CN118026718A

CN118026718A - Low-temperature sintered pure porous silicon carbide ceramic support and preparation method thereof

Info

Publication number: CN118026718A
Application number: CN202410176849.8A
Authority: CN
Inventors: 刘阳; 胡佳丽; 李光辉; 刘睿; 夏琴
Original assignee: Shanghai University of Engineering Science
Current assignee: Shanghai University of Engineering Science
Priority date: 2024-02-08
Filing date: 2024-02-08
Publication date: 2024-05-14

Abstract

The invention discloses a low-temperature sintered pure porous silicon carbide ceramic support and a preparation method thereof, wherein the preparation method comprises the following steps: a) Preparing composite powder: firstly, dissolving a silicon carbide precursor in an organic solvent, then adding silicon carbide particles, fully mixing and dispersing, continuously stirring under a heating condition until the organic solvent volatilizes, drying and grinding the obtained product to obtain composite powder; then placing the composite powder, ball milling media and silicon carbide grinding balls in a ball milling tank of a ball mill together for ball milling, and then drying and grinding slurry obtained by ball milling to obtain composite powder; wherein the mass of the silicon carbide precursor is 0.5-20% of the mass of the silicon carbide particles; b) Compression molding; c) Sintering. The silicon carbide ceramic support prepared by the invention is composed of pure silicon carbide phase, has the advantages of high mechanical strength, good compactness, good acid and alkali corrosion resistance, controllable pore diameter, uniform pore diameter distribution and the like, and can be applied to separation and purification in the field of microfiltration or ultrafiltration.

Description

Low-temperature sintered pure porous silicon carbide ceramic support and preparation method thereof

Technical Field

The invention relates to a low-temperature sintering (sintering temperature is 800-1200 ℃) pure porous silicon carbide ceramic support and a preparation method thereof, belonging to the technical field of silicon carbide ceramic supports.

Background

As a novel inorganic film material matrix, the porous silicon carbide ceramic support not only has high temperature resistance, abrasion resistance and excellent chemical stability of the silicon carbide material, but also has low density and good shock resistance due to a large number of air holes. As a ceramic material with both structural and functional properties, the ceramic material is widely applied to the fields of national defense, aerospace, chemical industry, biological energy and the like at present.

At present, a sintering method is mainly adopted for preparing the porous silicon carbide ceramic support body, and the sintering method mainly comprises recrystallization sintering and reaction sintering. The recrystallization sintering is based on the principle of evaporation and condensation, and the fine silicon carbide particles are evaporated and condensed into sintering necks at high temperature (2000-2450 ℃), and then coarse silicon carbide particles are bonded, so that the sintering effect is finally achieved. The reaction sintering is a process in which a ceramic raw material compact is subjected to a chemical reaction between a solid phase, a liquid phase and a gas phase at a certain temperature, and densification and synthesis of a predetermined component are simultaneously performed to obtain a predetermined sintered body. Compared with the reaction sintering, the recrystallization sintering has the defects of high sintering temperature, high energy consumption, high requirement on raw materials and the like, so the reaction sintering becomes an important direction of research and development. At present, a silicon source carbon source method and a sintering aid adding method are mainly adopted, wherein the silicon source carbon source method generally generates a new silicon carbide phase by means of a silicon source and a carbon source, and the sintering aid adding method realizes silicon carbide particle adhesion at low temperature by adding a sintering aid, for example:

Patent CN102659446B discloses a pure silicon carbide film tube support and a preparation method thereof, the method uses coarse grain silicon carbide, silicon powder or silicon oxide powder as basic materials, and adds high molecular materials as bonding agents, presses the above mixture in a cold isostatic pressing mode, and sinters to obtain the pure silicon carbide film tube support; according to the method, a silicon source (silicon powder or silicon oxide powder) and a carbon source (high polymer material) are added for reaction sintering to form a new silicon carbide phase for realizing the connection between coarse silicon carbide particles; the method has the advantages that the ingredients are more in proportion and complex, high-temperature sintering (the sintering temperature is 1500-2400 ℃) is needed in the protective atmosphere, the phenomena of residual silicon or carbon residue and the like are very easy to occur after sintering, the pure silicon carbide ceramic material is difficult to obtain, and the corrosion resistance and the high-temperature mechanical property of the material are reduced;

