DE112012000415T5 - Exhaust pipe and manufacturing method for an exhaust pipe - Google Patents

Abstract

The exhaust pipe of the present invention is an exhaust pipe having a substrate made of metal and a surface coating formed on the surface of the substrate containing a non-crystalline inorganic material, and characterized in that when there are five rectangular portions are determined by cutting a section of the surface coating in a vertical direction to the thickness direction of the exhaust pipe in five rectangular sections with a 500 times enlarged photograph of a sectional area parallel to the thickness direction of the exhaust pipe such that its thickness after cutting 1/5 of the thickness the surface coating is at least one rectangular section as the pore concentration section in which, of all the pores present in the entire surface coating, there are 30% or more of the pores in area, the rectangular section corresponding to the pore concentration Among the five rectangle sections, the middle rectangle section or one or two rectangle sections adjacent to the middle rectangle section and the pores present in the surface coating comprise independent pores and the independent pores do not comprise the exterior connect the exhaust pipe and the surface of the substrate.

Description

Technical area

The present invention relates to exhaust pipes and a manufacturing method for exhaust pipes.

General state of the art

For treating harmful substances such as harmful gases, etc. contained in the exhaust gas of an engine, a catalyst is provided along the exhaust passage.

In order to enhance the purifying effect for removing harmful substances of the catalyst, the temperature of the exhaust gas or the exhaust pipe, etc., in which the exhaust gas flows must be maintained at a temperature appropriate for the catalytic activation (hereinafter also referred to as "catalyst activation temperature"). However, when the engine is operating at high speed, temperatures temporarily occur at which the exhaust gas becomes more than 1,000 ° C hot, exceeding the upper limit of the catalyst activation temperature. This complicates the effective purification of the exhaust gas and leads to the problem of deterioration of the catalyst.

Therefore, it is required that, for example, when operating a vehicle engine at a high speed, the exhaust pipe connected to the vehicle engine discharges the heat of the exhaust gas flowing through the exhaust passage to the outside.

In Patent Laid-Open Publication 2009-133214, for example, there is disclosed an exhaust pipe to which a surface coating comprising a crystalline inorganic material and a non-crystalline inorganic material is formed on the outer peripheral surface of a metal tubular substrate.

In the prior art exhaust pipe of Patent Publication 2009-133214, the thickness of the non-crystalline inorganic material located closer to the outer peripheral surface than the crystalline inorganic material is 20 μm or less, and its heat dissipation is excellent.

Documents of the prior art

patents

• Patent Document 1: Patent Publication 2009-133214

Brief description of the invention

Object of the present invention

In prior art emission control systems, the temperature of the catalyst at engine startup is lower than the catalyst activation temperature. The catalyst is heated by the incoming hot exhaust gas, so that after a certain time after starting the engine, the catalyst temperature reaches the catalytic activation temperature. In order to shorten the time until the catalytic activation temperature is reached, in recent years, exhaust gas purification systems having a mechanism for increasing the catalyst temperature are being investigated, with the catalyst being directly supplied with power. In the exhaust gas piping used in the exhaust gas purifying system in which the catalyst is directly supplied with power, high insulation performance is required to prevent problems with ground faults, etc., because the electrodes touch or abut each other.

The inventors have tried to make the surface coating thicker in an exhaust pipe having a substrate and a surface coating used as an exhaust pipe to increase the insulation performance. Although the insulation performance was increased by making the surface coating thicker, cracks occurred in a high heat environment such as sudden temperature rises and falls of 20 ° C / second or more, thereby damaging the surface coating.

The present invention has been made to solve these problems, and its object is to provide an exhaust pipe having excellent low-temperature holding performance and excellent heat dissipation performance at high temperatures, which can ensure high insulation performance when used as an exhaust pipe.

Means for solving the problem

The inventors have dealt thoroughly with methods in which no surface coating damage occurs even if the surface coating is made thicker for increasing the insulating performance, and arrived at the present invention by recognizing that by determining the position of pores in the substrate Inside the surface coating, the spread of cracks can be avoided and damage to the surface coating can be prevented.

An exhaust pipe according to claim 1 therefore has a substrate made of metal and
a surface coating formed on the surface of the substrate containing a non-crystalline inorganic material, and characterized in that
there are pores in the surface coating,
when five rectangular sections are determined by cutting a section of the surface coating in vertical direction to the thickness direction of the exhaust pipe into five rectangular sections in a section 500 times enlarged by an electron microscope 500 times a sectional area parallel to the thickness direction of the exhaust pipe such that its thickness after cutting Is 1/5 of the thickness of the surface coating,
at least one rectangular section is present as a pore concentration section, in which 30% or more of the pores of all the pores present in the entire surface coating are present,
the rectangle portion constituting the pore concentration portion is one of the five rectangle portions of the middle rectangle portion or one or two rectangle portions adjacent to the middle rectangle portion
the pores present in the surface coating comprise independent pores and the independent pores do not interconnect the exterior of the exhaust conduit and the surface of the substrate.

In the exhaust pipe according to claim 1, at least one rectangular section as a pore concentration section is provided on the surface coating in which 30% or more of the pores are present in area of all pores existing in the entire surface coating.

It is believed that cracks that form in the surface coating due to exposure to heat first form on the surface of the surface coating and then spread in the thickness direction of the surface coating toward the substrate.

When a crack that has formed in the surface coating spreads and encounters an independent pore, the crack is prevented from spreading beyond the independent pore. Thus, if at least one of the rectangle sections in the surface coating is a pore concentration section, cracks eventually formed on the surface of the surface coating readily encounter an independent pore in the pore concentration section, preventing the crack from propagating beyond the pore concentration section to the substrate ,

The pores also include independent pores, and the independent pores do not connect the exterior of the exhaust conduit and the surface of the substrate to each other. Since the independent pores do not bond the exterior of the exhaust pipe and the surface of the substrate, it does not happen that a crack that hits the pore will penetrate the surface coating.

Thus, by providing a pore concentration portion in the surface coating and the independent pores of the surface coating not bonding the exterior of the exhaust pipe and the surface of the substrate, cracking of the surface coating may occur even if cracks are generated in the surface coating by heat Pore concentration section can be prevented.

Thus, damage to the surface coating can be prevented. For this reason, the exhaust pipe can ensure a high insulation performance.

In the exhaust pipe according to claim 2, the pore ratio (B / A) of the pore concentration section, which is the ratio between the area occupied by the pores (B) and the area (A) of the rectangular section, is 0.02 or more.

When the pore ratio is 0.02 or more, enough pores exist in the pore concentration portion to prevent cracks from spreading, since the probability of a crack hitting a pore increases. This is preferred, because the propagation of cracks can thus be prevented particularly reliably.

In the exhaust pipe according to claim 3, the surface coating further contains a crystalline inorganic material.

Crystalline inorganic material tends to have a high infrared light emission rate. When the surface coating contains a crystalline inorganic material, infrared light is radiated through the crystalline inorganic material so that the infrared light emission rate of the surface coating increases, whereby an exhaust pipe having excellent heat dissipation performance at a high temperature can be formed.

In the exhaust pipe according to claim 4, the surface coating comprises a layer of non-crystalline inorganic material containing a non-crystalline inorganic material, and a mixed layer containing a non-crystalline inorganic material and a crystalline inorganic material, wherein the pore concentration section of the Contains interface between the layer of non-crystalline inorganic material and the mixed layer.

In forming the surface coating, a roughened surface is formed on the surface of the lower layer (the layer located closer to the substrate), and on the roughened surface, the upper layer (made of a material other than the lower layer) is formed, whereby the pore concentration portion at the Position is formed, which contains the interface between the lower layer and the upper layer.

That is, in the exhaust pipe according to claim 4, the pore concentration portion is formed at the position defining the interface between the lower layer (the mixed layer or the non-crystalline inorganic material layer) and the upper layer (the non-crystalline inorganic material layer or the mixed layer). When the pore concentration section is formed at this position, excellent thermal shock resistance is exhibited because the pores in the pore concentration section alleviate the thermal stress occurring between the upper and lower layers.

In the exhaust pipe according to claim 5, the crystalline inorganic material contains at least one of manganese, iron, copper, cobalt, chromium and aluminum.

Since oxides have a high infrared radiation rate, the radiation of the surface coating can be increased. In particular, the use of an oxide of aluminum contributes to the insulation performance of the exhaust pipe.

In the exhaust pipe according to claim 6, the number of pore concentration sections is one per area of the substrate, and the rectangular section constituting the pore concentration section is the middle rectangle section of the five rectangular sections.

The thicker the surface coating, the stronger the thermal shock that acts on the surface coating.

When the pore concentration portion is the center rectangle portion of the five rectangle portions, the pore concentration portion is at the position where the surface coating is divided into two in the thickness direction.

When the pore concentration section is at the position where the surface coating is divided into two in the thickness direction, the surface coating is divided by the pore concentration section into two parts of equal thickness. The amount of thermal shock of the surface coating then corresponds to that which would be present in the case of a thin surface coating, so that damage to the surface coating can be effectively prevented.

In the exhaust pipe according to claim 7, the number of pore concentration sections is two per area of the substrate, and the rectangular sections constituting the pore concentration sections are the two rectangular sections adjacent to the middle rectangle section of the five rectangular sections.

In the exhaust pipe according to claim 7, the surface coating is divided by the two pore concentration sections into three parts each with 1/3 of the total thickness. As with the exhaust pipe according to claim 6, the thermal shock of the surface coating is equivalent to that which would be present in the case of a thin surface coating, so that damage to the surface coating can be effectively prevented.

In the exhaust pipe according to claim 8, the thickness of the surface coating is 25 to 1,000 μm.

If the thickness of the surface coating is less than 25 μm, sufficient insulation performance can not be achieved when used as an exhaust pipe. On the other hand, if the thickness of the surface coating is more than 1,000 μm, the amount of heat shock applied to the surface coating increases, so that the surface coating is more likely to be damaged.

In the exhaust pipe according to claim 9, the thermal conductivity of the surface coating at room temperature is 0.1 to 2 W / m · K.

If the thermal conductivity of the surface coating at room temperature is less than 0.1 W / m · K, there is insufficient heat dissipation of the exhaust pipe in the high temperature region, so that the heat of the exhaust gas flowing through the exhaust pipe is difficult to dissipate to the outside.

On the other hand, if the thermal conductivity of the surface coating at room temperature is more than 2 W / m · K, there is insufficient heat-retaining ability in the low-temperature region, so that it takes longer for the temperature of the catalyst to reach the catalytic activation temperature.

In the exhaust pipe according to claim 10, the volume resistivity of the exhaust pipe is 10 ⁷ to 10 ¹⁴ Ωm.

If the volume resistivity of the flue gas line is less than 10 ⁷ Ωm, there is a risk of an earth fault in the flue gas line.

In the exhaust pipe according to claim 11, the surface coating is formed by applying a base composition for forming the surface coating a plurality of times.

When the surface coating is formed by applying a primer composition for forming the surface coating a plurality of times, in the case that a surface coating formed by a single coating process has a connection pore connecting the outside of the exhaust pipe and the surface of the substrate , the pore in question are covered during the next coating process. In this way, it can be ensured with certainty that there are pores in the surface coating which extend through the entire surface coating. When there are no pores extending through the entire surface coating, moisture does not reach the substrate surface, so that an exhaust pipe in which the metal substrate does not rust can be obtained.

In the exhaust pipe according to claim 12, the surface coating on a blind pore, wherein a part is in communication with the exterior of the exhaust pipe.

Also, the blind pore, like an independent pore, is a pore that does not connect the exterior of the exhaust conduit to the surface of the substrate. Thus, even if the surface coating has a blind pore, cracks can be prevented from spreading further from the interface between the non-crystalline inorganic material layer and the mixed layer toward the substrate.

An exhaust pipe according to claim 13 comprises a substrate of metal and
a surface coating formed on the surface of the substrate containing a non-crystalline inorganic material, and characterized in that
the surface coating comprises a layer of non-crystalline inorganic material containing a non-crystalline inorganic material and a mixed layer containing a non-crystalline inorganic material and a crystalline inorganic material,
the surface coating has independent pores, and
the independent pores do not interconnect the exterior of the exhaust conduit and the surface of the substrate and are localized in the interface portion between the non-crystalline material layer and the mixed layer.

It is believed that cracks that form in the surface coating due to exposure to heat first form on the surface of the surface coating and then spread in the thickness direction of the surface coating toward the substrate.

When a crack that has formed in the surface coating spreads and encounters an independent pore, the crack is prevented from spreading beyond the independent pore.

If the independent pores do not connect the outside of the exhaust pipe and the surface of the substrate with each other and are localized in the interface portion between the non-crystalline material layer and the mixed layer, in case a crack is generated in the surface of the surface coating, it will hit easily to an independent pore which is localized in the interface portion between the layer of non-crystalline material and the mixed layer, therefore, the crack can be prevented from extending beyond the interface portion between the layer of non-crystalline material and the mixture layer to the substrate spreads.

Thus, damage to the surface coating can be prevented. For this reason, the exhaust pipe can ensure a high insulation performance.

In the exhaust pipe according to claim 14, the surface coating on a blind pore, wherein a part is in communication with the exterior of the exhaust pipe. Also, the blind pore, like an independent pore, is a pore that does not connect the exterior of the exhaust conduit to the surface of the substrate. Thus, even if the surface coating has a blind pore, cracks can be prevented from spreading further from the interface between the non-crystalline inorganic material layer and the mixed layer toward the substrate.

A method according to claim 15 for producing an exhaust pipe comprises the following steps:
Preparing a metal substrate,
Preparing a basecoat composition for a surface coating, and
Applying the base material composition for forming the surface coating on the metal substrate and forming the surface coating by firing, and is characterized in that
in the step of preparing the basecoat composition for forming the surface coating, a basecoat composition for a non-crystalline inorganic material layer containing a non-crystalline inorganic material, and / or a composite basecoat composition comprising a non-crystalline inorganic material and a crystalline inorganic material is prepared, and a pore-forming material is mixed with the base composition for a layer of non-crystalline inorganic material or the base material composition for a mixed layer, and a base material composition for forming a pore concentration portion is prepared;
in the step of forming the surface coating, the base composition is applied at least once to form a pore concentration portion, is fired to form pores in the surface coating, and the base composition for a layer of non-crystalline inorganic material or the composite composition for a mixed layer is applied at least once.

In the production method, a pore-forming material is mixed with the base material composition for a layer of non-crystalline inorganic material or the base material composition for a mixed layer to prepare a base composition for forming a pore concentration section, and the base composition for forming a pore concentration section is coated and fired.

Since pores are formed by firing at the position of the pore-forming material, an exhaust pipe having a pore concentration portion at a desired position of the surface coating can be manufactured.

A method according to claim 16 for producing an exhaust pipe
Preparing a metal substrate,
Preparing a basecoat composition for a surface coating, and
applying the base composition several times to form the surface coating on the metal substrate and forming the surface coating by firing, and characterized in that:
in the step of forming the surface coating, a step of forming a lower layer of the surface coating is carried out, wherein the application of the base composition for forming the surface coating and the firing are performed at least once;
the surface of the lower layer of the surface coating is roughened, and
by forming the base composition for forming the surface coating on the lower layer of the surface coating and baking, an upper layer of the surface coating is formed, and at the same time pores are formed between the lower layer of the surface coating and the upper layer of the surface coating.

In the manufacturing process, the surface of the lower layer of the surface coating is roughened. When the primer composition for forming the surface coating is applied to the roughened surface of the lower layer of the surface coating, not all of the recesses on the rough surface of the lower layer of the surface coating are filled with the primer composition for forming the surface coating; instead, air spaces are left between the recesses on the rough surface of the lower layer of the surface coating and the upper layer of the base material composition for forming the surface coating. After firing, the air spaces become pores so that independent pores are formed locally between the lower layer of the surface coating and the upper layer. Thus, it is possible to produce an exhaust pipe having a pore concentration portion at a desired position of the surface coating.

Brief description of the figures

1 FIG. 10 is a sectional view schematically showing an example of a sectional surface of an exhaust pipe according to a first embodiment of the first invention. FIG.

2 (a) is a photograph with an electron microscope showing a part of a sectional area of an exhaust pipe of the first embodiment of the first invention, and 2 B) is a receptacle that out the rectangle section and the pores 2 (a) shows.

3 (a) . 3 (b) . 3 (c) and 3 (d) 11 are sectional views schematically showing an example of a sectional surface of another exhaust pipe according to the first embodiment of the first invention.

4 FIG. 10 is a sectional view schematically showing an example of a sectional surface of another exhaust pipe according to the first embodiment of the first invention. FIG.

5 (a) . 5 (b) and 5 (c) 11 are sectional views schematically showing an example of a sectional surface of another exhaust pipe according to the first embodiment of the first invention.

6 (a) and 6 (b) 11 are sectional views schematically showing an example of a sectional surface of an exhaust pipe according to a second embodiment of the first invention.

7 (a) and 7 (b) 13 are sectional views schematically showing an example of a sectional surface of an exhaust pipe according to a third embodiment of the first invention.

8 (a) . 8 (b) and 8 (c) 11 are sectional views schematically showing a part of a step for manufacturing an exhaust pipe according to the third embodiment of the first invention.

9 (a) and 9 (b) 11 are sectional views schematically showing an example of a sectional surface of an exhaust pipe according to a fourth embodiment of the first invention.

10 FIG. 10 is a sectional view schematically showing an example of a sectional surface of an exhaust pipe according to a fifth embodiment of the first invention. FIG.

