WO2021176785A1

WO2021176785A1 - Electric heating-type carrier, exhaust gas purification device, and metal electrode

Info

Publication number: WO2021176785A1
Application number: PCT/JP2020/044882
Authority: WO
Inventors: 傑士高田; 尚哉高瀬
Original assignee: 日本碍子株式会社
Priority date: 2020-03-06
Filing date: 2020-12-02
Publication date: 2021-09-10
Also published as: JPWO2021176785A1

Abstract

This electric heating-type carrier comprises: an outer peripheral wall; a columnar honeycomb structure made of ceramics, which is disposed inside the outer peripheral wall and has a partition wall partitioning a plurality of cells that form a flow path passing therethrough from one end surface to the other end surface thereof; an electrode layer disposed on the surface of the outer peripheral surface of the columnar honeycomb structure; and a metal electrode disposed on the electrode layer. The metal electrode includes a body part and a plurality of tongue pieces extending from the body part. The tongue pieces of the metal electrode each have a neck portion and a head portion. The head portion of the tongue piece is disposed so that at least a portion thereof is in contact with the electrode layer. A length A from a terminal of the neck portion, which is a starting point extending from the body part of the tongue piece, to a tip of the neck portion and a minimum width B of the width of the neck portion satisfy the relationship 10<A/B≦160.

Description

Electric heating type carrier, exhaust gas purification device and metal electrode

The present invention relates to an electrically heated carrier, an exhaust gas purifying device, and a metal electrode. In particular, the present invention relates to an electrically heated carrier, an exhaust gas purifying device, and a metal electrode in which the generation of cracks due to a difference in thermal expansion during heating is satisfactorily suppressed.

_{Conventionally, for purification treatment of harmful substances such as HC, CO, NO x} contained in the exhaust gas discharged from the engine of an automobile or the like, a plurality of flow paths are formed by penetrating from one bottom surface to the other bottom surface. A columnar honeycomb structure having a plurality of partition walls forming a cell partition is supported by a catalyst. In this way, when the exhaust gas is treated by the catalyst supported on the honeycomb structure, it is necessary to raise the temperature of the catalyst to its active temperature, but when the engine is started, the exhaust gas does not reach the active temperature. There was a problem that it was not sufficiently purified. In particular, plug-in hybrid vehicles (PHEVs) and hybrid vehicles (HVs) include traveling only by the motor, so the frequency of engine starting is low and the catalyst temperature at the time of starting the engine is low. Exhaust gas purification performance tends to deteriorate.

In order to solve this problem, a metal electrode is connected to a columnar honeycomb structure made of conductive ceramics, and the honeycomb structure itself is heated by energization so that the catalyst can be heated to the active temperature before starting the engine. Electric heating catalyst (EHC) has been proposed.

In EHC, in order to heat the ceramic carrier by energization and efficiently purify the exhaust gas, it is necessary to heat the ceramic carrier while making the temperature distribution inside uniform. To achieve this, it is necessary to pass the current through the ceramic carrier as uniformly as possible.

In Patent Document 1, as one of the measures, a ceramic carrier, a surface electrode arranged on the surface of the ceramic carrier, and a comb tooth in which three or more teeth are arranged in parallel with each other and connected to the surface electrode, respectively. EHC has been proposed, which is provided with a metal electrode having a portion, and the comb tooth portion is formed so that the electrical resistance of the tooth near the end is lower than the electrical resistance of the tooth near the center. Then, it is described that according to such a configuration, the temperature distribution inside the ceramic carrier can be made uniform when the ceramic carrier is energized and heated.

Japanese Unexamined Patent Publication No. 2012-106164

When the EHC is energized and heated, there is a problem that cracks occur due to the difference in thermal expansion between the honeycomb structure and the electrode layer and the metal electrode. In the EHC described in Patent Document 1, in order to allow an electric current to flow uniformly through the ceramic carrier, the shape of the metal electrode is comb-shaped. Is not paying attention.

The present invention has been made in consideration of the above problems, and provides an electrically heated carrier, an exhaust gas purifying device, and a metal electrode in which the generation of cracks due to a difference in thermal expansion during heating is satisfactorily suppressed. That is the issue.

As a result of diligent studies, the present inventor has determined that the metal electrode provided on the electrode layer arranged on the surface of the outer peripheral wall of the honeycomb structure is provided with a main body portion and a plurality of tongue pieces extending from the main body portion. , The tongue piece has a neck and a head, and the head of the tongue piece is arranged so that at least a part of it is in contact with the electrode layer. It has been found that the above problem can be solved by controlling the relationship between the length A to the tip and the minimum value B of the width of the neck. Therefore, the present invention is specified as follows.
(1) A columnar honeycomb made of ceramics having an outer peripheral wall and a partition wall which is disposed inside the outer peripheral wall and forms a plurality of cells which form a flow path from one end face to the other end face. Structure and
An electrode layer arranged on the surface of the outer peripheral wall of the columnar honeycomb structure, and
A metal electrode arranged on the electrode layer and
With
The metal electrode includes a main body portion and a plurality of tongue pieces extending from the main body portion.
The tongue piece of the metal electrode has a neck and a head.
The head of the tongue piece is arranged so that at least a part thereof is in contact with the electrode layer.
The length A from the end of the neck, which is the starting point extending from the main body of the tongue piece, to the tip of the neck and the minimum width B of the neck have a relationship of 10 <A / B ≦ 160. An electroheated carrier that meets.
(2) The electrically heated carrier according to (1) and
A can body holding the electrically heated carrier and
Exhaust gas purification device with.
(3) A metal electrode configured to be disposable on the surface of the outer peripheral wall of a ceramic columnar honeycomb structure having an outer peripheral wall and a partition wall.
The metal electrode includes a main body portion and a plurality of tongue pieces extending from the main body portion.
The tongue piece of the metal electrode has a neck and a head.
The length A from the end of the neck, which is the starting point extending from the main body of the tongue piece, to the tip of the neck and the minimum width B of the neck have a relationship of 10 <A / B ≦ 160. A metal electrode that meets.

According to the present invention, it is possible to provide an electrically heated carrier, an exhaust gas purifying device, and a metal electrode in which the generation of cracks due to a difference in thermal expansion during heating is satisfactorily suppressed.

