JPH10296090A - Metallic catalyst converter and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ameliorate the resistance to oxidation at high temperatures on the end face of an exhaust gas inlet side and near the end face by adding the concentration of an element such as Cr or Al to a metallic foil material from the end face of the exhaust gas inlet side to a specific inside area of a honeycomb material made up of a metallic plain foil and a metallic corrugated foil rolled in a stacked state with numerous air holes formed in the axial direction and thereby, making the element concentration value higher than the average concentration value of the entire foils. SOLUTION: A sprayed layer 6 of Al is formed on a honeycomb material 3 made up of the corrugated foil 1 and the plain foil 2 of a metallic foil material rolled in a stacked state with numerous air holes 4 formed in the axial direction in such a manner that the Al concentration value from the end face of the exhaust gas inlet side to an area extending 0.2 mm from the former is made higher than the average concentration value of the entire metallic foil material. In addition, a ring-like elastic support which is wound around the outer periphery of the honeycomb material 3 and fastened is formed and further, a metal carrier is formed by mounting the honeycomb material 3 on an outer cylinder through the ring-like elastic support wound around the outer periphery. A catalyst is borne in the air holes 4 of the honeycomb material 3 to obtain the metallic catalyst converter. Thus it is possible to ameliorate the resistance to oxidation at high temperatures at least, in the exhaust gas inlet side area of the honeycomb material 3 and thereby, enhance the durability of the honeycomb material 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal catalytic converter installed in an exhaust gas passage of various internal combustion engines and used for purifying the exhaust gas, and a method of manufacturing the same.

[0002]

2. Description of the Related Art As a catalytic converter for purifying exhaust gas from various internal combustion engines such as automobiles, boilers, and generators, a flat metal foil material is used in a cylindrical metal casing (hereinafter referred to as an outer cylinder). There is a metal catalytic converter in which a honeycomb body in which a number of ventilation holes are formed in the axial direction by laminating and winding corrugated foils is mounted, and a catalyst is supported on the honeycomb body. Such a catalytic converter made of metal can raise the temperature to the activation temperature of the catalyst faster than that made of ceramics,
In addition, due to the low resistance of the passage of exhaust gas, its use has been increasing in recent years.

[0003] A honeycomb body used for this metal catalytic converter is usually formed by superimposing a flat foil of heat-resistant stainless steel and a corrugated foil corrugated on the flat foil and winding the flat foil into a spiral shape. It is manufactured by joining the contact portions by brazing, liquid phase diffusion bonding, diffusion bonding, or the like, in which a number of air holes surrounded by flat foil and corrugated foil are formed in the axial direction. Then, the honeycomb body is inserted into an outer cylinder, and the honeycomb body and the outer cylinder are directly joined by brazing or the like to form a metal carrier.

A catalyst supporting layer made of activated alumina or the like is formed on the surface of the inside of the vent hole of the honeycomb body constituting the metal carrier, and a catalyst such as Pt is supported on the catalyst supporting layer to form a metal catalytic converter. The metal catalytic converter is installed in an exhaust gas passage of various internal combustion engines, and passes exhaust gas to detoxify harmful components such as NOx and CO in the exhaust gas by catalytic action. At this time, the metal catalytic converter is heated by the reaction heat in addition to the heat transfer from the exhaust gas as the high-temperature exhaust gas passes.

By the way, in order to quickly raise the temperature at which the catalyst acts immediately after the start of the internal combustion engine, a catalyst must be installed near the engine to reduce the heat loss until exhaust gas reaches the catalyst. Is valid. However, when the catalyst is close to the engine, for example, when the car starts running at high speed, the catalyst will be exposed to higher temperature, high speed exhaust gas, and the oxidation of the metal material constituting the metal carrier will be promoted, There is a problem that the strength is reduced to cause breakage.

As a countermeasure, a ferrite stainless steel containing about 20% of Cr to which Al for improving oxidation resistance or Nb for increasing high-temperature strength is added is used as a metal foil material. However, if the Al content is high, the material becomes hard and brittle, and cannot be rolled. Therefore, the Al content is suppressed to about 5% at the maximum.

In the process of manufacturing the honeycomb body, heat treatment is performed at about 1200 ° C. in a vacuum furnace in order to join the flat foil and the corrugated foil.
As a result, there is also a problem that the Al concentration at the end face is reduced and the oxidation resistance is reduced by evaporating to the outside.

