Cylindrical member for fluid treatment device and fluid treatment device

Abstract

To provide a cylindrical member for a fluid treatment device and a fluid treatment device capable of improving adhesion of a cylindrical body and an insulation layer and suppressing peeling of the insulation layer when the insulation layer contains crystallized glass.SOLUTION: A cylindrical member 3 for a fluid treatment device includes a metal cylindrical body 33 and an insulation layer 34 containing crystallized glass. The surface of the cylindrical body 33 is provided with a reference surface 35 and a rough surface 36. A boundary surface of the cylindrical body 33 and the insulation layer 34 is formed with a chemical bonding layer 38 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 chemical bonding layer ratio (CL / IL) is 30% or more, which is obtained by dividing the extending length (CL) of the chemical bonding layer 38 in the region Re by the extending length (IL) of the inner peripheral surface 33a of the cylindrical body 33 in the region.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a cylindrical member for a fluid treatment apparatus and a fluid treatment apparatus used for a fluid treatment apparatus for treating a fluid.

Background Art

[0002] For example, in automobiles and the like, in order to highly efficiently purify exhaust gas from the start of engine operation, the use of a fluid treatment apparatus that can be heated by energization has been considered. Such a fluid treatment apparatus includes a cylindrical member (can or can body) made of metal 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 activation temperature suitable for the 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 is known in which an insulating layer is formed on the surface of a cylindrical main body (cylindrical metal member) to prevent leakage of electricity to the cylindrical main body. Further, Patent Document 1 discloses that when the firing temperature after forming the insulating layer is less than 400°C, at the interface between the insulating layer and the cylindrical main body, the substance constituting the insulating layer and the substance constituting the cylindrical main body cannot form a composite oxide by chemical bonding, resulting in a decrease in the adhesion between the insulating layer and the cylindrical main body and peeling of the insulating layer from the cylindrical main body.

[0004] Patent Document 2 below describes "a cylindrical member for an exhaust gas treatment apparatus having a metal cylindrical main body and an insulating layer provided on at least the inner peripheral surface of the cylindrical main body, the insulating layer containing a glass containing a crystalline substance, and the glass containing silicon, boron, and magnesium".

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] Glass includes amorphous glass used for general sheet glass and the like, and glass containing crystals (crystallized glass) as disclosed in Patent Document 2. Amorphous glass has the property of easily softening or melting when heated. On the other hand, crystallized glass has the property of being difficult to soften at high temperatures. In the invention described in Patent Document 2, the property of such crystallized glass is utilized to stably maintain the exhaust gas treatment (typically purification) function even at high temperatures. However, when the insulating layer contains crystallized glass, due to the property of crystallized glass being difficult to soften at high temperatures, it is difficult for the inner peripheral surface of the cylindrical body and the insulating layer to adhere closely, and a large gap is formed at their bonding interface, resulting in a new problem that the insulating layer is likely to peel off from the inner peripheral surface of the cylindrical body. Although it is expected to improve the adhesion between the cylindrical body and the insulating layer by a chemical bonding layer as shown in Patent Document 1, Patent Document 1 does not discuss an insulating layer containing crystallized glass.

[0007] The present invention has been made to solve the above problems, and one of its objects is to provide a cylindrical member for a fluid treatment device and a fluid treatment device that can improve the adhesion between a cylindrical body and an insulating layer and suppress the peeling of the insulating layer when the insulating layer contains crystallized glass. [Means for Solving the Problems]

[0008] Item 1. In one embodiment, the present invention relates to a cylindrical member for a fluid processing apparatus, comprising a metallic cylindrical main body and an insulating layer provided on the inner circumferential surface of the cylindrical main body and containing crystallized glass. 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 chemical bonding layer is partially formed at the interface between the cylindrical main body and the insulating layer. In a cross-sectional image of the inner circumferential 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 chemical bonding layer ratio (CL / IL) obtained by dividing the extension length (CL) of the chemical bonding layer in the region by the extension length (IL) of the inner circumferential surface of the cylindrical main body in the region is 30% or more. The present invention relates to a cylindrical member for a fluid processing apparatus.

[0009] Item 2. The present invention may relate to the cylindrical member for a fluid processing apparatus according to Item 1, wherein the thickness of the chemical bonding layer is 30 μm or less.

