Calcium-rich and aluminum-rich frit for Ru porcelain glaze as well as preparation method and application of calcium-rich and aluminum-rich frit
By designing calcium- and aluminum-rich frits and combining them with water quenching and ball milling processes, the narrow firing range and high energy consumption of Ru porcelain glaze were solved, enabling industrialized production with stable glaze color and low energy consumption.
Patent Information
- Application Number
- CN202511131133.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-13
- Publication Date
- 2025-11-28
AI Technical Summary
Traditional Ru ware glazes are fired at low temperatures and have a high aluminum and calcium content, resulting in large variations in glaze viscosity, a narrow firing range, and high energy consumption, making it difficult to achieve large-scale and stable production.
Using calcium- and aluminum-rich frits, and designed using the CaO-Al2O3-SiO2 ternary phase diagram, the ingredients are prepared near the eutectic point of 1265℃ to form a flowable high-temperature melt, reducing energy consumption and melting at a lower temperature. Combined with water quenching and ball milling processes, frits suitable for Ru porcelain glaze are prepared.
This technology enables Ru porcelain glaze to melt at lower temperatures, reducing energy consumption, expanding the firing range, ensuring stable glaze color, and making it suitable for industrial production.
Smart Images
Figure CN121020985A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of ceramic materials and production processes, and particularly relates to a calcium-rich and aluminum-rich frit for Ru porcelain glaze as well as a preparation method and application thereof. BACKGROUND
[0002] Ru kiln is the first of the five famous kilns in the Song Dynasty, and products thereof are famous for the sky blue color, and are also an important pillar of the present Henan ceramic industry. Calcium-rich and aluminum-rich in the traditional Ru porcelain glaze layer are introduced in the form of raw materials, and when the glaze is fired at 1140-1200 DEG C, the viscosity and liquid phase amount of the glaze will suddenly change due to high calcium and high aluminum, which hinders the discharge of CO2 gas in the glaze layer, and C produced by the cracking of CO2 at high temperature gathers in the glaze layer, so that the glaze is prone to staining; the sudden change of the liquid phase amount also makes the firing range of the glaze narrow, and a slight change in the kiln temperature can cause the glaze color to change. These problems are also the bottleneck restricting the current industrial scale and stable development. At present, the firing temperature of Ru porcelain produced in Henan is about 1170 DEG C, and some are even lower, only 1140 DEG C. Due to the low firing temperature and high aluminum and high calcium composition, more energy is needed to open the stable structure of the crystal in the raw material glaze, and then the melting reaction is carried out; secondly, the chemical composition of the Ru porcelain glaze falls in the anorthite crystallization region of the CaO-Al2O3-SiO2 ternary phase diagram, and the isotherm in this composition range is dense, and the liquid phase will rapidly increase at a certain temperature range, which will make the glaze only in a narrow temperature range to achieve good melting effect, which is not conducive to the industrial scale and stable production. SUMMARY
[0003] The purpose of the present application is to provide a calcium-rich and aluminum-rich frit for Ru porcelain glaze as well as a preparation method and application thereof.
[0004] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows: A calcium-rich and aluminum-rich frit for Ru porcelain glaze is composed of the following raw materials in parts by weight: 15 parts of potassium feldspar, 23 parts of calcite, 27 parts of wollastonite, 12.5 parts of aluminum oxide powder, 5 parts of quartz, and 4 parts of sodium fluoride; the ingredients are designed according to the composition near the low eutectic point of 1265 DEG C in the CaO-Al2O3-SiO2 ternary phase diagram, so that the ingredients can completely melt at a lower temperature to form a flowable high-temperature melt. Since the energy required for the melting of the frit in the glaze is much smaller than the energy required for breaking the crystal bonds in the raw material, the liquid phase can be formed in a shorter time, and the quartz and clay and other substances are melted, so that the chemical reaction of the glaze layer proceeds smoothly.
