JPH01188473A - Silicon carbide-based sintered body - Google Patents

Abstract

PURPOSE:To obtain the subject sintered body having high strength and reduced electric specific resistance and easily undergoing electric spark machining by blending SiC powder with specified amts. of TiB2 powder and Al2O3 powder and sintering the blend in an inert gaseous atmosphere. CONSTITUTION:25-60 pts.wt. SiC powder is blended with 30-70 pts.wt. TiB2 powder and 3-15 pts.wt. Al2O3 powder or a precursor giving 3-15 pts.wt. Al2O3, e.g., aluminum alkoxide, and <=4 pts.wt. C, e.g., phenol resin convertible into carbide giving <=4 pts.wt. C is further added to the blend as required. The blend is then sintered at 1,700-2,000 deg.C in an inert gaseous atmosphere to obtain the title sintered body having >=500 MPa bending strength and <=10<-2>OMEGAcm electric specific resistance.

Description

Detailed Description of the Invention (1) Purpose of the Invention [Field of Industrial Application] The present invention relates to a silicon carbide sintered body, and particularly relates to a silicon carbide sintered body that has low electrical resistivity to ensure conductivity and is suitable for electric discharge machining. The present invention relates to a silicon carbide sintered body that is easy to use and also has mechanical strength so that it can be used as a structural material.

[Prior Art] Conventionally, this type of silicon carbide sintered body has been proposed to be made by adding titanium boride TiB2 powder to silicon carbide SiC powder and sintering it. Because it had heat resistance properties, it was used as a material for mechanical parts (Japanese Patent Application Laid-Open No. 57-27975
reference).

[Problems to be solved] However, in conventional silicon carbide sintered bodies, titanium boride TiB2 powder was added to silicon carbide SiC powder, so (i) as the amount of titanium boride TiB2 increased, It has the disadvantage that the amount of silicon carbide (SiC) blended is relatively reduced, which in turn deteriorates the sinterability, and even if a sintered body is produced by pressure sintering, its mechanical strength is significantly reduced. Therefore, (ii) the shape of the sintered body cannot be complicated, and (iii) the range of use as a structural material is greatly limited.In addition, (iv) aluminum oxide AIto3 powder is added to the formulation. It was thought that this would impede conductivity (Japanese Patent Laid-Open No.
7-196770).

Therefore, the present invention aims to eliminate these drawbacks, reduce specific resistance, ensure conductivity, and ensure mechanical strength, thereby making silicon carbide easy to perform electric discharge machining and also usable as a structural material. The purpose is to provide a quality sintered body.

(2) Structure of the invention [Means for solving problems] To that end, the solution provided by the present invention is.

"To 25 to 90 parts by weight of silicon carbide powder, 5 to 70 parts by weight of titanium boride powder and 3 to 15 parts by weight of aluminum oxide powder are blended, and the "silicon carbide sintered body" characterized by being sintered at a temperature of 2000°C.

[Function] The silicon carbide sintered body according to the present invention contains silicon carbide powder 25
~90 parts by weight, 5 to 70 parts by weight of titanium boride powder, and 3 to 15 parts by weight of aluminum oxide powder
Only part by weight is blended, and 17% in an inert gas atmosphere.
Since it is sintered at a temperature of 00 to 2000℃, (
i) It acts to reduce electrical resistivity and ensure conductivity, which in turn makes electrical discharge machining easier, and (ir) it acts to ensure mechanical strength, such as bending strength. There is.

[Example] Next, examples of the present invention will be described.

First, the details of one embodiment of the silicon carbide sintered body according to the present invention will be explained.

The silicon carbide sintered body according to the present invention contains 25 to 90 parts by weight of silicon carbide SiC powder and titanium boride TiB.

After 5 to 70 parts by weight of powder is blended and 3 to 15 parts by weight of aluminum oxide Al2O powder is blended, the product is sintered at a temperature of 1700 to 2000°C in an inert gas atmosphere. ing.

Here, the blending amount of titanium boride TiB2 powder is 5 to 70
It is preferable that it is in parts by weight, that is, this amount is
If it is less than 5 parts by weight, the electrical conductivity of the resulting silicon carbide sintered body will be extremely impaired, and if it exceeds 70 parts by weight, the sinterability will deteriorate and its mechanical strength will decrease. .

Also aluminum oxide A1. O. What is the amount of powder mixed?