[0010] Item 3. The present invention may relate to the cylindrical member for a fluid processing apparatus according to Item 1 or 2, wherein the chemical bonding layer is an oxide layer that shares some elements from both the cylindrical main body and the insulating layer.

[0011] Item 4. The present invention may relate to the cylindrical member for a fluid processing apparatus according to Item 3, wherein the chemical bonding layer contains Si, Cr, and O.

[0012] Item 5. In one embodiment, the present invention relates to a fluid processing apparatus, comprising an electrically heated carrier capable of heating exhaust gas and the cylindrical member for a fluid processing apparatus according to any one of Items 1 to 4 that houses the electrically heated carrier.

Advantages of the Invention

[0013] According to one embodiment of the cylindrical member for a fluid processing apparatus and the fluid processing apparatus of the present invention, since the chemical bonding layer ratio (CL / IL) is 30% or more, when the insulating layer contains crystallized glass, the adhesion between the cylindrical main body and the insulating layer can be improved, and peeling of the insulating layer can be suppressed.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0015] 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.

[0016] FIG. 1 is a cross-sectional view of a fluid treatment apparatus 1 including a cylindrical member 3 for a fluid treatment 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 treatment apparatus in the embodiment of the present invention can be used in the fluid treatment apparatus 1 as shown in FIG. 1. The fluid treatment apparatus 1 is an apparatus for treating a fluid. The fluid treatment apparatus 1 can be provided, for example, on an exhaust path of an automobile or the like and used for treating or purifying exhaust gas discharged from an engine. However, the use of the fluid treatment apparatus 1 is not limited to the purification of exhaust gas, and it may be used for treating other fluids such as heating a fluid. Hereinafter, the "cylindrical member for a fluid treatment apparatus" may be simply referred to as a "cylindrical member".

[0017] As shown in FIG. 1, the fluid treatment apparatus 1 may include an electrically heated carrier 2, a cylindrical member 3, and a buffer member 4.

[0018] 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. Thus, the catalyst supported on the honeycomb structure 20 can be heated to the activation temperature before the engine is started.

[0019] As particularly shown in FIG. 2, the honeycomb structure 20 has a honeycomb structure portion 200 and at least one electrode layer 201.

[0020] The honeycomb structure portion 200 is a columnar member made of ceramics, and has an outer peripheral wall 202 and a partition wall 203 that is disposed inside the outer peripheral wall 202 and partitions and forms a plurality of cells 203a that form a flow path 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 (the 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.

[0021] 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, etc. Also, the size of the honeycomb structure portion 200 is such that, for the reason of enhancing heat resistance (suppressing cracks entering in the circumferential direction of the outer peripheral wall 202), the area of the end face is preferably 2000 to 65000 mm 2 and more preferably 5000 to 25000 mm 2 . It is also possible to join and use a plurality of columnar honeycomb structures with polygonal end faces.

[0022] 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, a hexagon, an octagon, 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.

[0023] The thickness of the partition wall 203 that forms the compartments 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.

[0024] In a cross section orthogonal to the extending direction of the cell 203a, the honeycomb structure portion 200 preferably has a cell density of 4 to 150 cells / cm 2 and more preferably 7 to 100 cells / cm 2 . 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.

[0025] 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 even 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 even 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.

[0026] 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.

[0027] 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. Further, a silicon carbide - silicon composite material, a silicon carbide / graphite composite material, or the like can also be used. Among these, from the viewpoint of achieving both heat resistance and conductivity, the material of the honeycomb structure portion 200 preferably 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% by mass or more of the silicon - silicon carbide composite material (total mass). 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% by mass or more of silicon carbide (total mass).

[0028] 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% by mass, and more preferably 15 to 35% by mass.

[0029] 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. When they are dense, the porosity of the outer peripheral wall 202 and the partition wall 203 may be 10% or less, or even 5% or less.

[0030] 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.

[0031] 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.

[0032] One electrode layer 201 may be provided on the entire outer peripheral surface of the honeycomb structure 20, but 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 a cross section of the honeycomb structure portion 200 orthogonal 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 a cross section orthogonal 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 a cross section of the honeycomb structure portion 200 orthogonal to the extending direction of the cell 203a. When the honeycomb structure portion 200 is cylindrical, this angle may be the interior angle of a sector formed by the two line segments and the electrode layer 201.

