Electroless refrigeration ceramic and preparation method thereof

Abstract

The invention belongs to the technical field of ceramics, and discloses an electroless refrigeration ceramic and a preparation method thereof.The electroless refrigeration ceramic is prepared from, by mass, 45-60% of first kaolin, 8-20% of second kaolin, 27-40% of feldspar and 3-5% of calcined talc, the first kaolin is modified kaolin, the aluminum oxide mass content of the modified kaolin is larger than or equal to 99%, the blue light whiteness is larger than 95 degrees, and the second kaolin is modified kaolin; the blue light whiteness of the second kaolin is greater than 85 degrees, and the feldspar comprises potassium feldspar. The blue light whiteness of the prepared electroless refrigeration ceramic is larger than or equal to 90 degrees, the whole body white effect is achieved, the electroless refrigeration ceramic has high reflectivity to sunlight, and the electroless refrigeration ceramic can reflect most of solar heat radiation, meanwhile, can emit 8-13 microns of infrared bands, guides ground surface heat to space and achieves the passive refrigeration effect.

Description

Technical Field

[0001] The present invention belongs to the technical field of ceramics, and in particular relates to a non-electric refrigeration ceramic and a preparation method thereof. Background Art

[0002] Non-electric cooling ceramics are a new type of inorganic material based on the principle of passive radiative cooling. They require no external energy and generally do not significantly increase the surface temperature of the ceramic even under direct sunlight. When used as building materials, such as exterior wall tiles or roofing materials, cooling ceramics can help lower indoor temperatures.

[0003] The performance of cooling ceramic products is related to the blue light whiteness of their surface. Currently, in the ceramic industry, tiles with a blue light whiteness of 45-50 degrees are called white tiles. Ceramic tiles with a blue light whiteness of 65 degrees are rare, and tiles with a blue light whiteness of 80 degrees or above are generally achieved by applying a glaze or coating to the surface. For example, Chinese invention patent publication number CN119822869A discloses a radiant cooling exterior wall tile and its preparation process. By adjusting the composition ratio of the base glaze layer and the protective glaze layer and adding a cooling powder for compounding, the reflectance and emissivity of infrared and visible light are improved. Chinese invention patent publication number CN114672205A discloses a radiant cooling coating and surface coating method, proposing a coating with a porous structure that reflects solar radiation. It can be seen that existing cooling ceramics primarily achieve their cooling function through coating or glazing; the ceramic itself does not truly reflect solar radiation. However, the glaze or coating easily falls off the ceramic surface during long-term use, greatly limiting the use of cooling ceramics. Based on this, the present invention proposes a new type of non-electric cooling ceramic and its preparation method to address the above problems. Summary of the Invention

[0004] In order to solve the above technical problems, the purpose of the present invention is to provide a non-electric cooling ceramic and a preparation method thereof. The blue light whiteness of the non-electric cooling ceramic is ≥90 degrees, achieving a white effect throughout the body, and has a high reflectivity to sunlight. While reflecting most of the solar thermal radiation, it can emit an 8-13μm infrared band, directing surface heat into space, achieving a passive cooling effect.

[0005] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is as follows: In the first aspect of the present invention, the present invention proposes a non-electric refrigeration ceramic. Calculated by mass percentage, the preparation raw materials include 45-60% of a first kaolin, 8-20% of a second kaolin, 27-40% of feldspar and 3-5% of calcined talc, wherein the first kaolin is modified kaolin, the modified kaolin has an aluminum oxide mass content of ≥99%, a blue light whiteness of >95 degrees, and the second kaolin has a blue light whiteness of >85 degrees.

[0006] Preferably, the first kaolin preparation method is as follows: Select kaolin ore with kaolin content greater than 40%, crush the kaolin ore, and obtain concentrate through water washing and classification; The concentrate is mixed with a chlorinating agent, calcined at 1350-1400°C for 1-3 hours, the calcined material is mixed with a decolorizing agent for reaction for 1-2 hours, the decolorized material is mixed with a silicon dissolving agent for reaction for 3-5 hours, and after the reaction, aluminum hydroxide seed crystals are added to precipitate to obtain a precipitate; The precipitate is calcined at 1100-1400°C for 2-4 hours, and water is added to the calcined material to prepare a slurry with a solid content of 20-30%. A dispersant is added, and the dispersant accounts for 0.5-1% of the slurry mass. The slurry is ground to make the median particle size ≤100nm to prepare modified kaolin.

