Cylindrical member for fluid treatment device and manufacturing method of cylindrical member for fluid treatment device

Abstract

To provide a cylindrical member for a fluid treatment device capable of suppressing peeling of an insulation layer.SOLUTION: A cylindrical member 3 for a fluid treatment device includes a cylindrical body 33 and an insulation layer 34. The surface of the cylindrical body 33 is provided with a smooth reference surface 35 and a rough surface 36 where a plurality of concave parts 36a are formed. A boundary surface of the cylindrical body 33 and the insulation layer 34 is formed with a space layer 37 partially. When a reference line RL passing through a most recessed point 36a of the rough surface 36 and parallel to the reference surface 35 is drawn in a cross-sectional image of an inner peripheral surface 33a of the cylindrical body 33, and a region Re with the thickness of 20 μm and the width of 120 μm is set toward the inside of the cylindrical body 33 from the reference line RL, a space layer ratio (VA / (BA+IA+VA)) is 25% or less, which is obtained by dividing an area (VA) of the space layer 37 in the region Re by a sum total of an area (BA) of the cylindrical body 33 in the region Re, an area (IA) of the insulation layer 34 in the region Re, and an area (VA) of the space layer 37 in the region Re.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a cylindrical member for a fluid treatment device used in a fluid treatment device for treating a fluid and a method for manufacturing the cylindrical member for the fluid treatment device.

Background Art

[0002] For example, in an automobile or the like, in order to highly efficiently purify exhaust gas from the start of engine operation, the use of a fluid treatment device that can be electrically heated has been studied. Such a fluid treatment device includes a metal cylindrical member (can or can body) and an electrically heated carrier disposed inside the cylindrical member, and heats the electrically heated carrier by energization so that the temperature of the catalyst supported on the electrically heated carrier can be raised to an active temperature suitable for purification of exhaust gas.

[0003] When the electrically heated carrier is in electrical contact with the metal cylindrical member, when a voltage is applied to the electrically heated carrier, an electric current also flows through the cylindrical member, resulting in energy loss. Therefore, as in Patent Document 1 below, a technique of protecting the inside of the cylindrical member with an insulating material for the purpose of electrically protecting the cylindrical member is known. Patent Document 1 describes "a method for manufacturing a cylindrical member for an exhaust gas treatment device having a metal cylindrical main body and an insulating layer containing glass provided on at least the inner peripheral surface of the cylindrical main body, the method including a step of spraying a coating liquid for forming an insulating layer on the inner peripheral surface of the cylindrical main body to form a coating film, and a step of firing the coating film to obtain the insulating layer, wherein the spraying is performed while rotating the cylindrical main body about its longitudinal axis as a rotation axis".

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When attempting to manufacture a cylindrical member for a fluid processing device by the method described in Patent Document 1, peeling of the insulating layer sometimes occurred when the cylindrical member was heated. As a result of various investigations by the present inventors, it was concluded that the peeling of the insulating layer was caused by the formation of a large space layer at the interface between the insulating layer and the cylindrical body.

[0006] In particular, in Patent Document 1 described above, a coating film is formed by spraying a coating liquid for forming an insulating layer. For this reason, it is considered that many bubbles are contained in the coating film, and a large space layer is likely to be formed due to these bubbles. In order to suppress the bubbles in the coating film formed by spraying, another method of forming a coating film by immersing the cylindrical body in the coating liquid for forming an insulating layer was attempted. However, due to reasons such as insufficient wettability of the coating liquid for forming an insulating layer with respect to the cylindrical body, there was room for improvement in suppressing the formation of the space layer.

[0007] The present invention has been made to solve the above-described problems, and one of its objects is to provide a cylindrical member for a fluid processing device capable of suppressing peeling of the insulating layer. Further, one of the objects of the present invention is to provide a method for manufacturing a cylindrical member for a fluid processing device capable of more reliably manufacturing a cylindrical member for a fluid processing device capable of suppressing peeling of the insulating layer.

Means for Solving the Problems

[0008] Item 1. The present invention, in one embodiment, is a cylindrical member for a fluid processing device including a metallic cylindrical main body and an insulating layer including glass provided on the inner peripheral surface of the cylindrical main body. On the surface of the cylindrical main body, a smooth reference surface and a rough surface with a plurality of recesses are provided. The insulating layer is provided at least on the rough surface, and a space layer is partially formed at the interface between the cylindrical main body and the insulating layer. In a cross-sectional image of the inner peripheral surface of the cylindrical main body, when a reference line passing through the deepest recessed point of the rough surface and parallel to the reference surface is drawn, and a region having a thickness of 20 μm and a width of 120 μm is set from the reference line toward the inside of the cylindrical main body, the space layer rate (VA / (BA + IA + VA)), where the area (VA) of the space layer in the region is divided by the total value of the area (BA) of the cylindrical main body in the region, the area (IA) of the insulating layer in the region, and the area (VA) of the space layer in the region, is 25% or less. The present invention relates to a cylindrical member for a fluid processing device.

[0009] Item 2. The present invention may relate to the cylindrical member for a fluid processing device according to Item 1, wherein the thickness of the insulating layer is 30 μm or more and 800 μm or less.

[0010] Item 3. The present invention, in one embodiment, is a method for manufacturing a cylindrical member for a fluid processing device having a metallic cylindrical main body and an insulating layer including glass provided at least on the inner peripheral surface of the cylindrical main body, the method including: kneading a slurry raw material including a wetting agent, a solvent, and a glass source to produce a slurry as a coating liquid for forming the insulating layer; after producing the slurry, immersing the cylindrical main body in the slurry stored in a treatment tank to form a coating film on at least the inner peripheral surface of the cylindrical main body; and after forming the coating film, baking the coating film to obtain the insulating layer. The present invention relates to a method for manufacturing a cylindrical member for a fluid processing device.

[0011] Item 4. The present invention may relate to the method for manufacturing a cylindrical member for a fluid processing device according to Item 3, wherein the wetting agent is a nonionic surfactant.

[0012] Item 5. The present invention may relate to a method for manufacturing a cylindrical member for a fluid treatment device according to Item 3 or 4, further including a step of applying centrifugal force to a slurry in a vacuum atmosphere after preparing the slurry and before putting the slurry into a treatment tank to remove bubbles in the slurry.

[0013] Item 6. The present invention may relate to a method for manufacturing a cylindrical member for a fluid treatment device according to Item 5, wherein in the step of removing bubbles in the slurry, the container containing the slurry is rotated and revolved, the revolution speed of the container is 700 rpm or more and 1600 rpm or less, the rotation speed of the container is 350 rpm or more and 750 rpm or less, and the atmospheric pressure in the container is 50 kPa or less.

[0014] Item 7. The present invention may relate to a method for manufacturing a cylindrical member for a fluid treatment device according to Item 5 or 6, wherein in the step of removing bubbles in the slurry, the container containing the slurry is rotated and revolved, and the revolution speed of the container is faster than the rotation speed of the container.

[0015] Item 8. The present invention may relate to a method for manufacturing a cylindrical member for a fluid treatment device according to any one of Items 3 to 7, wherein the viscosity of the slurry in the treatment tank is 1 dPa·s or more.

[0016] Item 9. The present invention may relate to a method for manufacturing a cylindrical member for a fluid treatment device according to any one of Items 3 to 8, wherein a wetting agent is contained in an amount of 2.0% or more based on the glass mass part of the slurry.

Effect of the Invention

[0017] According to one embodiment of the cylindrical member for a fluid treatment device of the present invention, since the space layer ratio (VA / (BA + IA + VA)) is 25% or less, peeling of the insulating layer can be suppressed. Further, according to one embodiment of the method for manufacturing a cylindrical member for a fluid treatment device of the present invention, a slurry raw material containing a wetting agent, a solvent, and a glass source is kneaded to prepare a slurry as a coating liquid for forming an insulating layer, so that a cylindrical member for a fluid treatment device capable of suppressing peeling of the insulating layer can be manufactured more reliably.

Brief Description of the Drawings

[0018]

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Mode for Carrying Out the Invention

[0019] Hereinafter, 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 components can be modified and embodied without departing from the gist thereof. Also, various inventions can be formed by appropriately combining a plurality of components disclosed in each embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, components of different embodiments may be appropriately combined.

