JPH06166571A - Production of sintered silicon nitride - Google Patents
Production of sintered silicon nitrideInfo
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- JPH06166571A JPH06166571A JP3245868A JP24586891A JPH06166571A JP H06166571 A JPH06166571 A JP H06166571A JP 3245868 A JP3245868 A JP 3245868A JP 24586891 A JP24586891 A JP 24586891A JP H06166571 A JPH06166571 A JP H06166571A
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Abstract
Description
【０００１】[0001]
【産業上の利用分野】この発明は、自動車，機械装置，
化学装置，宇宙航空機器などの広い分野において使用さ
れる各種構造部品の素材として利用でき、安価なβ型窒
化ケイ素粉末を原料として用い、とくに高い破壊靭性値
と優れた強度を有するファインセラミックス材料を得る
のに好適な窒化ケイ素質焼結体の製造方法に関するもの
である。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to automobiles, mechanical devices,
A fine ceramic material that can be used as a raw material for various structural parts used in a wide range of fields such as chemical equipment and aerospace equipment, and that uses inexpensive β-type silicon nitride powder as a raw material and that has a particularly high fracture toughness value and excellent strength The present invention relates to a method for producing a silicon nitride-based sintered body suitable for obtaining.
【０００２】[0002]
【従来の技術】窒化ケイ素を主成分とする焼結体は、常
温および高温で化学的に安定であり、高い機械的強度を
有するため、軸受などの摺動部材、ターボチャージャロ
ータなどのエンジン部材として好適な材料である。2. Description of the Related Art Sintered bodies containing silicon nitride as a main component are chemically stable at room temperature and high temperature and have high mechanical strength. Therefore, sliding members such as bearings and engine members such as turbocharger rotors are used. Is a suitable material.
【０００３】従来より、高強度の窒化ケイ素質焼結体を
得るには、α型を主成分とする原料粉末が必要とされて
おり、一般にα型の含有率が９０重量％以上の粉末が市
販されている。ここで、α型を主成分とする原料粉末を
用いるのは、 １．α型は微粉末であり、焼結性が高いこと、 ２．焼結中にα型からβ型への相転移が起こり、柱状結
晶が発達した組織となることにより強度および靭性が向
上すること、 等の理由からであった。Conventionally, in order to obtain a high-strength silicon nitride sintered body, a raw material powder containing α-type as a main component has been required. Generally, a powder having an α-type content of 90% by weight or more is required. It is commercially available. Here, the raw material powder mainly composed of α type is used as follows. 1. The α type is a fine powder and has high sinterability, This is because the phase transition from α-type to β-type occurs during sintering and the columnar crystals develop into a structure, which improves strength and toughness.
【０００４】[0004]
【発明が解決しようとする課題】しかしながら、上記し
たα型を出発原料とする窒化ケイ素粉末は、α型の含有
量を制御する必要があるため、原料粉末の合成過程が複
雑となり、原料が高価なものになるという問題点があっ
た。However, in the above-mentioned silicon nitride powder starting from α-type as a starting material, it is necessary to control the content of α-type, so that the synthesis process of the raw material powder is complicated and the raw material is expensive. There was a problem that it would be something like.
【０００５】一方、β型を主成分とする窒化ケイ素粉末
としては、耐火物の原料として使用する粉末が知られて
いる。このβ型を主成分とする窒化ケイ素を原料とする
焼結体としては、Ｊ．Ａｍ．Ｃｅｒａｍ．Ｓｏｃ．５７
巻２５ページ（１９７４年），特開昭５８−１５１３７
１号等が知られている。On the other hand, as a silicon nitride powder containing β-type as a main component, a powder used as a raw material of a refractory is known. As a sintered body made of silicon nitride containing β type as a main component as a raw material, J. Am. Ceram. Soc. 57
Volume 25 (1974), JP-A-58-15137
No. 1 is known.
【０００６】しかし、β型を主成分とする粉末は粒子が
粗く、α相の含有率が低いため柱状組織が得られず、高
強度の焼結体は得られないので、高強度の焼結体を製造
するための原料粉末としては使用されていなかった。However, the powder containing β-type as the main component has coarse particles, and since the content of α-phase is low, a columnar structure cannot be obtained and a high-strength sintered body cannot be obtained. It was not used as a raw material powder for manufacturing the body.
【０００７】本発明者の一人は、先に、高窒素下で高温
での焼結が可能となるガス圧焼結法を開発した（特許
１，２４７，１８３号）。また、ガス圧焼結法による
と、従来、焼結性が低いと考えられていたβ型窒化ケイ
素粉末を用いても、高密度まで焼結できることを示した
（ジャーナル オブ マテリアルズ サイエンス 第１
１巻 １１０３頁から１１０７頁（１９７６年）および
特公昭５８−１５１３７１号）。さらに、平成元年３月
２９日付けの特許出願で、高純度のβ型窒化ケイ素粉末
の粒度分布を調整することにより高強度の焼結体が得ら
れることを示した。One of the inventors of the present invention previously developed a gas pressure sintering method which enables sintering at high temperature under high nitrogen (Japanese Patent No. 1,247,183). In addition, according to the gas pressure sintering method, it was shown that β-type silicon nitride powder, which was conventionally considered to have low sinterability, can be sintered to a high density (Journal of Materials Science No. 1).
