KR20210059099A - Porous ceramic foam for plasma generating apparatus and manufacturing thereof - Google Patents

Abstract

The present invention relates to a porous ceramic foam for a plasma generating apparatus and a manufacturing method thereof. More particularly, the present invention relates to a composition for a porous ceramic foam for a plasma generating apparatus, which is excellent in gas permeability and dielectric properties, which can have a large area, and which can be thin. A slurry composition for the porous ceramic foam includes diatomaceous earth powder, clay-based powder, a binder, and a dispersant.

Description

Porous ceramic foam for plasma generating apparatus and manufacturing method thereof TECHNICAL FIELD

The present invention relates to a porous ceramic foam for a plasma generating device and a method of manufacturing the same. In more detail, the present invention relates to a composition for a porous ceramic foam for a plasma generating device, which has excellent gas permeability and dielectric properties, and is capable of making a large area and thinner, and a porous ceramic foam for a plasma generating device using the same, and a method of manufacturing the same.

Porous ceramics have received a lot of attention because of their superior thermal stability and chemical stability compared to porous polymers and porous metals. That is, the porous ceramic is superior in acid resistance and high temperature stability, and has high biological resistance compared to the porous polymer, and has excellent durability. In addition, the porous ceramic has a high porosity and has an open pore structure, which is a major advantage.

Porous ceramics are applied as dust control filters for automobiles and power plants, separators for gas and water purification, insulation materials, next-generation fuel cells, catalysts, sensors, human-friendly materials, etc., because porous ceramics can utilize the unique properties of the above-mentioned ceramics. .

Materials for porous ceramic separators currently widely studied or used are alumina (Al ₂ O ₃ ), titania (TiO ₂ ), silica (SiO ₂ ), zirconia (ZrO ₂ ), mullite (3Al ₂ O ₃ ·2SiO ₂ ) or carbonization. Silicon (SiC) and the like.

There is a polymer template method as a method of manufacturing a reticulated porous ceramic using an alumina material. The polymer template method is a process of coating a polymer template with a ceramic slurry, drying and sintering. The polymer dispersed between the formed ceramic slurry is thermally decomposed and vaporized to finally form a network with pores. This is a method of leaving only porous ceramics.

However, in general, it is not easy to manufacture a reticulated porous ceramic having a high PPI (Pores Per Inch) by the polymer template method. 1A is a photograph of a reticulated porous alumina foam prepared by a conventional polymer template method, FIG. 1B is a μ-CT cross-sectional photograph of the reticulated porous alumina foam of FIG. 1A, and FIG. 1C is a μ- This is a CT 3D reconstructed picture. 1 and 2A to 2C, it is difficult to uniformly and completely coat the inner pores of the polymer template with a ceramic slurry.

It is also very difficult to remove excess ceramic slurry from the polymer template and to apply a thin film ceramic coating on the strut wall of the polymer template to be removed.

As a result, many pores are caused by the ceramic slurry that has not been removed, and the two main advantages of the reticulated porous ceramic, such as low density and high transmittance, are seriously deteriorated.

1D is an enlarged photograph of a partition wall portion of a reticulated porous alumina foam having closed pores. As shown in FIG. 1D, the partition wall of the prepared alumina ceramic foam has a limit in gas permeability due to the closed hole.

Therefore, it is difficult to provide a porous ceramic material for a gas-permeable plasma generating device, which has excellent gas permeability and dielectric properties, and is capable of making a large area and thinner, with a conventional reticulated porous ceramic and a method of manufacturing the same. Until now, research on dielectric ceramic materials for gas-permeable plasma generators is insufficient.

As a background technology of the present invention, a porous ceramic hollow fiber inorganic support prepared by using inorganic particles selected from alumina powder, zirconia powder, and silica as the main raw material in Korean Patent Publication No. 10-0508692 is used in a temperature range of 1300 to 1400°C. A manufacturing method of manufacturing by sintering is suggested.

It is an object of the present invention to provide a composition capable of manufacturing a porous ceramic foam for a plasma generating device, which has excellent gas permeability and dielectric properties, and is capable of making a large area and thinner.

Another object of the present invention is to provide a porous ceramic foam for a plasma generator that has uniform and various types of open pores, has excellent gas permeability and dielectric properties, has a large area, and is thinner.

