KR101774334B1

KR101774334B1 - Method for manufacturing porous composite ceramics and porous composite ceramics manufactured by the same

Info

Publication number: KR101774334B1
Application number: KR1020150189898A
Authority: KR
Inventors: 황찬규; 김익진
Original assignee: 서울벤처대학원대학교 산학협력단; 황찬규; 김익진
Priority date: 2015-12-30
Filing date: 2015-12-30
Publication date: 2017-09-04
Also published as: KR20170079394A

Abstract

The present invention relates to a method for producing porous composite ceramics and a porous composite ceramics produced thereby. According to the present invention, by producing porous composite ceramics by direct foaming using silica and silicon carbide, It is possible to provide porous composite ceramics having porosity and high porosity, exhibiting excellent durability and thermal conductivity, and particularly excellent in shape stability.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for producing porous composite ceramics, and a porous composite ceramics produced by the method. BACKGROUND ART < RTI ID = 0.0 >

The present invention relates to a method for producing porous composite ceramics and porous composite ceramics produced thereby, and more particularly, to a method for producing porous composite ceramics by direct foaming using silica and silicon carbide, And high porosity, and exhibits excellent stability, and a porous composite ceramics produced by the method.

Porous ceramics refers to a solid having pores of various sizes in a solid such as a particle or a bill, and means a porous article, a porous solid, or a porous material.

When such a porous body is classified into a geometric structure, it can be broadly divided into an aggregate type and a sponge type (or Foam type) and a honeycomb type. The agglomerate or agglomerate is formed by sintering fine particles or solidifying them as binders. The pores originate from macro pores existing between the particles in addition to the internal micro pores of the raw particles, The size of the voids present between the particles is related to the size of the raw particles.

Conventionally, in porous ceramics, a certain amount of a flux component is mixed with a ceramics aggregate in which the particle size distribution is controlled to a certain range of width, and the mixture is sintered at a high temperature to burn the flux. Depending on the material and pore size, it has been used in a wide range of applications such as filtration or diffusion filters, media catalysts, sound absorbers, DPF (Diesel Particle Filter), heat exchangers, special heaters and bioceramics.

In recent years, ceramics have been applied to a heat dissipation package module for LED, which is mainly manufactured by laminating a sintered ceramic substrate and a ceramic substrate before sintering. Ceramics used in heat dissipating package modules for LEDs must have high porosity and high thermal conductivity, especially because they require good heat dissipation properties.

Conventionally, alumina (Korean Patent Publication No. 2003-0067102), zirconia (Korean Patent Publication No. 1992-0014744), silica (Korean Patent Laid- 0031289). However, due to the high anisotropy of the thermal expansion coefficient of such a material, microcracks are easily formed even if they are made of porous ceramics, which deteriorates mechanical properties and thermal characteristics, making them difficult to apply to various fields.

Conventional methods for producing porous ceramics include an inflow method (Korean Unexamined Patent Publication No. 2002-0023990) in which a pore-forming agent is mixed and sintered, and a method in which aggregates having a predetermined particle size range are uniformly dispersed in an organic or inorganic adhesive A compression molding method in which it is molded into a mold, followed by compression and molding, followed by drying and firing, and a template injection molding method in which molding is performed using natural templates and then firing is used.

However, the conventional production methods are difficult to effectively control the size and distribution of the pores of the porous article, and it is difficult to raise the porosity to 60% or more, and the production cost is relatively high. When the pores are not uniform, there is a problem that the particles are difficult to maintain a stable shape during the drying process, and when the porosity is low, the heat insulating effect is deteriorated.

Porous ceramics, despite the efforts of many researchers, has been used for various purposes such as the material of porous ceramics, the size, shape and distribution of porous ceramics pores and thermal properties, etc., due to the lack of know-how on production cost and microstructure control technology of open pores. The required properties according to the present invention can not be effectively controlled.

Therefore, a porous ceramics manufacturing method capable of improving the mechanical properties such as uniformity of the pores of the porous ceramics, improving the porosity and shape stability, and improving the thermal properties so that the porous ceramics can be applied to various fields including the LED field Technology development is required.

[Patent Document 1] Published Korean Patent Application No. 2003-0067102 [Patent Document 2] Korean Published Patent Application No. 1992-0014744 [Patent Document 4] Published Korean Patent Application No. 2012-0023990

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above-mentioned problems occurring in the prior art, and it is an object of the present invention to provide a method of manufacturing a porous ceramics which can optimize the material constituting the porous ceramics and effectively impart hydrophobicity to the surface of the ceramic particles, And a method for manufacturing porous composite ceramics using the direct foaming method.

