A greenish-yellow tea dust porcelain and a preparation method thereof

Abstract

The application provides a kind of green mixed yellow tea leaf powder porcelain, including green mixed yellow tea leaf powder glaze and green mixed yellow tea leaf powder porcelain.The green mixed yellow tea leaf powder glaze provided by the application includes quartz 15-20%, feldspar 35-40%, kaolin 5-10%, talc 10-15%, calcite 15-20%, ocher 3-5%, barium oxide 0.5-1%, bone ash 0.5-2%, which are mixed and then ball milled in a ball mill to obtain a slurry, and then a crystallization agent is added to the slurry and stirred uniformly to obtain the green mixed yellow tea leaf powder glaze.The green mixed yellow tea leaf powder glaze is applied to the surface of a green body, the glaze slurry on the bottom of the green body is scraped off after application, and the green body is dried to obtain a green body to be fired, and the green body to be fired is fired to obtain the green mixed yellow tea leaf powder porcelain.The process is simple, cost-saving and time-saving, and only one firing is required without the need for multiple coating of glaze.The green mixed yellow tea leaf powder porcelain fired by the preparation method of the application has rich and bright color, the tea leaf powder glaze layer is not easy to fall off, and the combination with the green body is good.

Description

Technical Field

[0001] The invention relates to the technical field of ceramic materials, in particular to green and yellow tea-leaf glaze porcelain and a preparation method thereof. Background Art

[0002] Tea-dust glaze originated from Tang Dynasty black glaze. Initially, it appears to have been a special type of black glaze, resulting from over-firing. It was not popular during the Tang and Song dynasties. Jingdezhen kilns in the Ming Dynasty also produced tea-dust glaze, but very few surviving pieces exist. The reigns of the Yongzheng and Qianlong dynasties of the Qing Dynasty truly marked the peak of tea-dust glaze production, with the Qianlong era achieving the highest level of success. Analysis of its chemical composition and crystal structure reveals that tea-dust glaze is a microcrystalline glaze with iron as the primary crystallizer and colorant. Its primary crystalline phase is orthopyroxene, making it a particularly important iron-based crystalline glaze. Tea-dust glaze is a high-temperature fired crystalline glaze, produced at temperatures between 1200°C and 1300°C in a reducing atmosphere.

[0003] Tea-leaf glaze is challenging to fire. The influence of firing temperature and the reducing-oxidizing atmosphere alters the crystal structure and nucleation growth of Fe₂O₃ and FeO, resulting in distinct colors and particle distributions, resulting in tea-leaf glazes such as "Crab Shell Blue" and "Fish Yellow." Tea-leaf glaze is highly sensitive to firing conditions. The higher the firing temperature, the richer the atmosphere, the darker the glaze, and the shinier the yellow gold specks are. The lower the firing temperature, the lighter the atmosphere, the paler the glaze, and the less visible gold specks are visible. Fine yellow-brown specks, resembling tea leaves, shimmer against a dark green background.

[0004] In recent years, relevant scholars have made certain breakthroughs in the research on the imitation of tea-leaf glaze porcelain. In the existing technology, the Chinese patent with the announcement number CN111704359B and the announcement date of 2022-05-24 discloses a tea-leaf glaze prepared from natural mineral soil and its firing method. The loess and screw soil are crushed and mixed evenly, and the mixed soil ore is added to the ball mill, and then water is added. After ball milling for 70-75 hours, the glaze is applied and fired. The loess and screw soil used in this method are both produced in Jianshui County, Yunnan Province. The raw materials are not easy to obtain and the ball milling and firing time in the preparation process are relatively long.

