JPH07126070A - Production of silicon carbide sintered material - Google Patents

Production of silicon carbide sintered material

Info

Publication number
JPH07126070A
JPH07126070A JP5271885A JP27188593A JPH07126070A JP H07126070 A JPH07126070 A JP H07126070A JP 5271885 A JP5271885 A JP 5271885A JP 27188593 A JP27188593 A JP 27188593A JP H07126070 A JPH07126070 A JP H07126070A
Authority
JP
Japan
Prior art keywords
sintered body
density
surface layer
sintered material
relative density
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP5271885A
Other languages
Japanese (ja)
Inventor
Shuichi Tateno
周一 立野
Masaki Terasono
正喜 寺園
Kenji Kitazawa
謙治 北澤
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Kyocera Corp
Original Assignee
Kyocera Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Kyocera Corp filed Critical Kyocera Corp
Priority to JP5271885A priority Critical patent/JPH07126070A/en
Publication of JPH07126070A publication Critical patent/JPH07126070A/en
Pending legal-status Critical Current

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Abstract

PURPOSE:To produce a high-density sintered material by forming a preliminary sintered material so that the surface layer may have a higher density than that of the inside and that the inside and the surface layer may have >=a specified relative density and applying an isostatic hot pressing treatment thereto. CONSTITUTION:A specific amount of a sintering assistant such as powdery B4C is admixed with a powdery alpha- or beta-type SiC having about 0.1 to 3.0mum average particle diameter and a forming binder is applied to the resultant mixture to form a specific shape and this process is repeated two or more times. The obtained shaped material is then calcined in a non-oxidative atmosphere at about 1900 to 2200 deg.C for about 0.5 to 4hr to prepare a preliminary sintered material having >=90% relative density of the inside and >=96% relative density of the surface layer. The resultant preliminary sintered material is then sintered in a non-oxidative atmosphere under conditions of about 500 to 2000atm and about 1600 to 2000 deg.C according to the isostatic hot pressing method, thus producing the objective dense SiC sintered material having >=about 99% relative density.

Description

【発明の詳細な説明】Detailed Description of the Invention

【0001】[0001]

【産業上の利用分野】本発明は、炭化珪素質焼結体の製
造方法に関し、詳細には大型形状の焼結体を製造するに
適した製造方法に関する。
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a silicon carbide based sintered body, and more particularly to a method for producing a large-sized sintered body.

【0002】[0002]

【従来技術】炭化珪素質焼結体は、機械的強度、高温強
度、硬度等に優れたセラミック材料として注目され、金
属に代わる各種の機械用部品への応用が進められてい
る。
2. Description of the Prior Art Sintered silicon carbide has been attracting attention as a ceramic material excellent in mechanical strength, high temperature strength, hardness, etc., and is being applied to various mechanical parts in place of metals.

【0003】このような炭化珪素質焼結体は、一般には
焼結助剤として炭素あるいはホウ素を添加し固相焼結す
るか、あるいはAl2 3 等の酸化物を添加し液相焼結
するなどの手法により高密度化が図られている。中でも
高密度焼結体を得る方法として、最近では熱間静水圧焼
成法(HIP法)が知られている。この方法は、ホット
プレス焼成、あるいは常圧焼成により得られた予備焼結
体に対して2000気圧の高圧ガスを付与しつつ焼成す
る方法である。
Such a silicon carbide sintered body is generally solid phase sintered by adding carbon or boron as a sintering aid, or liquid phase sintering by adding an oxide such as Al 2 O 3 or the like. Higher densities have been achieved by methods such as Among them, a hot isostatic pressing method (HIP method) has recently been known as a method for obtaining a high-density sintered body. This method is a method in which a pre-sintered body obtained by hot press firing or normal pressure firing is fired while applying a high pressure gas of 2000 atm.

【0004】[0004]

【発明が解決しようとする問題点】しかしながら、上記
HIP法では、予備焼結体として95%以上以上の相対
密度を有していなければ、高圧ガスによる圧力が焼結体
にかからず、さらに高密度化することができない。この
ような高密度の予備焼結体は、小型形状品の場合には従
来法により比較的容易に作製することができる。
However, in the above HIP method, unless the relative density of the pre-sintered body is 95% or more, the pressure by the high pressure gas does not act on the sintered body, and It cannot be densified. Such a high-density pre-sintered body can be relatively easily manufactured by a conventional method in the case of a small shape product.