Another object of the present invention is to provide porous composite ceramics having uniform pores and high porosity and high mechanical properties as well as high thermal conductivity and excellent stability since they are produced by the method of producing porous composite ceramics of the present invention.

According to an aspect of the present invention, there is provided a method of manufacturing porous composite ceramics according to an embodiment of the present invention includes the steps of:

(1) preparing a first aqueous suspension by mixing a silica (SiO ₂ ) powder with water and adding a surface treatment agent containing an amphiphile;

(2) mixing a silicon carbide (SiC) powder with water to prepare a second aqueous suspension;

(3) preparing an aqueous mixed suspension by mixing the first aqueous suspension prepared in step (1) with the second aqueous suspension prepared in step (2);

(4) stirring the aqueous mixed suspension to inject air, thereby forming a porous composite ceramic in which pores are formed by the interaction of the suspension and the air.

The method for producing porous composite ceramics of the present invention may further comprise the step of adjusting the pH of the first aqueous suspension prepared in the step (1).

The first aqueous suspension can be adjusted to pH 8-10.

The method of producing porous composite ceramics of the present invention may further include a step of drying and sintering the formed porous composite ceramics after the step of forming porous composite ceramics in the step (4).

The silica powder and the silicon carbide powder may have an average particle diameter of 0.1 to 100 mu m, respectively.

delete

In the first aqueous suspension preparation step, the volume ratio of the silica powder and the water may be 1: 0.5 to 3.

The surface treating agent may be added in an amount of 0.01 to 5 parts by weight based on 100 parts by weight of the aqueous suspension.

The surface treatment agent to be added to the first aqueous suspension may be selected from the group consisting of propyl gallate, butyl gallate, hexyl amine, or a carboxyalkyl group having 2 to 7 carbon atoms And a carboxylic acid.

In the second aqueous suspension preparation step, the volume ratio of the silicon carbide powder and the water may be 1: 5 to 20.

In the aqueous mixed suspension prepared in the aqueous mixing suspension preparation step, the molar ratio of the silicon carbide to 1 mole of the silica may be 0.25 to 0.5.

The contact angle of the aqueous mixing suspension obtained in the aqueous mixing suspension preparation step may be 50 DEG or more, preferably 50 to 90 DEG.

In the method for producing porous composite ceramics of the present invention, the step of preparing the first aqueous suspension of step (1), the step of preparing the second aqueous suspension of step (3), and the step of preparing the aqueous mixed suspension of step The resulting suspension may be ball milled, for example, the ball mill may be performed for 24 to 48 hours.

Also, the porous composite ceramics of the present invention produced by the method of producing porous composite ceramics of the present invention has an average pore size of 60 to 120 탆, a porosity of 80% or more, a thermal conductivity of 1.0 to 3.0 W / .

According to the method for producing porous composite ceramics of the present invention, silica and silicon carbide are appropriately used as ceramic powders, hydrophobic properties are imparted to the ceramic particles by a surface treatment agent containing a pro-affinity substance, Porous composite ceramics having uniform pores, remarkably high porosity of 80% or more, and excellent thermal stability such as shape stability and thermal shock resistance can be produced by a simple and inexpensive method of producing the composite ceramics.

The porous composite ceramics of the present invention can be widely applied to an energy saving field, an exhaust gas purification field, an environmental field, and the like by using the above characteristics. For example, the porous composite ceramics can be used as an LED module, a covering material for a reinforcing structure, a heat insulating material, A diesel particulate filter (DPF), a honeycomb carrier, a heat exchanger, a special heater, a biomaterial, and the like.

The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the description of the claims.