[0033] The thickness of the electrode layer 201 is preferably 0.01 to 5 mm, 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 in 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.

[0034] 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 in the form of bands having a predetermined width in the circumferential direction of the honeycomb structure portion 200, and the separation zone 2010 is in the form of a narrow line 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.

[0035] 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.

[0036] 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.

[0037] 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 simple metal of 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).

[0038] 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, to produce 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.

[0039] 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 alumina pore surface, and a three-way catalyst, an oxidation catalyst, or the like containing a promoter such as ceria or zirconia, or a NOx storage reduction catalyst (LNT catalyst) containing an alkaline earth metal and platinum as a NOx storage component is exemplified. Examples of catalysts that do not use noble metals include a NOx selective reduction catalyst (SCR catalyst) containing copper-substituted or iron-substituted zeolite. 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.

[0040] The metal electrode 21 may have a connection portion 210 disposed on the electrode layer 201 and a lead-out portion 211 drawn from the connection portion 210. Although not shown in detail, the connection portion 210 may be configured in a comb-tooth 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.

[0041] The cylindrical member 3 is a metal member that houses 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 include stainless steel, titanium alloy, copper alloy, aluminum alloy, and brass. Among them, stainless steel is preferred because of its high durability and reliability and low cost.

[0042] 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.

[0043] The plate thickness of the cylindrical member 3 may be, for example, 0.1 mm to 10 mm, 0.3 mm to 5 mm, or 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, 30 mm to 600 mm, 40 mm to 500 mm, or 50 mm to 400 mm.

[0044] 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.

[0045] 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.

[0046] 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 is compressible 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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 area of the 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 face 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.

[0052] From the viewpoint of suppressing leakage current 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 moisture non-permeability and moisture non-absorbency. Specifically, the insulating layer 34 is preferably configured to be dense and not to 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.

[0053] The insulating layer 34 contains crystallized glass. In other words, the insulating layer 34 contains glass, and the glass is 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 having 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.

[0054] Whether crystals are precipitated in the glass, i.e., whether it is a crystallized glass, can be confirmed by X-ray diffraction (XRD). Since amorphous glass has no atomic regularity, it does not exhibit distinct diffraction peaks. On the other hand, the precipitated crystals exhibit 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

[0055] 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, 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.

[0056] In one embodiment, the glass contains silicon and boron. Silicon may be contained in the glass in the form of SiO2, and boron may 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 even 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 even more preferably 8 mol% to 55 mol%.

[0057] In addition to silicon and boron, the above 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 above 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 above glass is preferably 3 mol% to 30 mol%, more preferably 5 mol% to 25 mol%, and still more preferably 6 mol% to 20 mol%.

[0058] In addition, 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) emission spectrometry.

[0059] The thickness of the insulating layer 34 may be 30 μm or more and 800 μm or less. By the thickness of the insulating layer 34 being 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. By the thickness of the insulating layer 34 being 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.

[0060] 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. The coating film may be formed by any method. For example, the coating film can be formed by a method of immersing the cylindrical body 33 in the slurry stored in a treatment tank and a method of spraying the slurry onto the inner peripheral surface 33a of the cylindrical body 33 by a spray.

[0061] As shown in FIGS. 4 and 5, on the surface of the cylindrical main body 33, there are provided a smooth reference surface 35 (see FIG. 4) and a rough surface 36 (see FIG. 5) having a plurality of recesses 36a, 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.

[0062] The rough surface 36 can be formed by a surface treatment such as blasting. The rough surface 36 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. By providing the insulating layer 34 on the rough surface 36, the adhesion between the cylindrical main 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 main 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 main body 33. In this specification, the "arithmetic mean roughness Ra" of the inner peripheral surface 33a of the cylindrical main body 33 is measured by a stylus type surface roughness measuring instrument in accordance with JIS B0601:2013.

[0063] 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. The surface of the reference surface 35 may have, for example, scratches formed on the surface of the metal plate constituting the cylindrical main body 33 by rolling or forming processes. As shown in FIG. 3, the reference surface 35 may be the outer peripheral surface 33b of the cylindrical main body 33.

