JP2002038921A - Filter material and exhaust gas removing device using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a filter material and exhaust gas removing device using it to heighten the capturing efficiency of particulates from the exhaust gas and enhance the durability. SOLUTION: The filter material 4 is embodied in a fiber laminate structure consisting of ceramics or heat-resistant metal, a honeycomb structure or foam structure, and a ceramic coating film (may include a surface unevenness 23a) 23 consisting of ceramics or heat-resistant metal is formed on the solid portion of the filter material 4, i.e., that surface portion of the base material 22 of filter which contacts with the fluid such as exhaust gas. The coating film 23 is made of ceramics produced through pyrolysis of CVD or organic silicon polymer, and a number of catalyst particles 35 are carried by the coating film 23.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filter material which can be used to manufacture a filter for collecting particulates in exhaust gas discharged from a diesel engine, and an exhaust gas removing apparatus using the same. .

[0002]

2. Description of the Related Art In a conventional exhaust gas removing apparatus for treating exhaust gas of an engine, a DPF using a filter made of a heat-resistant ceramic fiber such as silicon carbide is used.
An exhaust gas removing device called (diesel particulate filter) is known.

[0003] The ceramic fibers constituting this exhaust gas removing apparatus are formed to have a structure in which nonwoven fabrics having appropriate fiber diameters and different basis weights are laminated in order to increase the efficiency of collecting particulate matter contained in exhaust gas. ing.

[0004] The diesel particulate filter disclosed in Japanese Patent Application Laid-Open No. 8-243325 is a nonwoven fabric prepared by combining fibers having different fiber lengths to ensure usable strength. 30 to 10
It is composed of a nonwoven fabric in which long fibers having a length of 0 mm and short fibers having an average length of 10 to 30 mm are laminated at random.

[0005]

However, in a conventional exhaust gas removing apparatus using a filter made of ceramic fibers, the filter material has corrosion resistance to exhaust gas and the like, and the exhaust gas temperature is low. However, since high heat resistance is required, a high-quality fiber material such as silicon carbide is used, and there is a problem that the material cost is high and the manufacturing cost is high.

In this exhaust gas removing apparatus, it is possible to trap 80% or more of particulate matter contained in exhaust gas, but it traps suspended particulates, ie, SPM, containing unburned substances such as HC. In this case, since the surface of the ceramic fiber material has a smooth shape, there is a problem that particulate particulate matter passes between the fibers and is released into the outside air.

[0007] The present invention has been made to solve the above problems, and has the following objects.

First, a CVD or organosilicon polymer is applied to the surface of an inexpensive filter substrate constituting a filter material, and a heat treatment is performed to easily form a ceramic film on the surface. An object of the present invention is to provide a filter material having improved heat resistance and corrosion resistance by a coating made of a heat resistant metal.

[0009] Further, by providing these coatings with irregularities, when particulate matter in the exhaust gas comes into contact with the irregularities, it is easily trapped.
An object of the present invention is to provide a filter material in which the particulate matter is reliably collected by the uneven portions and the collection efficiency is improved.

[0010] The coating film and the concavo-convex portion as the coating layer of the filter base material function as a protective film against a corrosive component contained in the exhaust gas to improve the corrosion resistance and durability of the filter. Substrate is silica,
It is an object of the present invention to provide a filter material which can be manufactured from inexpensive low-quality materials such as alumina and carbon, and an exhaust gas removing device using the same.

[0011]

First, a filter material for achieving the above-mentioned object is constituted as follows.

1) A filter material according to the present invention is a filter having a fiber laminated structure, a honeycomb structure, or a foam structure made of ceramics or a heat-resistant metal. A film made of ceramics or a heat-resistant metal is formed on a surface portion in contact with the substrate.

2) In the above filter material, the coating is formed from ceramics generated by CVD or thermal decomposition of an organosilicon polymer.

3) Further, in the above-mentioned filter material, the uneven portion mainly contains amorphous silicon carbide or silicon nitride.

4) In the above filter material, the material constituting the filter, such as ceramic fibers, is selected from silicon carbide, silicon nitride, alumina, carbon, silica, and a composite material thereof.

5) In the above-mentioned filter material, the coating has an uneven portion on the surface.

6) Further, in the above-mentioned filter material, the uneven portion has a structure in which fine particles of ceramics or heat-resistant metal are included in a film made of the above-mentioned ceramics or heat-resistant metal.

