JP2016211434A - Exhaust system component and exhaust emission control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust system component that can prevent deposition of precipitated urea at the surface thereof when it is installed in a part that comes into contact with an exhaust gas containing a nitrogen oxide in an urea SCR system.SOLUTION: The exhaust system component is installed in the part that comes into contact with an exhaust gas containing a nitrogen oxide. In the exhaust system component, a surface on a side coming into contact with the exhaust gas is formed by a carbide layer that is formed on a substrate made of a metal.SELECTED DRAWING: Figure 1

Description

The present invention relates to an exhaust system component and an exhaust gas purification device.

NOx (nitrogen oxide) is contained in exhaust gas discharged from internal combustion engines such as diesel engines used in transportation equipment such as automobiles and ships, and exhaust gas discharged from cement plants.
In recent years, a technique called a urea SCR (Selective Catalytic Reaction) system has been studied as a method for purifying nitrogen oxides in exhaust gas.
In the urea SCR system, urea water is sprayed into an exhaust passage through which exhaust gas containing nitrogen oxide flows in an exhaust gas purification device, ammonia is generated by thermal decomposition of urea, and nitrogen oxide reduction reaction is performed by ammonia. .

A urea water injection device for injecting urea water is provided in the exhaust passage of the exhaust gas purification device, and a catalyst carrier is provided on the downstream side of the urea water injection device (for example, Patent Document 1).
The catalyst carrier has a catalytic action that promotes a reduction reaction of nitrogen oxides, and a honeycomb shape having a large number of through holes for exhaust gas to flow is often adopted.

In addition, an exhaust gas purification device in which a NOx occlusion reduction catalyst is provided in the middle of an exhaust pipe in order to purify NOx in exhaust gas is also known (Patent Document 2).
In Patent Document 2, in order to prevent fuel (light oil) injected as a reducing agent from adhering to the exhaust pipe and getting wet only when the exhaust pipe is wet, it is downstream from the nozzle tip of the fuel injector. It is described that a ceramic coating as a heat insulating structure is applied to a predetermined range of the exhaust pipe.

Further, Patent Document 3 discloses that a mixer or swirler is provided in the exhaust passage so as to generate a swirling flow in the exhaust gas in order to sufficiently mix ammonia as a reducing agent and exhaust gas in the urea SCR system. Yes.

Special table 2011-523585 gazette JP-A-2005-76460 JP 2008-280882 PR

In the exhaust gas purifying apparatus in which the catalyst carrier is provided on the downstream side of the urea water injection device as described in Patent Document 1, when urea water is injected into the exhaust passage, the urea water adheres to the surface of the exhaust passage. In some cases, the attached urea water is cooled and urea is deposited, and is deposited on the surface of the exhaust passage.
If urea is deposited and deposited on the surface of the exhaust passage, the flow of exhaust gas is hindered, pressure loss increases, and the purification efficiency of nitrogen oxides may decrease.
Further, when urea is deposited and deposited on the surface of the exhaust passage, urea in the injected urea water is not converted to ammonia, so that the amount of ammonia contributing to the reduction of nitrogen oxides is insufficient. There is a possibility that the purification efficiency is lowered. If the nitrogen oxide purification efficiency is low, the sensor that monitors the nitrogen oxide concentration at the catalyst carrier outlet performs feedback control to further increase the injection amount of urea water. The amount of precipitation increases, and as a result, the flow of exhaust gas may be further inhibited and the purification rate of nitrogen oxides may be reduced.

The ceramic coating technique described in Patent Document 2 is not a technique intended for use in a urea SCR system, but heat insulation for maintaining the temperature of the exhaust pipe surface at 180 to 350 ° C. or higher, which is the boiling point of light oil. It is a coating technology. With this technique, the assumed temperature for maintaining the temperature of the exhaust pipe surface is considerably higher than 133 to 135 ° C., which is the melting point of urea, and the purpose of the heat insulating coating is different. Further, Patent Document 2 does not disclose what kind of coating is specifically applied in order to maintain the temperature of the exhaust pipe surface at such a high assumed temperature.

The mixer and swirler described in Patent Document 3 are members that generate a swirling flow in the exhaust gas by partially inhibiting the flow of the exhaust gas, and the exhaust gas flow path is narrow. Therefore, if urea is deposited and deposited on the surfaces of these members, the exhaust gas flow path becomes narrower, which may increase pressure loss or clog the exhaust gas. Moreover, if urea is deposited on the surfaces of these members, the purification efficiency of nitrogen oxides may be reduced.

The present invention has been made in view of the above-described problems. When the urea SCR system is provided at a site in contact with exhaust gas containing nitrogen oxides, urea deposited on the surface thereof is deposited. It is an object of the present invention to provide an exhaust system component capable of preventing the exhaust gas and an exhaust gas purification apparatus including the exhaust system component.

In order to achieve the above object, the exhaust system component of the present invention is
An exhaust system component provided at a site that comes into contact with exhaust gas containing nitrogen oxides,
The surface on the side in contact with the exhaust gas is characterized by comprising a carbide layer formed on a metal substrate.

In the exhaust system component of the present invention, the surface on the side in contact with the exhaust gas is composed of a carbide layer.
It can be said that the carbide layer is a layer made of a separated urea water material which is a material to which urea water does not easily adhere. Therefore, even if the exhaust gas containing urea water comes into contact with the carbide layer made of the separated urea water material, the urea water can be separated from the carbide layer and flow downstream along the flow of the exhaust gas.
The urea water on the exhaust gas flow again flows toward the catalyst carrier and is supplied as an ammonia source.
That is, when the exhaust system component of the present invention is provided in a portion that comes into contact with the exhaust gas containing nitrogen oxides in the urea SCR system, urea can be prevented from being deposited on the surface of the exhaust system component.
Note that the carbide layer may include pinholes that may occur in manufacturing.

Since the carbide layer has few OH groups (hydroxyl groups) on the surface, the bonding strength between urea water and the carbide layer via the OH group is small. Therefore, it is considered that the urea water is easily separated from the surface of the carbide layer due to the pressure of the exhaust gas.
In addition, it is normal that there exists a metal oxide layer on the surface of the base material which consists of metals, and it is thought that it is in the state which is easy to have OH group. And since OH group is easy to couple | bond with urea water, compared with a carbide | carbonized_material layer, urea water becomes easy to couple | bond with the surface of the base material which consists of metals.
Further, by forming a carbide layer so as to block OH groups on the surface of the base material made of metal, the number of OH groups on the surface of the base material made of metal that can be bonded with urea water is reduced. This also prevents urea water from adhering to the surface of the exhaust system parts.

The exhaust system component of the present invention comprises the above base material,
A ceramic coating layer formed on the surface of the substrate on the side in contact with the exhaust gas;
It is preferable to consist of a carbide layer formed on the ceramic coat layer.
Since the ceramic coat layer is a preferable heat insulating coating by being provided on a base material made of metal, the temperature of the exhaust system component surface is not easily lowered, and precipitation of urea is effectively prevented.
In addition, when a ceramic coat layer is present, the adhesion between the ceramic coat layer and the metal substrate is increased, and the adhesion between the ceramic coat layer and the carbide layer is increased, thereby forming a carbide layer that is difficult to peel off. can do.
This is because a part of each component can diffuse into each layer at the interface between the ceramic coat layer and the carbide layer.
That is, through the ceramic coat layer, the adhesion between the metal substrate and the carbide layer can be improved.
In addition, since the ceramic coat layer becomes a glue material, the adhesion between the metal substrate and the carbide layer can be improved.

In the exhaust system component of the present invention, the ceramic coat layer preferably contains an amorphous inorganic material and a crystalline inorganic material.
Since the ceramic coating layer containing the amorphous inorganic material and the crystalline inorganic material becomes a more preferable heat insulating coating by being provided on the base made of metal, the temperature of the exhaust system component surface is less likely to be lowered, and urea Is more effectively prevented.

