JPH05295352A - Abrasive material or tool material comprising al2o3-based composite ceramic, and its production - Google Patents

Abstract

PURPOSE:To provide the objective material excellent in fracture toughness, hardness, strengths, abrasion resistance, etc. CONSTITUTION:This material essentially comprises 80-99vol.% matrix consisting mainly of alpha-Al2O3 and 1-20vol.% at least one kind of reinforcing particles selected from the group consisting of particles of highly fire-resistant compds. including SiC, Si3N4, TIC, TiN, and TiCN. The particles are dispersed in each particle of alpha-Al2O3. When the matrix is fractured, alpha-Al2O3 particles exhibit intraparticle fracture due to the reinforcing particles dispersed in alpha-Al2O3 particles, thus always generating sharp cutting egdes on abrasive particles and at the tip of a tool.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a high toughness Al ₂ O ₃ -based composite ceramic abrasive material, a tool material (particularly a cutting tool), particularly a high toughness, high hardness, high wear resistance Al ₂ O ₃ -based composite ceramic abrasive material, A tool material and its manufacturing method.

[0002]

2. Description of the Related Art Al ₂ O ₃ has hitherto been characterized by electrical properties, characteristic features such as high hardness, dimensional stability, easy sinterability,
It is widely used industrially as a substrate and package for integrated circuits, chips for cutting tools, abrasives for grinding tools, wear-resistant parts, and fire-resistant materials because of its productive characteristics such as low cost of raw materials. When used as a tool, its life depends not only on the wear resistance of Al ₂ O _{3 due to} its high hardness, but it is actually affected by chipping and cracking of the tool, and must be replaced even when wear is extremely small. In many cases, the strength, particularly toughness, is desired to be further improved. However, Al ₂ O ₃ has a low absolute toughness, and it is at the limit of providing a wide and high-performance ceramic tool with only Al ₂ O ₃ .

Attempts have been made to add and disperse the second component in order to increase the strength and toughness of Al ₂ O ₃ . For example, JP-A-59-3766 and JP-A-61-2196.
No. 4, JP 61-174165, and JP 63-28.
No. 2158, etc. In these documents, the increase in strength and toughness of Al ₂ O ₃ are described, but the second component added is mainly present between the particles of Al ₂ O ₃ forming the matrix, that is, at the grain boundaries. Therefore, there is a limit to the Al ₂ O ₃ sintered body that causes grain boundary fracture at the time of fracture, and further improvement in strength and toughness cannot be expected. Further, in a sintered body in which grain growth is not sufficiently controlled because grain boundary destruction occurs, chipping is large, the tool tip is rounded like the shape of the grain, and a sharp cutting edge cannot be expected.

On the other hand, the Al ₂ O ₃ -based abrasive is manufactured by a melting method or a sintering method. Generally, the abrasive produced by the above method is for heavy grinding. In recent years, precision grinding is one of the items required for abrasives,
This is because super-abrasive grains such as diamond and cubic boron nitride (CBN) are the mainstream, and Al ₂ O ₃ -based abrasives are not suitable.

However, such superabrasive grains are 100 to 200 times as expensive as the Al ₂ O ₃ -based abrasive, and are not practical as abrasives consumed in large quantities. Therefore, various improvements have been made to low-priced Al ₂ O ₃ -based abrasives, and production of Al ₂ O ₃ -based abrasives that can be sufficiently used for precision grinding has been attempted. JP-A-56-32369 and JP-A-60-2
Japanese Patent No. 31462 proposes a sintered body abrasive material using a sol-gel method. However, the sol-gel method generally involves complicated steps, and there are many unstable factors in mass production. Moreover, sufficient effects have not been obtained in wet grinding, which occupies most of precision grinding. Further, when the abrasive material produced by the sintering method is damaged or worn, as described above,
If grain growth of Al ₂ O ₃ caused by grain boundaries of Al ₂ O ₃ is not sufficiently suppressed during firing, the amount of chipping is large, and the tip of the abrasive is rounded like the shape of the grain. For this reason, the abrasive material is significantly damaged and the sharpness becomes poor.