[0005] Further, the chemical composition of the frit is: 41.70wt.% SiO2, 19.96wt.% Al2O3, 35.37wt.% CaO, 1.60wt.% K2O, 1.37wt.% Na2O; the frit commonly used in general building ceramics and daily ceramics is generally high in silicon, low in aluminum and calcium, and the chemical composition is mostly SiO2≥55wt.%, Al2O3<15wt.% (some less than 5%), CaO≤20wt.%, and the melting temperature of these frits is relatively high, generally above 1400℃, and some as high as 1500℃, so that the frit has good fluidity, and the yield of the frit is relatively large. For example, the commonly used frit 1 (frit formula used by Jianyi and Nobel Ceramics): 57.96wt.% SiO2, 13.71wt.% Al2O3, 6.5wt.% CaO, 2.44wt.% K2O, 2.66wt.% Na2O, 6.25wt.% MgO, 0.3% ZnO, 3.05% CaF, 6.87% BaO. Compared with the high-calcium and high-aluminum frit of the present application, it is more suitable for the high-aluminum and high-calcium composition of Ru porcelain glaze, and the frit is completely melted at a firing temperature of 1280℃, and the yield is more than 90%, and compared with the conventional frit, the energy consumption required for melting is lower.
[0006] Another object of the present application is to provide a preparation method of a calcium-rich and aluminum-rich frit for Ru porcelain glaze, comprising the following steps: S1. Mixing: the raw materials are added to the mixer according to the mixing ratio of the frit, and dry mixing is carried out for 3-5 times, and after each mixing, the mixture is sieved through a 200 mesh sieve, and the mixture is mixed uniformly to obtain a mixture; S2. Melting: the mixture in step S1 is placed in a corundum crucible and placed in an electric furnace, and melted at 1280℃ for 5h, and kept for 30min to obtain a melt; S3. Water quenching: after the heat preservation is completed, the kiln door is opened, and the melt in step S2 is poured into 25℃ water, and after cooling, a granular frit is obtained, and the frit is dried to obtain a dry frit. The purpose of water quenching is to ensure the high-temperature amorphous structure of the frit, prevent the growth of calcium feldspar crystals in the frit structure during natural cooling, and break the valence bond of the crystals during high-temperature firing. Additional heat and time are required to break the valence bond; on the other hand, the high-temperature frit has fluidity, and when poured into normal temperature water, it can be naturally broken into smaller particles, and the particles have more cracks, and compared with the naturally cooled frit, it is easier to break, making the ball milling process easier; S4. Ball milling: the dry frit obtained in step S3 is ball milled for standby use.
[0007] Still another object of the present application is to provide an application of a calcium-rich and aluminum-rich frit for Ru porcelain glaze, which is used to prepare a Ru porcelain series blue glaze by mixing the frit with potassium feldspar, iron oxide and gneiss; the composition of the blue glaze is: 30-50 parts of the calcium-rich and aluminum-rich frit, 40-60 parts of potassium feldspar, 4-10 parts of gneiss, and 0-1 part of iron oxide.
[0008] Furthermore, the potassium feldspar contains 7 wt.% K2O and less than 0.5 wt.% iron. Since the chemical composition of potassium feldspar varies from region to region, K2O, SiO2, and Al2O3 are three main indicator components. Adding potassium feldspar with different compositions to the glaze in the same proportion will lead to deviations in the final glaze's chemical composition, thus altering the glaze's characteristics and color. The gneiss contains approximately 10 wt.% CaO, 9 wt.% MgO, and 9 wt.% Fe2O3. The gneiss used in this invention is from the Pingdingshan area. Gneiss is a metamorphic rock, and due to metamorphism, its chemical composition fluctuates significantly. CaO, MgO, and Fe2O3 are three main indicator components, especially Fe2O3, whose content directly affects the glaze's color.
[0009] Furthermore, the firing process of the celadon glaze includes the following steps: (1) Ingredients: The ingredients are prepared based on the results of the energy dispersive X-ray fluorescence spectrum of the glaze to be fired. Here, the Ru ware unearthed from the Qingliangsi site is used as an example. Figure 1 The ingredients were formulated based on the results of the energy dispersive X-ray fluorescence spectrum of the glaze. The glaze of this porcelain shard has a typical sky-blue appearance, semi-gloss, and sparse bubbles. Using the X-ray fluorescence spectrum results of this glaze as the basis for glaze formulation ensures that the chemical composition of the formulated glaze is consistent with it and can be distinguished from other celadon glazes, such as Yaozhou celadon, Yingqing glaze, and Meiziqing glaze, ensuring that the ingredient composition is the basic glaze of Ru ware. The color parameters of the glaze are shown in Table 1. The X-ray fluorescence spectrum results of the porcelain glazes unearthed from the site are not completely consistent in chemical composition. The SiO2 content varies in the range of 55wt.%-63wt.%, the CaO content varies in the range of 10wt.%-17wt.%, and the Fe2O3 content varies in the range of 0.5wt.%-2.5wt.%. Different ingredient compositions present different colors. Based on the X-ray fluorescence spectrum results, calcium-rich and aluminum-rich frit, potassium feldspar, gneiss, and iron oxide were added respectively. In ceramics, L*a*b* is often used to represent color, where L* represents the brightness of the ceramic, a positive value of a* represents red, a negative value of a* represents green, a positive value of b* represents blue, and a negative value of b* represents yellow.