The patent CN110698215A discloses a high-temperature-resistant corrosion-resistant reaction sintering silicon carbide film support and a preparation method thereof, wherein silicon carbide powder is taken as a main raw material, silicon nitride powder is taken as a silicon source, a carbon precursor is taken as a carbon source, the raw materials are mixed according to a proportion to prepare a green body, and the green body is subjected to reaction sintering at 1350-1750 ℃ to obtain pure silicon carbide; the method takes silicon nitride as a silicon source for reaction sintering, and has high raw material cost; the carbon precursor comprises active carbon powder and/or carbon organic precursor, and has complex components; the reaction of the silicon source and the carbon source needs to be precisely controlled, otherwise, the phenomenon of residual silicon or carbon residue is easy to occur, and the pure silicon carbide ceramic support is difficult to obtain;

patent CN113999046B discloses a preparation method of a low-temperature reaction sintering silicon carbide ceramic membrane, which comprises the steps of generating a beta-SiC new phase and a liquid phase reaction of a NaCl-KCl molten salt system by reacting silicon powder with carbon black at 1350-1600 ℃, and adhering silicon carbide raw material particles together to form a continuous porous ceramic support; the method also needs a silicon source (silicon powder) and a carbon source (carbon powder), and is mixed with raw materials such as molten salt, kaolin and the like, so that the mixture is very complex, the phenomena such as residual silicon or carbon residue and the like are very easy to occur after sintering, and the pure silicon carbide ceramic support is difficult to obtain;

The patent CN107619281B discloses a preparation method of a low-temperature sintering acid-alkali-resistant porous silicon carbide ceramic support, which comprises the steps of preparing mud blanks with different geometric shapes by using an extrusion molding process and firing the porous silicon carbide ceramic support, wherein the raw materials used in the method are silicon carbide powder, a sintering aid, a forming agent, a pore-forming agent, a lubricant and a solvent; according to the method, natural ores such as zirconite, high boron silicon, potassium feldspar, quartz sand, suzhou soil, calcined talcum, chalk, fluorite and the like are used as sintering aids, and are sintered at high temperature to bond silicon carbide particles; the adopted natural ore belongs to oxide type mineral substances, and although liquid phase can be formed at 1400 ℃ so as to connect silicon carbide particles together, the prepared final product is not a single silicon carbide phase, and has the defects of low heat conductivity, poor thermal shock resistance, reduced service life at high temperature, weak inter-grain bonding, corrosion resistance and the like.

In summary, the silicon source carbon source method and the sintering aid adding method adopted by the reaction sintering at present have certain defects. Although the silicon source carbon source method can prepare a new phase of silicon carbide to connect silicon carbide particles, the reaction is very easy to be incomplete and residual silicon or carbon residue appears, so that the microstructure uniformity is poor, the residual stress born by the silicon carbide particles is large, the mechanical strength of the material is obviously reduced, the corrosion resistance is poor, and the application of the material is restricted; the sintering aid adding method generally introduces easily-melted substances such as oxides, and the like, so that the final material is poor in thermal shock resistance and not corrosion-resistant; in addition, such methods are often complex in formulation and cannot produce a pure silicon carbide ceramic support.

Disclosure of Invention

Aiming at the problems existing in the prior art, the invention aims to provide a low-temperature sintered pure porous silicon carbide ceramic support and a preparation method thereof.

In order to achieve the above purpose, the invention adopts the following technical scheme:

a preparation method of a low-temperature sintered pure porous silicon carbide ceramic support comprises the following steps:

a) Preparing composite powder: firstly, dissolving a silicon carbide precursor in an organic solvent, then adding silicon carbide particles, fully mixing and dispersing, continuously stirring under a heating condition until the organic solvent volatilizes, drying and grinding the obtained product to obtain composite powder; then placing the composite powder, ball milling media and silicon carbide grinding balls in a ball milling tank of a ball mill together for ball milling, and then drying and grinding slurry obtained by ball milling to obtain composite powder; wherein the mass of the silicon carbide precursor is 0.5-20% of the mass of the silicon carbide particles;

b) Compression molding: axially pressing the composite powder prepared in the step a) into a green body with a certain shape and thickness;

c) Sintering: sintering the green body prepared in the step b) for 1-3 hours at 800-1200 ℃ under vacuum or inert atmosphere to obtain the low-temperature sintered pure porous silicon carbide ceramic support.

