JP2022111744A - Honeycomb structure, electric heating type carrier, and exhaust emission control system - Google Patents

Abstract

To provide a honeycomb structure, an electric heating type carrier, and an exhaust emission control device that have good thermal shock resistance, and have a uniform heat generation distribution at energization.SOLUTION: A honeycomb structure includes: a ceramic columnar honeycomb structure portion that has an outer peripheral wall, and a partition wall arranged inside the outer peripheral surface and partitioning and forming a plurality of cells penetrating from one end surface to the other surface to form a channel; and a pair of electrode layers that is provided so as to extend in a strip shape in a channel direction of the cells on an outer surface of the outer peripheral wall, across a center axis of the columnar honeycomb structure portion. On a cross-section vertical to the channel direction of the cells of the columnar honeycomb structure, in an area S, a linear slit that does not reach to the outer peripheral wall is provided, an absolute value θ of an inclination of the slit with respect to a center line P is 60 degree or less, and the slit is provided on at least, one end surface of the columnar honeycomb structure portion.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a honeycomb structure, an electrically heated carrier, and an exhaust gas purification device.

In recent years, an electrically heated catalyst (EHC) has been proposed in order to improve the deterioration of exhaust gas purification performance immediately after engine start-up. The EHC, for example, connects metal electrodes to a columnar honeycomb structure made of conductive ceramics, and heats the honeycomb structure itself by energizing, so that the temperature can be raised to the activation temperature of the catalyst before starting the engine. is.

EHCs are required to have good thermal shock resistance because they receive heat and impact from the engine. When cracks occur in the honeycomb structure of the EHC due to heat or impact from the engine, the conduction paths in the honeycomb structure are changed and heat is generated locally, resulting in deterioration of the catalyst. Moreover, the energization resistance increases, making it difficult to control the energization. As a result, the exhaust gas purification efficiency of the EHC may deteriorate.

In Patent Document 1, in a honeycomb heater in which a honeycomb structure made of a conductive material is provided with an electrode for conducting electricity, a parallel circuit is provided in the honeycomb structure in order to adjust the amount of heat generated by the honeycomb structure, which is a heat-generating portion. Structures are disclosed which are slit to form. A slit is a notch made in a partition wall or the like of a honeycomb structure.

Patent Document 2 discloses a honeycomb structure in which an end face is divided into a plurality of current paths by providing a plurality of slits in the end face. Further, it discloses a structure in which a low-conductivity region is provided on the end face side of the honeycomb structure, and the depth of the low-conductivity region is shallower than the depth of the slit.

In Patent Document 3, an electrode portion region in which electrode portion slits are formed and a honeycomb structure portion region in which honeycomb structure portion slits are formed have an outer periphery, and the depth of the electrode portion slits is the same as that of the honeycomb structure portion. A honeycomb structure having a structure greater than the depth of the slits is disclosed.

JP-A-9-103684 Japanese Patent No. 6339577 Japanese Patent No. 6126434

In the technique of providing slits in the end faces of the honeycomb structure described in Patent Documents 1 to 3, a mode is disclosed in which the thermal shock resistance is improved and the occurrence of cracks can be suppressed. However, as a result of investigation by the present inventors, it was found that the heat generation distribution due to energization was changed by providing the slits in the end faces of the honeycomb structure, thereby changing the resistance and the current path of the honeycomb structure. In terms of quality, there is room for improvement.

The present invention has been created in view of the above circumstances, and provides a honeycomb structure, an electrically heated carrier, and an exhaust gas purifying device that have good thermal shock resistance and exhibit uniform heat generation distribution when energized. The challenge is to

The above problems are solved by the present invention described below, and the present invention is specified as follows.
(1) A columnar honeycomb made of ceramics, having an outer peripheral wall and a partition wall disposed inside the outer peripheral wall and partitioning and forming a plurality of cells that penetrate from one end face to the other end face to form a flow path. a structure;
a pair of electrode layers provided on the outer surface of the outer peripheral wall with the central axis of the columnar honeycomb structure part interposed therebetween so as to extend in a band shape in the flow channel direction of the cells;
with
In a cross section perpendicular to the flow path direction of the cells of the columnar honeycomb structure, a linear slit that does not extend to the outer peripheral wall is provided in a region S shown below,
the absolute value θ of the inclination of the slit with respect to the center line P is 60 degrees or less,
(The center line P is the central axis of the columnar honeycomb structure portion extending from the midpoint of a line segment connecting both ends of one of the electrode layers in a cross section perpendicular to the flow channel direction of the cells of the columnar honeycomb structure portion. through to the other electrode layer.
The region S is defined by straight lines _Q1 and _Q2 , which are parallel to the center line P and separated from the center line P by a distance of 4/5 of the length from the center axis to the outer peripheral wall. , indicates a region defined by the straight lines Q ₁ , Q ₂ and the outer peripheral wall. )
A honeycomb structure, wherein the slit is provided at least on one end face of the columnar honeycomb structure.
(2) A columnar honeycomb made of ceramics, having an outer peripheral wall and partition walls disposed inside the outer peripheral wall and partitioning and forming a plurality of cells that penetrate from one end face to the other end face to form a flow path. a structure;
a pair of electrode layers provided on the outer surface of the outer peripheral wall with the central axis of the columnar honeycomb structure part interposed therebetween so as to extend in a band shape in the flow channel direction of the cells;
with
In a cross section perpendicular to the flow path direction of the cells of the columnar honeycomb structure body, a slit that is not branched and does not extend to the outer peripheral wall is provided in a region S shown below,
the absolute value θ of the inclination of the slit with respect to the center line P is 60 degrees or less,
(The center line P is the central axis of the columnar honeycomb structure portion extending from the midpoint of a line segment connecting both ends of one of the electrode layers in a cross section perpendicular to the flow channel direction of the cells of the columnar honeycomb structure portion. through to the other electrode layer.
The region S is defined by straight lines _Q1 and _Q2 , which are parallel to the center line P and separated from the center line P by a distance of 4/5 of the length from the center axis to the outer peripheral wall. , indicates a region defined by the straight lines Q ₁ , Q ₂ and the outer peripheral wall. )
A honeycomb structure, wherein the slit is provided at least on one end face of the columnar honeycomb structure.
(3) a honeycomb structure according to (1) or (2);
a metal electrode electrically connected to the electrode layer of the honeycomb structure;
An electrically heated carrier with a
(4) the electrically heated carrier according to (3);
a metallic cylindrical member for holding the electrically heated carrier;
An exhaust gas purification device having

ADVANTAGE OF THE INVENTION According to the present invention, it is possible to provide a honeycomb structure, an electrically heated carrier, and an exhaust gas purifying device that have good thermal shock resistance and exhibit uniform heat generation distribution when energized.