It is a schematic appearance figure of the columnar honeycomb structure of the electric heating type carrier in embodiment of this invention. It is a schematic appearance figure of the electrode layer provided on the columnar honeycomb structure of the electric heating type carrier in embodiment of this invention, and the metal electrode provided on the electrode layer. It is a schematic appearance figure of the tongue piece in one Embodiment of this invention. It is sectional drawing of the tongue piece in another embodiment of this invention. It is sectional drawing of the tongue piece in still another embodiment of this invention. It is sectional drawing of the tongue piece in still another embodiment of this invention. It is a plane schematic diagram of the tongue piece in one Embodiment of this invention. It is a plan view of the tongue piece in another embodiment of this invention. It is a plane schematic diagram of the tongue piece in still another embodiment of this invention. It is a plane schematic diagram of the comb-tooth-shaped metal electrode which concerns on embodiment of this invention. It is sectional drawing of the electrode layer, the welding base layer and the metal electrode provided on the columnar honeycomb structure of the electric heating type carrier in embodiment of this invention.

Hereinafter, embodiments of the electrically heated carrier, the exhaust gas purifying device, and the metal electrode of the present invention will be described with reference to the drawings, but the present invention is not limited to this and is not construed as being limited to the present invention. Various changes, modifications and improvements can be made based on the knowledge of those skilled in the art as long as they do not deviate from the scope of.

<Electric heating type carrier>
FIG. 1 shows a schematic view of the appearance of the columnar honeycomb structure 10 of the electrically heated carrier 20 according to the embodiment of the present invention. FIG. 2 shows a schematic appearance of the

electrode layers

14a and 14b provided on the columnar honeycomb structure 10 of the electrically heated carrier 20 and the metal electrodes 30 provided on the

electrode layers

14a and 14b according to the embodiment of the present invention. The figure is shown.

(1. Columnar honeycomb structure)
The columnar honeycomb structure 10 includes an outer peripheral wall 12 and a partition wall 13 which is disposed inside the outer peripheral wall 12 and divides a plurality of cells 15 which penetrate from one end face to the other end face to form a flow path. Have.

The outer shape of the columnar honeycomb structure 10 is not particularly limited as long as it is columnar. , Octagon, etc.) can be shaped like a columnar shape. ^{Further, the size of the columnar honeycomb structure 10 is preferably 2000 to 20000 mm 2} and preferably 5000 to 15000 mm for the reason of improving heat resistance (suppressing cracks entering the circumferential direction of the outer peripheral wall). it is more preferably ^2.

The columnar honeycomb structure 10 has conductivity. The columnar honeycomb structure 10 is not particularly limited in electrical resistivity as long as it can be energized and generated by Joule heat, but it is preferably 0.1 to 200 Ωcm, more preferably 1 to 200 Ωcm. It is more preferably 10 to 100 Ωcm. In the present invention, the electrical resistivity of the columnar honeycomb structure 10 is a value measured at 25 ° C. by the four-terminal method.

The columnar honeycomb structure 10 is composed of ceramics and metal, and contains 40% by volume or less of metal. The metal component of the columnar honeycomb structure 10 may be 30% by volume or less, 20% by volume or less, or 10% by volume or less. The material of the columnar honeycomb structure 10 composed of ceramics and metal is not limited, but is not limited to oxide-based ceramics such as alumina, mulite, zirconia and cordierite, and non-oxide ceramics such as silicon carbide, silicon nitride and aluminum nitride. It can be selected from the group consisting of oxide-based ceramics. Further, 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 10 preferably contains a silicon-silicon carbide composite material or ceramics containing silicon carbide as a main component and a metal. , Silicon-Silicon Carbide Composite or Silicon Carbide and Metals are more preferred. When the material of the columnar honeycomb structure 10 is mainly composed of a silicon-silicon carbide composite material, the columnar honeycomb structure 10 contains the silicon-silicon carbide composite material (total mass) as a total of 90 masses. It means that it contains more than%. Here, the silicon-silicon carbide composite material contains silicon carbide particles as an aggregate and silicon as a binder for binding the silicon carbide particles, and a plurality of silicon carbide particles are formed between the silicon carbide particles. It is preferably bonded by silicon so as to form pores. When the material of the columnar honeycomb structure 10 is mainly composed of silicon carbide, it means that the columnar honeycomb structure 10 contains silicon carbide (total mass) in an amount of 90% by mass or more of the whole. means.

When the columnar honeycomb structure 10 contains a silicon-silicon carbide composite material, the “mass of silicon carbide particles as aggregate” contained in the columnar honeycomb structure 10 and the columnar honeycomb structure 10 are contained. The ratio of the "mass of silicon as a binder" contained in the columnar honeycomb structure 10 to the total of the "mass of silicon as a composite" is preferably 10 to 40% by mass, preferably 15 to 35. It is more preferably mass%. When it is 10% by mass or more, the strength of the columnar honeycomb structure 10 is sufficiently maintained. When it is 40% by mass or less, it becomes easy to maintain the shape at the time of firing.

There is no limitation on the shape of the cell in the cross section perpendicular to the extending direction of the cell 15, but it is preferably a quadrangle, a hexagon, an octagon, or a combination thereof. Among these, a quadrangle and a hexagon are preferable. By making the cell shape in this way, the pressure loss when the exhaust gas is passed through the columnar honeycomb structure 10 is reduced, and the purification performance of the catalyst is excellent. A quadrangle is particularly preferable from the viewpoint of easily achieving both structural strength and heating uniformity.

The thickness of the partition wall 13 forming the cell 15 is preferably 0.1 to 0.3 mm, more preferably 0.15 to 0.25 mm. When the thickness of the partition wall 13 is 0.1 mm or more, it is possible to suppress a decrease in the strength of the columnar honeycomb structure 10. When the thickness of the partition wall 13 is 0.3 mm or less, it is possible to suppress an increase in pressure loss when exhaust gas is flowed when the columnar honeycomb structure 10 is used as a catalyst carrier and a catalyst is supported. In the present invention, the thickness of the partition wall 13 is defined as the length of a portion of a line segment connecting the centers of gravity of adjacent cells 15 that passes through the partition wall 13 in a cross section perpendicular to the extending direction of the cell 15.