11 FIG. 10 is a sectional view schematically showing an example of a sectional surface of an exhaust pipe according to a sixth embodiment of the second invention. FIG.

12 is a sectional view made for the exhaust pipe 11 shows the case of a surface coating with five rectangular sections.

13 FIG. 10 is a sectional view schematically showing an example of a sectional surface of an exhaust pipe according to a seventh embodiment of the second invention. FIG.

14 FIG. 10 is a sectional view schematically showing an example of a sectional surface of an exhaust pipe according to an eighth embodiment of the second invention. FIG.

Embodiments of the invention

First embodiment

In the following, a first embodiment will be described with reference to the figures, which is an embodiment of an exhaust pipe of the first invention.

The exhaust pipe of the first invention is an exhaust pipe having a substrate made of metal and a surface coating formed on the surface of the substrate, which contains a non-crystalline inorganic material, and which is characterized in that, if five rectangular sections are determined by cutting a section of the surface coating in a vertical direction to the thickness direction of the exhaust pipe in five rectangular sections with a 500 times enlarged photograph of a sectional area parallel to the thickness direction of the exhaust pipe such that its thickness after cutting 1/5 of the thickness the surface coating is at least one rectangular section as a pore concentration section in which, of all the pores present in the entire surface coating, there are 30% or more of the pores in area, the rectangular section corresponding to the pore concentration section, among the five rectangle sections, the middle rectangle section or one or two rectangle sections adjoining the central rectangle section and the pores present in the surface coating comprise independent pores and the independent pores do not comprise the exterior connect the exhaust pipe and the surface of the substrate.

1 FIG. 10 is a sectional view schematically showing an example of a sectional surface of an exhaust pipe according to a first embodiment of the first invention. FIG.

The exhaust pipe off 1 FIG. 12 is an example of an exhaust pipe of the present embodiment and has a substrate. FIG 10 made of metal and a surface coating 20 on that on the surface of the substrate 10 is trained.

As material of the substrate 10 For example, metals such as stainless steel, steel, iron, copper or nickel alloys such as Inconel, Hastelloy, Invar, etc. may be mentioned. These metal materials have a high thermal conductivity and therefore contribute to increase the heat dissipation performance of the exhaust pipe.

Regarding the shape of the substrate 10 There are no particular restrictions, but it is preferably cylindrical because the shape of exhaust pipes is normally cylindrical.

The surface coating 20 has a layer of non-crystalline inorganic material 21 containing a non-crystalline inorganic material 31 contains, and a mixed layer 22 ( 22a . 22b ), which is a non-crystalline inorganic material 31 and a crystalline inorganic material 32 contains.

The surface coating 20 is constructed in three layers, this construction concrete, starting from the substrate 10 , the mixed layer 22b , the layer of non-crystalline inorganic material 21 and the mixed layer 22a comprises and is thus constructed of three superimposed layers whose thickness in each case 1/3 of the thickness of the surface coating 20 is.

Preferably, the layer is of non-crystalline inorganic material 21 a layer called non-crystalline inorganic material 31 contains a low melting point glass whose softening point is from 300 to 1,000 ° C. With regard to the type of glass with low enamel, there is none special limitation and barium glass, boron glass, strontium glass, aluminum silicate glass, soda lead glass, soda-barium glass, etc. may be mentioned.

These types of glass can be used singly or as a mixture of two or more types of glass.

Since the softening temperature of the low melting point glass is 300 to 1,000 ° C, the surface coating after melting and coating on the outer peripheral surface of the substrate can be easily and firmly formed on the outer peripheral surface of the substrate by a subsequent burning treatment.

When the non-crystalline inorganic material is a low melting point glass, its softening point is preferably 300 to 1,000 ° C.

When the softening point of the low melting point glass is lower than 300 ° C, the low melting point glass slightly softens when the exhaust pipe is used, so that foreign matters can adhere to the surface coating. On the other hand, if the softening point of the low melting point glass is over 1,000 ° C, the substrate may easily deteriorate in the heat treatment in forming the surface coating.

As concrete examples of the low melting point glass, there can be exemplified SiO ₂ -B ₂ O ₃ -ZnO glass, SiO ₂ -B ₂ O ₃ -Bi ₂ O ₃ glass, SiO ₂ -Pb glass, SiO ₂ -PbO -B ₂ O ₃ glass, SiO ₂ -B ₂ O ₃ -PbO glass, B ₂ O ₃ -ZnO-PbO glass, B ₂ O ₃ -ZnO-Bi ₂ O ₃ glass, B ₂ O ₃ - Call Bi ₂ O ₃ glass, B ₂ O ₃ -ZnO gas and BaO-SiO ₂ glass.

The softening point can be according to that of the Japanese Industrial Standard JIS R 3103-1: 2001 determined method, for example, with an automatic measuring device for the softening and deformation point of glass SSPM-31 manufacturer Opt, Inc.

The non-crystalline inorganic material may comprise a single type of low melting point glass or several types of low melting point glass.

The mixed layer 22 is a layer containing the non-crystalline inorganic material 31 contained in the layer of non-crystalline inorganic material 21 is contained, and also the crystalline inorganic material 32 contains. As a crystalline inorganic material 32 Preferably, an oxide of a transition metal is used, and in particular inorganic particles of at least one oxide from the group manganese, iron, copper, cobalt, chromium and aluminum.

These inorganic particles of oxides may be used singly or as a mixture of two or more.

These oxides of transition metals have a high rate of infrared radiation, thus contributing to increasing the heat dissipation performance of the exhaust pipe.

In particular, the use of an oxide of aluminum contributes to the insulation performance of the exhaust pipe.

In the surface coating 20 the exhaust pipe 1 according to the present embodiment are pores 33 in front.

The pores in surface coating 20 the exhaust pipe 1 according to the present embodiment are independent pores. Independent pores are located inside the surface coating 20 and are not exposed on the surface of the surface coating.

An independent pore is also a pore that does not connect the exterior of the exhaust pipe to the surface of the substrate.

In the surface coating 20 the exhaust pipe 1 According to the present embodiment, there is a pore concentration section 23 in front.

In the following, a method for determining the pore concentration section will be described with reference to the figures.

In determining the pore concentration portion, a 500-times magnified electron micrograph of a sectional area parallel to the thickness direction of the exhaust pipe is prepared, and a portion of the surface coating is cut in vertical direction to the thickness direction of the exhaust pipe into five rectangular sections such that their thickness after cutting is 1/5 of the thickness of the Surface coating is.

In 1 are the five rectangular sections with 20A . 20B . 20C . 20D and 20E designated.

Then the area of the pores 33 throughout the surface coating 20 are present, and that rectangular section at which 30% or more of the pores of the total area of the pores 33 throughout the surface coating 20 are present, is determined as pore concentration section.

At the exhaust pipe 1 out 1 is the rectangle section 20C the pore concentration section 23 ,

The pore concentration section 23 is a part of the layer of non-crystalline inorganic material 21 ,

In parts, not the pore concentration section 23 are, can pores 33 However, this need not be done.

2 (a) is a photograph with an electron microscope showing a part of a sectional area of an exhaust pipe of the first embodiment of the first invention, and 2 B) is a receptacle that out the rectangle section and the pores 2 (a) shows.

The acceleration voltage during the recordings off 2 (a) and 2 B) is 10.0 kV and the magnification is 500 times, and the recording area (the width of the recording) is 250 microns.

The on the shots off 2 (a) and 2 B) surface coating shown 20 the exhaust pipe has a structure starting from the substrate 10 a layer of non-crystalline inorganic material, a mixed layer and a layer of non-crystalline inorganic material are laminated one on top of the other.

The boundary lines between the layers can be in the shots 2 (a) and 2 B) do not recognize, but the thickness of the individual layers is about 25 microns.

For determining the pore concentration portion, a portion of the surface coating is cut in the vertical direction to the thickness direction of the exhaust pipe in five rectangular sections on the sectional recording that its thickness after cutting is 1/5 of the thickness of the surface coating.

The cutting takes place on the basis of the thickness of the surface coating from the surface of the surface coating to the surface of the substrate. The thus cut rectangular pieces are determined as rectangular sections.

When determining the position of the surface of the surface coating 20 (Starting point of the cutting process), in the case where the surface has irregularities, the deepest part of the surface coating 20 as a surface. The position of the surface of the surface coating 20 is in 2 B) shown with a dashed line.

When recording off 2 B) lie on the surface of the surface coating 20 no noticeable irregularities.

In determining the position of the surface of the substrate (end point of the cutting operation), in the case where the surface of the substrate has irregularities, the deepest part of the substrate is considered as the surface. The position of the surface of the substrate is in 2 B) shown with a dotted line.

When recording off 2 B) be in the procedure described above of the surface of the surface coating 20 starting from the substrate, five rectangular sections with the reference numerals A to E determined.

After the rectangle sections have been determined in this manner, the area of the pores present in the entire surface coating is determined, and the area of the pores present in the individual right-angled sections is determined in relation to the area of the pores present in the entire surface coating ,

In determining the area of the pores, pores present in the surface coating are determined.

In the present specification, a pore is considered a pore when it has a pore diameter of 5 μm or more on the sectional image with the electron microscope. The pore diameter, in case the pore is round, is the pore radius.

If the pore is not round, the maximum length reached when pulling a straight line through the pore is pore diameter.

In the recording off 2 B) the pores assessed as pores are represented by circling.

When calculating the pore area, only the area of the circled pores (the pores determined as pores) is considered.

After the pores present in the surface coating have been determined, the area of the pores in the surface coating is added, resulting in the total area of the pores in the surface coating.

Next, the area of all the pores in the individual rectangle sections is added, whereby the area of the pores present in the rectangular section is determined for each rectangular section.

Next, for each rectangular section, the ratio of the area of the pores present in the rectangular section to the total area of the pores in the surface coating is determined, the total area of the pores in the surface coating being 100%.

2 B) shows for the individual rectangular sections A to E, the ratio of the area of the pores present in the rectangular section to the total area of the pores in the surface coating.

In rectangular section C, the ratio is 73.8% and is thus above 30%, which is why the rectangular section C as pore concentration section (pore concentration section 32 ) is determined.

The ratio in the other rectangular sections A, B, D and E are each less than 30%, which is why they are not pore concentration sections.

In the present embodiment, the pore ratio (B / A) of the pore concentration section, which is the ratio between the area occupied by the pores (B) and the area (A) of the rectangular section, is 0.02 or more.

The pore ratio is determined by determining the area (A) of the rectangular section, determining the area of the pores present in the rectangular section, and then determining the ratio thereof (B / A).

The pore ratio of the rectangular section C from 2 B) is 0.27.

When recording off 2 B) if only the rectangular section C is a pore concentration section, then only one pore concentration section is present.

If, when counting the pore concentration sections in the surface coating, two adjacent rectangular sections are pore concentration sections, this is considered to be a pore concentration section.

If there is a rectangular section between pore concentration sections, which is not a pore concentration section, then they are considered separate pore concentration sections, and thus there are two pore concentration sections.

The thickness of the surface coating in the exhaust pipe of the present embodiment is preferably between 25 and 1,000 μm.

If the thickness of the surface coating is less than 25 μm, sufficient insulation performance can not be achieved when used as an exhaust pipe. On the other hand, if the thickness of the surface coating is more than 1,000 μm, the amount of heat shock applied to the surface coating increases, so that the surface coating is more likely to be damaged.

The thermal conductivity of the surface coating at room temperature (25 ° C) is preferably 0.1 to 2 W / m · K.

If the thermal conductivity of the surface coating at room temperature is less than 0.1 W / m · K, there is insufficient heat dissipation of the exhaust pipe in the high temperature region, so that the heat of the exhaust gas flowing through the exhaust pipe is difficult to dissipate to the outside.

On the other hand, if the thermal conductivity of the surface coating at room temperature is more than 2 W / m · K, there is insufficient heat-retaining ability in the low-temperature region, so that it takes longer for the temperature of the catalyst to reach the catalytic activation temperature.

The thermal conductivity of the surface coating at room temperature can be measured by the laser flash method.

The radiation rate of the surface coating at room temperature (25 ° C) and a wavelength of 1 to 15 μm is preferably 0.6 or more. If the radiation rate of the surface coating is less than 0.6, there is insufficient heat dissipation of the exhaust pipe in the high temperature region, so that the heat of the exhaust gas flowing through the exhaust pipe is difficult to discharge to the outside.

The irradiation rate of the surface coating at room temperature (25 ° C) and a wavelength of 1 to 15 μm is preferably 0.99 or less. The reason is that it is difficult to achieve a surface coating radiation rate above 0.99.

The positions for obtaining the electron micrograph of the sectional area parallel to the thickness direction of the exhaust pipe at 500 magnifications are a longitudinal center point on the exhaust pipe, a point at 1/3 of the longitudinal extent and a point at 2/3 of the longitudinal extent of the exhaust pipe.

When the surface coating is formed only on a part of the substrate, the part on which the surface coating is formed is the center point of this part, a point at 1/3 of the longitudinal extent and a point at 2/3 of the longitudinal extent thereof Part.

An exhaust pipe, which meets the conditions prescribed by the first invention at one of the three measuring points, is considered an exhaust pipe of the first invention.

3 (a) . 3 (b) . 3 (c) and 3 (d) 11 are sectional views schematically showing an example of a sectional surface of another exhaust pipe according to the first embodiment of the first invention.

At the exhaust pipe 50 out 3 (a) indicates the surface coating 20 a three-layer construction on. The arrangement of the mixed layer and the non-crystalline inorganic material layer is inverse to the arrangement of the mixed layer and the non-crystalline inorganic material layer of the exhaust pipe 1 out 1 ,

Specifically, this construction comprises starting from the substrate 10 , the layer of non-crystalline inorganic material 21b , the mixed layer 22b and the layer of non-crystalline inorganic material 21a is and thus constructed of three superimposed layers whose thickness in each case 1/3 of the thickness of the surface coating 20 is.

At the exhaust pipe 50 out 3 (a) is the pore concentration section 23 in the mixed layer 22 that is the middle layer.

In an exhaust pipe 60 , in the 3 (b) is shown is the surface coating 20 composed of two layers, namely the layer of non-crystalline inorganic material 21 and the mixed layer 22 ,

At the exhaust pipe 60 become 2/3 of the thickness of the surface coating 20 to the substrate side of the mixed layer 22 formed while the arranged on the side of the surface of the exhaust pipe layer of non-crystalline inorganic material 1/3.

At the exhaust pipe 60 out 3 (b) is the pore concentration section 23 in the mixed layer 22 ,

In an exhaust pipe 70 , in the 3 (c) is shown is the surface coating 20 composed of two layers, namely the layer of non-crystalline inorganic material 21 and the mixed layer 22 ,

Off at the exhaust pipe 3 (c) become 1/3 of the thickness of the surface coating 20 to the substrate side of the mixed layer 22 formed while the arranged on the side of the surface of the exhaust pipe layer of non-crystalline inorganic material 21 2/3 takes.

At the exhaust pipe 70 out 3 (c) is the pore concentration section 23 in the layer of non-crystalline inorganic material 21 ,

At the exhaust pipe 80 out 3 (d) is the surface coating ( 20a . 20b ) on both sides of the substrate 10 educated.

The surface coatings 20a . 20b each have the two-layer structure of the surface coating 3 (b) on.

The surface coating 20a is starting from the substrate 10 from a mixed layer 22a and a layer of non-crystalline inorganic material 21a , that is, composed of two layers laminated in this order.

At the exhaust pipe 80 out 3 (d) there is a pore concentration section 23a in the mixed layer 22a ,

The surface coating 20b is starting from the substrate 10 from a mixed layer 22b and a layer of non-crystalline inorganic material 21b , that is, composed of two layers laminated in this order.

At the exhaust pipe 80 out 3 (d) there is a pore concentration section 23b in the mixed layer 22b ,

At the exhaust pipe 80 become 2/3 of the thickness of the surface coatings 20a . 20b to the substrate side of the mixed layer 22a . 22b formed while the arranged on the side of the surface of the exhaust pipe layer of non-crystalline inorganic material 21a . 21b 1/3 takes.

Regarding the lamination order of the mixed layer 22 and the layer of non-crystalline inorganic material 21 There are no particular restrictions, but as in 1 . 3 (b) . 3 (c) and 3 (d) shown at the position adjacent to the substrate 10 preferably the mixed layer 22 arranged. The adhesive force between the mixed layer 22 and the substrate 10 is higher than the adhesive force between the non-crystalline inorganic material layer 21 and the substrate 10 Therefore, this structure is preferable in terms of the possibility of achieving a better adhesion performance between substrate and surface coating.

4 FIG. 10 is a sectional view schematically showing an example of a sectional surface of another exhaust pipe according to the first embodiment of the first invention. FIG. At the exhaust pipe 190 out 4 indicates the surface coating 20 a three-layer construction on.

Specifically, this structure is such that starting from the substrate 10 a mixed layer 22 , a layer of non-crystalline inorganic material 21b and a layer of non-crystalline inorganic material 21a , ie three layers, are laminated one above the other in this order.

The thickness ratio of the mixed layer 22 , the layer of non-crystalline inorganic material 21b and the layer of non-crystalline inorganic material 21a is mixed layer 22 : Layer of non-crystalline inorganic material 21b : Layer of non-crystalline inorganic material 21a = 25: 10: 5.

In 4 are five of the above-mentioned thickness ratio corresponding rectangular sections with 20A . 20B . 20C . 20D and 20E designated.