Further, the end face of the honeycomb body on the exhaust gas inlet side is not only most susceptible to the effects of rapid heating due to the heat of the exhaust gas and corrosion due to the exhaust gas components, but also has the strongest impact energy of the exhaust gas. The foil is cut,
Chipping or damage is likely. If the foil is chipped or the chipped foil collides with the carrier with exhaust gas energy, the damage to the carrier may be further increased.

As a countermeasure against this, Japanese Patent Laid-Open Publication No.
As disclosed in Japanese Patent Application Laid-Open No. H10-260, a method is disclosed in which a steel sheet having a high Al content is formed by applying Al plating to the surface of a steel sheet and diffusing the Al into the steel sheet. As an extension of the same idea, a method of applying Al plating to the surface of a steel sheet by hot-dip Al plating or calorizing method, stopping the diffusion process of Al halfway, and forming a high Al content alloy layer on the surface is applied to the metal carrier A method for performing this is disclosed in JP-B-56-41298.

[0010] These methods are similar to the methods described in Japanese Patent Application Laid-Open Nos. 1-176454 and 2-8, although there are differences in details.
No. 6,848, JP-A-2-180644, JP-A-7-323233, JP-A-8-80442, JP-A-8-108078, and the like.

However, in the hot-dip Al plating method, for example, as in the case of a catalyst carrier for purifying exhaust gas of an automobile, the cell density is 4%.
It is not practical to uniformly apply hot-dip plating to the pores where 00CPSI is used as standard, and it may cause clogging. In the calorize method, it is difficult to uniformly load the Al powder and the halide powder into the pores, and it is extremely difficult to maintain the temperature inside the carrier uniformly. Cannot uniformly coat Al. Further, the coating time is typically 24 hours or more, and the productivity is extremely low, and practical application is difficult.

Since the above-mentioned hot-dip Al plating method and calorizing method have a common obstacle, there is no example applied to a metal carrier for purification treatment of automobile exhaust gas and put to practical use. Defects common to the above methods are that the production cost becomes too high, and that the plating thickness is difficult to control, and that uniform plating cannot be performed at a reliable and practical level.

As mass production techniques for increasing the amount of Al,
As described in JP-A-1-194942, aluminum or an aluminum alloy is attached to both sides of a stainless steel foil, and then the diffusion of Al is stopped halfway, and A
A method for forming an alloy layer having a high l content is disclosed.

[0014] This method can provide uniform plating at a practical level with high reliability, and thus is close to practical use as compared with hot-dip Al plating and the calorization method, but the production cost is still too high. It has become a challenge.

[0015]

SUMMARY OF THE INVENTION The present invention provides a catalytic converter made of metal for purifying exhaust gases of various internal combustion engines, in which at least the exhaust gas entry side end face of the honeycomb body and the vicinity thereof are improved in high-temperature oxidation resistance, Provided is a metal catalytic converter and a method for manufacturing the same, which can improve durability while solving the problem of high cost and the problem of reduced workability during manufacturing.

[0016]

That is, the present invention relates to a metal catalytic converter which is installed in the exhaust gas passage of various internal combustion engines and purifies the exhaust gas. Hereinafter, the flat foil and the corrugated foil are also referred to as a “metal foil material”.) A honeycomb body having a large number of ventilation holes formed in an axial direction by being wound and mounted thereon is attached, and at least the end face of the honeycomb body on the exhaust gas entry side. In the region from to the inner side of 0.2 mm or more, an element such as Cr or Al for improving high-temperature oxidation resistance is added to the metal foil material, the concentration of this element is made higher than the average of the entire metal foil, and the honeycomb body is formed. A catalyst is supported on a surface of a vent hole of a metal catalyst.

