JP2009085202A - Honeycomb structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a honeycomb structure with an excellent thermal shock resistance. <P>SOLUTION: This honeycomb structure 1 has a honeycomb base 2 made of porous ceramic, and a mat material 5 disposed on an outer circumference of the honeycomb base 2. A thermal conductivity of the mat material 5 is smaller than that of the honeycomb base 2. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a honeycomb structure, and more particularly to a honeycomb structure excellent in thermal shock resistance.

  Catalytic carrier utilizing catalytic action of internal combustion engine, boiler, chemical reaction equipment, fuel cell reformer, etc., particulates such as soot in exhaust gas (particularly particulate matter (PM) in exhaust gas from diesel engine) A ceramic honeycomb structure is used for a collection filter (hereinafter referred to as DPF).

  A honeycomb structure made of a ceramic is generally made of a porous ceramic, and includes a honeycomb base material that divides a plurality of cells serving as fluid flow paths, and an outer periphery made of ceramic that covers the outer peripheral surface of the honeycomb base material in the circumferential direction. And a material layer. And the honeycomb base material is sealed with a sealing portion made of ceramics that seals the end portions where the adjacent cells are opposite to each other so that the end faces have a checkered pattern.

  A DPF made of a ceramic honeycomb structure is used as a wall flow type catalyst in which exhaust gas passes through partition walls that partition partition wall cells. The wall flow type catalyst collects PM in the exhaust gas through which the exhaust gas passes through the continuous pores formed in the cell wall and cannot pass through the pores. That is, the DPF is exposed to high-temperature exhaust gas in order to collect PM in the exhaust gas.

  Further, since the DPF is clogged when the collected PM is accumulated, it is necessary to remove the collected PM. One method of removing the collected PM is a method of decomposing and removing PM by combustion or the like. There is also a method in which a catalytic metal exhibiting catalytic activity is supported on the DPF and PM is decomposed with this catalytic metal.

  When PM is burned and removed, the honeycomb structure is heated, and combustion is further promoted by heat generated during decomposition (combustion) of PM. That is, the DPF is exposed to a rapid temperature change (temperature increase) during PM combustion.

  When the DPF exposed to high temperature is rapidly cooled, there is a problem in that the outer peripheral portion (outer peripheral material layer) is damaged. When the DPF held at a high temperature is rapidly cooled, the outer peripheral portion is rapidly cooled and contracts, but the inside (honeycomb substrate) remains at a high temperature and does not follow the contraction of the outer peripheral portion. As a result, tensile stress was applied to the outer peripheral portion, and cracks and cracks were generated in the outer peripheral portion.

  This invention is made | formed in view of the said situation, and makes it a subject to provide the honeycomb structure excellent in thermal shock resistance.

  In order to solve the above-mentioned problems, the present inventors have repeatedly studied about a ceramic honeycomb structure, and as a result, found that the outer peripheral material layer does not greatly contribute to the thermal shock resistance of the honeycomb structure in the conventional honeycomb structure. The present invention has been made.

  The honeycomb structure of the present invention is made of a porous ceramic and has a honeycomb substrate having a large number of cells extending in the axial direction, an outer peripheral material layer made of ceramic formed on the outer periphery of the honeycomb substrate, and an outer periphery of the outer peripheral material layer. A mat member made of a heat-resistant porous material disposed on the surface, wherein the mat member has a thermal conductivity κ1 smaller than the honeycomb substrate thermal conductivity κ0. Features.

  The honeycomb structure of the present invention is made of porous ceramics and has a honeycomb base material having a large number of cells extending in the axial direction, and a mat member made of a heat-resistant porous material disposed on the outer peripheral surface of the honeycomb base material. A ceramic structure obtained by impregnating a mat material with a slurry in which ceramic particles are dispersed, and then firing the ceramic material, wherein the mat material has a thermal conductivity κ1 that is equal to the thermal conductivity of the honeycomb substrate. It is smaller than κ0.

  The honeycomb structure of the present invention has a honeycomb base material made of porous ceramics and a mat material disposed on the outer periphery of the honeycomb base material, and the thermal conductivity of the mat material is smaller than that of the honeycomb base material. ing. With such a configuration, the temperature gradient of the honeycomb substrate when exposed to a high temperature can be reduced by the mat material. As a result, the honeycomb structure of the present invention became a honeycomb structure excellent in thermal shock resistance.

(First invention)
The honeycomb structure of the present invention is made of a porous ceramic and has a honeycomb substrate having a large number of cells extending in the axial direction, an outer peripheral material layer made of ceramic formed on the outer periphery of the honeycomb substrate, and an outer periphery of the outer peripheral material layer. And a mat member made of a heat-resistant porous material disposed on the surface.