[0010] (2) Ball milling: with a material:ball:water ratio of 1:2:0.6, ball milling speed of 300 r / min, ball milling for 20 minutes, and adding 0.3wt.% sodium silicate for wet milling to obtain glaze slurry; (3) Sieving and glazing: Sieving the glaze slurry through a 200-mesh sieve, and providing strength and water absorption by once biscuit firing at 900°C, and glazing with a thickness of 0.5 mm-1.0 mm and then drying; (4) Firing: placing the dried and glazed body obtained in step (3) into a kiln, the maximum firing temperature is 1210°C, and the total firing time is 9 h, and the temperature is converted into a reducing atmosphere at 980°C-1020°C, and when the maximum firing temperature is reached, the kiln door is opened, and the temperature is rapidly cooled to 1040°C, the kiln door is closed, and natural cooling is performed; the temperature from normal temperature to 980°C belongs to oxidation firing, and the organic matter and water in the body and glaze are rapidly discharged; the temperature is converted into a reducing atmosphere at 980°C, and reduction firing is started, and the opening of the air valve is adjusted to be small, so that the gas is not completely combusted, and preparation is made for the reduction of iron oxide; the temperature of 980°C-1210°C is mainly for the melting of the glaze and the reduction of iron oxide, and is an important stage for coloration; the maximum temperature is kept for 10 min, so as to flatten the temperature inside the kiln and make the feldspar crystals in the glaze layer grow, and a semi-glossy glaze surface is formed; the kiln is opened and rapidly cooled to 1040°C, so as to rapidly reduce the temperature, prevent the feldspar crystals from growing too large and causing the glaze surface to be rough, and at the same time, 1040°C is still the temperature for the growth of feldspar crystals, but at this temperature, the crystals will not be too large, and the glaze surface will be more oily.
[0011] Further, in step (4), the firing time before the conversion into a reducing atmosphere is 4 h, and the reduction stage is 5 h; the coloration mechanism of the Ru porcelain glaze is the coloration of divalent iron ions in a reduced state and the coloration of a separate phase structure, and the organic matter and water in the body and glaze need to be discharged in a completely oxidized state, so as to avoid causing carbon deposition and smoke absorption defects, and causing the glaze surface to be stained; according to the long-term firing mode, 4 h of oxidation stage can completely discharge the organic matter and water; 5 h of reduction stage can make the reduction of iron oxide more perfect, and a blue glaze with a cyan tone can be fired; the longer the reduction time, the more obvious the cyan tone of the glaze.
[0012] The advantages of this invention are as follows: This invention achieves a narrow firing range for Ru ware glaze during firing by designing a liquid phase gradient generation method. A portion of the high-alumina and high-calcium components are introduced into the frit, while some Al2O3 and CaO are retained and introduced into the glaze as raw materials. Since the high-alumina and high-calcium frit only needs to reach the corresponding temperature to melt during glaze firing, it does not require opening the stable crystal structure first. The liquid phase in the glaze layer is generated by the melting of the frit first, reducing the viscosity of the glaze layer and allowing the CO2 produced by carbonate decomposition to be smoothly discharged. This improves the melting of quartz, feldspar, and calcite raw materials. When the temperature reaches a higher level, the crystal structure in the raw materials is opened, and the second-stage liquid phase begins to appear. The frit formulation is designed with the composition near the eutectic point of 1265℃ in the CaO-Al2O3-SiO2 ternary phase diagram, enabling the formulation to completely melt at a lower temperature, forming a flowable high-temperature melt. Since the energy required for the frit to melt in the glaze is much less than the energy required to break the bonds in the crystals in the raw material, a liquid phase can be formed in a shorter time, melting quartz and clay and other substances, allowing the chemical reaction of the glaze to proceed slowly. Attached Figure Description
[0013] Figure 1 This is a photograph of the glaze characteristics of the ancient porcelain shards of this invention.
[0014] Figure 2 This is a photograph of the appearance of a sample of the glaze fired in Example 1.
[0015] Figure 3 These are scanning electron microscope (SEM) images of the glaze layer of the sample in Example 1, where a: 500x; b: 5000x; c: 5000x; d: 20000x.
