JP2801447B2 - Method for producing silicon nitride based sintered body - Google Patents
Method for producing silicon nitride based sintered bodyInfo
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- JP2801447B2 JP2801447B2 JP3284474A JP28447491A JP2801447B2 JP 2801447 B2 JP2801447 B2 JP 2801447B2 JP 3284474 A JP3284474 A JP 3284474A JP 28447491 A JP28447491 A JP 28447491A JP 2801447 B2 JP2801447 B2 JP 2801447B2
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- silicon
- silicon nitride
- sintered body
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Description
【０００１】[0001]
【産業上の利用分野】本発明は、室温から高温までの強
度特性に優れ、特に、自動車用部品やガスタ−ビンエン
ジン用部品等に使用される窒化珪素質焼結体の製造方法
に関するもので詳細には、高い寸法精度が要求される部
品等の製造方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a silicon nitride sintered body having excellent strength characteristics from room temperature to a high temperature and particularly used for parts for automobiles and parts for gas turbine engines. More specifically, the present invention relates to a method for manufacturing a component or the like that requires high dimensional accuracy.
【０００２】[0002]
【従来の技術】従来から、窒化珪素質焼結体は、耐熱
性、耐熱衝撃性および耐酸化性に優れることからエンジ
ニアリングセラミックス、特にターボロータ等の熱機関
用として応用が進められている。2. Description of the Related Art Hitherto, silicon nitride sintered bodies have been applied to engineering ceramics, particularly for heat engines such as turbo rotors, because of their excellent heat resistance, thermal shock resistance and oxidation resistance.
【０００３】窒化珪素はそれ自体難焼結性であることが
知られているが、従来より高密度の焼結体を作製するた
めの焼結助剤として希土類元素酸化物や酸化アルミニウ
ムを添加することが特公昭５２−３６４９号、特公昭５
８−５１９０号にて提案されている。It is known that silicon nitride itself is difficult to sinter, but a rare earth element oxide or aluminum oxide is added as a sintering aid for producing a sintered body having a higher density than before. It is Japanese Patent Publication No. 52-3649, Japanese Patent Publication No. 5
No. 8-5190.
【０００４】また、最近では、窒化珪素質焼結体中にＮ
ｂ、Ｔａ、Ｔｉ、Ｗ等の金属の化合物を添加することに
より焼結体の強度や靱性を高める方法等が特開昭６４−
８７５６８号にて提案されている。Recently, silicon nitride based sintered bodies have
A method of increasing the strength and toughness of a sintered body by adding a compound of a metal such as b, Ta, Ti, W, etc.
No. 87568.
【０００５】[0005]
【発明が解決しようとする問題点】しかしながら、窒化
珪素源として窒化珪素粉末のみを用い、焼結助剤として
酸化イットリウム（Ｙ2 Ｏ3 ）と酸化アルミニウム（Ａ
ｌ2 Ｏ3 ）を用いた場合、その焼結性が高められ、高密
度化できることにより室温および高温における強度をあ
る程度は向上することができるが、実用的には未だ不十
分であり、さらに強度の改良が要求される。However, only silicon nitride powder is used as a silicon nitride source, and yttrium oxide (Y 2 O 3 ) and aluminum oxide (A) are used as sintering aids.
When l 2 O 3 ) is used, its sinterability is enhanced and its density can be increased, so that the strength at room temperature and high temperature can be improved to some extent, but it is still insufficient for practical use and Improvement is required.
【０００６】また、Ｙ2 Ｏ3 やＡｌ2 Ｏ3を焼結助剤と
して用いた系では、液相焼結が進行するに伴い焼成収縮
が生じるために、焼成後に高い寸法精度が要求され、形
状が複雑なタービンロータ等の製品を製造する場合に、
収縮が大きいと設定される寸法に制御することが難し
く、あるいは研磨工程が複雑になる等の問題がある。そ
こで、従来より出発原料として珪素粉末を添加し焼成前
に窒素中で珪素を窒化処理して成形体の密度を高める方
法が提案されているが、かかる方法に対する適正な組成
については検討されていない。Further, in a system using Y 2 O 3 or Al 2 O 3 as a sintering aid, firing shrinkage occurs as liquid phase sintering progresses, so that high dimensional accuracy is required after firing. When manufacturing products such as turbine rotors with complex shapes,
If the shrinkage is large, there is a problem that it is difficult to control the size to the set value, or the polishing process becomes complicated. Therefore, conventionally, a method has been proposed in which silicon powder is added as a starting material and silicon is subjected to nitriding treatment in nitrogen before firing to increase the density of the compact, but an appropriate composition for such a method has not been studied. .