Further, as an Al ₂ O-based sintered body as a general structural material, TiN and Si are contained in alumina crystal grains.
It is generally known as a nanocomposite material to improve the toughness and strength by containing intragranularly dispersed particles such as C, TiC and Si ₃ N ₄ (Japanese Patent Application No. 64-87552, JP-A-1-188454, 2-229756, 2-2297
57 and NIKKEI MECHANICAL 1990.6.25 No. 1-8 new original papers). However, it is known that toughness enhancement as a structural material generally does not match the special properties required for conventional abrasives.

An object of the present invention is to overcome the above-mentioned drawbacks of conventional Al ₂ O ₃ -based abrasives and tools, to provide excellent wear resistance and chipping resistance, and to always provide stable sharpness.
An object is to provide a ₂ O ₃ -based composite ceramic polishing material and a tool material, and a method for producing the same.

[0008]

The Al ₂ O ₃ -based composite ceramic polishing material of the present invention comprises a matrix containing α-Al ₂ O ₃ as a main component in an amount of 80 vol% to 99 vol%, and a carbide or nitride of Si or Ti. And one or more dispersion strengthening particles in carbonitride 1
.About.20 vol%, and the dispersion-strengthening particles are α-
It is characterized in that it is dispersed in Al ₂ O ₃ particles and is destructible within the particles. The tool material (particularly usable as a cutting tool) of the present invention is the above-mentioned "Si, Ti" replaced with "Si".

The dispersion toughening particles have a fracture toughness value of 4.5 MPam ^1/2 or more and a hardness of 17 GPa or more (preferably 20 GPa or more) due to the effect of being dispersed in α-Al ₂ O ₃ particles forming a matrix. Excellent chipping resistance and wear resistance. Dispersion-enhancing particles are typically nanoparticles (particle size 1 μm
but less than about 2 μm for the purposes of the present invention, depending on the size of the Al ₂ O ₃ matrix crystal grains.

That is, the high refractory dispersion strengthening particles (which preferably have a certain thermal expansion difference) with Al ₂ O ₃ are mixed with α-A.
By dispersing in 1 ₂ O ₃ particles, both strength and toughness are sufficiently increased, and at the time of material breakage, α-Al ₂ O ₃ particles cause intra-particle fracture, so that the tool tip always has a sharp cutting edge. By providing the above, an Al ₂ O ₃ -based composite ceramic polishing material and a tool material capable of providing stable sharpness are provided.

In the production method of the present invention, a compounded powder containing 1 vol% to 20 vol% of the above dispersion-strengthening particles having a particle size of 1 μm or less and the balance being Al ₂ O ₃ powder having a particle size of 1 μm or less is prepared, and 1400 °. It is characterized in that it is sintered at ˜1800 ° C. to obtain an intra-particle dispersion strengthened and intra-particle destructible Al ₂ O ₃ -based composite ceramic abrasive material.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, as the dispersion-strengthening particles in the Al ₂ O ₃ crystal particles, ceramic particles having substantially higher refractory and hardness than Al ₂ O ₃ are used. Examples of the reinforced dispersed particles include abrasive materials such as Si and Ti carbides, nitrides, and carbonitrides, and SiC and Si.
₃ N ₄ , TiC, TiN, TiCN and the like. However, examples of the tool material include Si carbide, nitride, and carbonitride.

The amount of the reinforcing dispersed particles is preferably 2-10 vo.
l% The particle size of the reinforced dispersed particles should be about 2 μm or less, and should be about 5 compared to the size of the alumina matrix crystal particles.
It is preferably 1/20 to 1/20, and typically, a thickness of about 0.2 μm to 0.7 μm can be obtained. For the purpose of the present invention, it is preferable that the size of the alumina crystal particles is in the range of 0.5 to 100 μm.

[0014]

The function of the Al ₂ O ₃ -based composite ceramic material of the present invention will be described in more detail.

