JPH07291742A - Production of fine sic particle dispersed ceramics sintered compact - Google Patents

Abstract

PURPOSE:To produce a high density and high strength fine SiC particle dispersed ceramics sintered compact at low cost. CONSTITUTION:A pot and/or balls for pulverization are made essentially of SiC. Ceramics powder and the balls are filled into the pot and this pot is rotated or vibrated to wear the inner wall of the pot and/or the balls themselves while pulverizing and mixing the ceramics powder. By the wearing, >=0.3vol.% fine SiC particles of <=0.1mum average particle diameter are incorporated into the ceramics powder and the resultant powdery mixture is compacted into a desired shape and burnt in an inert atmosphere or in vacuum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a high-density and high-strength SiC fine particle-dispersed ceramics sintered body.

[0002]

2. Description of the Related Art A ceramics sintered body is made to have a high strength by suppressing the growth of crystal grains of a ceramic matrix or improving toughness by dispersing hard ceramics particles in the sintered body. It is known to be achieved.

It is known that the smaller the particle size of dispersed particles and the larger the volume fraction, the greater the effect of suppressing the grain growth of the matrix crystal grains.

In particular, when SiC particles are used as hard dispersed particles, it is easy to stably leave them in the sintered body even in the sintering process because of the heat resistance, oxidation resistance, chemical stability and the like of SiC. It is considered that the effect of suppressing the growth of the parent phase crystal grains is great.

However, in order to disperse the SiC particles in the ceramics, it is common to use a method in which the SiC particles are externally added and mixed at the same time as the ceramic powders are mixed and pulverized, as disclosed in JP-A-3-205363. Si
As for C particles, 0.3 is usually obtained by the Acheson method or the like.
It is as large as -20 μm.

It is possible to obtain fine particles of 0.2 μm or less by a vapor phase method or the like, but the finer the finer and the more difficult it is to handle, and the fine SiC particles are uniformly dispersed in the sintered body. Was difficult.

On the other hand, when the ceramic powder is mixed, Si,
There is also known a method of obtaining fine SiC particles during a sintering process by using an organometallic polymer containing C or the like, but the organometallic polymer is expensive, and a large amount of decomposition gas is generated during the sintering. Therefore, it was difficult to obtain a dense sintered body.

[0008]

As described above, according to the prior art, fine S having a remarkable suppressing effect on the growth of the parent phase crystal grains.
There are various problems in efficiently and uniformly dispersing iC particles in a ceramic sintered body by an inexpensive method.

The present invention has been made to solve the above problems. An object of the present invention is to provide an inexpensive method for producing a high-density and high-strength SiC fine particle-dispersed ceramics sintered body.

[0010]

The method for producing a sintered body of fine SiC particles according to the present invention uses a pot and / or a crushing ball which is substantially made of SiC, and the ceramic powder and the crushing powder are used in the pot. The ceramic powder is crushed and mixed by being filled with balls and being rotated or vibrated, and the inner wall of the pot and / or the crushing ball itself is abraded to obtain SiC fine particles having an average particle diameter of 0.1 μm or less in the ceramic powder. It is characterized in that 0.3% by volume or more is mixed and the obtained mixed powder is molded into a desired shape and fired in an inert atmosphere or in a vacuum.

According to the present invention, a crushed material of a pot or a crushing ball, which is inevitably mixed in the ceramic powder when the ceramic powder is mixed and crushed, is made of a predetermined material of Si.
Using a mixing pot made of C and a crushing ball, the mixture is generated by mixing so as to obtain a desired particle size and mixing amount, and is mixed into the ceramic powder, and the mixed SiC particles as crushed particles are particles. Low cost, high density and high strength SiC used as dispersed hard particles of dispersed ceramics
A fine particle-dispersed ceramics sintered body is obtained.

As a method for mixing and pulverizing the ceramic powder of the present invention, a rotary pot mill, a planetary ball mill, an attritor, a vibrating ball mill or the like can be used, and alumina, zirconia, mullite, silicon nitride, sialon or the like can be used. It can be used for producing a SiC particle-dispersed ceramics sintered body having fine ceramics as a mother phase.

As the pot to be used, a pot substantially composed of a main body of a SiC sintered body and a lid is preferable, and in the case of a large pot mill, a liner to which SiC tiles are stuck may be used as a liner.

Further, as the grinding balls, substantially Si is used.
A C sintered body is preferable, and a ball diameter used is preferably 10 mm or less, and more preferably 3 mm or less from the viewpoint of pulverization efficiency described later.

It is preferable to use the SiC sintered body for both the pot and the crushing ball in order to efficiently mix the desired SiC fine powder into the ceramic powder, but only one of them may be used.