In the exhaust system component of the present invention, the amorphous inorganic material is preferably a low-melting glass having a softening point of 300 to 1000 ° C.
When the amorphous inorganic material is the low-melting glass, the amorphous inorganic material is softened and melted by heating at a temperature exceeding the softening point and spreads on the surface of the base material to form a ceramic coat layer.

In the exhaust system component of the present invention, it is preferable that pores are formed in the ceramic coat layer.
If pores are formed in the ceramic coat layer, the heat insulating performance of the ceramic coat layer is further increased, and therefore the temperature of the exhaust system component surface is further less likely to be lowered, and urea precipitation is further effectively prevented.

The exhaust system component of the present invention comprises the above base material,
It is preferable to consist of the carbide layer provided by carrying out the surface treatment of the said base material.
The carbide layer provided by surface-treating the base material made of metal also functions as a urea separation water material, and can prevent urea water adhesion and urea deposition.

In the exhaust system component of the present invention, the carbide layer is preferably made of carbon or tungsten carbide.
Carbon or tungsten carbide is a material suitable for preventing urea water from adhering to the surface. Moreover, since heat resistance is also high, it is suitable as a material provided in the surface by which high temperature exhaust gas distribute | circulates.

The exhaust system component of the present invention is preferably a cylindrical member used as an exhaust passage through which exhaust gas containing nitrogen oxides flows.
When the exhaust system component of the present invention is used as an exhaust passage, urea is prevented from accumulating on the surface of the exhaust passage.

The exhaust system component of the present invention is preferably a diffusion member that is installed inside an exhaust passage through which exhaust gas containing nitrogen oxides flows, and partially obstructs the flow of exhaust gas flowing from the upstream of the exhaust passage.
When the exhaust system component of the present invention is used as a diffusion member, urea is prevented from being deposited on the surface of the diffusion member.

The exhaust gas purification apparatus of the present invention is
An exhaust passage through which exhaust gas containing nitrogen oxides flows;
A urea water injection device that is provided upstream of the exhaust passage and injects urea water into the exhaust passage;
An exhaust gas purification apparatus comprising a catalyst carrier provided on the downstream side of the exhaust passage,
The exhaust system component of the present invention is used in a portion where the exhaust gas contacts downstream of the urea water injection device and upstream of the catalyst carrier.

In the exhaust gas purification apparatus having the above configuration, the urea water injection device is provided upstream of the exhaust passage, and the exhaust gas purification device is provided downstream of the exhaust passage.
The exhaust system component of the present invention is used at a site where the exhaust gas contacts with the downstream side of the urea water injector and the upstream side of the catalyst carrier.
With such a configuration, even if the exhaust gas containing urea water injected from the urea water injection device into the exhaust passage comes into contact with the carbide layer in the region between the urea water injection device and the catalyst carrier, the urea water is a carbide. Apart from the bed, it can flow downstream with the exhaust gas flow.
Therefore, urea is prevented from depositing on the surface of the exhaust system part located between the urea water injection device and the catalyst carrier.

In the exhaust gas purification apparatus of the present invention, it is preferable to use the exhaust system parts of the present invention as the exhaust passage.
When the exhaust passage is composed of the exhaust system parts of the present invention, even if the urea water that contacts the surface of the exhaust passage contacts the carbide layer on the surface of the exhaust passage, the urea water leaves the carbide layer and rides on the flow of the exhaust gas. It can flow downstream.
Therefore, urea is prevented from being deposited on the surface of the exhaust passage located between the urea water injection device and the catalyst carrier.

In the exhaust gas purification apparatus of the present invention, it is preferable that the exhaust system component of the present invention is used as a diffusion member that is installed inside the exhaust passage and partially blocks the flow of exhaust gas flowing from the upstream of the exhaust passage.
When the diffusion member is composed of the exhaust system component of the present invention, even if the exhaust gas containing urea water contacts the carbide layer on the surface of the diffusion member, the urea water leaves the carbide layer and flows downstream on the exhaust gas flow. Can continue.
Therefore, urea is prevented from depositing on the surface of the diffusion member installed inside the exhaust passage.

FIG. 1 is a cross-sectional view schematically showing an example of an exhaust system component of the present invention. FIG. 2 is a cross-sectional view schematically showing another example of the exhaust system component of the present invention. FIG. 3 is a cross-sectional view schematically showing another example of the exhaust system component of the present invention. FIG. 4 is a perspective view schematically showing an example of an exhaust pipe which is an embodiment of the exhaust system component of the present invention. FIG. 5 is a perspective view schematically showing another example of an exhaust pipe which is an embodiment of the exhaust system component of the present invention. FIG. 6 is a cross-sectional view schematically showing an example of an exhaust gas purifying apparatus including an exhaust pipe as an exhaust system component of the present invention. FIG. 7 is a perspective view schematically showing an example of a diffusion member which is an embodiment of the exhaust system component of the present invention. FIG. 8 is a perspective view schematically showing an example of a diffusion member which is an embodiment of the exhaust system component of the present invention. FIG. 9 is a perspective view schematically showing an example of a diffusion member which is an embodiment of the exhaust system component of the present invention. FIG. 10 is a perspective view schematically showing an example of a diffusion member that is an embodiment of the exhaust system component of the present invention. FIG. 11 is a perspective view schematically showing an example of a diffusion member which is an embodiment of the exhaust system component of the present invention. FIG. 12 is a perspective view schematically showing an example of a diffusion member which is an embodiment of the exhaust system component of the present invention. FIG. 13 is a cross-sectional view schematically showing an example of an exhaust gas purifying apparatus provided with both a diffusion member and an exhaust pipe as an exhaust system component of the present invention. FIG. 14 (a) is a perspective view schematically showing an example of a flue that is an embodiment of the exhaust system component of the present invention, and FIG. 14 (b) is a cross-sectional view taken along line AA in FIG. 14 (a). FIG.

(Detailed description of the invention)
Hereinafter, the exhaust system parts and the exhaust gas purification apparatus of the present invention will be described in detail. However, the present invention is not limited to the following configurations, and can be applied with appropriate modifications without departing from the scope of the present invention. Note that the present invention also includes a combination of two or more desirable configurations of the present invention described below.

First, the exhaust system parts of the present invention will be described.
The exhaust system parts of the present invention are:
An exhaust system component provided at a site that comes into contact with exhaust gas containing nitrogen oxides,
The surface on the side in contact with the exhaust gas is characterized by comprising a carbide layer formed on a metal substrate.

The exhaust system component of the present invention is a component provided at a site that comes into contact with exhaust gas containing nitrogen oxides.
Sources of exhaust gas containing nitrogen oxides are not particularly limited, but examples of sources of exhaust gas containing nitrogen oxides include diesel engines and gasoline engines used in vehicles, ships, construction machinery, etc. Examples include factories such as internal combustion engines, cement plants, and power plants.

Even if the generation source of the exhaust gas is different, the configuration of the exhaust system component of the present invention is the same in that the surface on the side in contact with the exhaust gas is composed of a carbide layer, and thus constitutes the exhaust system component of the present invention. A configuration example of the carbide layer will be described with reference to the drawings.
At this time, a preferable configuration of the base material of the exhaust system component will also be described.

FIG. 1 is a cross-sectional view schematically showing an example of an exhaust system component of the present invention.
An exhaust system component 10 shown in FIG. 1 includes a base material 11 and a carbide layer 12 formed on the surface of the base material 11.
The exhaust system component 10 shown in FIG. 1 has a form in which the carbide layer 12 is formed directly on the surface of the base material 11 as a layer different from the base material 11.

The material of the base material is not particularly limited as long as it is a metal, and examples thereof include stainless steel, steel, iron, copper and the like, or nickel alloys such as Inconel, Hastelloy, and Invar.

Examples of the carbide layer include a layer made of carbide ceramic. Specific examples include SiC, WC, TiC, TaC, ZrC, VC, HfC, B ₄ C, Mo ₂ C, NbC, and Cr ₃ C ₂ . A layer made of carbon is also preferable.
Among these, a layer made of carbon or tungsten carbide (WC) is more preferable.

