Honeycomb structure, electrically heated carrier, and exhaust gas purification device

Abstract

Provided is a honeycomb structure having excellent thermal shock resistance, an electrically heated carrier, and an exhaust gas purification device. The honeycomb structure includes a honeycomb structure portion having a peripheral wall and a partition wall disposed on the inner side of the peripheral wall and dividing a plurality of cells that form flow paths extending from one end face to the other end face. A slit is provided in the peripheral wall and / or the cells. The slit includes a filler material layer composed of a filler material. The filler material layer has pores, and pores having a diameter of 90 μm or more account for 30% or more by volume relative to all of the pores included in the filler material layer.

Description

TECHNICAL FIELD

[0001] The present application relates to a honeycomb structure, an electrically heated carrier, and an exhaust gas purification device. BACKGROUND

[0002] In recent years, in order to improve the exhaust gas purification performance after engine start, an electrically heated catalyst (EHC) has been proposed. The EHC is formed so that, for example, a metal electrode is connected to a columnar honeycomb structure formed of an electrically conductive ceramic, and the honeycomb structure itself is heated by electric conduction, whereby it can be warmed up to the active temperature of the catalyst before engine start.

[0003] The EHC is subjected to heat and impact from the engine, and thus is required to have good thermal shock resistance. If cracking occurs in the honeycomb structure of the EHC due to heat and impact from the engine, the electric conduction path in the honeycomb structure changes, resulting in local heating, and thus the catalyst deteriorates. In addition, the electric conduction resistance rises, and the electric conduction control becomes difficult. As a result, the exhaust gas purification efficiency of the EHC can deteriorate.

[0004] It is known that, in order to suppress cracking of the honeycomb structure of the EHC, a slit for stress relaxation is formed in the honeycomb structure. In addition, a technique of filling a filler material in the slit for stress relaxation of the honeycomb structure is disclosed in Patent Literature 1.

[0005] PRIOR ART DOCUMENTS

[0006] Patent Literature 1: Japanese Patent Application Laid-Open No. 2015-174011 SUMMARY

[0007] Then, the present inventors conducted research, and as a result, it was found that if the Young's modulus of the filler material filled in the slit is too high, deformation is difficult to occur at the slit for stress relaxation. As a result of this, it was found that sometimes the stress generated at a portion other than the slit becomes too large, resulting in cracking of the honeycomb structure of the EHC, and thus there is room for improvement.

[0008] The present application was made in view of the above-described circumstances, and its object is to provide a honeycomb structure, an electrically heated carrier, and an exhaust gas purification device that have good thermal shock resistance.

[0009] The above-described object is solved by the present application as defined below.

[0010] (1) A honeycomb structure, wherein,

[0011] comprises a honeycomb structure portion having an outer peripheral wall and a partition wall provided on the inner side of the outer peripheral wall and dividing a plurality of cells that form flow paths extending from one end face to the other end face,

[0012] a slit is provided in the outer peripheral wall and / or the cell, the slit including a filler material layer composed of a filler material,

[0013] the filler material layer has pores, and pores having a diameter of 90 μm or more account for 30% or more by volume with respect to all the pores included in the filler material layer.

[0014] (2) The honeycomb structure according to (1), wherein the honeycomb structure further has a pair of electrode layers provided on the outer surface of the outer peripheral wall in a manner that extends in a strip shape along the flow path direction of the cells, sandwiching the central axis of the honeycomb structure.

[0015] (3) An electrically heated carrier, wherein:

[0016] (2) The honeycomb structure according to (1); and

[0017] a metal electrode electrically connected to the electrode layer of the honeycomb structure.

[0018] (4) An exhaust gas purification device, wherein:

[0019] (3) The electrically heated carrier according to (1); and

[0020] a cylindrical member made of metal for holding the electrically heated carrier.

[0021] Effects of Invention

[0022] According to the present application, it is possible to provide a honeycomb structure, an electrically heated carrier, and an exhaust gas purification device, each of which has good thermal shock resistance. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a schematic view of the appearance of a honeycomb structure in an embodiment of the present application.

[0024] Figure 2 in which (A) to (H) are schematic views of the planar end surface of a honeycomb structure in an embodiment of the present application, on which a slit is formed.

[0025] Figure 3 is a schematic view of a cross section perpendicular to the flow path direction of the cells of an electrically heated carrier in an embodiment of the present application.

[0026] Explanation of Symbols

[0027] 10…honeycomb structure, 11…honeycomb structure portion, 12…outer peripheral wall, 13a, 13b…electrode layer, 18…cell, 19…partition wall, 21…slit 25…filling material layer, 30…electrically heated carrier, 33a, 33b…metal electrode. DETAILED DESCRIPTION

[0028] Next, the scheme for carrying out the present application will be explained in detail with reference to the drawings. The present application is not limited to the following embodiments, and it should be understood that modifications, improvements, etc. can be made based on the common knowledge of those skilled in the art without departing from the gist of the present application.

[0029] (1. Honeycomb structure)

[0030] Figure 1 is a schematic view of the outer appearance of the honeycomb structure 10 in the embodiments of the present application. The honeycomb structure 10 is provided with a honeycomb structure portion 11 and electrode layers 13a, 13b. Note that the honeycomb structure 10 can not be provided with the electrode layers 13a, 13b.

[0031] (1-1. Honeycomb structure portion)

[0032] The honeycomb structure portion 11 is a columnar member having an outer peripheral wall 12 and a partition wall 19 disposed on the inner side of the outer peripheral wall 12 and dividing a plurality of cells 18 that form flow paths extending from one end surface to the other end surface. The columnar shape can be understood as a three-dimensional shape having a thickness in the flow path direction of the cells 18 (axial direction of the honeycomb structure portion 11). The ratio of the axial length of the honeycomb structure portion 11 to the diameter or width of the end surface (aspect ratio) is arbitrary. The columnar shape can also include a shape in which the axial length of the honeycomb structure portion 11 is shorter than the diameter or width of the end surface (flat shape).

[0033] The outer shape of the honeycomb structure portion 11 can be columnar, and is not particularly limited, and for example, a columnar shape in which the end surface is circular (cylindrical shape), a columnar shape in which the end surface is elliptical, a columnar shape in which the end surface is polygonal (quadrilateral, pentagonal, hexagonal, heptagonal, octagonal, etc.), or the like can be adopted. In addition, regarding the size of the honeycomb structure portion 11, the area of the end surface is preferably 2000 to 20000 mm 2 , and more preferably 5000 to 15000 mm 2

[0034] The honeycomb structure 11 is made of ceramic and has electrical conductivity. The honeycomb structure 11 having electrical conductivity can generate heat by Joule heat upon application of electric current, and the ceramic has no particular limitation in volume resistivity, and is preferably 0.1 to 200 Ωcm, and more preferably 1 to 200 Ωcm. In the present application, the volume resistivity of the honeycomb structure 11 is a value measured at 25°C using a four-terminal method.

