A non-electric refrigeration ceramic and its preparation method

Abstract

This invention belongs to the field of ceramic technology and discloses an electro-cooled ceramic and its preparation method. The raw materials, calculated by mass percentage, include 45-60% first kaolin, 8-20% second kaolin, 27-40% feldspar, and 3-5% calcined talc. The first kaolin is modified kaolin with an aluminum oxide content ≥99% and a blue light whiteness >95 degrees. The second kaolin has a blue light whiteness >85 degrees. The feldspar includes potassium feldspar. The electro-cooled ceramic obtained by this invention has a blue light whiteness ≥90 degrees, achieving a completely white effect. It has high reflectivity to sunlight, reflecting most of the solar heat radiation while emitting 8-13μm infrared wavelengths, directing surface heat into space and achieving a passive cooling effect.

Description

Technical Field

[0001] This invention belongs to the field of ceramic technology, specifically relating to an electro-cooled ceramic and its preparation method. Background Technology

[0002] Electric-free refrigeration ceramics are a new type of inorganic material based on the principle of passive radiation refrigeration. They require no external energy source and generally refer to products whose surface temperature does not significantly increase under direct sunlight. When used as building materials, such as exterior wall tiles or roofing materials, refrigeration ceramics can help reduce indoor temperatures.

[0003] The performance of cooling ceramic products is related to the blue light whiteness of their surface. Currently, ceramic tiles with a surface blue light whiteness of 45-50 degrees are called white tiles, while those with a blue light whiteness of 65 degrees are rare. Tiles with a blue light whiteness of 80 degrees or higher are generally achieved by coating the tile surface with glaze or paint. For example, Chinese invention patent CN119822869A discloses a radiation-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 cooling powder for compounding, the reflectivity and emissivity of infrared and visible light are improved. Chinese invention patent CN114672205A discloses a radiation-cooling coating and surface coating method, proposing a coating with a porous structure to reflect solar radiation. It is evident that existing cooling ceramics achieve their cooling function primarily through coatings or glazes; the ceramic itself does not possess a true solar radiation reflection effect. However, glazes or coatings are prone to peeling off the ceramic surface during long-term use, greatly limiting the use of cooling ceramics. Based on this, this invention proposes a novel non-electric cooling ceramic and its preparation method to solve the above problems. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the purpose of this invention is to provide an electro-cooled ceramic and its preparation method. The electro-cooled ceramic has a blue light whiteness of ≥90 degrees, achieving a completely white effect. It has a high reflectivity to sunlight and can emit 8-13μm infrared wavelengths while reflecting most of the solar heat radiation, thus guiding the heat from the Earth's surface into space and achieving a passive cooling effect.

[0005] To achieve the above-mentioned objectives, the technical solution adopted by the present invention is as follows:

[0006] In a first aspect, the present invention proposes an electro-cooled ceramic, wherein the raw materials for preparation, by mass percentage, include 45-60% of first kaolin, 8-20% of 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 ≥99% and a blue light whiteness >95 degrees, and the second kaolin has a blue light whiteness >85 degrees.

[0007] The preferred method for preparing the first kaolin is as follows:

[0008] Kaolin ore with a kaolin content >40% is selected, crushed, and then washed and classified to obtain concentrate.

[0009] The concentrate is mixed with a chlorinating agent and calcined at 1350–1400℃ for 1–3 h. The calcined material is then mixed with a decolorizing agent and reacted for 1–2 h. The decolorized material is then mixed with a silicon solvent and reacted for 3–5 h. After the reaction is complete, aluminum hydroxide seed crystals are added to precipitate the material and obtain the precipitate.

[0010] The precipitate is calcined at 1100–1400℃ for 2–4 h. Water is added to the calcined material to prepare a slurry with a solid content of 20–30%. A dispersant is added, accounting for 0.5–1% of the slurry mass. The slurry is ground to make the median particle size ≤100 nm to prepare modified kaolin.

