A high-thermal shock resistance, low-expansion heat-resistant ceramic glaze and a preparation method thereof

Abstract

The application relates to the technical field of ceramic materials, and discloses a high-thermal-shock-resistance and low-expansion heat-resistant ceramic glaze and a preparation method thereof. The glaze comprises 70.0-80.0 parts of base powder, 20.0-30.0 parts of beta-spodumene clinker, 50.0-60.0 parts of additional water, 0.2-0.4 parts of sodium polyacrylate, 0.1-0.3 parts of sodium carboxymethyl cellulose and 0.05-0.15 parts of calcium acetate; the base powder contains inorganic raw materials such as colemanite. In the system, the calcium ions ionized from calcium acetate and the molecular chains of sodium carboxymethyl cellulose are crosslinked to form a three-dimensional yield network structure. During preparation, the base powder and the beta-spodumene clinker are sequentially put into a ball mill for grinding, and a crosslinking agent is added before shutdown. The three-dimensional yield network structure is used for stably suspending the beta-spodumene clinker with a large particle size, and the ceramic product can buffer thermal stress concentration by means of the low-expansion crystal residual nucleus reserved in the interior when the temperature changes greatly, so that the glaze surface can be effectively prevented from cracking.

Description

Technical Field

[0001] This invention relates to the field of ceramic materials technology, specifically to a heat-resistant ceramic glaze with high thermal shock resistance and low expansion, and its preparation method. Background Technology

[0002] Heat-resistant ceramics often need to withstand rapid temperature changes during use. When the difference in thermal expansion coefficients between the glaze and the ceramic body is significant, the glaze may develop network cracks or peel off due to localized thermal stress concentration. To reduce the overall thermal expansion coefficient of the glaze layer, a common practice is to introduce inorganic mineral particles with low thermal expansion coefficients into the glaze formulation.

[0003] To ensure that these low-expansion inorganic materials can still provide physical buffering after ceramic firing, their relatively large particle size is typically required. However, in the actual slurry preparation and glazing processes, coarse-grained inorganic minerals are difficult to maintain suspension in conventional homogeneous aqueous glaze slurry systems and are highly susceptible to physical sedimentation due to gravity. This sedimentation and aggregation of coarse particles directly leads to uneven internal structure of the glaze layer, resulting in pinhole defects on the glaze surface after high-temperature firing. It also reduces the opacity of the glaze layer in the high-temperature molten state, making it difficult to meet the production and application requirements of high-quality heat-resistant ceramics.

[0004] Therefore, this invention proposes a heat-resistant ceramic glaze with high thermal shock resistance and low expansion, and its preparation method, to overcome the shortcomings of the prior art. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a heat-resistant ceramic glaze with high thermal shock resistance and low expansion, and its preparation method. This solves the problem that in existing heat-resistant ceramic glazes, low-expansion coarse particles are difficult to suspend stably and are prone to settling, resulting in uneven glaze layer structure and easy cracking of the glaze surface when the product undergoes drastic temperature changes.

[0006] To address the above problems, the present invention provides the following technical solution: In a first aspect, the present invention provides a heat-resistant ceramic glaze with high thermal shock resistance and low expansion, employing the following technical solution: A heat-resistant ceramic glaze with high thermal shock resistance and low expansion, wherein the heat-resistant ceramic glaze contains a three-dimensional yielding network structure formed by the cross-linking of sodium carboxymethyl cellulose molecular chains and calcium ions from the ionization of calcium acetate, so as to stably suspend the coarse particulate components inside the heat-resistant ceramic glaze. The heat-resistant ceramic glaze comprises the following raw materials in parts by weight: The base powder comprises 70.0–80.0 parts, including 18.0–22.0 parts of hard borate, 11.0–14.0 parts of calcined talc, 9.0–12.0 parts of kaolin, 20.0–25.0 parts of quartz, 3.0–5.0 parts of rutile titanium dioxide, 2.0–4.0 parts of calcium phosphate, and 2.0–4.0 parts of zirconium silicate. 20.0–30.0 parts of β-spodumene clinker; Add 50.0 to 60.0 parts of water; Sodium polyacrylate 0.2–0.4 parts; Sodium carboxymethyl cellulose, 0.1–0.3 parts; 0.05 to 0.15 parts of calcium acetate.

[0007] By employing the above-mentioned technical solutions, it is generally difficult to simultaneously achieve coarse particle suspension and glaze flowability using a single rheology modifier. Therefore, this invention utilizes sodium polyacrylate, sodium carboxymethyl cellulose, and calcium acetate to construct a rheology control system, combined with β-spodumene clinker as a low-expansion phase, thus resolving the technical contradiction between coarse particle suspension and high-temperature crack resistance. The specific rheological modification and mechanism of action are as follows: In the presence of added water, sodium polyacrylate ionizes and adsorbs onto the surface of the fine particles of the base powder, providing negative charge repulsion and steric hindrance, resulting in the uniform dissolution and dispersion of kaolin, quartz, zirconium silicate, and calcium borate, forming a low-viscosity base slurry fluid. Subsequently added sodium carboxymethyl cellulose undergoes dissociation of its sodium carboxylate groups in water, and the molecular chains extend and interweave between the fine particles of the base powder under electrostatic repulsion.

[0008] Based on this, calcium acetate undergoes complete ionization upon dissolving in water, as shown in the following reaction equation: Ca(CH3COO)2→Ca 2+ +2CH3COO - ; The divalent calcium ions released from ionization will undergo an ion coordination reaction with the free carboxyl groups on the extended sodium carboxymethyl cellulose chain, as shown in the following reaction equation: 2R-COO - +Ca 2+ →(R-COO)2Ca; where R represents the polymer backbone of sodium carboxymethyl cellulose; In this reaction, free divalent calcium ions act as cross-linking nodes, physically bridging multiple independent sodium carboxymethyl cellulose molecular chains, thus forming a three-dimensional yield network structure in situ within the aqueous phase of the glaze. This three-dimensional yield network structure imparts an initial yield stress to the glaze. As long as the shear force caused by gravity is below this yield value, large-diameter β-spodumene clinker particles can remain stably suspended within the slurry. During the firing stage of the product, only the superficial layer of the large-diameter β-spodumene clinker dissolves in the glass phase, while the interior retains its original crystal structure, forming residual nuclei. Once the ceramic product is subjected to a drastic change in ambient temperature, the β-spodumene residual nuclei, with their low coefficient of thermal expansion, offset the volume deformation of the surrounding glass matrix. The superficial dissolution zone also forms a compositional gradient at the crystal-glass phase interface, thereby buffering the interfacial thermal stress and ultimately improving the overall thermal shock resistance of the glaze layer.

[0009] Preferably, the heat-resistant ceramic glaze with high thermal shock resistance and low expansion comprises the following raw materials in parts by weight: The base powder comprises 75.0 parts, including 20.0 parts of borosilicate, 12.0 parts of calcined talc, 10.0 parts of kaolin, 23.0 parts of quartz, 4.0 parts of rutile titanium dioxide, 3.0 parts of calcium phosphate, and 3.0 parts of zirconium silicate; 25.0 parts of β-spodumene clinker; 55.0 parts of added water; 0.3 parts of sodium polyacrylate; 0.2 parts of sodium carboxymethyl cellulose; and 0.1 parts of calcium acetate.

[0010] By adopting the above technical solution, when the ratio is adjusted to this, the solid-liquid ratio and the concentration of crosslinking agent in the system are exactly in equilibrium. The resulting three-dimensional yield network structure can provide suitable yield stress without making the glaze slurry viscosity too high, thus taking into account both the fluidity of the glaze slurry in the glazing pipeline and the anti-settling stability during the storage period.