Next, an exhaust gas removing apparatus using the above filter material is configured as follows.

7) In an exhaust gas removing apparatus using a filter having a fiber laminated structure, a honeycomb structure or a foam structure made of ceramics or a heat-resistant metal, a surface portion of a continuous portion of the filter which is in contact with a fluid such as exhaust gas. Is formed by forming a coating made of ceramics or a heat-resistant metal on the substrate.

In addition to this configuration, it is also effective to provide the coating with irregularities in order to further increase the collection efficiency.

8) In the exhaust gas removing apparatus using the above-described filter material, catalyst particles having a function of reducing the combustion temperature are carried on the surface of the coating.

The supported catalyst particles have a function of reducing the combustion temperature.

9) In the exhaust gas removing apparatus using the above-described filter material, the catalyst particles contain Pt and / or Pd.

According to the filter material having the above-described structure and the exhaust gas removing apparatus using the same, the CVD method is applied to the filter material having a fiber laminated structure, a honeycomb structure or a foam structure.
Or, by applying an organosilicon polymer and performing a heat treatment, a film is formed on the surface serving as a filter material,
An inexpensive and durable filter material can be obtained.

Further, by providing the unevenness on the surface of the coating film, when the suspended fine particles in the exhaust gas come into contact with the surface of the unevenness, it is easy to be trapped, so that the collection efficiency of the particulate matter is improved. Up.

Since this coating functions as a protective film against corrosive components contained in the exhaust gas, low-cost materials such as silica, alumina and carbon metal can be used as ceramics as a base material of the filter material. Material costs can be reduced as a whole.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, embodiments of a filter material of the present invention and an exhaust gas removing apparatus using the same will be described below.

FIG. 1 is a schematic explanatory view showing one embodiment of the exhaust gas removing apparatus, and FIG. 2 is an enlarged sectional view of the filter used in the exhaust gas removing apparatus shown in FIG. Also,
FIG. 3 is an enlarged explanatory view showing a region indicated by reference numeral B of the filter shown in FIG. 2, and FIGS. 4 to 6 show a region indicated by reference numeral C of the filter shown in FIG. FIG.

The embodiment of this filter material is such that the filter material 4 constituting the filters 8 and 9 for collecting the particulate matter contained in the exhaust gas discharged from the engine 1 has a laminated structure of a fiber material. And the filter material 4
Is a filter 8, used for collecting particulate matter contained in exhaust gas and purifying the exhaust gas,
9, and has a structure in which a surface of a filter substrate 22 is provided with a coating 23 and an uneven portion 23a.

The embodiment of the exhaust gas removing apparatus is an exhaust gas removing apparatus incorporating filters 8 and 9 each having a fibrous material in a laminated structure. In the present invention, although not shown, the filter may be formed in a honeycomb structure or a foam structure in addition to the filters 8 and 9 in which the filter material 4 made of a fiber material is formed in a fiber laminated structure. Since the functions are substantially the same as those of the filters 8 and 9 having the fiber laminated structure, the filter material 4 formed of the filter manufactured from the fiber material and the filters 8 and 9 having the fiber laminated structure are used here. The incorporated exhaust gas removing device will be described.

The filter material 4 according to the present invention is used to purify the exhaust gas discharged from the engine 1 on the surface of the base material constituting the filters 8 and 9 for collecting the particulate matter contained in the exhaust gas. The filter material 4 includes a coating 23 and irregularities 23a, and is formed of a material selected from silicon carbide, silicon nitride, alumina, carbon, silica, and a composite material thereof.

Further, the exhaust gas removing device 3 according to the present invention comprises:
Filters 8 and 9 manufactured using the filter material 4 are incorporated into the exhaust pipe 2 to collect particulate matter in exhaust gas and heat and incinerate it. The engine 1 is provided with an exhaust manifold 19 for discharging exhaust gas generated in the combustion chamber 18 of each cylinder.
A high-power generator 5 is provided in which a rotating shaft 26 is driven through a drive belt 17 hung on the power belt.

FIGS. 2 to 6 show filters 8 and 9 formed into a fiber laminated structure by the filter material 4. A coating 23 made of ceramics or heat-resistant metal is formed on a surface portion of the solid portion constituting the filter material 4, that is, the filter substrate 22, which is in contact with a fluid such as exhaust gas when the fluid passes through the fluid passage 24. That is, as shown in FIG. 4, the coating 23 is formed on the filter base material 22 constituting the fiber of the filter material 4.