When only one of them is used, the other one of the pair of crushing balls or pot is preferably a material which is basically decomposed and volatilized during the sintering process of ceramics, such as polyimide, polyamide, nylon and Teflon (registered). Resin materials such as trademark) and acrylic resin are desirable.

When these resin-based materials are used as crushing balls, it is possible to efficiently use SiC from the pot by using a ball having a weight such as an iron ball embedded in the center.
Fine particles can be obtained.

Si used in pots and balls for grinding
As the C sintered body, a dense one having a relative density of 97% or more is preferable, and the material thereof is substantially composed of SiC, such as B, C, Al, O, N as a sintering aid. The compound may be contained in an amount of 10% by weight or less.

If it exceeds 10% by weight, the characteristics of SiC as hard particles in the particle-dispersed ceramics may be impaired.

The crystal structure of SiC is β-type, α-type,
It does not matter whether they are mixed or not.

When a pot made of a SiC sintered body having a relative density lower than 97% and a crushing ball are used, large crushed particles having an average particle size of 10 μm or more may be mixed into the ceramic powder being mixed. It is difficult to obtain a high-strength sintered body, which is the object of the invention.

The SiC fine particles to be mixed into the ceramic powder from the pot and the ball have a grain size of 0.5 to suppress the grain growth of the ceramic forming the mother phase of the sintered body and obtain the high strength which is the object of the present invention. It is preferable that the average particle diameter is 1 μm or less and the volume fraction is 0.3% or more.

Average particle size larger than 0.1 μm, 0.3
When the volume fraction is less than%, no significant effect is seen on the strength characteristics.

The particle size of the crushed powder and the amount of the crushed powder obtained by abrasion include the crushing ball, the ceramic powder, and the inner wall of the pot as the crushing ball falls and moves due to rotation or vibration of the pot in the pot. The larger the collision energy of the ceramic powder, the crushing balls, and the collision between the crushing ball and the inner wall of the pot, the larger the crushed powder obtained and the larger the amount thereof.

In the present invention, SiC having a desired small average particle size of 0.1 μm or less and a large volume fraction of 0.3% or more.
In order to obtain fine particles, it is necessary to reduce the above-mentioned collision energy and increase the number of collisions. When using a large pot, reduce the number of revolutions of the pot or reduce vibration to the pot, and It is preferable to mix and grind for a long time by using a large amount of grinding balls having a small particle size.

More specifically, a weight (less than a value obtained by dividing the pot volume (liter) by 3 in a rotary pot mill using a cylindrical pot made of SiC (or resin) whose inner wall has a density of 97% or more ( (kg) ceramic powder is mixed with the reciprocal of the square root of the inner diameter (meter) of the cylinder, which is 2
Rotating the pot at a rotational speed (rpm) smaller than the value obtained by multiplying by 0, a crushing ball to be used has a density of 9
7% or more of SiC (or resin, either pot or ball is SiC) and smaller than the value obtained by dividing the cylindrical inner diameter of the pot by 20, or at most 10 m
With a diameter of m, the amount (kg) larger than the value obtained by dividing the pot volume (liter) by 2.5 is filled in the pot,
It is desirable to pulverize and mix using a solvent such as purified water, ethanol, acetone, and hexane for 24 hours or more.

Depending on the physical properties and properties of the ceramic powder to be mixed and pulverized, by combining these conditions, it is possible to easily mix the SiC fine powder having the desired average particle diameter and volume fraction of the present invention into the ceramic powder to make it uniform. It can be dispersed.

When the number of rotations of the pot and the diameter of the ball are set to the above-mentioned conditions or more and / or the SiC density is set to be less than the above-mentioned conditions, SiC fine powder larger than a desired particle size tends to be obtained, and the ceramic powder filling When the amount and the ball diameter are more than the above conditions and / or the amount of the balls is less than the above conditions, it is difficult to mix the desired volume fraction into the ceramic powder within 24 hours, and the pulverization and mixing for a longer time is performed. Will be required.

As a method for molding the obtained mixed powder into a desired shape, a known method can be used, and a press molding method, a casting molding method, an injection molding method or the like can be used.

As the sintering method, any of an atmospheric pressure sintering method, a gas pressure sintering method, a hot isostatic pressing sintering method, and a hot pressing method can be used.

The atmosphere during the sintering of the present invention is preferably an inert atmosphere such as argon gas or nitrogen gas, or a vacuum.

The reason for this is to prevent the SiC fine particles mixed in the ceramic powder during pulverization and mixing from suppressing the reaction with the atmospheric gas and disappearing.

