Solid ceramic and preparation method thereof

Abstract

The present invention relates to the field of ceramics and preparation methods thereof, and in particular to a solid ceramic and preparation method thereof, wherein a solid body comprises a body skeleton and an outer body layer, wherein the outer body layer covers the surface of the body skeleton, and the raw materials of the outer body layer and the body skeleton comprise a base body and an organic powder. In the present invention, before drying, the solid body is first subjected to synchronous humidity control and preheating of the inside and outside of the body, so that the moisture content inside and outside the body tends to be consistent, the drying process is alternately carried out by microwave drying and hot air drying, and a reasonable drying system is set, so that the moisture content of the body is uniformly reduced in a relatively short time, the shrinkage stress of the body is small, and cracking is not easily caused; the solid body is formed by a combination of kneading molding and slip injection molding, and a stable outer surface shape and size can be obtained, which is suitable for industrial production.

Description

Technical Field

[0001] The invention relates to the field of ceramics and preparation methods thereof, and in particular to solid ceramics and a preparation method thereof. Background Art

[0002] During the drying process of ceramic green bodies, the traditional heating method is through thermal radiation, convection and conduction. Heat is transferred from the green body surface to the inside of the green body, and the heating is carried out from the surface to the inside. Since the surface temperature is higher than the center temperature, a large temperature gradient will be generated, which limits the heating rate, resulting in the phenomenon of being burnt on the outside and not cooked on the inside, and will lead to uneven submicrostructure and performance. Therefore, in order to avoid excessive temperature gradient, the heating rate is often not too fast, resulting in a very slow drying speed of the green body; and for solid ceramics or ceramics with particularly thick green body walls, during the drying stage, due to the large green body thickness, the humidity gradient difference of the green body in the thickness direction is too large, resulting in shrinkage stress greater than the bonding force of the green body, which in turn causes the green body to crack. Therefore, shrinkage stress may be generated when the green body is dried too quickly or unevenly. When the shrinkage stress exceeds the yield value of the green body in the plastic state, the green body may deform and crack. The use of traditional ceramics to dry solid green bodies cannot meet the needs, which is easy to cause cracking during the green body drying process. Insufficient drying inside the green body may even cause the green body to explode during the firing stage. In view of this, this case is thus generated. Summary of the invention

[0003] An object of the present invention is to solve at least the above-mentioned problems by a solid ceramic and a method for preparing the same.

[0004] To solve the above technical problems, the technical solution adopted by the present invention is as follows: solid ceramics, including a solid green body and a glaze, the solid green body includes a green body skeleton and an outer green body layer, the outer green body layer covers the surface of the green body skeleton, and the raw materials of the outer green body layer, measured in parts by weight, include the following components: 90-100 parts of basic green body and 2-3 parts of organic powder; the raw materials of the green body skeleton, measured in parts by weight, include the following components: 90-100 parts of basic green body and 3-4 parts of organic powder.

[0005] Preferably, the raw materials of the basic blank include the following components in parts by weight: 40-45 parts of kaolin, 20-30 parts of low-temperature clay, 10-15 parts of feldspar, 8-10 parts of quartz, 5-8 parts of limestone, and 2-4 parts of zinc oxide.

[0006] Preferably, the organic powder is wood powder or flour.

[0007] Preferably, the raw materials of the glaze include the following components in parts by weight: 50-60 parts of feldspar, 15-20 parts of dolomite, 20-25 parts of kaolin, 5-8 parts of calcium carbonate, 10-12 parts of titanium dioxide, 3-4 parts of nickel oxide, and 2-4 parts of bentonite.

[0008] According to the above-mentioned method for preparing solid ceramics, the following steps are included:

[0009] Step a, forming a green body skeleton;

[0010] Step b, placing the green body skeleton inside the grouting mold, grouting between the green body skeleton and the grouting mold while rotating the grouting mold, the slurry is dehydrated under the action of the grouting mold and adsorbed on the side wall of the grouting mold until the slurry fills the gap between the green body skeleton and the grouting mold, and then the grouting is stopped;

[0011] Step c: After standing for 10-15 minutes, check whether the height of the slurry meets the standard. If so, pour out the excess slurry;

[0012] Step d, continue to stand and wait for the outer layer of the blank to initially harden, then take the blank out of the mold, and trim and polish the position of the top grouting port of the outer layer and the excess mud on the outer surface;

[0013] Step e, placing the green body in a constant humidity and temperature synchronization device to synchronize the humidity of the green body skeleton and the outer green body layer;

[0014] Step f, drying the green body by microwave drying and hot air drying;

[0015] Step g, placing the green body into a kiln for biscuit firing;

[0016] Step h, applying glaze on the surface of the body;

[0017] Step i: firing in a kiln to obtain a ceramic product.