^{The columnar honeycomb structure 10 preferably has a cell density of 40 to 150 cells / cm 2} , and more preferably 70 to 100 cells / cm ² in a cross section perpendicular to the flow path direction of the cells 15. By setting the cell density in such a range, the purification performance of the catalyst can be improved while the pressure loss when the exhaust gas is passed is reduced. When the cell density is 40 cells / cm ² or more, a sufficient catalyst-supporting area is secured. When the cell density is 150 cells / cm ² or less, when the columnar honeycomb structure 10 is used as a catalyst carrier and the catalyst is supported, it is possible to prevent the pressure loss when the exhaust gas is flowed from becoming too large. The cell density is a value obtained by dividing the number of cells by the area of one bottom surface portion of the columnar honeycomb structure 10 excluding the outer wall 12 portion.

Providing the outer peripheral wall 12 of the columnar honeycomb structure 10 is useful from the viewpoint of ensuring the structural strength of the columnar honeycomb structure 10 and suppressing the fluid flowing through the cell 15 from leaking 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 made too thick, the strength becomes too high, the strength balance with the partition wall 13 is lost, and the heat impact resistance is lowered. 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 the normal direction with respect to the tangent line of the outer peripheral wall 12 at the measurement location 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 wall 13 can be made porous. The porosity of the partition wall 13 is preferably 35 to 60%, more preferably 35 to 45%. When the porosity is 35% or more, it becomes easier to suppress deformation during firing. When the porosity is 60% or less, the strength of the columnar honeycomb structure 10 is sufficiently maintained. Porosity is a value measured by a mercury porosimeter.

The average pore diameter of the partition wall 13 of the columnar honeycomb structure 10 is preferably 2 to 15 μm, more preferably 4 to 8 μm. When the average pore diameter is 2 μm or more, it is suppressed that the electrical resistivity becomes too large. When the average pore diameter is 15 μm or less, it is suppressed that the electrical resistivity becomes too small. The average pore diameter is a value measured by a mercury porosimeter.

(2. Electrode layer)
In the columnar honeycomb structure 10, a pair of

electrode layers

14a and 14b are arranged on the surface of the outer peripheral wall 12. In the pair of

electrode layers

14a and 14b, one electrode layer is provided so as to face the other electrode layer of the pair of

electrode layers

14a and 14b with the central axis of the columnar honeycomb structure 10 interposed therebetween. .. The pair of electrode layers may not be provided as described above. For example, on the surface of the outer peripheral wall 12 of the columnar honeycomb structure 10, only one of the above electrodes (either one of the electrode layer 14a or the electrode layer 14b) is provided. It may be provided.

There are no particular restrictions on the formation regions of the electrode layers 14a and 14b, but from the viewpoint of enhancing the uniform heat generation of the columnar honeycomb structure 10, each of the electrode layers 14a and 14b is on the outer surface of the outer peripheral wall 12 and is formed by the outer peripheral wall 12. It is preferable to extend the cells in a band shape in the circumferential direction and the extending direction of the cell. Specifically, each of the electrode layers 14a and 14b has a length of 80% or more, preferably a length of 90% or more, and more preferably a total length between both bottom surfaces of the columnar honeycomb structure 10. It is desirable that the current extends over the electrode layers 14a and 14b from the viewpoint that the current easily spreads in the axial direction.

In the embodiment of the present invention, the electrode layers 14a and 14b are provided with slit-shaped separation bands 19 extending along the axial direction of the columnar honeycomb structure 10, respectively, as shown in FIG. The separation band 19 has a function of alleviating the difference in thermal expansion between the columnar honeycomb structure 10 and the electrode layers 14a and 14b when the electrically heated carrier 20 is heated, and the electrode layers 14a and 14b due to the difference in thermal expansion It has a function of suppressing cracking and peeling. The width of the slit-shaped separation band 19 is not particularly limited, but can be formed to, for example, 0.5 to 3.0 mm. The separation band 19 of the electrode layers 14a and 14b may not be formed, and the electrode layer 14a and the electrode layer 14b may be one continuous electrode layer, respectively.

The thickness of each of the electrode layers 14a and 14b is preferably 0.01 to 5 mm, more preferably 0.01 to 3 mm. By setting it in such a range, uniform heat generation can be enhanced. When the thickness of each of the electrode layers 14a and 14b is 0.01 mm or more, the electric resistance is appropriately controlled and heat can be generated more uniformly. If it is 5 mm or less, the risk of damage during canning is reduced. The thickness of each of the electrode layers 14a and 14b is relative to the tangent line of the outer surface of each of the electrode layers 14a and 14b at the measurement point when the portion of the electrode layer for which the thickness is to be measured is observed in a cross section perpendicular to the stretching direction of the cell. It is defined as the thickness in the normal direction.

By making the electrical resistivity of each of the electrode layers 14a and 14b lower than the electrical resistivity of the columnar honeycomb structure 10, electricity can easily flow to the electrode layers 14a and 14b preferentially, and electricity flows in the cell flow path direction when energized. And it becomes easy to spread in the circumferential direction. The electrical resistivity of the electrode layers 14a and 14b is preferably 1/10 or less, more preferably 1/20 or less, and preferably 1/30 or less of the electrical resistivity of the columnar honeycomb structure 10. Even more preferable. However, if the difference in electrical resistivity between the two becomes too large, the current is concentrated between the ends of the electrode layers 14a and 14b facing each other, and the heat generation of the columnar honeycomb structure 10 is biased. The resistivity 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 10. In the present invention, the electrical resistivity of the electrode layers 14a and 14b is a value measured at 25 ° C. by the four-terminal method.

As the material of each of the electrode layers 14a and 14b, a composite material (cermet) of metal and conductive ceramics can be used. Examples of the metal include elemental metals of Cr, Fe, Co, Ni, Si and Ti, and alloys containing at least one metal selected from the group consisting of these metals. Examples of the conductive ceramics include, but are not limited to, silicon carbide (SiC), and examples thereof include metal compounds such as metal _{siliceates such as tantalum silicate (TaSi 2} ) and chromium _{silicate (CrSi 2).} Specific examples of the composite material (cermet) of metal and conductive ceramics include a composite material of metallic silicon and silicon carbide, a composite material of metal siliceous material such as tantalum silicate and chromium silicate, and a composite material of metallic silicon and silicon carbide, and further described above. From the viewpoint of reducing thermal expansion, a composite material obtained by adding one or more kinds of insulating ceramics such as alumina, mulite, zirconia, cordierite, silicon nitride and aluminum nitride to one or more kinds of metals can be mentioned. Among the various metals and conductive ceramics described above, the electrode layers 14a and 14b may be made of a columnar honeycomb by combining a metal silice such as tantalum silicate or chromium silicate and a composite material of metallic silicon and silicon carbide. It is preferable because it can be fired at the same time as the structural part, which contributes to simplification of the manufacturing process.