1 1103 to 1107 (1976) and Japanese Examined Patent Publication No. 58-151371). Further, in a patent application dated March 29, 1989, it was shown that a high-strength sintered body can be obtained by adjusting the particle size distribution of high-purity β-type silicon nitride powder.
【０００８】しかしながら、出発原料として高純度のβ
型粉末を用いることが必要であり、高価なものになると
いう問題点があった。However, high-purity β as a starting material
There is a problem that it is necessary to use a mold powder, which is expensive.
【０００９】それゆえ、原料粉末の合成過程が複雑でな
く、かつまた高純度のβ型粉末を用いる必要がなく、安
価な耐火物グレードのβ型窒化ケイ素粉末を原料として
強度および靭性に優れた窒化ケイ素質焼結体を得ること
ができるようにすることが課題となっていた。Therefore, the process of synthesizing the raw material powder is not complicated, and it is not necessary to use the high-purity β-type powder, and the inexpensive refractory-grade β-type silicon nitride powder is used as the raw material and is excellent in strength and toughness. It has been a problem to be able to obtain a silicon nitride sintered body.
【００１０】[0010]
【発明の目的】この発明は、上記した従来の課題にかん
がみてなされたもので、安価な耐火物グレードのβ型窒
化ケイ素粉末を原料とし、粉砕分級処理を施すことによ
り、粒度分布を制御した原料粉末を使用することによっ
て、強度および靭性に優れた窒化ケイ素質焼結体を提供
することを目的としている。SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and uses an inexpensive refractory grade β-type silicon nitride powder as a raw material, and controls the particle size distribution by pulverizing and classifying. It is an object of the present invention to provide a silicon nitride sintered body excellent in strength and toughness by using the raw material powder.
【００１１】[0011]
【課題を解決するための手段】この発明に係わる窒化ケ
イ素質焼結体の製造方法では、安価な耐火物グレードの
β型窒化ケイ素粉末を原料とし、適切な粉砕分級処理を
施すことにより粒度分布を制御した原料粉末を使用する
ことによって、高純度粉末を出発原料とした窒化ケイ素
質焼結体に劣らない優れた強度および靭性を備えた窒化
ケイ素質焼結体が得られることを新規に見い出してこの
発明を完成した。In the method for manufacturing a silicon nitride sintered body according to the present invention, an inexpensive refractory grade β-type silicon nitride powder is used as a raw material and subjected to an appropriate pulverizing and classifying treatment to obtain a particle size distribution. It has been newly found that the use of a raw material powder having a controlled temperature makes it possible to obtain a silicon nitride sintered body having excellent strength and toughness comparable to a silicon nitride sintered body using a high-purity powder as a starting material. The invention was completed.
【００１２】すなわち、この発明に係わる窒化ケイ素質
焼結体の製造方法は、α型とβ型とを有する窒化ケイ素
原料粉末においてβ型を８０重量％以上含みかつ平均粒
径が２．０μｍ以上の窒化ケイ素原料粉末に粉砕分級処
理を施して、０．８μｍ以下の割合が７０重量％以上９
５重量％以下でかつ１．５μｍ以上５．０μｍ以下の割
合が５重量％以上３０重量％以下の粒度分布に制御し、
この窒化ケイ素原料粉末に焼結助剤を添加して成形した
後、窒素雰囲気下で焼成する構成としたことを特徴とし
ており、このような窒化ケイ素質焼結体の製造方法に係
わる発明の構成をもって前述した従来の課題を解決する
ための手段としている。That is, in the method for producing a silicon nitride sintered body according to the present invention, the silicon nitride raw material powder having α type and β type contains β type in an amount of 80% by weight or more and has an average particle size of 2.0 μm or more. The raw material powder of silicon nitride is pulverized and classified so that the proportion of 0.8 μm or less is 70% by weight or more and 9% or less.
5% by weight or less and a ratio of 1.5 μm or more and 5.0 μm or less is controlled to a particle size distribution of 5% by weight or more and 30% by weight or less,
The silicon nitride raw material powder is molded by adding a sintering aid, and is then fired in a nitrogen atmosphere. The constitution of the invention relating to the method for producing such a silicon nitride sintered body is characterized. Is a means for solving the above-mentioned conventional problems.
【００１３】この発明に係わる窒化ケイ素質焼結体の製
造方法において、焼結助剤としては、酸化物および窒化
物より選択されたものを使用することができる。また、
窒素雰囲気下での焼成に際しては、１６００〜２０００
℃の温度を採用することができる。In the method for manufacturing a silicon nitride sintered body according to the present invention, a sintering aid selected from oxides and nitrides can be used. Also,
When firing in a nitrogen atmosphere, 1600 to 2000
Temperatures of ° C can be employed.
