Zirconium white ingot and preparation method and application thereof

Abstract

The present application relates to the technical field of building ceramics, and discloses a zircon white fused block and a preparation method and application thereof, wherein the raw materials of the zircon white fused block include kaolin 12-20 parts by weight, zirconium silicate powder 8-15 parts by weight, quartz 30-42 parts by weight, zinc oxide 3-8 parts by weight, calcium phosphate salt 3-8 parts by weight, and fluxing components 20-42 parts by weight. The zircon white fused block is rich in a large amount of microcrystalline zirconium oxide, and the zircon white fused block has excellent chemical temperature resistance and a refractive index significantly higher than that of a glass phase, so that a strong reflection and scattering effect is formed in a glaze surface; by introducing the zircon white fused block with high whiteness and high opalescence into a glaze system, the whiteness and opalescence of the fired glaze surface can be more effectively improved.

Description

Technical Field

[0001] This invention relates to the field of building ceramics technology, and in particular to a zirconium white frit, its preparation method, and its application. Background Technology

[0002] Radiant cooling coating technology, as an innovative and effective passive cooling technology, can significantly reduce the surface temperature of buildings without consuming electricity. It can be applied in building energy conservation, grain storage, petrochemical storage tanks, cold chain logistics, and new energy fields, effectively replacing or reducing the need for active cooling.

[0003] Compared to the building itself and ordinary coatings, building insulation coatings have a higher solar reflectance and a lower surface temperature, resulting in energy-saving effects. This ensures that the building surface temperature is lower than the ambient temperature even under high summer temperatures.

[0004] Traditional building insulation coatings are mainly composed of organic resin encapsulating inorganic fillers. The organic resin-CC structure is exposed to the outdoors and is easily corroded by acid rain and burned by ultraviolet radiation. After long-term use, it ages and discolors, and has disadvantages such as poor weather resistance, easy corrosion, and poor durability.

[0005] Radiation-cooled ceramic tiles can actively reflect solar heat and emit heat from the tile body into space in the form of infrared radiation, thus keeping the surface temperature of the tile lower than the ambient temperature. Existing technologies, such as Chinese patent CN116715539A "High-Reflectivity Heat-Insulating Ceramic Glaze, Ceramic Glaze, Ceramic Tile and its Preparation Method," achieve a certain reflective effect by directly adding pre-prepared titanium sphene powder to the glaze.

[0006] However, this technical approach has significant limitations in practical large-scale production applications: First, due to the large amount of titanium sphene powder added, it can only rely on physical dispersion during the glaze preparation process, which easily leads to the agglomeration of crystal particles, causing drastic fluctuations in the rheological properties of the glaze slurry. The quality of the glaze surface after firing is extremely unstable, and defects such as color difference, pinholes, and rough glaze surface are prone to occur. Second, the titanium sphene particles with larger particle sizes have poor compatibility with the glass matrix, resulting in a loose microstructure of the glaze layer and an increased open porosity, which seriously weakens the anti-fouling performance of ceramic tiles, causing their reflectivity to rapidly decrease due to the adsorption of dust and stains during long-term outdoor use.

[0007] Therefore, it is of great significance to develop a glaze that can maintain a high reflectivity while also taking into account excellent glaze quality and anti-fouling performance. Summary of the Invention

[0008] To address the aforementioned shortcomings, the primary objective of this invention is to propose a zirconium white frit that solves the problem of the direct use of titanium sphene powder affecting the quality of the glaze.

[0009] The second objective of this invention is to provide a method for preparing the aforementioned zirconium white frit.

[0010] The third objective of this invention is to propose the application of the aforementioned zirconium white frit, specifically including a reflective heat-insulating glaze containing the aforementioned zirconium white frit and a glaze surface formed by firing the aforementioned reflective heat-insulating glaze, thereby solving the problem in the prior art that it is difficult to simultaneously achieve high reflectivity, excellent glaze quality, and anti-fouling performance in heat-insulating ceramic glaze surfaces.

[0011] To achieve this objective, the present invention adopts the following technical solution: A zircon white frit for reflective heat-insulating glaze, comprising, by weight, 12-20 parts kaolin, 8-15 parts zircon powder, 30-42 parts quartz, 3-8 parts zinc oxide, 3-8 parts calcium phosphate, and 20-42 parts fluxing components.

[0012] Preferably, the calcium phosphate salt is tricalcium phosphate.

