JP2692377B2 - Silicon nitride sintered body and method for producing the same - Google Patents
Silicon nitride sintered body and method for producing the sameInfo
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- JP2692377B2 JP2692377B2 JP2333625A JP33362590A JP2692377B2 JP 2692377 B2 JP2692377 B2 JP 2692377B2 JP 2333625 A JP2333625 A JP 2333625A JP 33362590 A JP33362590 A JP 33362590A JP 2692377 B2 JP2692377 B2 JP 2692377B2
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- silicon nitride
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Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は窒化珪素焼結体及びその製造方法に係る。TECHNICAL FIELD The present invention relates to a silicon nitride sintered body and a method for manufacturing the same.
窒化珪素は耐熱性構造材料として最も広く実用され、
また研究開発が進められている材料である。窒化珪素は
難焼結性であるので、Y2O3，Al2O3,MgOなどの焼結助剤
を添加し、1700〜1800℃で焼結される。Silicon nitride is the most widely used heat-resistant structural material,
It is also a material that is being researched and developed. Since silicon nitride is difficult to sinter, it is sintered at 1700 to 1800 ° C by adding a sintering aid such as Y 2 O 3 , Al 2 O 3 and MgO.
また、高強度化、緻密化のために、ホットプレスを使
用した焼結法、HIP（熱間等方加圧）を用いた焼結法
（特公昭62−13310号公報）あるいはガス圧焼結法（特
公昭62−41191号公報）なども採用される。In addition, for high strength and densification, a sintering method using a hot press, a sintering method using HIP (hot isostatic pressing) (Japanese Patent Publication No. 62-13310) or gas pressure sintering. The law (Japanese Patent Publication No. 62-41191) is also adopted.
ガスタービン1200〜1400℃の高温において羽根物ゆえ
に700MPa以上の高強度が要求されるが、従来の窒化珪素
焼結体ではこのような高温高強度は実現されることがで
きなかった。その理由は、緻密な焼結体を得るためには
焼結温度を上げるか、焼結助剤の量を多くする必要があ
るが、焼結温度を上げると粒成長のため強度が低下し、
かつ粒界相も厚くなるため高温強度が低下し、また焼結
助剤の量を多くすると粒界相が厚くなるので高温強度が
低下するものと考えられる。Gas turbines require high strength of 700 MPa or higher due to the blades at high temperatures of 1200 to 1400 ° C, but such high temperature and high strength could not be realized with conventional silicon nitride sintered bodies. The reason is that in order to obtain a dense sintered body, it is necessary to raise the sintering temperature or increase the amount of the sintering aid, but when the sintering temperature is raised, the strength decreases due to grain growth,
Moreover, it is considered that the high temperature strength is lowered because the grain boundary phase is also thick, and that the high temperature strength is lowered when the amount of the sintering aid is increased because the grain boundary phase is thickened.
そこで、本発明は、1200〜1400℃の高温で700MPa以上
の如く高強度を発現する窒化珪素焼結体及びその製造方
法を提供することを目的とする。Therefore, an object of the present invention is to provide a silicon nitride sintered body that exhibits a high strength of 700 MPa or more at a high temperature of 1200 to 1400 ° C. and a method for manufacturing the same.
上記目的を達成するために、本発明は、窒化珪素に対
してY2O3，Yb2O3，Sc2O3のうち１種以上を３〜６重量％
とMgAl2O4を0.01〜0.03重量含み、粒状晶に観察される
組織とその中に分散して存在する柱状晶に観察される組
織からなり、柱状晶の平均径及び柱状晶の平均短径が0.
2〜0.6μｍであり、かつ密度が理論密度の99％以上であ
ることを特徴とする窒化珪素焼結体、及び焼結助剤とし
てY2O3，Yb2O3，Sc2O3のうちの１種以上を３〜６重量％
と、MgAl2O4を0.01〜0.03重量％とを添加した窒化珪素
との均一混合粉末を成形し、該成形体を1530〜1650℃の
範囲内の温度まで加熱して予備焼結し、次いで該温度範
囲内の温度で圧力を1500気圧以上まで昇圧して本焼結す
ることを特徴とする窒化珪素焼結体の製造方法を提供す
る。In order to achieve the above object, the present invention provides 3 to 6% by weight of at least one of Y 2 O 3 , Yb 2 O 3 , and Sc 2 O 3 with respect to silicon nitride.