[0011] More preferably, the content of Al2O3 corundum phase, i.e. α-alumina phase, in the first kaolinite is ≥99.0%.

[0012] More preferably, the near-infrared reflectance of the first kaolinite is >99.0%.

[0013] Preferably, the ferric oxide content of the second kaolin is <0.3% by mass.

[0014] Preferably, the total mass content of potassium and sodium in feldspar is ≥7.0%, and the sodium content is ≤3%.

[0015] More preferably, the potassium content of feldspar is ≥10% by mass.

[0016] More preferably, the feldspar is potassium feldspar, or the feldspar includes potassium feldspar and sodium feldspar.

[0017] Preferably, the blue light whiteness of calcined talc after being calcined at 1200℃ is >70 degrees.

[0018] In a second aspect, the present invention provides a method for preparing an electro-cooled ceramic, as follows:

[0019] S1. Mix the first kaolin, the second kaolin, feldspar and calcined talc to form a mixture;

[0020] S2. The mixture is calcined to produce an electro-cooled ceramic. The calcination curve is as follows:

[0021] The mixture is heated from room temperature to 1270–1300℃ for 45–60 minutes, and then held at 1270–1300℃ for 45–60 minutes.

[0022] Beneficial effects

[0023] The electro-cooled ceramic produced by this invention has a blue light whiteness of ≥90 degrees, achieving a completely white effect. It has a high reflectivity to sunlight and can emit 8-13μm infrared wavelengths while reflecting most of the solar heat radiation, thus guiding the heat from the Earth's surface into space and achieving a passive cooling effect. Detailed Implementation

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, specific implementation methods of the present invention will be described below. Obviously, the following description is merely some embodiments of the present invention; those skilled in the art can obtain other implementation methods based on these embodiments without creative effort.

[0025] This invention proposes a non-electric cooling ceramic. The raw materials for preparation, calculated by mass percentage, include 45-60% first kaolin, 8-20% second kaolin, 27-40% feldspar, and 3-5% calcined talc. The first kaolin is modified kaolin with an aluminum oxide content ≥99%, a blue light whiteness >95 degrees, and a near-infrared reflectance >99.0%. The second kaolin has an iron oxide content <0.3% and a blue light whiteness >85 degrees.

[0026] In this invention, the blue light whiteness of the first kaolin and the second kaolin are measured based on existing testing conditions and methods. In this 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 this invention improves the performance of the ceramic product based on its inherent properties; theoretically, any first kaolin meeting the above requirements is applicable to this invention. This invention also proposes a method for preparing the first kaolin, as follows:

[0027] Kaolin ore with a kaolin content >40% is selected, crushed, and then washed and classified to obtain concentrate.

[0028] The concentrate is mixed with a chlorinating agent and calcined at 1350–1400℃ for 1–3 h. The calcined material is then mixed with a decolorizing agent and reacted for 1–2 h. The decolorized material is then mixed with a silicon solvent and reacted for 3–5 h. After the reaction is complete, aluminum hydroxide seed crystals are added to precipitate the material and obtain the precipitate.

[0029] The precipitate is calcined at 1100–1400℃ for 2–4 h. Water is added to the calcined material to prepare a slurry with a solid content of 20–30%. A dispersant is added, accounting for 0.5–1% of the slurry mass. The slurry is ground to make the median particle size ≤100 nm to prepare modified kaolin.

[0030] The chlorinating agent includes one or more of calcium chloride, magnesium chloride, and ammonium chloride; the silicon solvent includes one or more of sodium hydroxide, potassium hydroxide, and sodium carbonate.

[0031] The first kaolin prepared by this invention has high alumina content and nano-fineness, with an alumina content ≥99%, high whiteness after re-firing at 1200℃, for example, blue light whiteness >95 degrees after firing at 1200℃, and near-infrared reflectance >99.0%.

[0032] In this invention, the second kaolin is commercially available kaolin, which is required to have good plasticity, good slurry suspension, and high blue light whiteness after firing at 1200℃, for example, blue light whiteness > 85 degrees after firing at 1200℃, and the mass content of ferric oxide is required to be < 0.3%.