The carbide layer can be formed by performing treatment such as vapor deposition, sputtering, thermal spraying, and cold spraying on the base material. Vapor deposition is preferred when forming a carbide layer made of carbon, and thermal spraying is preferred when forming a carbide layer made of tungsten carbide.

When the carbide layer is formed directly on the surface of the substrate as a layer different from the substrate, the thickness is not particularly limited, but is preferably 0.01 to 50 μm.

FIG. 2 is a cross-sectional view schematically showing another example of the exhaust system component of the present invention.
The exhaust system component 20 shown in FIG. 2 includes a base material 11 and a carbide layer 13 provided by surface-treating the surface of the base material 11.

It is preferable to provide a carbide layer by carbonizing a metal substrate.
As the substrate, it is preferable to use a metal material suitable for carbonization. Examples thereof include metals such as stainless steel, steel, iron and copper, or nickel alloys such as Inconel, Hastelloy and Invar. Further, chrome molybdenum steel, nickel chrome molybdenum steel, and the like are also suitable for carbonization.
And it is more preferable that the carbide layer is a carbonized metal layer formed by carbonizing a metal constituting the substrate.
A carburizing process is mentioned as a method of carbonizing the base material which consists of metals. Specific examples of the carburizing process include solid carburizing, gas carburizing, liquid carburizing, vacuum carburizing (vacuum gas carburizing), and plasma carburizing (ion carburizing).
Solid carburization is a method in which charcoal is used as a carbon source, and carbon monoxide generated by sealing and simultaneously heating a metal to be carbonized together with carbon is used as a carbon source.
Liquid carburization is a method of carburizing with a salt bath in which an inorganic salt mainly composed of sodium cyanide is melted at a high temperature.
Gas carburizing is a method in which carburizing is performed with a gas mainly composed of carbon dioxide, hydrogen, methane, water vapor, and the like.
Vacuum carburizing (vacuum gas carburizing) is a method of performing carburizing by injecting a gas for gas carburizing and heating after evacuation.
Plasma carburization (ion carburization) is a method of performing carburization by applying a high voltage after evacuating and injecting gas for gas carburization and converting the gas into plasma by glow discharge.

When the carbide layer is formed by surface-treating the surface of the substrate, the thickness is not particularly limited, but is preferably 0.01 to 50 μm.

FIG. 3 is a cross-sectional view schematically showing another example of the exhaust system component of the present invention.
The exhaust system component 30 shown in FIG. 3 includes a base material 11, a ceramic coat layer 32 formed on the surface of the base material 11, and a carbide layer 35 formed on the ceramic coat layer 32.

As a base material, the material demonstrated as a base material which comprises the exhaust-system components shown in FIG. 1 can be used. Specifically, it is preferably a metal, and examples thereof include metals such as stainless steel, steel, iron, and copper, or nickel alloys such as Inconel, Hastelloy, and Invar.

The ceramic coat layer 32 illustrated in FIG. 3 includes an amorphous inorganic material 33 and a crystalline inorganic material 34, and pores 36 are formed in the ceramic coat layer 32. However, since the ceramic coat layer formed on the exhaust system component of the present invention is not limited to the above-described configuration, a preferred form of the ceramic coat layer formed on the exhaust system component of the present invention will be described below.

The ceramic coat layer formed on the exhaust system component of the present invention preferably contains an amorphous inorganic material, more preferably contains an amorphous inorganic material and a crystalline inorganic material, and is a layer of an amorphous inorganic material. And more preferably, particles of crystalline inorganic material dispersed in the amorphous inorganic material layer.

Moreover, it is preferable that pores are formed in the ceramic coat layer.
When pores are formed in the ceramic coat layer, the pores hinder internal heat conduction, and thus excellent heat insulating properties can be obtained.

The porosity can adjust the porosity and the average pore diameter by a pore former described later, and the ceramic coat layer preferably has a porosity of 10 to 80%.
When the porosity of the ceramic coat layer is 10 to 80% and these pores are well dispersed, the heat transfer in the ceramic coat layer can be effectively blocked by the pores, and good heat insulation is achieved. Can be maintained.
The porosity of the ceramic coat layer is calculated by calculating the bulk density from the thickness of the ceramic coat layer and the thickness of the ceramic coat layer measured with a film thickness meter (dual scope), and calculating the ratio of the true density calculated by the pycnometer. Then, the value obtained by subtracting the value from 1 can be calculated as the porosity.

When the porosity of the ceramic coat layer is less than 10%, the heat insulating property may be deteriorated because the ratio of the pores is too small. On the other hand, when the porosity of the ceramic coat layer exceeds 80%, the ratio of the pores is excessively increased, so that the mechanical strength is lowered and the heat insulation performance is lowered due to coalescence of the pores.

Below, the amorphous inorganic material which comprises a ceramic coat layer is demonstrated.

The amorphous inorganic material is preferably an amorphous inorganic material containing silica, more preferably 35% by weight or more of silica, and a low melting glass having a softening point of 300 to 1000 ° C. More preferably.
The kind of the low melting 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 glass And soda barium glass.
These glasses may be used alone or in combination of two or more.

When the softening point of the amorphous inorganic material is in the range of 300 to 1000 ° C., the low melting point glass is melted and coated (coated) on the surface of the base material (metal material), and then heated and fired. It is possible to easily form a ceramic coat layer on the surface of a substrate made of metal and to form a ceramic coat layer excellent in adhesion to the substrate.

If the softening point of the low-melting glass is less than 300 ° C., the temperature of the softening point is too low, so that during the heat treatment, the layer that becomes the ceramic coat layer easily flows due to melting, etc. It becomes difficult to form. On the other hand, when the softening point of the low-melting glass 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 properties of the substrate may be deteriorated by heating.
The softening point can be measured using a glass automatic softening point / strain point measuring device (SSPM-31) manufactured by Opt Corporation, for example, based on the method defined in JIS R 3103-1: 2001. it can.

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-described low-melting glass, or may be composed of a plurality of kinds of low-melting glass.

Subsequently, the crystalline inorganic material will be described.

When the crystalline inorganic material is present in the ceramic coat layer, when the ceramic coat layer becomes high temperature, the crystalline inorganic material particles obstruct the movement of the pores and prevent the movement of the pores. It can prevent that heat insulation performance falls by coalescence of a pore.

The crystalline inorganic material preferably contains zirconia, more preferably contains 20% by weight or more of zirconia, and more preferably contains 50% by weight or more of zirconia.
Specific examples of the crystalline inorganic material containing zirconia include CaO-stabilized zirconia (5 wt% CaO—ZrO ₂ , 8 wt% CaO—ZrO ₂ , 31 wt% CaO—ZrO ₂ ), MgO stabilized zirconia (20 wt%). MgO—ZrO ₂ , 24 wt% MgO—ZrO ₂ ), Y ₂ O ₃ 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 , 10wt% Y 2 O 3 -ZrO} 2, 12wt% Y 2 O 3 -ZrO 2, 20wt% Y 2 O 3 -ZrO 2), zircon _{(ZrO 2 -33wt% SiO 2)} , include CeO stabilized zirconia It is done.
Among these, zirconia, Y ₂ O ₃ -stabilized zirconia, CaO-stabilized zirconia, and MgO-stabilized zirconia having excellent heat resistance and corrosion resistance and a thermal conductivity at 25 ° C. of 4 W / mK or less are preferable.

The crystalline inorganic material preferably has a softening point higher than the softening point of the amorphous inorganic material already described. Specifically, the crystalline inorganic material has a softening point of 950 ° C. or higher. It is preferable.

In addition, the crystalline inorganic material particles mechanically strengthen the ceramic coat layer and have excellent heat resistance, so the ceramic coat layer has excellent heat resistance, and cracks and the like are generated due to deterioration of mechanical strength. Can be prevented.

