A method for preparing a glaze-decorated ceramic

Abstract

The present application belongs to the technical field of ceramic preparation, and relates to a preparation method of a glaze-in-color ceramic, which comprises the following steps: before body element burning, carrying out water pressing on a body; carrying out body element burning; after the body element burning, carrying out glazing and glaze layer solidification, glaze-in-color drawing, and glazing and glaze firing after the glaze-in-color drawing; the body element burning is a segmented gradient element burning, which comprises a first stage of glue removal and a second stage of densification. The glaze-in-color product prepared by the present application has a glaze surface density of greater than or equal to 2.7 g / cm 3 , a color resolution improved by 35%, a glaze layer bonding strength improved from 2.8 MPa in the traditional process to 4.2 MPa, a bubble defect rate reduced from 3% in the traditional process to less than 0.3%, and is suitable for high-end artistic porcelain and collection-grade ceramic products; the technical contradiction between color fidelity and glaze layer density in glaze-in-color is solved, and color expression, wear resistance, corrosion resistance and safety are considered.

Description

Technical Field

[0001] This invention belongs to the field of ceramic preparation technology and relates to a method for preparing in-glaze ceramics. Background Technology

[0002] Traditional ceramic decoration techniques are mainly divided into three categories: overglaze decoration, in-glaze decoration, and underglaze decoration. Among them: Overglaze decoration requires hand-painting or decal application onto the surface of the porcelain body after glaze firing, followed by low-temperature firing at 700-850℃ to fix the color. However, the painted layer is exposed on the surface, making it prone to wear and fading with long-term use. Furthermore, there is a high risk of leaching heavy metals such as lead and cadmium, making it difficult to meet modern food contact standards in terms of safety.

[0003] Underglaze painting requires applying the color to the surface of the unglazed body and then glazing the entire body before high-temperature firing. The colors are completely covered by the glaze layer. Although it is wear-resistant and safe, high-temperature firing can easily lead to unstable pigment color development, thin color layers, and difficulty in presenting complex and delicate artistic effects.

[0004] The existing in-glaze painting process mostly adopts the process of "one-time glazing + painting + two-time glazing firing" (such as glazing firing at 1100-1200℃), but it generally suffers from problems such as insufficient integration between painting and glaze, high bubble rate, and poor glaze surface smoothness, which limits the artistry and practicality of the finished product.

[0005] As consumers demand "artistic value + practical safety" for ceramic products, there is an urgent need to develop a glaze color preparation process that takes into account color expression, wear resistance, corrosion resistance and safety, in order to solve the technical bottleneck of "difficulty in achieving both artistic effect and durability" in traditional processes. Summary of the Invention

[0006] The main objective of this invention is to overcome the defects in the prior art and provide a method for preparing in-glaze ceramics. The finished product is delicate and smooth, with rich, warm and soft colors, clear images, natural luster, wear resistance, corrosion resistance, long shelf life, high safety, and double-layer protection, making it less prone to firing defects.

[0007] To achieve the above objectives, the specific technical solution is as follows: This invention provides a method for preparing in-glaze ceramics, including bisque firing of the body, wherein the bisque firing of the body is a segmented gradient bisque firing, including a first stage of desizing period and a second stage of densification period; The first stage of the glue removal period: the firing temperature of the blank after water removal is raised from room temperature to 500℃-600℃; the heating rate is 2℃ / min-5℃ / min; and the temperature is held for 20-30 minutes. The second stage, the densification period, involves heating the green body from 500℃-600℃ to 1000℃-1100℃ at a rate of 1℃ / min-3℃ / min, holding it at that temperature for 40-60 minutes, and then cooling it to room temperature.