【０００７】また、焼結体中にＴａ、Ｎｂ、Ｔｉ等を添
加する方法では、室温強度の向上を主たる目的とするも
ので、一般に室温で用いられる産業用構造材料として開
発されているのみで、高温特性についてはその検討がほ
とんどなされていない。Further, the method of adding Ta, Nb, Ti, etc. to the sintered body has a main purpose of improving the strength at room temperature, and is only developed as an industrial structural material generally used at room temperature. Very little consideration has been given to high-temperature characteristics.
【０００８】本発明の目的は、室温から高温まで自動車
用部品やガスタ−ビンエンジン用部品等で使用されるに
充分な強度特性、特に、室温から１０００℃の高温まで
の抗折強度に優れ、高い寸法精度が要求される部品等に
適用される窒化珪素質焼結体の製造方法を提供するにあ
る。An object of the present invention is to provide strength characteristics sufficient for use in automobile parts and gas turbine engine parts from room temperature to high temperatures, and in particular, excellent flexural strength from room temperature to high temperatures of 1000 ° C. It is an object of the present invention to provide a method for manufacturing a silicon nitride sintered body applied to parts or the like requiring high dimensional accuracy.
【０００９】[0009]
【問題点を解決するための手段】本発明者等は、高い寸
法精度を持ち、且つ焼結体の高温特性を高めるために
は、焼成時の収縮量を小さくし、且つ焼結体の組成およ
び焼結体中の窒化珪素結晶相の形状や、窒化珪素結晶相
の粒界に存在する副相を制御することが重要であるとい
う見地に基づき、検討を重ねた結果、珪素粉末、あるい
は珪素粉末と窒化珪素粉末を主体とし、これに希土類元
素酸化物、酸化アルミニウムならびに酸化珪素の各粉末
を添加した系に対して、さらに周期律表第５ａ族元素酸
化物粉末を添加し、これを成形後、成形体を８００℃〜
１５００℃の低温域で熱処理して珪素粉末を窒化させて
収縮を抑制しつつ、さらに１６００〜１９００℃の高温
域で焼成し、焼結体中に窒化珪素結晶相の粒界に珪素、
希土類元素、アルミニウム、酸素および窒素からから構
成される結晶質あるいは非晶質を生成せしめ、さらに周
期律表第５ａ族元素の酸窒化物からなる相を析出させる
ことによって優れた高温特性を有し、且つ高い寸法精度
を有する焼結体が得られることを知見した。Means for Solving the Problems In order to have high dimensional accuracy and to enhance the high-temperature characteristics of the sintered body, the present inventors have reduced the amount of shrinkage during firing and reduced the composition of the sintered body. As a result of repeated studies based on the viewpoint that it is important to control the shape of the silicon nitride crystal phase in the sintered body and the subphases present at the grain boundaries of the silicon nitride crystal phase, silicon powder or silicon Powder and silicon nitride powder as main components, and to the system obtained by adding each of rare earth element oxide, aluminum oxide and silicon oxide powders, further add Group 5a element oxide powder of the periodic table, and mold it. After that, the molded body is
While the silicon powder is nitrided by heat treatment at a low temperature range of 1500 ° C. to suppress shrinkage, it is further baked at a high temperature range of 1600 to 1900 ° C.
It has excellent high-temperature properties by producing crystalline or amorphous composed of rare earth elements, aluminum, oxygen and nitrogen, and further precipitating a phase composed of oxynitride of group 5a element of the periodic table. And that a sintered body having high dimensional accuracy can be obtained.
【００１０】以下、本発明を詳述する。本発明の窒化珪
素質焼結体の製造方法によれば、原料粉末として珪素粉
末、窒化珪素粉末、希土類元素酸化物粉末、酸化アルミ
ニウム粉末および周期律表第５ａ族元素酸化物粉末を用
い、場合によってはさらに酸化珪素粉末を用いる。Hereinafter, the present invention will be described in detail. According to the method for producing a silicon nitride-based sintered body of the present invention, silicon powder, silicon nitride powder, rare earth element oxide powder, aluminum oxide powder and Group 5a element oxide powder of the periodic table are used as raw material powders. In some cases, a silicon oxide powder is further used.