[0007] More preferably, the content of Al2O3 corundum phase, i.e., α-alumina phase, in the first kaolin is ≥99.0%.

[0008] More preferably, the near-infrared reflectivity of the first kaolin is greater than 99.0%.

[0009] Preferably, the mass content of ferric oxide in the second kaolin is less than 0.3%.

[0010] Preferably, the total mass content of potassium and sodium in feldspar is ≥7.0%, and the sodium content is ≤3%.

[0011] More preferably, the potassium content of the feldspar is ≥10% by mass.

[0012] More preferably, the feldspar is potassium feldspar, or the feldspar includes potassium feldspar and sodium feldspar.

[0013] Preferably, the blue light whiteness of the calcined talc after calcination at 1200° C. is greater than 70 degrees.

[0014] In a second aspect of the present invention, the present invention provides a method for preparing a non-electric refrigeration ceramic, as follows: S1, mixing the first kaolin, the second kaolin, feldspar and calcined talc to form a mixed material; S2. calcining the mixed material to produce non-electric refrigeration ceramics, wherein the calcination curve is as follows: The mixed material is heated from room temperature to 1270-1300°C for 45-60 minutes, and kept at 1270-1300°C for 45-60 minutes.

[0015] Beneficial effects

[0016] The blue light whiteness of the non-electric cooling ceramic produced by the present invention is ≥90 degrees, achieving a completely white effect. It has a high reflectivity to sunlight and can emit 8-13μm infrared band while reflecting most of the solar thermal radiation, directing surface heat into space to achieve a passive cooling effect. DETAILED DESCRIPTION

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the specific implementation methods of the present invention will be described below. Obviously, the following descriptions are only some embodiments of the present invention. For those skilled in the art, other implementation methods can be obtained based on these embodiments without inventive work.

[0018] The present invention provides a non-electric refrigeration ceramic. The preparation raw materials include, calculated by mass percentage, 45-60% of a first kaolin, 8-20% of a second kaolin, 27-40% of feldspar and 3-5% of calcined talc. The first kaolin is modified kaolin, the modified kaolin has an aluminum oxide mass content of ≥99%, a blue light whiteness of >95 degrees, and a near-infrared reflectivity of >99.0%. The second kaolin has an iron oxide mass content of <0.3%, and a blue light whiteness of >85 degrees.

[0019] In the present invention, the blue light whiteness of the first kaolin and the second kaolin is measured based on existing test conditions and test methods. In the present invention, the first kaolin is beneficial for improving the blue light whiteness and solar reflectance of the final ceramic product, while the second kaolin improves plasticity. It should be noted that the first kaolin of the present invention improves the performance of the ceramic product based on its own characteristics. In theory, any first kaolin that meets the above requirements is suitable for the present invention. The present invention also proposes a method for preparing the first kaolin, as follows: Select kaolin ore with kaolin content greater than 40%, crush the kaolin ore, and obtain concentrate through water washing and classification; The concentrate is mixed with a chlorinating agent, calcined at 1350-1400°C for 1-3 hours, the calcined material is mixed with a decolorizing agent for reaction for 1-2 hours, the decolorized material is mixed with a silicon dissolving agent for reaction for 3-5 hours, and after the reaction, aluminum hydroxide seed crystals are added to precipitate to obtain a precipitate; The precipitate is calcined at 1100-1400°C for 2-4 hours, and water is added to the calcined material to prepare a slurry with a solid content of 20-30%. A dispersant is added, and the dispersant accounts for 0.5-1% of the slurry mass. The slurry is ground to make the median particle size ≤100nm to prepare modified kaolin.

