JP7335836B2 - Electrically heated carrier, exhaust gas purifier, and method for producing electrically heated carrier - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electrically heated carrier, an exhaust gas purifier, and a method for producing an electrically heated carrier. In particular, the present invention relates to an electrically heated carrier, an exhaust gas purifying device, and a method for manufacturing an electrically heated carrier, in which bonding reliability between a metal terminal and a honeycomb structure is excellent.

Conventionally, a plurality of cells forming a flow path penetrating from one bottom surface to the other bottom surface in order to purify harmful substances such as HC, CO, and _NOx contained in exhaust gas emitted from automobile engines. A columnar honeycomb structure having a plurality of partition walls defining a catalyst is used. In this way, when exhaust gas is treated by the catalyst supported on the honeycomb structure, it is necessary to raise the temperature of the catalyst to its activation temperature. I had a problem with not cleaning. In particular, plug-in hybrid electric vehicles (PHEV) and hybrid electric vehicles (HV) include driving only by the motor in their running, so the engine start frequency is low, and the catalyst temperature at engine start is low. Exhaust gas purification performance tends to deteriorate.

In order to solve this problem, a pair of terminals are connected to a columnar honeycomb structure made of conductive ceramics, and the honeycomb structure itself is heated by electricity so that the catalyst can be heated to its activation temperature before starting the engine. An electrically heated catalyst (EHC) has been proposed. In EHC, in order to obtain a sufficient catalytic effect, it is desired to reduce the temperature unevenness in the honeycomb structure so as to achieve a uniform temperature distribution.

Although the terminal is generally made of metal, the material is different from that of the honeycomb structure made of ceramics. Therefore, in applications where the honeycomb structure is used in a high-temperature oxidizing atmosphere such as in an automobile exhaust pipe, it is required to ensure mechanical and electrical connection reliability between the honeycomb structure and the metal terminal in a high-temperature environment.

In order to address such a problem, Patent Document 1 discloses a technique in which thermal energy is applied from the metal terminal side to join the metal terminal onto the electrode layer of the honeycomb structure by welding. Further, it is described that such a configuration can provide a conductive honeycomb structure with improved bonding reliability to a metal terminal.

JP 2018-172258 A

As a result of studies by the present inventors, it was found that the conductive honeycomb structure of Patent Document 1 has the following problems. That is, when the electrode layer of the honeycomb structure and the metal terminal are welded by laser irradiation, if the amount of metal contained in the electrode layer side is small, the surface that fuses with the metal terminal is reduced, and the honeycomb structure and the metal terminal are welded together. was found to be difficult to bond well. On the other hand, it was found that when the metal content of the honeycomb structure is increased, the difference in thermal expansion between the honeycomb structure and the ceramics is increased, and cracks are likely to occur. As described above, conventionally, there has been a problem of bonding reliability due to defective bonding and occurrence of cracks between the honeycomb structure and the metal terminal, and there is room for improvement.

The present invention has been created in view of the above circumstances, and provides an electrically heated carrier, an exhaust gas purifying device, and a method for manufacturing an electrically heated carrier, in which bonding reliability between a metal terminal and a honeycomb structure is excellent. is the subject.

As a result of intensive studies, the inventors of the present invention have found that the above problem can be solved by configuring the honeycomb structure to have a surface containing 40% by volume or more of metal in the welded portion with the metal terminal. That is, the present invention is specified as follows.
(1) A columnar honeycomb having an outer peripheral wall and porous partition walls that are disposed inside the outer peripheral wall and partition and form a plurality of cells that penetrate from one end face to the other end face to form a flow path. a conductive honeycomb structure having a structure;
a pair of metal terminals arranged to face each other across the central axis of the columnar honeycomb structure and joined to the surface of the conductive honeycomb structure via a welding site;
with
The columnar honeycomb structure portion is composed of ceramics and metal, and contains 40% by volume or less of metal,
The electrically heated carrier, wherein the welded portion of the honeycomb structure has a surface containing 40% by volume or more of the metal.
(2) the electrically heated carrier according to (1);
a can body holding the electrically heated carrier;
An exhaust gas purification device having
(3) having an outer peripheral wall and a porous partition wall disposed inside the outer peripheral wall and partitioning and forming a plurality of cells forming a flow path penetrating from one end surface to the other end surface; a conductive honeycomb structure having columnar honeycomb structure parts made of ceramics and metal;
a pair of metal terminals arranged to face each other across the central axis of the columnar honeycomb structure;
A method for producing an electrically heated carrier comprising
applying a first thermal energy to the surface of the honeycomb structure to form a surface containing 40% or more of the metal;
The metal terminal is arranged in a portion of the honeycomb structure having a surface containing 40% or more of the metal, and a second heat energy larger than the first heat energy is applied to the metal terminal to obtain the honeycomb structure. a step of bonding the metal terminal to the surface of
A method for producing an electrically heated carrier comprising:
(4) having an outer peripheral wall and a porous partition wall disposed inside the outer peripheral wall and partitioning and forming a plurality of cells forming a flow path penetrating from one end surface to the other end surface; a conductive honeycomb structure having columnar honeycomb structure portions made of ceramics having a melting point of 1600° C. or less and metal;
a pair of metal terminals arranged to face each other across the central axis of the columnar honeycomb structure;
A method for producing an electrically heated carrier comprising
applying a first thermal energy to the surface of the honeycomb structure to vaporize at least part of the ceramics to form a surface containing 40% or more of the metal;
The metal terminal is arranged in a portion of the honeycomb structure having a surface containing 40% or more of the metal, and a second heat energy larger than the first heat energy is applied to the metal terminal to obtain the honeycomb structure. a step of bonding the metal terminal to the surface of
A method for producing an electrically heated carrier comprising:

According to the present invention, it is possible to provide an electrically heated carrier, an exhaust gas purifying device, and a method for manufacturing an electrically heated carrier in which bonding reliability between a metal terminal and a honeycomb structure is excellent.

FIG. 2 is a schematic cross-sectional view perpendicular to the extending direction of cells of the electrically heated carrier in Embodiment 1 of the present invention. 1 is a schematic external view of a honeycomb structure according to Embodiment 1 of the present invention. FIG. FIG. 3 is a schematic cross-sectional view of the vicinity of a joint portion between a honeycomb structure and a metal terminal, for showing the state of a welding method in Embodiment 1 of the present invention. FIG. 4 is a schematic cross-sectional view perpendicular to the extending direction of the cells of the electrically heated carrier in Embodiment 2 of the present invention. FIG. 5 is a schematic cross-sectional view of the vicinity of a joint portion between a honeycomb structure and a metal terminal, for showing the state of a welding method in Embodiment 2 of the present invention. FIG. 10 is a schematic cross-sectional view perpendicular to the extending direction of the cells of the electrically heated carrier in Embodiment 3 of the present invention. FIG. 10 is a schematic cross-sectional view of the vicinity of a joint portion between a honeycomb structure and a metal terminal, for showing a state of a welding method in Embodiment 3 of the present invention. FIG. 10 is a schematic cross-sectional view perpendicular to the extending direction of the cells of the electrically heated carrier in Embodiment 4 of the present invention. FIG. 10 is a schematic cross-sectional view of the vicinity of a joint portion between a honeycomb structure and a metal terminal, for showing a state of a welding method in Embodiment 4 of the present invention.

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.

<Embodiment 1>
(1. Electrically heated carrier)
FIG. 1 is a schematic cross-sectional view perpendicular to the cell extension direction of an electrically heated carrier 20 according to Embodiment 1 of the present invention. The electrically heated carrier 20 includes a honeycomb structure 10 and a pair of metal terminals 21a and 21b.

(1-1. Honeycomb structure)
FIG. 2 shows a schematic external view of the conductive honeycomb structure 10 according to Embodiment 1 of the present invention. The conductive honeycomb structure 10 includes an outer peripheral wall 12 and a porous porous structure that is disposed inside the outer peripheral wall 12 and defines a plurality of cells 15 that penetrate from one end face to the other end face to form a flow path. It has a columnar honeycomb structure 11 having partition walls 13 .

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

The columnar honeycomb structure portion 11 has electrical conductivity. The electrical resistivity of the ceramics is not particularly limited as long as the conductive honeycomb structure 10 is energized and can generate heat by Joule heat. preferable. In the present invention, the electrical resistivity of the columnar honeycomb structure portion 11 is a value measured at 400° C. by a four-probe method.

The columnar honeycomb structure portion 11 is composed of ceramics and metal, and contains 40% by volume or less of metal. The metal component of the columnar honeycomb structure portion 11 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 11 made of ceramics and metal is not limited, but may be oxide-based ceramics such as alumina, mullite, zirconia and cordierite, and non-metallic materials such as silicon carbide, silicon nitride and aluminum nitride. It can be selected from the group consisting of oxide ceramics. 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 portion 11 preferably contains a silicon-silicon carbide composite material or a ceramic containing silicon carbide as a main component and a metal. , a silicon-silicon carbide composite or silicon carbide and a metal. 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. When it is 10% by mass or more, the strength of the columnar honeycomb structure body 11 is sufficiently maintained. When it is 40% by mass or less, it becomes easier to retain the shape during firing.

Although there is no limitation on the shape of the cells in the cross section perpendicular to the extending direction of the cells 15, it is preferably square, hexagonal, octagonal, or a combination thereof. Among these, squares and hexagons are preferred. By making the cell shape as described above, the pressure loss when the exhaust gas is caused to flow through the columnar honeycomb structure portion 11 is reduced, and the purification performance of the catalyst is excellent. A rectangular shape is particularly preferable from the viewpoint that it is easy to achieve both structural strength and heating uniformity.

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

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 15 . 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. When the cell density is 40 cells/cm ² or more, a sufficient catalyst supporting area is ensured. When the cell density is 150 cells/cm ² or less, when the columnar honeycomb structure portion 11 is used as a catalyst carrier to carry a catalyst, pressure loss when exhaust gas flows is suppressed from becoming too large. 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 11 excluding the outer 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 15 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 13 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 13 can be porous. The porosity of the partition walls 13 is preferably 35-60%, more preferably 35-45%. 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 honeycomb structure is sufficiently maintained. The porosity is a value measured with a mercury porosimeter.