【００１１】用いる珪素粉末は、窒化を容易にするため
にその平均粒径が１０μｍ以下、特に３μｍ以下の微粒
のものが望ましい。また、窒化珪素粉末は、それ自体α
−Ｓｉ3 Ｎ4 、β−Ｓｉ3 Ｎ4 のいずれでも用いること
ができ、それらの粒径は０．４〜１．２μｍであること
が望ましい。The silicon powder used is desirably fine particles having an average particle size of 10 μm or less, particularly 3 μm or less, in order to facilitate nitriding. In addition, silicon nitride powder itself has α
-Si 3 N 4, can be used either in β-Si 3 N 4, it is desirable that their particle size is 0.4～1.2Myuemu.
【００１２】本発明によれば、これらの粉末を用いて窒
化珪素（Ｓｉ3Ｎ4 ）換算が６０乃至９３モル％、特に
６８乃至８５モル％、希土類元素酸化物（ＲＥ
2 Ｏ3 ）、酸化アルミニウム（Ａｌ2 Ｏ3 ）、過剰酸素
（ＳｉＯ2 換算量）の合量が6.０乃至３９．９モル％、
特に１4.２乃至３１．８モル％、周期律表第５ａ族元素
酸化物を０．１乃至１．０モル％、特に０．２乃至０．
８モル％になるように調製、混合する。この時の過剰酸
素（ＳｉＯ2 ）とは、珪素粉末と窒化珪素粉末に含まれ
る不純物酸素をＳｉＯ2 換算した量と添加する酸化珪素
粉末との合量である。According to the present invention, using these powders, the conversion of silicon nitride (Si 3 N 4 ) to 60 to 93 mol%, especially 68 to 85 mol%, rare earth oxide (RE
2 O 3 ), aluminum oxide (Al 2 O 3 ) and excess oxygen (SiO 2 equivalent) in a total amount of 6.0 to 39.9 mol%,
Particularly, 14.2 to 31.8 mol%, and 0.1 to 1.0 mol%, particularly 0.2 to 0.
Prepare and mix to 8 mol%. The excess oxygen (SiO 2 ) at this time is the sum of the amount of impurity oxygen contained in the silicon powder and the silicon nitride powder in terms of SiO 2 and the added silicon oxide powder.
【００１３】これは、希土類元素、アルミニウム、過剰
酸素の合量が6.０モル％より小さいと焼結過程で液相が
不足するために焼成温度を高くする必要があり、そのた
めに窒化珪素結晶粒子の成長が起こり強度の低下を引き
起こし、３９．９モル％より大きいと焼結体中の粒界相
が多くなり、高温強度が低下するとともにさらには高温
での耐酸化特性が劣化してしまうためで、周期律表第５
ａ族元素が０．１モル％より小さいと窒化珪素粒子の成
長が起こるために強度低下を引き起こし、１．０モル％
より大きいと窒化珪素粒子の針状化が抑制され、破壊靱
性が低下してしまうからである。If the total content of the rare earth element, aluminum and excess oxygen is less than 6.0 mol%, the liquid phase becomes insufficient during the sintering process, so that the firing temperature must be increased. Grain growth occurs, causing a decrease in strength. If it exceeds 39.9 mol%, the number of grain boundary phases in the sintered body increases, so that high-temperature strength decreases and oxidation resistance at high temperatures deteriorates. In the periodic table 5
If the element of group a is less than 0.1 mol%, the growth of silicon nitride particles occurs, causing a decrease in strength, and 1.0 mol%.
If it is larger, needle-like formation of the silicon nitride particles is suppressed, and the fracture toughness is reduced.
【００１４】本発明に用いられる希土類元素としてはＹ
やランタノイド系元素挙げられるが、これらの中でもＹ
ｂ2 Ｏ3 、Ｅｒ2 Ｏ3 、Ｈｏ2 Ｏ3 、Ｄｙ2 Ｏ3 が焼結
体の均一性および、強度の点から好ましい。The rare earth element used in the present invention is Y
And lanthanoid elements, among which Y
b 2 O 3 , Er 2 O 3 , Ho 2 O 3 , and Dy 2 O 3 are preferable in terms of uniformity and strength of the sintered body.