【0005】しかしながら、大型形状品の場合には、内
部から表面に至り高密度の焼結体を得ることは非常に困
難であるため、HIP法を適用しても高密度体を得るこ
とができない。
However, in the case of a large-sized product, it is very difficult to obtain a high-density sintered body from the inside to the surface. Therefore, even if the HIP method is applied, a high-density product cannot be obtained. .

【0006】従って、本発明の目的は、大型形状品であ
っても熱間静水圧焼成により高密度の焼結体を得ること
のできる炭化珪素質焼結体の製造方法を提供するにあ
る。
Therefore, an object of the present invention is to provide a method for producing a silicon carbide based sintered body, which is capable of obtaining a high density sintered body by hot isostatic firing even in a large-sized product.

【0007】[0007]

【問題点を解決するための手段】本発明者らは、大型形
状品の予備焼結体の密度を高めるための方法について検
討したところ、静水圧が印加されるには、かならずしも
予備焼結体全体が高密度である必要がなく、焼結体表面
付近のみが高密度であればHIP処理により高密度化が
達成されることを見いだし、本発明に至った。
The inventors of the present invention have studied a method for increasing the density of a pre-sintered body of a large-sized product, and found that the pre-sintered body must be applied to apply hydrostatic pressure. The present invention has been completed by discovering that it is not necessary for the whole to have a high density, and if only the vicinity of the surface of the sintered body has a high density, HIP treatment can achieve high density.

【0008】即ち、本発明の炭化珪素質焼結体の製造方
法は、炭化珪素粉末に焼結助剤を添加した混合粉末を所
定の形状に成形した後、その成形体を非酸化性雰囲気中
で焼成して予備焼結体を得、さらに該予備焼結体を熱間
静水圧焼成するに当たり、予備焼結体として、表層部の
密度が内部よりも高く、内部の相対密度が90%以上、
表層部の相対密度が96%以上であることを特徴とする
もので、さらには、前記予備焼結体が、混合粉末に対し
て静水圧を印加し成形する工程を少なくとも2回以上繰
り返した後、その成形体を非酸化性雰囲気中で焼成する
ことにより得られたものであることを特徴とするのであ
る。
That is, according to the method for producing a silicon carbide-based sintered body of the present invention, a mixed powder obtained by adding a sintering aid to silicon carbide powder is molded into a predetermined shape, and then the molded body is placed in a non-oxidizing atmosphere. In order to obtain a pre-sintered body by calcining the pre-sintered body, and further subjecting the pre-sintered body to hot isostatic pressing, the density of the surface layer portion is higher than that of the interior and the relative density of the interior is 90% or more. ,
The relative density of the surface layer portion is 96% or more, and further, after the step of applying the hydrostatic pressure to the mixed powder and molding the pre-sintered body is repeated at least twice or more. It is characterized by being obtained by firing the molded body in a non-oxidizing atmosphere.

【0009】以下、本発明を詳述する。本発明の製造方
法によれば、まず、原料粉末として用いられる炭化珪素
粉末としては、α型、β型のいずれでもよく、平均粒径
が0.1〜3.0μm程度のものが好適である。また、
この炭化珪素粉末に添加される焼結助剤としては、公知
の助剤が使用でき、例えば炭素粉末やB、B4 C等のホ
ウ素化合物、Al、Be、Al2 3 、Y2 3 等の粉
末が使用できる。これらの焼結助剤は、助剤の種類によ
り適宜その量を決定され、具体的には、特開昭54−1
44411号、特開昭57−42577号、特開昭55
−116667号等に記載されるような比率で添加すれ
ばよい。
The present invention will be described in detail below. According to the production method of the present invention, first, the silicon carbide powder used as the raw material powder may be either α-type or β-type, and an average particle size of about 0.1 to 3.0 μm is preferable. . Also,
As the sintering aid added to the silicon carbide powder, known auxiliaries can be used. For example, carbon powder, boron compounds such as B and B 4 C, Al, Be, Al 2 O 3 and Y 2 O 3 can be used. And the like can be used. The amount of these sintering aids is appropriately determined depending on the kind of the aid, and specifically, it is described in JP-A-54-1.
44411, JP-A-57-42577, JP-A-55.
It may be added in a ratio as described in No. 116667.

