JPH075392B2 - Method for manufacturing ceramic / iron member joints - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a ceramic / iron member joined body that can be used in an exhaust system device of an internal combustion engine.

[Problems to be Solved by Prior Art and Invention]

In order to impart heat resistance, corrosion resistance and thermal shock resistance to those that are exposed to high temperature corrosive gas and are subjected to rapid thermal shock such as exhaust system members of internal combustion engine, a ceramic coating on the inner surface Is proposed.

The most serious problem with such a ceramic / iron member joined body is that it undergoes a rapid thermal shock due to high-temperature exhaust gas, and therefore the bonding interface between the ceramic and iron members is greatly affected by the difference in thermal expansion between the ceramic and iron members. Strain stress occurs and peeling occurs from the bonded surface of the ceramic.Since the thermal conductivity of the ceramic layer is much smaller than that of iron members, thermal shock causes an extremely large temperature gradient in the ceramic layer. Therefore, a large strain stress is generated in the ceramic layer and peeling occurs in the ceramic layer.

Generally, ceramic has a high compressive strength, but a low tensile strength and a very brittle property, and has a drawback that its resistance to thermal shock is very low.

Therefore, various proposals have been made to solve such problems.

For example, Japanese Patent Laid-Open No. 58-51214 discloses that a coating layer of an amorphous refractory made of a mixture of refractory raw material particles and a heat-resistant inorganic binder is formed on the inner surface of a metal device body in contact with high-heat exhaust gas. Disclosed is a characteristic exhaust gas system device for an internal combustion engine.

In addition to this, in JP-A-58-99180, a heat-resistant coating layer is formed by adhering a sludge made of a mixture of refractory raw material particles, an inorganic binder and a frit to the inner surface of a metal equipment body in contact with high-heat exhaust gas. To form a fire-resistant heat-insulating layer by adhering refractory heat-insulating material particles to the surface of the heat-resistant heat-insulating layer while the heat-resistant heat-insulating layer is in a wet state, and then solidifying the heat-resistant heat-insulating layer and then forming the heat-resistant heat-insulating layer. The surface of the heat-resistant coating layer is formed by adhering a slurry made of a mixture of refractory raw material particles, an inorganic binder and a frit to form a heat-resistant coating layer. Disclosed is a method of manufacturing an exhaust gas system device for an internal combustion engine, in which a fire-resistant heat-insulating layer of a material and a heat-resistant coating layer of the same material are sequentially repeated to form required layers.

However, even with these methods, the bonding strength between the ceramic layer and the metal is not always sufficient, and there is a risk of peeling at the bonding interface between the ceramic and the metal and peeling within the ceramic layer due to thermal shock, and long-term There is a problem with service life.

Recently, ceramic paints and coating agents using a metal alkoxide as a binder have been developed, but these are very expensive and it is difficult to make them thick enough to withstand long-term use.

Further, Japanese Patent Application Laid-Open No. 59-12116 discloses a composite ceramic material in which inorganic hollow particles are dispersed in a matrix made of ceramic. However, if the inorganic hollow particles are simply dispersed in the matrix, the heat insulating property is not improved. Even if it can be secured, it is not possible to obtain a coating that has good adhesion to the metal surface and is resistant to thermal shock. Moreover, since the inorganic hollow particles generally have low strength, they may be broken between the hollow particles to cause peeling or cracking.

By the way, recently, when a ceramic-iron member joined body is exposed to high temperature corrosive exhaust gas for a long time, the corrosive exhaust gas penetrates into the ceramic layer and reaches the interface with the iron member, where the surface of the iron member is exposed. It turns out that there is a problem of oxidizing. Oxidation of the surface of the iron member causes cracks in the oxide layer, which causes a problem of easy peeling due to mechanical shock or thermal shock. In addition, there is a problem that iron oxide diffuses to the surface of the coating, causing the coating to turn black and impairing its appearance.

Therefore, an object of the present invention is to have a sufficiently high bonding strength and good antioxidation property, and even if it is used under high temperature conditions for a long time, it does not discolor to black due to the diffusion of iron oxide in the coating, and the peeling It is an object of the present invention to provide a method for producing a ceramic / iron member joined body which does not have any problem.

[Means for Solving the Problems]

As a result of earnest research in view of the above object, the present inventors have found that, after forming a bonding layer in which an oxide film of an iron member and a silicate are reacted, a particulate metal oxide or an organic metal binder is solidified by oxidation. An iron diffusion prevention layer is formed, and if necessary, a heat insulation layer,
It was discovered that by forming a refractory layer and a protective layer, a ceramic-iron member joined body can be obtained that does not discolor even if it is exposed to high temperature corrosive exhaust gas for a long period of time and that there is no risk of peeling. The present invention was conceived.