In the layer of non-crystalline inorganic material 21b There are numerous large independent pores 33 before, and there the bulk of the rectangle section 20B from the layer of non-crystalline inorganic material 21b is formed, it is the rectangular section 20B around a pore concentration section 23 ,

The rectangle section 20B is a rectangle section that is at the middle rectangle section 20C the five rectangular sections abuts.

For forming the surface coating as in 4 In the method of manufacturing the exhaust pipe to be discussed later, a base material composition for a mixed layer, a base composition for forming a pore concentration portion, a base material composition for a layer of non-crystalline inorganic material, a pore-forming material, and a base composition for a non-crystalline layer may be shown. crystalline inorganic material can be applied in this order, and the thickness of the individual layers can be adjusted by regulating the amount applied during the individual application steps.

5 (a) . 5 (b) and 5 (c) 11 are sectional views schematically showing an example of a sectional surface of another exhaust pipe according to the first embodiment of the first invention.

At the exhaust pipe 90 out 5 (a) The shape of the substrate differs from the exhaust pipe of the first embodiment of the first invention 1 from.

At the exhaust pipe 90 is the shape of the substrate 11 a half cylinder with one cylinder cut in half.

The surface coating 20 is on the side of the substrate 11 formed, whose area is larger. The structure of the surface coating 20 the exhaust pipe 90 corresponds to the structure of the surface coating 20 the exhaust pipe 70 out 3 (c) ,

In the exhaust pipe of the present embodiment, when using a semi-cylindrical substrate 11 at the area where the surface coating 20 is formed, even to the smaller area (ie to the opposite surface of the embodiment 5 (a) act.

The surface coating 20 can also be on both sides of the substrate 11 be formed.

At the exhaust pipe 100 out 5 (b) is the substrate 12 cylindrically shaped.

The surface coating 20 is on the surface of the substrate 11 formed whose area is larger (the outer peripheral surface). The structure of the surface coating 20 the exhaust pipe 100 corresponds to the structure of the surface coating 20 the exhaust pipe 70 out 3 (c) ,

In the exhaust pipe of the present embodiment, when using a cylindrical substrate 12 at the area where the surface coating 20 is formed, even around the smaller area (the inner peripheral surface) act.

At the exhaust pipe 110 out 5 (c) is the substrate 12 cylindrically shaped. The surface coating 20 is on both surfaces of the substrate 11 formed, so on the outer peripheral surface and the inner peripheral surface.

The structure of the surface coating 20a . 20b the exhaust pipe 110 corresponds to the structure of the surface coating 20 the exhaust pipe 70 out 3 (c) ,

In the exhaust pipe of the present embodiment, which in 1 . 3 (a) . 3 (b) . 3 (c) . 3 (d) . 5 (a) . 5 (b) and 5 (c) are shown, the number of pore concentration sections 23 one per substrate area, and the pore concentration section 23 is in the middle rectangle section of the five rectangular sections. That is, the pore concentration section 23 is at the position where the surface coating 20 ( 20a . 20b ) is divided into two parts in the thickness direction.

In the exhaust pipes of the present embodiment, the presence of a pore concentration section does not mean that the pores are uniformly distributed in the surface coating, but that there are only a few pores at the locations of the surface coating other than the pore concentration section (non-pore concentration sections).

The spots with few pores contribute to the mechanical strength and to increase the insulation performance of the surface coating as a whole.

Namely, the less the pores are, the higher the strength of the surface coating is, and the volume resistivity of the few pore sites is higher.

The breakdown distance of the pore portion is 3 kV / mm, and when a voltage of 500 V is applied, no further improvement in insulation performance is achieved unless pores having a pore diameter of 167 μm or more are present.

Since the pore diameter in the exhaust pipes of the present embodiment is largely below 167 μm, the volume resistivity of the few-pore sites is higher.

In the exhaust pipes of the present embodiment, a favorable effect can be obtained in this way compared to exhaust pipes in which numerous pores are present in the entire surface coating.

Next, the sequence of steps of a method of manufacturing an exhaust pipe according to the first embodiment of the first invention will be described.

A method of manufacturing an exhaust pipe according to the first embodiment of the first invention includes the steps of: preparing a metal substrate;
Preparing a base material composition for a surface coating,
Applying the base material composition for forming the surface coating on the metal substrate and forming the surface coating by firing, and is characterized in that
in the step of preparing the basecoat composition for forming the surface coating, a basecoat composition for a non-crystalline inorganic material layer containing a non-crystalline inorganic material, and / or a composite basecoat composition comprising a non-crystalline inorganic material and a crystalline inorganic material is prepared, and a pore-forming material is mixed with the base composition for a layer of non-crystalline inorganic material or the base material composition for a mixed layer, and a base material composition for forming a pore concentration portion is prepared;
in the step of forming the surface coating, the base composition is applied at least once to form a pore concentration portion, is fired to form pores in the surface coating, and the base composition for a layer of non-crystalline inorganic material or the composite composition for a mixed layer is applied at least once.

• (1) Als Ausgangsmaterial dient ein Substrat aus Metall (Metallsubstrat), wobei die Oberfläche des Metallsubstrats zunächst einer Reinigungsbehandlung unterzogen wird, um Verunreinigungen zu entfernen.

Now, the method of manufacturing the exhaust pipe of the first embodiment of the first invention will be described with reference to the example of manufacturing an exhaust pipe 1 the first embodiment of the first invention are described schematically in 1 is shown.

• (1) The starting material is a substrate made of metal (metal substrate), wherein the surface of the metal substrate is first subjected to a cleaning treatment to remove impurities.

With regard to the cleaning treatment, there are no particular limitations, and a known type of cleaning treatment may be used, for example, a method of ultrasonic cleaning in an alcoholic solvent.

After the cleaning treatment, the relative surface area of the substrate may be increased as necessary, and the surface of the substrate may be subjected to roughening treatment to adjust the roughness of the surface of the substrate. Concretely, as a roughening treatment, a sand blast treatment, an etching treatment or a high-temperature oxidation treatment may be performed. These treatments may be performed singly or in combination of two or more treatments.

• (2) Ein kristallines anorganisches Material und ein nicht-kristallines anorganisches Material werden feucht vermischt, um eine Grundstoffzusammensetzung für eine Mischschicht zuzubereiten.

After the roughening treatment, another cleaning treatment may be performed.

• (2) A crystalline inorganic material and a non-crystalline inorganic material are wet-mixed to prepare a base material composition for a mixed layer.

Concretely, the raw material composition for a mixed layer is prepared by preparing respectively a powder of a crystalline inorganic material and a powder of a non-crystalline inorganic material having a certain grain size, shape, etc., the powders are dry blended in a certain mixing ratio, thereby obtaining a mixed powder is prepared, whereupon water is added and carried out in a ball mill wet mixing.

• (3) Es wird eine Grundstoffzusammensetzung für eine Schicht aus nicht-kristallinem anorganischem Material zubereitet, die ein nicht-kristallines anorganisches Material enthält.

There are no particular limitations on the mixing ratio between the mixed powder and the water, but it is preferable to use 100 parts by weight of mixed powder per 100 parts by weight of water. In this way, a suitable viscosity for application to the metal substrate can be achieved. If necessary, the base material composition for a mixed layer may be mixed with a dispersing agent such as an organic solvent and an inorganic binder.

• (3) A base material composition is prepared for a non-crystalline inorganic material layer containing a non-crystalline inorganic material.

• (4) Es wird eine Grundstoffzusammensetzung für einen Porenkonzentrationsabschnitt zubereitet.

The preparation of the base material composition for a layer of non-crystalline inorganic material is different from the method of preparing the base material composition for a mixed layer in that no crystalline inorganic material is added and no dry mixing is performed.

• (4) A base material composition for a pore concentration section is prepared.

When a pore concentration portion is formed in the mixed layer, as a method of forming the pore concentration portion of the composite composition for a mixed layer, a pore-forming material containing at least one of a pore-forming agent, an air-entraining agent, an air-filler and an inorganic fiber may be mixed.

Preferably, a pore-forming agent is used.

As the pore-forming agent, for example, blisters which are microfluidic spheres containing the oxide ceramics component, spherical acrylic particles, graphite, etc. may be used.

In forming the pore concentration section in the non-crystalline inorganic material layer, a method may be used wherein the base material composition for a non-crystalline inorganic material layer is admixed with at least one of a pore forming agent, an air entraining agent, an air filler, and an inorganic fiber.

• (5) Auf die Oberfläche des Metallsubstrats wird die Grundstoffzusammensetzung zum Ausbilden einer Oberflächenbeschichtung (Grundstoffzusammensetzung für eine Mischschicht) aufgetragen.

In the present specification, a base material composition for a mixed layer and a base composition for a non-crystalline inorganic material layer containing a base material composition for a pore concentration portion will also be referred to hereinafter as a base composition for forming a surface coating.

• (5) The base material composition for forming a surface coating (base material composition for a mixed layer) is applied to the surface of the metal substrate.

As a method of applying the base material composition for a mixed layer, for example, spray coating, electrostatic coating, ink jet, transfer by means of a stamper or roller, brushing, etc. may be used.

The application of the basecoat composition to form a surface coating may also be accomplished by dipping the metal substrate into the basecoat composition to form a surface coating.

When manufacturing the exhaust pipe 1 out 1 become from the substrate, the mixed layer 22b , the layer of non-crystalline inorganic material 21 containing the pore concentration section 23 contains, and the mixed layer 22a laminated in this order.

• (6) Das Metallsubstrat, auf das die Grundstoffzusammensetzung zum Ausbilden einer Oberflächenbeschichtung (Grundstoffzusammensetzung für eine Mischschicht) aufgetragen wurde, wird einer Brennbehandlung unterzogen.

Therefore, the base material composition for a mixed layer is first applied to the metal substrate.

• (6) The metal substrate to which the base coat composition for forming a surface coating (masterbatch composition for a mixed layer) has been applied is subjected to a firing treatment.

Concretely, after drying the metal substrate on which the base material composition has been applied to form a surface coating, a surface coating is formed by firing it by heating.

• (7) Auf die Oberfläche der Oberflächenbeschichtung (Mischschicht) wird die Grundstoffzusammensetzung zum Ausbilden einer Oberflächenbeschichtung (Grundstoffzusammensetzung für einen Porenkonzentrationsabschnitt) aufgetragen. In diesem Schritt wird eine Grundstoffzusammensetzung für einen Porenkonzentrationsabschnitt aufgetragen, wobei der Grundstoffzusammensetzung für eine Schicht aus nicht-kristallinem anorganischem Material ein Porenbildungsmaterial beigemischt wurde. Nach dem Trocknen wird durch erwärmendes Brennen eine Oberflächenbeschichtung ausgebildet.

As the firing temperature, a temperature above the softening point of the non-crystalline inorganic material is preferable, and depending on the nature of the non-crystalline inorganic material, preferably a temperature between 700 ° and 1,100 ° C. By choosing a temperature above the softening point of the non-crystalline inorganic material, a firm adhesion between the metal substrate and the non-crystalline inorganic material can be achieved, whereby a surface coating (mixed layer) can be formed firmly adhered to the substrate.

• (7) On the surface of the surface coating (mixed layer), the base material composition for forming a surface coating (base material composition for a pore concentration section) is applied. In this step, a base material composition for a pore concentration section is coated, and a pore-forming material is mixed with the base material composition for a layer of non-crystalline inorganic material. After drying, a surface coating is formed by heating firing.

Pores are formed by the action of the pore-forming material upon drying and firing, and therefore, the surface coating laminated in this step is a layer of non-crystalline inorganic material containing the pore concentration portion.

• (8) Auf die Oberfläche der Oberflächenbeschichtung (Schicht aus nicht-kristallinem anorganischem Material ist, die den Porenkonzentrationsabschnitt enthält) wird die Grundstoffzusammensetzung zum Ausbilden einer Oberflächenbeschichtung (Grundstoffzusammensetzung für eine Mischschicht) aufgetragen. Nach dem Trocknen wird durch erwärmendes Brennen eine Oberflächenbeschichtung ausgebildet. Die in diesem Schritt auflaminierte Oberflächenbeschichtung ist eine Mischschicht. Das Verfahren zum Auftragen der Grundstoffzusammensetzung zum Ausbilden einer Oberflächenbeschichtung und das Trocknungs- und Brennverfahren entsprechen denjenigen der Schritte 5 und 6.

The method for applying the base coat composition for forming a surface coating and the drying and firing method are the same as those of steps 5 and 6.

• (8) On the surface of the surface coating (non-crystalline inorganic material layer containing the pore concentration portion) is applied the base material composition for forming a surface coating (base material composition for a mixed layer). After drying, a surface coating is formed by heating firing. The surface coating laminated in this step is a mixed layer. The method for applying the base coat composition for forming a surface coating and the drying and firing method are the same as those of steps 5 and 6.

In the above-described sequence, an exhaust pipe of the present embodiment (shown in FIG 1 schematically illustrated exhaust pipe 1) are produced.

• (1) Bei der Abgasleitung ist an der Oberflächenbeschichtung wenigstens ein länglicher Rechteckabschnitt als Porenkonzentrationsabschnitt vorgesehen, auf dessen Fläche 30% oder mehr der Porenfläche der in der gesamten Oberflächenbeschichtung vorliegenden Poren vorliegen.

Hereinafter, the effects of the exhaust pipe of the present embodiment and the manufacturing method of the exhaust pipe of the present embodiment will be listed.

• (1) In the exhaust pipe, at least one elongate rectangular section as the pore concentration section is provided on the surface coating, on the surface of which 30% or more of the pore area of pores present in the entire surface coating is present.

It is believed that cracks that form in the surface coating due to exposure to heat first form on the surface of the surface coating and then spread in the thickness direction of the surface coating toward the substrate.

When a crack that has formed in the surface coating spreads and hits a pore, the crack is prevented from spreading beyond the pore. Thus, if at least one of the rectangular portions in the surface coating is a pore concentration portion, cracks eventually formed on the surface of the surface coating easily hit a pore in the pore concentration portion, thus preventing the crack from spreading further to the substrate via the pore concentration portion.

The pores also include independent pores, and the pores do not connect the exterior of the exhaust conduit and the surface of the substrate to each other. If the pores do not bond the exterior of the exhaust pipe and the surface of the substrate, it does not happen that a crack that enters the pore will penetrate the surface coating.

Thus, by providing a pore concentration portion in the surface coating and the pores of the surface coating can not connect the outside of the exhaust pipe and the surface of the substrate, even if cracks are generated in the surface coating by heat, crack propagation through the pores in the pore concentration portion can be prevented ,

• (2) Bei der Abgasleitung der vorliegenden Ausführungsform beträgt das Porenverhältnis (B/A) des Porenkonzentrationsabschnitts, bei dem es sich um das Verhältnis zwischen der von den Poren eingenommenen Fläche (B) zur Fläche (A) des Rechteckabschnitts handelt, 0,02 oder mehr. Wenn das Porenverhältnis 0,02 oder mehr beträgt, existieren genügend Poren im Porenkonzentrationsabschnitt, um zu verhindern, dass sich Risse ausbreiten, da die Wahrscheinlichkeit ansteigt, dass ein Riss auf eine Pore trifft. Aus diesem Grund lässt sich die Ausbreitung von Rissen besonders sicher verhindern.
• (3) In der Oberflächenbeschichtung der Abgasleitung der vorliegenden Ausführungsform ist ein kristallines anorganisches Material enthalten. Das kristalline anorganische Material enthält wenigstens ein Oxid aus der Gruppe Mangan, Eisen, Kupfer, Kobalt, Chrom und Aluminium.

Thus, damage to the surface coating can be prevented. For this reason, the exhaust pipe can ensure a high insulation performance.

• (2) In the exhaust pipe of the present embodiment, the pore ratio (B / A) of the pore concentration section, which is the ratio between the area occupied by the pores (B) and the area (A) of the rectangular section, is 0.02 more. When the pore ratio is 0.02 or more, enough pores exist in the pore concentration portion to prevent cracks from spreading, since the probability of a crack hitting a pore increases. For this reason, the spread of cracks can be prevented with particular certainty.
• (3) In the surface coating of the exhaust pipe of the present embodiment, a crystalline inorganic material is contained. The crystalline inorganic material contains at least one of manganese, iron, copper, cobalt, chromium and aluminum.

Since oxides have a high infrared radiation rate, the radiation of the surface coating can be increased. When the irradiation rate of the surface coating is high, an exhaust pipe having excellent heat dissipation performance at high temperatures can be obtained.

• (4) Bei der Abgasleitung der vorliegenden Ausführungsform beträgt die Anzahl der Porenkonzentrationsabschnitte eins pro Fläche des Substrats, und der Rechteckabschnitt, der den Porenkonzentrationsabschnitt bildet, ist der mittlere Rechteckabschnitt der fünf Rechteckabschnitte.

In addition, in particular, the use of an oxide of aluminum contributes to the insulation performance of the exhaust pipe.

• (4) In the exhaust pipe of the present embodiment, the number of pore concentration sections is one per area of the substrate, and the rectangular section that constitutes the pore concentration section is the middle rectangle section of the five rectangular sections.

• (5) Bei der Abgasleitung der vorliegenden Ausführungsform beträgt die Dicke der Oberflächenbeschichtung 25 bis 1.000 μm.

