JP2017180327A - Diffusion member, exhaust gas emission control device and use of diffusion member in exhaust gas emission control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a diffusion member capable of suppressing temperature reduction of exhaust gas, excellent in corrosion resistance against a by-product of urine, easy to connect to an exhaust pipe, and capable of extremely easily changing design according to a shape of the exhaust pipe or a flow passage.SOLUTION: A diffusion member is installed in an exhaust pipe, and configured to obstruct part of flow of exhaust gas inflowing from an upstream side of the exhaust pipe. The diffusion member comprises a ceramic member and a metal member. The metal member is a rod-like body. The ceramic member covers the periphery of the rod-like body so as to expose both ends of the rod-like body. The volume of the ceramic member constituting the diffusion member is made larger than the volume of the metal member.SELECTED DRAWING: Figure 1

Description

The present invention relates to a diffusion member, an exhaust gas purification device, and use of the diffusion member in the exhaust gas purification device.

Since generation of NOx is inevitable in a diesel engine, a method for removing this is essential. For removing NOx, a selective catalytic reduction system (urea SCR system) using urea as a reducing agent has been put into practical use.

In the urea SCR system, urea water is injected into the exhaust pipe. The injected urea water is hydrolyzed and thermally decomposed by the heat of the exhaust gas to become ammonia, and acts as a reducing agent that reduces NOx to N ₂ . Therefore, in order to sufficiently reduce NOx in the exhaust gas, it is necessary to sufficiently mix ammonia as a reducing agent and the exhaust gas.
It should be noted that it is important to sufficiently mix the exhaust gas in the exhaust pipe not only in the urea SCR system but also when used in combination with various sensors.

In the above-described urea SCR system or the like, when the exhaust pipe has a sufficiently large inner diameter or a sufficiently long exhaust pipe, the exhaust gas is sufficiently mixed. There are cases where the inner diameter cannot be made sufficiently large and the length of the exhaust pipe cannot be made sufficiently long. As a method for mixing the exhaust gas in such a case, Patent Document 1 discloses a method of providing a stationary mixer in the exhaust pipe, and Patent Document 2 provides a mixer or swirler in the exhaust pipe, A method for generating a swirling flow is disclosed.

Special table 2001-516635 gazette JP 2008-280882 A

However, when the static mixer described in Patent Document 1 or the mixer / swirler described in Patent Document 2 is used, the heat energy of the exhaust gas is deprived by the static mixer, the mixer, and the swirler. There was a problem that temperature fell. When the temperature of the exhaust gas is lower than the operating temperature range of the exhaust gas purification catalyst mounted downstream, it may not be possible to exert a sufficient purification action. Patent Document 1 discloses that a static mixer is made of plastic or metal. However, a static mixer made of plastic has a problem in heat resistance and durability. In a static mixer made of metal, urea water and ammonia are disclosed. In addition to concern about corrosion due to, there was a problem of reducing the temperature of exhaust gas as described above.

In the urea SCR system, urea water is injected into the exhaust pipe and is hydrolyzed by the heat of the exhaust gas to generate ammonia as a reducing agent. At this time, if the temperature inside the exhaust pipe is too low, the urea water is Hydrolysis and thermal decomposition do not proceed normally, and by-products (hereinafter also referred to as urea water by-products) tend to be generated. Since the by-product of urea water is more corrosive than ammonia, when the stationary mixer made of metal described in Patent Document 1 is used in the urea SCR system, the temperature of the exhaust gas is lowered to reduce NOx in the catalyst carrier. Not only does the efficiency of the reaction decrease, but there is a problem that the static mixer is more easily corroded by the by-product of urea water. Therefore, the stationary mixer used in the urea SCR system is required to solve not only the above-described problem of exhaust gas temperature decrease but also the problem of corrosion resistance to urea water by-products.

When the static mixer is made of plastic, it is difficult to receive the above-described corrosion, but the plastic static mixer cannot be fixed inside the exhaust pipe as it is. Therefore, there is a problem that it is necessary to fix the stationary mixer made of plastic separately to a metal member or the like, and to fix the metal member by welding or the like inside the exhaust pipe.

Patent Document 2 does not disclose what kind of material the mixer and swirler are made of and how the temperature of exhaust gas is reduced by the mixer and swirler.

As a result of intensive studies by the present inventors in view of the above-mentioned problems, the diffusion member is formed into a rod-shaped metal member (also referred to as a rod-shaped body) and the periphery of the rod-shaped body so that both ends of the rod-shaped body are exposed. Composed of a ceramic member to cover, can suppress the temperature drop of exhaust gas compared to a metal diffusion member, has excellent corrosion resistance against by-products of urea water, and is easy to connect to the exhaust pipe It has been found that the design can be changed very easily according to the shape and flow path of the exhaust pipe, and the present invention has been achieved.

That is, the diffusion member of the present invention is a diffusion member that is installed in the exhaust pipe and partially obstructs the flow of exhaust gas flowing in from the upstream of the exhaust pipe, and the diffusion member includes a ceramic member and a metal member, The metal member is a rod-shaped body, the ceramic member covers the periphery of the metal member so that both ends of the rod-shaped body are exposed, and the volume of the ceramic member constituting the diffusion member is the volume of the metal member It is characterized by being larger than.

The diffusion member of the present invention includes a ceramic member and a metal member, and the volume of the ceramic member is larger than the volume of the metal member. That is, most of the material constituting the diffusion member is ceramic. Therefore, the temperature reduction of exhaust gas can be suppressed as compared with a diffusion member made of only metal.

In the diffusing member of the present invention, the ceramic member covers the periphery of the metal member so that a part of the metal member is exposed. That is, the diffusion member of the present invention can be easily disposed in the exhaust pipe by welding the exposed portion of the metal member to the inside of the exhaust pipe.
And since the ceramic member has covered the surface except the location where the metal member mentioned above is exposed, it is hard to receive the corrosion by the by-product of urea water.

The diffusion member of the present invention is composed of a rod-shaped metal member (also referred to as a rod-shaped body) and a ceramic member covering the periphery of the metal member so that both ends of the metal member are exposed.
When the diffusing member has the shape described above, it is easy to optimize the effect of the diffusing member for each shape of the exhaust pipe to be installed by combining a plurality of the diffusing members and arranging them in the exhaust pipe. Therefore, it is not necessary to prepare a new mold or the like for each exhaust gas purifying apparatus having a different configuration, and the manufacturing cost can be suppressed.

In the diffusing member of the present invention, it is preferable that the exposed area of the ceramic member is larger than the exposed area of the metal member on the outermost surface of the diffusing member.
If the exposed area of the ceramic member is larger than the exposed area of the metal member on the outermost surface of the diffusion member of the present invention, the heat of the exhaust gas is not easily transmitted to the diffusion member, and further, it is more susceptible to corrosion by the byproduct of urea water. It becomes difficult.

In the diffusion member of the present invention, it is preferable that pores are formed in the ceramic member.
If pores are formed in the ceramic member, the pores prevent heat conduction inside the ceramic member, so that excellent heat insulation can be obtained and the temperature of the exhaust gas can be further suppressed from decreasing.

In the diffusion member of the present invention, the ceramic member preferably has a porosity of 5 to 60%.
A porosity of the ceramic member of 5 to 60% is particularly preferable from the viewpoint of achieving both the mechanical strength of the diffusion member and the effect of suppressing the temperature decrease of the exhaust gas.

In the diffusing member of the present invention, it is preferable that the ceramic member is not formed with a continuous air hole.
When the continuous air hole is formed in the ceramic member, the mechanical strength of the ceramic member is likely to be lowered. Further, if there is a continuous air hole, the exhaust gas that has contacted the diffusion member moves through the ceramic member and easily comes into contact with the metal member. Therefore, the continuous air hole is formed in the ceramic member from the viewpoint of suppressing corrosion of the metal member. Preferably not.
The continuous air holes are pores formed continuously from the surface of the ceramic member that can contact the exhaust gas to the interface of the ceramic member that contacts the metal member. In the case where a gap is formed between the ceramic member and the metal member, the pores are continuously formed from the surface that can contact the exhaust gas of the ceramic member to the surface exposed to the gap of the ceramic member. .

