JPH0774601B2 - Ceramics turbine scroll and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramics turbine scroll and a method for producing the same, and more particularly to a ceramics turbine scroll comprising a composite of ceramics and a metal for reducing heat dissipation and a method for producing the same. It is a thing.

[0002]

2. Description of the Related Art Recently, fine ceramics technology has attracted attention, and various parts are manufactured by using the ceramics manufactured by this technology. For example, many ceramics parts are also used in internal combustion engines for automobiles. .

The types of ceramics are extremely large, and each has their own characteristic points as physical properties. However, in the case of constructing a component that must have many features, such as a component of an internal combustion engine, 1
Since it is not possible to realize with various kinds of ceramics, it is necessary to combine several kinds of ceramics having different characteristics, or to combine ceramics and metals, to devise a ceramics composite structure that meets the required characteristics.

An example of a component using such a ceramic composite is a scroll for an internal combustion engine.

A conventional scroll for an internal combustion engine using a ceramics composite uses a ceramics composite in which a spiral tubular body made of aluminum titanate is surrounded by a metal such as aluminum or cast iron. Things are known.

[0006]

The conventional scroll of the internal combustion engine as described above has a good heat insulating property, but since aluminum aluminum titanate has a low strength level, it is difficult to be solidified and contracted during casting. It has a drawback that it is easily broken due to the generated stress, the thermal stress generated during operation, or other causes.

The present invention is intended to eliminate the above-mentioned conventional inconveniences, and an object of the present invention is to fabricate a turbine scroll made of a composite of ceramics and a metal, which can withstand a severe heat cycle and can be manufactured. It is to obtain a simple and low-cost ceramics turbine scroll and a manufacturing method thereof.

[0008]

In order to solve the above problems, the present invention provides all elements of silicon (Si), nitrogen (N), oxygen (O) and titanium (Ti), zirconium (Zr). , Hafnium (Hf), yttrium (Y), boron (B), aluminum (Al), and at least one kind of a group of pores.
A ceramics turbine scroll characterized in that ceramics containing 2% or more and a metal are arranged on the outer surface thereof.
And silicon (Si) as a main component, which contains all elements of nitrogen (N) and oxygen (O), and titanium (Ti), zirconium (Zr), hafnium (H).
f), a step of forming a mixed powder containing at least one element selected from the group of elements of yttrium (Y), boron (B), and aluminum (Al), and a spiral-shaped ceramics turbine scroll using the mixed powder. -A step of forming an inner cylinder of a slag, a step of sintering the spiral shape in a nitrogen atmosphere to nitride and sinter each element contained therein, and an oxygen-containing step after the nitriding and sintering step. In a molten atmosphere, the inner cylinder of the ceramics turbine scroll, which is a sintered part formed through the above steps, is heated in a molten atmosphere to change a part of the nitride into an oxide. Provided is a method for producing a ceramics turbine scroll, which comprises a step of immersing and depositing a metal around the inner cylinder, and a step of processing the deposited metal into a desired shape. To do.

[0009]

EXAMPLES Examples of the present invention will be described in detail below. First, the ceramics turbine scroll according to the present invention will be described.

In FIG. 1, reference numeral 1 is an exhaust pipe of an internal combustion engine, and a turbine housing 2 is provided with a turbine scroll 2 at a lower portion thereof. 3 is a turbine wheel. Exhaust gas exhausted from the internal combustion engine flows as indicated by the arrow. A spiral-shaped inner cylinder 5 made of ceramics according to the present invention is provided inside the ceramics turbine scroll, and an outer cylinder 6 made of stainless steel is formed outside thereof.

In FIG. 2, a ceramics turbine scroll 2 is an inner cylinder 5 made of ceramics by a manufacturing method described later.
It is obtained by forming the outer cylinder 6 by casting the inner cylinder 5 with a metal such as stainless steel.

The inner cylinder 5 of the ceramics turbine scroll 2 is manufactured as follows. Silicon (Si)
Metallic titanium (Ti) powder 5 to 100 parts by weight of the powder
Parts by weight are added, and a predetermined amount of oil is mixed therein, and then kneaded with a pressure kneader to prepare a composition having plasticity.