When the pore concentration portion is at the position of the middle rectangle portion where the surface coating is divided into two in the thickness direction, the surface coating is divided into two parts of equal thickness by the pore concentration portion. The amount of thermal shock applied to the surface coating then corresponds to that which would be present in the case of a thin surface coating, so that damage to the surface coating can be effectively prevented.

• (5) In the exhaust pipe of the present embodiment, the thickness of the surface coating is 25 to 1,000 μm.

• (6) Bei dem Herstellungsverfahren der Abgasleitung der vorliegenden Ausführungsform wird ein Porenbildungsmaterial mit der Grundstoffzusammensetzung für eine Schicht aus nicht-kristallinem anorganischem Material oder der Grundstoffzusammensetzung für eine Mischschicht vermischt und so eine Grundstoffzusammensetzung zum Ausbilden eines Porenkonzentrationsabschnitts zubereitet, und die Grundstoffzusammensetzung zum Ausbilden eines Porenkonzentrationsabschnitts wird auf ein Metallsubstrat aufgetragen, und dieses wird einer Brennbehandlung unterzogen.

If the thickness of the surface coating is less than 25 μm, sufficient insulation performance can not be achieved when used as an exhaust pipe. On the other hand, if the thickness of the surface coating is more than 1,000 μm, the thermal shock that acts on the surface coating increases, so that the surface coating is more likely to be damaged.

• (6) In the manufacturing method of the exhaust pipe of the present embodiment, a pore-forming material is mixed with the base material composition for a non-crystalline inorganic material layer or mixed layer base material composition to prepare a base composition for forming a pore concentration section, and the base material composition for forming a pore concentration section is applied to a metal substrate, and this is subjected to a burning treatment.

As pores are formed at the position of the pore-forming material by this treatment, an exhaust pipe having a pore concentration portion at a desired position of the surface coating can be manufactured.

embodiments

In the following, the first invention will be described in more detail based on an embodiment, but the first invention is not limited to this embodiment.

Preparation of the substrate

As a metal substrate, a plate-shaped stainless steel substrate (SUS430) of 2 mm in thickness was subjected to ultrasonic cleaning in an alcoholic solvent, and then its surfaces (both sides) were roughened by sandblasting. The sand blast treatment was carried out for 10 minutes with grit grains of 80 grit Al ₂ O ₃ .

In this way, a plate-shaped substrate was produced.

A cylindrical substrate made of stainless steel (SUS430) having a diameter of 40 mm and a thickness of 2 mm was subjected to the same cleaning and roughening treatment as the plate-shaped substrate, thereby producing a cylindrical substrate.

By cutting the cylindrical substrate in half, a semi-cylindrical substrate was also fabricated.

Preparation of the base material composition for a mixed layer

As powder of crystalline inorganic material, a powder having 30% by weight of MnO ₂ , 5% by weight of FeO, 5% by weight of CuO and 5% by weight of CoO was prepared.

As powder of non-crystalline inorganic material, K4006A-100M (Bi ₂ O ₃ -B ₂ O ₃ glass, softening point 770 ° C) manufactured by Asahi Glass Co., Ltd. was used. prepared.

As the organic binder, methyl cellulose (product name: METOLOSE-65SH) of Shin-Etsu Chemical Co., Ltd. was used. prepared.

For the preparation of the base material composition for a mixed layer, a mixed powder was prepared by dry mixing the powder of crystalline inorganic material and the powder of non-crystalline inorganic material, and to 100 parts by weight of the mixed powder, another 100 parts by weight of water was added thereto, and in a ball mill Wet mixing made a mud.

As the base material composition for a mixed layer, two kinds, namely a base material composition for a mixed layer X and a base material composition for a mixed layer Y, were prepared.

The mixing ratio of the base material composition for a mixed layer X was: crystalline inorganic material: non-crystalline inorganic material: organic binder = 4: 6: slight amount (wt%), and the mixing ratio of the base material composition for a mixed layer Y: crystalline inorganic material : non-crystalline inorganic material: organic binder = 1: 9: slight amount.

A "minor amount" refers to 0.1 to 3 wt .-% based on 100 wt .-% of the total mass of the base material composition for a mixed layer.

Preparation of the base material composition for a layer of non-crystalline inorganic material

The base material composition for a layer of non-crystalline inorganic material was prepared in the same process as the composite composition for a mixed layer, but using no crystalline inorganic material and no dry mixing step was performed.

This sludge is referred to below as the base material composition for a layer of non-crystalline inorganic material Z.

Preparation of the base material composition for a pore concentration section

The base material composition for a pore concentration section was prepared in the same process as the base material composition for a non-crystalline inorganic material layer, but with wet mixing as a pore-forming material, 10 weight parts of micro air balls whose main component was silica were added.

The pore concentration portion base compositions in which pore-forming material is added to the mixed layer X base material, the mixed layer Y base material composition, and the non-crystalline inorganic material Z base material composition are also referred to below as a base material composition for a pore concentration portion X, Reference substance composition for a pore concentration section Y or base composition for a pore concentration section Z denoted.

Using the substrate, the mixed layer base material compositions, the non-crystalline inorganic material layer base composition, and the pore concentration section base compositions, the following embodiments and comparative examples were performed.

First embodiment

On the surface of the plate-shaped substrate, the composite base material compositions X were spray-coated and dried at 70 ° C for 20 minutes in a dryer. Next, it was subjected to a firing treatment in air at 850 ° C for 15 minutes to form a surface coating (mixed layer). The thickness of the mixed layer was 25 μm. This layer is also referred to as the first layer.

Next, on the surface of the mixed layer by spray coating, the pore concentration portion Z base material compositions were applied and dried at 70 ° C for 20 minutes in a dryer. Then, it was subjected to a firing treatment in air at 850 ° C for 15 minutes to form a surface coating (non-crystalline inorganic material layer containing a pore concentration portion). The thickness of the non-crystalline inorganic material layer containing a pore concentration section was 10 μm. This layer is also referred to as the second layer.

Next, on the surface of the non-crystalline inorganic material layer containing a pore concentration section, by spray coating, the non-crystalline inorganic material layer Z primer compositions were applied and dried at 70 ° C for 20 minutes in a dryer. Then, it was subjected to a firing treatment in air at 850 ° C for 15 minutes to form a surface coating (non-crystalline inorganic material layer). The thickness of the non-crystalline inorganic material layer was 25 μm. This layer is also called the third layer.

An exhaust pipe was made based on the procedure described above.

The layer thickness of the surface coating of the exhaust pipe obtained in this way was 60 μm.

The pore concentration portion was thus formed at the position where the surface coating was divided into two in the thickness direction.

Second to seventh embodiments

Exhaust pipes were produced in the same method as for the first embodiment except that the composition of the surface coating was changed as shown in Table 1.

The embodiments two to seven differ from the first embodiment in the following points.

In the second embodiment, the thickness of the first layer having the composite composition for a mixed layer X was 25 μm, the thickness of the second layer having the base composition for a pore concentration section X was 10 μm, and the thickness of the third layer was the base composition for a layer of non-crystalline inorganic Material Z 25 μm.

In the third embodiment, on both sides of the substrate, the thickness of the first layer having the mixed layer base material X was 25 μm, the thickness of the second layer having the pore concentration section Z was 25 μm, and the thickness of the third layer was the mixed layer base material composition Z 25 μm.

In the fourth embodiment, the thickness of the first layer having the raw material composition for a non-crystalline inorganic material layer Z was 25 μm, the thickness of the second layer having the base material composition for a pore concentration section X was 25 μm, and the thickness of the third layer was one with the base material composition Layer of non-crystalline inorganic material Z 25 μm.

In the fifth embodiment, the thickness of the first layer having the composite composition for a mixed layer X was 5 μm, the thickness of the second layer containing the base material composition for a pore concentration section Z was 10 μm and the thickness of the third layer having the base material composition for a mixed layer X was 5 μm.

In the sixth embodiment, on both sides of the substrate, the thickness of the first layer having the mixed layer X composite was 100 μm, the thickness of the second layer having the pore concentration section Y was 50 μm, and the thickness of the third layer was one layer of non-crystalline inorganic material Z 50 μm.

In the seventh embodiment, the thickness of the first layer having the composite composition for a mixed layer X was 250 μm, the thickness of the second layer containing the base material composition for a pore concentration section Z was 100 μm, and the thickness of the third layer was the base composition for a non-crystalline inorganic layer Material Z 50 μm.

In all embodiments, the number of pore concentration sections was one per area of the substrate. In the first to fifth embodiments, the rectangle portion constituting the pore concentration portion was the middle rectangle portion of the five rectangle portions.

In the sixth and seventh embodiments, the rectangle portion constituting the pore concentration portion was the rectangle portion adjacent to the middle rectangle portion of the five rectangle portions (that is, the second rectangle portion counted from the surface).

Eighth embodiment

In the present embodiment, a semi-cylindrical substrate was used as the substrate.

Then, an exhaust pipe was produced in the same manner as in the first embodiment, but from the surfaces of the semi-cylindrical substrate only on the surface having the larger area, a surface coating having the composition shown in Table 1 was formed.

Concretely, the thickness of the first layer having the composite composition for a mixed layer X was 50 μm, the thickness of the second layer having the base composition for a pore concentration section X was 50 μm, and the thickness of the third layer was the base composition for a layer of non-crystalline inorganic material Z 35 μm.

Also in the present embodiment, the number of pore concentration sections was one per area of the substrate, and the rectangular section constituting the pore concentration section was the middle rectangle section of the five rectangular sections.

Ninth embodiment

In the present embodiment, a cylindrical substrate was used as the substrate.

Then, in the same manner as in the first embodiment, an exhaust pipe was manufactured, and a surface coating having the composition shown in Table 1 was formed on both surfaces of the cylindrical substrate.

Concretely, the thickness of the first layer having the composite composition for a mixed layer X was 50 μm, the thickness of the second layer having the base composition for a pore concentration section X was 50 μm, and the thickness of the third layer was the base composition for a layer of non-crystalline inorganic material Z 35 μm.

In the present embodiment, the number of pore concentration sections was one per area of the substrate, and the rectangular section that formed the pore concentration section was the middle rectangle section of the five rectangular sections.

First to sixth comparative examples

In Comparative Examples, surface coatings having the structure shown in Table 1 were formed without using a base material composition for a pore concentration section. In the first to fifth comparative examples, the surface coating was formed on one side of the substrate.

In the first comparative example, the thickness of the first layer having the mixed-layer base material composition X was 20 μm, the thickness of the second composite-base composite layer X was 20 μm, and the third layer containing the mixed-layer base material composition was X 20 μm.

In the second comparative example, the thickness of the first layer having the composite composition for a mixed layer X was 25 μm, the thickness of the second layer having the base composition for a non-crystalline inorganic material layer Z was 10 μm, and the thickness of the third layer was one with the base material composition Layer of non-crystalline inorganic material Z 25 μm.

In the third comparative example, the thickness of the first layer having the composite composition for a mixed layer X was 25 μm, the thickness of the second layer having the composite composition for a mixed layer X was 10 μm, and the thickness of the third layer was the base composition for a non-crystalline inorganic layer Material Z 25 μm.

In the fourth comparative example, the thickness of the first layer having the mixed-layer base material composition X was 50 μm, the thickness of the second layer containing the mixed-layer base material composition X was 50 μm, and no third layer was formed.

In the fifth comparative example, a semi-cylindrical substrate was used as the substrate. The thickness of the first layer with the base material composition for a mixed layer X was 50 μm, the thickness of the The second layer having the base material composition for a mixed layer X was 50 μm, and the thickness of the third layer containing the base material composition for a layer of non-crystalline inorganic material Z was 35 μm.

In the sixth comparative example, a cylindrical substrate was used as the substrate. The thickness of the first layer having the base material composition for a mixed layer X was 50 μm, the thickness of the second layer having the base material composition for a mixed layer X was 50 μm, and the thickness of the third layer was the base composition for a layer of non-crystalline inorganic material Z was 35 μm, and the layers were formed on both sides of the cylindrical substrate.

In none of the comparative examples was there a pore concentration section in the surface coating.

Evaluation of the characteristic curves of the exhaust pipes

The characteristics of the exhaust pipes of the embodiments and comparative examples were evaluated as follows.

The evaluation results of the individual characteristic curves are listed in Table 2.

Thermal shock testing

The individual exhaust pipes were heated to 600 ° C, the heated to 600 ° C exhaust pipes were kept under water at a temperature of 25 ° C and subjected to a thermal shock, after which it was visually checked whether there were spalling on the surface coating.

In the column "Chipping in thermal shock test" from Table 2, the presence of chippings in the test performed is indicated as "Yes" and the absence thereof as "No".

Measurement of the volume resistivity

The volume resistivity of the individual exhaust pipes was measured by means of a Digital High Resistance / Micro Current Meter (Model No. R8340) from Advantest Corporation. The measurement followed Japanese Industrial Standard JIS C 2131 , and a voltage of 500 V was applied, whereupon the resistance of the individual exhaust pipes was measured.

Since the volume resistivity of the metal substrate is extremely low, the volume resistivity measured here in practice depends strongly on the volume resistivity of the surface coating.

Measurement of dielectric strength

Of the Japanese Industrial Standard JIS C 2110-2 Subsequently, 500 V of voltage was applied to the front and rear of the exhaust pipes, and it was visually checked whether the insulation of the exhaust pipes was damaged.

In cases where a surface coating was formed on only one side of the exhaust pipe, the one electrode was brought into contact with the upper surface of the surface coating and the other electrode with the substrate.

In cases where a surface coating was formed on both sides of the exhaust pipe, the one electrode was brought into contact with the one surface of the surface coating and the other electrode with the other surface of the surface coating.

In the column "Dielectric strength (500 V)" of Table 2, the case that no damage of the insulation had occurred was rated as "Yes" (dielectric strength) and the case that the insulation was damaged was changed to "No (Dielectric strength does not exist).

Measurement of the radiation rate

By means of a radiation meter AERD the company Kyoto Electronics Manufacturing Co., Ltd. the radiation rate of the surface coating of the individual exhaust pipes was measured.

Measurement of the thermal conductivity of the surface coating

The thermal conductivity of the surface coating of the individual exhaust pipes was measured with a laser flash device (thermal constant measuring device: NETZSCH LFA457 Microflash).

Together with the measurement results for the individual exhaust pipes, Table 2 also shows a four-level overall assessment with the ratings "Very Good", "Good", "Sufficient" and "Insufficient".

• (1) Auftreten von Abplatzungen in der Wärmeschockprüfung: Ungenügend
• (2) Nicht unter (1) fallend, aber mit dem Ergebnis „Nein” für Durchschlagfestigkeit: Ausreichend
• (3) Nicht unter (1) oder (2) fallend, aber mit einem spezifischen Durchgangswiderstand von unter 1,E+10 (Ωm), einer Abstrahlungsrate von unter 0,80 oder einer Wärmeleitfähigkeit der Oberflächenbeschichtung von unter 0,5 (W/mK): Gut
• (4) Nicht unter (1) bis (3) fallend: Sehr gut

The evaluation standard for the overall assessment was as follows.

• (1) Occurrence of flaking in the thermal shock test: Insufficient
• (2) Not falling under (1), but with the result "No" for Dielectric Strength: Sufficient
• (3) Not covered by (1) or (2) but with a volume resistivity of less than 1, E + 10 (Ωm), a radiation rate of less than 0,80 or a thermal conductivity of the surface coating of less than 0,5 (W / mK): Good
• (4) Not covered by (1) to (3): Very good

Among the embodiments, the result of the fifth embodiment was "sufficient" while it was "very good" in the first to fourth embodiments and in the sixth to ninth embodiments.

Since a pore concentration section was formed in the individual embodiments, no flaking occurred in the thermal shock test, and damage to the surface coating could be prevented.

In the fifth embodiment, the total layer thickness of the 20 μm surface coating was low. In fact, if the surface coating is thin, sufficient insulation performance can not be ensured, so that the result in terms of dielectric strength was "No". Since the result with respect to the dielectric strength was "No", the overall result of the evaluation was "sufficient".