1 is a schematic external view of a honeycomb structure according to an embodiment of the present invention; FIG. FIG. 3 is a schematic cross-sectional view perpendicular to the extending direction of the cells of the honeycomb structure in the embodiment of the present invention. Fig. 3 is a schematic cross-sectional view for explaining "region S", "central axis O" and "central line P" of the honeycomb structure according to the embodiment of the present invention; FIG. 3 is a schematic cross-sectional view perpendicular to the extending direction of the cells of the honeycomb structure in the embodiment of the present invention. FIG. 3 is a schematic cross-sectional view perpendicular to the extending direction of the cells of the honeycomb structure in the embodiment of the present invention. 4A and 4B are cross-sectional schematic views perpendicular to the extending direction of the cells of the honeycomb structure according to the embodiment of the present invention. FIG. FIG. 3 is a schematic cross-sectional view perpendicular to the extending direction of the cells of the honeycomb structure in the embodiment of the present invention. 4A and 4B are cross-sectional schematic views perpendicular to the extending direction of the cells of the honeycomb structure according to the embodiment of the present invention. FIG. FIG. 3 is a schematic cross-sectional view perpendicular to the extending direction of the cells of the electrically heated carrier in the embodiment of the present invention. 4A and 4B are cross-sectional schematic views perpendicular to the extending direction of the cells of the honeycomb structure according to the embodiment of the present invention. FIG. FIG. 3 is a schematic cross-sectional view perpendicular to the extending direction of the cells of the honeycomb structure showing the arrangement of slits in Examples and Comparative Examples.

Embodiments for carrying out the present invention will now be described in detail with reference to the drawings. It is understood that the present invention is not limited to the following embodiments, and that design changes, improvements, etc., can be made as appropriate based on the ordinary knowledge of those skilled in the art without departing from the scope of the present invention. should.

(1. Honeycomb structure)
FIG. 1 is an external schematic diagram of a honeycomb structure 10 according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view perpendicular to the extending direction of the cells of the honeycomb structure 10 . The honeycomb structure 10 includes a columnar honeycomb structure portion 11 and electrode layers 13a and 13b.

(1-1. Columnar honeycomb structure part)
The columnar honeycomb structure portion 11 includes an outer peripheral wall 12 and partition walls 19 that are disposed inside the outer peripheral wall 12 and partition and form a plurality of cells 18 penetrating from one end face to the other end face to form flow paths. have.

The outer shape of the columnar honeycomb structure portion 11 is not particularly limited as long as it is columnar. , octagon, etc.). Further, the size of the columnar honeycomb structure portion 11 is preferably such that the area of the bottom surface is 2000 to 20000 mm ² for the reason of enhancing heat resistance (suppressing cracks entering the circumferential direction of the outer peripheral wall), and more preferably 5000 to 15000 mm. ² is more preferred.

The columnar honeycomb structure portion 11 is made of ceramics and has electrical conductivity. The electrical resistivity of the ceramics is not particularly limited as long as the conductive columnar honeycomb structure 11 is energized and can generate heat by Joule heat. more preferred. In the present invention, the electrical resistivity of the columnar honeycomb structure portion 11 is a value measured at 25° C. by a four-probe method.

The material of the columnar honeycomb structure 11 is not limited, but is selected from the group consisting of oxide ceramics such as alumina, mullite, zirconia and cordierite, and non-oxide ceramics such as silicon carbide, silicon nitride and aluminum nitride. can be selected. A silicon carbide-metal silicon composite material, a silicon carbide/graphite composite material, or the like can also be used. Among these, from the viewpoint of achieving both heat resistance and conductivity, the material of the columnar honeycomb structure 11 preferably contains a silicon-silicon carbide composite material or ceramics containing silicon carbide as a main component. When it is said that the material of the columnar honeycomb structure portion 11 is mainly composed of the silicon-silicon carbide composite material, the columnar honeycomb structure portion 11 is composed of the silicon-silicon carbide composite material (total mass) of 90 masses of the whole. % or more. Here, the silicon-silicon carbide composite material contains silicon carbide particles as an aggregate and silicon as a binder that binds the silicon carbide particles, and a plurality of silicon carbide particles are interposed between the silicon carbide particles. It is preferably bonded by silicon so as to form pores. When it is said that the material of the columnar honeycomb structure portion 11 contains silicon carbide as a main component, it means that the columnar honeycomb structure portion 11 contains 90% by mass or more of silicon carbide (total mass) of the whole. means.

When the columnar honeycomb structure portion 11 contains a silicon-silicon carbide composite material, the “mass of silicon carbide particles as an aggregate” contained in the columnar honeycomb structure portion 11 and the mass contained in the columnar honeycomb structure portion 11 The ratio of the "mass of silicon as a binder" contained in the columnar honeycomb structure portion 11 to the total "mass of silicon as a binder" is preferably 10 to 40% by mass, more preferably 15 to 35%. % by mass is more preferred.

Although the shape of the cells in the cross section perpendicular to the extending direction of the cells 18 is not limited, it is preferably square, hexagonal, octagonal, or a combination thereof. Among these, a quadrangle and a hexagon are preferable from the viewpoint that it is easy to achieve both structural strength and heating uniformity.

The thickness of the partition walls 19 defining the cells 18 is preferably 0.1 to 0.3 mm, more preferably 0.15 to 0.25 mm. In the present invention, the thickness of the partition wall 19 is defined as the length of the portion of the line segment connecting the centers of gravity of adjacent cells 18 passing through the partition wall 19 in a cross section perpendicular to the extending direction of the cells 18 .

The columnar honeycomb structure 11 preferably has a cell density of 40 to 150 cells/cm ² , more preferably 70 to 100 cells/cm ² in a cross section perpendicular to the direction of flow of the cells 18 . By setting the cell density within such a range, the purification performance of the catalyst can be enhanced while reducing the pressure loss when the exhaust gas flows. The cell density is a value obtained by dividing the number of cells by the area of one bottom portion of the columnar honeycomb structure portion 11 excluding the outer peripheral wall 12 portion.

Providing the outer peripheral wall 12 of the columnar honeycomb structure 11 is useful from the viewpoint of ensuring the structural strength of the columnar honeycomb structure 11 and suppressing leakage of the fluid flowing through the cells 18 from the outer peripheral wall 12 . Specifically, the thickness of the outer peripheral wall 12 is preferably 0.1 mm or more, more preferably 0.15 mm or more, and even more preferably 0.2 mm or more. However, if the outer peripheral wall 12 is too thick, the strength becomes too high, and the strength balance with the partition wall 19 is lost, resulting in a decrease in thermal shock resistance. Therefore, the thickness of the outer peripheral wall 12 is preferably 1.0 mm or less. , more preferably 0.7 mm or less, and even more preferably 0.5 mm or less. Here, the thickness of the outer peripheral wall 12 is measured in the direction normal to the tangential line of the outer peripheral wall 12 at the point of measurement when the portion of the outer peripheral wall 12 whose thickness is to be measured is observed in a cross section perpendicular to the extending direction of the cell. Defined as thickness.