[0033] In this invention, feldspar refers to feldspar with a total potassium and sodium content ≥7.0% and sodium content ≤3%. For example, the feldspar can be potassium feldspar, or the feldspar may include both potassium and sodium feldspar. Preferably, the potassium content of the feldspar is ≥10%. A high potassium content is beneficial for broadening the firing temperature range under high-temperature firing conditions. More preferably, the particle size of the feldspar is ≤74μm.

[0034] In this invention, the calcined talc is a commercially available conventional calcined talc, which has a blue light whiteness greater than 70 degrees after being calcined at 1200℃.

[0035] Based on the above-mentioned raw material composition of the non-electric refrigeration ceramic, the present invention also proposes a method for preparing the non-electric refrigeration ceramic, as follows:

[0036] S1. Mix the first kaolin, the second kaolin, feldspar and calcined talc to form a mixture;

[0037] S2. The mixture is calcined to produce an electro-cooled ceramic. The calcination curve is as follows:

[0038] The mixture is heated from room temperature to 1270–1300℃ for 45–60 minutes, and then held at 1270–1300℃ for 45–60 minutes.

[0039] The electro-cooled ceramic produced by this invention has a blue light whiteness of ≥90 degrees, achieving a completely white effect. It has a high reflectivity to sunlight and can emit 8-13μm infrared wavelengths while reflecting most of the solar heat radiation, thus guiding the heat from the Earth's surface into space and achieving a passive cooling effect.

[0040] The water absorption rate of the non-electric cooling ceramic obtained by the present invention is ≤0.5%. The ceramic product achieves the cooling effect by reflecting sunlight through outdoor paving. The ceramic product has a low water absorption rate, strong weather resistance, and good anti-freeze-thaw and anti-fouling properties.

[0041] The technical solution of the present invention will be described in detail below with specific embodiments.

[0042] In the following examples and comparative examples, the chemical composition of the raw materials and the blue light whiteness after calcination at 1200°C are as follows:

[0043] First kaolin:

[0044] Kaolin ore with a kaolin content >40% is selected, crushed, and then washed and classified to obtain concentrate.

[0045] The concentrate was mixed with calcium chloride and calcined at 1400℃ for 2 h. The calcined material was then mixed with a decolorizing agent and reacted for 2 h. The decolorized material was then mixed with sodium hydroxide and reacted for 4 h. After the reaction was completed, aluminum hydroxide seed crystals were added to precipitate the precipitate.

[0046] The precipitate was calcined at 1200℃ for 3 h. The calcined material was then mixed with water to form a slurry with a solid content of 30%. A dispersant was added, accounting for 0.5-1% of the slurry mass. The slurry was then ground to make the median particle size ≤100 nm, thus producing modified kaolin.

[0047] Calculated by mass percentage, the composition is: aluminum oxide 99.27%, silicon dioxide <0.01%, ferric oxide <0.01%, calcium oxide <0.01%, magnesium oxide <0.01%, potassium oxide <0.01%, sodium oxide <0.06%, titanium dioxide <0.01%, loss on ignition 0.33%, with the remainder being impurities. The first kaolin clay, after calcination at 1200℃, has a blue light whiteness of 97.13 degrees. The first kaolin clay contains 99.0% Al₂O₃ corundum phase (α-alumina phase) and 1.0% amorphous phase.

[0048] Conventional alumina: By mass percentage, it comprises 98.80% aluminum oxide, 0.01% silicon dioxide, 0.01% ferric oxide, <0.01% calcium oxide, <0.01% magnesium oxide, <0.01% potassium oxide, 0.45% sodium oxide, <0.01% titanium dioxide, with a loss on ignition of 0.33%, and the balance being impurities. Conventional alumina, after firing at 1200℃, has a blue light whiteness of 90.25 degrees.