In the diffusing member of the present invention, the pores formed in the ceramic member are preferably closed pores.
When the pores formed in the ceramic member are closed pores, it is possible to prevent the exhaust gas from penetrating into the ceramic member and corroding the metal member.

In the diffusion member of the present invention, it is preferable that a gap exists between the metal member and the ceramic member.
If there is a gap between the metal member and the ceramic member, it is easy to suppress the occurrence of cracks resulting from the difference in thermal expansion coefficient between the ceramic member and the metal member.

In the diffusing member of the present invention, the ceramic member is preferably made of a crystalline inorganic material and / or an amorphous inorganic material.
When the ceramic member contains a crystalline inorganic material, the heat resistance and mechanical strength of the ceramic member can be improved.
When the ceramic member contains an amorphous inorganic material, it becomes difficult to form rough atmospheric holes and continuous air holes in the ceramic member, so that the metal member can be easily prevented from coming into contact with the exhaust gas.
Further, when the ceramic member is made of an amorphous inorganic material and a crystalline inorganic material, the crystalline inorganic material plays a role of mechanically strengthening the ceramic member made of the amorphous inorganic material. Strength can be improved.

In the diffusing member of the present invention, the crystalline inorganic material is preferably made of at least one selected from the group consisting of alumina, silica, zirconia, zircon, yttria, calcia, magnesia, ceria and hafnia.
When the crystalline inorganic material is at least one selected from the group consisting of alumina, silica, zirconia, zircon, yttria, calcia, magnesia, ceria and hafnia, the ceramic member is excellent in heat resistance and heat insulation performance.

In the diffusing member of the present invention, the crystalline inorganic material is preferably made of at least one selected from the group consisting of zirconia and zircon.
When the crystalline inorganic material is at least one selected from the group consisting of zirconia and zircon, the ceramic member is particularly excellent in heat resistance and heat insulation.

The exhaust gas purification apparatus of the present invention includes an exhaust pipe through which exhaust gas containing nitrogen oxides flows, a urea injection apparatus that is provided upstream of the exhaust pipe and injects urea into the exhaust pipe, and a downstream side of the exhaust pipe. An exhaust gas purifying device comprising a provided catalyst carrier, wherein one or more diffusion members of the present invention are arranged at a site where exhaust gas contacts downstream of the urea injector and upstream of the catalyst carrier. The diffusion member is welded to the exhaust pipe at a portion where the metal member is exposed.

In the exhaust gas purifying apparatus of the present invention, one or more diffusion members of the present invention are arranged at a site where the exhaust gas contacts downstream of the urea injection device and upstream of the catalyst carrier.
Therefore, the exhaust gas purification apparatus of the present invention is less susceptible to corrosion of the diffusion member by the by-product of the urea water injected from the urea injection device, and further, the temperature reduction of the exhaust gas is suppressed, so that the reaction efficiency of the SCR reaction in the catalyst carrier Is good. In addition, it is easy to install the diffusing member during manufacturing.
When welding the portion of the diffusion member where the metal member is exposed and the exhaust pipe, the metal member constituting the diffusion member and the exhaust pipe may be directly welded or may be welded by brazing or the like. .

In the exhaust gas purification apparatus of the present invention, it is preferable that a ceramic coat layer covering the welded portion is formed at a welded portion between the portion where the metal member is exposed and the exhaust pipe.
When the ceramic coat layer which covers a welding part is formed in the welding part of the part which a metal member exposes, and an exhaust pipe, it can suppress that a welding part receives the corrosion by the by-product of urea water.

Use of the diffusion member of the present invention includes an exhaust pipe through which exhaust gas containing nitrogen oxides flows, a urea injection device that is provided upstream of the exhaust pipe and injects urea into the exhaust pipe, and a downstream side of the exhaust pipe The flow of exhaust gas flowing in from the upstream of the exhaust pipe at a site where the exhaust gas contacts the exhaust gas purification device comprising a catalyst carrier provided on the downstream side of the urea injection device and upstream of the catalyst carrier And, when the urea injected from the urea injection device is sufficiently mixed with the exhaust gas to reduce the bias of the components contained in the exhaust gas, the temperature of the exhaust gas is suppressed from decreasing, and The use of the diffusion member of the present invention to prevent the diffusion member from being corroded by urea and / or decomposition products of the urea injected from the urea injection device.

As described above, the diffusion member of the present invention includes a ceramic member and a metal member, and the volume of the ceramic member is larger than the volume of the metal member. Therefore, the temperature reduction of exhaust gas can be suppressed as compared with a diffusion member made of only metal. Furthermore, in the diffusion member of the present invention, the ceramic member covers the periphery of the metal member so that a part of the metal member is exposed. Therefore, the diffusion member can be easily disposed in the exhaust pipe by welding the exposed portion of the metal member to the inside of the exhaust pipe.
Therefore, the diffusion member of the present invention is provided with an exhaust pipe through which exhaust gas containing nitrogen oxides flows, a urea injection device that is provided upstream of the exhaust pipe and injects urea into the exhaust pipe, and a downstream side of the exhaust pipe Injecting from the urea injection device by using the exhaust gas purification device comprising the catalyst carrier provided on the downstream side of the urea injection device and the upstream side of the catalyst carrier at the site where the exhaust gas contacts When reducing the deviation of components contained in the exhaust gas by sufficiently mixing the released urea with the exhaust gas, the temperature of the exhaust gas is suppressed and urea injected from the urea injection device and / or the urea It is possible to prevent the diffusion member from being corroded by the decomposition product. Here, the decomposition product of urea refers to a by-product of ammonia and urea water.
When the diffusion member of the present invention is used, the portion of the diffusion member where the metal member is exposed can be easily placed in the exhaust pipe by welding or the like with the inside of the exhaust pipe.

Fig.1 (a) is a perspective view which shows typically an example of the diffusion member of this invention, and FIG.1 (b) is the sectional view on the AA line in Fig.1 (a). FIG. 2 is a perspective view showing an example in which a plurality of diffusion members of the present invention are combined and arranged in the exhaust pipe. Fig.3 (a) is a perspective view which shows typically another example of the diffusion member of this invention, FIG.3 (b) is a BB sectional drawing in Fig.3 (a). FIG. 4A is a schematic view schematically showing the exhaust gas purification apparatus of the present invention, and FIG. 4B is an enlarged view of a broken line region H in FIG. 4A.

(Detailed description of the invention)
Hereinafter, the diffusion member of the present invention will be described in detail.

The diffusion member of the present invention includes a ceramic member and a metal member, and the volume of the ceramic member is larger than the volume of the metal member. That is, most of the material constituting the diffusion member is ceramic. Therefore, the temperature reduction of exhaust gas can be suppressed as compared with a diffusion member made of only metal.

In the diffusing member of the present invention, the ceramic member covers the periphery of the metal member so that a part of the metal member is exposed. That is, the diffusion member of the present invention can be easily disposed in the exhaust pipe by welding the exposed portion of the metal member to the inside of the exhaust pipe.
And since the ceramic member has covered the surface except the location where the metal member mentioned above is exposed, it is hard to receive the corrosion by the by-product of urea water.

The shape of the diffusion member of the present invention will be described.
The diffusing member of the present invention includes a rod-shaped metal member (also referred to as a rod-shaped body) such as a cylindrical shape or a polygonal column shape, and a ceramic member that covers the periphery of the rod-shaped body so that both ends of the rod-shaped body are exposed. . By fixing one or more diffusion members having such a shape in the exhaust pipe in an appropriate arrangement, the configuration of each exhaust gas purification device (temperature of exhaust gas, shape of exhaust pipe, distance to catalyst carrier, urea water injection nozzle Since the arrangement of the diffusing member can be optimized according to the position and the injection angle, the present invention can be applied to exhaust gas purification apparatuses having any configuration. Furthermore, since it is not necessary to prepare a new mold or the like for each exhaust gas purifying apparatus having a different configuration, the manufacturing cost can be suppressed.