Al ₂ O ₃ is originally an anisotropic particle, and a shear stress is generated at a grain boundary due to anisotropy of thermal expansion during cooling after firing. Therefore, grain boundary destruction always occurs when the sintered body is damaged. To prevent the grain boundary fracture, Al ₂ O ₃ than the Al ₂ O ₃ in the particles are dispersed highly refractory or different particle thermal expansion, Al ₂ O ₃ in the cooling process after firing of Al ₂ O ₃
A local residual stress or a void effect is generated in the particles and used. This local stress causes a transition around the dispersed particles. This transition is pinned by dispersed particles that are harder than Al ₂ O _{3 at} a temperature higher than that of Al ₂ O ₃ , forming sub-grain boundaries, dividing the inside of the grains of the matrix, and substantially refining. This reduces the size of the fracture source. Also, A
The dispersed particles present in the l ₂ O ₃ particles deflect or trap the cracks at break. With such a mechanism, the Al ₂ O ₃ -based composite ceramic material is substantially significantly increased in strength and fracture toughness. That is, by using the Al ₂ O ₃ -based composite ceramic material having high strength and particularly high toughness, it is possible to reduce chipping and cracking of the tool material, exhibit the original performance of each material, and
The life can be extended and unnecessary tool replacement can be omitted.
In addition, when the Al ₂ O ₃ -based composite ceramic material of the present invention is used for abrasive particles, the abrasive particles during grinding are remarkably excellent in strength and particularly toughness as compared with conventional Al ₂ O ₃ -based abrasive particles. The damage of can be drastically reduced and the performance of the material itself can be demonstrated.

Regarding the coefficient of thermal expansion, Al ₂
SiC 4.3-4.5 for 8 × 10 ⁻⁶ cm / ° C. of O _3.
X10 ^-6 , Si ₃ N ₄ 4.8 x 10 ^-6 , TiC 7.61 x
10 ⁻⁶ , TiN 9.35 × 10 ⁻⁶ cm / ° C., and the same effect is obtained even when the difference in thermal expansion is not so large.

In addition to the above, the sub-grain boundaries formed in the Al ₂ O ₃ particles which are the matrix by the addition of the dispersed particles as described above make the Al ₂ O ₃ -based composite ceramic polishing material and tool material of the present invention extremely Shall be characterized as This will be described in detail below.

Microscopically observing the state of wear of the Al ₂ O ₃ -based cutting tool and the sintered abrasive grains, not only when the Al ₂ O ₃ particles themselves are worn so as to be scraped, but also when the Al ₂ O ₃ particles are worn. Is often dropped from the grain boundaries. This is A as mentioned above
This is because l ₂ O ₃ has anisotropy and thus has residual stress at the grain boundaries. For this reason, the high hardness inherent to Al ₂ O ₃ is often not fully utilized. Grain growth during firing must be sufficiently suppressed in order to reduce the loss of particles, but this is unsuitable for large-scale production due to many unstable factors, and it exists stochastically. It is inevitable to use coarse particles. On the other hand, attempts have been made to suppress the grain growth by adding some additives to Al ₂ O ₃ and firing the composite material, but in any case, it is unavoidable that they fall from the grain boundaries. It was When falling off from the grain boundary, there is always a grain boundary at the tip of the tool or the abrasive grain, and since it remains the shape of the grain, it has a microscopically rounded shape.
On the other hand, according to the Al ₂ O ₃ -based composite ceramic polishing material and the tool material according to the present invention, residual particles are eliminated from the Al ₂ O ₃ grain boundaries due to the dispersed particles, and the destruction from the grain boundaries can be suppressed. For this reason, the inherent hardness of the material can be utilized. In addition, since the sub-grain boundaries are formed within the grains, there is an effect of substantially suppressing grain growth. Since the fracture occurs from the sub-grain boundary, the amount of dropout at the time of fracture is overwhelmingly smaller than that of the conventional Al ₂ O ₃ -based tool. That is, the amount of wear can be reduced, which is effective for the tool life. In addition, because of the intragranular fracture from the sub-grain boundaries, the tip of the tool or the abrasive grain has a sharp shape, and has the effect of improving the sharpness. According to the Al ₂ O ₃ -based composite tool material or abrasive material of the present invention, it is possible to obtain a tool having good sharpness, a long life and less chipping, or abrasive particles having a good sharpness and a long life.

The Al ₂ O ₃ composite ceramic material of the present invention will be further described.