That is, in the method for manufacturing a ceramic / iron member joined body of the present invention, (a) an oxidation treatment is applied to the surface of the iron member to form an oxide film, and (b) a silicate binder is applied onto the oxide film. After drying and forming a binding layer, (c) a particulate metal oxide or an organometallic binder is applied to the surface of the binding layer to form an iron oxide diffusion prevention layer, and (c) subsequently curing. After drying, firing is performed in an atmosphere having an oxygen partial pressure of 10 mmHg or less to complete the bonding of the bonding layer and the iron oxide diffusion preventing layer.

The present invention is described in detail below.

In the method for manufacturing a ceramic / iron member joined body of the present invention, the bonding layer and the iron oxide diffusion preventing layer are formed as indispensable constituent conditions, and if necessary, the heat insulating layer, the fireproof layer and the protective layer are formed. Each layer will be described in detail below.

(1) Bonding Layer In order to firmly bond the ceramic to the surface of the iron member, it is important to bond the surface of the iron member by a physical and chemical synergistic action. As a result of various studies, the present inventors have found that forming an oxide film on the surface of the iron member in advance is effective for adhesion.

By forming an oxide film on the surface of the iron member in advance, very small irregularities are generated on the surface of the iron member to improve the wettability of the silicate as a binder, and the oxide film reacts with the silicate by the final heat treatment. Therefore, a good bonding layer that is chemically and strongly bonded is formed.

The bonding layer is a dense layer for joining the iron oxide diffusion preventing layer and the iron member and for preventing permeation of corrosive gas from the outside. It is appropriate that the thickness of the bonding layer is 50 μm or less,
If it exceeds 50 μm, it may peel off from the bonding layer. The thickness is preferably 2 to 30 μm. Here, the thickness is an average value, and there is a fluctuation of about 20 to 30% as a whole.

In the enamel technology, ceramic is formed on the surface of an iron-made member that does not have an oxide film by forming a ceramic on the surface of the iron-made member and oxidizing and firing it. In the method for forming a bonding layer according to the invention, an oxide film is formed on the surface of an iron member so as to have a predetermined film thickness in advance, and after applying a silicate binder, the oxide film and the silicic acid are formed by firing in a neutral atmosphere. The salt reacts to form a stable tie layer. In the present invention, the effect of the present invention does not change even if some oxide film remains if the bonding layer is sufficiently formed.

In the bonding layer forming method of the present invention, the oxide film on the surface of the iron member can be formed, for example, by putting the iron member in a heating atmosphere. The heating atmosphere is preferably 500 ° C. or higher in steam.

The reaction between the oxide film and the silicate is the final heat treatment, that is, 0.5% under a heating condition of about 750 to 850 ° C in a neutral atmosphere.
It can be performed by holding for about 1.5 hours.
As the neutral atmosphere, an atmosphere having an oxygen partial pressure of 10 mmHg or less is preferable.

As the silicate, one kind or a mixture of two or more kinds such as sodium silicate, potassium silicate and lithium silicate is used and is used in a solution form. These silicates are lithium silicate,
The coefficient of thermal expansion gradually increases with potassium silicate and sodium silicate, and by appropriately selecting these, the coefficient of thermal expansion of the bonding layer can be matched with the coefficient of thermal expansion of the iron member.

(2) Iron oxide diffusion preventive layer (prevention of discoloration) Liquid phase diffusion of iron oxide occurs on the surface of the bonding layer or other coating layers such as the antioxidant layer due to long-term use, and iron oxide is deposited on the surface of the coating layer. There is a problem that aesthetics are lost. In order to prevent this, it has been found that it is effective to provide a layer of fine particle metal oxide or organic metal binder.

As the particulate metal oxide, alumina sol, silica sol, chromia sol, zirconia sol, titania sol, etc. which have a small tendency to vitrify by reacting with iron oxide, and the organic metal binder include aluminum, silicon, chromium, zirconium and titanium. Alkoxides and the like can be used. The coefficient of thermal expansion of an iron member such as cast iron is very large, and if a layer of a metal oxide or an organometallic binder is thickened, thermal stress due to a difference in thermal expansion occurs and there is a risk of peeling. Alternatively, the layer of organometallic binder should be as thin as possible. High-purity alumina, silica,
Since a dense layer of chromia, zirconia, etc. has a great effect of preventing the permeation of iron oxide, the thickness of the iron oxide diffusion preventing layer is preferably 10 μm or less, and most preferably 3 to 6 μm. When the thickness is more than 10 μm, peeling occurs in the iron oxide diffusion preventing layer.

(3) Heat insulating layer This layer is for imparting heat insulating property, and is composed of a heat insulating material composed mainly of inorganic hollow particles, and is made of a mixture of a heat insulating material, a silicate binder and a curing agent. It can be formed by coating on the iron oxide diffusion preventing layer, curing and drying, and then firing in a neutral atmosphere with an oxygen partial pressure of 10 mmHg or less.