[0035] The material of the honeycomb structure 11 is not limited, and can be selected from the group consisting of oxide-based ceramics such as alumina, mullite, zirconia, and cordierite, non-oxide-based ceramics such as silicon carbide, silicon nitride, and aluminum nitride, and the like. In addition, silicon carbide-metal silicon composite materials, silicon carbide / graphite composite materials, and the like can also be used. Among these, from the viewpoint of combining heat resistance and electrical conductivity, the material of the honeycomb structure 11 preferably contains ceramic in which silicon-silicon carbide composite material or silicon carbide is the main component. When the material of the honeycomb structure 11 contains silicon-silicon carbide composite material as the main component, it means that the honeycomb structure 11 contains 90% by mass or more of silicon-silicon carbide composite material (total mass) in the entire honeycomb structure 11. Here, the silicon-silicon carbide composite material contains silicon carbide particles as aggregate and silicon as a binder material that binds the silicon carbide particles, and preferably a plurality of silicon carbide particles are bound together by silicon in a manner that forms fine pores between the silicon carbide particles. When the material of the honeycomb structure 11 contains silicon carbide as the main component, it means that the honeycomb structure 11 contains 90% by mass or more of silicon carbide (total mass) in the entire honeycomb structure 11.

[0036] When the honeycomb structure 11 contains silicon-silicon carbide composite material, the ratio of the "mass of silicon as a binder material" contained in the honeycomb structure 11 to the "mass of silicon carbide particles as aggregate" contained in the honeycomb structure 11 with respect to the total of the "mass of silicon as a binder material" contained in the honeycomb structure 11 is preferably 10 to 40% by mass, and more preferably 15 to 35% by mass.

[0037] The shape of the cells in the cross section perpendicular to the flow path direction of the cells 18 is not limited, and is preferably a quadrilateral, a hexagon, an octagon, or a combination of these shapes. Among these, from the viewpoint of easily combining structural strength and uniform heating, a quadrilateral and a hexagon are preferable.

[0038] The thickness of the partition wall 19 that forms the cells 18 is preferably 0.1 to 0.3 mm, and more preferably 0.1 to 0.2 mm. In the present application, the thickness of the partition wall 19 is defined as the length of the portion passing through the partition wall 19 in the line segment connecting the centers of gravity of the adjacent cells 18 to each other in the cross section perpendicular to the flow path direction of the cells 18.

[0039] As for the honeycomb structure portion 11, the cell density in a cross section perpendicular to the flow path direction of the cells 18 is preferably 40 to 150 cells / cm 2 More preferably, 70 to 100 cells / cm 2 By making the cell density within this range, it is possible to improve the purification performance of the catalyst while reducing the pressure loss when the exhaust gas flows. The cell density is the number of cells divided by the area of one end surface portion of the honeycomb structure portion 11 excluding the outer peripheral wall 12 portion.

[0040] It is useful to provide the outer peripheral wall 12 of the honeycomb structure portion 11 from the viewpoint of ensuring the structural strength of the honeycomb structure portion 11 and, moreover, suppressing leakage of the fluid flowing through the cells 18 from the outer peripheral wall 12. Specifically, the thickness of the outer peripheral wall 12 is preferably 0.1 mm or more, more preferably 0.15 mm or more, and further preferably 0.2 mm or more. However, if the outer peripheral wall 12 is made too thick, the strength becomes too high, and the strength balance with the partition walls 19 is lost, resulting in a decrease in thermal shock resistance. In this regard, the thickness of the outer peripheral wall 12 is preferably 1.0 mm or less, more preferably 0.7 mm or less, and further preferably 0.5 mm or less. Here, the thickness of the outer peripheral wall 12 is defined as the thickness in the normal direction with respect to the tangent line of the outer peripheral wall 12 at the portion of the outer peripheral wall 12 to be measured when the portion is observed in a cross section perpendicular to the flow path direction of the cells.

[0041] The partition wall 19 can be porous. In the case of being porous, the porosity of the partition wall 19 is preferably 35 to 60%, and more preferably 35 to 45%. The porosity is a value measured using a mercury porosimeter.

[0042] The average pore diameter of the partition wall 19 of the honeycomb structure portion 11 is preferably 2 to 15 μm, and more preferably 4 to 8 μm. The average pore diameter is a value measured using a mercury porosimeter.

[0043] (1-2. Electrode layer)

[0044] A pair of electrode layers 13a, 13b are provided on the outer surface of the outer peripheral wall 12 so as to extend in a band shape along the flow path direction of the cells 18, sandwiching the central axis of the honeycomb structure portion 11. By providing a pair of electrode layers 13a, 13b in this way, it is possible to improve the uniform heating property of the honeycomb structure portion 11. From the viewpoint that the current easily spreads in the axial direction of the electrode layers 13a, 13b, the electrode layers 13a, 13b are preferably extended over 80% or more of the length between the two end surfaces of the honeycomb structure portion 11, preferably 90% or more of the length, and more preferably the entire length.

[0045] The thickness of the electrode layers 13a, 13b is preferably 0.01 to 5 mm, more preferably 0.01 to 3 mm. By being in this range, the uniform heat generation property can be improved. The thickness of the electrode layers 13a, 13b is defined as the thickness in the normal direction to the tangent line at the measurement site of the outer surface of the electrode layers 13a, 13b when the measurement site of the thickness is observed in the cross section perpendicular to the flow path direction of the cells 18.

[0046] By making the volume resistivity of the electrode layers 13a, 13b lower than the volume resistivity of the honeycomb structure portion 11, the current is made to easily flow preferentially to the electrode layers 13a, 13b, and the current is made to easily spread in the flow path direction and the circumferential direction of the cells 18 at the time of energization. The volume resistivity of the electrode layers 13a, 13b is preferably 1 / 10 or less, more preferably 1 / 20 or less, and further preferably 1 / 30 or less of the volume resistivity of the honeycomb structure portion 11. However, if the volume resistivities of the two are too different, the current is concentrated between the end portions of the opposing electrode layers, and the heat generation of the honeycomb structure portion 11 is biased in this regard, so the volume resistivity of the electrode layers 13a, 13b is preferably 1 / 200 or more, more preferably 1 / 150 or more, and further preferably 1 / 100 or more of the volume resistivity of the honeycomb structure portion 11. In the present application, the volume resistivity of the electrode layers 13a, 13b is the value measured at 25°C using the four-terminal method.