[0005] The Chinese patent with announcement number CN108752050B and announcement date of 2020-12-15 discloses a Ru porcelain tea-leaf glaze and its production method. It uses 3-7 parts of black feldspar, 2-4 parts of golden soil, 28-32 parts of dolomite, 11-15 parts of quartz, 12-16 parts of calcite, 0.5-1.5 parts of talc, 0.5-1 part of agate, and 5-7 parts of bone ash. After the mixture is left to oxidize for 3-5 months, it is finely ground and water is added to obtain a glaze using Baume metering concentration. After the body is bisque-fired, it is dipped in glaze twice and placed in a kiln for high-temperature firing at a temperature of 950℃-1200℃ and a firing time of 12-16 hours. This method has complicated process steps and is time-consuming. It requires multiple coatings of glaze, drying and firing. The tea-leaf glaze does not bond well with the body and is easy to fall off.

[0006] Therefore, there is an urgent need for a tea-leaf glaze porcelain firing technology that has a simple preparation process, short time consumption, does not require multiple coatings of glaze, has a bright color, and has a good combination of glaze layer and body. Summary of the Invention

[0007] To address the above-mentioned issues, the present invention provides a green-yellow tea-leaf glaze porcelain and a method for preparing the same. This method simplifies the process, reduces costs and firing time, and requires only a single firing, eliminating the need for multiple glaze applications. The green-yellow tea-leaf glaze porcelain fired using this method exhibits rich and lustrous color, and the tea-leaf glaze layer resists shedding and adheres well to the base.

[0008] As a first aspect of the present invention, the present invention provides a green-yellow tea-leaf glaze, which includes 15-20% quartz, 35-40% feldspar, 5-10% kaolin, 10-15% talc, 15-20% calcite, 3-5% ochre, 0.5-1% barium oxide, 0.5-2% bone ash, and 1-2% crystallizer.

[0009] Furthermore, the crystallization agent is prepared by mixing zinc oxide, quartz and ochre and then sintering them.

[0010] The key components in preparing a green-yellow tea-leaf glaze include glaze, flux, and crystallizer. Calcite and barium oxide act as fluxes, lowering the glaze's melting temperature. Talc, bone ash, and crystallizers promote crystallization. Crystallizers not only facilitate crystallization but also alter the glaze's transparency, fluidity, and gloss.

[0011] As a second aspect of the present invention, a method for preparing a green-yellow tea-leaf glaze is provided. The method comprises mixing quartz, feldspar, kaolin, talc, calcite, ochre, barium oxide, and bone ash to obtain a first mixed material; ball-milling the first mixed material in a ball mill and then sieving the mixed material to obtain a slurry; adding a crystallizing agent to the slurry and uniformly stirring the mixture to obtain the green-yellow tea-leaf glaze. The green-yellow tea-leaf glaze comprises the following weight percentages: quartz 15-20%, feldspar 35-40%, kaolin 5-10%, talc 10-15%, calcite 15-20%, ochre 3-5%, barium oxide 0.5-1%, bone ash 0.5-2%, and crystallizing agent 1-2%.

[0012] Furthermore, the first mixed material, grinding balls and water are mixed in a mass ratio of material: balls: water of 1:1.5-2:0.8-1, and then added into a ball mill for grinding for 10-12 hours and then sieved to obtain a slurry.

[0013] Furthermore, the crystallization agent is prepared by mixing zinc oxide, quartz, and ochre and then grinding, sintering, and grinding. The zinc oxide, quartz, and ochre are mixed and ground to a fineness of 100-120 mesh, calcined at 1330-1350° C., and then further ground to a fineness of 60-80 mesh.

[0014] As a third aspect of the present invention, the present invention provides a green and yellow tea-leaf glaze porcelain, comprising a body and a glaze prepared by the green and yellow tea-leaf glaze preparation method provided by the second aspect of the present invention, glazing the surface of the body, scraping off the glaze slurry at the bottom of the body after glazing and drying to obtain a body to be fired, and firing the body to be fired to obtain the green and yellow tea-leaf glaze porcelain.

[0015] Furthermore, the method of glazing the body surface includes: adding sodium metasilicate solution to the green and yellow tea-leaf glaze to adjust the glaze slurry concentration, and then completely immersing the body in the glaze slurry, with the glazing thickness being 0.8-1.0 mm.

