WO2016167497A1

WO2016167497A1 - Honeycomb structure having crack resistance

Info

Publication number: WO2016167497A1
Application number: PCT/KR2016/003238
Authority: WO
Inventors: 이현재; 올렌켄
Original assignee: 주식회사 엔바이온
Priority date: 2015-04-16
Filing date: 2016-03-30
Publication date: 2016-10-20
Also published as: KR20160124292A; CN107532490B; CN107532490A; KR101714363B1

Abstract

Disclosed is a honeycomb structure having a high level of crack resistance. The present invention provides a honeycomb structure comprising a plurality of cells, which extend in the longitudinal direction, in order to provide a channel such that a fluid can flow along the same, and which are delimited by barriers, wherein the honeycomb structure comprises an outer wall that surrounds the same, and at least a part of the outer wall is provided with a stress relief feature. The present invention can provide a honeycomb structure that is scalable while suppressing generation and propagation of cracks efficiently.

Description

Honeycomb Structure with Crack Resistance

The present invention relates to a honeycomb structure of the present invention, and more particularly, to a honeycomb structure having high crack resistance.

In general, a honeycomb structure is a structure in which a plurality of cells for fluid flow are formed in a honeycomb shape, and is used for various purposes such as heat storage material, diesel particulate filter (DPF), and catalyst carrier.

Ceramics-based honeycomb structure is manufactured by a molding method such as extrusion, injection, etc., there is a problem that it is difficult to expand to a large-size honeycomb structure because a crack occurs on the surface of the structure during the drying process after molding. Due to this problem, a method of stacking and bonding a small honeycomb structure to a large capacity fluid flow is used, but this method requires the design of additional processes such as lamination and bonding.

On the other hand, silicon carbide is easy to accumulate and thermally regenerate due to high thermal conductivity, so that the use of Regenerative Thermal Oxidation System (RTO) as a heat storage material is considered. In addition, silicon carbide has a high heat resistance and chemical resistance has been increasingly used as a filter such as DPF. However, due to the high brittleness, cracks are inevitable in the molding and drying process at the time of large capacity, and have a problem of being exposed to thermal shock due to repeated heating and cooling in a high temperature operating environment.

SUMMARY OF THE INVENTION In order to solve the problems of the prior art, an object of the present invention is to provide a honeycomb structure having a structure effective to suppress crack generation in ceramic-based honeycomb structures such as silicon carbide, cordierite, alumina, mullite, and the like. .

In addition, an object of the present invention is to provide a honeycomb structure having crack resistance and easy capacity increase.

In order to achieve the above technical problem, the present invention, in the honeycomb structure including a plurality of cells extending in the longitudinal direction and partitioned by a partition to provide a channel for the flow of fluid, the outer wall surrounding the honeycomb structure And at least a portion of the outer wall is provided with a stress relief feature.

Here, the stress relaxation feature may be implemented by the outer wall end portion. At this time, the outer wall end portion may extend in the longitudinal direction of the honeycomb structure. In addition, the outer wall termination portion may be implemented by opening at least a portion of at least one cell constituting the honeycomb structure.

In one embodiment of the present invention the stress relaxation feature may be implemented by the outer wall bending portion. At this time, the outer wall bending portion may have a notched surface shape. On the contrary, the outer wall bending part may have a curvature recessed inward.

In addition, according to an embodiment of the present invention to achieve the above technical problem, in the honeycomb structure comprising a plurality of cells extending in the longitudinal direction and partitioned by a partition to provide a channel for the flow of fluid, the honeycomb The structure includes a plurality of partitionable blocks, a boundary between the blocks, and an outer wall surrounding the structure, wherein the outer wall at a position corresponding to the boundary between the blocks is provided with at least one stress relieving feature. To provide.

In one embodiment of the present invention, the cell size of the boundary between the blocks is preferably smaller than the cell size inside the block. At the same time or separately, the partition wall of the boundary between the blocks may have a larger thickness than the partition wall inside the block.

Honeycomb structure according to an embodiment of the present invention can be applied to heat storage material, diesel particulate filter, catalyst carrier and the like.

According to an embodiment of the present invention, a channel may be formed at the center of the honeycomb structure by removing at least some of the partition walls.

According to the present invention, it is possible to provide a honeycomb structure having a structure that is effective in suppressing crack generation and propagation. Accordingly, the honeycomb structure of the present invention is easily scalable.

1 is a view for explaining a honeycomb structure of the present invention.