[0047] The material of the electrode layers 13a, 13b can use an electrically conductive ceramic, a metal, or a composite material of a metal and an electrically conductive ceramic (cermet). As the metal, for example, a metal element of Cr, Fe, Co, Ni, Si, or Ti, or an alloy containing at least one metal selected from the group consisting of these metals can be given. As the electrically conductive ceramic, there is no limitation, and silicon carbide (SiC) can be given, and metal compounds such as metal silicides such as tantalum silicide (TaSi2) and chromium silicide (CrSi2) can also be given. As a specific example of the composite material of a metal and an electrically conductive ceramic (cermet), a composite material of metal silicon and silicon carbide, a composite material of metal silicides such as tantalum silicide, chromium silicide, and metal silicon, and silicon carbide, and further, from the viewpoint of reducing thermal expansion, a composite material obtained by adding one or two or more of an insulating ceramic such as alumina, mullite, zirconia, cordierite, silicon nitride, and aluminum nitride to one or two or more of the above-described metals can be given. As the material of the electrode layers 13a, 13b, from the reason that it is possible to simultaneously sinter with the honeycomb structure portion 11 and contribute to simplifying the manufacturing process, among the above-described various metals and electrically conductive ceramics, a combination of metal silicides such as tantalum silicide and chromium silicide, and a composite material of metal silicon and silicon carbide is preferably used.

[0048] (1-3. Slits)

[0049] The slit 21 is provided in the honeycomb structure 10, and the slit 21 includes a filler material layer 25 composed of a filler material. The slit 21 can be provided only in the peripheral wall 12 of the honeycomb structure 10, only in the cells 18, or in both the peripheral wall 12 and the cells 18. Note that providing the slit 21 in the cells 18 means that a portion of the partition wall that demarcates the cells is missing. Further, the slit 21 is formed on the outer surface of the peripheral wall 12 of the honeycomb structure 11, and can be a slit extending in a direction parallel to the axial direction of the honeycomb structure 10, a slit formed in at least one end surface of the honeycomb structure 11 (a cell of the end surface), or both. Furthermore, as shown in Figure 1

[0050] The shape and number of the slit 21 in the end surface of the honeycomb structure 10 are not particularly limited and can be appropriately designed. For example, in the end surface of the honeycomb structure 10, the slit 21 can be one, two or more, and can be formed so as not to intersect each other or so as to intersect at least a portion thereof. Further, the length and width of the slit 21 in the end surface of the honeycomb structure 10 are not particularly limited. The width of the slit 21 in the end surface of the honeycomb structure 10 can be formed to be the same degree as the width of the cell 18, or the width of the slit 21 can be formed to be smaller or larger than the width of the cell 18. The length of each slit 21 in the end surface of the honeycomb structure 10 is not particularly limited and can be 2 to 80 cells. The width of each slit 21 is not particularly limited and can be 1 to 5 cells. The length and width of each slit 21 in the end surface of the honeycomb structure 10 can be appropriately designed depending on the size, material, use, and number of slits 21 of the honeycomb structure 10.

[0051] The slit 21 can be provided so as to be divided in the extension direction of the slit 21 in the end surface of the honeycomb structure 10. At this time, in the end surface of the honeycomb structure 10, the slit can be divided into slits of the same length, or can be divided into slits of different lengths. By forming the slit 21 so as to be divided in the end surface of the honeycomb structure 10, it is possible to more effectively control cracking of the honeycomb structure 10. The number of divisions of the slit 21 is not particularly limited and can be formed to be divided into two, three, or four or more. Further, a plurality of slits obtained by mixing the slit formed to be divided and the slit not formed to be divided can be provided.

[0052] Figure 1 A case in which the slit 21 in the end surface of the honeycomb structure 10 is one is schematically shown in FIG. 12. The slit 21 can be formed so as to be divided in the end surface of the honeycomb structure 10.​Figure 1 The slits 21 can extend through the center of the end face of the honeycomb structure 10, or can not pass through the center. Also, in the Figure 2 Specific examples of the configuration in which the plurality of slits 21 are formed are shown in (A) to (H). Note that, Figure 2 The outer diameter of one end face of the honeycomb structure 10 and the shape of the slits 21 are shown only schematically in (A) to (H). Also, the configuration in one end face of the honeycomb structure 10 is shown, and these slits 21 can be formed only in one end face of the honeycomb structure 10, or can maintain the same configuration in the cross section of the honeycomb structure 10 and be formed so as to extend along the axial direction and pass through to the other end face of the honeycomb structure 10.

[0053] The slits 21 can be, as shown in Figure 2 As shown in (A), in the end face of the honeycomb structure 10, the slits formed in the cell walls from the outer peripheral wall by the amount of the plurality of cells are 3 sets of slits (a total of 6 slits) provided so as to oppose each other with the center of the end face of the honeycomb structure 10 interposed. Also, the slits 21 can be, as shown in Figure 2 As shown in (B), in the end face of the honeycomb structure 10, 3 slits that cross at the center and extend to the outer peripheral walls on both sides, respectively.

[0054] As for the slits 21, as shown in Figure 2 (C), in the end face of the honeycomb structure 10, Figure 2 The 3 slits shown in (B) can be formed so as to each not reach the inner peripheral end of the outer peripheral wall. Also, as shown in Figure 2 (D), Figure 2 The 3 slits shown in (B) can be slits that are each divided along the extension direction.

[0055] The slits 21 can be, as shown in Figure 2 (E), in the end face of the honeycomb structure 10, 3 slits that extend parallel to each other. Also, as shown in Figure 2 (F), Figure 2 The 3 slits shown in (E) can be slits that are each divided along the extension direction.

[0056] As for the slits 21, as shown in Figure 2 (G), in the end face of the honeycomb structure 10, can be 3 slits, and the 3 slits are formed into a substantially triangular shape that does not intersect at the vertex. Also, as shown in Figure 2 (H), can be 4 slits, and the 4 slits are formed into a substantially quadrangular shape that does not intersect at the vertex.

[0057] (1-4. Filler material layer)

[0058] The filler material layer 25 is included in the slit 21. The slit 21 can be filled with the filler material layer 25 entirely, or a part of the slit 21 can be filled with the filler material layer 25. From the viewpoint of the heat shock resistance of the honeycomb structure 10, it is more preferable that the slit 21 be filled with the filler material layer 25 entirely.

[0059] In the case where a plurality of slits 21 are provided, the filler material layer 25 can be included in all of the slits 21, or the filler material layer 25 can be included in only a part of the slits 21. From the viewpoint of the heat shock resistance of the honeycomb structure 10, it is more preferable that the filler material layer 25 be provided in all of the slits 21.