In a preferred embodiment, in step a), the silicon carbide precursor is polycarbosilane.

In a preferred embodiment, in the step a), the organic solvent is at least one selected from n-hexane, cyclohexane, benzene, toluene, xylene, trimethylbenzene, chlorotoluene, and decalin.

In a preferred embodiment, in the step a), the silicon carbide particles have a particle diameter of 0.1 μm to 10. Mu.m.

In a preferred embodiment, in step a), the silicon carbide particles: the mass ratio of the organic solvent is 1: (1.5-3).

In a preferred scheme, in the step a), stirring is continuously carried out under the heating condition of 55-65 ℃ until the organic solvent volatilizes, the obtained product is dried for 1-3 hours under the temperature of 55-65 ℃, and then the obtained product is ground and sieved to obtain the composite powder.

In a preferred embodiment, in step a), the composite powder: ball milling medium: the mass ratio of the silicon carbide grinding pellets is 1: (1-1.5): (1-1.5), wherein the ball milling medium is ethanol.

In a preferred embodiment, in step a), the number of revolutions of the ball mill is 250 to 300 revolutions per minute and the milling time is 0.5 to 12 hours.

In a preferred scheme, in the step a), slurry obtained by ball milling is dried for 5-8 hours at 55-65 ℃, and then is ground and sieved to obtain composite powder.

In a preferred embodiment, in step b), the molding pressure is 50 to 90MPa, the dwell time is 1 to 3 minutes, and the green body is dried at 55 to 65℃for 3 to 5 hours.

In a preferred scheme, in the step c), the temperature is firstly increased to 200-400 ℃ at a heating rate of 1-10 ℃/min, the temperature is kept for 10-100 min, then the temperature is increased to 700-900 ℃ at a heating rate of 1-10 ℃/min, the temperature is kept for 10-150 min, then the temperature is increased to 800-1200 ℃ at a heating rate of 1-10 ℃/min, the temperature is kept for 60-180 min, then the temperature is reduced to 300-500 ℃ at a cooling rate of 1-10 ℃/min, and finally the temperature is naturally cooled to room temperature.

The invention also provides the low-temperature sintered pure porous silicon carbide ceramic support body prepared by the preparation method.

Compared with the prior art, the invention has the following remarkable beneficial effects:

1. The raw materials adopted by the invention are silicon carbide particles and a silicon carbide precursor, wherein the silicon carbide precursor can be used as a binder, the silicon carbide precursor can be cracked and converted into amorphous silicon carbide when being sintered at 800-1200 ℃, the generated amorphous silicon carbide can play roles in binding and filling pores on the silicon carbide particles, no byproducts are generated, the finally prepared support body is composed of pure silicon carbide phases, and the bonding firmness among crystal particles can be effectively improved, so that the mechanical strength and acid and alkali corrosion resistance of the support body can be effectively improved; in addition, the preparation method provided by the invention has the advantages of simple operation, low sintering energy consumption, mild conditions, simple and easily available raw materials, low cost, easiness in molding, short production period, easiness in realization of large scale and the like;

2. The silicon carbide ceramic support provided by the invention consists of a pure silicon carbide phase, has high mechanical strength (bending strength is more than 20.1N/mm ²), good compactness (apparent porosity is 44.6% -51.2%), good acid and alkali corrosion resistance (acidity resistance and alkali resistance are both more than 99%), controllable pore diameter, uniform pore diameter distribution and can reach an ultrafiltration range (for example, the pore diameter of the support in the embodiment 1 is 0.155 mu m), belongs to the ultrafiltration range, and can be applied to separation and purification in the field of microfiltration or ultrafiltration.