【0010】このように炭化珪素粉末と焼結助剤とを上
記のように混合した後、成形用バインダー等を添加した
後、所定の形状に成形する。セラミックスの成形手段と
しては、金型プレス成形、冷間静水圧プレス成形、押出
し成形、射出成形などが知られているが、本発明によれ
ば、この中でも冷間静水圧プレスを用いる。この冷間静
水圧プレスは、混合粉末を変形可能な容器内に入れて水
又は油を圧力媒体として300〜5000kg/cm2
の圧力を印加し成形するものである。さらに、本発明に
よれば、このような静水圧プレス成形を2回以上繰り返
し行うことが重要である。具体的には、前記圧力を付与
して成形後、圧力を解除した後、再度圧力を付与しまた
圧力を解除し、場合によってはこれを繰り返し行う。な
お、静水圧プレスを行う前に、金型プレスなどの他の成
形方法により所望の形状に成形しておいてもよい。
After the silicon carbide powder and the sintering aid are mixed as described above, a binder for molding and the like are added, and the mixture is molded into a predetermined shape. As the ceramics molding means, die press molding, cold isostatic pressing, extrusion molding, injection molding and the like are known. According to the present invention, among them, cold isostatic pressing is used. In this cold isostatic press, the mixed powder is placed in a deformable container and water or oil is used as a pressure medium to obtain 300 to 5000 kg / cm 2.
The pressure is applied to mold. Further, according to the present invention, it is important to repeat such isostatic press molding twice or more. Specifically, after the pressure is applied and molded, the pressure is released, then the pressure is applied again and the pressure is released, and this is repeated in some cases. In addition, before performing the isostatic pressing, it may be formed into a desired shape by another forming method such as a die press.

【0011】上記のように圧力付与−解除を繰り返し行
うと、成形体の密度は全体的に徐々に高くなるが、特に
成形体の表層部における密度が高くなり、最終的には表
層部と内部とで密度差の存在する成形体が得られる。得
られる成形体の相対密度としては、内部が60%以上で
あることが望ましく、表層部はこれより高く、70%以
上であることがよい。
When the pressure application-release is repeatedly performed as described above, the density of the molded product gradually increases as a whole, but the density of the surface layer part of the molded product increases, and finally the surface layer part and the inside thereof. With and, a molded product having a density difference can be obtained. The relative density of the obtained molded body is preferably 60% or more in the inside, and higher than 70% in the surface layer portion.

【0012】本発明によれば、上記のようにして得られ
た成形体を予備焼成することにより内部の相対密度が9
0%以上で、表層部の相対密度が96%以上の焼結体を
得ることが重要である。このような密度を有する焼結体
を得るには、上記成形体を真空中やAr、N2 等の非酸
化性雰囲気中で1900〜2200℃で0.5〜4時間
程度焼成することにより得ることができる。
According to the present invention, the internal relative density is 9 by pre-baking the molded body obtained as described above.
It is important to obtain a sintered body in which the relative density of the surface layer portion is 0% or more and 96% or more. To obtain a sintered body having such a density, it is obtained by firing the above-mentioned molded body in vacuum or in a non-oxidizing atmosphere such as Ar or N 2 at 1900 to 2200 ° C. for about 0.5 to 4 hours. be able to.

【0013】次に、上記予備焼結体をアルゴンガスを圧
力媒体として500〜2000気圧の高圧下で1600
〜2000℃の温度で焼成することにより99%以上の
相対密度を有する焼結体を得ることができる。
Next, the presintered body was subjected to a pressure of 1600 at a pressure of 500 to 2000 atm using argon gas as a pressure medium.
By firing at a temperature of up to 2000 ° C, a sintered body having a relative density of 99% or more can be obtained.

【0014】なお、上記製造方法において予備焼成温度
および熱間静水圧焼成温度を上記の範囲に限定したの
は、温度が規定した条件より低いと所望の密度が得られ
ず、逆に高すぎると炭化珪素の分解が生じて表面が荒れ
特性も劣化するためである。
In the above-mentioned manufacturing method, the pre-firing temperature and the hot isostatic firing temperature are limited to the above ranges, because the desired density cannot be obtained when the temperature is lower than the specified conditions, and conversely, when the temperature is too high. This is because the decomposition of silicon carbide occurs and the surface is roughened and the characteristics are deteriorated.

【0015】[0015]

【作用】本発明の製造方法によれば、成形方法として冷
間静水圧プレス法を用いて圧力付与−圧力解除を繰り返
し行うと、成形体の全体的密度は回数を重ねることによ
り徐々に高くなるが、ある一定まで密度が高められると
それ以上密度が高くならない。しかしながら、この時の
成形体の表層部と内部とで表層部の方が内部よりも高く
なるという現象が生じる。このような表層部の密度が高
い成形体を焼成すると、表層部の方が緻密質な焼結体が
得られる。
According to the manufacturing method of the present invention, when the cold isostatic pressing method is used as the molding method to repeatedly apply pressure and release pressure, the overall density of the molded body gradually increases with the number of times. However, once the density is increased to a certain level, the density does not increase any further. However, at this time, a phenomenon occurs in which the surface layer portion of the molded body is higher than the inner portion of the surface layer portion. When a compact having such a high surface layer density is fired, a sintered body having a denser surface layer can be obtained.

