JPS62107087A - Exhaust apparatus - Google Patents

Abstract

PURPOSE:To obtain an exhaust apparatus which can be used for a long period of time under high-temp. gas without cracking by solidifying refractory material powder to form a refractory layer on the inside surface of the exhaust apparatus and further solidifying protective material powder to form a protective layer on the surface of the refractory layer. CONSTITUTION:An aq. sodium silicate soln. added with calcined aluminum phosphate as a hardener is coated on the inside surface of the exhaust apparatus and thereafter a refractory material such as stabilized zirconia particles having about 44-150mum grain size is sprayed and stuck thereon and is heat-treated at about 300 deg.C to solidify the refractory layer. The aq. sodium silicate soln. is coated on the above-mentioned refractory layer and protective material particles such as alumina particles having about 2-6mum grain size are immediately thereafter stuck on the refractory layer to form the protective layer. The apparatus provided with such refractory layer and protective layer is heat- treated at about 950 deg.C. The exhaust apparatus having the excellent coating layer which obviates cracking and exfoliation even after repetition of heating and cooling under the high-temp. gas is thus obtd.

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.

[Conventional technology]

The exhaust system equipment of an internal combustion engine, especially the inner surface of the manifold, is exposed to the high temperature and high pressure combustion gas discharged from the cylinder.
It was strongly affected by this, and had the disadvantage that it could not be used for a long time, and also had the disadvantage that its heat insulation property was low.

JP-A-58-51214 discloses exhaust gas 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 gas equipment for internal combustion engines is
A coating layer of an amorphous refractory made of a mixture of refractory raw material particles and an inorganic binder is formed on the inner surface of a fully curved device body that is in contact with high-temperature exhaust gas.

[Problem that the invention seeks to solve]

This manifold is coated on the inner surface with a monolithic refractory made of a mixture of refractory raw material particles and a heat-resistant inorganic binder, so the coating layer inevitably contains a relatively large amount of moisture and cracks when drying. Not only this, but also the shrinkage during heat treatment is large, which tends to cause peeling and breakage.

Furthermore, there is a high risk that cracks will occur due to thermal shock when rapidly heated by high-temperature exhaust gas.

Furthermore, since the coating material is a monolithic refractory, it is extremely difficult to obtain a manifold that is coated on the inner surface with a uniform thickness.

[Means for solving problems]

In view of these shortcomings, the inventors of the present invention have conducted various studies, and as a result, the inventors of the present invention have developed a protective layer that has a fireproof layer made of solidified fireproof material powder on the inner surface of the exhaust system equipment, and further has a protective material powder solidified on the surface of the fireproof layer. It has a structure having a yL layer.

〔Example〕

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

Example 1 As a first step, a silica ratio of 2.9. 10 wt % of calcined aluminum phosphate (H, B hardener manufactured by Hoechst) was added as a hardening agent to a 45 w % sodium silicate aqueous solution, and the mixture was delivered in a spray form along with 5 kg/cm2 of air through a rotating feed pipe. did.

Immediately after spraying stabilized zirconia particles with a particle size of 44 to 150 μm as a refractory material, the temperature was kept at room temperature for 1 hour, the temperature was further raised to 100°C, kept for 1 hour, and finally at 300'C.
The temperature was raised to 1 and maintained for 1 hour. This heat treatment completely solidified the refractory layer. Repeat this process two more times,
A fireproof layer with a thickness of 3 mm was formed.

As a second step, silica ratio 2.8, concentration 4 is applied on top of the above fireproof layer.
5 kg/cm2 of 2 wt% sodium silicate aqueous solution
Alumina particles having a particle size of 2 to 6 μm were immediately fed through the swirling feed tube to form a protective layer of 0.2 mm.

The manifold on which the refractory layer and protective layer were formed was heat-treated in a furnace at 950° C. for 1.5 hours to complete the coating process.

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

Example 2 As a first step, a sodium silicate aqueous solution with a silica ratio of 3.0 and a concentration of 40 wt% was baked as a hardening agent on the inner surface of a cast iron manifold having an oxide film that had been previously degreased with an alkaline solution of pH 10 to 11. 8 wt % of aluminum phosphate (Hoechst WH, B hardener) was added and fed through a rotating feed tube. Particle size 4 immediately as a refractory material
Stabilized zirconia particles of 4 to 150 μm were fed through a rotating feed tube. Heat treatment was performed by the same method as in Example 1,
The refractory layer was completely solidified. This process was repeated two more times to form a 3 mm thick fireproof layer.

As a second step, a sodium silicate aqueous solution with a silica ratio of 2.8 and a concentration of 42 wt% was sprayed together with 5 kg/cm'' of air onto the above refractory layer in the form of a spray, and immediately after that, the particle size was 2. Zirconia particles of ~6 μm were fed through a rotating feed tube to form a protective layer of 0.2 mm.

The manifold on which the fireproof layer and protective layer were formed was heat-treated in the same manner as in Example 1 to complete the coating process.

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

The following tests were conducted on the manifolds obtained in Examples 1 and 2, and good results were obtained.

(1) Heat resistance test Continuously blow hot air at 1,000℃ into the inside of the manifold for 10 days.
After blowing air for 0 hours, it was cooled to room temperature, but no damage or peeling of the coach ink layer was observed.

(2) Fever? A cycle of blowing hot air at 1,000°C for 30 minutes into a 1-ton test manifold 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) 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.

(4) 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 mm, but no damage or peeling of the coating layer was observed.

(5) Furthermore, no damage or peeling of the coating layer was observed on the manifolds that were subjected to other tests on the above four types of individual test completed products.

Although this embodiment has been described with respect to 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 port liners and turbine housings.

In addition, the protective layer, which is the final layer, has a fine particle size of 20 μm or less, so it is dense and the moisture generated by decomposition when the fuel gasoline is burned condenses in cold regions and prevents it from penetrating into the fireproof layer. In addition to preventing this, this layer is provided to smooth the inner surface of the manifold and reduce air flow resistance.

〔Effect of the invention〕

Since the exhaust system equipment of the present invention has a fireproof layer and a protective layer, it has an excellent coating that does not cause cracks or peeling even after repeated heating and cooling with high-temperature gas, vibration tests, constant strain tests, etc., as shown in the above test results. It has layers.

Claims (1)

[Claims] 1. An exhaust system device comprising: a fireproof layer made of solidified fireproof material powder on the inner surface of the exhaust system device; and a protective layer made of solidified protective material powder on the surface of the fireproof layer.