Multi-color purple sand pottery printing layering-free fusion firing process based on special mineral materials

Abstract

The invention relates to the technical field of fusion firing processes, in particular to a multi-color purple sand pottery printing layering-free fusion firing process based on a special mineral material, which comprises the following steps: a raw material pretreatment step: crushing colorful purple sand raw ore, removing impurities, and screening to 200 meshes to obtain colorful purple sand raw ore pug; the special mineral material is finely ground and screened to 500 meshes, and the superfine special mineral material is obtained; and a precise mixing step. According to the invention, special mineral materials and colorful purple sand raw ore pug are scientifically proportioned, so that the shrinkage ratio difference of purple sand pug with different colors in the firing process is adjusted, the internal stress concentration of a green body is reduced, the phenomena of layering and cracking in the firing process are reduced, and the yield is increased; through the control steps of stepped drying, segmented heating firing, gradient cooling and the like, uniform removal of moisture in the green body and effective release of stress are ensured, and the texture stability and color uniformity of the multicolor purple sand ceramic seal are improved.

Description

Technical Field

[0001] This invention relates to the field of fusion firing technology, and in particular to a non-layered fusion firing process for multi-color purple clay seals based on special mineral materials. Background Technology

[0002] As a traditional handicraft with both artistic value and cultural connotation, the color presentation and texture stability of Zisha pottery seals are the core quality indicators. Karamay's colorful Zisha raw ore naturally contains a variety of basic colors such as red, purple, blue, yellow, and brown, making it a high-quality regional resource for preparing multi-colored Zisha pottery seals. However, due to the limitations of firing technology, this resource has not been effectively developed and utilized for a long time.

[0003] Currently, the firing of multi-colored Zisha pottery seals adopts traditional techniques without unified standards and systematic technical systems. Traditional clay processing techniques generally use natural Zisha raw ore clay directly. When making multi-colored pottery seals, different colored clays are simply mixed or spliced. Some processes involve simple crushing and screening with low precision, which cannot optimize the particle structure and creates hidden dangers for firing quality. Traditional body drying techniques mainly rely on natural drying or single constant temperature drying. Traditional drying techniques rely on natural drying, which is environmentally dependent, has a long and unstable cycle, and is prone to creating hidden stress. It is difficult to completely remove deep moisture, and the stress cannot be effectively released, resulting in an unstable internal structure of the green body. Traditional firing core technology adopts extensive temperature control without scientific segmented heating design. The temperature is raised directly from room temperature to the final firing temperature at an arbitrary rate, without considering the needs of changes in the clay. There is no unified standard for the final firing temperature, which is set based on experience. There is a lack of heat preservation. Cooling is generally done naturally, and the sudden drop in temperature increases the probability of cracking and deformation. Traditional production and quality control technologies lack clear and standardized process parameter combinations, relying entirely on operator experience and lacking quantitative indicators. Subsequent production lacks dedicated quality inspection processes, resulting in low yield rates and inconsistent quality. Finished products exhibit poor color reproduction, low surface hardness, and high quality loss rates, making it difficult to meet demands and lacking regional characteristics and artistic appeal. Summary of the Invention

[0004] The purpose of this invention is to solve the problems of low yield, unstable quality, unnatural color fusion, and lack of standardized process parameters in the firing of multi-color purple clay pottery seals in the prior art. Therefore, this invention proposes a non-layered fusion firing process for multi-color purple clay pottery seals based on special mineral materials.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A non-layered fusion firing process for multi-colored purple clay seals based on special mineral materials, with the following raw material pretreatment steps: The five-colored purple clay ore is crushed, impurities are removed, and it is sieved to 200 mesh to obtain five-colored purple clay ore material; Special mineral materials are finely ground and sieved to 500 mesh to obtain ultrafine special mineral materials; Precise mixing steps: The five-colored purple clay raw material 97 parts by weight and the ultrafine special mineral material 3 parts by weight are thoroughly mixed and stirred to obtain composite purple clay material; Blank forming steps: The composite purple clay material is shaped or carved to form a multi-colored purple clay seal blank. Step-by-step drying process: The multicolored purple clay seal blanks were dried at 40°C for 12 hours and at 60°C for 24 hours in sequence to remove internal moisture and release latent stress. Segmented heating and firing steps: The dried green body is placed in the kiln and fired according to the following heating procedure: 0~300℃, heating rate is 2℃ / min; 300~500℃, heating rate is 4℃ / min; 500~800℃, heating rate is 3℃ / min; Constant temperature insulation steps: Once the firing temperature reaches 800℃, a heat preservation treatment is performed for 1.5 hours. Gradient cooling steps: When the temperature is above 500℃, cool down at a rate of 2℃ / min; When the temperature is below or equal to 500℃, allow it to cool naturally to room temperature. Finished product inspection steps: Quality testing was conducted on the cooled multi-colored purple clay pottery seals to obtain finished multi-colored purple clay pottery seals that were free of layering and cracking, and whose colors were naturally blended.