[0016] Adding sodium metasilicate to the glaze slurry can reduce the surface tension of the glaze, improve the fluidity and viscosity of the glaze, reduce the shrinkage rate of the glaze, and prevent problems such as cracking and loosening of the glaze surface.

[0017] Furthermore, the method for firing the green-yellow tea-leaf glaze porcelain comprises placing the green-yellow tea-leaf glaze porcelain in a kiln and firing it at 1280°C-1310°C in a reducing atmosphere to obtain the green-yellow tea-leaf glaze porcelain. The firing method comprises low-temperature oxidation, medium-temperature weak reduction, and high-temperature strong reduction firing. The specific firing system is as follows:

[0018] Drying stage (kiln temperature -200°C), heating rate is 2-3°C / min;

[0019] Oxidative decomposition stage (200-850°C), heating rate is 5-7°C / min;

[0020] Low temperature holding stage (850-950℃), heating rate is 1-2℃ / min, CO concentration is 1%-2%;

[0021] High temperature stage (950-1310℃), heating rate is 5-7℃ / min, CO concentration is 2%-4%;

[0022] Cooling and holding stage (1150-1170℃), heating rate is 0.2-0.5℃ / min, CO concentration is 2%-3%;

[0023] Natural cooling stage: the furnace temperature is cooled to room temperature, and the cooling time is 20-24 hours.

[0024] The present application adjusts the atmosphere at different stages of firing to achieve firing under different environments such as oxidation, weak reduction and strong reduction, thereby obtaining the most stable crystallization effect; in the drying stage and the oxidative decomposition stage, the heating rate is relatively fast, and the firing temperature can be reached quickly to reduce energy efficiency. At the same time, in the low-temperature insulation stage and the high-temperature stage, the heating rate is relatively slow to ensure that the crystalline glaze grows fully and forms stable crystals, thereby improving its overall effects such as color; in the low-temperature insulation stage and the high-temperature stage, the CO concentration is controlled within different ranges, which can achieve reactions under weak reduction and strong reduction environments, forming a crystalline glaze effect with the required color, crystal size and distribution.

[0025] In summary, the present invention adopts a specific firing system, including different stages such as drying, oxidative decomposition, low-temperature insulation, high temperature and cooling insulation. At the same time, the CO concentration is controlled within a certain range to achieve firing regulation at different stages, promote the formation and growth of glaze crystals, and ensure better crystallization effect.

[0026] The beneficial effects of the present invention are:

[0027] 1. Use talc and bone ash as raw materials to promote crystallization. Add crystallizing agents to the raw materials to promote glaze crystallization and change the transparency, fluidity and glossiness of the glaze.

[0028] 2. Low-temperature oxidation, medium-temperature weak reduction, and high-temperature strong reduction firing are used to obtain a bright, rich green and yellow tea-leaf glaze color. Keeping the glaze at the highest temperature and cooling it down promotes glaze crystallization and stabilizes the glaze color.

[0029] 3. Add sodium metasilicate to the glaze slurry to reduce the surface tension of the glaze, improve the fluidity and viscosity of the glaze, reduce the shrinkage rate of the glaze, and prevent problems such as cracking and loosening of the glaze surface.

[0030] 4. The glaze is prepared using common natural mineral raw materials and chemical raw materials. There is no need to apply the glaze multiple times. It can be fired once, which simplifies the process, saves costs and firing time, and reduces energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a chromatographic analysis comparison chart of an embodiment of green and yellow tea-leaf glaze porcelain of the present invention and commercially available tea-leaf glaze porcelain. DETAILED DESCRIPTION

[0032] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only a portion of the embodiments of the present invention, rather than all of the embodiments. Therefore, all other embodiments derived by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0033] Example 1: A first mixed material was prepared by mixing quartz (15%), feldspar (38%), kaolin (7%), talc (15%), calcite (15%), ochre (5%), barium oxide (1%), and bone ash (0.5%). The specific chemical composition was as follows: Na₂O: 1.34%, MgO: 6.74%, Al₂O₃: 10.28%, SiO₂: 60.61%, K₂O: 6.15%, CaO: 8.09%, TiO₂: 0.07%, Fe₂O₃: 5.85%, and BaO: 1.14%. The first mixed material was prepared at a material:ball:water ratio of 1:1.5:0.8, then wet-milled in a ball mill for 10 hours. The mixture was then passed through a 100-mesh sieve to obtain a fine, uniform slurry.

