Manufacturing method of honeycomb structure

Abstract

To provide a method for producing a honeycomb structure which can inhibit joining deviation.SOLUTION: A method for producing a honeycomb structure includes: a first step of preparing a honeycomb structure 1 free from slits and forming a slit 12 leaving at least part of an outer peripheral wall 10 or partition wall 11; after the first step, a second step of filling the slit 12 with a joining material 13; and, after the second step, a third step of removing the at least part of the outer peripheral wall 10 or partition wall 11 left in the first step to obtain the honeycomb structure 1 having the dividing slit 12.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a honeycomb structure which serves as a catalyst carrier and also functions as a heater when a voltage is applied thereto. [Background technology]

[0002] In general, there is a demand to raise the exhaust gas temperature, which becomes lower as vehicles are electrified. For example, as shown in the following Patent Document 1, an electrically heated catalyst carrier (EHC) has been proposed, which uses a honeycomb structure as a catalyst carrier and causes the honeycomb structure to self-heat when electricity is passed through it.

[0003] Honeycomb structures are required to withstand thermal shock caused by exhaust gas. For example, as shown in the following Patent Document 2, slits are provided in the honeycomb structure so as to divide the outer peripheral wall, thereby improving the thermal shock resistance of the honeycomb structure. The slits may be provided so as to divide the honeycomb structure in a cross section perpendicular to the axial direction of the honeycomb structure. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 9-103684 [Patent Document 2] Patent No. 6126434 Summary of the Invention [Problem to be solved by the invention]

[0005] Conventionally, a honeycomb structure having slits for dividing the honeycomb structure as described in Patent Document 2 has been produced by first dividing the honeycomb structure into two halves and then bonding them together with a bonding material. In this method, the honeycomb structure is first divided into two halves and then bonded together with a bonding material, which can cause shape deterioration due to bonding misalignment. Shape deterioration due to bonding misalignment can cause a decrease in canning ability or a decrease in strength of the honeycomb structure.

[0006] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a manufacturing method for a honeycomb structure capable of suppressing joint misalignment. [Means for solving the problem]

[0007] The method for manufacturing a honeycomb structure according to the present invention is a method for manufacturing a honeycomb structure made of ceramics having an outer peripheral wall and partition walls disposed inside the outer peripheral wall and partitioning a plurality of cells forming flow paths extending from one end face to the other end face, the honeycomb structure being provided with slits dividing the honeycomb structure in a cross section perpendicular to the axial direction of the honeycomb structure, the method comprising the steps of: preparing a honeycomb structure before the slits are formed; At the position where the slit is formed Outer circumference All the way from one end of a wall to the other a first step of forming a slit while leaving a periphery of the slit; a second step of filling the slit with a bonding material after the first step; and a second step of filling the periphery of the slit after the second step. Wall The method includes a third step of removing and dividing the honeycomb structure to obtain a honeycomb structure having slits. Effect of the Invention

[0008] According to the manufacturing method of the honeycomb structure of the present invention, a slit is formed while leaving at least a portion of the outer peripheral wall or partition wall, and after filling the slit with bonding material, at least a portion of the remaining outer peripheral wall or partition wall is removed, thereby suppressing bonding misalignment. [Brief description of the drawings]

[0009] [Figure 1]1 is a perspective view showing a honeycomb structure manufactured by a manufacturing method of a honeycomb structure according to an embodiment of the present invention; [Diagram 2] FIG. 2 is an explanatory diagram showing a manufacturing method of the honeycomb structure shown in FIG. 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the embodiments for carrying out the present invention will be described with reference to the drawings. The present invention is not limited to each embodiment, and the components can be modified and embodied without departing from the gist of the present invention. In addition, various inventions can be formed by appropriately combining multiple components disclosed in each embodiment. For example, some components may be deleted from all the components shown in the embodiments. Furthermore, components of different embodiments may be appropriately combined.