The matrix of the composite material is α-Al ₂
O ₃ , and the dispersed particles are SiC, Si ₃ N ₄ , TiC,
It is made of one of TiN and TiCN, and is preferably made of one or more of SiC and Si ₃ N ₄ as a material for cutting tools. The particle size of Al ₂ O ₃ after firing is 0.5 to 10
0 μm (however, the average particle size is preferably on the order of several tens of μm or less), and the particle size of the dispersed particles is Al ₂
A value of about 2.0 μm or less is taken corresponding to the particle diameter of O ₃ , and the dispersed particles are dispersed in the Al ₂ O ₃ particles. The particle diameter and the dispersion state of the particles are determined by a transmission electron microscope.
To be observed. The amount of dispersed particles is 1 vol% to 20 vol%, preferably 2 vol% to 10 vol%. Below 1 vol%,
The effect of dispersing the particles within the particles is not sufficiently obtained. This is because if it is 20 vol% or more, the sintering is difficult to proceed, and if the firing temperature is raised, not only is it uneconomical, but abnormal grain growth may occur. Al
_When the particle diameter of ₂ O ₃ is 0.5 to 100 μm, the strength and toughness characteristics show good values. (More preferably 0.5-
5 μm)

The method for producing the Al ₂ O ₃ -based composite ceramic material of the present invention will be further described.

The starting material of the composite material is α-Al ₂ O ₃ or γ-Al ₂ O ₃ having an average crystal grain size of 1 μm or less.
Powder, SiC having an average crystal grain size of 1 μm or less, Si
₃ N ₄ , TiC, TiN, and TiCN are mixed with one kind of dispersion strengthening particles. Al ₂ O ₃ is 1 μm
The following average crystal grain size is preferable because sintering easily proceeds and it is necessary to incorporate dispersed particles into matrix particles during firing. The reason why the particle size of the dispersion strengthening particles is 1 μm or less is to facilitate the incorporation into the Al ₂ O ₃ particles of the matrix. The raw material Al ₂ O ₃ may be α or γ as long as it becomes an α type after firing, but it is desirable that the purity is as high as possible. This is because the characteristics after sintering are greatly affected. (Eg purity 9
The use of high-purity Al ₂ O ₃ (9.8% or more, more preferably 99.9% or more) can minimize the grain boundary phase component of the Al ₂ O ₃ crystal grains of the composite sintered body.

The raw material powders may be mixed by either a wet method or a dry method, or both, but it is necessary that they are sufficiently mixed. If the mixing is insufficient, not only the firing density is not improved, but it is necessary to raise the firing temperature,
It causes deterioration of the characteristics after firing.

In order to prevent the dispersed particles from being oxidized, firing is preferably carried out in a vacuum atmosphere, an inert atmosphere such as N ₂ or Ar, or a reducing atmosphere such as H ₂ depending on the dispersed particles. If the firing can be performed sufficiently and the densification of the sintered body progresses, an atmospheric furnace,
Either a hot press furnace or a HIP furnace may be used,
To control densification and grain growth, the firing temperature is 1400 ° ~
1800 ° C is preferred. Pre-molding is preferably performed as necessary during sintering.

The method for producing the abrasive particles will be particularly described. The mixed powder is made into a green compact by CIP molding. The green compact is crushed and then sieved so as to obtain a desired particle size. Hexagonal boron nitride powder (hBN) is premixed as a refractory powder medium in order to prevent particles from sticking together during firing. After firing, this hBN is washed and then re-sieved to obtain a desired particle size.

The present invention will be described in more detail based on examples.

[0027]

【Example】

Example 1 Preparation of Mixed Powder Commercially available γ-Al ₂ O ₃ (purity 99.9% or more, average particle size 0.4 μm or less) and β-SiC (purity 98% or more, average particle size 0.3 μm or less). ) Was used as the starting material. γ-Al ₂
O ₃ 95 vol%, β-SiC 5 vol%,
The total amount was 100 g. This was put in a 500 ml polyethylene wide-mouthed bottle together with about 100 g of Al ₂ O ₃ boulders and ethanol, and wet-mixed for 10 hours. After the mixed powder has been dried sufficiently, it is reused together with about 100 g of Al ₂ O ₃ boulders,
Dry mixing was carried out for 24 hours.