Further, as shown in FIGS. 5 and 6,
An uneven portion 23a is formed on the surface of the film 23. Then, catalyst particles 35 of a combustion catalyst containing a catalyst such as Pt and Pd are carried on the surface of the uneven portion 23a, and a fluid passage 24 is formed between the laminated fibers. Is configured to pass through.

The coating 23 on the filter substrate 22 and the uneven portions 23a are formed of ceramics formed by CVD or thermal decomposition of an organosilicon polymer. Here, the filter material 4 includes silicon carbide, silicon nitride, alumina, carbon,
A ceramic fiber material selected from silica and a composite material thereof is used, and the filter material 4 is, for example, an integrated fiber material such as a ceramic fiber and / or a ceramic long fiber.

The filters 8, 9 are made of, for example, sheet-like or mat-like fibrous members made of a nonwoven fabric of the filter material 4, are folded in a fold shape, and are formed in a cylindrical shape as a whole. As shown by the arrow at 2, the exhaust gas is sent from the exhaust gas passage 27 on the outer peripheral side of the filters 8 and 9 to the exhaust gas passage 28 on the inner peripheral side.

Next, a description will be given of an exhaust gas removing apparatus incorporating a filter composed of the filter material 4 made of ceramic fibers.

This exhaust gas removing apparatus uses a filter in which the filters 8 and 9 are formed of a fiber laminated structure, a honeycomb structure or a foam structure made of ceramics or a heat-resistant metal. A coating 23 made of ceramics or heat-resistant metal and an uneven portion 23 a provided on the surface of the coating 23 are formed on a continuous portion, for example, a surface portion of the fiber filter base material 22 that comes into contact with a fluid such as exhaust gas. . Further, the uneven portion 23a
A countless number of combustion catalysts having a function of reducing the combustion temperature, that is, catalyst particles 35 are supported on the surface of the. The catalyst particles 35 contain Pt (platinum) and / or Pd (palladium).

As shown in FIG. 1, this exhaust gas removing apparatus is specifically incorporated in an exhaust pipe 2 for discharging exhaust gas from a combustion chamber 18 of the engine 1, and the exhaust gas passes through filters 8 and 9. As a result, the suspended particulates, ie, particulate matter (SPM), contained in the exhaust gas are collected, and the particulate matter collected by the filters 8, 9 is supplied to the wire mesh heater 20 to be heated and incinerated. Is to purify. The heat source that heats the wire mesh heater 20 is a part of the electric power generated by the high-power generator 5, and is configured to heat according to a command from the controller 10.

An exhaust pipe 2 through which exhaust gas discharged from an engine such as a diesel engine flows is provided with a separation chamber in the exhaust gas removing device 3, that is, an exhaust gas flow switching chamber 15. In the exhaust pipes 6, 7 of the branch passages extending from the switching chamber 15, casings 21, 21 for accommodating a pair of filters 8, 9 are arranged, and in the casing 21, for example, formed of the filter material 4. Filters 8 and 9 are fixed by support members and the like. The filters 8 and 9 collect particulate matter composed of carbon, smoke, SOx and the like contained in the exhaust gas.

In the embodiment shown in FIG. 1, a switching valve 14 is provided in the switching chamber 15, and the switching valve 14 is
By operating with 6, one of the exhaust pipes 6, 7 is closed and the other is opened.

The filters 8 and 9 are provided with an upstream wire mesh, that is, a wire mesh heater 20 and a downstream wire mesh 29 in order to prevent the fiber material from being scattered in close contact with their surfaces. The filters 8, 9 formed in the cylindrical body are sealed at the upstream end with the shield plate 30, and the downstream end is open at the outlet side exhaust gas passage 28 at the center at the shield plate 3.
1 sealed.

Therefore, the exhaust gas passing through the exhaust pipe 2 is
Exhaust gas passage 27 on the inlet side from exhaust pipes 6 and 7 in the branch passage
Then, the gas passes through the filters 8 and 9 from the inlet-side exhaust gas passage 27, is discharged to the outlet-side exhaust gas passage 28, and flows to and is discharged from the outlet-side branch passages to the exhaust pipes 6 and 7. Then, when passing through the filters 8 and 9, the particulate matter is collected.

