JPS63129114A - Exhaust system apparatus and manufacture thereof - Google Patents

Abstract

PURPOSE:To make improvements in heat resistance, impact resistance, vibro- proof or the like, by installing a fireproof insulating layer which makes porous grains, made up of granulating a ceramic fiber ad whiskers, stick fast to an inner surface of an exhaust system apparatus where high temperature exhaust gas passes through. CONSTITUTION:In an exhaust system apparatus, for example, an exhaust manifold of an internal combustion engine, a fireproof insulating layer, making porous grains made up of granulating a ceramic fiber and/or whiskers, stick fast to the inner surface is formed. With this formation, heat resistance, impact resistance, vibro-proof, etc., are improved, whereby an increase of service life longevity in the exhaust system apparatus is promoted. At the time of manufacturing the exhaust system apparatus like this, first an inorganic binder solution is uniformly applied to an inner surface of the exhaust system apparatus and then an admixture of the porous grains made up of granulating the ceramic finer and/or whiskers and a little binding assistant consisting of refractory grains at need stuck on top of that. After doing like this, a process of curing, drying and solidification is carried out as much as at least one time and thus fireproof insulating layer is formed up.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to exhaust system equipment suitable for use as internal combustion engine parts for automobiles and a method for manufacturing the same.

Conventional technology Exhaust system equipment for internal combustion engines, especially manifolds, have their inner surfaces in contact with high-temperature, high-pressure combustion gas, so they are strongly affected by this.
It has the drawback that it cannot be used for a long period of time, and also has the drawbacks of large heat dissipation and poor insulation properties.

JP-A No. 58-51214 discloses exhaust system equipment for internal combustion engines, such as an exhaust manifold, whose inner surface is coated with a fire-resistant and heat-insulating coating. This exhaust system equipment for an internal combustion engine has a coating layer of an amorphous refractory made of a mixture of refractory raw material particles and an inorganic binder formed on the inner surface of a metal awning body that is in contact with high-temperature exhaust gas.

Furthermore, Japanese Patent Application Laid-Open No. 58-99180 discloses a method of applying a fire-resistant and heat-insulating coating to the inner surface of exhaust gas system equipment for an internal combustion engine, such as an exhaust manifold.

In this method, a heat-resistant coating layer is formed by depositing a slurry made of a mixture of refractory raw material particles, an inorganic binder, and a frit on the inner surface of a metal device body that is in contact with high-temperature exhaust gas, and then the heat-resistant coating layer is While the layer is in a wet state, refractory insulation material particles are attached to the surface thereof to form a refractory insulation layer, and then the heat resistant coating layer is solidified, and refractory raw material particles and inorganic materials are applied to the surface of the refractory insulation layer. A heat-resistant coating layer is formed by avoiding adhesion of a slurry made of a mixture of a binder and a frit, and if necessary, a fire-resistant heat-insulating layer made of the same material as the fire-resistant heat-insulating layer and Heat-resistant coating layers made of the same material as the heat-resistant coating layer are sequentially repeated to form required layers. By this method, a coating layer is formed in which the three layers of the heat-resistant coating layer, the fire-resistant heat insulating layer, and the heat-resistant coating layer are integrated and laminated.

Problems to be Solved by the Invention This manifold is coated on the inner surface with an amorphous refractory made of a mixture of refractory raw material particles and a heat-resistant inorganic binder, so if the coating layer contains a relatively large amount of water, Unavoidably, not only cracks occur during drying, but also shrinkage during heat treatment is large and peeling and breakage tend to occur.

Also, when rapidly heated by high-temperature exhaust gas, the heat v
There is a high risk of cracking or peeling occurring due to E-blow. Furthermore, it is extremely difficult to apply a slurry-like coating material, which is a monolithic refractory, to the inner surface of a manifold, which has low hygroscopicity, with a uniform thickness.

In addition, the inner surface of the manifold has a coating layer of refractory material, so it has good heat resistance, but the insulation is insufficient, and the temperature is transmitted to the outer surface of the manifold, resulting in high temperatures, which may shorten the life of the manifold. This is not a desirable structure.

Means for Solving the Problems In view of these shortcomings, the inventors of the present invention have conducted various studies, and as a result, they have created a fireproof insulation layer that does not crack or peel by forming a fireproof heat insulating layer on the inner surface of the exhaust system equipment and performing heat treatment. They discovered that it is possible to form a heat insulating coating, leading to the completion of the present invention.

The exhaust system equipment of the present invention is characterized by having a fireproof heat insulating layer in which porous particles made of granulated ceramic fibers and/or whiskers are fixed to the inner surface of the exhaust system equipment through which high-temperature exhaust gas passes. be.

Further, the method for manufacturing exhaust system equipment of the present invention includes: (1) uniformly applying an inorganic binder solution to the inner surface of the exhaust system equipment, and (2) immediately granulating ceramic fibers and/or whiskers on the layer of the inorganic binder solution. A refractory heat insulating layer is created by adhering a mixture of porous particles and, if necessary, a small amount of a binding agent made of fine refractory powder, and then performing at least one step of curing, drying, and solidifying by heat treatment. It is something that forms.