Drawings

FIG. 1 is an XRD pattern of a porous silicon carbide ceramic support prepared in example 1 of the present invention;

fig. 2 is a physical view of a green body and a porous silicon carbide ceramic support prepared in example 1 of the present invention, in which: the left side is a green body, and the right side is a porous silicon carbide ceramic support;

FIG. 3 is an SEM image of a porous silicon carbide ceramic support prepared according to example 1 of the invention;

FIG. 4 is a BSE chart at 300nm scale of the porous silicon carbide ceramic support prepared in example 1 of the present invention;

FIG. 5 is a BSE diagram of a porous silicon carbide ceramic support prepared in example 1 of the present invention at a1 μm scale;

FIG. 6 is a graph showing pore size distribution of a porous silicon carbide ceramic support prepared in example 1 of the present invention;

FIG. 7 is an SEM image of a porous silicon carbide ceramic support prepared according to example 2 of the invention;

FIG. 8 is a physical view of the green body prepared in comparative example 1 of the present invention;

FIG. 9 is an SEM image of a silicon carbide ceramic support prepared according to comparative example 1;

FIG. 10 is an SEM image of a silicon carbide ceramic support prepared according to comparative example 2;

FIG. 11 is a golden phase diagram of a silicon carbide ceramic support prepared in accordance with comparative example 2 of the present invention;

FIG. 12 is a golden phase diagram of a silicon carbide ceramic support prepared in comparative example 3 of the present invention.

Detailed Description

The technical scheme of the invention is further and fully described in the following by combining examples. It is to be understood that these examples are illustrative of the present invention and are not intended to limit the scope of the present invention. The experimental procedures, which do not address the specific conditions in the examples below, are generally carried out under conventional conditions or under conditions recommended by the manufacturer.

Example 1

A) Preparing composite powder: dissolving polycarbosilane in n-hexane, adding 0.5 mu m silicon carbide particles, fully mixing and dispersing, continuously stirring at 60 ℃ until n-hexane volatilizes, drying the obtained product at 60 ℃ for 2 hours, grinding, and sieving with a 40-mesh sieve to obtain composite powder; then the composite powder, ethanol and silicon carbide grinding balls are put into a ball milling tank of a planetary ball mill for ball milling, the revolution of the ball mill is 280rpm, the ball milling time is 8 hours, then the slurry obtained by ball milling is dried for 6 hours at 60 ℃, and the slurry is ground and sieved by a 40-mesh sieve, thus obtaining composite powder; wherein the mass of the polycarbosilane is 15% of the mass of the silicon carbide particles: the mass ratio of the n-hexane is 1:3, and the composite powder is: ethanol: the mass ratio of the silicon carbide grinding pellets is 1:1:1;

b) Compression molding: axially pressing the composite powder obtained in the step a) into The molding pressure is 70MPa, the dwell time is 1.5 minutes, and the pressed green body is dried for 4 hours at 60 ℃;

c) Sintering: heating the green body prepared in the step b) to 300 ℃ at a heating rate of 5 ℃ per minute under vacuum, preserving heat for 20 minutes, heating to 800 ℃ at a heating rate of 5 ℃ per minute, preserving heat for 20 minutes, heating to 1000 ℃ at a heating rate of 5 ℃ per minute, preserving heat for 120 minutes, cooling to 300 ℃ at a cooling rate of 5 ℃ per minute, and naturally cooling to room temperature to obtain the porous silicon carbide ceramic support.

Fig. 1 is an XRD pattern of the porous silicon carbide ceramic support prepared in this example, as can be seen from fig. 1: the porous silicon carbide ceramic support prepared in this example consisted of a pure silicon carbide phase.

Fig. 2 is a physical view of the green body and porous silicon carbide ceramic support prepared in this example, in which: the left side is a green body, and the right side is a porous silicon carbide ceramic support; as can be seen from fig. 2: the green body and the porous silicon carbide ceramic support prepared in the embodiment have good molding effects.

Fig. 3 is an SEM image of the porous silicon carbide ceramic support prepared in this example, as can be seen from fig. 3: the porous silicon carbide ceramic support prepared by the embodiment has a good pore structure.

