JPS6146431B2 - - Google Patents
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- Publication number
- JPS6146431B2 JPS6146431B2 JP55180739A JP18073980A JPS6146431B2 JP S6146431 B2 JPS6146431 B2 JP S6146431B2 JP 55180739 A JP55180739 A JP 55180739A JP 18073980 A JP18073980 A JP 18073980A JP S6146431 B2 JPS6146431 B2 JP S6146431B2
- Authority
- JP
- Japan
- Prior art keywords
- sintering
- sintered body
- temperature
- relative density
- primary
- 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.)
- Expired
Links
- 238000005245 sintering Methods 0.000 claims description 81
- 239000007789 gas Substances 0.000 claims description 29
- 238000000034 method Methods 0.000 claims description 29
- 239000000843 powder Substances 0.000 claims description 21
- 239000012298 atmosphere Substances 0.000 claims description 19
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 12
- 229910052581 Si3N4 Inorganic materials 0.000 claims description 11
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims description 9
- 229910001873 dinitrogen Inorganic materials 0.000 claims description 4
- 229910052757 nitrogen Inorganic materials 0.000 claims description 4
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 3
- 239000011812 mixed powder Substances 0.000 claims description 2
- 150000004767 nitrides Chemical class 0.000 claims 1
- 239000011148 porous material Substances 0.000 description 13
- 238000000354 decomposition reaction Methods 0.000 description 9
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 6
- 239000000919 ceramic Substances 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 239000007791 liquid phase Substances 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 229910052593 corundum Inorganic materials 0.000 description 2
- 238000000465 moulding Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 229910001845 yogo sapphire Inorganic materials 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 229910010293 ceramic material Inorganic materials 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000009770 conventional sintering Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000000280 densification Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000001513 hot isostatic pressing Methods 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 238000001746 injection moulding Methods 0.000 description 1
- 239000012212 insulator Substances 0.000 description 1
- 238000000462 isostatic pressing Methods 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 239000012299 nitrogen atmosphere Substances 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000012071 phase Substances 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 229920002379 silicone rubber Polymers 0.000 description 1
- 239000004945 silicone rubber Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000005979 thermal decomposition reaction Methods 0.000 description 1
Description
【発明の詳細な説明】
本発明は相対密度98％以上の高密度窒化珪素焼
結体を容易に製造することができる窒化珪素の焼
結方法に関するものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for sintering silicon nitride that can easily produce a high-density silicon nitride sintered body having a relative density of 98% or more.
近年、Si3N4を主体とするセラミツクス材料
は、熱衝撃性、高温強度に優れているため、耐熱
エンジニアリング材料として注目を浴びている
外、耐摩耗性にも優れているため、メカニカルシ
ールの摺動部材や、工具など幅広い分野での用途
が期待されている。しかしながら、Si3N4セラミ
ツクスも他のセラミツクス例えばアルミナなどと
同様、極めて脆いという欠点を有している。この
ようなセラミツクスの脆さは、それ自体が共有結
合結晶から成つていることのほかに、その製造プ
ロセス上、内部特に結晶粒界に空孔が不可避的に
含まれ、その空孔を起点として脆性破壊するから
である。 In recent years, ceramic materials mainly composed of Si 3 N 4 have been attracting attention as heat-resistant engineering materials due to their excellent thermal shock resistance and high-temperature strength. It is expected to be used in a wide range of fields such as sliding parts and tools. However, like other ceramics such as alumina, Si 3 N 4 ceramics also have the disadvantage of being extremely brittle. The reason for the brittleness of ceramics is not only that they are made of covalently bonded crystals, but also that due to the manufacturing process, they inevitably contain vacancies, especially at grain boundaries. This is because it causes brittle fracture.
さらに、これら空孔の大きさ、数、位置的に分
布が製造条件、部材の形状によつて異なるため、
極めて信頼性が低いものとされている。従つて、
これら空孔のない材料が得られるならば、セラミ
ツクスの用途は非常に広範なものとなり得る。 Furthermore, the size, number, and positional distribution of these pores vary depending on manufacturing conditions and the shape of the member.
It is considered extremely unreliable. Therefore,
If materials without these pores could be obtained, the applications of ceramics could be very wide-ranging.
すでにアルミナなどでは、切削工具のスローア
ウエイチツプやナトリウムの透光性碍管など小形
の部品に、極めて空孔の少ない材料と製造プロセ
スが開発されている。 Already, materials and manufacturing processes with extremely few pores have been developed for small parts such as alumina, such as throw-away tips for cutting tools and transparent sodium insulator tubes.