[0020] FIG. 1 is a cross-sectional view of a fluid processing apparatus 1 including a cylindrical member 3 for a fluid processing apparatus according to an embodiment of the present invention, and FIG. 2 is a perspective view showing the honeycomb structure 20 of FIG. 1. The cylindrical member 3 for a fluid processing apparatus in the embodiment of the present invention can be used in the fluid processing apparatus 1 as shown in FIG. 1. The fluid processing apparatus 1 is an apparatus for processing a fluid. The fluid processing apparatus 1 is provided, for example, on an exhaust path of an automobile or the like, and can be used for processing or purifying exhaust gas discharged from an engine. However, the use of the fluid processing apparatus 1 is not limited to the purification of exhaust gas, and it may be used for processing other fluids such as heating a fluid. Hereinafter, the "cylindrical member for a fluid processing apparatus" may be simply referred to as a "cylindrical member".

[0021] As shown in FIG. 1, the fluid processing apparatus 1 may include an electrically heated carrier 2, a cylindrical member 3, and a buffer member 4.

[0022] The electrically heated carrier 2 may have a honeycomb structure 20 and a metal electrode 21 connected to the honeycomb structure 20. Although not shown, an external power source such as a battery may be connected to the metal electrode 21 via a power cable. By applying a voltage to the honeycomb structure 20 through the metal electrode 21, the honeycomb structure 20 can be heated to generate heat. Thereby, the catalyst supported on the honeycomb structure 20 can be heated to the activation temperature before the engine is started.

[0023] As particularly shown in FIG. 2, the honeycomb structure 20 has a honeycomb structure portion 200 and at least one electrode layer 201.

[0024] The honeycomb structure portion 200 is a columnar member made of ceramics, and has an outer peripheral wall 202 and partition walls 203 that are disposed inside the outer peripheral wall 202 and partition a plurality of cells 203a that form 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 extending direction of the cells 203a (axial direction of the honeycomb structure portion 200). The ratio (aspect ratio) of the axial length of the honeycomb structure portion 200 to the diameter or width of the end face of the honeycomb structure portion 200 is arbitrary. The columnar shape may include a shape (flat shape) in which the axial length of the honeycomb structure portion 200 is shorter than the diameter or width of the end face.

[0025] The outer shape of the honeycomb structure portion 200 is not particularly limited as long as it is columnar. For example, it can 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 (quadrilateral, pentagonal, hexagonal, heptagonal, octagonal, etc.) end face. Also, the size of the honeycomb structure portion 200 is preferably such that the area of the end face is 2000 to 65000 mm 2 and more preferably 5000 to 25000 mm 2 in order to enhance heat resistance (suppress cracks entering in the circumferential direction of the outer peripheral wall 202). A plurality of columnar honeycomb structures with polygonal end faces can also be joined and used.

[0026] There is no limitation on the shape of the cells 203a in a cross section orthogonal to the extending direction of the cells 203a, but it is preferably a quadrilateral, hexagonal, octagonal, or a combination thereof. Among these, a quadrilateral and a hexagon are more preferable. By making the cell shape like this, the pressure loss when exhaust gas flows through the honeycomb structure portion 200 becomes small, and the purification performance of the catalyst becomes excellent.

[0027] The thickness of the partition wall 203 that forms the partition of the cell 203a is preferably 0.1 to 0.8 mm, and more preferably 0.1 to 0.6 mm. When the thickness of the partition wall 203 is 0.1 mm or more, it is possible to suppress a decrease in the strength of the honeycomb structure portion 200. When the thickness of the partition wall 203 is 0.8 mm or less, when the honeycomb structure portion 200 is used as a catalyst carrier and a catalyst is supported, it is possible to suppress an increase in the pressure loss when the exhaust gas flows. In the present invention, the thickness of the partition wall 203 is defined as the length of the portion passing through the partition wall 203 among the line segments connecting the centers of gravity of adjacent cells 203a in a cross section orthogonal to the extending direction of the cell 203a.

[0028] In a cross section orthogonal to the extending direction of the cell 203a, the honeycomb structure portion 200 has a cell density of 4 to 150 cells / cm 2 and is preferably 7 to 100 cells / cm 2 more preferably. By setting the cell density within such a range, it is possible to improve the purification performance of the catalyst while reducing the pressure loss when the exhaust gas flows. When the cell density is 4 cells / cm 2 or more, a sufficient catalyst support area is ensured. When the cell density is 150 cells / cm 2 or less, when the honeycomb structure portion 200 is used as a catalyst carrier and a catalyst is supported, it is possible to suppress an excessive increase in the pressure loss when the exhaust gas flows. The cell density is a value obtained by dividing the number of cells by the area of one end face portion of the honeycomb structure portion 200 excluding the outer peripheral wall 202 portion.

[0029] Providing the outer peripheral wall 202 of the honeycomb structure portion 200 is useful from the viewpoints of ensuring the structural strength of the honeycomb structure portion 200 and suppressing leakage of the fluid flowing through the cell 203a from the outer peripheral wall 202. Specifically, the thickness of the outer peripheral wall 202 is preferably 0.05 mm or more, more preferably 0.10 mm or more, and still more preferably 0.15 mm or more. However, if the outer peripheral wall 202 is made too thick, the strength becomes too high, the strength balance with the partition wall 203 is lost, and the thermal shock resistance decreases. Therefore, the thickness of the outer peripheral wall 202 is preferably 1.0 mm or less, more preferably 0.7 mm or less, and still more preferably 0.5 mm or less. Here, the thickness of the outer peripheral wall 202 is defined as the thickness in the normal direction with respect to the tangent line of the outer peripheral wall 202 at the measurement location when observing the location of the outer peripheral wall 202 where the thickness is to be measured in a cross section orthogonal to the extending direction of the cell 203a.

[0030] The honeycomb structure portion 200 is made of ceramics and preferably has conductivity. The honeycomb structure portion 200 has no particular limitation on the volume resistivity as long as it can generate heat by Joule heat when energized, but it is preferably 0.1 to 200 Ωcm, and more preferably 1 to 200 Ωcm. In the present invention, the volume resistivity of the honeycomb structure portion 200 is the value measured at 25°C by the four-terminal method.

[0031] As the material of the honeycomb structure portion 200, although not limited, it can 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. Also, a silicon carbide - silicon composite material, a silicon carbide / graphite composite material, etc. can be used. Among these, from the viewpoint of achieving both heat resistance and conductivity, it is preferable that the material of the honeycomb structure portion 200 contains a silicon - silicon carbide composite material or ceramics mainly composed of silicon carbide. When the material of the honeycomb structure portion 200 is mainly composed of a silicon - silicon carbide composite material, it means that the honeycomb structure portion 200 contains 90 mass% or more of the silicon - silicon carbide composite material (total mass) in the whole. Here, the silicon - silicon carbide composite material contains silicon carbide particles as aggregates 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 portion 200 is mainly composed of silicon carbide, it means that the honeycomb structure portion 200 contains 90 mass% or more of silicon carbide (total mass) in the whole.

[0032] When the honeycomb structure portion 200 contains a silicon - silicon carbide composite material, the ratio of the "mass of silicon carbide particles as aggregates" contained in the honeycomb structure portion 200 to the "mass of silicon as a binder" contained in the honeycomb structure portion 200 with respect to the total of the two is preferably 10 to 40 mass%, and more preferably 15 to 35 mass%.

[0033] The outer peripheral wall 202 and the partition wall 203 may be porous. When they are porous, the porosity of the outer peripheral wall 202 and the partition wall 203 is preferably 35 to 60%, and more preferably 35 to 45%. The porosity is a value measured by a mercury porosimeter. Also, the outer peripheral wall 202 and the partition wall 203 may be dense, and when they are dense, the porosity of the outer peripheral wall 202 and the partition wall 203 may be 10% or less, or may be 5% or less.

[0034] The average pore diameter of the outer peripheral wall 202 and the partition wall 203 of the honeycomb structure portion 200 is preferably 2 to 15 μm, and more preferably 4 to 8 μm. The average pore diameter is a value measured by a mercury porosimeter.