FIGS. 4 and 5 are BSE diagrams of the porous SiC ceramic support prepared in this example at 300nm and 1 μm scale, respectively, as can be seen from FIGS. 4 and 5: the polycarbosilane not only serves as a silicon carbide precursor to generate a new silicon carbide phase, but also serves as a binder to combine original silicon carbide particles, so that the bonding effect is good, and a good pore channel structure can be constructed.

Fig. 6 is a pore size distribution diagram of the porous silicon carbide ceramic support prepared in this example, and fig. 6 shows that: the porous silicon carbide ceramic support prepared by the embodiment has uniform pore size distribution, the pore size is about 0.155 mu m and is close to 100nm, and the porous silicon carbide ceramic support belongs to the ultrafiltration range.

The performance test data of the porous silicon carbide ceramic support prepared in this example are shown in Table 2.

Example 2

A) Preparing composite powder: dissolving polycarbosilane in toluene, adding 0.1 mu m silicon carbide particles, fully mixing and dispersing, continuously stirring until the toluene volatilizes under the heating condition of 60 ℃, drying the obtained product at 60 ℃ for 2 hours, grinding, and sieving with a 40-mesh sieve to obtain composite powder; then the composite powder, ethanol and silicon carbide grinding balls are put into a ball milling tank of a planetary ball mill for ball milling, the revolution of the ball mill is 280rpm, the ball milling time is 4 hours, then the slurry obtained by ball milling is dried for 6 hours at 60 ℃, and the slurry is ground and sieved by a 40-mesh sieve, thus obtaining composite powder; wherein the mass of the polycarbosilane is 5% of the mass of the silicon carbide particles: toluene in the mass ratio of 1:2.5, and the composite powder: ethanol: the mass ratio of the silicon carbide grinding pellets is 1:1.2:1.5;

b) Compression molding: axially pressing the composite powder obtained in the step a) into The molding pressure is 60MPa, the dwell time is 2 minutes, and the pressed green body is dried for 4 hours at 60 ℃;

c) Sintering: heating the green body prepared in the step b) to 250 ℃ at a heating rate of 10 ℃ per minute under the protection of argon, preserving heat for 10 minutes, heating to 700 ℃ at a heating rate of 3 ℃ per minute, preserving heat for 10 minutes, heating to 1200 ℃ at a heating rate of 5 ℃ per minute, preserving heat for 80 minutes, cooling to 500 ℃ at a cooling rate of 10 ℃ per minute, and naturally cooling to room temperature to obtain the porous silicon carbide ceramic support.

Fig. 7 is an SEM image of the porous silicon carbide ceramic support prepared in this example, as can be seen from fig. 7: the porous silicon carbide ceramic support prepared by the embodiment has good sintering effect and uniform pore distribution.

Example 3

A) Preparing composite powder: dissolving polycarbosilane in cyclohexane, adding silicon carbide particles with the diameter of 2 mu m, fully mixing and dispersing, continuously stirring until the cyclohexane volatilizes under the heating condition of 60 ℃, drying the obtained product at the temperature of 60 ℃ for 2 hours, grinding, and sieving with a 40-mesh sieve to obtain composite powder; then the composite powder, ethanol and silicon carbide grinding balls are put into a ball milling tank of a planetary ball mill for ball milling, the revolution of the ball mill is 280rpm, the ball milling time is 6 hours, then the slurry obtained by ball milling is dried for 6 hours at 60 ℃, and the slurry is ground and sieved by a 40-mesh sieve, thus obtaining composite powder; wherein the mass of the polycarbosilane is 0.5% of the mass of the silicon carbide particles, and the silicon carbide particles are: the mass ratio of cyclohexane is 1:2, and the powder is composed of: ethanol: the mass ratio of the silicon carbide grinding pellets is 1:1:1.5;

b) Compression molding: axially pressing the composite powder obtained in the step a) into The molding pressure is 50MPa, the dwell time is 2.5 minutes, and the pressed green body is dried for 4 hours at 60 ℃;

c) Sintering: heating the green body prepared in the step b) to 200 ℃ at a heating rate of 3 ℃/min under vacuum, preserving heat for 10min, heating to 700 ℃ at a heating rate of 5 ℃/min, preserving heat for 10min, heating to 1100 ℃ at a heating rate of 8 ℃/min, preserving heat for 100 min, cooling to 400 ℃ at a cooling rate of 8 ℃/min, and naturally cooling to room temperature to obtain the porous silicon carbide ceramic support.

