High-strength lightweight daily-use ceramic and preparation method thereof

Abstract

The application relates to the technical field of special ceramics and daily-use ceramics, in particular to high-strength lightweight daily-use ceramics and a preparation method thereof, and the raw material composition and weight percentage of the body of the high-strength lightweight daily-use ceramics are as follows: talc 35-60%; calcite 5-15%; feldspar 5-18%; quartz 8-25%; bentonite 3-8%; washed mud 5-15%; the total content of alumina in the raw material composition is not more than 8%; the main crystal phase of the high-strength lightweight daily-use ceramics is original enstatite and alpha-cristobalite, and the original enstatite is generated by the reaction of talc, calcite and quartz at high temperature; through unique crystal phase structure design, the key indexes such as the Vickers hardness, bending strength and light transmittance of the prepared ceramic product have reached the performance level of lightweight light-transmitting special ceramics, but the raw material cost and sintering energy consumption are only one sixth of those of traditional special ceramics, so that the high-strength lightweight daily-use ceramics can also be applied to the field of daily-use ceramics with higher cost requirements.

Description

Technical Field

[0001] This invention relates to the field of special ceramics and daily-use ceramics technology, specifically to a high-strength, lightweight daily-use ceramic and its preparation method. Background Technology

[0002] Traditional high-strength daily-use ceramic systems primarily rely on introducing a large amount of alumina (Al2O3) into the formula. By increasing the aluminum content, high-hardness crystalline phases such as corundum (α-Al2O3) or mullite (3Al2O3·2SiO2) are generated at high temperatures, thereby improving the mechanical strength of the ceramic body. For example, the alumina content in traditional hard ceramic formulas is usually above 20%, and even reaches 30% to 45% by adding industrial alumina powder to achieve a Vickers hardness exceeding 6.0 GPa.

[0003] However, this traditional technical approach has several drawbacks:

[0004] First, the high aluminum content leads to a sharp increase in firing temperature. Alumina has a melting point as high as 2050℃ and is an extremely strong refractory oxide. The higher the aluminum content in the formula, the higher the required vitrification firing temperature, typically reaching 1280℃ to 1420℃. This means huge energy consumption and production costs, which runs counter to the current trend of green and low-carbon development.

[0005] Secondly, it hinders the achievement of lightweight design. The high firing temperature makes it difficult for the body to achieve sufficient densification through liquid-phase sintering during firing, often requiring the addition of more fluxing materials. At the same time, high-alumina ceramics generally have a high density (usually ≥2.6 g / cm³), making it difficult to achieve the effect of "thin body and lightweight".

[0006] Third, poor light transmittance. The main crystalline phase of high-alumina ceramics, mullite and residual quartz, have a significantly different refractive index from the surrounding glassy phase, and the grains are often interwoven in a needle-like pattern, which severely scatters visible light, resulting in extremely low or even completely opaque light transmittance of the ceramic body. Furthermore, although talc has been used in traditional ceramics, its role has almost exclusively been to utilize its high magnesium oxide content as a powerful flux to "cool down" the firing process and broaden the firing range. It has never been used to explore the technological inspiration of constructing entirely new crystalline phase structures through talc to simultaneously achieve high strength, high light transmittance, and lightweight properties.

[0007] Currently, achieving high-strength, high-transmittance ceramics with a Vickers hardness exceeding 6 GPa and visible light transmittance exceeding 10% typically relies on special ceramic systems such as alumina, zirconium oxide, and spinel. While these systems offer excellent performance, their extremely high firing temperatures (typically >1600℃), high raw material costs, and complex sintering processes (such as hot isostatic pressing) limit their application in the cost-sensitive field of daily-use ceramics. Therefore, we propose a high-strength, lightweight ceramic and its preparation method that combines the mechanical properties of special ceramics with the low-cost advantages of daily-use ceramics. Summary of the Invention

[0008] The purpose of this invention is to provide a high-strength, lightweight daily-use ceramic and its preparation method, so as to solve the technical problems mentioned in the background art.

[0009] This invention provides a high-strength, lightweight daily-use ceramic, the composition and weight percentage of its body raw materials are as follows:

[0010] Talc 35%–60%;

[0011] Calcite 5%–15%;

[0012] Feldspar 5%–18%;

[0013] Quartz 8%–25%;

[0014] Bentonite 3%–8%;

[0015] Washing mud 5%–15%;

[0016] The total alumina content in the raw material composition does not exceed 8%;

[0017] The main crystalline phases of the high-strength lightweight daily-use ceramics are protoenzyme and α-cristobalite. The protoenzyme is generated by the reaction of talc, calcite and quartz at high temperature, and the α-cristobalite is formed by the crystal transformation of quartz at high temperature.

[0018] As a preferred embodiment of the present invention, the talc is calcined talc or raw talc, with a magnesium oxide content ≥28%, a silicon oxide content ≥55%, and a loss on ignition ≤8%; the weight percentage of the talc is 42% to 55%.