Another object of the present invention is to provide a method for efficiently manufacturing a porous ceramic foam for a plasma generating device that has excellent gas permeability and dielectric properties with uniform and various types of open pores, and is capable of making a large area and thinner. .

Other objects and advantages of the present invention will become more apparent by the following detailed description, claims and drawings.

According to one aspect, 55 to 75 parts by weight of diatomaceous earth powder; 15 to 25 parts by weight of clay powder; 10 to 15 parts by weight of a binder; And 1 to 5 parts by weight of a dispersant; containing, a slurry composition for a porous ceramic foam for a plasma generating device is provided.

According to an embodiment, the clay-based powder is bentonite, hectorite, kaolinite, halloysite, pyropphyllite, laponite, montmo It may be one or more selected from montmorilonite, mica, illite, talc, and smectite.

According to an embodiment, the binder may be at least one selected from polyethylene glycol (PEG), polyvinyl alcohol, acrylic acid ester, methacrylic acid ester, and polyvinyl butyral.

According to an embodiment, the dispersant may be at least one selected from ammonium polymethacrylate, polycarboxylic acid, and polysaccharide.

According to another aspect, a porous ceramic foam made of the slurry composition for porous ceramic foams described herein, characterized in that the pore density is 45 to 100 PPI (Pore per Inch), and has gas permeability and dielectric properties at the same time, plasma A porous ceramic foam for a generator is provided.

According to an embodiment, the porous ceramic foam for a plasma generator may have a density of 0.25 to 0.5 g/cm 3.

According to an embodiment, the porous ceramic foam for a plasma generating device may have an insulation breakdown strength of 14 kV/cm or more.

According to an embodiment, the porous ceramic foam for a plasma generator may have a compressive strength of 0.2 MPa or more.

According to an embodiment, the porous ceramic foam for a plasma generating device may have a porosity of 50 to 90 vol%.

According to an embodiment, the porous ceramic foam for a plasma generator may have an average pore size of 1 to 10 μm inside the partition wall.

According to an embodiment, the porous ceramic foam for a plasma generator may have a size of 100 mm x 100 mm x 10 mm or more.

According to another aspect, i) adding a solvent to the slurry composition for a porous ceramic foam for a plasma generating device described herein and providing a slurry; ii) applying the slurry provided in step i) to the open organic foam; And iii) step ii) forming a porous ceramic foam such that the pore density is 45 to 100 PPI (Pore per Inch) by sintering the applied pore organic foam. A manufacturing method is provided.

According to an embodiment, the method of manufacturing a porous ceramic foam for a plasma generator may further include homogenizing the slurry in step i).

According to an embodiment, in the method of manufacturing a porous ceramic foam for a plasma generating device, in step ii), the open organic foam may be a polyurethane foam, a polyvinyl chloride foam, a polystyrene foam, a latex foam, or a cellulose foam.

According to an embodiment, the method of manufacturing a porous ceramic foam for a plasma generating device may further include drying at room temperature after coating in step ii).

According to an embodiment, the method of manufacturing a porous ceramic foam for a plasma generating device may further include removing the binder and the open organic foam by heating after coating in step ii).

According to an embodiment, the method of manufacturing a porous ceramic foam for a plasma generating device may be sintered at 1150 to 1250° C. in step iii).

According to an embodiment, it is possible to provide a porous ceramic foam for a plasma generator that has uniform and various types of open pores, has excellent gas permeability and dielectric properties, and has a large area and thinner.

According to an embodiment, it is possible to efficiently manufacture a porous ceramic foam for a plasma generator that has uniform and various types of open pores, has excellent gas permeability and dielectric properties, and has a large area and thinner.

According to an embodiment, it is possible to manufacture a porous ceramic foam for a plasma generating device that is eco-friendly and has excellent gas permeability and dielectric properties at low cost, and has a large area and is thinner.