In the diffusing member of the present invention, a gap is preferably formed between the metal member and the ceramic member.
If there is a gap between the metal member and the ceramic member, it is easy to suppress the occurrence of cracks resulting from the difference in thermal expansion coefficient between the ceramic member and the metal member.

In the diffusing member of the present invention, examples of the material constituting the metal member include aluminum, stainless steel, steel, iron, copper, Inconel (registered trademark), Hastelloy (registered trademark), and Invar (registered trademark).
When the metal member is made of these materials, the mechanical strength of the diffusing member can be improved, and further, joining to the exhaust pipe is facilitated.

In the diffusion member of the present invention, the thermal expansion coefficient of the material constituting the metal member is preferably close to the thermal expansion coefficient of the material constituting the ceramic member, and the thermal expansion coefficient of the material constituting the metal member and the ceramic member are configured. It is preferable that the difference of the thermal expansion coefficient of the material to perform is 10.0 * 10 <^-6> K <^-1> or less.
In the diffusion member of the present invention, when the difference between the thermal expansion coefficient of the material constituting the metal member and the thermal expansion coefficient of the material constituting the ceramic member is 10.0 × 10 ⁻⁶ K ⁻¹ or less, the metal member is configured. Generation of cracks due to the difference in thermal expansion between the material to be formed and the material constituting the ceramic member can be suppressed.

In the diffusing member of the present invention, the metal member may be composed of a single continuous metal member, or may be composed of a plurality of metal members.

In the diffusing member of the present invention, the exposed area of the ceramic member is preferably larger than the exposed area of the metal member on the outermost surface of the diffusing member.
If the exposed area of the ceramic member is larger than the exposed area of the metal member on the outermost surface of the diffusion member of the present invention, the heat of the exhaust gas is not easily transmitted to the diffusion member, and further, it is more susceptible to corrosion by the byproduct of urea water. It becomes difficult.
The ratio of the area of the ceramic member and the area of the metal member on the outermost surface of the diffusion member of the present invention can be determined visually. When it is desired to measure more precisely, the image data obtained by photographing the diffusion member can be corrected and calculated according to the shape of the diffusion member.
In calculating the exposed area of the ceramic member and the exposed area of the metal member, a region where the ceramic member and the metal member face each other with a gap therebetween is not considered.

The volume ratio of the ceramic member and the volume of the metal member in the diffusion member of the present invention can be measured by observing a cross section of the diffusion member made of the ceramic member and the metal member with a scanning electron microscope (SEM). . The SEM magnification is adjusted so that the entire thickness direction of the ceramic member and metal member is included. When the thickness of the ceramic member is less than 300 μm, it is 500 times, when it is 300 or more and less than 500 μm, it is 200 times, and 500 μm or more and less than 1000 μm. In this case, the magnification is 150 times. In the case of 1000 μm or more, it is 150 times or less. In addition, about the part in which the clearance gap is formed between the ceramic member and the metal member, you may observe a ceramic member and a metal member separately.
The volumes of the metal member and the ceramic member are obtained from the thickness of the ceramic member, the shape of the contact portion between the metal member and the ceramic member, and the outer dimensions of the diffusion member, which are obtained from the SEM image photographed by the above method. The number of SEM images to be taken is not particularly limited as long as the shape of the ceramic member and the metal member can be accurately grasped, and the number of measurement points may be appropriately increased according to the complexity of the shape of the ceramic member and the metal member. . The volume of pores formed in the ceramic member is included in the volume of the ceramic member, and the volume of the gap between the ceramic member and the metal member is not included in the volume of either the ceramic member or the metal member.

Whether or not continuous vents are formed in the ceramic member is obtained by photographing a cross-sectional view of the diffusion member in the normal direction of the surface of the metal member under the same conditions as the method for measuring the volume of the ceramic member and the volume of the metal member. Judgment is made based on the SEM image. If no continuous pores are formed from the surface of the ceramic member to the surface of the metal member in all of the ten SEM images photographed at random, it is determined that no continuous ventilation hole is formed in the ceramic member. In any one of 10 randomly selected SEM images, when continuous pores are formed from the surface of the ceramic member to the surface of the metal member, continuous air holes are formed in the ceramic member. to decide.

In the diffusing member of the present invention, examples of the material constituting the ceramic member include an amorphous inorganic material and a crystalline inorganic material, and any one kind or a mixture or composite of two or more kinds thereof may be used. However, from the viewpoint of heat insulation and corrosion resistance of the ceramic member, the ceramic member preferably contains an amorphous inorganic material, more preferably contains an amorphous inorganic material and a crystalline inorganic material, More preferably, the amorphous inorganic material is a material in which particles of the crystalline inorganic material are dispersed.
When the ceramic member contains a crystalline inorganic material, the heat resistance and mechanical strength of the ceramic member can be improved.
When the ceramic member contains an amorphous inorganic material, it becomes difficult to form rough atmospheric holes and continuous air holes in the ceramic member, so that the metal member can be easily prevented from coming into contact with the exhaust gas.

In the diffusion member of the present invention, when the material constituting the ceramic member includes an amorphous inorganic material and a crystalline inorganic material, the particles of the crystalline inorganic material serve to mechanically strengthen the ceramic member. The heat resistance and mechanical strength of the member can be improved.

In the diffusion member of the present invention, when the crystalline inorganic material is present in the material constituting the ceramic member, the pores in which the particles of the crystalline inorganic material are present in the ceramic member when the ceramic member is at a high temperature Therefore, it is possible to prevent the heat insulation performance from being deteriorated due to coalescence of pores.

When the mechanical strength of the ceramic member constituting the diffusing member of the present invention is increased, the ceramic member is destroyed due to impact caused by vibration of the exhaust pipe or collision of foreign matter such as welding spatter contained in exhaust gas discharged from the engine. Can be suppressed.

In the diffusing member of the present invention, the ceramic member may be composed of a first ceramic member and a second ceramic member formed on the surface of the first ceramic member.
As the material constituting the first ceramic member and the second ceramic member, the material constituting the above-described ceramic member can be suitably used. For example, the ceramic member constituting the diffusion member of the present invention is crystalline. The first ceramic member made of the equipment and the second ceramic member made of the amorphous inorganic material may be configured, and the first ceramic member made of the amorphous inorganic material and the first ceramic member made of the amorphous inorganic material. It may be composed of two ceramic members.
The manufacturing method of the first ceramic member and the manufacturing method of the second ceramic member may be the same or different.

In the diffusion member of the present invention, the amorphous inorganic material that can be used as the material of the ceramic member preferably contains amorphous silica, and more preferably contains 20% by weight or more of amorphous silica. More preferably, the glass is a low softening point glass having a softening point of 300 to 1000 ° C.

The kind of the low softening point glass is not particularly limited, but soda lime glass, alkali-free glass, borosilicate glass, potash glass, crystal glass, titanium crystal glass, barium glass, strontium glass, alumina silicate glass, soda zinc Examples thereof include glass and soda barium glass.
These low softening point glasses may be used alone, or two or more kinds may be mixed.

In the diffusion member of the present invention, when the amorphous inorganic material used as the material of the ceramic member is a low softening point glass having a softening point of 300 to 1000 ° C., the low softening point glass is melted or formed in the ceramic member forming stage. It becomes easy to soften. Since the melted or softened low-melting glass adheres to the surface of the metal member, a ceramic member having excellent adhesion to the metal member can be easily formed.
However, when the material of the metal member is aluminum and the ceramic member is directly formed on the surface of the metal member, the amorphous inorganic material is preferably a low softening point glass having a softening point of 300 to 550 ° C.
If the amorphous inorganic material is a low softening point glass having a softening point of 300 to 550 ° C., the amorphous inorganic material softens at a temperature lower than the temperature at which the aluminum that is the metal member melts, so that the metal member is deteriorated. The ceramic member can be formed without any problem.