The partition 19 may be porous. When porous, the partition wall 19 preferably has a porosity of 35 to 60%, more preferably 35 to 45%. The porosity is a value measured with a mercury porosimeter.

The average pore size of the partition walls 19 of the columnar honeycomb structure 11 is preferably 2 to 15 μm, more preferably 4 to 8 μm. The average pore diameter is a value measured with a mercury porosimeter.

(1-2. Electrode layer)
A pair of electrode layers 13 a and 13 b are provided on the outer surface of the outer peripheral wall 12 to sandwich the central axis of the columnar honeycomb structure portion 11 so as to extend in a strip shape in the direction of the flow path of the cells 18 . By providing the pair of electrode layers 13a and 13b in this way, the uniform heat generation property of the columnar honeycomb structure portion 11 can be enhanced. The electrode layers 13a and 13b extend over 80% or more of the length between both bottom surfaces of the columnar honeycomb structure portion 11, preferably over 90% or more of the length, and more preferably over the entire length. However, it is desirable from the viewpoint that the current is likely to spread in the axial direction of the electrode layers 13a and 13b.

The thickness of the electrode layers 13a and 13b is preferably 0.01 to 5 mm, more preferably 0.01 to 3 mm. Uniform heat build-up can be enhanced by setting it to such a range. The thickness of the electrode layers 13a and 13b is measured in the direction normal to the tangential line at the measurement point on the outer surface of the electrode layers 13a and 13b when the point where the thickness is to be measured is observed in a cross section perpendicular to the extending direction of the cell 18. Defined as thickness.

By making the electrical resistivity of the electrode layers 13a and 13b lower than the electrical resistivity of the columnar honeycomb structure portion 11, electricity preferentially flows through the electrode layers 13a and 13b, and electricity flows in the flow direction of the cells 18 when energized. And it becomes easy to spread in the circumferential direction. The electrical resistivity of the electrode layers 13a and 13b is preferably 1/10 or less, more preferably 1/20 or less, and 1/30 or less of the electrical resistivity of the columnar honeycomb structure portion 11. Even more preferred. However, if the difference between the electrical resistivities of the two becomes too large, the current will concentrate between the ends of the opposing electrode layers, and the heat generation of the columnar honeycomb structure 11 will be biased. is preferably 1/200 or more, more preferably 1/150 or more, and even more preferably 1/100 or more of the electrical resistivity of the columnar honeycomb structure portion 11 . In the present invention, the electrical resistivity of the electrode layers 13a and 13b is a value measured at 25° C. by a four-probe method.

Electrode layers 13a and 13b can be made of conductive ceramics, metal, or a composite material (cermet) of metal and conductive ceramics. Examples of metals include single metals such as Cr, Fe, Co, Ni, Si, and Ti, and alloys containing at least one metal selected from the group consisting of these metals. Conductive ceramics include, but are not limited to, silicon carbide (SiC) and include metal compounds such as metal silicides such as tantalum silicide (TaSi ₂ ) and chromium silicide (CrSi ₂ ). Specific examples of composites (cermets) of metals and conductive ceramics include composites of metal silicon and silicon carbide, composites of metal silicides such as tantalum silicide and chromium silicide, metal silicon and silicon carbide, and the above-mentioned From the viewpoint of thermal expansion reduction, one or more kinds of insulating ceramics such as alumina, mullite, zirconia, cordierite, silicon nitride and aluminum nitride are added to one or more kinds of metals. As the material of the electrode layers 13a and 13b, among the various metals and conductive ceramics described above, a combination of a metal silicide such as tantalum silicide or chromium silicide and a composite material of metal silicon and silicon carbide is preferable. It is preferable because it can be fired at the same time as the structural part 11, which contributes to simplification of the manufacturing process.

(1-3. Slit)
Linear slits 21a, 21b, and 21c that do not cross the outer peripheral wall 12 are provided in the region S in the cross section perpendicular to the flow path direction of the cells 18 of the columnar honeycomb structure portion 11 . By having such linear slits, cracks in the end faces of the honeycomb structure 10 can be suppressed. Specifically, when the car brakes suddenly, cold air suddenly hits the high-temperature honeycomb structure, and a difference in thermal expansion occurs in the direction of the flow path of the cells of the honeycomb structure. Cracks are likely to occur on the end face of the body. Therefore, it is considered that the provision of the linear slits alleviates the stress, leading to a reduction in the difference in thermal expansion. In addition, by providing the above-mentioned linear slits in the region S and setting the absolute value of the inclination of the slits with respect to the center line P to be within the range of 60 degrees or less, the electrical resistance does not increase even if the slits are provided. We believe that a uniform heat generation distribution can be obtained. In the present invention, the linear slits may be continuous slits 21a, 21b, and 21c as shown in FIGS. Like 22a, it is broken and divided here and there, but it may be linear as a whole.

In FIGS. 1 and 2, the slits 21a, 21b, and 21c indicate positions in the columnar honeycomb structure portion 11, and the shape is not particularly limited as long as it is elongated. For example, the slits 21a, 21b, and 21c may be slits 21a, 21b, and 21c formed by connecting adjacent cells by removing the partition walls 19 therebetween. The slits 21a, 21b, and 21c may be provided on one end surface of the columnar honeycomb structure portion 11, or may extend in the extending direction of the cells and have slits on both end surfaces. good.

FIG. 3 is a schematic cross-sectional view for explaining the "region S", the "center axis O" and the "center line P", and illustration of the cells 18, the partition walls 19, and the slits 21a, 21b, and 21c is omitted. ing. As shown in FIG. 3, the region S is a straight line parallel to the center line P and separated from the center line P by a distance of 4/5 of the length from the central axis O to the outer peripheral wall 12 as a straight line Q ₁ , A region defined by straight lines Q ₁ and Q ₂ and the outer peripheral wall 12 is Q ₂ (indicated by dotted lines in FIG. 3 ).

The center line P (indicated by a dotted line in FIG. 3) is the both end portions of one electrode layer 13a of the pair of electrode layers 13a and 13b in a cross section perpendicular to the flow path direction of the cells 18 of the columnar honeycomb structure portion 11. A straight line extending from the midpoint M of a line segment 27 (indicated by a dotted line in FIG. 3) passing through the central axis O of the columnar honeycomb structure portion 11 to the other electrode layer 13b of the pair of electrode layers 13a and 13b indicates

1 and 2 show an example in which three slits 21a, 21b, and 21c are provided in the region S in the cross section perpendicular to the flow path direction of the cells 18 of the columnar honeycomb structure portion 11. FIG. The slit 21a passes through the center line P, and the slits 21b and 21c are provided so as to extend parallel to the slit 21a.
Note that the linear slits provided in the honeycomb structure in the embodiment of the present invention do not include slits that are partially branched from linearly extending slits. That is, the linear slits provided in the honeycomb structure in the embodiment of the present invention are non-branched slits.