[0060] As the mode in which the filler material layer 25 is included in a part of the slit 21, the slit 21 can be filled with the filler material layer 25 to a prescribed depth from one end surface, or the filler material layer 25 of a prescribed thickness can be provided along the inner wall of the slit 21 from one end surface to the other end surface. In the case where the filler material layer 25 of a prescribed thickness is provided along the inner wall of the slit 21, the thickness of the filler material layer 25 can be adjusted appropriately according to the width of the slit 21, for example, can be 500 to 5000 μm, or can be the width of 1 to 5 cells. In the mode in which the filler material layer 25 is provided from one end surface to the other end surface of the slit 21, the filler material layer 25 also functions as a gas seal material that suppresses the leakage of gas from the slit 21.

[0061] The filler material layer 25 is composed of a filler material. In the case where the main component of the honeycomb structure 11 is silicon carbide or a silicon carbide-metallic silicon composite material, the content of silicon carbide is preferably 20% by mass or more, and more preferably 20 to 70% by mass. According to this, the thermal expansion coefficient of the filler material can be made close to the value of the thermal expansion coefficient of the honeycomb structure 11, and thus the heat shock resistance of the honeycomb structure 10 can be improved. The filler material can contain 30% by mass or more of silica, alumina, or the like. A plurality of filler materials can be used in combination as the filler material that constitutes the filler material layer 25. For example, a plurality of filler materials can be used separately according to the site in one slit 21, or can be used separately among a plurality of slits 21.

[0062] The volume resistivity of the filler material is preferably 100 to 100,000% of the volume resistivity of the honeycomb structure portion 11. Further, the volume resistivity of the filler material is more preferably 200 to 100,000% of the volume resistivity of the honeycomb structure portion 11, and particularly preferably 300 to 100,000%. If the volume resistivity of the filler material is 100% or more of the volume resistivity of the honeycomb structure portion 11, the current is less likely to flow through the filler material, and thus the current can flow uniformly through the honeycomb structure portion 11. Even if the volume resistivity of the filler material is high, there is no particular problem. The filler material can be an insulator. In terms of the volume resistivity of the filler material, 100,000% or so of the volume resistivity of the honeycomb structure portion 11 is practically the upper limit.

[0063] The filler material layer 25 has air pores. The air pore diameter of the air pores contained in the filler material layer 25 is not particularly limited and can be 1 to 500 μm. Of the air pores contained in the filler material layer 25, the air pores having an air pore diameter of 90 μm or more account for 30% or more by volume of all the air pores contained in the filler material layer 25. According to such a configuration, of the air pores contained in the filler material layer 25, the volume ratio of the larger air pores having an air pore diameter of 90 μm or more is large, and cracking is likely to occur in the filler material layer 25 when stress is generated in the honeycomb structure 10. By having the filler material layer 25 have air pores having a large diameter as described above, cracking is actively generated in the filler material layer 25, and thus the Young's modulus of the filler material layer 25 is optimized, the thermal stress generated in the vicinity of the slit 21 at the time of EHC heating is reduced, and the thermal shock resistance of the honeycomb structure 10 is improved. The air pores having an air pore diameter of 90 μm or more are preferably 40% or more by volume of all the air pores contained in the filler material layer 25. The air pores having an air pore diameter of 90 μm or more are more preferably 50% or more by volume of all the air pores contained in the filler material layer 25. Further, since cracking is less likely to occur in the filler material layer 25 in the absence of small air pores smaller than 90 μm, the air pores having an air pore diameter of 90 μm or more are more preferably 90% or less by volume of all the air pores contained in the filler material layer 25.

[0064] The pore diameter (μm) of the pores contained in the filler material layer 25, and the volume ratio (vol%) of the pores having a prescribed pore diameter with respect to the total pores contained in the filler material layer 25 can be measured by cross-sectional observation using an SEM. Specifically, first, a sample is cut out from the honeycomb structure provided with a slit containing the filler material layer in such a manner that the cross section of the filler material layer 25 can be observed. If necessary, the concavities and convexities of the cross section of the filler material layer 25 are filled with a resin, and further, the surface (cross section) is polished and observed. The cross-sectional area of each pore is calculated from the image analysis of the SEM image at a magnification of 100 times obtained from the observation of a region (unit region) of 0.5 mm x 1 mm. Then, the volume of each pore is calculated from the equivalent circle diameter of the cross-sectional area of the pores contained in the unit region, assuming that the pores are spherical. The volume ratio (vol%) of the pores having a prescribed pore diameter with respect to the total pores contained in the filler material layer 25 is calculated using the volume of each pore calculated as described above. Four such unit regions are observed, and the volume ratio of the pores having a prescribed pore diameter is calculated in the same manner, and the average of the four is taken as the volume ratio (vol%) of the pores having a prescribed pore diameter with respect to the total pores contained in the filler material layer 25.

[0065] The porosity of the filler material layer 25 is preferably 20 to 90%. If the porosity of the filler material layer 25 is 90% or less, the strength of the filler material layer 25 is sufficiently maintained, and the function of the filler material layer 25 to suppress gas leakage due to collapse can be suppressed. If the porosity of the filler material layer 25 is 20% or more, the Young's modulus of the filler material layer 25 does not become excessively high, and the stress relaxation function of the slit is sufficiently maintained. The porosity of the filler material layer 25 is more preferably 30 to 85%, and further preferably 45 to 75%. Here, even if the porosity of the filler material layer 25 is the same, as described above, the pore diameter (μm) of the pores contained in the filler material layer 25, and the volume ratio (vol%) of the pores having a prescribed pore diameter with respect to the total pores contained in the filler material layer 25 are not necessarily the same. In the present application, not only the porosity of the filler material layer 25 is controlled, but also the pores having a pore diameter of 90 μm or more contained in the filler material layer 25 are controlled to be 30 vol% or more with respect to the total pores contained in the filler material layer 25, whereby when the EHC generates heat and thermal stress is generated around the slit, the pores having a pore diameter of 90 μm or more dispersed in the filler material layer 25 are dispersed like a needle trace, the filler material layer 25 preferentially cracks, and the stress relaxation function can be exerted.

[0066] The D50 of the pore diameter in the cumulative distribution under the volume basis in the filler material layer 25 is preferably 80 to 500 μm. If the D50 of the pore diameter in the filler material layer 25 is 80 μm or more, when the EHC generates heat and thermal stress is generated around the slit, the pores of 80 μm or more in the filler material layer 25 are dispersed like a needle trace, the filler material layer 25 preferentially cracks, and a stress buffering function can be exerted. If the D50 of the pore diameter in the filler material layer 25 is 500 μm or less, after the filler material layer 25 cracks, the filler material layer 25 is not easily collapsed, and the effect of suppressing gas leakage is maintained. The D50 of the pore diameter in the cumulative distribution under the volume basis in the filler material layer 25 is more preferably 80 to 300 μm, and further preferably 80 to 200 μm. The D50 of the pore diameter in the cumulative distribution under the volume basis in the filler material layer 25 can be measured by cross-sectional observation using a SEM. Specifically, first, a sample is cut out from the honeycomb structure body in which the slit including the filler material layer is provided, in a manner that the cross section of the filler material layer 25 can be observed. If necessary, the concave-convex of the cross section of the filler material layer 25 is buried with a resin, and further, polishing is performed, and the polished surface (cross section) is observed. The cross-sectional area of each pore is calculated based on the image analysis of the SEM image at a magnification of 100 times obtained by observing four regions of 0.5 mm x 1 mm. Then, the equivalent circle diameter calculated from the cross-sectional area is set as the diameter of the pore, and the D50 is calculated from each pore diameter.