[0020] The chlorinating agent includes one or more of calcium chloride, magnesium chloride, and ammonium chloride; and the silicon dissolving agent includes one or more of sodium hydroxide, potassium hydroxide, and sodium carbonate.

[0021] The first kaolin prepared by the present invention has high alumina content and nano-fineness, with an aluminum oxide content of ≥99% and high whiteness after re-firing at 1200°C, for example, blue light whiteness after firing at 1200°C is greater than 95 degrees, and near-infrared reflectivity is greater than 99.0%.

[0022] In the present invention, the second kaolin is commercially available kaolin, which is required to have good plasticity, good mud suspension, and high blue light whiteness after firing at 1200°C, for example, blue light whiteness >85 degrees after firing at 1200°C, and the mass content of ferric oxide is required to be <0.3%.

[0023] In the present invention, feldspar refers to feldspar having a combined potassium and sodium content of ≥7.0% by weight and sodium ≤3%. For example, the feldspar may be potassium feldspar, or the feldspar may include potassium feldspar and sodium feldspar. Preferably, the potassium content of the feldspar is ≥10% by weight. A high potassium content facilitates widening the firing temperature range during high-temperature firing. More preferably, the feldspar has a particle size of ≤74 μm.

[0024] In the present invention, the calcined talc is a conventional calcined talc available on the market, and the blue light whiteness after calcination at 1200° C. is greater than 70 degrees.

[0025] Based on the raw material composition of the above-mentioned non-electric refrigeration ceramic, the present invention also proposes a preparation method of the non-electric refrigeration ceramic, as follows: S1, mixing the first kaolin, the second kaolin, feldspar and calcined talc to form a mixed material; S2. calcining the mixed material to produce non-electric refrigeration ceramics, wherein the calcination curve is as follows: The mixed material is heated from room temperature to 1270-1300°C for 45-60 minutes, and kept at 1270-1300°C for 45-60 minutes.

[0026] The blue light whiteness of the non-electric cooling ceramic produced by the present invention is ≥90 degrees, achieving a completely white effect. It has a high reflectivity to sunlight and can emit 8-13μm infrared band while reflecting most of the solar thermal radiation, directing surface heat into space to achieve a passive cooling effect.

[0027] The water absorption rate of the non-electric refrigeration ceramic prepared by the present invention is ≤0.5%. The ceramic product achieves a cooling effect by reflecting sunlight when paved outdoors. The ceramic product has low water absorption rate, strong weather resistance, and good freeze-thaw resistance and anti-fouling properties.

[0028] The technical solution of the present invention is described in detail below with reference to specific embodiments.

[0029] In the following examples and comparative examples, the chemical composition of the raw materials and the blue light whiteness after sintering at 1200°C are as follows: First Kaolin: Select kaolin ore with kaolin content greater than 40%, crush the kaolin ore, and obtain concentrate through water washing and classification; The concentrate is mixed with calcium chloride, calcined at 1400°C for 2 hours, the calcined material is mixed with a decolorizer for 2 hours, the decolorized material is mixed with sodium hydroxide for 4 hours, and after the reaction, aluminum hydroxide seeds are added to precipitate to obtain a precipitate. The precipitate was calcined at 1200℃ for 3 hours, and water was added to the calcined material to prepare a slurry with a solid content of 30%. A dispersant was added, and the dispersant accounted for 0.5-1% of the slurry mass. The slurry was ground to make the median particle size ≤100 nm to prepare modified kaolin.

[0030] Calculated by mass percentage, aluminum oxide is 99.27%, silicon dioxide is less than 0.01%, iron oxide is less than 0.01%, calcium oxide is less than 0.01%, magnesium oxide is less than 0.01%, potassium oxide is less than 0.01%, sodium oxide is less than 0.06%, titanium dioxide is less than 0.01%, and the loss on ignition is 0.33%, with the remainder being impurities. First Kaolin, after calcination at 1200°C, has a blue light whiteness of 97.13 degrees. The Al2O3 corundum phase, or α-alumina phase, in First Kaolin reaches 99.0%, and the amorphous phase content is 1.0%.