2 is a diagram schematically showing a cross-sectional structure of a honeycomb structure according to a first embodiment of the present invention.

3 is a diagram schematically illustrating a cross-sectional structure of a honeycomb structure according to a second embodiment of the present invention.

4 is a diagram schematically showing a cross-sectional structure of a honeycomb structure according to a third embodiment of the present invention.

5 is a view for explaining the stress relaxation mechanism of the residual stress relaxation feature (Rf) of the present invention described above.

6 is a cross-sectional view for schematically illustrating a honeycomb structure according to a fourth embodiment of the present invention.

7 is a cross-sectional view for schematically illustrating a honeycomb structure according to a fifth embodiment of the present invention.

8 is a cross-sectional view for schematically illustrating a honeycomb structure according to a sixth embodiment of the present invention.

FIG. 9 is a view illustrating some components of FIG. 8 in detail.

10 is a cross-sectional view for schematically illustrating a honeycomb structure according to a seventh embodiment of the present invention.

FIG. 11 is a view illustrating some components of FIG. 10 in detail.

12 is a diagram schematically showing a honeycomb structure according to an eighth embodiment of the present invention.

13 is a diagram schematically showing a honeycomb structure according to a ninth embodiment of the present invention.

14 is an enlarged view of a portion of FIG. 13.

15 is a view schematically showing a honeycomb product according to another embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is a view for explaining the structure of the honeycomb structure.

Referring to FIG. 1, the honeycomb structure 10 includes a plurality of cells 12 partitioned in a lattice shape.

The cell 12 provides a channel for the flow of the fluid. The cell 12 extends in the longitudinal direction of the honeycomb structure 10, and in some cases, one end of the cell 12 may be closed or both ends may be open. Individual cells of the honeycomb structure 10 are partitioned by cell walls. As shown, the inner wall 14 and outer wall 16 partition the cells of the honeycomb structure 10 and the thickness thereof can be appropriately designed. Typically, the outer wall 16 is designed to have a larger thickness than the inner wall 14, and in some cases, the inner wall 14 may have a different thickness. Although each cell is shown as having a cuboid shape in cross section in FIG. 1, the cross-sectional shape of the cell is merely exemplary.

The honeycomb structure may be made of various materials such as cordierite, alumina, mullite, and silicon carbide. In addition, the honeycomb structure may be made of a porous material to facilitate fluid flow between each cell.

Hereinafter, a method of manufacturing a honeycomb structure for heat storage material will be described.

At least one selected from the group consisting of cordierite, alumina, mullite, and SiC is the main material, and as a molding aid, a raw material including an organic binder such as PVA and MC and an inorganic binder such as clay, alumina, and silica is blended. do.

In addition, paraffin wax, steric acid, mineral oil or high boiling oil may be added to the raw material.

The blended raw material is kneaded uniformly in a kneader, aged for a certain period of time, and then extruded through an extruder.

The molded body extruded by the extruder is cut to a certain size and dried. Wet drying, vacuum drying and microwave drying may be used to make the drying speed uniform. If it dries to a certain strength, dry it for more than 12 hours at 50 ~ 150 ℃. If much moisture is left in the drying process, the water evaporates rapidly during the sintering process and may cause cracks, thereby minimizing moisture in the molded body.

The sintering process is carried out after drying, and the optimum sintering conditions are set according to the sintering characteristics of the main material and the inorganic binder. Usually, the sintering process is performed at 800 to 1600 ° C. for 3 to 24 hours.

On the other hand, in the case of DPF and catalyst carrier applications, a porous honeycomb structure may be prepared by adding a pore former that can be oxidized or volatilized by heat treatment such as carbon component, starch, polymer beads, and the like.

The honeycomb structure shrinks upon drying after molding, and generally dries faster on the structure surface than inside. This causes a difference in the drying rate between the surface of the structure and the interior, and thus residual stress exists on the surface of the outer wall of the structure. This residual stress is the tensile stress caused by the internal structure constraining the contraction of the outer wall surface. Thus, the tensile stress remaining on the outer wall surface causes the generation and propagation of cracks beyond a certain magnitude that the structure can tolerate. 1 illustrates a crack (C) generated during drying on the upper surface of the structure. Similar stresses and cracks can occur in cycles of heating and cooling during honeycomb structure operation.

As the size of the unit honeycomb structure increases, the difference in drying rate inside and outside the structure increases, and accordingly, the magnitude of the stress induced on the outer wall also increases. Therefore, the capacity of the honeycomb structure needs to be accompanied by a design considering resistance to cracks.