[0064] Next, FIG. 6 is an image showing the insulating layer 34 on the rough surface 36 of FIG. 5 in more detail, and FIG. 7 is an image emphasizing the inner peripheral surface 33a of the cylindrical body 33 and the chemical bonding layer 38 in the region Re of FIG. 6. As shown in FIG. 6, a space layer 37 and a chemical bonding layer 38 are 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 part, the insulating layer 34 appears as a darker part than the cylindrical body 33, the space layer 37 appears as a darker part than the insulating layer 34, the chemical bonding layer 38 appears at the part where the insulating layer 34 and the cylindrical body 33 are in contact, and appears as a part with a brightness intermediate between the insulating layer 34 and the cylindrical body 33.

[0065] The chemical bonding layer 38 is a layer in which the metal constituting the cylindrical body 33 and the insulating layer 34 are chemically bonded, and is formed at the position where the cylindrical body 33 and the insulating layer 34 are in contact. As described above, the insulating layer 34 is formed by firing a coating film formed on at least the inner peripheral surface 33a of the cylindrical body 33. The chemical bonding layer 38 is a covalent bonding layer generated in this firing process. The chemical bonding layer 38 may be an oxide layer that shares some elements from both the cylindrical body 33 and the insulating layer 34. The chemical bonding layer 38 may contain Si, Cr, and O.

[0066] It is empirically known that the more the chemical bonding layer 38 is formed, the better the adhesion between the cylindrical body 33 and the insulating layer 34 can be improved, and the peeling of the insulating layer 34 from the cylindrical body 33 can be suppressed. However, it was not clear to what extent the chemical bonding layer 38 could suppress the peeling of the insulating layer 34. 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 body 33 and the insulating layer to adhere closely, and large gaps are formed at their bonding interface, resulting in the problem that the insulating layer 34 is likely to peel off from the inner peripheral surface of the cylindrical body 33.

[0067] In the aspect where the insulating layer 34 contains crystallized glass, when the inventors conducted various studies, in the cross-sectional image of the inner peripheral surface 33a of the cylindrical body 33 as shown in FIG. 6, a reference line RL passing through the deepest point 36a of the rough surface 36 and parallel to the reference plane 35 was drawn, and when 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 body 33, the chemical bond layer ratio (CL / IL) obtained by dividing the extension length (CL) of the chemical bond layer 38 in the region Re by the extension length (IL) of the inner peripheral surface 33a of the cylindrical body 33 in the region Re was 30% or more. Thus, when the insulating layer 34 contains crystallized glass, it was found that the adhesion between the cylindrical body 33 and the insulating layer 34 can be improved and peeling of the insulating layer 34 can be suppressed (in FIG. 7, the inner peripheral surface 33a of the cylindrical body 33 in the region Re is emphasized by a thick black line, and the chemical bond layer 38 in the region Re is emphasized by a thick white line). That is, in the cylindrical member 3 of the present embodiment, the chemical bond layer ratio is 30% or more.

[0068] 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, the SEM image is continuously taken in the plate thickness direction of the cylindrical body 33, the straight line (reference plane 35) along which the outer peripheral surface 33b extends in the SEM image in which the outer peripheral surface 33b is taken is specified, 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.

[0069] Samples may be collected from a point 15 mm shifted in the upstream direction in which the exhaust gas flows and a point 15 mm shifted in the downstream direction from the central part at the upper portion of the part with a constant inner diameter of the cylindrical body 33. After cutting in the diametrical 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 elemental direction of the cylindrical body 33. A reference line RL is drawn so as to be in contact with the most recessed point 36a of the rough surface 36 of the cylindrical body 33 in parallel with the reference plane 35 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 chemical bond layer ratio is determined. The chemical bond layer 38 in the region Re is the white line portion in FIG. 7, the length of the white line portion is measured by image processing software, and the sum of the lengths of the respective white line portions is defined as the extension length (CL) of the chemical bond layer 38. The extension length (IL) of the inner peripheral surface 33a of the cylindrical body 33 in the region Re is the length of the black line portion in FIG. 7. The length of the black line portion may also be measured by image processing software.

[0070] When the average value of the chemical bond layer ratios obtained from the samples at the above two points is 30% or more, it may be determined that the chemical bond layer ratio of the cylindrical member 3 is 30% or more.