[0034] Mix zinc oxide, quartz and ochre, grind them evenly in a mortar to a fineness of 100 mesh, and then continue to grind them to 60 mesh after high-temperature reduction calcination at 1330°C to obtain a crystallizer. Add 1% crystallizer to the slurry and stir evenly to obtain a green and yellow tea-leaf glaze. Add sodium metasilicate solution to the green and yellow tea-leaf glaze to adjust the glaze slurry concentration to a specific gravity of 1.3 at room temperature. Use a glazing clamp to pick up the blank and completely immerse the blank in the green and yellow tea-leaf glaze slurry so that the glaze slurry evenly covers the blank. Scrape off the glaze on the bottom of the blank. The glaze thickness is 1mm, and after natural drying in a ventilated place for 24 hours, the blank to be fired is obtained. Place the blank to be fired in a reduction kiln. The specific firing system is as follows:

[0035] Drying stage (kiln temperature -200°C), heating rate is 3°C / min;

[0036] Oxidative decomposition stage (200-850°C), heating rate is 7°C / min;

[0037] Low temperature holding stage (850-950℃), heating rate is 2℃ / min, CO concentration is 2%;

[0038] High temperature stage (950-1290℃), heating rate is 7℃ / min, CO concentration is 4%;

[0039] Cooling and holding stage (1150-1170°C), heating rate is 0.5°C / min, CO concentration is 3%;

[0040] Natural cooling stage: the furnace temperature is cooled to room temperature, and the cooling time is 24 hours.

[0041] The preparation technology of mixing appropriate amounts of zinc oxide, quartz, and ochre, sintering them at a certain temperature, forming a crystallizer, and then grinding them, is different from the conventional crystallizer preparation technology in that, firstly, conventional crystallizer raw materials usually only use one or several specific compounds, such as zinc oxide, quartz, etc., while the present application selects zinc oxide, quartz, ochre and other raw materials for mixing and using, and then prepares crystallizers of different compositions and properties through high-temperature sintering and grinding. Secondly, in the conventional crystallizer preparation technology, the sintering temperature and time are usually set according to empirical values, so it is difficult to ensure the consistency and stability of the sintering effect. In the crystalline glaze preparation technology of the present application, the temperature and time can be fine-tuned and controlled according to the properties and requirements of the specific raw materials, thereby ensuring the quality and performance of the crystallizer. The present application adjusts the atmosphere at different stages of firing to achieve firing under different environments such as oxidation, weak reduction and strong reduction, thereby obtaining the most stable crystallization effect; in the drying stage and the oxidative decomposition stage, the heating rate is relatively fast, and the firing temperature can be reached quickly to reduce energy efficiency. At the same time, in the low-temperature insulation stage and the high-temperature stage, the heating rate is relatively slow to ensure that the crystalline glaze grows fully and forms stable crystals, thereby improving its overall effects such as color; finally, in the low-temperature insulation stage and the high-temperature stage, the CO concentration is controlled within different ranges, which can achieve reactions under weak reduction and strong reduction environments, forming a crystalline glaze effect with the desired color, crystal size and distribution.

[0042] This application achieves superior performance of the crystallizer due to the diversity of raw materials used in preparing the crystallizer and the control of the sintering process, such as stability in a high-temperature environment, control of crystallization speed, and crystal size and distribution, which can provide a guarantee for subsequent stable display effects.