[0016] Figure 4 This is a high-temperature microscope image of the sample from Example 1.
[0017] Figure 5 These are high-temperature microscope images of traditional Ru ware glaze.
[0018] Figure 6 This is a photograph of the appearance of a sample of the glaze fired in Example 2.
[0019] Figure 7 These are scanning electron microscope (SEM) images of the glaze layer of the sample in Example 2, where a: 500x; b: 5000x; c: 5000x; d: 20000x.
[0020] Figure 8 This is a high-temperature microscope image of the sample from Example 2. Detailed Implementation Example
[0021] A calcium- and aluminum-rich frit for Ru porcelain glaze is composed of the following raw materials in parts by weight: 15 parts potassium feldspar, 23 parts calcite, 27 parts wollastonite, 12.5 parts alumina powder, 5 parts quartz, and 4 parts sodium fluoride; the chemical composition of the frit is: 41.70 wt.% SiO2, 19.96 wt.% Al2O3, 35.37 wt.% CaO, 1.60 wt.% K2O, and 1.37 wt.% Na2O.
[0022] A method for preparing calcium- and aluminum-rich frit for Ru ware glaze includes the following steps: S1. Mixing: Add the raw materials to the mixer according to the proportion of the frit and mix dry 3-5 times. After each mixing, pass the mixture through a 200-mesh sieve to obtain the batch material. S2. Melting: Place the batch material from step S1 into a corundum crucible, place it in an electric furnace, and melt it at 1280℃ for 5 hours, then hold it for 30 minutes to obtain the melt. S3. Water quenching: After the heat preservation is completed, open the kiln door and pour the melt from step S2 into 25°C water. After cooling, granular melt is obtained and dried to obtain dry melt. S4. Ball milling: The dry melt obtained in step S3 is ball milled for later use.
[0023] Application Example 1 like Figures 1-5 As shown, a Ru ware celadon glaze is prepared with the following ingredients: 39 wt.% frit, 55 wt.% potassium feldspar, 5.5 wt.% gneiss, and 0.5 wt.% iron oxide. The weighed materials are poured into a ball mill jar, and 60 g of water is added at a material-to-water ratio of 1:0.6, along with 0.1 wt.% diluent (sodium silicate) to ensure the glaze has fluidity at a low moisture content, facilitating glazing. The ball mill speed is 300 r / min, and the milling time is 30 min. The unglazed body uses traditional Ru ware blanks (cups), which turn a light gray color after firing. After the glaze slurry is ground, it is applied using a dip-glazing method. After glazing, the weight gain of the body is controlled at approximately 50 wt.%, ensuring a glaze layer thickness of approximately 0.6 mm. Glazing is done in a single step, unlike the traditional method of dip-glazing followed by blowing. The glazed body is dried until the moisture content is below 2 wt.% before firing in a kiln with a volume of 0.5 m³. 3The firing process is as follows: from room temperature to 980℃, the heating time is 4 hours, the pressure gauge is 0.001, the damper is fully open, and the chimney damper is fully open; at 980℃, the atmosphere is switched to reducing atmosphere, the pressure gauge is adjusted to 0.012, the damper is opened to 1 / 4, the heating time from 980℃ to 1190℃ is 5 hours, the pressure gauge remains unchanged, at 1180℃, the chimney damper is pushed inward by 1cm to increase the chimney draft, and at the same time, the reducing atmosphere is slightly increased; at 1190℃, the temperature is held for 5 minutes to equalize the temperature difference in various parts of the kiln; during the cooling stage from 1190℃ to 950℃, a rapid cooling method is adopted, that is, the kiln door is opened to quickly cool down, the kiln door opening is about 30°, so that the glaze surface is rapidly cooled to present a better glassy texture; after the kiln temperature drops to 950℃, the kiln door is closed and the kiln is allowed to cool naturally.
[0024] The appearance of the sample is as follows Figure 2 As shown in Table 2, the colorimetric parameters of the samples were tested using a colorimeter. The microstructure of the glaze layer was analyzed using a scanning electron microscope. Figure 3 As shown. The characteristic temperatures of the samples were tested using a high-temperature point sintering apparatus, such as... Figure 4 As shown.
[0025] Scanning electron microscopes at 5000x and 20000x magnification show plate-like anorthite crystals, either singly or in clusters. The glaze matrix contains droplet-like phase separation structures, which are relatively uniformly distributed. The average size of the phase separation structures is around 100nm, with most being less than 100nm. The droplet-like phase separation structures produce Rayleigh scattering of light, forming a bluish glaze surface. After reduction firing, iron oxide exists as ferrous ions in the glaze structure. Together, they form the bluish-green color of Ru ware glaze. The size and number of anorthite crystals and bubbles in the glaze layer affect the gloss of the glaze surface, giving it an oily appearance.