The exhaust gas removing device includes a filter 8,
Pressure sensors 11 and 12 for detecting the pressure Px of the exhaust gas are provided on the exhaust pipes 6 and 7 upstream of the exhaust pipe 9, and the exhaust pipes 6 and 7 on the downstream side of the filters 8 and 9 are provided on the exhaust pipe 2. A pressure sensor 13 for detecting the pressure of the exhaust gas discharged from the exhaust gas removing device 3 is provided.

The pressure of the exhaust gas detected by these pressure sensors 11, 12, and 13 fluctuates depending on the engine rotation and the engine load, and the detected detection signal is input to the controller 10. This controller 10
In accordance with the engine rotation of the rotation sensor 32 and the load sensor 33 and the operating state of the load, for example, based on the detection values from the pressure sensors 11, 12, 13 upstream and downstream of the exhaust gas flow of the filters 8, 9, for example, the pressure difference , Pressure ratio, etc., and the state of accumulation of the particulate matter in the filters 8, 9 is detected from these values.

First, the particulate matter is collected by one of the filters 8 or 9. At that time, the pressure of the exhaust gas changes in accordance with the amount of collected or accumulated particulate matter in the filter 8 or 9. The pressure value on the upstream side of the filters 8 and 9 becomes gradually higher than the pressure value on the downstream side according to the accumulation amount of the particulate matter.

The controller 10 determines the ratio between the pressure value detected by the pressure sensors 11 and 12 on the upstream side of the filters 8 and 9 and the pressure value detected by the pressure sensor 13 on the downstream side of the filters 8 and 9 in advance. In a state where the particulate matter has reached a predetermined value or more, the particulate matter is sufficiently collected by the filter 8 or 9, and the actuator 16 is operated to switch the switching valve 14, thereby exhausting the flow of exhaust gas. The flow to the pipe 6 or 7 is controlled.

At the same time, since the filter 8 or 9 collects a predetermined amount or more of the particulate matter, the controller 10 supplies the power from the power source 34 such as a battery that stores the electric power from the generator 5 in accordance with a command from the controller 10. Then, control is performed to regenerate the filter 8 or 9 by energizing the wire mesh heater 20 through the electrode terminal and heating and burning the collected particulate matter.

Next, a method of manufacturing the filter material 4 according to the present invention will be described.

[Manufacturing Method 1] First, to manufacture the filter material 4, a filter substrate 2 made of silicon carbide was used.
Using a non-woven fabric of No. 2 and the non-woven fabric in a reaction vessel (not shown)
After heating to a predetermined temperature, a raw material gas to be the coating film 23 was introduced into the reaction vessel, and a CVD reaction was generated. The coating film 23 having the uneven portions 23a made of particles was generated.

Therefore, in order to manufacture the filters 8 and 9 using the filter material 4, the fibers of the filter material 4 are formed in a mat-like laminated structure, and the wire mesh 2 is formed on the upper and lower surfaces of the laminated filter material 4.
Filters 8 and 9 were manufactured by arranging 0 and 29, sandwiching the laminated structure between the wire meshes 20 and 29, and forming a bellows-like cylindrical body with folds as shown in FIG. Next, the wire mesh 20 was connected to the electrodes and arranged inside the casing 21 to constitute an exhaust gas removing device as shown in FIG.

An evaluation, ie, a test for collecting particulate matter contained in exhaust gas was performed by using the exhaust gas removing apparatus configured as described above, and the state of collection of particulate matter by the filters 8 and 9 was as follows. A high collection efficiency of about 95% was achieved.

When the particulate matter contained in the exhaust gas using a filter made of a conventional fiber filter material is collected, the collection state of the particulate matter is about 80%. 4 is uneven portion 23
It was found that when a was present, the collection efficiency of the particulate matter was improved. Further, in this exhaust gas removing device, it was found that SOx in the exhaust gas was also reduced as the particulate matter in the exhaust gas was collected.

Next, a nonwoven fabric is manufactured from alumina, carbon, silica and silicon nitride fibers instead of the silicon carbide forming the filter material 4, and the exhaust gas is removed using the filters 8 and 9 made of the nonwoven fabric. When the apparatus was formed and subjected to the same evaluation or test, the same collection efficiency of particulate matter could be achieved.