[0006] Preferably, the weight ratio of the five-colored purple clay ore to the special mineral material is 96-98 parts: 2-4 parts.

[0007] Preferably, the particle size of the five-colored purple clay raw ore is 180-220 mesh, and the particle size of the special mineral material is 450-600 mesh.

[0008] Preferably, the ultrafine special mineral material is a layered silicate mineral or its composite with a low expansion coefficient that has been processed by a specific process. The main functional components of the ultrafine special mineral material are hydrated oxides of silicon, aluminum, and magnesium. The special mineral material is used to adjust the shrinkage ratio difference of different colored purple clay materials during the firing process, so as to reduce the stress concentration inside the body during the firing process.

[0009] Preferably, the mixing step employs mechanical stirring or repeated manual kneading to ensure that the special mineral material is evenly dispersed in the gaps between the particles of the five-colored purple clay ore.

[0010] Preferably, the drying temperature range of the stepped drying step is 30 to 70°C, and the total drying time is 30 to 48 hours.

[0011] Preferably, in the segmented heating and firing step, the heating rate of each stage is allowed to fluctuate within the range of ±0.5℃ / min.

[0012] Preferably, the final firing temperature is 780–820°C, and the holding time for the constant temperature holding step is 1–2 hours.

[0013] Preferably, in the gradient cooling step, the cooling rate at the stage above 500°C is 1.5 to 2.5°C / min.

[0014] Preferably, the multi-colored purple clay pottery seals obtained by the above process have at least one of the following performance indicators: color uniformity ≥90%; surface hardness ≥7H; no delamination or obvious cracks after firing.

[0015] Compared with the prior art, the present invention has the following advantages: 1. This invention uses special mineral materials and multicolored purple clay raw materials in a scientific ratio to adjust the shrinkage ratio difference of different colored purple clay materials during the firing process, reduce the internal stress concentration of the body, reduce the delamination and cracking phenomena that occur during the firing process, and improve the yield. Through step-by-step drying, segmented heating and firing and gradient cooling, the invention ensures the uniform removal of moisture and effective release of stress inside the body, thereby improving the texture stability and color uniformity of multicolored purple clay seals.

[0016] 2. This invention employs refined pretreatment of raw materials, sieving the five-color purple clay ore and special mineral materials to specific mesh sizes to ensure the uniformity and fineness of the clay particles, resulting in a smooth surface and delicate texture in the finished product. The mixing step ensures the uniform dispersion of special mineral materials in the five-color purple clay ore, enhancing the stability of the body during firing. By adopting a stepped drying step, different combinations of temperatures and times are used according to the characteristics of the body to remove most of the moisture inside the body, gradually releasing latent stress and reducing cracking caused by stress concentration. The segmented heating and firing step sets the heating rate according to the changing needs of the clay in different temperature ranges, ensuring that the body is heated evenly during firing, reducing stress caused by sudden temperature changes, and lowering the risk of cracking and deformation.

[0017] 3. The present invention ensures that the green body fully reacts and crystallizes at the final firing temperature by adopting a constant temperature heat preservation step, which improves the color uniformity and surface hardness of the finished product. The gradient cooling step avoids the sharp increase in internal stress of the green body caused by a sudden drop in temperature by controlling the cooling rate, thus reducing the possibility of cracking. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the process for a non-layered fusion firing of multi-color purple clay seals based on special mineral materials proposed in this invention. Figure 2 This is a schematic diagram of the process for a non-layered fusion firing of multi-color purple clay seals based on special mineral materials proposed in this invention. Figure 3 This is a schematic diagram of the process for a non-layered fusion firing of multi-color purple clay seals based on special mineral materials proposed in this invention. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0020] Reference Figures 1-3 A multi-colored purple clay pottery seal-making process without layering and firing, based on special mineral materials, includes a raw material pretreatment step: The five-colored purple clay ore is crushed, impurities are removed, and it is sieved to 200 mesh to obtain five-colored purple clay ore material; Special mineral materials are finely ground and sieved to 500 mesh to obtain ultrafine special mineral materials; The weight ratio of the five-color purple clay raw material to special mineral materials is 96-98 parts: 2-4 parts. This setting allows the composite purple clay to better integrate different colors during the firing process, and the shrinkage ratio is more uniform, effectively reducing delamination and cracking.