  In the honeycomb structure of the present invention, the value of the thermal conductivity κ1 of the mat member is smaller than the thermal conductivity κ0 of the honeycomb substrate. As in the present invention, the mat material disposed on the outer periphery of the outer peripheral material layer is formed of a material having a lower thermal conductivity than the honeycomb base material, so that heat exchange with the outside through the mat material occurs. It becomes difficult. Thereby, the temperature gradient is reduced inside the mat member, and stress concentration due to the temperature gradient is relaxed. As a result, the occurrence of cracks and cracks in the honeycomb structure and the outer peripheral material layer due to thermal shock can be suppressed.

  More specifically, when the temperature of the honeycomb structure of the present invention is raised, the temperatures of the honeycomb base material and the outer peripheral material layer are increased, and each of them undergoes thermal expansion. However, since the mat material arranged on the outer periphery of the outer peripheral material layer has lower thermal conductivity than the honeycomb base material, it is difficult to transfer the heat inside the mat material to the outside. For this reason, the high heat of the honeycomb base material and the outer peripheral material layer inside the mat material is uniformly diffused inside the mat material. Then, the temperature gradient inside the mat member is eliminated or becomes a very small amount. As a result, the thermal stress unevenness caused by the temperature gradient is eliminated. That is, cracks and cracks do not occur in the honeycomb structure.

  Further, when the high-temperature honeycomb structure is cooled (rapidly cooled), the mat material exposed to a lower temperature is cooled. At this time, since the thermal conductivity of the mat material is low, the honeycomb base material and the outer peripheral material layer are maintained at a high temperature (a state in which thermal expansion occurs) inside the mat material. Further, due to the low thermal conductivity of the mat material, the heat inside the mat material is hardly released through the mat material. For this reason, a rapid temperature change does not occur in the honeycomb substrate and the outer peripheral material layer, and a large temperature gradient does not occur. As a result, the thermal stress unevenness caused by the temperature gradient is eliminated. That is, cracks and cracks do not occur in the honeycomb structure. Thus, the honeycomb structure of the present invention was excellent in thermal shock resistance.

  In the honeycomb structure of the present invention, the effect of eliminating the temperature gradient can be exhibited as the thermal conductivity of the mat member is smaller than the thermal conductivity of the honeycomb substrate. In the honeycomb structure of the present invention, the ratio of the thermal conductivity κ1 of the mat material and the thermal conductivity κ0 of the honeycomb base material is preferably 0.8 or less. If the thermal conductivity of the mat material exceeds 0.8 times the thermal conductivity of the honeycomb substrate, the difference in thermal expansion coefficient between the honeycomb substrate and the mat material becomes too small, and a temperature gradient tends to occur inside the mat material. Become. A more preferable ratio (κ1 / κ0) between the thermal conductivity κ1 of the mat member and the thermal conductivity κ0 of the honeycomb substrate is 0.5 or less.

  In the honeycomb structure of the present invention, the mat member is disposed on the outer peripheral surface of the outer peripheral material layer. At this time, the mat member is preferably arranged in a state where the outer peripheral surface is completely covered.

  The mat member is formed by arranging a substantially band-shaped member on the outer circumferential surface of the outer circumferential material layer along the circumferential direction, and an end surface of one end portion of the substantially band-shaped member in the tangential direction of the outer circumferential material layer. It is preferable that the end portion of the member which is inclined with respect to the end surface adjacent to the inclined end surface is in contact with the end surface. By having such a configuration, there is no gap between the substantially strip-shaped member and the outer peripheral material layer in the vicinity of one end of the substantially strip-shaped member constituting at least a part of the mat material. Adhesion with the outer peripheral material layer is improved.

  Here, the end adjacent to one end of the substantially band-shaped member may be the end of the same substantially band-shaped member or the end of a different member. That is, even if the mat member is formed by winding one substantially band-shaped member around the outer peripheral surface of the outer peripheral material layer along the circumferential direction, a plurality of substantially band-shaped members are formed circumferentially on the outer peripheral surface of the outer peripheral material layer. Therefore, it may be formed continuously. Furthermore, the mat member may be formed by spirally winding one substantially band-shaped member around the outer peripheral surface of the outer peripheral material layer.

  And the inclination of the end surface of the one edge part of the circumferential direction of a substantially strip-shaped member should just incline with respect to the tangent direction of an outer peripheral material layer. The end surface may be inclined in a state where the end surface is disposed on the outer peripheral surface of the outer peripheral material layer and the end surface is opposed to the outer side in the radial direction. By inclining in this way, no gap is generated when the adjacent end portions ride on the inclined end surface.

  The inclination angle formed by the end surface of one end of the substantially band-shaped member constituting the mat member is not particularly limited, but the end surface of one end is 10 to 10 in the tangential direction of the outer peripheral material layer. The angle is preferably 80 °. When the end surface has an inclination angle within this range, the adhesion between the mat material and the outer peripheral material layer is further improved. A more preferable inclination angle is 30 to 60 °.