It is preferable that the amount is from 3 to 15 parts by weight; in other words, if this amount is less than 3 parts by weight, the sinterability will deteriorate and the mechanical strength of the resulting silicon carbide sintered body will decrease; This is because if the thickness exceeds 100 mm, the mechanical strength and conductivity will be impaired. Aluminum oxide Alz
Oz powder does not necessarily have A1.0. It is not necessary to add it as a powder, but it can be added in the form of aluminum alkoxide, organic acid salt, or inorganic acid salt and subjected to appropriate treatment before sintering.
．． 0. It may be converted to

In addition, 4 parts by weight or less of carbon may be added to improve sinterability and mechanical strength. The reason why the amount of carbon is limited to 4 parts by weight or less is that if it exceeds 4 parts by weight, the mechanical strength of the silicon carbide sintered body will decrease.

Furthermore, in order to deepen the understanding of one embodiment of the silicon carbide sintered body according to the present invention described above, a specific explanation will be given using numerical values and the like.

87 g of silicon carbide SiC powder with an average particle size of 0.54 m was mixed with titanium boride Ti8. After adding 5g of powder and 8g of aluminum oxide 81□03 powder with an average particle size of 0.5#Lm, 11g of acetone was added as a solvent.
201 was added and mixed with stirring for 100 hours using a plastic bot mill or polypot and monoball.

Next, the stirred mixture was dried to remove the solvent and then granulated to obtain a granulated mixture.

The granulated mixture was molded using a mold press and a rubber press to form a molded body of 5 mm x 5 mm x 60 mm. The molded body was placed in a graphite container and sintered at a temperature of 1900° C. in an argon atmosphere to form a silicon carbide sintered body.

The silicon carbide sintered body was measured for relative density, electrical resistivity, and bending strength (three-point bending strength at room temperature), and the measurement results are shown in Table 1.

Example 1 was repeated except that the amounts of engineered silicon carbide SiC powder and titanium boride Tilt powder were 82 g and 10 g, respectively.

The silicon carbide sintered body was measured for relative density, electrical resistivity, and bending strength (three-point bending strength at room temperature), and the measurement results are shown in Table 1.

The blending amounts of silicon carbide SiC powder, titanium boride TiB2 powder, and aluminum oxide Al*03 powder are 7 each.
Example 1 except that 0g, 25g and 5g
was repeated.

The silicon carbide sintered body was measured for relative density, electrical resistivity, and bending strength (three-point bending strength at room temperature), and the measurement results are shown in Table 1.

Construction
Example 1 was repeated except that 5g, 40gj5 and 5g.

The silicon carbide sintered body was measured for relative density, electrical resistivity, and bending strength (three-point bending strength at room temperature), and the measurement results are shown in Table 1.

The blending amount of silicon carbide SiC powder, titanium boride TiBa powder and aluminum oxide AIJ: + powder is S
ag, 40 g and 5 g, and the sintering temperature is 185
Example 1 was repeated except that the temperature was 0°C.

The silicon carbide sintered body was measured for relative density, electrical resistivity, and bending strength (three-point bending strength at room temperature), and the measurement results are shown in Table 1.

-Cυ11 monosilicon carbide SiC powder, titanium boride Tie powder, and aluminum oxide Al20i powder each have a compounding amount of 4
Example 1 except that 5g, 50g and 5g
or repeated.

The silicon carbide sintered body was measured for relative density, electrical resistivity, and bending strength (three-point bending strength at room temperature), and the measurement results are shown in Table 1.

(Example 7) Silicon carbide SiC powder, titanium boride Tie, powder and aluminum oxide A1.0. The amount of powder mixed is 3 each.
Example 1 except that 5g, 60g and 5g
or repeated.

The silicon carbide sintered body was measured for relative density, electrical resistivity, and bending strength (three-point bending strength at room temperature), and the measurement results are shown in Table 1.

(Example day) Silicon carbide SiC powder, titanium boride Ti8□ powder, and aluminum oxide A1.0. The blending amount of powder is 2 each.
Example 1 except that 5g, 70g and 5g
was repeated.

The silicon carbide sintered body was measured for relative density, electrical resistivity, and bending strength (three-point bending strength at room temperature), and the measurement results are shown in Table 1.

Kuri Sesodanjo 51 g of silicon carbide SiC powder with an average particle size of 0.5 pm.