The thickness of the ceramic coat layer is preferably 5 to 2000 μm, and more preferably 50 to 2000 μm.
When the thickness of the ceramic coat layer is less than 5 μm, the thickness of the ceramic coat layer is too thin, so that sufficient heat insulation performance cannot be exhibited when used as an exhaust system component. On the other hand, if the thickness of the ceramic coat layer exceeds 2000 μm, the ceramic coat layer is too thick, so that when subjected to thermal shock, the bonding surface with the base material of the ceramic coat layer and the surface exposed to the atmosphere The temperature difference is likely to be large, and the ceramic coat layer is easily broken.

The thermal conductivity of the ceramic coat layer at 25 ° C. is preferably 0.05 to 2 W / mK.
When the thermal conductivity of the ceramic coat layer at 25 ° C. is 0.05 to 2 W / mK, the exhaust system parts of the present invention have excellent heat insulation properties, and the thermal conductivity is difficult to increase even at high temperatures. It is possible to prevent the temperature of gas or the like from decreasing.
Realizing a ceramic coat layer having a thermal conductivity at 25 ° C. of less than 0.05 W / mK of the ceramic coat layer is not easy considering the balance between both technical and economic viewpoints. On the other hand, if the thermal conductivity at 25 ° C. of the ceramic coat layer exceeds 2 W / mK, the heat retention in the low temperature region becomes insufficient, and for example, when used in a urea SCR system, the temperature of the exhaust gas decreases. The reduction of NOx may not proceed sufficiently.
The thermal conductivity of the ceramic coat layer at 25 ° C. can be measured by a laser flash method.

The thermal conductivity of the ceramic coat layer is measured by the laser flash method by measuring the thermal diffusion coefficient (α). The thermal conductivity (k) is a value calculated from the measured thermal diffusion coefficient (α), specific heat capacity (Cp), and density (ρ).
The thermal diffusion coefficient can be measured under the following conditions.
Measuring device: LFA467 made by NETZSCH
Surface treatment: Graphite spray Measurement temperature: 25 ° C
Measurement atmosphere: N ₂
Sample size: φ10mm, thickness = 2mm
When measuring the thermal diffusion coefficient of the ceramic coat layer, it is measured in a state integrated with the substrate, and the thermal diffusion coefficient of only the ceramic coat layer is calculated by multilayer analysis. Further, when measuring the thermal diffusion coefficient of the ceramic coat layer, the sample is set so that the laser is irradiated perpendicularly to the ceramic coat layer.

The thermal conductivity is calculated from the following formula.
k = ρ · Cp · α [W / mK]
<Measurement of bulk density (ρ)>
When determining the bulk density of the ceramic coat layer, first measure the weight of the substrate, then form a ceramic coat layer on the substrate and then subtract the ceramic coat layer from the measurement of the weight of the substrate with the ceramic coat layer. The weight of (= A) is measured. Thereafter, the volume (= B) of the ceramic coat layer is calculated from the film thickness of the ceramic coat layer, and A / B is defined as the bulk density.
<Measurement of specific heat capacity (Cp)>
The specific heat capacity can be measured under the following conditions.
Measuring device: Seiko Denshi Kogyo DSC210 type Measuring temperature: 25 ° C
Measurement method: DSC method Measurement atmosphere: Ar
When measuring the specific heat capacity of the ceramic coat layer, the ceramic coat layer can be formed into a bulk body having a diameter of 4 mm and a thickness of 1 mm.

As the carbide layer 35, the material described as the carbide layer 12 constituting the exhaust system component 10 shown in FIG. 1 can be used.
Examples of the carbide layer include a layer made of carbide ceramic. Specific examples include SiC, WC, TiC, TaC, ZrC, VC, HfC, B ₄ C, Mo ₂ C, NbC, and Cr ₃ C ₂ . A layer made of carbon is also preferable.
Among these, a layer made of carbon or tungsten carbide (WC) is more preferable.

The carbide layer made of these materials can be formed by performing a process such as vapor deposition, sputtering, spraying, etc. on the ceramic coat layer.
Also, a slurry prepared by mixing an amorphous inorganic material and a material to be a carbide layer (carbide ceramic) is prepared, and the slurry is applied on the ceramic coat layer, followed by drying and firing. A carbide layer can be formed thereon.

When the carbide layer is formed on the ceramic coat layer, the thickness is not particularly limited, but is preferably 0.01 to 50 μm.

A preferable aspect of the base material that can constitute the exhaust system component of the present invention is common to all of the exhaust system components shown in FIGS. 1, 2, and 3, and will be described below.
In order to improve the adhesion to the carbide layer or the ceramic coat layer, the surface of the substrate may be subjected to a roughening treatment such as sand blasting or chemicals.

Surface roughness _{Rz JIS} of the roughened surface of the substrate to be formed by the roughening treatment, 1.5～20Myuemu is desirable. The surface roughness Rz _JIS of the roughened surface described above is a ten-point average roughness defined by JIS B 0601 (2001).
In particular, when the ceramic coat layer is provided on the surface of the substrate, the surface roughness is preferable.
When the surface roughness Rz _{JIS of the} roughened surface of the base material of the exhaust system component is less than 1.5 μm, the surface area of the base material becomes small, and it becomes difficult to obtain sufficient adhesion between the base material and the ceramic coat layer. . On the other hand, when the surface roughness Rz _{JIS of the} roughened surface of the base material of the exhaust system component exceeds 20 μm, there is a problem that the base material is deformed. In particular, the deformation of the base material increases as the roughened area increases.
In addition, the surface roughness Rz _JIS of the roughened surface of the base material of the exhaust system component can be measured according to JIS B 0601 (2001) using Handy Surf E-35B manufactured by Tokyo Seimitsu Co., Ltd. . The measuring distance is 4 mm.

The shape of the base material is not particularly limited, and the shape of the outer edge of the cross section other than a flat plate, a semi-cylinder, and a cylindrical shape can be any shape such as an ellipse or a polygon.
When used as an exhaust passage to be described later, a tubular shape is preferable.
When the base material of the exhaust system part is cylindrical, the diameter of the base material may not be constant along the longitudinal direction, and the cross-sectional shape perpendicular to the length direction may not be constant along the longitudinal direction. Also good.
Moreover, when using as a diffusion member, it is preferable that it is a shape which can inhibit the flow of exhaust gas partially.

In the exhaust system part of the present invention, the desirable lower limit of the thickness of the substrate is 0.2 mm, the more desirable lower limit is 0.4 mm, the desirable upper limit is 10 mm, and the more desirable upper limit is 4 mm.
When the thickness of the base material of the exhaust system component is less than 0.2 mm, the strength of the exhaust system component is insufficient. In addition, if the thickness of the base material of the exhaust system component exceeds 10 mm, the weight of the exhaust system component increases, and it becomes difficult to mount the exhaust system component on a vehicle such as an automobile, for example.
However, in the case of an exhaust system part used in a flue of a factory such as a cement plant, the base material may be thicker.

The carbide layer constituting the exhaust system component is formed on the surface on the side in contact with the exhaust gas. The surface on the side in contact with the exhaust gas is determined by the portion where the exhaust system parts are arranged, but usually is naturally determined from the shape of the exhaust system parts.
When the exhaust system component is a cylindrical member used as an exhaust passage, the inner peripheral surface through which the exhaust gas flows is the surface on the side in contact with the exhaust gas.
When the exhaust system component is used as a diffusion member, the surface corresponding to the portion where the exhaust gas collides and contacts is the surface on the side in contact with the exhaust gas.

Examples of exhaust system parts of the present invention include an exhaust passage through which exhaust gas containing nitrogen oxides flows. Specific examples of the exhaust passage include diesel engines, gasoline engines, etc. used in vehicles, ships, construction machinery, etc. An example of an exhaust pipe through which exhaust gas discharged from the internal combustion engine flows and an exhaust gas purification apparatus including the exhaust pipe will be described.