[0019] As a preferred embodiment of the present invention, the calcite has a calcium oxide content of ≥52% and a weight percentage of 8% to 12%; the feldspar is potassium feldspar, sodium feldspar, or a mixture of both, and its total potassium oxide and sodium oxide content is ≥8% and a weight percentage of 10% to 15%.

[0020] As a preferred embodiment of the present invention, the quartz is vein quartz or quartz sand, with a silicon dioxide content ≥98% and a weight percentage of 15% to 22%; the bentonite is calcium-based bentonite or sodium-based bentonite, with a montmorillonite content ≥60% and a weight percentage of 4% to 6%.

[0021] As a preferred embodiment of the present invention, the washed mud is kaolin clay with an alumina content of 25% to 35%, a plasticity index of ≥15, and a weight percentage of 8% to 12%.

[0022] As a preferred embodiment of the present invention, the weight ratio of talc to calcite is in the range of (4-8):1; by controlling this ratio, magnesium oxide and calcium oxide in the formula react at high temperature to generate calcium magnesium silicate eutectic, which promotes the full development of the original enstatite crystal phase and forms an interwoven structure with the α-cristobalite crystal phase transformed from quartz crystal form.

[0023] A method for preparing high-strength, lightweight daily-use ceramics includes the following steps:

[0024] (1) Weigh each raw material according to the proportion, mix talc, calcite, feldspar and quartz and then perform wet ball milling to obtain a hard slurry;

[0025] (2) Disperse bentonite and washed mud in water to make a soft slurry, then mix it with the hard slurry obtained in step (1), and perform a second ball milling to obtain a mixed slurry;

[0026] (3) Pass the mixed slurry through a 200-300 mesh sieve to remove iron, then press and filter to dewater to obtain mud cake;

[0027] (4) The clay cake is kneaded and aged, and then rolled or pressed to obtain the blank;

[0028] (5) Dry the green body at 60-100℃ until the moisture content is less than 2%;

[0029] (6) The dried green body is fired once in an oxidizing atmosphere at 1160-1260℃ for 20-60 minutes to obtain the high-strength lightweight daily ceramic.

[0030] As a preferred embodiment of the present invention, in step (1), during wet ball milling, the weight ratio of material:ball:water is 1:(1.5~2.5):(0.6~1.0), the ball milling time is 2~6 hours, and the particle size of the hard slurry after ball milling reaches ≤2.5% on a 10,000-mesh sieve.

[0031] As a preferred embodiment of the present invention, the secondary ball milling time in step (2) is 1 to 3 hours, and the particle size of the resulting mixed slurry reaches ≤1.0% on a 10,000-mesh sieve; the aging time in step (4) is 48 to 96 hours.

[0032] As a preferred embodiment of the present invention, the firing conditions in step (6) are: room temperature to 900°C, with a heating rate of 5 to 8°C / min; 900°C to the maximum firing temperature, with a heating rate of 2 to 4°C / min; the maximum firing temperature is 1190 to 1230°C, and the holding time is 30 to 45 minutes.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] This invention changes the conventional understanding of talc as merely a cooling agent, increasing its content to 35%–60% to serve as the main structural builder of the ceramic body. At a relatively low temperature of 1160–1260°C, the magnesium oxide in talc reacts with the calcium oxide and quartz (SiO2) produced by the decomposition of calcite (CaCO3) to generate a large number of fine protoencipite (MgO·SiO2) crystals. Protoencipite is a chain-like silicate mineral with high hardness and low density. Simultaneously, some quartz irreversibly transforms into α-cristobalite at high temperatures. The refractive index of cristobalite is very close to that of the magnesium-rich glass phase. When light passes through the ceramic body, the loss due to scattering at grain boundaries is minimal, thus achieving light transmittance far superior to traditional high-alumina ceramics. Furthermore, the tightly interwoven protoencipite and cristobalite form a rigid network framework, endowing the ceramic body with high strength.

[0035] In this invention, during the high-temperature heat treatment process, talc (3MgO·4SiO2·H2O) first decomposes into magnesium metasilicate and quartz at approximately 900℃. As the temperature continues to rise, the calcium oxide (CaO) produced by the decomposition of calcite, along with excess silicon oxide released from talc and magnesium metasilicate, forms a ternary eutectic (liquid phase) of CaO-MgO-SiO2. The formation temperature of this liquid phase is much lower than the reaction temperature of the pure MgO-SiO2 system. This calcium-magnesium-silicon liquid phase can dissolve the fine protoenstatite rudimentary crystals produced by the decomposition of talc. After reaching supersaturation, these rudimentary crystals precipitate and grow uniformly on them, thereby promoting the full development and homogenization of protoenstatite crystals at a lower temperature (1160–1260℃). This calcium-magnesium-silicon liquid phase has good fluidity and wettability, which can fully fill the pores of the green body, driving densification. This allows the invention to be completely sintered at a low temperature of 1160–1260℃, achieving energy-saving effects. The glass phase formed by cooling the calcium magnesium silicon liquid phase has a refractive index that perfectly matches the α-cristobalite crystal phase formed simultaneously, which greatly reduces grain boundary light scattering and gives the ceramic good light transmittance.