Titanium boride τiB2 powder 4 (
Ig and aluminum oxide A1.0 with an average particle size of 0.5 gm
．． After 5 g of powder was added, 120 cm of an acetone solution containing 8 g of phenol resin with a degree of carbonization of 50% by weight was added as a solvent, and the mixture was stirred and mixed for 100 hours using a plastic bot mill, that is, a polypot and a monoball. Ta.

Next, the stirred mixture was dried to remove the solvent and then granulated to obtain a granulated mixture.

The granulated mixture was molded using a mold press and a rubber press to form a molded body of 5 cm x 5 cm x 60 cm. The molded body was placed in a graphite container and sintered at a temperature of 2000° C. in an argon atmosphere to form a silicon carbide sintered body.

The silicon carbide sintered body was measured for relative density, electrical resistivity, and bending strength (three-point bending strength at room temperature), and the measurement results are shown in Table 1.

(Comparative Example 1) 90 g of silicon carbide SiC powder with an average particle size of 057 zm was mixed with 2 g of titanium boride TiB2 powder with an average particle size of 1.5 μm and 8 g of aluminum oxide A12 (1+ powder) with an average particle size of 0.5 gm. , and acetone 12 as a solvent
(1 ml was added and stirred and mixed for 100 hours using a plastic pot mill or monoball.

Next, the stirred mixture was dried to remove the solvent and then granulated to obtain a granulated mixture.

The granulated mixture was molded using a die press and a rubber press to form a 5-carbon, 5-weight, 60-inch molded product. The molded body was placed in a graphite container and sintered under an argon atmosphere at a temperature of 1°C to form a silicon carbide sintered body.

The silicon carbide sintered body was measured for relative density, electrical resistivity, and bending strength (three-point bending strength at room temperature), and the measurement results are shown in Table 1.

Example 1 was repeated except that the amounts of the polishing finish, silicon carbide SiC powder, and titanium boride TiB2 powder were 80-84 g and 16-20 g, respectively.

The silicon carbide sintered body was measured for relative density, electrical resistivity, and bending strength (three-point bending strength at room temperature), and the measurement results are shown in Table 1.

Example 1 was repeated, except that the amounts of L. acetate, silicon carbide SiC powder, and titanium boride TiBt powder were 60 g and 40 g, respectively.

The silicon carbide sintered body was measured for relative density, electrical resistivity, and bending strength (three-point bending strength at room temperature), and the measurement results are shown in Table 1.

As is clear from Table 1, according to the present invention, the electrical resistivity of the silicon carbide sintered body can be reduced to 102 Ωc or less, compared to the comparative example. Further, according to the present invention, even under pressureless sintering, it is possible to achieve an electrical resistivity of less than lo-2 Ωam and a theoretical relative density of more than 95%, and as a result, the mechanical strength, such as bending strength, is greater than 500 MPa, which is greater than that of the comparative example. can. Therefore, according to the present invention, electrical discharge machining of a silicon carbide sintered body can be facilitated, even a deep shape can be machined in a short time, and high strength and toughness can be ensured.

In the above-mentioned example, the particle size of the silicon carbide SiC powder was 0.5. Bm, but is not limited to this. However, in consideration of the mechanical strength of the silicon carbide sintered body, it is particularly preferable that the particle size of the silicon carbide SiC powder is 1pm or less.

(3) Effects of the invention As is clear from the above, the silicon carbide sintered body according to the present invention contains 5 to 70 parts by weight of titanium boride powder to 25 to 90 parts by weight of silicon carbide powder, It also contains 3 to 15 parts by weight of aluminum oxide powder and is sintered at a temperature of 1,700 to 2,000°C in an inert gas atmosphere to (a) reduce the electrical resistivity to 102 ΩC or less; In addition, (b) it has the effect of facilitating electrical discharge machining, and (C) it has an electrical resistivity of 1O-2ΩC1 or less even when sintered under pressure, and a theoretical value of 95% or more. It is possible to achieve a relative density, and as a result, the mechanical strength, for example, the bending strength, can be increased to 500 MPa or more, and it also has the effect of providing high strength and high toughness.

Patent Applicant Toshiba Ceramics Co., Ltd. Agent Patent Attorney Takao Kudo Procedural Amendment (Mutsu) April 14, 1988 Commissioner of the Patent Office Kunio Ogawa
order.