As the heat insulating material, it is preferable to use inorganic hollow particles such as shirasu balloon, expanded silica, and ceramic balloon. The average particle size of the powder is generally in the range of 10 to 500 μm. If it is less than 10 μm, cracking and peeling due to shrinkage occur, and if it is more than 500 μm, it is difficult to form a smooth coating layer. The preferred particle size range is 40 to 200 μm.

The silicate binder can be selected from potassium silicate, sodium silicate, lithium silicate and the like described in the section of the binding layer. As the curing agent, calcined aluminum phosphate, calcium silicate or the like can be used.

According to the method of the present invention, the mixed substance of the heat insulating material, the silicate binder and the hardening agent is applied in the state of slurry on the iron oxide diffusion preventing layer. After application, cure at a temperature of 18 to 30 ° C for 8 to 24 hours. Then, after removing moisture sufficiently by drying,
Baking at 50 ° C for 0.5-1.5 hours. The firing is performed in a neutral atmosphere with an oxygen partial pressure of 10 mmHg or less as in the bonding layer.

In addition, as shown in FIG. 11, inorganic scale-like particles may be mixed in the heat insulating layer. As the inorganic scaly particles 1, naturally produced mica, artificially synthesized mica, film glass, or crushed inorganic hollow particles such as balloons are used. The shape of the inorganic scale-like particles 1 is such that the major axis and the minor axis are about 2 to 74 μm and the thickness is about 0.1 to 3 μm,
It is suitable that the ratio of thickness to major axis is 10 or more. More preferably, the major axis is 5 to 30 μm, the thickness is 0.5 to 2 μm,
The ratio of thickness to major axis is 15 or more. When the structure in which the inorganic scale-like particles 1 are mixed is used, the heat insulating layer also has sufficient strength and flexibility, and peeling and cracking do not easily occur even when subjected to high temperature thermal shock, and also has an antioxidant function. improves.

As for the thickness of the heat insulation layer, the thicker it is, the better from the aspect of heat insulation, but 20
If it exceeds 00 μm, it may be peeled off by high temperature thermal shock, and if it is less than 150 μm, the heat insulating effect cannot be obtained. It is preferably 300 to 800 μm.

(5) Refractory layer This layer is a layer formed for imparting fire resistance, and has a structure in which a refractory material mainly composed of inorganic particles is solidified.

For the refractory layer, apply a mixture of refractory material, silicate binder and curing agent to the dried surface of the iron oxide diffusion prevention layer or heat insulation layer, and after curing and drying, the oxygen partial pressure should be 10 mmHg or less. It can be formed by firing in a natural atmosphere.

As the refractory material, generally used materials such as chamotte, alumina, zircon, and zirconia may be used, but zirconia is particularly preferable because of its low thermal conductivity. The average particle size of the refractory powder is generally in the range of 10 to 500 μm. If it is less than 10 μm, agglomeration between particles is likely to occur, it is difficult to form a smooth coating layer, and it tends to shrink due to the influence of high heat. If it is larger than 500 μm, it is difficult to form a smooth film. A preferable average particle size is 20 to 200 μm.

The silicate binder and the curing agent may be the same as those used for the heat insulating layer.

The curing, drying and firing conditions for forming the refractory layer may be basically the same as the conditions for forming the heat insulating layer.

The thickness of this layer is better from the viewpoint of fire resistance, but 2000
If it exceeds 100 μm, it may peel off due to thermal shock at high temperature, and if it is less than 100 μm, a sufficient fire resistance effect cannot be obtained. It is preferably 200 to 800 μm.

(6) Protective layer This layer is a layer that forms a dense ceramic thin film on the surface of the iron oxide diffusion preventing layer, the heat insulating layer or the refractory layer to prevent intrusion of corrosive gas from the surface.

The protective layer has a constitution comprising an inorganic binder and / or an organometallic binder, and the inorganic binder and / or the organometallic binder is applied to the surface of the iron oxide diffusion preventing layer, the heat insulating layer or the fireproof layer after drying. After coating, it can be formed by baking in an atmosphere having an oxygen partial pressure of 10 mmHg or less.

Further, when the inorganic binder and / or the organometallic binder is stabilized only by being dried, the inorganic binder and / or the organometallic binder is formed on the surface of the iron oxide diffusion preventing layer, the heat insulating layer or the refractory layer after firing. The protective layer can be formed by applying a high quality binder and drying.

Suitable inorganic binders are solutions of alkali silicates such as sodium silicate, potassium silicate and lithium silicate, aluminum phosphate solutions, silica sols and the like.

Further, as the organometallic binder, a binder containing silicon alkoxide, zirconium alkoxide or the like as a main component is suitable.

With respect to this layer, it is difficult to match the coefficient of thermal expansion with the iron member in terms of material, and the layer thickness must be 15 μm or less. If the layer thickness exceeds 15 μm, the strain stress due to the difference in the coefficient of thermal expansion increases, which may cause peeling or cracking. It is preferably 3 to 10 μm.