Separately, a mold for producing an inner cylinder is prepared, and the above composition is filled in the mold. Afterward, after pressing with a pressure of about 0.4 ton / cm @ 2, the molded composition is taken out of the mold. In addition, the ceramics turbine scroll
Since the rule 2 has a spiral tube shape, a molded product cannot be produced by a single pressing process. Therefore, first, two gutter-shaped molded products made of the above-mentioned composition in which a spirally-shaped cylindrical inner cylinder is vertically divided are made, and these are bonded with an adhesive to form a cylindrical inner cylinder, which is used in a furnace. Put in a nitrogen atmosphere up to 500 ℃
And degreasing and baking at a maximum of 1400 ° C. in the same nitrogen atmosphere. By this calcination, the above composition is completely nitrided, and pores having a volume close to 15% and having uniformly dispersed pores are formed therein.

Next, this was heat-treated in the atmosphere at 1000 ° C. According to the dimension measurement after the heat treatment, the dimension of the inner cylinder is almost the same as the dimension at the time of molding with the mold. A turbine scroll for a diesel engine is produced by casting the outer periphery of the inner cylinder thus produced with a metal such as aluminum or cast iron. As one of the methods of casting metal around the inner cylinder, after closing both sides of the inner cylinder, immersing it in molten metal and then pulling it up to deposit metal around the inner cylinder. Then, an outer cylinder is formed, and then the metal is cut to finish it into a desired shape. The thermal conductivity, strength, coefficient of thermal expansion of the inner cylinder after sintering in the atmosphere and the product identification results by X-ray are shown in FIG.
And shown in the diagram of FIG.

The ceramic inner cylinder 5 manufactured by the above manufacturing method has the same level of thermal characteristics as the conventional inner cylinder made of aluminum titanate.
It can be seen from the diagrams of FIGS. 3 and 4 that the strength is greatly superior.

Incidentally, this ceramic turbine scroll
No damage occurred during the production of the inner cylinder or when the outer cylinder was cast around the inner cylinder. In addition, the ceramic target
As a result of performing a bench test by connecting the bin scroll to the exhaust pipe of the diesel engine, there is no problem in durability. Although it is a problem outside the scope of the present invention, it was also found that the exhaust energy does not escape from the scroll of the ceramic internal combustion engine to the outside, so that the fuel consumption rate is also improved by about 2.9% as compared with the conventional one. .

In addition to the above examples, in the present invention, the percentage of the metal powder blended with silicon Si powder as a base is changed, the type thereof is changed, the percentage of the ceramic powder is changed, and the type thereof is changed. By changing the above, an inner cylinder made of ceramics similar to that in the above-mentioned example was prepared. In the diagram of FIG. 3, the embodiment numbers 2 to 9 and in the diagram of FIG. 4 are the examples 10 to 13.

In the following embodiment, the inner cylinder of the embodiment 1 which has been sintered up to the atmosphere is immersed in a polycarbosilane solution or an organic silicon polymer solution, and the ceramic is contained in the pores inside the ceramic. After being soaked, a heat treatment was performed under a predetermined condition in the air or an ammonia atmosphere to convert this portion into a thin nitride film. After that, a ceramics turbine scroll was manufactured in the same manner as in the above-mentioned example.
The strength of the ceramics turbine scroll thus constructed is slightly increased as compared with that of the first embodiment.

Further, in the next embodiment, the polycarbosilane paste or the organosilicon polymer paste having a viscosity higher than that of the polycarbosilane solution or the organosilicon polymer solution used in the above embodiment is sintered up to the atmosphere. After coating on the surface of the inner cylinder of the ceramics turbine scroll of Example 1, it was fired under the same conditions as above to form a thin nitride film on the surface of the inner cylinder. After that, a ceramics turbine scroll was manufactured in the same manner as in the above-mentioned example. In the ceramics turbine scroll thus constructed, the inner wall of the inner cylinder of the ceramics turbine scroll, which is in contact with the exhaust gas, is covered with a thin nitride film. Heat insulation is improved.

