Diopside crystal glaze with radiation refrigeration function as well as preparation method and application of diopside crystal glaze

Abstract

The invention discloses diopside crystal glaze with a radiation refrigeration function as well as a preparation method and application of the diopside crystal glaze. The diopside crystal glaze is prepared from the following components in percentage by weight: 25 to 67 percent of SiO2, 2 to 12 percent of Al2O3, 5 to 13 percent of MgO, 8 to 16 percent of CaO, 3 to 6 percent of K2O3, 0.5 to 3 percent of Na2O, 1 to 5 percent of P2O5 and 3 to 6 percent of ZnO. A nanoscale split-phase structure and a multistage dispersion structure of micron-sized long-rod-shaped diopside microcrystals exist in the obtained glaze layer body, the diopside crystals are in a long-rod shape, the average diameter is 0.2-2 microns, and the glaze layer body has a strong Mie scattering effect on sunlight. The glaze layer has a good radiation refrigeration effect, the solar radiation reflectivity reaches 92% or above, and the atmospheric window infrared emissivity reaches 0.90 or above.

Description

Technical Field

[0001] This invention belongs to the field of building ceramics technology, specifically relating to a diopside crystalline glaze with radiative cooling function, its preparation method, and its application. Background Technology

[0002] As global warming intensifies, residents' demand for indoor cooling continues to rise. Currently, active cooling methods, mainly based on traditional air conditioning systems, rely on electricity, which accounts for about 10% of global energy consumption. This not only leads to significant carbon emissions but also further exacerbates global warming and the urban heat island effect.

[0003] Radiative cooling is a passive cooling method that requires no energy consumption. It relies on the intrinsic optical properties of materials to emit heat into outer space through atmospheric windows (8–13 μm) via thermal radiation, while simultaneously reducing the absorption of solar radiation (0.3–2.5 μm), thus achieving a cooling effect. Ceramic tiles are widely used building envelope materials in modern architecture, offering good weather resistance and easy construction, making them an ideal carrier for planned radiative cooling applications. However, current technologies for radiative cooling ceramics mainly rely on complex nanostructures or precious metal additives, resulting in complex processes, high costs, and difficulties in achieving large-scale production and widespread application using existing ceramic production lines.

[0004] Existing radiation-cooled ceramic materials mostly rely on functional powders to improve optical properties. For example, Chinese invention patent CN117756409A uses diatomaceous earth-supported mesoporous alumina, and CN119591321A uses nanoporous alumina and spinel doping to enhance scattering. The key raw materials used in these technologies are expensive, and the manufacturing process is complex, limiting their application in ordinary buildings. Chinese invention patent CN119822869A discloses a radiation-cooled exterior wall tile and its manufacturing process. By adding "cooling powder" to the glaze layer to improve reflection and emission capabilities, the ceramic tile adopts a double-glaze structure and uses Ba-containing raw materials with high refractive index, increasing the cost of raw materials and processes.

[0005] It is evident that existing radiative cooling ceramic technologies generally suffer from high raw material costs, difficulties in process control, and incompatibility with traditional ceramic production lines, hindering their rapid large-scale production in the building ceramics sector. Therefore, there is an urgent need to develop a building radiative cooling material that combines high performance and low cost to meet the demands of green building and sustainable development. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a diopside crystalline glaze with radiation cooling function, exhibiting an average reflectance greater than 92% in the solar spectrum (300–2500 nm) and a near-infrared emissivity exceeding 0.90 within the atmospheric window (8–13 μm), as well as a method for its preparation.

[0007] Another object of the present invention is to provide the application of the aforementioned diopside crystalline glaze with radiation cooling function in building ceramics.

[0008] To achieve the above objectives, the present invention is implemented through the following technical solutions.

[0009] A diopside crystalline glaze with radiation cooling function is prepared from raw materials comprising the following components:

[0010] SiO2: 58-67 wt%;

[0011] Al2O3: 2-12 wt%;

[0012] MgO: 5–13 wt%;

[0013] CaO: 8–16 wt%;

[0014] K2O: 3-6 wt%;

[0015] Na2O: 0.5–3 wt%;

[0016] P2O5: 1-5 wt%;

[0017] ZnO: 3-6 wt%;

[0018] The sum of all the components is 100%;

[0019] The crystal phase is mainly columnar diopside crystals; the diopside crystalline glaze glass matrix contains a nanoscale phase separation structure and a multi-level dispersion structure of micron-sized long rod-shaped diopside microcrystals.