[0011] Preferably, the characteristic parameters of the raw material satisfy the following conditions: The borate calcium carbide contains B2O3 with a mass fraction ≥ 40.0% and CaO with a mass fraction ≥ 25.0%; the calcined talc contains MgO with a mass fraction ≥ 30.0%; the sodium polyacrylate has a weight-average molecular weight (Mw) of 2000–5000 and a solid content ≥ 40.0%; the sodium carboxymethyl cellulose has a degree of substitution (DS) of 0.7–0.9; and the 2% aqueous solution of sodium carboxymethyl cellulose has a dynamic viscosity ≥ 800 mPa·s at 25°C.

[0012] By adopting the above technical solutions, the parameters of these inorganic minerals and polymer materials are clearly defined. This is mainly because the chemical composition of hard borate and calcined talc can provide sufficient alkaline earth metal oxides and boron-oxygen network formations during high-temperature firing, which is beneficial to reducing the high-temperature viscosity of the glaze. Controlling the weight-average molecular weight of sodium polyacrylate in the range of 2000 to 5000 can avoid flocculation caused by high molecular weight polymers and ensure the dispersion efficiency of fine particle groups. In addition, the degree of substitution of sodium carboxymethyl cellulose is 0.7 to 0.9, which can effectively control the carboxyl group density on the molecular chain, so that the number of cross-linking reaction sites of calcium ions is moderate, avoiding insufficient network strength due to too few cross-linking sites or overall gelation of the slurry due to too many cross-linking sites.

[0013] The heat-resistant ceramic glaze with high thermal shock resistance and low expansion is in the form of a glaze slurry and meets the following particle size and rheological parameter requirements: The particle size D50 of the solid particles in the base powder of the high thermal shock resistant and low expansion heat-resistant ceramic glaze is 2.0-3.0 μm; the particle size D50 of the solid particles in the β-spodumene clinker of the high thermal shock resistant and low expansion heat-resistant ceramic glaze is 10.0-12.0 μm; the initial yield stress of the high thermal shock resistant and low expansion heat-resistant ceramic glaze measured at 25℃ is 28.3-34.1 Pa.

[0014] By adopting the above technical solution, this setup establishes a bimodal particle size distribution system of fine particles in the base powder and coarse particles in the β-spodumene clinker. The fine particle size of the base powder ensures rapid melting and vitrification during the firing process, forming a continuous and uniform glass matrix; while the coarse particle size of the β-spodumene clinker, ranging from 10.0 to 12.0 μm, limits its complete dissolution during firing and retains low-expansion crystal nuclei; at the same time, maintaining the initial yield stress within the range of 28.3 to 34.1 Pa provides just the right amount of support matching the weight of the β-spodumene clinker particles, achieving physical suspension of the coarse particles.

[0015] Preferably, the β-spodumene clinker is prepared by the following pretreatment method: α-spodumene ore with LiAlSi2O6 as the main component and Li2O mass fraction ≥ 6.5% is initially crushed to a particle size ≤ 5 mm; it is placed in a sagger and calcined in a calcining kiln at a constant temperature of 1030–1080℃ for 2.0–4.0 h; after calcination, it is cooled to below 200℃ with the kiln and then dry-pulverized to a particle size ≤ 200 μm to obtain the β-spodumene clinker.

[0016] By adopting the above technical solution, high-temperature calcination is used to induce an irreversible phase transformation of α-spodumene into the β-spodumene phase with an extremely low coefficient of thermal expansion. This eliminates the phase transformation volume expansion effect of the mineral during the subsequent glaze firing process. Controlling the constant temperature and time of calcination can ensure the conversion rate of the phase transformation process and provide a low-expansion physical framework for the glaze as a whole.

[0017] Secondly, the present invention provides a method for preparing a heat-resistant ceramic glaze with high thermal shock resistance and low expansion, employing the following technical solution: A method for preparing a heat-resistant ceramic glaze with high thermal shock resistance and low expansion includes the following steps: S1. The base powder, added water and sodium polyacrylate are put into a wet ball mill for the first stage of ball milling to obtain the basic slurry that is decoagulated and dispersed. S2. Add β-spodumene clinker to the base slurry obtained in S1 and continue mixing and grinding. S3. Dissolve sodium carboxymethyl cellulose and calcium acetate separately in water beforehand to obtain sodium carboxymethyl cellulose solution and calcium acetate solution. Then add them to a wet ball mill in sequence, continue to run and mix, and then stop the mill to discharge the slurry to obtain a heat-resistant ceramic glaze with high thermal shock resistance and low expansion.

[0018] By employing the aforementioned technical solutions, it is generally difficult to simultaneously ball-mill all raw materials to meet the particle size requirements of different components. Therefore, the process design in this application decouples the feeding sequence from the grinding process. In stage S1, only the basic powder is ball-milled for an extended period. The decoupling effect of sodium polyacrylate pulverizes the relevant inorganic raw materials to the micron level, exposing fresh surfaces and forming a low-viscosity homogeneous fluid in the aqueous phase. With this buffering effect of the basic dispersion medium, when β-spodumene clinker is added in stage S2 for further mixing, the grinding medium primarily serves to surface-peel and uniformly mix the β-spodumene clinker. This directly prevents the β-spodumene clinker from being over-pulverized, thus retaining the large particle cores required to maintain low expansion characteristics in the final glaze slurry. The final addition of the pre-dissolved sodium carboxymethyl cellulose solution and calcium acetate solution in stage S3 is to prevent the prolonged high-intensity mechanical shear force from breaking the polymer molecular chains if added earlier. The crosslinking reaction is carried out before the machine is stopped. The crosslinking agent reacts rapidly through short-time mixing, which can form and maintain the three-dimensional yield network structure of the glaze slurry under low shear conditions, thus effectively preventing the sedimentation of coarse particles after slurry discharge.

[0019] Preferably, the grinding process parameters for steps S1 and S2 are controlled as follows: In S1, the first stage of ball milling continues until the particle size of the solid particles in the base slurry reaches D50 of 2.0–3.0 μm; In S2, β-spodumene clinker is fed into the wet ball mill 40–60 minutes before the wet ball mill is shut down and discharged. Samples are taken and tested before the clinker is discharged to control the particle size D50 of the β-spodumene clinker solid particles in the slurry after mixing and grinding to be 10.0–12.0 μm.

[0020] By adopting the above technical solution, the grinding endpoints of different components are clearly defined. This is mainly because controlling the particle size of the base powder to 2.0 to 3.0 micrometers can increase the specific surface area, improve the reactivity in the early stages of firing, and promote low-temperature melting and vitrification. The mixing and grinding time of β-spodumene clinker is limited to 40 to 60 minutes to strictly control the particle size within the range of 10.0 to 12.0 micrometers. This bimodal particle size distribution provides sufficient liquid phase filling of pores while leaving β-spodumene framework support, thus avoiding thermal stress cracking during the cooling process.

[0021] Preferably, the feeding sequence in step S3 is controlled as follows: In step S3, a pre-dissolved sodium carboxymethyl cellulose solution is added to the wet ball mill. The sodium carboxymethyl cellulose solution is added within 1 to 2 minutes, and the mill continues to run and disperse for 1 to 2 minutes. Then, a pre-dissolved calcium acetate solution is added at a uniform rate within 3 to 5 minutes. After the calcium acetate solution is added, the mill continues to run until a total of 10 to 15 minutes have elapsed since the addition of the sodium carboxymethyl cellulose solution, at which point the mill is stopped and the slurry is discharged.

[0022] By employing the above technical solution, the molecular chains of sodium carboxymethyl cellulose are first added in a pre-dissolved solution to allow them to fully extend and evenly distribute among the inorganic particles in the glaze slurry. Subsequently, a pre-dissolved calcium acetate solution is introduced to provide cross-linking nodes, effectively preventing the polymer from agglomerating due to excessively high local concentrations. Furthermore, the cumulative running time of 10-15 minutes from the initial addition of the sodium carboxymethyl cellulose solution precisely meets the kinetic requirements for calcium ion diffusion throughout the system and completion of the coordination reaction, ensuring the integrity of the cross-linked network while avoiding network degradation caused by excessive grinding.