And MgAl 2 O 4 in 0.01 to 0.03 weight, consisting of the structure observed in granular crystals and the structure observed in columnar crystals dispersed therein, the average diameter of the columnar crystals and the average minor axis of the columnar crystals. Is 0.
2 to 0.6 μm, and the density is 99% or more of the theoretical density, and a silicon nitride sintered body, and Y 2 O 3 , Yb 2 O 3 , and Sc 2 O 3 as a sintering aid. 3-6% by weight of one or more of them
And a uniform mixed powder of silicon nitride added with 0.01 to 0.03 wt% of MgAl 2 O 4 and heating the compact to a temperature in the range of 1530 to 1650 ° C. to presinter, and then Provided is a method for manufacturing a silicon nitride sintered body, which comprises subjecting a pressure to 1500 atm or more at a temperature within the temperature range to perform main sintering.
出発原料としての窒化珪素及び焼結助剤は、粒径0.6
μｍ以下、より好ましくは0.1〜0.4μｍのものを使用す
る。出発原料の粒径が大きくなると、焼結粒子の粒径が
大きくなり、強度低下の原因になるからである。また、
純度はSi3N4で金属不純物総量100ppm以下、焼結助剤で9
9.9％以上のものを使用する。不純物がこれより多くな
ると流界相の耐酸化性が低下して1400℃強度が低下す
る。Silicon nitride as a starting material and a sintering aid have a particle size of 0.6.
The thickness is not more than μm, more preferably 0.1 to 0.4 μm. This is because when the particle size of the starting material becomes large, the particle size of the sintered particles also becomes large, which causes a decrease in strength. Also,
The purity is Si 3 N 4 and the total amount of metal impurities is 100ppm or less.
Use at least 9.9%. If the amount of impurities is larger than this, the oxidation resistance of the flow field phase decreases and the 1400 ° C strength decreases.
焼結助剤としてはY2O3，Yb2O3，Sc2O3のうち１種以上
を３〜６重量％と、MgAl2O4を0.01〜0.03重量％添加す
る。Y2O3，Yb2O3とMgAl2O4との組合せは公知であるが、
本発明ではMgAl2O4の添加量を0.01〜0.03重量％の範囲
内として、従来より極めて少ない量で使用する。Y2O3，
Yb2O3，Sc2O3の量は上記より少なくても多くても緻密に
焼結しない。また、MgAl2O4の量は0.01重量％より少な
いと緻密に焼結せず、一方0.03重量％より多くなると14
00℃強度が低下する。MgAl2O4の添加量が増えると粒界
の耐酸化性が低下して高温強度が低下するものと考えら
れる。As a sintering aid, 3 to 6 wt% of one or more of Y 2 O 3 , Yb 2 O 3 and Sc 2 O 3 and 0.01 to 0.03 wt% of MgAl 2 O 4 are added. The combination of Y 2 O 3 , Yb 2 O 3 and MgAl 2 O 4 is known,
In the present invention, the addition amount of MgAl 2 O 4 is set within the range of 0.01 to 0.03% by weight, and it is used in a much smaller amount than before. Y 2 O 3 ,
Even if the amounts of Yb 2 O 3 and Sc 2 O 3 are smaller or larger than those mentioned above, they do not sinter densely. Also, if the amount of MgAl 2 O 4 is less than 0.01% by weight, it does not sinter densely, while if it is more than 0.03% by weight, 14
00 ℃ Strength decreases. It is considered that when the addition amount of MgAl 2 O 4 increases, the oxidation resistance of the grain boundaries decreases and the high temperature strength decreases.
出発粉末の成形は常法により行なうことができる。す
なわち、典型的には、均一混合粉末を加圧成形する。Molding of the starting powder can be carried out by a conventional method. That is, typically, the uniformly mixed powder is pressure-molded.