[0026] The melting temperature range of traditional Ru porcelain glaze and Ru porcelain glaze added with high-aluminum and high-calcium frit was compared. Four characteristic temperature points were tested, namely softening temperature (DT), spherical temperature (ST), hemispherical temperature (HT) and flowing temperature (FT). The firing range of general domestic porcelain, artistic porcelain and architectural porcelain is often selected between HT and FT, in which the glaze can be perfectly fused and adhered to the body. However, the firing temperature of Ru porcelain glaze is usually lower, generally less than 1220℃, far from reaching the HT temperature line. If the firing temperature is also selected between HT and FT, the color and characteristics of Ru porcelain glaze will change seriously, which does not have the characteristics of a classic artifact. The firing temperature of Song Dynasty Ru porcelain glaze is about 1200℃, which is between the DT and ST of modern traditional Ru porcelain glaze. However, the DT of modern Ru porcelain glaze is lower, about 28℃ lower than 1200℃. In this temperature range, the amount of liquid phase is larger, and the bubble size and morphology of the glaze layer structure will change, thereby causing color change. After adding calcium-rich and aluminum-rich frit, the DT of the sample moves to a higher temperature, about 1201.5℃, which is basically consistent with the maximum firing temperature of the kiln, and the color change caused by the change of liquid phase during heating is avoided.
[0027] Application Example 2 As shown in Figures 5-8 A Ru porcelain blue glaze, the ingredients are: 44wt.% frit, 50wt.% potassium feldspar, 5wt.% dolomite, 1.0wt.% iron oxide. Weigh the materials into a ball mill tank, add 70g water according to the material-water mass ratio of 1:0.7, and add 0.2wt.% diluent (sodium silicate) to make the glaze have fluidity at a lower water content, which is convenient for glazing; the speed of the ball mill is 300r / min, and the ball milling time is 30min. The body adopts traditional Ru porcelain body (cup), which is gray after firing. After the glaze slurry is ground, it is applied by spraying. After glazing, the mass increment of the body is controlled at about 60wt.%, which ensures the thickness of the glaze layer to be about 0.7mm, and the glazing is done once. Dry the glazed body to a water content of less than 2wt.%, and load it into the kiln for firing. The volume of the kiln is 0.5m 3The firing process is as follows: from room temperature to 980℃, the heating time is 4 hours, the pressure gauge is 0.001, the damper is fully open, and the chimney damper is fully open; at 980℃, the atmosphere is switched to reducing atmosphere, the pressure gauge is adjusted to 0.012, the damper is opened to 1 / 4, the heating time from 980℃ to 1200℃ is 5 hours, the pressure gauge remains unchanged, at 1180℃, the chimney damper is pushed inward by 1cm to increase the chimney draft, and at the same time, the reducing atmosphere is slightly increased; at 1200℃, the temperature is held for 10 minutes to equalize the temperature difference in various parts of the kiln; during the cooling stage from 1200℃ to 1040℃, a rapid cooling method is adopted, that is, the kiln door is opened to quickly cool down, the kiln door opening is about 30°, so that the glaze surface is rapidly cooled to present a better glassy texture; after the kiln temperature drops to 1040℃, the kiln door is closed and the kiln is allowed to cool naturally.
[0028] The appearance of the sample is as follows Figure 6 As shown in Table 3, the colorimetric parameters of the samples were tested using a colorimeter. The microstructure of the glaze layer was analyzed using a scanning electron microscope. Figure 7 As shown. The characteristic temperatures of the samples were tested using a high-temperature point sintering apparatus, such as... Figure 8 As shown.
[0029] SEM images at 5000x and 20000x magnification show plate-like and columnar anorthite crystals with less clustering, likely due to higher firing temperatures and increased fluxing agents in the glaze. The droplet-like phase separation structure of the glaze's glass matrix is difficult to observe; instead, a continuous, sponge-like phase separation structure is visible. At 20000x magnification, extremely fine, round phase separation droplets, only a few nanometers in size, are observed, exhibiting stronger Rayleigh scattering and a deeper blue hue on the glaze surface. Simultaneously, the increased firing temperature causes the glaze to begin to show a glossy appearance.
