JPH07166869A - Subsidiary chamber for engine - Google Patents

Abstract

PURPOSE:To contribute to forming an engine into high performance having a sufficient characteristic also in heat resistance or the like with high fracture toughness strength and excellent thermal shock resistance by providing a constitution of a grain dispersing compound ceramics material of dispersing particulates of prescribed amount of titanium carbide and silicon nitride in a crystal of prescribed amount of alumina matrix. CONSTITUTION:A subsidiary chamber for an engine is constituted of grain dispersing compound ceramics material formed by dispersing 1 to 30vol.% titanium carbide particulates and 10 to 30vol.% silicon nitride particulates in a 60 to 70vol.% alumina matrix crystal. That is, in the grain dispersing compound ceramics material, alumina (Al2O3) is used as a ceramics matrix component, and the titanium carbide particulate is dispersed in this alumina to form a nanograin dispersing structure, but in order to obtain higher performance, this ceramics material is a new material of nanodispersing the silicon nitride particulate as the third component.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine sub-combustion chamber for an internal combustion engine, and more particularly to a ceramic material sub-combustion chamber for ceramics, which has advantages over conventional metal sub-combustion chambers for engines. Regarding the combustion chamber.

[0002]

2. Description of the Related Art In automobile engines, a method is provided in which a sub combustion chamber is provided above a piston, and a swirl of air is generated in the sub combustion chamber, and fuel is introduced into the sub combustion chamber for efficient combustion. ing. At the bottom of this engine sub-combustion chamber, the injected flame is hot toward the main combustion chamber,
An inlet (jet port) that moves at high speed is attached.
Therefore, the secondary combustion chamber for an engine is required to have extremely high characteristics in terms of heat resistance, thermal shock resistance, and the like.

Conventionally, the auxiliary combustion chamber for the engine of the internal combustion engine is mainly composed of a heat-resistant metal material, but in response to the recent high performance of the engine, the auxiliary combustion chamber for the engine made of a ceramic material has also been developed. ing. Although this ceramic material is still insufficient in performance, it has been partially put into practical use, and is manufactured by a method such as die pressing, CIP, slip casting, and injection molding.
The manufacturing method itself has no technical characteristics and is a general method.

[0004]

Among the conventional auxiliary combustion chambers for engines, metallic ones cannot be used to improve the performance of the engine by their own materials, and ceramic materials are sprayed onto the metal surface. By using a metal clad material, the characteristics of the material are improved, but a sufficient material has not been obtained.

On the other hand, as a ceramic material, one made of silicon nitride (Si ₃ N ₄ ) ceramics is mainly used as one of the most excellent materials, but it is sufficient in terms of heat resistance and thermal shock resistance. Not a thing.

In such a situation, the combustion characteristics in the auxiliary combustion chamber for an engine have become an important factor due to the improvement of the combustibility with the recent high performance of the engine.
Since the combustion temperature is becoming higher, it is expected that a material capable of sufficiently withstanding this will appear, particularly a material having high fracture toughness at high temperature and excellent heat resistance.

The present invention has been made in view of the above conventional circumstances, and has high fracture toughness and excellent thermal shock resistance,
It is an object of the present invention to provide a sub-combustion chamber for a high performance ceramic engine, which has sufficient characteristics in terms of heat resistance and can withstand high performance of the engine.

[0008]

According to a first aspect of the present invention, there is provided an auxiliary combustion chamber for an engine, wherein 1 to 30% by volume of titanium carbide fine particles are contained in 60 to 70% by volume of an alumina matrix crystal.
It is characterized by being composed of a particle-dispersed composite ceramic material in which ˜30% by volume of silicon nitride fine particles are dispersed.

The sub-combustion chamber for an engine according to claim 2 is 60-
Within the crystal of 70% by volume of alumina matrix, 1 to 3
It is characterized by being composed of a particle-dispersed composite ceramic material in which 0% by volume of titanium carbide fine particles and 5 to 20% by volume of silicon nitride whiskers are dispersed.

The sub-combustion chamber for an engine according to claim 3 is 60-
Within the crystal of 70% by volume of alumina matrix, 1 to 3
What is claimed is: 1. A particle-dispersed composite ceramic material comprising 0% by volume of titanium carbide fine particles, 20% by volume or less of silicon nitride fine particles, and 10% by volume or less of silicon nitride whiskers. Is composed of a particle-dispersed composite ceramic material having a total ratio of 15 to 30% by volume.

The present invention will be described in detail below.

The particle-dispersed composite ceramic material according to the present invention comprises alumina (Al ₂ O ₃ ) as a matrix.
And titanium (Ti) as dispersed particles of the second component.
C) fine particles, and silicon nitride (Si ₃ N ₄ ) fine particles and / or silicon nitride (Si ₃ ) as dispersed particles of the third or fourth component.
N ₄ ) Whiskers are included.