  The inclination angle formed by the end surface of one end portion of the substantially band-shaped member constituting the mat material is an inclination angle with respect to the tangential direction of the outer peripheral material layer, but the substantially band-shaped member before being wound around the outer peripheral material layer. The angle between the inner peripheral surface and the end surface can be set.

  Here, the end that contacts the inclined end surface of one end may be in contact with the inclined end surface on the inner peripheral surface or on the end surface of the contacting end. When the end surfaces of the abutting end portions abut, it is preferable that the end surface of the end portion that abuts in an inclined shape corresponding to the inclination of the inclined end surface is also formed.

  In the honeycomb structure of the present invention, the thickness of the mat material (the thickness in the radial direction of the honeycomb structure) is not particularly limited, but the effect of the mat material (temperature) increases as the thickness increases. The effect of suppressing the concentration of thermal stress due to the gradient is increased. That is, as the mat material becomes thicker, it can withstand a higher temperature thermal shock. A preferable mat material has a thickness of 0.5 mm or more, and a more preferable thickness is 1.0 mm or more.

  The porous ceramic material forming the honeycomb substrate of the honeycomb structure of the present invention is not particularly limited, and conventionally known ceramics can be used. The ceramic is preferably mainly composed of one kind selected from aluminum titanate, silicon carbide, silicon nitride, and cordierite. Of these ceramics, it is more preferable to be made of ceramics mainly composed of silicon carbide.

  In the honeycomb structure of the present invention, the shape (cross-sectional shape) of the cells formed on the honeycomb substrate is not particularly limited, and can be a conventionally known cross-sectional shape. Of the conventionally known cell shapes, a square shape is more preferable.

  Furthermore, the honeycomb substrate may be formed by bonding a plurality of ceramic bodies through a bonding material layer. At this time, the size (cell shape) of the cells formed in each ceramic segment may be the same or different. The size (cell shape) of each ceramic segment cell is preferably the same.

  In the honeycomb substrate, one end or the other end of many cells is preferably sealed with a sealing material made of ceramics. A wall flow type honeycomb structure can be formed by sealing one end or the other end of the cell with a sealing material. The material of the ceramic constituting the sealing material is not particularly limited, and may be the same as or different from the porous ceramic constituting the honeycomb substrate. More preferably, the ceramic is mainly composed of porous ceramics.

  The outer peripheral material layer of the honeycomb structure of the present invention can have the same configuration as the conventionally known outer peripheral material layer of the honeycomb structure. That is, a conventionally known material can be used as the material constituting the outer peripheral material layer, and for example, SiC, silica-based compounds, alumina-based compounds such as aluminum titanate, and the like can be used.

  The thickness of the outer peripheral material layer of the honeycomb structure of the present invention can be the same as that conventionally known, and preferably has a thickness of 0.5 mm or more. Here, since the outer peripheral material layer regulates the thermal expansion of the honeycomb base material as the thickness of the outer peripheral material layer increases, the thermal shock resistance is improved. Generally, the outer peripheral material layer is formed by preparing a slurry that constitutes the outer peripheral material layer and applying this slurry to the outer peripheral surface of the honeycomb base material. Therefore, as the thickness of the outer peripheral material layer increases, the slurry is applied. Thickness increases, workability deteriorates and costs increase. For this reason, the preferable thickness of the outer peripheral material layer is 0.5 to 5.0 mm, the more preferable thickness is 0.5 to 3.0 mm, and the further preferable thickness is 0.5 to 1.0 mm. . Here, the thickness of the outer peripheral material layer is defined as the thickness of the outer peripheral material layer at the portion where the thickness in the radial direction of the honeycomb structure is the thinnest.

  The mat material of the honeycomb structure of the present invention is not limited as long as it has the above-described thermal expansion coefficient. For example, the nonwoven fabric which consists of heat resistant ceramic fibers can be mention | raise | lifted. Conventionally, a mat member wound around the outer periphery of the honeycomb structure when the honeycomb structure is inserted and arranged in the exhaust pipe may be used.

  The honeycomb structure of the present invention is preferably used for a DPF. The honeycomb structure of the present invention can be used as a wall flow type filter catalyst in which exhaust gas (gas) passes through partition walls that partition cells, and among these filter catalysts, it is particularly preferable to use as a DPF.

  When the honeycomb structure of the present invention is used as a DPF, it is preferable to support at least one of a porous oxide made of alumina or the like and a catalyst metal such as Pt, Pd, or Rh on at least the pore surfaces of the partition walls. By carrying these substances, purification performance such as particulates as DPF is improved.