[0023] Preferably, the dynamic viscosity of the base slurry obtained in step S1 is controlled at 184 to 213 mPa·s; after adding the pre-dissolved calcium acetate solution in step S3 and stopping the machine to discharge the slurry, the dynamic viscosity of the heat-resistant ceramic glaze with high thermal shock resistance and low expansion reaches 1256 to 1482 mPa·s.

[0024] By adopting the above technical solution, viscosity is used as the criterion for judging the process state. Maintaining a low viscosity state in the S1 stage is conducive to the efficient impact of the media balls on the material in the ball mill, thereby reducing grinding energy consumption. The dynamic viscosity jump that occurs after adding the pre-dissolved calcium acetate solution directly reflects the successful construction of the three-dimensional yield network structure in the system. The high viscosity state at this time endows the glaze slurry with thixotropy, making it fluid under shear force and able to quickly recover viscosity during static storage to block the sedimentation path of coarse particles.

[0025] Preferably, after shutdown and slurry discharge, the following glazing and firing application steps are included: The high thermal shock resistance and low expansion heat-resistant ceramic glaze obtained from shutdown and slurry discharge is passed through a 100-120 mesh sieve and applied to the surface of the ceramic green body, controlling the dry base glaze layer thickness to be 0.6-1.0 mm; the ceramic green body with the applied high thermal shock resistance and low expansion heat-resistant ceramic glaze is sent to a drying kiln for drying at 100-120°C; it is then sent to a continuous roller kiln for firing, with the firing temperature controlled at 1165-1195°C and held at a constant temperature for 15-25 minutes; after the constant temperature holding period, the blower system is turned on to cool to 900-950°C at a rate of 15-20°C / min, and then cooled to room temperature before being removed from the kiln.

[0026] By adopting the above technical solution, in the end-application stage, using a 100-120 mesh sieve can intercept impurities while allowing micron-sized coarse particles to pass through smoothly, ensuring a smooth glaze surface. Controlling the firing temperature between 1165 and 1195℃ not only allows the base powder to completely melt into a glassy matrix but also prevents excessive dissolution of β-spodumene. After holding at this temperature, cooling to 900-950℃ at a rate of 15-20℃ / min using a blower system inhibits glaze crystallization, while the subsequent slow cooling stage releases residual thermal stress. This temperature control method combining rapid and slow cooling, along with the effect of low-expansion crystal nuclei, jointly suppresses the initiation of network cracks, ultimately resulting in a dense and thermally shock-resistant ceramic product.

[0027] This invention provides a heat-resistant ceramic glaze with high thermal shock resistance and low expansion, and its preparation method. It has the following beneficial effects: 1. This invention introduces sodium carboxymethyl cellulose and calcium acetate into the glaze formulation, utilizing their ion coordination reaction in the aqueous phase to generate a three-dimensional yield network structure in situ. This structure imparts appropriate initial yield stress to the glaze slurry, providing physical support during static storage, ensuring stable suspension of large-diameter β-spodumene coarse particles without sedimentation; while exhibiting normal flowability under shear force in the glazing pipeline. This solves the problem of easy sedimentation and aggregation of low-expansion coarse particles in traditional homogeneous glaze slurries, ensuring the structural uniformity of the glaze layer on the green body surface.

[0028] 2. This invention utilizes a bimodal particle size distribution system to improve the high-temperature crack resistance of ceramic products. The base powder in the formula is controlled to a small particle size to ensure rapid melting during firing to form a continuous glassy matrix, while the β-spodumene clinker is retained at a coarse particle size of 10.0 to 12.0 micrometers. During firing, the large-particle β-spodumene only undergoes superficial dissolution, maintaining its original crystal structure internally. When the finished product encounters drastic changes in ambient temperature during use, these low-thermal-expansion crystal remnants can effectively offset the volume deformation of the surrounding glassy matrix, reduce the concentration of thermal stress at the interface, and thus inhibit glaze cracking or peeling.

[0029] 3. The preparation method of this invention employs a segmented and decoupled grinding and feeding sequence. The process involves first independently ball milling and decoupling the basic inorganic raw materials, then adding β-spodumene for 40-60 minutes of mixed grinding, and finally adding pre-dissolved sodium carboxymethyl cellulose solution and calcium acetate solution in a sequential manner. The process is stopped and the slurry is discharged after a cumulative 10-15 minutes from the initial addition of the sodium carboxymethyl cellulose solution. This segmented control avoids excessive crushing of the low-expansion phase minerals, preventing them from losing their skeletal support, and also prevents prolonged high-intensity mechanical shear forces from severing the polymer molecular chains, ensuring the complete formation of the three-dimensional yield network structure. Through this process, the produced glaze can stably maintain the preset rheological parameters and solid particle size. Attached Figure Description

[0030] Figure 1 The figures show a comparison of the dynamic viscosity and initial yield stress of the glaze slurry at different preparation stages in the embodiments and comparative examples of the present invention. (a) is a dynamic viscosity change diagram at the end of step (2) and at the discharge of slurry in step (4), and (b) is an initial yield stress distribution diagram at the discharge of slurry in step (4). Figure 2 The graph shows the variation of the average linear thermal expansion coefficient of the glaze blocks of each group in the present invention in different temperature ranges. Figure 3 The following are comparison diagrams of the anti-settling properties and drying defects of the glaze slurry in the embodiments and comparative examples of the present invention. Among them, (a) is the distribution diagram of the 24-hour static settling rate, and (b) is the distribution diagram of the mud cracking rate during the drying of the green body. Figure 4 This is a comparison chart of the overall appearance quality of the glaze after firing for each group of the present invention, wherein (a) is the average appearance quality per 100cm. 2 (a) is a distribution map of the number of pinholes, (b) is a distribution map of the gloss of a 60-degree specular surface, and (c) is a distribution map of the opacity. Figure 5 The following are distribution diagrams of the critical temperature difference for thermal shock resistance and wear mass loss of each group of samples in this invention. Among them, (a) is a line graph of the highest critical temperature difference for thermal shock resistance obtained by testing, and (b) is a scatter plot of mass loss of the sample after 500 revolutions of grinding. Detailed Implementation

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] The main raw materials and reagents used in the following examples and comparative examples have the following sources and specifications. Reagents not specifically mentioned are all commercially available analytical grade or higher grade products.

[0033] The β-spodumene clinker of different weights required in the embodiments were prepared by scaling up the process according to the method described in the corresponding preparation example, or by repeating the preparation of multiple batches and then merging them together.

[0034] Hard borate is a natural mineral raw material. Its main chemical formula is 2CaO·3B2O3·5H2O, in which the mass fraction of B2O3 is greater than or equal to 40.0% and the mass fraction of CaO is greater than or equal to 25.0%.

[0035] Calcined talc is a magnesium silicate mineral obtained by calcining natural talc. Its main chemical formula is 3MgO·4SiO2·H2O, in which the mass fraction of MgO is greater than or equal to 30.0%.

[0036] α-Spodumene ore is a natural monoclinic mineral with the main chemical formula LiAlSi2O6, in which the mass fraction of Li2O is greater than or equal to 6.5%.

[0037] Sodium polyacrylate, CAS number 9003-04-7, structural formula [-CH2-CH(COONa)-] n It is a monomer homopolymer of sodium acrylate with a weight-average molecular weight (Mw) of 2000 to 5000 and a solid content of ≥40.0%.

[0038] Sodium carboxymethyl cellulose, CAS number 9004-32-4, structural formula [C6H7O2(OH)2OCH2COONa] n The degree of substitution (DS) is 0.7 to 0.9, and the dynamic viscosity of a 2% aqueous solution at 25°C is greater than or equal to 800 mPa·s.