[0008] The bisque firing process of the in-glaze ceramic preparation method provided by this invention adopts a segmented gradient bisque firing method. This is achieved through a two-stage control: a first-stage desizing period and a second-stage densification period. The first-stage desizing period effectively removes organic matter from the body, while the second-stage densification period effectively controls the body density to 2.3-2.5 g / cm³. 3 The deformation rate of the body is reduced from the traditional 5% to 1.2%. This facilitates precise operation of subsequent glazing and painting processes, avoiding problems such as glaze cracking and misalignment of painted patterns caused by uneven body density or deformation. At the same time, the segmented gradient bisque firing, through reasonable control of the heating rate and holding time, allows the internal stress of the body to be fully released, further improving the mechanical properties of the body. This lays a solid foundation for the good bonding between the glaze and the body in the subsequent glazing firing process, and helps to finally obtain high-quality in-glaze ceramic products with a smooth surface, bright glaze, and stable color.

[0009] Furthermore, the cooling method for the segmented gradient sintering is as follows: after the heat preservation is completed, the furnace is first cooled to 350-450℃, and then cooled to room temperature at a rate of 0.2℃ / min-0.4℃ / min.

[0010] The cooling method of this invention facilitates the uniform release of internal temperature in the green body, avoiding cracking caused by excessive internal stress due to rapid cooling. The kiln-based cooling stage utilizes residual heat to slowly lower the temperature, allowing the green body's structure to stabilize within a higher temperature range. The programmed cooling stage allows for more precise control of the cooling rate at lower temperatures, ensuring that the internal crystal structure remains orderly as the green body cools from 350-450°C to room temperature, reducing the formation of microcracks, and further guaranteeing the structural integrity and dimensional stability of the green body. This provides a higher-quality foundation for subsequent processes such as glazing.

[0011] Furthermore, the green body is subjected to water removal before bisque firing. The method for water removal is as follows: the green body is immersed in water or a mixture of water and ethanol, treated with ultrasound, and then wiped along the texture of the green body with a soft brush; preferably, the green body is treated with 40kHz ultrasound for 10-20 minutes.

[0012] This invention uses ultrasonic-assisted water removal to remove surface and shallow (depth ≤ 50 μm) microporous impurities from the blank.

[0013] Furthermore, after the body is bisque-fired, it is glazed and the glaze layer is cured; the glaze slurry used for glazing includes the following components by weight: The composition includes 18-22 parts quartz, 37-43 parts potassium feldspar, 8-12 parts kaolin, 9-15 parts limestone, 5-10 parts talc, 4-8 parts borax, 2-5 parts zinc oxide, and 4-7 parts nano-zirconia; the nano-zirconia has a particle size of 28-33 nm.

[0014] This invention adds nano-zirconia to form a dispersed reinforcing phase, thereby improving the hardness of the glaze surface.

[0015] Furthermore, the glaze preparation process for glazing the green body after bisque firing is as follows: after mixing the components, the mixture is ball-milled for 10 hours at a speed of 500 r / min and then passed through a 200-mesh sieve with a ball-to-material ratio of 4:1; the concentration is adjusted to 55±1 Baume degrees.

[0016] Furthermore, the glazing method is one of dipping, glazing, spraying, or brushing; preferably electrostatic spraying, the glaze film thickness is 0.15-0.2mm; more preferably, the electrostatic spraying voltage is 60kV; ensuring that the glaze layer uniformly covers the uneven surface of the blank.

[0017] Furthermore, the glaze curing process includes a heating procedure and cooling control: Heating procedure: The firing temperature of the glazed body is raised from room temperature to 650℃ at a heating rate of 5℃ / min and held for 70min to allow the glaze to initially melt and solidify. Cooling control: First, forced air cooling is used to reduce the temperature to 200°C, and then it is allowed to cool naturally to room temperature; the forced air cooling wind speed is 1.5 m / s to prevent glaze crystallization.

[0018] Furthermore, after the glaze layer has cured, in-glaze painting is performed. The pigments used in the in-glaze painting, by weight, include the following components: The composition includes: 40-50 parts colorant core, 8-12 parts SiO2 nanoparticles, 30-40 parts borosilicate glass powder, 1.5-2.5 parts sodium carboxymethyl cellulose, and 2-4 parts γ-aminopropyltriethoxysilane. The colorant core is vanadium zirconium yellow or chromium aluminum red, the SiO2 nanoparticles have a particle size of 20 nm, and the borosilicate glass powder has a softening point of 700 °C.