[0049] Second-grade kaolin: By mass percentage, it contains 32.38% aluminum oxide, 53.56% silicon dioxide, 0.27% ferric oxide, 0.04% calcium oxide, 0.11% magnesium oxide, 1.01% potassium oxide, 0.62% sodium oxide, and 0.04% titanium dioxide. The loss on ignition is 11.65%, with the remainder being impurities. The second-grade kaolin has a blue light whiteness of 87.03 degrees after firing at 1200℃. K75 kaolin (product of Foshan Guyue New Materials Co., Ltd.) can be used as the second-grade kaolin.

[0050] Laiyang kaolin: By mass percentage, it contains 13.27% aluminum oxide, 70.43% silicon dioxide, 1.37% ferric oxide, 3.03% calcium oxide, 2.19% magnesium oxide, 3.41% potassium oxide, 1.72% sodium oxide, and 0.12% titanium dioxide. The loss on ignition is 4.35%, with the remainder being impurities. Laiyang kaolin, after being calcined at 1200℃, has a blue light whiteness of 22.87 degrees.

[0051] Potassium feldspar: By mass percentage, it comprises 18.74% aluminum oxide, 65.06% silicon dioxide, 0.12% ferric oxide, 0.23% calcium oxide, 0.07% magnesium oxide, 12.41% potassium oxide, 2.66% sodium oxide, 0.01% titanium dioxide, with a loss on ignition of 0.40%, and the balance being impurities. Potassium feldspar, after being ignited at 1200℃, has a blue light whiteness of 44.31 degrees.

[0052] Albite: By mass percentage, it comprises 15.46% aluminum oxide, 72.86% silicon dioxide, 0.11% ferric oxide, 0.92% calcium oxide, 0.27% magnesium oxide, 0.41% potassium oxide, 8.48% sodium oxide, and 0.10% titanium dioxide. The loss on ignition is 1.25%, with the balance being impurities. Albite, after being ignited at 1200℃, has a blue light whiteness of 42.22 degrees.

[0053] Calcined talc: By mass percentage, it contains 2.67% aluminum oxide, 60.84% ​​silicon dioxide, 0.28% ferric oxide, 0.94% calcium oxide, 33.83% magnesium oxide, 0.69% potassium oxide, 0.07% sodium oxide, and 0.08% titanium dioxide. The loss on ignition is 0.31%, with the remainder being impurities. The bluish whiteness of calcined talc after calcination at 1200℃ is 71.65 degrees.

[0054] Example 1

[0055] S1. Calculate by mass percentage, mix 45% of first kaolin, 17% of second kaolin, 35% of potassium feldspar and 3% of calcined talc to form a mixture, ball mill it and dry it into powder, and finally press it into a round cake with a diameter of 80 mm and a thickness of 10 mm.

[0056] S2. The mixture is calcined to produce ceramic samples. The calcination curve is shown below:

[0057] The mixture was heated from room temperature to 1280℃ for 45 minutes and held at 1280℃ for 60 minutes.

[0058] Example 2

[0059] S1. Calculate by mass percentage, mix 50% of first kaolin, 12% of second kaolin, 35% potassium feldspar and 3% calcined talc to form a mixture, ball mill it and dry it into powder, and finally press it into a round cake with a diameter of 80 mm and a thickness of 10 mm.

[0060] S2. The mixture is calcined to produce ceramic samples. The calcination curve is shown below:

[0061] The mixture was heated from room temperature to 1280℃ for 45 minutes and held at 1280℃ for 60 minutes.

[0062] Example 3

[0063] S1. Calculate by mass percentage, mix 55% of first kaolin, 9% of second kaolin, 33% of potassium feldspar and 3% of calcined talc to form a mixture, ball mill it and dry it into powder, and finally press it into a round cake with a diameter of 80 mm and a thickness of 10 mm.

[0064] S2. The mixture is calcined to produce ceramic samples. The calcination curve is shown below:

[0065] The mixture was heated from room temperature to 1280℃ for 45 minutes and held at 1280℃ for 60 minutes.