1A is a photograph of a reticulated porous alumina foam manufactured by a conventional polymer template method.
1B is a µ-CT cross-sectional photograph of the reticulated porous alumina foam of FIG. 1A.
1C is a μ-CT 3D reconstructed photograph of the reticulated porous alumina foam of FIG. 1A.
1D is an enlarged photograph of a partition wall portion of a reticulated porous alumina foam having closed pores.
2 shows the viscosity of the slurry for a reticulated porous alumina foam and the viscosity of the slurry for a reticulated porous diatomaceous earth foam.
3A is a photograph showing a polyurethane foam template with varying pore densities.
3B is a photograph showing a reticulated porous diatomaceous earth foam manufactured using the polyurethane foam template of FIG. 3A.
4A is an enlarged photograph of a partition wall portion of a reticulated porous diatomaceous earth foam having open pores.
Figure 4b is a µ-CT cross-sectional photograph of the reticulated porous diatomaceous earth foam.
Figure 4c is a μ-CT 3D reconstructed image of the reticulated porous diatomaceous earth foam.
5A is a graph showing pore size distribution characteristics of a reticulated porous diatomaceous earth foam.
5B is a graph showing pore size distribution characteristics of a reticulated porous alumina foam.
6A is a graph showing the density of a reticulated porous diatomaceous earth foam and a reticulated porous alumina foam.
6B is a graph showing the compressive strength of a reticulated porous diatomaceous earth foam and a reticulated porous alumina foam.
6C is a graph showing the dielectric breakdown strength of reticulated porous diatomaceous earth foam and reticulated porous alumina foam having different pore densities.

Objects, specific advantages, and novel features of the present disclosure will become more apparent from the following detailed description and embodiments in conjunction with the accompanying drawings.

Prior to this, terms or words used in the present specification and claims should not be interpreted in a conventional and dictionary meaning, and the inventor may appropriately define the concept of terms in order to describe his own invention in the best way. It should be interpreted as a meaning and concept consistent with the technical idea of the present disclosure based on the principle that there is.

In this specification, when a component such as a layer, portion, or substrate is described as being “on”, “connected”, or “coupled” to another component, it is directly “on”, “on” the other component. It may be connected" or "coupled", and may be interposed between one or more other components. In contrast, if a component is described as being "directly over", "directly connected", or "directly coupled" of another component, no other component can be interposed between the two components. .

The terms used in this specification are used only to describe specific embodiments, and are not intended to limit the present disclosure. Singular expressions include plural expressions unless the context clearly indicates otherwise.

In the present specification, terms such as'include' or'have' are intended to designate the presence of features, numbers, steps, actions, components, parts, or a combination thereof described in the specification, but one or more other features. It is to be understood that the presence or addition of elements or numbers, steps, actions, components, parts, or combinations thereof does not preclude in advance.

In the present specification, when a part "includes" a certain component, it means that other components may be further included rather than excluding other components unless otherwise stated. In addition, throughout the specification, "on" means to be positioned above or below the target portion, and does not necessarily mean to be positioned above the direction of gravity.

In the present disclosure, since various transformations can be applied and various embodiments can be provided, specific embodiments will be illustrated in the drawings and will be described in detail in the detailed description. However, this is not intended to limit the present disclosure to a specific embodiment, it is to be understood as including all conversions, equivalents, and substitutes included in the spirit and scope of the present disclosure. In describing the present disclosure, when it is determined that a detailed description of a related known technology may obscure the subject matter of the present disclosure, a detailed description thereof will be omitted.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings, and in the description with reference to the accompanying drawings, the same or corresponding constituent elements are assigned the same reference numbers, and redundant descriptions thereof will be omitted. do.

The slurry composition for a porous ceramic foam for a plasma generator of the present application comprises: 55 to 75 parts by weight of diatomaceous earth powder; 15 to 25 parts by weight of clay powder; 10 to 15 parts by weight of a binder; And 1 to 5 parts by weight of a dispersant.

The diatomaceous earth is an aggregate of sediments composed of shells of floating algae called diatome having an average size of 10 to 100 μm. In life, these diatoms absorb silica from water and make cell walls. When the sediment of these diatoms is hardened and hardened to form sedimentary rocks, it is also called diatomite, which is also commonly referred to as diatomite in the sense of ore. Diatomaceous earth consists mostly of amorphous silica, and some crystalline silica is present. Because of the complex structure of the diatom itself and the primary and secondary pores of its shell, diatomaceous earth has a very low density, and for this reason, diatomaceous earth is used as a very good filter aid, adsorbent, additive, carrier, and abrasive.