[0019] This invention, by adding SiO2 nanoparticles, forms a nanolayer encapsulating the colorant, preventing color loss due to metal ion diffusion at high temperatures, thus improving color resolution by 35%. Simultaneously, the SiO2 nanoparticles refine the microstructure of the pigment layer through a filling effect, enhancing color saturation and gloss, ensuring that the in-glaze painting maintains a clear and stable artistic effect after subsequent high-temperature firing. Borosilicate glass powder forms a good fusion bond with the body and the isolation layer; its low coefficient of expansion reduces the thermal stress difference between the pigment layer and the glaze surface, preventing cracking in the painted area. Sodium carboxymethyl cellulose, as a dispersant, ensures uniform mixing of the components and maintains the rheological properties of the pigment, facilitating both manual and mechanical painting. γ-aminopropyltriethoxysilane enhances the bonding between the SiO2 nanoparticles and the colorant core.

[0020] Furthermore, the preparation method of the pigments used in the in-glaze painting is as follows: SiO2 nanoparticles are prepared into a silica sol with a mass concentration of 15%, the colorant core, borosilicate glass powder, and sodium carboxymethyl cellulose are dispersed in the silica sol, γ-aminopropyltriethoxysilane is added, the mixture is stirred in a water bath at 65°C for 4 hours, centrifuged and dried, and then calcined at 650-700°C for 2.5 hours to obtain nano-pigment particles with a SiO2 coating on the surface.

[0021] Furthermore, the painting technique of the underglaze painting adopts one of the following: hand brush painting, spray painting, screen printing, and decal transfer; hand brush painting is preferred; micro brush painting is more preferred, with the line width controlled at 0.2-0.5mm.

[0022] Furthermore, the underglaze painting is followed by glazing and firing; the glaze slurry used for glazing after underglaze painting comprises, by weight, the following components: The composition includes 27-32 parts quartz, 26-35 parts potassium feldspar, 9-15 parts kaolin, 7-14 parts limestone, 8-13 parts talc, 3-7 parts borax, 3-6 parts titanium dioxide, and 1-4 parts nano-alumina, wherein the nano-alumina has a particle size of 50 nm. The preferred glaze preparation process for the glaze slurry used after in-glaze painting is as follows: after mixing the components, the mixture is ball-milled for 12 hours at a speed of 500 r / min and then passed through a 220-mesh sieve with a ball-to-material ratio of 4:1; the concentration is adjusted to 48±1 Baume degrees.

[0023] Furthermore, the method of applying glaze after the in-glaze painting is: immersion glaze and centrifugal glaze spinning. The centrifugal glaze spinning speed is 300 r / min and the time is 30s to ensure that the pigment layer is completely covered and the glaze layer thickness is 0.3-0.4mm.

[0024] Furthermore, the glaze firing adopts a dual-atmosphere gradient glaze firing, including an oxidation stage, a reduction stage, and a cooling stage; The oxidation stage involves heating the glaze firing temperature of the body after in-glaze painting and glazing from room temperature to 980-1050℃, introducing oxygen at a flow rate of 2L / min-3.0L / min, a heating rate of 3℃ / min-5℃ / min, and holding the temperature for 30min. The reduction stage involves heating the glaze firing temperature from 980-1050℃ to 1250-1300℃, introducing a mixed atmosphere of hydrogen and nitrogen with a volume ratio of 1:9, a heating rate of 1℃ / min-3℃ / min, and holding at that temperature for 60 minutes. Cooling stage: The glaze firing temperature is reduced from 1250-1300℃ to 800℃ at a rate of 3℃ / min-5℃ / min; then it is allowed to cool naturally to room temperature.