【0016】予備焼成−熱間静水圧焼成により緻密化を
図る場合、予備焼結体として少なくとも95%以上の相
対密度が必要であるが、大型品では、このような高密度
の予備焼結体を作製することは難しい。
Pre-firing-When densifying by hot isostatic pressing, a relative density of at least 95% or more is required as a pre-sintered body. Is difficult to make.

【0017】そこで、本発明によれば、前記の成形−予
備焼成により表層部のみ密度の高い焼結体を得ることに
より、大型品であっても熱間静水圧焼成により高密度の
焼結体を得ることができる。
Therefore, according to the present invention, a sintered body having a high density only in the surface layer portion is obtained by the above-mentioned forming-prefiring, so that even a large-sized product can be sintered by hot isostatic pressing to have a high density. Can be obtained.

【0018】よって、大型形状品について、必ずしも全
体としての相対密度が95%以上の予備焼結体を作製す
る必要がなく、表層部のみ密度が高ければ高圧が焼結体
全体に付与されて内部まで高密度で均質な焼結体を得る
ことができる。
Therefore, it is not necessary to prepare a pre-sintered body having a relative density as a whole of 95% or more for a large-sized product, and if only the surface layer portion has a high density, a high pressure is applied to the whole sintered body. It is possible to obtain a high density and homogeneous sintered body.

【0019】[0019]

【実施例】β型SiC粉末に、B4 C粉末0.4重量%
と炭素粉末2重量%を添加し、ボールミルにより24時
間混合した後、この混合粉末に結合材としてフェノール
樹脂を添加し0.1kg/cm2 の圧力で一軸プレスし
た後、静水圧プレスを行ない直径60mm、厚さ30m
mの成形体を得た。この時、静水圧プレスは2000k
g/cm2 の圧力により1〜4回行った。その後、上記
成形体をアルゴン中、2000℃で3時間予備焼成した
後、196MPaのアルゴン中、1950℃で1時間熱
間静水圧焼成した。
EXAMPLE 0.4% by weight of B 4 C powder was added to β-type SiC powder.
And 2% by weight of carbon powder and mixed by a ball mill for 24 hours, phenol resin as a binder was added to this mixed powder, and the mixture was uniaxially pressed at a pressure of 0.1 kg / cm 2 , and then hydrostatically pressed to obtain a diameter. 60mm, thickness 30m
A molded body of m was obtained. At this time, the hydrostatic press is 2000k
It was carried out 1 to 4 times with a pressure of g / cm 2 . Then, the molded body was pre-baked in argon at 2000 ° C. for 3 hours and then hot isostatically baked in argon at 196 MPa at 1950 ° C. for 1 hour.

【0020】上記工程中、成形体、予備焼結体および最
終焼結体の密度を測定した。密度の測定は、硬度と密度
が直線的な関係にあることから検量線を作成し、成形体
の表層部から内部にわたり1mm間隔で硬度測定を行
い、測定された硬度を作成した検量線により相対密度に
換算した。また、焼結体の特性としては、JISR16
01に基づく試験片を最終焼結体より切り出し3点曲げ
強度を測定した。結果は表1に示した。
During the above steps, the densities of the molded body, the pre-sintered body and the final sintered body were measured. As for the measurement of the density, since the hardness and the density have a linear relationship, a calibration curve is created, and the hardness is measured at 1 mm intervals from the surface layer portion of the molded body to the inside, and the measured hardness is relative by the created calibration curve. Converted to density. The characteristics of the sintered body are JIS R16.
A test piece based on No. 01 was cut out from the final sintered body and the three-point bending strength was measured. The results are shown in Table 1.