[0043] Example 2: A first mixed material is prepared by mixing quartz (18%), feldspar (35%), kaolin (10%), talc (10%), calcite (20%), ochre (3%), BaO (0.5%), and bone ash (1%) in proportions by mass. The specific chemical composition is as follows: Na₂O: 1.47%, MgO: 4.68%, Al₂O₃: 11.30%, SiO₂: 62.20%, K₂O: 5.83%, CaO: 10.99%, TiO₂: 0.07%, Fe₂O₃: 3.65%, and BaO: 0.58%.

[0044] The first mixed material was prepared at a mass ratio of material: ball: water of 1:1.5:1 and then placed in a ball mill for wet ball milling for 12 hours. After passing through a 100-mesh sieve, a fine and uniform slurry was obtained.

[0045] Mix zinc oxide, quartz and ochre, grind them evenly in a mortar to a fineness of 100 mesh, and then continue to grind them to 60 mesh after high-temperature reduction calcination at 1350°C to obtain a crystallizer. Add 1% by mass of the crystallizer to the slurry and stir evenly to obtain a green and yellow tea-leaf glaze. Add sodium metasilicate solution to the green and yellow tea-leaf glaze to adjust the glaze slurry concentration to a specific gravity of 1.4 at room temperature. Use a glazing clamp to pick up the blank and completely immerse the blank in the green and yellow tea-leaf glaze slurry so that the glaze slurry evenly covers the blank. Scrape off the glaze on the bottom of the blank. The glaze thickness is 0.8mm. After naturally drying in a ventilated place for 24 hours, the blank to be fired is obtained. The blank to be fired is placed in a reduction kiln. The specific firing system is as follows:

[0046] Drying stage (kiln temperature -200°C), heating rate is 2°C / min;

[0047] Oxidative decomposition stage (200-850°C), heating rate is 5°C / min;

[0048] Low temperature holding stage (850-950℃), heating rate is 1℃ / min, CO concentration is 1%;

[0049] High temperature stage (950-1310°C), heating rate is 5°C / min, CO concentration is 2%;

[0050] Cooling and holding stage (1150-1170°C), heating rate is 0.2°C / min, CO concentration is 2%;

[0051] Natural cooling stage: the furnace temperature is cooled to room temperature, and the cooling time is 20 hours.

[0052] Example 3: A first mixed material is prepared by mixing 38% feldspar, 15% quartz, 9% kaolin, 15% talc, 18% calcite, 34% Fe2O, 0.5% BaO, and 2% bone ash. The specific chemical composition is as follows: Na2O: 1.40%, MgO: 6.53%, Al2O3: 10.75%, SiO2: 60.25%, K2O: 5.94%, CaO: 10.17%, TiO2: 0.07%, Fe2O3: 4.54%, and BaO: 0.55%.

[0053] The first mixed material was prepared at a mass ratio of material: ball: water of 1:1.5:1 and then placed in a ball mill for wet ball milling for 12 hours. After passing through a 120-mesh sieve, a fine and uniform slurry was obtained.

[0054] Mix zinc oxide, quartz and ochre, grind them evenly in a mortar to a fineness of 100 mesh, and then continue to grind them to 60 mesh after high-temperature reduction calcination at 1350°C to obtain a crystallizer. Add 1% by mass of the crystallizer to the slurry and stir evenly to obtain a green and yellow tea-leaf glaze. Add sodium metasilicate solution to the green and yellow tea-leaf glaze to adjust the glaze slurry concentration to a specific gravity of 1.35 at room temperature. Use a glazing clamp to pick up the blank and completely immerse the blank in the glaze slurry of the green and yellow tea-leaf glaze so that the glaze slurry evenly covers the blank. Scrape off the glaze on the bottom of the blank. The glaze thickness is 0.9mm. After natural drying in a ventilated place for 24 hours, the blank to be fired is obtained. The blank to be fired is placed in a reduction kiln. The specific firing system is as follows: drying stage (kiln temperature -200°C), heating rate is 2.5°C / min;

[0055] Oxidative decomposition stage (200-850°C), heating rate is 6°C / min;

[0056] Low temperature holding stage (850-950°C), heating rate is 1.5°C / min, CO concentration is 1.5%;

[0057] High temperature stage (950-1300°C), heating rate is 6°C / min, CO concentration is 3.5%;

[0058] Cooling and holding stage (1150-1170°C), heating rate is 0.3°C / min, CO concentration is 2.5%;

[0059] Natural cooling stage: the furnace temperature is cooled to room temperature, and the cooling time is 24 hours.

