KR102533253B1 - Method for manufacturing ceramic body - Google Patents

Abstract

One embodiment of the present invention is mixing a ceramic raw material and a solvent, milling (milling) to prepare a ceramic slurry; stirring the ceramic slurry; sieving the stirred ceramic slurry; removing heavy metals by magnetism while passing the sieved ceramic slurry through an electromagnet chamber; manufacturing a ceramic cake by performing a filter press on the heavy metal-removed ceramic slurry to remove water to a predetermined degree; and extruding the ceramic cake to produce a ceramic body, wherein the preparing of the ceramic slurry is performed by using a ball having a particle size of less than 12 mm to obtain a first ceramic having a particle size of 2 μm or less in the total weight of the ceramic powder. A method for manufacturing a ceramic body is provided, wherein a ceramic slurry having a powder weight of 10% or more is prepared.

Description

Method for manufacturing ceramic body {Method for manufacturing ceramic body}

Embodiments of the present invention relate to a method for manufacturing a ceramic body.

In general, ceramics are non-metallic inorganic materials made by applying heat to minerals and have high heat resistance and excellent mechanical and insulating properties. Due to these characteristics of ceramics, it is used as a core material for high-tech products closely related to industry and life or numerous devices used in daily life. However, most ceramics have disadvantages in that they are brittle and difficult to mold compared to metals or polymer materials.

On the other hand, in the ceramic process, the ball mill is most often used for the purpose of grinding raw material powder into fine powder or mixing materials, and is widely adopted and used in the field because of its low installation and operating costs and relatively easy handling. The principle of ball milling is to put a hard ball in a cylindrical container and rotate it to pulverize the raw material using impact, shear force, frictional force, etc. by tumbling. becomes a measure The particle size and shape of the powder depend greatly on the ball size, hardness, strength, weight, and amount, and are also greatly affected by milling conditions such as rotational speed, milling time, and loading.

In the conventional ceramic industry, raw powder that has undergone only simple grinding and refining processes has shown sufficient performance, but the shape and size of powder particles have a great influence on the characteristics of the final material and product performance. High purity and ultra-fine granulation of raw material powder are essential.

In order to solve the above problems and/or limitations, an object of the present invention is to prepare a ceramic slurry containing ultra-fine ceramic powder and to provide a method for manufacturing a high-strength ceramic body using the same.

One embodiment of the present invention is mixing a ceramic raw material and a solvent, milling (milling) to prepare a ceramic slurry; stirring the ceramic slurry; sieving the stirred ceramic slurry; removing heavy metals by magnetism while passing the sieved ceramic slurry through an electromagnet chamber; manufacturing a ceramic cake by performing a filter press on the heavy metal-removed ceramic slurry to remove water to a predetermined degree; and extruding the ceramic cake to produce a ceramic body, wherein the preparing of the ceramic slurry is performed by using a ball having a particle size of less than 12 mm to obtain a first ceramic having a particle size of 2 μm or less in the total weight of the ceramic powder. A method for manufacturing a ceramic body is provided, wherein a ceramic slurry having a powder weight of 10% or more is prepared.

In one embodiment of the present invention, in the step of preparing the ceramic slurry, the ball and the ceramic raw material may be mixed in a ratio of 1:1.1 to 1:3 and milled for 9.5 hours to 10.5 hours.

In one embodiment of the present invention, manufacturing a ceramic product having a bending strength of 50 kg/cm ² or more by sintering after molding the ceramic body; may include.

In one embodiment of the present invention, the particle size of the ball and the weight of the first ceramic powder may have an inversely proportional relationship.

In one embodiment of the present invention, the preparing of the ceramic slurry may include milling a first ceramic raw material having a first viscosity with a first ball having a first particle size when mixed with the solvent in a predetermined ratio to obtain the first slurry manufacturing; and preparing a second slurry by milling a second ceramic raw material having a second viscosity different from the first viscosity when mixed with the solvent in a predetermined ratio with a second ball having a second particle size different from the first particle size. In the step of stirring the ceramic slurry, the prepared first slurry and the second slurry may be mixed and stirred in a stirring tank.

Other aspects, features and advantages other than those described above will become apparent from the following drawings, claims and detailed description of the invention.