  The outer peripheral shape of the honeycomb structure of the present invention is not particularly limited, and can be a conventionally known shape. For example, the cross section may be a substantially circular or elliptical cylinder, and the cross section may be a square or polygonal prism, and more preferably a cylinder.

(Second invention)
The honeycomb structure of the present invention is made of porous ceramics and has a honeycomb base material having a large number of cells extending in the axial direction, and a mat member made of a heat-resistant porous material disposed on the outer peripheral surface of the honeycomb base material. And a ceramic formed by impregnating a mat material with a slurry in which ceramic particles are dispersed and then firing. That is, in the honeycomb structure of the present invention, the mat material and the ceramic form an outer peripheral material layer.

  In the honeycomb structure of the present invention, the value of the thermal conductivity κ1 of the mat member is smaller than the thermal conductivity κ0 of the honeycomb substrate. As in the present invention, the mat material disposed on the outer periphery of the honeycomb base material is formed of a material having a lower thermal conductivity than the honeycomb base material, so that the mat material and the ceramic are formed via the outer peripheral material layer. The heat exchange with the outside is less likely to occur. As a result, the temperature gradient of the honeycomb substrate is reduced inside the outer peripheral material layer, and the concentration of stress due to the temperature gradient is relaxed. As a result, the occurrence of cracks and cracks in the honeycomb structure and the outer peripheral material layer due to thermal shock can be suppressed.

  More specifically, when the temperature of the honeycomb structure of the present invention is increased, the temperatures of the honeycomb base material and the outer peripheral material layer are increased. However, since the outer peripheral material layer has a lower thermal conductivity than the honeycomb substrate, it is difficult to transfer the heat inside the outer peripheral material layer to the outside. For this reason, the high heat of the honeycomb base material inside the outer peripheral material layer diffuses uniformly inside the outer peripheral material layer. And the temperature gradient inside an outer peripheral material layer is eliminated, or it becomes a trace amount. As a result, the thermal stress unevenness caused by the temperature gradient is eliminated. That is, cracks and cracks do not occur in the honeycomb structure.

  Further, when the high-temperature honeycomb structure is cooled (rapidly cooled), the outer peripheral material layer exposed to a lower temperature is cooled. At this time, since the thermal conductivity of the outer peripheral material layer is low due to the mat material, the high temperature (a state in which thermal expansion occurs) of the honeycomb substrate is maintained inside the outer peripheral material layer. Further, due to the low thermal conductivity of the outer peripheral material layer, the heat inside the outer peripheral material layer is hardly released through the outer peripheral material layer. For this reason, a rapid temperature change does not occur in the honeycomb substrate, and a large temperature gradient is not generated. As a result, the thermal stress unevenness caused by the temperature gradient is eliminated. That is, cracks and cracks do not occur in the honeycomb structure.

  Thus, the honeycomb structure of the present invention has excellent thermal shock resistance.

  In the honeycomb structure of the present invention, the effect of eliminating the temperature gradient can be exhibited as the thermal conductivity of the mat member is smaller than the thermal conductivity of the honeycomb substrate. In the honeycomb structure of the present invention, the ratio of the thermal conductivity κ1 of the mat material and the thermal conductivity κ0 of the honeycomb base material is preferably 0.8 or less. If the thermal conductivity of the mat material exceeds 0.8 times the thermal conductivity of the honeycomb substrate, the difference in thermal expansion coefficient between the honeycomb substrate and the mat material becomes too small, and a temperature gradient is generated inside the outer peripheral material layer. It becomes easy. A more preferable ratio (κ1 / κ0) between the thermal conductivity κ1 of the mat member and the thermal conductivity κ0 of the honeycomb substrate is 0.5 or less.

  In the honeycomb structure of the present invention, the mat member is disposed on the outer peripheral surface of the honeycomb substrate. At this time, the mat member is preferably arranged in a state in which the outer peripheral surface of the honeycomb substrate is completely covered.

  The mat member is formed by arranging a substantially band-shaped member on the outer circumferential surface of the outer circumferential material layer along the circumferential direction, and an end surface of one end portion of the substantially band-shaped member in the tangential direction of the outer circumferential material layer. It is preferable that the end portion of the member which is inclined with respect to the end surface adjacent to the inclined end surface is in contact with the end surface. By having such a configuration, there is no gap between the substantially strip-shaped member and the outer peripheral material layer in the vicinity of one end of the substantially strip-shaped member constituting at least a part of the mat material. Adhesion with the outer peripheral material layer is improved.

  Here, the end adjacent to one end of the substantially band-shaped member may be the end of the same substantially band-shaped member or the end of a different member. That is, even if the mat member is formed by winding one substantially band-shaped member around the outer peripheral surface of the outer peripheral material layer along the circumferential direction, a plurality of substantially band-shaped members are formed circumferentially on the outer peripheral surface of the outer peripheral material layer. Therefore, it may be formed continuously. Furthermore, the mat member may be formed by spirally winding one substantially band-shaped member around the outer peripheral surface of the outer peripheral material layer.