[0020] To further achieve the purpose of this invention, preferably, the diopside crystal is in the shape of a long rod or column, and the crystal diameter is 0.2 to 2 μm.

[0021] Preferably, the diopside crystalline glaze has a solar radiation reflectivity greater than 92% in the 0.3–2.5 μm band and an emissivity greater than 0.9 in the atmospheric window infrared region in the 8–13 μm band.

[0022] The preparation method of the diopside crystalline glaze with radiation cooling function includes the following steps:

[0023] S1: Weigh the raw materials according to the mass fractions of the raw material components. The raw materials are selected from a combination of quartz, alumina, magnesium oxide, calcium carbonate, potassium carbonate, sodium carbonate, calcium phosphate, zinc oxide, potassium feldspar, sodium feldspar, kaolin, wollastonite, and talc. The combination of raw materials meets the composition requirements of diopside crystalline glaze.

[0024] S2: After the raw materials are mixed evenly, they are pre-calcined at 700-1000℃ for 0.5-4 hours. After cooling, the calcined product is ball-milled to obtain glaze powder with uniform fineness.

[0025] S3: Add additives to the glaze powder, add water and ball mill to obtain a stable glaze slurry;

[0026] S4: Apply the glaze slurry to the surface of the ceramic body, dry it, and then fire it at 1050-1250℃ to obtain the diopside crystalline glaze with radiation cooling function.

[0027] Preferably, in step S1, the purity of the raw material is not less than 98%, and it is pretreated by drying at 150-220°C for 2-6 hours before weighing.

[0028] Preferably, in step S3, the ball milling speed is 300-500 rpm and the time is 20-60 min.

[0029] Preferably, in step S3, the glaze slurry passes through a 200-mesh sieve, and the residue on the sieve is less than 0.15 wt%.

[0030] Preferably, in step S3, the additive is selected from one or more of sodium tripolyphosphate, sodium hexametaphosphate, sodium carboxymethyl cellulose, and polyvinyl alcohol.

[0031] Preferably, 0.1 to 0.5 parts by weight of additives are added to every 100 parts by weight of glaze powder.

[0032] Application of the diopside crystalline glaze with radiation cooling function in building ceramics: The diopside crystalline glaze with radiation cooling function is applied to the surface of the ceramic substrate, and the thickness of the glaze layer after firing is 0.2 to 1.5 mm.

[0033] Compared with the prior art, the present invention has the following beneficial technical effects:

[0034] 1) The diopside crystalline glaze of the present invention has a radiation cooling function. In terms of radiation cooling function, the diopside crystalline glaze has an average reflectivity of more than 92% in the solar spectrum (300-2500nm) range and a near-infrared emissivity of more than 0.90 in the atmospheric window (8-13μm), showing excellent radiation cooling performance and energy saving potential.

[0035] 2) The diopside crystalline glaze obtained by this invention has high crystallinity and moderate grain diameter, which significantly enhances the scattering effect of sunlight. At the same time, it has good sintering density and glaze adhesion, meeting the mechanical performance requirements of building ceramics.

[0036] 3) The raw material cost of this invention is low, the process flow is compatible with traditional ceramic tile production, and it has good industrial adaptability; it is suitable for the large-scale preparation of building ceramic tiles with radiant cooling function and has good energy-saving effect. Attached Figure Description

[0037] Figure 1 The X-ray diffraction pattern of the diopside crystalline glaze in Example 1;

[0038] Figure 2 This is a scanning electron microscope image of the diopside crystalline glaze of Example 1;

[0039] Figure 3 The solar reflectance and infrared emissivity spectra of the diopside crystalline glaze of Example 1 are shown. Detailed Implementation

[0040] To better understand the present invention, it will be further described below with reference to the accompanying drawings and specific embodiments. However, the implementation of the present invention is not limited thereto. The described embodiments are some, but not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] In the following embodiments and comparative examples of the present invention, a uniform testing method was used to characterize the optical properties of the samples:

[0042] Solar radiation reflectance test: The test was conducted using a PerkinElmer Lambda 950s ultraviolet-visible-near-infrared spectrophotometer equipped with an integrating sphere attachment, with a test wavelength of 0.3 to 2.5 μm. The average reflectance was calculated according to the standard GB / T 2680-2021.

[0043] Atmospheric window average emissivity test: The test was conducted using a Fourier transform infrared spectrometer (ThermoScientific Nicolet iS50 FTIR) equipped with an integrating sphere, with a test band of 2.5–25 μm. The average emissivity within the atmospheric window (8–13 μm) was calculated according to standard GB / T 30127-2013.