[0035] At least one electrode layer 201 is provided on the outer surface of the outer peripheral wall 202. The electrode layer 201 may extend from one end to the other end of the honeycomb structure portion 200 in the extending direction of the cell 203a. The electrode layer 201, together with the outer peripheral wall 202, constitutes the outer peripheral surface of the honeycomb structure 20.

[0036] One electrode layer 201 may be provided on the entire outer peripheral surface of the honeycomb structure 20. However, in the present embodiment, a pair of electrode layers 201 that are spaced apart from each other in the circumferential direction of the honeycomb structure portion 200 and extend in a strip shape in the extending direction of the cell 203a are provided. In the cross section of the honeycomb structure portion 200 perpendicular to the extending direction of the cell 203a, one of the pair of electrode layers 201 is disposed on the opposite side of the other electrode layer 201 in the pair of electrode layers 201 with the center of the honeycomb structure portion 200 interposed therebetween. In FIG. 2, only one of the pair of electrode layers 201 is shown. In the cross section perpendicular to the extending direction of the cell 203a, 0.5 times the central angle of each electrode layer 201 may be 15 to 89°. Note that the central angle of the electrode layer 201 may be an angle formed by two line segments connecting both ends of the electrode layer 201 and the center of the honeycomb structure portion 200 in the cross section of the honeycomb structure portion 200 perpendicular to the extending direction of the cell 203a. When the honeycomb structure portion 200 is columnar, this angle may be an interior angle of a sector formed by the two line segments and the electrode layer 201.

[0037] The thickness of the electrode layer 201 is preferably 0.01 to 5 mm, and more preferably 0.01 to 3 mm. By setting it within such a range, heat can be generated uniformly. If the thickness of the electrode layer 201 is less than 0.01 mm, the electrical resistance may become high and uniform heat generation may not be possible. If it is more than 5 mm, it may be damaged during canning. Also, if the electrode layer 201 is too thin, as described later, the effect of outer diameter adjustment when varying the outer diameter of the honeycomb structure 20 in the extending direction of the cell 203a due to fluctuations in the thickness of the electrode layer 201 becomes weak. If the electrode layer 201 is too thick, the holding force in the portion without the electrode layer 201 does not work, and it becomes easy to fall off during the vibration test. Further, if the electrode layer 201 is too thin, the resistance value of the electrode layer 201 is not sufficient, current easily flows through the base material (honeycomb structure portion 200), the heat generation distribution becomes unstable, leading to a decrease in purification performance and damage to the base material. On the other hand, if the electrode layer 201 is too thick, current easily flows through the electrode layer 201, and the electrode layer 201 easily generates heat, so the heat generation distribution becomes unstable, leading to a decrease in purification performance and damage to the base material.

[0038] The pair of electrode layers 201 of the present embodiment each have a separation zone 2010, a first partial electrode layer 2011, and a second partial electrode layer 2012 separated by this separation zone 2010. The separation zone 2010 can be a slit provided between the first partial electrode layer 2011 and the second partial electrode layer 2012. The slit may be filled with a material having a higher volume resistivity than the first partial electrode layer 2011 and the second partial electrode layer 2012. The first partial electrode layer 2011 and the second partial electrode layer 2012 are formed in a strip shape having a predetermined width in the circumferential direction of the honeycomb structure portion 200, and the separation zone 2010 is formed in a narrow linear shape narrower than the first partial electrode layer 2011 and the second partial electrode layer 2012. However, the arrangement method of the separation zone 2010, the first partial electrode layer 2011, and the second partial electrode layer 2012 is not limited to this form as long as it can be connected to the metal electrode 21 described later.

[0039] As shown in FIG. 1, the metal electrode 21 is fixed on the electrode layer 201. By applying a voltage to the honeycomb structure portion 200 through the metal electrode 21 and the electrode layer 201, the honeycomb structure portion 200 can be heated.

[0040] From the viewpoint of facilitating the flow of electricity through the electrode layer 201, the volume resistivity of the electrode layer 201 is preferably 1 / 200 or more and 1 / 10 or less of the volume resistivity of the honeycomb structure portion 200.

[0041] As the material of the electrode layer 201, a conductive ceramic, a metal, or a composite material (cermet) of a metal and a conductive ceramic can be used. 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).

[0042] As a method for manufacturing the honeycomb structure 20 having the electrode layer 201, first, an electrode layer forming raw material containing a ceramic raw material is applied to the side surface of the honeycomb green body and dried, and a pair of unfired electrode layers are formed so as to extend in a strip shape in the extending direction of the cell 203a on the outer surface of the outer peripheral wall 202 with the central axis of the honeycomb green body interposed therebetween, thereby producing a honeycomb green body with unfired electrode layers. Next, the honeycomb green body with unfired electrode layers is fired to produce a honeycomb fired body having a pair of electrode layers 201. Thereby, the honeycomb structure 20 having the electrode layer 201 is obtained.

[0043] By supporting a catalyst on the honeycomb structure portion 200, the electric heating carrier 2 can be used as a catalyst body. Examples of the catalyst include noble metal-based catalysts or catalysts other than these. As noble metal-based catalysts, noble metals such as platinum (Pt), palladium (Pd), and rhodium (Rh) are supported on the surface of alumina pores, and a three-way catalyst, an oxidation catalyst, or a NOx storage reduction catalyst (LNT catalyst) containing a promoter such as ceria and zirconia, or an NOx storage reduction catalyst (LNT catalyst) containing an alkaline earth metal and platinum as an NOx storage component are exemplified. As a catalyst that does not use noble metals, an NOx selective reduction catalyst (SCR catalyst) containing copper-substituted or iron-substituted zeolite is exemplified. Further, two or more catalysts selected from these catalysts may be used. Note that there is no particular limitation on the method of supporting the catalyst, and it can be carried out according to the conventional method of supporting the catalyst on the honeycomb structure 20.

[0044] The metal electrode 21 may have a connection portion 210 disposed on the electrode layer 201 and a lead-out portion 211 drawn out from the connection portion 210. Although not shown in detail, the connection portion 210 may be configured in a comb-like shape having a plurality of tooth portions, and some of the plurality of tooth portions may be connected to the first partial electrode layer 2011 (see FIG. 2), and the other tooth portions may be connected to the second partial electrode layer 2012 (see FIG. 2). The connection portion 210 may be formed in an arc shape along the outer peripheral surface of the honeycomb structure 20. The lead-out portion 211 may be erected from one end of the connection portion 210 and drawn out to the outside of the cylindrical member 3, and a power cable may be connected to the lead-out portion 211.

[0045] The cylindrical member 3 is a metal member that holds the honeycomb structure 20. The cylindrical member 3 may also be referred to as a can or a can body. Various metals can be used as the metal constituting the cylindrical member 3, and examples thereof include stainless steel, titanium alloy, copper alloy, aluminum alloy, and brass. Among them, stainless steel is preferable because of its high durability and reliability and low cost.

[0046] The cylindrical member 3 can surround the honeycomb structure 20 in the circumferential direction of the honeycomb structure 20. The inner diameter of the cylindrical member 3 at the outer peripheral position of the honeycomb structure 20 may be constant in the extending direction of the cell 203a. The portion of the cylindrical member 3 with a constant inner diameter may be referred to as the body portion. The outer peripheral position of the honeycomb structure 20 may be understood as the outside of the honeycomb structure 20 in the radial direction of the honeycomb structure 20 and the position between the end faces of the honeycomb structure 20 with respect to the extending direction of the cell 203a.

[0047] The plate thickness of the cylindrical member 3 may be, for example, from 0.1 mm to 10 mm, may be from 0.3 mm to 5 mm, or may be from 0.5 mm to 3 mm from the viewpoint of durability and reliability. The length of the portion of the cylindrical member 3 with a constant inner diameter at the outer peripheral position of the honeycomb structure 20 may be longer than the axial length of the honeycomb structure 20, and may be, for example, from 30 mm to 600 mm, may be from 40 mm to 500 mm, or may be from 50 mm to 400 mm.

[0048] A lead-out opening 30 corresponding to the lead-out portion 211 may be provided on the circumferential surface of the cylindrical member 3, and a power cable can be connected from the outside of the cylindrical member 3 to the lead-out portion 211 through the lead-out opening 30.