  And the inclination of the end surface of the one edge part of the circumferential direction of a substantially strip-shaped member should just incline with respect to the tangent direction of an outer peripheral material layer. The end surface may be inclined in a state where the end surface is disposed on the outer peripheral surface of the outer peripheral material layer and the end surface is opposed to the outer side in the radial direction. By inclining in this way, no gap is generated when the adjacent end portions ride on the inclined end surface.

  The inclination angle formed by the end surface of one end of the substantially band-shaped member constituting the mat member is not particularly limited, but the end surface of one end is 10 to 10 in the tangential direction of the outer peripheral material layer. The angle is preferably 80 °. When the end surface has an inclination angle within this range, the adhesion between the mat material and the outer peripheral material layer is further improved. A more preferable inclination angle is 30 to 60 °.

  The inclination angle formed by the end surface of one end portion of the substantially band-shaped member constituting the mat material is an inclination angle with respect to the tangential direction of the outer peripheral material layer, but the substantially band-shaped member before being wound around the outer peripheral material layer. The angle between the inner peripheral surface and the end surface can be set.

  Here, the end that contacts the inclined end surface of one end may be in contact with the inclined end surface on the inner peripheral surface or on the end surface of the contacting end. When the end surfaces of the abutting end portions abut, it is preferable that the end surface of the end portion that abuts in an inclined shape corresponding to the inclination of the inclined end surface is also formed.

  In the honeycomb structure of the present invention, the thickness of the mat material (the thickness in the radial direction of the honeycomb structure) is not particularly limited, but the effect of the mat material (temperature) increases as the thickness increases. The effect of suppressing the concentration of thermal stress due to the gradient is increased. That is, as the mat material becomes thicker, it can withstand a higher temperature thermal shock. A preferable mat material has a thickness of 0.5 mm or more, and a more preferable thickness is 1.0 mm or more.

  The porous ceramic material forming the honeycomb substrate of the honeycomb structure of the present invention is not particularly limited, and conventionally known ceramics can be used. The ceramic is preferably mainly composed of one kind selected from aluminum titanate, silicon carbide, silicon nitride, and cordierite. Of these ceramics, it is more preferable to be made of ceramics mainly composed of silicon carbide.

  In the honeycomb structure of the present invention, the shape (cross-sectional shape) of the cells formed on the honeycomb substrate is not particularly limited, and can be a conventionally known cross-sectional shape. Of the conventionally known cell shapes, a square shape is more preferable.

  Furthermore, the honeycomb substrate may be formed by bonding a plurality of ceramic bodies through a bonding material layer. At this time, the size (cell shape) of the cells formed in each ceramic segment may be the same or different. The size (cell shape) of each ceramic segment cell is preferably the same.

  In the honeycomb substrate, one end or the other end of many cells is preferably sealed with a sealing material made of ceramics. A wall flow type honeycomb structure can be formed by sealing one end or the other end of the cell with a sealing material. The material of the ceramic constituting the sealing material is not particularly limited, and may be the same as or different from the porous ceramic constituting the honeycomb substrate. More preferably, the ceramic is mainly composed of porous ceramics.

  The honeycomb structure of the present invention includes a mat material made of a heat-resistant porous material disposed on the outer peripheral surface of a honeycomb base material, and a ceramic formed by impregnating the mat material with a slurry in which ceramic particles are dispersed and firing. The mat material and the ceramic are integrated to form an outer peripheral material layer. By forming the outer peripheral material layer in which the mat material and ceramics are integrated, the number of steps required for manufacturing can be reduced. Furthermore, since the mat member and the ceramic form an integral outer peripheral material layer, the mat member and the ceramic are fixed to the honeycomb substrate, and the mat member is difficult to peel off.

  As the ceramic of the outer peripheral material layer, ceramics constituting the outer peripheral material layer of the conventional honeycomb structure can be used. For example, SiC, silica-based compounds, alumina-based compounds such as aluminum titanate, and the like can be used.

  The mat material of the honeycomb structure of the present invention is not limited as long as it has the above-described thermal conductivity. For example, the nonwoven fabric which consists of heat resistant ceramic fibers can be mention | raise | lifted. Conventionally, a mat member wound around the outer periphery of the honeycomb structure when the honeycomb structure is inserted and arranged in the exhaust pipe may be used.