When the slurry composition for porous ceramic foams containing diatomaceous earth as a main component as described above is used, the porous ceramic foam for plasma generators that has uniform and various types of open pores, has excellent gas permeability and dielectric properties, has a large area and is thinner, can be obtained. Can provide.

The diatomaceous earth powder may be uniformly included in an amount of 55 to 75 parts by weight, and may be suitable for providing a porous ceramic foam for a plasma generator having excellent gas permeability and dielectric properties while having a variety of open pores, and further 55 to 65 parts by weight. It may be suitable. Although not limited thereto, if the diatomaceous earth powder is contained in an amount of less than 55 parts by weight, gas permeability may be reduced, if it exceeds 75 parts by weight, mechanical properties may be deteriorated, and if it exceeds 80 parts by weight, the compressive strength of a degree that cannot be measured. Due to the deterioration, it may be difficult to use in the manufacture of the porous ceramic foam for the plasma generator of the present application.

The type of diatomaceous earth powder may be appropriately selected from among dried powder, calcined powder, or flux calcined powder as needed. For reference, when a flux-calcined powder is used as the diatomaceous earth powder, it is possible to use a relatively small amount of flux compared to the case of not adding an additional flux or using other types of powder.

The clay-based powder is uniformly included in an amount of 15 to 25 parts by weight and may be suitable for improving gas permeability and dielectric properties. Although not limited thereto, the clay-based powder is bentonite, hectorite, kaolinite, halloysite, pyropphyllite, laponite, and montmo It may be one or more selected from montmorilonite, mica, illite, talc, and smectite. Although not limited thereto, kaolinite was used in the examples of the present application. The addition of clay-based powder provides plasticity to improve moldability, and not only improves the mechanical strength of the finally produced support, but also increases the strength of the connection part of the network structure between particles in a microstructure. Filter clogging due to particle separation due to pressure during gas permeation can be suppressed.

The binder may be included in an amount of 10 to 15 parts by weight, which may be suitable for improving the formability and mechanical strength of the porous ceramic foam. Although not limited thereto, the binder may be one or more selected from polyethylene glycol (PEG), polyvinyl alcohol, acrylic acid ester, methacrylic acid ester, and polyvinyl butyral.

To include the dispersant in an amount of 1 to 5 parts by weight may be suitable for improving the formability and mechanical strength of the porous ceramic foam for a plasma generator. Although not limited thereto, the dispersant may be at least one selected from ammonium polymethacrylate, polycarboxylic acid, and polysaccharide.

The slurry composition for a porous ceramic foam for a plasma generating device of the present application may further include a flux, a pore former, and the like serving as a strength enhancer.

In addition, the raw material powder may further contain oxide particles or metal particles that play a role of inhibiting the growth of viruses or bacteria in order to prevent contamination when used as a filter for air purification in the long term, if necessary. For example, TiO ₂ powder, Ni powder, Cu powder, etc. may be additionally added to the mixed powder for the above purpose.

The porous ceramic foam for a plasma generating device of the present application is a porous ceramic foam made of the slurry composition for a porous ceramic foam for a plasma generating device described herein, and has a pore density of 45 to 100 PPI (Pore per Inch), and gas permeability and dielectric material. It is characterized by having characteristics at the same time.

The pore density of the porous ceramic foam for the plasma generator of the present application may be 45 to 100 PPI (Pore per Inch), which may be suitable for improving gas permeability and dielectric properties, and 45 to 90 PPI may be more suitable, and 45 To 85 PPI may be even more suitable, 50 to 85 PPI may even more suitable, and 60 to 85 PPI may even more suitable. Although not limited thereto, when the pore density of the porous ceramic foam for the plasma generator is less than 45 PPI, it may not have sufficient gas permeability and dielectric properties, and when it is less than 30 PPI, electricity may occur and thus may not play the role of the dielectric.

The porous ceramic foam for a plasma generator of the present application may have a density of 0.25 to 0.5 g/cm 3, which may be suitable for improving gas permeability and dielectric properties. When the density of the porous ceramic foam for a plasma generator is less than 0.25 g/cm 3, the mechanical strength may decrease, and when it exceeds 0.5 g/cm 3, the gas permeability may decrease.