[0021] The particle size of the five-color purple clay raw material is 180-220 mesh, and the particle size of the special mineral materials is 450-600 mesh. This setting ensures the fineness of the raw materials, laying a good foundation for the subsequent mixing and firing process, so that the purple clay of different colors can be better integrated during firing and reduce the occurrence of layering.

[0022] Precise mixing steps: By mixing 97 parts by weight of the five-color purple clay raw material with 3 parts by weight of ultrafine special mineral material, a composite purple clay material is obtained. Ultrafine special mineral materials are layered silicate minerals or their complexes with low expansion coefficients, processed using a specific technique. The main functional components of ultrafine special mineral materials are hydrated oxides of silicon, aluminum, and magnesium. These special mineral materials are used to adjust the shrinkage ratio differences of different colored purple clay materials during the firing process, thereby reducing stress concentration inside the clay body during firing. By utilizing the characteristics of these special mineral materials, the problem of stress concentration inside the clay body caused by shrinkage ratio differences in traditional processes is improved, reducing cracking and delamination during firing and increasing the yield.

[0023] The mixing process employs mechanical stirring or repeated manual kneading to ensure that the special mineral materials are evenly dispersed in the gaps between the particles of the five-color purple clay ore. This arrangement allows the special mineral materials to fully integrate with the five-color purple clay ore, ensuring the natural fusion of colors and the stability of texture during subsequent firing, and reducing firing quality problems caused by uneven mixing.

[0024] Blank forming steps: The composite purple clay is shaped or carved to form a multi-colored purple clay seal blank. Step-by-step drying process: The multi-colored purple clay seal blanks were dried at 40℃ for 12 hours and at 60℃ for 24 hours in sequence to remove the internal moisture and release the hidden stress. The drying temperature range of the stepped drying step is 30 to 70°C, and the total drying time is 30 to 48 hours. This setting allows for more thorough removal of moisture from the body and release of latent stress, reducing the problems of incomplete drying and stress concentration that may occur in traditional drying methods, and ensuring the stability of the subsequent firing process.

[0025] Segmented heating and firing steps: The dried green body is placed in the kiln and fired according to the following heating procedure: 0~300℃, heating rate is 2℃ / min; 300~500℃, heating rate is 4℃ / min; 500~800℃, heating rate is 3℃ / min; In the segmented heating and firing process, the heating rate of each stage is allowed to fluctuate within ±0.5℃ / min. By setting it in this way, the heating rate can be scientifically controlled according to the characteristics of different colored Zisha clay and the physicochemical changes during the firing process. This avoids problems such as cracking and deformation of the body caused by improper heating rate in traditional processes. At the same time, allowing a certain range of fluctuation also increases the flexibility and operability of the process, and can better adapt to the firing needs of different batches of raw materials and different environmental conditions.

[0026] Constant temperature insulation steps: Once the firing temperature reaches 800℃, a heat preservation treatment is performed for 1.5 hours. The final firing temperature is 780–820℃. The holding time for the constant temperature step is 1–2 hours. This setting ensures that the clay body can fully react during the firing process, allowing different colors of purple clay to better fuse at high temperatures. It reduces firing quality problems caused by excessively high or low temperatures or insufficient holding time, reduces uneven coloring, layering, cracking, etc., and improves the color uniformity and texture stability of the finished product.

[0027] Gradient cooling steps: When the temperature is above 500℃, cool down at a rate of 2℃ / min; When the temperature is below or equal to 500℃, allow it to cool naturally to room temperature. In the gradient cooling step, the cooling rate above 500℃ is 1.5~2.5℃ / min. This setting reduces the cracking and deformation of the billet caused by the sudden drop in temperature in the traditional natural cooling method, and allows the billet to transition smoothly during the cooling process, ensuring the integrity and quality stability of the finished product. This cooling step also takes into account the changes in the physical properties of the billet at different temperature stages. By controlling the cooling rate in segments, it achieves refined management of the billet cooling process.

[0028] Finished product inspection steps: Quality testing was conducted on the cooled multi-colored Zisha pottery seals to obtain finished products that were free of delamination and cracking, with naturally blended colors. The finished multi-colored Zisha pottery seals, after firing, possessed at least one of the following performance indicators: color uniformity ≥90%; surface hardness ≥7H; and no delamination or obvious cracks after firing. This established clear quality standards for the finished products, providing quantifiable indicators for the production process and improving the overall quality level of the products. It also enhanced the artistic appeal and market competitiveness of the products.