  In the honeycomb structure of the present invention, a mat member (outer peripheral mat member) may be further arranged on the outer peripheral surface. By providing this outer periphery mat member, cushioning properties when inserted into the exhaust pipe of the vehicle can be ensured. The material of the outer peripheral mat member is not limited to the back of the hand, and a conventionally known mat member can be used. Conventionally, a mat member wound around the outer periphery of the honeycomb structure when the honeycomb structure is inserted and arranged in the exhaust pipe may be used as the outer periphery mat member. The material of the outer peripheral mat material is not particularly limited, but is preferably made of a material having a lower thermal conductivity than the honeycomb base material, and has a thermal conductivity higher than that of the mat material arranged on the outer periphery of the honeycomb base material. More preferably, it is made of a low material.

  The honeycomb structure of the present invention is preferably used for a DPF. The honeycomb structure of the present invention can be used as a wall flow type filter catalyst in which exhaust gas (gas) passes through partition walls that partition cells, and among these filter catalysts, it is particularly preferable to use as a DPF.

  When the honeycomb structure of the present invention is used as a DPF, it is preferable to support at least one of a porous oxide made of alumina or the like and a catalyst metal such as Pt, Pd, or Rh on at least the pore surfaces of the partition walls. By carrying these substances, purification performance such as particulates as DPF is improved.

  The outer peripheral shape of the honeycomb structure of the present invention is not particularly limited, and can be a conventionally known shape. For example, the cross section may be a substantially circular or elliptical cylinder, and the cross section may be a square or polygonal prism, and more preferably a cylinder.

  Hereinafter, the present invention will be described using examples.

  As an example of the present invention, a honeycomb structure for DPF was manufactured.

Example 1
In this example, a honeycomb body 2 made of porous ceramics, a sealing portion 3 for sealing cells of the honeycomb body 2, an outer peripheral material layer 4 disposed on the outer periphery of the honeycomb body 2, and an outer peripheral material layer 4 1 is a honeycomb structure 1 having a substantially columnar outer shape. The honeycomb structure of the present example is shown in FIGS. FIG. 1 shows an end face on one end side of the honeycomb structure 1 of this example, and FIG. 2 shows a cross section in the axial direction.

  The honeycomb body 2 is made of porous SiC ceramics, and a large number of cells 20 and 21 extending in the axial direction of the honeycomb body 2 are partitioned by cell walls 22 and have a substantially cylindrical outer peripheral shape. . And many cells 20 and 21 are divided by the cell wall 22 so that the cross-sectional shape of square shape may be made, respectively. The porous ceramics constituting the honeycomb body 2 has a uniform pore distribution. The honeycomb body 2 of the present example is formed to have a substantially cylindrical shape with a diameter of 90 mm and an axial length of 150 mm.

  A sealing portion 3 made of sealing materials 30 and 31 for sealing the cells 20 and 21 is formed at any of the axial ends of the numerous cells 20 and 21 of the honeycomb body 2. The sealing material 30 seals the cells 20 on one end side of the honeycomb structure 1, and the sealing material 31 seals the cells 21 on the other end side. And the sealing materials 30 and 31 are sealing the cells 20 and 21 so that an end surface may make a checkered pattern. The sealing materials 30 and 31 are provided so that the length in the cells 20 and 21 is constant.

  The outer peripheral material layer 4 is an SiC ceramic layer formed on the outer peripheral surface of the honeycomb body 2 with a uniform thickness. The outer peripheral material layer 4 was formed with a thickness of 0.5 mm.

  The mat member 5 is a porous body made of heat resistant ceramics. In this example, a band-shaped member having a width of 150 mm formed from a nonwoven fabric of ceramic fibers made of alumina silica fibers (manufactured by NICHIAS Corporation, trade name: Fine Flex Paper 5130-T) It was formed by winding on a surface. The mat member 5 is formed so that the thickness in the radial direction is 20 mm.

The thermal conductivity of the honeycomb substrate 2 and the mat member 5 of the honeycomb structure 1 of this example was measured. The honeycomb substrate 2 had a thermal conductivity κ0 of 40.6, and the mat member 5 had a thermal conductivity κ1 of 0.07. That is, the thermal conductivity ratio (κ1 / κ0) was 0.002 (1.7 × 10 ⁻³ ).

  A method for manufacturing the honeycomb structure 1 of the present embodiment will be described below.

  First, the honeycomb body 2 in which the sealing part 3 is formed is manufactured. For this production, a conventionally known production method was used.

  And the slurry which disperse | distributed SiC ceramic particle was prepared, the slurry was apply | coated to the outer peripheral surface of the honeycomb body 2, and it baked. Thereby, the outer peripheral material layer 4 was formed.

  Subsequently, a belt-like mat member 50 was prepared. As shown in FIG. 3, the mat member 50 is formed with an end face 50c at one end in the longitudinal direction and an end face 50d at the other end inclined. Here, in FIG. 3 showing the mat member 50, FIG. 3 (a) shows the upper surface, and 3 (b) shows the side surface. Further, as shown in FIG. 3, the end surface 50c at one end portion has an inclination angle α of 45 ° with respect to the inner peripheral surface 50a. This inclination angle α is an angle formed between the tangential direction of the outer peripheral surface of the outer peripheral material layer 4 and the end surface 50 c when the mat member 50 is wound around the outer peripheral surface of the outer peripheral material layer 4. The inclination angle formed by the end surface 50d of the other end portion with respect to the outer peripheral surface 50b was also the same as the angle α formed by the end surface 50c with respect to the inner peripheral surface 50a.