The method for manufacturing a ceramic body according to embodiments of the present invention may provide a ceramic slurry including ultra-fine ceramic powder, and a ceramic body using the ceramic slurry may have improved mechanical properties such as bending strength.

1 is a flowchart sequentially illustrating a method of manufacturing a ceramic body according to an embodiment of the present invention.
Figure 2 is a table showing the weight ratio according to the particle size of the ceramic powder with respect to the ball particle size.
3 is a graph showing the measured bending strength according to the weight ratio of the first ceramic powder in the ceramic body manufactured according to an embodiment of the present invention.
4 is a graph showing bending strength measured according to a weight ratio of a second ceramic powder in a ceramic body manufactured according to an embodiment of the present invention.

Hereinafter, the following embodiments will be described in detail with reference to the accompanying drawings, and when describing with reference to the drawings, the same or corresponding components are given the same reference numerals, and redundant description thereof will be omitted.

Since the present embodiments can apply various transformations, specific embodiments will be illustrated in the drawings and described in detail in the detailed description. Effects and characteristics of the present embodiments, and methods for achieving them will become clear with reference to the details described later in conjunction with the drawings. However, the present embodiments are not limited to the embodiments disclosed below and may be implemented in various forms.

In the following embodiments, terms such as first and second are used for the purpose of distinguishing one component from another component without limiting meaning.

In the following examples, singular expressions include plural expressions unless the context clearly indicates otherwise.

In the following embodiments, terms such as include or have mean that features or elements described in the specification exist, and do not preclude the possibility that one or more other features or elements may be added.

In the following embodiments, when a part such as a unit, area, component, etc. is on or above another part, not only when it is directly above the other part, but also when another unit, area, component, etc. is interposed therebetween Including case

In the following embodiments, terms such as connect or combine do not necessarily mean direct and/or fixed connection or coupling of two members unless the context clearly indicates otherwise, and does not mean that another member is interposed between the two members. not to exclude

When an embodiment is otherwise implementable, a specific process sequence may be performed differently from the described sequence. For example, two processes described in succession may be performed substantially simultaneously, or may be performed in an order reverse to the order described.

In the drawings, the size of components may be exaggerated or reduced for convenience of explanation. For example, since the size and thickness of each component shown in the drawings are arbitrarily shown for convenience of description, the following embodiments are not necessarily limited to those shown.

1 is a flow chart sequentially illustrating a method for manufacturing a ceramic body according to an embodiment of the present invention, FIG. 2 is a table showing a weight ratio according to the particle size of ceramic powder with respect to the ball particle size, and FIG. 3 is an embodiment of the present invention. A graph showing the measured bending strength according to the weight ratio of the first ceramic powder in the ceramic body manufactured according to the example, and FIG. 4 is a graph showing the weight ratio of the second ceramic powder in the ceramic body manufactured according to an embodiment It is a graph showing the measured bending strength.

Referring to FIG. 1 , a method for manufacturing a ceramic body according to an embodiment of the present invention includes preparing a ceramic slurry by mixing a ceramic raw material and a solvent and milling (S100), stirring the ceramic slurry (S200), and stirring Sieve the sieved ceramic slurry (S300), remove heavy metals from the sieved ceramic slurry (S400), remove moisture to prepare a ceramic cake (S500), and extrude the ceramic cake to prepare a ceramic body ( S600 ), and the method for manufacturing a ceramic body according to an embodiment of the present invention may further include a step ( S700 ) of manufacturing a ceramic product by shaping and firing the ceramic body.

Hereinafter, each step of the method for manufacturing a ceramic body according to an embodiment of the present invention will be described in detail.

First, in the method for manufacturing a ceramic body according to an embodiment of the present invention, a ceramic slurry is prepared by mixing and milling a ceramic raw material and a solvent (S100).

The ceramic body manufacturing method may use a ball mill to mechanically mix and grind the prepared ceramic raw material. The ball mill puts a hard ball in a cylindrical container and rotates it at high speed to apply an external force such as compression, shear, or impact to the particles to pulverize and mix the raw materials. The container used for ball milling may use a Teflon material, and when the Teflon material is used, there is an advantage in that contamination or non-uniformity in composition caused by wear in the ball milling process can be eliminated. It is preferable to use a ball used for ball milling that wear of the ball has little effect on the raw material, and zirconia (ZrO ₂ ) powder and alumina (Al ₂ O ₃ ) powder included in the ceramic raw material are the same as zirconia. Alternatively, it is preferable to use an alumina ball in view of not generating impurities. The balls may all be of the same size, or balls of two or more sizes may be used together.