[0039] Preparation Example 1: This preparation example provides a method for preparing β-spodumene clinker, including the following steps: Weigh 10.0 kg of α-spodumene ore and crush it to a particle size of less than or equal to 5 mm. Place the crushed ore into a refractory sagger and place it in a calcining kiln. Calcinate it at a constant temperature of 1030℃ for 2.0 h. After calcination, cool it to below 200℃ in the kiln and remove it. Cool it in the air to 25℃ and then dry grind it to a particle size of less than or equal to 200 μm to obtain β-spodumene clinker.

[0040] Preparation Example 2: This preparation example provides a method for preparing β-spodumene clinker, including the following steps: Weigh 10.0 kg of α-spodumene ore and crush it to a particle size of less than or equal to 5 mm. Place the crushed ore into a refractory sagger and place it in a calcining kiln. Calcinate it at a constant temperature of 1050℃ for 3.0 h. After calcination, cool it to below 200℃ in the kiln and remove it. Cool it in the air to 25℃ and then dry grind it to a particle size of less than or equal to 200 μm to obtain β-spodumene clinker.

[0041] Preparation Example 3: This preparation example provides a method for preparing β-spodumene clinker, including the following steps: Weigh 10.0 kg of α-spodumene ore and crush it to a particle size of less than or equal to 5 mm. Place the crushed ore into a refractory sagger and place it in a calcining kiln. Calcinate it at a constant temperature of 1080℃ for 4.0 h. After calcination, cool it to below 200℃ in the kiln and remove it. Cool it in the air to 25℃ and then dry grind it to a particle size of less than or equal to 200 μm to obtain β-spodumene clinker.

[0042] In Examples 1-5 below, the particle size control of β-spodumene clinker solid particles involved in step (3) is performed as follows: After the β-spodumene clinker is added, a sample is taken and tested before entering step (4) to confirm that the D50 of the β-spodumene clinker solid particles in the slurry after mixing and grinding reaches the value recorded in the corresponding example. The 40min, 50min, and 60min listed in Examples 1-5 are the actual in-machine mixing times that can achieve the target D50 under the feeding amount and wet ball milling conditions of the corresponding examples, as confirmed by sampling.

[0043] In step (4), the sodium carboxymethyl cellulose solution and the calcium acetate solution were prepared separately by dissolving them in water before being added to the ball mill. This pre-dissolution process is a pretreatment process for the additives and is not included in the cumulative running time of the ball mill in step (4). The cumulative running time in step (4) is calculated from the time the sodium carboxymethyl cellulose solution is added to the ball mill until the time the mill is stopped and the slurry is discharged.

[0044] Example 1: This example provides a heat-resistant ceramic glaze with high thermal shock resistance and low expansion. Its preparation and application verification process includes the following steps: (1) Weigh out the dry base raw materials, the base powder totals 70.0 kg, including 19.0 kg of borosilicate, 11.0 kg of calcined talc, 9.0 kg of kaolin, 23.0 kg of quartz, 3.0 kg of rutile titanium dioxide, 2.0 kg of calcium phosphate, 3.0 kg of zirconium silicate; add 50.0 kg of water and 0.2 kg of sodium polyacrylate.

[0045] (2) The above-mentioned basic powder, added water and sodium polyacrylate are put into a wet ball mill for the first stage of ball milling until the particle size of the solid particles in the slurry reaches D50 of 3.0μm.

[0046] (3) 40 minutes before the ball mill is shut down, 30.0 kg of β-spodumene clinker obtained in Preparation Example 1 is added to the ball mill and mixed milling is continued. Before the ball mill is discharged, a sample is taken for testing to control the particle size D50 of the β-spodumene clinker solid particles in the slurry after mixed milling to be 12.0 μm.

[0047] (4) Dissolve 0.1 kg of sodium carboxymethyl cellulose and 0.05 kg of calcium acetate separately in water beforehand to obtain sodium carboxymethyl cellulose solution and calcium acetate solution for later use. First, add sodium carboxymethyl cellulose solution to the ball mill. Add the sodium carboxymethyl cellulose solution within 1 to 2 minutes and continue to run and disperse for 1 to 2 minutes. Then, add calcium acetate solution at a uniform rate within 3 to 5 minutes. After the calcium acetate solution is added, continue to run until the cumulative running time from the beginning of adding sodium carboxymethyl cellulose solution is 10 minutes. Then stop the machine and discharge the slurry to obtain the required high thermal shock resistant, low expansion heat resistant ceramic glaze (in glaze slurry state).

[0048] (5) Pass the glaze obtained above through a 100-mesh sieve and apply it evenly to the surface of the ceramic green body using a glazing device, controlling the dry base glaze layer thickness to be 0.6 mm.

[0049] (6) The glazed body is sent into a drying kiln and dried at 100°C to remove moisture. Then it is sent into a continuous roller kiln for firing. The firing temperature is controlled at 1165°C and the constant temperature holding time is 15 min. After the holding time is completed, the blower system is turned on to cool the kiln temperature to 900°C at a rate of 15-20°C / min. Finally, it is slowly cooled to room temperature and removed from the kiln to obtain a ceramic product with the glaze layer on the surface, which is used for subsequent performance testing.

[0050] Example 2: This example provides a heat-resistant ceramic glaze with high thermal shock resistance and low expansion. Its preparation and application verification process includes the following steps: (1) Weigh out the dry base raw materials, the base powder totals 80.0 kg, including 22.0 kg of borosilicate, 14.0 kg of calcined talc, 12.0 kg of kaolin, 20.0 kg of quartz, 5.0 kg of rutile titanium dioxide, 3.0 kg of calcium phosphate, 4.0 kg of zirconium silicate; add 60.0 kg of water and 0.4 kg of sodium polyacrylate.

[0051] (2) The above-mentioned basic powder, added water and sodium polyacrylate are put into a wet ball mill for the first stage of ball milling until the particle size of the solid particles in the slurry reaches D50 of 2.0μm.

[0052] (3) 60 minutes before the ball mill is shut down, 20.0 kg of β-spodumene clinker obtained in Preparation Example 3 is added to the ball mill and mixed milling is continued. Before the ball mill is discharged, a sample is taken for testing to control the particle size D50 of the β-spodumene clinker solid particles in the slurry after mixed milling to be 10.0 μm.

[0053] (4) Dissolve 0.3 kg of sodium carboxymethyl cellulose and 0.15 kg of calcium acetate separately in water beforehand to obtain sodium carboxymethyl cellulose solution and calcium acetate solution for later use. First, add sodium carboxymethyl cellulose solution to the ball mill. Add the sodium carboxymethyl cellulose solution within 1 to 2 minutes and continue to run and disperse for 1 to 2 minutes. Then, add calcium acetate solution at a uniform rate within 3 to 5 minutes. After the calcium acetate solution is added, continue to run until a total of 15 minutes have been run since the sodium carboxymethyl cellulose solution was first added. Then stop the machine and discharge the slurry to obtain the required high thermal shock resistant, low expansion heat resistant ceramic glaze (in glaze slurry state).

[0054] (5) Pass the glaze obtained above through a 120-mesh sieve and apply it evenly to the surface of the ceramic green body using a glazing device, controlling the dry base glaze layer thickness to be 1.0 mm.

[0055] (6) The glazed body is sent into a drying kiln and dried at 120°C to remove moisture. Then it is sent into a continuous roller kiln for firing. The firing temperature is controlled at 1195°C and the constant temperature holding time is 25 min. After the holding time is completed, the blower system is turned on to cool the kiln temperature to 950°C at a rate of 15-20°C / min. Finally, it is slowly cooled to room temperature and removed from the kiln to obtain a ceramic product with the glaze layer on the surface, which is used for subsequent performance testing.