【００１４】この発明に係わる窒化ケイ素質焼結体の製
造方法において、出発原料粉末としては、α型とβ型と
を有する窒化ケイ素原料粉末においてβ型を８０重量％
以上含みかつ平均粒径が２．０μｍ以上の窒化ケイ素原
料粉末を用いる。この場合、この発明では、β型の窒化
ケイ素の焼結性に合わせた粒度分布および焼成条件を設
定するので、α型の含有量が多くなると異常粒成長が起
こり、強度が低下する。そして、前記窒化ケイ素原料粉
末に粉砕分級処理を施すことによって、０．８μｍ以下
と１．５μｍ以上５．０μｍ以下の粒子を得る必要があ
るため、窒化ケイ素原料粉末の平均粒径は２．０μｍ以
上とすることが必要である。In the method for producing a silicon nitride sintered body according to the present invention, the starting raw material powder is a silicon nitride raw material powder having α type and β type, and β type is 80% by weight.
A silicon nitride raw material powder containing the above and having an average particle diameter of 2.0 μm or more is used. In this case, in the present invention, since the particle size distribution and firing conditions are set in accordance with the sinterability of β-type silicon nitride, if the α-type content increases, abnormal grain growth occurs and the strength decreases. Then, it is necessary to obtain particles of 0.8 μm or less and 1.5 μm or more and 5.0 μm or less by subjecting the silicon nitride raw material powder to pulverizing and classifying treatment, so that the average particle diameter of the silicon nitride raw material powder is 2.0 μm. It is necessary to do the above.
【００１５】次に、前記窒化ケイ素原料粉末に粉砕分級
処理を施すことによって、０．８μｍ以下の割合が７０
重量％以上９５重量％以下でかつ１．５μｍ以上５．０
μｍ以下の割合が５重量％以上３０重量％以下である粒
度分布に制御する。この場合、０．８μｍ以下の粉末
と、１．５μｍ以上５．０μｍ以下の粉末のみよりなる
場合に限定されないものであり、前記割合を満たす範囲
内でその他０．８μｍ超過１．５μｍ未満の粉末や５．
０μｍ超過の粉末を若干含んでいる場合も包含される。
そして、０．８μｍ以下の粉末（以下、「細粒」と呼
ぶ。）は、焼結体の緻密化を促進する働きをするため、
細粒の最大粒子径が０．８μｍ超過となると焼結性が低
下する。また、細粒の割合が７０重量％未満となると焼
結性が低下する。反対に、細粒の割合が９５重量％超過
となると、組織制御の粒成長の核となる１．５μｍ以上
５．０μｍ以下の範囲の粒子（以下、「粗粒」と呼
ぶ。）の割合が少なくなるため、緻密化はするものの柱
状の組織が発達せず、強度および靭性値が低下する。Next, the silicon nitride raw material powder is subjected to a pulverizing and classifying treatment to reduce the ratio of 0.8 μm or less to 70%.
% To 95% by Weight and 1.5 μm to 5.0
The particle size distribution is controlled such that the proportion of μm or less is 5% by weight or more and 30% by weight or less. In this case, it is not limited to the case where it is composed only of powder of 0.8 μm or less and the powder of 1.5 μm or more and 5.0 μm or less, and the powder of other than 0.8 μm and less than 1.5 μm within the range satisfying the above ratio. And 5.
It also includes the case where a small amount of powder exceeding 0 μm is contained.
And, the powder of 0.8 μm or less (hereinafter referred to as “fine particles”) has a function of promoting the densification of the sintered body,
If the maximum particle size of the fine particles exceeds 0.8 μm, the sinterability decreases. Further, if the proportion of fine particles is less than 70% by weight, the sinterability is deteriorated. On the other hand, when the proportion of fine grains exceeds 95% by weight, the proportion of particles in the range of 1.5 μm or more and 5.0 μm or less (hereinafter referred to as “coarse grains”), which are cores of grain growth for structure control, is produced. Since the amount becomes small, the columnar structure does not develop although it is densified, and the strength and toughness values decrease.
【００１６】粗粒の粒子径は、１．５μｍ以上５．０μ
ｍ以下がよい。すなわち、１．５μｍ未満では柱状の粒
成長の核となる働きが少なく、柱状の組織が得られな
い。反対に、５．０μｍ超過では粒子径の大きい柱状組
織は得られるものの、成長速度が小さいために、強化機
構が小さく強度および靭性が向上しない。また、粗粒の
割合は５重量％以上３０重量％以下が良い。すなわち、
５重量％未満では核が少ないため柱状結晶が発達しな
い。反対に、３０重量％超過では細粒の割合が少なくな
るために焼結性が低下する。さらに、より一層の高強度
化を狙う場合には１０．０μｍ以上の巨大粒子は沈殿法
あるいはふるいなどにより取り除くことが望ましい。The particle size of the coarse particles is from 1.5 μm to 5.0 μm.
m or less is preferable. That is, when the thickness is less than 1.5 μm, there is little function as a nucleus of columnar grain growth, and a columnar structure cannot be obtained. On the other hand, if it exceeds 5.0 μm, a columnar structure having a large particle size can be obtained, but since the growth rate is low, the strengthening mechanism is small and the strength and toughness are not improved. The proportion of coarse particles is preferably 5% by weight or more and 30% by weight or less. That is,
When it is less than 5% by weight, columnar crystals do not develop due to the small number of nuclei. On the other hand, if it exceeds 30% by weight, the proportion of fine particles decreases and the sinterability decreases. Further, when aiming at further higher strength, it is desirable to remove the giant particles of 10.0 μm or more by a precipitation method or a sieve.