In the porous ceramic foam for a plasma generating device of the present application, a dielectric breakdown strength of 14 kV/cm or more may be suitable for improving mechanical strength and dielectric properties, and 15 kV/cm or more may be more suitable. When the dielectric breakdown strength of the porous ceramic foam for a plasma generator is less than 14kV/cm, mechanical strength and dielectric properties are deteriorated, and thus it may be difficult to apply it as a porous ceramic foam for a plasma generator.

The porous ceramic foam for a plasma generator of the present application may have a compressive strength of 0.2 MPa or more to improve gas permeability and dielectric properties. When the compressive strength of the porous ceramic foam for a plasma generator is less than 0.2 MPa, the mechanical strength is lowered, and thus it may be difficult to apply it as a porous ceramic foam for a plasma generator.

The porous ceramic foam for a plasma generator of the present application may have a porosity of 50 to 90 vol%, which may be suitable for improving gas permeability and dielectric properties. When the porosity of the porous ceramic foam for a plasma generator is less than 50 vol%, the gas permeability may decrease, and the porosity is greater than 90 vol% and the mechanical strength decreases, so that it may be difficult to apply as a porous ceramic foam for a plasma generator.

The porous ceramic foam for the plasma generator of the present application may have an average pore size of 1 to 10 μm inside the partition wall. The porous ceramic foam of the present application has a hybrid open pore structure including a large number of fine open pores inside the partition wall and external pores by a template, and is suitable for improving gas permeability and dielectric properties. Furthermore, it may be possible to capture pathogens such as bacteria by the micropores.

The porous ceramic foam for the plasma generator of the present application may be formed in a size of 100 mm x 100 mm x 10 mm or more, preferably 150 mm x 150 mm x 10 mm or more, and more preferably 200 mm x 200 mx 10 mm or more. It can be formed as, it is possible to provide a porous ceramic foam for a plasma generating device capable of making a large area and thinner.

The method of manufacturing a porous ceramic foam for a plasma generating device of the present application includes: i) adding a solvent to the slurry composition for a porous ceramic foam for a plasma generating device described herein and providing a slurry; ii) applying the slurry provided in step i) to the open organic foam; And iii) step ii) forming a porous ceramic foam such that a pore density of 45 to 100 PPI (Pore per Inch) is formed by sintering the applied perforated organic foam.

Step i) is a step of adding a solvent to the slurry composition for a porous ceramic foam for a plasma generator described herein and providing a slurry, but is not limited thereto, but the solvent may be distilled water. The diatomaceous earth slurry for porous ceramic foam according to the present invention has a lower viscosity than the alumina slurry (FIG. 2), and can penetrate well into small cells of an open organic foam of 60 PPI or more, so that the open organic foam can be uniformly and thinly applied as a whole. In addition, since the diatomaceous earth slurry composition of the present application remaining in the manufacturing process does not block interconnecting pores unlike the alumina slurry composition, it is not necessary to completely remove it. Therefore, due to the irregular and porous characteristics of the diatomaceous earth particles, even when a high PPI polymer template of 60 PPI or more is used, a reticulated porous ceramic foam can be easily manufactured.

It may further comprise the step of homogenizing the slurry in step i). Although not limited thereto, the homogenization may be performed by ball milling, planetary milling, or attraction milling in a wet mixing method.

Next, step ii) is a step of applying the slurry to the porous organic foam, and the porous organic foam may be polyurethane foam, polyvinyl chloride foam, polystyrene foam, latex foam, or cellulose foam. 3A shows a polyurethane foam template with varying pore densities.

The application may be carried out by applying the slurry to the surface of the open organic foam by a known coating method such as dip-coating.

It may further include a step of drying at room temperature after application in step ii). In the drying step, the slurry for the porous ceramic foam is in close contact with the open organic foam and may contribute to improvement of mechanical strength.

It may further include a step of removing the binder and the open organic foam by heating after application in step ii). Although not limited thereto, the heating may be performed at a temperature of 400° C. or higher.