1 is a process flow diagram illustrating a method of fabricating porous composite ceramics according to an embodiment of the present invention.
FIG. 2 is a view showing steps of a method of manufacturing porous composite ceramics according to one embodiment of the present invention.
FIG. 3 is a view illustrating a process of producing porous composite ceramics by forming pores (direct foaming) according to the method of producing porous composite ceramics of the present invention.
4 is a view showing a stabilization mechanism of an aqueous mixed suspension produced according to the process for producing porous composite ceramics of the present invention.
5 is a graph showing the zeta-potential according to the pH of the first aqueous suspension (SiO ₂ suspension) prepared according to the example.
6 is a graph showing the contact angle and surface tension of the aqueous mixed suspension prepared according to the Example, measured according to the molar ratio of silicon carbide (SiC) to silica (SiO ₂ ).
FIG. 7 is a graph showing the wet foam stability of the porous composite ceramics prepared according to the embodiment according to the molar ratio of silicon carbide (SiC) to silica (SiO ₂ ).
8 is a graph showing the average bubble size and average pore size of the porous composite ceramics manufactured according to the embodiment according to the molar ratio of silicon carbide (SiC) to silica (SiO ₂ ).
FIG. 9 is a graph showing the relative bubble size (bubble stability) of porous composite ceramics manufactured according to the embodiment over time after foaming according to the molar ratio of silicon carbide (SiC) to silica (SiO ₂ ).
10 is a scanning electron microscope (SEM) image showing the microstructure according to the molar ratio of silicon carbide (SiC) to silica (SiO ₂ ) after foaming of the porous composite ceramics prepared according to the embodiment. It is a photograph.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and how to accomplish them, will become apparent by reference to the embodiments described in detail below with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

Unless defined otherwise, all terms (including technical and scientific terms) used herein may be used in a sense commonly understood by one of ordinary skill in the art to which this invention belongs. Also, commonly used predefined terms are not ideally or excessively interpreted unless explicitly defined otherwise.

Hereinafter, a method of manufacturing porous ceramics of the present invention will be described in detail with reference to the drawings.

1 and 2, a method of manufacturing porous ceramics according to an embodiment of the present invention includes:

(4) stirring the aqueous mixed suspension to inject air to form a porous composite ceramic in which pores are formed by the interaction of the suspension and the air.

The particles constituting the silica powder and the silicon carbide powder (hereinafter also referred to as " ceramic particles ") used in the method for producing porous composite ceramics of the present invention have an average particle diameter of 0.1 to 100 μm, preferably 1 to 50 μm, More preferably 1 to 10 mu m, but is not limited thereto.

Here, there is a method of expressing the average size of a population by measuring the particle size of the particles by a measurement method. However, there are a mode diameter indicating the maximum value of the distribution, a median diameter corresponding to the median value of the integral distribution curve, (Average number average, length average, area average, mass average, volume average, etc.). In the present invention, unless otherwise specified, the average particle diameter is a number average particle diameter, and D50 Particle diameter) of the particles.

In the method of preparing porous composite ceramics of the present invention, the first aqueous suspension preparation step in step (1) is a step of preparing a first aqueous suspension by mixing silica powder and water.

The water used as the solvent in the preparation of the first aqueous suspension of step (1) may be deionized water (DI water), or a solute such as sodium chloride may be further added.

The volume ratio of the silica powder and the water may be 1: 0.5 to 3, preferably 1: 1 to 2, more preferably 1: 1, and if it is out of the above range, The improvement effect may be insignificant.

The first aqueous suspension prepared in the first aqueous suspension preparation may be ball milled to prevent coagulation of the ceramic particles and to homogenize the first aqueous suspension. When the ball mill is performed, it is possible to use a ball of a known material, and it is preferable to use zirconia balls. For example, the ball mill may be rotated at a rotational speed of 40 to 100 rpm for 24 to 48 hours.

In the method for producing porous composite ceramics of the present invention, the surface of the silica particles can be changed from hydrophilic to hydrophobic by adding the surface treatment agent in the step (1). That is, the surface treatment agent has a function of changing the ceramic particles to be hydrophobic from the outside by forming a layer on the surface of the hydrophilic ceramic particles having hydrophilic portions.

The surface treating agent may be at least one selected from the group consisting of propyl gallate, butyl gallate, hexyl amine, and carboxylic acid having 2 to 7 carbon atoms . &Lt; / RTI > Preferably, the surface treatment agent is at least one selected from hexylamine and a carboxylic acid having 2 to 7 carbon atoms. Preferable examples of the carboxylic acid having 2 to 7 carbon atoms (not including the carbon of the carboxyl group) include butyric acid and valeric acid. When the number of carbon atoms of the carboxylic acid is 8 or more, a large surface area of the ceramic particles is formed as compared with the carboxylic acid having 2 to 7 carbon atoms, so that the stability of the porous ceramics form can be remarkably lowered by blowing air later.