(3. Metal electrode)
The metal electrode 30 is arranged on the electrode layers 14a and 14b and is electrically bonded. As a result, when a voltage is applied to the metal electrode 30, the columnar honeycomb structure 10 can be energized and the columnar honeycomb structure 10 is heated by Joule heat. Therefore, the columnar honeycomb structure 10 can be suitably used as a heater. The applied voltage is preferably 12 to 900 V, more preferably 48 to 600 V, but the applied voltage can be changed as appropriate.

As the material of the metal electrode 30, there are no particular restrictions as long as it is a metal, and a single metal, an alloy, or the like can be adopted. However, from the viewpoint of corrosion resistance, electrical resistance, and linear expansion rate, for example, Cr, Fe, Co. , Ni and Ti are preferably used as alloys containing at least one selected from the group, and stainless steel and Fe—Ni alloys are more preferable.

The metal electrode 30 includes a main body portion 31 and a plurality of tongue pieces 32 extending from the main body portion 31. The tongue piece 32 of the metal electrode 30 has a neck portion 33 and a head portion 34, and the head portion 34 of the tongue piece 32 is arranged so that at least a part thereof is in contact with the electrode layers 14a and 14b. When the slit-shaped separation band 19 is formed in the electrode layers 14a and 14b as shown in FIG. 2, one metal electrode 30 is formed on both of the electrode layers 14a and 14b divided by the separation band 19. At least one of the plurality of tongue pieces 32 is arranged.

The main body portion 31 and the tongue piece 32 of the metal electrode 30, and the neck 33 and the head 34 of the tongue piece 32 may be formed separately and electrically connected to each other, or one metal plate. It may be integrally formed by cutting from.

The shape of the main body portion 31 is not particularly limited, but it is preferably plate-shaped from the viewpoint of manufacturing efficiency, operability, space saving, and the like. Further, the plate shape may be a flat plate shape or a curved plate shape. The main body portion 31 may have a grip portion 36 formed on the side opposite to the tongue piece 32. The grip portion 36 may be formed in a ring shape from the viewpoint of operability. Further, the grip portion 36 also has a function as a contact point for electrically connecting to the external electrode.

Each of the plurality of tongue pieces 32 is formed so that the neck portion 33 extends from the main body portion 31, and the head portion 34 at the tip thereof is electrically joined to the electrode layers 14a and 14b, respectively. As shown in FIG. 11, a welding base layer 39 may be provided between the head portion 34 and the electrode layers 14a and 14b. In this case, the welding base layer 39 is provided on the electrode layers 14a and 14b, and the head 34 of the tongue piece 32 of the metal electrode 30 is further provided on the welding base layer 39, and laser welding or the like is performed from the head 34 side. The head 34 of the metal electrode 30 and the electrode layers 14a and 14b are electrically connected by welding with the metal electrode 30. At this time, the metal electrode 30 and the welding base layer 39 on the electrode layers 14a and 14b are formed by the welding penetration portion 40 formed between at least a part of the head 34 which is the tip of the plurality of tongue pieces 32 and the welding base layer 39. Is firmly joined. Further, the joint area S of the weld penetration portion 40 becomes the minimum area required for energization, and the thermal expansion difference between the weld penetration portion 40, the weld base layer 39, and the metal electrode 30 can be suppressed. Therefore, the stress generated in the joint portion in a high temperature environment can be satisfactorily suppressed. The head 34 may be electrically bonded to the electrode layers 14a and 14b on the entire surface thereof, or may be electrically bonded to the electrode layers 14a and 14b in a part of the region of the head 34.

The welding base layer 39 can be formed of conductive ceramics. Examples of the conductive ceramics constituting the welding base layer 39 include, but are not limited to, silicon carbide (SiC), and metal compounds such as metal _{silicates such as tantalum silicate (TaSi 2} ) and chromium _{silicate (CrSi 2).} Further, a composite material (cermet) containing one or more metals can be mentioned. Specific examples of the cermet include a composite material of metallic silicon and silicon carbide, a composite material of metallic siliceous material such as tantalum silicate and chromium silicate, and a composite material of metallic silicon and silicon carbide, and further, thermal expansion to the above-mentioned one or more kinds of metals. From the viewpoint of reduction, a composite material to which one or more kinds of insulating ceramics such as alumina, mullite, zirconia, cordierite, silicon carbide and aluminum nitride are added can be mentioned.

Twelve tongue pieces 32 of the metal electrode 30 shown in FIG. 2 extend from the lower end of the main body portion 31 of the plate-shaped portion at equal intervals, and six bodies extend toward one side surface of the main body portion 31 of the plate-shaped portion. It is formed so as to be folded, and six more bodies are formed so as to be folded in the direction of the other side surface of the main body portion 31 of the plate-shaped portion. The number of tongue pieces 32 can be appropriately changed according to the requirements for the energizing performance of the metal electrode 30 and the columnar honeycomb structure 10.

The shape of the tongue piece 32 is not particularly limited, but it is preferably the shape shown in FIGS. 3 to 6, for example. The tongue piece 32 shown in FIG. 3 has the same shape as the tongue piece 32 shown in FIG. The tongue piece 32 shown in FIG. 3 is formed so that the neck portion 33 extends from one end of the plate-shaped main body portion 31, and is bent at two bent portions 35 in a direction of approximately 180 degrees, respectively, and is bent near the head portion 34. The portion 38 is bent in a direction of approximately 90 degrees. Further, the tongue piece 32 shown in FIG. 4 is formed so that the neck portion 33 extends from one end of the plate-shaped main body portion 31, is bent in a direction of approximately 180 degrees at one bent portion 35, and is near the head portion 34. The bent portion 38 is bent in a direction of approximately 90 degrees. As described above, when the tongue piece 32 includes the plurality of bent portions 35, the elasticity of the metal electrode 30 is increased, and the columnar honeycomb structure 10 and the electrode layers 14a and 14b when the electrically heated carrier 20 is heated, and the electrode layers 14a and 14b. By relaxing the difference in thermal expansion from the metal electrode 30, the occurrence of cracks can be suppressed more satisfactorily. Further, in the neck portion 33, the bent portion 35, which is a portion that is bent in a direction of approximately 180 degrees, is provided at one in FIG. 4 and two in FIG. 3, but three or more may be provided. Although it depends on the material of the neck portion 33, the more the bent portion 35, the more the elasticity of the metal electrode 30 increases, and the columnar honeycomb structure 10 and the electrode layers 14a and 14b and the metal electrode when the electrically heated carrier 20 is heated. The difference in thermal expansion from 30 can be relaxed better.