The average pore size of the partition walls 13 of the columnar honeycomb structure 11 is preferably 2 to 15 μm, more preferably 4 to 8 μm. When the average pore diameter is 2 μm or more, excessive increase in electrical resistivity is suppressed. When the average pore diameter is 15 µm or less, the electrical resistivity is prevented from becoming too small. The average pore diameter is a value measured with a mercury porosimeter.

The conductive honeycomb structure 10 has a pair of electrode layers 14 a and 14 b made of ceramics and metal on the surface of the outer peripheral wall 12 of the columnar honeycomb structure 11 . One electrode layer of the pair of electrode layers is provided so as to face the other electrode layer of the pair of electrode layers with the central axis of the columnar honeycomb structure portion 11 interposed therebetween. A pair of electrode layers 14a, 14b are provided with weld sites 17a, 17b.

Although there are no particular restrictions on the regions where the electrode layers 14a and 14b are formed, from the viewpoint of improving the uniform heat generation property of the columnar honeycomb structure portion 11, the electrode layers 14a and 14b are formed on the outer surface of the outer peripheral wall 12. It is preferable to extend in a strip shape in the circumferential direction and in the extending direction of the cells. Specifically, each of the electrode layers 14a and 14b extends 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, more preferably over the entire length. Extending across the electrode layers 14a and 14b is desirable from the viewpoint that the current tends to spread in the axial direction.

The thickness of each electrode layer 14a, 14b 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. When the thickness of each of the electrode layers 14a and 14b is 0.01 mm or more, the electrical resistance is appropriately controlled and heat can be generated more uniformly. If it is 5 mm or less, the risk of breakage during canning is reduced. The thickness of each electrode layer 14a, 14b is measured against the tangential line at the measurement point of the outer surface of each electrode layer 14a, 14b when the portion of the electrode layer whose thickness is to be measured is observed in a cross section perpendicular to the extending direction of the cell. Defined as normal thickness.

By making the electrical resistivity of the electrode layers 14a and 14b lower than the electrical resistivity of the columnar honeycomb structure 11, electricity preferentially flows through the electrode layers. spread more easily. The electrical resistivity of the electrode layers 14a and 14b 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 electric current concentrates between the ends of the opposing electrode layers, and the heat generation of the columnar honeycomb structure is uneven. It 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 14a and 14b is a value measured at 400° C. by a four-probe method.

A composite material (cermet) of metal and conductive ceramics can be used for the material of each electrode layer 14a, 14b. 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 14a and 14b, 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 simultaneously with the structural portion, which contributes to simplification of the manufacturing process.

(1-2. Metal terminal)
The pair of metal terminals 21a and 21b are arranged so as to face each other with the central axis of the columnar honeycomb structure portion 11 of the honeycomb structure 10 interposed therebetween, and are provided on the pair of electrode layers 14a and 14b, respectively. is joined to Accordingly, when a voltage is applied to the metal terminals 21a and 21b through the electrode layers 14a and 14b, the conductive honeycomb structure 10 can be heated by Joule heat. Therefore, the conductive honeycomb structure 10 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.

A pair of metal terminals 21a and 21b are joined to the surface of the conductive honeycomb structure 10 via welding portions 17a and 17b, respectively.

The material of the metal terminals 21a and 21b 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 terminals 21a and 21b are not particularly limited, and can be appropriately designed according to the size of the electrically heated carrier 20, the current-carrying performance, and the like.

The metal terminals 21a, 21b are joined to the respective electrode layers 14a, 14b via one or two or more welded portions 17a, 17b. By reducing the welding area of each welded portion 17a, 17b, it is possible to suppress cracking and peeling due to the difference in thermal expansion. Specifically, the welded area of the welded portions 17a and 17b per location is preferably 50 mm ² or less, more preferably 45 mm ² or less, even more preferably 40 mm ² or less, and 30 mm ² or less. It is even more preferable that However, if ^the welded area of ^the welded parts 17a and 17b per one point ^is excessively small, the joint strength cannot be ensured. is even more preferred.

Although it depends on the size of the metal terminals 21a and 21b, it is preferable to increase the joint strength by forming two or more welded portions 17a and 17b to increase the total welded area. Specifically, the total welded area of each metal terminal at one or more welded portions is preferably 2 mm ² or more, more preferably 3 mm ² or more, and further preferably 4 mm ² or more. more preferred. On the other hand, if the total welded area is excessively increased, thermal shock resistance tends to deteriorate. Therefore, from the viewpoint of ensuring thermal shock resistance, the total welded area for each metal terminal of one or more welded portions 17a and 17b is preferably 120 mm ² or less, and is 110 mm ² or less. is more preferable, and 100 mm ² or less is even more preferable.

In addition, when there are two or more welded portions 17a and 17b for each metal terminal, from the viewpoint of increasing the joint strength while ensuring thermal shock resistance, the interval between the adjacent welded portions is adjusted according to the welded area of the welded portion. It is preferable to secure at least a certain level. There is no particular problem even if the distance between the welded parts is large, and the distance may be appropriately set in consideration of the size of the metal terminal.