Since the honeycomb structure 10 according to the embodiment of the present invention is provided with the linear slits 21a, 21b, and 21c in the region S as described above, the thermal shock resistance is improved, and cracks are prevented. can be suppressed. In addition, the slits 21a, 21b, and 21c are controlled so that the absolute values of the inclinations of the slits 21a, 21b, and 21c with respect to the center line P are controlled within a range of 60 degrees or less (0 degrees or more and 60 degrees or less). Changes in the resistance and current paths of the structure 10 can be suppressed, and changes in heat generation distribution due to energization can be suppressed. The absolute value of the inclination of the slits 21a, 21b, and 21c with respect to the center line P is preferably 45 degrees or less, and is 30 degrees or less, from the viewpoint of further suppressing changes in resistance and current paths of the honeycomb structure 10. is more preferred.

The absolute values of the inclinations of the slits 21a, 21b, and 21c with respect to the center line P will be described with reference to FIGS. The slit 21a shown in FIG. 10A is inclined counterclockwise with respect to the center line P by θ degrees. The slit 21a shown in FIG. 10B is inclined clockwise with respect to the center line P by θ degrees. In the present invention, both the counterclockwise tilt angle and the clockwise tilt angle with respect to the center line P are the absolute values of the tilts of the slits 21a, 21b, and 21c with respect to the center line P ( θ).

In the honeycomb structure 10 according to the embodiment of the present invention, it is preferable to provide the end faces having the slits 21a, 21b, and 21c on the upstream side of the exhaust gas flow. According to such a configuration, the slits 21a, 21b, and 21c are formed in the end faces through which the higher-temperature exhaust gas passes, so that the thermal shock can be satisfactorily mitigated, and cracks can be prevented more favorably. can be suppressed.

The ratio of the length of the slits 21a, 21b, 21c to the outer diameter of the columnar honeycomb structure portion 11 is preferably 25 to 99%. When the ratio of the length of the slits 21a, 21b, and 21c to the outer diameter of the columnar honeycomb structure portion 11 is 25% or more, the thermal shock can be better alleviated, and the occurrence of cracks can be better suppressed. can be done.

It is preferable that the depth of the slits 21a, 21b, and 21c in the flow path direction of the cells 18 from one end surface of the honeycomb structure 10 is 30% or more of the total length of the columnar honeycomb structure 11. When the depth of the slits 21a, 21b, and 21c is 30% or more of the total length of the columnar honeycomb structure portion 11, the thermal shock resistance is further improved. The depth of the slits 21a, 21b, and 21c is more preferably 30 to 100%, even more preferably 50 to 100%, even more preferably 70 to 100% of the total length of the columnar honeycomb structure portion 11. is even more preferred.

The slits 21 a , 21 b , 21 c may be formed so as to include the cells 18 or may be formed only in the partition walls 19 . When the slits 21a, 21b, and 21c are formed so as to include the cells 18, a slit having a structure in which a plurality of cells 18 are connected can be formed simply by removing the partition walls 19 between the adjacent cells 18. , the manufacturing efficiency is good.

The number of slits is not particularly limited, and as shown in FIGS. 1 and 2, a plurality of slits 21a, 21b, and 21c are provided independently of each other in a cross section perpendicular to the flow path direction of the cells 18 of the columnar honeycomb structure body 11. Alternatively, as shown in FIG. 4, only one slit 21a may be formed. The slits 21a shown in FIG. 4 indicate positions in a cross section perpendicular to the flow path direction of the cells 18 of the columnar honeycomb structure body 11, and the shape of the slits 21a is not particularly limited. This is the same for each slit shown in FIGS. 5 to 10, which will be described later.

Two or four or more slits may be formed independently. Since a plurality of slits are formed independently, the occurrence of cracks in the honeycomb structure 10 can be well controlled. Moreover, the width of the slit is not particularly limited. For example, when a slit is formed by removing the partition wall 19 between adjacent cells and connecting them, the width of the slit is formed to be approximately the same as the width of the cell 18 . Alternatively, the width of the slits may be formed smaller or larger than the width of the cells 18 . The width of each slit is not particularly limited, but may be 1 to 10 mm. The width of each slit can be appropriately adjusted depending on the size, material, application of the honeycomb structure 10, the number and length of the slits, and the like.

In the examples shown in FIGS. 1, 2 and 4, the slit 21a passes through the central axis O of the columnar honeycomb structure 11 in the cross section perpendicular to the flow path direction of the cells 18 of the columnar honeycomb structure 11. However, as shown in FIG. 5, it may be composed only of slits 21b and 21c that do not pass through the central axis O.

In the embodiment of the present invention, it is preferable that the slits pass through the central portion of the columnar honeycomb structure 11 in the cross section perpendicular to the flow path direction of the cells 18 of the columnar honeycomb structure 11 . The central portion is a region of ⅓ of the distance from the central axis O of the columnar honeycomb structure portion 11 to the outer peripheral wall 12 . According to such a configuration, it is possible to more satisfactorily suppress changes in the resistance of the honeycomb structure 10 and current paths. The central portion is more preferably a region of 1/4, more preferably 1/5 of the distance from the central axis O of the columnar honeycomb structure portion 11 to the outer peripheral wall 12 .

As shown in FIGS. 6A and 6B, linear slits 22a may be divided along the direction in which the slits 22a extend. In FIG. 6(A), it is divided into slits of approximately the same length, and in FIG. 6(B), it is divided into slits of different lengths. By dividing the slits, the occurrence of cracks in the honeycomb structure 10 can be well controlled. The number of divisions of the slit 22a is not particularly limited, and may be divided into two, three, or four or more. Also, a plurality of slits may be provided by mixing slits formed by division and slits that are not divided.

As shown in FIG. 7, the columnar honeycomb structure portion 11 further has peripheral slits 23a to 23h extending in the flow path direction of the cells 18 in the peripheral wall 12, and the slit 21a and the peripheral slits 23a to 23h are independent. May be present. By forming the outer peripheral slits 23a to 23h in addition to the slit 21a, the thermal shock resistance is further improved. In FIG. 7, the peripheral slits 23a and 23e are formed on the extension line of the center line P. As shown in FIG. Further, in the cross section perpendicular to the flow path direction of the cells 18 of the columnar honeycomb structure portion 11, assuming that the outer peripheral slits 23a and 23e are formed in the outer peripheral wall 12 in directions of 0 degrees and 180 degrees from the central axis O, respectively, The outer peripheral slits 23c and 23g are formed in the outer peripheral wall 12 in directions of 90 degrees and 270 degrees from the central axis O, respectively. It is formed on the outer peripheral wall 12 in directions of 120 degrees, 240 degrees, and 300 degrees. In addition, the outer peripheral slits 23a and 23e both extend to the electrode layers 13a and 13b, thereby dividing the electrode layers 13a and 13b, respectively. Moreover, even if the slit is divided, a peripheral slit may be similarly provided. As such a honeycomb structure, in FIGS. 8A and 8B, in the honeycomb structure formed with the divided slits 22a shown in FIGS. A configuration in which slits 23a to 23h are provided is shown.