  Then, the belt-like mat member 50 was wound around the outer peripheral surface of the honeycomb body 2 (outer peripheral material layer 4) along the circumferential direction. Thereby, the mat member 50 completely covered the outer peripheral surface of the outer peripheral material layer 4. Further, the mat member 50 has an end face 50c at one end and an end face 50d at the other end completely in contact with each other.

  Thus, the honeycomb structure 1 of the present example was manufactured.

(Example 2)
This example is a honeycomb structure similar to Example 1 except that the thickness of the mat member 5 is 0.5 mm.

(Example 3)
This example is a honeycomb structure similar to Example 1 except that the thickness of the mat member 5 is 1.0 mm.

(Comparative Example 1)
This comparative example is the honeycomb body 2 of Example 1 described above.

(Comparative Example 2)
This comparative example is the honeycomb body 2 in a state where the outer peripheral material layer 4 of Example 1 is formed.

(Evaluation)
As an evaluation of the honeycomb structures 1 of Examples 1 to 3 and Comparative Examples 1 and 2, each honeycomb structure was subjected to a thermal shock test. Specific test methods are shown below.

  First, a heating furnace capable of adjusting the internal temperature is prepared, and the furnace temperature is heated and held at a predetermined temperature of 500 to 700 ° C. every 50 ° C. When it is confirmed that the furnace temperature is maintained at a predetermined temperature, the honeycomb structure to be tested is placed in the furnace and held for 20 minutes.

  After holding for 20 minutes, the honeycomb structure was taken out from the furnace, kept at room temperature, and rapidly cooled.

  This rapid cooling was observed until the temperature of the honeycomb structure was sufficiently lowered. The observation results are shown in Table 1. In Table 1, the case where cracks could not be confirmed in the honeycomb structure 1 (honeycomb body 2) was indicated by ◯, and the case where cracks were confirmed in the honeycomb structure 1 (honeycomb body 2) was indicated by x.

  As shown in Table 1, the honeycomb structures of Examples 1 to 3 were subjected to a thermal shock that was rapidly cooled by heating to 600 ° C., which is a temperature at which cracks occur in the honeycomb structures of Comparative Examples 1 and 2. However, no cracks could be confirmed. That is, it was confirmed that the honeycomb structures of Examples 1 to 3 in which the mat material having low thermal conductivity was arranged on the outer periphery were excellent in thermal shock resistance. And the honeycomb structure of Example 1 in which the mat material disposed on the outer periphery is as thick as 20 mm has the most excellent thermal shock resistance with no cracks observed even at 700 ° C. thermal shock.

  Next, after the honeycomb structures 1 of Examples 1 to 3 and Comparative Examples 1 and 2 are held at 600 ° C., the center portion of the honeycomb structure 1 when the honeycomb structures 1 are similarly held at room temperature (the axial center portion of the honeycomb structure) Then, the temperature change in the axial length) was measured. The measurement results are shown in FIG.

  As shown in FIG. 4, in the honeycomb structures of Comparative Examples 1 and 2 in which the mat material is not disposed on the outer periphery, the temperature at the center portion immediately decreases. On the other hand, in the honeycomb structure of each example in which the mat material is arranged on the outer periphery, the temperature decrease in the central part is more gradual than in the comparative example. That is, the honeycomb structure of each example does not cause a rapid temperature change (temperature decrease) and does not generate a large temperature gradient. That is, the bias of thermal stress caused by the temperature gradient is eliminated. As a result, the honeycomb structure was not cracked or cracked.

Example 4
In this example, a honeycomb body 2 made of porous ceramics, a sealing portion 3 for sealing cells of the honeycomb body 2, and a peripheral material layer 6 formed on the outer periphery of the honeycomb body 2 made of a mat member and ceramics. Is a honeycomb structure 1 having a substantially cylindrical outer shape. The honeycomb structure of the present example is shown in FIG.

  The honeycomb body 2 and the sealing portion 3 are the same as in the first embodiment.

  The outer peripheral material layer 6 includes a mat member made of a heat-resistant porous body disposed on the outer peripheral surface of the honeycomb body 2, and ceramics that are fired after impregnating the mat member with a slurry in which ceramic particles are dispersed. Become.

  The mat member is the same member as the mat member 5 of the first embodiment. Further, the ceramic is a ceramic similar to the ceramic forming the outer peripheral material layer 4 of the first embodiment.