The surface treatment agent may be added in an amount of 0.01 to 5 parts by weight based on 100 parts by weight of the total weight of the first aqueous suspension. When the addition amount of the surface treatment agent is less than 0.01 part by weight, the surface treatment effect is lowered due to the fact that a part of the surface of the ceramic particles such as silica particles can not be changed to be hydrophobic. As a result, There is a problem that the morphology stability of the ceramics is rapidly deteriorated. If the amount of the surface treatment agent exceeds 5 parts by weight, there is a problem that the stability of the formed porous composite ceramics is remarkably deteriorated as well as the physical properties of the porous composite ceramics formed by the presence of a large number of surface treatment agents fixed to the surface of the ceramic particles.

The pH of the first aqueous suspension may be 8.0 to 10.0, preferably 8.0 to 9.5. If the pH of the first aqueous suspension is out of the above range, the stability of the formed porous composite ceramics may be significantly lowered.

In order to control the pH, an acid or a base may be added. The type of the acid or base used is not limited. However, the acid may include hydrochloric acid due to the characteristics of the porous composite ceramics, and the base may include sodium hydroxide have.

In the method for producing porous composite ceramics of the present invention, the second aqueous suspension preparation step in step (2) is a step of preparing a second aqueous suspension by mixing silicon carbide powder and water.

Water used as a solvent in the preparation of the second aqueous suspension of step (2) may be deionized water (DI water), or may be further added with a solute such as sodium chloride.

The volume ratio of the silicon carbide powder and the water may be 1: 5 to 20, preferably 1: 8 to 10, and the stability of the wet molded article may be deteriorated if the amount is outside the above range.

The second aqueous suspension prepared in the second aqueous suspension preparation may be ball milled to prevent coagulation of the ceramic particles and to homogenize the second aqueous suspension. Can facilitate mixing with the first aqueous suspension in the aqueous mixing suspension preparation step, which is the next step. When the ball mill is performed, it is possible to use a ball of a known material, and it is preferable to use zirconia balls. For example, the ball mill may be rotated at a rotational speed of 40 to 100 rpm for 24 to 48 hours.

In the method for preparing porous composite ceramics of the present invention, the step of preparing the aqueous mixed suspension of step (3) is a step of preparing an aqueous mixed suspension by mixing the first aqueous suspension and the second aqueous suspension.

In the preparation of the aqueous mixed suspension of step (3), the silica in the first aqueous suspension acts as a stabilizer and is added in the form of a suspension in a volume ratio within the above-mentioned range, thereby stabilizing the wet foam and sintering And the mechanical properties of the porous composite ceramics can be improved.

In the aqueous mixed suspension prepared in the aqueous mixing suspension preparation step, the molar ratio of the silicon carbide to 1 mole of the silica is preferably 0.25 to 5.0. When the molar ratio of silicon carbide to silica is in the above range, the stability is particularly excellent.

The aqueous mixed suspension prepared in the step (4) may have a solid content of 20 to 40% by volume. Here, the solid refers to an added ceramic powder. For adjustment of the solids content, water may be added, if necessary, in the aqueous mixing suspension preparation step. By adjusting the solid content of the aqueous mixed suspension to the above range, it is possible to facilitate the formation of porous composite ceramics having improved stability.

In the preparation of the aqueous mixing suspension, the aqueous mixing suspension may be ball milled to prevent agglomeration of the ceramic particles, facilitate the mixing of the first aqueous suspension and the second aqueous suspension, The suspension can be homogenized. When the ball mill is performed, it is possible to use a ball of a known material, and it is preferable to use zirconia balls. For example, the ball mill may be rotated at a rotational speed of 40 to 100 rpm for 24 to 48 hours.

The aqueous mixed suspension prepared in the step (3) may have a contact angle of 50 to 90 °, preferably 60 to 90 °. When the contact angle of the aqueous mixed suspension is less than 50 °, the stability of the formed porous composite ceramics sharply drops and the pore size also becomes excessively small. The contact angle exceeding 90 ° is practically difficult to process However, there is a problem that the size of the pores becomes remarkably large.

In the method of producing porous composite ceramics of the present invention, the porous composite ceramic of step (4) is formed by stirring the aqueous mixed suspension prepared in step (3) Thereby forming porous composite ceramics by forming pores in the ceramics by interaction of the aqueous mixed suspension and air injected in a direct foaming manner.