The tongue piece 32 shown in FIG. 5 is formed so that the neck portion 33 extends from one end of the plate-shaped main body portion 31, and is bent in the direction of approximately 90 degrees at the bent portion 38 near the head portion 34. The neck portion 33 shown in FIG. 6 is formed so as to extend from one end of the plate-shaped main body portion 31 and reach the head portion 34 without being bent as it is.

The metal electrode 30 according to the embodiment of the present invention has a length A from the end of the neck 33, which is a starting point extending from the main body 31 of the tongue piece 32, to the tip of the neck 33, and a minimum width B of the neck 33. Satisfies the relationship of 10 <A / B ≦ 160. In FIG. 3, the length A and the minimum value B of the width of the neck portion 33 are shown. As shown in FIG. 3, the length A is the total length of the neck portion 33 when the neck portion 33 is bent by the bent portion 35 by approximately 180 degrees. Further, in FIG. 3, the widths of the neck 33 are all uniformly formed, and the minimum value B of the width of the neck 33 may be measured at any position, but the bent portion 35 and the bent portion 38 are formed. It is preferable to measure at the removed position.

When the length A from the end of the neck 33, which is the starting point extending from the main body 31 of the tongue piece 32, to the tip of the neck 33 and the minimum width B of the neck 33 satisfy the relationship of 10 <A / B. , The elasticity of the metal electrode 30 becomes good, and the difference in thermal expansion between the columnar honeycomb structure 10 and the electrode layers 14a and 14b and the metal electrode 30 when the electrically heated carrier 20 is heated can be more satisfactorily relaxed. .. Further, the length A from the end of the neck 33, which is the starting point extending from the main body 31 of the tongue piece 32, to the tip of the neck 33, and the minimum width B of the neck 33 have a relationship of A / B ≦ 160. When it is satisfied, the strength of the metal electrode 30 is maintained, and the destruction of the metal electrode 30 can be suppressed. The length A from the end of the neck 33, which is the starting point extending from the main body 31 of the tongue piece 32, to the tip of the neck 33, and the minimum width B of the neck 33 have a relationship of 20 ≦ A / B ≦ 160. It is preferable to satisfy, it is more preferable to satisfy the relationship of 20 ≦ A / B ≦ 80, and it is further preferable to satisfy the relationship of 30 ≦ A / B ≦ 40.

The length of the neck 33 of the tongue piece 32 is preferably 10 to 1000 mm. When the length of the neck portion 33 of the tongue piece 32 is 10 mm or more, the elasticity of the metal electrode 30 increases, and the columnar honeycomb structure 10, the electrode layers 14a and 14b, and the metal electrode 30 when the electrically heated carrier 20 is heated. The difference in thermal expansion with and from can be alleviated better. Further, if the length of the neck portion 33 of the tongue piece 32 is too large, the stress due to the vibration of the metal electrode 30 increases, so that the length is preferably 1000 mm or less. The length of the neck 33 of the tongue piece 32 is more preferably 20 to 320 mm, and even more preferably 30 to 320 mm.

The minimum width B of the neck 33 of the tongue piece 32 is preferably 0.15 to 6.5 mm. When the minimum value B of the width of the neck portion 33 of the tongue piece 32 is 6.5 mm or less, the elasticity of the metal electrode 30 increases, and the columnar honeycomb structure 10 and the electrode layers 14a and 14b when the electrically heated carrier 20 is heated. And, the difference in thermal expansion from the metal electrode 30 can be relaxed more satisfactorily. Further, if the minimum value B of the width of the neck portion 33 of the tongue piece 32 is too small, the strength of the metal electrode 30 decreases, so that it is preferably 0.15 mm or more. The minimum width B of the neck 33 of the tongue piece 32 is more preferably 0.15 to 5.0 mm, and even more preferably 0.15 to 4.0 mm.

The thickness of the neck 33 and the head 34 of the tongue piece 32 is preferably 0.05 to 0.7 mm, respectively. If the thickness of the neck 33 and the head 34 of the tongue piece 32 is too small, the strength of the metal electrode 30 will decrease, so the thickness is preferably 0.05 mm or more. Further, when the thickness of the neck 33 and the head 34 of the tongue piece 32 is 0.7 mm or less, the elasticity of the metal electrode 30 increases, and the columnar honeycomb structure 10 and the electrode layer 14a when the electrically heated carrier 20 is heated. , 14b and the metal electrode 30 can better alleviate the difference in thermal expansion. The thickness of the neck 33 and the head 34 of the tongue piece 32 is more preferably 0.05 to 0.6 mm, and even more preferably 0.05 to 0.2 mm, respectively.

The larger the length of the neck 33 of the tongue piece 32 from the bent portion 35 closest to the head 34 of the tongue piece 32 to the head 34, the more the columnar honeycomb structure 10 and the columnar honeycomb structure 10 and the electric heating type carrier 20 are heated. The difference in thermal expansion between the electrode layers 14a and 14b and the metal electrode 30 can be relaxed more satisfactorily. From this point of view, it is preferable that the length of the neck 33 of the tongue piece 32 from the bent portion 35 closest to the head 34 of the tongue piece 32 to the head 34 is 10 mm or more. Further, the length is more preferably 20 mm or more, and even more preferably 30 mm or more.

The planar shapes of the neck 33 and the head 34 of the tongue piece 32 are not particularly limited, but it is preferable to form the tongue pieces 32 into the shapes shown in FIGS. 7 to 9, for example. The tongue piece 32a shown in FIG. 7 is provided with a rectangular head 34a having a width of about five times the width of the neck 33a at the tip of the elongated rectangular neck 33a. Further, the tongue piece 32b shown in FIG. 7 is provided with a rectangular head portion 34b having a width narrower than the width of the neck portion 33a at the tip of the elongated rectangular neck portion 33a.