しかしながら、Si3N4系では、Si3N4がアルミナ
などと異なつて昇華性であること、即ち極めて高
温にあげても液相を生じないため、通常の手法で
若干の液相を生じさせて焼結を進めることは困難
でこれを行なうには、液相を生じさせるような添
加物（焼結助剤）を５〜20％と多量に用いなけれ
ばならない。この場合、当然のことながら焼結助
剤の量が多ければ、それだけSi3N4自体の特性が
犠性にされるので、少量で空孔のない焼結体を得
られる助剤の選択が要点となる。残念ながら、こ
れまでのところ、圧力を加えない大気圧下の焼結
法、あるいは大気圧近傍での窒素雰囲気焼結では
10％程度の焼結助剤を加えても数％程度の空孔を
含むものしか得られていない。 However, in the case of Si 3 N 4 systems, unlike alumina, Si 3 N 4 is sublimable, that is, it does not produce a liquid phase even at extremely high temperatures, so it is not possible to produce a slight liquid phase using normal methods. It is difficult to proceed with sintering, and in order to do this, it is necessary to use a large amount of additives (sintering aids) that generate a liquid phase (5 to 20%). In this case, it goes without saying that the larger the amount of sintering aid, the more the properties of Si 3 N 4 itself are sacrificed, so it is important to select an aid that can obtain a sintered body without pores with a small amount. This is the main point. Unfortunately, so far, sintering methods under atmospheric pressure without applying pressure, or sintering in a nitrogen atmosphere near atmospheric pressure have not been successful.
Even if about 10% of the sintering aid is added, only a few percent of pores can be obtained.
一方、このような焼結体中に残存する空孔を除
去する方法として、熱間静水圧プレス（以下HIP
と云う）法が優れた技術として知られており、超
硬合金部材や前述のアルミナ製スローアウエイチ
ツプの製造などに用いられている。この方法で
は、真空焼結法、水素雰囲気焼結法などで95％以
上の密度に焼結された物品を、アルゴンなど不活
性ガスの1000Kg／cm2内外の高圧雰囲気で高温にす
ることにより、物品に等方圧力を加えて、物品中
に残存している空孔を圧潰すると同時に接合せし
めるものである。 On the other hand, hot isostatic pressing (hereinafter referred to as HIP
This method is known as an excellent technology and is used for manufacturing cemented carbide parts and the aforementioned alumina throw-away chips. In this method, an article sintered to a density of 95% or more by vacuum sintering method, hydrogen atmosphere sintering method, etc. is heated to high temperature in a high pressure atmosphere of 1000 kg/cm 2 of inert gas such as argon. Isostatic pressure is applied to the articles to crush any remaining pores in the articles and at the same time join them together.
従来、このような高温高圧ガス雰囲気下で
Si3N4を焼結する方法としては、例えば特開昭52
−47015号公報及び特開昭55−109277号公報に記
載されているが、この方法は100Kg／cm2程度の高
圧N2ガス雰囲気下で焼結助剤を含むSi3N4を約
2000℃で焼結するもので、大気圧近傍の焼結で
は、Si3N4が分解を生じ、焼結温度に限界がある
ので、この分解を抑えるためN2ガスの分圧の高
い雰囲気下で、通常の焼結法よりも高温で焼結を
行ない、高密度の焼結体を得ようとするものであ
る。ところが、この方法は、相対密度50〜80％の
低密度の焼結体の焼結が可能な利点があるが、相
対密度98％以上の高密度の焼結体を得ることが困
難で、焼結体の到達密度は高々95〜96％である。 Conventionally, under such high temperature and high pressure gas atmosphere,
As a method for sintering Si 3 N 4 , for example, JP-A-52
This method is described in JP-A-47015 and JP-A-55-109277, and this method involves sintering Si 3 N 4 containing a sintering aid in a high-pressure N 2 gas atmosphere of about 100 Kg/cm 2 .
It is sintered at 2000℃, and when sintered near atmospheric pressure, Si 3 N 4 decomposes and there is a limit to the sintering temperature, so in order to suppress this decomposition, Si 3 N 4 is sintered in an atmosphere with a high partial pressure of N 2 gas. In this method, sintering is performed at a higher temperature than the normal sintering method, and a high-density sintered body is obtained. However, although this method has the advantage of being able to sinter a low-density sintered body with a relative density of 50 to 80%, it is difficult to obtain a high-density sintered body with a relative density of 98% or more. The density achieved by the solids is at most 95-96%.