• X: Grundstoffzusammensetzung für eine Mischschicht (kristallines anorganisches Material:nicht-kristallines anorganisches Material:organisches Bindemittel = 4:6:geringfügige Menge)
• Y: Grundstoffzusammensetzung für eine Mischschicht (kristallines anorganisches Material:nicht-kristallines anorganisches Material:organisches Bindemittel = 1:9:geringfügige Menge)
• Z: Grundstoffzusammensetzung für eine Schicht aus nicht-kristallinem anorganischem Material (nicht-kristallines anorganisches Material:organisches Bindemittel = 10:geringfügige Menge)

Tabelle 2 Abplatzung bei Wärmeschockprüfung Spezifischer Durchgangswiderstand Durchschlagfestigkeit (500 V) Abstrahlungsrate Wärmeleitfähigkeit der Oberflächenbeschichtung Gesamtbewertung [Ωm] [–] [W/mK] Erstes Ausführungsbeispiel Nein 6,E+12 Ja 0,81 1,1 Sehr gut Zweites Ausführungsbeispiel Nein 4,E+12 Ja 0,81 1,4 Sehr gut Drittes Ausführungsbeispiel Nein 3,E+12 Ja 0,82 1,5 Sehr gut Viertes Ausführungsbeispiel Nein 7,E+12 Ja 0,81 1,0 Sehr gut Fünftes Ausführungsbeispiel Nein 5,E+12 Nein 0,82 1,3 Ausreichend Sechstes Ausführungsbeispiel Nein 5,E+12 Ja 0,81 1,5 Sehr gut Siebtes Ausführungsbeispiel Nein 4,E+12 Ja 0,81 1,5 Sehr gut Achtes Ausführungsbeispiel Nein 3,E+12 Ja 0,81 1,6 Sehr gut Neuntes Ausführungsbeispiel Nein 3,E+12 Ja 0,81 1,6 Sehr gut Erstes Vergleichsbeispiel Ja 1,E+08 Ja 0,82 2,0 Ungenügend Zweites Vergleichsbeispiel Ja 6,E+12 Ja 0,81 1,1 Ungenügend Drittes Vergleichsbeispiel Ja 4,E+12 Ja 0,81 1,4 Ungenügend Viertes Vergleichsbeispiel Ja 1,E+13 1a 0,81 0,5 Ungenügend Fünftes Vergleichsbeispiel Ja 3,E+12 Ja 0,81 1,6 Ungenügen Sechstes Vergleichsbeispiel Ja 1,E+12 Ja 0,81 1,8 Ungenügen Since no pore concentration section was formed in the first to sixth comparative examples, flaking occurred in the thermal shock test, so that the result of the evaluation was "insufficient" in all cases. Table 1

• X: base material composition for mixed layer (crystalline inorganic material: non-crystalline inorganic material: organic binder = 4: 6: slight amount)
• Y: base material composition for mixed layer (crystalline inorganic material: non-crystalline inorganic material: organic binder = 1: 9: slight amount)
• Z: base material composition for non-crystalline inorganic material layer (non-crystalline inorganic material: organic binder = 10: slight amount)

Table 2 Chipping at thermal shock test Specific volume resistance Dielectric strength (500 V) radiation rate Thermal conductivity of the surface coating Overall [Ohm-m] [-] [W / mK] First embodiment No 6, E + 12 Yes 0.81 1.1 Very well Second embodiment No 4, E + 12 Yes 0.81 1.4 Very well Third embodiment No 3, E + 12 Yes 0.82 1.5 Very well Fourth embodiment No 7, E + 12 Yes 0.81 1.0 Very well Fifth embodiment No 5, E + 12 No 0.82 1.3 Sufficient Sixth embodiment No 5, E + 12 Yes 0.81 1.5 Very well Seventh embodiment No 4, E + 12 Yes 0.81 1.5 Very well Eighth embodiment No 3, E + 12 Yes 0.81 1.6 Very well Ninth embodiment No 3, E + 12 Yes 0.81 1.6 Very well First comparative example Yes 1, E + 08 Yes 0.82 2.0 Insufficient Second comparative example Yes 6, E + 12 Yes 0.81 1.1 Insufficient Third comparative example Yes 4, E + 12 Yes 0.81 1.4 Insufficient Fourth Comparative Example Yes 1, E + 13 1a 0.81 0.5 Insufficient Fifth Comparative Example Yes 3, E + 12 Yes 0.81 1.6 insufficiency Sixth Comparative Example Yes 1, E + 12 Yes 0.81 1.8 insufficiency

Second embodiment

In the following, a second embodiment will be described, which is an embodiment of an exhaust pipe of the first invention.

In the exhaust pipe of the second embodiment of the first invention, the surface coating comprises only one layer of non-crystalline inorganic material or only a mixed layer. Otherwise, its structure corresponds to the exhaust pipe of the first embodiment of the first invention.

6 (a) and 6 (b) 15 are sectional views schematically showing an example of a sectional area of the exhaust pipe according to the second embodiment of the first invention.

At the exhaust pipe 120 out 6 (a) includes the surface coating 20 only one layer of non-crystalline inorganic material 21 , while no mixed layer is present. The pore concentration section 23 is located in the middle rectangle section of the five rectangular sections.

At the exhaust pipe 130 out 6 (b) includes the surface coating 20 only a mixed layer 22 while there is no layer of non-crystalline inorganic material. The pore concentration section 23 is located in the middle rectangle section of the five rectangular sections.

The exhaust pipe of the present embodiment can be manufactured in the exhaust pipe manufacturing method of the first embodiment of the first invention, but only a base material composition for a non-crystalline inorganic material layer or a composite base material composition is used.

As in 6 (a) and 6 (b) As a method for forming a pore concentration section in the center rectangle section, the five rectangle section can be called a method wherein the surface coating formed with each application process has the same thickness five times by applying the base material compositions, and the base material composition for the third application process is the base material composition for forming a pore concentration section at least one of a pore-forming agent, an air-entraining agent, an air-filler and an inorganic fiber is used.

Even if the coating operation of the raw material compositions is carried out three times, each forming surface coatings of the same thickness and using the base composition for forming a pore concentration portion as the base material composition for the second coating operation, the pore concentration portion is likely to be formed in the middle rectangle portion of the five rectangular portions.

Also, by suitably adjusting the thickness of the surface coatings according to the number of application operations, the pore concentration portion can be formed at the desired position.

With the exhaust pipe of the present embodiment, the effects (1), (2), (4) and (5) of the exhaust pipe of the first embodiment of the first invention can be achieved. When the surface coating comprises only the mixed layer, the effect (3) of the exhaust pipe of the first embodiment of the first invention can be also obtained.

Tenth and eleventh embodiment

According to the procedure of the first embodiment of the first embodiment of the first invention, exhaust pipes were manufactured, whereby the composition of the surface coating was changed as shown in Table 3.

In the tenth embodiment, on both sides of a cylindrical substrate, the thickness of the first layer having the base material composition for a non-crystalline inorganic material layer Z was 50 μm, the thickness of the second layer having the base material composition for a pore concentration section Z was 50 μm and the thickness of the third Layer with the base material composition for a layer of non-crystalline inorganic material Z 50 μm.

In the eleventh embodiment, on both sides of a cylindrical substrate, the thickness of the first layer having the composite composition for a mixed layer X was 50 μm, the thickness of the second layer having the base composition for a pore concentration section X was 50 μm, and the thickness of the third layer was one with the base material composition Mixed layer X 50 μm.

In both embodiments, the number of pore concentration sections was one per area of the substrate, and the rectangular section that formed the pore concentration section was the middle rectangle section of the five rectangular sections.

Thus, in the tenth embodiment, a surface coating comprising only layers of non-crystalline inorganic material was formed, and in the eleventh embodiment, a surface coating comprising only mixed layers was formed.

• X: Grundstoffzusammensetzung für eine Mischschicht (kristallines anorganisches Material:nicht-kristallines anorganisches Material:organisches Bindemittel = 4:6:geringfigige Menge)
• Z: Grundstoffzusammensetzung für eine Schicht aus nicht-kristallinem anorganischem Material (nicht-kristallines anorganisches Material:organisches Bindemittel = 10:geringfügige Menge)

Tabelle 4 Abplatzung bei Wärmeschockprüfung Spezifischer Durchgangswiderstand Durchschlagfestigkeit (500 V) Abstrahlungsrate Wärmeleitfähigkeit der Oberflächenbeschichtung Gesamtbewertung [Ωm] [–] [W/mK) Zehntes Ausführungsbeispiel Nein 6,E+13 Ja 0,81 0,5 Sehr gut Elftes Ausführungsbeispiel Nein 1,E+8 Ja 0,82 2,0 Gut A judgment was made according to the first embodiment of the first embodiment of the first invention, and the evaluation results for the individual embodiments are shown in Table 4. Table 3

• X: base material composition for mixed layer (crystalline inorganic material: non-crystalline inorganic material: organic binder = 4: 6: low amount)
• Z: base material composition for non-crystalline inorganic material layer (non-crystalline inorganic material: organic binder = 10: slight amount)

Table 4 Chipping at thermal shock test Specific volume resistance Dielectric strength (500 V) radiation rate Thermal conductivity of the surface coating Overall [Ohm-m] [-] [W / mK) Tenth embodiment No 6, E + 13 Yes 0.81 0.5 Very well Eleventh embodiment No 1, E + 8 Yes 0.82 2.0 Well

The overall rating of the tenth embodiment was "very good" and the overall rating of the eleventh embodiment was "good".

Since a pore concentration portion was present in both embodiments, no flaking occurred in the thermal shock test, and damage to the surface coating could be prevented.

Since the exhaust pipe of the tenth embodiment had a surface coating comprising only layers of non-crystalline inorganic material, the volume resistivity was 1, E + 13 (Ωm) high.

In contrast, since the exhaust pipe of the eleventh embodiment had a surface coating comprising only mixed layers, the volume resistivity was 1, E + 08 (Ωm) low. For this reason, their evaluation result was "good".

Third embodiment

Hereinafter, a third embodiment will be described, which is an exhaust pipe of the first invention and an embodiment of a manufacturing method of an exhaust pipe of the first invention.

The exhaust pipe of the third embodiment of the first invention differs from the first embodiment of the first invention in the method of forming the pore concentration portion.

In the exhaust pipe of the present embodiment, the surface coating is formed divided into a plurality of layers.

In the step of forming the surface coating, a lower surface coating is roughened, and on the roughened surface of the surface coating, an upper surface coating is formed, whereby pores are formed in the interface between the lower surface coating and the upper surface coating. The part containing the pores formed in this way and containing the interface between the lower surface coating and the upper surface coating is thus the pore concentration section.

Also, the exhaust pipe of the present embodiment has a pore concentration portion, wherein the pore concentration portion of the present embodiment is determined by the same method as used to determine the pore concentration portion of the exhaust pipe of the first embodiment of the first invention.

The "bottom surface coating" refers to the layer of surface coating that is closer to the substrate, and the "top surface coating" refers to the layer of surface coating that is closer to the surface.

7 (a) and 7 (b) 15 are sectional views schematically showing an example of a sectional area of the exhaust pipe according to the third embodiment of the first invention.

At the exhaust pipe 140 out 7 (a) includes the surface coating 20 a mixed layer 22a , a layer of non-crystalline inorganic material 21 and a mixed layer 22b ,

The pore concentration section 23 is at the interface between the mixed layer 22b the closer to the substrate 10 lying side (lower layer) and the layer of non-crystalline inorganic material 21 contain.

The rectangle section, which is in 7 (a) the pore concentration section 23 is formed, the arranged from below at the second position rectangle portion of the five rectangular sections and can thus be referred to as adjacent to the middle rectangular section.

The exhaust pipe 150 out 7 (b) Although similar in terms of the structure of the surface coating 20 the exhaust pipe off 7 (a) but the total thickness of the mixed layer is 22b about the same as the thickness of the non-crystalline inorganic material layer 21 and the mixed layer 22a combined.

The pore concentration section 23 So is the middle rectangle section of the five rectangular sections and is in the position where the surface coating 20 is divided into two parts in the thickness direction.

Now, the sequence of steps of a method of manufacturing an exhaust pipe according to the present embodiment will be described.

A method for manufacturing an exhaust pipe according to the third embodiment of the first invention comprises the steps of: preparing a metal substrate,
Preparing a base material composition for a surface coating,
applying the base composition several times to form the surface coating on the metal substrate and forming the surface coating by firing, and characterized in that:
in step of forming the surface coating, a step of forming a lower layer of the surface coating is carried out, wherein the application of the base composition for forming the surface coating and the firing is performed at least once;
the surface of the lower layer of the surface coating is roughened, and
by forming the base composition for forming the surface coating on the lower layer of the surface coating and baking, an upper layer of the surface coating is formed, and at the same time pores are formed between the lower layer of the surface coating and the upper layer of the surface coating.

Now, the method of manufacturing the exhaust pipe of the third embodiment of the first invention will be described with reference to the example of manufacturing an exhaust pipe 140 the first embodiment of the first invention are described schematically in 7 (a) is shown.

• (1) Ebenso wie in den Herstellungsschritten (1) bis (3) der Abgasleitung der ersten Ausführungsform der ersten Erfindung wurden ein Substrat, eine Grundstoffzusammensetzung für eine Mischschicht und eine Grundstoffzusammensetzung für eine Schicht aus nicht-kristallinem anorganischem Material vor- bzw. zubereitet.
• (2) Ebenso wie in den Herstellungsschritten (5) bis (6) der Abgasleitung der ersten Ausführungsform der ersten Erfindung wird auf dem Substrat die untere Oberflächenbeschichtung (Mischschicht) ausgebildet.
• 8(a) zeigt den Zustand mit ausgebildeter Mischschicht 22b auf dem Substrat 10.
• (3) Die Oberfläche der unteren Oberflächenbeschichtung wird einer Aufrauungsbehandlung unterzogen.

8 (a) . 8 (b) and 8 (c) 11 are sectional views schematically showing a part of a step for manufacturing an exhaust pipe according to the third embodiment of the first invention.

• (1) As well as the production steps (1) to (3) of the exhaust pipe of the first embodiment of the first invention, a substrate, a composite base material composition and a base material composition for a non-crystalline inorganic material layer were prepared.
• (2) As in the manufacturing steps (5) to (6) of the exhaust pipe of the first embodiment of the first invention, the lower surface coating (mixed layer) is formed on the substrate.
• 8 (a) shows the condition with the mixed layer formed 22b on the substrate 10 ,
• (3) The surface of the lower surface coating is subjected to a roughening treatment.

8 (b) shows the surface of the mixed layer 22b after performing the roughening treatment. As a method for the roughening treatment, a sand blast treatment, an etching treatment, etc. may be used.

The surface roughness Rz _{JIS of} the roughened surface is preferably 0.1 to 100 μm.

The surface roughness Rz _JIS can be calculated from the Japanese Industrial Standard JIS B 0601 (2001) measure up.

When the surface roughness Rz _{JIS of} the roughened surface is less than 0.1 μm, insufficient pores are formed between the lower surface coating and the upper surface coating, and therefore, the thermal shock absorbing effect of the surface coating decreases. On the other hand, when the surface roughness Rz _{JIS of} the roughened surface is more than 100 μm, the contact area between the lower surface coating and the upper surface coating decreases, so that the adhesion performance between the lower surface coating and the upper surface coating decreases.

• (4) Auf der Oberfläche der unteren Oberflächenbeschichtung, die einer Aufrauungsbehandlung unterzogen wurde, wird eine Grundstoffzusammensetzung zum Ausbilden einer Oberflächenbeschichtung (Grundstoffzusammensetzungen für eine Schicht aus nicht-kristallinem anorganischem Material) aufgetragen, wodurch nach dem Trocknen und Brennen eine Schicht aus nicht-kristallinem anorganischem Material ausgebildet wird.

The surface roughness Rz _{JIS of} the roughened surface can be determined according to JIS B 0601 (2001) Using a Handysurf E-35B from Tokyo Seimitsu Co., Ltd. be measured.

• (4) On the surface of the lower surface coating which has been subjected to a roughening treatment, a base material composition for forming a surface coating (base compositions for a layer of non-crystalline inorganic material) is applied, whereby a layer of non-crystalline inorganic material after drying and firing Material is formed.

8 (c) shows that on the mixed layer 22b formed layer of non-crystalline inorganic material 21 ,

• (5) Ebenso wie im Herstellungsschritt (8) der Abgasleitung der ersten Ausführungsform der ersten Erfindung wird auf dem Substrat die obere Oberflächenbeschichtung (Mischschicht) ausgebildet (Darstellung entfällt).

By forming a layer of non-crystalline inorganic material on the surface of the lower surface coating (mixed layer) which has been subjected to a roughening treatment, pores can be formed at the interface of the two layers. Therefore, in the exhaust pipe manufacturing method of the present embodiment, a pore concentration portion becomes 23 formed at a position containing a surface which has been subjected to a roughening treatment.

• (5) As in the manufacturing step (8) of the exhaust pipe of the first embodiment of the first invention, the upper surface coating (mixed layer) is formed on the substrate (not shown).

In the above-described sequence, an exhaust pipe of the present embodiment (shown in FIG 7 (a) schematically shown exhaust pipe 140 ) getting produced.

The exhaust pipe 140 out 7 (a) is just one example of an exhaust pipe of the third embodiment of the first invention, and in the surface coating of the exhaust pipe of the third embodiment, the position of the pore concentration section is not limited to the position that the interface between the lower mixed layer and the upper layer of non-crystalline inorganic material contains.

In addition, as with the exhaust pipe of the second embodiment, the surface coating may include only one layer of non-crystalline inorganic material or only one mixed layer.

• (7) Bei dem Herstellungsverfahren für eine Abgasleitung der vorliegenden Ausführungsform wird beim Ausbilden der Oberflächenbeschichtung ein Schritt des Aufrauens der Oberfläche der unteren Oberflächenbeschichtung durchgeführt. Wenn auf die aufgeraute Oberfläche der unteren Schicht der Oberflächenbeschichtung die Grundstoffzusammensetzung zum Ausbilden der Oberflächenbeschichtung aufgetragen wird, werden nicht alle Vertiefungen auf der rauen Fläche der unteren Schicht der Oberflächenbeschichtung mit der Grundstoffzusammensetzung zum Ausbilden der Oberflächenbeschichtung gefüllt; stattdessen bleiben zwischen den Vertiefungen auf der rauen Fläche der unteren Schicht der Oberflächenbeschichtung und der oberen Schicht der Grundstoffzusammensetzung zum Ausbilden der Oberflächenbeschichtung Lufträume zurück. Nach dem Brennen werden die Lufträume zu Poren, so dass örtlich begrenzt zwischen der unteren Schicht der Oberflächenbeschichtung und der oberen Schicht unabhängige Poren ausgebildet werden. So ist es möglich, eine Abgasleitung herzustellen, die an einer gewünschten Position der Oberflächenbeschichtung einen Porenkonzentrationsabschnitt aufweist.