[0067] The Young's modulus of the filler material layer 25 is preferably 10 to 1000 MPa. If the Young's modulus of the filler material layer 25 is 10 MPa or more, the mechanical strength of the honeycomb structure body 10 becomes good. If the Young's modulus of the filler material layer 25 is 1000 MPa or less, the thermal shock resistance of the honeycomb structure body 10 becomes better. The Young's modulus of the filler material layer 25 is more preferably 20 to 500 MPa, further preferably 50 to 200 MPa, and particularly preferably 70 to 200 MPa. The Young's modulus of the filler material layer 25 can be calculated from the stress and the deformation at 20 to 50% of the stress load measured by the 4-point bending strength as described in Japanese Patent No. 6259327.

[0068] The Young's modulus of the honeycomb structure portion 11 is preferably 1 to 100 GPa. If the Young's modulus of the honeycomb structure portion 11 is 1 GPa or more, the mechanical strength of the honeycomb structure body 10 becomes good. If the Young's modulus of the honeycomb structure portion 11 is 100 GPa or less, the thermal shock resistance of the honeycomb structure body 10 becomes better. The Young's modulus of the honeycomb structure portion 11 is more preferably 2 to 50 GPa, and further preferably 5 to 20 GPa. The Young's modulus of the honeycomb structure portion 11 can be calculated from the stress and the deformation at 20 to 50% of the stress load measured by the 4-point bending strength.

[0069] (2. Electrically heated carrier)

[0070] Figure 3 Fig. 2 is a schematic view of a cross section of an electrically heated carrier 30 in an embodiment of the present application, taken perpendicular to the flow path direction of the cells. The electrically heated carrier 30 comprises a honeycomb structure 10 and metal electrodes 33a, 33b electrically connected to the electrode layers 13a, 13b of the honeycomb structure 10.

[0071] (2-1. Metal electrodes)

[0072] The metal electrodes 33a, 33b are provided on the electrode layers 13a, 13b of the honeycomb structure 10. The metal electrodes 33a, 33b can be a pair of metal electrodes arranged so that one metal electrode 33a opposes the other metal electrode 33b with the central axis of the honeycomb structure 11 interposed therebetween. If the metal electrodes 33a, 33b are supplied with voltage via the electrode layers 13a, 13b, the metal electrodes 33a, 33b are energized, thereby generating heat in the honeycomb structure 11 by Joule heat. Thus, the electrically heated carrier 30 can also be preferably 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 appropriately changed.

[0073] As the material of the metal electrodes 33a, 33b, any metal can be used without particular limitation, and a metal element and an alloy, etc. can be used. However, from the viewpoint of corrosion resistance, resistivity, and linear expansion rate, for example, an alloy containing at least one selected from the group consisting of Cr, Fe, Co, Ni, and Ti is preferably used, and stainless steel and Fe-Ni alloy are more preferably used. The shape and size of the metal electrodes 33a, 33b are not particularly limited, and can be appropriately designed in accordance with the size and the energization performance of the electrically heated carrier 30, etc.

[0074] By supporting the catalyst on the electrically heatable carrier 30, the electrically heatable carrier 30 can be used as a catalytic converter. For example, a fluid such as automobile exhaust gas can be circulated through the flow paths of the plurality of cells 18 of the honeycomb structure 10. As the catalyst, for example, a noble metal-based catalyst or a catalyst other than the noble metal-based catalyst can be cited. As the noble metal-based catalyst, a three-way catalyst that supports a noble metal such as platinum (Pt), palladium (Pd), rhodium (Rh) on the surface of alumina fine pores and includes a cocatalyst such as ceria, zirconia, an oxidation catalyst, or an NOx storage reduction catalyst (LNT catalyst) that includes an alkali earth metal and platinum as an NOx storage component can be exemplified. As the catalyst that does not use a noble metal, an NOx selective reduction catalyst (SCR catalyst) that includes a copper-exchanged zeolite or an iron-exchanged zeolite, or the like can be exemplified. In addition, two or more kinds of catalysts selected from the group consisting of the above-described catalysts can be used. Note that the method of supporting the catalyst is not particularly limited, and the catalyst can be supported on the honeycomb structure according to a method of supporting a catalyst on a honeycomb structure in the past.

[0075] (3. Method of manufacturing honeycomb structure)

[0076] Next, a method of manufacturing a honeycomb structure according to an embodiment of the present application will be described.

[0077] The method of manufacturing a honeycomb structure according to an embodiment of the present application includes a molding step of manufacturing a honeycomb molded body, a drying step of manufacturing a honeycomb dried body, and a firing step of manufacturing a honeycomb fired body.

[0078] (Molding step)

[0079] In the molding step, first, a molding material containing a ceramic raw material having electrical conductivity is prepared. The molding material is manufactured by adding a silicon metal powder (silicon metal), a binder, a surfactant, a pore-forming material, water, and the like to a silicon carbide powder (silicon carbide). The mass of the silicon metal is preferably 10 to 40% by mass with respect to the total of the mass of the silicon carbide powder and the mass of the silicon metal. The average particle diameter of the silicon carbide particles in the silicon carbide powder is preferably 3 to 50 μm, and more preferably 3 to 40 μm. The average particle diameter of the silicon metal (silicon metal powder) is preferably 2 to 35 μm. The average particle diameter of the silicon carbide particles and the silicon metal (silicon metal particles) refers to the arithmetic average particle diameter on a volume basis when the frequency distribution of the particle size 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 silicon metal particles are fine particles of silicon metal that constitute the silicon metal powder. Note that this is a mixture of the molding material when the material of the honeycomb structure is a silicon-silicon carbide composite material, and in the case where the material is silicon carbide, the silicon metal is not added.

[0080] As the binder, methylcellulose, hydroxypropylmethylcellulose, hydroxypropyloxycellulose, hydroxyethylcellulose, carboxymethylcellulose, polyvinyl alcohol, and the like can be given. Among them, methylcellulose and hydroxypropyloxycellulose are preferably used in combination. 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 silicon metal powder is 100 parts by mass.

[0081] The content of the water is preferably 20 to 60 parts by mass when the total mass of the silicon carbide powder and the silicon metal powder is 100 parts by mass.