【００１７】粉砕分級処理の方法は、上記の粒度分布が
得られる方法ならばどれでも良いが、一例を以下に説明
する。Any method can be used for the pulverizing / classifying treatment as long as the above-mentioned particle size distribution can be obtained. An example will be described below.
【００１８】まず、原料粉末を水に分散させ、次いでア
トリッションミルを用いて粉砕を行い、処理済みのスラ
リーを水槽に入れ、続いて沈殿法によって粒子を分級し
て必要な量の細粒と粗粒を水槽から取り出す。分級によ
って余った粗粒は再度原料と共にアトリッションミルに
投入し、粉砕処理を繰り返す。このようにして、同一粉
末を粉砕分級処理することによって、所定の粒度分布を
持つ原料粉末を得るのが効率の点でよい。First, the raw material powder is dispersed in water, then pulverized by using an attrition mill, the treated slurry is put in a water tank, and then the particles are classified by a precipitation method to obtain a necessary amount of fine particles. And remove the coarse particles from the water tank. The coarse particles left over from the classification are charged again into the attrition mill together with the raw materials, and the crushing process is repeated. In this way, it is good in terms of efficiency to obtain a raw material powder having a predetermined particle size distribution by pulverizing and classifying the same powder.
【００１９】このようにして粒度調整をした窒化ケイ素
原料粉末に、酸化物や窒化物などの焼結助剤を添加す
る。ここで用いる焼結助剤は、通常、α型またはβ型の
窒化ケイ素の焼結に用いる焼結助剤から選ばれる。酸化
物の焼結助剤としては、例えば、ＭｇＯ，Ａｌ２Ｏ３，
Ｙ２Ｏ３またはランタニド金属酸化物から選ばれる１種
あるいは２種以上の混合物を用いる。また、窒化物の焼
結助剤としては、例えば、ＡｌＮが使われる。この焼結
助剤の添加量は、通常、５〜１５重量％が添加される。A sintering aid such as an oxide or a nitride is added to the silicon nitride raw material powder whose particle size has been adjusted in this manner. The sintering aid used here is usually selected from the sintering aids used for sintering α-type or β-type silicon nitride. Examples of the oxide sintering aid include MgO, Al 2 O 3 , and
One or a mixture of two or more selected from Y 2 O 3 and lanthanide metal oxides is used. In addition, for example, AlN is used as the sintering aid for the nitride. The addition amount of this sintering aid is usually 5 to 15% by weight.
【００２０】さらに、上記粉末の成形に際しては、金型
プレス成形，静水圧プレス成形，射出成形，鋳込み成形
など、通常の成形法を用いて成形することができる。こ
の後、成形に要した有機バインダーを除去して焼成を行
う。Further, when molding the above-mentioned powder, it is possible to carry out molding by a usual molding method such as die press molding, isostatic press molding, injection molding, casting molding and the like. After that, the organic binder required for molding is removed and firing is performed.
【００２１】焼成は、窒素雰囲気下で１６００〜２００
０℃の温度で行うのが良い。この場合、窒素は窒化ケイ
素の熱分解を防ぐために必要であり、高温で焼成するほ
ど高圧の窒素雰囲気を使用する。この焼成において必要
な最低圧は、１６００〜１７５０℃の焼成温度で１気
圧、１８００℃の焼成温度で２気圧，１９００℃の焼成
温度で５気圧、２０００℃の焼成温度で１０気圧であ
る。そして、所定圧力よりも低いと窒化ケイ素は熱分解
を起こし、窒素を放出してケイ素となるので好ましくな
い。好ましい焼成温度は、焼結手法と使用する助剤の種
類および量等により異なるが、１６００〜２０００℃の
温度が使用される。焼結手法は、製品形状，使用する焼
結助剤の種類および量等を考えて、ホットプレス，常圧
焼結法，ガス圧焼結法等が採用される。Firing is performed in a nitrogen atmosphere at 1600 to 200.
It is better to carry out at a temperature of 0 ° C. In this case, nitrogen is necessary to prevent thermal decomposition of silicon nitride, and the higher the temperature, the higher the pressure of the nitrogen atmosphere used. The minimum pressure required for this firing is 1 atm at a firing temperature of 1600 to 1750 ° C, 2 atm at a firing temperature of 1800 ° C, 5 atm at a firing temperature of 1900 ° C, and 10 atm at a firing temperature of 2000 ° C. If the pressure is lower than the predetermined pressure, silicon nitride undergoes thermal decomposition and releases nitrogen to become silicon, which is not preferable. The preferable firing temperature varies depending on the sintering method and the type and amount of the auxiliary agent used, but a temperature of 1600 to 2000 ° C. is used. As the sintering method, hot pressing, atmospheric pressure sintering method, gas pressure sintering method and the like are adopted in consideration of the product shape, the type and amount of the sintering aid to be used, and the like.