With the exhaust pipe of the present embodiment, the effects (1) to (5) of the exhaust pipe of the first embodiment of the first invention can be achieved. Further, with the exhaust pipe manufacturing method of the present embodiment, the following effect can be obtained.

• (7) In the exhaust pipe manufacturing method of the present embodiment, a step of roughening the surface of the lower surface coating is performed in forming the surface coating. When the primer composition for forming the surface coating is applied to the roughened surface of the lower layer of the surface coating, not all of the recesses on the rough surface of the lower layer of the surface coating are filled with the primer composition for forming the surface coating; instead, air spaces are left between the recesses on the rough surface of the lower layer of the surface coating and the upper layer of the base material composition for forming the surface coating. After firing, the air spaces become pores so that independent pores are formed locally between the lower layer of the surface coating and the upper layer. Thus, it is possible to produce an exhaust pipe having a pore concentration portion at a desired position of the surface coating.

Twelfth embodiment

In the same procedure as in the first embodiment of the first embodiment of the first invention, a substrate, a mixed-layer base material composition X and a non-crystalline inorganic material-Z base material composition were prepared.

First, in the same procedure as in the first embodiment of the first embodiment of the first invention, by spray coating, the composite base material compositions X were applied to the surface of a plate-shaped substrate and then dried in a dryer at 70 ° C for 20 minutes. Next, it was subjected to a firing treatment in air at 850 ° C for 15 minutes to form a surface coating (mixed layer, first layer). The thickness of the mixed layer was 20 μm.

Then, the surface of the mixed layer was roughened by a sand blast treatment. The surface roughness Rz _{JIS of} the surface of the roughened mixed layer was 10 μm.

The surface roughness Rz _{JIS of} the roughened surface was determined according to JIS B 0601 (2001) Using a Handysurf E-35B from Tokyo Seimitsu Co., Ltd. measured.

Next, on the roughening-treated surface of the mixed layer in the same procedure as in the first embodiment of the first embodiment of the first invention by spray coating, the base composition for a layer of non-crystalline inorganic material Z was applied and set at 70 ° C for 20 minutes Drier dried. Then, it was subjected to a firing treatment in air at 850 ° C for 15 minutes to form a surface coating (non-crystalline inorganic material layer, second layer). The thickness of the non-crystalline inorganic material layer was 20 μm.

On the surface of the non-crystalline inorganic material layer was then spray-coated the base material composition for a mixed layer X and dried at 70 ° C for 20 minutes in a dryer. Next, it was subjected to a firing treatment in air at 850 ° C for 15 minutes to form a surface coating (mixed layer, third layer). The thickness of the mixed layer was 20 μm.

An exhaust pipe was made based on the procedure described above.

Table 5 shows an overview of the structure of the surface coating of the exhaust pipe produced in the twelfth embodiment.

In the exhaust pipe produced in the twelfth embodiment, the pore concentration portion was at the position containing the interface between the first layer (lower mixed layer on the substrate side) and the second layer (layer of non-crystalline inorganic material). This position of the pore concentration section is indicated in Table 5 as "between first and second layers".

In the column "roughening" in Table 5, in the case where the individual layers have been subjected to a roughening treatment, "Yes" is given, and in the case where they have not been roughened, "No" is given. The layer referred to as the "third layer" is the one appearing on the surface of the exhaust pipe; as its surface has not undergone roughening treatment, it lacks the "roughening" column.

Thirteenth to nineteenth embodiment

Exhaust pipes were produced in the same method as for the twelfth embodiment, but the composition of the surface coating was changed as shown in Table 5.

The thirteenth to nineteenth embodiments differ from the twelfth embodiment in the following points.

In the thirteenth embodiment, the thickness of the first layer having the raw material composition for a non-crystalline inorganic material layer Z was 20 μm, the thickness of the second layer having the mixed layer base material composition was X 20 μm, and the thickness of the third layer was one with the base material composition Layer of non-crystalline inorganic material Z 20 μm.

The roughened surface was formed on the surface of the first layer.

In the fourteenth embodiment, the thickness of the first layer having the mixed-coat base material X was 14 μm, the thickness of the second layer containing the non-crystalline inorganic material layer Z was 20 μm, and the thickness of the third layer was one with the base-material composition Mixed layer X 20 μm. The roughened surface was formed on the surface of the second layer.

In the fifteenth embodiment, the thickness of the first layer having the raw material composition for a non-crystalline inorganic material layer Z was 20 μm, the thickness of the second layer having the mixed-layer base material composition was X 20 μm, and the thickness of the third layer was one with the base material composition Layer of non-crystalline inorganic material Z 20 μm.

The roughened surface was formed on the surface of the second layer.

In the sixteenth embodiment, the thickness of the first layer having the composite base material composition X was 40 μm, and the thickness of the second layer was the same Base material composition for a layer of non-crystalline inorganic material Z 20 μm and the thickness of the third layer with the base material composition for a mixed layer X 20 μm.

The roughened surface was formed on the surface of the first layer.

In the seventeenth embodiment, the thickness of the first layer having the base material composition for a non-crystalline inorganic material layer Z was 40 μm, the thickness of the second layer having the base material composition for a mixed layer X was 20 μm, and the thickness of the third layer was one with the base material composition Layer of non-crystalline inorganic material Z 20 μm.

The roughened surface was formed on the surface of the first layer.

In the eighteenth embodiment, the thickness of the first layer having the mixed-layer base material composition X was 20 μm, the thickness of the second composite-base composite layer X was 20 μm, and the third layer containing the mixed-layer base material composition was X 20 μm.

The roughened surface was formed on the surface of the first layer.

In the nineteenth embodiment, the thickness of the first layer having the base composition for a non-crystalline inorganic material layer Z was 20 μm, the thickness of the second layer having the base composition for a non-crystalline inorganic material layer was Z 20 μm, and the thickness of the third Layer with the base material composition for a layer of non-crystalline inorganic material Z 20 μm. The roughened surface was formed on the surface of the first layer.

In the fourteenth and fifteenth embodiments, the surface of the layer shown as the second layer was subjected to a roughening treatment, and a pore concentration section was formed between the second and third layers.

In the sixteenth and seventeenth embodiments, as in 7 (b) 1, the layer 1 was formed to be 40 μm thick, and by subjecting the surface of the layer shown as a first layer to a roughening treatment, a pore concentration section was formed between the first and second layers. That is, the pore concentration section was in the middle rectangle section of the five rectangular sections, that is, at the position where the surface coating 20 is divided into two parts in the thickness direction, formed.

In the eighteenth embodiment, a surface coating comprising only mixed layers was formed, and in the nineteenth embodiment, a surface coating comprising only layers of non-crystalline inorganic material was formed.

Twentieth to Twenty-third Embodiment

Exhaust pipes were produced in the same method as for the twelfth embodiment, but the composition of the surface coating was changed as shown in Table 5.

The twentieth to twenty-third embodiments differ from the twelfth embodiment in the following points.

In the twentieth embodiment, the thickness of the first layer having the composite base material composition X was 50 μm, the thickness of the second layer containing the base material composition for the non-crystalline inorganic material layer Z was 30 μm, and no third layer was formed.

The roughened surface was formed on the surface of the first layer.

In the twenty-first embodiment, the thickness of the first layer having the raw material composition for a non-crystalline inorganic material layer X was 30 μm, the thickness of the second layer having the mixed-layer base material composition X was 50 μm, and no third layer was formed.

The roughened surface was formed on the surface of the first layer.

In the twenty-second embodiment, the thickness of the first layer having the mixed-layer base material composition X was 20 μm, the thickness of the second layer containing the base material composition for non-crystalline inorganic material layer Z was 200 μm, and no third layer was formed.

The roughened surface was formed on the surface of the first layer.

In the twenty-third embodiment, the thickness of the first layer having the base material composition for a non-crystalline inorganic material layer Z was 100 μm, the thickness of the second layer having the base material composition for a non-crystalline inorganic material layer Z was 100 μm, and none became third layer formed.

The roughened surface was formed on the surface of the first layer.

In these embodiments, the surface of the layer shown as the first layer was subjected to a roughening treatment, whereby a pore concentration section was formed between the first and second layers. Further, in these embodiments, no third layer was provided.

• X: Grundstoffzusammensetzung für eine Mischschicht (kristallines anorganisches Material:nicht-kristallines anorganisches Material:organisches Bindemittel = 4:6:geringfügige Menge)
• Z: Grundstoffzusammensetzung für eine Schicht aus nicht-kristallinem anorganischem Material (nicht-kristallines anorganisches Material:organisches Bindemittel = 10:geringfügige Menge)

Tabelle 6 Abplatzung bei Wärmeschockprüfung Spezifischer Durchgangswiderstand Durchschlagfestigkeit (500 V) Abstrahlungsrate Wärmeleitfähigkeit der Oberflächenbeschichtung Gesamtbewertung [Ωm] [–] [W/mK] Zwölftes Ausführungsbeispiel Nein 3,E+12 Ja 0,82 1,5 Sehr gut Dreizehntes Ausführungsbeispiel Nein 7,E+12 Ja 0,81 1,0 Sehr gut Vierzehntes Ausführungsbeispiel Nein 3,E+12 Ja 0,82 1,5 Sehr gut Fünfzehntes Ausführungsbeispiel Nein 7,E+12 Ja 0,81 1,0 Sehr gut Sechzehntes Ausführungsbeispiel Nein 3,E+12 Ja 0,82 1,6 Sehr gut Siebzehntes Ausführungsbeispiel Nein 8,E+12 Ja 0,81 0,9 Sehr gut Achtzehntes Ausführungsbeispiel Nein 1,E+08 Ja 0,82 2,0 Gut Neunzehntes Ausführungsbeispiel Nein 1,E+13 Ja 0,81 0,5 Sehr gut Zwanzigstes Ausführungsbeispiel Nein 4,E+12 Ja 0,81 1,4 Sehr gut Einundzwanzigstes Ausführungsbeispiel Nein 6,E+12 Ja 0,82 1,1 Sehr gut Zweiundzwanzigstes Ausführungsbeispiel Nein 9,E+12 Ja 0,81 0,6 Sehr gut Dreiundzwanzigstes Ausführungsbeispiel Nein 1,E+13 Ja 0,81 2,0 Sehr gut A judgment was made according to the first embodiment of the first embodiment of the first invention, and the evaluation results for the individual embodiments are shown in Table 6. Table 5

• X: base material composition for mixed layer (crystalline inorganic material: non-crystalline inorganic material: organic binder = 4: 6: slight amount)
• Z: base material composition for non-crystalline inorganic material layer (non-crystalline inorganic material: organic binder = 10: slight amount)

Table 6 Chipping at thermal shock test Specific volume resistance Dielectric strength (500 V) radiation rate Thermal conductivity of the surface coating Overall [Ohm-m] [-] [W / mK] Twelfth embodiment No 3, E + 12 Yes 0.82 1.5 Very well Thirteenth embodiment No 7, E + 12 Yes 0.81 1.0 Very well Fourteenth embodiment No 3, E + 12 Yes 0.82 1.5 Very well Fifteenth embodiment No 7, E + 12 Yes 0.81 1.0 Very well Sixteenth embodiment No 3, E + 12 Yes 0.82 1.6 Very well Seventeenth embodiment No 8, E + 12 Yes 0.81 0.9 Very well Eighteenth embodiment No 1, E + 08 Yes 0.82 2.0 Well Nineteenth embodiment No 1, E + 13 Yes 0.81 0.5 Very well Twentieth Embodiment No 4, E + 12 Yes 0.81 1.4 Very well Twenty-first embodiment No 6, E + 12 Yes 0.82 1.1 Very well Twenty-second embodiment No 9, E + 12 Yes 0.81 0.6 Very well Twenty-third embodiment No 1, E + 13 Yes 0.81 2.0 Very well

The overall judgment of the twelfth to seventeenth embodiment and the nineteenth to the twenty-third embodiment was "Very Good" and the overall rating of the eighteenth embodiment was "Good".

Since a pore concentration portion was present in both embodiments, no flaking occurred in the thermal shock test, and damage to the surface coating could be prevented.

Since the exhaust pipe of the twelfth to seventeenth embodiment and the nineteenth to the twenty-third embodiment had a surface coating comprising layers of non-crystalline inorganic material, the volume resistivity was 1, E + 10 (Ωm) high.

On the other hand, since the exhaust pipe of the eighteenth embodiment had a surface coating comprising only mixed layers, the volume resistivity was 1, E + 08 (Ωm) low.

In the twelfth to twenty-third embodiments, since there was a pore concentration portion, no flaking occurred in the thermal shock test, and damage of the surface coating could be prevented.

Fourth embodiment

Hereinafter, a fourth embodiment will be described, which is an embodiment of an exhaust pipe of the first invention.

In the exhaust pipe of the fourth embodiment of the first invention, the number of pore concentration sections is two, and the pore concentration sections are located at positions where the surface coating is divided into three in the thickness direction. Otherwise, its structure corresponds to the exhaust pipe of the first embodiment of the first invention.

9 (a) and 9 (b) 11 are sectional views schematically showing an example of a sectional area of the exhaust pipe according to the fourth embodiment of the first invention.

Off at the exhaust pipe 9 (a) For example, as with the exhaust pipe of the first embodiment of the first invention, a pore concentration portion is formed by blending a pore forming material into the base composition for forming a surface coating.

At the exhaust pipe 160 out 9 (a) the surface coating comprises a mixed layer 22a , a layer of non-crystalline inorganic material 21a , a mixed layer 22b , a layer of non-crystalline inorganic material 21b and a mixed layer 22c ,

The thickness of the mixed layer 22a , the layer of non-crystalline inorganic material 21a , the mixed layer 22b , the layer of non-crystalline inorganic material 21b and the mixed layer 22c is equal to. For this reason, the mixed layer 22a , the layer of non-crystalline inorganic material 21a , the mixed layer 22b , the layer of non-crystalline inorganic material 21b and the mixed layer 22c be equated with the individual five rectangular sections.

The layer of non-crystalline inorganic material 21a is a pore concentration section 23a and the layer of non-crystalline inorganic material 21b is a pore concentration section 23b ,

That is, there are two pore concentration layers per area of the substrate, with the two layers being of non-crystalline inorganic material 21a and 21b leading to the mixed layer 22b are adjacent, which forms the middle of the five rectangular sections, the pore concentration sections 23 are.

The pore concentration sections 23a and 23b are thus present at the position at which the surface coating 20 is divided into three parts in the thickness direction.

At the exhaust pipe 170 out 9 (b) Similarly to the exhaust pipe of the first embodiment of the first invention, a pore concentration portion is formed by roughening the lower layer of the surface coating.

At the exhaust pipe 170 out 9 (b) includes the surface coating 20 a mixed layer 22a , a layer of non-crystalline inorganic material 21 and a mixed layer 22b ,

There are two pore concentration sections, the pore concentration section 23a the rectangle section is that of the interface between the mixed layer 22a on the surface side of the surface coating (upper layer) and the layer of non-crystalline inorganic material 21 contains, and the pore concentration section 23b the rectangle section is the interface between the mixed layer 22b closer to the substrate 10 is (lower layer) and the layer of non-crystalline inorganic material 21 contains.

The pore concentration section 23a and the pore concentration section 23b are the two rectangular sections of the five rectangular sections adjacent to the middle rectangular section and the pore concentration section 23a and the pore concentration section 23b are present at the positions where the surface coating 20 is divided into three parts in the thickness direction.

The exhaust pipe of the present embodiment can be manufactured by proceeding as well as the exhaust pipe manufacturing method of the first embodiment or the exhaust pipe manufacturing method of the third embodiment of the first invention except that the pore concentration section forming step (Application of the base material composition for a pore concentration section and roughening treatment of the surface layer) is carried out twice (in two places).

With the exhaust pipe of the present embodiment, the effects (1) to (3) and (5) to (7) of the exhaust pipe of the first embodiment of the first invention and the exhaust pipe of the third embodiment of the first invention can be obtained.

• (8) Bei der Abgasleitung der vorliegenden Ausführungsform liegen pro Fläche des Substrats zwei Porenkonzentrationsschichten vor, und die Rechteckabschnitte, die die Porenkonzentrationsabschnitte bilden, sind die zwei zum mittleren Rechteckabschnitt der fünf Rechteckabschnitte benachbarten Rechteckabschnitte. Das heißt, die Porenkonzentrationsabschnitte liegen an den Positionen vor, an denen die Oberflächenbeschichtung in Dickenrichtung dreigeteilt ist.

In addition, the following effect can additionally be achieved.

• (8) In the exhaust pipe of the present embodiment, there are two pore concentration layers per area of the substrate, and the rectangular portions constituting the pore concentration portions are the two rectangular portions adjacent to the middle rectangle portion of the five rectangle portions. That is, the pore concentration sections exist at the positions where the surface coating is divided into three in the thickness direction.

When the pore concentration sections are at the positions where the surface coating is divided into three in the thickness direction, the surface coating is divided by the pore concentration sections into three parts of equal thickness. The amount of thermal shock applied to the surface coating then corresponds to that which would be present in the case of a thin surface coating, so that damage to the surface coating can be effectively prevented.

Twenty-fourth embodiment

According to the procedure of the first embodiment of the first embodiment of the first invention, an exhaust pipe was manufactured, wherein the composition of the surface coating was changed as shown in Table 7.

The twenty-fourth embodiment differs from the first embodiment of the first embodiment of the first invention as follows.