The width of the peripheral slits 23a to 23h is not particularly limited, but may be 1 to 10 mm. The width of the peripheral slits 23a to 23h can be appropriately adjusted depending on the size, material, application of the honeycomb structure 10, and the number and length of the peripheral slits 23a to 23h.

In the honeycomb structure 10 according to the embodiment of the present invention, fillers may be provided in at least part of the spaces within the slits 21a, 21b, 21c, and 22a. Thus, the isostatic strength of the honeycomb structure 10 is improved by providing the filler in at least part of the spaces within the slits 21a, 21b, 21c, and 22a. When "at least part" is filled, "part" in the depth direction of the slits 21a, 21b, 21c, and 22a may be filled, and "part" in the length direction of the slits 21a, 21b, 21c, and 22a may be filled. , or a combination thereof. Also, the filling material may be provided in all the spaces within the slits 21a, 21b, 21c, and 22a.

When the main component of the columnar honeycomb structure portion 11 is silicon carbide or a silicon carbide-metallic silicon composite, the filler preferably contains 20% by mass or more of silicon carbide, and may contain 20 to 50% by mass. More preferred. Thereby, the thermal expansion coefficient of the filler can be made close to the thermal expansion coefficient of the columnar honeycomb structure body 11, and the thermal shock resistance of the honeycomb structure 10 can be improved. The filler may contain 50% by mass or more of silica, alumina, or the like.

In the honeycomb structure 10 according to the embodiment of the present invention, the Young's modulus of the filler is preferably 0.001 to 20 GPa, more preferably 0.005 to 15 GPa, and 0.01 to 10 GPa. is particularly preferred. When the Young's modulus of the filler is 0.001 GPa or more, the honeycomb structure 10 has good mechanical strength. When the Young's modulus of the filler is 20 GPa or less, the honeycomb structure 10 has good thermal shock resistance.

In the honeycomb structure 10 according to the embodiment of the present invention, the electrical resistivity of the filler is preferably 100 to 100000% of the electrical resistivity of the columnar honeycomb structure body 11 . Moreover, the electrical resistivity of the filler is more preferably 200 to 100,000% of the electrical resistivity of the columnar honeycomb structure portion 11, and particularly preferably 300 to 100,000%. When the electrical resistivity of the filler is 100% or more of the electrical resistivity of the columnar honeycomb structure 11, it is difficult for the current to flow through the filler, so that it is easy to uniformly pass the current through the columnar honeycomb structure 11. Become. There is no particular problem even if the electrical resistivity of the filler is high. The filler may be an insulator. The upper limit of the electrical resistivity of the filler is actually about 100000% of the electrical resistivity of the columnar honeycomb structure portion 11 . As the filler, a plurality of fillers may be used together. For example, it is possible to use different parts in one slit or use different slits.

(2. Electrically heated carrier)
FIG. 9 is a schematic cross-sectional view perpendicular to the extending direction of the cells of the electrically heated carrier 30 in the embodiment of the present invention. The electrically heated carrier 30 includes a honeycomb structure 10 and metal electrodes 33 a and 33 b electrically connected to the electrode layers 13 a and 13 b of the honeycomb structure 10 .

(2-1. Metal electrode)
The metal electrodes 33 a and 33 b are provided on the electrode layers 13 a and 13 b of the honeycomb structure 10 . The metal electrodes 33a and 33b may be a pair of metal electrodes arranged such that one metal electrode 33a faces the other metal electrode 33b across the central axis of the columnar honeycomb structure portion 11. good. When a voltage is applied through the electrode layers 13a and 13b, the metal electrodes 33a and 33b can be energized to cause the columnar honeycomb structure 11 to generate heat by Joule heat. Therefore, the electrically heated carrier 30 can also be suitably used as a heater. The applied voltage is preferably 12 to 900 V, more preferably 64 to 600 V, but the applied voltage can be changed as appropriate.

The material of the metal electrodes 33a and 33b is not particularly limited as long as it is metal, and single metals and alloys can be used. , Co, Ni and Ti, and more preferably stainless steel and Fe--Ni alloy. The shape and size of the metal electrodes 33a and 33b are not particularly limited, and can be appropriately designed according to the size of the electrically heated carrier 30, the current-carrying performance, and the like.

By supporting a catalyst on the electrically heated carrier 30, the electrically heated carrier 30 can be used as a catalyst body. Fluid such as automobile exhaust gas can flow through the channels of the plurality of cells 18 of the honeycomb structure 10 . Examples of catalysts include noble metal-based catalysts and other catalysts. As noble metal catalysts, noble metals such as platinum (Pt), palladium (Pd), and rhodium (Rh) are supported on the surface of alumina pores, and three-way catalysts and oxidation catalysts containing co-catalysts such as ceria and zirconia, or alkali An NO _x storage reduction catalyst (LNT catalyst) containing an earth metal and platinum as a nitrogen oxide (NO _x ) storage component is exemplified. Examples of catalysts that do not use precious metals include NO _x selective reduction catalysts (SCR catalysts) containing copper-substituted or iron-substituted zeolites. Also, two or more catalysts selected from the group consisting of these catalysts may be used. The catalyst loading method is also not particularly limited, and can be carried out according to a conventional loading method for loading a catalyst on a honeycomb structure.

(3. Manufacturing method of honeycomb structure)
Next, a method for manufacturing the honeycomb structure 10 according to the embodiment of the present invention will be exemplified. In one embodiment, the method for manufacturing the honeycomb structure 10 according to the embodiment of the present invention includes a step A1 of obtaining an unfired honeycomb structure body with the electrode layer forming paste, and firing the unfired honeycomb structure body with the electrode layer forming paste. and Step A2 of obtaining a honeycomb structure.

Step A1 is a step of obtaining an unfired honeycomb structure with electrode layer forming paste.
First, a columnar honeycomb structure made of ceramics, having an outer peripheral wall and a partition wall disposed inside the outer peripheral wall and partitioning a plurality of cells forming a flow path penetrating from one end face to the other end face. prepare.
Next, linear slits are formed by removing the partition walls from the end faces of the columnar honeycomb structure so as to form linear slits. The linear slits can also be formed by removing the partition walls by processing after firing the honeycomb structure.
Next, an electrode layer forming paste is applied to a predetermined region of the unfired honeycomb structure. As a result, an unfired honeycomb structure with the electrode layer forming paste is obtained.