[0044] Example 1

[0045] A diopside crystalline glaze with radiative cooling function is composed of the following components in weight fractions: SiO2: 61.00%, Al2O3: 6.46%, MgO: 5.42%, CaO: 13.32%, K2O: 4.93%, Na2O: 0.99%, P2O5: 3.94%, ZnO: 3.94%.

[0046] Based on the above formula, the raw material formula used in this embodiment is calculated as follows: 55.6 parts by weight of quartz, 5.9 parts by weight of alumina, 4.9 parts by weight of magnesium oxide, 14.1 parts by weight of calcium carbonate, 6.6 parts by weight of potassium carbonate, 1.5 parts by weight of sodium carbonate, 7.8 parts by weight of calcium phosphate, and 3.6 parts by weight of zinc oxide, all dried at 180℃ for 4 hours. After being mixed evenly, the mixture is calcined at 900℃ for 2 hours and then ball-milled again to obtain glaze powder. The glaze powder is ball-milled and mixed with 100g of glaze powder, 0.3g of sodium carboxymethyl cellulose, 0.3g of sodium tripolyphosphate, and 72ml of water. After passing through a 200-mesh sieve, a glaze slurry is obtained. The glaze is applied by spraying, dried, and then placed in a box furnace. It is heated to 1150℃ at a heating rate of 10℃ / min, held for 30 minutes, and then cooled with the furnace to obtain a diopside crystalline glaze with radiative cooling function.

[0047] X-ray diffraction analysis was performed on the crystalline glaze obtained in this embodiment, and the results are as follows: Figure 1 As shown. By Figure 1 As can be seen, the phase composition of the crystalline glaze is mainly diopside, with a small amount of quartz. The scanning electron microscope (SEM) image of the crystalline glaze obtained in this example after etching with 5 wt% HF solution for 60 seconds is shown below. Figure 2 As shown. By Figure 2 As can be seen in a, its crystal phase is mainly columnar diopside crystals, with a crystal length of about 5 μm and a diameter ranging from 0.2 to 2 μm. This diameter range falls precisely within the optimal size range for Mie scattering in the solar radiation band (0.3–2.5 μm), enabling it to scatter sunlight extremely effectively. Figure 2 A clear liquid-liquid phase separation is visible in sample b. This is because the P2O5 introduced into the formulation induces the separation of the phosphorus-rich phase and the silicon-rich phase during cooling, forming a nanoscale droplet structure. This nanoscale phase separation, together with the micron-sized diopside crystals, constitutes a nano-micron multi-level dispersion structure, further enhancing the scattering ability of short-wavelength light. Solar reflectance and infrared emissivity spectra are shown below. Figure 3 As shown, from Figure 3 It can be seen that the diopside crystalline glaze of this embodiment has a solar radiation reflectance of 96% in the 0.3-2.5μm band and an emissivity greater than 0.91 in the mid-infrared region in the 8-13μm band.

[0048] Example 2

[0049] The diopside crystalline glaze with radiation cooling function in this embodiment is composed of the following components by weight fraction: SiO2: 61.00%, Al2O3: 6.46%, MgO: 5.42%, CaO: 13.32%, K2O: 4.93%, Na2O: 0.99%, P2O5: 3.94%, ZnO: 3.94%.

[0050] Based on the above formula, the raw material formula used in this embodiment is calculated as follows: 42.6 parts potassium feldspar, 17.6 parts wollastonite, 16.0 parts talc, 6.9 parts sodium feldspar, 8.6 parts calcium phosphate, 4.4 parts quartz, and 3.9 parts zinc oxide, all dried at 160℃ for 6 hours. After being mixed evenly, the mixture is calcined at 700℃ for 4 hours and then ball-milled again to obtain glaze powder. The glaze powder is ball-milled and mixed in a ratio of 100g glaze powder, 0.15g sodium carboxymethyl cellulose, 0.15g sodium tripolyphosphate, and 72ml water, and then passed through a 200-mesh sieve to obtain a glaze slurry. The glaze is applied by spraying, dried, and then placed in a box furnace. It is heated to 1220℃ at a heating rate of 10℃ / min, held for 10 minutes, and then cooled with the furnace to obtain a diopside crystalline glaze with radiative cooling function.