[0060] The green and yellow tea-leaf glaze porcelain prepared by the present invention is tested for product performance using a Japan Denshoku NF-333 portable spectrocolorimeter.

[0061] Table 1 is a chromatographic analysis comparison table of Examples 1-3 and common tea-leaf glaze products on the market:

[0062]

[0063] The green and yellow mixed color of the tea powder glaze is a mixture of green and yellow wavelengths, making the overall color tone more soft and natural. Compared with the common tea powder glaze porcelain product in the market, the green and yellow mixed color tea powder glaze porcelain has certain advantages in color saturation and wavelength peak. Specifically, in terms of saturation, the green and yellow mixed color tea powder glaze provided by the application is more stable than the common tea powder glaze in the market and is not prone to color change; in terms of wavelength peak, the green and yellow mixed color tea powder glaze has a shorter wavelength peak and better physical and chemical properties. The green and yellow mixed color tea powder glaze porcelain prepared by the application has a smooth glaze surface and a yellow-green color that is opaque, and on the dark green background, it appears like yellow-brown fine points of tea powder, with a smooth and delicate touch, a deep and solemn color, and a thick ancient flavor. The glaze formula has strong compatibility with the common clay or porcelain clay in the market, and can easily avoid defects such as glaze cracking caused by the expansion coefficient of the body and glaze.

Claims

1. A green and yellow tea-leaf glaze porcelain, characterized in that: The invention comprises a body and a green-yellow tea-leaf glaze. The preparation method of the green-yellow tea-leaf glaze comprises the following steps: mixing 15-20% of quartz, 35-40% of feldspar, 5-10% of kaolin, 10-15% of talc, 15-20% of calcite, 3-5% of ochre, 0.5-1% of barium oxide, and 0.5-2% of bone ash to obtain a first mixed material; then mixing the first mixed material, grinding balls, and water in a mass ratio of material: balls: water of 1:1.5-2:0.8-1; and adding the mixture into a ball mill and grinding for 10-12 hours. The mixture is then sieved to obtain a slurry, 1-2% of a crystallizing agent is added to the slurry and uniformly stirred to obtain a green and yellow tea-leaf glaze slurry, wherein the crystallizing agent is prepared by mixing zinc oxide, quartz, and ochre, grinding the mixture to a fineness of 100-120 mesh, calcining the mixture at 1330-1350° C., and then further grinding the mixture to a fineness of 60-80 mesh; glazing the surface of the green body, scraping off the glaze slurry on the bottom of the green body after glazing, and drying the green body to be fired, placing the green body to be fired in a kiln, and firing the green body at 1280-1310° C. in a reducing atmosphere. The firing method comprises: Drying stage: kiln temperature -200℃, heating rate 2-3℃ / min; Oxidation decomposition stage: 200-850℃, heating rate 5-7℃ / min; Low temperature holding stage: 850-950℃, heating rate of 1-2℃ / min, CO concentration of 1%-2%; High temperature stage: 950-1310℃, heating rate of 5-7℃ / min, CO concentration of 2%-4%; Cooling and holding stage: 1150-1170℃, heating rate 0.2-0.5℃ / min, CO concentration 2%-3%; Natural cooling stage: the furnace temperature is cooled to room temperature, and the cooling time is 20-24 hours; The result is green and yellow tea-leaf glaze porcelain.

2. The green and yellow tea-leaf glaze porcelain according to claim 1, characterized in that: The method for glazing the surface of the green body comprises: adding sodium metasilicate solution into the glaze slurry to adjust the concentration of the glaze slurry, and then completely immersing the green body into the glaze slurry, wherein the glazing thickness is 0.8-1.0 mm.

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