[0071] By adjusting the maximum temperature when baking the coating film and the time for maintaining the maximum temperature, the growth of the chemical bond layer 38 can be adjusted. By adjusting the growth of the chemical bond layer 38, the chemical bond layer ratio and the thickness of the chemical bond layer 38 can be adjusted. For example, by performing baking at a temperature of 850°C to 950°C for 1 hour or more, a chemical bond layer 38 of about 10 μm can be obtained partially. The growth of the chemical bond layer 38 can also be adjusted by the temperature of the cylindrical body 33 before forming the coating film. If the cylindrical body 33 is baked before forming the coating film, the wettability deteriorates due to the cylindrical body 33 being oxidized in advance to form a passive film, so the chemical bond layer ratio tends to decrease and the chemical bond layer 38 tends to become thinner.

[0072] Next, FIG. 8 is an image for explaining the thickness Th of the chemical bonding layer 38 in FIG. 6. The chemical bonding layer 38 has a different coefficient of thermal expansion from that of the cylindrical main body 33 and the insulating layer 34. When the thickness Th of the chemical bonding layer 38 becomes excessive, cracks may occur in the insulating layer 34 starting from the chemical bonding layer 38 when the cylindrical main body 33 or the cylindrical member 3 is heated. As a result of various studies by the present inventors, it was found that by setting the thickness Th of the chemical bonding layer 38 to 30 μm or less, the occurrence of cracks in the insulating layer 34 due to the chemical bonding layer 38 can be avoided. That is, in the cylindrical member 3 of the present embodiment, the thickness Th of the chemical bonding layer 38 is set to 30 μm or less.

[0073] The thickness Th of the chemical bonding layer 38 may be measured from a cross-sectional image for obtaining the chemical bonding layer ratio (CL / IL). In the cross-sectional image obtained as described above, the chemical bonding layer 38 appears at the portion where the insulating layer 34 and the cylindrical main body 33 are in contact, and is represented as a portion with a brightness intermediate between the insulating layer 34 and the cylindrical main body 33. The chemical bonding layer 38 may be cut out using image processing software, and the average value of any two points of the length from the insulating layer 34 toward the cylindrical main body 33 may be taken as the thickness Th of the chemical bonding layer 38.

[0074] As described above, the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, but 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.

Examples

[0075] Hereinafter, the present invention will be described more specifically by way of examples. The present invention is not limited to these examples.

[0076] The inventors prepared a cylindrical member 3 provided with an insulating layer 34 on the inner peripheral surface 33a of the cylindrical body 33 while changing the presence or absence of firing (pre-firing) of the cylindrical body 33 before forming the coating film, the maximum firing temperature (°C) when firing the coating film to form the insulating layer 34, and the holding time (hr) of the maximum firing temperature. Then, in the prepared cylindrical member 3, it was investigated whether the glass of the insulating layer 34 was crystallized glass or amorphous glass, the chemical bond layer ratio, and the thermal shock resistance. The results are shown in Table 1 below. In Table 1, those in which the glass of the insulating layer 34 is crystallized glass and the chemical bond layer ratio is 30% or more are shown as examples, and those in which the glass of the insulating layer 34 is amorphous glass or the chemical bond layer ratio is less than 30% are shown as comparative examples.

[0077]

Table 1

[0078] (Common conditions) In the examples and comparative examples, the following are common. That is, as the cylindrical body 33, one made of SUS430 with a size of φ90 and a length of 200 mm was used. As a method for forming the coating film, it was formed by a method of immersing the cylindrical body 33 in the slurry stored in the treatment tank using a slurry as a coating liquid for forming an insulating layer containing a glass source. After heating the coated cylindrical body 33 at 50°C to 120°C for an arbitrary time, the coating film was fired using an atmospheric firing furnace to obtain the insulating layer 34.