次いで、焼成するが、本発明では焼成温度を1530〜16
50℃の範囲内として、従来の常圧焼結温度1700〜1800
℃、あるいはHIP焼結温度1700〜1900℃より低い焼結温
度を採用することを特徴としている。すなわち、従来
は、常圧焼結温度として1700〜1800℃が採用されるが、
この温度では焼結体が充分に緻密化せず、理論密度の99
％に達する高密度の焼結体を得ることはできなかった。
そこで、より高温で充分に焼結させるために、Si3N4の
熱分解を抑制すべく高圧をかけて焼成する方法（HIP）
が利用されている。このようなHIP法によれば焼結が進
み、理論密度の99％以上の高密度の焼結体を得ることも
可能である。しかしながら、高温で焼結されるため、粒
径も成長し、強度が所望の様に向上しないという問題が
あった。Then, it is fired, but in the present invention, the firing temperature is 1530 to 16
Within the range of 50 ° C, the conventional atmospheric pressure sintering temperature is 1700-1800
It is characterized by adopting a sintering temperature lower than ℃ or HIP sintering temperature 1700 ~ 1900 ℃. That is, conventionally, 1700 to 1800 ° C. is adopted as the atmospheric pressure sintering temperature,
At this temperature, the sintered body does not fully densify and the theoretical density of 99
%, It was not possible to obtain a high density sintered body.
Therefore, in order to sufficiently sinter at higher temperature, a method of firing under high pressure to suppress thermal decomposition of Si 3 N 4 (HIP)
Is used. According to such a HIP method, sintering progresses, and it is possible to obtain a high density sintered body of 99% or more of the theoretical density. However, since it is sintered at a high temperature, there is a problem that the grain size grows and the strength is not improved as desired.
これに対して、本発明は、驚くことに、1500気圧以上
の高圧を利用する場合には、従来Si3N4が焼結しないと
考えられていた1530〜1650℃の低い温度でも焼結が進行
し、理論密度の99％以上、さらには99.5％以上の高密度
のSi3N4焼結体を得ることができること、またこのよう
に低温高圧下で焼結した場合には粒成長が抑えられるた
め1200〜1400℃で700MPa以上という高温高強度の発現も
可能になるということを発見して為されたものである。
従来より、窒化珪素の一般的焼結温度として1600℃以上
であることが言及されることはあったが、実際に1600℃
でSi3N4焼結体を作製した例はなく、仮に1600℃で焼結
されたとしても、得られる焼結体の密度は極めて低いも
のとならざるを得ないことが、当業者の常識である。ま
た、前述の如く、HIP法を採用する理由は、より高温で
あるいはより長時間焼結してより緻密な焼結体を得るた
めにSi3N4及び酸化物助剤の熱分解を防止することにあ
るから、HIP処理を採用しながら、なおかつ焼成温度を1
700℃より低くようということは、当業者の常識では考
えられないことであった。本発明者は、あえてこれを行
ない、上記の如く驚くべき知見を得て、本発明に到達し
たものである。In contrast, the present invention Surprisingly, when using a high pressure more than 1500 atm, sintering even at a low temperature of a conventional Si 3 N 4 1530~1650 was considered not to sinter ℃ It is possible to obtain a high density Si 3 N 4 sintered body of 99% or more of the theoretical density, further 99.5% or more, and grain growth is suppressed when sintered at low temperature and high pressure. Therefore, it was made by discovering that high temperature and high strength of 700 MPa or more at 1200 to 1400 ° C can be realized.
Conventionally, it has been mentioned that the general sintering temperature of silicon nitride is 1600 ° C or higher, but it is actually 1600 ° C.