[0013] Preferably, the chemical composition of the zirconium white ingot, by mass ratio, includes: SiO2 52~57%, Al2O3 5~12%, Fe2O3 0.1~0.5%, TiO2 0.01~0.5%, CaO 3~12%, MgO 1.0~4.5%, K2O 2~7%, ZnO 3~9%, ZrO2 6~12%, P2O5 1~4%.

[0014] Preferably, the fluxing component comprises the following raw materials in parts by weight: 5-12 parts of dolomite, 10-20 parts of calcite Potassium carbonate 5-10 parts.

[0015] Preferably, the raw materials are mixed evenly according to the proportion, heated to a firing temperature of 1500~1600℃ for firing, and held at the firing temperature for 0.1~1h, then discharged and cooled to obtain zircon white frit.

[0016] A reflective heat-insulating glaze, the raw materials of which include kaolin, titanium dioxide, potassium feldspar, wollastonite, barium carbonate and the above-mentioned zirconium white frit; According to the mass ratio, the chemical composition of the glaze includes: SiO2 45~52%, Al2O3 9~15%, Fe2O3 0.1~0.4%, TiO2 7~12%, CaO 8~15%, MgO 1~3%, BaO 2~6%, ZnO 1.5~5%, K2O 2~5%, Na2O 0.5~3%, ZrO2 2~4.5%, P2O5 0.2~1.5%, Weight loss upon ignition at 1000℃ is 2-5%; And according to the mass ratio, .

[0017] Preferably, the ingredients, by weight, include the following raw materials: 5-10 parts of kaolin 5-10 parts titanium dioxide, 25-35 parts of zirconium white frit, Potassium feldspar 20-35 parts, 15-25 parts wollastonite 5-12 parts of barium carbonate.

[0018] Preferably, the method for preparing the reflective heat-insulating glaze includes the following steps: S1. Weigh 100 parts of raw materials according to the proportion of raw materials for the glaze; S2. Add the weighed raw materials to the ball mill, and add 40 parts water and 0.12~5 parts grinding aid according to the mass ratio, and then ball mill. S3, ball milling until the ball specific gravity is 1.85~1.9g / cm³ 3 The fineness is 0.4~0.6g, which is measured by the amount of residue after 200g of slurry passes through a 325-mesh sieve, and the reflective heat-insulating glaze is prepared.

[0019] Preferably, the grinding aid comprises 0.12 parts sodium carboxymethyl cellulose, 0.42 parts sodium tripolyphosphate, and 0.05 parts preservative.

[0020] A high solar reflectance glaze, the surface of which is made of the above-mentioned reflective heat-insulating glaze, the firing temperature of the glaze is 1180~1230℃, the thickness is 0.16~0.17mm, the solar reflectance of the glaze is 0.92~0.925, and the anti-fouling performance of the glaze is level 5.

[0021] The technical solution provided by this invention may include the following beneficial effects: 1. Zircon powder, with zirconium silicate as the main component, can form two compounds after firing: zirconium silicate with a refractive index of 1.9 and zirconium oxide with a refractive index of 2.2. Under the action of a large amount of fluxing components, supersaturated zirconium oxide will precipitate microcrystals. With zinc oxide as a crystallizing agent, the zircon white frit is rich in microcrystalline zirconium oxide. Utilizing its excellent chemical temperature resistance and refractive index significantly higher than that of the glass phase, it forms a strong reflection and scattering effect in the glaze. By introducing this high-whiteness and high-turbidity zircon white frit into the glaze system, the whiteness and turbidity of the fired glaze can be improved more effectively.

[0022] Calcium phosphate is a phosphorus-containing component. Driven by thermodynamic instability, in the high-temperature molten state, the phosphate-containing melt enters the thermodynamically unstable region due to reduced miscibility between components. During cooling, it spontaneously separates into two or more glassy phases with different compositions. Phosphate forms a phosphate network with silica, which can change the melt structure and viscosity, promoting the nucleation and growth of phase-separated droplets. In the preparation of zirconium white frit, it acts as a nucleating agent to guide the orderly precipitation of zirconium oxide crystals. Furthermore, in the subsequent firing process of glazes, phosphate acts as a phase-separating agent, significantly enhancing the phase-separation tendency of the glaze in lime glaze systems. The phase separation forms droplets or crystallization micro-regions, which, due to their different refractive indices from the matrix glass, produce light scattering, forming opacity, thereby improving the opacity of the glaze surface and the glaze surface scattering and diffuse reflection effects.