[0036] The present invention controls the total alumina content to below 8%. This extremely low aluminum content is a prerequisite for ensuring that the above-mentioned reaction and structure can be realized. If the alumina content is too high, aluminum ions will competitively consume calcium oxide and magnesium oxide, generating impurities such as anorthite or magnesium aluminum spinel with high melting point and large refractive index difference, which will hinder the development of protoenzyme and the formation of the light-transmitting interface, and drastically increase the firing temperature.

[0037] This invention breaks through the technical barriers between special ceramics and daily-use ceramics through a unique crystal phase structure design. The ceramic products produced have reached the performance level of lightweight, translucent special ceramics in key indicators such as Vickers hardness (5.8-6.8 GPa), flexural strength (105-122 MPa), and light transmittance (9.2-14.5%). However, its raw material cost and firing energy consumption are only a fraction of those of traditional special ceramics, making it applicable to the field of daily-use ceramics where cost requirements are high. Detailed Implementation

[0038] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0039] The sources and specifications of the raw materials used in the following examples and comparative examples are as follows:

[0040] Talc: Black or white talc from Guangfeng, Jiangxi Province is selected, with MgO content ≥30%, SiO2 content ≥58%, Fe2O3 content ≤0.5%, and loss on ignition ≤6%.

[0041] Calcite: Selected from Hezhou, Guangxi, with CaO content of 54.5%, SiO2 content of 1.2%, and loss on ignition of 42.8%.

[0042] Feldspar: Potassium-sodium feldspar from Yichun, Jiangxi Province, with K2O content of 9.5%, Na2O content of 5.2%, Al2O3 content of 18.1%, and SiO2 content of 65.3%.

[0043] Quartz: Vein quartz from Heyuan, Guangdong Province, with a SiO2 content of 99.2%.

[0044] Bentonite: Calcium-based bentonite from Jianping, Liaoning Province, with a montmorillonite content of 72% and a plasticity index of 25 was selected.

[0045] The clay used for washing is kaolin from Xingzi, Jiangxi Province, with an Al2O3 content of 30.5%, a SiO2 content of 47.8%, and a plasticity index of 18.

[0046] This embodiment provides a method for preparing high-strength, lightweight daily-use ceramics, including the following steps:

[0047] Step 1: Ingredient Preparation: According to the formula design, accurately weigh talc, calcite, feldspar, quartz, bentonite, and washed mud using an electronic scale, with a weighing accuracy of ±0.05 kg. Place the weighed raw materials into different hoppers. Hard raw materials (talc, calcite, feldspar, and quartz) will be added to the ball mill together, while soft raw materials (bentonite and washed mud) will be added later.

[0048] Step 2: Preparation of Hard Slurry (Single Ball Milling): After thoroughly mixing the talc, calcite, feldspar, and quartz weighed in Step 1, add them to an intermittent wet ball mill. Add grinding media (high-alumina balls, 20-40mm in diameter) and water to the ball mill, controlling the weight ratio of material, balls, and water to be 1:2:0.8. Start the ball mill for wet grinding to fully crush and mix the hard raw materials, obtaining a hard slurry.

[0049] Step 3: Preparation of the Mixed Slurry (Secondary Ball Milling): Add the weighed bentonite and washed mud from Step 1 to another mixing tank, add an appropriate amount of water, and start the high-speed disperser to stir for 30 minutes to prepare a fully dispersed soft slurry. Then, pump all of this soft slurry into the ball mill containing the hard slurry obtained in Step 2, add water to the total amount required for the process, and continue the secondary wet ball milling to ensure that all raw materials are fully mixed and reach the specified fineness, thus obtaining the mixed slurry.

[0050] Step 4, Sieving and Iron Removal: The mixed slurry obtained in Step 3 is discharged from the ball mill and passed through a 250-mesh vibrating screen to remove coarse particles or impurities. The slurry after sieving flows into a storage tank equipped with a high-gradient permanent magnet iron separator. The slurry is circulated through the iron separator at least 3 times to maximize the removal of iron carried in by the raw materials and generated by ball mill wear, ensuring the whiteness of the porcelain body.

[0051] Step 5: Filtration and Dewatering: The slurry after iron removal in Step 4 is pumped into a chamber filter press using a diaphragm pump and dewatered under a pressure of 1.2 MPa. When the filtrate flow rate decreases significantly, the slurry feed is stopped, and compressed air is introduced to blow the filter element for 15 minutes to further reduce the moisture content of the filter cake. After filtration is completed, the filter cake is removed; at this point, the moisture content of the filter cake is controlled at 23% ± 1%.