In the twenty-fourth embodiment, the thickness of the first layer having the mixed-layer base material X was 30 μm, the thickness of the second layer containing the non-crystalline inorganic material layer Z was 10 μm, and the thickness of the third layer was the same as the base material composition Mixed layer X 30 μm, the thickness of the fourth layer with the base material composition for a layer of non-crystalline inorganic material Z 10 μm, and the thickness of the fifth layer having the base material composition for a mixed layer X is 30 μm. The formation of the fourth and fifth layers was performed such that a surface coating was formed on the third layer in the same process as that for forming the first to third layers.

In the procedure described above, a pore concentration section was formed on each of the second and fourth layers.

Twenty-fifth embodiment

According to the procedure of the twelfth embodiment of the third embodiment of the first invention, an exhaust pipe was manufactured, wherein the composition of the surface coating was changed as shown in Table 7.

The twenty-fifth embodiment differs from the twelfth embodiment of the third embodiment of the first invention as follows.

In the fourteenth embodiment, the thickness of the first layer having the composite composition for a mixed layer X was 25 μm, the thickness of the second layer containing the base composition for a non-crystalline inorganic material layer Z was 20 μm, and the thickness of the third layer was one with the base material composition Mixed layer X 20 μm.

The roughened surface was formed on the surface of the first layer and the second layer.

In this way, a pore concentration section was formed in two places, namely, between the first and second layers and between the second and third layers.

The pore concentration sections were located at the position containing the interface between the first layer (lower mixed layer on the substrate side, first layer) and the second layer (layer of non-crystalline inorganic material, second layer) and the rectangular section forming the interface between the second layer and third layer (mixed layer on the surface side of the surface coating (upper layer), third layer).

The column "Pore-forming material or roughening" in Table 7 indicates in the twenty-fourth embodiment whether a pore-forming material was present in the base material composition for forming a surface coating, and in the 25th embodiment, whether the surface of the respective layer had been subjected to a roughening treatment.

• X: Grundstoffzusammensetzung für eine Mischschicht (kristallines anorganisches Material:nicht-kristallines anorganisches Material:organisches Bindemittel = 4:6:geringfügige Menge)
• Z: Grundstoffzusammensetzung für eine Schicht aus nicht-kristallinem anorganischem Material (nicht-kristallines anorganisches Material:organisches Bindemittel = 10:geringfügige Menge)

Tabelle 8 Abplatzung bei Wärmeschockprüfung Spezifischer Durchgangswiderstand Durchschlagfestigkeit (500 V) Abstrahlungsrate Wärmeleitfähigkeit der Oberflächenbeschichtung Gesamtbewertung [Ωm] [–] [W/mK] Vierundzwanzigstes Ausführungsbeispiel Nein 4,E+12 Ja 0,82 1,4 Sehr gut Fünfundzwanzigstes Ausführungsbeispiel Nein 3,E+12 Ja 0,82 1,5 Sehr gut A judgment was made according to the first embodiment of the first embodiment of the first invention, and the evaluation results for the individual embodiments are shown in Table 8. Table 7

• X: base material composition for mixed layer (crystalline inorganic material: non-crystalline inorganic material: organic binder = 4: 6: slight amount)
• Z: base material composition for non-crystalline inorganic material layer (non-crystalline inorganic material: organic binder = 10: slight amount)

Table 8 Chipping at thermal shock test Specific volume resistance Dielectric strength (500 V) radiation rate Thermal conductivity of the surface coating Overall [Ohm-m] [-] [W / mK] Twenty-fourth embodiment No 4, E + 12 Yes 0.82 1.4 Very well Twenty-fifth embodiment No 3, E + 12 Yes 0.82 1.5 Very well

In both the twenty-fourth and twenty-fifth embodiments, the result was "very good".

In the twenty-fourth and twenty-fifth embodiments, since there was a pore concentration portion, no flaking occurred in the thermal shock test, and damage to the surface coating could be prevented.

Fifth embodiment

Hereinafter, a fifth embodiment will be described, which is an embodiment of an exhaust pipe of the first invention.

The surface coating of an exhaust pipe of a fifth embodiment of the first invention has a blind pore in which a part communicates with the outside of the exhaust pipe.

10 FIG. 10 is a sectional view schematically showing an example of a sectional surface of an exhaust pipe according to the fifth embodiment of the first invention. FIG.

The surface coating of the exhaust pipe 180 The fifth embodiment of the first invention has a blind pore 34 on, with a part in connection with the exterior of the exhaust pipe is.

Otherwise, its structure corresponds to the exhaust pipe of the first embodiment of the first invention 1 ,

A blind pore is a pore having a part communicating with the exterior of the exhaust pipe, or in other words a recessed part exposed at the surface coating. Blind pores do not connect the exterior of the exhaust pipe to the surface of the substrate and do not extend to the surface of the substrate.

The exhaust pipe of the present embodiment can be manufactured in the exhaust pipe manufacturing method of the first embodiment of the first invention, however, to form the top layer, namely the surface coating, as the base composition for forming a surface coating, a base material composition is used to form a pore concentration section.

With the exhaust pipe of the present embodiment, the effects (1) to (5) of the exhaust pipe of the first embodiment of the first invention can be achieved. It is also possible that dummy pores are also provided in the exhaust pipe of the third embodiment of the first invention or in the exhaust pipe of the fourth embodiment of the first invention. In this case, it is possible to obtain the effect (7) of the method of manufacturing the exhaust pipe of the third embodiment of the first invention and the effect (8) of the method of manufacturing the exhaust pipe of the fourth embodiment of the first invention.

Sixth embodiment

Hereinafter, a sixth embodiment which is an embodiment of an exhaust pipe of the second invention will be described with reference to the drawings.

An exhaust pipe of the second invention comprises a substrate of metal and
a surface coating formed on the surface of the substrate containing a non-crystalline inorganic material, and characterized in that
a surface coating comprises a layer of non-crystalline inorganic material containing a non-crystalline inorganic material and a mixed layer containing a non-crystalline inorganic material and a crystalline inorganic material,
the surface coating has independent pores,
the independent pores do not interconnect the exterior of the exhaust conduit and the surface of the substrate and are localized in the interface portion between the non-crystalline material layer and the mixed layer.

11 FIG. 10 is a sectional view schematically showing an example of a sectional surface of an exhaust pipe according to the sixth embodiment of the second invention. FIG.

At the exhaust pipe 200 out 11 includes the surface coating 220 a mixed layer 222a , a layer of non-crystalline inorganic material 221 and a mixed layer 222b ,

The composition of the mixed layers 222a . 222b the exhaust pipe according to the sixth embodiment of the second invention is the same as the composition of the mixed layer 22 the first embodiment of the first invention.

The composition of the layer of non-crystalline inorganic material 221 the exhaust pipe according to the sixth embodiment of the second invention is the same as the composition of the non-crystalline inorganic material layer 21 the first embodiment of the first invention.

The thickness of the surface coating 220 is 25 to 1,000 μm.

The surface coating 220 has independent pores 233 on, and the independent pores 233 connect the outside of the exhaust pipe 200 and the surface of the substrate 10 not with each other.

The independent pores 233 are localized at the interface between the mixed layer 222b and the layer of non-crystalline inorganic material 221 arranged.

The following is based on 11 the localized presence at the interface between the mixed layer and the non-crystalline inorganic material layer will be described.

The localized presence at the interface between the mixed layer and the non-crystalline inorganic material layer indicates a state in which, in a range within 40% of the surface coating thickness of all independent pores existing in the entire surface coating, 60th in area % or more of the independent pores are present.

At the exhaust pipe 200 is the surface of the mixed layer 222b not smooth, but roughened, and between the mixed layer 222b and the layer of non-crystalline inorganic material 221 are independent pores 233 in front.

The interface between the mixed layer and the non-crystalline inorganic material layer is determined by the following method.

Through the part where the roughened surface of the lower layer (at the exhaust pipe 200 out 11 the mixed layer 222b ) is the deepest, becomes a line 240L pulled through the part where the roughened surface of the lower layer, which is highest, becomes a line 240H pulled, and between the line 240L and 240H becomes a centerline 240M drawn.

The centerline set in this way 240M is the centerline of the interface section.

The lines 240L . 240H and 240M are parallel to each other.

The thickness of the surface coating 220 is determined. As a method of determining the thickness of the surface coating 220 is a method, starting from the surface of the surface coating 220 the thickness to the substrate surface is determined, which is the same method as that used to determine the rectangular sections in the first embodiment of the first invention.

In addition, the range of 40% of the thickness of the surface coating 220 with the center line 240M of the interface portion as the center. Specifically, the side above the center line applies 240M as a range of 20% of the thickness of the surface coating 220 , and it becomes an interface line 250H drawn. The side below the midline 240M is considered as a range of 20% of the thickness of the surface coating 220 , and it becomes an interface line 250L drawn.

The lines 250L . 250H and 240M are parallel to each other.

The area within 40% of the surface coating thickness is the area between the line 250H and the line 250L ; this area is the interface area.

The area of the independent pores present in the entire surface coating is determined in the same manner as described for the first embodiment of the first invention. In defining the area of the independent pores, the definition of a pore in the surface coating is the same as that described for the first embodiment of the first invention.

In the exhaust pipe of the sixth embodiment of the second invention, in terms of the area of the independent pores in the surface coating, there are 60% or more of the independent pores in the interface portion in area.

In the exhaust pipe of the sixth embodiment of the second invention, the pores are localized in the interface portion of the lower layer of the surface coating and the upper layer of the surface coating. At the exhaust pipe 200 of the sixth embodiment of the second invention 11 the lower layer of the surface coating is the mixed layer 222b and at the top layer the surface coating around the layer of non-crystalline inorganic material 221 ,

However, in the exhaust pipe of the sixth embodiment of the second invention, unlike the exhaust pipe of the third embodiment of the first invention, it is not absolutely necessary to have a pore concentration portion as defined in the case where the surface coating is cut and five rectangular portions are set ,

12 is a view that looks for the exhaust pipe 11 the case of a surface coating with five rectangular sections 220A . 220B . 220C . 220D and 220E shows.

At the exhaust pipe 200 out 12 the boundary lines of the bottom of the second rectangle section 220D and the middle rectangle section 220C and the center of the interface portion, and in the interface portion between the mixed layer 222b and the layer of non-crystalline inorganic material 221 are locally independent pores 233 in front.

If the surface coating in such an aspect comprises five rectangular sections, it is possible that neither in the second rectangular section 220D from below still in the middle rectangle section 220C of all the independent pores present in the entire surface coating, with respect to the pore area, 30% or more of the independent pores are present. That is, there is no pore concentration portion as defined in the case where the surface coating is cut and five rectangle portions are set, so that it is not the exhaust pipe of the third embodiment of the first invention in this case. However, in the interface portion of the mixed layer 222b and the layer of non-crystalline inorganic material 221 localized independent pores 233 so that it is an exhaust pipe according to the sixth embodiment of the second invention.

An aspect in which, as in the exhaust pipe of the third embodiment of the first invention, the part containing the interface between the lower layer of the surface coating and the upper layer of the surface coating is regarded as a pore concentration section, falls under an exhaust pipe of the sixth embodiment of the second invention. when the independent pores are localized in the interface portion of the mixed layer and the non-crystalline inorganic material layer.

Now, the sequence of steps of a method of manufacturing an exhaust pipe according to the present embodiment will be described.

A method for manufacturing an exhaust pipe according to the sixth embodiment of the second invention comprises the steps of: preparing a metal substrate,
Preparing a base material composition for a surface coating,
applying the base composition several times to form the surface coating on the metal substrate and forming the surface coating by firing, and characterized in that:
in step of forming the surface coating, a step of forming a lower layer of the surface coating is carried out, wherein the application of the base composition for forming the surface coating and the firing is performed at least once;
the surface of the lower layer of the surface coating is roughened, and
by forming the base composition for forming the surface coating on the lower layer of the surface coating and baking, an upper layer of the surface coating is formed, and at the same time pores are formed between the lower layer of the surface coating and the upper layer of the surface coating.

• (1) Ebenso wie in den Herstellungsschritten (1) bis (3) der Abgasleitung der ersten Ausführungsform der ersten Erfindung werden ein Substrat, eine Grundstoffzusammensetzungen für eine Mischschicht und eine Grundstoffzusammensetzung für eine Schicht aus nicht-kristallinem anorganischem Material vor- bzw. zubereitet.
• (2) Ebenso wie in den Herstellungsschritten (5) bis (6) der Abgasleitung der ersten Ausführungsform der ersten Erfindung wird auf dem Substrat die untere Oberflächenbeschichtung (Mischschicht) ausgebildet.
• (3) Die Oberfläche der unteren Oberflächenbeschichtung wird einer Aufrauungsbehandlung unterzogen.

Now, the method of manufacturing the exhaust pipe of the sixth embodiment of the second invention will be described with reference to the example of manufacturing an exhaust pipe 200 of the sixth embodiment of the second invention, which are schematically illustrated in FIG 11 is shown.

• (1) As well as the manufacturing steps (1) to (3) of the exhaust pipe of the first embodiment of the first invention, a substrate, a mixed layer base material composition and a non-crystalline inorganic material layer base composition are prepared.
• (2) As in the manufacturing steps (5) to (6) of the exhaust pipe of the first embodiment of the first invention, the lower surface coating (mixed layer) is formed on the substrate.
• (3) The surface of the lower surface coating is subjected to a roughening treatment.

As a method for the roughening treatment, a sand blast treatment, an etching treatment, etc. may be used.

The surface roughness Rz _{JIS of} the roughened surface is preferably 0.1 to 100 μm.

The surface roughness Rz _JIS can be calculated from the Japanese Industrial Standard JIS B 0601 (2001) measure up.

When the surface roughness Rz _{JIS of} the roughened surface is less than 0.1 μm, insufficient pores are formed between the lower surface coating and the upper surface coating, and therefore, the thermal shock absorbing effect of the surface coating decreases. On the other hand, when the surface roughness Rz _{JIS of} the roughened surface is more than 100 μm, the contact area between the lower surface coating and the upper surface coating decreases, so that the adhesion performance between the lower surface coating and the upper surface coating decreases.

• (4) Auf die Oberfläche der unteren Oberflächenbeschichtung, die einer Aufrauungsbehandlung unterzogen wurde, wird eine Grundstoffzusammensetzung zum Ausbilden einer Oberflächenbeschichtung (Grundstoffzusammensetzung für eine Schicht aus nicht-kristallinem anorganischem Material) aufgetragen, wodurch nach dem Trocknen und Brennen eine Schicht aus nicht-kristallinem anorganischem Material ausgebildet wird.

The surface roughness Rz _{JIS of} the roughened surface can be determined according to JIS B 0601 (2001) Using a Handysurf E-35B from Tokyo Seimitsu Co., Ltd. be measured.

• (4) On the surface of the lower surface coating, which has been subjected to a roughening treatment, a base coat composition (base composition for a layer of non-crystalline inorganic material) is applied, whereby after drying and firing, a non-crystalline inorganic layer Material is formed.

By forming a layer of non-crystalline inorganic material on the surface of the lower surface coating (mixed layer) subjected to a roughening treatment, independent pores can be formed in the interface portion of the two layers.

• (5) Ebenso wie im Herstellungsschritt (8) der Abgasleitung der ersten Ausführungsform der ersten Erfindung wird auf dem Substrat die obere Oberflächenbeschichtung (Mischschicht) ausgebildet.

Therefore, in the manufacturing method of the exhaust pipe of the present embodiment, independent pores are locally formed in the interface portion of the mixed layer and the non-crystalline inorganic material layer.

• (5) As in the manufacturing step (8) of the exhaust pipe of the first embodiment of the first invention, the upper surface coating (mixed layer) is formed on the substrate.

In the above-described sequence, an exhaust pipe of the present embodiment (shown in FIG 11 schematically shown exhaust pipe 200 ) getting produced.

• (9) Bei der Abgasleitung der vorliegenden Ausführungsform weist die Oberflächenbeschichtung unabhängige Poren auf, und die unabhängigen Poren verbinden das Äußere der Abgasleitung und die Oberfläche des Substrats nicht miteinander, und die unabhängigen Poren liegen örtlich begrenzt im Grenzflächenabschnitt der Mischschicht und der Schicht aus nicht-kristallinem anorganischem Material vor.

Hereinafter, the operations of the exhaust pipe of the present embodiment and the manufacturing method of the exhaust pipe of the present embodiment will be listed.

• (9) In the exhaust pipe of the present embodiment, the surface coating has independent pores, and the independent pores do not connect the outside of the exhaust pipe and the surface of the substrate with each other, and the independent pores are localized in the interface portion of the mixed layer and the non-porous layer. crystalline inorganic material.

It is believed that cracks that form in the surface coating due to exposure to heat first form on the surface of the surface coating and then spread in the thickness direction of the surface coating toward the substrate.

When a crack that has formed in the surface coating spreads and encounters an independent pore, the crack is prevented from spreading beyond the independent pore.

If the independent pores do not connect the outside of the exhaust pipe and the surface of the substrate and are localized in the interface portion between the non-crystalline material layer and the mixed layer, then if a crack is generated in the surface of the surface coating, it easily hits an independent pore localized in the interface portion between the non-crystalline material layer and the mixed layer, therefore, the crack can be prevented from spreading beyond the interface portion between the non-crystalline material layer and the mixed layer to the substrate.