[0023] 2. The application of zirconium white frit in titanium sphene glazes can produce white ceramic tile glazes with high solar reflectivity. During the glaze firing process, microcrystalline zirconium oxide in the zirconium white frit serves as a heterogeneous nucleus, inducing an interfacial reaction between titanium dioxide and zirconium white frit. This generates uniformly distributed titanium sphene microcrystals with controlled particle size in situ, constructing a zirconium-titanium composite reflective layer. This achieves extremely high solar reflectivity and excellent anti-fouling performance while maintaining the glaze's hardness and stain resistance.

[0024] 3. The purpose of controlling the firing temperature of zirconium white frit to above 1500℃ is to ensure that the zirconium white frit has a suitable high-temperature viscosity for feeding, and at the same time, a suitable curing time ensures that the zirconium white frit can effectively precipitate titanium sphene crystals during the subsequent glaze firing process. The firing temperature and curing time can be adjusted against each other. Generally, the higher the firing temperature, the shorter the curing time can be, while the longer the curing time, the longer the zirconium oxide crystallization time and the more crystals. However, it is necessary to avoid the problem of increasing the glass phase content in the glaze due to excessively long firing time. One purpose of zirconium white frit is to provide zirconium oxide crystals. Secondly, the phosphate formed by calcium phosphate during the frit firing is introduced into the raw material to promote titanium sphene crystallization. Thirdly, the frit contains a large amount of calcium oxide components, which promote the crystallization of titanium sphene during secondary applications.

[0025] 4. Applying zirconium white frit to titanium sphene glazes increases the whiteness and opacity of the fired glaze surface. Utilizing the different refractive indices of various crystals, when using zirconium white frit, the glaze layer contains titanium dioxide crystals, zirconium oxide crystals, titanium sphene crystals, and a glass matrix with refractive indices of 2.71, 2.2, 1.9, and 1.5, respectively, creating a refractive index gradient. Materials with different refractive indices can construct multiple diffuse reflection paths, optimizing the overall optical uniformity of the glaze surface and reducing solar transmission and absorption. In particular, due to its high refractive index, when titanium sphene crystals precipitate at micron and submicron levels, the grain size approaches the visible light band, resulting in a strong opacity in the glaze surface. This leads to highly efficient Mie scattering and reflection, further increasing the solar reflectance and achieving a high solar reflectance of 0.92.

[0026] 5. The proposed reflective heat-insulating glaze simultaneously considers solar reflectance, whiteness, opacity, and anti-fouling performance. Under the condition that zirconium white frit provides phosphate as a phase separation and crystallization agent, wollastonite and titanium dioxide react at high temperature to precipitate titanium sphene microcrystals in situ. The grains are fine and uniform, the glaze surface is delicate and dense, and the opacity effect is good. This solves the problem that conventional titanium sphene system glazes cannot achieve both high solar reflectance and high anti-fouling performance when titanium sphene powder is used directly. Detailed Implementation

[0027] To facilitate understanding of the present invention, a more complete description is provided below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0028] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0030] A zircon white frit for reflective heat-insulating glaze, comprising, by weight, 12-20 parts kaolin, 8-15 parts zircon powder, 30-42 parts quartz, 3-8 parts zinc oxide, 3-8 parts calcium phosphate, and 20-42 parts fluxing components.

[0031] Zircon powder, with zirconium silicate as its main component, can be fired to form two compounds: zirconium silicate with a refractive index of 1.9 and zirconium oxide with a refractive index of 2.2. Under the action of a large amount of fluxing components, supersaturated zirconium oxide will precipitate microcrystals. With zinc oxide as a crystallizing agent, the zircon white frit is rich in microcrystalline zirconium oxide. Utilizing its excellent chemical temperature resistance and refractive index significantly higher than that of the glass phase, it forms a strong reflection and scattering effect in the glaze. By introducing this high-whiteness and high-turbidity zircon white frit into the glaze system, the whiteness and turbidity of the fired glaze can be improved more effectively.

[0032] It is worth noting that calcium phosphate is a phosphorus-containing component. Driven by thermodynamic instability, in the high-temperature molten state, the phosphate-containing melt enters the thermodynamically unstable region due to reduced miscibility between components. During cooling, it spontaneously separates into two or more glass phases with different compositions. Phosphate forms a phosphate network with silica, which can change the melt structure and viscosity, promoting the nucleation and growth of phase-separated droplets. In the preparation of zirconium white frit, it acts as a nucleating agent to guide the orderly precipitation of zirconium oxide crystals. Furthermore, in the subsequent firing process of glazes, phosphate acts as a phase-separating agent, significantly enhancing the phase-separation tendency of the glaze in lime glaze systems. The phase separation forms droplets or crystallization micro-regions, which, due to their different refractive indices from the matrix glass, produce light scattering, forming opacity, thereby improving the opacity of the glaze surface and the glaze surface scattering and diffuse reflection effects.