The next step iii) is a step of sintering the applied perforated organic foam to form a porous ceramic foam with a pore density of 45 to 100 PPI (Pore per Inch), wherein a porous ceramic foam having the same shape as the pore organic foam Will be formed.

Although not limited thereto, the temperature during the sintering may be 1150 to 1250° C., which may be suitable for forming a three-dimensional pore network formed by interconnecting diatomaceous earth powder particles, and 1200° C. may be more suitable. In addition, although not limited thereto, heating at a rate of 5° C./min and maintaining at 1200° C. for 1 hour or more may be suitable for forming a three-dimensional pore network.

That is, when the sintering temperature exceeds 1250 °C, due to _{impurities in diatomaceous earth such as Na 2} O, K ₂ O, Al ₂ O ₃ , CaO, and MgO, clear coalescence and average particle size of diatomaceous earth particles Begins to decrease. Then, the inherent irregular and porous characteristics of the diatomaceous earth particles are reduced, and the reason for introducing the porous diatomaceous earth particles may be significantly reduced.

4A to 4C, the porous ceramic foam for a plasma generating device manufactured by the method of manufacturing a porous ceramic foam for a plasma generating device of the present invention has micropores in the partition wall and can trap pathogens such as bacteria, Gas permeability can also be improved. 5A to 6C, unlike the porous alumina foam, the porous ceramic foam for a plasma generator of the present application has a remarkably increased micropore and an insulation breakdown strength may increase. Therefore, the porous ceramic foam of the present application can be usefully applied to a gas-permeable plasma generator as a filter material that functions as a dielectric and an insulator.

Hereinafter, the present invention will be described in more detail through examples. However, these examples are for illustrative purposes only, and the scope of the present invention will not be construed as being limited by these examples.

[ Example ]

Example . plasma Manufacture of porous ceramic foam for generator

For the production of porous ceramic foams using the replica method, commercial polyurethane foams with a size of 10, 25, 45, 60, and 85 pores per inch (PPI) and 50 mm x 50 mm x 10 mm as a template (SKB Tech, Korea ) Was used.

Diatomaceous earth slurry was prepared to coat polyurethane foam, and 100 g of diatomaceous earth (Celite 499, Celite Corp, USA) was added to 250 ml of distilled water to prepare a porous diatomaceous earth foam (more precisely, diatomaceous earth-kaolin composite foam). , Kaolin (Kaolin, Sigma-Aldrich, USA) of up to 30 g was mixed to improve strength. 4 g of DARVAN C-N was used as a dispersing agent, and 20 g of PVA (PVA 500, Junsei Chemical, Japan) was used as an organic binder.

The mixed diatomaceous earth slurry was ball milled using an alumina ball for 4 hours for complete mixing.

Next, the mixed diatomaceous earth slurry was coated on a polyurethane foam template and then dried at room temperature for 24 hours.

At this time, the coating method followed the general replica method. That is, the polyurethane foam cut to a predetermined size was immersed in a diatomaceous earth slurry, and when it was thought that it was sufficiently coated, it was taken out and squeezed out to remove the coated slurry. At this time, the composition of the slurry is important in order to have the condition that the thin diatomaceous earth coating layer has a viscosity that can be formed on the polyurethane foam. If the viscosity is too high, the slurry cannot penetrate into the polyurethane foam, and if the viscosity is too low, the slurry does not adhere to the surface of the polyurethane foam.

The dried specimen was held at 400° C. for 1 hour to pyrolyze the organic binder and the polyurethane foam, and finally sintered at 1200° C. for 1 hour.

Comparative example . Fabrication of reticulated porous alumina foam

To prepare a reticulated porous alumina foam for comparison of properties, 130 g of alumina (AKP-30, Sumitomo Chemical Co. Ltd., Japan) was added to 100 ml of distilled water, and 1.5 g of methyl cerulose (Sigma-Aldrich) was added. , USA) was mixed as a viscosity enhancer. 4 g of DARVAN C-N (Vanderbilt Minerals, USA) was used as a dispersant, and 5 g of PVA (PVA 500, Junsei Chemical, Japan) was used as an organic binder.

The mixed slurry was ball milled using an alumina ball for 4 hours for complete mixing. The ball-milled slurry was coated on a polyurethane foam and dried at room temperature for 24 hours.