[0025] This invention employs a dual-atmosphere gradient glaze firing process. In the oxidation stage, oxygen is introduced and the heating rate is controlled to effectively remove organic impurities and carbon from the body and glaze, avoiding defects such as pinholes and bubbles on the glaze surface. The bubble defect rate is reduced from 3% to below 0.3%. In the reduction stage, a mixed atmosphere of hydrogen and nitrogen is used to adjust the valence state of metal oxides in the glaze, thereby enriching the color layers of the glaze surface. At the same time, the slow heating rate and heat preservation process help crystals to develop fully, enhancing the mechanical properties of the glaze layer. In the cooling stage, the cooling rate is first controlled to prevent the glaze surface from cracking due to internal stress caused by rapid cooling. Then, it is naturally cooled to room temperature to ensure a tight bond between the glaze layer and the body, forming a stable overall structure and a uniform glass phase glaze surface, resulting in the finished product.

[0026] Furthermore, in the dual-atmosphere gradient glazing process, microwave-assisted heating is introduced at 1100-1150℃, preferably with a microwave-assisted heating frequency of 2450MHz, a power of 500-600W, and a time of 20-30min.

[0027] This invention introduces microwave-assisted heating, which can directly act on the polar molecules inside the glaze, causing the molecules to vibrate at high frequency and generate heat through mutual friction. This achieves overall heating of the glaze from the inside out, promoting the melting, diffusion, and reaction of various mineral components in the glaze in a more uniform thermal environment. It reduces problems such as uneven crystallization and differences in glaze gloss caused by local overheating or insufficient reaction, further improving the smoothness and gloss of the glaze surface. At the same time, it also helps the nano-encapsulated pigments to disperse more stably in the glaze layer, ensuring the color uniformity and vibrancy of the painted pattern.

[0028] Compared with the prior art, the present invention has the following significant advantages: This invention provides a method for preparing in-glaze ceramics, employing ultrasonic-assisted water removal to eliminate microporous impurities in the body; a segmented bisque firing process of "low-temperature debinding - medium-temperature densification" is designed to control the shrinkage rate of the body; a high-flowability glaze slurry containing nano-zirconia is used in the first glazing to form an isolation layer; SiO2-coated nano-pigmentation is used to prevent high-temperature diffusion of the painting pigments; microwave pre-firing is introduced after the second glazing to eliminate interface bubbles; and finally, a dual-atmosphere glazing firing of "oxidation-reduction" promotes uniform crystal growth in the glaze layer. The glaze density of the finished in-glaze ceramic produced by this invention is ≥2.7 g / cm³. 3 The color resolution is improved by 35%, the glaze bonding strength is increased from 2.8MPa in the traditional process to 4.2MPa, and the bubble defect rate is reduced from 3% to below 0.3%, making it suitable for high-end art porcelain and collectible ceramic products. It solves the technical contradiction between "color fidelity" and "glaze density" in in-glaze coloring, and balances color expression, wear resistance, corrosion resistance and safety. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0030] Unless otherwise specified in the embodiments of the present invention, the techniques or conditions described in the literature in this field or the product instructions shall be followed; if the manufacturers of the reagents or instruments used are not specified, they are all conventional products that can be purchased through legitimate channels.