【００１５】また、周期律表第５ａ族元素としては、Ｎ
ｂ、Ｖ、Ｔａが挙げられるが、これらの中でもＮｂが最
も効果が大きい。In addition, as an element of Group 5a of the periodic table, N
Among them, b, V, and Ta are listed, and among these, Nb is the most effective.
【００１６】また、珪素粉末を多量に含む場合、後述す
る窒化工程において、添加された窒素粉末をすべて窒化
珪素に変換することが困難となり、逆に特性が低下する
ことがあるために、珪素粉末を適量含むことが望まし
い。When a large amount of silicon powder is contained, it is difficult to convert all of the added nitrogen powder into silicon nitride in the nitriding step described later, and conversely, the characteristics may be reduced. Is desirably contained in an appropriate amount.
【００１７】このようにして得られた混合粉末を公知の
成形方法、例えば、プレス成形、鋳込み成形、押出し成
形、射出成形、冷間静水圧成形などにより所望の形状に
成形する。The mixed powder thus obtained is formed into a desired shape by a known molding method, for example, press molding, cast molding, extrusion molding, injection molding, cold isostatic pressing and the like.
【００１８】次に、上記のようにして得られた成形体を
窒素含有雰囲気中で８００℃〜１５００℃の温度で熱処
理して成形体に含まれる珪素粉末を窒化し、窒化珪素を
生成させる。この窒化珪素への変換に際して、寸法変化
が無く重量増加するために成形体の密度が向上する。こ
の窒化処理後の成形体の対理論密度比が６０％以上とな
るように制御することが望ましい。この窒化処理におい
て、含有される珪素をすべて窒化させるためには、上記
温度範囲内にて、温度を多段に上昇させつつ徐々に窒化
させていくことが望ましく、一定温度での窒化処理では
珪素の完全な窒化ができない場合がある。また、この窒
化工程において系中に添加されている周期律表第５ａ族
元素酸化物も一部窒化されるために酸窒化物相が形成さ
れる。Next, the compact obtained as described above is heat-treated in a nitrogen-containing atmosphere at a temperature of 800 ° C. to 1500 ° C. to nitride the silicon powder contained in the compact to produce silicon nitride. During the conversion to silicon nitride, there is no dimensional change and the weight increases, so that the density of the molded body is improved. It is desirable to control the ratio of the theoretical density of the compact after the nitriding treatment to 60% or more. In this nitriding treatment, in order to nitride all of the contained silicon, it is desirable to gradually nitride while increasing the temperature in multiple steps within the above-mentioned temperature range. Complete nitriding may not be possible. In this nitriding step, the oxide of the element belonging to Group 5a of the periodic table added to the system is also partially nitrided, so that an oxynitride phase is formed.
【００１９】次に、得られた成形体を公知の焼成方法、
例えば、ホットプレス方法、常圧焼成、窒素ガス圧力焼
成、さらには、これらの焼成後のＨＩＰ焼成、および、
ガラスシ−ルＨＩＰ焼成等で焼成し、緻密な焼結体を得
る。この時の焼成温度は、高温しぎると窒化珪素結晶が
粒成長し強度が低下するため、１６００〜１９００℃、
特に１６５０〜１８００℃の窒素ガス含有非酸化性雰囲
気であることが望ましい。Next, the obtained molded body is fired by a known firing method,
For example, hot press method, normal pressure firing, nitrogen gas pressure firing, and further, HIP firing after firing, and
It is fired by glass seal HIP firing or the like to obtain a dense sintered body. The firing temperature at this time is 1600 to 1900 ° C., since if the temperature is too high, silicon nitride crystals grow and the strength decreases.
In particular, a non-oxidizing atmosphere containing nitrogen gas at 1650 to 1800 ° C. is desirable.