[0049] The cylindrical member 3 may be provided with a first end opening 31 and a second end opening 32 spaced apart in the extending direction of the cell 203a. The inner diameters of the first end opening 31 and the second end opening 32 may be smaller than the inner diameter of the cylindrical member 3 at the outer peripheral position of the honeycomb structure 20. Exhaust gas can be introduced into the inside of the cylindrical member 3 from one of the first end opening 31 and the second end opening 32, and the exhaust gas that has passed through the cell 203a of the honeycomb structure 20 inside the cylindrical member 3 can be discharged to the outside of the cylindrical member 3 from the other of the first end opening 31 and the second end opening 32. One of the first end opening 31 and the second end opening 32 into which the exhaust gas is introduced may be referred to as the inlet opening, and the other of the first end opening 31 and the second end opening 32 from which the exhaust gas is discharged may be referred to as the outlet opening. Also, one end face of the honeycomb structure 20 into which the exhaust gas is introduced may be referred to as the inlet end face, and the other end face of the honeycomb structure 20 from which the exhaust gas escapes may be referred to as the outlet end face.

[0050] The buffer member 4 is disposed between the honeycomb structure 20 and the cylindrical member 3. The buffer member 4 may be wound around the outer periphery of the honeycomb structure 20. The buffer member 4 is provided with a through hole 40 corresponding to the lead-out portion 211, and a power cable can be connected to the lead-out portion 211 from the outside of the cylindrical member 3 through the through hole 40. The buffer member 4 may be made of a material that can be compressed in the radial direction of the honeycomb structure 20. Although there is no particular limitation on the material of the buffer member 4, a non-expandable ceramic fiber mat, a thermally expandable mineral material mat, or the like can be used.

[0051] Next, FIG. 3 is an enlarged cross-sectional view of the cylindrical member 3 in region III of FIG. 1, FIG. 4 is an enlarged cross-sectional view of the cylindrical member 3 in region IV of FIG. 3, and FIG. 5 is an enlarged cross-sectional view of the cylindrical member 3 in region V of FIG. 3.

[0052] As particularly shown in FIG. 3, the cylindrical member 3 of the present embodiment has a metal cylindrical main body 33 and an insulating layer 34.

[0053] The cylindrical main body 33 may be understood to refer to the base material on which the insulating layer 34 is provided in the cylindrical member 3. The cylindrical main body 33 can surround the honeycomb structure 20 in the circumferential direction of the honeycomb structure 20 as described above, and may have a lead-out opening 30, a first end opening 31, and a second end opening 32. The metal constituting the cylindrical main body 33 is the same as the metal constituting the cylindrical member 3.

[0054] The insulating layer 34 is provided on the inner peripheral surface 33a of the cylindrical main body 33. By providing such an insulating layer 34, the electrical resistance between the cylindrical main body 33 and the honeycomb structure 20 can be increased or they can be electrically insulated from each other. Thereby, when a voltage is applied to the electrically heated carrier 2, the current flowing through the cylindrical member 3 can be reduced, and the energy loss can be reduced.

[0055] The insulating layer 34 may be provided on the inner peripheral surface 33a of the cylindrical main body 33 at least at the outer peripheral position of the honeycomb structure 20. In the illustrated embodiment, the insulating layer 34 is provided over the entire inner peripheral surface 33a of the cylindrical main body 33. A non-formation region of the insulating layer 34 may be provided outside the end surface of the honeycomb structure 20 with respect to the extending direction of the cell 203a. As in the illustrated embodiment, the insulating layer 34 may be further provided on the outer peripheral surface 33b of the cylindrical main body 33.

[0056] In terms of suppressing leakage of electricity to the surrounding exhaust pipes, the electrical insulation of the insulating layer 34 preferably satisfies JIS standard D5305-3 typically, and the insulation resistance value per unit voltage may be, for example, 100 Ω / V or more. The insulating layer 34 preferably has water impermeability and non-water absorbency. Specifically, the insulating layer 34 is preferably configured to be dense and not allow water to pass through or be absorbed. Being dense means that the porosity of the insulating layer 34 is small, and the porosity of the insulating layer 34 may be, for example, 10% or less, and may be, for example, 8% or less.

[0057] The insulating layer 34 contains glass. The composition of the glass is not particularly limited, and glasses having various compositions can be used. Specific examples of the glass include silicate glass, borosilicate glass, barium glass, boron glass, strontium glass, aluminosilicate glass, soda zinc glass, soda barium glass, etc. These may be used alone or in combination of two or more.

[0058] Although not limited, the insulating layer 34 may contain crystallized glass. In other words, the glass of the insulating layer 34 may be crystallized glass. Crystallized glass is glass in which crystals are precipitated by heating during manufacturing. By the insulating layer 34 containing crystallized glass, an insulating layer 34 that is difficult to soften and deform even at high temperatures (for example, 750 °C or higher) can be obtained. Also, an insulating layer 34 with excellent adhesion to the cylindrical main body 33 can be obtained. Specifically, the difference in the coefficient of thermal expansion from the cylindrical main body 33 (metal) can be reduced, and the thermal stress generated during heating can be reduced.

[0059] Whether crystals are precipitated in the glass, i.e., whether it is a crystallized glass, can be confirmed by X-ray diffraction. Since amorphous glass has no atomic regularity, it does not show distinct diffraction peaks. On the other hand, the precipitated crystals show characteristic diffraction peaks. Although not necessarily limited, the crystallized glass may be a glass with a crystallinity of 50% or more. The crystallized glass may be a glass with a crystallinity of 65% or more, 80% or more, or 90% or more. The crystallinity (%) is obtained from the diffraction pattern obtained by X-ray diffraction to obtain the peak area of the crystalline phase and the peak area of the amorphous phase, and is determined by the following formula. Crystallinity (%) = {Peak area of crystalline phase / (Peak area of crystalline phase + Peak area of amorphous phase)} × 100

[0060] In one embodiment, the glass contains silicon and boron. Silicon can be contained in the glass in the form of SiO2; boron can be contained in the glass in the form of B2O3. Specifically, the glass is a SiO2 - B2O3 based glass (borosilicate glass). The content of silicon in the glass is preferably 5 mol% to 50 mol%, more preferably 7 mol% to 45 mol%, and still more preferably 10 mol% to 40 mol%. The content of boron in the glass is preferably 5 mol% to 60 mol%, more preferably 7 mol% to 57 mol%, and still more preferably 8 mol% to 55 mol%.

[0061] In addition to silicon and boron, the glass may contain other components (metal elements) such as magnesium, barium, lanthanum, zinc, calcium, etc. For example, it may further contain magnesium. Magnesium can be contained in the glass in the form of MgO. In this case, the content of magnesium in the glass is preferably 10 mol% or more, more preferably 15 mol% to 55 mol%. Also, for example, it may further contain barium. Barium can be contained in the glass in the form of BaO. In this case, the content of barium in the glass is preferably 3 mol% to 30 mol%, more preferably 5 mol% to 25 mol%, and still more preferably 6 mol% to 20 mol%.

[0062] In this specification, the element content in the glass is the molar ratio of the atoms of the element when the total amount of all atoms in the glass excluding oxygen atoms is 100 mol%. The amount of atoms of each element in the glass is measured, for example, by inductively coupled plasma (ICP) optical emission spectrometry.

[0063] The thickness of the insulating layer 34 may be 30 μm or more and 800 μm or less. When the thickness of the insulating layer 34 is 30 μm or more, sufficient insulation can be obtained. From the viewpoint of more surely obtaining sufficient insulation, the thickness of the insulating layer 34 is preferably 50 μm or more, more preferably 100 μm or more, and still more preferably 150 μm or more. When the thickness of the insulating layer 34 is 800 μm or less, the pressure on the honeycomb structure 20 can be reduced, and from the viewpoint of preventing damage to the honeycomb structure 20, the thickness of the insulating layer 34 is preferably 600 μm or less.

[0064] As will be described in detail later, the insulating layer 34 can be obtained by forming a coating film on at least the inner peripheral surface 33a of the cylindrical body 33 using a slurry as a coating liquid for forming an insulating layer containing a glass source, and then firing the coating film.