[0031] Example 1 This embodiment provides a method for preparing in-glaze ceramics, including the following steps: (1) Ultrasonic-assisted water removal process: Immerse the billet in a mixture of deionized water and ethanol (volume ratio 2:1), treat it with 40kHz ultrasound for 15min, and then wipe it along the texture of the billet with a soft brush to remove surface and shallow (depth ≤50μm) microporous impurities. (2) Segmented gradient sintering: First stage of glue removal period: room temperature → 550℃, heating rate 3℃ / min, holding temperature for 25min, to remove organic matter from the green body; Second stage, densification period: 550℃→1050℃, heating rate 1.8℃ / min, holding for 50min, controlling the density of the green body to 2.3-2.5g / cm³. 3 ; Cooling method: Cool with the furnace up to 400℃ (rate 2℃ / min), and then cool down to room temperature at a rate of 0.3℃ / min after 400℃; (3) One-time glazing (isolation layer): By weight, the glaze slurry includes: 20 parts quartz, 40 parts potassium feldspar, 10 parts kaolin, 12 parts limestone, 8 parts talc, 6 parts borax, 4 parts zinc oxide, and 5 parts nano-zirconia (particle size 30nm). Glaze preparation process: Each component is ball-milled for 10 hours using a planetary ball mill (500 r / min, ball-to-material ratio 4:1), passed through a 200-mesh sieve, and the concentration is adjusted to 55 Baume degrees. Glazing method: electrostatic spraying (voltage 60kV, film thickness 0.15mm) to ensure that the glaze layer evenly covers the uneven surface of the body; (4) Glaze curing: Heating program: room temperature → 650℃, heating rate 5℃ / min, hold for 70min to allow the glaze to initially melt and solidify; Cooling control: Forced air cooling up to 200℃ with a wind speed of 1.5m / s, followed by natural cooling to room temperature to prevent glaze crystallization; (5) Underglaze painting: By weight, the pigments include: 45 parts of colorant core (vanadium zirconium yellow), 10 parts of SiO2 nanoparticles (particle size 20nm), 35 parts of borosilicate glass powder (softening point 700℃), 2 parts of sodium carboxymethyl cellulose, and 2.5 parts of γ-aminopropyltriethoxysilane. The preparation method of nano-encapsulated pigment is as follows: SiO2 nanoparticles are prepared into a silica sol with a mass concentration of 15%. The colorant core, borosilicate glass powder, and sodium carboxymethyl cellulose are dispersed in the silica sol with a mass concentration of 15%. Finally, γ-aminopropyltriethoxysilane is added, and the mixture is stirred in a water bath at 65°C for 4 hours. After centrifugation and drying, it is calcined at 650°C for 2.5 hours to obtain nano-pigment particles with a surface coating of SiO2.

[0032] Painting technique: Use a micro brush (0.1mm tip diameter) to draw, with line width controlled between 0.2-0.5mm, and allow to dry naturally for 3 hours; (6) Second glazing (protective layer): By weight, the glaze slurry includes: 30 parts quartz, 30 parts potassium feldspar, 12 parts kaolin, 10 parts limestone, 12 parts talc, 5 parts borax, 4 parts titanium dioxide, and 3 parts nano alumina (particle size 50nm). Glaze preparation process: Each component is ball-milled for 12 hours in a planetary ball mill (500 r / min, ball-to-material ratio 4:1), and then passed through a 220 mesh sieve to a concentration of 48 Baume degrees. Glazing method: immersion glazing + centrifugal glazing (300r / min, 30s), ensuring complete coverage of the pigment layer, with a glaze thickness of 0.3mm; (7) Dual-atmosphere gradient glaze firing: Oxidation stage: room temperature → 1000℃, oxygen is introduced (flow rate 2.5L / min), heating rate 4℃ / min, and held for 30min; Reduction stage: 1000℃→1260℃, switch to hydrogen-nitrogen mixed atmosphere (volume ratio 1:9), heating rate 2℃ / min, hold for 60min; Cooling stage: 1260℃→800℃, rate 3℃ / min; natural cooling below 800℃ to form a uniform glass phase glaze, and then firing to produce the finished product; During the glaze firing process, microwave-assisted heating (frequency 2450MHz, power 600W) is introduced at 1100℃ for 20 minutes to promote uniform melting of the glaze layer.

[0033] The performance test results of the finished product prepared in Example 1 are shown in Table 1: Table 1. Performance test results of the finished product prepared in Example 1.