[0033] The high viscosity of zircon white frit during preparation requires a large amount of fluxing components to reduce the high-temperature viscosity of the zircon white frit. Too much zircon powder makes it difficult to feed the zircon white frit, while too little results in low zirconium oxide content and limited whitening effect.

[0034] Too little zinc oxide will have a limited crystallization effect and a significant impact on the whiteness of the glaze; too much will further enhance melting and similarly reduce whiteness.

[0035] If too much phosphate is added, the subsequent glaze will have high gloss, a lot of glass phase, and low whiteness; if too little is added, the crystallization and phase separation effects will be very limited, and the expected results will not be achieved.

[0036] The main components of kaolin are active silica and alumina. Too much silica will result in high viscosity of zirconium white frit, making it difficult to feed. Too little frit will result in too much glass phase, affecting the whiteness of the glaze.

[0037] Quartz is the main component of glassy silicon-oxygen tetrahedra. Too little quartz results in a low glass phase, high glaze viscosity, and difficulty in feeding. Too much quartz may lead to an excessive glass phase during subsequent glaze firing, affecting the whiteness of the glaze surface.

[0038] In a specific embodiment, when zirconium white frit is applied to reflective heat-insulating glazes, specifically in titanium sphene glaze systems, a white ceramic tile glaze with high solar reflectance can be prepared. During the glaze firing process, microcrystalline zirconium oxide in the zirconium white frit serves as a heterogeneous nucleus, inducing an interfacial reaction between it and titanium dioxide. This generates uniformly distributed titanium sphene microcrystals with controlled particle size in situ, constructing a zirconium-titanium composite reflective layer. Thus, while ensuring the hardness and stain resistance of the glaze, extremely high solar reflectance and extremely high stain resistance are achieved.

[0039] Calcium phosphate salts can also be calcium dihydrogen phosphate, calcium hydrogen phosphate, octacalcium phosphate, or apatite, etc., and the addition ratio will be adjusted in specific applications. Calcium phosphate salts can be used in all formulation systems because, under high-temperature firing conditions, their melting point is lower than the melting point of the frit, allowing them to decompose into calcium oxide and P2O5. Preferably, the calcium phosphate salt is tricalcium phosphate. Tricalcium phosphate has a wide range of applications in the industry, good maturity, and higher stability. The main components of tricalcium phosphate are P2O5 and CaO. Increasing the calcium oxide content in the formulation is also one of the sources of titanium sphene calcium. In glazes, tricalcium phosphate mainly acts as an opacifier and phase separation promoter, improving the hiding power and whiteness of the glaze. Simultaneously, tricalcium phosphate can reduce the melt viscosity of the glaze, improve its fluidity, and enhance its anti-fouling properties. Using tricalcium phosphate avoids the use of fluorine and chlorine impurities in apatite, which lower the melting temperature of the glaze and prevents the corrosiveness of equipment caused by fluorine and chlorine impurities. Compared to dicalcium phosphate and dicalcium phosphate, tricalcium phosphate has better high-temperature stability and is more suitable for high-temperature glaze systems that require high-temperature stability and opacification.

[0040] Calcium dicalcium phosphate: When heated above 36℃, it gradually loses its water of crystallization. At 400–430℃, it can be converted into calcium pyrophosphate (Ca2P2O7). It is unstable at high temperatures and easily undergoes phase transformation. It is suitable for use in glaze formulations sintered at low temperatures. For glazes requiring high-temperature stability and good opacity (such as bone china and daily-use porcelain), tricalcium phosphate is preferred.

[0041] If low-temperature melting is required, the glaze gloss needs to be adjusted, or different phosphorus elements need to be introduced, dicalcium phosphate can be used with caution, but attention should be paid to matching its decomposition temperature with the glaze firing curve.

[0042] Preferably, the chemical composition of the zirconium white ingot, by mass ratio, includes: SiO2 52~57%, Al2O3 5~12%, Fe2O3 0.1~0.5%, TiO2 0.01~0.5%, CaO 3~12%, MgO 1.0~4.5%, K2O 2~7%, ZnO 3~9%, ZrO2 6~12%, P2O5 1~4%.