• (10) In der Oberflächenbeschichtung der Abgasleitung der vorliegenden Ausführungsform ist ein kristallines anorganisches Material enthalten. Das kristalline anorganische Material enthält wenigstens ein Oxid aus der Gruppe Mangan, Eisen, Kupfer, Kobalt, Chrom und Aluminium.

Thus, damage to the surface coating can be prevented. For this reason, the exhaust pipe can ensure a high insulation performance.

• (10) In the surface coating of the exhaust pipe of the present embodiment, a crystalline inorganic material is contained. The crystalline inorganic material contains at least one of manganese, iron, copper, cobalt, chromium and aluminum.

Since oxides have a high infrared radiation rate, the radiation of the surface coating can be increased. When the irradiation rate of the surface coating is high, an exhaust pipe having excellent heat dissipation performance at high temperatures can be obtained.

• (11) Bei der Abgasleitung der vorliegenden Ausführungsform beträgt die Dicke der Oberflächenbeschichtung 25 bis 1.000 μm. Beträgt die Dicke der Oberflächenbeschichtung weniger als 25 μm, kann bei Verwendung als Abgasleitung keine ausreichende Isolationsleistung erreicht werden. Beträgt die Dicke der Oberflächenbeschichtung dagegen mehr als 1.000 μm, nimmt der Wärmeschock, der auf die Oberflächenbeschichtung einwirkt, zu, so dass die Oberflächenbeschichtung leichter beschädigt wird.
• (12) Bei dem Herstellungsverfahren für eine Abgasleitung der vorliegenden Ausführungsform wird beim Ausbilden der Oberflächenbeschichtung ein Schritt des Aufrauens der Oberfläche der unteren Oberflächenbeschichtung durchgeführt. Wenn auf die aufgeraute Oberfläche der unteren Schicht der Oberflächenbeschichtung die Grundstoffzusammensetzung zum Ausbilden der Oberflächenbeschichtung aufgetragen wird, werden nicht alle Vertiefungen auf der rauen Fläche der unteren Schicht der Oberflächenbeschichtung mit der Grundstoffzusammensetzung zum Ausbilden der Oberflächenbeschichtung gefüllt; stattdessen bleiben zwischen den Vertiefungen auf der rauen Fläche der unteren Schicht der Oberflächenbeschichtung und der oberen Schicht der Grundstoffzusammensetzung zum Ausbilden der Oberflächenbeschichtung Lufträume zurück. Nach dem Brennen werden die Lufträume zu unabhängigen Poren, so dass örtlich begrenzt zwischen der unteren Schicht der Oberflächenbeschichtung und der oberen Schicht unabhängige Poren ausgebildet werden.

In particular, the use of an oxide of aluminum contributes to the insulation performance of the exhaust pipe.

• (11) In the exhaust pipe of the present embodiment, the thickness of the surface coating is 25 to 1,000 μm. If the thickness of the surface coating is less than 25 μm, sufficient insulation performance can not be achieved when used as an exhaust pipe. On the other hand, if the thickness of the surface coating is more than 1,000 μm, the thermal shock that acts on the surface coating increases, so that the surface coating is more likely to be damaged.
• (12) In the exhaust pipe manufacturing method of the present embodiment, a step of roughening the surface of the lower surface coating is performed in forming the surface coating. When the primer composition for forming the surface coating is applied to the roughened surface of the lower layer of the surface coating, not all of the recesses on the rough surface of the lower layer of the surface coating are filled with the primer composition for forming the surface coating; instead, air spaces are left between the recesses on the rough surface of the lower layer of the surface coating and the upper layer of the base material composition for forming the surface coating. After firing, the air spaces become independent pores so that independent pores are formed locally between the lower layer of the surface coating and the upper layer.

In this way, an exhaust pipe can be produced in which there are locally independent pores in the interface portion of the lower layer of the surface coating and the upper layer.

Seventh embodiment

Hereinafter, a seventh embodiment will be described, which is an embodiment of an exhaust pipe of the second invention.

In the exhaust pipe of the seventh embodiment of the second invention, there are two interface portions in which independent pores are localized.

13 FIG. 10 is a sectional view schematically showing an example of a sectional surface of an exhaust pipe according to the seventh embodiment of the second invention. FIG.

At the exhaust pipe 270 out 13 For example, as with the exhaust pipe of the sixth embodiment of the second invention, independent pores are formed in the interface portion between the non-crystalline inorganic material layer and the mixed layer by roughening the lower layer of the surface coating.

At the exhaust pipe 270 out 13 the surface coating comprises a mixed layer 222a , a layer of non-crystalline inorganic material 221 and a mixed layer 222b ,

The number of interface portions determined by the method described with respect to the sixth embodiment of the second invention is two.

In the present embodiment, in the same method as in the sixth embodiment of the second invention, a center line 240mA and a midline 240MB the interface sections determined. In addition, in each case a range of 40% of the thickness of the surface coating 220 with the center line 240mA and the midline 240MB the interface sections determined as the center.

The areas thus determined within 40% of the thickness of the surface coating are the areas between the line 250ha and the line 250La or between the line 250Hb and 250lb ,

That is, both the area between the line 250ha and the line 250La as well as the area between the line 250Hb and 250lb is an interface section.

The exhaust pipe of the present embodiment has two (2) interface portions. When there are plural interface portions in the surface coating, the area of the independent pores in the individual interface portions is calculated respectively and when the sum of the area of the independent pores in the interface portions with respect to the area of all independent pores present in the surface coating is 60% or more it is an exhaust pipe of the second invention.

In the exhaust pipe of the present embodiment, the sum of the area of the independent pores in the two interface portions (the area between the line 250ha and the line 250La and the area between the line 250Hb and the line 250lb ) with respect to the area of all the independent pores present in the surface coating 60% or more.

The method of manufacturing the exhaust pipe of the present embodiment is carried out as well as the method of manufacturing the sixth embodiment of the second invention, except that the step of roughening treatment of the surface coating is performed twice (in two places).

With the exhaust pipe of the present embodiment, the effects (9) to (11) of the exhaust pipe of the sixth embodiment of the second invention can be obtained.

Eighth embodiment

In the following, an eighth embodiment will be described, which is an embodiment of an exhaust pipe of the second invention.

The surface coating of an exhaust pipe of an eighth embodiment of the second invention has a blind pore in which a part communicates with the outside of the exhaust pipe.

14 FIG. 10 is a sectional view schematically showing an example of a sectional surface of an exhaust pipe according to the eighth embodiment of the second invention. FIG.

The surface coating of the exhaust pipe 280 The eighth embodiment of the second invention has a blind pore 34 on, with a part in connection with the exterior of the exhaust pipe is.

Otherwise, their structure corresponds to the exhaust pipe 200 of the sixth embodiment of the second invention 11 ,

A blind pore is a pore having a part communicating with the exterior of the exhaust pipe, or in other words a recessed part exposed at the surface coating. Blind pores do not connect the exterior of the exhaust pipe to the surface of the substrate and do not extend to the surface of the substrate.

The exhaust pipe of the present embodiment can be manufactured in the exhaust pipe manufacturing method of the sixth embodiment of the second invention, however, to form the top layer, namely the surface coating, as the base composition for forming a surface coating, a base material composition is used to form a pore concentration section.

With the exhaust pipe of the present embodiment, the effects (9) to (11) of the exhaust pipe of the sixth embodiment of the second invention can be obtained.

Further embodiments

In the surface coating of the exhaust pipe of the present invention, there are no pores penetrating the surface coating, that is, connecting the outside of the exhaust pipe and the surface of the substrate.

If there are pores that penetrate the surface coating, the substrate surface is free of metal and moisture may enter this exposed surface so that the substrate surface may rust over the exposed surface. If there are no pores penetrating the surface coating, the substrate surface is not exposed, so that moisture does not penetrate and the metal substrate surface is prevented from rusting.

In order to avoid pores penetrating the surface coating, a method is preferably used wherein, in forming the surface coating, the base coat composition is applied to the surface of the substrate several times to form a surface coating. So that no pores are present, which penetrate the surface coating, the surface coating can also be made thick.

In the base material composition for a mixed layer which is the base material composition for forming a surface coating, the blending ratio of the non-crystalline inorganic material with respect to the total weight of the non-crystalline inorganic material powder and the crystalline inorganic material powder is preferably at least 50% by weight and preferably at most 99.5% by weight.

When the blending ratio of the non-crystalline inorganic material is less than 50% by weight, the amount of non-crystalline inorganic material contributing to the adhesion between the surface coating and the substrate does not suffice, so that the Surface coating of the manufactured exhaust pipe triggers. On the other hand, if the blending ratio of the non-crystalline inorganic material is more than 99.5% by weight, the amount of the crystalline inorganic material is small, so that the exhaust pipe heat dissipation performance may decrease. More preferably, the blending ratio of the non-crystalline inorganic material is at least 60% by weight, and more preferably at most 95% by weight.

In the base material composition for a mixed layer which is the base material composition for forming a surface coating, the blending ratio of the crystalline inorganic material with respect to the total weight of the non-crystalline inorganic material powder and the crystalline inorganic material powder is preferably at least 0 , 5 wt .-% and preferably at most 50 wt .-%.

When the blending ratio of the crystalline inorganic material is less than 0.5 wt%, the amount of crystalline inorganic material is too small, so that the heat dissipation performance of the exhaust pipe may decrease. In contrast, when the blending ratio of the crystalline inorganic material is more than 50% by weight, the amount of non-crystalline inorganic material contributing to the adhesion between the surface coating and the substrate is small, so that the surface coating of the manufactured exhaust pipe dissolves.

As the dispersing agent for mixing with the base material composition for forming a surface coating, there may be mentioned, for example, water, methanol, ethanol, acetone and other organic solvents. There are no particular limitations on the mixing ratio between the mixed powder and the dispersing agent, but it is preferable to use 50 to 150 parts by weight of the mixed powder per 100 parts by weight of the dispersant. In this way, a suitable viscosity for the application to the substrate of the exhaust pipe can be achieved.

As organic binders for blending with the base composition for forming a surface coating, there can be exemplified polyvinyl alcohol, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, etc. These may be used singly or in combination of two or more.

Both a dispersant and an organic binder can be used simultaneously.

In addition to a flat, semicircular or round shape, the outer profile may also have any other shape, such as elliptical or polygonal.

In the exhaust pipe of the present invention, the surface coating does not necessarily have to be formed on the entire outer peripheral surface of the substrate, but may be formed only on the part which makes the insulation the lowest current-carrying part (electrode).

A compelling condition for an exhaust pipe of the first invention is that it has a substrate of metal and a surface coating containing a non-crystalline inorganic material and formed on the surface of the substrate, wherein when five rectangle sections are determined by a section of the surface coating is cut in a vertical direction to the thickness direction of the exhaust pipe into five rectangular sections such that their thickness after cutting is 10 .mu.m, at least one rectangular section is a pore concentration section in which the Ratio in which there are pores in the rectangular section is larger than in the other rectangular sections.

A mandatory condition for an exhaust pipe of the second invention is that it comprises a metal substrate and a surface coating containing a non-crystalline inorganic material and formed on the surface of the substrate, the surface coating being a layer of non-crystalline inorganic material non-crystalline inorganic material containing a mixed layer containing a non-crystalline inorganic material and a crystalline inorganic material, the surface coating having independent pores, the independent pores not being the exterior of the exhaust pipe and the surface of the substrate interconnect, wherein the independent pores are localized in an interface portion between the layer of non-crystalline inorganic material and the mixed layer.

By subjecting these stringent conditions as needed to the various constructions of the first to eighth embodiments discussed in detail and other embodiments (such as the presence or absence of a crystalline inorganic material, pores formed by adding a pore-forming material, pores formed by roughening treatment, etc .), the desired effects can be achieved.

LIST OF REFERENCE NUMBERS

1, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 270, 280

exhaust pipe

10, 11, 12

substratum

20, 220

surface coating

20A, 20B, 20C, 20D, 20E

rectangular section

21, 21a, 21b, 221

Layer of non-crystalline inorganic material

22, 22a, 22b, 22c, 222a, 222b

mixed layer

23, 23a, 23b

Pore concentration section

31

non-crystalline inorganic material

32

crystalline inorganic material

33, 233

independent pore

34

Blindpore

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited non-patent literature

• Japanese Industrial Standard JIS R 3103-1: 2001 [0084]
• Japanese Industrial Standard JIS C 2131 [0270]
• Japanese Industrial Standard JIS C 2110-2 [0272]
• Japanese Industrial Standard JIS B 0601 (2001) [0322]
• JIS B 0601 (2001) [0324]
• JIS B 0601 (2001) [0334]
• Japanese Industrial Standard JIS B 0601 (2001) [0447]
• JIS B 0601 (2001) [0449]

Claims (16)

An exhaust pipe comprising a substrate of metal and a surface coating formed on the surface of the substrate containing a non-crystalline inorganic material, characterized in that pores are present in the surface coating, when five rectangular sections are determined by one at an electron microscope 500 times enlarged recording of a sectional area parallel to the thickness direction of the exhaust pipe, a portion of the surface coating is cut in vertical direction to the thickness direction of the exhaust pipe into five rectangular sections such that their thickness after cutting is 1/5 of the thickness of the surface coating, at least one rectangular section as pore concentration section is present in which of all the pores, which are present in the entire surface coating, surface area 30% or more of the pores, the rectangular section, which forms the pore concentration section, under de n five rectangle sections of the middle rectangle section or one or two rectangle sections adjoining the middle rectangle section are, and the pores present in the surface coating comprise independent pores and the independent pores do not surround the exterior of the exhaust pipe and connect the surface of the substrate. The exhaust pipe according to claim 1, wherein the pore ratio (B / A) of the pore concentration section, which is the ratio between the area occupied by the pores (B) and the area (A) of the rectangular section, is 0.02 or more. The exhaust pipe of claim 1 or 2, wherein the surface coating further comprises a crystalline inorganic material The exhaust pipe of claim 3, wherein the surface coating comprises a non-crystalline inorganic material layer containing a non-crystalline inorganic material and a mixed layer containing a non-crystalline inorganic material and a crystalline inorganic material, wherein the pore concentration portion is the interface between the non-crystalline inorganic material layer and the mixed layer The exhaust pipe according to claim 3 or 4, wherein the crystalline inorganic material contains at least one of manganese, iron, copper, cobalt, chromium and aluminum. The exhaust pipe according to any one of claims 1 to 5, wherein the number of pore concentration sections is one per area of the substrate, and the rectangular section constituting the pore concentration section is the middle rectangle section of the five rectangular sections. The exhaust pipe according to any one of claims 1 to 5, wherein the number of pore concentration portions per area of the substrate is two, and the rectangular portions constituting the pore concentration portions are two rectangular portions adjacent to the middle rectangle portion of the five rectangular portions. The exhaust pipe according to any one of claims 1 to 7, wherein the thickness of the surface coating is 25 to 1,000 μm. Exhaust pipe according to one of claims 1 to 8, wherein the thermal conductivity of the surface coating at room temperature 0.1 to 2 W / m · K. Exhaust pipe according to one of claims 1 to 9, wherein the volume resistivity of the exhaust pipe 10 ⁷ to 10 ¹⁴ Ωm. is. The exhaust pipe according to any one of claims 1 to 10, wherein the surface coating is formed by repeatedly applying the base composition for forming a surface coating. The exhaust pipe according to any one of claims 1 to 11, wherein the surface coating further comprises a blind pore having a part in communication with the outside of the exhaust pipe. Exhaust pipe comprising a metal and metal substrate a surface coating formed on the surface of the substrate and containing a non-crystalline inorganic material, characterized in that the surface coating comprises a layer of non-crystalline inorganic material containing a non-crystalline inorganic material and a mixed layer containing a non-crystalline inorganic material; crystalline inorganic material and a crystalline inorganic material, the surface coating having independent pores, the independent pores do not connect the outside of the exhaust pipe and the surface of the substrate and are localized in the interface portion between the layer of non-crystalline material and the mixed layer. The exhaust pipe of claim 13, wherein the surface coating further comprises a blind pore having a part in communication with the exterior of the exhaust pipe. A method of manufacturing an exhaust pipe, comprising the steps of: preparing a metal substrate, Preparing a base material composition for a surface coating, Applying the base material composition for forming the surface coating on the metal substrate and forming the surface coating by firing, characterized in that in the step of preparing the basecoat composition for forming the surface coating, a basecoat composition for a non-crystalline inorganic material layer containing a non-crystalline inorganic material, and / or a composite basecoat composition comprising a non-crystalline inorganic material and a crystalline inorganic material is prepared, and a pore-forming material is mixed with the base material composition for a layer of non-crystalline inorganic material or the base material composition for a mixed layer, and a base material composition for forming a pore concentration portion is prepared; in the step of forming the surface coating, the base composition is applied at least once to form a pore concentration portion, is fired to form pores in the surface coating, and the base composition for a layer of non-crystalline inorganic material or the base composition for a mixed layer is applied at least once. A method of manufacturing an exhaust pipe, comprising the steps of: preparing a metal substrate, Preparing a base material composition for a surface coating, applying the base composition several times to form the surface coating on the metal substrate and forming the surface coating by firing, and characterized in that: in the step of forming the surface coating, a step of forming a lower layer of the surface coating is carried out; wherein the application of the primer composition to form the surface coating and firing is performed at least once; the surface of the lower layer of the surface coating is roughened, and forming an upper layer of the surface coating by applying the base composition for forming the surface coating on the lower layer of the surface coating and firing, and simultaneously forming pores between the lower layer of the surface coating and the upper layer of the surface coating.

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