When the softening point of the amorphous inorganic material is less than 300 ° C., the temperature of the softening point is too low, so that during the heat treatment, the softened amorphous inorganic material easily flows due to melting or the like, and the shape of the ceramic member is reduced. It becomes difficult to obtain a desired shape. On the other hand, when the softening point of the amorphous inorganic material exceeds 1000 ° C., on the contrary, it is necessary to set the temperature of the heat treatment to be extremely high, so that the mechanical characteristics of the metal member may be deteriorated by heating.

In the diffusion member of the present invention, the softening point of the amorphous inorganic material used as the material of the ceramic member is based on a method defined in JIS R 3103-1: 2001, for example, a glass automatic manufactured by Opt Corp. It can be measured using a softening point / strain point measuring apparatus (SSPM-31).

Kind of the borosilicate glass is not particularly _limited, SiO ₂ -B ₂ O 3 -ZnO type _{glass, SiO 2 -B 2 O 3 -Bi} 2 O 3 system glass. The crystal glass is a glass containing PbO, and the type thereof is not particularly limited, but SiO ₂ —PbO glass, SiO ₂ —PbO—B ₂ O ₃ glass, SiO ₂ —B ₂ O ₃ —PbO glass. Etc. Kind of the barium glass is not particularly limited, include BaO-SiO ₂ based glass or the like.
Further, the amorphous inorganic material may be composed of only one kind of the above-mentioned low softening point glasses, or may be composed of plural kinds of low softening point glasses.

Examples of the low softening point glass having a softening point of 300 to 550 ° C. include SiO ₂ —TiO ₂ glass, SiO ₂ —PbO glass, SiO ₂ —PbO—B ₂ O ₃ glass, and B ₂ O ₃ —PbO glass. Al ₂ O ₃ —SiO ₂ —B ₂ O ₃ —PbO glass, Na ₂ O—P ₂ O ₅ —SiO ₂ glass, and the like.

Subsequently, the crystalline inorganic material will be described.

In the diffusion member of the present invention, when the ceramic member contains a crystalline inorganic material, the crystalline inorganic material includes alumina, silica, zirconia, zircon, yttria, calcia, magnesia, ceria, hafnia, forsterite, steatite, cordierite. It is preferably composed of at least one selected from the group consisting of mullite, aluminum titanate, potassium titanate and mica, and consists of alumina, silica, zirconia, zircon, yttria, calcia, magnesia, ceria and hafnia. It is more preferably composed of at least one selected from the group, and further preferably composed of at least one selected from the group consisting of zirconia and zircon.
Furthermore, the crystalline inorganic material preferably contains at least zirconia, more preferably contains 20% by weight or more of zirconia, from the viewpoint of mechanical strength and corrosion resistance of the ceramic member, More preferably, the content is 50% by weight or more.

The zirconia is preferably stabilized zirconia to which a stabilizer such as yttria, calcia, magnesia, alumina, ceria is added.
Examples of the stabilized zirconia include yttria stabilized zirconia, calcia stabilized zirconia, magnesia stabilized zirconia, alumina stabilized zirconia, and ceria stabilized zirconia.
The content of the stabilizer is preferably 5 to 30% by weight of the total amount of stabilized zirconia.
A part of zirconium constituting zirconia may be substituted with hafnium.

The mica may be either natural mica or artificial mica. Moreover, the composite_body | complex of mica and another crystalline inorganic material may be sufficient. Examples of the composite of mica and other crystalline inorganic material include Micalex (registered trademark) obtained by hot forming a mixture of mica and glass.

Silica is crystalline silica which may contain amorphous silica, and may be a molded body obtained by mixing these with other crystalline inorganic materials and / or inorganic fibers, and this powder.
Examples of the molded body formed by mixing silica fine particles and inorganic fibers and this powder include Microtherm (registered trademark).

In the diffusion member of the present invention, the ceramic member may further contain inorganic fibers. Examples of the inorganic fiber include silica alumina fiber, mullite fiber, alumina fiber, silica fiber, glass fiber, carbon fiber, silicon carbide fiber, silicon nitride fiber, zirconia fiber, and potassium titanate fiber.
When the ceramic member contains inorganic fibers, the mechanical strength of the ceramic member can be improved.

It is preferable that pores are formed in the ceramic member constituting the diffusion member of the present invention.
If pores are formed in the ceramic member, the pores prevent heat conduction inside the ceramic member, so that excellent heat insulation can be obtained and the temperature of the exhaust gas can be further suppressed from decreasing.

The porosity of the ceramic member in the diffusing member of the present invention is preferably 5 to 60%, more preferably 10 to 55%, and still more preferably 15 to 50%. The porosity of the ceramic member in the diffusing member of the present invention is particularly preferably 5 to 60% from the viewpoint of achieving both the mechanical strength of the diffusing member and the effect of suppressing the temperature reduction of the exhaust gas.

When the porosity of the ceramic member constituting the diffusion member of the present invention is 5 to 60% and the pores in the ceramic member are evenly dispersed, the heat transfer in the ceramic member is more effectively blocked. Therefore, particularly good heat insulation can be exhibited.

The porosity of the ceramic member constituting the diffusing member of the present invention can be determined by the Archimedes method, specifically, for example, by the following method.
First, as a pretreatment, a sample to be subjected to porosity measurement is washed with ultrasonic waves using ion-exchanged water and acetone, and then dried at 100 ° C.
Next, the sample subjected to the pretreatment is boiled with ion-exchanged water for 3 hours to prepare a saturated sample. Subsequently, the saturated sample is hung with a thread in water, and the buoyancy (W1) of the saturated sample is measured with an electronic balance. Further, the mass (W2) of the saturated sample is measured with an electronic balance, dried at 120 ° C. for 60 minutes, and then the mass (W3) of the dried sample is measured.
Using the results obtained by the above method, the porosity is calculated by the following calculation formula.
{[Mass of saturated sample (W2) −mass of dry sample (W3)] / buoyancy of saturated sample (W1)} × 100 (%)
In addition, when the ceramic member is comprised from the 1st ceramic member and the 2nd ceramic member, the porosity of the 1st ceramic member and the porosity of the 2nd ceramic member are measured separately, respectively. The total value of the values multiplied by the volume ratio constituting the member is defined as the porosity of the ceramic member.

When the porosity of the ceramic member constituting the diffusing member of the present invention is less than 5%, the proportion of pores is too small, and thus the heat insulation may not be sufficient. On the other hand, when the porosity of the ceramic member constituting the diffusing member of the present invention exceeds 60%, the ratio of the pores is excessively increased, so that the heat insulation performance and mechanical strength are reduced due to coalescence of the pores. .

As the average pore diameter of the pores in the ceramic member constituting the diffusion member of the present invention is smaller, heat transfer due to radiant heat transfer and convective heat transfer in the pores can be reduced. Specifically, the thickness is preferably 0.1 to 150 μm, more preferably 0.1 to 50 μm, and still more preferably 0.1 to 5 μm. When the average pore diameter of the pores is 0.1 to 150 μm, heat transfer in the ceramic member can be effectively prevented by the pores, and high thermal insulation of the ceramic member can be maintained.

It is technically difficult to make the average pore diameter of pores in the ceramic member constituting the diffusing member of the present invention less than 0.1 μm, and in order to form such pores, a very small pore former is used. It is necessary to use a special material such as, which is not preferable because the material cost increases rapidly. On the other hand, when the average pore diameter of the pores in the ceramic member constituting the diffusing member of the present invention exceeds 50 μm, the ceramic member has few solid portions, so that the mechanical properties of the ceramic member are deteriorated. In addition, pores having a diameter exceeding 150 μm have a risk of reducing heat insulation because heat dissipation effect is promoted by convective heat transfer in the pores.

The average pore diameter of the pores in the ceramic member constituting the diffusing member of the present invention can be measured by cutting the diffusing member and observing the cross section with a digital microscope or SEM.