[0043] Preferably, the fluxing component comprises the following raw materials in parts by weight: 5-12 parts of dolomite, 10-20 parts of calcite Potassium carbonate 5-10 parts.

[0044] Dolomite's main components are calcium oxide and magnesium oxide, calcite's main component is calcium oxide, and potassium carbonate mainly provides potassium oxide. All are used as fluxing components; too little addition results in high viscosity of the zirconium white frit, making feeding difficult, while too much leads to a higher glass phase and poor whitening effect. The combined application of dolomite and calcite simultaneously increases the CaO content in the glaze. Using these raw materials allows for a direct visual observation of the approximate calcium, magnesium, and potassium content in the flux system. As a simple substitution, other materials that can decompose to release calcium oxide, magnesium oxide, or potassium oxide at firing temperatures can also be used, such as potassium nitrate replacing potassium carbonate.

[0045] Preferably, the raw materials are mixed evenly according to the proportion, heated to a firing temperature of 1500~1600℃ for firing, and held at the firing temperature for 0.1~1h, then discharged and cooled to obtain zircon white frit.

[0046] The purpose of controlling the firing temperature of zirconium white frit to above 1500℃ is to ensure that the zirconium white frit has a suitable high-temperature viscosity for feeding, while an appropriate curing time ensures that the zirconium white frit can effectively precipitate titanium sphene crystals during the subsequent glaze firing process. The firing temperature and curing time are mutually adjustable. Generally, the higher the firing temperature, the shorter the curing time can be, while the longer the curing time, the longer the zirconium oxide crystallization time and the greater the number of crystals. However, it is necessary to avoid the problem of excessively long firing times leading to an increase in the glass phase content in the glaze. One purpose of zirconium white frit is to provide zirconium oxide crystals; secondly, because the calcium phosphate formed during frit firing is introduced into the raw material, it promotes titanium sphene crystallization; and thirdly, the frit contains a large amount of calcium oxide components, which promote titanium sphene crystallization during secondary applications.

[0047] In a specific embodiment, the temperature curve for sintering zircon white frit is set as follows: 0~300℃ for 2h, 300~1530℃ for 2.5h, and 1530℃ for 0.5h.

[0048] A reflective heat-insulating glaze, the raw materials of which include kaolin, titanium dioxide, potassium feldspar, wollastonite, barium carbonate and the above-mentioned zirconium white frit; According to the mass ratio, the chemical composition of the glaze includes: SiO2 45~52%, Al2O3 9~15%, Fe2O3 0.1~0.4%, TiO2 7~12%, CaO 8~15%, MgO 1~3%, BaO 2~6%, ZnO 1.5~5%, K2O 2~5%, Na2O 0.5~3%, ZrO2 2~4.5%, P2O5 0.2~1.5%, Weight loss upon ignition at 1000℃ is 2-5%; And according to the mass ratio, .

[0049] Applying zirconium white frit to titanium sphene glazes increases the whiteness and opacity of the fired glaze surface. Utilizing the different refractive indices of various crystals, the glaze layer contains titanium dioxide crystals, zirconium oxide crystals, titanium sphene crystals, and a glass matrix with refractive indices of 2.71, 2.2, 1.9, and 1.5, respectively, creating a refractive index gradient. These different refractive index materials construct multiple diffuse reflection paths, optimizing the overall optical uniformity of the glaze surface and reducing solar transmission and absorption. In particular, titanium sphene crystals, due to their high refractive index, exhibit a grain size close to the visible light band when precipitated at micron and submicron levels. This results in a strong opacity in the glaze surface, leading to efficient Mie scattering and reflection, further increasing the solar reflectance and achieving a high solar reflectance of 0.92.

[0050] Titanite crystals are monoclinic with a complex oxygen octahedral network; their crystal structure consists of Ca²⁺. + Ti 4+ It is composed of SiO4 tetrahedra, in which Ti 4+ Located in a distorted octahedral coordination environment surrounded by oxygen ions, this structure results in a high abundance of phonons in the lattice vibration modes, especially forming dense phonon absorption and re-radiation channels in the mid- and far-infrared bands.

[0051] The eutectic point of CaO-SiO2 binary eutectic is about 1436℃, that of CaO-TiO2 binary eutectic is about 1460℃, and that of CaO-TiO2-SiO2 ternary eutectic is about 1350℃. With the help of fluxing components such as potassium, sodium, calcium, magnesium, and zinc in the glaze, the eutectic melting point of titanium sphene will be further reduced to a firing temperature of about 1200℃ suitable for ceramic tiles. When the titanium dioxide in the raw material has a high Ca and Si content, a large amount of titanium sphene crystals will precipitate after firing, melting, and cooling.