The welded portions 17a, 17b of the respective electrode layers 14a, 14b have surfaces containing 40% by volume or more of metal. With such a configuration, the metal terminals can be satisfactorily joined to the conductive honeycomb structure, and the reliability of joining between the conductive honeycomb structure and the metal terminals is improved. The upper limit of the metal volume ratio of the surfaces of the welded portions 17a and 17b containing 40% by volume or more of metal is not particularly limited, and can be appropriately designed according to the thickness of the surfaces. The volume percentage of metal on the surface can be, for example, 40-100% by volume. Moreover, it is preferable that the entire welded portion of the conductive honeycomb structure has a surface containing 40% by volume or more of the metal. With such a configuration, the surfaces on which the conductive honeycomb structure and the metal terminals are satisfactorily bonded are increased, so that the reliability of bonding between the conductive honeycomb structure and the metal terminals is further improved.

The welded portions 17a, 17b of the electrode layers 14a, 14b preferably have a surface depth of 0.05 to 5 mm containing 40% by volume or more of metal. If the depth of the surface containing 40% by volume or more of the metal is less than 0.05 mm, there is a risk that the honeycomb structure and the metal terminal will be poorly joined. Moreover, if the depth of the surface containing 40% by volume or more of the metal exceeds 5 mm, the difference in thermal expansion from the ceramics of the honeycomb structure increases, and cracks may occur. The welded portions 17a, 17b of the electrode layers 14a, 14b preferably have a surface containing 40% by volume or more of metal and have a depth of 0.05 to 2 mm, more preferably 0.05 to 0.5 mm. Even more preferred.

By supporting a catalyst on the electrically heated carrier 20, the electrically heated carrier 20 can be used as a catalyst body. For example, a fluid such as automobile exhaust gas can flow through the flow paths of the plurality of cells 15 . 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.

(2. Method for producing electrically heated carrier)
Next, a method for manufacturing the electrically heated carrier 20 according to the present invention will be exemplified. In one embodiment of the method for manufacturing the electrically heated carrier 20 of the present invention, a step A1 of obtaining an unfired honeycomb structure portion with the electrode layer forming paste; It includes a step A2 of obtaining a structure and a step A3 of welding metal terminals to the conductive honeycomb structure.

Step A1 is a step of producing a formed honeycomb body, which is a precursor of the honeycomb structure portion, and applying the electrode layer forming paste to the side surface of the formed honeycomb portion to obtain an unfired honeycomb structure portion with the electrode layer forming paste. The formed honeycomb body can be manufactured according to a method for manufacturing a formed honeycomb body in a known method for manufacturing a honeycomb structure. For example, first, metal silicon powder (metal silicon), a binder, a surfactant, a pore-forming material, water, etc. are added to silicon carbide powder (silicon carbide) to prepare a forming raw material. It is preferable that the mass of the metallic silicon is 10 to 40% by mass with respect to the sum of the mass of the silicon carbide powder and the mass of the metallic silicon. 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 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. It should be noted that this is the composition of the forming raw materials when the material of the honeycomb structure is a silicon-silicon carbide composite material, and when the material of the honeycomb structure 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 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 metal silicon powder is 100 parts by mass. The average particle size of the pore-forming material is preferably 10-30 μm. If the thickness is less than 10 μm, sufficient pores may not be formed. If it is larger than 30 μm, the die may be clogged during molding. 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 extruded 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.

Next, an electrode layer forming paste for forming an electrode layer is prepared. The electrode layer forming paste can be formed by appropriately adding various additives to raw material powders (metal powder, 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.

Next, the obtained electrode layer forming paste is applied to the side surface of the formed honeycomb body (typically the dried honeycomb body) to obtain an unfired honeycomb structure portion 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 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 modification of the method for manufacturing a conductive 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 unfired honeycomb structure body with the electrode layer forming paste is fired to obtain a conductive honeycomb structure. 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.

In step A3, a pair of metal terminals are welded to the surface of the electrode layer on the honeycomb structure portion of the conductive honeycomb structure. As the welding method, a method of laser welding is preferable from the viewpoint of control of the welding area and production efficiency. At this time, laser irradiation is performed twice in total, divided into a front stage and a rear stage. Specifically, first, as shown in FIG. 3, first thermal energy is applied to the surfaces of the electrode layers 14a and 14b on the columnar honeycomb structure 11 by a laser 30, and the surfaces containing 40% by volume or more of metal are heated. to form Parts having surfaces containing 40% by volume or more of the metal are defined as welding parts 17a and 17b. At this time, the thermal energy of the laser melts the metal component contained in the electrode layer and agglomerates it near the surface. By adjusting the thermal energy, a surface containing 40% by volume or more of metal can be formed.

In the above method, the surface containing 40% by volume or more of the metal is formed by aggregating the metal component on the surface of the electrode layer by the laser irradiation in the preceding stage. However, the method of forming a surface containing 40% by volume or more of the metal is not limited to this. For example, the first heat energy may be applied to the surface of the conductive honeycomb structure after the columnar honeycomb structure is composed of ceramics having a melting point of 1600° C. or less and metal. At this time, at least part of the ceramic component on the surface of the electrode layer is transpired by the first thermal energy. By evaporating the ceramic component from the surface of the electrode layer in this manner, a surface containing 40% by volume or more of metal may be formed on the electrode layer.