Example 4

A) Preparing composite powder: dissolving polycarbosilane in benzene, adding silicon carbide particles with the size of 5 mu m, fully mixing and dispersing, continuously stirring until benzene volatilizes under the heating condition of 60 ℃, drying the obtained product at 60 ℃ for 2 hours, grinding, and sieving with a 40-mesh sieve to obtain composite powder; then the composite powder, ethanol and silicon carbide grinding balls are put into a ball milling tank of a planetary ball mill for ball milling, the revolution of the ball mill is 280rpm, the ball milling time is 12 hours, then the slurry obtained by ball milling is dried for 12 hours at 60 ℃, ground and sieved by a 40-mesh sieve, and composite powder is obtained; wherein the mass of the polycarbosilane is 13% of the mass of the silicon carbide particles, and the silicon carbide particles are: benzene mass ratio is 1:1.5, and the composite powder: ethanol: the mass ratio of the silicon carbide grinding pellets is 1:1.5:1.5;

b) Compression molding: axially pressing the composite powder obtained in the step a) into The molding pressure is 90MPa, the dwell time is 3 minutes, and the pressed green body is dried for 4 hours at 60 ℃;

c) Sintering: heating the green body prepared in the step b) to 300 ℃ at a heating rate of 5 ℃ per minute under the protection atmosphere of argon gas, preserving heat for 10 minutes, heating to 800 ℃ at a heating rate of 3 ℃ per minute, preserving heat for 80 minutes, cooling to 300 ℃ at a cooling rate of 10 ℃ per minute, and naturally cooling to room temperature to obtain the porous silicon carbide ceramic support.

Comparative example 1

Comparative example 1 is the same as example 1 in step, except that: the raw materials are not added with polycarbosilane, and the silicon carbide particles are directly added into normal hexane for stirring and dispersing.

Fig. 8 is a physical view of the green body prepared in this comparative example, as can be seen from fig. 8: the green body prepared in this comparative example could not be formed. It can be seen from the physical diagram of the green body prepared in example 1 shown in fig. 2 that addition of polycarbosilane has a significant effect on the green body molding, and that sample molding effect without addition of polycarbosilane is poor and the green body is extremely brittle.

Fig. 9 is an SEM image of the silicon carbide ceramic support prepared in this comparative example, as can be seen from fig. 9: the silicon carbide ceramic support prepared in this comparative example had poor sintering effect and did not adhere to each other.

Further, the mechanical strength (bending strength) of the silicon carbide ceramic support prepared in this comparative example was tested, and the result showed that: the silicon carbide ceramic support prepared in this comparative example has no mechanical strength.

It can be seen in connection with example 1: the addition of the polycarbosilane has obvious influence on the molding effect, the sintering effect and the mechanical strength of the silicon carbide ceramic support, and can enhance the bonding among silicon carbide particles and improve the molding effect, the sintering effect and the mechanical strength of the support.

Comparative example 2

Comparative example 2 is identical to example 2 in step, except that: and (3) directly carrying out compression molding on the composite powder which is not subjected to ball milling treatment without ball milling technology.

Fig. 10 is an SEM image of the silicon carbide ceramic support prepared in this comparative example, as can be seen from fig. 10: the silicon carbide ceramic support prepared in this comparative example had poor molding effect and severe inter-particle agglomeration.

Fig. 11 is a gold phase diagram of the silicon carbide ceramic support prepared in this comparative example, as can be seen from fig. 11: the silicon carbide ceramic support prepared in the comparative example has obvious cracks on the surface and poor sintering effect.

Further, the mechanical strength (bending strength) of the silicon carbide ceramic support prepared in this comparative example was tested, and the result showed that: the mechanical strength of the silicon carbide ceramic support prepared in this comparative example was about 60% lower than that of the porous silicon carbide ceramic support of example 2, and the mechanical strength was poor.