The binding layer, the iron oxide diffusion preventing layer, the heat insulating layer, the refractory layer and the protective layer have been described above, but the combination of each layer is summarized as follows.

(A) Bonding layer + iron oxide diffusion preventing layer (b) Bonding layer + iron oxide diffusion preventing layer + protective layer (c) Bonding layer + iron oxide diffusion preventing layer + heat insulating layer (d) Bonding layer + iron oxide diffusion preventing layer + Heat insulating layer + Protective layer (e) Bonding layer + Iron oxide diffusion preventing layer + Fire resistant layer (f) Bonding layer + Iron oxide diffusion preventing layer + Fire resistant layer + Protective layer (g) Bonding layer + Iron oxide diffusion preventing layer + Thermal insulation Layer + Fireproof Layer (h) Bonding Layer + Iron Oxide Diffusion Prevention Layer + Heat Insulation Layer + Fireproof Layer + Protective Layer [Example] The present invention will be described in more detail by the following examples.

Example 1 An L-shaped tubular member 2 made of vermicular cast iron having a shape shown in FIG. 1 (long axis a: 200 mm, short axis b: 120 mm, inner diameter c: 40 mm, pipe thickness d:
The tubular member 2 was heated to 550 ° C. to form a 3 μm oxide film in order to form the bonding layer 3 on the inner surface and the outer surface of (3 mm).

This tubular member 2 was treated with a potassium silicate solution (SiO ₂ / K ₂ O molar ratio 3.
0, concentration 10% by weight), hold for 3 minutes and then pull up to remove excess sodium silicate, then raise from room temperature to 150 ° C over 25 minutes in a dryer and hold for 1 hour Then, it was cooled to room temperature to form a bonding layer 3.

Next, in order to form the iron oxide diffusion preventing layer 4 on the bonding layer 3 thus obtained, the tubular member 2 is dipped in silica sol of 20% SiO ₂ (Snowtex manufactured by Nissan Chemical Co., Ltd.). Then, it was held for 10 seconds and then pulled up to remove excess silica sol, and then cured for 1 hour at room temperature.

Next, the tubular member 2 was heated from room temperature to 300 ° C. at a temperature rising rate of 1 ° C./minute in a dryer, held for 1 hour, and then cooled to room temperature to dehydrate excess water.

Next, this tubular member 2 was heated in an N ₂ atmosphere (oxygen partial pressure 5 mmHg) to 800 ° C. at a heating rate of 200 ° C./hour, held for 1 hour, and then cooled to room temperature in the furnace, and the bonding layer 3 and The iron oxide diffusion preventing layer 4 was fired and solidified.

FIG. 2 schematically shows a cross section of one side of the coating layer formed of the bonding layer 3 having a thickness of about 10 μm and the iron oxide diffusion preventing layer 4 having a thickness of 3 μm.

Comparative Example 1 FIG. 3 is a cross-sectional view schematically showing the coating layer of the bonding layer formed on the inner and outer surfaces of the iron tubular member 2.

Bonding layer 3 was formed in the same manner as in Example 1. The thickness of this tie layer was about 10 μm.

The following evaluation tests were carried out in order to confirm the characteristics of the coating layers of Example 1 and Comparative Example 1 above.

1) Oxidation increase test The above-mentioned tubular member 2 was attached to an inner surface heating evaluation device that burns propane gas to generate a high temperature gas, and a test was conducted under the following conditions.

Gas temperature 980 ℃ Primary air flow rate 50Nm ³ / hour Propane gas flow rate 2Nm ³ / hour Secondary air flow rate 36Nm ³ / hour Oxygen concentration 11% Oxidation increase is shown in Table 1. Table 1 also shows the oxidation gain without the ceramic coating.

The inner surface temperature of the tubular member was 585 ° C in Example 1 and Comparative Example 1, and 580 ° C without coating.

2) Durability test The tubular member 2 of Example 1 was repeatedly subjected to 100 cycles of heating / cooling test with a heating evaluation device.

The conditions of the heating / cooling cycle were as follows.

Gas temperature 1050 ℃ Primary air flow rate 300Nm ³ / hour Propane gas flow rate 12Nm ³ / hour Secondary air flow rate 200Nm ³ / hour Oxygen concentration 15% Tubular member surface temperature 780 ℃ (with coating) Temperature rising rate 1000 ℃ / min Hold time 30 minutes Cooling in air 30 minutes As a result of the above test, no cracks or peeling were observed in the coating layer of the present invention, and it was confirmed that the durability was sufficiently satisfactory.

Although the coating layer is formed on the inner surface and the outer surface of the tubular member in the above-described embodiment, it is of course possible to form the coating layer only on the inner surface.

3) Discoloration test The tubular member 2 was attached to an internal heating evaluation test device, and a discoloration test of the coating layer on the inner and outer surfaces of the tubular member was performed by the continuous heating method under the following conditions.