【００２２】[0022]
【発明の作用】この発明に係わる窒化ケイ素質焼結体の
製造方法においては、β型の窒化ケイ素の焼結特性に合
わせた粒度分布の窒化ケイ素原料粉末を用いるようにし
ており、α型とβ型とを有する窒化ケイ素原料粉末にお
いてβ型を８０重量％以上含みかつ平均粒径が２．０μ
ｍ以上の窒化ケイ素原料粉末に粉砕分級処理を施して、
０．８μｍ以下の割合が７０重量％以上９５重量％以下
でかつ１．５μｍ以上５．０μｍ以下の割合が５重量％
以上３０重量％以下である粒度分布に制御し、この窒化
ケイ素原料粉末に焼結助剤を添加して成形した後、窒素
雰囲気下で焼成するようにしているので、安価な耐火物
グレードのβ型窒化ケイ素粉末を使用したときでも、高
純度粉末を出発原料とした窒化ケイ素質焼結体に劣らな
い優れた強度および破壊靱性値を有する特性の優れた窒
化ケイ素質焼結体が得られることとなる。In the method for producing a silicon nitride sintered body according to the present invention, the silicon nitride raw material powder having a particle size distribution that matches the sintering characteristics of β-type silicon nitride is used. A silicon nitride raw material powder having β-type, containing 80% by weight or more of β-type and having an average particle size of 2.0μ
m or more silicon nitride raw material powder is pulverized and classified,
The proportion of 0.8 μm or less is 70% by weight or more and 95% by weight or less, and the proportion of 1.5 μm or more and 5.0 μm or less is 5% by weight.
Since the particle size distribution is controlled to be 30% by weight or less, a sintering aid is added to the silicon nitride raw material powder, and the mixture is molded and then fired in a nitrogen atmosphere, it is an inexpensive refractory grade β. Even when using the silicon nitride type powder, it is possible to obtain a silicon nitride type sintered body which has excellent strength and fracture toughness value and excellent properties comparable to those of the silicon nitride type sintered body made of high purity powder as a starting material. Becomes
【００２３】[0023]
（実施例１）図１に、この発明の実施例１において採用
した粉砕分級処理の概要を示す。(Embodiment 1) FIG. 1 shows an outline of the pulverizing / classifying treatment adopted in Embodiment 1 of the present invention.
【００２４】この実施例１において、まず、平均粒径
２．５μｍ，最大粒径２０μｍでかつβ型含有量が９９
重量％の窒化ケイ素粉末に水と窒化ケイ素焼結体のビー
ズを添加し、アトリッションミルを使用して連続粉砕を
行い、粉砕後のスラリーを水槽に入れ、水槽の下部から
粗粒を、上部から細粒を取り出すことにより、０．８μ
ｍ以下の細粒の割合が９０重量％、０．８μｍ超過１．
５μｍ未満の割合が１重量％、１．５μｍ以上５．０μ
ｍ以下の粗粒の割合が８重量％，５．０μｍ超過１０．
０μｍ未満の割合が１重量％となるように粒度調整を行
った。この際、水槽の最下部に沈降した巨大粒子（１
０．０μｍ以上）は取り除いて廃却し、余った１．５μ
ｍ以上から１０．０μｍ未満の粉末は回収して再度原料
粉末と共にアトリッションミルに投入した。In Example 1, first, the average particle size was 2.5 μm, the maximum particle size was 20 μm, and the β-type content was 99.
Water and beads of the silicon nitride sintered body are added to the silicon nitride powder of weight%, continuous crushing is performed using an attrition mill, the crushed slurry is put in a water tank, and coarse particles are put from the lower part of the water tank. 0.8μ by removing fine particles from the top
90% by weight of fine particles of m or less, exceeding 0.8 μm 1.
The ratio of less than 5 μm is 1% by weight, 1.5 μm or more and 5.0 μm
8% by weight of coarse particles of m or less, exceeding 5.0 μm 10.
The particle size was adjusted so that the ratio of less than 0 μm was 1% by weight. At this time, the giant particles (1
0.0μm or more) is removed and discarded, and the remaining 1.5μ
The powder having a particle size of m or more and less than 10.0 μm was collected and again charged into the attrition mill together with the raw material powder.
【００２５】次いで、粒度調整した窒化ケイ素原料粉末
に、酸化イットリウム６重量％と酸化アルミニウム２重
量％を添加し、ボールミルで２時間混合した。続いて、
空気中でスプレイドライヤを用いて乾燥した後、２０Ｍ
Ｐａの圧力で金型プレス成形を行い、さらに２００ＭＰ
ａの圧力でラバープレスを施すことによって、６ｍｍ×
６ｍｍ×５０ｍｍの成形体を得た。Next, 6% by weight of yttrium oxide and 2% by weight of aluminum oxide were added to the raw material powder of silicon nitride whose particle size was adjusted, and they were mixed in a ball mill for 2 hours. continue,
20M after drying with a spray dryer in air
Mold press molding with pressure of Pa, 200MP
By applying a rubber press with a pressure of a, 6 mm ×
A 6 mm × 50 mm molded body was obtained.
