KR20090048234A - Composition for sillicon carbide filter, sillicon carbide filter comprising the same and preparation method thereof - Google Patents

Abstract

The present invention is silicon carbide; Inorganic oxides; And it relates to a composition for a silicon carbide filter comprising an inorganic fiber, a silicon carbide filter comprising the above and a manufacturing method thereof. The composition for a silicon carbide filter of the present invention includes an inorganic fiber, and the inorganic fiber is characterized in that the bonding of the silicon carbide with the inorganic oxide is further strengthened. Accordingly, the silicon carbide filter including the composition of the present invention has improved thermal shock resistance and is excellent in resistance to crack generation and breakage during manufacturing and operation.

Silicon Carbide, Inorganic Oxide, Inorganic Fiber, Filter, Thermal Shock Resistance.

Description

Composition for Silicon Carbide Filter, Silicon Carbide Filter Comprising the Same and Method for Manufacturing the Same {Composition for sillicon carbide filter, sillicon carbide filter comprising the same and preparation method

The present invention is silicon carbide; Inorganic oxides; And it relates to a composition for a silicon carbide filter comprising an inorganic fiber, a silicon carbide filter comprising the above and a manufacturing method thereof.

Dust collector filters are used in a variety of applications in the chemical, power, and steel fields, for example, for pollution prevention such as industrial waste disposal and for product recovery from hot gases. Specific examples in which such a dust collecting filter is used include a catalyst carrier for automobile exhaust purification, a heat exchanger of a gas turbine, and a filtering system for a diesel engine.

Diesel Particulate Filter (DPF), which collects Particulte Material (PM) from diesel engines, is generally a porous honeycomb structure, which is used in exhaust gas from diesel engines. It is used as a catalyst carrier for supporting a catalyst component for removing harmful substances contained in exhaust gas or a filter for removing particulate matter contained therein.

This porous ceramic honeycomb structure of the DPF has a plurality of cells formed in parallel with the exhaust flow. Adjacent cells are separated by a porous partition wall, and the inlet and outlet sections are sealed alternately, functioning as a wallflow method to capture particulate matter while the introduced exhaust gases pass through the porous partition wall. . However, excessive accumulation of particulate matter on the porous partition wall of the DPF may cause a pressure loss of the filter and a decrease in engine output. Accordingly, in the DPF, the collected particulate matter needs to be burned and removed every time using an external ignition means such as an electric heater or a burner. By the way, in the regeneration process, the temperature of the particulate matter is much higher than that of the small portion, the temperature rises, and due to the thermal stress there may be a problem such as crack generation or breakage.

Accordingly, the DPF material is required to have a low pressure loss to prevent the degradation of the engine performance, and to have a thermal shock resistance to withstand thermal shock due to a sudden temperature change during engine regeneration or stop. In this respect, silicon carbide with high heat resistance and low resistivity is suitable as a DPF material.

The method of joining silicon carbide particles in the manufacture of segments constituting silicon carbide DPFs is a method of joining silicon carbide particles by recrystallization of silicon carbide, adding carbon and silicon, and converting them to silicon carbide in the manufacturing process. And a method of using an inorganic oxide. Among them, the method of using an inorganic oxide is produced in an oxidizing atmosphere without controlling the atmosphere, has a low firing temperature, low production cost, and has excellent chemical resistance, oxidation resistance, and ease of processing. However, in the case of the above method, since the filter is manufactured in an oxidizing atmosphere, oxidation occurs on the surface of the silicon carbide particles during firing, which leads to a weakening of the thermal shock of the filter. As a result, when inorganic oxides are used, problems such as breakage or cracking of the filter occur during the manufacturing process or operation.

Japanese Patent Laid-Open No. 2002-070529 has a honeycomb filter installed in a casing of an exhaust passage of an internal combustion engine; And it discloses a method for preventing the occurrence of cracks by adjusting the thermal conductivity of the support between the casing and the filter.

Further, Japanese Patent Laid-Open No. 2004-142978 discloses a method of improving the strength of a filter by including colloidal particles such as silica sol, alumina sol, or metal alkoxide in ceramic particles, water, organic binder, and pore-forming agent. have.

