KR20140019895A - Particle-stabilized ceramic foams with a bimodal pore structure and the method for manufacturing the same - Google Patents

Abstract

The present invention relates to a ceramic material and a manufacturing method thereof. In the ceramic material obtained using a colloid particle stabilization mode, material powder of the ceramic material is formed of material powder with an opened pore structure or an uneven shape, and first pores which are closed pores and second pores which are opened pores are formed by mixing the material powder with a surfactant, and drying and sintering the mixture. The manufacturing method of the ceramic material by the present invention comprises the following steps: a material preparation step for preparing the material powder and the surfactant; a ceramic foam production step for mixing the material powder with water to obtain a mixture, adding the surfactant into the mixture, and producing colloid particle stabilized foam; a drying step for drying the ceramic foam produced from the ceramic foam production step; and a sintering step for sintering the dried ceramic foam. In the material preparation step, the material powder is the material powder with the opened pore structure or the uneven shape. According to the present invention, a user can produce the ceramic foam with a dual pore structure without using different kinds of pore inducing substances to the ceramic foam.

Description

TECHNICAL FIELD The present invention relates to a ceramic material having a double-pore structure using a colloid particle stabilization method and a method for manufacturing the ceramic material.

The present invention relates to a ceramic material having a double-pore structure using a colloid particle stabilization method and a method for manufacturing the ceramic material.

Foam refers to a substance in which a gas is held in a liquid or solid state. Most of the substance is formed of a gas and the gas is accommodated in a space formed by a liquid or a thin film. I have.

Among the foam of the above-mentioned type, the solid foam may be classified into an open-cell foam and a closed-cell foam. In an example of the open-cell foam, A bath sponge can be mentioned.

One example of the waste foam is an outdoor mat, and the waste foam has a form in which the gas is surrounded by a solid in the separated region.

On the other hand, the ceramic foam is made of a non-polymer ceramic such as a polyurethane foam, a polystyrene foam and the like in the classification of the solid foam.

Generally, a method of manufacturing a ceramic foam includes a process of impregnating a porous slurry made of a polymer into a ceramic slurry, a process of drying and sintering the ceramic polymer, pyrolyzing and vaporizing the ceramic polymer, and then leaving only the ceramic partition wall structure .

On the other hand, US 2009-00325780 AlUltrastable Particle-Stabilized Foams and Emulsions describes how to prepare ceramic foams using colloidal particle stabilization.

In the disclosed technique, in the preparation of a long-term stabilized wet foam, the colloid particles contained in the suspension are used to fix the gas-liquid interface, and the colloid particles have a volume of at least 1% As shown in FIG.

The ceramic foam thus manufactured has application fields such as heat insulation, soundproofing, absorption of harmful substances, catalytic reaction, and molten metal filtration according to its microstructure.

On the other hand, among the ceramic foams to be produced as described above, the open pores have a wide specific surface area, so that the impregnation of the catalytic material is easy, and the liquid phase and the vapor phase move easily within the foam, but the strength is low.

In addition, among the ceramic foams to be produced as described above, the disposal foam has a relatively high strength as compared with open pores, but has a narrow specific surface area and difficulty in moving the material inside the foam, have.

Therefore, in order to utilize the ceramic foam material in various fields, it is necessary to manufacture a foam having a high specific surface area and proper strength while maintaining the diffusion and movement path of the material.

However, as a method of forming pores at a position where the polymer particles are located at the inner partitions of the disposal hole by mixing the polymer particles with the ceramic particles and then forming the foam and pyrolyzing it, a ceramic foam having a desired shape is implemented And there is a problem that cracks are generated in the ceramic foam along the movement path of the gasified polymer in the pyrolysis reaction.

It is an object of the present invention to provide a ceramic material having a double pore structure by using a colloidal particle stabilizing method which enables the produced ceramic foam to simultaneously include characteristics inherent to the waste foam and characteristics inherent in the open pore foam.

Another object of the present invention is to provide a method of manufacturing a ceramic material having a double pore structure by using a colloid particle stabilization method.

The present invention is a ceramic material produced by using a colloidal particle stabilization method, the raw material powder of the ceramic material is formed of a raw powder having an open pore structure or irregular shape, the raw powder is mixed with a surfactant and then dried and Sintering is characterized in that the first pores which are waste holes and the second pores which are open pores are formed.

The first pore is characterized in that it has a size of 50㎛ to 300㎛.

