JPH0826830A - Silicon nitride-based sintered compact, its production and method for its utilization - Google Patents
Silicon nitride-based sintered compact, its production and method for its utilizationInfo
- Publication number
- JPH0826830A JPH0826830A JP6183909A JP18390994A JPH0826830A JP H0826830 A JPH0826830 A JP H0826830A JP 6183909 A JP6183909 A JP 6183909A JP 18390994 A JP18390994 A JP 18390994A JP H0826830 A JPH0826830 A JP H0826830A
- Authority
- JP
- Japan
- Prior art keywords
- silicon nitride
- cerium
- sintered body
- oxide
- weight
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 229910052581 Si3N4 Inorganic materials 0.000 title claims abstract description 96
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 title claims abstract description 92
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 11
- 238000000034 method Methods 0.000 title claims description 13
- 230000007797 corrosion Effects 0.000 claims abstract description 63
- 238000005260 corrosion Methods 0.000 claims abstract description 63
- 238000005245 sintering Methods 0.000 claims abstract description 42
- 239000000654 additive Substances 0.000 claims abstract description 30
- 230000000996 additive effect Effects 0.000 claims abstract description 22
- 239000000203 mixture Substances 0.000 claims abstract description 12
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 7
- 229910052791 calcium Inorganic materials 0.000 claims abstract description 7
- 229910052735 hafnium Inorganic materials 0.000 claims abstract description 7
- 229910052749 magnesium Inorganic materials 0.000 claims abstract description 7
- 150000004767 nitrides Chemical class 0.000 claims abstract description 7
- 229910052761 rare earth metal Inorganic materials 0.000 claims abstract description 7
- 229910052727 yttrium Inorganic materials 0.000 claims abstract description 7
- 229910052726 zirconium Inorganic materials 0.000 claims abstract description 7
- 229910052684 Cerium Inorganic materials 0.000 claims description 60
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 claims description 60
- 239000007864 aqueous solution Substances 0.000 claims description 36
- 238000006243 chemical reaction Methods 0.000 claims description 13
- 150000001875 compounds Chemical class 0.000 claims description 13
- 238000010304 firing Methods 0.000 claims description 10
- 239000000126 substance Substances 0.000 claims description 10
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 6
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims description 6
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 claims description 6
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 6
- 239000011575 calcium Substances 0.000 claims description 6
- VBJZVLUMGGDVMO-UHFFFAOYSA-N hafnium atom Chemical compound [Hf] VBJZVLUMGGDVMO-UHFFFAOYSA-N 0.000 claims description 6
- 239000011777 magnesium Substances 0.000 claims description 6
- VWQVUPCCIRVNHF-UHFFFAOYSA-N yttrium atom Chemical compound [Y] VWQVUPCCIRVNHF-UHFFFAOYSA-N 0.000 claims description 6
- 238000005259 measurement Methods 0.000 claims description 4
- 239000000470 constituent Substances 0.000 claims description 3
- 230000001590 oxidative effect Effects 0.000 claims description 3
- 239000000843 powder Substances 0.000 abstract description 9
- 239000002002 slurry Substances 0.000 abstract description 6
- CETPSERCERDGAM-UHFFFAOYSA-N ceric oxide Chemical compound O=[Ce]=O CETPSERCERDGAM-UHFFFAOYSA-N 0.000 abstract description 4
- 229910000422 cerium(IV) oxide Inorganic materials 0.000 abstract description 4
- 150000001247 metal acetylides Chemical class 0.000 abstract description 4
- 239000011812 mixed powder Substances 0.000 abstract description 2
- 229910001404 rare earth metal oxide Inorganic materials 0.000 abstract 1
- 239000011369 resultant mixture Substances 0.000 abstract 1
- 239000002904 solvent Substances 0.000 abstract 1
- 239000000523 sample Substances 0.000 description 18
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 12
- 239000000463 material Substances 0.000 description 12
- 239000012752 auxiliary agent Substances 0.000 description 11
- 239000012670 alkaline solution Substances 0.000 description 7
- 230000035939 shock Effects 0.000 description 7
- 150000001785 cerium compounds Chemical class 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 239000002245 particle Substances 0.000 description 5
- 230000004580 weight loss Effects 0.000 description 5
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 4
- 238000000280 densification Methods 0.000 description 4
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 3
- 239000003513 alkali Substances 0.000 description 3
- 238000010828 elution Methods 0.000 description 3
- 238000007731 hot pressing Methods 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 230000001737 promoting effect Effects 0.000 description 3