[0082] As the surfactant, ethylene glycol, dextrin, fatty acid soap, polyhydric alcohol, and the like can be given. These surfactants can be used alone or in combination of two or more. 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 silicon metal powder is 100 parts by mass.

[0083] As the pore-forming material, any material that becomes a pore after firing is acceptable, and for example, graphite, starch, foamed resin, water-absorbing resin, silica gel, and the like can be given. 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 silicon metal powder is 100 parts by mass. The average particle diameter of D50 in the cumulative distribution on a volume basis is preferably 10 to 30 μm. In the case where the pore-forming material is a water-absorbing resin, the average particle diameter of the pore-forming material refers to the average particle diameter after water absorption.

[0084] Next, the obtained molding material is kneaded, and a green body is formed. The green body is extrusion-molded to produce a honeycomb molded body. The honeycomb molded body has peripheral walls and partition walls provided on the inner side of the peripheral walls and dividing a plurality of cells. The plurality of cells form flow paths extending from one end face to the other end face.

[0085] (Drying step)

[0086] Next, the obtained honeycomb molded body is dried to produce a honeycomb dried body. The drying method is not particularly limited, and for example, electromagnetic wave heating methods such as microwave heating drying, high-frequency dielectric heating drying, and external heating methods such as hot air drying, superheated steam drying, and the like can be given. Among them, it is preferable to dry a certain amount of moisture by the electromagnetic wave heating method and then dry the remaining moisture by the external heating method, in terms of being able to dry the molded body as a whole rapidly and uniformly without cracking. As the conditions for drying, it is preferable to remove 30 to 99% by mass of the moisture by the electromagnetic wave heating method and then to make the moisture 3% by mass or less by the external heating method, with respect to the amount of moisture before drying. As the electromagnetic wave heating method, dielectric heating drying is preferable, and as the external heating method, hot air drying is preferable. The drying temperature is preferably 50 to 120°C.

[0087] Next, a slit is formed in the outer peripheral wall and / or the partition wall of the honeycomb dry body. As a method of forming the slit, a cutting tool or the like can be used in accordance with a general method of forming a slit. Note that the slit can not be formed in the honeycomb dry body, and instead, a honeycomb sintered body can be produced by sintering the honeycomb dry body, and then a slit can be formed in the honeycomb sintered body, as described later. In addition, the shape, number, intersection number, length, and width of the slit, and the like can be appropriately designed in accordance with the desired properties of the honeycomb structure to be produced, and the like.

[0088] (Sintering step)

[0089] Next, the honeycomb dry body in which the slit is formed is sintered to produce a honeycomb sintered body. As the sintering conditions, heating at 1400 to 1500°C for 1 to 20 hours in an inert atmosphere such as nitrogen or argon is preferable. In addition, after sintering, oxidation treatment at 1200 to 1350°C for 1 to 10 hours is preferable in order to improve the durability. The method of debinding and sintering is not particularly limited, and sintering can be performed using an electric furnace, a gas furnace, or the like.

[0090] (Filling step)

[0091] Next, a raw material for the filler material is filled in the slit of the honeycomb dry body or the honeycomb sintered body, and dried, thereby forming a filler material layer. As the method of filling the filler material, a known method such as a doctor blade press-in method can be used. The raw material for the filler material is prepared by adding a bonding material (metallic silicon or the like), a binder, a surfactant, a pore-forming material, water, or the like to an aggregate (silicon carbide or the like).

[0092] As the pore-forming material used in the raw material for the filler material, any material that becomes a pore after sintering can be used without particular limitation, and examples include graphite, starch, foamed resin, water-absorbing resin, silica gel, and the like. When the total mass of the aggregate and the bonding material is 100 parts by mass, the content of the pore-forming material is preferably 0.1 to 20 parts by mass, and more preferably 1 to 15 parts by mass. The average particle diameter of the pore-forming material is preferably 3 to 150 μm.

[0093] The average particle diameter of the pore-forming material in the cumulative distribution based on volume is preferably 50 to 200 μm. In the case where the pore-forming material is a water-absorbing resin, the average particle diameter of the pore-forming material refers to the average particle diameter after water absorption. In addition, the pore-forming material can be used in a plurality of combinations of a relatively small pore-forming material having an average particle diameter of 3 to 90 μm and a relatively large pore-forming material having an average particle diameter of more than 90 μm. The average particle diameter of the relatively large pore-forming material is more preferably 100 μm or more. The mixing ratio (parts by mass ratio) of the relatively small pore-forming material to the relatively large pore-forming material is preferably 1.5:8.5 to 7:3.

[0094] From the viewpoint of workability when filling the slit with the filler material, the viscosity of the filler material raw material is preferably 1 to 100 Pa-s.

[0095] Next, the honeycomb dried body or the honeycomb fired body having the filler material in the slit is heated, thereby producing a honeycomb dried body or a honeycomb fired body (honeycomb structure) having a slit provided with a filler material layer. As the heating conditions, heating at 400 to 700°C for 10 to 60 minutes is preferable. The purpose of the heating (heat treatment) is to strengthen the chemical bonds of the filler material. The heating method is not particularly limited, and firing using an electric furnace, a gas furnace, or the like can be performed.

[0096] In addition, as a method of producing a honeycomb structure having an electrode layer, first, an electrode layer forming raw material containing a ceramic raw material is applied to the side surface of a honeycomb dried body, dried, and a pair of unfired electrode layers are formed on the outer surface of the outer peripheral wall so as to extend in a band shape in the flow direction of the cells with the center axis of the honeycomb dried body interposed therebetween, thereby producing a honeycomb dried body with a pair of unfired electrode layers. Next, the honeycomb dried body with a pair of unfired electrode layers is fired, thereby producing a honeycomb fired body with a pair of electrode layers. Thus, a honeycomb structure having an electrode layer is obtained. Note that the electrode layer can be formed after the honeycomb fired body is produced. Specifically, a honeycomb fired body can be produced first, a pair of unfired electrode layers can be formed on the honeycomb fired body, and the honeycomb fired body with a pair of unfired electrode layers can be fired, thereby producing a honeycomb fired body with a pair of electrode layers.

[0097] By appropriately adding various additives to the raw material powder (metal powder and / or ceramic powder, etc.) in accordance with the required characteristics of the electrode layer, and mixing, an electrode layer forming raw material can be formed.

[0098] The method of adjusting the electrode layer forming raw material, and the method of applying the electrode layer forming raw material to the honeycomb fired body can be performed in accordance with the publicly known method of producing a honeycomb structure, but in order to make the resistivity of the electrode layer lower than the resistivity of the honeycomb structure, the content ratio of the metal can be made higher than that of the honeycomb structure, or the particle diameter of the metal particles can be made smaller than that of the honeycomb structure.

[0099] Before the honeycomb dried body with a pair of unfired electrode layers is fired, a debinding process can be performed in order to remove the binder, etc. The debinding process is as described above.