[0018] Preferably, in step a, the green body skeleton is formed by kneading.

[0019] Preferably, in step b, the grouting mold comprises a bottom mold and two upper molds, the two upper molds are placed above the bottom mold after being spliced, and the two upper molds and the base together form a molding cavity for grouting molding.

[0020] Preferably, in step e, the synchronization device includes an openable and closable shell, an electric heater, a temperature sensor, a humidifier, a dehumidifier, a humidity sensor and a circulating fan, and the interior of the shell is used to place the blank.

[0021] Preferably, in step i, lime powder and quartz sand are laid on the shelf in the kiln, the lime powder and quartz sand are covered with a layer of shells, and the glazed body is placed on the shells in a lying position.

[0022] Preferably, the specific steps in step f include: a constant-rate drying stage: microwave drying is continued for 1-1.5 hours, during which hot air drying is turned on every 10 minutes, and each hot air drying time lasts for 10 minutes; a reduced-rate drying stage: hot air drying is continued for 1-1.5 hours, during which microwave drying is turned on every 20 minutes, and each microwave drying time lasts for 10 minutes.

[0023] From the above description, it can be seen that the solid ceramic and the preparation method thereof provided by the present invention have the following beneficial effects: in the present invention, the humidity inside and outside of the solid body are synchronized and preheated before drying, so that the moisture content inside and outside the body tends to be consistent, and the drying process is carried out alternately by microwave drying and hot air drying, and a reasonable drying system is set, so that the moisture content of the body is uniformly reduced in a short time, the shrinkage stress of the body is small, and it is not easy to cause cracking; the solid body is formed by a combination of kneading molding and slip injection molding, and a stable outer surface shape and size can be obtained, which is suitable for industrial production; after the glaze on its surface is fired, the whole is matte yellow, and there are shell patterns and granular gray-white patterns on the upper side, which is unique in beauty. DETAILED DESCRIPTION

[0024] The present invention is further described below through specific implementation modes.

[0025] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0026] The solid ceramic of the present invention comprises a solid body and a glaze. The solid body comprises a body skeleton and an outer body layer. The outer body layer covers the surface of the body skeleton. The raw materials of the outer body layer include the following components by weight: 90-100 parts of basic body and 2-3 parts of organic powder; the raw materials of the body skeleton include the following components by weight: 90-100 parts of basic body and 3-4 parts of organic powder. The organic powder in the body is decomposed during the biscuit firing process, so that pores are formed inside the body to help water diffusion. The content of organic powder in the body skeleton is slightly higher than that in the outer body layer. After the body is biscuit fired, the pores formed inside the body are higher than those in the outer body layer, thereby helping the water inside the body to diffuse to the outside better.

[0027] The raw materials of the basic blank include the following components in parts by weight: 40-45 parts of kaolin, 20-30 parts of low-temperature clay, 10-15 parts of feldspar, 8-10 parts of quartz stone, 5-8 parts of limestone, and 2-4 parts of zinc oxide.

[0028] The organic powder is wood powder or flour or other organic matter. The particle size of the wood powder or flour is less than 300 meshes.

[0029] The raw materials of the glaze include the following components by weight: 50-60 parts of feldspar, 15-20 parts of dolomite, 20-25 parts of kaolin, 5-8 parts of calcium carbonate, 10-12 parts of titanium dioxide, 3-4 parts of nickel oxide, and 2-4 parts of bentonite. After firing, the glaze surface forms a yellow matte glaze effect.