[0079] (Method for determining glass) In the trial-produced cylindrical member 3, it was determined by X-ray diffraction method (XRD) whether the glass of the insulating layer 34 is crystallized glass (whether the insulating layer 34 contains crystallized glass). When the crystallinity of the glass of the insulating layer 34 is 50% or more (when the amorphous glass is less than 50%), it was determined that the glass of the insulating layer 34 is crystallized glass (the insulating layer 34 contains crystallized glass). In Table 1, this case is expressed as "crystallized glass". On the other hand, when the crystallinity of the glass of the insulating layer 34 is less than 50% (when the amorphous glass is 50% or more), it was determined that the glass of the insulating layer 34 is amorphous glass (the insulating layer 34 does not contain crystallized glass). In Table 1, this case is expressed as "amorphous glass". The glasses of Examples 1 to 5 and Comparative Examples 1 to 3 are borosilicate glasses containing magnesium, and their crystallinities were 90% or more. In contrast, the glass of Comparative Example 4 is a glass (SiO2-BaO-ZnO-SrO) mainly composed of silicic acid.

[0080] The crystallinity (%) was obtained by obtaining the peak area of the crystalline and the peak area of the amorphous from the diffraction pattern obtained by X-ray diffraction and calculating according to the following formula. Crystallinity (%) = {peak area of crystalline / (peak area of crystalline + peak area of amorphous)} × 100 The X-ray diffraction measurement was carried out by the following method. Samples were collected from a point 15 mm shifted in the upstream direction and a point 15 mm shifted in the downstream direction of the exhaust gas flow from the central part of the upper part of the constant inner diameter part (barrel part) of the cylindrical member 3 trial-produced in the examples and comparative examples. After the samples were cut in the diameter direction, they were further cut to a length of 20 mm, resin-embedded, and mirror-polished. As a result, a cross-section of the inner peripheral surface 33a of the cylindrical main body 33 was obtained. The position was adjusted so that the glass part of the cross-section was irradiated with X-rays, and the measurement was carried out to obtain a diffraction pattern.

[0081] (Measurement method of chemical bond layer ratio) The chemical bond layer ratio was measured by the following method. Samples were taken from the point shifted 15 mm in the upstream direction where the exhaust gas flows and the point shifted 15 mm in the downstream direction 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 diametrical 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 with 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 most recessed 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 chemical bond layer ratio was determined using image processing software. The chemical bond layer 38 in the region Re was taken as the white line part in FIG. 7, and the sum of the lengths of each white line part was taken as the extension length (CL) of the chemical bond layer 38. The extension length (IL) of the inner peripheral surface 33a of the cylindrical main body 33 in the region Re was taken as the length of the black line part in FIG. 7. The lengths of the white line part and the black line part were measured by image processing software. From these obtained lengths, the chemical bond layer ratio (CL / IL) was calculated.

[0082] (Method for measuring the thickness of the chemical bond layer) The thickness Th of the chemical bond layer 38 was measured from the cross-sectional image for obtaining the chemical bond layer ratio (CL / IL). In the cross-sectional image obtained as described above, the chemical bond layer 38 appears at the portion where the insulating layer 34 is in contact with the cylindrical main body 33 and appears as a portion with a brightness intermediate between the insulating layer 34 and the cylindrical main body 33. The chemical bond layer 38 was cut out using image processing software, and the average value of any two points of the length from the insulating layer 34 toward the cylindrical main body 33 was taken as the thickness Th of the chemical bond layer 38.

[0083] (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. After that, the sample was dropped into a trough filled with water at a temperature of 20 - 25°C, and the surface state of the sample was checked. In addition, peeling also occurred at the points where cracks were present. If peeling occurred, the test was terminated. If no peeling occurred, the temperature of the furnace was increased by 50°C, and the above test was repeated. The above operation was repeated until peeling occurred.

[0084] In Table 1, "◎" in the row of "thermal shock resistance" means that when the sample was dropped into water from a furnace heated to 900°C, 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 into water from a furnace heated to 850°C, peeling occurred in the insulating layer 34 when the sample was dropped into water from a furnace heated to 900°C. "△" means that although no peeling occurred in the insulating layer 34 when the sample was dropped into water from a furnace heated to 800°C, peeling occurred in the insulating layer 34 when the sample was dropped into water from a furnace heated to 850°C. "×" means the case where peeling occurred in the insulating layer 34 when the sample was dropped into water from a furnace heated to 750°C. The evaluations of "◎" - "△" indicate that it can withstand practical use from the perspective of withstanding thermal shock in the exhaust gas purification device, and "×" indicates that it is difficult to withstand practical use from the perspective that cracks occur due to thermal shock in the exhaust gas purification device and the insulation performance is impaired.