[0052] After the precipitation of titanite crystals, a small amount of excess TiO2 glaze precipitates as rutile TiO2 crystals. TiO2, as one of the most potent white pigments and scatterers, has a refractive index as high as 2.71. Rutile TiO2 is tetragonal with a close-packed structure, making its structure more stable. 4+ With high charge density and strong polarization, it can significantly enhance the thermal excitation of the lattice dipole moment, strengthen the coupling between photons and lattice vibrational phonons, promote the emission efficiency of infrared photons, improve infrared emissivity, and achieve higher scattering in the infrared band. Specifically, the glaze is white, but the rutile crystals will give it a slightly yellowish tint. If there is an excess of TiO2, the yellow tint will become more pronounced. Therefore, the amount of TiO2 used must be limited to ensure that the glaze is milky white with a slight yellowish tint without turning into a yellow glaze.

[0053] In addition, high barium content can react with kaolin to form barium feldspar crystals, while low barium content will exist in the glaze in a glassy state, which increases the transparency and gloss of the glaze. High barium content exists in the glaze in the form of barium feldspar crystals. Since the crystals exist in the glaze in granular or columnar form, and the reflectivity of the crystals is different from that of the glassy state, the gloss of the glaze is effectively reduced.

[0054] The proposed reflective heat-insulating glaze simultaneously considers solar reflectance, whiteness, opacity, and anti-fouling performance. Under the condition that zirconium white frit provides phosphate as a phase separation and crystallization agent, wollastonite reacts with titanium dioxide at high temperature to precipitate titanium sphene microcrystals in situ. The grains are fine and uniform, the glaze surface is delicate and dense, and the opacity effect is good. This solves the problem that conventional titanium sphene glazes cannot achieve both high solar reflectance and high anti-fouling performance when titanium sphene powder is used directly.

[0055] Preferably, the ingredients, by weight, include the following raw materials: 5-10 parts of kaolin 5-10 parts titanium dioxide, 25-35 parts of zirconium white frit, Potassium feldspar 20-35 parts, 15-25 parts wollastonite 5-12 parts of barium carbonate.

[0056] In glaze raw materials, kaolin acts as a plastic raw material, providing suspension and viscosity. Too much kaolin results in poor glaze fluidity, while too little kaolin results in poor adhesion between the glaze and the base glaze layer.

[0057] Titanium dioxide is the main component in the synthesis of titanium sphene. Too much titanium dioxide will produce a large amount of golden-red titanium dioxide on the glaze, turning the glaze yellow; too little titanium sphene will result in fewer titanium sphene crystals, affecting the reflectivity.

[0058] Zirconium white frit mainly introduces zirconia microcrystals. Too much will increase the cost of the glaze, while less titanium sphene microcrystals will reduce the reflectivity. Too little will reduce the whitening effect of the glaze and lower the reflectivity.

[0059] Potassium feldspar is used as a fluxing component. Too much potassium feldspar results in a higher glass phase, increasing the glaze's transparency and decreasing its reflectivity; too little potassium feldspar results in a rough glaze and poor stain resistance. At the same time, boric acid and sodium feldspar should be avoided as the high transparency they exhibit after firing can negatively impact the glaze's whiteness.

[0060] Wollastonite is mainly composed of Ca3Si3O9, which is the main component in the synthesis of titanite. Too much wollastonite results in more glass phase transition and a decrease in reflectivity; too little wollastonite results in fewer titanite crystals and a decrease in reflectivity.

[0061] Barium carbonate is the main component that forms barium feldspar crystals. Too much barium carbonate inhibits the growth of titanite crystals and reduces reflectivity; too little barium carbonate forms a glassy phase and increases the luster of the glaze.

[0062] Preferably, the method for preparing the reflective heat-insulating glaze includes the following steps: S1. Weigh 100 parts of raw materials according to the proportion of raw materials for the glaze; S2. Add the weighed raw materials to the ball mill, and add 40 parts water and 0.12~5 parts grinding aid according to the mass ratio, and then ball mill. S3, ball milling until the ball specific gravity is 1.85~1.9g / cm³ 3 The fineness is 0.4~0.6g, which is calculated based on the residue on a 325-mesh sieve after 200g of slurry is passed through it to prepare the glaze slurry; S4. Apply glaze using glaze slurry, controlling the amount of glaze applied to be 50~55g / (350mm×350mm).