このような相対密度98％以上もの高密度化が困
難な理由としては、
(a) N2ガスの圧力が低く、緻密化のための加圧
力としての作用が殆んどないこと、
(b) 相対密度が93〜95％に到達した時点で、内部
の空孔は、N2ガスで満たされた状態で閉塞さ
れるので、この状態で焼結を続けても、かかる
雰囲気の圧力では、内部の空孔を消失させるこ
とは困難であること。更にこの状態の焼結体は
降温・減圧過程で空孔中のガス圧力により焼結
体表面に連通する穴やクラツクが生じること。 The reasons why it is difficult to increase the relative density to 98% or more are that (a) the pressure of N 2 gas is low and there is almost no effect as a pressurizing force for densification; (b) When the relative density reaches 93-95%, the internal pores are filled with N2 gas and are blocked, so even if sintering is continued in this state, the pressure of the atmosphere will not allow the internal pores to close. It is difficult to eliminate the vacancies. Furthermore, in the sintered body in this state, holes and cracks communicating with the surface of the sintered body are generated due to the gas pressure in the pores during the temperature-lowering and pressure-reducing process.
等が考えられる。従つて、相対密度が98％以上の
高密度焼結体が得られず製品としても充分満足す
べきものとは云い難いものであつた。etc. are possible. Therefore, a high-density sintered body with a relative density of 98% or more could not be obtained, and it was difficult to say that the product was fully satisfactory.
本発明はかかる現状に鑑み、クラツクや表面に
連通する穴を有しない相対密度98％以上の高密度
Si3N4焼結体を容易に製造し得る方法を提供する
ものであり、窒化珪素粉末を所定形状に成形した
圧粉体若しくはこれを焼結した相対密度70〜90％
の予備焼結体を10〜200気圧の窒素ガス若しくは
窒素を主成分とするガス雰囲気下で1500℃以上の
温度で一次焼結することにより相対密度92％以上
の一次焼結体を形成し、続いて該一次焼結体を
500〜2500気圧の窒素ガス若しくは窒素を主成分
とするガス雰囲気下で1500℃以上の温度で二次焼
結することにより相対密度98％以上の高密度焼結
体を製造することを特徴とするものである。 In view of the current situation, the present invention provides a high-density material having a relative density of 98% or more and having no cracks or holes communicating with the surface.
This provides a method for easily manufacturing a Si 3 N 4 sintered body, which is a green compact formed by molding silicon nitride powder into a predetermined shape, or a green compact formed by sintering the same with a relative density of 70 to 90%.
Form a primary sintered body with a relative density of 92% or more by primary sintering the pre-sintered body at a temperature of 1500°C or higher in a nitrogen gas atmosphere of 10 to 200 atmospheres or a gas atmosphere mainly composed of nitrogen, Next, the primary sintered body
It is characterized by producing a high-density sintered body with a relative density of 98% or more by performing secondary sintering at a temperature of 1500°C or higher in a nitrogen gas atmosphere of 500 to 2500 atmospheres or a gas atmosphere mainly composed of nitrogen. It is something.
以下、本発明を更に詳細に説明する。 The present invention will be explained in more detail below.
先ず、本発明方法においては、Si3N4粉末また
はこれに焼結助剤を添加して所定形状に成形し、
圧粉体若しくはこれを予備焼結して相対密度70〜
90％の予備焼結体とする。 First, in the method of the present invention, Si 3 N 4 powder or a sintering aid is added thereto and formed into a predetermined shape.
Green compact or pre-sintering it to a relative density of 70~
90% pre-sintered body.
前記Si3N4粉末に添加する焼結助剤としては、
Y2O3粉末、Al2O3粉末、MgO粉末等が挙げら
れ、これらの添加量はSi3N4粉末に対して５〜15
重量％が適当である。前記のSi3N4粉末または焼
結助剤を含有したSi3N4粉末の成形は静水圧成型
法、射出成型法等、公知の成形手段により行な
い、相対密度50〜60％の圧粉体とする。 The sintering aid added to the Si 3 N 4 powder is as follows:
Examples include Y2O3 powder, Al2O3 powder, MgO powder, etc., and the amount of these added is 5 to 15% per Si3N4 powder .
Weight % is appropriate. The above-mentioned Si 3 N 4 powder or Si 3 N 4 powder containing a sintering aid is molded by known molding methods such as isostatic pressing and injection molding to form a green compact with a relative density of 50 to 60%. shall be.