[0085] By comparing Example 1 and Comparative Example 1, it can be seen that the higher the maximum firing temperature, the more the chemical bonding layer 38 can be grown (the chemical bonding layer rate can be increased and the chemical bonding layer 38 can be thickened). Similarly, by comparing Example 1 and Comparative Example 3, it can be seen that the longer the holding time at the maximum temperature, the more the chemical bonding layer 38 can be grown (the chemical bonding layer 38 can be thickened). Example 1 and Comparative Example 3 are examples of relatively high temperatures. If a high temperature is maintained for a long time as in Comparative Example 3, the chemical bonding layer 38 may grow excessively and the chemical bonding layer rate may decrease. If the temperature is relatively low as in Example 2 and Comparative Example 2, the longer the holding time at the maximum temperature, the higher the chemical bonding layer rate. By comparing Comparative Example 1 and Comparative Example 2, it can be seen that the chemical bonding layer rate decreases when the cylindrical body 33 is fired before forming the coating film.

[0086] As in Examples 1 to 5, when the glass of the insulating layer 34 is crystallized glass and the chemical bonding layer rate is 30% or more, the evaluation of thermal shock resistance was from "◎" to "△". However, when the chemical bonding layer rate was less than 30% as in Comparative Examples 1 to 3, the evaluation of thermal shock resistance was "×". From this result, it was confirmed that when the insulating layer 34 contains crystallized glass, by setting the chemical bonding layer rate to 30% or more, the adhesion between the cylindrical body 33 and the insulating layer 34 can be improved and peeling of the insulating layer 34 can be suppressed.

[0087] Note that as in Comparative Example 4, when the glass of the insulating layer 34 is amorphous glass, even if the maximum firing temperature is low and the holding time at the maximum temperature is short, the chemical bonding layer rate becomes high. This is presumably because amorphous glass has the property of being easily softened or melted by heating. When the glass of the insulating layer 34 is amorphous glass, the evaluation of thermal shock resistance was "×" even when the chemical bonding layer rate was 90% as in Comparative Example 4. This is also presumably due to the property of amorphous glass being easily softened or melted by heating. That is, it can be seen that the usefulness of the chemical bonding layer rate differs depending on whether the glass of the insulating layer 34 is crystallized glass or amorphous glass.

[0088] Also, when the thickness of the chemical bonding layer 38 was 30 μm or less as in Examples 1 to 3 and 5, the evaluation of thermal shock resistance was "◎" or "〇", but when the thickness of the chemical bonding layer 38 exceeded 30 μm as in Example 4, the evaluation of thermal shock resistance was "△". From this result, it was confirmed that by setting the thickness of the chemical bonding layer 38 to 30 μm or less, peeling of the insulating layer 34 can be more reliably suppressed.

Explanation of Signs

[0089] 1: Fluid treatment apparatus 3: Cylindrical member for fluid treatment apparatus (cylindrical member) 33: Cylindrical main body 33a: Inner peripheral surface 34: Insulating layer 35: Reference plane 36: Rough surface 36a: Concave portion 38: Chemical bonding layer

Claims

1. A metallic cylindrical body; an insulating layer including crystallized glass provided on the 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 chemically bonded 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 chemically bonded layer ratio (CL / IL) obtained by dividing the extension length (CL) of the chemically bonded layer in the region by the extension length (IL) of the inner circumferential surface of the cylindrical main body in the region is 30% or more. A cylindrical member for a fluid processing device.

2. The thickness of the chemical bonding layer is 30 μm or less. The cylindrical member for a fluid treatment device according to claim 1 .

3. The chemically bonded layer is an oxide layer that shares some elements from both the cylindrical body and the insulating layer. The cylindrical member for a fluid processing device according to claim 1 or 2.

4. The chemical bonding layer comprises Si, Cr and O; The cylindrical member for a fluid treatment device according to claim 3 .

5. an electrically heated carrier capable of heating the exhaust gas; The cylindrical member for a fluid treatment device according to claim 1 or 2, which houses the electrically heated carrier; Equipped with Fluid processing equipment.

Images