KR20090047848A - Composition for particulate filter, sic dpf and method for manufacturing the same - Google Patents

Abstract

The present invention relates to a composition for a dust filter comprising at least one selected from the group consisting of silicon powder and hollow silicon carbide beads, a silicon carbide dust filter produced using the same, and a method for producing the same. In the present invention, due to the excellent thermal properties of the components included in the composition, it is possible to remarkably improve the regeneration efficiency during the high temperature regeneration of the silicon carbide dust filter, and excellent bonding strength by the reaction and the high temperature reaction between each component included in the composition. It is possible to maintain the heat resistance and excellent heat shock resistance of the filter.

Silicon Powder, Hollow Silicon Carbide Beads, Compositions, Silicon Carbide Dust Filters, High Temperature Regeneration, Thermal Shock Resistance, Thermal Conductivity

Description

Composition for dust filter, silicon carbide dust filter and manufacturing method thereof {Composition for particulate filter, SiC DPF and method for manufacturing the same}

The present invention relates to a dust filter composition including a component having excellent thermal properties and having excellent thermal conductivity and thermal shock resistance, a silicon carbide dust filter manufactured using the same, and a method for manufacturing the same.

Diesel engines have a high fuel efficiency and long durability of at least about 20-30% compared to gasoline engines. In addition, the diesel engine has a relatively low emissions such as CO ₂ , CO and evaporated hydrocarbons mainly from the gasoline engine has been positively evaluated in terms of the environment. However, diesel engines are inferior in gas emission prevention technology compared to gasoline engines, and particulate materials such as nitrogen oxides and soot, which are mainly emitted from diesel engines, are recognized as a major cause of air pollution. The particulate matter absorbs more light than any other particles generated in urban areas and the like, thus reducing visibility. In addition, the particulate material is fine and contains a large amount of chemicals, causing health and property damage such as lowering air quality, respiratory disease, or lung cancer.

As a method for reducing soot in the exhaust gas of a diesel engine, a combustion chamber improvement of the engine or a method using a diesel oxidation catalyst (DOC) may be used. However, this method alone has a limitation in completely removing soot.

Accordingly, a method of physically removing particulate matter using a diesel particulate filter (DPF) has attracted attention. Conventionally, cordierite-based ceramics have been mainly used as materials for such filters. Cordierite has the advantage of excellent thermal shock, and can be freely manufactured in a structure of various sizes and shapes. However, since cordierite has a low melting point, there is a problem in that when used for a dust filter or the like, it is locally dissolved or destroyed in a regeneration process of a structure, that is, a high temperature process of removing adsorbed dust by applying high temperature heat.

Accordingly, recently, attention has been paid to silicon carbide (SiC) quality filters having a high melting point and excellent thermal conductivity. However, since silicon carbide has a large coefficient of thermal expansion, cracking occurs due to stress generated during heating and cooling. Therefore, the silicon carbide filter is difficult to manufacture in monolithic form, such as cordierite, and is generally manufactured by forming a rectangular column segment and then joining a plurality of them.

Korean Patent Laid-Open Publication No. 2007-62449 discloses a segment constituting a silicon carbide filter including oxide particles such as alumina, zirconia, titania and silica; Disclosed is a technique of bonding and integrating an inorganic binder such as silica sol or alumina sol and a sealing material (bonding agent) layer containing a specific colorant. U.S. Patent Application Publication No. 2006-216466 also discloses containing an inorganic binder such as silica sol or alumina sol and oxide particles of a specific particle size as a seal material for bonding a plurality of honeycomb units.

However, when the silicon carbide segments are bonded using a binder in which oxide particles or oxide fibers, carbide powders, and / or inorganic binders are mixed as disclosed in the foregoing patent, the binder has thermal conductivity during filter regeneration. Acts as a heat transfer barrier between the excellent silicon carbide segments, there is a problem that the regeneration characteristics are lowered. In addition, in the case of the binder for the extruded silicon carbide filter, in order to improve the bonding property, it is heat treated at about 1200 ℃ or more. At this time, the internal stress is applied due to the plastic shrinkage caused by the high temperature reaction of the oxide fiber and the inorganic binder included in the bonding agent, and there is a problem that cracks occur during cooling. Have.

The present invention has been made in consideration of the above-described prior art, and by applying a material having excellent thermal properties such as thermal conductivity and thermal shock resistance to the composition, the heat transfer between the silicon carbide segments is facilitated, thereby increasing the regeneration area during regeneration. It aims at improving regeneration efficiency and at the same time improving the bonding strength between segments and the heat shock resistance of the entire filter.

The present invention provides a dust filter composition comprising at least one selected from the group consisting of silicon powder and hollow silicon carbide beads as a means for solving the above problems.