【００２６】次に、この成形体を表１に示す種々の焼成
条件で焼成することによって各種焼結体を得た後、水を
用いたアルキメデス法により各焼結体の気孔率を求めて
密度を算出した。さらに、８００メッシュのダイヤモン
ドホイールで平面研削し、３ｍｍ×４ｍｍ×４０ｍｍの
形状に加工し、ＪＩＳ Ｒ １６０１に準じた室温３点
曲げにより曲げ強さを求めると共に、ＪＩＳ Ｒ １６
０７に準じたＳＥＰＢ法（試験片の３×４０ｍｍの面に
ビッカース圧痕を加え、これから予亀裂を生成し、この
予亀裂から破壊する手法）により破壊靱性値を求めた。
これらの結果を同じく表１に示す。Next, after firing the molded body under various firing conditions shown in Table 1, various sintered bodies are obtained, and then the porosity of each sintered body is determined by the Archimedes method using water to obtain the density. Was calculated. Further, it was surface ground with an 800 mesh diamond wheel, processed into a shape of 3 mm x 4 mm x 40 mm, and the bending strength was determined by room temperature three-point bending according to JIS R 1601, and JIS R 16
The fracture toughness value was determined by the SEPB method according to 07 (a method in which Vickers indentation is added to the surface of a test piece of 3 × 40 mm, a precrack is generated from this, and fracture is performed from this precrack).
The results are also shown in Table 1.
【００２７】[0027]
【表１】 [Table 1]
【００２８】表１に示した結果より明らかなように、何
れの条件においても高強度かつ高靱性の窒化ケイ素質焼
結体が得られていることが認められた。As is clear from the results shown in Table 1, it was confirmed that a high-strength and high-toughness silicon nitride sintered body was obtained under any of the conditions.
【００２９】（実施例２）図２に、この発明の実施例２
において採用した粉砕分級処理の概要を示す。(Embodiment 2) FIG. 2 shows an embodiment 2 of the present invention.
The outline of the pulverizing and classifying process adopted in is shown below.
【００３０】この実施例２において、まず、平均粒径１
０μｍ，最大粒径２００μｍでかつβ型含有量が９０重
量％の窒化ケイ素粉末に水と窒化ケイ素焼結体のボール
を添加し、ボールミルで２００時間粉砕し、乾燥した
後、ジェット粉砕機と乾式の分級機を使用して粉砕分級
を行い、０．８μｍ以下の細粒と０．８μｍ超過１．５
μｍ未満のものと１．５μｍ以上５．０μｍ以下の粗粒
と５．０μｍ超過１０．０μｍ未満のものを得た。そし
て、１０．０μｍ以上のものは廃却した。次いで、前記
粉末を混合することにより、０．８μｍ以下の細粒の割
合が８０重量％，０．８μｍ超過１．５μｍ未満の割合
が３重量％，１．５μｍ以上５．０μｍ以下の割合が１
５重量％，５．０μｍ超過１０．０μｍ未満の割合が２
重量％となるように粒度調整を行った。In this Example 2, first, the average particle size was 1
Water and balls of a silicon nitride sintered body were added to silicon nitride powder having a particle size of 0 μm, a maximum particle size of 200 μm, and a β-type content of 90% by weight, ground with a ball mill for 200 hours, dried, and then dried with a jet grinder. Pulverizing and classifying using a classifier of 0.8 μm and fine particles of 0.8 μm or less and 0.8 μm or more 1.5
Particles of less than μm, coarse particles of 1.5 μm or more and 5.0 μm or less, and particles of more than 5.0 μm and less than 10.0 μm were obtained. And the thing of 10.0 micrometers or more was abandoned. Then, by mixing the powders, the ratio of fine particles of 0.8 μm or less is 80% by weight, the ratio of 0.8 μm or more and less than 1.5 μm is 3% by weight, and the ratio of 1.5 μm or more and 5.0 μm or less is added. 1
5% by weight, ratio of more than 5.0 μm and less than 10.0 μm is 2
The particle size was adjusted so that the weight% was obtained.
【００３１】次いで、粒度調整した窒化ケイ素原料粉末
に、表２に示す組成の焼結助剤を添加し、ボールミルで
２時間混合した。続いて、空気中でスプレイドライヤを
用いて乾燥した後、２０ＭＰａの圧力で金型成形を行
い、さらに２００ＭＰａの圧力でラバープレスを施すこ
とによって、６ｍｍ×６ｍｍ×５０ｍｍの成形体を得
た。Next, the sintering aid having the composition shown in Table 2 was added to the silicon nitride raw material powder whose particle size was adjusted, and mixed for 2 hours in a ball mill. Then, after drying in air using a spray dryer, mold molding was performed at a pressure of 20 MPa, and a rubber press was further performed at a pressure of 200 MPa to obtain a molded body of 6 mm × 6 mm × 50 mm.