1. Indication of the case 1986 Patent Application No. 13376 2. Name of the invention Ceramic sintered body 3. Person making the amendment Relationship to the case Patent applicant address 26-2 Nishi-Shinjuku-chome, Shinjuku-ku, Tokyo Name: Toshiba Ceramics Corporation Representative Atsushi Hiyoshi - 4, Agent 160 Phone: 03-3
56-3016---25, Full text of the specification to be amended 6, Contents of the amendment as shown in the attached sheet Amended specification 1, Title of the invention Ceramic sintered body 2, Claims (1) Silicon carbide powder 25~ 60 parts by weight, 30 to 70 parts by weight of titanium boride powder and 3 to 15 parts by weight of aluminum oxide powder are mixed, and the mixture is sintered at a temperature of 1700 to 2000°C in an inert gas atmosphere. A ceramic sintered body characterized by being fused.

(2) The ceramic sintered body according to claim (1), wherein 4 parts by weight or less of carbon is added.

(3) The bending strength is 500 MPa or more at room temperature.
2) Ceramic sintered body described in section 2).

(4) The ceramic sintered body according to any one of claims (1) to (3), wherein the ceramic sintered body has an electrical resistivity of 10 -2 ΩC or less at room temperature.

3. Detailed Description of the Invention (1) Purpose of the Invention [Field of Industrial Application] The present invention relates to a ceramic sintered body, and in particular, the present invention relates to a ceramic sintered body that has a lower electrical resistivity, thereby ensuring conductivity and facilitating electrical discharge machining. The present invention relates to a ceramic sintered body that can also be used as a structural material by ensuring mechanical strength.

[Prior Art] Conventionally, this type of ceramic sintered body has been proposed in which titanium boride Ti1t powder is added to silicon carbide SiC powder and sintered. Because of its properties, it was used as a material for mechanical parts (Japanese Patent Application Laid-Open No. 57-27975
and Japanese Unexamined Patent Publication No. 62-3072, etc.).

[Problems to be solved] However, in conventional ceramic sintered bodies, titanium boride TiB* powder was added to silicon carbide SiC powder, so as the amount of (i) titanium boride Tie increases, There is a drawback that the blending amount of silicon carbide (SiC) is relatively reduced, which in turn deteriorates sinterability, and even if sintered by pressure sintering, its mechanical strength is significantly reduced (Unexamined Japanese Patent Publication No. 62-3072), and therefore (i
It has the disadvantages of i) not being able to complicate its shape, and (iii) greatly limiting its range of use as a structural material.In addition, (iv) addition of aluminum oxide AIJ:+ powder inhibits conductivity. (Refer to Japanese Unexamined Patent Publication No. 57-196770).

Therefore, the present invention aims to eliminate these drawbacks and create a ceramic sintered material that can be easily processed by electric discharge machining and can also be used as a structural material by lowering the electrical resistivity to ensure conductivity and mechanical strength. It is intended to provide a structure.

(2) Structure of the invention [Means for solving the problem] To this end, the solution provided by the present invention is as follows: ``30 to 70 parts by weight of titanium boride powder is blended with 25 to 60 parts by weight of silicon carbide powder. , and contains 3 to 15 parts by weight of aluminum oxide powder, and is sintered at a temperature of 1700 to 2000° C. in an inert gas atmosphere.

[Function] The ceramic sintered body according to the present invention contains silicon carbide powder 2
5 to 60 parts by weight, titanium boride powder is 30 to 70 parts by weight.
Aluminum oxide powder or aluminum oxide powder is added in only 3 parts by weight.
It contains only 15 parts by weight and is sintered at a temperature of 1,700 to 2,000°C in an inert gas atmosphere, so it has the effect of reducing electrical resistivity and ensuring conductivity, which in turn facilitates electrical discharge machining. (ii) It serves to ensure mechanical strength, such as bending strength.

[Example] Next, the present invention will be explained by giving examples.

First, the details of one embodiment of the ceramic sintered body according to the present invention will be explained.

The ceramic sintered body according to the present invention is made of silicon carbide SiC
After 60 parts by weight of powder 25, 30 to 70 parts by weight of titanium boride Tie powder and 3 to 15 parts by weight of aluminum oxide Al2O:+ powder were mixed, and then the mixture was heated under an inert gas atmosphere. It is created by sintering at a temperature of 1700 to 2000°C.