There is no example of producing a Si 3 N 4 sintered body with, and even if it is sintered at 1600 ° C., the density of the obtained sintered body must be extremely low. Is. Further, as described above, the reason for adopting the HIP method is to prevent thermal decomposition of Si 3 N 4 and the oxide auxiliary agent in order to obtain a denser sintered body by sintering at a higher temperature or for a longer time. Therefore, while using the HIP process, the firing temperature is set to 1
Trying to lower the temperature below 700 ° C was unthinkable in the common sense of those skilled in the art. The inventor of the present invention has intentionally performed this, and obtained the surprising knowledge as described above, and arrived at the present invention.
そこで、本発明では、1530〜1650℃、特に1600℃未満
の温度で焼成することを特徴としているが、直ちに高圧
にすると焼結体内の気孔の圧力も高くなって、緻密化し
ないので、最初に低圧下で予備焼結させる。予備焼結の
圧力はSi3N4が熱分解しない限り、低い圧力が望ましい
が、減圧下ではSi3N4が熱分解し易いので、一般的には
１気圧N2雰囲気で行なう。ただし、この予備焼結もHIP
装置内で行なうことが都合がよい関係上、実際の圧力は
１〜30気圧位になるであろう。要は、本焼結の1500気圧
以上に対して低い圧力、常圧付近であればよい。Therefore, the present invention is characterized in that it is fired at a temperature of 1530 to 1650 ° C., particularly below 1600 ° C., but when the pressure is immediately made high, the pressure of the pores in the sintered body also increases, so that it does not become densified. Pre-sinter under low pressure. Unless the pressure of the pre-sintering of Si 3 N 4 is not thermally decomposed, but lower pressure is desired, because it is easy Si 3 N 4 is thermally decomposed under reduced pressure, generally carried out at 1 atm N 2 atmosphere. However, this preliminary sintering is also HIP
Actual pressures will be in the order of 1 to 30 atmospheres, as is convenient to do in the equipment. The point is that the pressure should be lower than 1500 atm for main sintering, or near normal pressure.
典型的には、予備焼結は、１気圧付近のN2雰囲気下、
0.5〜10℃／分程度の昇温速度で1530〜1650℃の範囲内
の温度まで昇温して行なう。昇温プロファイルは所望に
変更できる。予備焼結の終点の一応のめどは理論密度の
90％程度の密度である。Typically, pre-sintering is performed in a N 2 atmosphere near 1 atmosphere,
The temperature is raised within the range of 1530 to 1650 ° C at a heating rate of about 0.5 to 10 ° C / min. The heating profile can be changed as desired. Prima facie prospect of the end of the preliminary sintering of the theoretical density
The density is about 90%.
1530〜1650℃の範囲内の温度に到達したら、次に圧力
を５〜30気圧／分程度の昇圧速度で1500気圧以上まで昇
圧し、その圧力に保持して本焼結を行なう。本焼結の圧
力は1500気圧以上、典型的には1500〜2500気圧である。
1500気圧未満では焼結体の1400℃強度が低下するからで
ある。高圧側は装置の問題がなければ、特に上限はな
い。When the temperature within the range of 1530 to 1650 ° C. is reached, the pressure is increased to 1500 atm or more at a pressure increasing rate of about 5 to 30 atm / min, and the main sintering is performed while maintaining the pressure. The pressure of the main sintering is 1500 atm or higher, typically 1500 to 2500 atm.
This is because if the pressure is less than 1500 atm, the strength of the sintered body decreases at 1400 ° C. There is no upper limit on the high-pressure side unless there is a problem with the device.
こうして、本発明の方法により低温高圧焼結された窒
化珪素焼結体は、Si3N4結晶粒の粒成長を抑制したまま
で緻密に焼結し、理論密度の99％以上、さらには99.5％
以上の高密度で、かつ1400℃での４点曲げ強度が700MPa
以上のガスタービンに必要な高温高強度を発現する。本
発明者は、従来、99％以上の相対密度で700MPa以上（於
1400℃）の強度を実現した窒化珪素焼結体を知らない。Thus, the silicon nitride sintered body sintered at low temperature and high pressure by the method of the present invention is densely sintered while suppressing the grain growth of Si 3 N 4 crystal grains, and has a theoretical density of 99% or more, further 99.5% or more. %
The above high density and the 4-point bending strength at 1400 ℃ is 700MPa.