また、前記の圧粉体の予備焼結はN2ガス雰囲
気焼結法、ホツトプレス焼結法等により行ない、
相対密度70〜90％の予備焼結体とする。 Further, the preliminary sintering of the green compact is performed by N2 gas atmosphere sintering method, hot press sintering method, etc.
A pre-sintered body with a relative density of 70 to 90%.
前記の所定形状に成形された圧粉体若しくは予
備焼結体は次いで一次焼結し、相対密度92％以上
の一次焼結体とする。一次焼結はSi3N4の熱分解
を防止するため加圧N2ガス若しくはN2を主成分
とするガス雰囲気下で行なう必要がある。一次焼
結の圧力は10〜200気圧が必要であり、焼結温度
が高くなる程高圧とすることが好ましい。また一
次焼結の温度は1500℃以上、好ましくは1700℃以
上である。 The green compact or pre-sintered body formed into the predetermined shape is then primarily sintered to obtain a primary sintered body having a relative density of 92% or more. In order to prevent thermal decomposition of Si 3 N 4 , primary sintering must be performed in a pressurized N 2 gas atmosphere or a gas atmosphere containing N 2 as the main component. A pressure of 10 to 200 atmospheres is required for primary sintering, and the higher the sintering temperature, the higher the pressure is preferable. Further, the temperature of the primary sintering is 1500°C or higher, preferably 1700°C or higher.
この一次焼結において重要なことは、一次焼結
より得られる焼結体中の空孔が表面に連通してい
ない状態にまで密度が高められることであつて、
一次焼結体の相対密度が92％以上であることが必
要である。 What is important in this primary sintering is that the density is increased to the point where the pores in the sintered body obtained by primary sintering are not connected to the surface.
It is necessary that the relative density of the primary sintered body is 92% or more.
図はこれを実証するための一例であり、一次焼
結体の相対密度と後述する二次焼結後の焼結体の
相対密度との関係を示したものである。 The figure is an example for demonstrating this, and shows the relationship between the relative density of the primary sintered body and the relative density of the sintered body after secondary sintering, which will be described later.
図から明らかな如く、一次焼結体の相対密度が
90％付近迄は表面に連通する空孔が残つており、
二次焼結前後の密度に殆んど差がなく、二次焼結
による高密度化は期待できないが、一次焼結体の
相対密度が91％を超える付近から二次焼結後の密
度は急激に上昇し、92％以上では安定して相対密
度98％以上の高密度焼結体が得られることが判
る。 As is clear from the figure, the relative density of the primary sintered body is
Up to around 90%, there are pores remaining that communicate with the surface.
There is almost no difference in density before and after secondary sintering, and high density cannot be expected by secondary sintering, but when the relative density of the primary sintered body exceeds 91%, the density after secondary sintering becomes It can be seen that the relative density increases rapidly, and when the relative density exceeds 92%, a high-density sintered body with a relative density of 98% or above can be obtained stably.
なお、90〜92％程度の相対密度では空孔のうち
表面に連通するものが残つていることが多く、後
述する二次焼結を行なつた際に、焼結体が変形を
起すことがあるので好ましくない。従つて、一次
焼結体の相対密度は92％以上、好ましくは95％以
上とすることが望ましい。 Note that at a relative density of about 90 to 92%, some pores that communicate with the surface often remain, which may cause deformation of the sintered body during secondary sintering, which will be described later. I don't like it because it is. Therefore, it is desirable that the relative density of the primary sintered body is 92% or more, preferably 95% or more.
上記の如くして得られた一次焼結体は、続いて
N2ガス若しくはN2を主成分とするガス雰囲気下
で二次焼結を行ない、相対密度98％以上の高密度
焼結体とする。 The primary sintered body obtained as described above is then
Secondary sintering is performed in an atmosphere of N 2 gas or a gas mainly composed of N 2 to produce a high-density sintered body with a relative density of 98% or more.