If the shape is like the

tongue pieces

32a and 32b, the stress during thermal expansion is concentrated on the boundary between the

neck

33a and 33b and the

head

34a and 34b. Can be designed as a target.

The tongue piece 32c shown in FIG. 8 has a shape in which the width gradually expands from the elongated rectangular neck portion 33c to the maximum width. More specifically, the head 34c of the tongue piece 32c has a linear tapered shape in which the width gradually expands from the neck portion 33c of the tongue piece 32c to the maximum width.

The tongue piece 32d shown in FIG. 8 has a shape in which the width gradually decreases from the elongated rectangular neck portion 33d to the minimum width. More specifically, the head 34d of the tongue piece 32d has a linear tapered shape whose width gradually decreases from the neck portion 33d of the tongue piece 32d to the minimum width.

The tongue piece 32e shown in FIG. 9 has a shape in which the width gradually expands from the elongated rectangular neck portion 33e to the maximum width. More specifically, the head 34e of the tongue piece 32e has a parabolic taper shape in which the width gradually expands from the neck portion 33e of the tongue piece 32e to reach the maximum width.

The tongue piece 32f shown in FIG. 9 has a shape in which the width gradually decreases from the elongated rectangular neck portion 33f to the minimum width. More specifically, the head 34f of the tongue piece 32f has a parabolic taper shape in which the width gradually decreases from the neck portion 33f of the tongue piece 32f to the minimum width.

If the tongue pieces have a shape such as 32c, 32d, 32e, 32f, the stress generated during thermal expansion between the

neck

33c, 33d, 33e, 33f and the

head

34c, 34d, 34e, 34f is dispersed and relaxed. Therefore, it is possible to satisfactorily suppress the destruction in the region during thermal expansion.

As shown in FIG. 10, the metal electrode 30 g may be formed in a comb-teeth shape. The metal electrode 30 g includes a plate-shaped main body portion 31 g and a plurality of tongue pieces 32 g formed so as to extend from the plate-shaped main body portion 31 g. Each of the plurality of tongue pieces 32g includes an elongated rectangular neck portion 33g and a rectangular head portion 34g provided at the tip of the neck portion 33g, which is wider than the neck portion 33g. In the comb-teeth-shaped metal electrode 30 g, the width of the plurality of elongated rectangular neck portions 33 g can be formed to be 0.5 to 3.0 mm, respectively. Further, the head 34g may be narrower than the neck 33g as shown in FIG. 7, may have a linear taper shape as shown in FIG. 8, and may have a parabolic taper shape as shown in FIG. It may have a shape.

By supporting the catalyst on the electrically heated carrier 20, the electrically heated carrier 20 can be used as a catalyst. For example, a fluid such as automobile exhaust gas can flow through the flow paths of the plurality of cells 15. Examples of the catalyst include noble metal-based catalysts and catalysts other than these. As the noble metal catalyst, a noble metal such as platinum (Pt), palladium (Pd), or rhodium (Rh) is supported on the surface of the alumina pores, and a three-way catalyst containing a co-catalyst such as ceria or zirconia, an oxidation catalyst, or an alkali. _{An example is a NO x} storage reduction catalyst (LNT catalyst) containing earth metal and platinum as storage components of _{nitrogen oxide (NO x).} Examples of catalysts that do not use noble metals include NO _x selective reduction catalysts (SCR catalysts) containing copper-substituted or iron-substituted zeolites. Further, two or more kinds of catalysts selected from the group consisting of these catalysts may be used. The method of supporting the catalyst is also not particularly limited, and can be carried out according to the conventional method of supporting the catalyst on the honeycomb structure.

<Manufacturing method of electrically heated carrier>
Next, a method for producing the electrically heated carrier 20 according to the present invention will be exemplified. In one embodiment, the method for producing the electroheated carrier 20 of the present invention includes a step A1 for obtaining an unfired columnar honeycomb structure portion with an electrode layer forming paste and a columnar structure by firing the unfired columnar honeycomb structure portion with an electrode layer forming paste. The step A2 for obtaining the honeycomb structure and the step A3 for welding the metal electrode to the columnar honeycomb structure are included.

In step A1, a columnar honeycomb molded body which is a precursor of the columnar honeycomb structure is produced, and an electrode layer forming paste is applied to the side surface of the columnar honeycomb molded body to obtain an unfired columnar honeycomb structure with the electrode layer forming paste. It is a process. The columnar honeycomb molded body can be produced according to the method for producing a columnar honeycomb molded body in a known method for producing a columnar honeycomb structure. For example, first, a metal silicon powder (metal silicon), a binder, a surfactant, a pore-forming material, water, or the like is added to silicon carbide powder (silicon carbide) to prepare a molding raw material. It is preferable that the mass of the metallic silicon is 10 to 40% by mass with respect to the total of the mass of the silicon carbide powder and the mass of the metallic silicon. The average particle size of the 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 metallic silicon (metallic silicon powder) is preferably 2 to 35 μm. The average particle diameter of silicon carbide particles and metallic silicon (metal silicon particles) refers to the arithmetic average diameter based on the volume when the frequency distribution of particle size is measured by the laser diffraction method. The silicon carbide particles are fine particles of silicon carbide constituting the silicon carbide powder, and the metallic silicon particles are fine particles of metallic silicon constituting the metallic silicon powder. This is a blending of molding raw materials when the material of the columnar honeycomb structure is silicon-silicon carbide-based composite material, and when the material of the columnar honeycomb structure is silicon carbide, metallic silicon is added. do not.

Examples of the binder include methyl cellulose, hydroxypropyl methyl cellulose, hydroxypropoxyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, polyvinyl alcohol and the like. Among these, it is preferable to use methyl cellulose and hydroxypropoxyl cellulose in combination. The binder content is preferably 2.0 to 10.0 parts by mass when the total mass of the silicon carbide powder and the metallic silicon powder is 100 parts by mass.

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

As the surfactant, ethylene glycol, dextrin, fatty acid soap, polyalcohol and the like can be used. These may be used individually by 1 type, or 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 becomes pores after firing, and examples thereof include graphite, starch, foamed resin, water-absorbent resin, and silica gel. 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 metallic silicon powder is 100 parts by mass. The average particle size of the pore-forming material is preferably 10 to 30 μm. If it is smaller than 10 μm, pores may not be sufficiently formed. If it is larger than 30 μm, it may clog the base during molding. The average particle size of the pore-forming material refers to the arithmetic mean diameter based on the volume when the frequency distribution of the particle size is measured by the laser diffraction method. When the pore-forming material is a water-absorbent resin, the average particle size of the pore-forming material is the average particle size after water absorption.