[0030] The method for preparing the solid ceramic comprises the following steps:

[0031] Step a, forming a green body skeleton;

[0032] In step a, the body skeleton is formed by kneading, and the body skeleton after kneading has a certain support and is used as a skeleton for subsequent grouting molding. Preferably, the mud block used to form the body skeleton is kneaded on a molding frame, and the molding frame includes a base and a plurality of smooth metal rods perpendicular to the base. The base is provided with an inner molding ring that passes through the base and is used to form an inner ring foot of the blank. The mud block is inserted into the smooth metal rod, and the bottom of the mud block is embedded in the inner ring foot of the base to form the inner ring foot of the blank. From the bottom of the inner molding ring of the base, it is observed whether the mud fills the inner molding ring. If there are defects, fill them with mud. After kneading and processing the outer surface of the mud block, the formed body skeleton is taken out from the molding frame, and a plurality of exhaust channels are formed at the bottom of the body skeleton. The exhaust channels can assist in discharging moisture inside the blank during the drying and firing stages, reduce the humidity gradient inside and outside the blank, and thereby reduce shrinkage stress.

[0033] Step b, placing the green body skeleton inside the grouting mold, grouting between the green body skeleton and the grouting mold while rotating the grouting mold, the slurry is dehydrated under the action of the grouting mold and adsorbed on the side wall of the grouting mold until the slurry fills the gap between the green body skeleton and the grouting mold, and then the grouting is stopped;

[0034] In step b, the grouting mold includes a bottom mold and two upper molds, the two upper molds are spliced ​​and placed above the bottom mold, the two upper molds and the base are surrounded to form a molding cavity for grouting molding, the tops of the two upper molds are surrounded to form a conical grouting cavity, the grouting cavity and the molding cavity are connected, and during the grouting process, the slurry is injected from the grouting cavity into the molding cavity of the grouting molding. A positioning ring matching the shape of the inner ring foot is provided on the bottom mold, and an outer molding ring for molding the outer ring foot is also provided on the bottom mold. The gap between the blank skeleton and the inner wall of the upper mold gradually increases from bottom to top. During the grouting process, the moisture in the slurry is absorbed by the gypsum mold, so that the slurry is absorbed on the wall of the gypsum mold, and the slurry wall thickness gradually thickens until the slurry completely fills the gap between the gypsum mold and the blank skeleton.

[0035] Step c: after standing for 10-15 minutes, check whether the height of the slurry meets the standard. If so, pour out the excess slurry. When the grouting blank accumulates to the connecting port between the grouting cavity and the molding cavity, stop grouting and pour out the excess slurry in the grouting cavity.

[0036] Step d, continue to wait for the outer layer of the blank to harden initially, then take the blank out of the mold, trim and polish the top grouting port of the outer layer and the excess clay on the outer surface; if necessary, perform texture carving on the surface of the outer layer or adhere other decorative clay.

[0037] Step e, placing the green body in a constant humidity and temperature synchronization device to synchronize the humidity of the green body skeleton and the outer green body layer;

[0038] In step e, the synchronization device includes an openable and closable shell, an electric heater, a temperature sensor, a humidifier, a dehumidifier, a humidity sensor and a circulating fan, and the inside of the shell is used to place the blank. The temperature sensor and humidity sensor are arranged inside the shell, and the electric heater, humidifier and dehumidifier are arranged in a channel outside the shell. The channel is connected to the shell through a circulating fan. The wind extracted from the shell through the circulating fan passes through the humidifier, dehumidifier and electric heater in the channel in turn. The humidifier and dehumidifier perform humidification and dehumidification operations respectively, which can improve the stability and accuracy of system control. The humidity sensor is used to collect humidity, the electric heater heats the inside of the shell, and the temperature sensor collects the temperature inside the shell. The circulating fan helps the air in the shell to flow evenly, accelerates the balance of temperature and humidity, and controls and adjusts the temperature and humidity through a temperature and humidity controller. The temperature and humidity controller of the synchronization device receives the temperature and humidity signals inside the shell, and controls the humidifier, dehumidifier and electric heater in real time according to the set temperature and humidity parameters, thereby maintaining the required temperature and humidity; during operation, grouting molding The green body is placed in the synchronous device, the equipment is turned on, the humidity is set to 12%, the temperature is set to 50-55 degrees, the air in the shell is reciprocated under the drive of the circulating fan, the air in the shell is passed through the pipeline into the heater, humidifier and dehumidifier, the temperature is adjusted by the heater, and the humidity is controlled by the humidifier and dehumidifier, so that the air in the shell maintains a constant temperature and humidity environment. The temperature should be kept in a suitable range. If the temperature is too high, the thermal motion of water molecules will cause the clay bonding strength to decrease. The green body is left to stand for a period of time in a relatively high humidity environment, so that the humidity of the green body skeleton and the outer green body layer is synchronized, so that the internal and external shrinkage consistency of the green body in the subsequent drying step is good. The standing time in the synchronous device is 20-24 hours. This step is also preheating the green body before drying, so that the internal temperature of the green body is increased, and the internal moisture diffusivity of the green body is improved, so that it can be quickly dried in the subsequent drying stage. The green body is placed on the drying bracket inside the shell, and a through hole is opened on the support plate of the drying bracket to facilitate the diffusion of moisture at the bottom of the green body. Further, the drying bracket can be rotated so that all parts of the green body are heated evenly.