【００２０】この焼成によれば、添加成分のほとんどは
窒化珪素結晶相の粒界に存在するが、これらのうち周期
律表第５ａ族元素は酸窒化物相として残存し、その他の
添加物により珪素、窒素、酸素からなる結晶相と、珪
素、アルミニウム、希土類元素、酸素、窒素からなる粒
界相が形成されるが、条件によって珪素、窒素、酸素か
らなる結晶相が生成されない場合には、得られた焼結体
を１０００〜１５００℃の非酸化性雰囲気中で処理する
ことにより結晶相を生成することができる。According to this baking, most of the additional components are present at the grain boundaries of the silicon nitride crystal phase, but among them, the Group 5a element of the periodic table remains as an oxynitride phase, A crystal phase composed of silicon, nitrogen, and oxygen, and a grain boundary phase composed of silicon, aluminum, a rare earth element, oxygen, and nitrogen are formed, but when a crystal phase composed of silicon, nitrogen, and oxygen is not generated depending on conditions, A crystalline phase can be generated by treating the obtained sintered body in a non-oxidizing atmosphere at 1000 to 1500 ° C.
【００２１】[0021]
【作用】窒化珪素結晶粒子は適当なアスペクト比と大き
さをもち、高信頼性を得るためには異常成長粒子が存在
しない事が必要である。その為には、適当量の粒界相が
必要で、かつ従来の希土類元素酸化物と酸化アルミニウ
ムの添加だけではなく、ＳｉＯ2 を添加することで焼結
過程で生成する液相の融点が低下し、低温焼成が可能と
なり、窒化珪素粒子の成長を抑制でき、微細な組織を形
成することができる。The silicon nitride crystal grains have an appropriate aspect ratio and size, and in order to obtain high reliability, it is necessary that no abnormally grown grains exist. For that purpose, an appropriate amount of the grain boundary phase is necessary, and the melting point of the liquid phase generated in the sintering process is lowered by adding SiO 2 in addition to the conventional rare earth element oxide and aluminum oxide. In addition, low-temperature sintering becomes possible, growth of silicon nitride particles can be suppressed, and a fine structure can be formed.
【００２２】さらに、かかる方法によれば、焼成前の窒
化工程において周期律表第５ａ族元素酸窒化物が生成さ
れることにより、焼結過程で液相中に溶解することな
く、酸窒化物相として残存するために、この酸窒化物相
が窒化珪素粒子の成長を更に抑制し、微細でアスペクト
比の揃った均一な組織を形成することができ、これによ
り室温および高温における抗折強度を向上させることが
できる。Further, according to this method, the oxynitride of the Group 5a element of the periodic table is generated in the nitriding step before firing, so that the oxynitride does not dissolve in the liquid phase during the sintering process. This oxynitride phase further suppresses the growth of silicon nitride particles, and can form a fine and uniform structure with a uniform aspect ratio, thereby increasing the bending strength at room temperature and high temperature. Can be improved.
【００２３】さらに焼結体中に珪素、酸素、窒素からな
る結晶相を形成させることにより窒化珪素結晶相以外の
成分の高温安定化が図られ、これにより焼結体の室温お
よび高温における強度を高めるとともに靱性をも高める
ことができる。Further, by forming a crystal phase composed of silicon, oxygen, and nitrogen in the sintered body, the components other than the silicon nitride crystal phase are stabilized at a high temperature, thereby increasing the strength of the sintered body at room temperature and high temperature. As well as increasing the toughness.
【００２４】[0024]
実施例１ 原料粉末として平均粒径３μｍ、酸素量１．１重量％の
珪素粉末、窒化珪素粉末（ＢＥＴ比表面積８ｍ2 ／ｇ、
α率９８％、酸素量１．２重量％）と各種希土類元素酸
化物粉末、酸化珪素粉末、酸化アルミニウム粉末ならび
に周期律表第５ａ族元素酸化物粉末を用いて、表１に示
す組成なるように調合して混合後、鋳込み成形にてブレ
ードを成形した。得られた成形体を窒素中、１２００℃
で５時間、さらに１４００℃で１０時間窒化処理した。
この際、重量増加率からいずれの試料も添加された珪素
がすべて窒化されたことを確認した。Example 1 Silicon powder and silicon nitride powder having an average particle size of 3 μm and an oxygen content of 1.1% by weight (BET specific surface area 8 m 2 / g,
(α ratio 98%, oxygen content 1.2% by weight) and various rare earth element oxide powders, silicon oxide powders, aluminum oxide powders, and powders of the Group 5a element oxides of the Periodic Table. After mixing and mixing, a blade was formed by casting. The obtained molded body was placed in nitrogen at 1200 ° C.