[0052] Step Six: Clay Preparation and Aging: The clay cake obtained in Step Five is fed into a vacuum clay preparation machine via conveyor belt. The vacuum degree of the clay preparation machine is -0.095 MPa. After initial preparation, crushing, and re-kneading, the clay is extruded into cylindrical clay segments. These segments are cut into 5kg blocks, wrapped in plastic film, and placed in a temperature- and humidity-controlled aging chamber. The aging environment conditions are: temperature 20℃±2℃, relative humidity 90%±5%.

[0053] Step 7: Roll forming: Take out the clay block from Step 6, knead it again in a vacuum clay mixer, extrude solid clay segments, cut clay blocks of appropriate weight according to the target shape, place them in a plaster mold, and roll form them using a roll forming machine to obtain a 6-inch shallow dish blank with uniform thickness. During roll forming, the roller head speed is 400 rpm, the plaster mold speed is 600 rpm, and the forming time is 10 seconds.

[0054] Step 8: Green Body Drying: Place the molded green body formed in Step 7 into an intermittent hot air dryer. First, dry it at 40℃ for 4 hours with the mold on to allow the green body to initially set and gain a certain strength. Then, remove the plaster mold and continue drying the green body in the dryer with stepped temperature increases: dry at 60℃ for 2 hours, dry at 80℃ for 2 hours, and finally dry at 100℃ until the moisture content of the green body is below 2% as measured by a rapid moisture analyzer. The dehumidifying fan is on throughout the drying process.

[0055] Step Nine, First Firing: Carefully place the qualified green bodies, dried in Step Eight and inspected for cracks and deformation, onto silicon carbide racks and push them into a high-temperature shuttle kiln. Use clean natural gas as fuel and fire at atmospheric pressure in an oxidizing atmosphere. The firing process is automatically controlled by a programmable logic controller (PLC) according to a set firing curve. After firing, allow the kiln to cool naturally to room temperature before removing the ceramic product, thus obtaining the finished ceramic product of this invention.

[0056] The following examples and comparative examples are based on the general preparation process described above, with adjustments made to the raw material ratios and / or some process parameters.

[0057] Example 1

[0058] This embodiment follows the overall preparation process described above, and the specific formula and process parameters are as follows:

[0059] Formula (by weight): 46 parts talc, 10 parts calcite, 14 parts feldspar, 20 parts quartz, 5 parts bentonite, and 5 parts washed mud. The total alumina content in this formula is 3.9%, and the weight ratio of talc to calcite is 4.6:1.

[0060] Step 2 Process Parameters: The ball mill loading capacity for hard raw materials is 500 kg, the grinding media (high-alumina balls) weight is 1000 kg, and the added water volume is 400 kg. The ball mill speed is 16 rpm, and the ball milling time is 5 hours per cycle. After ball milling, a sample is taken and tested using a 325-mesh sieve; the residue on the sieve is 2.0%.

[0061] Step 3 Process Parameters: During the preparation of the soft slurry, add 100 kg of clean water to the mixture of bentonite and washed mud and stir to disperse. After incorporating the soft slurry into the hard slurry, add 50 kg of clean water, and perform a second ball milling for 2 hours. After the second ball milling, take a sample and test it using a 325-mesh sieve; the residue should be 0.5%.

[0062] Step 6 process parameters: The aging time for the mud cake is 72 hours.

[0063] Step 9 Process Parameters: The maximum firing temperature is set to 1230℃. The specific firing curve is as follows: from room temperature to 900℃, the heating rate is 6℃ / min; from 900℃ to 1230℃, the heating rate is 3℃ / min; hold at 1230℃ for 40 minutes. The total firing cycle is 8.5 hours.

[0064] Example 2

[0065] This embodiment follows the overall preparation process described above, and the specific formula and process parameters are as follows:

[0066] Formula (by weight): 52 parts talc, 8 parts calcite, 10 parts feldspar, 18 parts quartz, 4 parts bentonite, and 8 parts washed mud. The total alumina content in this formula is 4.4%, and the weight ratio of talc to calcite is 6.5:1.

[0067] Step 2 process parameters: The ball mill loading capacity for hard raw materials is 500 kg, the grinding media weight is 1250 kg (material-to-ball ratio 1:2.5), and the added water is 450 kg. One ball milling cycle is 4 hours, and the residue on a 325 mesh sieve after ball milling is 2.3%.

[0068] Step 3 process parameters: The water consumption for preparing the soft slurry is 120 kg. After combining the soft and hard slurries, add 20 kg of clean water. The secondary ball milling time is 1.5 hours. The residue on a 325-mesh sieve after the secondary ball milling is 0.6%.

[0069] Step 6 process parameters: aging time is 96 hours.

[0070] Step 9 Process Parameters: The maximum firing temperature is set to 1190℃. The specific firing curve is as follows: from room temperature to 900℃, the heating rate is 8℃ / min; from 900℃ to 1190℃, the heating rate is 4℃ / min; hold at 1190℃ for 60 minutes. The total firing cycle is 7.5 hours.