The tubular member surface temperature 750 ° C. 1 primary air quantity 30 Nm ³ / time propane gas flow rate 1.2 Nm ³ / time oxygen concentration of 5 percent retention time of 30 hours results in the tests are shown in Table 2.

As is clear from Table 2, in the tubular member of Comparative Example 1 in which the iron oxide diffusion preventing layer is not applied, it is recognized that the diffusion of iron oxide into the coating layer is progressing. On the other hand, the tubular member of Example 1 provided with the iron oxide diffusion preventing layer exhibited good durability.

Example 2 FIG. 4 shows a bonding layer 3 formed on the inner surface of an iron tubular member 2.
FIG. 3 is a diagram schematically showing a coating layer composed of an iron oxide diffusion preventing layer 4 made of silica sol and a protective layer 5.

After forming the bonding layer 3 and the iron oxide diffusion preventing layer 4 by the same method as in Example 1, alumina sol (concentration: 10% by weight) is applied to the surface of the iron oxide diffusion preventing layer 4, and the temperature rising rate is 10%. ℃ /
The temperature was raised to 110 ° C. in minutes, a heat treatment was performed for 1 hour, and then the temperature was cooled to room temperature to form a protective layer 5 having a thickness of 8 μm.

Example 3 FIG. 5 shows the bonding layer 3 formed on the inner surface of the iron tubular member 2.
FIG. 3 is a cross-sectional view schematically showing a coating layer including an iron oxide diffusion preventing layer 4 and a heat insulating layer 6.

After forming the bonding layer 3 and the iron oxide diffusion preventing layer 4 in the same manner as in Example 1, the heat insulating material powder (having a specific gravity of 0.2, a particle size of 44
˜150 μm shirasu balloon), sodium silicate (silicate binder), and calcined aluminum phosphate (curing agent) were mixed in the following proportions to prepare a mixed slurry.

Sodium silicate (SiO ₂ / Na ₂ O molar ratio 3.0, concentration 30% by weight)
100 parts by weight Shirasu balloon (<74 μm) 30 parts by weight Calcined aluminum phosphate (<74 μm) 10 parts by weight The above-mentioned mixed slurry is applied to the surface of the iron oxide diffusion preventing layer 4 formed on the inner surface of the iron tubular member 2 and then applied for 2 hours. The heat curing operation was repeated to form the heat insulating layer 6.

In this state, curing was carried out at room temperature for 15 hours to carry out a curing reaction between sodium silicate in the heat insulation and calcined aluminum phosphate.

Next, this iron tubular member 2 was put in a drier, heated from room temperature to 300 ° C. at a temperature rising rate of 1 ° C./minute, and held for 1 hour,
The excess water was dehydrated by cooling to room temperature.

Next, the iron tubular member 2 was placed in an N ₂ atmosphere (oxygen partial pressure 5 mmH
In (g), the temperature was raised to 800 ° C. at a temperature rising rate of 200 ° C./hour and held for 1 hour, then cooled to room temperature, and the heat insulating layer 6 having a thickness of 1500 μm was solidified.

Example 4 FIG. 6 schematically shows a coating layer composed of a bonding layer 3 formed on the inner surface of an iron tubular member 2, an iron oxide diffusion preventing layer 4, a heat insulating layer 6, and a protective layer 5. FIG.

The bonding layer 3, the iron oxide diffusion preventing layer 4, and the heat insulating layer 6 are formed by the same method as in Example 3, and after firing, an aluminum phosphate solution (concentration 40% by weight) is applied to the surface of the heat insulating layer 6. Then
The temperature was raised to 110 ° C. at a temperature rising rate of 10 ° C./minute, heat treatment was performed for 1 hour, and then cooled to room temperature to form a protective layer 5 having a thickness of 8 μm.

Example 5 FIG. 7 shows a bonding layer 3 formed on the inner surface of an iron tubular member 2.
FIG. 3 is a cross-sectional view schematically showing a coating layer including an iron oxide diffusion preventing layer 4, a heat insulating layer 6, and a fireproof layer 7.

After forming the bonding layer 3, the iron oxide diffusion preventing layer 4, and the heat insulating layer 6 by the same method as in Example 3, the refractory powder (particle size 44 to 15
0 μm of stabilized zirconia), sodium silicate (silicate binder), and calcined aluminum phosphate (curing agent) were mixed in the following proportions to apply a mixed slurry.

Sodium silicate (SiO ₂ / Na ₂ O molar ratio 3.0, concentration 30% by weight)
100 parts by weight Stabilized zirconia (<74 μm) 120 parts by weight Calcined aluminum phosphate (<74 μm) 10 parts by weight Operation of applying the above mixed slurry to the surface of the heat insulating layer 6 formed on the inner surface of the iron tubular member 2 and curing for 2 hours Was repeated to form the refractory layer 7.

In this state, curing was carried out at room temperature for 15 hours to carry out a curing reaction between sodium silicate in the refractory layer and calcined aluminum phosphate.