The second pore is characterized in that it has a size of 0.1㎛ to 10㎛.

The raw powder includes diatomite, aluminum nitride (AlN), silicon nitride (Si₃N₄), silicon carbide (SiC), zirconium carbide (ZrC), tungsten carbide (WC), cordierite, mullite (Mullite), It is characterized in that it is a single powder or a composite powder such as zirconia (ZrO₂).

In the method of manufacturing a ceramic material according to the present invention, a material preparation step of preparing a raw material powder and a surfactant, and a raw material powder prepared in the material preparation step and water are mixed to form a mixture, and then stabilized colloidal particles after adding a surfactant. A ceramic foam manufacturing step of manufacturing a foam, a drying step of drying the ceramic foam produced in the ceramic foam manufacturing step and a sintering step of sintering the dried ceramic foam, the material preparation step in the open material structure as a raw powder Or preparing a raw material powder having an irregular shape.

In the material preparation step, the raw material powder is characterized in that it further comprises a pulverizing process for grinding for more than 24 hours.

According to the present invention, it is possible to produce a ceramic foam having a double pore structure without a different pore inducing material on the ceramic foam.

Therefore, the produced ceramic material has an advantage of maintaining the basic strength of the ceramic waste foam at a certain level while exhibiting functions of catalytic reaction of the ceramic open pore foam, selective permeation, soundproof effect, absorption of harmful substances, and filtration of molten metal .

In addition, it is possible to control the double pore structure of the ceramic foam by controlling only the size and shape of the raw material particles, the colloid particle stabilization process and the sintering process parameters without adding different kinds of materials, thereby simplifying the process and improving the convenience .

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing a double pore structure of a ceramic material according to an embodiment of the present invention. FIG.
2 is a flow chart showing a process of manufacturing a ceramic material according to the present invention.
3 is a Scanning Electron Microscope (SEM) photograph of a diatomaceous earth as a raw material in an embodiment of the present invention.
4 is a scanning electron microscope (SEM) photograph showing the result of ball milling the raw material shown in FIG. 4 for 24 hours.
FIG. 5 is a graph illustrating particle size of a raw material powder of a ceramic material according to the present invention; FIG.
FIG. 6 is a scanning electron microscope (SEM) photograph of a diatomite foam, which is one embodiment of the ceramic material according to the present invention, for identifying primary pores constituting the main part.
FIG. 7 is a partially enlarged view of FIG. 5 so that primary pores and secondary pores, which are essential parts of the present invention, can be identified.
FIG. 8 is an enlarged photograph of a secondary pore, which is a main constituent of the present invention, in FIG.
9 is a graph showing mercury porosity measured by measuring the size of a secondary pore, which is a main constituent of a ceramic material according to the present invention.
10 is a scanning electron microscope (SEM) photograph showing a waste hole of an alumina ceramic foam produced by a conventional colloidal particle stabilization method as a comparative example of the present invention.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. It is to be understood, however, that the spirit of the invention is not limited to the embodiments shown and that those skilled in the art, upon reading and understanding the spirit of the invention, may easily suggest other embodiments within the scope of the same concept.

FIG. 1 is a schematic view showing a double pore structure of a ceramic material according to an embodiment of the present invention.

Referring to the drawings, a ceramic material according to the present invention includes a primary pore 100 in the form of a waste pore having a relatively large diameter, a porous pore 100 having a size smaller than that of the primary pore 100, And a secondary pore 200 in the form of an open pore.

In detail, the ceramic material may be selected from the group consisting of Diatomite, AlN, Si3N4, SiC, ZrC, WC, Cordierite, Mullite, ), Zirconia (ZrO2), and the like are used as raw materials.

In addition, the ceramic material can form a primary pore 100 that can be adjusted in various sizes by selectively adding a surfactant in a manufacturing process.

That is, a surfactant is added to a raw material powder to prepare a suspension containing pores, and the prepared suspension is adjusted to have an interfacial property using a colloid particle stabilization method, and then sintered to form a 50 탆 The primary pores 100 can be formed in the size range of about 300 to 300 mu m.

Meanwhile, the secondary pores 200 are formed by the powder particle size of the raw material in the process of controlling the interface characteristics by the surfactant as described above. The secondary pores 200 are formed in the primary pores 100 in the range of 0.1 [ Mu] m.