[0029] Experiment 1: Verification of the effectiveness of the core material formulation. Experimental objective: To verify the key role of adding 3% by weight of 500-mesh ultrafine special mineral material in regulating the shrinkage ratio difference of Karamay five-color purple clay raw ore (200 mesh) and preventing delamination and cracking after firing.

[0030] Experimental materials and group assignments: Test compound: The main clay material is Karamay Wucai Zisha raw ore, which is crushed, screened and fixed to 200 mesh.

[0031] The functional adjustment material is an ultrafine special mineral material, which is ground to 500 mesh.

[0032] Blank control group: 100% Five-color Purple Clay Ore Clay.

[0033] Experimental Group 1: 97% Five-color purple clay raw ore + 3% ultrafine special mineral materials.

[0034] Experimental Group 2: 90% Five-color Purple Clay Ore Clay + 10% Ultrafine Special Mineral Materials.

[0035] Experimental Group 3: 97% Five-color Purple Clay Ore + 3% Ordinary Kaolin.

[0036] Solution: Ingredients and mixing: Weigh strictly according to the group ratio, mix in a vacuum plywood machine for 30 minutes to ensure uniformity.

[0037] Sample preparation: Prepare 10 parallel samples for each group by shaping each group into a standard 20mm x 20mm x 100mm strip specimen.

[0038] Drying and firing: All specimens were dried under the same conditions (40℃ / 12h→60℃ / 24h) and fired using a uniform simplified firing regime to eliminate interference from process variables.

[0039] Experimental methods and observation indicators: Linear shrinkage rate determination: The length of each group of specimens before and after firing was measured. Samples of the five colors of clay were prepared and measured separately, and the shrinkage rate of each color of clay was calculated.

[0040] Calculation method: Shrinkage rate (α) = [(L0-L1) / L0] × 100%. Where L0 is the length after drying and L1 is the length after firing.

[0041] Key indicators: Calculate the standard deviation and range of the shrinkage rate of the five-color clay materials in each group to quantify the differences in shrinkage ratio.

[0042] Finished product defect rate statistics: After firing, each specimen is independently observed by 3 experienced ceramic craftsmen under a 10x magnifying glass.

[0043] Layering determination: A visible continuous gap or peeling appears at the interface between any two colors.

[0044] Crack determination: Cracks with a length greater than 2 mm appear on the surface or inside the specimen.

[0045] Calculation method: Defect rate = (Number of specimens with a specific defect / Total number of specimens in the group) × 100%.

[0046] Microstructure analysis: The cross-sections of specimens without macroscopic defects were randomly selected from each group, and after gold sputtering, the micro-bonding state at the color interface was observed using a scanning electron microscope.

[0047] The following experimental results were obtained;

[0048] The data above shows that the extremely high stratification and cracking rate of the blank control group confirms that the untreated multi-colored purple clay cannot be fused due to the huge difference in shrinkage ratio. The perfect performance of experimental group 1 proves that adding 3% ultrafine special mineral material is a necessary means to solve this problem.

[0049] Experimental group 1 achieved zero delamination and extremely low cracking rate while preserving the natural texture and color of Zisha to the greatest extent. Although experimental group 2 had better shrinkage control, it damaged the material's intrinsic properties, proving that 3% is the optimal dosage for balancing function and intrinsic properties.

[0050] The results of experimental group 3 were significantly lower than those of experimental group 1, proving that the ultrafine special mineral material used has specific functions, rather than the general effect of any fine-particle material.

[0051] The functional principle of this invention can be explained through the following operational methods: In the raw material stage, 200-mesh multicolored purple clay ore and 500-mesh special mineral materials are mixed in a predetermined ratio to form a uniform composite clay system. After the composite clay is formed, the purple clay particles of different colors are continuously distributed in the overall structure, and the special mineral materials are evenly present between the purple clay particles. During the drying stage, the green body undergoes a step-by-step drying process at 40℃ and 60℃, and the moisture inside the green body is gradually discharged. The structure of the green body remains stable during the drying process, providing a uniform initial state for subsequent firing. During the heating and firing stage, the clay body is processed in the kiln according to a preset segmented heating program: the 0-300℃ stage is slowly heated to complete the dehumidification process; the 300-500℃ stage completes the transformation of the clay structure; and the 500-800℃ stage completes the stabilization of the clay body shape and overall sintering. During the heating process, the multi-colored purple clay material changes synchronously in the composite clay system. When the firing temperature reaches 800℃, the body enters the constant temperature heat preservation stage. During this stage, the composite clay system completes the overall densification process, and the multi-colored purple clay structure is stably formed. During the cooling stage, the clay body is cooled at a set rate within a range above 500℃, and then naturally cooled below 500℃ to complete the entire firing process. After cooling, the multi-colored purple clay pottery seal forms a continuous overall structure, and each color area maintains a natural transition state.