  The mat member 5 is a porous body made of heat resistant ceramics. In this example, a mat material similar to that used in Example 1 was used.

  In the honeycomb structure 1 of the present example, first, the honeycomb body 2 in which the sealing portion 3 was formed was manufactured. For this production, a conventionally known production method was used.

  A belt-like mat member similar to the mat member 50 of Example 1 was prepared. This mat member was wound around the outer peripheral surface of the honeycomb body 2 along the circumferential direction. Thereby, the mat member completely covered the outer peripheral surface of the honeycomb body 2. In the mat member, the end face of one end part and the end face of the other end part completely contacted.

  Thereafter, a slurry similar to that used for forming the outer peripheral material layer 4 of Example 1 was prepared, and the wound body was immersed in the slurry. By this immersion, the slurry entered the inside of the hole of the mat member.

  When the mat member of the wound body was sufficiently impregnated with the slurry, it was pulled up and fired. The peripheral material layer 6 was formed by this baking.

  Thus, the honeycomb structure 1 of the present example was manufactured.

  The honeycomb structure 1 of the present example was subjected to the same thermal shock test as in Example 1, and the test results are shown in Table 1.

  As shown in Table 1, no cracks were observed in the honeycomb structure of Example 4 even at 700 ° C. as in Example 1. That is, the honeycomb structure of Example 4 is also excellent in thermal shock resistance. That is, as in the honeycomb structure 1 of the present embodiment, even if the outer peripheral material layer 6 is composed of the mat member 60 and ceramics, the outer peripheral material layer 6 can reduce the temperature gradient of the honeycomb body 2.

  As described above, also in the honeycomb structure of the present example, the thermal stress unevenness caused by the temperature gradient due to the outer peripheral material layer 6 is eliminated. As a result, the honeycomb structure 1 of the present example is excellent in thermal shock resistance.

3 is a view showing an end face of a honeycomb structure of Example 1. FIG. 3 is a view showing a cross section in the axial direction of a honeycomb structure of Example 1. FIG. It is the figure which showed the mat member. It is the figure which showed the test result of the heat shock test of an Example and a comparative example. 6 is a view showing an end face of a honeycomb structure of Example 4. FIG.

Explanation of symbols

1: Honeycomb structure 2: Honeycomb body 3: Sealing material 4: Peripheral material layer 5: Mat material 6: Bonding material layer

Claims (8)

A honeycomb substrate made of porous ceramics and having a large number of cells extending in the axial direction;
An outer peripheral material layer made of ceramics formed on the outer periphery of the honeycomb substrate;
A mat member made of a heat-resistant porous material disposed on the outer peripheral surface of the outer peripheral material layer;
A honeycomb structure having
A honeycomb structure characterized in that a thermal conductivity κ1 of the mat member is smaller than a thermal conductivity κ0 of the honeycomb substrate.   The honeycomb structure according to claim 1, wherein the ratio of the thermal conductivity κ1 of the mat member and the thermal conductivity κ0 of the honeycomb base material is 0.8 or less. The mat material is a substantially strip-shaped member arranged on the outer peripheral surface of the outer peripheral material layer along the circumferential direction,
The end surface of one end portion in the circumferential direction of the substantially band-shaped member is inclined with respect to the tangential direction of the outer peripheral material layer, and the end portion of the member adjacent to the inclined end surface is in contact with the end surface. The honeycomb structure according to any one of claims 1 and 2.   4. The honeycomb structure according to claim 3, wherein the mat member has an end surface of the one end portion of 10 to 80 ° with respect to a tangential direction of the outer peripheral material layer. A honeycomb substrate made of porous ceramics and having a large number of cells extending in the axial direction;
A mat member made of a heat-resistant porous material disposed on the outer peripheral surface of the honeycomb substrate;
A ceramic formed by impregnating the mat material with a slurry in which ceramic particles are dispersed, and then firing;
A honeycomb structure having
A honeycomb structure characterized in that a thermal conductivity κ1 of the mat member is smaller than a thermal conductivity κ0 of the honeycomb substrate.   The honeycomb structure according to claim 5, wherein a ratio of a thermal conductivity κ1 of the mat member and a thermal conductivity κ0 of the honeycomb base material is 0.8 or less. The mat material is a substantially strip-shaped member arranged on the outer peripheral surface of the outer peripheral material layer along the circumferential direction,
The end surface of one end portion in the circumferential direction of the substantially band-shaped member is inclined with respect to the tangential direction of the outer peripheral material layer, and the end portion of the member adjacent to the inclined end surface is in contact with the end surface. The honeycomb structure according to any one of claims 5 to 6.   The honeycomb structure according to claim 7, wherein an end surface of the one end portion of the mat member is 10 to 80 degrees with respect to a tangential direction of the outer peripheral material layer.

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