invention according to the interpretation of the present invention should be within the protection scope of the present invention.

Claims

1. A geopolymer-based reversible color-changing high-temperature resistant material, characterized in that, Comprising the following components in parts by weight: Metakaolin 60 parts, alkali activator 50 - 70 parts, BiVO4 30 - 150 parts, first solvent 25 - 35 parts.

2. The geopolymer-based reversible color-changing high-temperature resistant material according to claim 1, characterized in that, Comprising the following components in parts by weight: Metakaolin 60 parts, alkali activator 60 parts, BiVO4 90 parts, first solvent 30 parts.

3. The geopolymers-based reversible color-changing high-temperature resistant material according to claim 2, wherein, The alkali activator comprises 49 - 51 wt% of sodium silicate solution, 3 - 5 wt% of strong base, 0.4 - 0.6 wt% of water reducing agent, and the balance is the second solvent.

4. The geopolymers-based reversible color-changing high-temperature resistant material according to claim 3, characterized in that, The metakaolin D 50 is 0.68 to 0.70 μm; The sodium silicate solution comprises 25 - 45 wt% of silicon dioxide and 10 - 15 wt% of sodium oxide, and the balance is the third solvent; The strong base is selected from one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide or barium hydroxide; The water reducing agent is selected from one or more of polycarboxylate water reducing agent, naphthalene-based superplasticizer, amino sulfonate-based superplasticizer, melamine-based and modified melamine-based superplasticizer or lignosulfonate water reducing agent.

5. A preparation method of a geopolymer-based reversible color-changing high-temperature resistant material according to any one of claims 1 to 4, characterized in that, Comprising the following steps: (S1) Mix the alkali activator and then carry out heat preservation treatment; (S2) Mix metakaolin with the heat-preserved alkali activator prepared in step (S1) to obtain geopolymers; (S3) Mix 60 parts of BiVO4 with water to obtain a pigment and filler solution; (S4) Add the pigment and filler solution prepared in step (S3) to the geopolymers prepared in step (S2) and mix well to obtain a geopolymers-based reversible color-changing high-temperature resistant material.

6. The preparation method of a geopolymer-based reversible color-changing high-temperature resistant material according to claim 5, characterized in that, In step (S1), during the heat preservation treatment, the temperature is 40 - 50 °C and the time is 18 - 30 h.

7. The preparation method of a geopolymer-based reversible color-changing high-temperature resistant material according to claim 5, characterized in that, In step (S2), during the mixing process, the rotation speed is 600 - 900 rpm and the time is 12 - 24 h; In step (S3), the mixing is ultrasonic dispersion mixing and the time is 20 - 60 min; In step (S4), during the mixing process, the rotation speed is 600 - 900 rpm and the time is 20 - 40 min.

8. Use of a geopolymers-based reversible color-changing high-temperature resistant material according to any one of claims 1 - 4 in the preparation of a coating.

9. The application according to claim 8, characterized in that, Comprising the following steps: Coat the geopolymers-based reversible color-changing high-temperature resistant material onto a substrate, and then carry out gradient heating and curing treatment.

10. The application according to claim 9, characterized in that, The gradient heating and curing treatment includes a first curing treatment, a second curing treatment and a third curing treatment; During the first curing treatment, the temperature is 40 - 60 °C and the time is 8 - 16 h; During the second curing treatment, the temperature is 60 - 80 °C and the time is 8 - 16 h; During the third curing treatment, the temperature is 80 - 100 °C and the time is 8 - 16 h.

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