Next, a metal terminal is arranged at a portion (welded portions 17a, 17b) having a surface containing 40% or more of the metal of the electrode layer. Subsequently, a second heat energy larger than the first heat energy is applied from the metal terminal side to join the metal terminals to the surface of the conductive honeycomb structure.

The laser output in the above-described laser irradiation in the preceding stage can be, for example, 20 to 100 W/mm ² , depending on the material of the electrode layer. Also, the laser output in the subsequent laser irradiation can be, for example, 150 to 400 W/mm ² , depending on the material and thickness of the metal terminal.

In general, when a honeycomb structure and a metal terminal are welded by laser irradiation, if the amount of metal contained on the honeycomb structure side is small, the surface that fuses with the metal terminal decreases. As a result, there arises a problem that the honeycomb structure and the metal terminals are not well bonded. In contrast, according to the welding method shown in the embodiment of the present invention, the metal terminal can be joined after increasing the metal content of the surface on the honeycomb structure side. For this reason, in the honeycomb structure, it is possible to secure a surface that fuses with the metal terminal and to suppress the difference in thermal expansion between the honeycomb structure and the metal terminal. Therefore, it is possible to satisfactorily bond the metal terminal and the honeycomb structure and suppress the occurrence of cracks. As a result, it is possible to provide an electrically heated carrier with good bonding reliability between the metal terminal and the honeycomb structure.

<Embodiment 2>
FIG. 4 is a schematic cross-sectional view perpendicular to the cell extension direction of the electrically heated carrier 40 in Embodiment 2 of the present invention. As shown in FIG. 4, in the electrically heated carrier 40 according to the second embodiment of the present invention, in addition to the electrically heated carrier 20 shown in the first embodiment, between the electrode layers 14a, 14b and the metal terminals 21a, 21b, In addition, a pair of welding base layers 16a and 16b made of conductive ceramics are provided so as to face each other across the central axis of the columnar honeycomb structure. A pair of weld substrate layers 16a, 16b are provided with weld sites 17a, 17b. In Embodiment 2, the welded parts 17a, 17b have surfaces containing 40% by volume or more of metal.

The welding underlayers 16a and 16b serve as underlayers for laser welding when joining with the metal terminals 21a and 21b, and preferably have a function as a stress relaxation layer. That is, if there is a large difference in coefficient of linear expansion between the electrode layers 14a, 14b and the metal terminals 21a, 21b, cracks may occur in the electrode layers 14a, 14b due to thermal stress. Therefore, it is preferable that the welding base layers 16a and 16b have a function of relaxing the thermal stress caused by the difference in linear expansion coefficient between the electrode layers 14a and 14b and the metal terminals 21a and 21b. This makes it possible to suppress the occurrence of cracks in the electrode layers 14a and 14b when welding the metal terminals 21a and 21b to the electrode layers 14a and 14b and due to repeated fatigue of thermal cycles.

A composite material (cermet) of metal and conductive ceramics can be used as the material of the welding base layers 16a and 16b. 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. 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 silicon metal and silicon carbide is preferred as the material for the welding base layers 16a and 16b. It is preferable because it can be fired at the same time as the honeycomb structure, which contributes to simplification of the manufacturing process.

In Embodiment 1, an unfired honeycomb structure body with an electrode layer forming paste was manufactured, and fired to manufacture a conductive honeycomb structure. In Embodiment 2, at this time, a welding base layer forming paste is also formed at the same time, an unfired honeycomb structure portion with a welding base layer forming paste and an electrode layer forming paste is produced, and a conductive honeycomb structure is obtained by firing the unfired honeycomb structure portion. You can make a body.

Further, in Embodiment 2, a pair of metal terminals are welded to the surface of the welding base layer of the conductive honeycomb structure. The welding method can be the same as in Embodiment 1, and the laser irradiation is performed twice in total by dividing the front stage and the rear stage. Specifically, first, as shown in FIG. 5, a first thermal energy is applied to the surfaces of the welding base layers 16a and 16b by a laser 30 to form surfaces containing 40% by volume or more of metal. At this time, the columnar honeycomb structure portion 11 is composed of ceramics having a melting point of 1600° C. or less and metal, and then the first thermal energy is applied to the surfaces of the welding base layers 16a and 16b to evaporate the ceramic components. , a surface containing 40% by volume or more of metal may be formed. Next, metal terminals are arranged at the sites (welded sites 17a and 17b) having surfaces containing 40% by volume or more of metal. Subsequently, a second heat energy larger than the first heat energy is applied from the metal terminal side to join the metal terminals to the surface of the conductive honeycomb structure. With such a welding method, the metal terminal can be joined after increasing the metal content of the surface on the side of the conductive honeycomb structure. Therefore, similarly to the first embodiment, it is possible to satisfactorily bond the metal terminal and the conductive honeycomb structure and suppress the occurrence of cracks. As a result, it is possible to provide an electrically heated carrier having good bonding reliability between the metal terminal and the conductive honeycomb structure.