Among the materials examined in the above-mentioned group of Examples, aluminum titanate (TiAl ₂ O ₅ ) of Example 10: 15% and titanium (Ti): 10% were added, and the steps up to the treatment in the atmosphere were carried out. The resulting porous and low thermal conductivity ceramic material was dipped in a polycarbosilane solution diluted with toluene, and the pores formed in the ceramic were impregnated with it, followed by thermal decomposition in an ammonia atmosphere. A part of the surface of the pores was composed of amorphous ceramics by heat treatment in a nitrogen atmosphere. The material thus obtained is
As shown in the diagram of FIG. 4, the amorphous ceramics adhere to the pores in the porous ceramics. The porous ceramics thus formed has a porosity of 20.1.
%, Which is 17.1%, which is about 3% less than the original material, but the strength has been improved by 16%. This was also seen in all the examples. It was also confirmed that the thermal conductivity was at the same level as before this processing.

[0021]

INDUSTRIAL APPLICABILITY The present invention relates to a ceramics turbine scroll composed of a composite of ceramics and a metal, wherein an oxide composite reaction-sintered ceramics is used in place of aluminum titanate which is a ceramic constituting a tubular body. Since the turbine scroll is constructed, the thermal conductivity is about the same as that of the conventional type, but the strength is three times that of the conventional type, and the reliability of the parts used in the part where the heat cycle is intense is improved. . Further, since the dimensional change rate at the time of sintering is small and the variation in the change rate is small, the mold design becomes easy. Further, for the same reason, the processing amount after sintering becomes small, which leads to low cost of parts.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view of a ceramics turbine scroll.

FIG. 2 is a lateral cross-sectional view of a main part of a ceramics turbine scroll.

FIG. 3 is a diagrammatic chart.

FIG. 4 is another diagram.

[Explanation of symbols]

 1 ... Exhaust pipe of internal combustion engine 2 ... Turbin scroll 3 ... Turbin wheel 4 ... Turbin housing 5 ... Inside Cylinder 6 ... Outer cylinder

Claims (8)

[Claims] 1. Silicon (Si), nitrogen (N), oxygen (O),
Of all elements and titanium (Ti), zirconium (Z
r), hafnium (Hf), yttrium (Y), boron (B), aluminum (Al) and at least one element selected from the group consisting of at least 12% of pores and a metal on the outer surface thereof. The ceramics turbine scroll which is characterized in that 2. A ceramics turbine scroll according to claim 1, wherein amorphous ceramics are formed inside said pores. 3. A ceramics turbine scroll according to claim 1, wherein a dense ceramics thin film is formed on the inner surface of said ceramics containing 12% or more of pores, which is not in contact with the metal. 4. The ceramics turbine scroll according to claim 1, wherein the metal on the outer surface is aluminum. 5. The ceramics turbine scroll according to claim 1, wherein the metal on the outer surface is cast iron. 6. Silicon (Si) as a main component, containing all elements of nitrogen (N) and oxygen (O), and titanium (Ti), zirconium (Zr), hafnium (H).
f), a step of forming a mixed powder containing at least one element selected from the group of elements of yttrium (Y), boron (B), and aluminum (Al), and a step of forming a ceramic turbine scroll using the mixed powder. A step of forming an inner cylinder, a step of sintering the inner cylinder in a nitrogen atmosphere to nitride and sinter each contained element, and a heating in an atmosphere containing oxygen after the nitriding and sintering step. And a step of converting a part of the nitride into an oxide, and an inner cylinder of a ceramics turbine scroll, which is a sintered part formed through the above-mentioned steps, is dipped in a molten metal. A ceramics turbine scroll including a step of depositing a metal around a cylinder and a step of processing the deposited metal into a desired shape.
Manufacturing method. 7. After the step of heating a part of the inner cylinder in an atmosphere containing oxygen, it is immersed in a polycarbosilane or organic silicon polymer solution and then heat-treated to form a thin nitride film on the surface of the pores. 7. The method for manufacturing a ceramics turbine scroll according to claim 6, further comprising the step of forming. 8. After the step of heating a part of the inner cylinder in an atmosphere containing oxygen, polycarbosilane or an organosilicon polymer paste is applied to the inner surface of the inner cylinder, and then heat treated to heat the inner cylinder. 7. The method for manufacturing a ceramics turbine scroll according to claim 6, further comprising the step of forming a thin nitride film on the inner surface.