[0031] Conventional alumina: Calculated by mass percentage, aluminum oxide 98.80%, silicon dioxide 0.01%, ferric oxide 0.01%, calcium oxide <0.01%, magnesium oxide <0.01%, potassium oxide <0.01%, sodium oxide 0.45%, titanium dioxide <0.01%, loss on ignition 0.33%, the remainder being impurities. Conventional alumina, after calcining at 1200°C, has a blue light whiteness of 90.25 degrees.

[0032] Second-grade kaolin: Calculated by mass, the following components are: aluminum oxide 32.38%, silicon dioxide 53.56%, iron oxide 0.27%, calcium oxide 0.04%, magnesium oxide 0.11%, potassium oxide 1.01%, sodium oxide 0.62%, titanium dioxide 0.04%, loss on ignition 11.65%, the remainder being impurities. After calcination at 1200°C, the second-grade kaolin has a blue light whiteness of 87.03 degrees. K75 kaolin (from Foshan Guyue New Materials Co., Ltd.) can be used for this second-grade kaolin.

[0033] Laiyang kaolin: Calculated by mass, aluminum oxide (aluminum oxide) 13.27%, silicon dioxide (silicon dioxide) 70.43%, iron oxide (ferric oxide) 1.37%, calcium oxide (calcium oxide) 3.03%, magnesium oxide (magnesium oxide) 2.19%, potassium oxide (potassium oxide) 3.41%, sodium oxide (sodium oxide) 1.72%, titanium dioxide (titanium dioxide) 0.12%, loss on ignition (loss on ignition) 4.35%, with the remainder being impurities. Laiyang kaolin calcined at 1200°C has a blue light whiteness of 22.87 degrees.

[0034] Potash feldspar: Calculated by mass: aluminum oxide 18.74%, silicon dioxide 65.06%, iron oxide 0.12%, calcium oxide 0.23%, magnesium oxide 0.07%, potassium oxide 12.41%, sodium oxide 2.66%, titanium dioxide 0.01%, loss on ignition 0.40%, the remainder being impurities. Potash feldspar calcined at 1200°C has a blue light whiteness of 44.31 degrees.

[0035] Albite: Calculated by mass: 15.46% aluminum oxide, 72.86% silicon dioxide, 0.11% iron oxide, 0.92% calcium oxide, 0.27% magnesium oxide, 0.41% potassium oxide, 8.48% sodium oxide, 0.10% titanium dioxide. Loss on ignition is 1.25%, with the remainder being impurities. After calcining at 1200°C, the blue light whiteness of the albite is 42.22 degrees.

[0036] Burnt talc: Calculated by mass percentage, aluminum oxide 2.67%, silicon dioxide 60.84%, iron oxide 0.28%, calcium oxide 0.94%, magnesium oxide 33.83%, potassium oxide 0.69%, sodium oxide 0.07%, titanium dioxide 0.08%, loss on ignition 0.31%, the remainder being impurities. Burnt talc has a blue light whiteness of 71.65 degrees after being burned at 1200°C.

[0037] Example 1

[0038] S1. Calculate by mass percentage by mixing 45% of the first kaolin, 17% of the second kaolin, 35% of potassium feldspar, and 3% of calcined talc to form a mixture, ball-mill the mixture, dry the mixture, and finally press the mixture into a round cake with a diameter of 80 mm and a thickness of 10 mm. S2. calcining the mixed material to prepare a ceramic sample, wherein the calcination curve is as follows: The mixture was heated from room temperature to 1280°C for 45 min and kept at 1280°C for 60 min.

[0039] Example 2

[0040] S1. Calculate by mass percentage by mixing 50% of the first kaolin, 12% of the second kaolin, 35% of potassium feldspar, and 3% of calcined talc to form a mixture, ball-mill the mixture, dry the mixture, and finally press the mixture into a round cake with a diameter of 80 mm and a thickness of 10 mm. S2. calcining the mixed material to prepare a ceramic sample, wherein the calcination curve is as follows: The mixture was heated from room temperature to 1280°C for 45 min and kept at 1280°C for 60 min.