[0066] Example 4

[0067] S1. Calculate by mass percentage, mix 60% of first kaolin, 10% of second kaolin, 27% of potassium feldspar and 3% of calcined talc to form a mixture, ball mill it and dry it into powder, and finally press it into a round cake with a diameter of 80 mm and a thickness of 10 mm.

[0068] S2. The mixture is calcined to produce ceramic samples. The calcination curve is shown below:

[0069] The mixture was heated from room temperature to 1280℃ for 45 minutes and held at 1280℃ for 60 minutes.

[0070] Comparative Example 1

[0071] Compared with Examples 1-4, the first kaolin in this comparative example was insufficient.

[0072] S1. Calculate by mass percentage, mix 20% first kaolin, 50% second kaolin, 25% potassium feldspar and 5% calcined talc to form a mixture, ball mill it and dry it into powder, and finally press it into a round cake with a diameter of 80 mm and a thickness of 10 mm.

[0073] S2. The mixture is calcined to produce ceramic samples. The calcination curve is shown below:

[0074] The mixture was heated from room temperature to 1280℃ for 45 minutes and held at 1280℃ for 60 minutes.

[0075] Comparative Example 2

[0076] Compared with Examples 1-4, this comparative example lacks a second kaolin.

[0077] S1. Calculate by mass percentage, mix 60% first kaolin, 35% potassium feldspar and 5% calcined talc to form a mixture, ball mill and dry to make powder, and finally press into shape to obtain a round cake with a diameter of 80 mm and a thickness of 10 mm.

[0078] S2. The mixture is calcined to produce ceramic samples. The calcination curve is shown below:

[0079] The mixture was heated from room temperature to 1280℃ for 45 minutes and held at 1280℃ for 60 minutes.

[0080] Comparative Example 3

[0081] Compared with Examples 1-4, this comparative example uses Laiyang kaolin instead of the second kaolin. The ferric oxide content of Laiyang kaolin is too high, resulting in low blue light whiteness after burning at 1200℃.

[0082] S1. Calculate by mass percentage, mix 45% of first kaolin, 17% of Laiyang kaolin, 35% of potassium feldspar and 3% of calcined talc to form a mixture, ball mill it and dry it into powder, and finally press it into a round cake with a diameter of 80 mm and a thickness of 10 mm.

[0083] S2. The mixture is calcined to produce ceramic samples. The calcination curve is shown below:

[0084] The mixture was heated from room temperature to 1280℃ for 45 minutes and held at 1280℃ for 60 minutes.

[0085] Comparative Example 4

[0086] Compared with Examples 1-4, this comparative example uses conventional alumina instead of the first kaolin.

[0087] S1. By mass percentage, 45% conventional alumina, 17% second kaolin, 35% potassium feldspar and 3% calcined talc are mixed to form a mixture. After ball milling, the mixture is dried and powdered, and finally pressed into a round cake with a diameter of 80 mm and a thickness of 10 mm.

[0088] S2. The mixture is calcined to produce ceramic samples. The calcination curve is shown below:

[0089] The mixture was heated from room temperature to 1280℃ for 45 minutes and held at 1280℃ for 60 minutes.

[0090] Comparative Example 5

[0091] Compared with Examples 1-4, the first kaolin in this comparative example is in excess and the other raw materials are in insufficient amounts.

[0092] S1. Calculate by mass percentage, mix 90% of first kaolin, 2% of second kaolin, 3% potassium feldspar and 5% calcined talc to form a mixture, ball mill it and dry it into powder, and finally press it into a round cake with a diameter of 80 mm and a thickness of 10 mm.

[0093] S2. The mixture is calcined to produce ceramic samples. The calcination curve is shown below:

[0094] The mixture was heated from room temperature to 1280℃ for 45 minutes and held at 1280℃ for 60 minutes.

[0095] Comparative Example 6

[0096] Compared with Examples 1-4, this comparative example uses sodium feldspar instead of potassium feldspar.