[0011] FIG. 1 is a perspective view showing a honeycomb structure 1 manufactured by a manufacturing method of a honeycomb structure 1 according to an embodiment of the present invention. The honeycomb structure 1 shown in FIG. 1 is a columnar member made of ceramics, and has an outer peripheral wall 10 and partition walls 11 arranged inside the outer peripheral wall 10 and partitioning a plurality of cells 11a forming flow paths extending from one end face to the other end face. The columnar shape can be understood as a three-dimensional shape having a thickness in the extension direction of the cells 11a (axial direction of the honeycomb structure 1). The ratio (aspect ratio) of the axial length of the honeycomb structure 1 to the diameter or width of the end face of the honeycomb structure 1 is arbitrary. The columnar shape may also include a shape (flat shape) in which the axial length of the honeycomb structure 1 is shorter than the diameter or width of the end face.

[0012] The outer shape of the honeycomb structure 1 is not particularly limited as long as it is columnar, and may be other shapes such as a columnar shape with a circular end face (cylindrical shape), a columnar shape with an oval end face, a columnar shape with a polygonal end face (quadragonal, pentagonal, hexagonal, heptagonal, octagonal, etc.), etc. The size of the honeycomb structure 1 is set to 2000 to 20000 mm2 in order to increase heat resistance (suppress cracks in the circumferential direction of the outer peripheral wall). 2It is preferable that the thickness is 5000 to 15000 mm. 2 It is more preferable that:

[0013] Although there is no limitation on the shape of the cells in a cross section perpendicular to the extension direction of the cells 11a, a rectangle, a hexagon, an octagon, or a combination of these is preferable. Among these, a rectangle and a hexagon are preferable. By making the cell shape like this, the pressure loss when exhaust gas flows through the honeycomb structure 1 is reduced, and the purification performance of the catalyst is excellent. From the viewpoint of easily achieving both structural strength and heating uniformity, a rectangle is particularly preferable.

[0014] The thickness of the partition walls 11 that define the cells 11a is preferably 0.1 to 0.3 mm, and more preferably 0.15 to 0.25 mm. When the thickness of the partition walls 11 is 0.1 mm or more, it is possible to suppress a decrease in the strength of the honeycomb structure 1. When the thickness of the partition walls 11 is 0.3 mm or less, it is possible to suppress an increase in pressure loss when exhaust gas flows through the honeycomb structure 1 when the honeycomb structure 1 is used as a catalyst carrier to support a catalyst. In the present invention, the thickness of the partition walls 11 is defined as the length of a portion that passes through the partition walls 11, of a line segment that connects the centers of gravity of adjacent cells 11a in a cross section perpendicular to the extension direction of the cells 11a.

[0015] The honeycomb structure 1 has a cell density of 40 to 150 cells / cm in a cross section perpendicular to the flow path direction of the cells 11a. 2 Preferably, the cell density is 70 to 100 cells / cm. 2 By setting the cell density in this range, it is possible to increase the purification performance of the catalyst while reducing the pressure loss when exhaust gas flows through it. 2 If the cell density is 150 cells / cm or more, the catalyst carrying area is sufficiently secured. 2When the honeycomb structure 1 is used as a catalyst carrier to support a catalyst, the pressure loss caused when exhaust gas flows therethrough is prevented from becoming too large if the honeycomb structure 1 is used as a catalyst carrier to support a catalyst, and the cell density is a value obtained by dividing the number of cells by the area of ​​one bottom surface portion of the honeycomb structure 1 excluding the outer peripheral wall 10 portion.

[0016] Providing the outer peripheral wall 10 of the honeycomb structure 1 is useful from the viewpoint of ensuring the structural strength of the honeycomb structure 1 and suppressing leakage of the fluid flowing through the cells 11a from the outer peripheral wall 10. Specifically, the thickness of the outer peripheral wall 10 is preferably 0.05 mm or more, more preferably 0.10 mm or more, and even more preferably 0.15 mm or more. However, if the outer peripheral wall 10 is made too thick, it becomes too strong, and the strength balance with the partition walls 11 is lost, resulting in a decrease in thermal shock resistance. Therefore, the thickness of the outer peripheral wall 10 is preferably 1.0 mm or less, more preferably 0.7 mm or less, and even more preferably 0.5 mm or less. Here, the thickness of the outer peripheral wall 10 is defined as the thickness in the normal direction to the tangent of the outer peripheral wall 10 at the measurement point when the portion of the outer peripheral wall 10 to be measured for thickness is observed in a cross section perpendicular to the extension direction of the cells.