In the present invention, particularly, in the region from the end of the honeycomb body on the exhaust gas entry side to the inner side of 0.2 mm or more, the high-temperature oxidation resistance of the metal foil material forming the honeycomb body is reinforced and its durability is improved. As a means of reinforcing heat resistance and oxidation resistance, a metal foil material forming a honeycomb body is coated with an element for improving high-temperature oxidation resistance, and a non-oxidizing atmosphere is provided. It is also characterized in that a flat foil and a corrugated foil are joined by mutually diffusing the coated metal and the metal foil material by heat treatment (for example, under vacuum). At this time, the honeycomb body is preferably stored in an outer cylinder for processing, or may be stored after processing.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
In the present invention, in the region of at least 0.2 mm or more from the end face on the exhaust gas entry side of the honeycomb body, a large amount of an element for improving high-temperature oxidation resistance is added to the metal foil material forming the honeycomb body, and the concentration of the element is increased. The reason for increasing is as follows. That is, after the engine durability test of the metal catalytic converter, as a result of investigating the component distribution in the stainless steel foil (containing 1 to 6% of Al) forming the honeycomb body, the area from the end face on the exhaust gas entry side to 0.2 mm was measured. In this case, since the decrease in Al is remarkable, and as a result, the metal foil material is oxidized and the damage is likely to be enlarged, at least the Al concentration in this region is increased to ensure the oxidation resistance function for a long time. That's why.

The term "addition" as used herein means that the surface of the metal foil material is coated by, for example, thermal spraying, bonding, coating or the like. The "concentration" of the element that improves the high-temperature oxidation resistance is the weight of the element originally contained in the material of the metal foil and the element added to the surface of the metal foil, based on the weight of the metal foil. Total weight of weight (% by weight)
Means

When the element for improving the high-temperature oxidation resistance is added to the surface of the metal foil material, the concentration of the element in the addition region is 5 to 15% by weight (the average concentration of the element in the entire metal foil at this time) Is 1 to 5% by weight), it is possible to secure sufficient high-temperature oxidation resistance.

As an element for improving high-temperature oxidation resistance, A
In addition to l, Cr, Si, or the like can be used, and the region where the concentration of these elements is increased is preferably selected within a range of 30 mm from the end face on the exhaust gas entry side of the honeycomb body. There is an effect of improving the high-temperature oxidation resistance even in a region beyond this region, but the degree of oxidation in that region is not remarkable, and the concentration of the element that improves the high-temperature oxidation resistance is increased up to 30 mm from the end face on the exhaust gas entry side. There is no merit in the case where the cost is taken into consideration.

As a mass production technique for increasing the concentration of an element for improving high-temperature oxidation resistance, for example, Al, in the specific region of the honeycomb body, low-temperature spraying of aluminum or aluminum alloy within a range of 30 mm or less from an end face is used. A method of coating a metal for improving high-temperature oxidation resistance and heating it in a non-oxidizing atmosphere to interdiffuse the metal between the metal foil material and aluminum can be used.

In this low-temperature spraying, 20 to
For a 50 μm metal foil material, a metal such as aluminum or aluminum alloy which improves high temperature oxidation resistance
It can be coated with a thickness of 0 μm or less.

The coating of the element for improving the high-temperature oxidation resistance can be carried out before or during the forming of the honeycomb body. However, this may cause a reduction in the formability and the precision of the formation. The coating is preferably performed after forming the honeycomb body because the metal that improves the high-temperature oxidation property is likely to be excessively consumed.

The element for improving the high-temperature oxidation resistance may be uniformly coated on the whole inside of the honeycomb body, but it is impossible after the honeycomb body is formed. Then, the degree of oxidation is not remarkable, so that the concentration of the element for improving the high-temperature oxidation resistance is equal to the region up to 30 mm from the end face on the exhaust gas inlet side, since there is no merit in consideration of the cost for that, Practically, it is advantageous to limit it to a range within 30 mm from the end face.

As a means for coating the element for improving the high-temperature oxidation resistance, low-temperature spraying, which can easily secure adhesion in a relatively low-temperature region, is effective. When performing low-temperature spraying, the honeycomb body is sprayed in the spraying direction. By performing the rotation while tilting and rotating, a more uniform sprayed layer can be formed in a desired region.

In the present invention, when forming the honeycomb body, the corrugated foil has a trapezoidal cross section having a flat portion with a crest (bottom) width of 0.2 to 0.5 mm. It is effective to easily attach a metal such as aluminum or an aluminum alloy which improves oxidation resistance to a corner portion in contact with the flat foil when the metal is sprayed at a low temperature. And by making the contact angle between the flat foil and the corrugated foil flat portion 40 degrees or more, preferably 60 degrees or more, aluminum or an aluminum alloy can enter the corner of the contact portion between the flat foil and the corrugated foil. If this is diffused at around 1000 ° C., a flat foil and a corrugated foil in a range of 0.5 mm or more, preferably 5 mm or more from the end face can be joined, thereby effectively preventing damage due to the notch effect on the end face. Can be prevented.