Next, after kneading the obtained molding raw materials to form a clay, the clay is extruded to produce a columnar honeycomb molded body. In extrusion molding, a mouthpiece having a desired overall shape, cell shape, partition wall thickness, cell density and the like can be used. Next, it is preferable to dry the obtained columnar honeycomb molded body. When the length in the central axis direction of the columnar honeycomb molded body is not the desired length, both bottom portions of the columnar honeycomb molded body can be cut to obtain the desired length. The columnar honeycomb molded body after drying is called a columnar honeycomb dried body.

Next, the electrode layer forming paste for forming the electrode layer is prepared. The electrode layer forming paste can be formed by appropriately adding various additives to the raw material powder (metal powder, ceramic powder, etc.) blended according to the required characteristics of the electrode layer and kneading. 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 electrode and the electrode layer tends to improve. The average particle size of the metal powder refers to the arithmetic mean diameter based on the volume when the frequency distribution of the particle size is measured by the laser diffraction method.

Next, the obtained electrode layer forming paste is applied to the side surface of the columnar honeycomb molded body (typically, the columnar honeycomb dried body) to obtain an unfired columnar honeycomb structure with the electrode layer forming paste. The method of preparing the electrode layer forming paste and the method of applying the electrode layer forming paste to the columnar honeycomb structure can be performed according to a known method for producing a columnar honeycomb structure, but the electrode layer has a columnar honeycomb structure. In order to have a lower electrical resistance than that of the body, the metal content ratio can be increased or the particle size of the metal particles can be reduced as compared with the columnar honeycomb structure.

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

In step A2, the unfired columnar honeycomb structure with the electrode layer forming paste is fired to obtain a columnar honeycomb structure. Before firing, the unfired columnar honeycomb structure with the electrode layer forming paste may be dried. Further, before firing, degreasing may be performed in order to remove the binder 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. Further, after firing, it is preferable to carry out an 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.

In step A3, a pair of metal electrodes are welded to the surface of the electrode layer on the columnar honeycomb structure. As a welding method, a laser welding method is preferable from the viewpoint of controlling the welding area and production efficiency. At this time, the heads, which are the tips of the plurality of tongue pieces of the metal electrodes, are arranged on the electrode layer and welded from the head side. As a result, an electrically heated carrier in which the metal electrode is electrically connected to the electrode layer is obtained.

<Exhaust gas purification device>
The electrically heated carrier according to each embodiment of the present invention described above can be used for an exhaust gas purification device. The exhaust gas purifying device has an electrically heated carrier and a can body that holds the electrically heated carrier. In the exhaust gas purification device, the electrically heated carrier is installed in the middle of the exhaust gas flow path for flowing the exhaust gas from the engine. As the can body, a metal tubular member or the like accommodating an electrically heated carrier can be used.

Hereinafter, examples for better understanding the present invention and its advantages will be illustrated, but the present invention is not limited to the examples.

<Example>
(1. Preparation of columnar clay)
Silicon carbide (SiC) powder and metallic silicon (Si) powder were mixed at a mass ratio of 80:20 to prepare a ceramic raw material. Then, hydroxypropyl methylcellulose as a binder and a water-absorbent resin as a pore-forming material were added to the ceramic raw material, and water was added to prepare a molding raw material. Then, the molding raw material was kneaded with a vacuum clay kneader to prepare a columnar clay. The binder content was 7 parts by mass when the total of the silicon carbide (SiC) powder and the metallic silicon (Si) powder was 100 parts by mass. The content of the pore-forming material was 3 parts by mass when the total of the silicon carbide (SiC) powder and the metallic silicon (Si) powder was 100 parts by mass. The water content was 42 parts by mass when the total of the silicon carbide (SiC) powder and the metallic silicon (Si) powder was 100 parts by mass. The average particle size of the silicon carbide powder was 20 μm, and the average particle size of the metallic silicon powder was 6 μm. The average particle size of the pore-forming material was 20 μm. The average particle size of the silicon carbide powder, the metallic silicon powder, and the pore-forming material refers to the arithmetic mean diameter based on the volume when the frequency distribution of the particle size is measured by the laser diffraction method.

(2. Preparation of dried honeycomb)
The obtained columnar clay was molded using an extrusion molding machine having a grid-like base structure to obtain a columnar honeycomb molded body in which each cell shape is square in a cross section perpendicular to the cell flow path direction. rice field. This honeycomb molded body was dried by high frequency dielectric heating and then dried at 120 ° C. for 2 hours using a hot air dryer, and both bottom surfaces were cut by a predetermined amount to prepare a honeycomb dried body.

(3. Preparation of electrode layer forming paste)
Metallic silicon (Si) powder, silicon carbide (SiC) powder, methyl cellulose, glycerin, and water were mixed with a rotating and revolving stirrer to prepare an electrode layer forming paste. The Si powder and the SiC powder were blended so that the volume ratio was 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 average particle size of the silicon carbide powder was 35 μm. These average particle diameters refer to the arithmetic mean diameters based on the volume when the frequency distribution of particle size is measured by the laser diffraction method.

(4. Paste application)
The electrode layer forming paste was applied to the outer surface of the outer peripheral wall of the dried honeycomb body at two locations so as to face each other with the central axis interposed therebetween. Each coating portion was formed in a band shape over the entire length between both bottom surfaces of the dried honeycomb body, and each was provided with a slit-shaped separation band extending along the axial direction of the dried honeycomb body. Next, the dried honeycomb structure after applying the electrode layer forming paste was dried at 120 ° C. to obtain an unfired honeycomb structure with the electrode layer forming paste.

(5. Baking)
Next, the unfired honeycomb structure with the electrode layer forming paste was degreased at 550 ° C. for 3 hours in an air atmosphere. Next, the unfired honeycomb structure with the degreased electrode layer forming paste was fired and oxidized to prepare a honeycomb structure. The firing was carried out in an argon atmosphere at 1450 ° C. for 2 hours. The oxidation treatment was carried out in the air at 1300 ° C. for 1 hour.