[0033]

According to the present invention, it is possible to efficiently mix the SiC fine particles during the mixing and pulverization of the ceramic powder, and as shown in Examples described later, when the SiC powder is externally added, it is not added. In comparison with the above case, fine SiC particles having an average particle size of 0.1 μm or less mixed from the pot and / or the ball made of the SiC sintered body according to the present invention are uniformly dispersed in an amount of 0.3 vol% or more. The obtained sintered body has high strength.

Next, examples of the present invention will be described together with comparative examples.

[0035]

【Example】

[0036]

Example 1 Alumina (Al ₂ O ₃ ) powder (average particle size of 0.
6 μm) 1 kg, a β-SiC pot (sintering density 98%, pot inner diameter 15 cm) having a capacity of 5 liters prepared with 0.5 wt% B ₄ C as a sintering aid, β having a diameter of 3 mm
-Using a SiC ball (sintered density 98%) 2 kg, or a nylon pot of the same capacity, and a nylon ball 2 mm containing iron balls with a diameter of 10 mm, and using purified water as a solvent, a rotary pot mill with a rotation speed of 50 rpm. First using
Kneading was performed under the conditions shown in the table.

Then, the obtained mixed powder was dried and molded, and then sintered in a vacuum at 1500 ° C. for 1 hour.

The density and room temperature strength of each sintered body obtained according to the present invention are shown in Table 1 together with the average particle diameter and volume fraction of dispersed SiC fine particles.

The density is the Archimedes method, and the strength is JIS.
-Measured by 4-point bending according to R1601. SiC
The average particle diameter and the volume fraction of the fine particles were measured by a 1-line cutting method from a transmission electron micrograph.

As shown in Table 1, in the examples of the present invention, the desired SiC fine particles of the present invention were contained in the sintered body, and the strength was as high as 710 MPa or more as compared with the comparative examples. It was confirmed that it was obtained.

[0041]

Example 2 Silicon nitride (Si ₃ N ₄ ) powder (average particle size of 0.
5 μm) 90 g, yttrium oxide (Y ₂ O ₃ ) powder (average particle size 1 μm) 5 g, and alumina powder (average particle size 0.
5 μm) 5 g of AlN of 2 wt% and B ₄ C of 0.5 wt% were used as a sintering aid to prepare a 0.5-liter capacity α
-SiC pot (sintered density 99%, inner diameter 10 cm),
3mm diameter α-SiC balls (sintered density 99%) 2
50 g, or a Teflon pot of the same capacity, 250 g of Teflon balls containing iron balls and having a diameter of 10 mm were used, and kneaded under the conditions shown in Table 2 using ethanol as a solvent and a planetary ball mill at a rotation speed of 60 rpm. .

Then, the obtained mixed powder was dried and molded, and then sintered under nitrogen atmosphere at atmospheric pressure at 1750 ° C. for 4 hours.

The density and room temperature strength of each sintered body obtained according to the present invention are shown in Table 2 together with the average particle diameter and volume fraction of dispersed SiC fine particles. The density, strength, average particle size of SiC fine particles, and volume fraction were measured in the same manner as in Example 1.

As shown in Table 2, in the same manner as in Example 1, according to the example of the present invention, the desired SiC fine particles of the present invention were contained in the sintered body, which was 1120 M as compared with the comparative example.
It was confirmed that a high strength of at least Pa was obtained.

[0045]

[Table 1]

[0046]

[Table 2]

[0047]

According to the present invention, as described above, a SiC fine particle-dispersed ceramics sintered body having high strength and excellent reliability can be manufactured efficiently at low cost, and its industrial utility is extremely large.

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[Procedure amendment]

[Submission date] June 7, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0028

[Correction method] Change

[Correction content]

[0028] The pot rotational speed, than the above-mentioned conditions the ball diameter
When a case has been increased and / or SiC density was less than the above conditions are tend to large SiC fine powder obtained from the desired particle size, when the ceramic powder loading, the ball diameter is greater than the above conditions and / Alternatively, when the amount of balls is less than the above conditions, it is difficult to mix the desired volume fraction into the ceramic powder within 24 hours, and it is necessary to carry out pulverization and mixing for a longer time.

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Claims (1)

[Claims] 1. A pot and / or a ball for crushing, which is substantially made of SiC, is filled with ceramic powder and the ball for crushing, and the ceramic powder is crushed and mixed by applying rotation or vibration. While the inner wall of the pot and / or the grinding balls themselves are abraded, Si having an average particle diameter of 0.1 μm or less is contained in the ceramic powder.
A method for producing a SiC fine particle-dispersed ceramics sintered body, characterized in that 0.3% by volume or more of C fine particles are mixed, the obtained mixed powder is shaped into a desired shape, and is fired in an inert atmosphere or in a vacuum. .