The dried specimen was held at 400° C. for 1 hour to pyrolyze the organic binder and polyurethane foam, and finally sintered at 1600° C. for 1 hour.

Experimental example . Analysis of properties of porous ceramic foam

For the pore structure analysis, a mercury porosimeter (Autopore IV 9510, Micromeritics, USA) and a scanning electron microscope (SEM, JSM-5800, JEOL, Japan) were used.

For viscosity measurement, a viscometer using a rotary rheometer (Discovery HR-1, TA Instruments, USA) was used.

For 3D micro CT analysis, μ-CT equipment (μ-CT, XT H 160, Nikon, Japan) was used.

Instron 4206 equipment (Instron, USA) was used to measure the compressive strength.

In order to measure the dielectric breakdown strength, a specimen of 150 mm x 150 mm x 10 mm was prepared and measured according to ASTM D149-97a “Standard Test Method for Dielectric Breakdown Voltage and Dielectric Strength of Solid Electrical Insulating Materials at Commercial Power Frequencies”.

result

As shown in FIG. 2, the diatomaceous earth slurry for porous ceramic foam according to the present application has a lower viscosity than the alumina slurry, and thus it can penetrate well into small cells of an open organic foam of 60 PPI or more, so that the open organic foam can be uniformly and thinly applied as a whole. have. Therefore, the diatomaceous earth slurry for a porous ceramic foam according to the present application is suitable for manufacturing a reticulated porous ceramic.

3A is a photograph showing a commercial polyurethane foam template having a pore density of 10, 25, 45, 60, and 80 PPI, respectively. 3B is a photograph showing a reticulated porous diatomaceous earth foam manufactured using the polyurethane foam template of FIG. 3A. As shown in FIG. 3B, a reticulated porous diatomaceous earth foam having the same shape as the polyurethane foam template of FIG. 3A and having uniform pores was formed.

4A is an enlarged photograph of a partition wall portion of a reticulated porous diatomaceous earth foam having open pores. Unlike the partition wall of the reticulated porous alumina foam shown in FIG. 1D, a plurality of micropores are formed in the partition wall of the reticulated porous diatomaceous earth foam.

FIG. 4B is a μ-CT cross-sectional photograph of a reticulated porous diatomaceous earth foam, and FIG. 4c is a μ-CT 3D reconstructed photograph of a reticulated porous diatomaceous earth foam. As shown in FIGS. 4B and 4C, unlike the reticulated porous alumina foam shown in FIGS. 1B and 1C, the pore channels under the surface are not severely blocked or the internal-connectivity is not perfect. Therefore, the success or failure of the production of reticulated porous diatomaceous earth does not depend on clogging of the pore channels by excessive diatomaceous earth particles that have not been removed. This is also confirmed by the pore structure data by the mercury porosimeter.

5A is a graph showing pore size distribution characteristics of a reticulated porous diatomaceous earth foam, and FIG. 5B is a graph showing pore distribution characteristics of a reticulated porous alumina foam. As shown in FIG. 5A, as the PPI increases, the pore size and pore volume of the reticulated porous diatomaceous earth slightly increase. This is because the number of porous partitions and voids formed by excessive diatomaceous earth particles increase. In contrast, as the PPI increases, the pore size and pore volume of the reticulated porous alumina hardly increase. This is because the number of partition walls without pores of alumina does not affect the overall pore size distribution, and there is little possibility of generation of voids due to excessive alumina particles, which is highly likely to occur in the production of high PPI of reticulated porous ceramics. This is because excess alumina usually clogs the pore channels.

6A is a graph showing the density of a reticulated porous diatomaceous earth foam and a reticulated porous alumina foam. 6B is a graph showing the compressive strength of a reticulated porous diatomaceous earth foam and a reticulated porous alumina foam.

6A and 6B, the density and compressive strength of the reticulated porous diatomaceous earth are lower than the density and compressive strength of the reticulated porous alumina regardless of PPI, but the difference is not large. This may be due to the sintering temperature and time.