(Example 2) Firing The powder mixture was filled in a carbon die (inner diameter 50 mm), and hot-press firing (thickness 5 mm after firing) was performed at 1600 ° C. in an atmosphere of 30 MPa N _{2 for} 1 hour. It was The following test was performed using this as a test material.

Example 3 Characteristic Evaluation As a result of measuring the density of the sintered body by the Archimedes method,
It was 3.89 g / cm ³ . This is 95 vol% -αAl ₂ O ₃
It was 99.0% of the theoretical specific gravity arithmetically determined from the theoretical density of 5 vol% -βSiC, and it was confirmed that the densification of sintering was progressing. Regarding the microstructure,
As a result of TEM observation, the average crystal grain size of α-Al ₂ O ₃ was 10 μm and that of β-SiC was 0.5 μm.
It was confirmed that the particles were dispersed in ₂ O ₃ particles. Next, a three-point bending test piece was prepared from the test material according to JIS R1601. Regarding this, the three-point bending strength at room temperature was measured according to JIS R1601. As a result,
The average bending strength was 935.1 MPa, and it was confirmed that the strength was sufficiently high. The fracture toughness value was measured by the IM method using the test piece after measuring the bending strength.

As a result, the fracture toughness value of this test material was 4.8.
MPam ^1/2 , Vickers hardness measured at the same time is 2
It was 0.1 GPa. From the above results, it was confirmed that the dispersion-strengthening particles were dispersed in the Al ₂ O ₃ particles that were the matrix, and that this material had sufficiently high strength and high toughness.

Example 4 Production and Evaluation of Grinding Stone 1. In the preparation of the mixed powder, the prepared mixed powder was put in a vinyl bag for cold isostatic pressing (CIP), deaerated, and vacuum-packed. About 1.5 Ton / cm ² per bag
After performing CIP with the pressure of 1, the green compact was taken out and crushed in a mortar. This was sieved to a desired particle size and lightly mixed with 200 g of hexagonal boron nitride (hBN) powder in a vinyl bag. After filling this powder in a graphite mold, hot press it at 1600 ° C and 30MPa in a nitriding atmosphere.
Burned for hours. The calcined product was sieved with hBN powder as a pressure medium and then completely separated and washed with an ultrasonic cleaner. The washed main sintered body was dried in a drier to sufficiently remove water, and sieved again with # 60 to obtain abrasive particles.
When the characteristics of this were measured, the density was 3.89.
g / cm ³ , Vickers hardness, 20.0 GPa, and from the TEM observation results, the particle size of α-Al ₂ O ₃ as a matrix was 10 μm on average, and the average particle size was 0 in the particles of Al ₂ O _3. It was observed that β-SiC particles of 0.5 μm were dispersed. From the above, it was confirmed that the characteristics substantially the same as those of the test piece evaluated by the characteristic evaluation of 3 were obtained by the main forming and sintering methods.

A vitrified grindstone was produced in the following manner using the abrasive particles. By adding 89.7 parts by weight of abrasive particles, 10.3 parts by weight of vitrified binder, and 3.1 parts by weight of dextrin (organic binder), mixing and pressing to form a molding density of 2.20 g / cm ³ , Manufactured. Next, put these raw whetstones in an electric furnace and heat at 50 ° C / hr.
It was heated up to 1100 ° C. at a heating rate of and was baked at the same temperature for 6 hours. Thereafter, the heating was stopped and the mixture was allowed to cool in the furnace. The vitrified binder used was made of feldspar, clay and frit glass (borosilicate glass). The obtained grinding wheel contained 46.9 vol% of abrasive particles and 8.
1vol%, pores 45vol%, density 2.07g / cm ³
Met.

The dimensions of the grinding wheel were 200 mm outer diameter × 19 mm thickness × 76.2 mm inner diameter. This was used as a test grindstone.

Next, a grinding test was performed using this grindstone. For comparison with this grindstone, a grinding grindstone using abrasive particles using a fused alumina single crystal was used. This comparative grindstone was manufactured in the same manner as the test grindstone except that the abrasive particles were different from the test grindstone. The conditions of the grinding test were as follows.