The bottom surface of the honeycomb structure was circular with a diameter of 100 mm, and the height (length in the flow path direction of the cell) was 100 mm. The cell density was 93 cells / cm ² , the thickness of the partition was 101.6 μm, the porosity of the partition was 45%, and the average pore diameter of the partition was 8.6 μm. The thickness of the electrode layer was 0.3 mm. When the electrical resistivity at 400 ° C. was measured by the four-terminal method using a test piece made of the same material as the honeycomb structure and the electrode layer, it was 5 Ωcm, 0.01 Ω cm, and 0.001 Ω cm, respectively.

(6. Formation and welding of metal electrodes)
A metal electrode having the shape shown in FIG. 2 was formed by cutting a stainless steel plate and then bending it. For each metal electrode, the length A from the end of the neck, which is the starting point extending from the main body of the tongue piece, to the tip of the neck, the minimum width B of the neck, and the thickness t of the neck and head of the tongue piece, respectively. It is shown in Table 1. Next, half of the 12 tongue pieces of the metal electrode are arranged on both of the electrode layers divided by the median strip, and each head is brought into contact with the electrode layer to perform laser welding from the head side. rice field.

<Evaluation of stress relaxation>
As described above, a ceramic mat was wound around a honeycomb structure in which tongue pieces were fixed by welding to prepare a test product. Next, the test product was stored in a metal container, and a thermal shock test (vibration test) was conducted in which vibration with a frequency of 100 Hz and an acceleration of 30 G was applied for 24 hours. Next, the honeycomb structure after the thermal shock test is taken out from the metal storage container and visually inspected, and the number of path disconnections of the metal electrode regarding the portion joined to the honeycomb structure (number of peeling of the joint portion /). Number of metal breaks) was detected.
Table 1 shows each of the above evaluation conditions and evaluation results.

(Discussion)
In Examples 1 to 10, the length A from the end of the neck, which is the starting point extending from the main body of the tongue piece, to the tip of the neck and the minimum width B of the neck are 10 <A / B ≦ 160. Since the relationship was satisfied, the peeling of the joint portion after the thermal shock test was well suppressed.
On the other hand, none of Comparative Examples 1 to 4 satisfied the relationship of 10 <A / B ≦ 160, so that the peeling of the joint portion after the thermal shock test increased as compared with each Example.

10 Columnar honeycomb structure 12 Outer wall 13

Partition

14a, 14b Electrode layer 15 Cell 19 Separation zone 20 Electric

heating type carrier

30,

30g Metal electrode

31,

31g Body part

32, 32a, 32b, 32c, 32d, 32e, 32f,

32g Tongue pieces

33, 33a, 33b, 33c, 33d, 33e, 33f,

33g Neck

34, 34a, 34b, 34c, 34d, 34e, 34f, 34g Head 35 Bent 36 Grip 38 Bend 39 Welding base layer 40 Weld penetration

Claims

A columnar honeycomb structure made of ceramics having an outer peripheral wall, a partition wall arranged inside the outer peripheral wall and partitioning a plurality of cells forming a flow path from one end face to the other end face. ,
An electrode layer arranged on the surface of the outer peripheral wall of the columnar honeycomb structure, and
A metal electrode arranged on the electrode layer and
With
The metal electrode includes a main body portion and a plurality of tongue pieces extending from the main body portion.
The tongue piece of the metal electrode has a neck and a head.
The head of the tongue piece is arranged so that at least a part thereof is in contact with the electrode layer.
The length A from the end of the neck, which is the starting point extending from the main body of the tongue piece, to the tip of the neck and the minimum width B of the neck have a relationship of 10 <A / B ≦ 160. An electroheated carrier that meets.
The electrically heated carrier according to claim 1, wherein the thickness of the neck and the head of the tongue piece is 0.05 to 0.7 mm, respectively.
The electrically heated carrier according to claim 1 or 2, wherein the minimum value B of the width of the neck of the tongue piece is 0.15 to 6.5 mm.
The electroheated carrier according to any one of claims 1 to 3, wherein the length of the neck of the tongue piece is 10 to 1000 mm.
The electroheated carrier according to any one of claims 1 to 4, wherein the head of the tongue piece has a shape in which the width gradually expands from the neck of the tongue piece to reach the maximum width.
The electroheated carrier according to claim 5, wherein the head of the tongue piece has a linear tapered shape in which the width gradually expands from the neck of the tongue piece to reach the maximum width.
The electroheated carrier according to claim 5, wherein the head of the tongue piece has a parabolic taper shape in which the width gradually expands from the neck of the tongue piece to reach the maximum width.
The electroheated carrier according to any one of claims 1 to 4, wherein the head of the tongue piece has a shape in which the width gradually decreases from the neck of the tongue piece to reach the minimum width.
The electroheated carrier according to claim 8, wherein the head of the tongue piece has a linear tapered shape in which the width gradually decreases from the neck of the tongue piece to the minimum width.
The electroheated carrier according to claim 8, wherein the head of the tongue piece has a parabolic taper shape in which the width gradually decreases from the neck of the tongue piece to the minimum width.
The electroheated carrier according to any one of claims 1 to 10, wherein the neck of the tongue piece has two or more bent portions.
The electrically heated carrier according to claim 11, wherein the length from the bent portion closest to the head of the tongue piece to the head of the neck of the tongue piece is 10 mm or more.
The electrically heated carrier according to any one of claims 1 to 12, wherein the metal electrode has a comb-like shape.
The electrode layer disposed on the surface of the outer peripheral wall of the columnar honeycomb structure is arranged so as to face the surface of the outer peripheral wall of the columnar honeycomb structure with the central axis of the columnar honeycomb structure interposed therebetween. The electrically heated carrier according to any one of claims 1 to 13, which is a pair of electrode layers.
The electrically heated carrier according to any one of claims 1 to 14,
A can body holding the electrically heated carrier and
Exhaust gas purification device with.
A metal electrode configured to be disposable on the surface of the outer peripheral wall of a ceramic columnar honeycomb structure having an outer peripheral wall and a partition wall.
The metal electrode includes a main body portion and a plurality of tongue pieces extending from the main body portion.
The tongue piece of the metal electrode has a neck and a head.
The length A from the end of the neck, which is the starting point extending from the main body of the tongue piece, to the tip of the neck and the minimum width B of the neck have a relationship of 10 <A / B ≦ 160. A metal electrode that meets.