[0065] As shown in FIGS. 4 and 5, on the surface of the cylindrical body 33, a smooth reference surface 35 (see FIG. 4) and a rough surface 36 (see FIG. 5) having a plurality of recesses 36a are provided, and the insulating layer 34 is provided at least on the rough surface 36. In the illustrated embodiment, the insulating layer 34 is also provided on the reference surface 35.

[0066] The rough surface 36 can be formed by a surface treatment such as blasting, for example. The rough surface 36 may be provided on the inner peripheral surface 33a of the cylindrical body 33 at least at the outer peripheral position of the honeycomb structure 20. By providing the insulating layer 34 on the rough surface 36, the adhesion between the cylindrical body 33 and the insulating layer 34 can be improved. Although not limited, the arithmetic mean roughness Ra measured along the circumferential direction of the cylindrical body 33 at the position where the rough surface 36 is provided is preferably 10.0 μm or less, more preferably 7.0 μm or less, and even more preferably 5.0 μm or less. By controlling the arithmetic mean roughness Ra within such a range, the insulating layer 34 can be uniformly formed on the inner peripheral surface 33a of the cylindrical body 33. In this specification, the "arithmetic mean roughness Ra" of the inner peripheral surface 33a of the cylindrical body 33 is measured by a stylus type surface roughness measuring instrument in accordance with JIS B0601:2013.

[0067] The reference surface 35 is a portion that has not been subjected to surface treatment like the rough surface 36. Smoothness is a relative term in comparison with the rough surface 36, and it may be understood that the surface roughness of the reference surface 35 is smaller than the surface roughness of the rough surface 36. There may be, for example, scratches formed on the surface of the metal plate constituting the cylindrical body 33 by rolling or forming processes on the surface of the reference surface 35. As shown in FIGS. 3 and 4, the reference surface 35 may be the outer peripheral surface 33b of the cylindrical body 33.

[0068] Next, FIG. 6 is an image showing the insulating layer 34 on the rough surface 36 of FIG. 5 in more detail. As shown in FIG. 6, a space layer 37 is partially formed at the interface between the cylindrical body 33 and the insulating layer 34. In FIG. 6, the cylindrical body 33 appears as a bright portion, the insulating layer 34 appears as a darker portion than the cylindrical body 33, and the space layer 37 appears as a darker portion than the insulating layer 34.

[0069] At the position where the space layer 37 is formed, the cylindrical main body 33 and the insulating layer 34 are not chemically and physically connected. Chemical connection may include the formation of a chemical bonding layer in which the metal constituting the cylindrical main body 33 and the insulating layer 34 are chemically bonded. The chemical bonding layer may be an oxide layer that shares some elements from both the cylindrical main body 33 and the insulating layer 34. The chemical bonding layer may contain Si, Cr, and O. Physical connection may include the anchor effect caused by the insulating layer 34 entering the recess 36a of the cylindrical main body 33. Therefore, when a large space layer 37 is formed at the interface between the cylindrical main body 33 and the insulating layer 34, peeling of the insulating layer 34 may occur when the cylindrical member 3 is heated.

[0070] As a result of various studies by the inventors, it has been found that peeling of the insulating layer 34 can be suppressed when the size of the space layer 37 within a predetermined region is equal to or less than a certain size. More specifically, in the cross-sectional image of the inner peripheral surface 33a of the cylindrical main body 33 as shown in FIG. 6, a reference line RL parallel to the reference plane 35 and passing through the deepest point 36a of the rough surface 36 is drawn, and when a region Re having a thickness of 20 μm and a width of 120 μm is set from the reference line RL toward the inside of the cylindrical main body 33, the space layer ratio (VA / (BA + IA + VA)), where the area (VA) of the space layer 37 within the region Re is divided by the sum of the area (BA) of the cylindrical main body 33 within the region Re, the area (IA) of the insulating layer 34 within the region Re, and the area (VA) of the space layer 37 within the region Re, is set to 25% or less, it has been found that peeling of the insulating layer 34 can be suppressed. That is, in the cylindrical member 3 of the present embodiment, the space layer ratio is set to 25% or less.

[0071] In particular, when the insulating layer 34 contains crystallized glass, due to the property of the crystallized glass that it is difficult to soften at high temperatures, it is difficult for the inner peripheral surface of the cylindrical main body 33 and the insulating layer to adhere closely, and a large gap is formed at their bonding interface, resulting in a problem that the insulating layer 34 is likely to peel off from the inner peripheral surface of the cylindrical main body 33. Setting the space layer ratio to 25% or less is particularly useful when the insulating layer 34 contains crystallized glass.

[0072] The cross-sectional image of the inner peripheral surface 33a of the cylindrical body 33 may be an image of a scanning electron microscope (SEM) (SEM image). The SEM image may be a backscattered electron image (BSE). The thickness direction of the region Re may be the plate thickness direction of the cylindrical body 33, and the width direction of the region Re may be a direction perpendicular to the plate thickness direction of the cylindrical body 33. The deepest point 36a of the rough surface 36 may not be the deepest part of the entire rough surface 36, but may be the deepest part in the cross-sectional image (within a specific field of view) of the inner peripheral surface 33a to be observed. When the reference plane 35 is the outer peripheral surface 33b of the cylindrical body 33, an SEM image is continuously taken in the plate thickness direction of the cylindrical body 33, a straight line (reference plane 35) along which the outer peripheral surface 33b extends is specified in the SEM image in which the outer peripheral surface 33b is taken, and the reference line RL can be drawn by translating the straight line along which the outer peripheral surface 33b extends to the position passing through the deepest point 36a in the SEM image in which the inner peripheral surface 33a is taken.

[0073] Samples may be collected from a point 15 mm shifted in the upstream direction and a point 15 mm shifted in the downstream direction in which the exhaust gas flows, from the central part at the upper part of the portion where the inner diameter of the cylindrical body 33 is constant. After cutting in the diameter direction, the samples may be further cut to a length of 20 mm, resin-embedded, and mirror-polished. Thereby, a cross-section of the inner peripheral surface 33a of the cylindrical body 33 can be obtained. Imaging of the cross-section may be continuously performed at a magnification of 1000 times from the surface of the insulating layer 34 until the reference plane 35 (smooth surface) of the outer peripheral surface 33b of the cylindrical body 33 appears in the base material direction of the cylindrical body 33. Parallel to the reference plane 35 of the cylindrical body 33, a reference line RL is drawn so as to contact the deepest point 36a of the rough surface 36 of the cylindrical body 33, and a region Re having a thickness of 20 μm and a width of 120 μm is set from the reference line RL toward the inside of the cylindrical body 33, and the area of the space layer 37 existing at the interface between the cylindrical body 33 and the insulating layer 34 may be obtained using image processing software. The area (VA) of the space layer 37 in the region Re may be taken as the area of the black portion in FIG. 6, the area (BA) of the cylindrical body 33 in the region Re may be taken as the area of the white portion in FIG. 6, and the area (IA) of the insulating layer 34 in the region Re may be taken as the area of the gray portion in FIG. 6.

[0074] Using image processing software, binary processing of cross-sectional images can be performed by the fixed threshold method. When viewing a cross-sectional image on a graph (histogram) with the horizontal axis representing brightness and the vertical axis representing area, three peaks appear. It is advisable to use the midpoint between the peaks of the lowest brightness peak and the second lowest brightness peak as the threshold. At this time, the total area of the portion with brightness lower than the threshold is taken as the area (VA) of the space layer 37 in the region Re, and the total area of the portion with brightness equal to or higher than the threshold is taken as the sum value (BA + IA) of the area (BA) of the cylindrical main body 33 and the area (IA) of the insulating layer 34 in the region Re. From these, the space layer ratio (VA / (BA + IA + VA)) can be obtained.

[0075] When the average value of the space layer ratios obtained from the above two samples is 25% or less, it may be determined that the space layer ratio of the cylindrical member 3 is 25% or less.