[0097] S1. Calculate by mass percentage, mix 45% of first kaolin, 17% of second kaolin, 35% of sodium feldspar and 3% of calcined talc to form a mixture, ball mill it, dry it and grind it into powder, and finally press it into a round cake with a diameter of 80 mm and a thickness of 10 mm.

[0098] S2. The mixture is calcined to produce ceramic samples. The calcination curve is shown below:

[0099] The mixture was heated from room temperature to 1280℃ for 45 minutes and held at 1280℃ for 60 minutes.

[0100] The ceramic samples obtained in Examples 1-4 and Comparative Examples 1-6 were subjected to performance tests, and the test methods are as follows.

[0101] Whiteness test method: Prepare samples according to the requirements of Section 7 of GB / T 5950-2008 "Methods for Measurement of Whiteness of Building Materials and Non-metallic Mineral Products". Preheat and zero the instrument that meets the specifications, calibrate it with a standard white plate, and then measure the value of the sample.

[0102] Test methods for solar reflectance, visible light reflectance, and infrared reflectance: Sample preparation and determination shall be carried out in accordance with GB / T 2680-1994 standard.

[0103] Water absorption test method: Prepare the samples 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 the samples in a vacuum container, ensuring they do not touch each other. Add sufficient water to cover the samples, raising them 5 cm above the surface. Evacuate to 10 kPa ± 1 kPa and maintain this pressure for 30 minutes. Stop evacuating and allow the samples to soak for 15 minutes. Remove the samples and place them on a suspended support. Blow the samples with 0.8 kg of compressed air continuously for 3 minutes at a distance of 10 cm from the top surface. Weigh the samples immediately and record the weight. Calculate the water absorption rate according to the method specified in 6.1 of GB / T 3810.3-2006.

[0104] The performance test results are shown in Table 1.

[0105] Table 1 Performance test results of Examples 1-4 and Comparative Examples 1-6

[0106]

[0107] Analysis based on Table 1. Comparison of Examples 1-4 with Comparative Example 1 shows that reducing the amount of the first kaolin to 20% and increasing the amount of the second kaolin to 50% directly reduces the blue light whiteness of the ceramic sample due to the reduction of the high-whiteness first kaolin, thus affecting the reduction of multiple reflectance data.

[0108] A comparison of Examples 1-4 with Comparative Example 2 shows that although omitting the second kaolin results in higher overall ceramic product specifications, the slurry exhibits poor suspension during preparation, tending to settle to the bottom, which is detrimental to industrial production. Furthermore, the lack of plasticity provided by the second kaolin leads to product cracking during firing.

[0109] A comparison of Examples 1-4 with Comparative Example 3 shows that replacing the second kaolin with kaolin of higher iron content reduces the blue light whiteness of the final product, thereby affecting various reflectance data.

[0110] By comparing Examples 1-4 with Comparative Example 4, it can be seen that when conventional alumina is replaced with the first kaolinite, due to the different structures of the two, the blue light whiteness of the first kaolinite is higher than that of conventional alumina. The blue light whiteness of the ceramic sample in Comparative Example 4 decreases, which in turn leads to a significant decrease in various reflectance ratios.

[0111] By comparing Examples 1-4 with Comparative Example 5, it can be seen that increasing the amount of first kaolin results in an excessively high firing temperature. Therefore, under the same firing curve conditions, the ceramic sample of Comparative Example 5 has a low degree of sintering, resulting in low strength and high water absorption. Even though the ceramic sample has high blue light whiteness and reflectance, it is not suitable for actual production.

[0112] A comparison of Examples 1-4 with Comparative Example 6 shows that Comparative Example 6 uses only sodium feldspar, resulting in excessively high sodium content and insufficient potassium content. This leads to a narrow firing range in the formula, making it difficult to control the temperature during production and causing sample deformation.