The width of the crest (bottom) of the corrugated foil is 0.2 to 0.
The reason why the thickness is set to 5 mm is that, in addition to the above reasons, the cross section can be easily processed into a trapezoidal shape, and the cell density (holes in the axial direction) of the honeycomb body can be appropriately obtained.

Although the conventional knowledge mentions a method of diffusing aluminum coated on the surface by a hot-dip plating method or a calorizing method into a metal foil material and alloying the same, the present inventors have conducted experiments. If aluminum is present in close contact with the surface of the metal foil material by low-temperature spraying, alloying at the coating stage at the initial stage like the hot-dip plating method and calorizing method does not cause chemical bonding However, it has been found that the integration process can be sufficiently performed. That is, when sprayed at a low temperature, the alloy is not uniformly alloyed. However, if the alloy is held at about 900 ° C. in a vacuum furnace, Fe or Cr is diffused and alloyed in aluminum. If this is raised to a high temperature of 1000 ° C. or more,
The aluminum that suddenly flows out when heated to a high temperature does not move to its original location, but causes interdiffusion, forming an alloy layer with a high aluminum concentration but close to the composition of the metal foil material and integrated with the metal foil material Can be

Therefore, in the present invention, after the element for improving the high-temperature oxidation resistance, for example, aluminum, is sprayed at a low temperature, the honeycomb body is introduced into a vacuum furnace, and is subjected to a heat treatment at a temperature higher than the melting point of the aluminum. In this case, the degree of vacuum (pressure) of the atmosphere in the vacuum furnace is equal to or higher than the vapor pressure of aluminum (preferably 1.1 to 2.0 times the vapor pressure of aluminum). Thus, it is effective to suppress the evaporation of aluminum, and such a condition can be satisfied by selecting the degree of vacuum (pressure) of the vacuum furnace.

According to the present invention, as described above, the element for improving the high-temperature oxidation resistance is reinforced in the honeycomb body constituting the metal catalytic converter, particularly in the exhaust gas inlet side region,
The high-temperature oxidation resistance of the metal foil material in this region can be improved, and at the same time, the corrugated foil and the flat foil can be bonded firmly by diffusion bonding.

This diffusion bonding can be performed in a relatively low temperature range of 900 to 1000 ° C., and compared with the conventional bonding performed at about 1100 ° C. by using a brazing material, the brazing material and the brazing material mounting work are not required. Since it becomes unnecessary, manufacturing cost can be reduced and productivity can be improved.

Hereinafter, the present invention will be further described based on specific examples shown in the drawings. FIG. 1 shows a honeycomb body constituting a metal catalytic converter of the present invention in a state where a part of an outer peripheral portion is unwound. In the figure, reference numeral 3 denotes a honeycomb body formed by laminating and winding a corrugated foil 1 and a flat foil 2 formed of a metal foil material and having a large number of ventilation holes 4 formed in an axial direction, and forming a region on the inlet side of the exhaust gas 5. A thermal spray layer 6 made of aluminum is formed on the side end portions of the corrugated foil 1 and the flat foil 2 to make the Al concentration higher than the average of the entire metal foil material.

The honeycomb body 3 is mounted in an outer cylinder.
In other words, as shown in FIG. 2, the honeycomb body 3 is wound around the outer periphery of the honeycomb body 3 around the ring-shaped elastic support body 7 having a corrugated ring shape so as to have a further overlap of several mm. It is joined 9 to the honeycomb body at several points in the circumferential direction. The joining method is not particularly limited, but may be electric resistance welding, brazing, aluminum-mediated diffusion joining, or the like.

On the other hand, the ring-shaped elastic support member 8 having a corrugated cross section overlaps with the ring-shaped elastic support member 7 wound around the outer periphery of the honeycomb body 3 on the exhaust gas entry side. Wrap so that a part protrudes from the end face.

Then, the honeycomb body 3 around which the ring-shaped elastic supports 7 and 8 are wound around the outer periphery is inserted into the outer cylinder 11,
The protruding portion of the ring-shaped elastic support body 8 on the exhaust gas entry side of the honeycomb body 3 is joined by brazing using aluminum foil 9 as a brazing material or by aluminum-mediated diffusion bonding to support the honeycomb body 3 in a ring-shaped elastic support manner. It can be fixed to the outer cylinder 11 via the bodies 7 and 8.