Specifically, a digital microscope image or SEM image is taken so that a predetermined region (500 μm × 500 μm) of the ceramic member enters, and the pore diameters of all the pores existing in the predetermined region are measured, and the average The average pore diameter can be obtained by determining the value. When the shape of the pores is not substantially spherical, the diameter of the pores is the diameter corresponding to the projected area circle (Haywood diameter).
When the ceramic member is composed of the first ceramic member and the second ceramic member, the average pore diameter of the pores in the first ceramic member and the average pore diameter of the pores in the second ceramic member Are individually measured, and the total value of the values obtained by multiplying the volume ratio of the ceramic member is defined as the average pore diameter of the pores in the ceramic member.

In the diffusing member of the present invention, it is preferable that the ceramic member has no continuous air hole.
When the continuous air hole is formed in the ceramic member, the mechanical strength of the ceramic member is likely to be lowered. Further, if there is a continuous air hole, the exhaust gas that has contacted the diffusion member moves through the ceramic member and easily comes into contact with the metal member. Therefore, the continuous air hole is formed in the ceramic member from the viewpoint of suppressing corrosion of the metal member. Preferably not.

In the diffusion member of the present invention, the pores formed in the ceramic member are preferably closed pores.
When the pores formed in the ceramic member are closed pores, it is possible to prevent the exhaust gas from penetrating into the ceramic member and corroding the metal member.

The diffusion member of the present invention preferably has an exposed area of the ceramic member larger than an exposed area of the metal member on the outermost surface.
When the exposed area of the ceramic member on the outermost surface of the diffusing member is larger than the exposed area of the metal member, the temperature reduction of the exhaust gas can be effectively suppressed.
When the exposed area of the ceramic member on the outermost surface of the diffusion member is equal to or smaller than the exposed area of the metal member, the exposed area of the metal member is too large, and the temperature of the exhaust gas may be excessively lowered. Furthermore, since the metal member is easily corroded by the by-product of urea water, the progress of the corrosion of the diffusion member may not be sufficiently suppressed.

In the diffusing member of the present invention, the surface roughness (Rzjis) of the ceramic member on the outermost surface of the diffusing member is preferably 0.1 to 10 μm.
Since the surface roughness (Rzjis) of the ceramic member on the outermost surface of the diffusing member is 0.1 to 10 μm, the flow of the exhaust gas that has passed through the surface of the diffusing member can be sufficiently disturbed. Can be sufficiently reduced.
In this specification, the surface roughness (Rzjis) is a ten-point average roughness (Rz) measured by a method according to JIS B 0601-1994, which is defined in Annex JA of JIS B 0601-2013. It is.

The diffusion member of the present invention preferably has a gap between the metal member and the ceramic member.
If there is a gap between the metal member and the ceramic member, it is easy to suppress the occurrence of cracks resulting from the difference in thermal expansion coefficient between the ceramic member and the metal member.
When the difference between the thermal expansion coefficient of the material constituting the metal member and the thermal expansion coefficient of the material constituting the ceramic member exceeds 10.0 × 10 ⁻⁶ K ⁻¹ , the material constituting the metal member and the ceramic member are Since cracks due to differences in the thermal expansion coefficients of the constituent materials are likely to occur, it is particularly preferable to provide a gap between the metal member and the ceramic member in order to suppress this.

The thermal expansion coefficient of the metal member and ceramic member in the present invention refers to a linear thermal expansion coefficient measured by the following method.

<Measurement method of thermal expansion coefficient>
A metal member and a ceramic member are cut out to a size of 3 mm × 3 mm × 15 mm to obtain a measurement sample, and this measurement sample is installed in a measurement device (thermal expansion meter TD5000SA manufactured by NETZSCH) to measure the thermal expansion coefficient. .
The measurement conditions are an air atmosphere, a temperature increase rate of 10 ° C./min, and a temperature range of 25 to 430 ° C.

The shape of the diffusion member of the present invention will be further described in detail.
Examples of the shape of the diffusing member of the present invention include the shape shown in FIG.
Fig.1 (a) is a perspective view which shows typically an example of the diffusion member of this invention, and FIG.1 (b) is the sectional view on the AA line in Fig.1 (a).
A diffusion member 10 shown in FIGS. 1A and 1B includes a rod-shaped metal member 11 and a ceramic member 12 covering the periphery thereof, and both end portions 11a and 11b of the metal member 11 are covered with the ceramic member. It is not exposed and is exposed on the outermost surface.
When the diffusion member 10 is installed in the exhaust pipe, it can be easily fixed by welding both end portions 11a and 11b of the metal member 11 exposed on the outermost surface to the inside of the exhaust pipe.
A plurality of diffusion members 10 may be installed in the exhaust pipe in order to obtain a desired effect.

The method for disposing the diffusion member of the present invention inside the exhaust pipe is not particularly limited, and one or more diffusion members are considered in consideration of the shape of the exhaust pipe, the urea water injection position, the position to the catalyst carrier, and the like. For example, a plurality of diffusion members may be combined and arranged inside the exhaust pipe as shown in FIG. FIG. 2 is a perspective view showing an example in which a plurality of diffusion members of the present invention are combined and arranged in the exhaust pipe.
In the exhaust pipe shown in FIG. 2, a total of nine diffusion members 10 of 3 × 3 are arranged so as to be substantially perpendicular to each other to form a lattice.

Examples of the shape of the diffusing member of the present invention include the shape shown in FIG.
Fig.3 (a) is a perspective view which shows typically another example of the diffusion member of this invention, FIG.3 (b) is a BB sectional drawing in Fig.3 (a).
The diffusion member 20 shown in FIG. 3A is composed of a rod-shaped metal member 21 and a ceramic member 22 covering the periphery thereof. Both end portions 21a and 21b of the metal member 21 are not covered with the ceramic member 22, Exposed on the surface. Further, as shown in FIG. 3B, a gap 23 is formed between the metal member 21 and the ceramic member 22.

In calculating the exposed area of the ceramic member and the exposed area of the metal member, a region where the ceramic member and the metal member face each other with a gap therebetween is not considered.
That is, for example, in the diffusing member 20 shown in FIGS. 3A and 3B, a region 22 a facing the metal member 21 across the gap 23 in the surface of the ceramic member 22 is made of the ceramic member. The exposed area of the metal member 21 is not regarded as the exposed area of the metal member 21.

Next, a method for producing the diffusion member of the present invention will be described.
As a method for producing the diffusion member of the present invention, for example, a raw material composition (also referred to as a ceramic raw material) serving as a raw material for a ceramic member is applied to the surface of a metal member processed to a size smaller than the desired size of the diffusion member A method of drying and firing, a method of placing a metal member in a mold and pouring the raw material composition into the mold, drying and firing, and a film by spraying a material to be a ceramic member on the surface of the metal member The method of forming is mentioned.
The ceramic member is not necessarily formed on the surface of the metal member, and the diffusion member may be manufactured by separately creating the metal member and the ceramic member and combining them at the end.

[Metal member preparation process]
The metal member can be obtained by processing a metal material as a raw material into a desired shape.
As a method of processing a metal member into a desired shape, a conventionally known metal processing technique can be used, and examples thereof include molding by a press machine and molding by cutting. A plurality of metal materials may be joined by welding or the like.

In the method for producing the diffusion member of the present invention, in the metal member preparation step, a cleaning process for removing impurities on the surface of the metal member may be performed as necessary. The cleaning process is not particularly limited, and a conventionally known cleaning process can be performed. Specifically, a method of performing ultrasonic cleaning in an alcohol solvent or the like can be used.

In the method for producing the diffusion member of the present invention, in the metal member preparation step, a roughening treatment for roughening the surface of the metal member may be performed as necessary. By roughening the surface of the metal member, the specific surface area of the metal member is increased, so that the adhesion with the ceramic member is improved.
Moreover, you may perform the washing | cleaning process mentioned above after the roughening process.