[0051] Example 3

[0052] The diopside crystalline glaze with radiation cooling function in this embodiment is composed of the following components by weight fraction: SiO2: 65.37%, Al2O3: 2.78%, MgO: 5.23%, CaO: 12.70%, K2O: 4.97%, Na2O: 0.99%, P2O5: 3.98%, ZnO: 3.98%.

[0053] Based on the above formula, the raw material formula used in this embodiment is calculated as follows: 59.8 parts by weight of quartz, 2.5 parts by weight of alumina, 4.8 parts by weight of magnesium oxide, 13.1 parts by weight of calcium carbonate, 6.7 parts by weight of potassium carbonate, 1.6 parts by weight of sodium carbonate, 7.9 parts by weight of calcium phosphate, and 3.6 parts by weight of zinc oxide, all dried at 180℃ for 4 hours. After being mixed evenly, the mixture is calcined at 1000℃ for 3 hours and then ball-milled again to obtain glaze powder. The glaze powder is ball-milled and mixed with 0.3g of sodium carboxymethyl cellulose, 0.3g of sodium tripolyphosphate, and 72ml of water, and then passed through a 200-mesh sieve to obtain a glaze slurry. The glaze is applied by spraying, dried, and then placed in a box furnace. It is heated to 1050℃ at a heating rate of 10℃ / min, held for 10 minutes, and then cooled with the furnace to obtain a diopside crystalline glaze with radiative cooling function.

[0054] Example 4

[0055] The diopside crystalline glaze with radiation cooling function in this embodiment is composed of the following components by weight fraction: SiO2: 58.98%, Al2O3: 6.25%, MgO: 9.06%, CaO: 11.59%, K2O: 5.04%, Na2O: 1.01%, P2O5: 4.03%, ZnO: 4.03%.

[0056] Based on the above formula, the raw material formula used in this embodiment is calculated as follows: 54.4 parts by weight of quartz, 5.8 parts by weight of alumina, 8.4 parts by weight of magnesium oxide, 11.2 parts by weight of calcium carbonate, 6.8 parts by weight of potassium carbonate, 1.6 parts by weight of sodium carbonate, 8.1 parts by weight of calcium phosphate, and 3.7 parts by weight of zinc oxide, all dried at 180℃ for 4 hours. After being mixed evenly, the mixture is calcined at 900℃ for 2 hours and then ball-milled again to obtain glaze powder. The glaze powder is ball-milled and mixed with 100g of glaze powder, 0.3g of sodium carboxymethyl cellulose, 0.3g of sodium tripolyphosphate, and 72ml of water, and then passed through a 200-mesh sieve to obtain a glaze slurry. The glaze is applied by spraying, dried, and then placed in a box furnace. It is heated to 1250℃ at a heating rate of 10℃ / min, held at that temperature for 10 minutes, and then cooled with the furnace to obtain a diopside crystalline glaze with radiative cooling function.

[0057] Comparative Example 1 (without P)

[0058] The diopside crystalline glaze of this comparative example is composed of the following components in weight fractions: SiO2: 64.62%, Al2O3: 6.82%, MgO: 5.36%, CaO: 13.01%, K2O: 5.10%, Na2O: 1.02%, ZnO: 4.08%.

[0059] Based on the above formula, the raw material formula used in this embodiment is calculated as follows: 57.0 parts by weight of quartz, 6.0 parts by weight of alumina, 4.7 parts by weight of magnesium oxide, 20.5 parts by weight of calcium carbonate, 6.6 parts by weight of potassium carbonate, 1.5 parts by weight of sodium carbonate, and 3.6 parts by weight of zinc oxide, all dried at 160℃ for 6 hours. After being mixed evenly, the mixture is calcined at 900℃ for 2 hours and then ball-milled again to obtain glaze powder. The glaze is then ball-milled and mixed with 100g of glaze powder, 0.3g of sodium carboxymethyl cellulose, 0.3g of sodium tripolyphosphate, and 72ml of water, and passed through a 200-mesh sieve to obtain a glaze slurry. The glaze is applied by spraying, dried, and then placed in a box furnace. It is heated to 1220℃ at a heating rate of 10℃ / min, held at that temperature for 15 minutes, and then cooled with the furnace to obtain a diopside crystalline glaze.

[0060] Comparative Example 2 (High Al, Low Si)

[0061] The diopside crystalline glaze of this comparative example is composed of the following components by weight fraction: SiO2: 52.34%, Al2O3: 17.80%, MgO: 4.90%, CaO: 11.90%, K2O: 4.66%, Na2O: 0.93%, P2O5: 3.73%, ZnO: 3.73%.