Further, as a filter substrate, a metal foam and a metal honeycomb having continuous air holes formed of a heat-resistant metal were used, placed in a reaction vessel (not shown) in the same manner as in the case of the ceramic fiber, and predetermined. After heating to a predetermined temperature, a raw material gas to be an uneven portion was introduced into the reaction vessel, and a CVD reaction was generated on the surface of the filter substrate.
Irregularities formed of countless particles of about several microns on the surface of the filter substrate.

In the same manner as described above, the state of collection of particulate matter in the exhaust gas was evaluated or tested. As a result, the state of collection of particulate matter was about 85%.

[Production Method 2] Another example of producing the filter material 4 was as follows.

In order to manufacture the filter material 4, a polycarbosilane solution, which is a kind of an organosilicon polymer, is applied to the nonwoven fabric substrate 22 using the nonwoven fabric of the filter substrate 22 formed of silicon carbide, and then thermally decomposed. By performing the baking treatment, it was possible to form the uneven portions 23a made of countless particles having a size of about several microns on the surface of the fiber filter base material 22.

Further, a nonwoven fabric may be produced from fibers of alumina, carbon, silica and silicon nitride in place of the silicon carbide forming the filter material 4 or a metal foam or metal having continuous air holes formed of a heat-resistant metal. When the same process was applied to the case of using honeycomb,
On the surface of the filter substrate 22, irregularities 23a composed of innumerable nodular particles of about several microns could be formed. As a result of the analysis, it was found that the uneven portion 23a was amorphous silicon carbide.

Therefore, an exhaust gas removing device was constructed using the filter material 4 produced by applying the organosilicon polymer to the filter substrate 22, and the state of trapping particulate matter in the exhaust gas was evaluated. The collection efficiency of the particulate matter in the gas was 85 to 93%. Further, when the exhaust gas was purified using the exhaust gas removing device of this embodiment, it was found that the amount of unburned substances in the exhaust gas contained in the exhaust gas was reduced.

[Production Method 3] Further, another example of producing a filter material was as follows.

As the filter material 4, a metal foam having a continuous vent made of a heat-resistant metal and a metal honeycomb are used as the filter base material 22, and about 1 μm of Fe—Cr—Al particles are fused on the surface of the filter base material 22. Then, the irregularities 23a were formed on the surface of the filter substrate 22.

Similarly, an exhaust gas removing apparatus was manufactured using this filter material 4, and the state of collection of the particulate matter in the exhaust gas was evaluated. The collection efficiency of the particulate matter in the exhaust gas was 85%. Was.

In addition, Pt and Pd, which are combustion catalysts, are innumerably supported on the surface of the uneven portion 23a of the filter base material 22 to produce the filter material 4. In the same manner as described above, the filter material 4 is used to remove the exhaust gas. The particulate matter in the exhaust gas was manufactured and the collection state of the particulate matter in the exhaust gas was evaluated. The collection efficiency of the particulate matter in the exhaust gas was 90%.

[Production Method 4] In another embodiment, a suspension prepared by dispersing alumina fine particles, silica fine particles, silicon nitride fine particles, and silicon carbide fine particles in a polycarbosilane solution, which is one kind of an organosilicon polymer, is used. A suspension is prepared, a nonwoven fabric, which is a ceramic fiber, is immersed in the suspension, and then dried and heat-treated to convert the polycarbosilane to silicon carbide and fix the fine particles on the fiber surface. Was provided.

A wire mesh for electric current was arranged on the upper and lower surfaces of each of the fiber non-woven fabrics produced by the treatment using this suspension, and after being overlapped, a filter element was formed in a bellows shape. An electrode was formed on this, and it was arranged in a container to obtain an exhaust gas removing device.

In this exhaust gas removing device, the collection efficiency of the conventional exhaust gas removing device was about 80%, whereas the trapping efficiency was 9%.
The collection efficiency was as high as about 8%. Also, it was found that SOx was also reduced with the improvement of the collection efficiency.

Then, a treatment similar to the treatment using the suspension was performed on the surface of a metal foam and a metal honeycomb having continuous ventilation holes, and an exhaust gas removing device was manufactured. The collection efficiency was shown.

In the treatment using this suspension, the same effect can be obtained by using ceramic particles such as silicon nitride, silicon carbide and zirconia as well as nickel-based heat-resistant metal particles in addition to the fine particles used above. Can be obtained.