For 5 hours and further at 1400 ° C. for 10 hours.
At this time, it was confirmed from the weight increase rate that all the added silicon was nitrided in all the samples.
【００２５】[0025]
【表１】 [Table 1]
【００２６】その後、得られた成形体を炭化珪素質の匣
鉢に入れて、カ−ボンヒ−タ−を用い、常圧にて窒素ガ
ス気流中１７５０℃で４時間焼成し、焼結体を得た。得
られた焼結体に対し、寸法を測定し、生成形体の寸法に
対する収縮率を測定した。また、ブレードを翼形状の測
定し設計値からの最大変形量を測定した。Thereafter, the obtained compact is placed in a silicon carbide sagger, and calcined at 1750 ° C. for 4 hours in a nitrogen gas stream at normal pressure using a carbon heater to obtain a sintered compact. Obtained. The dimensions of the obtained sintered body were measured, and the shrinkage ratios to the dimensions of the formed body were measured. Further, the blade shape of the blade was measured, and the maximum deformation amount from the design value was measured.
【００２７】得られた焼結体からＪＩＳ−Ｒ１６０１に
て指定される形状まで試験片を切り出し、研磨し試料を
作成した。この試料についてアルキメデス法に基づく比
重測定、窒化珪素結晶の平均結晶粒径（短径）およびそ
の平均アスペクト比を電子顕微鏡写真から測定し、ＪＩ
Ｓ−Ｒ１６０１に基づく室温および１０００℃での４点
曲げ抗折強度試験を実施し、さらに破壊靱性の測定を行
った。またＸ線回折測定により焼結体中の結晶を同定し
た。結果は表２に示した。A test piece was cut out from the obtained sintered body to a shape specified by JIS-R1601, and polished to prepare a sample. The specific gravity of this sample was measured based on the Archimedes method, the average crystal grain size (short diameter) of the silicon nitride crystal and the average aspect ratio thereof were measured from an electron micrograph.
A four-point bending strength test at room temperature and at 1000 ° C. based on SR1601 was performed, and the fracture toughness was measured. Further, crystals in the sintered body were identified by X-ray diffraction measurement. The results are shown in Table 2.
【００２８】[0028]
【表２】 [Table 2]
【００２９】表１および表２の結果によると、Ｓｉ3 Ｎ
4 換算量が６０モル％未満でＲＥ2 Ｏ3 、Ａｌ2 Ｏ3 、
ＳｉＯ2 の合量が３９．９モル％を越えるＮo,４の焼結
体は高温強度が低下しており、Ｓｉ3 Ｎ4 換算量が９３
モル％を越え、ＲＥ2 Ｏ3 、Ａｌ2 Ｏ3 、ＳｉＯ2 の合
量が６モル％未満のＮo,７の焼結体は緻密化不足で強度
も低下していた。また、第５ａ族元素が０．１モル％未
満のＮo,２０の焼結体は室温強度が低下し、第５ａ族元
素が１．０モル％を越えるＮo,１３の焼結体は破壊靱性
と室温強度が低下していた。また、原料として珪素粉末
を添加しなかったＮo,１の焼結体は、収縮率が１８％と
大きく、変形量が１００μｍを越えるものであった。According to the results shown in Tables 1 and 2, Si 3 N
4 When the conversion amount is less than 60 mol%, RE 2 O 3 , Al 2 O 3 ,
The sintered body of No.4, in which the total amount of SiO 2 exceeds 39.9 mol%, has a low high-temperature strength, and the equivalent amount of Si 3 N 4 is 93.
Exceed mol%, RE 2 O 3, Al 2 O 3, the total amount of SiO 2 is less than 6 mol% No, 7 sintered body strength was also decreased in insufficient densification. Further, the sintered body of No.20 containing less than 0.1 mol% of the group 5a element has reduced room temperature strength, and the sintered body of No.13 containing more than 1.0 mol% of the group 5a element has a fracture toughness. And the room temperature strength was reduced. The sintered body of No, 1 to which no silicon powder was added as a raw material had a large shrinkage of 18% and a deformation of more than 100 μm.