The present invention relates to a silicon carbide dust filter in which a plurality of honeycomb segments are joined by a composition according to the present invention as another means for solving the above problems.

Silicon carbide dust filter of the present invention is preferably the outer wall finishing treatment by the composition according to the present invention.

The present invention as another means for solving the above problems, the first step of bonding the silicon carbide honeycomb segment to the composition according to the present invention; A second step of processing the outer wall surface of the segment joint manufactured in the first step; And a third step of applying and drying the outer wall finish on the outer wall surface processed in the second step.

In the present invention, due to the excellent thermal properties of the binder and / or the outer wall finishing material constituting the silicon carbide dust filter, it is possible to significantly improve the regeneration efficiency during high temperature regeneration. In addition, the bonding strength can be excellently maintained by the reaction between the components contained in the composition and the high temperature reaction, and the heat shock resistance of the filter can be excellently maintained.

The present invention relates to a dust filter composition comprising at least one selected from the group consisting of silicon powder and hollow silicon carbide beads. The present invention comprises the above components having excellent thermal properties, and is excellent in thermal conductivity and thermal shock resistance. Accordingly, the composition of the present invention can be applied to a silicon carbide dust filter (SiC DPF) to improve the regeneration efficiency, and also maintain excellent bonding strength and thermal shock resistance between segments.

Hereinafter, the composition of the present invention will be described in detail.

The composition of the present invention is characterized in that it comprises silicon powder and / or hollow silicon carbide beads. The composition of the present invention preferably includes the two components at the same time, but is not limited thereto. That is, in the composition of the present invention, the silicon powder or the hollow silicon carbide beads may be included alone or simultaneously. Such silicon powder and hollow silicon carbide beads are included in the composition of the present invention, and serves to improve thermal properties such as thermal conductivity and thermal shock resistance.

The composition for a dust filter of the present invention may further include inorganic particles, inorganic fibers and / or binders, etc., in addition to the above components.

Inorganic particles in the above serves to improve the adhesive strength and thermal shock resistance of the composition. The type of inorganic particles that can be used in the present invention is not particularly limited, and conventional ones in this field such as alumina, silica, titania, silicon carbide, silicon nitride, cerima, mullite or zirconia can be used without limitation. .

The composition of the present invention may also further comprise an inorganic fiber. The kind of inorganic fiber that can be used in the present invention is not particularly limited, and for example, glass fiber, alumina fiber, silicon carbide fiber, potassium titanate fiber, silica-alumina fiber or aluminum borate fiber can be used.

The composition of the present invention may also further comprise a binder. An organic binder or an inorganic binder may be used as the binder, but it is preferable to use an inorganic binder in that sufficient strength can be obtained even at a low firing temperature. Examples of such inorganic binders include, but are not limited to, inorganic sol or clay-based binders. Specific examples of the inorganic sol may include silica sol, alumina sol or titania sol, and the like, and examples of the clay-based binder may include clay, kaolin, montmorillonite or cyclic clay (sepiolite or attapulgite). In the present invention, one or a mixture of two or more of the above can be used.

The method for producing a composition for a dust filter of the present invention containing each of the above-mentioned components is not particularly limited, and may be prepared by a conventional method in the art using each of the above-described components.

The invention also relates to a silicon carbide dust filter (SiC DPF) in which a plurality of honeycomb segments are joined by a composition according to the invention. The composition constituting the silicon carbide dust filter of the present invention has excellent thermal properties, and therefore, high temperature heat is rapidly transferred from the center of the highest temperature to the outside in the regeneration stage of the filter. Accordingly, the silicon carbide dust filter of the present invention has an advantage that the regeneration in the segment outside the filter can be efficiently performed. In addition, it has the advantage of having excellent bonding strength and excellent thermal shock resistance by the reaction between the components contained in the composition and the high temperature reaction during the high temperature baking process.

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

The structure of the silicon carbide filter used in the present invention is not particularly limited. That is, in the present invention, most conventional filters made of silicon carbide can be used. Examples of such a filter include a honeycomb filter and a candle filter. Among them, a honeycomb filter is more preferable. Such silicon carbide honeycomb filters are manufactured by joining a plurality of honeycomb segments in the shape of a square bar column.

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 view of a honeycomb structure formed by joining a plurality of segments according to FIG.