[0062] Based on the above formula, the raw material formula used in this embodiment is calculated as follows: 48.1 parts by weight of quartz, 16.4 parts by weight of alumina, 4.5 parts by weight of magnesium oxide, 12.3 parts by weight of calcium carbonate, 6.3 parts by weight of potassium carbonate, 1.5 parts by weight of sodium carbonate, 7.5 parts by weight of calcium phosphate, and 3.4 parts by weight of zinc oxide, all dried at 160℃ for 6 hours. After being mixed evenly, the mixture is calcined at 900℃ for 2 hours and then ball-milled again to obtain glaze powder. The glaze is ball-milled and mixed with 100g of glaze powder, 0.3g of sodium carboxymethyl cellulose, 0.3g of sodium tripolyphosphate, and 72ml of water, and then passed through a 200-mesh sieve to obtain a glaze slurry. The glaze is applied by spraying, dried, and then placed in a box furnace. It is heated to 1220℃ at a heating rate of 10℃ / min, held at that temperature for 15 minutes, and then cooled with the furnace to obtain a diopside crystalline glaze.

[0063] Comparative Example 3 (Low CaMg)

[0064] The crystalline glaze of this comparative example is composed of the following components in weight fractions: SiO2: 66.71%, Al2O3: 7.49%, MgO: 4.37%, CaO: 6.12%, K2O: 5.47%, Na2O: 1.09%, P2O5: 4.37%, ZnO: 4.37%.

[0065] Based on the above formula, the raw material formula used in this embodiment is calculated as follows: 64.1 parts by weight of quartz, 7.2 parts by weight of alumina, 4.2 parts by weight of magnesium oxide, 1.6 parts by weight of calcium carbonate, 7.7 parts by weight of potassium carbonate, 1.8 parts by weight of sodium carbonate, 9.2 parts by weight of calcium phosphate, and 4.2 parts by weight of zinc oxide, all dried at 160℃ for 6 hours. After being mixed evenly, the mixture is calcined at 900℃ for 2 hours and then ball-milled again to obtain glaze powder. The glaze powder is ball-milled and mixed with 100g of glaze powder, 0.3g of sodium carboxymethyl cellulose, 0.3g of sodium tripolyphosphate, and 72ml of water. After passing through a 200-mesh sieve, a glaze slurry is obtained. The glaze is applied by spraying, dried, and then placed in a box furnace. It is heated to 1220℃ at a heating rate of 10℃ / min, held at that temperature for 15 minutes, and then cooled with the furnace to obtain a diopside crystalline glaze.

[0066] Comparative Example 4

[0067] This comparative example uses commercially available white glazed ceramic building tiles as the comparison sample. The sample was purchased from a building materials market and is a common zirconium white glaze product. Its surface is white with no obvious defects, its whiteness is 78.47, and its surface gloss is 22.9.

[0068] The optical performance test data of each embodiment and comparative example are summarized in Table 1.

[0069] Table 1 Optical performance test results

[0070] Group Solar radiation reflectivity (0.3–2.5 μm) Infrared emissivity (8–13 μm) Example 1 96.0％ 0.912 Example 2 94.3％ 0.908 Example 3 92.0％ 0.915 Example 4 93.2％ 0.911 Comparative Example 1 89.2％ 0.867 Comparative Example 2 87.2％ 0.854 Comparative Example 3 88.7％ 0.831 Comparative Example 4 78.0％ 0.831

[0071] As shown in Table 1, the diopside crystalline glazes prepared in Examples 1-4 exhibit a solar radiation reflectance of over 92% and an infrared emissivity of over 0.90, demonstrating excellent radiative cooling effects. Comparative Example 1, lacking P2O5, could not induce liquid phase separation to lower the nucleation barrier, resulting in a glaze layer dominated by the glass phase and lacking microcrystalline scattering centers. Comparative Example 2, with its excessively high aluminum content, experienced a sharp increase in high-temperature viscosity, severely hindering the diffusion of crystal-forming ions and suppressing the growth kinetics of diopside crystals. Comparative Example 3, with its calcium and magnesium content below the theoretical stoichiometry of diopside, lacked necessary crystal framework components, limiting the total amount of crystallization. All of these factors significantly weakened the Mie scattering effect and infrared emissivity. Compared to commercially available white ceramic tiles (Comparative Example 4, reflectance 78.0%), this invention drastically reduced the solar radiation absorption rate from 22% of ordinary products to 4%, reducing heat radiation input by nearly 80%. Meanwhile, the infrared emissivity of the diopside crystalline glazes prepared in Examples 1 to 4 all reached above 0.90, which is better than the 0.831 of commercially available samples. They can more efficiently utilize the atmospheric transparent window of 8 to 13 μm to emit heat into the cold outer space in the form of thermal radiation, and have significant advantages in radiation cooling.