【００３０】これらの比較例に対し、本発明の焼結体は
いずれも優れた抗折強度、破壊靱性を示しており、収縮
率は１５％以下で変形量が１００μｍ以下と非常に寸法
精度に優れたものであった。In contrast to these comparative examples, all of the sintered bodies of the present invention show excellent transverse rupture strength and fracture toughness, with a shrinkage of 15% or less and a deformation of 100 μm or less, which is extremely dimensional accuracy. It was excellent.
【００３１】[0031]
【発明の効果】以上詳述した通り、本発明によれば、焼
結過程における収縮および変形を低減し、寸法精度の高
い焼結体を作製することができる。又、Ｓｉ3 Ｎ4 −Ｒ
Ｅ2 Ｏ3 −Ａｌ2 Ｏ3 −ＳｉＯ2 系に対して周期律表第
５ａ族元素酸化物を添加し、焼結体中に第５ａ族酸窒化
物からなる結晶相を析出させることにより、窒化珪素結
晶粒の粒成長を抑制するとともに、高温域での焼結助剤
等の添加物を安定化することができ、これにより室温か
ら高温において高い強度と靱性を得ることができる。As described above in detail, according to the present invention, shrinkage and deformation during the sintering process can be reduced, and a sintered body having high dimensional accuracy can be manufactured. Also, Si 3 N 4 -R
By adding a Group 5a element oxide of the periodic table to the E 2 O 3 —Al 2 O 3 —SiO 2 system, and precipitating a crystal phase consisting of a Group 5a oxynitride in the sintered body, In addition to suppressing the growth of silicon nitride crystal grains, it is possible to stabilize additives such as a sintering aid in a high-temperature region, thereby obtaining high strength and toughness from room temperature to high temperature.
【００３２】よって、ガスタービンやターボロータ等の
熱機関用構造材料をはじめとし、各種の室温や高温にて
使用される高い寸法精度が要求される構造用材料として
用いることができる。Therefore, it can be used as a structural material for a heat engine such as a gas turbine or a turbo rotor, or a structural material requiring high dimensional accuracy used at various room temperatures and high temperatures.
Claims (1)
末よりなる成分を窒化珪素換算で６０〜９３モル％と、
希土類元素酸化物、酸化アルミニウムおよび酸化珪素を
合量で６〜３９．９モル％と、周期律表第５ａ族元素酸
化物を０．１〜１．０モル％の割合で混合した混合物を
成形後、８００℃〜１５００℃の窒素含有雰囲気中で熱
処理をして、前記珪素を窒化した後、さらに窒素を含む
非酸化性雰囲気中で１６００〜１９００℃の温度で焼結
し、窒化珪素結晶相と、周期律表第５ａ族元素の酸窒化
物相と、珪素、酸素、窒素、希土類元素およびアルミニ
ウムから構成される粒界相を生成させることを特徴とす
る窒化珪素質焼結体の製造方法。1. A silicon powder or a component comprising a silicon powder and a silicon nitride powder in an amount of 60 to 93 mol% in terms of silicon nitride.
A mixture is formed by mixing a rare earth element oxide, aluminum oxide and silicon oxide in a total amount of 6 to 39.9 mol% and a group 5a element oxide of the periodic table at a ratio of 0.1 to 1.0 mol%. Thereafter, heat treatment is performed in a nitrogen-containing atmosphere at 800 ° C. to 1500 ° C. to nitride the silicon, and then sintering is performed at a temperature of 1600 to 1900 ° C. in a non-oxidizing atmosphere containing nitrogen to obtain a silicon nitride crystal phase. Producing an oxynitride phase of a Group 5a element of the periodic table and a grain boundary phase composed of silicon, oxygen, nitrogen, a rare earth element and aluminum. .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3284474A JP2801447B2 (en) | 1991-10-30 | 1991-10-30 | Method for producing silicon nitride based sintered body |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3284474A JP2801447B2 (en) | 1991-10-30 | 1991-10-30 | Method for producing silicon nitride based sintered body |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH05117033A JPH05117033A (en) | 1993-05-14 |
| JP2801447B2 true JP2801447B2 (en) | 1998-09-21 |
Family
ID=17678996
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3284474A Expired - Fee Related JP2801447B2 (en) | 1991-10-30 | 1991-10-30 | Method for producing silicon nitride based sintered body |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2801447B2 (en) |
-
1991
- 1991-10-30 JP JP3284474A patent/JP2801447B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH05117033A (en) | 1993-05-14 |
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