[0071] Example 3

[0072] This embodiment follows the overall preparation process described above, and the specific formula and process parameters are as follows:

[0073] Formula (by weight): 39 parts talc, 13 parts calcite, 16 parts feldspar, 23 parts quartz, 6 parts bentonite, and 3 parts washed mud. The total alumina content in this formula is 2.8%, and the weight ratio of talc to calcite is 3.0:1.

[0074] Step 2 process parameters: The ball mill loading capacity for hard raw materials is 500 kg, the grinding media weight is 750 kg (material-to-ball ratio 1:1.5), and the added water is 300 kg. One ball milling cycle is 7 hours, and the residue on a 325-mesh sieve after ball milling is 1.8%.

[0075] Step 3 process parameters: 150 kg of water is used for preparing the soft slurry. After combining the soft and hard slurries, 100 kg of clean water is added. The second ball milling time is 1 hour. The residue on a 325-mesh sieve after the second ball milling is 0.8%.

[0076] Step 6 process parameters: aging time is 48 hours.

[0077] Step 9 Process Parameters: The maximum firing temperature is set to 1250℃. The specific firing curve is as follows: from room temperature to 900℃, the heating rate is 5℃ / min; from 900℃ to 1250℃, the heating rate is 2℃ / min; hold at 1250℃ for 30 minutes. The total firing cycle is 9.2 hours.

[0078] Example 4

[0079] This embodiment follows the overall preparation process described above, and the specific formula and process parameters are as follows:

[0080] Formula (by weight): 55 parts talc, 10 parts calcite, 5 parts feldspar, 20 parts quartz, 6 parts bentonite, and 4 parts washed mud. The total alumina content in this formula is 3.0%, and the weight ratio of talc to calcite is 5.5:1.

[0081] Step 2 process parameters: The ball mill loading capacity for hard raw materials is 500 kg, the grinding media weight is 1000 kg, and the water added is 500 kg (material-to-water ratio 1:1). The ball milling time is 3 hours per cycle, and the residue on a 325-mesh sieve after ball milling is 2.8%.

[0082] Step 3 process parameters: The water consumption for preparing the soft slurry is 100 kg. No additional water is added after the soft and hard slurries are combined. The secondary ball milling time is 3 hours. The residue on a 325-mesh sieve after the secondary ball milling is 0.3%.

[0083] Step 6 process parameters: aging time is 60 hours.

[0084] Step 9 Process Parameters: The maximum firing temperature is set to 1180℃. The specific firing curve is as follows: from room temperature to 900℃, the heating rate is 7℃ / min; from 900℃ to 1180℃, the heating rate is 3℃ / min; hold at 1180℃ for 45 minutes. The total firing cycle is 7.8 hours.

[0085] Comparative Example 1

[0086] The preparation process of this comparative example is exactly the same as that of Example 1, to demonstrate the impact of the absence of the key component calcite on performance.

[0087] Formula (by weight): Talc 46 parts, calcite 0 parts, feldspar 18 parts, quartz 26 parts, bentonite 5 parts, washed mud 5 parts. This formula contains no calcite and is completely free of it. The total alumina content is 4.2%.

[0088] Step 2 process parameters: consistent with Example 1, ball milling time 5 hours, 2.1% residue on 325 mesh sieve.

[0089] Step 3 process parameters: consistent with Example 1, secondary ball milling time 2 hours, 325 mesh sieve residue 0.5%.

[0090] Step 6 process parameters: consistent with Example 1, aging time 72 hours.

[0091] Step 9 Process parameters: Same as in Example 1, firing temperature 1230℃, holding time 40 minutes.

[0092] Comparative Example 2

[0093] The preparation process of this comparative example is basically the same as that of Example 1, but the alumina content in the formula is greatly increased by increasing the amount of sludge used, to demonstrate the necessity of strictly controlling the low aluminum content.

[0094] Formula (by weight): 20 parts talc, 8 parts calcite, 25 parts feldspar, 24 parts quartz, 8 parts bentonite, and 15 parts washed mud. The total alumina content of this formula is as high as 15.8%, and the weight ratio of talc to calcite is 2.5:1.

[0095] Step 2 process parameters: consistent with Example 1, ball milling time 5 hours, 2.2% residue on 325 mesh sieve.

[0096] Step 3 Process Parameters: Due to the significant increase in the proportion of plastic material, the water consumption for preparing the soft slurry is increased to 200 kg to prevent poor slurry fluidity. After incorporating the hard slurry, the secondary ball milling time is 2 hours, and the residue on a 325-mesh sieve is 0.7%.

[0097] Step 6 process parameters: consistent with Example 1, aging time 72 hours.

[0098] Step 9 Process parameters: Same as in Example 1, firing temperature 1230℃, holding time 40 minutes.

[0099] Comparative Example 3

[0100] This comparative example was prepared using a typical formulation approach for traditional high-alumina hard ceramics, without employing the specific formulation and firing conditions of this invention, in order to demonstrate the comprehensive superiority of this invention over traditional technologies.