[0056] Example 3: This example provides a heat-resistant ceramic glaze with high thermal shock resistance and low expansion. Its preparation and application verification process includes the following steps: (1) Weigh out the dry base raw materials, the base powder totals 75.0 kg, including 20.0 kg of borosilicate, 12.0 kg of calcined talc, 10.0 kg of kaolin, 23.0 kg of quartz, 4.0 kg of rutile titanium dioxide, 3.0 kg of calcium phosphate, 3.0 kg of zirconium silicate; add 55.0 kg of water and 0.3 kg of sodium polyacrylate.

[0057] (2) The above-mentioned basic powder, added water and sodium polyacrylate are put into a wet ball mill for the first stage of ball milling until the particle size of the solid particles in the slurry reaches D50 of 2.5μm.

[0058] (3) 50 minutes before the ball mill is shut down, 25.0 kg of β-spodumene clinker obtained in Preparation Example 2 is added to the ball mill and mixed milling is continued. Before the ball mill is discharged, a sample is taken for testing to control the particle size D50 of the β-spodumene clinker solid particles in the slurry after mixed milling to be 11.0 μm.

[0059] (4) Dissolve 0.2 kg of sodium carboxymethyl cellulose and 0.1 kg of calcium acetate separately in water beforehand to obtain sodium carboxymethyl cellulose solution and calcium acetate solution for later use. First, add sodium carboxymethyl cellulose solution to the ball mill. Add the sodium carboxymethyl cellulose solution within 1 to 2 minutes and continue to run and disperse for 1 to 2 minutes. Then, add calcium acetate solution at a uniform rate within 3 to 5 minutes. After the calcium acetate solution is added, continue to run until a total of 12 minutes have been run since the sodium carboxymethyl cellulose solution was first added. Then stop the machine and discharge the slurry to obtain the desired high thermal shock resistant, low expansion heat-resistant ceramic glaze (in glaze slurry state).

[0060] (5) Pass the glaze obtained above through a 120-mesh sieve and apply it evenly to the surface of the ceramic green body using a glazing device, controlling the dry base glaze layer thickness to be 0.8 mm.

[0061] (6) The glazed body is sent into a drying kiln and dried at 110°C to remove moisture. Then it is sent into a continuous roller kiln for firing. The firing temperature is controlled at 1180°C and the constant temperature holding time is 20 min. After the holding time is completed, the blower system is turned on to cool the kiln temperature to 920°C at a rate of 15-20°C / min. Finally, it is slowly cooled to room temperature and removed from the kiln to obtain a ceramic product with the glaze layer on the surface, which is used for subsequent performance testing.

[0062] Example 4: This example provides a heat-resistant ceramic glaze with high thermal shock resistance and low expansion. Its preparation and application verification process includes the following steps: (1) Weigh out the dry base raw materials, the base powder totals 72.0 kg, including 21.0 kg of borosilicate, 11.0 kg of calcined talc, 11.0 kg of kaolin, 21.5 kg of quartz, 3.5 kg of rutile titanium dioxide, 2.0 kg of calcium phosphate, 2.0 kg of zirconium silicate; add 55.0 kg of water and 0.4 kg of sodium polyacrylate.

[0063] (2) The above-mentioned basic powder, added water and sodium polyacrylate are put into a wet ball mill for the first stage of ball milling until the particle size of the solid particles in the slurry reaches D50 of 2.5μm.

[0064] (3) 50 minutes before the ball mill is shut down, 28.0 kg of β-spodumene clinker obtained in Preparation Example 2 is added to the ball mill and mixed milling is continued. Before the ball mill is discharged, a sample is taken for testing to control the particle size D50 of the β-spodumene clinker solid particles in the slurry after mixed milling to be 11.0 μm.

[0065] (4) Dissolve 0.2 kg of sodium carboxymethyl cellulose and 0.15 kg of calcium acetate separately in water beforehand to obtain sodium carboxymethyl cellulose solution and calcium acetate solution for later use. First, add sodium carboxymethyl cellulose solution to the ball mill. Add the sodium carboxymethyl cellulose solution within 1 to 2 minutes and continue to run and disperse for 1 to 2 minutes. Then, add calcium acetate solution at a uniform rate within 3 to 5 minutes. After the calcium acetate solution is added, continue to run until the cumulative running time from the beginning of adding sodium carboxymethyl cellulose solution is 10 minutes. Then stop the machine and discharge the slurry to obtain the required high thermal shock resistant, low expansion heat resistant ceramic glaze (in glaze slurry state).

[0066] (5) Pass the glaze obtained above through a 120-mesh sieve and apply it evenly to the surface of the ceramic green body using a glazing device, controlling the dry base glaze layer thickness to be 0.8 mm.

[0067] (6) The glazed body is sent into a drying kiln and dried at 110°C to remove moisture. Then it is sent into a continuous roller kiln for firing. The firing temperature is controlled at 1180°C and the constant temperature holding time is 20 min. After the holding time is completed, the blower system is turned on to cool the kiln temperature to 920°C at a rate of 15-20°C / min. Finally, it is slowly cooled to room temperature and removed from the kiln to obtain a ceramic product with the glaze layer on the surface, which is used for subsequent performance testing.

[0068] Example 5: This example provides a heat-resistant ceramic glaze with high thermal shock resistance and low expansion. Its preparation and application verification process includes the following steps: (1) Weigh out the dry base raw materials, the base powder totals 78.0 kg, including 18.0 kg of borosilicate, 13.0 kg of calcined talc, 9.0 kg of kaolin, 25.0 kg of quartz, 5.0 kg of rutile titanium dioxide, 4.0 kg of calcium phosphate, 4.0 kg of zirconium silicate; add 55.0 kg of water and 0.3 kg of sodium polyacrylate.

[0069] (2) The above-mentioned basic powder, added water and sodium polyacrylate are put into a wet ball mill for the first stage of ball milling until the particle size of the solid particles in the slurry reaches D50 of 2.5μm.

[0070] (3) 50 minutes before the ball mill is shut down, 22.0 kg of β-spodumene clinker obtained in Preparation Example 2 is added to the ball mill and mixed milling is continued. Before the ball mill is discharged, a sample is taken for testing to control the particle size D50 of the β-spodumene clinker solid particles in the slurry after mixed milling to be 11.0 μm.

[0071] (4) Dissolve 0.2 kg of sodium carboxymethyl cellulose and 0.1 kg of calcium acetate separately in water beforehand to obtain sodium carboxymethyl cellulose solution and calcium acetate solution for later use. First, add sodium carboxymethyl cellulose solution to the ball mill. Add the sodium carboxymethyl cellulose solution within 1 to 2 minutes and continue to run and disperse for 1 to 2 minutes. Then, add calcium acetate solution at a uniform rate within 3 to 5 minutes. After the calcium acetate solution is added, continue to run until a total of 12 minutes have been run since the sodium carboxymethyl cellulose solution was first added. Then stop the machine and discharge the slurry to obtain the desired high thermal shock resistant, low expansion heat-resistant ceramic glaze (in glaze slurry state).

[0072] (5) Pass the glaze obtained above through a 120-mesh sieve and apply it evenly to the surface of the ceramic green body using a glazing device, controlling the dry base glaze layer thickness to be 0.8 mm.

[0073] (6) The glazed body is sent into a drying kiln and dried at 110°C to remove moisture. Then it is sent into a continuous roller kiln for firing. The firing temperature is controlled at 1180°C and the constant temperature holding time is 20 min. After the holding time is completed, the blower system is turned on to cool the kiln temperature to 920°C at a rate of 15-20°C / min. Finally, it is slowly cooled to room temperature and removed from the kiln to obtain a ceramic product with the glaze layer on the surface, which is used for subsequent performance testing.