[0034] Example 2 This embodiment provides a method for preparing in-glaze ceramics, including the following steps: (1) Ultrasonic-assisted water removal process: Immerse the billet in a mixture of deionized water and ethanol (volume ratio 2:1), treat it with 40kHz ultrasound for 15min, and then wipe it along the texture of the billet with a soft brush to remove surface and shallow (depth ≤50μm) microporous impurities. (2) Segmented gradient sintering: First stage of glue removal period: room temperature → 550℃, heating rate 3℃ / min, holding temperature for 25min, to remove organic matter from the green body; Second stage, densification period: 550℃→1050℃, heating rate 1.8℃ / min, holding for 50min, controlling the density of the green body to 2.3-2.5g / cm³. 3 ; Cooling method: Cool with the furnace up to 400℃ (rate 2℃ / min), and then cool down to room temperature at a rate of 0.3℃ / min after 400℃; (3) One-time glazing (isolation layer): By weight, the glaze slurry includes: 21 parts quartz, 36 parts potassium feldspar, 9 parts kaolin, 13 parts limestone, 6 parts talc, 5 parts borax, 4 parts zinc oxide, and 6 parts nano-zirconia (particle size 30nm). Glaze slurry preparation process: Each component is ball-milled for 10 hours at a speed of 500 r / min and a ball-to-material ratio of 4:1, then passed through a 200-mesh sieve and the concentration is adjusted to 56 Baume degrees. Glazing method: electrostatic spraying (voltage 60kV, film thickness 0.18mm) to ensure that the glaze layer evenly covers the uneven surface of the body; (4) Low-temperature pre-firing (glaze curing): Heating program: room temperature → 650℃, heating rate 5℃ / min, hold for 70min to allow the glaze to initially melt and solidify; Cooling control: Forced air cooling up to 200℃ with a wind speed of 1.5m / s, followed by natural cooling to room temperature to prevent glaze crystallization; (5) Nano-encapsulated pigment painting: Pigment composition (parts by weight): Colorant core (chrome aluminum red) 45 parts, SiO2 nanoparticles (particle size 20nm) 10 parts, borosilicate glass powder (softening point 700℃) 35 parts, sodium carboxymethyl cellulose 2 parts, γ-aminopropyltriethoxysilane 2.5 parts; The preparation method of nano-coated pigment is as follows: SiO2 nanoparticles are prepared into a silica sol with a mass concentration of 15%. The colorant core, borosilicate glass powder, and sodium carboxymethyl cellulose are dispersed in the silica sol with a mass concentration of 15%. 2.8 parts of γ-aminopropyltriethoxysilane are added. The mixture is stirred in a water bath at 65°C for 4 hours. After centrifugation and drying, it is calcined at 680°C for 2.5 hours to obtain nano-pigment particles with a surface coating of SiO2.

[0035] Painting technique: Use a micro brush (0.1mm tip diameter) to draw, with line width controlled between 0.2-0.5mm, and allow to dry naturally for 3 hours; (6) Second glazing (protective layer): By weight, the glaze slurry includes: 30 parts quartz, 30 parts potassium feldspar, 12 parts kaolin, 10 parts limestone, 12 parts talc, 5 parts borax, 4 parts titanium dioxide, and 3 parts nano alumina (particle size 50nm). Glaze preparation process: Each component is ball-milled for 12 hours in a planetary ball mill (500 r / min, ball-to-material ratio 4:1), and then passed through a 220 mesh sieve to a concentration of 48 Baume degrees. Glazing method: immersion glazing + centrifugal glazing (300r / min, 30s), ensuring complete coverage of the pigment layer, with a glaze thickness of 0.3mm; (7) Dual-atmosphere gradient glaze firing: Oxidation stage: room temperature → 1000℃, oxygen is introduced (flow rate 2.5L / min), heating rate 4℃ / min, and held for 30min; Reduction stage: 1000℃→1260℃, switch to hydrogen-nitrogen mixed atmosphere (volume ratio 1:9), heating rate 2℃ / min, hold for 60min; Cooling stage: 1260℃→800℃, rate 3℃ / min; natural cooling below 800℃ to form a uniform glass phase glaze, and then firing to produce the finished product; During the glaze firing process, microwave-assisted heating (frequency 2450MHz, power 600W) is introduced at 1100℃ for 20 minutes to promote uniform melting of the glaze layer.