When the ring-shaped elastic support 8 is wound around the outer periphery of the ring-shaped elastic support 7, one round and a few mm are added in order to maintain the sealing property between the ring-shaped elastic supports 7 and 8. Be sure to wrap it so that there is some overlap.
At this time, by coating the contact surface between the ring-shaped elastic supports 7 and 8 with ceramics, the heat insulating effect between the honeycomb body 3 and the outer cylinder 11 can be enhanced.

In this manner, as shown in FIG. 1, the Al concentration in the specific region 10 on the exhaust gas entry side of the honeycomb body 3 formed by overlapping and winding the corrugated foil 1 and the flat foil 2 made of a metal foil material. Body 3 in which the average is higher than the average of the entire metal foil material
As shown in FIG. 2, a metal carrier is formed by attaching to an outer cylinder 11 via a ring-shaped elastic support 7 wrapped around the outer periphery and a ring-shaped elastic support 8 wrapped around the outer periphery. Then, a catalyst is supported in the ventilation holes 4 of the honeycomb body 3 to manufacture a metal catalytic converter.

As shown in FIG. 3B, the corrugated foil 1 forming the honeycomb body generally has a sine curve type top 13 as shown in FIG. 3B. As shown, the cross section is trapezoidal, and the top (bottom) 12
And a flat portion having a width of 0.2 to 0.5 mm is formed. The contact angle θ with the flat foil 2 is set to 40 ° or more to secure an appropriate contact area and to obtain a sufficient bonding strength. It is desirable to secure the flat foil 2 and the corrugated foil 1 from the end face of the honeycomb body 3 on the exhaust gas entry side by 0.5 mm or more by diffusion bonding.

[0040]

EXAMPLE A metal catalytic converter according to the present invention is manufactured.
An evaluation experiment was performed. Experimental conditions and experimental results are compared with those of the conventional example, and are described below with reference to Tables 1 to 3. The experimental conditions are shown in Tables 1 and 2, and the experimental results and evaluation results are shown in Table 3.

[0041]

[Table 1]

[0042]

[Table 2]

[0043]

[Table 3]

Experimental Example 1 Fe-20 wt% Cr-5 wt%
Al ferritic stainless steel (Nippon Steel Standard YUS2
Using a stainless steel foil (made of 05SMI), a catalytic converter was manufactured in which a honeycomb body 3 as shown in FIG. 1 was formed and mounted on an outer cylinder 11 as shown in FIG.

The procedure is as follows: first, a thickness of 30 μm and a width of 106 m
Using two stainless steel foil coils, a flat foil 2 from one stainless steel foil coil, and a corrugated foil 1 manufactured by corrugating the other stainless steel foil coil,
After the flat foil and the corrugated foil are overlapped and wound to form a honeycomb body 3 having a large number of ventilation holes 4 formed in the axial direction, one end face on the exhaust gas entry side and an area 10 mm inward from the end face to 30 mm inside.
Was coated with aluminum by a low-temperature spraying method.

The manufactured honeycomb body 3 is subjected to a degree of vacuum (pressure).
Is heated at 930 ° C. for 1 hour in a vacuum furnace having an atmosphere in which the vapor pressure is 1.5 to 2.0 times the vapor pressure of aluminum to form an aluminum diffusion layer and further joins the flat foil 2 and the corrugated foil 1 For this purpose, a heat treatment was performed at 1220 ° C. for 30 minutes.

Although this low-temperature sprayed aluminum was not uniformly alloyed, it can be alloyed by diffusing Fe or Cr into aluminum by holding it at 930 ° C. in a vacuum furnace. By performing heat treatment at about 1000 ° C., aluminum is interdiffused without moving to the original place, and an alloy layer having a high Al concentration of 8 to 15% but close to the composition of the metal foil material is formed. The flat foil 2 and the corrugated foil 1 were simultaneously joined by diffusion bonding.

After manufacturing the honeycomb body 3 having a high Al concentration in the exhaust gas inlet side region in this way, activated alumina was coated on the entire surface of the honeycomb body 3 in contact with the exhaust gas, and platinum and palladium were supported.

Next, as shown in FIG. 2, a ring-shaped elastic support 7 is wrapped around the honeycomb body 3 and joined by electric resistance welding, and another ring-shaped elastic support 8 wrapped around the honeycomb support 3 is wound thereon. The protruding portion was joined to the outer cylinder 11 by brazing. Each elastic support was joined by electric resistance welding.