<Embodiment 3>
FIG. 6 is a schematic cross-sectional view perpendicular to the cell extension direction of the electrically heated carrier 50 according to Embodiment 3 of the present invention. As shown in FIG. 6, an electrically heated carrier 50 according to the third embodiment of the present invention has a configuration in which the electrode layers 14a and 14b are not provided in contrast to the electrically heated carrier 40 shown in the second embodiment. A pair of weld substrate layers 16a, 16b are provided with weld sites 17a, 17b. In Embodiment 3, the welded portions 17a, 17b have surfaces containing 40% by volume or more of metal.

In Embodiment 1, an unfired honeycomb structure body with an electrode layer forming paste was manufactured, and fired to manufacture a conductive honeycomb structure. In Embodiment 3, at this time, an unfired honeycomb structure portion with a welding base layer forming paste is manufactured without forming an electrode layer forming paste, and then fired to manufacture a conductive honeycomb structure.

Further, in Embodiment 3, a pair of metal terminals are welded to the surface of the welding base layer of the conductive honeycomb structure. The welding method can be the same as in Embodiment 1, and the laser irradiation is performed twice in total by dividing the front stage and the rear stage. Specifically, first, as shown in FIG. 7, a first thermal energy is applied to the surfaces of the welding base layers 16a and 16b by a laser 30 to form surfaces containing 40% by volume or more of metal. At this time, the columnar honeycomb structure portion 11 is composed of ceramics having a melting point of 1600° C. or less and metal, and then the first thermal energy is applied to the surfaces of the welding base layers 16a and 16b to evaporate the ceramic components. , a surface containing 40% by volume or more of metal may be formed. Next, metal terminals are arranged at the sites (welded sites 17a and 17b) having surfaces containing 40% by volume or more of metal. Thereafter, metal terminals are joined to the conductive honeycomb structure by the same steps as in the second embodiment. By such a welding method, it is possible to provide an electrically heated carrier having good bonding reliability between the metal terminal and the conductive honeycomb structure.

<Embodiment 4>
FIG. 8 is a schematic cross-sectional view perpendicular to the cell extension direction of the electrically heated carrier 60 in Embodiment 4 of the present invention. As shown in FIG. 8, an electrically heated carrier 60 according to Embodiment 4 of the present invention has a configuration in which welding base layers 16a and 16b are not provided in contrast to the electrically heated carrier 50 shown in Embodiment 3. . The columnar honeycomb structure portion 11 has welded portions 17a and 17b. In Embodiment 4, the columnar honeycomb structure portion 11 has a surface containing 40% by volume or more of metal.

In Embodiment 1, an unfired honeycomb structure body with an electrode layer forming paste was manufactured, and fired to manufacture a conductive honeycomb structure. In Embodiment 4, at this time, the electrode layer forming paste is not formed, only the unfired honeycomb structure portion is manufactured, and the unfired honeycomb structure portion is fired to manufacture the conductive honeycomb structure.

Further, in Embodiment 4, a pair of metal terminals are welded to the surface of the honeycomb structure portion of the conductive honeycomb structure. The welding method can be the same as in Embodiment 1, and the laser irradiation is performed twice in total by dividing the front stage and the rear stage. Specifically, first, as shown in FIG. 9, a first thermal energy is applied to the surface of the columnar honeycomb structure 11 by a laser 30 to form a surface containing 40% by volume or more of metal. At this time, the columnar honeycomb structure portion 11 is composed of ceramics having a melting point of 1600° C. or less and metal, and then the first thermal energy is applied to evaporate the ceramic component, thereby containing 40% by volume or more of the metal. A surface may be formed. Next, metal terminals are arranged at the sites (welded sites 17a and 17b) having surfaces containing 40% by volume or more of metal. Thereafter, metal terminals are joined to the conductive honeycomb structure by the same steps as in the second embodiment. By such a welding method, it is possible to provide an electrically heated carrier having good bonding reliability between the metal terminal and the conductive honeycomb structure.

(3. Exhaust gas purification device)
The electrically heated carrier according to each embodiment of the present invention described above can be used in an exhaust gas purifier. The exhaust gas purifier has an electrically heated carrier and a can holding the electrically heated carrier. In the exhaust gas purifier, the electrically heated carrier is installed in the middle of the exhaust gas flow path through which the exhaust gas from the engine flows. As the can body, a metallic cylindrical member or the like for accommodating the electrically heated carrier can be used.

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

<Example 1>
(1. Preparation of cylindrical 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 grid-like die structure to obtain a cylindrical honeycomb molded body in which each cell has a square shape in a cross section perpendicular to the flow direction of the cells. Ta. This honeycomb molded body was dried by high-frequency dielectric heating, 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 dried honeycomb body.