[0113] 30 kg of a mixture was prepared using the formulation of Example 4 and fired at 1280°C to obtain a ceramic sample. The ceramic sample had a blue light whiteness of 92.01 degrees before polishing and 92.57 degrees after polishing, with a water absorption rate of 0.0928% and a solar reflectance of 93.65%. When the firing temperature was increased to 1300°C, the resulting ceramic sample had a blue light whiteness of 92.23 degrees before polishing and 93.11 degrees after polishing, with a water absorption rate of 0.0328% and a solar reflectance of 93.88%. It is evident that the preparation method of this invention is suitable for industrial production.

[0114] The water absorption rates of the ceramic samples prepared according to Examples 1-4 all meet the requirements. According to the national standard GB / T2680-1994 test method, based on the radiation performance index of "solar reflectance ≥92%" for radiant cooling materials for buildings, the ceramics prepared according to Examples 1-4 of this invention all meet the requirements.

[0115] The ceramic product prepared in Example 4, as well as several objects and tile products with different blue light whiteness, were dried in the sun. The ambient temperature was measured at 39°C. The surface temperatures of each sample were compared as shown in Table 2.

[0116] Table 2 Comparison of blue light whiteness and surface temperature of various objects under sunlight

[0117]

[0118] According to the data in Table 2, under an ambient temperature of 39°C, the object heats up and stores heat due to the influence of heat radiation. The surface temperature of the cooling ceramic of the present invention is significantly lower than that of other tested objects due to its high reflectivity to sunlight.

[0119] The embodiments provided by the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention, and the descriptions of the embodiments above are only for the purpose of helping to understand the core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A non-electrically cooled ceramic, characterized in that, The raw materials for preparation, calculated by mass percentage, include 45-60% primary kaolin, 8-20% secondary kaolin, 27-40% feldspar, and 3-5% calcined talc. Among them, the primary kaolin is modified kaolin with an aluminum oxide content ≥99% and a blue light whiteness >95 degrees. The secondary kaolin has a blue light whiteness >85 degrees. The feldspar includes potassium feldspar. The preparation method of the first kaolin is as follows: Kaolin ore with a kaolin content >40% is selected, crushed, and then washed and classified to obtain concentrate. The concentrate is mixed with a chlorinating agent and calcined at 1350–1400℃ for 1–3 h. The calcined material is then mixed with a decolorizing agent and reacted for 1–2 h. The decolorized material is then mixed with a silicon solvent and reacted for 3–5 h. After the reaction is complete, aluminum hydroxide seed crystals are added to precipitate the material and obtain the precipitate. The precipitate is calcined at 1100-1400℃ for 2-4 hours. Water is added to the calcined material to prepare a slurry with a solid content of 20-30%. A dispersant is added, accounting for 0.5-1% of the slurry mass. The slurry is ground to make the median particle size ≤100 nm to prepare modified kaolin. The chlorinating agent includes one or more of calcium chloride, magnesium chloride, and ammonium chloride; the silicon solvent includes one or more of sodium hydroxide, potassium hydroxide, and sodium carbonate.

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

3. The non-electric cooling ceramic according to claim 1 or 2, characterized in that, The near-infrared reflectance of the first kaolin is >99.0%.

4. The non-electric cooling ceramic according to claim 1, characterized in that, The ferric oxide content of the second kaolin is <0.3%.

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

6. The non-electric cooling ceramic according to claim 5, characterized in that, The potassium content of feldspar is ≥10%.

7. The non-electric cooling ceramic according to claim 5, characterized in that, Feldspar also includes sodium feldspar.

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

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

10. A method for preparing an electro-cooled ceramic, characterized in that, The electro-cooled ceramic according to any one of claims 1-9 is prepared as follows: S1. Mix the first kaolin, the second kaolin, feldspar and calcined talc to form a mixture; S2. The mixture is calcined to produce an electro-cooled ceramic. The calcination curve is as follows: The mixture is heated from room temperature to 1270–1300℃ for 45–60 minutes, and then held at 1270–1300℃ for 45–60 minutes.

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