Next, this iron tubular member 2 was placed in a drier and heated from room temperature to 300 ° C. at a temperature rising rate of 1 ° C./minute, held for 1 hour, and then cooled to room temperature to dehydrate excess water.

Next, the iron tubular member 2 was placed in an N ₂ atmosphere (oxygen partial pressure 5 mmH
In g), raise the temperature to 800 ° C at a heating rate of 200 ° C / hour, and
After holding for a period of time, it was cooled to room temperature, and the fireproof layer 7 having a thickness of 1000 μm, the heat insulating layer 6, and the iron oxide diffusion preventing layer 4 were solidified.

Example 6 FIG. 8 shows a bonding layer 3 formed on the inner surface of an iron tubular member 2.
An iron oxide diffusion preventing layer 4, a heat insulating layer 6, a refractory layer 7,
FIG. 3 is a cross-sectional view schematically showing a coating layer including a protective layer 5.

The bonding layer 3, the iron oxide diffusion preventing layer 4, the heat insulating layer 6, and the refractory layer 7 were formed in the same manner as in Example 5 and baked, and then an aluminum phosphate solution (concentration 40% by weight) was applied to the above refractory. Apply to the surface of layer 7 and raise the temperature to 110 ° C at a heating rate of 10 ° C / min.
After heat treatment for holding time, cool down to room temperature, thickness 8μ
m protective layer 5 was formed.

Example 7 FIG. 9 shows a bonding layer 3 formed on the inner surface of an iron tubular member 2.
FIG. 3 is a cross-sectional view schematically showing a coating layer composed of an iron oxide diffusion prevention layer 4 and a refractory layer 7.

After forming the bonding layer 3 and the iron oxide diffusion preventing layer 4 by the same method as in Example 1 and baking, a refractory powder (alumina having a particle size of 44 to 150 μm), sodium silicate (silicate binder), and Then, a mixed slurry containing fired aluminum phosphate (curing agent) in the following proportions was applied.

Sodium silicate (SiO ₂ / Na ₂ O molar ratio 3.0, concentration 30% by weight)
100 parts by weight Alumina (<74 μm) 85 parts by weight Calcined aluminum phosphate (<74 μm) 10 parts by weight The above-mentioned mixed slurry is applied to the surface of the iron oxide diffusion preventing layer 4 formed on the inner surface of the iron tubular member 2 and cured for 2 hours. The operation was repeated to form the refractory layer 7.

In this state, curing was carried out at room temperature for 15 hours to carry out a curing reaction between sodium silicate in the refractory layer and calcined aluminum phosphate.

Next, this iron tubular member 2 was put in a drier, heated from room temperature to 300 ° C. at a temperature rising rate of 1 ° C./minute, and held for 1 hour,
The excess water was dehydrated by cooling to room temperature.

Next, the iron tubular member 2 was placed in an N ₂ atmosphere (oxygen partial pressure 5 mmH
In g), raise the temperature to 800 ° C at a heating rate of 200 ° C / hour, and
After holding for a period of time, it was cooled to room temperature, and the refractory layer 7 having a thickness of 1000 μm was solidified.

Example 8 FIG. 10 shows a bonding layer 3 formed on the inner surface of an iron tubular member 2.
FIG. 3 is a view schematically showing a coating layer formed by an iron oxide diffusion preventing layer 4, a fire resistant layer 7, and a protective layer 5.

After forming the bonding layer 3, the iron oxide diffusion preventing layer 4, and the refractory layer 7 by the same method as in Example 7, the alumina sol (concentration 10
Wt%) is applied to the surface of the refractory layer 5 and the heating rate is 10 ° C.
The temperature was raised to 110 ° C./min, the heat treatment was performed for 1 hour, and the temperature was cooled to room temperature to form a surface layer 5 having a thickness of 8 μm.

Example 9 FIG. 11 shows a bonding layer 3 formed on the inner surface of an iron tubular member 2.
FIG. 3 is a cross-sectional view schematically showing a coating layer including an iron oxide diffusion preventing layer 4 and a heat insulating layer 6.

The bonding layer 3 and the iron oxide diffusion preventing layer 4 were formed by the same method as in Example 1. Next, this iron tubular member 2 was heated from room temperature to 300 at a temperature rising rate of 1 ° C./min in a dryer and held for 1 hour, after which excess water was dehydrated.

Next, a ceramic balloon with a bulk specific gravity of 0.47 and a particle size of 44 to 150 μm (insulator powder), crushed silica balloon particles (inorganic scaly particles), and sodium silicate (silicate binder)
And calcined aluminum phosphate (curing agent) were mixed in the following proportions to prepare a mixed slurry.

Sodium silicate (SiO ₂ / Na ₂ O molar ratio 3.0, concentration 30% by weight)
100 parts by weight Ceramic balloon (<100 μm) 20 parts by weight Silica balloon crushed particles (<74 μm) 25 parts by weight Calcined aluminum phosphate (<74 μm) 10 parts by weight Iron oxide diffusion preventive layer 4 formed on the inner surface of the iron tubular member 2 The heat-insulating layer 6 was formed by repeating the operation of applying the above-mentioned mixed slurry on the surface and curing for 2 hours.