[0041] Example 3

[0042] S1. Calculate by mass percentage by mixing 55% of the first kaolin, 9% of the second kaolin, 33% of potassium feldspar, and 3% of calcined talc to form a mixture, ball-mill the mixture, dry the mixture, and finally press the mixture into a round cake with a diameter of 80 mm and a thickness of 10 mm. S2. calcining the mixed material to prepare a ceramic sample, wherein the calcination curve is as follows: The mixture was heated from room temperature to 1280°C for 45 min and kept at 1280°C for 60 min.

[0043] Example 4

[0044] S1. Calculate by mass percentage by mixing 60% of the first kaolin, 10% of the second kaolin, 27% of potassium feldspar, and 3% of calcined talc to form a mixture, ball-mill the mixture, dry the mixture, and finally press the mixture into a round cake with a diameter of 80 mm and a thickness of 10 mm. S2. calcining the mixed material to prepare a ceramic sample, wherein the calcination curve is as follows: The mixture was heated from room temperature to 1280°C for 45 min and kept at 1280°C for 60 min.

[0045] Comparative Example 1 Compared with Examples 1-4, the first kaolin in this comparative example is insufficient.

[0046] S1. Calculate by mass percentage by mixing 20% ​​of the first kaolin, 50% of the second kaolin, 25% of potassium feldspar, and 5% of calcined talc to form a mixture, ball-mill the mixture, dry the mixture, and finally press the mixture into a round cake with a diameter of 80 mm and a thickness of 10 mm. S2. calcining the mixed material to prepare a ceramic sample, wherein the calcination curve is as follows: The mixture was heated from room temperature to 1280°C for 45 min and kept at 1280°C for 60 min.

[0047] Comparative Example 2 Compared with Examples 1-4, this comparative example lacks the second kaolin.

[0048] S1. Calculate by mass percentage by mixing 60% first kaolin, 35% potassium feldspar, and 5% calcined talc to form a mixture, ball-mill the mixture, dry it, and finally press it into a round cake with a diameter of 80 mm and a thickness of 10 mm. S2. calcining the mixed material to prepare a ceramic sample, wherein the calcination curve is as follows: The mixture was heated from room temperature to 1280°C for 45 min and kept at 1280°C for 60 min.

[0049] Comparative Example 3 Compared with Examples 1-4, the comparative example uses Laiyang kaolin instead of the second kaolin. The ferric oxide content of Laiyang kaolin is too high, and the blue light whiteness is low after being calcined at 1200°C.

[0050] S1. Calculate by mass percentage by mixing 45% first kaolin, 17% Laiyang kaolin, 35% potassium feldspar, and 3% calcined talc to form a mixture, ball-mill the mixture, dry the mixture, and finally press the mixture into a round cake with a diameter of 80 mm and a thickness of 10 mm. S2. calcining the mixed material to prepare a ceramic sample, wherein the calcination curve is as follows: The mixture was heated from room temperature to 1280°C for 45 min and kept at 1280°C for 60 min.

[0051] Comparative Example 4 Compared with Examples 1-4, this comparative example uses conventional alumina instead of the first kaolin.

[0052] S1. 45% conventional alumina, 17% second kaolin, 35% potassium feldspar, and 3% calcined talc were mixed by mass percentage to form a mixture, which was ball-milled, dried, and pulverized, and finally pressed into a round cake with a diameter of 80 mm and a thickness of 10 mm. S2. calcining the mixed material to prepare a ceramic sample, wherein the calcination curve is as follows: The mixture was heated from room temperature to 1280°C for 45 min and kept at 1280°C for 60 min.

[0053] Comparative Example 5 Compared with Examples 1-4, the first kaolin in this comparative example is excessive and the other raw materials are insufficient.

[0054] S1. 90% of the first kaolin, 2% of the second kaolin, 3% of potassium feldspar, and 5% of calcined talc were mixed by mass percentage to form a mixture, which was ball-milled, dried, and pulverized, and finally pressed into a round cake with a diameter of 80 mm and a thickness of 10 mm. S2. calcining the mixed material to prepare a ceramic sample, wherein the calcination curve is as follows: The mixture was heated from room temperature to 1280°C for 45 min and kept at 1280°C for 60 min.