[0039] Step f, the green body is dried by microwave drying and hot air drying; a microwave heating device is arranged on the synchronization device, and the microwave heating device includes a microwave generator, a cooling system, a control system, etc. The specific structure of the microwave heating device refers to the prior art and will not be repeated here.

[0040] The specific steps in step f include: 1. Constant speed drying stage: microwave drying is continued for 1-1.5 hours, during which hot air drying is turned on every 10 minutes, and each hot air drying time lasts for 10 minutes; 2. Decreasing speed drying stage: hot air drying is continued for 1-1.5 hours, during which microwave drying is turned on every 20 minutes, and each microwave drying time lasts for 10 minutes.

[0041] At the beginning of the isotropic drying stage, the hot air drying is not turned on first. The diffusion inside the green body is accelerated by microwave drying first. After 10 minutes, the hot air drying is turned on again. The hot air drying is continued for 10 minutes and then stopped. This process is repeated. The isotropic drying stage is mainly based on microwave drying, which focuses on stimulating the heat diffusion and moisture diffusion inside the green body. The moisture of the outer layer of the green body is removed by intermittent hot air drying, so that the humidity of the green body is uniformly and rapidly reduced in a relatively short period of time. During this period, the humidity in the shell of the synchronous device is synchronously regulated, and the humidity drops from 12% to 6%.

[0042] At the beginning of the speed-down drying stage, microwave drying is not turned on. Hot air drying is used to accelerate the external diffusion of the green body. After 20 minutes, microwave drying is turned on again. Microwave drying is continued for 10 minutes and then paused. This cycle repeats. Since the moisture inside the green body has dropped to a lower level during the constant-speed drying stage, the green body shrinks less at this time and does not produce a large shrinkage stress. At this time, hot air drying is not likely to cause green body cracking. The speed-down drying stage is mainly hot air drying, which promotes the external diffusion of the green body. During this period, microwave heating is intermittently turned on to further stimulate the diffusion of residual moisture inside the green body. During this period, the humidity in the shell of the synchronous device is synchronously regulated, and the humidity drops from 6% to 3%.

[0043] The characteristic of microwave heating is that the whole inside and outside of the green body are heated synchronously, the microwave heating is uniform, the shrinkage stress is small, and the green body is not easy to crack, while hot air drying can accelerate the diffusion outside the green body, thereby accelerating the rapid discharge of moisture; the green body drying process is carried out alternately by microwave drying and hot air drying, and a reasonable drying system is set. The humidity is reduced synchronously during the drying process, so that the moisture content of the green body decreases evenly in a relatively short time, the shrinkage stress of the green body is small, and it is not easy to cause cracking.

[0044] Step g, the green body is put into a kiln for biscuit firing; the biscuit firing temperature is 700-800 degrees Celsius. The green body contains organic powder, which decomposes during the biscuit firing process to form pores in the green body, helping the moisture inside the green body to be discharged from the green body during the biscuit firing process. Therefore, the green body is not easy to crack during the biscuit firing. In addition, the moisture inside the green body is fully discharged during the drying process, so the green body has good stability during the biscuit firing process.