In this state, curing was carried out at room temperature for 15 hours to carry out a curing reaction between sodium silicate in the heat insulating layer and calcined aluminum phosphate.

Next, this iron tubular member 2 was put in a dryer to dehydrate excess water.

The mixture was heated from room temperature to 300 ° C. at a temperature rising rate of 1 ° C./minute, held for 1 hour, and then cooled to room temperature.

Next, the iron tubular member 2 was placed in an N ₂ atmosphere (oxygen partial pressure 5 mmH
In (g), the temperature was raised to 800 ° C. at a temperature rising rate of 200 ° C./hour and held for 1 hour, then cooled to room temperature, and the heat insulating layer 6 having a thickness of 1500 μm was solidified.

The constitution and thickness of each coating layer in Examples 2 to 9 are as shown in Table 3 below.

The following heating test was performed in order to evaluate the characteristics of the coating layers obtained in Examples 2 to 9 above.

1) Test conditions Each tubular member was attached to a heating evaluation device that burns propane gas to generate a high temperature gas, and an inner surface heating test was performed under the conditions shown in Table 4.

2) Anticorrosion test (oxidation weight increase test) Under the conditions shown in Table 4, the thickness of the oxide layer on the adhesion surface by the combustion gas after each test time was measured by a scanning electron microscope (SEM).

The results are shown in Table 5 together with Comparative Example 2 having no coating layer.

The antioxidant effect of each example is about 3 to 6 times that of the case without coating. From this, it can be seen that the increased amount of oxidation is significantly reduced by the heat insulating effect of the coating layer.

3) Adiabatic test The surface temperature of the iron tubular member was measured under the conditions shown in Table 4 to examine the adiabatic property. The results are shown in Table 6 together with Comparative Example 2 having no coating layer.

4) Durability test As a result of 100 cycles of repeated heating / cooling test of heating and holding for 30 minutes under the conditions shown in Table 4 and then cooling to room temperature, no cracks or peeling were observed in the coating layer and the durability was sufficiently satisfactory. It was confirmed to do.

The function and effect of each layer in the above embodiment will be described.

A bonding layer 3 having a thickness of about 30 μm is formed on the inner surface of the iron tubular member 2. The bonding layer 3 is a dense glass and adheres well to the casting, contributing to the bonding between the iron oxide diffusion preventing layer 4 and the casting.

The thickness of the iron oxide diffusion preventing layer 4 formed on the surface of the bonding layer 3 was about 3 μm.

The heat insulating layer 6 had a thickness of 1500 μm. In the heat insulating layer of Example 9, since the hollow ceramic particles were formed by using a mixture of the inorganic scaly particles, the binder and the curing agent as a matrix, the heat insulating layer was firmly bonded to the iron oxide diffusion preventing layer 4 and rapidly. With sufficient flexibility against thermal shock,
It also has excellent heat insulation.

The refractory layer 7 is a refractory material that sufficiently withstands exhaust gas at high temperatures exceeding 1100 ° C., and is also a layer that is firmly bonded to the heat insulating layer 6.

The protective layer 5 had a thickness of 8 μm. Since the protective layer 5 is a dense and thin layer filling the open pores of the heat insulating layer 6 or the refractory layer 7, it has an extremely excellent effect of preventing invasion of harmful gas into the iron oxide diffusion preventing layer 4. .

Although this embodiment describes the manifold, it can be similarly applied to a port liner, a front tube, a turbocharger and the like.

〔The invention's effect〕

As described above in detail, the ceramic / iron member joined body of the present invention has a bonding layer having an action of strengthening the bonding between the iron member and the ceramic layer, and also has a fine particle metal oxide or an organic metal binder. Basically, it has an iron oxide diffusion preventing layer consisting of, and if necessary, a heat insulating layer consisting of inorganic hollow particles, a refractory layer and a protective layer are appropriately combined, so that the ceramic layer can be heated even under high temperature heating conditions. It does not turn black, there is no risk of peeling or cracking, and the corrosion resistance is extremely good. Therefore, when the ceramic / iron member joined body of the present invention is used in, for example, an exhaust system device of an internal combustion engine, it can sufficiently withstand rapid repeated thermal shock due to high temperature exhaust gas exceeding 800 ° C. It has excellent corrosion resistance and fire resistance without impairing the heat resistance, and exerts a remarkable effect in extending the service life of the member.