[0030] The melting temperature range of Ru porcelain glaze with high alumina and high calcium frit was analyzed. Four characteristic temperature points were tested, namely softening temperature (DT), spherical temperature (ST), hemispherical temperature (HT) and flowing temperature (FT). The firing range of general domestic porcelain, art porcelain and building porcelain is usually selected between HT and FT, in which the glaze can melt and adhere to the body perfectly. However, the firing temperature of Ru porcelain glaze is usually lower than 1220 ℃, far from the HT temperature line. If the firing temperature is also selected between HT and FT, the color and characteristics of Ru porcelain glaze will change seriously, which does not have the characteristics of the classic works. The firing temperature of Song Dynasty Ru porcelain glaze is about 1200 ℃, which is between the DT and ST of modern traditional Ru porcelain glaze. The DT of modern traditional Ru porcelain glaze is lower, about 28 ℃ lower than 1200 ℃. In this temperature range, the amount of liquid phase is larger, and the bubble size and crystal size and morphology of the glaze layer structure will change, which will cause the color change. After adding calcium and aluminum rich frit, the DT of the sample moves to high temperature, about 1196.0 ℃, which is close to the maximum firing temperature of the kiln, only 4 ℃ difference, which will not cause color change due to the change of liquid phase during heating.
Claims
1. A calcium- and aluminum-rich frit for Ru ware glaze, characterized in that: It is composed of the following raw materials in parts by weight: 15 parts potassium feldspar, 23 parts calcite, 27 parts wollastonite, 12.5 parts alumina powder, 5 parts quartz, and 4 parts sodium fluoride.
2. The calcium- and aluminum-rich frit for Ru ware glaze as described in claim 1, characterized in that, The chemical composition of the fused block is: 41.70 wt.% SiO2, 19.96 wt.% Al2O3, 35.37 wt.% CaO, 1.60 wt.% K2O, and 1.37 wt.% Na2O.
3. The method for preparing calcium-rich and aluminum-rich frit for Ru ware glaze as described in any one of claims 1-2, characterized in that, Includes the following steps: S1. Mixing: Add the raw materials to the mixer according to the proportion of the frit and mix dry 3-5 times. After each mixing, pass the mixture through a 200-mesh sieve to obtain the batch material. S2. Melting: Place the batch material from step S1 into a corundum crucible, place it in an electric furnace, and melt it at 1280℃ for 5 h, then hold it for 30 min to obtain the melt. S3. Water quenching: After the heat preservation is completed, open the kiln door and pour the melt from step S2 into 25°C water. After cooling, granular melt is obtained and dried to obtain dry melt. S4. Ball milling: The dry melt obtained in step S3 is ball milled for later use.
4. The application of the calcium-rich and aluminum-rich frit for Ru ware glaze as described in any one of claims 1-2, characterized in that: Ru porcelain series celadon glaze is prepared by mixing frit, potassium feldspar, iron oxide and gneiss; the composition of celadon glaze is: 20-30 parts calcium-rich and aluminum-rich frit, 35-45 parts potassium feldspar, 4-10 parts gneiss and 0-0.5 parts iron oxide.
5. The application as described in claim 4, characterized in that: The potassium feldspar contains 7 wt.% K2O and less than 0.5 wt.% iron; the gneiss contains approximately 10 wt.% CaO, 9 wt.% MgO, and 9 wt.% Fe2O3.
6. The application as described in claim 5, characterized in that: The firing process of the celadon glaze includes the following steps: (1) Ingredient preparation: The ingredients are prepared based on the results of the energy dispersive X-ray fluorescence spectrum of the glaze to be fired; (2) Ball milling: with a material:ball:water ratio of 1:2:0.6, ball milling speed of 300 r / min, ball milling for 20 minutes, and adding 0.3wt.% sodium silicate for wet milling to obtain glaze slurry; (3) Sieving and glazing: The glaze slurry is sieved through a 200-mesh sieve, the body is bisque-fired once at 900℃, and the glaze thickness is 0.5 mm-1.0 mm before drying; (4) Firing: Place the dried glazed body obtained in step (3) into the kiln. The maximum firing temperature is 1210℃. Firing takes 9 hours. The atmosphere is reduced between 980℃ and 1020℃. When the maximum firing temperature is reached, keep it at that temperature for 10 minutes. Open the kiln door and cool it rapidly to 1040℃. Close the kiln door and let it cool naturally.
7. The application as described in claim 6, characterized in that: In step (4), the firing time before switching to a reducing atmosphere is 4 hours, and the reduction stage is 5 hours.