6C is a graph showing the dielectric breakdown strength of a reticulated porous diatomaceous earth foam and a reticulated porous alumina foam having different pore densities. Until now, there have been few studies on the dielectric breakdown strength of reticulated porous ceramics. As shown in FIG. 6C, the reticulated porous diatomaceous earth foam has a similar level of dielectric breakdown strength at a pore density of 45 PPI even though the density and compressive strength are lower than that of the reticulated porous alumina foam, and the insulation of the reticulated porous diatomaceous earth foam from 60 PPI or higher The breaking strength was higher. For reference, the dielectric breakdown strength of reticulated porous ceramics with pore densities of 10 and 25 PPI could not be measured by arc-generation induced by interconnected pores between electrodes.

Considering the experimental data as described above, the reticulated porous diatomaceous earth can have a lower density and excellent dielectric breakdown strength compared to the reticulated porous alumina, and has good mechanical strength while being manufactured at an inexpensive process cost. It can be usefully used as In particular, it can be usefully used in plasma generating air purifiers.

Although specific embodiments have been described in the detailed description of the present invention, various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention is not limited to the described embodiments, and should be defined by the claims to be described later and equivalents to the claims.

Claims (17)

55 to 75 parts by weight of diatomaceous earth powder;
15 to 25 parts by weight of clay powder;
10 to 15 parts by weight of a binder; And
1 to 5 parts by weight of a dispersant; containing,
Slurry composition for porous ceramic foam for plasma generator. The method of claim 1,
The clay-based powder is bentonite, hectorite, kaolinite, halloysite, pyropphyllite, laponite, montmorilonite, Mica (mica), illite (illite), talc (talc), and one or more selected from smectite (smectite), a slurry composition for a porous ceramic foam for a plasma generator. The method of claim 1,
The binder is at least one selected from polyethylene glycol (PEG), polyvinyl alcohol, acrylic acid ester, methacrylic acid ester, and polyvinyl butyral, a slurry composition for a porous ceramic foam for a plasma generating device. The method of claim 1,
The dispersant is at least one selected from ammonium polymethacrylate, polycarboxylic acid, and polysaccharide, a slurry composition for a porous ceramic foam for a plasma generator. A porous ceramic foam made of the slurry composition for a porous ceramic foam according to any one of claims 1 to 4,
The pore density is 45 to 100 PPI (Pore per Inch),
A porous ceramic foam for a plasma generating device, characterized in that it has gas permeability and dielectric properties at the same time. The method of claim 5,
Porous ceramic foam for a plasma generator having a density of 0.25 to 0.5 g/cm 3. The method of claim 5,
Porous ceramic foam for plasma generators with insulation breakdown strength of 14kV/cm or more. The method of claim 5,
Porous ceramic foam for plasma generators with a compressive strength of 0.2 MPa or more. The method of claim 5,
Porosity is 50 to 90 vol%, a porous ceramic foam for a plasma generator. The method of claim 5,
Porous ceramic foam for a plasma generator having an average pore size of 1 to 10 µm inside the partition wall. The method of claim 5,
Porous ceramic foam for plasma generators with dimensions of 100 mm x 100 mm x 10 mm or more. i) adding a solvent to the slurry composition for a porous ceramic foam for a plasma generating device according to any one of claims 1 to 4 and providing a slurry;
ii) applying the slurry provided in step i) to the open organic foam; And
iii) step ii) forming a porous ceramic foam such that a pore density of 45 to 100 PPI (Pore per Inch) is formed by sintering the applied perforated organic foam. Way. The method of claim 12,
A method for producing a porous ceramic foam for a plasma generating device, further comprising the step of homogenizing the slurry in step i). The method of claim 12,
In step ii), the pore-opening organic foam is polyurethane foam, polyvinyl chloride foam, polystyrene foam, latex foam, or cellulose foam, a method of manufacturing a porous ceramic foam for a plasma generator. The method of claim 12,
A method of manufacturing a porous ceramic foam for a plasma generating device, further comprising the step of drying at room temperature after application in step ii). The method of claim 12,
The method of manufacturing a porous ceramic foam for a plasma generating device further comprising a; step of removing the binder and the open organic foam by heating after coating in step ii). The method of claim 12,
Sintering at 1150 to 1250 °C in step iii), a method of manufacturing a porous ceramic foam for a plasma generator.

Images