- -1 carbides Chemical class 0.000 description 2
- 229910000420 cerium oxide Inorganic materials 0.000 description 2
- 238000009694 cold isostatic pressing Methods 0.000 description 2
- 235000019441 ethanol Nutrition 0.000 description 2
- 238000001513 hot isostatic pressing Methods 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- BMMGVYCKOGBVEV-UHFFFAOYSA-N oxo(oxoceriooxy)cerium Chemical compound [Ce]=O.O=[Ce]=O BMMGVYCKOGBVEV-UHFFFAOYSA-N 0.000 description 2
- 239000013055 pulp slurry Substances 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- 229910002492 Ce(NO3)3·6H2O Inorganic materials 0.000 description 1
- 229910052692 Dysprosium Inorganic materials 0.000 description 1
- 229910052688 Gadolinium Inorganic materials 0.000 description 1
- 229910021193 La 2 O 3 Inorganic materials 0.000 description 1
- 229910052779 Neodymium Inorganic materials 0.000 description 1
- 229910052772 Samarium Inorganic materials 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- 239000004809 Teflon Substances 0.000 description 1
- 229920006362 Teflon® Polymers 0.000 description 1
- 229910052769 Ytterbium Inorganic materials 0.000 description 1
- BCZWPKDRLPGFFZ-UHFFFAOYSA-N azanylidynecerium Chemical compound [Ce]#N BCZWPKDRLPGFFZ-UHFFFAOYSA-N 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- UNJPQTDTZAKTFK-UHFFFAOYSA-K cerium(iii) hydroxide Chemical compound [OH-].[OH-].[OH-].[Ce+3] UNJPQTDTZAKTFK-UHFFFAOYSA-K 0.000 description 1
- WXANAQMHYPHTGY-UHFFFAOYSA-N cerium;ethyne Chemical compound [Ce].[C-]#[C] WXANAQMHYPHTGY-UHFFFAOYSA-N 0.000 description 1
- 238000013329 compounding Methods 0.000 description 1
- 238000000748 compression moulding Methods 0.000 description 1
- 230000009089 cytolysis Effects 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- KBQHZAAAGSGFKK-UHFFFAOYSA-N dysprosium atom Chemical compound [Dy] KBQHZAAAGSGFKK-UHFFFAOYSA-N 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- UIWYJDYFSGRHKR-UHFFFAOYSA-N gadolinium atom Chemical compound [Gd] UIWYJDYFSGRHKR-UHFFFAOYSA-N 0.000 description 1
- 238000001746 injection moulding Methods 0.000 description 1
- 229910052746 lanthanum Inorganic materials 0.000 description 1
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- QEFYFXOXNSNQGX-UHFFFAOYSA-N neodymium atom Chemical compound [Nd] QEFYFXOXNSNQGX-UHFFFAOYSA-N 0.000 description 1
- 238000007344 nucleophilic reaction Methods 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000013001 point bending Methods 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- KZUNJOHGWZRPMI-UHFFFAOYSA-N samarium atom Chemical compound [Sm] KZUNJOHGWZRPMI-UHFFFAOYSA-N 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 229910052712 strontium Inorganic materials 0.000 description 1
- CIOAGBVUUVVLOB-UHFFFAOYSA-N strontium atom Chemical compound [Sr] CIOAGBVUUVVLOB-UHFFFAOYSA-N 0.000 description 1
- 230000003746 surface roughness Effects 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- 238000003826 uniaxial pressing Methods 0.000 description 1
- 239000013585 weight reducing agent Substances 0.000 description 1
- NAWDYIZEMPQZHO-UHFFFAOYSA-N ytterbium Chemical compound [Yb] NAWDYIZEMPQZHO-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
- Ceramic Products (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、耐アルカリ水溶液腐食
性を有する窒化ケイ素質焼結体及びその製造方法並びに
その利用方法に関する。詳細には、本発明は、常温ある
いは高温高圧下でのアルカリ水溶液に対する耐腐食性に
優れた窒化ケイ素質焼結体及びその製造方法に関し、更
に、該窒化ケイ素質焼結体を、従来適用できなかった耐
食性構造部材(例えばアルカリ水溶液に対する耐腐食性
を必要とするパイプ、ノズル、ベアリングなどの構成部
材、導電率測定用セル部材又は導電率測定用電極部材な
どの耐食性構造部材)として利用する方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicon nitride-based sintered body having an alkali solution corrosion resistance, a method for producing the same, and a method for using the same. More specifically, the present invention relates to a silicon nitride sintered body having excellent corrosion resistance to an alkaline aqueous solution at room temperature or under high temperature and high pressure and a method for producing the same, and further, the silicon nitride sintered body can be applied conventionally. There was no corrosion-resistant structural member (e.g. pipes, nozzles, bearings and other components that require corrosion resistance to alkaline aqueous solutions, corrosion-resistant structural members such as conductivity measuring cell members or conductivity measuring electrode members) Regarding
【０００２】[0002]
【課題を解決するための手段】窒化ケイ素質焼結体は、
破壊靱性などの機械的特性、耐熱性、耐熱衝撃性に優れ
ているため、耐熱性高強度材料としての用途開発が進め
られている。[Means for Solving the Problems] The silicon nitride sintered body is
Since it has excellent mechanical properties such as fracture toughness, heat resistance, and thermal shock resistance, application development as a heat resistant and high strength material is underway.