Here, the blending amount of titanium boride Ti8□ powder is 30 to 7
It is preferable that the amount is 0 parts by weight, that is, if this amount is less than (i) 30 parts by weight, the conductivity of the resulting ceramic sintered body will be extremely impaired, resulting in difficulty in electrical discharge machining. (ii) If the amount exceeds 70 parts by weight, the sinterability deteriorates and the mechanical strength decreases.

In addition, the blending amount of aluminum oxide A1.03 powder is 3~
It is preferable that the amount is 15 parts by weight, that is, if this amount is less than (i) 3 parts by weight, the sinterability will deteriorate and the mechanical strength of the resulting ceramic sintered body will decrease. ii) If it exceeds 15 parts by weight, its mechanical strength and conductivity will be impaired. Aluminum oxide Al2O3 powder does not necessarily have to be added as A120i powder, but may be added in the form of aluminum alkoxide, organic acid salt, or inorganic acid salt and converted into AIzOz by performing appropriate treatment before sintering.

In addition, 4 parts by weight or less of carbon may be added to improve sinterability and mechanical strength. The basis for limiting the amount of carbon added to 4 parts by weight or less is that if it exceeds 4 parts by weight, the mechanical strength of the ceramic sintered body will decrease.

Further, in order to deepen the understanding of one embodiment of the ceramic sintered body according to the present invention described above, a specific explanation will be given using numerical values and the like.

Silicon carbide SiC powder with an average particle size of 0.5 JLm [iog is titanium boride TiBa powder 35 with an average particle size of 1.5 gm]
After adding 12 g of acetone, 12 g of acetone was added as a solvent.
was added and mixed with stirring for 100 hours using an alumina pot mill, that is, an alumina pot and bowl.

Next, the stirred mixture was dried to remove the solvent and then granulated to obtain a granulated mixture. Since the granulated mixture was made of alumina, aluminum oxide A1. O,
was contained in an amount of 5% by weight (here, 5g). The average particle size of the aluminum oxide Al2O mixed into the granulation mixture was 10 m.

The granulated mixture was molded using a mold press and a rubber press to form a molded body of 5 mm x Sml x 60 mm. The molded body was placed in a graphite container and sintered at a temperature of 1900° C. in an argon atmosphere to form a ceramic sintered body.

Ceramic sintered bodies have relative density, electrical resistivity, and bending strength (3-point bending strength at room temperature)
were measured, and the measurement results are shown in Table 1.

(Example 2) Silicon carbide SiC powder, titanium boride TiB2 powder, and aluminum oxide A1□0. The amount of powder mixed is 5 each.
Example 1 except that 5g, 40g and 5g
was repeated.

Ceramic sintered bodies have relative density, electrical resistivity, and bending strength (3-point bending strength at room temperature)
were measured, and the measurement results are shown in Table 1. Since the electrical resistivity was 4 x 10-'Ωcm, the wire electrical discharge machining speed of the ceramic sintered body was 12
It was large and economically sufficient at 0 to 150 sulfur/min.

(Example 3) The blending amounts of silicon carbide SiC powder, titanium boride TiBa powder, and aluminum oxide A1□03 powder were each 5
5g, 40g and 5g, and the sintering temperature is 185
Example 1 was repeated except that the temperature was 0°C.

Ceramic sintered bodies have relative density, electrical resistivity, and bending strength (3-point bending strength at room temperature)
were measured, and the measurement results are shown in Table 1.

4. Silicon carbide SiC powder, titanium boride TiB2 powder and aluminum oxide A1. O, powder blending amount is 4 each
Example 1 except that 5g, 50g and 5g
was repeated.

Ceramic sintered bodies have relative density, electrical resistivity, and bending strength (3-point bending strength at room temperature)
were measured, and the measurement results are shown in Table 1.

Example 1 was repeated except that the amounts of silicon carbide SiC powder, titanium boride Tie powder, and aluminum oxide Al2O:l powder were 35 g, 50 g, and 5 g, respectively.

Ceramic sintered bodies have relative density, electrical resistivity, and bending strength (3-point bending strength at room temperature)
were measured, and the measurement results are shown in Table 1.

Example 1 was repeated except that the amounts of silicon carbide SiC powder, titanium boride TiB powder, and aluminum oxide AllO:I powder were 25 g, 70 g, and 5 g, respectively.

Ceramic sintered bodies have relative density, electrical resistivity, and bending strength (3-point bending strength at room temperature)
The results are shown in Table 1.