After the ceramic raw material and the solvent are put into the ball mill, balls are put together for grinding and mixing, and then the ball mill is rotated at a constant speed to mechanically grind the ceramic raw material and mix it uniformly. At this time, friction and centrifugal force act on the ball and the ceramic raw material in the rotating container, and while rotating together with the rotating container, they automatically fall from a certain height, and the ceramic raw material collides with the ball and the ceramic raw material or the inside of the container and the ceramic raw material. The raw materials may be pulverized into fine-sized powders and mixed with a solvent to prepare a ceramic slurry.

As the solvent, a material that does not cause a chemical reaction with the ceramic raw material, is non-toxic, is safe, has a low boiling point, is volatile at about 100° C., and has a small surface tension may be used. Preferably, alcohol such as water or ethanol may be used as a solvent. When wet pulverization is performed using a solvent, the powder can be dispersed and pulverized and mixed uniformly, and during the pulverization process, no coating formed by adherence of the fine particles to the wall or ball of the container is formed, so that the powder can be pulverized into finer particles. do.

By adjusting the size of the ball, the weight ratio of the ball and the ceramic raw material, the milling time, and the rotational speed of the mill in the ball mill, the ceramic raw material can be pulverized into the target powder particle size and mixed uniformly. A ceramic slurry may be prepared. In general, balls having a particle size of 1 mm to 60 mm may be used, milling time may be 1 to 100 hours, and ceramic slurry may be prepared by milling at a rotational speed of 150 to 250 RPM.

A method for manufacturing a ceramic body according to an embodiment of the present invention includes preparing a ceramic slurry in which the weight of first ceramic powder having a particle size of 2 μm or less is 10% or more of the total weight of the ceramic powder using balls having a particle size of less than 12 mm. can include

The first ceramic powder may be produced in a step of preparing a ceramic slurry by mixing and milling a ceramic raw material and a solvent, and refers to ceramic powders having a particle size of 2 μm or less.

Balls with a grain size of less than 12 mm can be used during ball milling, but large balls with a size of 12 mm or more have a large gap between the balls, which hinders grinding and may not achieve the desired fine grinding. However, too small-sized balls have weak crushing power, and when the rotational speed increases, they rotate together along the inside of the bowl of the ball mill, so that crushing does not occur. Therefore, it is preferable to use one or more balls selected from among balls having a grain size of 2 mm, 3 mm, 5 mm, and 8 mm. Balls may be used singly or in combination.

Referring to FIG. 2, when the particle size of the ball is gradually changed from 40 to 60 mm to 2 mm during ball milling and the weight ratio according to the particle size of the ceramic powder is examined, the particle size of 40 to 60 mm, 20 to 40 mm, and 12 mm is When ball milling is performed using a ball, it can be seen that it is difficult to achieve fine grinding because the weight ratio of ceramic powder having a particle size of more than 10 μm is 50% or more. When ball milling is performed using balls with a particle size of 8 mm, 5 mm, 3 mm, or 2 mm, the weight ratio of ceramic powder with a particle size of 10 μm or less accounts for more than 50%, and in particular, the fine ceramic powder with a particle size of 2 μm or less The weight ratio becomes 10% or more. Accordingly, the ball milling process may be performed using balls having a particle size of less than 12 mm to prepare a ceramic slurry in which the weight of the first ceramic powder having a particle size of 2 μm or less is 10% or more of the total weight of the ceramic powder.

In addition, in the method for manufacturing a ceramic body according to an embodiment of the present invention, the grain size of the ball and the weight of the first ceramic powder may have an inversely proportional relationship. Referring to FIG. 2, as the particle size of the balls decreases, the weight of the first ceramic powder having a particle size of 2 μm or less increases in inverse proportion thereto. The ball milling process can be performed by selecting the particle size of

Meanwhile, in the method for manufacturing a ceramic body according to an embodiment of the present invention, milling may be performed for 9.5 hours to 10.5 hours by mixing balls and ceramic raw materials in a ratio of 1:1.1 to 1:3. In the milling process, as the ball loading increases, more collisions occur between the balls and the ceramic raw material, which can increase the grinding efficiency. A suitable loading of may be less than 50% of the vessel volume. On the other hand, if too few balls are loaded, the balls tend to slide, and in this case, the grinding efficiency may be lowered. Therefore, it is preferable to mix the ball and the ceramic raw material in a ratio of 1:1.1 to 1:3. In this case, a preferred milling time may be 9.5 hours to 10.5 hours.