If the proportion of TiC fine particles as the second component in the dispersed particles is less than 10% by volume, a sufficient effect due to the dispersion of TiC cannot be obtained. On the other hand, when the ratio of the TiC fine particles exceeds 30% by volume, the amount of TiC is too large, sufficient stress is not generated, and a toughened ceramic cannot be obtained. Therefore, the proportion of TiC fine particles is 10 to 30% by volume.
And

Further, when containing only Si ₃ N ₄ particles and Si ₃ N ₄ Si ₃ N ₄ particles of whiskers, S
When the proportion of i ₃ N ₄ fine particles is less than 10% by volume, Si ₃ N ₄
A sufficient effect cannot be obtained due to the dispersion of Al, and if it exceeds 30% by volume, the amount of Si ₃ N ₄ is too large to generate sufficient stress. Therefore, the ratio of Si ₃ N ₄ fine particles is 1
It is 0 to 30% by volume.

Meanwhile, if it contains only Si ₃ N ₄ whiskers of the Si ₃ N ₄ particles and Si ₃ N ₄ whiskers, since Si ₃ N ₄ whiskers is difficult uniformly dispersed as compared with the microparticle, the content ratio is less Will be things. However, if the proportion of Si ₃ N ₄ whiskers is less than 5% by volume, S
A sufficient strength improving effect cannot be obtained by dispersing the i ₃ N ₄ whiskers, and if it exceeds 20% by volume, the sinterability deteriorates and the strength decreases. Therefore, the proportion of Si ₃ N ₄ whiskers is 5 to 20% by volume.

When both the Si ₃ N ₄ fine particles and the Si ₃ N ₄ whiskers are contained, the upper and lower limits are set for the same reason as in the case of mixing them alone, and the Si ₃ N ₄ fine particles are 20% by volume or less. , Preferably 10 to 20% by volume,
Si ₃ N ₄ whiskers are 10 vol% or less, preferably 5
In the range of 10 to 10% by volume, Si ₃ N ₄ fine particles and Si ₃ N ₄
The total proportion of whiskers should be 15 to 30% by volume.

Al ₂ O ₃ forming the matrix
As the raw material powder, the average particle diameter is preferably 300 nm or less.

Among the dispersed particles, the average particle diameters of TiC fine particles and Si ₃ N ₄ fine particles are within a range such that they are easily incorporated into Al ₂ O ₃ crystals and that microcracks causing material defects are not generated. For that reason, it is preferable that the average particle diameter of the powder raw material is 700 nm or less, particularly 50 to 500 nm. Also for Si ₃ N ₄ whiskers, for the same reason, an average diameter of 0.3 to
The average length is preferably 0.5 μm and 5 to 30 μm.

In order to manufacture the auxiliary combustion chamber for an engine of the present invention using such a particle-dispersed composite ceramic material, Al ₂ O ₃ fine particles, TiC fine particles, Si ₃ N ₄ fine particles and / or Si ₃ N ₄ whiskers are used. Are mixed at a predetermined ratio, the resulting mixture is molded by various methods such as press molding, injection molding, slip cast molding, and then fired. The firing is 1500 ° C to 17
The optimal condition is 50 ° C. for 1 to 3 hours, and it is possible to use the HIP method, atmospheric pressure sintering method, gas pressure sintering method, or the like.

[0020]

The main problems of the auxiliary combustion chamber for an engine are heat resistance and thermal shock resistance.

As described above, although the Si ₃ N ₄ ceramics engine sub-combustion chamber has been put into practical use, it does not exhibit sufficient performance under the combustion conditions associated with higher engine performance, and thermal shock Due to this, microcracks were generated, and some of them developed into large cracks.

On the other hand, Al ₂ O ₃ ceramics is a material having excellent heat resistance and wear resistance.

The present invention provides an auxiliary combustion chamber for an engine, which is made of such a ceramic composite material having high heat resistance and high thermal shock resistance, which uses such Al ₂ O ₃ ceramics as a matrix.

That is, the particle-dispersed composite ceramic material according to the present invention contains A as the ceramic matrix component.
This is a structure in which TiC fine particles are dispersed in l ₂ O ₃ to form a nanoparticle dispersed structure. However, in order to further improve the performance, Si ₃ N ₄ fine particles and / or
Alternatively, it is a new material in which Si ₃ N ₄ whiskers are nano-dispersed.

The Al ₂ O ₃ —TiC—Si ₃ N ₄ (fine particles and / or whiskers) 3 (or 4) component type nanoparticle-dispersed composite ceramic material has high strength at high temperature and also has high thermal shock resistance. high. In the present invention, the use of this material makes it possible to overcome the drawbacks that cannot be solved by the conventional auxiliary combustion chamber.