[0074] Comparative Example 1: Compared with Example 3, the difference is that the order of material addition was changed. Sodium carboxymethyl cellulose and calcium acetate in step (4) were added together with the basic powder in step (2) into a wet ball mill for the first stage of ball milling. The operation in step (4) was cancelled and the slurry was discharged directly. All other aspects are the same.

[0075] Comparative Example 2: Compared with Example 3, the difference is that the type of crosslinking agent was changed, and the calcium acetate in step (4) was replaced with 0.1 kg of calcium nitrate, while the rest were the same.

[0076] Comparative Example 3: Compared with Example 3, the difference is that a traditional suspension system was adopted, without adding sodium polyacrylate, sodium carboxymethyl cellulose and calcium acetate, but instead using a traditional inorganic suspending agent. In step (2), 1.5 kg of bentonite was added together with the base powder for ball milling, and the operation in step (4) was canceled and the slurry was discharged directly. All other aspects are the same.

[0077] Comparative Example 4: Compared with Example 3, the difference is that the mixing and grinding process was changed, the post-mixing and grinding operation in step (3) was cancelled, and the β-spodumene clinker was put into a wet ball mill together with the base powder in step (2) for long-term ball milling until the overall particle size of all solid particles in the slurry reached D50 of 2.5μm, and the rest were the same.

[0078] Comparative Example 5: Compared with Example 3, the difference is that the β-spodumene clinker added in step (3) is replaced with calcined alumina coarse powder of equal mass and with the same particle size D50 of 11.0 μm after milling, while the rest are the same.

[0079] Comparative Example 6: Compared with Example 3, the difference is that the composition of the base powder was changed, zirconium silicate in the formula was removed, and the missing 3.0 kg mass share was made up with an equal mass of quartz, while the rest were the same.

[0080] Test Example 1: Test objective: To verify the effects of process timing and organic crosslinking system on the rheological behavior and suspension properties of glaze slurry.

[0081] The experimental steps are as follows: The slurries prepared in Examples 1 to 5 were selected as test objects, and the slurries from the corresponding stages of Comparative Examples 1 and 3 were selected as reference samples.

[0082] Two sampling points were set for rheological monitoring: at the end of the first stage of ball milling in step (2) and when the machine was stopped and the slurry was discharged in step (4). The sampling volume was 500 mL each time. After sampling, the samples were sealed and kept at a constant temperature of 25°C.

[0083] The rheological parameters of the slurry at each sampling point were measured using a rotational viscometer. A matching coaxial cylindrical test rotor was selected, and the dynamic viscosity data when the system reached steady state were recorded under a constant shear rate.

[0084] For the sample during slurry discharge in step (4), the initial yield stress test was performed using the stress control mode. By gradually applying increasing shear stress and monitoring the strain response, the critical stress value at which the slurry transitions from elastic deformation to plastic flow was determined.

[0085] The experimental results are shown in Table 1: Table 1: Rheological parameter test results of glaze slurries of each group at different preparation stages

[0086] in conclusion: Based on the data in Table 1 and referring to the appendix Figure 1 The dynamic viscosity of Examples 1 to 5 at the end of step (2) was in the range of 184 to 213 mPa·s. The lower initial viscosity kept the base powder in a fluid state during the ball milling stage, which helped the material to deagglomerate and disperse. After entering step (4) and adding calcium acetate, the dynamic viscosity of each example increased compared to the state at the end of step (2), and an initial yield stress of 28.3 to 34.1 Pa was generated in situ. The free calcium ions and the long molecular chains of sodium carboxymethyl cellulose in step (4) underwent strong ionic cross-linking, thereby forming a three-dimensional yield network structure, which provided the physical support required for the suspension of large β-spodumene clinker particles of 10 to 12 μm. Comparative tests showed that when the cross-linking agent was mixed into the slurry in the early stage of grinding in Comparative Example 1, after a long period of ball milling shearing, the yield stress at the time of slurry discharge decreased to 3.5 Pa, and the rheological structure that maintained the suspension of large particles was not constructed. This indicates that the timing of the addition of the cross-linking agent has a direct impact on the slurry state. Comparative Example 3 used bentonite as a suspending agent, and the yield stress at discharge was measured to be 14.8 Pa, which is lower than that of the example group using an organic crosslinking system. The time-sequential decoupling scheme guided the formation of the three-dimensional yield network structure of the slurry by controlling the viscosity in the early stage of grinding and changing the rheological state before discharge.

[0087] Test Example 2: Test objective: To determine the effect of β-spodumene clinker of a specific particle size on the coefficient of thermal expansion of the glaze.

[0088] The experimental steps are as follows: Examples 1 to 5, as well as Comparative Examples 4 and 5, were selected as experimental subjects after the slurry was removed in step (4).

[0089] The above glaze slurry was injected into a plaster mold, dehydrated and dried, and shaped into a long strip sample with dimensions of 50mm×5mm×5mm.

[0090] The long strip sample was placed in a high-temperature box furnace and sintered according to the same firing curve as in step (6). After cooling and removing it from the furnace, the two ends were mechanically polished to obtain a solid glaze block.

[0091] The linear thermal expansion coefficient of the glaze block under test was determined using a thermal dilatometer. The heating rate was set to 5℃ / min, and the test temperature range was from 20℃ to 500℃. The change in sample length at different temperature nodes was recorded and the average linear thermal expansion coefficient was calculated.

[0092] The experimental results are shown in Table 2: Table 2: Average linear thermal expansion coefficient of glaze blocks in different temperature ranges (×10) -6 / ℃)

[0093] in conclusion: Based on the test data in Table 2 and referring to the appendix Figure 2 The β-spodumene clinker obtained in Examples 1 to 3 was introduced into the glaze system as a low-expansion phase. The average linear thermal expansion coefficients of Examples 1 to 5 ranged from 3.95 to 4.48 × 10⁻⁶ in the temperature range of 20 to 500 °C. -6 The overall temperature range was relatively low; among them, the examples with a higher content of β-spodumene clinker exhibited a lower average linear coefficient of thermal expansion. The 10-12 μm large-particle β-spodumene clinker introduced into the formulation underwent shallow surface dissolution during sintering, and the in-situ aggregated aluminum ions increased the local interfacial viscosity, slowing down the erosion rate of the high-temperature liquid relative to the particle interior. Undissolved low-expansion spodumene nuclei remained in the glaze matrix, reducing the overall volume change of the material under heat. In Comparative Example 4, after long-term co-milling of β-spodumene and the base powder, its coefficient of thermal expansion in the 20-500℃ range increased to 6.63 × 10⁻⁶. -6 / ℃. The reduced particle size leads to an increased solid-liquid contact area, resulting in greater dissolution and transformation of spodumene into a glassy phase in the high-temperature melt. This indicates that the degree of retention of particle physical size directly affects the macroscopic expansion data. Comparative Example 5 uses calcined alumina coarse powder instead of β-spodumene, and its measured coefficient of thermal expansion is 7.35 × 10⁻⁶. -6 / ℃. The inherent thermal expansion properties of alumina make it difficult for it to counteract the thermal expansion of the matrix. Retaining a mineral framework with low expansion characteristics in the formulation provides a material basis for maintaining the dimensional stability of the ceramic glaze under temperature fluctuations.

[0094] Test Example 3: Test objective: To evaluate the effects of specific addition timing and pure organic crosslinking system on the suspension stability of glaze slurry and the integrity of film formation during the green body drying stage.

[0095] The experimental steps are as follows: The glaze slurries obtained after slurry removal in step (4) of Examples 1 to 5, as well as Comparative Examples 1 and 3, were selected as experimental subjects.

[0096] Measure 1000 mL of each group of glaze slurry and inject it into a graduated standard glass graduated cylinder. Seal the cylinder and let it stand at room temperature of 25°C for 24 hours. Measure the volume change of the supernatant before and after standing and calculate the 24-hour sedimentation rate.