[0052] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A non-layered fusion firing process for multi-colored purple clay pottery seals based on special mineral materials, characterized in that... Raw material pretreatment steps: The five-colored purple clay ore is crushed, impurities are removed, and it is sieved to 200 mesh to obtain five-colored purple clay ore material; Special mineral materials are finely ground and sieved to 500 mesh to obtain ultrafine special mineral materials; Precise mixing steps: The five-colored purple clay raw material 97 parts by weight and the ultrafine special mineral material 3 parts by weight are thoroughly mixed and stirred to obtain composite purple clay material; Blank forming steps: The composite purple clay material is shaped or carved to form a multi-colored purple clay seal blank. Step-by-step drying process: The multicolored purple clay seal blanks were dried at 40°C for 12 hours and at 60°C for 24 hours in sequence to remove internal moisture and release latent stress. Segmented heating and firing steps: The dried green body is placed in the kiln and fired according to the following heating procedure: 0~300℃, heating rate is 2℃ / min; 300~500℃, heating rate is 4℃ / min; 500~800℃, heating rate is 3℃ / min; Constant temperature insulation steps: Once the firing temperature reaches 800℃, a heat preservation treatment is performed for 1.5 hours. Gradient cooling steps: When the temperature is above 500℃, cool down at a rate of 2℃ / min; When the temperature is below or equal to 500℃, allow it to cool naturally to room temperature. Finished product inspection steps: Quality testing was conducted on the cooled multi-colored purple clay pottery seals to obtain finished multi-colored purple clay pottery seals that were free of layering and cracking, and whose colors were naturally blended.

2. The non-layered fusion firing process for multi-color purple clay pottery seals based on special mineral materials according to claim 1, characterized in that, The weight ratio of the five-colored purple clay raw ore to the special mineral material is 96-98 parts: 2-4 parts.

3. The non-layered fusion firing process for multi-color purple clay pottery seals based on special mineral materials according to claim 1, characterized in that, The particle size of the five-colored purple clay raw ore is 180-220 mesh, and the particle size of the special mineral material is 450-600 mesh.

4. The non-layered fusion firing process for multi-color purple clay pottery seals based on special mineral materials according to claim 1, characterized in that, The ultrafine special mineral material is a layered silicate mineral or its composite with a low expansion coefficient that has been processed by a specific process. The main functional components of the ultrafine special mineral material are hydrated oxides of silicon, aluminum, and magnesium. The special mineral material is used to adjust the shrinkage ratio difference of different colored purple clay materials during the firing process, so as to reduce the stress concentration inside the body during the firing process.

5. The non-layered fusion firing process for multi-color purple clay pottery seals based on special mineral materials according to claim 1, characterized in that, The mixing step employs mechanical stirring or repeated manual kneading to ensure that the special mineral material is evenly dispersed in the gaps between the particles of the five-colored purple clay ore.

6. The non-layered fusion firing process for multi-color purple clay pottery seals based on special mineral materials according to claim 1, characterized in that, The drying temperature range of the stepped drying step is 30 to 70°C, and the total drying time is 30 to 48 hours.

7. The non-layered fusion firing process for multi-color purple clay pottery seals based on special mineral materials according to claim 1, characterized in that, In the segmented heating and firing process, the heating rate at each stage is allowed to fluctuate within the range of ±0.5℃ / min.

8. The non-layered fusion firing process for multi-color purple clay pottery seals based on special mineral materials according to claim 1, characterized in that, The final firing temperature is 780–820°C, and the holding time for the constant temperature holding step is 1–2 hours.

9. The non-layered fusion firing process for multi-color purple clay pottery seals based on special mineral materials according to claim 1, characterized in that, In the gradient cooling step, the cooling rate above 500°C is 1.5–2.5°C / min.

10. The non-layered fusion firing process for multi-color purple clay pottery seals based on special mineral materials according to claim 1, characterized in that, The multi-colored purple clay seals obtained by firing using the aforementioned process have at least one of the following performance indicators: color uniformity ≥90%; surface hardness ≥7H; no delamination or obvious cracks after firing.

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