The high temperature and high strength required for the above gas turbines are exhibited. The inventor of the present invention has conventionally used a relative density of 99% or higher (at
I do not know the silicon nitride sintered body that realized the strength of 1400 ℃.
なお、本発明の方法により得られる窒化珪素焼結体中
の窒化珪素粒子は、一般的な粒状晶に観察される組織と
その中に分散して存在する柱状晶に観察される組織とか
らなるが、粒状晶の平均径及び柱状晶の平均短径はいず
れも0.2〜0.6μｍ、さらには0.2〜0.4μｍ、柱状晶の平
均長径は１〜４μｍ、さらには１〜３μｍであり、これ
は従来法（HIP）による焼結体の場合のほぼ1/3の大きさ
である。このように結晶粒径が小さいことにより、高温
強度を低下させる粒界相が薄めて薄くなり、Si3N4粒子
同士がよく結合し、特に粒界３重点が小さくなっている
ことが観察されたので、このために高温強度が改善され
るものと考えられる。The silicon nitride particles in the silicon nitride sintered body obtained by the method of the present invention are composed of a structure observed in general granular crystals and a structure observed in columnar crystals dispersed therein. However, the average diameter of the granular crystals and the average short diameter of the columnar crystals are both 0.2 to 0.6 μm, further 0.2 to 0.4 μm, and the average long diameter of the columnar crystals is 1 to 4 μm, and further 1 to 3 μm. It is almost 1/3 the size of the sintered body by the HIP method. It is observed that the small grain size results in thinning and thinning of the grain boundary phase that lowers the high temperature strength, the Si 3 N 4 grains are well bonded to each other, and the grain boundary triple point is particularly small. Therefore, it is considered that this improves the high temperature strength.
1500気圧以上の高圧をかけることにより1650℃以下の
低い温度でSi3N4を緻密に焼結することができ、粒成長
を抑制し、粒界相の厚さを薄くでき、かつ焼結助剤のMg
Al2O4の添加量を極微少量にしたことによっても粒界相
の耐酸化性が向上し、その結果、高密度、高温高強度、
高硬度の焼結体が得られる。By applying a high pressure of 1500 atm or more, Si 3 N 4 can be densely sintered at a low temperature of 1650 ° C or less, grain growth can be suppressed, grain boundary phase thickness can be made thin, and sintering aid can be achieved. Agent Mg
The oxidation resistance of the grain boundary phase is also improved by making the addition amount of Al 2 O 4 extremely small, resulting in high density, high temperature and high strength,
A high-hardness sintered body can be obtained.
Si3N4粉末（平均粒径0.2μｍ、金属不純物総量30pp
m、α化率ほぼ100％）に焼結助剤としてY2O3粉末（平均
粒径0.3μｍ、純度99.9％）、Yb2O3粉末（平均粒径0.1
μｍ、純度99.9％）又はSc2O3粉末（平均粒径0.6μｍ、
純度99.9％）及びMgAl2O4粉末（平均粒径0.3μｍ、純度
99.9％）の添加量を第１表に示すような組成で混合（Si
3N4製ボールミル）した各種粉末を200kgf/cm2の圧力で
加圧成形し、その成形体を薄ゴムにつめ真空封入後CIP
にて3000kgf/cm2の圧力で加圧した。次いで、この成形
体を第１表に示す条件でN2雰囲気中の炉内で焼結させ
た。昇温速度は５℃/min、最高温度に到達するまでは１
気圧のN2雰囲気下で、最高温度到達後に第１表に示す条
件まで毎分15気圧の昇温速度で加圧した。また、最高温
度での保持時間は４時間とした。なお、焼成の温度、圧
力プロファイルを第１図に示す。Si 3 N 4 powder (average particle size 0.2μm, total metal impurities 30pp
m, α conversion rate of almost 100%) Y 2 O 3 powder (average particle size 0.3 μm, purity 99.9%), Yb 2 O 3 powder (average particle size 0.1)
μm, purity 99.9%) or Sc 2 O 3 powder (average particle size 0.6 μm,
Purity 99.9%) and MgAl 2 O 4 powder (average particle size 0.3μm, purity
99.9%) with the composition as shown in Table 1 (Si
3 N 4 ball mill) various pressure-molded powders at a pressure of 200 kgf / cm 2 , the molded body is packed in thin rubber, and vacuum filled, then CIP
It was pressurized at a pressure of 3000 kgf / cm 2 . Next, this compact was sintered in a furnace in an N 2 atmosphere under the conditions shown in Table 1. The rate of temperature rise is 5 ° C / min, 1 until the maximum temperature is reached.