This is because the Al ₂ O ₃ matrix ceramics is originally a material having high heat resistance and abrasion resistance, but Al ₂ O _{3 is} dispersed by nano-dispersing TiC fine particles in this material.
Fine particles of TiC are uniformly dispersed in the grain of the matrix, and due to the mismatch of their thermal expansion coefficients, Al ₂
Internal stress is generated uniformly in the O ₃ matrix and in the entire grain. Therefore, due to external thermal stress, A
The l ₂ O ₃ composite material does not easily break. The third to fourth component Si ₃ N ₄ fine particles synergize with the second component TiC fine particles to enhance the effect of adding TiC and enhance heat resistance, thermal shock resistance and toughness. Also,
The Si ₃ N ₄ whiskers act effectively to improve the toughness, in addition to the above effects.

With the above-mentioned mechanism of action, an auxiliary combustion chamber for an engine which exhibits remarkably excellent characteristics with respect to thermal shock from the outside and which is remarkably excellent in various characteristics such as heat resistance and wear resistance.

[0028]

EXAMPLES The present invention will be described more specifically with reference to Examples and Comparative Examples below. The raw materials used are as follows.

Al ₂ O ₃ powder: Showa Metal Co., Ltd. (average particle size 0.25 μm) TiC powder: Nippon Shinkin Co., Ltd. (average particle size 200 nm) Si ₃ N ₄ powder: Ube Industries (average particle size 300 n
m) Si ₃ N ₄ whiskers: manufactured by Tateho Chemical Co., Ltd. (average diameter: 0.
5 μm, average length 10 μm) Examples 1 to 5, Comparative Example 1 Dispersed particles were added to the Al ₂ O ₃ powder in the compounding ratio shown in Table 1 (not added in Comparative Example 1). Add an organic binder (polyvinyl alcohol) and a demulsifier and mix with a ball mill for 3 hours to obtain a solid content of 75
A wt% slurry was prepared. This slurry was molded by the slip casting method. The molding was performed by the gypsum mold method, and a slight pressure (1-2 kg / cm ² ) was applied during the molding.

After air-drying the obtained green form, it is at 50-80 ° C.
After being dried in a dryer for 10 hours, it was baked in a nitrogen atmosphere. Firing is performed by raising the temperature to 1650 ° C. in 10 hours and 2
It was held for a period of time and then naturally cooled.

For the heat resistance test of the obtained sample,
It was cooled from 800 ° C. to 200 ° C. in 10 minutes and examined for the occurrence of cracks. Also, it is 100 with a thermal shock tester.
A thermal shock resistance test was performed in a cycle. Regarding the thermal shock resistance, the one having no crack was “good”, and the one having the microcrack was “poor”. Further, the fracture toughness was measured, and the bending strength was measured at 500 ° C.

The results are shown in Table 1.

[0033]

[Table 1]

As is clear from Table 1, Al of Comparative Example 1
_In contrast to the generation of cracks in the ₂ O ₃ sample, the particle-dispersed composite ceramic material according to the present invention is excellent in heat resistance, thermal shock resistance, heat resistance, high temperature toughness, etc. A secondary combustion chamber for the engine is provided.

[0035]

As described in detail above, the particle-dispersed composite ceramic material according to the present invention has the following properties: wear resistance, thermal shock resistance,
It is remarkably excellent in mechanical strength such as high temperature toughness and bending strength. Therefore, the auxiliary combustion chamber for an engine of the present invention made of such a particle-dispersed composite ceramic material has high characteristics that can withstand high performance of the engine. A secondary combustion chamber for the engine is provided.

Claims (3)

[Claims] 1. A titanium carbide fine particle of 1 to 30% by volume in a crystal of 60 to 70% by volume of an alumina matrix,
An auxiliary combustion chamber for an engine, comprising a particle-dispersed composite ceramic material in which 10 to 30% by volume of silicon nitride fine particles are dispersed. 2. A titanium matrix fine particle of 1 to 30% by volume in a crystal of an alumina matrix of 60 to 70% by volume,
An auxiliary combustion chamber for an engine, comprising a particle-dispersed composite ceramic material in which 5 to 20% by volume of silicon nitride whiskers are dispersed. 3. 60 to 70% by volume of alumina matrix crystals and 1 to 30% by volume of titanium carbide fine particles,
What is claimed is: 1. A particle-dispersed composite ceramic material comprising 20% by volume or less of silicon nitride fine particles and 10% by volume or less of silicon nitride whiskers dispersed therein, wherein the total proportion of silicon nitride fine particles and silicon nitride whiskers is 15 to 30% by volume. %, A sub-combustion chamber for an engine, characterized in that it is made of a particle-dispersed composite ceramic material.