[0070]

According to the filter material and the exhaust gas removing apparatus using the same according to the present invention, as described above, the surface of a filter having a fiber laminated structure, a honeycomb structure or a foam structure in contact with a fluid such as exhaust gas. Since a coating made of ceramics or heat-resistant metal is provided on the part, the surface of the filter base material can be covered with a coating layer, and this coating layer becomes a protective film against corrosion components contained in exhaust gas,
Since the corrosion resistance of the filter is improved and the durability of the filter is improved, the filter base material can be manufactured from inexpensive low-quality materials such as silica, alumina, and carbon, and the manufacturing cost can be reduced.

Further, when irregularities were formed on the surface of a filter substrate constituting a filter material such as fibers, honeycombs and foams made of ceramics and heat-resistant alloys, the particulate matter in the exhaust gas contacted the irregularities. At that time,
Since trapping is facilitated, the particulate matter is reliably collected at the uneven portion, and the collection efficiency can be increased.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing one embodiment of an exhaust gas removing device according to the present invention.

FIG. 2 is an enlarged cross-sectional view taken along the line AA of FIG. 1 showing a filter used in the exhaust gas removing device of FIG.

FIG. 3 is an enlarged explanatory view showing a region indicated by reference numeral B of the filter of FIG. 2;

FIG. 4 is a schematic enlarged cross-sectional view showing a film formed on a filter substrate in a region indicated by reference numeral C of the filter of FIG. 3;

FIG. 5 is an enlarged explanatory view showing a concave-convex portion formed on the surface of a film of a filter base material in a region indicated by reference numeral C of the filter of FIG. 3;

6 is a schematic enlarged cross-sectional view showing an uneven portion formed on the surface of a film of a filter base material in a region indicated by reference numeral C of the filter of FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine 2,6,7 Exhaust pipe 3 Exhaust gas removing device 4 Filter material 8,9 Filter 20 Wire mesh heater 22 Filter base material 23 Coating 23a Uneven part 24 Fluid passage 27,28 Exhaust gas passage 35 Catalyst particles

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F01N 3/02 321 F01N 3/02 321A 341 341J B01D 39/14 B01D 39/14 B 39/20 39/20 DA 53/94 F01N 3/24 E F01N 3/24 B01D 53/36 103C F-term (reference) 3G090 AA01 AA02 AA03 BA04 CB24 DA03 DA18 DA20 3G091 AA18 AB02 AB13 BA00 EA01 EA04 EA32 GA02 GA06 GB01X GB06W GBX GB07 4D019 AA01 BA02 BA05 BB02 BB03 BB07 BC07 BC12 CA01 CA02 CA03 4D048 AA14 AB01 AB03 BA30X BA31X BB02 BB08 BB09 BB12 BB15 BB20 CC38 CD05

Claims (9)

[Claims] 1. A filter constituted by a fiber laminated structure, a honeycomb structure or a foam structure made of ceramics or heat-resistant metal, wherein, of the solid portion constituting the filter, the surface portion in contact with a fluid such as exhaust gas has ceramics or heat-resistant. A filter material comprising a metal coating. 2. The filter material according to claim 1, wherein said coating is formed from ceramics formed by CVD or thermal decomposition of an organosilicon polymer. 3. The filter material according to claim 2, wherein the coating is mainly composed of amorphous silicon carbide or silicon nitride. 4. The filter material according to claim 1, wherein a material constituting the filter is a material selected from silicon carbide, silicon nitride, alumina, carbon, silica, and a composite material thereof. 5. The filter material according to claim 1, wherein the coating has an uneven portion formed on a surface thereof. 6. The filter material according to claim 5, wherein said uneven portion is formed by encapsulating ceramics or heat-resistant metal fine particles in a film made of said ceramics or heat-resistant metal. 7. An exhaust gas removing apparatus using a filter constituted by a fiber laminated structure, a honeycomb structure or a foam structure made of ceramics or a heat-resistant metal, wherein a surface portion of a continuous portion of the filter which is in contact with a fluid such as exhaust gas. An exhaust gas removing apparatus, wherein a coating made of ceramics or a heat-resistant metal is formed on the exhaust gas removing apparatus. 8. The exhaust gas removing apparatus according to claim 7, wherein catalyst particles having a function of reducing a combustion temperature are carried on the surface of the coating. 9. The exhaust gas removing device according to claim 8, wherein the catalyst particles contain Pt and / or Pd.