In this step, the surface treatment agent is fixed on the surface of the ceramic particles, and external air is introduced into the aqueous mixing suspension by stirring the aqueous mixed suspension containing the hydrophobized silica and the silicon carbide particles and water, And the surface-treated ceramic particles are also hydrophobic and interact with each other due to their interaction with water, so that the ceramic particles adhere to the periphery of air bubbles. As a result, as shown in FIG. 4, ceramic particles Is formed and stabilized.

Accordingly, the ceramic particles form a barrier around the air bubbles. As a result, the pores are easily formed, and the size, shape, and distribution of the pores can be easily controlled by controlling the air injection according to the stirring speed and time.

In addition, the stability of porous composite ceramics formed by optimizing these process conditions as described above can also be enhanced.

The stirring in the porous composite ceramic forming step may be carried out in any manner, but it is effective to carry out the stirring for 5 to 40 minutes, more preferably for 10 to 25 minutes using a stirrer.

The method of producing porous composite ceramics of the present invention may further comprise the step of drying and sintering the porous composite ceramic after forming the porous composite ceramic in the step (4).

The drying can be carried out for 20 to 70 hours at a temperature of 15 to 35 DEG C in the air in the porous ceramics. The drying temperature may preferably be room temperature (20 to 25 ° C), and the drying time may preferably be 30 to 55 hours.

The sintering can be performed by heat-treating the dried porous composite ceramics at a temperature of 800 to 2,000 DEG C for 15 minutes to 4 hours, thereby completing the stable porous composite ceramic. The sintering temperature may preferably be 1,000 to 1,500 ° C, more preferably 1,200 to 1,300 ° C, and the sintering time may preferably be 30 minutes to 2 hours, more preferably 1 hour.

The porous composite ceramics of the present invention can be produced through the above-described method of producing porous composite ceramics of the present invention.

The porous composite ceramics of the present invention have uniform pores, high porosity, and excellent thermal stability including shape stability and thermal shock resistance.

In one embodiment of the present invention, the porous composite ceramics of the present invention may have an average pore size of 60 to 120 탆, preferably 70 to 110 탆, a porosity of 80% or more, preferably 85% More preferably at least 90%, most preferably at least 95%, and the thermal conductivity may be 1.0 to 3.0 W / mk, preferably 2.0 to 3.0 W / mk.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail through examples and experimental results for demonstrating the superiority of the porous composite ceramics of the present invention and the method for producing the same. However, the following examples are for illustrative purposes only, and the present invention is not limited to the following examples.

Example

Silica powder (average particle size: 3.5 탆, Junsei Chemicals, Japan) was added to deionized water, hexylamine was added thereto, and the mixture was stirred to prepare a first aqueous suspension having a solid content of 50% by volume. The pH of the first aqueous suspension was varied by adding 4M sodium hydroxide or 10N hydrochloric acid. The zeta-potential was measured according to the pH of the thus-prepared first aqueous suspension (SiO2 suspension) at various pH values, and the results are shown in FIG.

Thereafter, water was added to the first aqueous suspension of pH 8.5 to adjust the solids content of the first aqueous suspension to 30% by volume, and the mixture was ball-milled for 24 hours at a rotation speed of 60 rpm using a ball mill filled with a zirconia ball having an average particle diameter of 10 mm to homogenize .

Separately, a second aqueous suspension having a solids content of 10% by volume was prepared by adding silicon carbide powder (average particle size: 0.5 mu m, SIKA Tech Co., Germany) to deionized water. Using a ball mill charged with a zirconia ball having an average particle diameter of 10 mm at a rotating speed of 60 rpm for 24 hours.

The first aqueous suspension and the second aqueous suspension were mixed by varying the molar ratio of silica to silicon carbide in the range of 0 to 1.0 to prepare various aqueous mixed suspensions.

Each of the prepared aqueous mixed suspensions was injected with air while stirring to form respective porous composite ceramics. The porous composite ceramics were dried and then sintered at 1,300 ° C for 1 hour under an argon atmosphere to obtain porous composite materials having various molar ratios of silica and silicon carbide Ceramics. SEM photographs of the respective porous composite ceramics after foaming are shown in Fig.

Experiment result

The contact angle, surface tension, wet foam stability, bubble size and pore size, and bubble stability were measured for each of the porous composite ceramics prepared as described above and shown in FIGS. 6 to 9. 6 to 8, (1) shows the measurement results of the wet molded article, and (1) shows the measurement results of the formed article after the firing.