[Ceramic material preparation process]
Examples of the method for forming the ceramic member include a method of firing a raw material composition to be a ceramic member, and a method of forming a film by spraying a raw material to be a ceramic member on the surface of a metal member.

First, a method using a raw material composition will be described.
When applying the raw material composition used as a ceramic member on the surface of a metal member, and baking it, you may laminate | stack a ceramic member by repeating application | coating and baking of a raw material composition in multiple times.

When the diffusion member of the present invention is produced by a method using a raw material composition, as a raw material composition to be a raw material of the ceramic member, an amorphous inorganic material and / or a crystalline inorganic material constituting the ceramic member, If necessary, a mixture in which an inorganic binder, an organic binder, a pore former, a dispersion medium, a molding aid and the like are mixed can be used. At this time, in order to improve the mechanical strength of the ceramic member, inorganic fibers or the like may be added to the raw material composition.

When the diffusion member of the present invention is produced by a method using a raw material composition, the inorganic binder that may be added to the raw material composition used as the raw material of the ceramic member includes alumina sol, silica sol, titania sol, water glass, sepiolite, attapulgite Boehmite and the like, and two or more of these may be used in combination.

When the diffusion member of the present invention is produced by a method using a raw material composition, the organic binder that may be added to the raw material composition used as the raw material of the ceramic member is methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, polyethylene glycol, phenol Resins, epoxy resins and the like can be mentioned, and two or more of these may be used in combination.

When the diffusion member of the present invention is produced by a method using a raw material composition, the dispersion medium that may be added to the raw material composition used as the raw material of the ceramic member includes water, organic solvents such as methanol, ethanol, and acetone. Etc.

When the diffusion member of the present invention is produced by a method using a raw material composition, the molding aid that may be added to the raw material composition used as the raw material of the ceramic member includes ethylene glycol, dextrin, fatty acid, fatty acid soap, poly Alcohol etc. are mentioned, You may use these 2 or more types together.

When the diffusion member of the present invention is produced by the method using the raw material composition, the pore former that may be added to the raw material composition used as the raw material of the ceramic member is a micro hollow sphere containing an oxide ceramic as a component Examples thereof include balloons, spherical acrylic particles, carbon such as graphite, and foaming agents such as carbonate.
Among these, from the viewpoint of imparting high heat insulating properties to the ceramic member, it is preferable that pores having a small diameter are uniformly dispersed in the ceramic member, and therefore, a foaming agent such as carbon such as graphite and a carbonate is preferable. .

Examples of the carbonate foaming agent include CaCO ₃ , BaCO ₃ , NaHCO ₃ , Na ₂ CO ₃ , (NH ₄ ) ₂ CO _{3 and the} like.

Among these pore formers, carbon such as graphite is more preferable. This is because carbon can be dispersed as fine particles in the coating material for a diffusion member by a treatment such as pulverization, and can be decomposed by heating and baking to form pores having a suitable pore size.

When the diffusion member of the present invention is manufactured by the method using the raw material composition, when preparing the raw material composition used for forming the ceramic member, after preparing each raw material, wet pulverization is performed, The inorganic inorganic material and the crystalline inorganic material may be those initially adjusted to an appropriate particle size, or may be obtained with a target particle size by wet pulverization after the raw materials are prepared.

When the diffusion member of the present invention is produced by a method using a raw material composition, the final average particle diameter of the amorphous inorganic material constituting the raw material composition is preferably 0.1 to 100 μm, and preferably 1 to 20 μm. More preferred. In the range of 1 to 20 μm, it is presumed that the influence of electricity charged on the particle surface is small, but the particles are easily dispersed uniformly.

When the diffusion member of the present invention is produced by a method using a raw material composition, the final average particle diameter of the crystalline inorganic material constituting the raw material composition is preferably 0.1 to 150 μm.

When the diffusion member of the present invention is produced by a method using a raw material composition, the average particle diameter of the pore former constituting the raw material composition is preferably 0.1 to 25 μm, and preferably 0.5 to 10 μm. It is more preferable.
It becomes easy to adjust the average pore diameter in a ceramic member to 0.1-150 micrometers as the average particle diameter of the pore former which comprises a raw material composition is 0.1-25 micrometers.

When the diffusion member of the present invention is produced by a method using a raw material composition, the pore former is included in the raw material composition when the average particle size of the pore former particles constituting the raw material composition is less than 0.1 μm. Is difficult to disperse well, and as a result, the degree of dispersion of the pores in the formed ceramic member is reduced, and the pores are likely to coalesce at a high temperature.

On the other hand, when the diffusion member of the present invention is produced by the method using the raw material composition, when the average particle diameter of the pore former constituting the raw material composition exceeds 25 μm, it is formed in the ceramic member. The pore diameter becomes too large, and the heat insulating property and mechanical strength of the ceramic member tend to be lowered.

In producing the diffusion member of the present invention, examples of the method for forming the ceramic member around the metal member include a method of applying the above-described raw material composition to the surface of the metal member.
As a method for applying the raw material composition to the surface of the metal member, for example, a method such as spray coating, electrostatic coating, inkjet, transfer using a stamp or roller, brush coating, or electrodeposition coating may be used. it can.
Moreover, you may apply | coat a raw material composition to the surface of a metal member by immersing a metal member in a raw material composition.
At this time, a part of the metal member can be exposed on the surface of the diffusion member by creating a region where the raw material composition is not applied to a part of the metal member.
As a method for forming a region where the raw material composition is not applied to a part of the metal member, a conventionally known method can be used, and a method using a masking agent such as a masking tape or a masking sol can be used.

The raw material composition applied to the surface of the metal member becomes a ceramic member by heating and firing after drying.
In addition, dryers, such as a microwave dryer, a hot air dryer, a dielectric dryer, a vacuum dryer, a vacuum dryer, a freeze dryer, can be used for drying the raw material composition.

When the raw material composition includes an organic substance such as an organic binder, the raw material composition may be degreased after drying.
The degreasing conditions can be appropriately selected depending on the type and amount of organic matter contained in the raw material composition after drying, and for example, heating at 200 to 500 ° C. for 2 to 6 hours is preferable.

The firing temperature depends on the physical properties of the crystalline inorganic material and the amorphous inorganic material constituting the raw material composition, but when the amorphous inorganic material is included, the firing temperature is set to a temperature equal to or higher than the softening point of the amorphous inorganic material. It is preferable to heat. Specifically, it may be a temperature at which the metal member does not deteriorate, preferably 700 to 1100 ° C, more preferably 700 to 1000 ° C, and further preferably 750 to 950 ° C.
However, when the material constituting the metal member is aluminum and the raw material composition includes an amorphous inorganic material, a low softening point glass having a softening point of 300 to 550 ° C. is used as the amorphous inorganic material. It is preferable to heat at ~ 600 ° C.

Then, the manufacturing method of the diffusion member of the present invention using thermal spraying is explained.
Thermal spraying is a method in which a material to be a coating (also referred to as a thermal spraying material) is melted or softened by heating, accelerated into fine particles, and sprayed onto the surface of an object.
In thermal spraying, it is considered that a film of almost any material can be formed as long as it is a material that melts or softens by heating. Therefore, the ceramic member which comprises the diffusion member of this invention can be easily formed by thermal spraying.

The thermal spray material preferably contains a crystalline inorganic material, and may further contain an amorphous inorganic material and an inorganic binder.