二次焼結における温度と圧力、特にN2分圧
は、二次焼結による高密度化とSi3N4の分解反応
抑止の点から極めて重要であり、このうち、二次
焼結温度は通常の焼結温度である1500℃以上、好
ましくは1700℃以上が必要である。二次焼結温度
の上限は格別にはないが、当然Si3N4の分解温度
以下でなければならず、この分解温度もN2ガス
分圧の上昇と共に高くなるが、少くともその二次
焼結時のN2ガス分圧における分解温度よりも100
℃低い温度以下で行なうことが好ましく、このた
めには次式で示される温度Ｔ〔〓〕以下であるこ
とが必要である。 Temperature and pressure in secondary sintering, especially N 2 partial pressure, are extremely important from the viewpoint of increasing the density by secondary sintering and suppressing the decomposition reaction of Si 3 N 4. Of these, the secondary sintering temperature is A normal sintering temperature of 1500°C or higher, preferably 1700°C or higher is required. There is no upper limit for the secondary sintering temperature, but it must naturally be below the decomposition temperature of Si 3 N 4 , and this decomposition temperature also increases as the N 2 gas partial pressure increases, but at least the secondary sintering temperature 100 than the decomposition temperature at N2 gas partial pressure during sintering
It is preferable to carry out the reaction at a temperature lower than 0.degree. C., and for this purpose, it is necessary that the temperature is lower than the temperature T [〓] expressed by the following equation.
Ｔ＝213400／ （100.2−3.974 ln PN2）−100 ここで、PN2はN2ガス分圧〔気圧〕を示す。T=213400/(100.2−3.974 ln PN 2 )−100 Here, PN 2 indicates N 2 gas partial pressure [atmospheric pressure].
なお、上式からも明らかな通り、本発明方法で
は二次焼結温度として、N2ガス分圧１気圧にお
けるSi3N4の分解温度約1880℃よりも高い温度を
採用することができるため、高密度化のための二
次焼結時間が短縮され、Si3N4の分解が一層抑止
されるという効果も期待できる。 As is clear from the above equation, in the method of the present invention, a temperature higher than the decomposition temperature of Si 3 N 4 at 1 atmosphere of N 2 gas partial pressure, which is approximately 1880°C, can be adopted as the secondary sintering temperature. It is also expected that the secondary sintering time for high density will be shortened and the decomposition of Si 3 N 4 will be further suppressed.
次に、二次焼結の圧力は、N2ガス分圧で500気
圧以上で行なうのが良く、500気圧以下では二次
焼結に長時間がかかると共に、Si3N4の分解反応
量が時間に比例して大きくなるため焼結体の重量
減少を招くのみならず、高密度化自体が達成し難
くなる。従つて、二次焼結時のN2ガス分圧は少
くとも500気圧、好ましくは700気圧以上にするこ
とが望まれる。 Next, the pressure for secondary sintering is preferably 500 atmospheres or more with N 2 gas partial pressure. If it is less than 500 atmospheres, secondary sintering will take a long time and the amount of decomposition reaction of Si 3 N 4 will decrease. Since it increases in proportion to time, it not only causes a decrease in the weight of the sintered body, but also makes it difficult to achieve high density. Therefore, it is desirable that the N 2 gas partial pressure during secondary sintering be at least 500 atmospheres, preferably 700 atmospheres or more.
一方、N2ガス分圧は高ければ高い程、Si3N4の
分解反応が抑止され高密度化が達成し易いといえ
るが、昇圧に長時間かかり、昇圧用のコンプレツ
サを始め、本体圧力容器など焼結装置が大型化す
るので実用的でなくなる。従つて、実用的には
2500気圧までのN2ガス分圧で二次焼結すること
が望ましい。 On the other hand, the higher the N 2 gas partial pressure, the more likely it is to suppress the decomposition reaction of Si 3 N 4 and achieve high density. As the sintering equipment becomes larger, it becomes impractical. Therefore, in practical terms
It is desirable to perform secondary sintering with N2 gas partial pressure up to 2500 atmospheres.
なお、二次焼結後、雰囲気温度及び圧力を低下
させる場合、焼結体に残留空孔があると考えられ
るので、先ず雰囲気温度を1000℃以下に低下せし
めた後、雰囲気ガスの放出を行ない、圧力を低下
させるようにする方が良い。 Note that when lowering the ambient temperature and pressure after secondary sintering, there may be residual pores in the sintered body, so first lower the ambient temperature to below 1000°C, and then release the atmospheric gas. , it is better to let the pressure drop.
かくして二次焼結された焼結体は相対密度98％
以上の高密度焼結体となる。 The sintered body thus secondary sintered has a relative density of 98%.
This results in a high-density sintered body.
上記の一次焼結及び二次焼結を実施する装置と
しては、公知の加熱装置を設けた耐圧炉が使用さ
れるが、一次焼結と二次焼結とを同一装置で行え
る点からして、例えば高温熱間静水圧プレス装置
（以下HIP装置という）が好適である。 A pressure-resistant furnace equipped with a known heating device is used as the device for carrying out the above-mentioned primary sintering and secondary sintering, but since primary sintering and secondary sintering can be performed in the same device, For example, a high temperature hot isostatic press device (hereinafter referred to as HIP device) is suitable.