FIG. 4 is a perspective view schematically showing an example of an exhaust pipe which is an embodiment of the exhaust system component of the present invention.
The exhaust pipe 50 shown in FIG. 4 is a cylindrical tubular member, and the inner peripheral surface of the cylindrical base material 11 is composed of the carbide layer 12, so the carbide layer 12 is formed on the surface on the side where the exhaust gas flows. It can be said that.
Since the carbide layer 12 is a layer made of a separated urea water material that is a material to which urea water does not easily adhere, even if an exhaust gas containing urea water comes into contact with the carbide layer made of the separated urea water material, the urea water is a carbide layer. It is possible to flow downstream by riding on the flow of exhaust gas.

FIG. 5 is a perspective view schematically showing another example of an exhaust pipe which is an embodiment of the exhaust system component of the present invention.
The exhaust pipe 60 shown in FIG. 5 is a cone-shaped cylindrical member, and is the same as the exhaust pipe 50 shown in FIG. 4 except that its diameter decreases from the first end face 61 toward the other end face 62. It is a cylindrical member.
Also in this exhaust pipe 60, since the carbide layer 12 is formed on the inner peripheral surface of the substrate 11, it can be said that the carbide layer 12 is formed on the surface on the side where the exhaust gas contacts.
And since the carbide layer 12 is a layer made of a separated urea water material which is a material to which urea water does not easily adhere, even if the exhaust gas containing urea water comes into contact with the carbide layer made of the separated urea water material, the urea water is Apart from the carbide layer, it can flow downstream with the exhaust gas flow.

Subsequently, an exhaust gas purification apparatus of the present invention using an exhaust pipe as an embodiment of the exhaust system component of the present invention as an exhaust passage will be described.
FIG. 6 is a cross-sectional view schematically showing an example of an exhaust gas purifying apparatus including an exhaust pipe as an exhaust system component of the present invention.
In the exhaust gas purification apparatus 100, a holding sealing material 300 is wound around the catalyst carrier 400 and disposed in the exhaust pipe.
The exhaust pipe 50a, the cone-shaped exhaust pipe 60, and the cylindrical exhaust pipe 50b are combined into a cross-sectional shape as shown in FIG. 6, and the inner diameter of the exhaust pipe 50b is that of the exhaust pipe 50a. It is larger than the inner diameter.

In FIG. 6, the flow of the exhaust gas is indicated by an arrow G, and in FIG. 6, the left side corresponds to the upstream side of the exhaust pipe, and the right side corresponds to the downstream side.
A urea water injection device 500 is provided on the upstream side of the exhaust pipe, and the exhaust pipe located downstream of the urea water injection device 500 and upstream of the catalyst carrier 400 is the exhaust system of the present invention. It is an exhaust pipe as a part. That is, in the exhaust pipe 50a, the exhaust pipe 60, and the exhaust pipe 50b, which are located downstream of the urea water injection device 500 and upstream of the catalyst carrier 400, the carbide layer 12 is provided at a site where exhaust gas contacts. Yes.

The urea water injected from the urea water injection device 500 becomes exhaust gas containing urea water and flows through the exhaust pipes (50a, 60, 50b). The exhaust gas containing urea water comes into contact with the carbide layer 12 formed in the exhaust pipe (50a, 60, 50b) in the region between the urea water injection device 500 and the catalyst carrier 400. Since the carbide layer 12 is a layer made of a separated urea water material that is a material to which urea water does not easily adhere, even if an exhaust gas containing urea water comes into contact with the carbide layer made of the separated urea water material, the urea water is a carbide layer. It is possible to flow downstream by riding on the flow of exhaust gas.
Furthermore, when the ceramic coat layer (see Fig. 3) is formed on the exhaust pipe (50a, 60, 50b) and the carbide layer is formed on the ceramic coat layer (50a, 60, 50b), the heat insulation performance is excellent and the exhaust gas temperature drop is suppressed. It is possible to prevent urea from being deposited on the surface of the exhaust system component.
Since urea is prevented from accumulating on the surface of the exhaust pipe (50a, 60, 50b) in the region between the urea water injection device 500 and the catalyst carrier 400, urea and ammonia generated by decomposition of urea can be used without waste. It is introduced into the inside of the catalyst carrier 400 from the exhaust gas inflow side end face 400a, and nitrogen oxides are reduced and decomposed.
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.

As an example of the exhaust system component of the present invention, there is a diffusion member that is installed inside an exhaust passage through which exhaust gas containing nitrogen oxides flows and partially obstructs the flow of exhaust gas flowing from the upstream of the exhaust passage.
Hereinafter, specific examples of the diffusing member will be described.
7, 8, 9, 10, 11, and 12 are perspective views schematically showing examples of diffusion members that are one embodiment of the exhaust system component of the present invention.

The shape of the diffusing member is not particularly limited as long as it is disposed inside the exhaust passage and can partially block the flow of the exhaust gas flowing from the upstream of the exhaust passage. For example, the shape shown in FIG.
FIG. 7 is a perspective view schematically showing an example of the diffusing member.
The diffusing member 110 shown in FIG. 7 includes a cylindrical outer edge portion 111 and a plurality of blades 112 extending radially from substantially the center of the outer edge portion 111. The blades 112 are inclined at a predetermined angle with respect to the exhaust gas passage direction. Yes.
Therefore, the exhaust gas flowing into the diffusing member 110 flows into the diffusing member 110 from the exhaust gas inflow side end surface 110a, a part of the flow path is blocked by the blades 112, force is applied in the swirl direction, and the exhaust gas outflow side end surface It flows out from 110b. Therefore, on the exhaust gas outflow side of the diffusing member 110, a flow in the swirl direction is generated in the exhaust gas, and the deviation of components contained in the exhaust gas can be reduced.

Since the diffusion member 110 is provided with the carbide layer 12 at a site where the exhaust gas contacts, urea is prevented from being deposited on the surface of the diffusion member 110.

FIG. 8 is a perspective view schematically showing another example of the diffusing member of the present invention, and FIGS. 9, 10 and 12 are perspective views schematically showing still another example of the diffusing member of the present invention. FIG. 11 is a perspective view of still another example of the diffusing member of the present invention as viewed from the exhaust gas outflow side end surface.
Also in these diffusing members, since the carbide layer 12 is provided at the site where the exhaust gas contacts, it is possible to prevent urea from being deposited on the surface of the diffusing member. Since this action is the same for any diffusing member, its description is omitted, and only the shape of the diffusing member will be described.

The diffusing member 120 shown in FIG. 8 includes a cylindrical outer edge portion 121 and a plurality of blades 122 that spirally extend from the approximate center of the outer edge portion 121, and the blades 122 are inclined at a predetermined angle with respect to the passage direction of the exhaust gas. ing.
Like the diffusion member 110 shown in FIG. 7, the diffusion member 120 applies rotation in the swirl direction to the exhaust gas that has passed through the diffusion member, so that the exhaust gas is mixed and the deviation of components contained in the exhaust gas is reduced. Can do.

The diffusing member 130 shown in FIG. 9 includes a cylindrical outer edge portion 131 and a plurality of blades 132 protruding from the inner surface of the outer edge portion 131 toward the substantially center of the outer edge portion. It is inclined at a predetermined angle.
Although the wing 132 is not disposed at the center of the outer edge 131 of the diffusing member 130, it is not essential to block all the flow paths of the exhaust gas passing through the diffusing member 130. Even if it exists, waste gas can fully be mixed and the bias | inclination of the component contained in waste gas can be reduced.

In the diffusing member 140 shown in FIG. 10, a plurality of holes 141 penetrating the front and back are formed on the surface of a disk-shaped base material.
Since the exhaust gas passing through the diffusion member 140 inevitably passes through the hole 141, the flow of the exhaust gas is disturbed when passing through the hole 141, and the exhaust gas is mixed. Can be reduced.

The diffusion member 150 shown in FIG. 11 has a projection 152 for changing the movement direction to a predetermined direction when exhaust gas collides inside the cylindrical outer edge portion 151, and the movement direction of the exhaust gas in a direction different from the projection 152. And a protrusion 153 for changing the shape.
The exhaust gas passing through the diffusion member 150 flows into the diffusion member 150 from the exhaust gas inflow side end surface 150a and flows out from the exhaust gas outflow side end surface 150b. At this time, the exhaust gas collides with the protrusion 152 or the protrusion 153, but the direction in which the exhaust gas colliding with the protrusion 152 moves is different from the direction in which the exhaust gas that has collided with the protrusion 153 moves. The bias of the contained components can be reduced.