However, the proposed method is a method of adjusting the thermal conductivity or reinforcing the mechanical strength of the support, not the honeycomb structure itself, and this method has a limit to fundamentally prevent breakage or cracking of the filter.

The present invention is to solve the problems of the prior art as described above provides a composition for a silicon carbide filter that can enhance the thermal shock resistance of the filter by strengthening the bond between the silicon carbide, and a silicon carbide filter comprising the same and a method of manufacturing the same. It is.

The present invention is a silicon carbide as a means for solving the above problems; Inorganic oxides; And it provides a composition for a silicon carbide filter comprising an inorganic fiber.

The silicon carbide contained in the composition of the present invention preferably has an average particle diameter of 20 μm to 80 μm.

The inorganic oxide contained in the composition of the present invention is preferably at least one selected from the group consisting of silica, mullite, silica-alumina, glass, alumina, kaolin, clay, feldspar, and silica. In addition, the content of the inorganic oxide is preferably 5 to 25 parts by weight based on 100 parts by weight of silicon carbide.

It is preferable that the inorganic fiber contained in the composition of the present invention is at least one selected from the group consisting of non-oxide fiber, oxide fiber and metal fiber.

In addition, the length of the inorganic fiber is preferably 20㎛ to 200㎛, the content of the inorganic fiber is preferably 3 to 15 parts by weight relative to 100 parts by weight of silicon carbide.

The present invention provides a silicon carbide filter in which a silicon carbide segment containing the composition according to the present invention is integrated by a bonding material as another means for solving the above problems.

The present invention is another means for solving the above problems, the first step of producing a silicon carbide segment using the composition according to the invention; And it provides a method of manufacturing a silicon carbide filter comprising a second step of joining the segment produced in the first step.

The method of manufacturing the silicon carbide filter includes a third step of processing the outer wall surface of the joint prepared in the second step; And a fourth step of treating the processed outer wall surface with an outer wall finish.

The composition for the silicon carbide filter of the present invention includes an inorganic fiber, which further strengthens the bond between the silicon carbide with the inorganic oxide. Accordingly, the silicon carbide filter including the composition has excellent thermal shock resistance, and is excellent in resistance to crack generation and breakage during manufacturing and operation of the filter.

The present invention is silicon carbide; Inorganic oxides; And an inorganic fiber comprising a composition for a silicon carbide filter. The composition of the present invention can be produced in the oxidation atmosphere without the need to control the atmosphere by using the inorganic oxide as a bonding material of silicon carbide, characterized in that the bond between the inorganic oxide and the silicon carbide together with the inorganic oxide more strengthened do.

Accordingly, the silicon carbide filter to which the composition of the present invention is applied has improved thermal shock resistance and is excellent in resistance to crack generation and breakage during manufacturing and operation.

Hereinafter, the composition for silicon carbide filters of this invention is demonstrated concretely.

Silicon carbide included in the composition of the present invention has excellent heat resistance and is suitable as a filter material which is exposed to high temperatures several times during manufacturing and operation. Although not specifically limited, it is preferable that the said silicon carbide is particulate form, and in this case, it is preferable that average particle diameter is 20 micrometers-80 micrometers.

If the particle diameter is less than 20㎛ the pore (pore) formed in the filter is too small there is a risk that the back pressure is too high in the engine, if it exceeds 80㎛ the pore formed in the filter is too large to be discharged from the engine It is difficult to filter out particulate matter, and the strength of the filter may be too weak.

The composition of the present invention is characterized by including an inorganic oxide as a binder together with the silicon carbide described above. The inorganic oxide melts during firing and wets the surface of silicon carbide to serve to bond silicon carbide.

The inorganic oxide usable in the present invention is not particularly limited and is preferably at least one selected from the group consisting of silica, mullite, silica-alumina, glass, alumina, kaolin, clay, feldspar, and silica.

The inorganic oxide is preferably included in an amount of 5 to 25 parts by weight based on 100 parts by weight of silicon carbide. If the content is less than 5 parts by weight, the strength of the silicon carbide bonding strength is weak, there is a fear that the strength of the filter is lowered, if it exceeds 25 parts by weight inorganic oxide filling the pores (pore) can not form as many pores as necessary There is concern.

The composition of the present invention further comprises an inorganic fiber in addition to the above components, which serves to strengthen the bond between the silicon carbide with the inorganic oxide.