[0017] The honeycomb structure 1 is preferably made of ceramics and has electrical conductivity. The electrical resistivity of the honeycomb structure 1 is not particularly limited as long as it can generate heat by Joule heat when an electric current is applied, but is preferably 0.1 to 200 Ωcm, and more preferably 1 to 200 Ωcm. In the present invention, the electrical resistivity of the honeycomb structure 1 is a value measured at 25° C. by a four-terminal method.

[0018] The material of the honeycomb structure 1 is not limited, and may be selected from the group consisting of oxide ceramics such as alumina, mullite, zirconia, and cordierite, and non-oxide ceramics such as silicon carbide, silicon nitride, and aluminum nitride. A silicon carbide-metal silicon composite material, a silicon carbide / graphite composite material, and the like may also be used. Among these, from the viewpoint of achieving both heat resistance and electrical conductivity, it is preferable that the material of the honeycomb structure 1 contains a silicon-silicon carbide composite material or a ceramic containing silicon carbide as a main component. When the material of the honeycomb structure 1 is said to contain a silicon-silicon carbide composite material as a main component, it means that the honeycomb structure 1 contains 90 mass% or more of the silicon-silicon carbide composite material (total mass) of the entirety. Here, the silicon-silicon carbide composite material contains silicon carbide particles as aggregate and silicon as a binder for binding the silicon carbide particles, and it is preferable that a plurality of silicon carbide particles are bound by silicon so as to form pores between the silicon carbide particles. When the material of the honeycomb structure 1 is said to be mainly composed of silicon carbide, it means that the honeycomb structure 1 contains silicon carbide (total mass) in an amount of 90 mass% or more of the entire material.

[0019] When the honeycomb structure 1 contains a silicon-silicon carbide composite material, the ratio of the "mass of silicon as a binder" contained in the honeycomb structure 1 to the sum of the "mass of silicon carbide particles as aggregate" contained in the honeycomb structure 1 and the "mass of silicon as a binder" contained in the honeycomb structure 1 is preferably 10 to 40 mass%, and more preferably 15 to 35 mass%.

[0020] The partition walls 11 may be porous. When the partition walls 11 are porous, the porosity of the partition walls 11 is preferably 35 to 60%, and more preferably 35 to 45%. The porosity is a value measured by a mercury porosimeter.

[0021] The average pore diameter of the partition walls 11 of the honeycomb structure 1 is preferably from 2 to 15 μm, and more preferably from 4 to 8 μm. The average pore diameter is a value measured by a mercury porosimeter.

[0022] The honeycomb structure 1 has slits 12 that divide the honeycomb structure 1 in a cross section perpendicular to the axial direction of the honeycomb structure 1. The slits 12 extend linearly from one end to the other end of the honeycomb structure 1 in the radial or width direction of the honeycomb structure 1. The slits 12 also extend linearly in the axial direction of the honeycomb structure 1 from one end face to the other end face of the honeycomb structure 1.

[0023] The slits 12 are filled with a bonding material 13. The bonding material 13 is preferably filled in at least a part of the space of the slits 12. The bonding material 13 is preferably filled in 50% or more of the space of the slits 12, and more preferably filled in the entire space of the slits 12. In the embodiment shown in FIG. 1, the bonding material 13 is filled in the entire space of the slits 12, forms flat surfaces integral with both end faces of the honeycomb structure 1, and forms a curved surface integral with the outer peripheral wall 10 of the honeycomb structure 1. However, the bonding material 13 may be filled up to a position on the inside in the axial direction from the end faces of the honeycomb structure 1, or may be filled up to a position on the inside in the radial direction or width direction from the outer peripheral wall 10 of the honeycomb structure 1.