The ceramic / iron member joined body of the present invention having such effects is particularly suitable for use in an engine exhaust gas manifold, an exhaust pipe, and the like, and also in a port liner, a turbocharger, and the like.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of an iron member to which the present invention can be applied, and FIG. 2 is a sectional view schematically showing a ceramic / iron member joined body according to Embodiment 1 of the present invention. FIG. 4 is a sectional view schematically showing a ceramic / iron member joined body according to Comparative Example 1, and FIGS. 4 to 11 are sectional views schematically showing the ceramic / iron member joined body according to each embodiment of the present invention. Is. 1: Inorganic scale-like particles 2: Iron tubular member 3: Bonding layer 4: Iron oxide diffusion prevention layer 5: Protective layer 6: Thermal insulation layer 7: Refractory layer 8: Hollow spherical particles 9: Refractory particles

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masatoshi Nakamizo, 35 Nagahama-cho, Kanda-cho, Kyoto-gun, Fukuoka Prefecture Kyushu Factory, Hitachi Metals, Ltd. (72) Kensuke Kido 1-1, Higashihama-cho, Hachimansai-ku, Kitakyushu, Fukuoka No. 1 within Kurosaki Ceramics Co., Ltd. (72) Inventor Katsumi Morikawa 1-1, Higashihama-cho, Hachimansai-ku, Kitakyushu, Fukuoka Prefecture Within Kurosaki Ceramics Co., Ltd. (56) Reference JP-A-61-70119 (JP, A) JP-A-62 -107080 (JP, A) JP-A-62-107083 (JP, A) JP-A-62-107085 (JP, A) JP-A-62-107086 (JP, A) JP-A-1-145383 (JP, A) ) JP-A-2-258983 (JP, A)

Claims (8)

[Claims] 1. A method for producing a ceramic / iron member joined body, comprising: (a) oxidizing a surface of an iron member to form an oxide film, and (b) forming a silicate binder on the oxide film. After coating and drying to form a binding layer, (c) a particulate metal oxide or an organometallic binder is applied to the surface of the binding layer to form an iron oxide diffusion preventing layer, and (c) subsequently. A method for manufacturing a ceramic / iron member joined body, which comprises curing and drying, and then firing in an atmosphere having an oxygen partial pressure of 10 mmHg or less to complete the joining of the bonding layer and the iron oxide diffusion preventing layer. 2. The method for producing a ceramic / iron member joined body according to claim 1, wherein (a) the iron oxide diffusion preventing layer is dried and then the surface thereof has an inorganic binder and / or an organometallic binder. Is applied to form a protective layer, and (b) firing is then performed in an atmosphere having an oxygen partial pressure of 10 mmHg or less, which is a method for producing a ceramic / iron member joined body. 3. The method for manufacturing a ceramic / iron member joined body according to claim 1, wherein (a) after drying the iron oxide diffusion preventing layer, a heat insulating material mainly composed of inorganic hollow particles and a silicate binder. A mixture of a curing agent and a hardener is applied to the surface of the iron oxide diffusion prevention layer to form a heat insulating layer. (B) After curing and drying, baking is performed in an atmosphere with an oxygen partial pressure of 10 mmHg or less. A method for producing a characteristic ceramic / iron member joined body. 4. The method for manufacturing a ceramic / iron member joined body according to claim 3, wherein (a) after drying the heat insulating layer, an inorganic binder and / or an organometallic binder is applied to the surface thereof. A protective layer is formed by (b) and then firing is performed in an atmosphere with an oxygen partial pressure of 10 mmHg or less, which is a method for producing a ceramic / iron member joined body. 5. The method for manufacturing a ceramic / iron member joined body according to claim 3, wherein (a) after drying the heat insulating layer, a mixture of a refractory material, a silicate binder and a hardening agent is added to the heat insulating layer. A method for manufacturing a ceramic / iron member joined body, which comprises applying a fire-resistant layer to the surface of (1), followed by curing and drying, and then firing in an atmosphere with an oxygen partial pressure of 10 mmHg or less. 6. The method for manufacturing a ceramic / iron member joined body according to claim 5, wherein (a) after drying the refractory layer, an inorganic binder and / or an organometallic binder is applied to the surface thereof. A protective layer is formed by (b) and then firing is performed in an atmosphere with an oxygen partial pressure of 10 mmHg or less, which is a method for producing a ceramic / iron member joined body. 7. The method for manufacturing a ceramic / iron member joined body according to claim 1, wherein (a) after drying the iron oxide diffusion preventing layer, a mixture of a refractory material, a silicate binder and a curing agent is added. A ceramic / iron member characterized by being applied on the surface of the iron oxide diffusion preventing layer to form a refractory layer, and (b) subsequently being cured and dried, and then fired in an atmosphere with an oxygen partial pressure of 10 mmHg or less. Manufacturing method of bonded body. 8. The method for manufacturing a ceramic / iron member joined body according to claim 7, wherein (a) after drying the refractory layer, an inorganic binder and / or an organometallic binder is applied to the surface thereof. A protective layer is formed by (b) and then firing is performed in an atmosphere with an oxygen partial pressure of 10 mmHg or less, which is a method for producing a ceramic / iron member joined body.