[0076] Next, FIG. 7 is a flowchart showing a method for manufacturing the cylindrical member 3 for a fluid processing apparatus according to an embodiment of the present invention, FIG. 8 is an explanatory diagram for explaining the action of a wetting agent used in the step of preparing the slurry of FIG. 7, FIG. 9 is a flowchart showing the step of preparing the slurry of FIG. 7 in more detail, FIG. 10 is an explanatory diagram showing the step of forming the coating film of FIG. 7 in more detail, and FIG. 11 is an explanatory diagram showing the step of removing bubbles of FIG. 7 in more detail.

[0077] The method for manufacturing the cylindrical member 3 for a fluid processing apparatus according to an embodiment of the present invention is a method for manufacturing a cylindrical member 3 having a metal cylindrical main body 33 and an insulating layer 34 containing glass provided on at least the inner peripheral surface 33a of the cylindrical main body 33. As shown in FIG. 7, this manufacturing method includes a step of preparing a slurry (step S1), a step of forming a coating film (step S2), and a step of obtaining the insulating layer 34 (step S3).

[0078] The step of preparing a slurry (step S1) is a step of kneading a slurry raw material containing a wetting agent, a solvent, and a glass source to prepare a slurry (dispersion) as a coating liquid for forming an insulating layer.

[0079] The wetting agent is an auxiliary agent for improving the wettability of the slurry with respect to the surface (metal surface) of the cylindrical body 33. In FIG. 8, the state in which the slurry adheres more closely to the surface of the cylindrical body 33 due to the wetting agent is shown.

[0080] The wetting agent may be a nonionic surfactant. The nonionic surfactant may include a polyethylene glycol type nonionic surfactant and a polyhydric alcohol type nonionic surfactant.

[0081] The polyethylene glycol type nonionic surfactant is composed of a polyethylene glycol chain and a hydrophobic group (usually an alkyl group or an alkylaryl group). The polyethylene glycol chain is a superposition of ethylene oxide (EO) units, and its length varies depending on the type of polyethylene glycol. The hydrophobic group has the ability to interact with oils and lipids, resulting in the properties of a surfactant. Examples of the polyethylene glycol type nonionic surfactant include polyoxyethylene alkyl ether (higher alcohol EO adduct), polyoxyethylene alkyl phenyl ether (alkylphenol EO adduct), polyoxyethylene fatty acid ester (fatty acid EO adduct, polyethylene glycol fatty acid ester), polyoxyethylene polyhydric alcohol fatty acid ester (polyhydric alcohol fatty acid ester EO adduct), polyoxyethylene alkylamine (higher alkylamine EO adduct), polyoxyethylene fatty acid amide (fatty acid amide EO adduct), and polyoxyethylene polyoxypropylene glycol (polypropylene glycol EO adduct), etc.

[0082] The polyhydric alcohol type nonionic surfactant is made based on polyhydric alcohol. Polyhydric alcohol is a compound having a plurality of hydroxyl groups (-OH). For example, glycerin, pentaerythritol, sorbitol, etc. are generally used. The polyhydric alcohol type nonionic surfactant is made by bonding a hydrophobic group such as a fatty acid to the hydroxyl group of the polyhydric alcohol. By this bond, the hydrophilicity and hydrophobicity of the polyhydric alcohol are combined, showing the characteristics as a surfactant. This type of surfactant mainly has strong hydrophilicity and functions to promote emulsification and dispersion at the interface between oil and water. Examples of the polyhydric alcohol type nonionic surfactant include glycerin fatty acid ester, pentaerythritol fatty acid ester, sorbitol and sorbitan fatty acid ester, sucrose fatty acid ester, alkyl polyglycoside, and fatty acid alkanolamide, etc.

[0083] The coating liquid for forming an insulating layer may contain a raw material as a glass source and may contain glass frit. Specific examples of the raw material include silica sand (silicon source), dolomite (magnesium and calcium source), alumina (aluminum source), boric acid, barium oxide, lanthanum oxide, zinc oxide (zinc white), and strontium oxide. The raw material is not limited to oxides and may be, for example, a carbonate or a hydroxide. Glass frit is typically obtained by pulverizing (for example, pulverizing in two stages of coarse pulverization and fine pulverization) glass synthesized from the raw material. The above synthesis is typically carried out by long-time melting at a high temperature (for example, 1200 °C or higher).

[0084] The solvent refers to the liquid medium contained in the coating liquid for forming an insulating layer and is a concept including the solvent and the dispersion medium. The solvent may be water or an organic solvent. The solvent is preferably water or a water-soluble organic solvent such as alcohol, and more preferably water. The blending amount of the solvent is preferably, for example, 50 parts by mass to 300 parts by mass, and more preferably 80 parts by mass to 200 parts by mass, based on 100 parts by mass of the glass source.

[0085] The coating liquid (slurry) for forming the insulating layer may contain a slurry auxiliary agent. Examples of the slurry auxiliary agent include resins, plasticizers, dispersants, thickeners, and various additives. The type, number, combination, blending amount, etc. of the slurry auxiliary agent can be appropriately set according to the purpose.

[0086] In one embodiment, the slurry can be prepared according to the procedure shown in FIG. 9. That is, after mixing a wetting agent and a solvent to dissolve and disperse the wetting agent in the solvent to create a dispersion liquid, a glass source may be mixed in the dispersion liquid.

[0087] The step of forming the coating film (step S2) is a step of forming a coating film on at least the inner peripheral surface 33a of the cylindrical body 33 by immersing the cylindrical body 33 in the slurry stored in the treatment tank 50 as shown in FIG. 10 after preparing the slurry. The viscosity of the slurry in the treatment tank 50 is preferably 1 dPa·s or more. By setting the viscosity to such a value, the shear rate of the slurry from the cylindrical body 33 can be lowered, and the dripping of the slurry until it dries can be suppressed. The viscosity of the slurry is more preferably 2 dPa·s or more, and even more preferably 5 dPa·s or more. The upper limit of the viscosity is preferably 50 mPa·s or less, and more preferably 100 mPa·s or less. This is for suppressing the variation in the coating amount per unit time. The viscosity of the slurry may be measured using a coaxial double-cylindrical rotational viscometer of the inner cylinder constant-speed method in accordance with the method specified in JIS Z8803:2011 at 20°C of the raw material slurry.

[0088] The film thickness of the coating film may be appropriately adjusted according to the desired thickness of the insulating layer 34 (after firing). Specifically, the film thickness of the coating film may be about 2 to 5 times the thickness of the insulating layer 34.

[0089] The step of obtaining the insulating layer 34 (step S3) is a step of firing the coating film after forming the coating film to obtain the insulating layer 34. The firing temperature is preferably 1100 °C or lower, more preferably 600 °C to 1100 °C, and even more preferably 700 °C to 1050 °C. The firing time is, for example, 5 minutes to 60 minutes, and may be 8 minutes to 15 minutes.

[0090] Here, if there are many bubbles in the coating film (slurry) and / or the wettability of the coating film with respect to the surface (metal surface) of the cylindrical body 33 is poor, a large space layer 37 (see FIG. 6) is formed at the interface between the insulating layer 34 and the cylindrical body 33 after firing the coating film. This is because air bubbles gather and integrate at the interface between the coating film and the cylindrical body 33 during the process of drying and firing the coating film. In this manufacturing method, a slurry raw material containing a wetting agent, a solvent, and a glass source is kneaded to produce a slurry as a coating liquid for forming an insulating layer, so that the air bubbles in the coating film (slurry) can be reduced, and the space layer 37 at the interface between the insulating layer 34 and the cylindrical body 33 can be made smaller. Thereby, the cylindrical member 3 that can suppress the peeling of the insulating layer 34 can be manufactured more reliably.

[0091] As shown in the examples to be described later, it is preferable to contain 2.0% or more of the wetting agent with respect to the glass mass part of the slurry. The peeling of the insulating layer 34 can be more reliably suppressed. In addition, even if 6.0% or more of the wetting agent is added, the effect reaches a plateau. Therefore, from an economic point of view, 6.0% can be considered as the upper limit amount of the wetting agent.

[0092] As shown in FIG. 7, this manufacturing method may further include a step of removing air bubbles (step S4). The step of removing air bubbles can be arbitrarily added and may be omitted. The step of removing air bubbles is a step of applying centrifugal force to the slurry under a vacuum atmosphere after preparing the slurry and before putting the slurry into the treatment tank 50 to remove the air bubbles in the slurry.