[0024] When the main component of the honeycomb structure 1 is silicon carbide or a silicon metal-silicon carbide composite material, the bonding material 13 preferably contains 20 mass % or more, and more preferably 20 to 70 mass % of silicon carbide. This allows the thermal expansion coefficient of the bonding material 13 to be close to that of the honeycomb structure 1, thereby improving the thermal shock resistance of the honeycomb structure 1. The bonding material 13 may contain 30 mass % or more of silica, alumina, etc.

[0025] Although not shown in the figure, a pair of electrode layers extending in a band shape in the flow direction of the cells 11a are provided on the outer surface of the outer wall 10 of the honeycomb structure 1, and electrode terminals can be provided on these electrode layers. A voltage can be applied to the honeycomb structure 1 through these electrode terminals and electrode layers to cause the honeycomb structure 1 to generate heat.

[0026] From the viewpoint of making it easy to pass electricity through the electrode layers, the electrical resistivity of the electrode layers is preferably 1 / 200 or more and 1 / 10 or less of the electrical resistivity of the honeycomb structure 1 .

[0027] The material of the electrode layer may be a conductive ceramic, a metal, or a composite material (cermet) of a metal and a conductive ceramic. Examples of the metal include a single metal such as Cr, Fe, Co, Ni, Si, or Ti, or an alloy containing at least one metal selected from the group consisting of these metals. Examples of the conductive ceramic include, but are not limited to, silicon carbide (SiC), and metal compounds such as metal silicides such as tantalum silicide (TaSi2) and chromium silicide (CrSi2).

[0028] In the manufacturing method of the honeycomb structure 1 having the electrode layer, first, an electrode layer forming raw material containing a ceramic raw material is applied to the side surface of the dried honeycomb body, and then dried to form a pair of unfired electrode layers extending in a band shape in the flow direction of the cells on the outer surface of the outer wall, sandwiching the central axis of the dried honeycomb body, to produce a dried honeycomb body with an unfired electrode layer. Next, the dried honeycomb body with the unfired electrode layer is fired to produce a fired honeycomb body having a pair of electrode layers. This produces the honeycomb structure 1 having the electrode layer.

[0029] Next, Fig. 2 is an explanatory diagram showing a manufacturing method of the honeycomb structure 1 for manufacturing the honeycomb structure 1 of Fig. 1. The honeycomb structure 1 of Fig. 1 can be manufactured through a first step shown in Fig. 2(a), a second step shown in Fig. 2(b), a third step shown in Fig. 2(c), and a fourth step shown in Fig. 2(d).

[0030] As shown in (a) of FIG. 2, in the first step, a honeycomb structure 1 before slit formation is prepared, and slits 12 are formed while leaving at least a part of the outer peripheral wall 10 or partition wall 11. The slits 12 can be formed, for example, by cutting the outer peripheral wall 10 or partition wall 11. At this time, it is preferable to leave at least a part of the outer peripheral wall 10 or partition wall 11 so that both sides of the slit 12 of the honeycomb structure 1 are connected by the outer peripheral wall 10 or partition wall 11. In other words, it is preferable that at least a part of the outer peripheral wall 10 or partition wall 11 is left on both sides of the slit 12 in the radial direction, width direction, or axial direction. This is to suppress the occurrence of collapse of the honeycomb structure 1 after the slit 12 is formed in the first step. As shown in (a) of FIG. 2, it is more preferable to leave at least a part of the outer peripheral wall 10. More specifically, it is more preferable to leave the entire outer peripheral wall 10 at the position where the slit 12 is formed (the outer peripheral wall 10 is left over the entire axial area at both sides in the radial direction or width direction of the honeycomb structure 1). This is to prevent the honeycomb structure 1 from collapsing after the first step by leaving all of the outer peripheral walls 10, which have a relatively high strength. In addition, as shown in FIG. 2(a), it is preferable to remove all of the partition walls 11 at the positions where the slits 12 are to be formed. This is to reduce the amount of work in the subsequent third step. However, unlike the embodiment shown in FIG. 2(a), the partition walls 11 may be left instead of the outer peripheral walls 10. When part of the partition walls 11 is left, all of the outer peripheral wall 10 at the positions where the slits 12 are to be formed may be removed, or at least part of the outer peripheral wall 10 at the same positions may be further left. The position where part of the outer peripheral wall 10 or the partition walls 11 is left may be only a part in the radial or width direction, or only a part in the axial direction.