Here, the ring-shaped elastic support 7 joined to the honeycomb body 3 is divided into two semicircles. The portion was joined to the honeycomb body 3 by electric resistance welding.

Next, the ring-shaped elastic support 8 fixed to the outer cylinder 11 is superimposed on and wound around the ring-shaped elastic support 7 joined to the honeycomb body 3 and then inserted into the outer cylinder 11 to form a ring-shaped. Of the elastic support 8 was joined to the outer cylinder 11 by brazing.

The honeycomb body 3 is formed by laminating a flat foil having a thickness of 30 μm and a corrugated foil obtained by corrugating the flat foil and winding and joining them. The diameter is 86 mm, the length is 106 mm, and the cell density is 400 CPSI.
It is.

The outer cylinder 11 is made of Fe-19 wt% Cr-0.4
wt% Cu-0.4wt% Nb ferrite diameter stainless steel (made by Nippon Steel Standard YUS180) pipe, wall thickness 1.5
mm, an outer diameter of 105 mm, and a length of 238 mm were used.

The thus-manufactured honeycomb body 3 was constructed by incorporating the outer cylinder 11 into a catalytic converter,
It was installed in the middle of the exhaust pipe of a 0 cc gasoline engine, and a 900-cycle cold heat endurance test was performed under the condition that the temperature on the exhaust gas inlet side reached 950 ° C.

Further, the engine is completely stopped, and the entire catalytic converter is started from a state close to room temperature. The end of the honeycomb body 3 on the exhaust gas side, a position 20 mm from the center in the radial direction, Was measured with a thermocouple attached to the middle part in the longitudinal direction.

Further, a thermocouple is also attached to a substantially intermediate portion of the honeycomb body 3, and the engine is operated for 15 minutes under the condition that the temperature at the exhaust gas outlet side reaches 950 ° C., and then the engine is stopped. The temperature of Sample No. 3 was measured, and the state of damage to the honeycomb body 3 after the heat insulating effect and the durability test was investigated.

As a result, as shown in Table 3, the temperature of the end portion of the honeycomb body 3 on the exhaust gas outlet side was changed to the engine start 5
The temperature rose to 260 ° C. after the elapse of 0 second, and the surface temperature of the outer cylinder at that time was 35 ° C. The temperature of the intermediate portion of the honeycomb body 3 at the time of 15 minutes after the engine was stopped was 220 ° C.

On the other hand, the stainless steel foil and the outer cylinder of the same material as those of the first embodiment of the present invention were used, and the outer cylinder 11 and the honeycomb body 3 were directly joined by brazing without strengthening the end faces. In the conventional example in which diffusion bonding was performed by heating in a vacuum furnace at 1230 ° C. for 90 minutes, there was no heat insulating layer between the honeycomb body and the outer cylinder, so the diameter of the outer cylinder was smaller than that of the inventive example 1. Although the outer diameter is as small as 89 mmφ, the temperature of the end of the honeycomb body on the exhaust gas outlet side rises to 250 ° C. 50 seconds after the start of the engine, and the surface temperature of the outer cylinder at that time is 80 °.
° C. Further, the temperature of the intermediate portion of the honeycomb body at the time of 15 minutes after the engine was stopped was 120 ° C.

This result indicates that the honeycomb body 3 of Example 1 of the present invention was used.
Compared to the conventional case, the catalyst activation temperature is reached in a short time from the start of the engine, the temperature drop is small even when the engine is stopped, and the catalyst activation temperature is short in the case of restarting the engine. , Which means that the thermal efficiency is good.

Further, as compared with the conventional example, the surface temperature of the outer cylinder is as low as 35 ° C., and the heat insulating effect between the honeycomb body and the outer cylinder is good. Indicates that it is not inhibited. In addition, the sealing property between the ring-shaped elastic support 7 and the ring-shaped elastic support 8 was sufficiently ensured.

On the other hand, as a result of examining the damage state of the honeycomb body after the durability test, in Example 1 of the present invention, no displacement or damage (chip) between the flat foil and the corrugated foil was observed. On the other hand, in the case of the conventional example, the displacement between the flat foil and the corrugated foil and the damage due to the chipping of 2 ml in volume were recognized on the exhaust gas entry side end face of the honeycomb body.