As the crystalline inorganic material constituting the thermal spray material, zirconia or alumina is more preferable. More specifically, as the composition of zirconia, calcia-stabilized zirconia (5 wt% CaO—ZrO ₂ , 8 wt% CaO—ZrO ₂ , 31 wt% CaO—ZrO ₂ ), magnesia stabilized zirconia (20 wt% MgO—ZrO ₂ , 24 wt% MgO—ZrO ₂ ), yttria stabilized zirconia (6 wt% Y ₂ O ₃ —ZrO ₂ , 7 wt% Y ₂ O ₃ —ZrO ₂ , 8 wt% Y ₂ O ₃ —ZrO ₂ , 10 wt% Y ₂ O ₃ − ZrO ₂ , 12 wt% Y ₂ O ₃ —ZrO ₂ , 20 wt% Y ₂ O ₃ —ZrO ₂ ), zircon (ZrO ₂ —33 wt% SiO ₂ ), ceria-stabilized zirconia, and the like can be given. The content of the stabilizer is preferably 5 to 30% by weight of the total amount of stabilized zirconia. A part of zirconium constituting zirconia may be substituted with hafnium.
As the composition of alumina, more specifically, white alumina (Al ₂ O ₃ ), gray alumina (Al ₂ O ₃ -1.5 to ₄ wt% TiO ₂ ), alumina / titania (Al ₂ O ₃ -13 wt) _{% TiO 2, Al 2 O 3} -20wt% TiO 2, Al 2 O 3 -40wt% TiO 2, Al 2 O 3 -50wt% TiO 2), alumina-yttria _{(3Al 2 O 3 · 5Y 2} O 3), alumina magnesia _{(Mg · Al 2 O 4)} , alumina-silica _{(3Al 2 O 3 · 2SiO 2} ) , and the like.
Among these, zirconia having excellent heat resistance and corrosion resistance, low thermal conductivity having a thermal conductivity at 25 ° C. of 4 W / m · K or less is preferable, and yttria-stabilized zirconia is more preferable.

Although the average particle diameter of the crystalline inorganic material which comprises a thermal spray material is not specifically limited, 0.1-100 micrometers is preferable and 1-20 micrometers is more preferable.

As the amorphous inorganic material that may be contained in the thermal spray material, the same amorphous inorganic material that constitutes the ceramic member in the diffusion member of the present invention can be suitably used.

Examples of the inorganic binder that may be contained in the thermal spray material include alumina sol, silica sol, titania sol, water glass, sepiolite, attapulgite, and boehmite, and two or more of these may be used in combination.

As the thermal spraying method, plasma spraying, flame spraying, high-speed flame spraying, reduced pressure spraying, arc spraying, wire spraying, or explosion spraying can be used. In these, the plasma spraying which can form the ceramic member excellent in heat resistance is preferable, and gas plasma spraying is more preferable.
In the method using gas plasma spraying, the ceramic member is formed on the surface of the metal member by spraying a crystalline inorganic material powder constituting the ceramic member using a gas plasma of Ar—H ₂ or the like. .
When a ceramic member is formed using gas plasma spraying, the spraying conditions such as spraying current, spraying voltage, spraying distance, powder supply amount, Ar / H ₂ amount, etc. are sprayed particles (melted or softened crystalline inorganic material). Of the particles), the thickness of the target ceramic member, and the like.

When the ceramic member is formed by thermal spraying, masking may be performed on a region of the metal member where the ceramic member is not desired to be formed. By performing masking, a region where the ceramic member is not formed can be created, and the shape of the ceramic member can be controlled. Examples of the masking method include a method using a masking agent such as a masking tape or a masking sol.

In addition, when forming a ceramic member by thermal spraying, you may form a ceramic member by spraying a material directly on the surface of a metal member, and the 1st ceramic member formed by the method using the raw material composition mentioned above A second ceramic member may be formed on the surface by thermal spraying.

When the second ceramic member is formed on the first ceramic member, the first ceramic member is heated to soften the amorphous inorganic material (glass or the like) constituting the first ceramic member. More preferably, thermal spraying is performed. By performing thermal spraying in a state where the amorphous inorganic material constituting the first ceramic member is softened, the thermal spraying particles that become the thermal spraying layer bite into the first ceramic member, and the first ceramic member and the second ceramic This is because the member can be more firmly adhered.

In the method for producing the diffusing member of the present invention, the ceramic member formed around the metal member may be cut or polished as necessary. The shape of the diffusion member can be adjusted by cutting the ceramic member formed around the metal member. Moreover, by polishing the ceramic member formed around the metal member, the surface roughness (Rzjis) of the ceramic member can be adjusted.

In the method described above, it is difficult to form a gap between the metal member and the ceramic member constituting the diffusing member of the present invention.
When manufacturing a diffusion member in which a gap exists between a metal member and a ceramic member, by producing the ceramic member in a shape such that there is no gap for a structure having a size larger than that of the assumed metal member. A gap can be provided between the metal member and the metal member.

The diffusion member of the present invention can be manufactured by the above procedure.

The exhaust gas purification apparatus of the present invention will be described.
The exhaust gas purification apparatus of the present invention includes an exhaust pipe through which exhaust gas containing nitrogen oxides flows, a urea injection apparatus that is provided upstream of the exhaust pipe and injects urea into the exhaust pipe, and a downstream side of the exhaust pipe. An exhaust gas purifying device comprising a provided catalyst carrier, wherein one or more diffusion members of the present invention are arranged at a site where exhaust gas contacts downstream of the urea injector and upstream of the catalyst carrier. The diffusion member is welded to the exhaust pipe at a portion where the metal member is exposed.

In the exhaust gas purifying apparatus of the present invention, the diffusion member of the present invention having excellent heat resistance is provided on the downstream side of the urea injection apparatus and on the upstream side of the catalyst carrier, so that the urea injected from the urea injection apparatus Can be sufficiently mixed with exhaust gas containing nitrogen oxides. Furthermore, since the diffusion member of the present invention is composed of a ceramic member and a metal member, and the volume of the ceramic member is larger than the volume of the metal member, the temperature reduction of the exhaust gas is suppressed as compared with a diffusion member made of only metal. Can do. Furthermore, since the diffusion member of the present invention covers the periphery of the metal member so that a part of the metal member is exposed, by welding the exposed portion of the metal member with the inside of the exhaust pipe, It becomes easy to arrange the diffusion member in the exhaust pipe. And since the ceramic member has covered the surface except the location where the metal member mentioned above is exposed, it is hard to receive the corrosion by the by-product of urea water.

In the exhaust gas purifying apparatus of the present invention, the diffusion member is fixed in the exhaust pipe by welding a portion of the metal member constituting the diffusion member exposed to the outermost surface to the exhaust pipe.
As a method for welding the metal member constituting the diffusing member and the exhaust pipe, a conventionally known welding method can be suitably used. For example, arc welding, laser welding, resistance welding, brazing, or the like can be used.

In addition, conventionally well-known things can be used suitably about the exhaust pipe, urea injection apparatus, and catalyst carrier which comprise the exhaust gas purification apparatus of this invention.

In the exhaust gas purifying apparatus of the present invention, it is preferable that a ceramic coat layer covering the welded portion is formed at a welded portion between the portion where the metal member is exposed and the exhaust pipe.
When the ceramic coat layer which covers a welding part is formed in the welding part of the part which a metal member exposes, and an exhaust pipe, it can suppress that a welding part receives the corrosion by the by-product of urea water.

In the exhaust gas purifying apparatus of the present invention, when there is a portion where the metal member is exposed to the diffusion member fixed inside the exhaust pipe, a ceramic coat layer is also formed at the portion so that the metal member is not exposed. It is more preferable.
When the ceramic coat layer is formed at a location where the metal member of the diffusion member fixed inside the exhaust pipe is exposed, the metal member constituting the diffusion member is not substantially in contact with the exhaust gas. Corrosion of the diffusion member due to can be suppressed.

In the exhaust gas purifying apparatus of the present invention, the ceramic coat layer covering the welded portion can be formed by applying a ceramic coat raw material to be a raw material of the ceramic coat layer to the welded portion and heating.
As the ceramic coat raw material, the same material as the raw material of the ceramic member constituting the diffusion member of the present invention can be suitably used, and more preferably comprises an amorphous inorganic material and a crystalline inorganic material.