[0072] This invention relates to a diopside crystalline glaze with radiative cooling function, which can be applied in building ceramics. The glaze is applied to the surface of a ceramic substrate, with the thickness of the glaze layer after firing controlled to be 0.2–1.5 mm. Compared to existing polymer-based radiative cooling coatings, this invention uses an inorganic ceramic material system, exhibiting superior weather resistance and fire resistance. It effectively improves upon the shortcomings of organic coatings, such as aging, peeling, and reflectivity attenuation due to dust accumulation during long-term outdoor service, demonstrating excellent long-term stability. Therefore, this crystalline glaze has broad application prospects in the field of green building envelope structures, significantly reducing building surface temperature and effectively reducing air conditioning energy consumption.

[0073] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A diopside crystalline glaze with radiation cooling function, characterized in that, The raw materials include the following components: SiO2: 58-67 wt%; Al2O3: 2-12 wt%; MgO: 5–13 wt%; CaO: 8–16 wt%; K2O: 3-6 wt%; Na2O: 0.5–3 wt%; P2O5: 1-5 wt%; ZnO: 3-6 wt%; The sum of all the components is 100%; The crystal phase is mainly columnar diopside crystals; the diopside crystalline glaze glass matrix contains a nanoscale phase separation structure and a multi-level dispersion structure of micron-sized long rod-shaped diopside microcrystals.

2. The diopside crystalline glaze with radiation cooling function according to claim 1, characterized in that, The diopside crystals are long rod-shaped or columnar, with a diameter of 0.2–2 μm.

3. The diopside crystalline glaze with radiation cooling function according to claim 1, characterized in that, The diopside crystalline glaze has a solar radiation reflectance of greater than 92% in the 0.3–2.5 μm band and an emissivity of greater than 0.9 in the atmospheric window infrared region in the 8–13 μm band.

4. The method for preparing diopside crystalline glaze with radiation cooling function as described in claim 1, characterized in that, Includes the following steps: S1: Weigh the raw materials according to the mass fractions of the raw material components. The raw materials are selected from a combination of quartz, alumina, magnesium oxide, calcium carbonate, potassium carbonate, sodium carbonate, calcium phosphate, zinc oxide, potassium feldspar, sodium feldspar, kaolin, wollastonite, and talc. The combination of raw materials meets the composition requirements of diopside crystalline glaze. S2: After the raw materials are mixed evenly, they are pre-calcined at 700-1000℃ for 0.5-4 hours. After cooling, the calcined product is ball-milled to obtain glaze powder with uniform fineness. S3: Add additives to the glaze powder, add water and ball mill to obtain a stable glaze slurry; S4: Apply the glaze slurry to the surface of the ceramic body, dry it, and then fire it at 1050-1250℃ to obtain the diopside crystalline glaze with radiation cooling function.

5. The method for preparing diopside crystalline glaze with radiation cooling function according to claim 4, characterized in that, In step S1, the purity of the raw material is not less than 98%, and it is pretreated by drying at 150-220℃ for 2-6 hours before weighing.

6. The method for preparing diopside crystalline glaze with radiation cooling function according to claim 4, characterized in that, In step S3, the ball milling speed is 300-500 rpm and the time is 20-60 min.

7. The method for preparing diopside crystalline glaze with radiation cooling function according to claim 4, characterized in that, In step S3, the glaze slurry is passed through a 200-mesh sieve, and the residue on the sieve is less than 0.15 wt%.

8. The method for preparing diopside crystalline glaze with radiation cooling function according to claim 4, characterized in that, Step S3, wherein the additive is selected from one or more of sodium tripolyphosphate, sodium hexametaphosphate, sodium carboxymethyl cellulose and polyvinyl alcohol.

9. The method for preparing diopside crystalline glaze with radiation cooling function according to claim 8, characterized in that, For every 100 parts by weight of glaze powder, add 0.1 to 0.5 parts by weight of additives.

10. The application of the diopside crystalline glaze with radiation cooling function according to any one of claims 1-3 in building ceramics, characterized in that, The diopside crystalline glaze with radiation cooling function is applied to the surface of a ceramic substrate, and the thickness of the glaze layer after firing is 0.2 to 1.5 mm.

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