A diffusing member 160 shown in FIG. 12 extends in a spiral shape from a cylindrical outer edge portion 161, a doughnut-shaped plate portion 163 having a hole 164, and an inner surface of the plate portion 163 toward the approximate center of the plate portion 163. It consists of a plurality of blades 162, and the blades 162 are inclined at a predetermined angle with respect to the exhaust gas passage direction.
Since the diffusing member 160 has the wings 162, similarly to the diffusing member 110 shown in FIG. 7, the swirling direction rotation is applied to the exhaust gas that has passed through the diffusing member. Further, when the exhaust gas passes through the holes 164 formed in the plate portion 163, the flow of the exhaust gas is disturbed similarly to the diffusion member 140 shown in FIG. 10, the exhaust gas is mixed, and the components contained in the exhaust gas are mixed. The bias can be reduced.

The shape of the diffusing member is not limited to that described above. For example, the holes shown in FIG. 10 may have different sizes and shapes, and are not necessarily arranged at equal intervals. The shapes of the wings, holes, and protrusions described in FIGS. 7, 8, 9, 10, 11, and 12 can be arbitrarily combined.
Further, the diffusion member basically has no movable part, but may have a valve or the like for opening the exhaust gas when the pressure of the exhaust gas increases and forming a new exhaust gas flow path.

FIG. 13 is a cross-sectional view schematically showing an example of an exhaust gas purifying apparatus provided with both a diffusion member and an exhaust pipe as an exhaust system component of the present invention.
The configuration of the exhaust gas purification apparatus 200 shown in FIG. 13 is substantially the same as that of the exhaust gas purification apparatus 100 shown in FIG. 6, but a diffusion member 110 is provided in the exhaust pipe.
The diffusion member 110 is arranged on the downstream side of the urea water injection device 500 and on the upstream side of the catalyst carrier 400.
When the exhaust gas containing urea water injected from the urea water injection device passes through the diffusion member 110, a part of the flow is obstructed and rotates in the swirl direction (the exhaust gas flow is schematically indicated by an arrow G). Show).
Therefore, since the exhaust gas that has passed through the diffusion member 110 circulates in the exhaust pipe while swirling, when the exhaust gas reaches the exhaust gas inflow end surface 400a of the catalyst carrier 400, the component bias in the exhaust gas and / or the temperature distribution. Will be reduced.
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.
Further, the carbide layer 12 is formed on the diffusion member 110, and the carbide layer is a layer made of a urea separation material that is a material to which urea water does not easily adhere. Even if it comes into contact with the resulting carbide layer, the urea water can move away from the carbide layer and flow downstream on the exhaust gas flow.
Furthermore, when the ceramic coat layer (see FIG. 3) is formed on the diffusion member 110 and the carbide layer is formed thereon, the heat insulation performance is excellent, the exhaust gas temperature drop can be suppressed, and the diffusion Urea can be prevented from precipitating on the surface of the member.
Further, since the exhaust gas purification apparatus 200 is also provided with exhaust pipes (50a, 60, 50b) made of the exhaust system parts of the present invention, urea is prevented from being deposited on the surface of the exhaust pipe.

An example of the exhaust system part of the present invention is an exhaust passage through which exhaust gas containing nitrogen oxides flows. As a specific example of the exhaust passage, the exhaust passage is discharged from a factory such as a cement plant instead of the exhaust pipe described above. An example of a flue through which smoke passes will be described below.

FIG. 14 (a) is a perspective view schematically showing an example of a flue that is an embodiment of the exhaust system component of the present invention, and FIG. 14 (b) is a cross-sectional view taken along line AA in FIG. 14 (a). FIG.
In FIG. 14A, exhaust gas G containing nitrogen oxides discharged from a factory such as a cement plant flows toward the catalyst carrier 400 in the direction of the arrows (solid line and dotted line).
A rectangular tubular member, which is an exhaust passage through which the exhaust gas G flows, is the flue 70, and a urea water injection device 500 that injects urea water into the flue 70 is provided on the upstream side of the exhaust passage. .

The exhaust system component of the present invention is provided on the downstream side of the urea water injection device 500 and is a flue 70 in which the carbide layer 12 is formed on the inner peripheral surface of the base material 11 which is a rectangular tubular member. is there.
When the exhaust gas containing nitrogen oxides flows along with the urea water inside the flue 70, even if the exhaust gas containing urea water comes into contact with the carbide layer made of the separated urea water material, the urea water is separated from the carbide layer, It can flow downstream with the flow of exhaust gas.
That is, similar to the case of the exhaust pipe as an exhaust passage, the effect of the present invention is exhibited even when the exhaust system component of the present invention is used as a flue through which exhaust gas from a factory or the like flows. be able to.

Moreover, you may arrange | position the diffusion member as an exhaust-system component of this invention in the flue as an exhaust passage.
In addition, as a catalyst support | carrier arrange | positioned in a flue, the catalyst support | carrier conventionally used in this field | area, such as a ceramic honeycomb catalyst, can be used.

Next, an example of a method for manufacturing an exhaust system component of the present invention will be described.
First, a base material is prepared.
Since the material which comprises a base material was demonstrated in description of the diffusion member of this invention, it abbreviate | omits.
A substrate is prepared by processing the substrate into a shape of an exhaust passage such as a cylinder or a rectangular tube, or the shape of a diffusion member shown in FIG.
Subsequently, if necessary, a cleaning process may be performed to remove impurities on the surface of the substrate. The cleaning process is not particularly limited, and a conventionally known cleaning process can be used. Specifically, for example, a method of performing ultrasonic cleaning in an alcohol solvent can be used.

In addition, after the cleaning treatment, as necessary, the surface of the base material is subjected to a roughening treatment in order to increase the specific surface area of the base material or adjust the surface roughness of the base material. May be. Specifically, for example, a roughening process such as a sandblast process, an etching process, or a high temperature oxidation process may be performed. These may be used alone or in combination of two or more.
You may perform a washing process after this roughening process.

After the ceramic coat layer is formed on the prepared base as necessary, a carbide layer is formed.
When the carbide layer is formed directly on the surface of the base material as a layer different from the base material as in the exhaust system component 10 shown in FIG. 1, the carbide layer is treated by vapor deposition, sputtering, spraying, etc. on the base material. Can be formed. Vapor deposition is preferred when forming a carbide layer made of carbon, and thermal spraying is preferred when forming a carbide layer made of tungsten carbide.

When the carbide layer is formed by surface-treating the surface of the substrate as in the exhaust system component 20 shown in FIG. 2, solid carburization, gas carburization, liquid carburization, vacuum carburization (vacuum gas carburization), plasma carburization (ion The carbonized metal layer can be formed by a method such as carburization.

When the exhaust system component 30 shown in FIG. 3 is manufactured, a ceramic coat layer and a carbide layer are formed.
First, a raw material composition for forming a ceramic coat layer is prepared.
The raw material composition used for forming the ceramic coat layer preferably contains an amorphous inorganic material, and more preferably contains a crystalline inorganic material and / or a pore former.

Since the kind, material, material, and other characteristics of the amorphous inorganic material have already been described, a description thereof will be omitted.
When preparing the raw material composition used for the formation of the ceramic coat layer, each raw material is prepared and then wet pulverization is performed. The amorphous inorganic material powder is first adjusted to an appropriate particle size. After preparing the raw material, it is preferable to obtain a product having a target particle size by wet pulverization.

As for the crystalline inorganic material, its type, material, material, its characteristics and the like have already been described, and therefore will be omitted. When preparing the raw material composition used for forming the ceramic coat layer, wet pulverization is performed after each raw material is prepared, but in the case of a crystalline inorganic material, the first adjusted to an appropriate particle size is used. It is preferable to obtain the desired particle size by wet pulverization after preparation of the raw materials.