【０００３】[0003]
【発明が解決しようとする課題】しかしながら、窒化ケ
イ素質焼結体は、高温高圧のアルカリ水溶液などの特殊
な環境下では、腐食によってその本来の特性(機械的特
性、耐熱性、耐熱衝撃性)を十分に発揮することができ
ないという欠点を有している。そのため、従来の窒化ケ
イ素質焼結体は、高温高圧のアルカリ水溶液を使用する
環境下で使用される構造材料としては利用されていなか
った。However, the silicon nitride sintered body has its original characteristics (mechanical characteristics, heat resistance, thermal shock resistance) due to corrosion in a special environment such as high temperature and high pressure alkaline aqueous solution. It has a drawback that it cannot fully exhibit. Therefore, the conventional silicon nitride sintered body has not been used as a structural material used in an environment where an alkaline aqueous solution at high temperature and high pressure is used.
【０００４】窒化ケイ素質焼結体が高温のアルカリ水溶
液中で腐食することは、島田らの報告「Boshoku Gijuts
u，37，373−378(1988)」及び「Br.Ceram.Trans.J.，9
1，117−120(1992)」によって広く知られるところであ
る。この腐食は、基本的には酸化反応であり、Si3N4＋6
H2O→3SiO2＋4NH3の反応によって窒化ケイ素の腐食が進
行するものである。この反応において、アルカリ水溶液
中のOH-イオンは、生成したシリカ(SiO2)と求核反応に
より結合し、SiO2＋2OH-→SiO3 2-＋H2Oの反応が生じ、
水溶液中にSi成分を溶解せしめて、この腐食をさらに進
行させるものと考えられている。The fact that a silicon nitride sintered body is corroded in a high temperature alkaline aqueous solution is reported by Shimada et al., "Boshoku Gijuts".
u, 37, 373-378 (1988) "and" Br. Ceram. Trans. J., 9
1, 117-120 (1992) ”. This corrosion is basically an oxidation reaction and results in Si 3 N 4 +6
Corrosion of silicon nitride proceeds due to the reaction of H 2 O → 3SiO 2 + 4NH 3 . In this reaction, the OH − ion in the alkaline aqueous solution is bonded to the generated silica (SiO 2 ) by a nucleophilic reaction, and a reaction of SiO 2 + 2OH − → SiO 3 2 − + H 2 O occurs,
It is believed that this corrosion is further promoted by dissolving the Si component in the aqueous solution.
【０００５】また、窒化ケイ素質焼結体を構成する粒界
のシリケ−トも、前述の生成したシリカと同様な機構に
よりアルカリ溶液中に溶出する。この腐食は、表面から
進行し、構成成分の溶出による重量減少を伴いながら粒
界腐食が進行し、表面に変質層を形成していく。Further, the silicate of the grain boundary which constitutes the silicon nitride sintered body is also eluted into the alkaline solution by the same mechanism as that of the silica produced above. This corrosion progresses from the surface, and the intergranular corrosion progresses with the weight loss due to the elution of the constituents, forming an altered layer on the surface.