2 is a view schematically showing a cross-sectional structure of the honeycomb structure according to an embodiment of the present invention.

Referring to FIG. 2, the honeycomb structure 100 is exemplarily composed of a cell 112, an inner wall 114, and an outer wall 116 arranged in a lattice arrangement. In the present invention, the honeycomb structure 100 has a residual stress relaxation characteristic Rf on the outer wall 116.

In one embodiment of the invention, the residual stress relaxation feature Rf includes an outer wall termination that breaks continuity around the outer wall. In the present invention, the outer wall end portion functions as a free end. That is, the outer wall is no longer continuous along the perimeter of the structure, and the cut off portion forms the outer wall free end.

Although the outer wall end portion is shown as a gap in the figure, it extends in the longitudinal direction of the honeycomb structure, that is, the extending direction of the cell in three dimensions. The outer wall end portion may extend throughout the longitudinal direction of the honeycomb structure, or alternatively may extend only partially in the longitudinal direction.

In addition, although only one free end is shown in the figure, in the present invention, the outer wall end portion may be repeated, for example, a predetermined period or irregularly, based on the cell spacing.

In the present invention, the honeycomb structure can be manufactured by the following method.

First, the blended raw material is kneaded uniformly in a kneader, subjected to aging for a certain period of time, and then extruded through an extruder. The mold of the extruder for the extrusion of the honeycomb structure of FIG. 2 may be provided with a honeycomb structure and a corresponding structure for forming the stress relief feature Rf. For example, the corresponding structure may have a negative shape relative to the stress relaxation feature Rf. Specifically, as shown in FIG. 2, a protruding structure extending in the longitudinal direction may be formed at a corresponding position of the extrusion die in order to form the long slit-shaped outer wall end portion.

Although the honeycomb structured manufacturing method illustrated in FIG. 2 is exemplified above, the same method may be applied to the above manufacturing method except that the shape of the mold is changed.

The residual stress relief feature Rf of FIG. 3 is another implementation of the outer wall termination. In this embodiment, one cell does not have an outer wall and is exposed to the outside. Even in such a structure, the residual stress relaxation feature still breaks the continuity of the outer walls on the left and right sides of the cell.

FIG. 3 shows how to form an outer wall termination by exposing a cell, but those skilled in the art will appreciate that two or more cells adjacent to the outer wall surface or two or more cells adjacent in a direction perpendicular to the outer wall surface are shown in the art. It will be appreciated that they can be exposed in the same way.

Unlike FIG. 4, the outer wall termination is implemented by removing some outer walls of two adjacent surface cells. In this case, the inner wall intersection point (dashed circle) of the lower cell is exposed to the outside.

As shown in FIG. 5A, the residual tensile stress acts at any point P on the surface of the outer wall 116 as the dry shrinkage occurs. This can be explained by the limitation of the structure on the contraction of the outer wall. That is, the outer wall cannot contract to the extent corresponding to drying and the corresponding tensile stress remains on the outer wall as a stress. This tensile stress generates and propagates surface cracks.

As shown in (b) of FIG. 5, the deformation of the outer wall may be caused by the residual stress relaxation feature Rf such as the outer wall end portion. That is, the outer wall end portion functions as a free end, so that the structure portion adjacent thereto can be deformed in a direction to solve or alleviate the residual stress. For example, the outer wall adjacent to the free end of the outer wall can be relatively freely contracted, so that the residual stress is eliminated.

In addition, in the present embodiment, the residual stress relaxation characteristic Rf such as the free end may act as an obstacle to propagation of the crack. Cracks generated on the outer wall surface propagate the outer wall. However, when reaching the free end, which is a discontinuous section of the outer wall, the propagation energy of the crack is released and as a result, the stress at the free end can be relaxed. In this case, the propagation of cracks can be efficiently suppressed by arranging the plurality of stress relaxation features Rf at predetermined intervals on the outer circumferential surface of the structure.

Referring to FIG. 6, the honeycomb structure 100 has a residual stress relaxation characteristic Rf such as an outer wall bending portion.

As shown, at some point of the structure a portion of the outer wall is bent into the honeycomb structure. As illustrated, the outer wall bending portion may have a negative curvature. The stress is relaxed in the outer wall bend in a manner similar to that described with respect to FIG. 5. In the outer wall bending portion, the structure has an effect similar to the deformation at the free end. That is, the outer wall length corresponding to the cell increases while the outer wall thickness is kept substantially constant in the outer wall bending portion. The increased outer wall length can serve as a buffer for outer wall deformation.