前記HIP装置により一次焼結及び二次焼結を行
なう場合には、焼結体の表面を清浄に維持するた
め、圧粉体若しくは予備焼結体をSi3N4、BN等の
難焼結性の窒化物粉末内に埋設して行なうか、耐
熱ルツボ内に圧粉体若しくは予備焼結体を配置
し、該ルツボ内にSi3N4粉末とSiO2との混合粉末
若しくはその圧粉体あるいはその焼結体を配置
し、該ルツボをHIP装置に装入して行なうことが
好ましい。 When primary sintering and secondary sintering are performed using the HIP device, the green compact or pre-sintered body must be made of hard-to-sinter materials such as Si 3 N 4 or BN in order to keep the surface of the sintered body clean. A mixed powder of Si 3 N 4 powder and SiO 2 or a green compact of Si 3 N 4 powder and SiO 2 powder is placed in the crucible. Alternatively, it is preferable to arrange the sintered body and insert the crucible into a HIP device.
以上述べた如く本発明方法は、圧粉体若しくは
相対密度70〜90％の予備焼結体を一次焼結して相
対密度92％以上の一次焼結体とし、続いて二次焼
結を行なうものであるから、相対密度98％以上の
高密度焼結体を容易に得ることができる。 As described above, the method of the present invention involves primary sintering of a green compact or a preliminary sintered body with a relative density of 70 to 90% to obtain a primary sintered body with a relative density of 92% or more, followed by secondary sintering. Therefore, a high-density sintered body with a relative density of 98% or more can be easily obtained.
しかも、一次焼結と二次焼結とを同一炉例えば
HIP装置で行なう場合には、一次焼結後、一次焼
結体を取り出すことなく、引続き二次焼結を行な
うことができるから、各焼結体の出し入れの手間
が省け、工程の短縮が可能であると共に、それに
伴う昇温等の熱エネルギーの節約が図られるのみ
ならず、一次焼結体を取り出す必要がないから従
来見られるような大気放置中に吸着した水分等が
焼結時にO2ガス等となつて焼結体の表面を汚染
するということがなく、表面性状に優れた高密度
焼結体を得ることができる。更に、Si3N4粉末を
予め成形して圧粉体若しくは予備焼結体とするも
のであるから、任意の複雑形状の高密度焼結体を
容易に製造することができる等の利点もあり、本
発明方法は工業生産手法として極めて優れてお
り、Si3N4セラミツクスの実用化に資するところ
極めて顕著である。 Moreover, the primary sintering and the secondary sintering are performed in the same furnace, for example.
When using a HIP device, secondary sintering can be carried out after primary sintering without having to take out the primary sintered body, which saves the effort of loading and unloading each sintered body and shortens the process. At the same time, not only is it possible to save thermal energy such as temperature rise, but also because there is no need to take out the primary sintered body, moisture etc. adsorbed during sintering when left in the atmosphere, as in the case of conventional sintering, is reduced to O2. A high-density sintered body with excellent surface quality can be obtained without contaminating the surface of the sintered body with gas or the like. Furthermore, since the Si 3 N 4 powder is pre-formed into a green compact or pre-sintered compact, it has the advantage that high-density sintered compacts of arbitrary complex shapes can be easily produced. The method of the present invention is extremely excellent as an industrial production method, and is extremely useful for the practical application of Si 3 N 4 ceramics.
以下、本発明方法を実施例によつて更に具体的
に説明する。 Hereinafter, the method of the present invention will be explained in more detail with reference to Examples.
〔実施例〕
H.C.Starck社（西独）製の純度99％以上、α
相93％、平均粒径07μｍのSi3N4粉末に焼結助剤
としてY2O36％とAl2O32％を添加し、有機溶媒中
で10時間混合した後、乾燥させて、原料粉末を調
整した。この原料粉末をシリコンゴムのチユーブ
に入れ栓をして、5000Kg／cm2の圧力で静水圧プレ
スして相対密度61％の成形体を得た。この成形体
をN2気流中で仮焼して相対密度80％の予備焼結
体とした。[Example] HCStarck (West Germany), purity 99% or more, α
6 % Y2O3 and 2 % Al2O3 were added as sintering aids to Si3N4 powder with a phase of 93% and an average particle size of 07μm , mixed in an organic solvent for 10 hours, and then dried. , the raw material powder was prepared. This raw material powder was placed in a silicone rubber tube and the tube was stoppered, and the tube was hydrostatically pressed at a pressure of 5000 kg/cm 2 to obtain a molded product with a relative density of 61%. This compact was calcined in a N 2 stream to obtain a pre-sintered body with a relative density of 80%.