[0100] (Firing Process)

[0101] Next, the honeycomb dried body with the un-fired electrode layer is fired to produce a honeycomb fired body. As the firing conditions, heating at 1400 to 1500°C for 1 to 20 hours in an inert atmosphere such as nitrogen or argon is preferred. Before the firing, a debinding process can be performed to remove the binder and the like. The debinding process is performed at 400 to 500°C in an atmospheric atmosphere, an inert atmosphere, or a reduced pressure atmosphere. After the firing, an oxidation treatment at 1200 to 1350°C for 1 to 10 hours is preferably performed to improve the durability. The firing method is not particularly limited, and a furnace, a gas furnace, or the like can be used for the firing. Thus, the honeycomb structure 10 according to the embodiment of the present application is obtained.

[0102] (4. Method for manufacturing an electrically heated carrier)

[0103] For the method for manufacturing the electrically heated carrier 30 according to the embodiment of the present application, in one embodiment, a metal electrode is fixed to the electrode layer of the honeycomb structure 10 and electrically connected. As the fixing method, for example, a method known in the art such as laser welding, sputtering, ultrasonic welding, or the like can be used. More specifically, a pair of metal electrodes is provided on the outer surface of the electrode layer while sandwiching the center axis of the honeycomb structure portion of the honeycomb structure 10. Thus, the electrically heated carrier 30 according to the embodiment of the present application is obtained.

[0104] (5. Exhaust gas purification device)

[0105] The electrically heated carrier 30 according to the embodiment of the present application described above can be used for an exhaust gas purification device. The exhaust gas purification device has the electrically heated carrier 30 and a metal cylindrical member that holds the electrically heated carrier 30. In the exhaust gas purification device, the electrically heated carrier 30 is disposed in the middle of an exhaust gas flow path through which exhaust gas from an engine flows. In the exhaust gas purification device, in a case where a slit and a filler material are provided on the end surface of the honeycomb structure portion 11, the end surface is preferably disposed on the upstream side of the exhaust gas flow. According to such a configuration, the slit of the honeycomb structure is formed on the end surface through which exhaust gas at a higher temperature passes, and thermal shock can be moderated well, so that cracking can be suppressed more favorably.

[0106] Example

[0107] Hereinafter, although examples for better understanding of the present application and advantages thereof are illustrated, the present application is not limited to the examples.

[0108] Example 1

[0109] (1. Production of a blank)

[0110] A ceramic raw material was prepared by mixing silicon carbide (SiC) powder and silicon (Si) powder at a mass ratio of 80:20. Then, a molding raw material was prepared by adding hydroxypropyl methylcellulose as a binder, a water-absorbing resin as a pore-forming material, and water to the ceramic raw material. Then, the molding raw material was kneaded using a vacuum pug mill to produce a cylindrical green compact. The content of the binder was 7 parts by mass when the total of the silicon carbide (SiC) powder and the silicon (Si) powder was taken as 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 silicon (Si) powder was taken as 100 parts by mass. The content of water was 42 parts by mass when the total of the silicon carbide (SiC) powder and the silicon (Si) powder was taken as 100 parts by mass. The average particle diameter of the silicon carbide powder was 20 μm, and the average particle diameter of the silicon powder was 6 μm. In addition, the average particle diameter of the pore-forming material was 20 μm. The average particle diameters of the silicon carbide powder, the silicon powder, and the pore-forming material refer to the arithmetic average particle diameters on a volume basis when the frequency distribution of the particle size is measured using a laser diffraction method.

[0111] (2. Production of honeycomb dry body)

[0112] A cylindrical honeycomb molded body in which each cell shape in a cross section perpendicular to the flow path direction of the cells was hexagonal was produced by molding the obtained cylindrical green compact using an extrusion molding machine having a die structure in the shape of a checkerboard. The honeycomb molded body was dried at 120°C for 2 hours using a hot air dryer after high-frequency dielectric heating drying, and a honeycomb dry body was produced.

[0113] Next, the cells of the honeycomb dry body were removed by a slit as shown in FIG. 1, and a slit was formed. Figure 1

[0114] (3. Preparation and application of electrode layer-forming paste)

[0115] An electrode layer-forming paste was prepared by mixing silicon (Si) powder, silicon carbide (SiC) powder, methylcellulose, glycerol, and water using a self-rotating and revolving stirrer. The Si powder and the SiC powder were mixed at a volume ratio of Si powder: SiC powder = 40:60. In addition, the content of the methylcellulose was 0.5 parts by mass, the content of the glycerol was 10 parts by mass, and the content of the water was 38 parts by mass when the total of the Si powder and the SiC powder was taken as 100 parts by mass. The average particle diameter of the silicon powder was 6 μm. The average particle diameter of the silicon carbide powder was 35 μm. These average particle diameters refer to the arithmetic average particle diameters on a volume basis when the frequency distribution of the particle size is measured using a laser diffraction method.

[0116] Next, the electrode layer-forming paste was applied to the honeycomb dry body at an appropriate area and film thickness using a curved surface printer. ​

[0117] (4. Filling and firing of the filler material)

[0118] Next, the filler material was made using raw materials as follows. First, silicon carbide powder and silica powder (colloidal silica) were mixed in a mass ratio of 68:32 in terms of solid content. At this time, the mass of the silica was the mass converted to an oxide (SiO2). A binder, carboxymethyl cellulose, a pore-forming material with an average particle diameter of 50 μm, and a pore-forming material with an average particle diameter of 150 μm, a humectant, glycerin, and water were added, and mixed, thereby obtaining a mixture. Next, the mixture was kneaded to make a filler material forming raw material. The content of the binder was 1.0 parts by mass when the total of the solid contents of the silicon carbide powder and the silica powder was taken as 100 parts by mass. The content of the pore-forming material with an average particle diameter of 50 μm was 7 parts by mass when the total of the solid contents of the silicon carbide powder and the silica powder was taken as 100 parts by mass. The content of the pore-forming material with an average particle diameter of 150 μm was 3 parts by mass when the total of the solid contents of the silicon carbide powder and the silica powder was taken as 100 parts by mass. The D50 of the pore-forming material on a volume basis was 80 μm. The content of the glycerin was 4 parts by mass when the total of the solid contents of the silicon carbide powder and the silica powder was taken as 100 parts by mass. The content of the water was 30 parts by mass when the total of the silicon carbide powder and the silica powder was taken as 100 parts by mass. The average particle diameter of the silicon carbide powder was 8 μm. This average particle diameter was a value determined using a laser diffraction method. The filler material forming raw material was filled into the slits of the honeycomb dry body using a doctor blade.

[0119] Further, after drying at 120°C for 30 minutes using a hot air dryer, the honeycomb dry body was fired at 1400°C for 3 hours in an Ar atmosphere to produce a columnar honeycomb structure in which a filler material layer was provided in the slits.