Examples of the inorganic fibers usable in the present invention include non-oxide based fibers such as carbon fibers, silicon carbide fibers, boron carbide fibers or boron nitride fibers; Oxide fibers such as silica, silica-alumina, alumina, mullite, potassium titanate fibers or zirconium oxide fibers; And it is preferably one or more selected from the group consisting of metal fibers such as stainless steel fibers or steel fibers, but is not limited thereto.

It is preferable that the length of the said inorganic fiber is 20 micrometers-200 micrometers. If the length of the inorganic fiber is less than 20 μm, the effect of improving the desired thermal shock may not be obtained. If the length of the inorganic fiber is more than 200 μm, there may be a problem in breakability during segment manufacture.

In addition, the inorganic fiber is preferably included in an amount of 3 to 15 parts by weight based on 100 parts by weight of silicon carbide. When the content is less than 3 parts by weight, there is a fear that the desired thermal shock improvement effect may not be obtained. When the content is more than 15 parts by weight, the content of the binder component is relatively low and there is a fear that the bonding force is lowered.

The composition for a silicon carbide filter of the present invention may further include at least one selected from the group consisting of an organic binder and a pore-forming agent in addition to the above-mentioned components in view of ease of molding.

At this time, examples of the organic binder that may be used include, but are not limited to, hydroxypropylmethylcellulose, methylcellulose, hydroxyethyl cellulose, carboxymethylcellulose, or polyvinyl alcohol.

The content of the organic binder is preferably 8 to 20 parts by weight based on 100 parts by weight of silicon carbide. If the content is less than 8 parts by weight, there is a fear that the molding strength is too weak, and if it exceeds 20 parts by weight, the strength after firing may be weakened.

In addition, the pore-forming agent serves to increase the porosity of the filter, and specific examples thereof include graphite, foamed resin, flour, starch, phenol resin, polymethyl methacrylate, polyethylene, polymethacrylate, or polyethylene terephthalate. However, it is not limited thereto.

The content of the pore-forming agent is preferably 4 to 10 parts by weight based on 100 parts by weight of silicon carbide. If the content is less than 4 parts by weight, too little pore may be formed. If the content is more than 10 parts by weight, too much pore may be formed, leading to a decrease in strength.

The invention also

A silicon carbide filter comprising a composition according to the invention is integrated with a bonding material.

In the silicon carbide filter of the present invention, the inorganic fibers included in the segment reinforce the bond between the silicon carbide together with the inorganic oxide. Accordingly, the silicon carbide filter of the present invention has excellent thermal shock resistance and is excellent in resistance to breakage and crack generation due to thermal stress generated during manufacturing and operation.

Hereinafter, an embodiment of the silicon carbide filter of the present invention will be described in detail with reference to the accompanying drawings.

1 and 2 are a perspective view and a cross-sectional view of a segment constituting a silicon carbide filter according to an aspect of the present invention, Figure 3 is a perspective view of a silicon carbide filter formed by joining a plurality of segments according to FIG. The silicon carbide filter is generally manufactured by joining the silicon carbide segments 1 with the joining material 5 and processing the outer wall surface of the joining material. In the silicon carbide segment 1, a plurality of cells 2 penetrated in the longitudinal direction are formed, and adjacent cells 2 are separated by a porous partition wall 3. In addition, the inlet side 1a or the outlet side 1b of the said cell 2 is sealed by the sealing material 4 by turns. Accordingly, when the silicon carbide filter is used for a diesel engine dust filter or the like, the gas G flowing into the cell 2 passes through the porous partition wall 3 and is discharged through an adjacent cell, and in the process Particulates in the body are collected in the porous partition wall 3. Excessive accumulation of particulates in the porous partition wall may cause a loss of pressure in the filter and a decrease in engine output, and thus, the collected particulates are subjected to a regeneration process that is removed every predetermined time. In this regeneration process, the portion of the particulate collection has a large temperature is increased compared to the small portion, there is a fear that problems such as crack generation and breakage due to the thermal stress. However, the silicon carbide filter of the present invention has excellent thermal shock resistance due to the excellent thermal properties of the segment as described above in the manufacturing process and the regeneration process to remove the collected fine particles, and excellent resistance to crack generation and breakage due to thermal stress. .