[0093] By placing the slurry in a vacuum atmosphere, the bubbles contained in the slurry can be expanded. The expanded bubbles rise to the slurry surface due to buoyancy, and over time, the liquid film on the surface is broken, removing the bubbles in the slurry. Also, by applying centrifugal force to the slurry, the slurry and gas with a density difference can be separated.

[0094] The method of applying centrifugal force to the slurry is arbitrary, but a method as shown in Fig. 11 can be adopted. That is, in the step of removing the bubbles in the slurry, the container 51 containing the slurry may be rotated and revolved. Rotation can be understood as rotating the container 51 around the rotation axis passing through the inside of the container 51, and revolution can be understood as rotating the container 51 around the rotation axis passing through the outside of the container 51.

[0095] At this time, it is preferable that the revolution speed of the container 51 is 700 rpm or more and 1600 rpm or less, the rotation speed of the container 51 is 350 rpm or more and 750 rpm or less, and the atmospheric pressure inside the container 51 is 50 kPa or less. When the revolution speed is 700 rpm or more, the bubbles in the slurry can be defoamed more efficiently, and when it is 1600 rpm or less, the rise in the slurry temperature can be suppressed. When the rotation speed is 350 rpm or more, the bubbles in the slurry can be efficiently defoamed, and when it is 750 rpm or less, the entrainment of bubbles from the gas-liquid interface of the slurry can be suppressed. When the atmospheric pressure is 50 kPa or less, the bubbles in the slurry expand and are easily broken.

[0096] The revolution speed is more preferably 1000 rpm or more and 1600 rpm or less, and even more preferably 1200 rpm or more and 1600 rpm or less. The rotation speed is more preferably 500 rpm or more and 750 rpm or less, and even more preferably 600 rpm or more and 750 rpm or less. The atmospheric pressure is more preferably 20 kPa or less, and even more preferably 10 kPa or less. From the viewpoint of making the bubbles expand more and be more easily broken, the atmospheric pressure may be set as low as possible. However, in order to prevent the boiling of water as the solvent, generally the lower limit value of the atmospheric pressure is about 5 kPa.

[0097] Also, it may be considered preferable that the revolution speed of the container 51 is faster than the rotation speed of the container 51. By the revolution speed of the container 51 being faster than the rotation speed of the container 51, the entrainment of bubbles from the surface can be suppressed.

[0098] The rotation axis of the container 51 may be inclined with respect to the revolution axis of the container 51. The rotation axis may be inclined such that the upper part of the container 51 approaches the center of the revolution axis. The revolution radius of the container 51 may be 70 mm or more and 120 mm or less. The revolution radius may be the length of the line segment connecting the revolution axis and the central point of the diameter and length of the container 51 in the plane perpendicular to the revolution axis. The container 51 may be a bottomed cylindrical body with an openable and closable lid attached to the upper part. The diameter of the container 51 may be 60 mm or more and 80 mm or less. The capacity of the container 51 is 3 300 mm or more 3 and 1000 mm or less. The time for rotating and revolving the container 51 may be, for example, 120 seconds or more and 600 seconds or less.

[0099] The container 51 may be sealed and the inside of the container 51 may be a vacuum atmosphere, or the container 51 may be open and the container 51 may rotate and revolve in a chamber with a vacuum atmosphere.

[0100] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to such examples. It is obvious that those having ordinary knowledge in the technical field to which the present invention pertains can conceive of various modification examples or correction examples within the scope of the technical idea described in the claims, and it is naturally understood that these also belong to the technical scope of the present invention.

Example

[0101] Hereinafter, the present invention will be described more specifically by way of examples. The present invention is not limited to these examples.

[0102] As an example, the inventors adopted a method of forming a coating film by immersing the cylindrical body 33 in the slurry stored in the treatment tank 50 using a slurry containing a wetting agent (hereinafter, the method of forming a coating film by immersion may be referred to as the "dip method"), and prototyped a cylindrical member 3 provided with an insulating layer 34 on the inner peripheral surface 33a of the cylindrical body 33. As the wetting agent, SN Wet 366 (polyhydric alcohol type nonionic surfactant) and SN Deformer PC (polyethylene glycol type nonionic surfactant) manufactured by Sannopco Co., Ltd. were used. In addition, while changing the ratio of the wetting agent in the slurry (a mixture of silicate glass and water), the presence or absence of centrifugal vacuum degassing (a process of applying a centrifugal force to the slurry in a vacuum atmosphere to remove bubbles in the slurry) was changed (Examples 1 to 15). Then, in the prototyped cylindrical member 3, the space layer ratio and the thermal shock resistance were investigated. The results are shown in Tables 1 and 2 below.

[0103] In addition, the inventors also investigated the space layer ratio and the thermal shock resistance in the prototyped cylindrical member 3 using a slurry not containing a wetting agent as a comparative example. The results are shown together with Table 1 below. In Comparative Example 1, a method of forming a coating film by spraying the slurry onto the inner peripheral surface 33a of the cylindrical body 33 by spraying (hereinafter, the method of forming a coating film by spraying may be referred to as the "spray method") was adopted. In Comparative Example 2, the dip method was adopted in the same manner as in the examples.

[0104]

Table 1

[0105]

Table 2

[0106] (Common conditions) In the examples and comparative examples, the following are common. That is, water was used as the solvent, and silicate glass was used as the glass source. 100 parts by mass of water was used for 100 parts by mass of silicate glass. As the cylindrical main body 33, one made of SUS430 with a size of φ90 and a length of 200 mm was used. Using an atmospheric firing furnace, the coating film was fired at 850 °C for 60 minutes to obtain the insulating layer 34. For example, in Example 1, the indication that the wetting agent is 3.0% means that 3.0 g of the wetting agent was added to 100 g of the glass.

[0107] (Method for measuring the space layer ratio) The spatial layer ratio was measured by the following method. Samples were taken from a point shifted 15 mm in the upstream direction and a point shifted 15 mm in the downstream direction of the exhaust gas flow from the central part at the upper part of the portion with a constant inner diameter (barrel part) of the cylindrical member 3 prototyped in the examples and comparative examples. After cutting the sample in the diameter direction, it was further cut into a length of 20 mm, resin-embedded, and mirror-polished. Thereby, a cross-section of the inner peripheral surface 33a of the cylindrical main body 33 was obtained. Imaging of the cross-section was performed at a voltage of 15 kV using a scanning electron microscope (SEM), and continuous imaging was performed at a magnification of 1000 times from the surface of the insulating layer 34 until the reference plane 35 (smooth surface) of the outer peripheral surface 33b of the cylindrical main body 33 appeared in the base material direction of the cylindrical main body 33. A reference line RL was drawn so as to be in contact with the deepest point 36a of the rough surface 36 of the cylindrical main body 33 in parallel with the reference plane 35 of the cylindrical main body 33, and a region Re having a thickness of 20 μm and a width of 120 μm was set from the reference line RL toward the inside of the cylindrical main body 33. Thereafter, the area of the spatial layer 37 existing at the interface between the cylindrical main body 33 and the insulating layer 34 was determined using image processing software. As the image processing software, GIMP, an image processing software distributed by the Free Software Foundation, was used to perform binarization processing by the fixed threshold method to obtain the spatial layer ratio. Regarding the threshold value, since three peaks appeared in a graph with the horizontal axis being brightness and the vertical axis being area, the intermediate point between the peak of the lowest brightness peak and the second lowest brightness peak was used as the threshold value. In the binarization process, the total area of the portion with brightness lower than the threshold value was taken as the area (VA) of the spatial layer 37 in the region Re. Also, in the binarization process, the total area of the portion with brightness equal to or higher than the threshold value was taken as the total value (BA + IA) of the area (BA) of the cylindrical main body 33 and the area (IA) of the insulating layer 34 in the region Re. From these areas, the spatial layer ratio (VA / (BA + IA + VA)) was calculated.

[0108] As an example, images showing cross-sections of the inner peripheral surface 33a of the cylindrical main body 33 in Example 1 and Comparative Example 1 are shown in FIGS. 12 and 13. From the comparison between FIG. 12 and FIG. 13, it can be seen that the spatial layer 37 is smaller in Example 1 than in Comparative Example 1.