Machine: Okamoto Heiken CFG-52AN Grindstone peripheral speed: 2000 m / min Cutting depth: ΔR 20 μm / pass dry plunge Down Cut Work material: SKD-1 (hardness H _RC- 60) Dimension: Length 100 × high 50 x width 10 (mm) Work width: 10 mm Dress: Single stone dresser

[0036]

[Table 1]

The results of the grinding test are shown in Table 1. The maximum power value is the value per 10 mm width of the grindstone. As is apparent from Table 1, the test grinding wheel of the present example is a molten Al ₂
Grinding ratio is about 4 compared with the comparative grindstone using O ₃ single crystal
The surface roughness and the maximum power value are almost the same, and the performance is low noise. Further, it was confirmed that grinding burn was small.

(Example 5) Preparation and evaluation of cutting tool 1. Preparation of mixed powder and 2. S obtained by firing
to prepare a cutting tool using the iC-Al ₂ O ₃ composite ceramic tool materials. The tool shape is SNGN433,
This was subjected to the following tests. High purity Al as a comparative sample
_{A 2} O ₃ type commercially available SNGN433 shape was used.

A precision lathe was used for the cutting test, and a tool microscope was used for measuring the flank wear width (VB). The conditions of the cutting test were as follows.

Cutting speed: 400 m / min Feed rate: 0.2 mm / rev Depth of cut: 1.5 mm Length with tool: 40 mm Tailstock protrusion: 35 mm Work material: Cast iron FC20 (hardness H _B 250) Workpiece Cutting material size: φ110 × 600mm round bar

Next, the flank wear width (VB) was measured. Since the work material was scraped off with a tip holder at an inclination of 5 ° C., the tip was tilted 5 ° with respect to the tool microscope, and the tool flank was parallel. It was installed so that The cutting test was performed by dry type outer turning, and the flank wear width VB = 0.2 mm was set as a tool life judgment standard.

The test results are shown in Table 2.

[0043]

[Table 2]

As is clear from Table 2, the Si of this embodiment is
It was confirmed that the cutting tool using the C-Al ₂ O ₃ composite ceramic tool material had a tool life of about 1.7 times that of the cutting tool used for comparison. Further, the wear surface of the tool was observed after the test, but no abnormal wear, chipping, etc. were observed, and it was confirmed that the tool life of the tool of this example depends only on the pure wear of the tool.

[0045]

As described above, according to the Al ₂ O ₃ -based composite ceramic polishing material of the present invention, the matrix α-Al is used.
SiC, Si ₃ N ₄ , which has higher fire resistance than ₂ O ₃ particles,
One or more dispersion-strengthened particles of TiC, TiN, TiCN, etc. have a fine structure dispersed in α-Al ₂ O ₃ particles and have an intragranular fracture property. The particles can be SiC, Si ₃ N _4, etc.). This material is characterized in that its strength and fracture toughness value are remarkably improved as compared with conventional Al ₂ O ₃ -based materials, and that intra-particle fracture occurs at the time of fracture. When such a material is used as a cutting tool or abrasive particles, it has a high fracture toughness value, which results in a longer life due to the reduction of abnormal chipping wear (cutting tool), and a reduction in wear due to the reduction of particles that have fallen out due to intra-particle fracture ( Cutting tools, abrasive particles) and improved sharpness due to internal particle destruction (cutting tools, abrasive particles). Thus, the Al ₂ O ₃ -based composite ceramic abrasive material according to the present invention,
By using the tool material, not only various tools such as cutting tools and abrasive particles but generally the performance of wear-resistant materials is greatly improved, and it can be used as a structural material (the above claims) 1-5, 8-10).
According to claims 6 and 7, the industrial manufacturing method of the composite ceramic abrasive material is realized.

Further, since it is much less expensive than extremely expensive ultra-high-grade materials (diamond, cubic boron nitride CBN), it is very suitable for tools that are often used in large quantities.

That is, according to the present invention, a high-performance, long-life and inexpensive abrasive material and tool material are provided.

[Brief description of drawings]

FIG. 1 is a photograph showing a crystal structure of an example of an Al ₂ O ₃ -based composite ceramic polishing material and a tool material, SiC-Al.
_{It is} a microstructure of ₂ O ₃ system observed by a transmission electron microscope (TEM). SiC particles are dispersed in the Al ₂ O ₃ crystal particles that are the matrix.