The invention also

A first step of producing a silicon carbide segment using the composition according to the invention; And a second step of joining the segments manufactured in the first step.

The first step of the present invention is to prepare silicon carbide segments using the composition according to the present invention.

Specifically, the silicon carbide segment may be manufactured by molding the composition according to the present invention in a predetermined form and then firing the composition and content of the composition used as described above. The method for molding the segment using the composition as described above is not particularly limited, and conventional means known in the art may be employed without limitation. For example, the desired shape can be molded to the composition of the present invention through an extrusion process. In the first step of the present invention, the molded article molded in the above manner may be dried by conventional means such as microwaves and hot air, and cut to a predetermined dimension to carry out the firing process.

Due to the firing process, the organic binder and the like are removed, and the silicon carbide is bonded by an inorganic oxide, and at this time, a segment having a stronger bond between the silicon carbides is prepared by the inorganic fiber.

The second step of the invention is the step of joining the segments produced in the first step. The method of joining a silicon carbide segment is not specifically limited, For example, the method of apply | coating a joining material to the outer peripheral surface of a segment, joining, and drying is mentioned. The bonding material used is not particularly limited, and conventional bonding materials known in the art can be used without limitation.

In the method for producing a silicon carbide filter according to the invention also

A third step of processing the outer wall surface of the joint prepared in the second step; And a fourth step of treating the processed outer wall surface with an outer wall finish.

The method of processing the outer wall surface of the segment in the third step is not particularly limited, and for example, a method of processing the outer wall surface of the joint in the form of a circle or a square using a grinding tool can be used.

The fourth step of the present invention is a step of treating the outer wall surface of the joined workpiece processed in the third step with an outer wall finish material. That is, in the third step, the cell of the segment may be open when the outer wall surface is processed, and thus, the step of treating the outer wall surface with the outer wall finishing material is necessary. At this time, the treatment method of the outer wall surface is not particularly limited, for example, after applying and drying the outer wall finishing material on the outer wall surface can be carried out through a process such as firing in a commonly used method according to the characteristics of the outer wall finishing material.

1 is a perspective view of a silicon carbide segment constituting a silicon carbide filter according to one aspect of the present invention.

2 is a cross-sectional view of a silicon carbide segment constituting a silicon carbide filter according to one aspect of the present invention.

3 is a perspective view of a silicon carbide filter in accordance with an aspect of the present invention.

<Description of Drawing>

1: silicon carbide segment 2: cell

3: porous partition wall 4: sealing material

5: bonding material

Claims (11)

Silicon carbide; Inorganic oxides; And an inorganic fiber comprising a silicon carbide filter. The method of claim 1, Silicon carbide filter composition, characterized in that the average particle diameter of 20 to 80㎛. The method of claim 1, The inorganic oxide is a silicon carbide filter composition, characterized in that at least one selected from the group consisting of silica, mullite, silica-alumina, glass, alumina, kaolin, clay, feldspar, and silica. The method of claim 1, The inorganic oxide is a composition for a silicon carbide filter, characterized in that contained in an amount of 5 to 25 parts by weight based on 100 parts by weight of silicon carbide. The method of claim 1, The inorganic carbide filter is a silicon carbide filter composition, characterized in that at least one member selected from the group consisting of non-oxide fibers, oxide fibers and metal fibers. The method of claim 1, The composition for a silicon carbide filter, characterized in that the length of the inorganic fiber is 20 to 200㎛. The method of claim 1, Silicon carbide filter composition, characterized in that the inorganic fiber is contained in an amount of 3 to 15 parts by weight with respect to 100 parts by weight of silicon carbide. The method of claim 1, The composition for a silicon carbide filter further comprises at least one selected from the group consisting of an organic binder and a pore-forming agent. A silicon carbide filter in which a silicon carbide segment comprising the composition according to any one of claims 1 to 8 is integrated by a bonding material. A first step of producing a silicon carbide segment using the composition according to any one of claims 1 to 8; And A method of manufacturing a silicon carbide filter comprising a second step of joining the segments produced in the first step. The method of claim 10, A third step of processing the outer wall surface of the joint prepared in the second step; And And a fourth step of treating the processed outer wall surface with an outer wall finish.

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