In a N 2 atmosphere at atmospheric pressure, after reaching the maximum temperature, pressurization was performed at a heating rate of 15 atm per minute until the conditions shown in Table 1 were reached. The holding time at the maximum temperature was 4 hours. The firing temperature and pressure profile are shown in FIG.
これらの焼結体の室温４点曲げ強度（JIS R 1601）、
高温４点曲げ強度（JIS R 1604、大気中）を測定して第
１表に示す結果を得た。焼結体の相対密度はｎ−ブタノ
ール置換法で求めた嵩密度を理論密度で除して得た値で
ある。残部は気孔率であるが、光学顕微鏡による鏡面研
磨面の観察結果からも裏付けられた。Room temperature 4-point bending strength of these sintered bodies (JIS R 1601),
High temperature 4-point bending strength (JIS R 1604, in air) was measured and the results shown in Table 1 were obtained. The relative density of the sintered body is a value obtained by dividing the bulk density obtained by the n-butanol substitution method by the theoretical density. The rest is porosity, which was confirmed by the observation result of the mirror-polished surface with an optical microscope.
比較のために、実施例と同様な方法で成形したのち、
この成形体を第２表に示す条件でN2雰囲気の炉内で焼結
させ、第２表の結果を得た。For comparison, after molding in the same manner as in the example,
This compact was sintered in a N 2 atmosphere furnace under the conditions shown in Table 2, and the results shown in Table 2 were obtained.
実施例の試料No.1及び比較例試料No.22の焼結体組織
をTEMにて詳細に観察した結果、本発明の製造方法によ
りNo.1のβ−Si3N4の粒子径はNo.22のそれに比較して1/
3の大きさになっており、さらにNo.1はβ−Si3N4粒子が
より一層緻密に充填され、粒界相の幅が非常に狭くSi3N
4粒子同士がよく結合しており、特に粒界３重点が小さ
くなっていることが観察できた。その結果、高温曲げ強
度が改善されたものと考えられる。なお、試料No.1の粒
状晶の平均粒径は0.2μｍ、柱状晶の長径の平均は２μ
ｍ、短径の平均は0.3μｍであった。 As a result of observing the sintered body structures of the sample No. 1 of the example and the comparative sample No. 22 in detail with a TEM, the particle diameter of β-Si 3 N 4 of No. 1 by the manufacturing method of the present invention is No. 1/2 compared to that of .22
3 and is sized, further No.1 is more densely packed with beta-Si 3 N 4 particles, very width of the grain boundary phase narrowed Si 3 N
It was observed that the four grains were well bonded to each other, and especially the triple point of the grain boundary was small. As a result, it is considered that the high temperature bending strength was improved. The average grain size of the granular crystals of sample No. 1 was 0.2 μm, and the average major axis of columnar crystals was 2 μm.
The average of m and the minor axis was 0.3 μm.
また、実施例及び比較例において、酸化反応速度定数
を、直径20×厚さ1mm、表面粗度RMAX0.8μｍ以下の試料
を乾燥空気中で100Hまで試料の増量を測定して求めた。
結果を次に示す。In addition, in Examples and Comparative Examples, the oxidation reaction rate constant was determined by measuring the increase of the sample having a diameter of 20 × the thickness of 1 mm and the surface roughness R MAX of 0.8 μm or less up to 100 H in dry air.
The results are shown below.