次いで、この予備焼結体を黒鉛ルツボ中にBN
粉末で埋設した状態で配置し、HIP装置に装入し
た。 Next, this pre-sintered body was placed in a graphite crucible with BN.
It was placed in a powdered state and loaded into a HIP device.
先ず、HIP装置内を排気し、N2ガスを置換した
後、N2ガスを注入して50Kg／cm2の圧力とし、ヒ
ータに電力を投入して1700℃で１時間一次焼結を
行なつた。なお、一次焼結終了時のN2ガス圧力
は190Kg／cm2に上昇していた。引続いて、N2ガス
を更に注入すると同時に加熱して、約1500Kg／
cm2、1850℃で１時間二次焼結した後、雰囲気温度
を低下し、800℃に達してから減圧を行なつた。
取り出した焼結体はクラツクや表面に連通する穴
は見られず、その相対密度は99.6％であつた。 First, the HIP equipment was evacuated and replaced with N 2 gas, then N 2 gas was injected to create a pressure of 50 kg/cm 2 , power was applied to the heater, and primary sintering was performed at 1700°C for 1 hour. Ta. Note that the N 2 gas pressure at the end of the primary sintering had risen to 190 Kg/cm 2 . Subsequently, N 2 gas was further injected and heated at the same time, resulting in approximately 1500 kg/
After secondary sintering at 1850° C. for 1 hour at 1850° C., the atmospheric temperature was lowered, and after reaching 800° C., the pressure was reduced.
The removed sintered body showed no cracks or holes communicating with the surface, and its relative density was 99.6%.
図は一次焼結体の相対密度と二次焼結体の相対
密度との関係を示すグラフである。
The figure is a graph showing the relationship between the relative density of the primary sintered body and the relative density of the secondary sintered body.
Claims (1)
50〜60％の圧粉体若しくはこれを焼結した相対密
度70〜90％の予備焼結体を高温高圧炉内で10〜
200気圧の窒素ガス若しくは窒素を主成分とする
ガス雰囲気下で1500℃以上の温度で一次焼結する
ことにより相対密度92％以上の一次焼結体を形成
し、続いて同炉内の圧力を上昇して該一次焼結体
を500〜2500気圧の窒素ガス雰囲気下で1500℃以
上の温度で二次焼結することにより相対密度98％
以上の高密度焼結体を製造することを特徴とする
窒化珪素の焼結方法。 ２ 圧粉体若しくは予備焼結体を難焼結性の窒化
物粉末内に埋設して一次焼結並びに二次焼結を行
なう特許請求の範囲第２項記載の窒化珪素の焼結
方法。 ３ 耐熱ルツボ内に圧粉体若しくは予備焼結体を
配置すると共に、該ルツボ内に窒化珪素粉末と、
SiO2粉末との混合粉末若しくはその圧粉体或い
はそね焼結体を配置して一次焼結及び二次焼嫌を
行なう特許請求の範囲第１項記載の窒化珪素の焼
結方法。 ４ 二次焼結温度Ｔ〔〓〕が次式で示される温度
以下である特許請求の範囲第１項、第２項又は第
３項記載の窒化珪素の焼結方法。 Ｔ＝213400／ （100.2−3.974 ln PN2）−100 上式中PN2は高温高圧ガスの窒素分圧（気圧）
を示す。[Claims] 1. Relative density of silicon nitride powder molded into a predetermined shape
A green compact of 50 to 60% or a preliminary sintered compact of relative density of 70 to 90% is sintered in a high-temperature, high-pressure furnace for 10 to 10 minutes.
A primary sintered body with a relative density of 92% or higher is formed by primary sintering at a temperature of 1500°C or higher in a nitrogen gas atmosphere of 200 atm or a gas atmosphere containing nitrogen as the main component, and then the pressure in the furnace is reduced. The relative density is 98% by secondary sintering the primary sintered body at a temperature of 1500°C or higher in a nitrogen gas atmosphere of 500 to 2500 atm.