[0036] The performance test results of the finished product prepared in Example 2 are shown in Table 2: Table 2 Performance test results of the finished product prepared in Example 2

[0037] Comparative Example 1 This comparative example provides a method for preparing traditional in-glaze ceramics, including the following steps: (1) Ultrasonic-assisted water removal process: Immerse the billet in a mixture of deionized water and ethanol (volume ratio 2:1), treat it with 40kHz ultrasound for 15min, and then wipe it along the texture of the billet with a soft brush to remove surface and shallow (depth ≤50μm) microporous impurities. (2) One-time glazing (isolation layer): By weight, the glaze slurry includes: 20 parts quartz, 40 parts potassium feldspar, 10 parts kaolin, 12 parts limestone, 8 parts talc, 6 parts borax, 4 parts zinc oxide, and 5 parts nano-zirconia (particle size 30nm). Glaze preparation process: Each component is ball-milled for 10 hours using a planetary ball mill (500 r / min, ball-to-material ratio 4:1), passed through a 200-mesh sieve, and the concentration is adjusted to 55 Baume degrees. Glazing method: electrostatic spraying (voltage 60kV, film thickness 0.15mm) to ensure that the glaze layer evenly covers the uneven surface of the body; (3) Glaze curing: Heating program: room temperature → 650℃, heating rate 5℃ / min, hold for 70min to allow the glaze to initially melt and solidify; Cooling control: Forced air cooling up to 200℃ with a wind speed of 1.5m / s, followed by natural cooling to room temperature to prevent glaze crystallization; (4) Underglaze painting: By weight, the pigment comprises: 100 parts of colorant core (vanadium zirconium yellow); Painting technique: Use a micro brush (0.1mm tip diameter) to draw, with line width controlled between 0.2-0.5mm, and allow to dry naturally for 3 hours; (5) Second glazing (protective layer): By weight, the glaze slurry includes: 30 parts quartz, 30 parts potassium feldspar, 12 parts kaolin, 10 parts limestone, 12 parts talc, 5 parts borax, 4 parts titanium dioxide, and 3 parts nano alumina (particle size 50nm). Glaze preparation process: Each component is ball-milled for 12 hours in a planetary ball mill (500 r / min, ball-to-material ratio 4:1), and then passed through a 220 mesh sieve to a concentration of 48 Baume degrees. Glazing method: immersion glazing + centrifugal glazing (300r / min, 30s), ensuring complete coverage of the pigment layer, with a glaze thickness of 0.3mm; (7) Glazing: Room temperature → 1260℃, heating rate 2℃ / min, hold for 60min; Cooling stage: 1260℃→800℃, rate 3℃ / min; natural cooling below 800℃ to form a uniform glass phase glaze, and then firing to produce the finished product; The performance test results of the finished product prepared in Comparative Example 1 are shown in Table 3: Table 3 shows the performance test results of the finished product prepared in Comparative Example 1.

[0038] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing in-glaze ceramics, comprising bisque firing of the body, characterized in that, The green body is sintered in a segmented gradient sintering process, including a first stage of debinding and a second stage of densification. The first stage of the debinding period: the firing temperature of the green body is heated from room temperature to 500℃-600℃; the heating rate is 2℃ / min-5℃ / min; and the temperature is held for 20-30 minutes. The second stage, the densification period, involves heating the green body from 500℃-600℃ to 1000℃-1100℃ at a rate of 1℃ / min-3℃ / min. Keep warm for 40-60 minutes, then cool to room temperature.

2. The method for preparing in-glaze ceramics according to claim 1, characterized in that, After the body is bisque-fired, it is glazed and the glaze layer is cured; after the glaze layer is cured, it is painted with in-glaze colors. The pigments used in the underglaze painting, by weight, comprise the following components: The composition includes: 40-50 parts colorant core, 8-12 parts SiO2 nanoparticles, 30-40 parts borosilicate glass powder, 1.5-2.5 parts sodium carboxymethyl cellulose, and 2-4 parts γ-aminopropyltriethoxysilane. The colorant core is vanadium zirconium yellow or chromium aluminum red, the SiO2 nanoparticles have a particle size of 20 nm, and the borosilicate glass powder has a softening point of 700 °C.

3. The method for preparing in-glaze ceramics according to claim 2, characterized in that, The preparation method of the pigments used in the in-glaze painting includes: preparing SiO2 nanoparticles into a silica sol with a mass concentration of 15%; dispersing the colorant core, borosilicate glass powder, and sodium carboxymethyl cellulose in the silica sol; adding γ-aminopropyltriethoxysilane; stirring at 65°C for 4 hours; centrifuging and drying; and calcining at 650-700°C for 2.5 hours to obtain nano-pigment particles with a SiO2 coating on the surface.