[0055] Comparative Example 6 Compared with Examples 1-4, this comparative example uses sodium feldspar instead of potassium feldspar.

[0056] S1. Calculate by mass percentage by mixing 45% of the first kaolin, 17% of the second kaolin, 35% of albite, and 3% of calcined talc to form a mixture, ball-mill the mixture, dry the mixture, and finally press the mixture into a round cake with a diameter of 80 mm and a thickness of 10 mm. S2. calcining the mixed material to prepare a ceramic sample, wherein the calcination curve is as follows: The mixture was heated from room temperature to 1280°C for 45 min and kept at 1280°C for 60 min.

[0057] The ceramic samples prepared in Examples 1-4 and Comparative Examples 1-6 were subjected to performance tests using the following methods.

[0058] Whiteness test method: Prepare the sample according to the requirements of Section 7 of GB / T 5950-2008, "Measurement of Whiteness of Building Materials and Non-metallic Mineral Products." Preheat and zero the instrument that meets the requirements. After calibration with a standard white plate, align it with the sample and measure the value.

[0059] Solar reflectance, visible light reflectance, and infrared reflectance test methods: Sample preparation and measurement shall be in accordance with GB / T 2680-1994.

[0060] Water absorption test method: Prepare specimens according to the requirements of Chapter 4 of GB / T 3810.3-2006, "Test methods for ceramic tiles, Part 3: Determination of water absorption, apparent porosity, apparent relative density, and bulk density." Place them in a vacuum container, ensuring that the specimens do not touch each other. Add enough water to cover the specimens by 5 cm. Evacuate to 10 kPa ± 1 kPa and maintain for 30 minutes. Then, discontinue vacuuming and allow the specimens to soak for 15 minutes. Remove the specimens and place them on a suspended stand. Blow 0.8 kg of compressed air continuously for 3 minutes at a distance of 10 cm from the upper surface. Immediately weigh and record the weight. Calculate water absorption according to the method specified in 6.1 of GB / T 3810.3-2006.

[0061] The performance test results are shown in Table 1.

[0062] Table 1 Performance test results of Examples 1-4 and Comparative Examples 1-6

[0063]

[0064] According to the analysis in Table 1, by comparing Examples 1-4 with Comparative Example 1, it can be seen that reducing the amount of the first kaolin to 20% and increasing the amount of the second kaolin to 50% directly leads to a decrease in the blue light whiteness of the ceramic sample due to the reduction of the high-whiteness first kaolin, which in turn affects the decrease in multiple reflectance data.

[0065] Comparing Examples 1-4 with Comparative Example 2 shows that while the omission of the secondary kaolin resulted in higher ceramic product performance, the slurry exhibited poor suspension properties and tended to sink to the bottom during the preparation process, making it unsuitable for industrial production. Furthermore, the lack of the plasticity provided by the secondary kaolin resulted in cracking during the firing process.

[0066] By comparing Examples 1-4 with Comparative Example 3, it can be seen that when the second kaolin is replaced with kaolin having a higher iron content, the coloration of the iron element will reduce the blue light whiteness of the final product, thereby reducing various reflectance data.

[0067] By comparing Examples 1-4 with Comparative Example 4, it can be seen that when the first kaolin is replaced by conventional alumina, due to the different structures of the two, the blue light whiteness of the first kaolin is higher than that of conventional alumina, and the blue light whiteness of the ceramic sample of Comparative Example 4 decreases, which leads to a significant decrease in various reflectance ratios.

[0068] By comparing Examples 1-4 with Comparative Example 5, it can be seen that increasing the amount of the first kaolin causes the firing temperature of the formula to be too high. Therefore, under the same firing curve conditions, the ceramic sample of Comparative Example 5 has a low sintering degree, resulting in low strength and high water absorption. Even though the ceramic sample has a high blue light whiteness and reflectance, it is not suitable for actual production.