The secondary pores 200 are obtained by the spacing between the particles or the pores inside the particles during sintering. If less than 0.1 μm, the pores easily disappear during the sintering process, and pores having a size larger than 10 μm are formed therein. If the size of the particles themselves should have a size of 10㎛ or more, in the colloidal particle stabilization method is difficult to form the first pore 100 when the particles of the raw material powder is 10㎛ or more.

Hereinafter, a method of manufacturing a ceramic material having the above-described structure will be described with reference to the accompanying drawings.

FIG. 2 is a flowchart illustrating a manufacturing process of a ceramic material according to the present invention.

Referring to the drawings, a process for manufacturing a ceramic material according to the present invention comprises: preparing a raw material for forming a double pore and a surfactant to be added (S100); and preparing a ceramic foam (S200) for manufacturing a ceramic foam to be manufactured, a drying step (S300) for drying the produced ceramic foam, and a sintering step (S400) for sintering the dried ceramic foam.

In detail, in the material preparation step (S100), a raw material powder having an open pore structure or a raw material powder having an irregular shape and a surface active material to be added thereto are prepared. A ball-milling process is performed to adjust the particle size.

3 shows a scanning electron microscope (SEM) photograph of diatomaceous earth as a raw material in the embodiment of the present invention. The result of ball milling the raw material shown in FIG. 4 for 24 hours is shown in FIG. FIG. 5 is a graph showing the grain size of the raw material powder of the ceramic material according to the ball milling time according to the present invention. FIG.

Referring to these drawings, in order to simultaneously form the primary pores 100 and the secondary pores 200, which are difficult to realize in the conventional colloid particle stabilization method, It adopts an irregular shape and undergoes a ball-milling process so as to form more effective pores.

That is, as shown in FIG. 3, fine pores are formed in the diatomite, and the particle size of the diatomite as the raw powder is controlled by subjecting the diatomite to ball milling process.

On the other hand, as shown in FIG. 5, when the ball milling process is not performed as shown in FIG. 5, and when it is performed for 4 hours, formation of micropores is not smooth. However, when the ball milling process is performed for 24 hours or more, As shown in FIG.

Therefore, in the present invention, the raw material powder is ball milled for 24 hours or more to control the particle size so that the secondary pores 200 can be smoothly formed.

The surfactant to be mixed with the raw material powder may be various surfactants including hexyldiamine, and the primary pores 100 can be controlled according to the amount and type of the surfactant.

On the other hand, when the material preparation step S100 is completed, the ceramic foam manufacturing step S200 for forming the ceramic foam using the prepared material is performed.

In the step of manufacturing the ceramic foam (S200), air is injected into a mixture obtained by wet mixing the prepared raw material powder and a surfactant by using an agitator to form a foam-like foam.

When the step of manufacturing the ceramic foam (S200) is completed, a drying step (S300) for drying the produced ceramic foam is performed.

In the drying step (S300), the prepared ceramic foam is heated to prepare for sintering.

On the other hand, when the drying step (S300) is completed, the above-described sintering step (S400) is performed.

In the sintering step (S400), the dried ceramic foam is heated and baked so that the primary pores (100) and the secondary pores (200) inside the ceramic foam can be formed at the same time.

After the sintering step (S400) is completed, a final polishing step may be further performed to increase the precision of the surface, if necessary.

Hereinafter, an embodiment of a ceramic material produced according to a method of manufacturing a ceramic material having a double pore structure using the colloid particle stabilization method according to the present invention and a ceramic material having a porous structure using a conventional colloid particle stabilization method will be described below. Will be described with reference to the accompanying drawings.

Diatomite was used as a raw material powder to produce a ceramic foam having a double pore structure, and hexyldiamine was used as a surfactant.

The diatomite as a raw material powder was milled for 24 hours to have a mode value of 5.88 mu m, an average value of 6.22 mu m, and a median value of 4.65 mu m.

The measured raw material powder and surfactant were mixed by wetting, and distilled water was used as a solvent.

The volume of powder and balls was 1: 2 when mixed with raw materials, and the distilled water was filled in mad cow (polypropylene) for 24 hours.

105 mmol / L of hexyldiamine was added to the powder, and the final pH of the mixture was adjusted to 11.8 with aqueous 1 HCl solution.

The mixture was stirred for 5 minutes at 1000 rpm using a stirrer, and then a shaped body of wet foam type in which air was charged into the mixture was prepared.

The thus-prepared wet foam was dried at 30 DEG C for 24 hours so as to be dried well.