It can be seen in connection with example 2 that: the ball milling treatment has obvious influence on the molding effect, sintering effect and mechanical strength of the silicon carbide ceramic support body, and the molding effect, sintering effect and mechanical strength of the sample subjected to the ball milling treatment are better.

Comparative example 3

Comparative example 3 is identical to example 3 in step, except that: the sintering is carried out directly by heating to 1100 ℃ at the heating rate of 10 ℃/min without adopting step sintering operation of gradient heating and heat preservation.

Fig. 12 is a gold phase diagram of the silicon carbide ceramic support prepared in this comparative example, as can be seen from fig. 12: the silicon carbide ceramic support prepared in the comparative example has obvious surface cracks and poor sintering effect.

It can be seen in connection with example 3 that: the sintering operation has obvious influence on the sintering effect of the silicon carbide ceramic support body, and the sintering effect of step sintering is better.

The porous silicon carbide ceramic supports prepared in examples 1 to 4 were tested for flexural strength, pore diameter, apparent porosity, acidity and alkali resistance, and the specific test methods are shown in Table 1, and the test results are shown in Table 2.

TABLE 1 Performance test method for porous silicon carbide ceramic supports

TABLE 2 Performance test data for porous silicon carbide ceramic supports

As can be seen from the test results in table 2: the porous silicon carbide ceramic support prepared by the invention has the advantages of high mechanical strength, good compactness, good acid and alkali corrosion resistance, controllable pore diameter and the like, and the pore diameter is uniformly distributed and can reach the ultrafiltration range.

Finally, it is pointed out here that: the above is only a part of the preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention, and some insubstantial modifications and adaptations of the present invention based on the foregoing are within the scope of the present invention.

Claims

1. The preparation method of the low-temperature sintered pure porous silicon carbide ceramic support is characterized by comprising the following steps of:

c) Sintering: sintering the green body prepared in the step b) for 1-3 hours at 800-1200 ℃ under the protection atmosphere of vacuum or inert gas to obtain the porous silicon carbide ceramic support.

2. The method of manufacturing according to claim 1, characterized in that: in the step a), the silicon carbide precursor is polycarbosilane.

3. The method of manufacturing according to claim 1, characterized in that: in the step a), the organic solvent is at least one selected from normal hexane, cyclohexane, benzene, toluene, xylene, trimethylbenzene, chlorotoluene and decalin.

4. The method of manufacturing according to claim 1, characterized in that: in step a), silicon carbide particles: the mass ratio of the organic solvent is 1: (1.5-3).

5. The method of manufacturing according to claim 1, characterized in that: in the step a), stirring is continuously carried out under the heating condition of 55-65 ℃ until the organic solvent volatilizes, the obtained product is dried for 1-3 hours under the temperature of 55-65 ℃, and the obtained product is ground and sieved to obtain the composite powder.

6. The method of manufacturing according to claim 1, characterized in that: in step a), the composite powder: ball milling medium: the mass ratio of the silicon carbide grinding pellets is 1: (1-1.5): (1-1.5), wherein the ball milling medium is ethanol.

7. The method of manufacturing according to claim 1, characterized in that: in the step a), the revolution of the ball mill is 250-300 rpm, and the ball milling time is 0.5-12 hours.

8. The method of manufacturing according to claim 1, characterized in that: in the step b), the molding pressure is 50-90 MPa, the dwell time is 1-3 minutes, and the pressed green body is dried for 3-5 hours at 55-65 ℃.

9. The method of manufacturing according to claim 1, characterized in that: in the step c), the temperature is firstly increased to 200-400 ℃ at a heating rate of 1-10 ℃/min, the temperature is kept for 10-100 min, then the temperature is increased to 700-900 ℃ at a heating rate of 1-10 ℃/min, the temperature is kept for 10-150 min, the temperature is increased to 800-1200 ℃ at a heating rate of 1-10 ℃/min, the temperature is kept for 60-180 min, the temperature is reduced to 300-500 ℃ at a cooling rate of 1-10 ℃/min, and finally the temperature is naturally cooled to the room temperature.

10. A low-temperature sintered pure porous silicon carbide ceramic support is characterized in that: prepared by the preparation method according to any one of claims 1 to 9.