Examples of the inorganic binder used to impart adhesiveness in the manufacturing method of exhaust system equipment of the present invention include silicate binders such as sodium silicate, potassium silicate, and lithium silicate, monobasic aluminum phosphate, monobasic Phosphoric acid binders such as calcium phosphate, monobasic magnesium phosphate, condensed sodium phosphate, phosphoric acid, sol binders such as colloidal silica, colloidal alumina zirconia, and ethyl silicate are suitable.

The binder is used in the form of an aqueous solution, and its concentration is between 20 and 6
0 wt% is preferred. If it is lower than 20 wt%, the adhesive force is small and peeling is likely to occur. Moreover, if it exceeds 5Qwt%, coating work becomes difficult. More preferably, it is 25 to 55 wt%.

Hardeners can also be added to the binder solution. Although the curing agent differs depending on the type of binder, any known curing agent can be used. For example, silicate binders include sodium silicate, calcined aluminum phosphate, dicalcium silicate, carbon dioxide, and the like. Examples of aluminum phosphate include basic oxides such as magnesia and lime, calcium aluminate, and ammonium fluoride.

The fireproof insulation material used to provide insulation is ceramic! It is a porous particle made by granulating IN and/or whiskers, and is a special material.

The porous particles formed by granulating ceramic tIN and/or whiskers contain one or more types of crystalline tUT such as corundum, mullite, and zirconia, and whiskers such as potassium titanate, silicon carbide, and silicon nitride. The particle size is 30 to 2000 μm.
A range of is appropriate.

The reason why the particle size is limited to 30 μm or more is that if it is smaller than 30 μm, cracks and peeling occur due to shrinkage. Also, the particle size was increased to 20
The reason why the thickness is limited to 00 μm or less is that if it is larger than 2000 μm, it is difficult to form a smooth coating layer.

A bonding agent made of fine refractory powder is used to fill in spaces between porous particles formed by granulating ceramic fibers and/or whiskers, and to reinforce the bond. The fine refractory powder is suitably made of the same material as the fibers used and has a particle size of 44 μm or less.

When forming a fireproof heat insulating layer, first, an inorganic binder solution is uniformly applied to the inner surface of the exhaust system-like vessel, and porous particles made by granulating ceramic 41 fibers and/or whiskers are immediately applied to the surface to which the binder solution is applied. Sprinkle a mixture of refractory fine powder with a small amount of bonding aid according to the requirements.

The binder solution permeates between the porous particles and between the binding aids to form a fireproof insulation layer. The thickness of this layer varies depending on the concentration of the binder, the coating thickness, and the particle size of the porous particles;
It is 3000 μm.

A remarkable feature of the present invention is that the fireproof heat insulating layer formed by the above method has a much lower moisture content than a layer coated in the form of a slurry. Due to this feature, shrinkage due to dehydration is reduced in the subsequent drying/solidification process by heat treatment, and the occurrence of cracks and peeling in the fireproof heat insulating layer can be prevented.

The heat treatment of the fireproof heat insulating layer is carried out by gradually heating it to about 300°C. @ Vigorous heating should be avoided as it may cause cracking and peeling.

Next, if necessary, a binder solution is further applied on the above fireproof insulation layer by the same method, porous particles made of ceramic fibers and/or whiskers are attached, and then dried and solidified by heat treatment. let This cycle is repeated several times to obtain a relatively thick refractory insulation layer. In order to ensure sufficient heat insulation, the fireproof insulation layer should have a rating of 1.0 to 5. □
It is desirable that it is mm. The fireproof insulation layer is 1. OIIl
If it is smaller than 5.0 m, the insulation effect will be low, and the fireproof insulation layer will be less than 5.m. O
If it is larger than mm, the heat insulation effect will be large, but the tendency for peeling will be strong. More preferably 1.0 to 3. A range of Omm is appropriate.

The exhaust system equipment with the refractory heat insulating layer formed in this way is placed in the furnace for 8
The coating process is completed by heating to 00 to 1000°C and holding for 15 to 60 minutes.

This heat treatment may be performed by heating in a furnace or by passing hot air through the boat.

Example The present invention will be explained in more detail by the following examples.

Example 1 The inner surface of a cast iron exhaust manifold with an inner diameter of 40mm and a thickness of 5mm having an oxide film was degreased in advance with an alkaline solution of PI-110, and the silica ratio was 2.9° and the concentration was 45.
To 100 parts by weight of a wt% sodium silicate aqueous solution, 10@1 part of calcined aluminum phosphate (Hoechst %HB hardener) was added as a hardening agent, and immediately potassium titanate (K2 Ti 6013) whiskers were applied. Porous particles having a particle diameter of 210 to 44 μm and a bulk ratio of 10.3 were dispersed by a swirling air current and dried and solidified. By repeating this operation 5 times, the thickness becomes 3
A fireproof heat insulating layer of mm was formed.