The sintering was carried out in an argon atmosphere at a temperature rising / falling rate of 1 占 폚 / min and holding at 1600 占 폚 for 2 hours.

The fracture surface and pore structure were measured using SEM (JSM + 5800, JEOL).

(Comparative Example 1)

Alumina (Al ₂ O ₃ ) was used as a raw material powder to produce general waste ceramic foam using colloidal particle stabilization method and Valeric Acid was used as a surfactant.

The measured raw material powder and surfactant were mixed by wetting, and distilled water was used as a solvent.

Volume ratio of powder and balls was 1: 2 in raw material mixing and distilled water was filled in madpowder (polypropylene) for 24 hours.

3.1 g / L of Valeric Acid was added to the powder, and the final pH of the mixture was titrated to 4.7 using 1NaOH aqueous solution.

The mixture was stirred for 5 minutes at 100 rpm using a stirrer, and then a shaped body of wet foam type in which air was charged into the mixture was prepared

Drying was carried out at 30 DEG C for 24 hours so that the alumina ceramic foam was dried well.

The sintering was carried out in an argon atmosphere at a temperature rising / falling rate of 1 占 폚 / min and holding at 1600 占 폚 for 2 hours.

The fracture surface and pore structure were measured using SEM (JSM + 5800, JEOL).

6, there is shown a scanning electron microscope (SEM) photograph for confirming the primary pore, which is a main constituent in the diatomite foam, which is one embodiment of the ceramic material according to the present invention, FIG. 5 is a partially enlarged view showing the primary porosity and secondary porosity, which are major components of the invention. FIG. 8 is an enlarged view of the secondary pores of the present invention, and FIG. 9 is a graph showing the relationship between the secondary pores of the ceramic material according to the present invention. A porosity measurement graph is shown.

Referring to these drawings, as shown in the figure, a ceramic material manufactured using the colloidal particle stabilization method according to the present invention is formed with a number of primary pores having a relatively large diameter and is disposed along the partition walls of the primary pores. It is confirmed that numerous secondary pores are formed.

Therefore, both the disposal hole and the open pore structure are included, and functions according to the respective characteristics can be exhibited.

Meanwhile, FIG. 10 shows a scanning electron microscope (SEM) photograph of a waste hole of an alumina ceramic foam manufactured by a conventional colloidal particle stabilization method as a comparative example of the present invention.

As shown in (Comparative Example 1), the produced ceramic foam has only the waste pores, but no open pores as shown in [Example 1] are observed in the partition walls of the pore.

100 ..... first pore 200 ..... second pore
300 ..... partition wall
S100 ..... material preparing step S200 ..... ceramic foam manufacturing step
S300 ..... Drying step S400 ..... Sintering step

Claims (6)

In a ceramic material produced using a colloidal particle stabilization system,
The raw material powder of the ceramic material is formed of a raw material powder having an open pore structure or irregular shape,
After the raw material powder is mixed with the surfactant, it is dried and sintered to form the first pores, which are discarded pores, and the second pores, which are open pores.
The method of claim 1,
The first pore is a ceramic material having a double pore structure by using a colloidal particle stabilization method having a size of 50㎛ to 300㎛.
The method of claim 1,
The second pore is a ceramic material having a double pore structure by using a colloidal particle stabilization method having a size of 0.1 ㎛ to 10 ㎛.
The method of claim 1,
The raw powder includes diatomite, aluminum nitride (AlN), silicon nitride (Si₃N₄), silicon carbide (SiC), zirconium carbide (ZrC), tungsten carbide (WC), cordierite, mullite (Mullite), Ceramic material having a double pore structure using a colloidal particle stabilization method, characterized in that it is a single powder or a composite powder such as zirconia (ZrO₂).
Preparing a material for preparing a raw material powder and a surfactant;
Preparing a ceramic foam by mixing a raw material powder prepared in the material preparation step with water to form a mixture, and adding a surfactant to prepare a colloidal particle stabilized foam;
A drying step of drying the ceramic foam produced in the ceramic foam manufacturing step; And
And a sintering step of sintering the dried ceramic foam,
In the material preparation step
A method of producing a ceramic material having a double pore structure by using a colloidal particle stabilization method characterized in that to prepare a raw material powder having an open pore structure or irregular shape as the raw material powder.
The method of claim 5, wherein in the material preparation step,
Method of producing a ceramic material having a double pore structure by using a colloidal particle stabilization method characterized in that the grinding step of grinding the raw material powder for more than 24 hours.

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