[0069] By comparing Examples 1-4 with Comparative Example 6, it can be seen that the feldspar in Comparative Example 6 only uses sodium feldspar, which has too high a sodium content and insufficient potassium content, resulting in a narrow sintering range of the formula, difficulty in controlling the temperature during production, and deformation of the sample.

[0070] 30 kg of the mixture was prepared using the recipe of Example 4 and fired at 1280°C to produce a ceramic sample. The sample exhibited a blue light whiteness of 92.01°C before polishing and 92.57°C after polishing, a water absorption of 0.0928%, and a solar reflectance of 93.65%. When the firing temperature was increased to 1300°C, the sample exhibited a blue light whiteness of 92.23°C before polishing and 93.11°C after polishing, a water absorption of 0.0328%, and a solar reflectance of 93.88%. This demonstrates that the preparation method of the present invention is suitable for industrial production.

[0071] The water absorption rates of the ceramic samples prepared according to Examples 1-4 all meet the water absorption rate requirements. According to the national standard GB / T2680-1994 testing method, according to the radiation performance index of radiation cooling materials for buildings "sunlight reflectance ≥92%", the ceramics prepared in Examples 1-4 of the present invention all meet the requirements.

[0072] The ceramic product prepared in Example 4 and several objects and tile products with different blue light whiteness were taken and dried in the sun. The ambient temperature was measured to be 39° C. The surface temperatures of the samples were compared as shown in Table 2.

[0073] Table 2 Comparison of blue light whiteness and surface temperature of various objects under sunlight

[0074]

[0075] According to the data in Table 2, under the condition of an ambient temperature of 39°C, the object is affected by heat radiation and heat is stored. The surface temperature of the refrigeration ceramic of the present invention is significantly lower than that of other test objects due to its high reflectivity to sunlight.

[0076] The embodiments provided by the present invention are described in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the core idea of ​​the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, the present invention can also be improved and modified in a number of ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A non-electric refrigeration ceramic, characterized in that: Calculated by mass percentage, the preparation raw materials include 45-60% of first kaolin, 8-20% of second kaolin, 27-40% of feldspar and 3-5% of calcined talc, among which the first kaolin is modified kaolin, the aluminum oxide mass content of the modified kaolin is ≥99%, the blue light whiteness is >95 degrees, the blue light whiteness of the second kaolin is >85 degrees, and the feldspar includes potassium feldspar.

2. The electric-free refrigeration ceramic according to claim 1, characterized in that: The α-alumina phase content in the first kaolin is ≥99.0%.

3. The electric-free refrigeration ceramic according to claim 1 or 2, characterized in that: The near-infrared reflectivity of the first kaolin is greater than 99.0%.

4. The electric-free refrigeration ceramic according to claim 1, characterized in that: The mass content of ferric oxide in the second kaolin is less than 0.3%.

5. The electric-free refrigeration ceramic according to claim 1, characterized in that: The total mass content of potassium and sodium in feldspar is ≥7.0%, and sodium is ≤3%.

6. The electric-free refrigeration ceramic according to claim 5, characterized in that: The potassium content of feldspar is ≥10% by mass.

7. The electric-free refrigeration ceramic according to claim 5, characterized in that: Feldspar also includes albite.

8. The electric-free refrigeration ceramic according to claim 1, characterized in that: The blue light whiteness of talc after burning at 1200℃ is greater than 70 degrees.

9. The electric-free refrigeration ceramic according to claim 1, characterized in that: The blue light whiteness of non-electric cooling ceramics is ≥90 degrees.

10. A method for preparing non-electric refrigeration ceramics, characterized in that: The non-electric refrigeration ceramic according to any one of claims 1 to 9 is prepared as follows: S1, mixing the first kaolin, the second kaolin, feldspar and calcined talc to form a mixed material; S2. calcining the mixed material to produce non-electric refrigeration ceramics, wherein the calcination curve is as follows: The mixed material is heated from room temperature to 1270-1300°C for 45-60 minutes, and kept at 1270-1300°C for 45-60 minutes.

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