For the production of the columnar honeycomb structure in step A1, first, silicon carbide powder (silicon carbide) is added with metal silicon powder (metal silicon), a binder, a surfactant, a pore-forming material, water, and the like to obtain a forming raw material. make. It is preferable that the mass of the metal silicon powder is 10 to 40% by mass with respect to the sum of the mass of the silicon carbide powder and the mass of the metal silicon powder. The average particle size of silicon carbide particles in the silicon carbide powder is preferably 3 to 50 μm, more preferably 3 to 40 μm. The average particle size of the metallic silicon particles in the metallic silicon (metallic silicon powder) is preferably 2 to 35 μm. The average particle size of silicon carbide particles and metallic silicon (metallic silicon particles) refers to the volume-based arithmetic mean diameter when the frequency distribution of particle sizes is measured by a laser diffraction method. The silicon carbide particles are fine particles of silicon carbide that constitute the silicon carbide powder, and the metallic silicon particles are fine particles of metallic silicon that constitute the metallic silicon powder. Note that this is the composition of the forming raw materials when the material of the columnar honeycomb structure portion in step A1 is a silicon-silicon carbide composite material, and when the material is silicon carbide, metallic silicon is not added. .

Binders include methylcellulose, hydroxypropylmethylcellulose, hydroxypropoxylcellulose, hydroxyethylcellulose, carboxymethylcellulose, polyvinyl alcohol and the like. Among these, it is preferable to use methyl cellulose and hydroxypropoxyl cellulose together. The content of the binder is preferably 2.0 to 10.0 parts by mass when the total mass of the silicon carbide powder and the metal silicon powder is 100 parts by mass.

The content of water is preferably 20 to 60 parts by mass when the total mass of the silicon carbide powder and the metal silicon powder is 100 parts by mass.

Ethylene glycol, dextrin, fatty acid soap, polyalcohol and the like can be used as surfactants. These may be used individually by 1 type, and may be used in combination of 2 or more type. The content of the surfactant is preferably 0.1 to 2.0 parts by mass when the total mass of the silicon carbide powder and the metal silicon powder is 100 parts by mass.

The pore-forming material is not particularly limited as long as it forms pores after baking, and examples thereof include graphite, starch, foamed resin, water-absorbing resin, silica gel, and the like. The content of the pore-forming material is preferably 0.5 to 10.0 parts by mass when the total mass of the silicon carbide powder and the metal silicon powder is 100 parts by mass. The average particle size of the pore-forming material is preferably 10-30 μm. The average particle diameter of the pore-forming material refers to the volume-based arithmetic mean diameter when the frequency distribution of particle sizes is measured by a laser diffraction method. When the pore-forming material is a water absorbent resin, the average particle size of the pore-forming material means the average particle size after water absorption.

Next, after kneading the obtained forming raw material to form a clay, the clay is formed (for example, extrusion-molded) to produce a formed honeycomb body. For extrusion molding, a die having a desired overall shape, cell shape, partition wall thickness, cell density, etc. can be used. Next, it is preferable to dry the obtained honeycomb molded body. When the length of the honeycomb formed body in the central axis direction is not the desired length, the desired length can be obtained by cutting both bottom portions of the honeycomb formed body. The dried honeycomb molded body is called a honeycomb dried body.

Preparation of the electrode layer forming paste for forming the electrode layer in step A1 will be described. The electrode layer forming paste can be formed by appropriately adding various additives to raw material powder (metal powder and/or ceramic powder, etc.) blended according to the required properties of the electrode layer and kneading the mixture. When the electrode layer has a laminated structure, the average particle size of the metal powder in the paste for the second electrode layer is made larger than the average particle size of the metal powder in the paste for the first electrode layer. , the bonding strength between the metal terminal and the electrode layer tends to improve. The average particle size of metal powder refers to the volume-based arithmetic mean size when the frequency distribution of particle sizes is measured by a laser diffraction method.

The method of preparing the electrode layer forming paste and the method of applying the electrode layer forming paste to the formed honeycomb body can be carried out according to a known method for manufacturing a honeycomb structure. In order to make the electrical resistivity lower than that of the honeycomb structure portion, the metal content ratio can be increased or the particle size of the metal particles can be made smaller than that of the honeycomb structure portion.

As a modified example of the method for manufacturing a columnar honeycomb structure, in step A1, the formed honeycomb body may be once fired before applying the electrode layer forming paste. That is, in this modified example, a honeycomb formed body is fired to produce a honeycomb fired body, and the electrode layer forming paste is applied to the honeycomb fired body.

In step A2, the honeycomb structure 10 is obtained by firing the unfired honeycomb structure body with the electrode layer forming paste. Before firing, the unfired honeycomb structure body with the electrode layer forming paste may be dried. Moreover, before firing, degreasing may be performed to remove binders and the like. As the firing conditions, it is preferable to heat at 1400 to 1500° C. for 1 to 20 hours in an inert atmosphere such as nitrogen or argon. After firing, it is preferable to perform oxidation treatment at 1200 to 1350° C. for 1 to 10 hours in order to improve durability. The method of degreasing and firing is not particularly limited, and firing can be performed using an electric furnace, a gas furnace, or the like.

(4. Method for producing electrically heated carrier)
In one embodiment of the method for manufacturing the electrically heated carrier 30 according to the embodiment of the present invention, a metal electrode is fixed on the electrode layer of the honeycomb structure 10 . Examples of fixing methods include conventionally known methods such as laser welding, thermal spraying, and ultrasonic welding. More specifically, a pair of metal electrodes are provided on the outer surface of the electrode layer with the central axis of the columnar honeycomb structure portion of the honeycomb structure 10 interposed therebetween. Thus, an electrically heated carrier 30 according to an embodiment of the present invention is obtained.

(5. Exhaust gas purification device)
The electrically heated carrier 30 according to the embodiment of the present invention described above can be used in an exhaust gas purifier. The exhaust gas purifier has an electrically heated carrier 30 and a metallic tubular member that holds the electrically heated carrier 30 . In the exhaust gas purifier, the electrically heated carrier 30 is installed in the middle of the exhaust gas flow path through which the exhaust gas from the engine flows. In the exhaust gas purification device, it is preferable that one end surface of the columnar honeycomb structure portion 11 is provided on the upstream side of the exhaust gas flow. According to such a configuration, the slits 21a, 21b, and 21c of the honeycomb structure 10 are formed in the end faces through which the higher-temperature exhaust gas passes, so that the thermal shock can be favorably alleviated, and cracks can occur. The occurrence can be better suppressed.

The following examples are provided for a better understanding of the invention and its advantages, but are not intended to limit the invention.

<Example 1>
(1. Preparation of Clay)
A ceramic raw material was prepared by mixing silicon carbide (SiC) powder and metal silicon (Si) powder at a mass ratio of 80:20. Then, hydroxypropylmethyl cellulose as a binder, a water-absorbing resin as a pore-forming material, and water were added to the ceramic raw material to obtain a molding raw material. Then, the forming raw material was kneaded by a vacuum kneader to prepare a cylindrical kneaded material. The binder content was 7 parts by mass when the total of silicon carbide (SiC) powder and metal silicon (Si) powder was 100 parts by mass. The content of the pore-forming material was 3 parts by mass when the total of silicon carbide (SiC) powder and metal silicon (Si) powder was 100 parts by mass. The content of water was 42 parts by mass when the total of silicon carbide (SiC) powder and metal silicon (Si) powder was 100 parts by mass. The silicon carbide powder had an average particle size of 20 μm, and the metallic silicon powder had an average particle size of 6 μm. Also, the average particle size of the pore-forming material was 20 μm. The average particle size of the silicon carbide powder, metallic silicon powder and pore-forming material refers to the volume-based arithmetic mean size when the frequency distribution of particle sizes is measured by a laser diffraction method.