【０００６】窒化ケイ素質構造部材において、表面変質
層の存在は致命的な強度の低下を招き、材料自体の信頼
性を失うことになる。従って、このような腐食反応によ
って容易に腐食を受ける従来の窒化ケイ素質焼結体を、
高温高圧のアルカリ水溶液腐食環境下での構造材料とし
て利用することは、非常に困難であった。In the silicon nitride-based structural member, the presence of the surface-altered layer causes a fatal decrease in strength, and the reliability of the material itself is lost. Therefore, the conventional silicon nitride sintered body which is easily corroded by such a corrosion reaction,
It was very difficult to use as a structural material in a high temperature and high pressure alkaline aqueous solution corrosive environment.
【０００７】本発明者等は、特に高温高圧のアルカリ水
溶液腐食環境下での構造材料として利用できる窒化ケイ
素質焼結体について鋭意研究を重ねた結果、本発明を完
成したものであって、その目的とするところは、 ・第１に、窒化ケイ素質焼結体が本来有している特性、
即ち破壊靱性等の機械的特性、耐熱性、耐熱衝撃性を損
なうことがなく、しかも高温高圧のアルカリ水溶液に対
する耐食性に優れた新規な窒化ケイ素質焼結体を提供す
ることにあり、 ・第２に、上記の窒化ケイ素質焼結体を製造する方法を
提供することにあり、 ・第３に、常温又は高温高圧のアルカリ水溶液を使用す
る特殊な環境下の構造材料として利用できる窒化ケイ素
質焼結体を提供することにある。The inventors of the present invention have completed the present invention as a result of earnestly researching a silicon nitride-based sintered body that can be used as a structural material under a high temperature and high pressure alkaline aqueous solution corrosive environment. The purpose is as follows: First, the characteristics that the silicon nitride sintered body originally has,
That is, it is to provide a novel silicon nitride sintered body that does not impair mechanical properties such as fracture toughness, heat resistance, and thermal shock resistance, and that is excellent in corrosion resistance to an alkaline aqueous solution at high temperature and high pressure. To provide a method for producing the above-mentioned silicon nitride sintered body. Thirdly, a silicon nitride sintered material that can be used as a structural material under a special environment using an alkaline aqueous solution at room temperature or high temperature and high pressure. To provide a union.
【０００８】[0008]
【課題を解決するための手段】本発明は、窒化ケイ素と
焼結助剤を含む添加剤からなる窒化ケイ素質焼結体にお
いて、 ・焼結助剤としてセリウムの単体又はその化合物を使用
する点、及び ・焼結助剤を含む添加剤に対するセリウム成分比を適性
範囲とする点、を特徴とし、これによりアルカリ水溶液
に対する耐食性を向上させたものであり、また、該窒化
ケイ素質焼結体の製造方法において、 ・窒化ケイ素：60〜99重量％に、上記焼結助剤を含む添
加剤：1〜40重量％を配合する点、及び、 ・これを0.1MPa以上で非酸化雰囲気中で焼成する点、を
特徴とし、また、本発明に係る窒化ケイ素質焼結体を利
用する方法として、 ・アルカリ水溶液に対する耐食性を必要とする耐食性構
造部材として使用する点を特徴とする。The present invention relates to a silicon nitride sintered body comprising silicon nitride and an additive containing a sintering aid, wherein cerium alone or a compound thereof is used as the sintering aid. And, the cerium component ratio with respect to the additive containing a sintering aid is in a suitable range, thereby improving the corrosion resistance to an alkaline aqueous solution. In the manufacturing method: -Silicon nitride: 60 to 99% by weight, an additive containing the above sintering aid: 1 to 40% by weight, and-calcination of this at 0.1 MPa or more in a non-oxidizing atmosphere. In addition, as a method of using the silicon nitride sintered body according to the present invention, it is characterized in that it is used as a corrosion-resistant structural member requiring corrosion resistance to an alkaline aqueous solution.