(3. Preparation of electrode layer forming paste)
Tantalum silicide (TaSi ₂ ) powder, metal silicon (Si) powder, silicon carbide (SiC) powder, methyl cellulose, glycerin, and water were mixed in a rotation-revolution stirrer to prepare a first electrode layer forming paste. The TaSi ₂ powder, Si powder, and SiC powder were blended in a volume ratio of TaSi ₂ powder:Si powder:SiC powder=50:30:20. Further, when the total of TaSi ₂ powder, 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 tantalum silicide powder was 7 μm. 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. Preparation of welding base layer forming paste)
Chromium silicide (CrSi ₂ ) powder, metallic silicon (Si) powder, methyl cellulose, glycerin, and water were mixed with a rotation-revolution stirrer to prepare a welding base layer forming paste. Here, the CrSi ₂ powder and the Si powder were blended in a volume ratio of CrSi ₂ powder:Si powder=90:10. Further, when the total of CrSi ₂ powder and Si 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 chromium silicide powder was 7 μm. The average particle size of the metallic silicon powder was 6 μm.

(5. Application of paste)
The above-mentioned electrode layer forming paste was applied onto the outer surface of the outer peripheral wall of the above-mentioned dried honeycomb body at two locations facing each other across the central axis. Each coated portion was formed in a band shape over the entire length between both bottom surfaces of the dried honeycomb body. Next, the welding base layer forming paste was applied only to the area required for welding the metal terminal so as to partially cover the applied portion of the electrode layer forming paste. The dried honeycomb body after applying the electrode layer forming paste and the welding base layer forming paste was dried at 120° C. to obtain an unfired honeycomb structure with the electrode layer forming paste and the welding base layer forming paste.

(6. Firing)
Next, the unfired honeycomb structure portion with the electrode layer forming paste and the welding base layer forming paste was degreased at 550° C. for 3 hours in an air atmosphere. Next, the unfired honeycomb structure portion with the degreased electrode layer forming paste and welding base layer forming paste was fired and oxidized to produce a honeycomb structure. Firing was performed in an argon atmosphere at 1450° C. for 2 hours. The oxidation treatment was performed in the air at 1300° C. for 1 hour.

The honeycomb structure had a circular bottom surface with a diameter of 100 mm and a height (the length of the cells in the direction of the flow path) of 100 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 size was 8.6 μm. The thickness of the electrode layer was 0.3 mm, and the thickness of the welding base layer was 0.2 mm. When the electrical resistivity at 400° C. was measured by the four-probe method using a test piece of the same material as the honeycomb structure part, the electrode layer, and the welding base layer, it was 5 Ωcm, 0.01 Ωcm, and 0.001 Ωcm, respectively.

(7. Welding of metal terminals)
Using a fiber laser welder, the surface of the weld base layer of the honeycomb structure obtained under the above manufacturing conditions was subjected to laser irradiation in the previous stage. At this time, the laser output was set to 80 W/mm ² . Next, a plate-like metal terminal made of SUS and having a thickness of 0.4 mm was arranged at the location where the previous laser irradiation was performed. Subsequently, the plate-shaped metal terminal was subjected to subsequent laser irradiation using a fiber laser welding machine. At this time, the laser output of the preceding laser irradiation was set to 50 W/mm ² and the laser spot diameter was set to 4.0 mm. The laser output of the laser irradiation in the latter stage was set to 300 W/mm ² and the laser spot diameter was set to 1.0 mm. In this manner, the SUS plate-shaped metal terminal was joined to the welding base layer of the honeycomb structure.

<Examples 2 and 3>
A sample was prepared as in Example 2 in the same manner as in Example 1, except that the laser output in the preceding laser irradiation was 60 W/mm ² .
A sample was prepared in the same manner as in Example 1 except that the metal ratio of the welding base layer was 35% by volume.

<Comparative Examples 1 and 2>
A sample was prepared as Comparative Example 1 in the same manner as in Example 1, except that the laser irradiation in the previous stage was not performed.
A sample was prepared in the same manner as in Comparative Example 1 except that the metal ratio of the welding base layer was 50% by volume.

(8. Volume ratio of metal in welded part)
For each sample of Examples and Comparative Examples, the following method was used to evaluate the volume percentage of the surface containing the metal at the welded portion of the weld base layer to the metal terminal. That is, for each sample of the example, a SEM image was obtained with a scanning electron microscope (SEM) of the welded portion of the weld base layer to the metal terminal. The SEM image was binarized, and the metal ratio was measured for a portion with a depth of 0.05 to 5 mm where the welding base layer was welded to the metal terminal.

(9. Presence or absence of cracks during welding)
It was investigated with a magnifying glass at a magnification of 40 whether or not cracks were generated in the vicinity of the welding site of the honeycomb structure when the metal terminals were welded under the above conditions. A case where no crack occurred was evaluated as "none", and a case where a crack occurred was evaluated as "cracked". In Examples 1 to 3 and Comparative Example 1, cracks did not occur, but in the honeycomb structure portion of Comparative Example 2, cracks occurred.

(10. Bond strength test)
When the metal terminals welded under the above conditions were peeled off in accordance with the peel test of JIS Z3144:2013, all welded portions were examined for peeled portions. For each sample, if the peeling of all the welded parts is accompanied by the destruction of the honeycomb structure part, the electrode layer, or the weld base layer, it is judged that the bonding strength at the interface between the metal terminal and the weld base layer is high. OK." On the other hand, if the detachment does not involve destruction of the honeycomb structure, the electrode layer, or the underweld layer, and if even one welded portion occurs at the interface between the metal terminal and the underweld layer, the metal terminal and the underweld layer It was determined that the bonding strength at the interface between was low, and it was set as "NG".
The evaluation results are shown in Table 1.