【００３２】次に、この成形体を同じく表２に示す種々
の焼成条件で焼成することによって各焼結体を得た後、
水を用いたアルキメデス法により各焼結体の気孔率を求
めて密度を算出した。さらに、８００メッシュのダイヤ
モンドホイールで平面研削し、３ｍｍ×４ｍｍ×４０ｍ
ｍの形状に加工し、ＪＩＳ Ｒ １６０１に準じた室温
３点曲げにより曲げ強さを求めると共に、ＪＩＳ Ｒ
１６０７に準じたＳＥＰＢ法（試験片の３×４０ｍｍの
面にビッカース圧痕を加え、これから予亀裂を生成し、
この予亀裂から破壊する手法）により破壊靱性値を求め
た。これらの結果を同じく表２に示す。Next, after firing the molded body under various firing conditions similarly shown in Table 2 to obtain respective sintered bodies,
The density was calculated by obtaining the porosity of each sintered body by the Archimedes method using water. Furthermore, the surface is ground with an 800-mesh diamond wheel and 3 mm x 4 mm x 40 m.
It is processed into the shape of m and the bending strength is obtained by room temperature three-point bending according to JIS R 1601.
SEPB method according to 1607 (Vickers indentation was added to the surface of the test piece of 3 × 40 mm to generate a pre-crack,
The fracture toughness value was determined by the method of fracture from this precrack. The results are also shown in Table 2.
【００３３】[0033]
【表２】 [Table 2]
【００３４】表２に示した結果より明らかなように、何
れの条件においても高強度かつ高靱性の窒化ケイ素質焼
結体が得られていることが認められた。As is clear from the results shown in Table 2, it was confirmed that a high-strength and high-toughness silicon nitride sintered body was obtained under any of the conditions.
【００３５】（比較例１）実施例２と同様の工程により
原料粉末を粉砕分級処理し、０．８μｍ以下の細粒と
０．８μｍ超過１．５μｍ未満のものと１．５μｍ以上
５．０μｍ以下の粗粒と５．０μｍ超過のものを得た。
そして、１０．０μｍ以上のものは廃却した。次いで、
前記粉末を混合することにより、０．８μｍ以下の細粒
と、０．８μｍ超過１．５μｍ未満のものと、１．５μ
ｍ以上５．０μｍ以下の粗粒と、５．０μｍ超過のもの
との割合が表３に示すものとなるように粒度調整を行っ
た。(Comparative Example 1) The raw material powder was pulverized and classified by the same steps as in Example 2, and fine particles of 0.8 µm or less, fine particles of 0.8 µm or more and less than 1.5 µm, and 1.5 µm or more and 5.0 µm or more were used. The following coarse particles and particles with a size exceeding 5.0 μm were obtained.
And the thing of 10.0 micrometers or more was abandoned. Then
By mixing the powders, fine particles of 0.8 μm or less, fine particles of more than 0.8 μm and less than 1.5 μm, and 1.5 μm
The particle size was adjusted so that the ratio of coarse particles of m or more and 5.0 μm or less and particles of more than 5.0 μm was as shown in Table 3.
【００３６】次いで、粒度調整した窒化ケイ素粉末に、
同じく表３に示す組成の焼結助剤を添加し、ボールミル
で２時間混合した。ついで、実施例２と同様の成形を行
った後、この成形体を同じく表３に示す焼成条件で焼成
することによって各焼結体を得た後、実施例２と同様の
評価を行った。これらの結果を同じく表３に示す。Next, the particle size-adjusted silicon nitride powder was added,
Similarly, a sintering aid having the composition shown in Table 3 was added and mixed by a ball mill for 2 hours. Then, after performing the same molding as in Example 2, each sintered body was obtained by firing the molded body under the firing conditions shown in Table 3 as well, and the same evaluation as in Example 2 was performed. The results are also shown in Table 3.
【００３７】[0037]
【表３】 [Table 3]
【００３８】表３に示した結果より明らかなように、
１．５μｍ以上５．０μｍ以下の粗粒を含まないＮｏ．
９では、密度が大であるものの曲げ強さおよび破壊靱性
値が低く、また、０．８μｍ以下の細粒の割合が少なす
ぎるＮｏ．１０，１１では、いずれも密度，曲げ強さお
よび破壊靱性値が低いものとなっていることが認められ
た。As is clear from the results shown in Table 3,
No. 1 containing no coarse particles of 1.5 μm or more and 5.0 μm or less.
No. 9 has a high density but a low bending strength and fracture toughness value, and the ratio of fine particles of 0.8 μm or less is too small. In Nos. 10 and 11, it was confirmed that the density, bending strength and fracture toughness were low.