【０００９】即ち、本発明に係る窒化ケイ素質焼結体
は、「窒化ケイ素：60〜99重量％と、(1)セリウムの単
体又はその化合物及び(2)マグネシウム、カルシウム、
アルミニウム、ジルコニウム、ハフニウム、イットリウ
ム又はその他の希土類元素の単体もしくはその酸化物、
窒化物、炭化物などの化合物ないしはこれらの混合物、
よりなる焼結助剤を含む添加剤であって、添加した全て
の添加剤に対するセリウム成分の酸化物換算重量比「Ce
O2／(CeO2＋X)、X：セリウム成分以外に添加した全ての
添加成分の酸化物換算重量」が0.1〜1.0である添加剤：
1〜40重量％(酸化物換算)からなる窒化ケイ素質焼結体
であって、理論密度に対する相対比が90％以上の焼結体
で、且つ焼成中に生成したセリウム成分が粒界相に存在
してなることを特徴とする窒化ケイ素質焼結体。」を要
旨とする。That is, the silicon nitride-based sintered body according to the present invention is composed of "silicon nitride: 60 to 99% by weight, (1) a simple substance of cerium or its compound, and (2) magnesium, calcium,
Aluminum, zirconium, hafnium, yttrium or other rare earth element simple substance or oxide thereof,
Compounds such as nitrides and carbides, or mixtures thereof,
An additive containing a sintering aid consisting of the cerium component in terms of oxide conversion weight ratio “Ce
O 2 / (CeO 2 + X), X: additive whose oxide equivalent weight of all the added components other than the cerium component is 0.1 to 1.0:
A silicon nitride sintered body composed of 1 to 40% by weight (as oxide), with a relative ratio to the theoretical density of 90% or more, and the cerium component generated during firing becomes a grain boundary phase. A silicon nitride sintered body characterized by being present. Is the gist.
【００１０】また、本発明に係る窒化ケイ素質焼結体の
製造方法は、「60〜99重量％の窒化ケイ素に、(1)セリ
ウムの単体又はその化合物及び(2)マグネシウム、カル
シウム、アルミニウム、ジルコニウム、ハフニウム、イ
ットリウム又はその他の希土類元素の単体もしくはその
酸化物、窒化物、炭化物などの化合物ないしはこれらの
混合物、よりなる焼結助剤を含む添加剤であって、添加
した全ての添加剤に対するセリウム成分の酸化物換算重
量比「CeO2／(CeO2＋X)、X：セリウム成分以外に添加し
た全ての添加成分の酸化物換算重量」が0.1〜1.0である
添加剤を酸化物換算で1〜40重量％配合し、0.1MPa以上
で非酸化雰囲気中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。」を要旨とし、さらに、本発明
は、「前記窒化ケイ素質焼結体を、アルカリ水溶液に対
する耐食性を必要とするパイプ、ノズル、ベアリングな
どの構成部材、導電率測定用セル部材又は導電率測定用
電極部材などの耐食性構造部材として利用する方法。」
を要旨とする。Further, the method for producing a silicon nitride sintered body according to the present invention includes: (60-99% by weight of silicon nitride, (1) cerium alone or a compound thereof and (2) magnesium, calcium, aluminum, Zirconium, hafnium, yttrium or other rare earth element simple substance or its oxides, nitrides, compounds such as carbides, or mixtures thereof, an additive containing a sintering aid, which is based on all the added additives The oxide conversion weight ratio of cerium component “CeO 2 / (CeO 2 + X), X: oxide conversion weight of all the added components other than the cerium component” is 0.1 to 1.0, and the additive is 1 in oxide conversion. A method for producing a silicon nitride-based sintered body, which comprises blending up to 40% by weight and firing in a non-oxidizing atmosphere at 0.1 MPa or more. Further, the present invention provides the "silicon nitride sintered body, a component member such as a pipe, a nozzle or a bearing, which requires corrosion resistance to an alkaline aqueous solution, a conductivity measuring cell member or a conductivity measuring member. A method of using it as a corrosion resistant structural member such as an electrode member. "
Is the gist.
【００１１】なお、以下の明細書で、上記『(1) セリウ
ムの単体又はその化合物』を“セリウム系焼結助剤”と
記載し、また、上記『(2) マグネシウム、カルシウム、
アルミニウム、ジルコニウム、ハフニウム、イットリウ
ム又はその他の希土類元素の単体もしくはその酸化物、
窒化物、炭化物等の化合物ないしはこれらの混合物』を
“その他の助剤”と記載する。また、上記『添加した全
ての添加剤に対するセリウム成分の酸化物換算重量比
「CeO2／(CeO2＋X)、X：セリウム成分以外に添加した全
ての添加成分の酸化物換算重量」』を単に“セリウム成
分比”と略記する。In the following specification, the above "(1) simple substance of cerium or its compound" is referred to as "cerium-based sintering aid", and "(2) magnesium, calcium,
Aluminum, zirconium, hafnium, yttrium or other rare earth element simple substance or oxide thereof,
A compound such as a nitride or a carbide or a mixture thereof is described as "other auxiliary agent". In addition, the above “oxide conversion weight ratio of cerium component to all added additives“ CeO 2 / (CeO 2 + X), X: oxide conversion weight of all addition components other than cerium component ”” is simply It is abbreviated as "cerium component ratio".