FIG. 2 is a model view showing a state of wear that occurs when a tool (for example, a cutting tool) is produced using the Al ₂ O ₃ -based composite ceramic tool material of the present invention and is used. The matrix Al ₂ O ₃ particles do not undergo grain boundary destruction,
Intra-particle fracture occurs from the sub-grain boundaries within the particles, which is a feature of the material of the present invention. For this reason, the amount of falling off is reduced and sharp cutting edges are generated as compared with the usual grain boundary breakage peculiar to Al ₂ O ₃ .

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenji Oshima 3-36 Noritake Shincho, Nishi-ku, Nagoya-shi, Aichi Noritake Company Limited Limited 36 (72) Inventor Tsuguo Ito 3-chome, Noritake Shin-cho, Nishi-ku, Nagoya, Aichi No. 36 Noritake Company Limited (72) Inventor Hideyuki Tomita 1-3-1 Noritake Shinmachi, Nishi-ku, Nagoya-shi Aichi Prefecture No. 36 Noritake Company Limited (72) Inventor Misao Iwata Sanori Noritake Nishi-ku, Nagoya, Aichi Prefecture No. 1-36 Noritake Company Limited (72) Inventor Eiichi Kuda No. 1-336 Noritake Shinmachi, Nishi-ku, Nagoya-shi, Aichi Prefecture Noritake Company Limited (72) Inventor Shinichi Shinbara Kaori Hirakata, Osaka Prefecture 9-7-1142 (72) Inventor Atsushi Nakahira Suita, Osaka Prefecture Aoyama stand 1-2 C33-307 Room No.

Claims (10)

[Claims] 1. A matrix containing α-Al ₂ O ₃ as a main component in an amount of 80 vol% to 99 vol% and at least one dispersion strengthening particle in a carbide, nitride or carbonitride of Si or Ti in an amount of 1 to 20 vol.
%, And the dispersion-strengthened particles are dispersed in α-Al ₂ O ₃ particles and are characterized by being intra-particle destructible.
Al ₂ O ₃ based composite ceramic polishing material. 2. A fracture toughness value of 4.5 MPam ^1/2 or more and a hardness of 1
The Al ₂ O ₃ -based composite ceramic polishing material according to claim 1, which has a chipping resistance and wear resistance of 7 GPa or more. 3. The Al ₂ O ₃ -based composite ceramic polishing material according to claim 2, which has a hardness of 20 GPa or more. 4. A grinding wheel using the abrasive material according to claim 1. 5. An abrasive cloth paper using the abrasive material according to claim 1. 6. An α-A having an average crystal grain size of 1 μm or less.
and l ₂ O ₃ or γ-Al ₂ O ₃ powder, carbides of Si and Ti having an average grain size below 1 [mu] m, nitrides and dispersion strengthening particles 1 vol% of one or more of the carbonitride ～20Vol%
Al ₂ O ₃ -based composite ceramic abrasive material which is mixed with and sintered at 1400 to 1800 ° C. to obtain intra-particle dispersion strengthened and intra-particle destructible Al ₂ O ₃ -based composite ceramic abrasive material. Manufacturing method. 7. A granular sintered body is obtained by preforming the mixture and sintering it in a refractory powder medium.
The method for producing the Al ₂ O ₃ -based composite ceramic polishing material as described in 1. 8. An essentially 80 vol% to 99 vol% matrix containing α-Al ₂ O ₃ as a main component and 1 to 20 vol% of one or more dispersion strengthening particles in carbides, nitrides and carbonitrides of Si. The Al ₂ O ₃ -based composite ceramic tool material usable as a grinding tool, characterized in that the dispersion-strengthened particles are dispersed in α-Al ₂ O ₃ particles and have intra-particle destructive properties. 9. A fracture toughness value of 4.5 MPam ^1/2 or more and a hardness of 1
The tool material according to claim 8, which has a chipping resistance and wear resistance of 7 GPa or more. 10. The tool material according to claim 9, which has a hardness of 20 GPa or more.