[0109] (Method for measuring thermal shock resistance) The thermal shock resistance was measured by the following method. That is, the sample was set in a furnace and heated until it reached 750 °C, then maintained at a predetermined temperature for 20 minutes, and then the sample was dropped into a tank filled with water at a temperature of 20 - 25 °C, and the surface state of the sample was checked. Note that peeling also occurred at the points where cracks had occurred. If peeling occurred, the test was terminated. If no peeling occurred, the temperature of the furnace was raised by 50 °C, and the above test was repeated. The above operation was repeated until peeling occurred.

[0110] In Tables 1 and 2, "◎" in the row of "thermal shock resistance" means that when the sample was dropped from a furnace heated to 900 °C into water, no peeling occurred in the insulating layer 34. "〇" means that although no peeling occurred in the insulating layer 34 when the sample was dropped from a furnace heated to 850 °C into water, peeling occurred in the insulating layer 34 when the sample was dropped from a furnace heated to 900 °C into water. "×" means the case where peeling occurred in the insulating layer 34 when the sample was dropped from a furnace heated to 750 °C into water. The evaluations of "◎" to "〇" indicate that it can withstand practical use from the perspective of being able to withstand thermal shock in the exhaust gas purification device, and "×" indicates that it is difficult to withstand practical use from the perspective that peeling occurs due to thermal shock in the exhaust gas purification device and the insulation performance is impaired.

[0111] As shown in Tables 1 and 2, in Examples 1 to 15 using a slurry containing a wetting agent, the void layer ratio could be suppressed to 25% or less. Also, the evaluation of the thermal shock resistance was "◎" to "〇".

[0112] On the other hand, in Comparative Examples 1 and 2 using a slurry not containing a wetting agent, the void layer ratio was 30% or more. In particular, in Comparative Example 1 adopting the spray method, the void layer ratio was as high as 35%. In these Comparative Examples 1 and 2, the evaluation of the thermal shock resistance was "×".

[0113] From these results, it was confirmed that by setting the void layer ratio to 25% or less, peeling of the insulating layer 34 can be suppressed. Also, it was confirmed that by using a wetting agent, the cylindrical member 3 capable of suppressing peeling of the insulating layer 34 can be manufactured more reliably.

[0114] By adding 2.0% or more of the wetting agent as in Examples 1 to 15, the evaluation of thermal shock resistance became from "◎" to "〇". From this result, it was confirmed that it is preferable to include 2.0% or more of the wetting agent with respect to the glass mass part of the slurry. Also, even when 6.0% or more of the wetting agent was added, the effect leveled off. That is, the void fraction could not be further reduced, and no improvement in thermal shock resistance was observed. Therefore, from an economic point of view, 6.0% is considered as the upper limit amount of the wetting agent.

[0115] In particular, in Example 1 where centrifugal vacuum degassing was carried out, the void fraction could be suppressed to 3%. From this result, it can be seen that it is preferable to carry out centrifugal vacuum degassing.

[0116] In Example 1, the revolution speed of the container 51 containing the slurry was set to 1400 rpm, the rotation speed of the container 51 was set to 700 rpm, and the atmospheric pressure inside the container 51 was set to 6 kPa. When the revolution speed was increased to more than 1600 rpm as in Example 5, no change was observed in the space layer ratio. However, the slurry temperature increased and the viscoelasticity of the slurry changed significantly, resulting in impaired uniformity of the film thickness of the coating film. However, the uniformity of the film thickness of the coating film in Example 5 was not a problem in practical use. Also, when the revolution speed was decreased to less than 700 rpm as in Example 7, no improvement in the space layer ratio was observed. Furthermore, when the atmospheric pressure inside the container 51 was increased to more than 50 kPa as in Example 13, the effect on defoaming was small and no improvement in the space layer ratio was observed. Also, when the rotation speed was decreased to less than 350 rpm as in Example 11, no improvement in the space layer ratio was observed. Additionally, when the rotation speed was increased to more than 750 rpm as in Example 9, the slurry temperature increased and the viscoelasticity of the slurry changed significantly, resulting in impaired uniformity of the film thickness of the coating film. However, the uniformity of the film thickness of the coating film in Example 9 was not a problem in practical use. From these results, the superiority of setting the revolution speed of the container 51 to be 700 rpm or more and 1600 rpm or less, the rotation speed of the container 51 to be 350 rpm or more and 750 rpm or less, and the atmospheric pressure inside the container 51 to be 50 kPa or less was confirmed. In addition, when the rotation speed was faster than the revolution speed as in Examples 14 and 15, entrainment of bubbles occurred and deterioration of the space layer ratio was observed. From the above, the superiority of setting the revolution speed of the container 51 to be faster than the rotation speed of the container 51 was confirmed.

Explanation of Signs

[0117] 1: Fluid processing apparatus 3: Cylindrical member for fluid processing apparatus (cylindrical member) 33: Cylindrical body 33a: Inner peripheral surface 34: Insulation layer 35: Reference plane 36: Rough surface 36a: Concave portion 37: Space layer 50: Processing tank 51: Container

Claims

1. A metallic cylindrical body; an insulating layer including glass provided on an inner peripheral surface of the cylindrical body; A cylindrical member for a fluid treatment device comprising: The surface of the cylindrical body is provided with a smooth reference surface and a rough surface having a plurality of recesses, and the insulating layer is provided at least on the rough surface, a space layer is partially formed at the interface between the cylindrical body and the insulating layer, In the cross-sectional image of the inner circumferential surface of the cylindrical main body, a reference line is drawn that passes through the most recessed point of the rough surface and is parallel to the reference surface, and a region having a thickness of 20 μm and a width of 120 μm from the reference line toward the inside of the cylindrical main body is set. A space layer ratio (VA / (BA+IA+VA)) obtained by dividing the area (VA) of the space layer in the region by the sum of the area (BA) of the cylindrical main body in the region, the area (IA) of the insulating layer in the region, and the area (VA) of the space layer in the region is 25% or less. A cylindrical member for a fluid processing device.

2. The thickness of the insulating layer is 30 μm or more and 800 μm or less. The cylindrical member for a fluid treatment device according to claim 1 .

3. A method for manufacturing a cylindrical member for a fluid processing device, comprising: a metallic cylindrical body; and an insulating layer including glass provided on at least an inner peripheral surface of the cylindrical body, the method comprising the steps of: A step of kneading a slurry raw material including a wetting agent, a solvent, and a glass source to prepare a slurry as a coating liquid for forming an insulating layer; a step of forming a coating film on at least an inner circumferential surface of the cylindrical main body by immersing the cylindrical main body in the slurry stored in a treatment tank after preparing the slurry; A step of forming the coating film and then baking the coating film to obtain the insulating layer; Including, A method for manufacturing a cylindrical member for a fluid processing device.

4. The wetting agent is a non-ionic surfactant. The method for producing the cylindrical member for a fluid processing device according to claim 3 .

5. The method further includes a step of applying a centrifugal force to the slurry in a vacuum atmosphere after preparing the slurry and before placing the slurry in the treatment tank, thereby removing air bubbles in the slurry. The method for producing the cylindrical member for a fluid processing device according to claim 3 .

6. In the step of removing air bubbles from the slurry, a container containing the slurry is rotated and revolved, the revolution speed of the container is set to 700 rpm or more and 1600 rpm or less, the rotation speed of the container is set to 350 rpm or more and 750 rpm or less, and the atmospheric pressure in the container is set to 50 kPa or less. The method for producing the cylindrical member for a fluid processing device according to claim 5 .

7. 6. The method for manufacturing a cylindrical member for a fluid processing device according to claim 5, wherein in the step of removing air bubbles from the slurry, a container containing the slurry is rotated and revolved, and the revolving speed of the container is faster than the rotating speed of the container.

8. The viscosity of the slurry in the treatment tank is 1 dPa s or more; The method for producing the cylindrical member for a fluid processing device according to claim 3 .

9. The wetting agent is contained in an amount of 2.0% or more based on the glass mass part of the slurry. The method for producing the cylindrical member for a fluid processing device according to claim 3 .

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