Next, the obtained ceramic slurry is stirred (S200). Since the ceramic slurry obtained by the above process has viscosity and fluidity, it requires a mixing process for homogenization. In this case, the ceramic slurry may be stirred using an agitator having a main stirring blade rotating horizontally along a vertical axis at the center of the stirring tank, or the ceramic slurry may be stirred using a ball mill used in the milling process. In the case of using a ball mill, the ceramic slurry may be stirred using a lower rotational speed than in a milling process in which grinding is mainly performed. For example, the rotation speed may be 50 to 150 RPM. When the temperature of the ceramic slurry is increased due to a machine rotating at a high rotation speed in the milling process, the temperature of the ceramic slurry may be lowered to room temperature in this step. Meanwhile, a dispersant may be added to improve the dispersibility of the ceramic slurry. In the step of stirring the ceramic slurry, pulverization of the ceramic powder may occur.

A method for manufacturing a ceramic body according to an embodiment of the present invention includes the steps of preparing a first slurry by milling a first ceramic raw material having a first viscosity with a first ball having a first particle size when mixed with a solvent in a predetermined ratio; preparing a second slurry by milling a second ceramic raw material having a second viscosity different from the first viscosity when mixing at a certain ratio into a second ball having a second particle size different from the first particle size, Mixing and stirring the first slurry and the second slurry in a stirring tank may be included. In the case of manufacturing a ceramic body using two ceramic raw materials, since each ceramic raw material has a different viscosity when mixed with a solvent, a ceramic slurry is prepared through a milling process with balls having different particle sizes for each ceramic raw material. , Ceramic slurries can be prepared through the steps of putting the prepared ceramic slurries in a stirring tank, mixing them uniformly, and stirring them. The ceramic slurry thus prepared may have characteristics different from those of the first slurry or the second slurry. Even in the case of using three or more ceramic raw materials, ceramic slurries having target characteristics may be prepared by performing a milling process using balls each having a different particle size, and then stirring the prepared ceramic slurries in a stirring tank.

Next, the stirred ceramic slurry is sieved (S300). Since the ceramic slurry obtained in the above process contains the balls used in the milling process, the balls and ceramic slurry may be separated through a sieving step. In addition, impurities or particles of a target size or larger can be filtered out by appropriately selecting the size of the pores of the sieve. In order to improve the efficiency of the wet sieving process, a vibrator, sonicator, vacuum pump, etc. may be used.

Next, heavy metals are removed from the sieved ceramic slurry (S400). Heavy metals can be adsorbed and separated by magnetism while passing the ceramic slurry that has undergone sieving in the above process through the electromagnet chamber. At this time, a stirring blade may be further formed in the electromagnet chamber to perform the heavy metal separation process, and by applying vibration to the electromagnet chamber, heavy metal removal from the ceramic slurry may be more easily performed.

Next, a ceramic cake is prepared by removing moisture (S500). Since the ceramic slurry obtained by the above process contains a large amount of water, water may be removed by performing a filter press. The filter press uses the pressurized dehydration principle. After injecting the ceramic slurry into the filtering device, pressure is applied to separate the filtrate and remove moisture to a predetermined extent to produce a ceramic cake. A drying process may be further included to remove moisture from the ceramic slurry.

Next, a ceramic body is manufactured by extruding the ceramic cake (S600). The ceramic cake that has undergone the filter press operation can be used to manufacture a ceramic body using an extrusion device. The extrusion device may include a mold, and a ceramic body having a certain shape may be manufactured when the ceramic cake is put into the extrusion device, passed through the mold of the extrusion device, and extruded out.

Next, a ceramic product is manufactured by molding and firing the ceramic body (S700). After molding the ceramic body obtained through the above process into a target shape, a ceramic product may be manufactured through a firing process. Conditions of the firing process may be adjusted according to the components of the molded ceramic body.