(2. Preparation of dried honeycomb body)
The obtained cylindrical clay was molded using an extruder having a die structure to obtain a cylindrical honeycomb molded body in which each cell had a hexagonal shape in a cross section perpendicular to the flow direction of the cells. After the honeycomb molded body was dried by high-frequency dielectric heating, it was dried at 120° C. for 2 hours using a hot air dryer to prepare a dried honeycomb body.
Next, linear slits were formed by removing the partition walls from the end faces of the dried honeycomb body so as to form linear slits.

(3. Preparation of electrode layer forming paste)
Metallic silicon (Si) powder, silicon carbide (SiC) powder, methyl cellulose, glycerin, and water were mixed with a rotation-revolution stirrer to prepare an electrode layer forming paste. The Si powder and the SiC powder were blended in a volume ratio of Si powder:SiC powder=40:60. Further, when the total of Si powder and SiC powder was 100 parts by mass, methyl cellulose was 0.5 parts by mass, glycerin was 10 parts by mass, and water was 38 parts by mass. The average particle size of the metallic silicon powder was 6 μm. The silicon carbide powder had an average particle size of 35 μm. These average particle diameters refer to volume-based arithmetic mean diameters when the frequency distribution of particle sizes is measured by a laser diffraction method.

(4. Application and firing of electrode layer forming paste)
Next, this electrode layer forming paste was applied to the dried honeycomb body with a suitable area and film thickness using a curved surface printer, and dried at 120° C. for 30 minutes with a hot air dryer.
Next, the "dried honeycomb body with electrode layer forming paste and slits" was filled with the raw material for filler using a spatula to obtain the "dried honeycomb body with raw material for filler". After that, the “dried honeycomb body with raw material for filler” was dried at 70°C. After that, the dried honeycomb body was fired in an Ar atmosphere at 1400° C. for 3 hours to obtain a columnar honeycomb structure. The raw material for the filler had the same composition as the raw material for forming the electrode portion.

The columnar honeycomb structure had a circular bottom surface with an outer diameter (diameter) of 100 mm, a height (length in the flow direction of the cells) of 100 mm, and an outer peripheral wall thickness of 0.5 mm. The cell density was 93 cells/cm ² , the partition wall thickness was 101.6 μm, the partition wall porosity was 45%, and the partition wall average pore diameter was 8.6 μm. The thickness of the electrode layer was 0.3 mm.

The slits formed in Example 1 were linearly provided in the above-described region S without extending over the outer peripheral wall in the cross section perpendicular to the flow path direction of the cells of the columnar honeycomb structure.
The width of the slit in Example 1 was 1 mm, the length was 99 mm, and the ratio of the length of the slit to the outer diameter (diameter) of the columnar honeycomb structure was 99%.
The absolute value of the inclination of the slit with respect to the center line P of Example 1 was 0 degree.
In addition, the ratio of the depth of the slits in the flow path direction of the cells from one end surface of the columnar honeycomb structure was set to 100%.

<Example 2>
A sample was prepared in the same manner as in Example 1, except that the width of the slit was 3 mm.

<Example 3>
A sample was prepared in the same manner as in Example 1, except that the ratio of the slit length to the outer diameter of the columnar honeycomb structure was 80%.

<Example 4>
A sample was prepared in the same manner as in Example 1, except that the ratio of the slit length to the outer diameter of the columnar honeycomb structure was 60%.

<Example 5>
Except that the ratio of the length of the slits to the outer diameter of the columnar honeycomb structure was set to 80%, and the ratio of the depth of the slits in the flow direction of the cells from one end surface of the columnar honeycomb structure was set to 60%. A sample was prepared in the same manner as in Example 1.

<Example 6>
A sample was prepared in the same manner as in Example 1, except that the ratio of the length of the slits to the outer diameter of the columnar honeycomb structure was 80% and the absolute value of the inclination of the slits with respect to the center line P was 30 degrees.

<Example 7>
A sample was prepared in the same manner as in Example 1, except that the ratio of the length of the slits to the outer diameter of the columnar honeycomb structure was set to 80%, and the absolute value of the inclination of the slits with respect to the center line P was set to 60 degrees.

<Example 8>
A sample was produced in the same manner as in Example 1, except that the slits were formed in a linear shape partially interrupted like perforations at substantially equal intervals.

<Example 9>
A sample was prepared in the same manner as in Example 1, except that the slits were continuous in the central part of the columnar honeycomb structure and were partially discontinuous like perforations near the periphery.

<Example 10>
A sample was prepared in the same manner as in Example 3, except that one slit was provided on both sides of the slit in parallel with the slit of Example 3 and spaced apart at regular intervals. For each slit (“outside” in Table 1) provided at equal intervals parallel to the slit (“center” in Table 1), the ratio of the length of the slit to the outer diameter of the columnar honeycomb structure was set to 60%.

<Comparative Example 1>
A sample was prepared in the same manner as in Example 1, except that no slit was provided.

<Comparative Example 2>
A sample was produced in the same manner as in Example 3, except that the absolute value of the slope of the slit with respect to the center line P was set to 90 degrees.

FIG. 11 shows a schematic cross-sectional view perpendicular to the extending direction of the cells of the honeycomb structure showing the arrangement of slits in Examples 1 to 10 and Comparative Examples 1 and 2. As shown in FIG. The slits of Examples 1 to 10 are all formed within the region S described above. Further, Table 1 shows configurations of the honeycomb structure portion and the slits in Examples 1 to 10 and Comparative Examples 1 and 2.

(5. Current resistance)
For each of the samples of Examples 1 to 10 and Comparative Examples 1 and 2, a silver paste was applied to the outer peripheral surface, and wiring was made so that electricity could be supplied. Next, a voltage applied current measuring device was connected to the sample. Next, a thermocouple was placed in the center of the sample, a voltage was applied, and changes in the temperature of the test piece over time during voltage application were confirmed with a recorder. Specifically, a voltage of 100 to 200 V was applied, the current value and voltage value were measured at a sample temperature of 400° C., and the current resistance (Ω) was calculated from the obtained current value and voltage value.

(6. Conducting performance)
A voltage of 200 V was applied to each of the samples of Examples 1 to 10 and Comparative Examples 1 and 2 to conduct a current test. Then, the maximum temperature of the sample at that time was measured. In this test, the higher the maximum temperature, the more uneven the heat generation, and the more likely cracks were to occur when the current was applied.