実施例試料No.1 1400℃の酸化反応速度定数3.5×10
-7mg2cm-4sec-1 比較例試料No.22 1400℃の酸化反応速度定数4.5×10-6
mg2cm-4sec-1 この酸化反応速度定数より、本発明による焼結体は耐
酸化性が向上しているのが認められる。これは粒界相の
幅が極めて狭くなり、Si3N4粒子同士がよく結合したこ
とに起因すると思われる。Example Sample No. 1 1400 ° C. oxidation reaction rate constant 3.5 × 10
-7 mg 2 cm -4 sec -1 Comparative example Sample No.22 Oxidation rate constant at 1400 ℃ 4.5 × 10 -6
mg 2 cm -4 sec -1 From this oxidation reaction rate constant, it is recognized that the sintered body according to the present invention has improved oxidation resistance. This is probably because the width of the grain boundary phase became extremely narrow and the Si 3 N 4 grains were well bonded to each other.
本発明によれば、理論密度の99％以上の高密度でかつ
1400℃強度が700MPa以上で、ガスタービン等に好適の窒
化珪素焼結体が得られる。According to the present invention, a high density of 99% or more of the theoretical density and
With a strength of 1400 ° C. and 700 MPa or more, a silicon nitride sintered body suitable for a gas turbine or the like can be obtained.
第１図は実施例の焼成の温度、圧力プロファイルを示す
図である。FIG. 1 is a diagram showing a temperature and pressure profile of firing in the example.
Claims (2)
ち１種以上を３〜６重量％とMgAl2O4を0.01〜0.03重量
％含み、粒状晶に観察される組織とその中に分散して存
在する柱状晶に観察される組織からなり、柱状晶の平均
径及び柱状晶の平均短径が0.2〜0.6μｍであり、かつ密
度が理論密度の99％以上であることを特徴とする窒化珪
素焼結体。1. A granular crystal containing 3 to 6% by weight of at least one of Y 2 O 3 , Yb 2 O 3 and Sc 2 O 3 and 0.01 to 0.03% by weight of MgAl 2 O 4 with respect to silicon nitride. And the average diameter of the columnar crystals and the average minor axis of the columnar crystals are 0.2 to 0.6 μm, and the density is equal to the theoretical density. A silicon nitride sintered body characterized by being 99% or more.
の１種以上を３〜６重量％と、MgAl2O4を0.01〜0.03重
量％とを添加した窒化珪素との均一混合粉末を成形し、 該成形体を1530〜1650℃の範囲内の温度まで加熱して予
備焼結し、次いで該温度範囲内の温度で圧力を1500気圧
以上まで昇圧して本焼結することを特徴とする窒化珪素
焼結体の製造方法。2. A sintering aid comprising 3 to 6% by weight of at least one of Y 2 O 3 , Yb 2 O 3 and Sc 2 O 3 and 0.01 to 0.03% by weight of MgAl 2 O 4. A uniform mixed powder with the added silicon nitride is molded, the molded body is heated to a temperature in the range of 1530 to 1650 ° C for pre-sintering, and then the pressure is increased to 1500 atm or more at a temperature in the temperature range. A method for manufacturing a silicon nitride sintered body, comprising:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2333625A JP2692377B2 (en) | 1990-11-30 | 1990-11-30 | Silicon nitride sintered body and method for producing the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2333625A JP2692377B2 (en) | 1990-11-30 | 1990-11-30 | Silicon nitride sintered body and method for producing the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH04202060A JPH04202060A (en) | 1992-07-22 |
| JP2692377B2 true JP2692377B2 (en) | 1997-12-17 |
Family
ID=18268146
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2333625A Expired - Fee Related JP2692377B2 (en) | 1990-11-30 | 1990-11-30 | Silicon nitride sintered body and method for producing the same |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2692377B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0987037A (en) * | 1995-07-18 | 1997-03-31 | Ngk Spark Plug Co Ltd | Silicon nitride-base sintered compact and its production |
-
1990
- 1990-11-30 JP JP2333625A patent/JP2692377B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH04202060A (en) | 1992-07-22 |
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