Experimental Example 2 A catalytic converter was manufactured in substantially the same manner as in Example 1 of the present invention. The procedure is as follows: First, a flat foil made of stainless steel foil having a thickness of 30 μm and a width of 106 m,
The stainless steel foil is corrugated, and as shown in FIG. 3, the top 12 has a trapezoidal cross section having a flat portion of 0.3 mm. A corrugated foil of 70 degrees is manufactured, and the corrugated foil and the flat foil are stacked and wound to form a honeycomb body 3, and the end faces on both sides and an area 30 mm inward from the end face are coated with aluminum by low-temperature spraying. did. The axis of the honeycomb body 3 was inclined at about 45 degrees with respect to the spraying direction of the low-temperature spraying, and spraying was performed while rotating the honeycomb body 3 so that aluminum was easily attached to the contact portion between the flat foil and the corrugated foil.

Next, as shown in FIG. 2, a ring-shaped elastic support 7 is wound around the honeycomb body 3 with an aluminum foil 9 having a thickness of 20 μm interposed between the honeycomb body 3 and another one. One ring-shaped elastic support 8 was inserted between the outer cylinder 11 and aluminum having a thickness of 20 μm.
The ring-shaped elastic supports 7 and 8 each have 10
Since it has an overlap of about mm, it can be easily inserted into the outer cylinder 11 by squeezing it so that the overlap becomes slightly larger.

It is heated in a vacuum furnace at 900 ° C. for 30 minutes,
Further heating was performed at 1000 ° C. for 60 minutes. The Al concentration of the honeycomb body was clearly increased in the region 10 mm from the end face, while the average content of the original metal foil material was 5%, with the maximum being 20% and the minimum being 15%. % Has been reached.

In the area where aluminum was sprayed, the metal foil materials Fe and Cr were added to the aluminum at the contact portion between the flat foil and the corrugated foil.
Were diffused, and the flat foil and the corrugated foil were firmly diffusion bonded. Further, the ring-shaped elastic support 7 and the honeycomb body 3 and the ring-shaped elastic support 8 and the outer cylinder 11 diffuse Fe and Cr in the metal foil material (material) into the aluminum foil interposed therebetween. By doing so, diffusion bonding was performed. Thereafter, activated alumina was coated on the entire surface of the honeycomb body 3 to support platinum and palladium.

Although not performed in Experimental Example 1, alumina was sprayed in advance on the contact surface between the ring-shaped elastic support 8 joined to the outer cylinder 11 and the ring-shaped elastic support 7 joined to the honeycomb body 3. To improve heat insulation. The size of the honeycomb body 3 and the size of the outer cylinder 11 are the same as those in the experimental example 1.

The obtained catalytic converter was mounted in the middle of the exhaust pipe of a 2000 cc gasoline engine, and the same heat insulation effect as in Experimental Example 1 and the state of damage to the honeycomb body after the durability test were examined. As a result, as shown in Table 3, the temperature of the end portion of the honeycomb body 3 on the exhaust gas outlet side was changed to the engine start 50%.
After a lapse of seconds, the temperature rose to 270 ° C., and the surface temperature of the outer cylinder 11 at that time was 28 ° C. The temperature of the intermediate portion of the honeycomb body 3 at the time of 15 minutes after the engine was stopped was 250 ° C.

This result indicates that the honeycomb body 3 of the present invention example 2 was formed by spraying alumina in advance between the ring-shaped elastic support 7 and the ring-shaped elastic support 8 to enhance the heat insulating property. Compared to the case of the invention example 1, the catalyst activation temperature is reached in a short time from the start of the engine, the temperature drop is small even when the engine is stopped, and the catalyst activation temperature is quickly reached even when the engine is restarted. Means that the thermal efficiency is even better.

The temperature of the surface of the outer cylinder 11 is as low as 28 ° C. as compared with the case of the first embodiment of the present invention, and the heat insulating effect between the honeycomb body 3 and the outer cylinder 11 is further improved. This indicates that the degree of inhibition of the temperature rise of the honeycomb body 3 is further reduced. In addition, the sealing property between the ring-shaped elastic support 7 and the ring-shaped elastic support 8 was sufficiently ensured.

On the other hand, as a result of examining the state of damage of the honeycomb body after the durability test, in Example 2 of the present invention, no displacement or damage between the flat foil and the corrugated foil was observed.