51 g of silicon carbide SiC powder with an average particle diameter of 0.57 zm was
Titanium boride TiB with an average particle size of 1.5 JLm, powder 40
g was added, and then an acetone solution 1201 containing 8 g of phenol resin with a carbonization degree of 50% by weight was added as a solvent.
was added and mixed with stirring for 100 hours using an alumina pot mill, that is, an alumina pot and bowl.

Next, the stirred mixture was dried to remove the solvent and then granulated to obtain a granulated mixture. Because the bot mill was made of alumina, the granulated mixture contained aluminum oxide A1.0.0 mixed from the pot wall and ball.
It contained only 5% by weight (5g in this case). Aluminum oxide A1 mixed into the granulation mixture. The average particle size of O, is 1. It was OILm.

The granulated mixture was molded using a mold press and a rubber press to form a 5 m x 5 m x 60 m compact. The molded body was placed in a graphite container and sintered at a temperature of 2000'C in an argon atmosphere to form a ceramic sintered body.

Ceramic sintered bodies have relative density, electrical resistivity, and bending strength (3-point bending strength at room temperature)
were measured, and the measurement results are shown in Table 1.

(Comparative Example 1) 90 g of silicon carbide SiC powder with an average particle size of 0.5 ILm was
2g of titanium boride Ti1t powder with an average particle size of 1.5JLm
and aluminum oxide A1.0 with an average particle size of 0.5 pLm!
After adding 3 g of powder, acetone 1201 was further added as a solvent, and the mixture was stirred and mixed for 100 hours using an alumina acid pot mill, that is, an alumina acid pot and bowl.

Next, the stirred mixture was dried to remove the solvent and then granulated to obtain a granulated mixture. The granulated mixture contains aluminum oxide A1.03 mixed in from the pot wall and ball because the bot mill was heated with alumina acid.
is included in the aluminum oxide A1. Only 8% by weight (here, 8 g) of O, was included. The average particle size of the aluminum oxide A1□0:I mixed into the granulated mixture from the bot mill was 1.0 m.

The granulated mixture was molded using a Kinsei press and a rubber press to form a molded product measuring 5 cm x 5 ms x 60 m. The molded body was placed in a graphite container and sintered at a temperature of 1900° C. in an argon atmosphere to form a ceramic sintered body.

Ceramic sintered bodies have relative density, electrical resistivity, and bending strength (3-point bending strength at room temperature)
were measured, and the measurement results are shown in Table 1. Since the electrical specific resistance was 1.0 x 103 Ωcm,
Wire electrical discharge machining of ceramic sintered bodies has been virtually impossible.

Comparative Example 2 Comparative Example 1 was repeated except that the amounts of silicon carbide SiC powder and titanium boride Tin2 powder were 87 g and 5 g, respectively.

Ceramic sintered bodies have relative density, electrical resistivity, and bending strength (3-point bending strength at room temperature)
were measured, and the measurement results are shown in Table 1.

Comparative Example 3 Comparative Example 1 was repeated except that the amounts of silicon carbide SiC powder and titanium boride Tie2 powder were 82 g and 10 g, respectively.

Ceramic sintered bodies have relative density, electrical resistivity, and bending strength (3-point bending strength at room temperature)
were measured, and the measurement results are shown in Table 1. Since the electrical specific resistance was 5.0 x 10'Ωcm,
Wire electrical discharge machining speed of ceramic sintered body is 0.00
It was small, 21 minutes long for 3 dragons, and economically insufficient.

(Comparative Example 4) 70 g of silicon carbide SiC powder with an average particle size of 0.51 Lm was
Titanium boride Tin, powder 25g with an average particle size of 1.5pm
After that, 120 liters of acetone was further added as a solvent, and the mixture was stirred and mixed for 100 hours using an alumina acid bot mill, that is, an alumina acid pot and bowl.

Next, the stirred mixture was dried to remove the solvent and then granulated to obtain a granulated mixture. The granulated mixture contained 5% by weight (here 5 g) of aluminum oxide AIJ+ mixed in from the pot wall and ball since the bot mill was alumina acid. The average particle size of the aluminum oxide AIJs mixed into the granulated mixture from the bot mill was 1.0 m.

The granulated mixture was molded using a mold press and a rubber press to form a 5 inch x 5 inch x 60 inch molded body. The molded body was placed in a graphite container and sintered at a temperature of 1900° C. in an argon atmosphere to form a ceramic sintered body.