4. The method for preparing underglaze colored ceramics according to any one of claims 1-3, characterized in that, This also includes in-glaze painting followed by glazing and firing; The glaze firing adopts a dual-atmosphere gradient glaze firing method, including an oxidation stage, a reduction stage, and a cooling stage; The oxidation stage involves heating the glaze firing temperature of the body after in-glaze painting to 980-1050℃ from room temperature, introducing oxygen at a flow rate of 2L / min-3.0L / min, a heating rate of 3℃ / min-5℃ / min, and holding the temperature for 30min. The reduction stage involves heating the glaze firing temperature from 980-1050℃ to 1250-1300℃, introducing a mixed atmosphere of hydrogen and nitrogen with a volume ratio of 1:9, a heating rate of 1℃ / min-3℃ / min, and holding at that temperature for 60 minutes. Cooling stage: The glaze firing temperature is reduced from 1250-1300℃ to 800℃ at a rate of 3℃ / min-5℃ / min; then it is allowed to cool naturally to room temperature.

5. The method for preparing in-glaze ceramics according to claim 4, characterized in that, In the dual-atmosphere gradient glazing process, microwave-assisted heating is introduced at 1100-1150℃. Preferably, the microwave-assisted heating frequency is 2450MHz, the power is 500-600W, and the time is 20-30min.

6. The method for preparing in-glaze ceramics according to any one of claims 1-3, characterized in that, The glaze slurry used for glazing the bisque-fired body comprises, by weight, the following components: The composition includes 18-22 parts quartz, 37-43 parts potassium feldspar, 8-12 parts kaolin, 9-15 parts limestone, 5-10 parts talc, 4-8 parts borax, 2-5 parts zinc oxide, and 4-7 parts nano-zirconia; the nano-zirconia has a particle size of 28-33 nm. The preferred process for preparing the glaze slurry for glazing after the bisque firing of the body is as follows: after mixing the components, the mixture is ball-milled for 10-12 hours at a speed of 500 r / min and then passed through a 200-mesh sieve with a ball-to-material ratio of 4:1; the concentration is adjusted to 55±1 Baume degrees.

7. The method for preparing in-glaze ceramics according to claim 1, characterized in that, The cooling method for the segmented gradient sintering is as follows: after the heat preservation is completed, the furnace is first cooled to 350-450℃, and then cooled to room temperature at a rate of 0.2℃ / min-0.4℃ / min.

8. The method for preparing underglaze colored ceramics according to any one of claims 7, characterized in that, Before bisque firing, the green body is subjected to water removal. The method for water removal is as follows: immerse the green body in water or a mixture of water and ethanol, treat it with ultrasound, and then wipe it along the texture of the green body with a soft brush; preferably, treat it with 40kHz ultrasound for 10-20 minutes.

9. The method for preparing in-glaze ceramics according to claim 2, characterized in that, The glaze curing process includes a heating procedure and cooling control: Heating procedure: The firing temperature of the glazed body is raised from room temperature to 650℃, the heating rate is 5℃ / min, and the holding time is 70min; Cooling control: First, forced air cooling is used to reduce the temperature to 200°C, and then it is naturally cooled to room temperature; the air velocity of the forced air cooling is 1.5 m / s.

10. The method for preparing in-glaze ceramics according to claim 4, characterized in that, The glaze used after in-glaze painting comprises the following components by weight: The composition includes 27-32 parts quartz, 26-35 parts potassium feldspar, 9-15 parts kaolin, 7-14 parts limestone, 8-13 parts talc, 3-7 parts borax, 3-6 parts titanium dioxide, and 1-4 parts nano-alumina, wherein the nano-alumina has a particle size of 50 nm. The preferred glaze preparation process for the glaze slurry used after in-glaze painting is as follows: after mixing the components, the mixture is ball-milled for 10-12 hours at a speed of 500 r / min and then passed through a 220-mesh sieve with a ball-to-material ratio of 4:1; the concentration is adjusted to 48±1 Baume degrees.

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