(7. Thermal shock resistance test)
A sample heating and cooling test was performed using a propane gas burner tester equipped with a metal case for housing a sample and a propane gas burner capable of supplying heating gas into the metal case. The heating gas was combustion gas generated by burning propane gas with a gas burner (propane gas burner). Then, the thermal shock resistance was evaluated by confirming whether or not cracks were generated in the sample by the above heating and cooling test. Specifically, first, the obtained sample was housed (canned) in a metal case of a propane gas burner tester. Gas (combustion gas) heated by a propane gas burner was supplied into the metal case and passed through the honeycomb structure. The temperature condition of the heating gas flowing into the metal case (inlet gas temperature condition) was set as follows. First, the temperature was raised to the specified temperature in 5 minutes, held at the specified temperature for 10 minutes, cooled to 100° C. in 5 minutes, and held at 100° C. for 10 minutes. A series of operations such as heating, cooling, and holding are referred to as "heating and cooling operations". After that, the sample was checked for cracks. Then, while increasing the specified temperature from 825° C. by 25° C., the above “heating and cooling operations” were repeated. The specified temperature was set in 14 steps, starting from 825°C and 25°C each. In other words, the above "heating and cooling operations" were performed until the specified temperature reached 1150°C. As the designated temperature increases, the temperature rise steepness increases, and the temperature rise in the outer peripheral portion is delayed relative to that in the central portion. In Table 1, the column of "Thermal shock resistance test" indicates the specified temperature at which cracks occurred in the honeycomb structure in the thermal shock resistance test.
Table 1 shows test conditions and evaluation results.

(8. Consideration)
In each of the samples of Examples 1 to 10, a non-branching slit was provided in the above-described region S in the cross section of the columnar honeycomb structure without extending to the outer peripheral wall, and the inclination of the slit with respect to the center line P was 60 degrees or less. For this reason, all of them had good current-carrying performance and good thermal shock resistance.
Comparative Example 1 did not have slits and had poor thermal shock resistance.
In Comparative Example 2, the absolute value θ of the inclination of the slit with respect to the center line P was 90 degrees, and the electrical conduction performance was poor.

10 Honeycomb structure 11 Columnar honeycomb structure portion 12 Peripheral walls 13a, 13b Electrode layer 18 Cells 19 Partition walls 21a, 21b, 21c Slits 22a Slits 23a, 23b, 23c, 23d, 23e, 23f, 23g, 23h Peripheral slits 30 Electric heating type Carriers 33a, 33b Metal electrodes

Claims (15)

a columnar honeycomb structure made of ceramics, comprising: an outer peripheral wall; and a partition wall disposed inside the outer peripheral wall and partitioning a plurality of cells forming a flow path penetrating from one end face to the other end face. ,
a pair of electrode layers provided on the outer surface of the outer peripheral wall with the central axis of the columnar honeycomb structure part interposed therebetween so as to extend in a band shape in the flow channel direction of the cells;
with
In a cross section perpendicular to the flow path direction of the cells of the columnar honeycomb structure, a linear slit that does not extend to the outer peripheral wall is provided in a region S shown below,
the absolute value θ of the inclination of the slit with respect to the center line P is 60 degrees or less,
(The center line P is the central axis of the columnar honeycomb structure portion extending from the midpoint of a line segment connecting both ends of one electrode layer in a cross section perpendicular to the flow path direction of the cells of the columnar honeycomb structure portion. through to the other electrode layer.
The region S is defined by straight lines _Q1 and _Q2 , which are parallel to the center line P and separated from the center line P by a distance of 4/5 of the length from the center axis to the outer peripheral wall. , indicates a region defined by the straight lines Q ₁ , Q ₂ and the outer peripheral wall. )
A honeycomb structure, wherein the slit is provided in at least one end face of the columnar honeycomb structure. a columnar honeycomb structure made of ceramics, comprising: an outer peripheral wall; and a partition wall disposed inside the outer peripheral wall and partitioning a plurality of cells forming a flow path penetrating from one end face to the other end face. ,
a pair of electrode layers provided on the outer surface of the outer peripheral wall with the central axis of the columnar honeycomb structure part interposed therebetween so as to extend in a band shape in the flow channel direction of the cells;
with
In a cross section perpendicular to the flow path direction of the cells of the columnar honeycomb structure body, a slit that is not branched and does not extend to the outer peripheral wall is provided in a region S shown below,
the absolute value θ of the inclination of the slit with respect to the center line P is 60 degrees or less,
(The center line P is the central axis of the columnar honeycomb structure portion extending from the midpoint of a line segment connecting both ends of one of the electrode layers in a cross section perpendicular to the flow channel direction of the cells of the columnar honeycomb structure portion. through to the other electrode layer.
The region S is defined by straight lines _Q1 and _Q2 , which are parallel to the center line P and separated from the center line P by a distance of 4/5 of the length from the center axis to the outer peripheral wall. , indicates a region defined by the straight lines Q ₁ , Q ₂ and the outer peripheral wall. )
A honeycomb structure, wherein the slit is provided at least on one end face of the columnar honeycomb structure. The honeycomb structure according to claim 1 or 2, wherein the slits are divided along the direction in which the slits extend. The honeycomb structure according to any one of claims 1 to 3, wherein the depth of the slit from the one end face in the direction of flow path of the cells is 30% or more of the total length of the columnar honeycomb structure. . The honeycomb structure according to any one of claims 1 to 4, wherein the slits contain the cells. The honeycomb structure according to any one of claims 1 to 5, wherein a plurality of slits are provided independently of each other in a cross section perpendicular to the flow channel direction of the cells of the columnar honeycomb structure body. The honeycomb structure according to any one of claims 1 to 6, wherein the slit passes through the central portion of the columnar honeycomb structure in a cross section perpendicular to the flow path direction of the cells of the columnar honeycomb structure.
(The central portion is a region of 1/3 of the distance from the central axis of the columnar honeycomb structure portion to the outer peripheral wall.) The columnar honeycomb structure further has an outer peripheral slit extending in the flow direction of the cells in the outer peripheral wall,
The honeycomb structure according to any one of claims 1 to 7, wherein the slit and the peripheral slit exist independently. The honeycomb structure according to any one of claims 1 to 8, wherein a filling material is provided in at least part of the spaces within the slits. The honeycomb structure according to claim 9, wherein the filling material fills the entire space within the slit. The honeycomb structure according to claim 9 or 10, wherein the electrical resistivity of the filler is 100 to 100000% of the electrical resistivity of the columnar honeycomb structural body. The honeycomb structure according to any one of claims 1 to 11, wherein the one end face of the columnar honeycomb structure body is on the upstream side of the exhaust gas flow. a honeycomb structure according to any one of claims 1 to 12;
a metal electrode electrically connected to the electrode layer of the honeycomb structure;
An electrically heated carrier with a An electrically heated carrier according to claim 13;
a metallic cylindrical member for holding the electrically heated carrier;
An exhaust gas purification device having 15. The exhaust gas purifying device according to claim 14, wherein said one end surface of said columnar honeycomb structure is on the upstream side of the exhaust gas flow.

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