[0101] Formula (by weight): 35 parts industrial alumina, 30 parts feldspar, 15 parts quartz, 5 parts bentonite, and 25 parts washed clay (kaolin). The total alumina content in this formula is as high as 45.5%. The industrial alumina used has a purity of 99.5% and an average particle size of 5 micrometers. The initial formulation does not contain talc or calcite and fully adopts the high-alumina strengthened ceramic technology route.

[0102] Step 2 Process Parameters: Due to the high hardness and difficulty in crushing industrial alumina, alumina, feldspar, and quartz are fed into the ball mill together. The ball milling time is extended to 12 hours per cycle, and the material-to-ball-to-water ratio is the same as in Example 1. After one ball milling cycle, the residue on a 325-mesh sieve is 1.5%.

[0103] Step 3 process parameters: Disperse the bentonite and washed mud with water and feed them into a ball mill. The secondary ball milling time is 4 hours. After the secondary ball milling, the residue on a 325-mesh sieve is 0.4%.

[0104] Step 6 process parameters: aging time 72 hours.

[0105] Step Nine: Process Parameters: Based on the traditional firing requirements of high-alumina reinforced ceramics, the maximum firing temperature is set to 1310℃. The firing curve is as follows: from room temperature to 900℃, the heating rate is 5℃ / min; from 900℃ to 1310℃, the heating rate is 2℃ / min; hold at 1310℃ for 60 minutes. Then cool with the furnace.

[0106] Comparative Example 4

[0107] The preparation process of this comparative example is exactly the same as that of Example 1 in all aspects, including formulation, ball milling, aging, and drying. The only difference is that a temperature lower than that required by the present invention was used in the firing process, to demonstrate that the firing conditions are an essential component for achieving the effects of the present invention.

[0108] Formula (by weight): 46 parts talc, 10 parts calcite, 14 parts feldspar, 20 parts quartz, 5 parts bentonite, and 5 parts washed mud. The total alumina content is 3.9%, and the weight ratio of talc to calcite is 4.6:1.

[0109] Step 2 process parameters: consistent with Example 1, ball milling time 5 hours, 2.1% residue on 325 mesh sieve.

[0110] Step 3 process parameters: consistent with Example 1, secondary ball milling time 2 hours, 325 mesh sieve residue 0.5%.

[0111] Step 6 process parameters: consistent with Example 1, aging time 72 hours.

[0112] Step Nine: Process Parameters: The highest firing temperature set in this comparative example is 1120℃, which is lower than the lower limit of this invention. The specific firing curve is as follows: from room temperature to 900℃, the heating rate is 6℃ / min; from 900℃ to 1120℃, the heating rate is 3℃ / min; hold at 1120℃ for 40 minutes, and then cool with the furnace.

[0113] Performance Testing and Results Analysis

[0114] To verify the technical effects of the present invention, the ceramic samples obtained in Examples 1-4 and Comparative Examples 1-4 were subjected to the following tests:

[0115] Volume density test

[0116] Test method: Archimedes' displacement method was used with an electronic analytical balance with an accuracy of 0.0001g. First, the dry weight of the sample in air (m1) was measured. Then, the sample was placed in distilled water and evacuated in a vacuum container with a vacuum degree of -0.1MPa for 30 minutes to ensure that the open pores were completely filled with water. After removal, excess water droplets on the sample surface were wiped off with a lint-free cloth saturated with water, and the mass of the saturated sample in air (m2) was measured. Finally, the sample was suspended in water and its mass in water (m3) was measured. The bulk density of the sample was calculated using the formula: bulk density = m1 / (m2 - m3), with the unit being g / cm³.

[0117] Vickers hardness test

[0118] Test method: Cut 10mm × 10mm cubes from the flat bottom of the finished shallow dish, mount them with cold-mounting material, and then polish the surface to a mirror finish using diamond polishing paste. Use a digital Vickers hardness tester with a load of 1kg force (9.8N) and a holding time of 15 seconds. Randomly select 10 points on the surface of each sample for indentation testing, and measure the length of the diagonal of the indentation. The instrument automatically calculates and displays the Vickers hardness value (GPa). The final result is the arithmetic mean of the 10 points.

[0119] Three-point bending strength test

[0120] Test Method: A 3mm × 4mm × 40mm test strip was cut from the finished shallow tray using a precision cutting machine. All edges of the test strip were lightly chamfered with 600-grit sandpaper to eliminate stress concentration points. The test was conducted on a universal testing machine using a three-point bending mode. The lower span of the clamp was set to 30mm, and the upper indenter applied downward pressure at a constant rate of 0.5mm / min. The maximum load value (F) at which the test strip broke was recorded. The bending strength (MPa) was calculated using the formula: Bending Strength = (3 × F × L) / (2 × b × h²), where L is the span (30mm), b is the width of the test strip, and h is the thickness of the test strip. Five test strips were tested for each sample, and the average value was taken.