The contact angle was measured according to the Sessile-drop-method and the surface tension was measured according to the Pendant-drop-method (KSV Instruments Ltd., Helsinki, Finland) and is shown in FIG. Specifically, the contact angle and the surface tension were measured by measuring the contact angle and the surface tension of the aqueous mixed suspension in which the first aqueous suspension and the second aqueous suspension were mixed.

Referring to FIG. 6, in the case of each of the aqueous mixed suspensions prepared according to the present invention, the contact angle was measured to be about 50 ° or more, and hydrophobicity was effectively achieved thereby, and it is expected that the wet foam stability is excellent. In particular, when the molar ratio of silicon carbide to silica is about 0.25 to 0.5, it can be confirmed that the contact angle is about 70 ° or more, and the stability is excellent.

In addition, the wet foam stability of the wet foam (porous composite ceramics before drying) against each of the aqueous mixed suspensions prepared in the examples was measured and is shown in Fig.

Referring to FIG. 7, it can be seen that the stability of the wet foamed foam is more than 70%, and the stabilization is effectively performed. Particularly, when the molar ratio of silicon carbide to silica is about 0.25 to 0.5, it can be confirmed that the wet foam stability is excellent.

In addition, the average bubble size and average pore size of each of the aqueous mixed suspensions prepared in the examples were measured and shown in FIG.

The relative bubble size (bubble stability) of each of the porous composite ceramics prepared according to the example according to elapse of time after foaming was measured and is shown in Fig.

Referring to Figs. 8 and 9, it can be seen that the addition of silicon carbide keeps the bubble size without change even over time, which improves bubble stability and wet molded article stability.

The scope of the present invention is not limited to the above-described embodiments, but may be embodied in various forms of embodiments within the scope of the appended claims. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the appended claims.

Claims

A method for producing a porous composite ceramic comprising the steps of: (1) preparing a first aqueous suspension by mixing a silica (SiO ₂ ) powder with water and adding a surface treatment agent comprising an amphiphile ;
(2) mixing a silicon carbide (SiC) powder with water to prepare a second aqueous suspension;
(3) mixing the second aqueous suspension prepared in step (2) with the first aqueous suspension prepared in step (1) so that the molar ratio of the silicon carbide to the silica is 0.25 to 0.5 mol, Preparing a suspension;
(4) stirring the aqueous mixed suspension to inject air, thereby forming a porous composite ceramic in which pores are formed by the interaction of the suspension and the air.

The method of claim 1, further comprising adjusting the pH of the first aqueous suspension prepared in step (1) to 8 to 10.

[6] The method of claim 1, wherein the porous composite ceramics further comprises a step of drying and sintering the formed porous composite ceramic after the step (4).

The method of claim 1, wherein the silica powder and the silicon carbide powder have an average particle diameter of 0.1 to 100 μm.

The method according to claim 1, wherein, in the step of preparing the first aqueous suspension, the volume ratio of the silica powder and the water is 1: 0.5 to 3.

The method of claim 1, wherein in the step of preparing the second aqueous suspension, the volume ratio of the silicon carbide powder and the water is 1: 5 to 20.

The method according to claim 1, wherein the surface treating agent is added in an amount of 0.01 to 5 parts by weight based on 100 parts by weight of the total weight of the silica powder and water in the step (1).

The surface treatment agent according to claim 1, wherein the surface treatment agent is selected from the group consisting of propyl gallate, butyl gallate, hexyl amine, or a carbamate having 2 to 7 carbon atoms And a carboxylic acid and / or a carboxylic acid.

delete

The method according to claim 1, wherein the contact angle of the aqueous mixed suspension obtained in the step of preparing the aqueous mixed suspension is 50 to 90 °.

The method according to claim 1, characterized by comprising homogenizing the obtained suspension by ball milling for 24 to 48 hours in at least one of the first aqueous suspension preparation step, the second aqueous suspension preparation step and the aqueous mixing suspension preparation step Wherein the porous composite ceramics is produced by a method comprising the steps of:

A method for producing a porous composite ceramics according to any one of claims 1 to 8 or 10 to 11, which comprises the steps of: preparing a porous composite ceramics according to any one of claims 1 to 8, wherein the pore has an average size of 60 to 120 μm and a porosity of 80% Porous composite ceramics.

13. The porous composite ceramics of claim 12, wherein the porous composite ceramic is for an LED module.