Finally, heat treatment was performed at 800°C for 30 minutes to complete a cast iron exhaust manifold with a fireproof heat insulating layer on the inner surface.

No cracks were observed in the coating layer of the obtained manifold.

The following tests were conducted on the manifold obtained in Example 1 and good results were obtained.

(1) Heat resistance test Continuously blow hot air at i ooo℃ into the inside of the manifold.
After blowing air for 00 hours, the coating layer was cooled to room temperature, but there was no damage or peeling of the coating layer.

(2) Thermal Shock Test A cycle of blowing hot air at 1000°C into the manifold for 30 minutes and then allowing it to cool to 100°C was repeated 150 times, but no damage or peeling of the coating layer was observed.

(3) Heat insulation test After blowing hot air at 100°C into the inside of the manifold for 30 minutes, the outside surface temperature was measured. The outside surface temperature of the manifold without inner coating was 805°C, but the temperature of the outside surface of the manifold without inner coating was 805°C. The outer surface temperature was 440°C, and it was recognized that it had excellent heat insulation properties.

(4) Vibration test Vibration was continued for 200 hours under the conditions of 20G x 280 Hz, but no damage or peeling of the coating layer was observed.

(5) Constant strain test The test was repeated 100 times by fixing one end of the manifold and applying a vertical load to the other end to give a strain of ±2 mra, but no damage or peeling of the coating layer was observed. .

(6) Furthermore, no damage or peeling of the coating layer was observed in the manifolds that were subjected to other tests for the above-mentioned five types of individual test completed products.

Example 2゜The inner surface of the same cast iron manifold as in Example 1 was degreased in advance with an alkaline solution of PHIO, and the silica ratio was 2.
．． 9. To 100 parts of sodium silicate aqueous solution with a concentration of 45 wt%, 10 parts of calcined aluminum phosphate (wAHB hardener from Hoechst Co., Ltd.) was added as a hardening agent and immediately filled with a bulk specific gravity of 0.41 grains totaling 500 to 1.
000μm mullite fiber (A1203; 80%)
A mixture of a particulate ioomm part and a 2Offl part of alumina of 0.044 μm or less as a binding agent is attached,
A fireproof heat insulating layer with a thickness of 3 mm was formed by the same method as in Example 1, and the same heat treatment as in Example 1 was performed.

No cracks were observed in the coating layer of the obtained manifold.

The following tests were conducted on the manifold obtained in Example 2 and good results were obtained.

(1) Heat resistance test Continuously blow hot air at 1000℃ into the inside of the manifold for 10 days.
After blowing air for 0 hours, it was cooled to room temperature, but there was no damage or peeling of the coating layer.

(2) Thermal Shock Test A cycle of blowing hot air at 1000°C into the manifold for 30 minutes and then allowing it to cool to 100°C was repeated 150 times, but no damage or peeling of the coating layer was observed.

(3) Insulation test After blowing hot air at 1000°C into the inside of the manifold for 30 minutes, the outside surface temperature was measured. The outside temperature of the manifold without inner coating was 805°C, but the temperature of the outside surface of the manifold of the present invention was 805°C. The outer surface temperature was 560°C, and it was recognized that it had excellent heat insulation properties.

(4) Vibration test Vibration was continued for 200 hours under the conditions of 20G x 280 Hz, but no damage or peeling of the coating layer was observed.

(5) Constant strain test The test was repeated 100 times by fixing one end of the manifold and applying a vertical load to the other end to give a strain of ±2u, but no damage or peeling of the coating layer was observed. .

(6) Furthermore, no damage or peeling of the coating layer was observed in the manifolds that were subjected to other tests for the above-mentioned five types of individual test completed products.

Although this experimental example describes a manifold, the present invention is not limited thereto, and can also be applied to the formation of coating layers for exhaust system equipment such as boat liners and turbine housings.

Effects of the Invention The exhaust system equipment of the present invention has a fireproof heat insulating layer in which porous particles formed by granulating ceramic fibers and/or whiskers are fixed to the inner surface, so it has excellent heat insulation, heat resistance, thermal shock resistance, and vibration resistance. It has extremely excellent flexibility, etc., and has a remarkable effect on increasing the useful life of exhaust system equipment, reducing fuel consumption, and increasing output of automobile engines.

Claims (2)

[Claims] (1) An exhaust system device characterized by having a fireproof heat insulating layer in which porous particles made of granulated ceramic fibers and/or whiskers are fixed to the inner surface of the exhaust system device through which high-temperature exhaust gas passes. (2) In the method of manufacturing exhaust system equipment, [1] uniformly apply an inorganic binder solution to the inner surface of the exhaust system equipment, and [2] immediately granulate ceramic fibers and/or whiskers on the layer of the inorganic binder solution. By adhering a mixture of porous particles made of polyurethane and a small amount of a binding agent made of fine refractory powder as needed, and performing the steps of [3] curing, drying, and solidifying by heat treatment at least once. A method for manufacturing exhaust system equipment, characterized by forming a fireproof heat insulating layer.