As in FIG. 6, the honeycomb structure 100 includes an outer wall bending portion as a residual stress relaxation characteristic Rf. Although the unit length of the outer wall increases in the outer wall bending portion, the outer shape is different in that the outer shape is notched, not negative curvature.

As described above, the honeycomb structure 100 having an external appearance having a rectangular pillar shape has been described, but the honeycomb structure of the present invention is not limited thereto. It will be appreciated by those skilled in the art that, for example, a cylindrical honeycomb structure can be designed to have the stress relaxation features of the present invention. In this case, at least one stress relaxation feature may be arranged at predetermined intervals along the circumference of the honeycomb structure to extend in the longitudinal direction of the structure.

As described above, the honeycomb structure 100 according to the embodiment of the present invention can suppress crack generation and propagation. Accordingly, it is possible to implement a honeycomb structure having a large capacity and a large area. On the other hand, the stress relaxation mechanism according to the embodiments of the present invention described above is for the purpose of understanding the present invention. The honeycomb structure 100 of the present invention may suppress the generation and propagation of cracks by a stress relaxation mechanism different from the above, and such a mechanism naturally falls within the scope of the technical idea of the present invention.

Hereinafter will be described an embodiment of a large capacity honeycomb structure according to an embodiment of the present invention.

Referring to FIG. 8, the honeycomb structure 200 includes a plurality of sub blocks 110. Each sub block 110 may be approximately 7.5 cm long and 30 cm long, for example. In this case, the cell size of the structure 200 is preferably 15 to 50 cpsi for the heat storage material, 25 to 100 cpsi for the DPF, and 50 to 400 cpsi for the catalyst carrier. Of course, in the present invention, the cell size may be set to an appropriate size as required.

An outer wall 116 surrounds the circumference of the plurality of sub blocks 110. Residual stress relaxation characteristics Rf are provided at predetermined points of the outer wall. The residual stress relaxation feature Rf may be configured as an outer wall end portion or an outer wall bending portion as described above. As shown, the residual stress relaxation characteristic Rf may be formed at the boundary between the sub blocks, but the present invention is not limited thereto. For example, the residual stress relaxation feature Rf may be installed at an intermediate point of the outer wall of the sub block 110. In addition, the number of residual stress relaxation characteristics Rf is not specifically limited. For example, a plurality of residual stress relief features may be installed at appropriate intervals on the upper surface of the structure 200.

FIG. 9A is a diagram illustrating the inside of the sub-block (part A) of FIG. 8 in detail. As shown in FIG. 9A, the sub block is an aggregate of cells 112 spaced apart by the inner wall 114. As shown, the thickness of the inner wall 114 in the sub-block may be maintained at a constant interval (d1).

9B is a diagram illustrating in detail the boundary B between the subblocks of FIG. 8. As shown in FIG. 9B, it can be seen that the plurality of cells 112 partitioned by the inner wall 114 and the like continue in the sub-block boundary portion B as in the interior. In addition, FIG. 9B shows that the thickness d2 of the inner wall defining the boundary portion may be formed thicker than the thickness of the inner wall thickness d1 of other cells.

10 and 11 are cross-sectional views for schematically explaining a honeycomb structure according to a seventh embodiment of the present invention.

Referring to FIG. 10, the honeycomb structure 300 is divided into sub blocks B1, B2, B3, and B4 similarly to FIG. 8.

As shown in Fig. 11A, the interior A of each block is composed of a plurality of partitioned cells. However, as shown in (b) of FIG. 10, cells having a narrower width than the inside are arranged at the boundary portion 140 of the block, and the inner wall thickness d3 of the boundary portion 140 is the inner wall thickness d1 within the block. It is arranged to have a larger value. This complements the structure strength at the boundary.

However, it will be appreciated by those skilled in the art that the thickness and cell size of the inner wall constituting the block boundary 140 in the present embodiment can be appropriately adjusted according to design requirements.

Referring to FIG. 12, it can be seen that the honeycomb structure 400 is composed of sixteen sub blocks 110. In addition, four adjacent sub-block sets form a honeycomb structure having the structure as shown in FIG. 8, and four sub-block sets gather the boundary portion 140 at the boundary to form the entire honeycomb structure 400.