[0045] Step h, applying glaze on the surface of the body;

[0046] Step i: firing in a kiln to obtain a solid ceramic product.

[0047] In step i, lime powder and quartz sand are laid on the shelf in the kiln, and the ratio of lime powder to quartz sand is 3:1. A layer of shells is covered on the lime powder and quartz sand, and the glazed body is placed on the shells in a lying position. Shells, lime powder and quartz sand are used as supports for the body to prevent the body from adhering to the shelf. At the same time, due to the different heights of the shells, a certain gap is formed between the body and the shelf when the body is supported, which is conducive to the removal of moisture from the body and the glaze during the glaze firing process. After the glaze is fired, the shells form shell traces on the glaze surface, and some shells are directly integrated with the glaze surface. Part of the lime powder is covered on the glaze surface to form gray-white stripes, and part of the quartz sand is integrated with the glaze surface, so that uneven granular texture is formed on the gray-white texture. The glaze surface is matte yellow as a whole, and shell texture and granular gray-white texture are distributed on one side, which is unique in beauty.

[0048] In the present invention, the humidity inside and outside of the solid green body is synchronized and preheated before drying, so that the moisture content inside and outside the green body tends to be consistent. The drying process is carried out alternately by microwave drying and hot air drying, and a reasonable drying system is set up, so that the moisture content of the green body is uniformly reduced in a relatively short time, the shrinkage stress of the green body is small, and it is not easy to cause cracking.

[0049] A plurality of exhaust channels can be provided at the bottom of the blank skeleton to assist in discharging the internal moisture during the drying process, reduce the internal and external humidity gradient, and make the drying speed inside and outside the blank consistent.

[0050] Traditional solid green bodies are usually formed by the method of overall kneading, which takes a long time to form and has non-uniform external dimensions. Since the solid green body is too thick, it cannot be formed by the method of slip injection, because the outward expansion performance of its water content decreases in the later stage of slip injection, resulting in the center of the solid green body being unable to be filled with slurry, and additional mud is required to supplement the internal hollow, which may cause internal hollowing. In the present invention, the solid green body is formed by a combination of kneading and slip injection, and a stable external surface shape and size can be obtained, which is suitable for industrial production and suitable for mass production of solid ceramics with not very complex surface textures and morphologies. Compared with the process of preparing green bodies by pure kneading, the production efficiency of the process of the present invention is significantly improved.

[0051] Microwave drying is a process in which microwaves directly interact with the green body to convert electromagnetic energy into heat energy in an instant, thereby achieving rapid dehydration and drying of the green body. Microwave heating utilizes the dielectric loss principle. During the heating process, electromagnetic energy is converted into heat energy through dielectric loss. Only materials that absorb microwaves can be heated by microwaves. Since the dielectric loss of water is very large, the microwave energy absorbed by water is much greater than that of other substances. Microwaves are electromagnetic waves with a frequency of 300MHz to 300GHz. The water molecules in the heated green body are polar molecules. Under the action of a rapidly changing high-frequency electromagnetic field, their polar orientation will change with the change of the external electric field, causing the movement of the molecules and the mutual friction effect. At this time, the field energy of the microwave field is converted into heat energy in the medium, which increases the temperature of the green body, produces a series of physical and chemical processes such as thermalization and puffing, and achieves the purpose of microwave heating and drying.

[0052] The green body is dried by microwave heating. Since microwaves have strong penetration ability to the absorption medium, the heat does not need to be transferred from the surface to the inside of the green body. Instead, the energy is directly applied to the entire green body and instantly converted into heat inside the green body. The heating is uniform, the shrinkage stress is reduced, the heating time is greatly shortened, and the problem of inconsistent drying speed between the surface and the inside of the green body is overcome when drying thick-walled green bodies.

[0053] Microwave heating is generated from inside the blank. The heat source comes from inside the blank, and the heating inertia is small, which can achieve rapid control of temperature rise and fall. During microwave heating, heat is conducted from inside the blank through the blank to the outside, so the surface temperature of the blank is lower than the center temperature, ensuring that the direction of heat expansion and moisture diffusion is consistent. After a period of microwave heating, the internal diffusion is accelerated. At this time, hot air is sprayed to accelerate the external diffusion of the blank, thereby accelerating the rapid discharge of moisture.