[0031] 2(b) is performed after the first step. In the second step, the slits 12 formed in the first step are filled with a bonding material 13. The bonding material 13 can be filled into the slits 12 by pressure using a tool such as a syringe.

[0032] The third step shown in FIG. 2(c) is performed after the second step. In the third step, at least a part of the outer peripheral wall 10 or the partition wall 11 remaining in the first step is removed to obtain a honeycomb structure 1 having slits 12 that divide the honeycomb structure 1. FIG. 2(c) shows an embodiment in which the outer peripheral wall 10 remaining in the first step is removed to form grooves 14 extending in the axial direction of the honeycomb structure 1. The parts of the honeycomb structure 1 divided by the slits 12 are bonded by a part of the outer peripheral wall 10 or the partition wall 11 or a bonding material 13 through the first to third steps. This makes it possible to suppress bonding misalignment compared to the case in which at least a part of the outer peripheral wall 10 or the partition wall 11 is not left in the first step.

[0033] The third step is preferably performed after the bonding material 13 filled in the second step is dried and solidified. The bonding material 13 may be dried by leaving the honeycomb structure 1 for a predetermined time after filling the slits 12 with the bonding material 13, or may be dried using equipment such as a drying furnace.

[0034] The fourth step shown in Fig. 2(d) is carried out after the third step. In the fourth step, a bonding material 13 is filled into the portion from which at least a portion of the outer peripheral wall 10 or the partition wall 11 has been removed in the third step. Fig. 2(d) shows an embodiment in which the bonding material 13 is filled into grooves 14 extending in the axial direction of the honeycomb structure 1 so as to form a curved surface integral with the outer peripheral wall 10 of the honeycomb structure 1. This fourth step is not essential, and the manufacture of the honeycomb structure 1 may be completed in the third step.

[0035] In the manufacturing method of the honeycomb structure 1 according to the present embodiment, the slits 12 are formed leaving at least a part of the outer peripheral wall 10 or the partition walls 11, and the slits 12 are filled with the bonding material 13, and then at least a part of the remaining outer peripheral wall 10 or the partition walls 11 is removed, thereby suppressing the occurrence of bonding misalignment. This makes it possible to suppress deterioration of the shape of the honeycomb structure 1 and to avoid a decrease in the canning property or the strength of the honeycomb structure 1.

[0036] Furthermore, since at least a portion of the outer peripheral wall 10 is left in the first step, it is possible to more reliably prevent the joining from becoming misaligned.

[0037] In addition, after the third step, the bonding material 13 is filled into the area where at least a portion of the outer wall 10 or the partition wall 11 has been removed, so that the bonding material 13 can be filled into the entire slit 12, thereby improving the strength of the honeycomb structure 1. [Explanation of symbols]

[0038] 1: Honeycomb structure 10:Outer wall 11: Bulkhead 11a: Cell 12: Slit 13: Bonding material

Claims

1. A method for manufacturing a honeycomb structure, comprising the steps of: manufacturing a honeycomb structure made of ceramics, the honeycomb structure having an outer peripheral wall and partition walls disposed inside the outer peripheral wall and partitioning a plurality of cells forming flow paths extending from one end face to the other end face; and manufacturing the honeycomb structure having slits dividing the honeycomb structure in a cross section perpendicular to an axial direction of the honeycomb structure, a first step of preparing the honeycomb structure before forming a slit, and forming the slit while leaving the entire outer peripheral wall from the one end face to the other end face at a position where the slit is to be formed; A second step of filling the slit with a bonding material after the first step; and A third step of removing the outer peripheral wall remaining in the first step after the second step to obtain the honeycomb structure having the dividing slits. Including, A method for manufacturing a honeycomb structure.

2. A fourth step of filling the portion from which the outer peripheral wall has been removed with the bonding material after the third step. Further comprising: A method for manufacturing a honeycomb structure according to claim 1.

3. The honeycomb structure has a pair of electrode layers provided on the outer surface of the outer wall. The method for manufacturing a honeycomb structure according to claim 1 or 2.

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