【００１２】以下、本発明について詳細に説明すると、
本発明者等は、窒化ケイ素の添加物としてセリウム系焼
結助剤又はセリウム系焼結助剤とその他の助剤を併用
し、セリウム成分比を特定範囲に規定することにより、
粒界相にセリウムを含むシリケ−トなどのセリウム化合
物が形成され、粒界相の溶出が抑制されることを見いだ
した。The present invention will be described in detail below.
The present inventors, by using a cerium-based sintering aid or other aids together with a cerium-based sintering aid as an additive of silicon nitride, by defining the cerium component ratio in a specific range,
It has been found that a cerium compound such as silicate containing cerium is formed in the grain boundary phase and the elution of the grain boundary phase is suppressed.
【００１３】そして、本発明に係る窒化ケイ素質焼結体
をアルカリ水溶液により腐食させた後の状態を観察する
と、この焼結体の表面にあらわれる腐食相は極めて薄
く、また、EPMA(Electron probe micro analysis)によ
れば、セリウム元素が濃縮した相となっていることが認
められる。このように、腐食後の本発明に係る窒化ケイ
素質焼結体は、その表面に大きな変化が認められず、腐
食後の残留強度が極めて高いものであり、アルカリ水溶
液に対する耐食性が飛躍的に向上した窒化ケイ素質焼結
体であることを見いだし、本発明を完成したものであ
る。When the state after the silicon nitride sintered body according to the present invention is corroded by an alkaline aqueous solution is observed, the corrosion phase appearing on the surface of this sintered body is extremely thin, and EPMA (Electron probe micro) is used. According to the analysis), it is recognized that the phase is a phase enriched with cerium element. As described above, after the corrosion, the silicon nitride sintered body according to the present invention has no significant change in the surface, has a very high residual strength after the corrosion, and the corrosion resistance to the alkaline aqueous solution is remarkably improved. The present invention has been completed by finding out that it is a silicon nitride sintered body.
【００１４】本発明に係る窒化ケイ素質焼結体では、
“窒化珪素”と“セリウム系焼結助剤及びその他の助
剤”の配合割合として、窒化珪素：60〜99重量％「好ま
しくは70〜90重量％」と、セリウム系焼結助剤及びその
他の助剤の合量：1〜40重量％「好ましくは5〜30重量％
(常圧焼結する場合)、より好ましくは10〜20重量％」と
することを特徴とし、また、セリウム成分比を0.1〜1.0
(最適は0.7以上)とすることを特徴とする。なお、セリ
ウム成分比が1.0の場合は、窒化珪素とセリウム系焼結
助剤からなる窒化ケイ素質焼結体であって、その他の助
剤を併用しないものであり、これも本発明に包含される
ものである。In the silicon nitride sintered body according to the present invention,
As a compounding ratio of "silicon nitride" and "cerium-based sintering aid and other aids", silicon nitride: 60 to 99% by weight "preferably 70 to 90% by weight", cerium-based sintering aid and other Total amount of auxiliaries: 1-40 wt% "preferably 5-30 wt%
(In the case of normal pressure sintering), more preferably 10 to 20 wt% ``, cerium component ratio of 0.1 to 1.0
(The optimum value is 0.7 or more). Incidentally, when the cerium component ratio is 1.0, it is a silicon nitride sintered body composed of silicon nitride and a cerium-based sintering aid, which does not use other aids in combination, and this is also included in the present invention. It is something.