[0097] Apply the glaze slurry of each group evenly to the surface of ceramic green bodies of the same size, control the dry glaze layer thickness to 0.8 mm, and then place the glazed green bodies in a drying kiln at 110℃ for constant temperature drying for 40 minutes.

[0098] The dried glaze surface was observed under a microscope using a standard light source combined with a grid statistical method. A specific area on the sample surface was randomly selected and divided into 1000 5mm × 5mm micro-grids. The number of grids with mud crack defects was recorded, and the mud crack incidence rate was calculated.

[0099] The experimental results are shown in Table 3: Table 3: Test results of settling rate and drying mud cracking rate of glaze slurry in each group

[0100] in conclusion: Based on the test results in Table 3 and referring to the appendix Figure 3 The 24-hour settling rates of Examples 1 to 5 ranged from 1.18% to 1.82%. Solid-liquid separation during glaze slurry settling easily interferes with the consistency of glaze thickness. The formulations in these examples introduced an organic calcium source before slurry discharge, allowing calcium ions to crosslink with the long polymer chains of sodium carboxymethyl cellulose, forming a thixotropic three-dimensional yield network structure. The yield stress provided by this three-dimensional yield network structure restricts the displacement of 10-12 μm large-particle clinker in the gravitational field, maintaining a uniform distribution of the slurry system. Comparative Example 1, by changing the timing of crosslinking agent addition, showed a settling rate increase to 14.56%. The crosslinking agent added earlier damaged the calcium bridge structure under prolonged ball milling shearing. The damaged polymer network was difficult to reconstruct the required yield stress under static conditions, indicating that the timing of addition directly affects the establishment of the suspension mechanism. The film-forming state during the drying stage reflects the slurry system's ability to cope with shrinkage stress. Comparative Example 3, using a traditional suspension scheme based on bentonite, achieved a mud cracking rate of 85.4%. When layered silicate minerals undergo interlayer water removal, the lattice spacing shrinks, generating tensile stresses that exceed the fracture toughness of the green glaze layer, leading to network cracking on the surface. The organic crosslinking system used in this example removes the high-shrinkage clay component from the formulation, keeping the mud cracking rate at 1.0% or below. The organic network framework possesses a certain deformation tolerance during the water evaporation stage, reducing stress concentration in localized areas and maintaining the structural continuity of the dried glaze layer. This process adjustment scheme based on rheology and material composition provides data reference for alleviating the contradiction between large particle suspension and coating drying shrinkage.

[0101] Test Example 4: Test objective: To determine the effects of different types of crosslinking agents, mixing and grinding processes, and nucleation templates on the exhaust defects and optical properties of ceramic glazes after firing.

[0102] The experimental steps are as follows: Ceramic samples from Examples 1 to 5, as well as Comparative Examples 2, 4, and 6, after firing and exiting the kiln were selected as experimental subjects.

[0103] A shielding plate with a standard 10cm x 10cm opening was used to cover the sample surface. Under a standard detection light source, the number of visible pinholes and bubbles within the opening area was observed and counted. Ten different areas were randomly selected from each sample surface for statistical analysis, and the number of pinholes and bubbles per 100cm area was calculated. 2 The average number of pinholes.

[0104] The cleaned and dried sample was measured using a standard gloss meter. The instrument's measurement angle was set to 60 degrees, and the specular gloss value read when the probe was placed on the glaze surface was recorded.

[0105] The opacity of the glaze layer was determined using a spectrophotometer. By comparing the reflectance ratio of the sample under black and white backings, quantitative data reflecting the light scattering ability of the internal microcrystals and phase-separated droplets were obtained.

[0106] The experimental results are shown in Table 4: Table 4: Test results of air venting defects and optical appearance properties of the glaze after firing for each group

[0107] in conclusion: Based on the test data in Table 4 and referring to the appendix Figure 4In Examples 1 to 5, the number of pinholes per unit area after firing ranged from 1.2 to 2.1, the 60-degree mirror gloss ranged from 45.3 to 51.8, and the opacity reached 88.6% or higher. In ceramic product quality inspection, a low pinhole rate, moderate gloss, and high opacity constitute the physical basis for the warm and smooth texture of the surface. In Comparative Example 2, replacing calcium acetate with inorganic calcium nitrate increased the number of pinholes on the glaze surface to 15.4 after firing. Inorganic nitrates undergo thermal decomposition and release gas during the high-temperature melting and sealing period of the kiln. At this time, the glaze viscosity increases, and the generated bubbles cannot escape from the system, leaving venting defects on the surface. Using organic calcium sources such as calcium acetate allows for gasification and decomposition in the lower temperature range of the kiln preheating zone, avoiding interference caused by gas escape during the high-temperature stage. Comparative Example 4 used a mixed grinding process, resulting in finer solid particles. The measured number of pinholes reached 12.8, the opacity decreased to 35.2%, and the gloss increased to 85.6. Due to the increased contact area, the solubility of refined spodumene particles in the boron-rich calcium melt increases, releasing aluminum ions into the liquid phase and increasing the macroscopic viscosity of the matrix environment. This increased viscosity restricts the escape channels for gases within the base glaze layer and the green body, while simultaneously altering the local chemical composition of the melt, suppressing liquid-liquid phase separation during cooling, ultimately resulting in a transparent glassy state with bubbles. Comparative Example 6, which removed zirconium silicate from its formulation, showed a reduction in opacity to 52.7%. Zirconium silicate acts as a solid-phase template in the melt, providing a low-barrier heterogeneous growth interface for newly formed boron-rich droplets. The absence of this template leads to a reduction in internal nucleation sites, decreased aggregation of microcrystals and phase-separated structures, and weakened light scattering within the glaze layer. Maintaining a low-viscosity macroscopic environment during firing and introducing a suitable nucleation template effectively controls the expulsion of bubbles within the glaze layer and the formation of surface optical appearance.

[0108] Test Example 5: Test objective: To determine the effect of a gradient buffer layer constructed using micro-dissolution behavior on the thermal shock resistance limit, surface hardness, and mechanical wear resistance of ceramic glaze surfaces.

[0109] The experimental steps are as follows: Ceramic samples from Examples 1 to 5, as well as Comparative Examples 4 and 5, after firing and exiting the kiln were selected as experimental subjects.

[0110] The ultimate thermal shock resistance performance was determined using the water quenching method. The sample was placed in an electrically heated drying oven and heated to the set temperature, then held at that temperature for 1 hour. Afterward, it was removed and rapidly immersed in flowing water at 20°C to cool. The sample was dried, and red ink was applied to the surface and left to stand for 5 minutes. After cleaning, the surface was observed under a microscope for the appearance of ink-penetrating network cracks. The heating temperature setpoint of the drying oven was gradually increased, and the highest critical temperature difference at which the sample did not crack after cooling was recorded.

[0111] The surface hardness of the samples was determined using a micro Vickers hardness tester. A constant load of 9.8 Newtons was applied to the test area and held for 15 seconds. The Vickers hardness value was calculated by measuring the diagonal length of the indentation. Eight test points were randomly selected from the surface of each sample to obtain the average value.

[0112] The surface abrasion resistance of the samples was evaluated using a rotary platform grinder. A rubber abrasion wheel was selected and a 1000-gram counterweight was applied. After a grinding cycle of 500 revolutions, the mass loss of the samples was weighed using an analytical balance and recorded.