[0054] In addition to microwave heating, the present invention also combines hot air drying and humidity gradient control in the drying process, wherein appropriate use of hot air drying can accelerate the drying speed, and hot air drying and microwave drying are performed alternately or intermittently, which can better promote internal diffusion or external diffusion at different stages, and through humidity control, the humidity of the blank can be uniformly reduced during the drying process, thereby improving the accuracy and stability of the blank humidity control, thereby reducing the cracking phenomenon of the blank during the drying process.

[0055] The above are only some specific implementation methods of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial changes to the present invention using this concept shall be deemed as an infringement of the protection scope of the present invention.

Claims

1. A method for preparing solid ceramics, characterized in that: The steps include: Step a, forming a green body skeleton; Step b, placing the green body skeleton inside the grouting mold, grouting between the green body skeleton and the grouting mold while rotating the grouting mold, the slurry is dehydrated under the action of the grouting mold and adsorbed on the side wall of the grouting mold until the slurry fills the gap between the green body skeleton and the grouting mold, and then the grouting is stopped; Step c: After standing for 10-15 minutes, check whether the height of the slurry meets the standard. If it does, pour out the excess slurry; Step d, continue to stand and wait for the outer layer of the blank to initially harden, then take the blank out of the mold, and trim and polish the position of the top grouting port of the outer layer and the excess mud on the outer surface; Step e, placing the green body in a constant humidity and temperature synchronization device to synchronize the humidity of the green body skeleton and the outer green body layer; Step f, drying the green body by microwave drying and hot air drying; Step g, placing the green body into a kiln for biscuit firing; Step h, applying glaze on the surface of the body; Step i, firing in a kiln to obtain a ceramic product; The solid ceramic comprises a solid body and a glaze, wherein the solid body comprises a body skeleton and an outer body layer, wherein the outer body layer covers the surface of the body skeleton, and the raw materials of the outer body layer comprise the following components in parts by weight: 90-100 parts of a basic body and 2-3 parts of an organic powder; the raw materials of the body skeleton comprise the following components in parts by weight: 90-100 parts of a basic body and 3-4 parts of an organic powder; The raw materials of the basic blank include the following components in parts by weight: 40-45 parts of kaolin, 20-30 parts of low-temperature clay, 10-15 parts of feldspar, 8-10 parts of quartz, 5-8 parts of limestone, and 2-4 parts of zinc oxide; The organic powder is wood powder or flour; The raw materials of the glaze include the following components in parts by weight: 50-60 parts of feldspar, 15-20 parts of dolomite, 20-25 parts of kaolin, 5-8 parts of calcium carbonate, 10-12 parts of titanium dioxide, 3-4 parts of nickel oxide, and 2-4 parts of bentonite.

2. The method for preparing solid ceramics according to claim 1, characterized in that: In the step a, the green body skeleton is formed by kneading.

3. The method for preparing solid ceramics according to claim 1, characterized in that: In the step b, the grouting mold includes a bottom mold and two upper molds. The two upper molds are placed above the bottom mold after being spliced, and the two upper molds and the base are surrounded to form a molding cavity for grouting molding.

4. The method for preparing solid ceramics according to claim 1, characterized in that: In the step e, the synchronization device includes an openable and closable shell, an electric heater, a temperature sensor, a humidifier, a dehumidifier, a humidity sensor and a circulating fan, and the inside of the shell is used to place the blank.

5. The method for preparing solid ceramics according to claim 1, characterized in that: In the step i, lime powder and quartz sand are laid on the shelf in the kiln, a layer of shells are covered on the lime powder and quartz sand, and the glazed body is placed on the shells in a lying position.

6. The method for preparing solid ceramics according to claim 1, characterized in that: The specific steps in step f include: a constant-rate drying stage: microwave drying is continued for 1-1.5 hours, during which hot air drying is turned on every 10 minutes, and each hot air drying time lasts for 10 minutes; a reduced-rate drying stage: hot air drying is continued for 1-1.5 hours, during which microwave drying is turned on every 20 minutes, and each microwave drying time lasts for 10 minutes.