The weight of the crystalline inorganic material particles is preferably 5 to 60 parts by weight with respect to 100 parts by weight of the entire ceramic coat layer (total weight of the amorphous inorganic material and the crystalline inorganic material).
By using the particles of the crystalline inorganic material in such a weight ratio with respect to the total weight of the ceramic coat layer, the crystalline inorganic material is contained in the amorphous inorganic material layer constituting the manufactured exhaust system part. The particles can be dispersed at an appropriate ratio to ensure the heat resistance and heat insulation of the ceramic coat layer. It is more preferable that the weight of the crystalline inorganic material particles is set to 10 to 40 parts by weight with respect to 100 parts by weight of the entire ceramic coat layer.

When the weight of the crystalline inorganic material particles relative to 100 parts by weight of the entire ceramic coat layer is less than 5 parts by weight, the amount of the crystalline inorganic material particles dispersed in the amorphous inorganic material layer is small. The pores dispersed inside are easily moved in the high temperature range, and the heat insulating property is lowered.
On the other hand, when the weight of the crystalline inorganic material particles exceeds 60 parts by weight with respect to 100 parts by weight of the entire ceramic coat layer, the amount of the amorphous inorganic material is relatively reduced. Layer formation) becomes difficult, and peeling from the base material is likely to occur.

Next, the pore former will be described.
The pore former is used to form pores in the ceramic coat layer when a coating film is formed on the surface of the substrate using the raw material composition and then the ceramic coat layer is formed by heating and firing.

As the pore former, for example, balloons that are fine hollow spheres composed of oxide ceramics, spherical acrylic particles, carbon such as graphite, carbonates, foaming agents, and the like can be used. The formed ceramic coat layer preferably has a high heat insulating performance. For that purpose, it is preferable that pores having a diameter as small as possible are uniformly dispersed.

From such a viewpoint, the pore former is preferably carbon, carbonate or foaming agent.
Examples of the carbonate and the foaming agent include CaCO ₃ , BaCO ₃ , NaHCO ₃ , Na ₂ CO ₃ , (NH ₄ ) ₂ CO _{3 and the} like.
Further, among these pore formers, carbon such as graphite is preferable. This is because carbon can be dispersed as fine particles in the raw material composition by a treatment such as pulverization, and can be decomposed by heating and firing to form pores having a suitable pore size.

In addition to the amorphous inorganic material, the crystalline inorganic material, and the pore former, a dispersion medium, an organic binder, and the like may be added to the raw material composition.
Examples of the dispersion medium include water and organic solvents such as methanol, ethanol, and acetone. The blending ratio of the mixed powder or the amorphous inorganic material powder and the dispersion medium contained in the raw material composition is not particularly limited, but for example, dispersed with respect to 100 parts by weight of the amorphous inorganic material powder. The medium is preferably 50 to 150 parts by weight. It is because it becomes a viscosity suitable for apply | coating to a base material.
As an organic binder which can be mix | blended with a raw material composition, polyvinyl alcohol, methylcellulose, ethylcellulose, carboxymethylcellulose etc. can be mentioned, for example. These may be used alone or in combination of two or more.
Moreover, you may use a dispersion medium and an organic binder together.

Furthermore, a slurry (also referred to as a carbide-based ceramic-containing slurry) containing a material (carbide-based ceramic) that becomes a carbide layer is prepared separately from the raw material composition.
Since the type, material, material, and other characteristics of the carbide-based ceramic have already been described, a description thereof will be omitted.
The carbide-based ceramic-containing slurry is prepared by dispersing carbide-based ceramic particles in a dispersion medium.
Examples of the dispersion medium include water and organic solvents such as methanol, ethanol, and acetone, as in the case of the dispersion medium used for the raw material composition. Similarly to the raw material composition, for example, polyvinyl alcohol, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, or the like may be mixed as the organic binder.
And it is preferable to mix the same amorphous inorganic material as the amorphous inorganic material contained in the raw material composition for forming a ceramic coat layer with this slurry.

An exhaust system part is manufactured as follows using the above-described base material, raw material composition, and carbide-based ceramic-containing slurry.

(1) Process of coating the raw material composition on the surface of the substrate As a method of coating the raw material composition on the surface of the substrate, for example, spray coating, electrostatic coating, inkjet, transfer using a stamp or roller, Methods such as brush coating or electrodeposition coating can be used. Moreover, you may coat the said raw material composition by immersing a base material in a raw material composition.
If necessary, the substrate coated with the raw material composition may be dried.
The drying conditions are preferably 50 to 150 ° C. and about 10 to 180 minutes.

(2) Process of coating carbide-based ceramic-containing slurry The carbide-based ceramic-containing slurry is coated on the raw material composition coated on the base material.
By doing so, the carbide-based ceramic is distributed on the surface of the raw material composition.
As a method for coating the carbide-based ceramic-containing slurry, a method similar to the method exemplified as the method for coating the raw material composition can be used.
If necessary, the substrate coated with the carbide-based ceramic-containing slurry may be dried. The drying conditions are preferably 50 to 150 ° C. and about 10 to 180 minutes.

(3) Step of performing firing treatment Specifically, a ceramic coat layer and a carbide layer are formed by heating and firing a base material coated with the raw material composition and the carbide-based ceramic-containing slurry.
The firing temperature is preferably equal to or higher than the softening point of the amorphous inorganic material, and is preferably 700 ° C. to 1100 ° C., although it depends on the type of the blended amorphous inorganic material and the type of pore former. By setting the firing temperature to a temperature equal to or higher than the softening point of the amorphous inorganic material, the substrate and the amorphous inorganic material can be firmly adhered to each other, and a ceramic coat layer that is firmly adhered to the substrate is formed. Because you can.
By the firing treatment, the carbide-based ceramic distributed on the surface of the raw material composition forms a carbide layer on the ceramic coat layer.

In addition, instead of using a carbide-based ceramic-containing slurry, a carbide layer may be formed by forming a ceramic coat layer on the substrate and then performing a process such as vapor deposition, sputtering, or thermal spraying on the ceramic coat layer. Good.

The effects of the exhaust system parts and the exhaust gas purification apparatus of the present invention will be listed below.
(1) In the exhaust system component of the present invention, the surface on the side where exhaust gas contacts is made of a carbide layer.
It can be said that the carbide layer is a layer made of a separated urea water material which is a material to which urea water does not easily adhere. Therefore, even if the exhaust gas containing urea water comes into contact with the carbide layer made of the separated urea water material, the urea water can move away from the carbide layer and flow downstream on the exhaust gas flow.
The urea water on the exhaust gas flow again flows toward the catalyst carrier and is supplied as an ammonia source.
That is, when the exhaust system component of the present invention is provided in a portion that comes into contact with the exhaust gas containing nitrogen oxides in the urea SCR system, urea can be prevented from being deposited on the surface of the exhaust system component.

(2) The exhaust system component of the present invention can be a cylindrical member used as an exhaust passage through which exhaust gas containing nitrogen oxides flows. When the exhaust system component is used as an exhaust passage, urea is formed on the surface of the exhaust passage. Is prevented from depositing.

(3) The exhaust system component of the present invention can be a diffusion member that is installed inside an exhaust passage through which exhaust gas containing nitrogen oxides flows, and that partially inhibits the flow of exhaust gas flowing from the upstream of the exhaust passage. When the exhaust system component is used as the diffusion member, urea is prevented from being deposited on the surface of the diffusion member.

(4) In the exhaust gas purification apparatus of the present invention, the urea water injection device is provided upstream of the exhaust passage, and the exhaust gas purification device is provided downstream of the exhaust passage.
The exhaust system component of the present invention is used at a site where the exhaust gas contacts with the downstream side of the urea water injector and the upstream side of the catalyst carrier.
With such a configuration, even if the exhaust gas containing urea water injected from the urea water injection device into the exhaust passage comes into contact with the exhaust system parts in the region between the urea water injection device and the catalyst carrier, Apart from the carbide layer, it can flow downstream with the exhaust gas flow.
Therefore, urea is prevented from depositing on the surface of the exhaust system part located between the urea water injection device and the catalyst carrier.