[0121] Total transmittance test

[0122] Test method: Take the bottom of the finished shallow dish and cut a 20mm×20mm cube using a diamond slicer. The sample was thinned by double-sided grinding on a glass plate using boron carbide powder of different particle sizes, followed by double-sided mirror polishing with 1-micron diamond polishing paste. The final thickness was precisely controlled to 1mm±0.02mm using a micrometer. The polished sheet was placed in the sample chamber of a UV-Vis spectrophotometer, and baseline correction was performed against an air background. The transmittance (%) at a visible light wavelength of 550nm was measured. 550nm represents the visible light band most sensitive to the human eye; the higher the value, the better the light transmittance of the porcelain.

[0123] Qualitative analysis of the main crystal phase

[0124] Test method: The fresh fracture surface after the above bending strength test was carefully preserved, and phase analysis was performed on the fracture surface using X-ray diffraction (XRD). Test conditions: Cu target Kα radiation, scanning angle (2θ) range of 10° to 80°, scanning speed of 4° / min. The diffraction patterns were compared and phases were identified using the JCPDS standard card.

[0125] The test results are shown in Table 1.

[0126] Test Project Bulk density (g / cm³) Vickers hardness (GPa) Flexural strength (MPa) Light transmittance (%) Main crystal phase Example 1 2.46 6.3 115 11.5 Protoencipite and α-cristobalite Example 2 2.42 6.8 122 13.8 Protoencipite and α-cristobalite Example 3 2.49 5.8 105 9.2 Protoencipite and α-cristobalite Example 4 2.39 6.7 118 14.5 Protoencipite and α-cristobalite Comparative Example 1 2.61 4.2 72 2.5 No characteristic peaks of α-cristobalite were observed in the original enstatite and tridymite. Comparative Example 2 2.58 5.5 95 1.8 Mullite, protoencipite and residual quartz Comparative Example 3 2.55 5.8 102 3.5 Mullite, quartz, and a small amount of glassy phase diffuse peaks Comparative Example 4 2.31 3.8 55 7.0 Enstatite and a large amount of unreacted quartz

[0127] By summarizing all the above performance test data, the following comparative analysis can be performed:

[0128] Overall superiority of the embodiments of the present invention over traditional materials

[0129] The representative properties of all examples (1-4) were directly compared with those of Comparative Example 3, which represents conventional high-alumina reinforced ceramics. The results showed that Example 2, fired at the lowest temperature of 1190°C, achieved a Vickers hardness of 6.8 GPa, a flexural strength of 122 MPa, and a light transmittance of 13.8%, with a bulk density of only 2.42 g / cm³. In contrast, Comparative Example 3, fired at a high temperature of 1310°C, achieved a hardness of only 5.8 GPa, a strength of 102 MPa, extremely poor light transmittance (3.5%), and a density as high as 2.55 g / cm³. This means that by significantly reducing the firing temperature by 120°C from 1310°C, the product produced by this invention has 17% higher hardness, 20% higher strength, 5% lighter weight, and nearly three times higher light transmittance. This set of data fully demonstrates the significant advantages of this invention's technical solution in four key dimensions: "low-temperature energy saving," "high strength," "lightweight," and "high light transmittance."

[0130] Technical Attribution of the Synergistic Effect of Talc and Calcite

[0131] This invention establishes an essential synergistic effect between talc and calcite. Comparative Example 1's formulation, based on a high proportion of talc (46%), eliminated calcite (0%). Results: Hardness plummeted from 6.3 GPa to 4.2 GPa, strength decreased from 115 MPa to 72 MPa, and light transmittance dropped sharply from 11.5% to 2.5%, while density increased to 2.61 g / cm³. The reasons are as follows: Due to the lack of calcium oxide provided by calcite, a sufficient and effective CaO-MgO-SiO2 ternary liquid phase could not be formed at a low temperature of 1230℃. This resulted in two problems: firstly, the development of the protoencite crystals was hindered, preventing the formation of a strong framework, leading to a sharp drop in hardness and strength; secondly, α-cristobalite, crucial for light transmittance, did not form, instead generating tridymite with a refractive index mismatch with the glass phase. This demonstrates that in the formulation system of this invention, calcite is the key catalyst and structure regulator for initiating and maintaining the entire high-performance crystal phase system.

[0132] Technical Attribution for Limiting Alumina Content

[0133] Comparative Example 2 simulated a scenario where, without changing the firing temperature, the alumina content exceeded the standard (15.8%) simply by increasing the amount of plastic washing mud. As a result, the transmittance plummeted to 1.8%, becoming almost completely opaque. Qualitative analysis of the main crystalline phase revealed that excessive aluminum ions preempted calcium, silicon, and other components in the system, generating a large amount of mullite impurities. The refractive index of mullite itself was severely mismatched with the surrounding glassy phase, causing strong light scattering and damaging the transmittance. Simultaneously, the formation of mullite diluted the magnesium source that should have formed protoencite, resulting in significantly lower strength (95 MPa) and hardness (5.5 GPa) compared to Example 1. This fully demonstrates that controlling the alumina content below 8% provides a foundation for the talc-calcite synergistic system and is a necessary constraint to avoid side reactions and ensure the formation of the target crystalline phase by the dominant reaction.