[0063] In a specific embodiment, a bell-shaped glazing process is used, resulting in a smoother glaze surface with lower surface roughness, which improves the reflectivity of the glaze. When the glaze slurry has a high specific gravity, glaze drift can easily occur during glazing, leading to significant thickness variations in the glaze layer.

[0064] The thickness of the glaze layer is limited by controlling the glaze weight parameters. The solar reflectance test is the sum of the incident and emitted amounts on the glaze surface and the entire glaze layer. The glaze surface is generally composed of three structures: glass phase, transparent crystalline phase, and opaque crystalline phase. Under the condition of containing opaque phase, the thicker the glaze, the higher the degree of opaque particles in the glaze. After the incident light passes through the transparent phase, it will also be reflected out of the glaze layer when it encounters the opaque crystalline phase, and the degree of reflection of the incident light is higher.

[0065] Preferably, the grinding aid comprises 0.12 parts sodium carboxymethyl cellulose, 0.42 parts sodium tripolyphosphate, and 0.05 parts preservative.

[0066] A high solar reflectance glaze, the surface of which is made of the above-mentioned reflective heat-insulating glaze, the firing temperature of the glaze is 1180~1230℃, the thickness is 0.16~0.17mm, the solar reflectance of the glaze is 0.92~0.925, and the anti-fouling performance of the glaze is level 5.

[0067] The glaze flux system is mainly composed of divalent alkaline earth flux system of calcium, barium and zinc. It has a wide firing temperature range. At the same time, a large number of crystals precipitate on the glaze surface and bond with the glass to form a dense body. Glaze crystallization requires a stable and uniform nucleation, growth and crystallization process. If there are many bubbles on the glaze surface, it will destroy the entire crystallization environment.

[0068] Meanwhile, TiO2, as an intermediate ion constituting the glassy or crystalline state, has a smaller ion field than zirconium and tin, and even smaller than silicon and aluminum. As a refractory oxide, its high-temperature viscosity is more suitable for a firing temperature of 1180~1230℃. It has a wider firing range when combined with divalent alkali metal fluxes, and its anti-fouling performance is guaranteed.

[0069] The glaze thickness should be between 0.16 and 0.17 mm. If it is too thin, the glazing process will be unstable and the glaze layer will be uneven. If it is too thick, the cost will increase.

[0070] The preparation methods of the zirconium white frits in Examples 1-3 are as follows: After weighing and mixing the raw materials according to the proportions shown in Table 1, the temperature curves were set as follows: 0~300℃ for 2h, 300~1530℃ for 2.5h, and 1530℃ for 0.5h. After heating and firing, the materials were discharged and cooled to obtain zirconium white frit.

[0071] The methods for preparing the glaze on the surfaces of Examples 4-9 are as follows: S1. Weigh 100 portions of raw materials according to the proportions shown in Tables 3 to 5 below; S2. Add the weighed raw materials to the ball mill, and according to the mass ratio, add 40 parts water, 0.12 parts sodium carboxymethyl cellulose, 0.42 parts sodium tripolyphosphate and 0.05 parts preservative, and then ball mill. S3, ball milling until the ball specific gravity is 1.85~1.9g / cm³ 3 A glaze slurry with a fineness of 0.4~0.6g was prepared. S4. Use glaze slurry for glazing, and control the amount of glaze to be 50~55g / (350mm×350mm); The glaze preparation method of Comparative Example 1 is the same as that of Example 4, except that Comparative Example 1 uses the same weight of titanium sphene powder instead of titanium dioxide. Since titanium sphene powder is directly added to the glaze, the content of titanium sphene crystals will be significantly less than that of titanium dioxide crystals, requiring an increase in the amount of titanium sphene powder. At the same time, in the application of a large amount of titanium sphene powder, it is necessary to control the particle size of the titanium sphene powder to ensure that it is not dissolved by the glassy phase in the glaze. Generally, the particle size is required to be larger than that of ordinary glaze. Adding a large amount of titanium sphene powder leads to unstable glaze performance and makes it difficult to control the anti-fouling performance.

[0072] The glaze preparation method for Comparative Example 2 is the same as in Example 4, except that quartz was used instead of wollastonite in Comparative Example 2 in the same weight proportions. Because the calcium oxide content in the formula is significantly reduced, the glaze's crystalline composition is no longer dominated by titanium sphene, but rather becomes a titanium-based yellow glaze. The reason for this is that, with the TiO2 content in the glaze remaining essentially unchanged, TiO2 is in an absolute excess state in the glaze and will dissolve in the vitreous layer, resulting in a very obvious yellow glaze surface and a sharp decrease in solar reflectance.