A method of manufacturing a ceramic body according to an embodiment of the present invention may include manufacturing a ceramic product having a bending strength of 50 kg/cm ² or more by sintering the ceramic body after molding it. The bending strength of a ceramic product manufactured by the method for manufacturing a ceramic body according to an embodiment of the present invention may have a value of greater than or equal to 50 kg/cm ² and less than 100 kg/cm ² .

When the particle size of the ceramic powder decreases, the density of the molded ceramic body increases, and the strength of a ceramic product manufactured through a firing process can be improved. In addition, as the size of the particles decreases, the surface roughness decreases.

The strength of the ceramic body can be achieved by eliminating or reducing defects such as micro gaps where stress accumulates. When the particle size of the ceramic raw material powder is reduced, the structure of the ceramic body becomes more dense and the pores are reduced, so that high strength can be achieved. there will be

3 is a graph showing the bending strength of a ceramic body manufactured by a method for manufacturing a ceramic body according to an embodiment of the present invention, seven samples having different weights of first ceramic powder having a particle size of 2 μm or less among the total weight of ceramic powder; The bending strength was measured and expressed.

Referring to FIG. 3 , it can be seen that as the weight ratio of the first ceramic powder increases, the bending strength of the ceramic body increases, and samples having a weight ratio of the first ceramic powder of 10% or less have a bending strength of 50 kg/cm ² or less. It can be confirmed that it has In particular, it can be confirmed that samples having a weight ratio of the first ceramic powder of 10% or more significantly increase bending strength and have a high bending strength of 50 kg/cm ² or more.

Therefore, a ceramic body manufactured by the method for manufacturing a ceramic body according to an embodiment of the present invention is manufactured so that the weight of the first ceramic powder having a particle size of 2 μm or less is 10% or more of the total weight, so that it can have excellent strength. , it becomes possible to retain good machinability.

Meanwhile, FIG. 4 is a graph showing the bending strength of seven samples having different weights of the second ceramic powder having a particle size of 4 μm or less among the total weight of the ceramic powder.

Referring to FIG. 4 , it can be seen that the bending strength increases as the weight ratio of the second ceramic powder increases, and four samples having a weight ratio of the second ceramic powder of 11.5% or more have significantly increased bending strength. can

Therefore, in the milling process of the ceramic raw material, a ceramic body having higher strength can be manufactured using balls having a particle size of less than 12 mm as the specific gravity of the second ceramic powder having a particle size of 4 μm or less increases.

So far, the present invention has been mainly looked at with respect to preferred embodiments. Those skilled in the art to which the present invention belongs will understand that the present invention can be implemented in a modified form without departing from the essential characteristics of the present invention. Therefore, the disclosed embodiments should be considered from a descriptive point of view rather than a limiting point of view. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the equivalent scope should be construed as being included in the present invention.

Claims (5)

preparing a ceramic slurry by mixing and milling a ceramic raw material and a solvent;
stirring the ceramic slurry;
sieving the stirred ceramic slurry;
removing heavy metals by magnetism while passing the sieved ceramic slurry through an electromagnet chamber;
manufacturing a ceramic cake by performing a filter press on the heavy metal-removed ceramic slurry to remove water to a predetermined degree;
manufacturing a ceramic body by extruding the ceramic cake; and
Forming and firing the ceramic body to produce a ceramic product having a bending strength of 50 kg/cm ² or more;
Preparing the ceramic slurry
Using a ball having a particle size of less than 12 mm, the ball and the ceramic raw material are mixed in a ratio of 1:1.1 to 1:3 and milled for 9.5 hours to 10.5 hours, and the first ceramic having a particle size of 2 μm or less among the total ceramic powder weight Preparing a ceramic slurry in which the weight of the powder is 10% or more, the particle size is 4 μm or less, and the weight of the second ceramic powder different from the first ceramic powder is 11.5% or more,
preparing a first slurry by milling a first ceramic raw material having a first viscosity when mixed with the solvent in a predetermined ratio into first balls having a first particle size; and
preparing a second slurry by milling a second ceramic raw material having a second viscosity different from the first viscosity when mixed with the solvent in a predetermined ratio with second balls having a second particle size different from the first particle size; do,
In the step of stirring the ceramic slurry, the prepared first slurry and the second slurry are mixed and stirred in a stirring tank.
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