(Example)
Examples that specifically disclose one embodiment of the present invention will be described below. In addition, this invention is not limited only to these Examples.

(1) Preparation of base material As a base material, a 40 mm × 40 mm × 1.5 mmt stainless steel base material (manufactured by SUS430) is prepared, subjected to ultrasonic cleaning in an alcohol solvent, and subsequently subjected to a sand blast treatment. The surface (both sides) of was roughened. The sandblast treatment was performed for 10 minutes using # 100 Al ₂ O ₃ abrasive grains.
When the surface roughness of the substrate was measured using a surface roughness measuring machine (Handy Surf E-35B, manufactured by Tokyo Seimitsu Co., Ltd.), the surface roughness of the substrate was Rz _JIS = 8.8 μm. .
The base material was prepared by the said process.

Example 1
(2-1) Formation of Carbon Carbide Layer Carbon was vapor-deposited on the base material prepared in (1) above to form a carbon carbide layer, and an evaluation sample was prepared.
The thickness of the carbide layer was 0.1 μm.
Formation of a carbide layer by vapor deposition of carbon was performed by repeatedly vapor-depositing until a predetermined carbide layer thickness was obtained using SC-701CT QUICK CARBON COATER manufactured by Sanyu Electronics Co., Ltd.

(Example 2)
(2-2) Formation of Carbide Layer Consisting of Tungsten Carbide A carbide layer composed of tungsten carbide was formed by thermal spraying on the base material prepared in (1) above to produce a sample for evaluation.
The thickness of the carbide layer was 20 μm.
Formation of the carbide layer by thermal spraying of tungsten carbide was performed by using a cermet WC / 12% Co powder (15 to 45 μm, manufactured by Utec Co., Ltd.) as a thermal spraying material by a high-speed plasma spraying apparatus under the following conditions.
Current: 400A
Electric power: 43kw
Plasma gas used: Ar80L / min, He5L / min
Thermal spray distance: 130mm from the tip of the thermal spray gun to the substrate surface
Thermal spray gun moving speed: 670 mm / s

Example 3
(2-3) Formation of ceramic coat layer and carbide layer A sample for evaluation is formed by forming a ceramic coat layer on the base material prepared in (1) above, and depositing a carbon on the ceramic coat layer to form a carbide layer. Was made.

(2-3-1) Preparation of raw material composition Barium silicate glass (softening point 770 ° C) was prepared as a powder of an amorphous inorganic material. The amorphous inorganic material powder had an average particle size of 15 μm and contained 35% by weight of silica.
In addition to 35 parts by weight of the amorphous inorganic material powder, 15 parts by weight of crystalline inorganic material (zirconia), 0.012 parts by weight of carbon as a pore former, 0.5 parts by weight of organic binder (methylcellulose), And water was added and mixed so that a total weight might be 100 weight part.

(2-3-2) Application of raw material composition and the raw material composition was applied to the entire surface of the dried substrate by a spray coating method, and dried in a dryer at 70 ° C. for 20 minutes.

(2-3-3) Formation of ceramic coating layer by firing treatment Subsequently, a ceramic coating layer having a thickness of 500 μm was formed by heating and firing treatment in air at 850 ° C. for 90 minutes.

(2-3-3) Formation of Carbide Layer Consisting of Carbon Carbon was vapor-deposited on the ceramic coat layer formed in the above (2-3-3) to form a carbide layer composed of carbon, and an evaluation sample was prepared. .
The thickness of the carbide layer was 0.1 μm.
Formation of a carbide layer by vapor deposition of carbon was performed by repeatedly vapor-depositing until a predetermined carbide layer thickness was obtained using SC-701CT QUICK CARBON COATER manufactured by Sanyu Electronics Co., Ltd.

(Comparative Example 1)
In Example 3, an evaluation sample was obtained in which only a ceramic coat layer made of a raw material composition was formed on a base material without forming a carbide layer made of carbon.

(Comparative Example 2)
In Example 1, the carbide layer was not formed, and the base material prepared in (1) Preparation of base material was used as an evaluation sample as it was.

(Evaluation of urea water adhesion by contact angle measurement)
1 g of urea water (32.5% urea water for SCR system: AdBlue (registered trademark)) was dropped on the evaluation sample prepared in each example and comparative example, and the sample was taken with a digital camera from the horizontal direction. A line on the surface of the base material and a tangent line at the contact point of the base material and urea water were entered in the photographed image, and the contact angle was measured with a protractor.
Example 1: Contact angle 50 °
Example 2: Contact angle 55 °
Example 3: Contact angle 54 °
Comparative Example 1: Contact angle 30 °
Comparative Example 2: Contact angle 35 °
In the sample for evaluation of each example, urea water was dropped on the surface on which the carbide layer was formed.
In the sample for evaluation of Comparative Example 1, urea water was dropped on the surface of the ceramic coat layer, and in the sample for evaluation of Comparative Example 2 on the surface of the substrate.
From this, it was found that the adhesion amount of urea water can be reduced when the surface on the exhaust gas contact side is made of a carbide layer as in the evaluation samples according to Examples 1 to 3.

10, 20, 30 Exhaust system parts 11 Base material 12, 13, 35 Carbide layer 32 Ceramic coating layer 33 Amorphous inorganic material 34 Crystalline inorganic material 36 Pore 50, 50a, 50b, 60 Exhaust pipe 70 Flue 100, 200 Exhaust gas purification device 110, 120, 130, 140, 150, 160 Diffusion member 400 Catalyst carrier 500 Urea water injection device G Exhaust gas

Claims (12)

An exhaust system component provided at a site that comes into contact with exhaust gas containing nitrogen oxides,
An exhaust system part characterized in that the surface on the side in contact with the exhaust gas comprises a carbide layer formed on a base material made of metal. The substrate;
A ceramic coat layer formed on the surface of the substrate on the side in contact with the exhaust gas;
The exhaust system component according to claim 1, comprising a carbide layer formed on the ceramic coat layer. The exhaust system component according to claim 2, wherein the ceramic coat layer includes an amorphous inorganic material and a crystalline inorganic material. The exhaust system component according to claim 3, wherein the amorphous inorganic material is a low-melting glass having a softening point of 300 to 1000 ° C. The exhaust system component according to any one of claims 2 to 4, wherein pores are formed in the ceramic coat layer. The substrate;
The exhaust system component according to claim 1, comprising a carbide layer provided by subjecting the base material to a surface treatment. The exhaust system component according to any one of claims 1 to 6, wherein the carbide layer is made of carbon or tungsten carbide. The exhaust system component according to any one of claims 1 to 7, which is a cylindrical member used as an exhaust passage through which exhaust gas containing nitrogen oxides flows. The exhaust system component according to any one of claims 1 to 7, wherein the exhaust system component is a diffusion member that is installed inside an exhaust passage through which exhaust gas containing nitrogen oxides flows and partially blocks the flow of exhaust gas flowing from upstream of the exhaust passage. . An exhaust passage through which exhaust gas containing nitrogen oxides flows;
A urea water injection device that is provided upstream of the exhaust passage and injects urea water into the exhaust passage;
An exhaust gas purification apparatus comprising a catalyst carrier provided downstream of the exhaust passage,
The exhaust system component according to any one of claims 1 to 9, wherein the exhaust system component is used in a portion where the exhaust gas contacts with the downstream side of the urea water injection device and the upstream side of the catalyst carrier. Exhaust gas purification device. The exhaust gas purification apparatus according to claim 10, wherein the exhaust system part according to any one of claims 1 to 9 is used as the exhaust passage. The exhaust system component according to any one of claims 1 to 9, wherein the exhaust system component according to any one of claims 1 to 9 is used as a diffusion member that is installed inside the exhaust passage and partially obstructs the flow of exhaust gas flowing from upstream of the exhaust passage. The exhaust gas purification apparatus according to 1.

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