[0134] Technical attribution of firing conditions

[0135] The low-temperature firing conditions of this invention are also an indispensable factor. Comparative Example 4 used an advanced formula that was exactly the same as that of High-Performance Example 1, but its performance completely collapsed simply because the firing temperature was mistakenly reduced to 1120°C (below the lower limit of 1160°C). Its hardness (3.8 GPa) and strength (55 MPa) were even lower than those of ordinary daily-use porcelain. The qualitative analysis of the main crystal phase showed that low-hardness enstatite and a large amount of residual quartz were generated. This indicates that the formula of this invention needs to be within a specific thermodynamic window of 1160 to 1260°C to activate and complete the complete chain reaction from phase transformation to crystal phase regulation to liquid phase densification, thereby transforming the formula advantages into product advantages.

[0136] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high-strength, lightweight daily-use ceramic, characterized in that, The composition and weight percentage of the raw materials for the billet are as follows: Talc 35%–60%; Calcite 5%–15%; Feldspar 5%–18%; Quartz 8%–25%; Bentonite 3%–8%; Washing mud 5%–15%; The total alumina content in the raw material composition does not exceed 8%; The main crystalline phases of the high-strength lightweight daily-use ceramics are protoenzyme and α-cristobalite. The protoenzyme is generated by the reaction of talc, calcite and quartz at high temperature, and the α-cristobalite is formed by the crystal transformation of quartz at high temperature.

2. The high-strength, lightweight daily-use ceramic according to claim 1, characterized in that, The talc is calcined talc or raw talc, with a magnesium oxide content ≥28%, a silicon oxide content ≥55%, and a loss on ignition ≤8%; the weight percentage of the talc is 42% to 55%.

3. The high-strength, lightweight daily-use ceramic according to claim 1, characterized in that, The calcite has a calcium oxide content of ≥52% and a weight percentage of 8% to 12%; the feldspar is potassium feldspar, sodium feldspar, or a mixture of both, and its total potassium oxide and sodium oxide content is ≥8% and a weight percentage of 10% to 15%.

4. The high-strength, lightweight daily-use ceramic according to claim 1, characterized in that, The quartz is vein quartz or quartz sand, with a silica content ≥98% and a weight percentage of 15% to 22%; the bentonite is calcium-based bentonite or sodium-based bentonite, with a montmorillonite content ≥60% and a weight percentage of 4% to 6%.

5. The high-strength, lightweight daily-use ceramic according to claim 1, characterized in that, The washed mud is kaolin clay with an alumina content of 25% to 35%, a plasticity index of ≥15, and a weight percentage of 8% to 12%.

6. The high-strength, lightweight daily-use ceramic according to claim 1, characterized in that, The weight ratio of talc to calcite is in the range of (4-8):

1. By controlling this ratio, magnesium oxide and calcium oxide in the formula react at high temperature to form calcium magnesium silicate eutectic, which promotes the full development of the original enstatite crystal phase and forms an interwoven structure with the α-cristobalite crystal phase transformed from quartz crystal form.

7. A method for preparing high-strength, lightweight daily-use ceramics as described in any one of claims 1 to 6, characterized in that, Includes the following steps: (1) Weigh each raw material according to the proportion, mix talc, calcite, feldspar and quartz and then perform wet ball milling to obtain a hard slurry; (2) Disperse bentonite and washed mud in water to make a soft slurry, then mix it with the hard slurry obtained in step (1), and perform a second ball milling to obtain a mixed slurry; (3) Pass the mixed slurry through a 200-300 mesh sieve to remove iron, then press and filter to dewater to obtain mud cake; (4) The clay cake is kneaded and aged, and then rolled or pressed to obtain the blank; (5) Dry the green body at 60-100℃ until the moisture content is less than 2%; (6) The dried green body is fired once in an oxidizing atmosphere at 1160-1260℃ for 20-60 minutes to obtain the high-strength lightweight daily ceramic.

8. The method for preparing high-strength, lightweight daily-use ceramics according to claim 7, characterized in that, In step (1), during wet ball milling, the weight ratio of material:ball:water is 1:(1.5~2.5):(0.6~1.0), the ball milling time is 2~6 hours, and the particle size of the hard slurry after ball milling reaches ≤2.5% on a 10,000-mesh sieve.

9. The method for preparing high-strength, lightweight daily-use ceramics according to claim 7, characterized in that, In step (2), the secondary ball milling time is 1 to 3 hours, and the particle size of the resulting slurry reaches ≤1.0% on a 10,000-mesh sieve; in step (4), the aging time is 48 to 96 hours.

10. The method for preparing high-strength, lightweight daily-use ceramics according to claim 7, characterized in that, The firing conditions in step (6) are: room temperature to 900℃, heating rate of 5 to 8℃ / min; 900℃ to the maximum firing temperature, heating rate of 2 to 4℃ / min; maximum firing temperature of 1190 to 1230℃, holding time of 30 to 45 minutes.