[0113] The experimental results are shown in Table 5: Table 5: Test results of critical thermal shock resistance temperature difference and mechanical properties of samples in each group

[0114] in conclusion: Based on the data in Table 5 and referring to the appendix Figure 5 The highest critical temperature difference in Examples 1 to 5 ranged from 225 to 265°C, and the wear mass loss after 500 revolutions ranged from 14.8 to 17.1 mg. The structural integrity of the material in response to changes in ambient temperature is related to the product's service life. The coarse β-spodumene particles introduced in the formulations of the examples underwent shallow surface dissolution at the edges in the high-temperature melt. Aluminum ions entering the liquid phase accumulated near the particle interface, increasing the local spatial viscosity. The surface dissolution behavior created a gradient buffer region with gradual compositional change between the residual low-expansion mineral core and the external high-expansion glass matrix. When the sample underwent water quenching shock, the gradient buffer layer smoothed out the physical difference in the coefficient of thermal expansion, alleviated the tensile stress concentration at the interface, and improved the system's ability to withstand temperature changes. The dispersed hard mineral remnants acted as physical load-bearing fulcrums during contact mechanical friction, reducing surface mass wear. In Comparative Example 5, calcined alumina coarse powder was used to replace β-spodumene, and the highest critical temperature difference decreased to 115°C. A mismatch in the coefficient of thermal expansion between alumina and the surrounding silicate glass matrix induced internal microcracks at the particle interface during the kiln cooling stage. Residual stress reduced the fracture toughness of the overall structure, leading to network cracking of the sample under relatively low external thermal shock, indicating that the introduction of high-hardness components requires consideration of the system's thermodynamic stability. In Comparative Example 4, prolonged grinding resulted in powder refinement, with shallow dissolution evolving into volume dissolution, the critical temperature difference decreasing to 165℃, and the wear mass loss increasing to 28.6 mg. Without the support of a low-expansion physical core, the glaze layer transformed into an isotropic homogeneous glass phase, exhibiting brittle mechanical properties. Controlling the size retention of solid particles in the liquid phase and inducing the formation of an interfacial buffer layer helps to balance the mechanical wear resistance and thermal shock resistance of the ceramic surface.

[0115] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A heat-resistant ceramic glaze with high thermal shock resistance and low expansion, characterized in that, The heat-resistant ceramic glaze with high thermal shock resistance and low expansion comprises the following raw materials in parts by weight: The base powder comprises 70.0–80.0 parts, including 18.0–22.0 parts of hard borate, 11.0–14.0 parts of calcined talc, 9.0–12.0 parts of kaolin, 20.0–25.0 parts of quartz, 3.0–5.0 parts of rutile titanium dioxide, 2.0–4.0 parts of calcium phosphate, and 2.0–4.0 parts of zirconium silicate. 20.0–30.0 parts of β-spodumene clinker; Add 50.0 to 60.0 parts of water; Sodium polyacrylate 0.2–0.4 parts; Sodium carboxymethyl cellulose, 0.1–0.3 parts; Calcium acetate 0.05–0.15 parts; The heat-resistant ceramic glaze with high thermal shock resistance and low expansion is in the form of a glaze slurry and meets the following particle size and rheological parameter requirements: The particle size D50 of the solid particles in the base powder of the heat-resistant ceramic glaze with high thermal shock resistance and low expansion is 2.0 to 3.0 μm. The particle size D50 of the β-spodumene clinker solid particles in the heat-resistant ceramic glaze with high thermal shock resistance and low expansion is 10.0-12.0 μm; The initial yield stress of the heat-resistant ceramic glaze with high thermal shock resistance and low expansion was measured at 25°C to be 28.3–34.1 Pa.

2. The heat-resistant ceramic glaze with high thermal shock resistance and low expansion according to claim 1, characterized in that, The heat-resistant ceramic glaze with high thermal shock resistance and low expansion comprises the following raw materials in parts by weight: 75.0 parts of basic powder, which includes 20.0 parts of hard borate, 12.0 parts of calcined talc, 10.0 parts of kaolin, 23.0 parts of quartz, 4.0 parts of rutile titanium dioxide, 3.0 parts of calcium phosphate, and 3.0 parts of zirconium silicate; 25.0 parts of β-spodumene clinker; Add 55.0 parts of water; Sodium polyacrylate 0.3 parts; Sodium carboxymethyl cellulose 0.2 parts; 0.1 parts of calcium acetate.

3. The heat-resistant ceramic glaze with high thermal shock resistance and low expansion according to claim 1, characterized in that, The characteristic parameters of the raw material satisfy the following conditions: The mass fraction of B2O3 in the hard borate is ≥40.0% and the mass fraction of CaO is ≥25.0%. The mass fraction of MgO in the calcined talc is ≥30.0%; The sodium polyacrylate has a weight-average molecular weight (Mw) of 2000–5000 and a solid content of ≥40.0%. The degree of substitution (DS) of the sodium carboxymethyl cellulose is 0.7 to 0.9, and the dynamic viscosity of a 2% aqueous solution of sodium carboxymethyl cellulose at 25°C is ≥800 mPa·s.

4. The heat-resistant ceramic glaze with high thermal shock resistance and low expansion according to claim 1, characterized in that, The β-spodumene clinker was prepared by the following pretreatment method: The α-spodumene ore, whose main component is LiAlSi2O6 and whose Li2O mass fraction is ≥6.5%, is initially crushed to a particle size ≤5mm; it is then placed in a sagger and placed in a calcining kiln, and calcined at a constant temperature of 1030~1080℃ for 2.0~4.0h; after calcination, it is cooled to below 200℃ with the kiln and then dry-crushed to a particle size ≤200μm to obtain the β-spodumene clinker.

5. A method for preparing a heat-resistant ceramic glaze with high thermal shock resistance and low expansion according to any one of claims 1-4, characterized in that, Includes the following steps: S1. The base powder, added water and sodium polyacrylate are put into a wet ball mill for the first stage of ball milling to obtain a decoagulated and dispersed base slurry. S2. Add the β-spodumene clinker to the basic slurry obtained in S1 and continue mixing and grinding. S3. Dissolve sodium carboxymethyl cellulose and calcium acetate separately in water to obtain sodium carboxymethyl cellulose solution and calcium acetate solution, then add them sequentially to the wet ball mill. After mixing, stop the mill and discharge the slurry to obtain the heat-resistant ceramic glaze with high thermal shock resistance and low expansion.

6. The method for preparing the heat-resistant ceramic glaze with high thermal shock resistance and low expansion according to claim 5, characterized in that, The grinding process parameters for steps S1 and S2 are controlled as follows: In step S1, the first stage of ball milling continues until the particle size of the solid particles in the base slurry reaches D50 of 2.0 to 3.0 μm. In step S2, the β-spodumene clinker is fed into the wet ball mill 40 to 60 minutes before the wet ball mill is shut down and discharged. Before exiting the mill, samples are taken for testing to control the particle size D50 of the β-spodumene clinker solid particles in the slurry after mixing and grinding to be 10.0 to 12.0 μm.

7. The method for preparing the heat-resistant ceramic glaze with high thermal shock resistance and low expansion according to claim 5, characterized in that, The feeding sequence in step S3 is controlled as follows: In step S3, a pre-dissolved sodium carboxymethyl cellulose solution is added to the wet ball mill. The sodium carboxymethyl cellulose solution is added within 1 to 2 minutes, and the mill continues to run and disperse for 1 to 2 minutes. Then, a pre-dissolved calcium acetate solution is added at a uniform rate within 3 to 5 minutes. After the calcium acetate solution is added, the mill continues to run until a total of 10 to 15 minutes have elapsed since the addition of the sodium carboxymethyl cellulose solution, at which point the mill is stopped and the slurry is discharged.

8. The method for preparing the heat-resistant ceramic glaze with high thermal shock resistance and low expansion according to claim 5, characterized in that, The dynamic viscosity of the base slurry obtained in step S1 is controlled at 184-213 mPa·s; after adding the pre-dissolved calcium acetate solution in step S3 and stopping the machine to discharge the slurry, the dynamic viscosity of the heat-resistant ceramic glaze with high thermal shock resistance and low expansion reaches 1256-1482 mPa·s.

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