The outer wall of the honeycomb structure 400 is provided with a stress relaxation feature Rf at an appropriate position, for example, at the subblock boundary. As shown, the stress relaxation feature Rf may be configured by an outer wall termination, an outer wall bending portion, or a combination thereof.

Referring to FIG. 13, as described with reference to FIG. 12, the honeycomb structure 500 is composed of 16 subblocks 110, and four sets of subblocks gather together at the boundary portion 140 to form a whole honeycomb structure. 400 is formed. 12, the stress relief feature Rf is provided on the outer wall of the honeycomb structure 500.

The structure of the honeycomb center portion is different from that of the structure of FIG.

Referring to FIG. 14, the center portion Cf of the honeycomb structure 600 has a shape in which a partition wall partitioning some cells is removed. Such a center portion facilitates the supply of drying air along the center of the center during drying, and may act to relieve stress during shrinkage due to the drying of the center like the stress relaxation feature of the outer wall. Although a cross-shaped channel is shown in FIG. 14, this is only an example of the present invention, and it will be appreciated by those skilled in the art that various channels such as 'ㅏ' and 'ㅓ' may be formed according to a method of removing the inner partition of the center part. will be. In addition, the center portion structure such as the cruciform channel of the present embodiment can be similarly applied to the other honeycomb structures described herein.

In the above-described embodiments, the honeycomb structure is illustrated as having a hexagonal column shape, but the honeycomb product may be implemented in a cylindrical columnar shape.

15 exemplarily shows a honeycomb product having a cylindrical columnar shape.

Referring to FIG. 15, the honeycomb product 600 includes a plurality of sub blocks 110. The honeycomb product 600 having such a structure may be implemented by variously combining the honeycomb structure of the present embodiment described above.

The honeycomb structure described with reference to FIG. 8 may be used as the honeycomb structure 200 including four central sub-blocks 110. Of course, the honeycomb structure 200 as illustrated in FIGS. 10 and 12 may be used as the honeycomb structure 200. The eight sub-blocks 110 adjacent to the honeycomb structure 200 may be manufactured by joining a portion of a separate honeycomb structure to the honeycomb structure 200.

Alternatively, the central four sub-blocks 110 may be formed of a honeycomb structure 100 as shown in FIGS. 2 to 4, 6, and 7, respectively. In this case, peripheral sub-blocks may be manufactured by bonding a portion of the honeycomb structure to the honeycomb structure 200.

The honeycomb structure of the present invention can be used in various applications such as heat storage material, diesel particulate filter (DPF), catalyst carrier and the like.

Claims

In a honeycomb structure comprising a plurality of cells extending in the longitudinal direction and partitioned by a partition wall to provide a channel for the flow of fluid,

An outer wall surrounding the honeycomb structure,

Honeycomb structure, characterized in that at least a portion of the outer wall is provided with a stress relaxation feature.
The method of claim 1,

The stress relief feature is a honeycomb structure, characterized in that it comprises an outer wall end.
The method of claim 2,

And the outer wall end portion extends in the longitudinal direction of the honeycomb structure.
The method of claim 2,

And the outer wall end portion opens at least a portion of at least one cell constituting the honeycomb structure.
The method of claim 1,

The stress relaxation characteristic is a honeycomb structure, characterized in that it comprises an outer wall bending portion.
The method of claim 5,

The outer wall bending portion honeycomb structure, characterized in that the surface shape of the notch shape.
The method of claim 5,

And the outer wall bending part has a curvature recessed therein.
The method of claim 1,

Honeycomb structure, characterized in that the channel is formed in the center of the honeycomb structure by removing at least a portion of the partition wall.
In a honeycomb structure comprising a plurality of cells extending in the longitudinal direction and partitioned by a partition wall to provide a channel for the flow of fluid,

The honeycomb structure includes a plurality of partitionable blocks, a boundary between the blocks, and an outer wall surrounding the structure,

Honeycomb structure, characterized in that the outer wall at the position corresponding to the boundary between the blocks is provided with at least one stress relaxation feature.
The method of claim 8,

And the cell size of the boundary between the blocks is smaller than the cell size inside the block.
The method of claim 8,

The partition wall of the boundary between the blocks is larger than the partition wall inside the honeycomb structure, characterized in that.
The method of claim 8,

Honeycomb structure, characterized in that the channel is formed in the center of the honeycomb structure by removing at least a portion of the partition wall.
The heat storage material containing the honeycomb structure as described in any one of Claims 1-10.
A diesel particulate filter comprising the honeycomb structure according to any one of claims 1 to 10.