Ceramic sintered bodies have relative density, electrical resistivity, and bending strength (3-point bending strength at room temperature)
were measured, and the measurement results are shown in Table 1. Since the electrical specific resistance was 5.0 x 10'Ωcm,
Wire electrical discharge machining speed of ceramic sintered body is 0.00
The speed was as small as 3 mm''/min and was economically insufficient.

(Comparative Example 5) 80 to 84 g of silicon carbide SiC powder with an average particle size of 0.5 gm
is titanium boride Tie2 powder 1 with an average particle size of 1.5 gm.
After 6 to 20 grams were added, 120 liters of acetone was added as a solvent, and the mixture was stirred and mixed for 100 hours using a plastic bot mill or pot and monoball.

Next, the stirred mixture was dried to remove the solvent and then granulated to obtain a granulated mixture.

The granulated mixture was molded using a mold press and a rubber press to form a molded body of 5 intestine x 5 x 60 x 10 mm. The molded body was placed in a graphite container and sintered at a temperature exceeding 2000° C. in an argon atmosphere to form a ceramic sintered body.

Ceramic sintered bodies have relative density, electrical resistivity, and bending strength (3-point bending strength at room temperature)
The results are shown in Table 1.

The blended amounts of silicon carbide SiC powder and titanium boride Tie powder were 60 g and 40 g, respectively, and 1.0 to 10.0 g of phenol resin with a carbonization degree of 50% by weight.
Comparative Example 5 was repeated, except that the sintering temperature was 1900-2200°C.

Ceramic sintered bodies are characterized by relative density, electrical resistivity, and bending strength (3-point bending strength at room temperature).
were measured, and the measurement results are shown in Table 1.

(Comparative Example 7) The blending amounts of silicon carbide SiC powder and titanium boride Ti1t powder were 20 g and 70 g, respectively, and aluminum oxide A1. Comparative Example 1 was repeated except that Oyu powder was not added directly.

Ceramic sintered bodies have relative density, electrical resistivity, and bending strength (3-point bending strength at room temperature)
were measured, and the measurement results are shown in Table 1.

As is clear from Table 1, according to the present invention, the electrical resistivity of the ceramic sintered body can be reduced to 10 -2 Ωcm or less, compared to the comparative example. Further, according to the present invention, even under normal pressure sintering, the electrical resistivity is 10-2 Ωcm or less and the electrical resistivity is 95
% or more of the theoretical relative density, and as a result, the mechanical strength, for example, the bending strength, can be increased to 500 MPa or more, compared to the comparative example. Therefore, according to the present invention, electrical discharge machining of a ceramic sintered body can be facilitated, even a shape with a large depth can be machined in a short time, and high strength and high toughness can be ensured.

In the above embodiment, the particle size of the silicon carbide SiC powder is 0.5 g, m, but the particle size is not limited to this. However, considering the mechanical strength of the ceramic sintered body, the particle size of the silicon carbide SiC powder is
In particular, it is preferably 1Bm or less.

(3) Effects of the Invention As is clear from the above, the ceramic sintered body according to the present invention contains 30 to 70 parts by weight of titanium boride powder to 25 to 60 parts by weight of silicon carbide powder, and Since it contains 3 to 15 parts by weight of aluminum powder and is sintered at a temperature of 1,700 to 2,000°C in an inert gas atmosphere, (a) the electrical resistivity can be reduced to 10-2ΩC or less; In addition, (b) it has the effect of facilitating electrical discharge machining, and (c) it has an electrical resistivity of 10-2 Ω or less (J or less and a theoretical relative resistance of 95% or more) even during pressureless sintering. It also has the effect of achieving high density, increasing mechanical strength, such as bending strength, to 500 MPa or more, and achieving high strength and toughness.

Claims (1)

[Scope of Claims] (1) 5 to 70 parts by weight of titanium boride powder and 3 to 15 parts by weight of aluminum oxide powder are blended to 25 to 90 parts by weight of silicon carbide powder, A silicon carbide sintered body characterized by being sintered at a temperature of 1700 to 2000°C in an inert gas atmosphere. (2) The silicon carbide sintered body according to claim (1), wherein 4 parts by weight or less of carbon is added to the silicon carbide powder. (4) The bending strength is 500 MPa or more at room temperature.
2) The silicon carbide sintered body described in item 2). (4) The silicon carbide sintered body according to any one of claims (1) to (3), characterized in that the electrical resistivity is 10Ω^2cm or less at room temperature. .