A method for sintering silicon nitride, characterized by producing a high-density sintered body as described above. 2. The method for sintering silicon nitride according to claim 2, wherein the green compact or the pre-sintered compact is embedded in a hard-to-sinter nitride powder to perform the primary sintering and the secondary sintering. 3 Place a green compact or pre-sintered body in a heat-resistant crucible, and place silicon nitride powder in the crucible,
2. The method for sintering silicon nitride according to claim 1, wherein a mixed powder with SiO 2 powder, a compacted powder body, or a sintered compact thereof is arranged to perform primary sintering and secondary sintering. 4. The method for sintering silicon nitride according to claim 1, 2, or 3, wherein the secondary sintering temperature T [〓] is equal to or lower than the temperature expressed by the following formula. T=213400/ (100.2−3.974 ln PN 2 )−100 In the above formula, PN 2 is the nitrogen partial pressure (atmospheric pressure) of the high temperature and high pressure gas.
shows.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP55180739A JPS57106574A (en) | 1980-12-19 | 1980-12-19 | Method of sintering silicon nitride |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP55180739A JPS57106574A (en) | 1980-12-19 | 1980-12-19 | Method of sintering silicon nitride |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS57106574A JPS57106574A (en) | 1982-07-02 |
| JPS6146431B2 true JPS6146431B2 (en) | 1986-10-14 |
Family
ID=16088459
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP55180739A Granted JPS57106574A (en) | 1980-12-19 | 1980-12-19 | Method of sintering silicon nitride |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS57106574A (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5918165A (en) * | 1982-07-19 | 1984-01-30 | 日本特殊陶業株式会社 | Manufacture of silicon nitride sintered body |
| JPS5939769A (en) * | 1982-08-28 | 1984-03-05 | 住友電気工業株式会社 | Method of sintering silicon nitride |
| JPS60166271A (en) * | 1984-02-10 | 1985-08-29 | 工業技術院長 | Manufacture of ceramic sintered body |
| JPH0649612B2 (en) * | 1987-02-18 | 1994-06-29 | 日本碍子株式会社 | Highly dense hot isostatically sintered silicon nitride sintered body and method for producing the same |
| JP5983525B2 (en) * | 2013-05-08 | 2016-08-31 | 信越化学工業株式会社 | Method for producing translucent metal oxide sintered body |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4838762A (en) * | 1971-09-17 | 1973-06-07 | ||
| JPS5330612A (en) * | 1976-09-03 | 1978-03-23 | Toshiba Ceramics Co | Manufacture of silicon nitride sintered articles |
| JPS53102320A (en) * | 1977-01-03 | 1978-09-06 | Gen Electric | Silicon nitride sintered articles and manufacture thereof |
| JPS53102321A (en) * | 1977-01-03 | 1978-09-06 | Gen Electric | Silicon nitride sintered articles and manufacture thereof |
| JPS54107914A (en) * | 1978-02-10 | 1979-08-24 | Tokyo Shibaura Electric Co | Production of high density silicon nitride base sintered body |
| JPS54144413A (en) * | 1978-05-02 | 1979-11-10 | Asea Ab | Manufacture of silicon nitride product |
| JPS54144412A (en) * | 1978-05-02 | 1979-11-10 | Asea Ab | Manufacture of silicon nitride product |
| JPS54148010A (en) * | 1977-12-23 | 1979-11-19 | Fiat Spa | Sintering silicon nitride compressed body |
-
1980
- 1980-12-19 JP JP55180739A patent/JPS57106574A/en active Granted
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4838762A (en) * | 1971-09-17 | 1973-06-07 | ||
| JPS5330612A (en) * | 1976-09-03 | 1978-03-23 | Toshiba Ceramics Co | Manufacture of silicon nitride sintered articles |
| JPS53102320A (en) * | 1977-01-03 | 1978-09-06 | Gen Electric | Silicon nitride sintered articles and manufacture thereof |
| JPS53102321A (en) * | 1977-01-03 | 1978-09-06 | Gen Electric | Silicon nitride sintered articles and manufacture thereof |
| JPS54148010A (en) * | 1977-12-23 | 1979-11-19 | Fiat Spa | Sintering silicon nitride compressed body |
| JPS54107914A (en) * | 1978-02-10 | 1979-08-24 | Tokyo Shibaura Electric Co | Production of high density silicon nitride base sintered body |
| JPS54144413A (en) * | 1978-05-02 | 1979-11-10 | Asea Ab | Manufacture of silicon nitride product |
| JPS54144412A (en) * | 1978-05-02 | 1979-11-10 | Asea Ab | Manufacture of silicon nitride product |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS57106574A (en) | 1982-07-02 |
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