Segment 1 constituting the honeycomb structure is generally manufactured by adding an organic binder such as a polymer compound and an inorganic binder as a sintering aid to silicon carbide powder, and then extruding, cutting, drying and firing it. In the segment 1 constituting the honeycomb structure, a plurality of channels 3 are formed to penetrate in the longitudinal direction, and either the inlet or the outlet of the channel 3 is alternately sealed by the sealing material 3a. (plugging). Accordingly, when the silicon carbide filter is used for a diesel particulate filter (DPF) or the like, the exhaust gas G introduced into the channel 3 passes through the porous partition wall 2 and then another adjacent channel. Outflow through (3), and thus dust contained in the exhaust gas (G) is collected in the porous partition (2).

In the present invention, the segment 1 as described above is bonded by the composition 4 according to the present invention after the firing process, the outer peripheral part is processed through a grinding process or the like, and then treated with an outer wall finish. Although it does not specifically limit, In this invention, it is preferable to use the thing of the same composition as the composition of this invention mentioned above as an exterior wall finishing material. In this case, even when exposed to room temperature in the manufacturing or regeneration process of the filter, since the heat is released at a high speed, the thermal gradient between the exterior wall finish and the atmosphere is minimized, thereby minimizing thermal shock breakage of the exterior wall finish. Will be.

The present invention also provides

A first step of bonding the silicon carbide honeycomb segment to the composition of the present invention;

A second step of processing the outer wall surface of the segment joint manufactured in the first step; And

It relates to a method for producing a silicon carbide dust filter comprising a third step of applying and drying the outer wall finish on the outer wall surface processed in the second step.

The first step of the present invention is the step of joining the segments constituting the filter using the composition of the present invention. At this time, the method for producing the silicon carbide honeycomb segment is not particularly limited. For example, the segment may be manufactured through a general process such as extrusion molding, cutting, drying and firing using a sinterable silicon carbide slurry or paste incorporating silicon carbide powder, organic and inorganic binder as a raw material.

In the first step of the present invention, such segments are joined. At this time, the bonding method is not particularly limited, and after applying the composition according to the invention on the surface of the segment, it may be carried out through a bonding and drying process.

In the second step of the present invention is a step of processing the outer wall surface to form a cylindrical or oval shape according to the purpose of the bonded material prepared as described above, this is usually carried out through a grinding process or the like.

Subsequently, in the third step of the present invention, the outer wall finish is applied to the processed outer wall and dried. After the outer wall processing process of the segment joining in the second step, the channel of the outer peripheral part may be open, which is required to finish the outer wall finish. As described above, it is preferable to use the same composition as the composition of the present invention as the outer wall finishing material, and the advantages thereof are as described above.

In the present invention, it is also preferable to calcinate or bake the silicon carbide dust filter through heat treatment at an appropriate temperature after the first to third steps. Through such heat treatment, a film of inorganic particles such as silica is formed on the surface of the silicon carbide beads and silicon powder added to the composition and / or the outer wall finish, and bonded by the above-described sol-gel reaction and high temperature reaction. The effect of increasing the bond strength of the layer can be obtained. At this time, the heat treatment conditions are not particularly limited, and the average person skilled in the art can easily select appropriate conditions according to the size and use of the filter.

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

2 is a cross-sectional view of the honeycomb segment of FIG. 1.

3 is a diagram illustrating a honeycomb structure in which the honeycomb segment of FIG. 1 is bonded according to an embodiment of the present invention.

<Description of Drawing>

1: honeycomb segment 2: bulkhead

3: channel 3a: sealing material

4: binder 5: finish

Claims (9)

Dust filter composition comprising at least one selected from the group consisting of silicon powder and hollow silicon carbide beads. The method of claim 1, Dust filter composition, characterized in that it further comprises one or more selected from the group consisting of inorganic particles, inorganic fibers and binders. The method of claim 2, The inorganic particles are at least one selected from the group consisting of alumina, silica, titania, silicon carbide, silicon nitride, cerima, mullite and zirconia. The method of claim 2, The inorganic fiber is at least one selected from the group consisting of glass fibers, alumina fibers, silicon carbide fibers, potassium titanate fibers, silica-alumina fibers, and aluminum borate fibers. The method of claim 2, The binder is a dust filter, characterized in that at least one selected from the group consisting of silica sol, alumina sol, titania sol, clay, kaolin, montmorillonite and crushed clay. A silicon carbide dust filter in which a plurality of honeycomb segments are joined by a composition according to any one of claims 1 to 5. The method of claim 6, A silicon carbide dust filter, wherein the filter is a honeycomb filter. A silicon carbide dust filter, which is finished with an outer wall by the composition according to any one of claims 1 to 5. A first step of bonding the silicon carbide honeycomb segment to the composition according to any one of claims 1 to 5; A second step of processing the outer wall surface of the segment joint manufactured in the first step; And A method for producing a silicon carbide dust filter comprising a third step of applying and drying the outer wall finish on the outer wall surface processed in the second step.

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