[0071]

According to the present invention, the durability of the honeycomb body is improved at the same time as the durability of the honeycomb body is improved by reinforcing the element improving the high-temperature oxidation resistance at least in the exhaust gas entry side of the honeycomb body constituting the metal catalytic converter. In addition, the corrugated foil and the flat foil can be joined by the metal-mediated diffusion joining, so that the productivity can be improved and the manufacturing cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a three-dimensional explanatory view showing an example of element (Al) reinforcement for improving high-temperature oxidation resistance in a honeycomb body used in an embodiment of the present invention.

FIG. 2 is a cross-sectional explanatory view showing an example of a mounting structure between a honeycomb body and an outer cylinder in the embodiment of the present invention.

FIG. 3 is an explanatory view showing an example of a top cross-sectional shape of a corrugated foil forming a honeycomb body and a contact angle between the corrugated foil and a flat foil. FIG. Indicates that
(B) shows an example of the shape of a corrugated foil having a sine-curve top cross section, which is generally used conventionally.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Corrugated foil 2 Flat foil 3 Honeycomb body 4 Vent hole 5 Exhaust gas 6 Aluminum sprayed layer 7 Ring-shaped elastic support body (joined with honeycomb body) 8 Ring-shaped elastic support body (joined with outer cylinder) 9 Aluminum foil 10 Aluminum concentration 11 The outer cylinder 12 The top has a trapezoidal cross section 13 The top has a sine curve cross section

Claims (5)

[Claims] 1. A flat body made of a metal foil material and a corrugated foil are wound on top of one another to mount a honeycomb body having a large number of ventilation holes formed in an axial direction, and installed in an exhaust gas passage to purify the exhaust gas. In the converter of the above, in the metal foil material forming the honeycomb body at least 0.2 mm or more inside from the end face on the exhaust gas input side, heat resistance, metal that improves oxidation resistance is an average of the entire metal foil material A cylindrical metal catalytic converter characterized in that the catalyst is supported on the surface of the inside of the air hole of the honeycomb body while the contact portion between the flatbed and the corrugated foil is integrated by containing more than the content. . 2. A metal foil for improving heat resistance and oxidation resistance is coated on a metal foil material by low-temperature spraying in a region not less than 0.2 mm from the end face of the honeycomb body, and at a temperature not lower than the melting point of the metal and Heat treatment is performed in a vacuum furnace having an atmosphere in which the degree of vacuum (pressure) is equal to or higher than the vapor pressure of the metal, and the contact portions of the flat foil and the corrugated foil constituting the honeycomb body are integrated by mutual diffusion of the metal. The metallic catalytic converter according to claim 1, wherein: 3. A low-temperature spraying of a metal for improving heat resistance and oxidation resistance onto a region of a metal foil material 0.2 mm or more from a side end of the honeycomb body before or during the forming of the honeycomb body. The honeycomb body obtained by coating and molding is heated in a vacuum furnace having an atmosphere in which the temperature is equal to or higher than the melting point of the metal and the degree of vacuum (pressure) is equal to or higher than the vapor pressure of the metal. 2. The metallic catalytic converter according to claim 1, wherein the contact portions of the flat foil and the corrugated foil constituting the honeycomb body are integrated by mutual diffusion of the catalytic converter. 4. The metallic catalytic converter according to claim 1, wherein the metal which improves heat resistance and oxidation resistance is aluminum or an aluminum alloy. 5. A flat foil made of a metal foil material and a corrugated foil are superposed and wound to form a honeycomb body having a large number of ventilation holes in an axial direction. ,
Using a corrugated foil with a trapezoidal cross section having a flat portion of 0.5 mm or less, and forming a honeycomb body with a contact angle between the corrugated foil and the flat foil of 40 degrees or more, housed in an outer cylinder or not housed At least 0.2 mm from the end face on the exhaust gas entry side
In the region up to the inner side of not less than 0.2 mm, aluminum or an aluminum alloy is sprayed at a low temperature and then heat-treated in a vacuum furnace to cause mutual diffusion between the metal foil materials coated with the aluminum or aluminum alloy.
Increase the aluminum concentration of the metal foil material in the area up to the inner side of mm or more to the average aluminum concentration of the entire metal foil material, and join the flat foil and corrugated foil in the area up to 0.2 mm or more inside from the end face of the honeycomb body A method of manufacturing a metal catalytic converter.