(11. Comprehensive evaluation)
If no cracks were generated in the above tests 9 and 10 and the judgment of the bonding strength test was "OK", the overall evaluation was "A". On the other hand, when at least one of cracks occurred and the bonding strength test judgment was "NG", the overall evaluation was "C". Comprehensive evaluation "A" is a level at which the effect of the present invention is obtained, and comprehensive evaluation "C" is a level at which the effect of the present invention is not obtained.

(12. Consideration)
In Examples 1 to 3, the difference in thermal expansion from the honeycomb structure portion was reduced by lowering the metal ratio of the welding base layer, and breakage of the honeycomb structure portion during firing was suppressed. Furthermore, by increasing the metal ratio of the welding part, the metal ratio that is joined at the time of welding also increases, making welding possible. As a result, when the bonding strength test was performed, the electrode layer with the lowest strength was broken.
In Comparative Example 1, since the metal ratio of the welded portion was low, the metal ratio joined during welding was not sufficient, and the welding could not be performed well.
In Comparative Example 2, the metal ratio of the welding base layer was greater than 40%, and the difference in thermal expansion from that of the honeycomb structure became large, and the honeycomb structure broke during firing and cracks occurred.

REFERENCE SIGNS LIST 10 honeycomb structure 11 columnar honeycomb structure portion 12 outer wall 13 partition walls 14a, 14b electrode layer 15 cells 16a, 16b welding base layers 17a, 17b welding sites 20, 40, 50, 60 electrically heated carriers 21a, 21b metal terminal 30 laser

Claims (7)

a columnar honeycomb structure having an outer peripheral wall and porous partition walls disposed inside the outer peripheral wall and partitioning and forming a plurality of cells penetrating from one end surface to the other end surface to form a flow path; a conductive honeycomb structure comprising
a pair of metal terminals arranged to face each other across the central axis of the columnar honeycomb structure and joined to the surface of the conductive honeycomb structure via a welding site;
with
The honeycomb structure includes a welding base layer composed of a pair of ceramics and a metal arranged on the surface of the outer peripheral wall of the columnar honeycomb structure so as to face each other across the central axis of the columnar honeycomb structure. has
the pair of weld substrate layers comprising the weld site;
An electrode layer made of ceramics and metal is provided between the outer peripheral wall and the welding base layer,
The weld base layer other than the welded portion is composed of ceramics and metal, and contains 40% by volume or less of metal,
The electrically heated carrier, wherein the welded portion of the honeycomb structure has a surface containing 50 % by volume or more of the metal. 2. The electrically heated carrier according to claim 1, wherein the depth of the surface containing 50 % by volume or more of the metal in the welded portion of the honeycomb structure is 0.05 to 5 mm. 3. The electrically heated carrier according to claim 1, wherein the entire welded portion of the honeycomb structure is a surface containing 50 % by volume or more of the metal. 4. The electrically heated carrier according to any one of claims 1 to 3 , having a plurality of said welding sites. The electrically heated carrier according to any one of claims 1 to 4 ;
a can body holding the electrically heated carrier;
An exhaust gas purification device having and a porous partition wall disposed inside the outer peripheral wall and partitioning and forming a plurality of cells forming a flow path penetrating from one end face to the other end face, and comprising a ceramic and a metal A conductive honeycomb structure having a columnar honeycomb structure composed of
a pair of metal terminals arranged to face each other across the central axis of the columnar honeycomb structure;
A method for producing an electrically heated carrier comprising
A step of applying a first thermal energy to the surface of the honeycomb structure to melt the metal on the surface, thereby aggregating the metal on the surface and forming a surface containing 50% by volume or more of the metal. and,
The metal terminal is arranged in a portion of the honeycomb structure having a surface containing 50% by volume or more of the metal, and a second thermal energy larger than the first thermal energy is applied to the metal terminal to obtain the honeycomb structure. bonding the metal terminal to the surface of the body;
A method for producing an electrically heated carrier comprising: It has an outer peripheral wall, and a porous partition wall that is disposed inside the outer peripheral wall and partitions and forms a plurality of cells that penetrate from one end surface to the other end surface to form a flow path, and has a melting point of 1600. a conductive honeycomb structure having a columnar honeycomb structure composed of ceramics with a temperature of ℃ or less and metal;
a pair of metal terminals arranged to face each other across the central axis of the columnar honeycomb structure;
A method for producing an electrically heated carrier comprising
a step of applying a first thermal energy to the surface of the honeycomb structure to transpire at least part of the ceramics to form a surface containing 50% by volume or more of the metal;
The metal terminal is arranged in a portion of the honeycomb structure having a surface containing 50% by volume or more of the metal, and a second thermal energy larger than the first thermal energy is applied to the metal terminal to obtain the honeycomb structure. bonding the metal terminal to the surface of the body;
A method for producing an electrically heated carrier comprising:

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