The function of the diffusing member of the present invention will be further described in detail.
FIG. 4A is a schematic view schematically showing the exhaust gas purification apparatus of the present invention, and FIG. 4B is an enlarged view of a broken line region H in FIG. 4A.
As shown in FIG. 4A, the exhaust gas purification apparatus 1 includes an exhaust pipe 100 through which exhaust gas flows, a urea injection apparatus 500 that is provided upstream of the exhaust pipe 100 and injects urea into the exhaust pipe 100, The diffusion member 10 includes a catalyst carrier 400 provided on the downstream side of the exhaust pipe 100, and the diffusion member 10 is disposed at a portion where the exhaust gas contacts with the downstream side of the urea injection device 500 and the upstream side of the catalyst carrier 400.
When the diffusing member 10 is installed in the exhaust pipe 100, the exhaust gas flowing in from the upstream of the exhaust pipe is partially blocked when passing through the diffusing member 10, and the exhaust gas is mixed (flow of exhaust gas). Is schematically shown by arrow G).
Accordingly, since the exhaust gas that has passed through the diffusion member 10 flows into the casing 200 while turning, when the exhaust gas reaches the exhaust gas inflow side end surface 400a of the catalyst carrier 400 disposed inside the casing 200 by the holding sealing material 300, This reduces the bias of the components in the exhaust gas and / or the bias of the temperature distribution.
Since the urea water injected from the urea water injection device 500 reaches the catalyst carrier 400 in a sufficiently dispersed state in the exhaust gas, the urea SCR system can be sufficiently operated. And since the volume of the ceramic member in the diffusion member 10 is larger than the volume of a metal member, the heat | fever of waste gas cannot be easily transmitted to a diffusion member, and can suppress the fall of waste gas temperature.
Further, as shown in FIG. 4B, the metal member 11 constituting the diffusing member 10 is welded to the exhaust pipe 100 to form a welded portion 600. Further, a ceramic coat layer 700 is provided on the surface of the welded portion 600 and the metal member 11.

For the reasons described above, the diffusion member of the present invention includes an exhaust pipe through which exhaust gas containing nitrogen oxides flows, a urea injection device that is provided upstream of the exhaust pipe and injects urea into the exhaust pipe, and the exhaust pipe. Of the exhaust gas purification device comprising a catalyst carrier provided on the downstream side of the exhaust gas from the upstream side of the exhaust pipe at a site where the exhaust gas contacts downstream of the urea injection device and upstream of the catalyst carrier. Suppresses the temperature of the exhaust gas when partially blocking the flow of the exhaust gas and reducing the deviation of components contained in the exhaust gas by thoroughly mixing the urea injected from the urea injection device with the exhaust gas In addition, it can be suitably used for preventing the diffusion member from being corroded by urea and / or decomposition products of urea injected from the urea injection device.

In addition, as a catalyst carrier used for the exhaust gas purification apparatus, a catalyst carrier conventionally used in this field such as a ceramic honeycomb catalyst can be used.

Even in an exhaust pipe that does not include a urea water injection device, the diffusion member is effective in order to reduce the components and / or temperature deviation in the exhaust gas.

Below, it enumerates about the effect of the diffusion member of this invention.
(1) The diffusion member of the present invention is composed of a ceramic member and a metal member, and the volume of the ceramic member is larger than the volume of the metal member. be able to.

(2) Since the diffusion member of the present invention covers the periphery of the metal member so that a part of the metal member is exposed, the exposed portion of the metal member is welded to the inside of the exhaust pipe. It becomes easy to dispose the diffusion member in the exhaust pipe.

(3) In the diffusion member of the present invention, the ceramic member covers the surface except for the portion where the above-described metal member is exposed.

(4) By combining a plurality of diffusion members of the present invention and disposing them in the exhaust pipe, it becomes easy to optimize the effect of the diffusion members for each shape of the exhaust pipe to be installed. Therefore, it is not necessary to prepare a new mold or the like for each exhaust gas purifying apparatus having a different configuration, and the manufacturing cost can be suppressed.

(5) The exhaust gas purifying apparatus of the present invention comprises a ceramic member and a metal member, and the volume of the ceramic member includes a diffusion member that is larger than the volume of the metal member, so that the diffusion member absorbs the thermal energy of the exhaust gas. It is difficult to suppress the temperature reduction of the exhaust gas.

(6) As described above, the diffusion member of the present invention can sufficiently reduce the bias of components contained in the exhaust gas by sufficiently mixing urea injected from the urea injection device with the exhaust gas containing nitrogen oxides. In addition, since it is possible to suppress a decrease in the temperature of the exhaust gas, an exhaust pipe through which the exhaust gas containing nitrogen oxide flows, and a urea injection device that is provided upstream of the exhaust pipe and injects urea into the exhaust pipe And a catalyst carrier provided on the downstream side of the exhaust pipe can be suitably used for a portion where the exhaust gas contacts downstream of the urea injection device of the exhaust gas purification device and upstream of the catalyst carrier. .

DESCRIPTION OF SYMBOLS 1 Exhaust gas purification apparatus 10, 20 Diffusion member 11, 21 Metal member 12, 22 Ceramic member 23 Crevice 100 Exhaust pipe 200 Casing 300 Holding sealing material 400 Catalyst carrier 500 Urea water injection device 600 Welding part 700 Ceramic coat layer

Claims (13)

A diffusion member that is installed in the exhaust pipe and partially blocks the flow of exhaust gas flowing from the upstream of the exhaust pipe,
The diffusion member comprises a ceramic member and a metal member,
The metal member is a rod-shaped body,
The ceramic member covers the periphery of the metal member such that both ends of the rod-shaped body are exposed;
The volume of the ceramic member which comprises the said diffusion member is larger than the volume of the said metal member, The diffusion member characterized by the above-mentioned. The diffusion member according to claim 1, wherein an exposed area of the ceramic member is larger than an exposed area of the metal member on the outermost surface of the diffusion member. The diffusion member according to claim 1, wherein pores are formed in the ceramic member. The diffusion member according to claim 3, wherein the ceramic member has a porosity of 5 to 60%. The diffusion member according to claim 3 or 4, wherein the ceramic member has no continuous air hole. The diffusion member according to claim 3, wherein the pores formed in the ceramic member are closed pores. The diffusion member according to claim 1, wherein a gap exists between the metal member and the ceramic member. The diffusion member according to claim 1, wherein the ceramic member is made of a crystalline inorganic material and / or an amorphous inorganic material. The diffusion member according to claim 8, wherein the crystalline inorganic material is at least one selected from the group consisting of alumina, silica, zirconia, zircon, yttria, calcia, magnesia, ceria, and hafnia. The diffusion member according to claim 8 or 9, wherein the crystalline inorganic material is at least one selected from the group consisting of zirconia and zircon. An exhaust pipe through which exhaust gas containing nitrogen oxides flows;
A urea injection device that is provided upstream of the exhaust pipe and injects urea into the exhaust pipe;
An exhaust gas purification apparatus comprising a catalyst carrier provided on the downstream side of the exhaust pipe,
One or more diffusion members according to any one of claims 1 to 10 are arranged at a site where exhaust gas contacts downstream of the urea injection device and upstream of the catalyst carrier,
The exhaust gas purifier according to claim 1, wherein the diffusion member is welded to the exhaust pipe at a portion where the metal member is exposed. The exhaust gas purifying apparatus according to claim 11, wherein a ceramic coat layer covering the welded portion is formed at a welded portion between the portion where the metal member is exposed and the exhaust pipe. An exhaust pipe through which exhaust gas containing nitrogen oxides circulates, a urea injector provided upstream of the exhaust pipe and injecting urea into the exhaust pipe, and a catalyst carrier provided downstream of the exhaust pipe In the exhaust gas purifying device, at the site where the exhaust gas contacts on the downstream side of the urea injection device and on the upstream side of the catalyst carrier,
When partially reducing the flow of the exhaust gas flowing in from the upstream of the exhaust pipe and reducing the bias of the components contained in the exhaust gas by sufficiently mixing the urea injected from the urea injection device with the exhaust gas, 11. The method according to claim 1, wherein the temperature drop is suppressed and the diffusion member is prevented from being corroded by urea and / or a decomposition product of the urea injected from the urea injection device. Use of diffusion members.

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