【００３９】[0039]
【発明の効果】この発明に係わる窒化ケイ素質焼結体の
製造方法では、α型とβ型とを有する窒化ケイ素原料粉
末においてβ型を８０重量％以上含みかつ平均粒径が
２．０μｍ以上の窒化ケイ素原料粉末に粉砕分級処理を
施して、０．８μｍ以下の割合が７０重量％以上９５重
量％以下でかつ１．５μｍ以上５．０μｍ以下の割合が
５重量％以上３０重量％以下である粒度分布に制御し、
この窒化ケイ素原料粉末に焼結助剤を添加して成形した
後、窒素雰囲気下で焼成する構成としたから、安価な耐
火物グレードのβ型窒化ケイ素粉末を原料として用いた
ときでも、粉砕分級処理を施して特定の粒径のものを特
定量配合することによって、高純度粉末を出発原料とし
た窒化ケイ素質焼結体に劣らない優れた強度および靱性
を備えた窒化ケイ素質焼結体を得ることが可能であると
いう著しく優れた効果がもたらされる。In the method for producing a silicon nitride sintered body according to the present invention, the silicon nitride raw material powder having α type and β type contains β type in an amount of 80% by weight or more and has an average particle size of 2.0 μm or more. The silicon nitride raw material powder is subjected to pulverization and classification treatment so that the proportion of 0.8 μm or less is 70 wt% or more and 95 wt% or less and the proportion of 1.5 μm or more and 5.0 μm or less is 5 wt% or more and 30 wt% or less. Control to a certain particle size distribution,
This silicon nitride raw material powder is molded by adding a sintering aid and then fired in a nitrogen atmosphere, so even when an inexpensive refractory grade β-type silicon nitride powder is used as a raw material, pulverization and classification are performed. By processing and blending a specific amount of a specific particle size, a silicon nitride sintered body with excellent strength and toughness comparable to a silicon nitride sintered body using high purity powder as a starting material is obtained. It is possible to obtain a remarkably excellent effect.
【図１】この発明の実施例１において用いた粉砕分級処
理の概要を示す説明図である。FIG. 1 is an explanatory diagram showing an outline of a pulverizing / classifying process used in Example 1 of the present invention.
【図２】この発明の実施例２において用いた粉砕分級処
理の概要を示す説明図である。FIG. 2 is an explanatory diagram showing an outline of a pulverizing / classifying process used in Example 2 of the present invention.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 安 藤 元 英 神奈川県横浜市神奈川区宝町２番地 日産 自動車株式会社内 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Motohide Ando 2 Takara-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd.
Claims (3)
末においてβ型を８０重量％以上含みかつ平均粒径が
２．０μｍ以上の窒化ケイ素原料粉末に粉砕分級処理を
施して、０．８μｍ以下の割合が７０重量％以上９５重
量％以下でかつ１．５μｍ以上５．０μｍ以下の割合が
５重量％以上３０重量％以下である粒度分布に制御し、
この窒化ケイ素原料粉末に焼結助剤を添加して成形した
後、窒素雰囲気下で焼成することを特徴とする窒化ケイ
素質焼結体の製造方法。1. A silicon nitride raw material powder having α-type and β-type powders, which contains 80% by weight or more of β-type and has an average particle size of 2.0 μm or more, is ground and classified, The particle size distribution is controlled such that the proportion of 8 μm or less is 70% by weight or more and 95% by weight or less, and the proportion of 1.5 μm or more and 5.0 μm or less is 5% by weight or more and 30% by weight or less,
A method for producing a silicon nitride sintered body, comprising adding a sintering aid to the silicon nitride raw material powder and shaping the powder, followed by firing in a nitrogen atmosphere.
択される請求項１に記載の窒化ケイ素質焼結体の製造方
法。2. The method for producing a silicon nitride sintered body according to claim 1, wherein the sintering aid is selected from oxides and nitrides.
請求項１または２に記載の窒化ケイ素質焼結体の製造方
法。3. The method for producing a silicon nitride sintered body according to claim 1, wherein the firing temperature is 1600 to 2000 ° C.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3245868A JPH0753615B2 (en) | 1991-09-25 | 1991-09-25 | Method for manufacturing silicon nitride sintered body |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3245868A JPH0753615B2 (en) | 1991-09-25 | 1991-09-25 | Method for manufacturing silicon nitride sintered body |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH06166571A true JPH06166571A (en) | 1994-06-14 |
| JPH0753615B2 JPH0753615B2 (en) | 1995-06-07 |
Family
ID=17140013
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3245868A Expired - Fee Related JPH0753615B2 (en) | 1991-09-25 | 1991-09-25 | Method for manufacturing silicon nitride sintered body |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0753615B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20190032966A (en) * | 2017-09-20 | 2019-03-28 | 주식회사 엘지화학 | Tape casting slurry composition for manufacturing silicon nitride sintered body |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02255573A (en) * | 1989-03-29 | 1990-10-16 | Natl Inst For Res In Inorg Mater | Production of high-toughness silicon nitride sintered body |
-
1991
- 1991-09-25 JP JP3245868A patent/JPH0753615B2/en not_active Expired - Fee Related
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02255573A (en) * | 1989-03-29 | 1990-10-16 | Natl Inst For Res In Inorg Mater | Production of high-toughness silicon nitride sintered body |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20190032966A (en) * | 2017-09-20 | 2019-03-28 | 주식회사 엘지화학 | Tape casting slurry composition for manufacturing silicon nitride sintered body |
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| Publication number | Publication date |
|---|---|
| JPH0753615B2 (en) | 1995-06-07 |
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