【0021】[0021]

【表1】 [Table 1]

【0022】表1の結果によれば、予備焼結体の表層部
の相対密度が96%に達していない試料No.1,2では
いずれも最終焼結体において高い高密度化が達成されな
いのに対して、本発明に基づき作製された予備焼結体表
層部の相対密度が96%以上の焼結体は、最終焼結体に
おいて内部まで十分に緻密化しており、比較例に比べて
強度も高いものであった。
According to the results shown in Table 1, in samples No. 1 and 2 in which the relative density of the surface layer portion of the pre-sintered body has not reached 96%, high densification cannot be achieved in the final sintered body. On the other hand, the sintered body having a relative density of the surface layer portion of the pre-sintered body produced according to the present invention of 96% or more has sufficiently densified to the inside in the final sintered body, and has a higher strength than the comparative example. Was also expensive.

【0023】[0023]

【発明の効果】以上詳述したように、本発明の製造方法
によれば、HIP焼成により高密度の焼結体を得るため
に必要な予備焼結体密度より内部密度が低い焼結体であ
っても、高密度の焼結体を得ることができる。よって、
大型形状品の作製において、容易に高密度で均質な焼結
体を得ることができる。
As described in detail above, according to the manufacturing method of the present invention, a sintered body having an internal density lower than the density of the pre-sintered body required to obtain a high density sintered body by HIP firing is used. Even if it exists, a high-density sintered body can be obtained. Therefore,
In producing a large-sized product, a high-density and homogeneous sintered body can be easily obtained.

Claims (2)

【特許請求の範囲】[Claims] 【請求項1】炭化珪素粉末に焼結助剤を添加した混合粉
末を所定の形状に成形した後、該成形体を非酸化性雰囲
気中で焼成して予備焼結体を得、さらに該予備焼結体を
熱間静水圧焼成する炭化珪素質焼結体の製造方法におい
て、前記予備焼結体の表層部の密度が内部よりも高く、
内部の相対密度が90%以上、表層部の相対密度が96
%以上であることを特徴とする炭化珪素質焼結体の製造
方法。
1. A mixed powder obtained by adding a sintering aid to silicon carbide powder is molded into a predetermined shape, and the molded body is fired in a non-oxidizing atmosphere to obtain a pre-sintered body. In the method for manufacturing a silicon carbide-based sintered body in which a sintered body is hot isostatically fired, the density of the surface layer portion of the pre-sintered body is higher than that of the inside,
Internal relative density is 90% or more, surface layer relative density is 96
% Or more, a method for producing a silicon carbide-based sintered body.
【請求項2】前記予備焼結体が、前記混合粉末に対して
静水圧を印加し成形する工程を少なくとも2回以上繰り
返した後、その成形体を非酸化性雰囲気中で焼成するこ
とにより得られたものであることを特徴とする炭化珪素
質焼結体の製造方法。
2. The pre-sintered body is obtained by repeating the step of applying a hydrostatic pressure to the mixed powder and molding it at least twice, and then firing the molded body in a non-oxidizing atmosphere. A method for manufacturing a silicon carbide-based sintered body, characterized by comprising:
JP5271885A 1993-10-29 1993-10-29 Production of silicon carbide sintered material Pending JPH07126070A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP5271885A JPH07126070A (en) 1993-10-29 1993-10-29 Production of silicon carbide sintered material

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP5271885A JPH07126070A (en) 1993-10-29 1993-10-29 Production of silicon carbide sintered material

Publications (1)

Publication Number Publication Date
JPH07126070A true JPH07126070A (en) 1995-05-16

Family

ID=17506264

Family Applications (1)

Application Number Title Priority Date Filing Date
JP5271885A Pending JPH07126070A (en) 1993-10-29 1993-10-29 Production of silicon carbide sintered material

Country Status (1)

Country Link
JP (1) JPH07126070A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001192258A (en) * 1999-12-28 2001-07-17 Toshiba Corp Ceramic sintered compact, method of producing the same, and sliding member, bearing ball and bearing using the same
WO2001097264A1 (en) * 2000-06-16 2001-12-20 Ibiden Co., Ltd. Hot plate
JP2022057795A (en) * 2020-09-30 2022-04-11 日本碍子株式会社 Firing setter

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001192258A (en) * 1999-12-28 2001-07-17 Toshiba Corp Ceramic sintered compact, method of producing the same, and sliding member, bearing ball and bearing using the same
JP4642956B2 (en) * 1999-12-28 2011-03-02 株式会社東芝 Bearing ball, bearing, and method of manufacturing bearing ball
WO2001097264A1 (en) * 2000-06-16 2001-12-20 Ibiden Co., Ltd. Hot plate
US6825555B2 (en) 2000-06-16 2004-11-30 Ibiden Co., Ltd. Hot plate
JP2022057795A (en) * 2020-09-30 2022-04-11 日本碍子株式会社 Firing setter

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