[0073] Finally, the anti-fouling level was tested according to GB / T3810.14-2016, and according to GB / T 31389... The solar reflectance (wavelength 300nm~2500nm) was tested in 2015, and the specific data are summarized in Tables 1-7 below.

[0074] Table 1. Raw materials / parts by weight of zirconium white ingot

[0075] Table 2 Chemical composition of zirconium white ingot / %

[0076] Table 3 Raw materials / parts by weight for surface glaze

[0077] Table 4 Raw materials / parts by weight for surface glaze

[0078] Table 5 Raw materials / parts by weight for surface glaze

[0079] Table 6 Chemical composition of raw materials for surface glaze / %

[0080] Table 7 Summary of Test Performance

[0081] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0082] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A reflective heat-insulating glaze, characterized in that, The raw materials consist of kaolin, titanium dioxide, potassium feldspar, wollastonite, barium carbonate, and zirconium dioxide frit. According to the weight parts, the raw materials of the zircon white fused block are composed of 12-20 parts of kaolin, 8-15 parts of zircon powder, 30-42 parts of quartz, 3-8 parts of zinc oxide, 3-8 parts of calcium phosphate and 20-42 parts of fluxing components; The method for preparing the zircon white fused block is as follows: after mixing the raw materials of the zircon white fused block evenly according to the proportion, the temperature is raised to a firing temperature of 1500~1600℃ for firing, and the firing temperature is held for 0.1~1h. The material is then discharged and cooled to obtain the zircon white fused block. According to the mass ratio, the chemical composition of the glaze includes: SiO2 45~52%, Al2O39~15%, Fe2O3 0.1~0.4%, TiO2 7~12%, CaO 8~15%, MgO 1~3%, BaO2~6%, ZnO 1.5~5%, K2O2~5%, Na2O 0.5~3%, ZrO2 2~4.5%, P2O5 0.2~1.5%, Weight loss upon ignition at 1000℃ is 2-5%; And according to the mass ratio, .

2. The reflective heat-insulating glaze according to claim 1, characterized in that, The calcium phosphate salt is tricalcium phosphate.

3. The reflective heat-insulating glaze according to claim 2, characterized in that, According to the mass ratio, the chemical composition of the zirconium white ingot includes: SiO2 52~57%, Al2O35~12%, Fe2O3 0.1~0.5%, TiO2 0.01~0.5%, CaO 3~12%, MgO 1.0~4.5%, K2O2~7%, ZnO3~9%, ZrO2 6~12%, P2O5 1~4%.

4. The reflective heat-insulating glaze according to claim 1, characterized in that, By weight, the fluxing component includes the following raw materials: 5-12 parts of dolomite, 10-20 parts of calcite Potassium carbonate 5-10 parts.

5. The reflective heat-insulating glaze according to claim 1, characterized in that, The raw materials for the glaze, by weight, are: 5-10 parts of kaolin 5-10 parts titanium dioxide, 25-35 parts of zirconium white frit, Potassium feldspar 20-35 parts, 15-25 parts wollastonite 5-12 parts of barium carbonate.

6. The reflective heat-insulating glaze according to claim 1 or 5, characterized in that, The preparation method of the reflective heat-insulating glaze includes the following steps: S1. Weigh 100 parts of raw materials according to the proportion of raw materials for the glaze; S2. Add the weighed raw materials to the ball mill, and add 40 parts water and 0.12~5 parts grinding aid according to the mass ratio, and then ball mill. S3, ball milling until the ball specific gravity is 1.85~1.9g / cm³ 3 The fineness is 0.4~0.6g, which is measured by the amount of residue after 200g of slurry passes through a 325-mesh sieve, and the reflective heat-insulating glaze is prepared.

7. The reflective heat-insulating glaze according to claim 6, characterized in that: The grinding aid comprises 0.12 parts sodium carboxymethyl cellulose, 0.42 parts sodium tripolyphosphate, and 0.05 parts preservative.

8. A high solar reflectance glaze, applied to ceramic tiles, characterized in that: The glaze is made by firing the reflective heat-insulating glaze as described in any one of claims 5-7. The firing temperature of the glaze is 1180~1230℃, the thickness is 0.16~0.17mm, the solar reflectance of the glaze is 0.92~0.925, and the anti-fouling performance of the glaze is level 5.

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