[0120] The honeycomb structure had a circular end face with a diameter of 100 mm and a height (length in the flow path direction of the cells) of 100 mm. The cell density was 93 cells / cm 2 , the thickness of the partition walls was 101.6 μm, the porosity of the partition walls was 45%, and the average pore diameter of the partition walls was 8.6 μm. The thickness of the electrode layer was 0.3 mm. The Young's modulus of the honeycomb structure was 5 GPa.

[0121] The proportion of the volume of pores having a pore diameter of 90 μm or more in the honeycomb structure of Example 1, relative to the total volume of pores in the filler material layer, the Young's modulus, the porosity, the D50 pore diameter on a volume basis, and the content of each pore-forming material having an average particle diameter of 50 μm and an average particle diameter of 150 μm are shown in Table 1. The content of the pore-forming material indicates the mass ratio (mass parts) of the pore-forming material when the total of the silicon carbide powder and the silica powder contained in the filler material layer is taken as 100 mass parts.

[0122] For the obtained honeycomb structure, a "heat shock resistance test" was performed using the method given below. In the table, as a result of the "heat shock resistance test", the "occurrence temperature of longitudinal cracking" and the "occurrence temperature of end face cracking" are shown.

[0123] [Heat shock resistance test (burner test)]

[0124] A heating and cooling test of the honeycomb structure was performed using a "propane gas burner test machine provided with a metal case in which the honeycomb structure is housed, and a propane gas burner capable of supplying a heating gas into the metal case". As the heating gas, a combustion gas produced by combusting propane gas in a gas burner (propane gas burner) was used. And, by the heating and cooling test, it was confirmed whether or not the honeycomb structure cracked, whereby the heat shock resistance was evaluated. Specifically, first, the obtained honeycomb structure was housed (canned) in the metal case of the propane gas burner test machine. Then, a gas (combustion gas) heated by the propane gas burner was supplied into the metal case so as to pass through the honeycomb structure. The temperature conditions of the heating gas flowing into the metal case (inlet gas temperature conditions) were as follows. First, the temperature was raised to a specified temperature at 5 minutes, maintained at the specified temperature for 10 minutes, and then cooled to 100°C at 5 minutes, maintained at 100°C for 10 minutes. This series of operations of raising, cooling, and maintaining was called "raising and cooling operation". After that, the cracking of the honeycomb structure was confirmed. And, while the specified temperature was raised by 25°C from 825°C, the above "raising and cooling operation" was repeated. With respect to the specified temperature, when the specified temperature at which the sample cracked was raised by 25°C, the raising gradient became larger, the outer peripheral portion was raised slower than the center portion, and thus the temperature difference between the center portion and the outer peripheral portion became larger, and the stress became larger.

[0125] The heat shock resistance test of the honeycomb structure in which no cracking occurred up to the specified temperature of 850°C was good. That is, if no cracking occurred at the specified temperature of 850°C, the heat shock resistance was good even if cracking occurred at a higher specified temperature, and in the case where cracking occurred at a specified temperature of less than 850°C, the effect of the heat shock resistance of the present application was not obtained. In the present heat shock resistance test, the presence or absence of the following two types of cracking was confirmed. The first type of cracking is referred to as "longitudinal cracking", and the second type of cracking is referred to as "end face cracking". The "longitudinal cracking" is cracking that occurs in the side surface of the honeycomb structure in a direction from the first end face of the honeycomb structure toward the second end face. The "end face cracking" is cracking that occurs in the end face of the honeycomb structure. The temperature at which the above-mentioned longitudinal cracking was confirmed to occur is shown in the column of "temperature at which longitudinal cracking occurred" in Table 1. The temperature at which the above-mentioned end face cracking was confirmed to occur is shown in the column of "temperature at which end face cracking occurred" in Table 1.

[0126] Examples 2 to 12, Comparative Examples 1, 2

[0127] The honeycomb structures were produced in the same manner as in Example 1, except that the conditions of the filler material were changed as shown in Table 1. The "heat shock resistance test" was performed in the same manner as in Example 1.

[0128] In Table 1, the "temperature at which longitudinal cracking occurred" and the "temperature at which end face cracking occurred" are shown as the results of the "heat shock resistance test".

[0129] Table 1

[0130]

[0131] (Evaluation results)

[0132] As shown in Table 1, in the honeycomb structures of Examples 1 to 12, both the "temperature at which longitudinal cracking occurred" and the "temperature at which end face cracking occurred" were 850°C or higher, and the heat shock resistance was excellent. On the other hand, in the honeycomb structures of Comparative Examples 1 and 2, at least one of the "temperature at which longitudinal cracking occurred" and the "temperature at which end face cracking occurred" was lower than 850°C, and the heat shock resistance was poor. From the above results, it was found that the filler material layer filled in the slits of the honeycomb structure has pores, and that the pores having a diameter of 90 μm or more account for 30% or more by volume with respect to all the pores contained in the filler material layer, and thus cracking at high temperatures is suppressed.

Claims

1. A honeycomb structure, wherein a honeycomb structure portion having a peripheral wall and a partition wall provided on an inner side of the peripheral wall and dividing a plurality of cells forming flow paths extending from one end face to the other end face, a slit is provided in the peripheral wall and / or the cell, the slit including a filler material layer composed of a filler material, the filler material layer has pores, and the volume of pores having a pore diameter of 90 μm or more is 30% or more and 90% or less with respect to the volume of all the pores included in the filler material layer.

2. The honeycomb structure according to claim 1, wherein in the filler material layer, the pore diameter of D50 in the cumulative distribution on a volume basis is 80 to 500 μm.

3. The honeycomb structure according to claim 1, wherein the Young's modulus of the filler material layer is 10 to 1000 MPa.

4. The honeycomb structure according to claim 1, wherein the Young's modulus of the honeycomb structure portion is 1 to 100 GPa.

5. The honeycomb structure according to claim 1, wherein the slit is formed on the outer surface of the peripheral wall of the honeycomb structure portion, and is a slit extending in a direction parallel to the axial direction of the honeycomb structure, and / or a slit formed in at least one end face of the honeycomb structure portion.

6. The honeycomb structure according to any one of claims 1 to 5, wherein the honeycomb structure further has a pair of electrode layers provided on the outer surface of the peripheral wall in a manner extending in a band shape along the flow path direction of the cell, sandwiching the central axis of the honeycomb structure portion.

7. An electrically heatable support, wherein provided with: the honeycomb structure according to claim 6; and a metal electrode electrically connected to the electrode layer of the honeycomb structure.

8. An exhaust gas purification apparatus, wherein, provided with: the electrically heated carrier according to claim 7; and a metal cylindrical member for holding the electrically heated carrier.

Images