【００１５】本質的には、窒化ケイ素とセリウム系焼結
助剤との組合せにより、アルカリ水溶液に対する耐食性
が向上する(後記表２の試料No.1〜4参照)。そして、セ
リウム系焼結助剤とその他の助剤を併用すると、アルカ
リ水溶液に対する耐食性を低下させることなしに、その
他の助剤の併用による相乗効果により“緻密化促進効
果”及び“強度向上効果”の作用が生じる(後記表２の
試料No.5〜16参照)。In essence, the combination of silicon nitride and a cerium-based sintering aid improves the corrosion resistance to alkaline aqueous solutions (see Sample Nos. 1 to 4 in Table 2 below). When a cerium-based sintering additive is used in combination with other auxiliary agents, the "densification promoting effect" and "strength improving effect" are achieved by the synergistic effect of the combined use of other auxiliary agents without reducing the corrosion resistance to alkaline aqueous solution. Occurs (see sample Nos. 5 to 16 in Table 2 below).
【００１６】ただし、本発明に係る窒化ケイ素質焼結体
において、セリウム系焼結助剤とその他の助剤を併用す
る場合は、セリウム成分の添加量が適正でなければ、セ
リウム化合物の粒界における相対量が適正とならないた
め、アルカリ水溶液に対する耐食性と緻密化、高強度化
の効果が同時に発現しない。その発現範囲は、セリウム
成分比、即ち“添加した全ての添加剤に対するセリウム
成分の酸化物換算重量比「CeO2／(CeO2＋X)，X：セリウ
ム成分以外に添加した全ての添加成分の酸化物換算重
量」”が0.1以上であり、最適範囲は0.7以上である。However, in the silicon nitride sintered body according to the present invention, when a cerium-based sintering aid is used in combination with other auxiliaries, if the addition amount of the cerium component is not appropriate, the grain boundary of the cerium compound is Since the relative amount in is not appropriate, the effects of corrosion resistance, densification, and strengthening against an alkaline aqueous solution are not exhibited at the same time. The expression range is the cerium component ratio, that is, “the oxide conversion weight ratio of the cerium component to all the added additives“ CeO 2 / (CeO 2 + X), X: oxidation of all the added components other than the cerium component. The "equivalent weight" is 0.1 or more, and the optimum range is 0.7 or more.
【００１７】セリウム成分比が0.1未満では、セリウム
化合物の粒界における相対量が適正とならず、アルカリ
水溶液に対する耐食性向上が望めないので好ましくな
い。本発明において、セリウム系焼結助剤及びその他の
助剤を含む添加剤の量が過多であれば、高温、常温での
機械的特性が低下するため、窒化ケイ素に対する添加剤
は適正でなければならない。If the cerium component ratio is less than 0.1, the relative amount of the cerium compound at the grain boundaries is not appropriate, and improvement in corrosion resistance to an alkaline aqueous solution cannot be expected, which is not preferable. In the present invention, if the amount of the additive containing a cerium-based sintering aid and other additives is excessive, the mechanical properties at high temperature and room temperature will deteriorate, so the additive for silicon nitride must be appropriate. I won't.
【００１８】本発明において、窒化珪素を60重量％未満
では、強度が低下し、窒化ケイ素質焼結体本来の特性
(機械的特性、耐熱性、耐熱衝撃性)を十分に発揮し難い
ので好ましくなく、一方、99重量％を超えると、本発明
で特徴とするセリウム系焼結助剤の添加量、セリウム系
焼結助剤及びその他の助剤の添加量が必然的に少なくな
り、窒化ケイ素が焼結し難くなるのみならず、アルカリ
水溶液に対する耐食性向上がみられず、また、緻密化促
進効果及び強度向上効果が生じなくなるので、好ましく
ない。In the present invention, when the content of silicon nitride is less than 60% by weight, the strength is lowered and the original characteristics of the silicon nitride sintered body are obtained.
(Mechanical properties, heat resistance, thermal shock resistance) is not preferable because it is difficult to sufficiently exert it. On the other hand, when it exceeds 99% by weight, the addition amount of the cerium-based sintering aid characterized by the present invention, cerium-based firing Inevitably the amount of addition of auxiliary agents and other auxiliary agents becomes small, not only does silicon nitride become difficult to sinter, but also no improvement in corrosion resistance to alkaline aqueous solution is observed, and densification promoting effect and strength improving effect. Is not preferable because it does not occur.
【００１９】本発明において、セリウム系焼結助剤及び
その他の助剤の添加量が1重量％未満では、窒化ケイ素
が99重量％を超える場合に相当することになり、前記し
たとおり、窒化ケイ素の焼結し難くなるのみならず、ア
ルカリ水溶液に対する耐食性向上がみられず、また、緻
密化促進効果及び強度向上効果が生じなくなるので、好
ましくない。一方、セリウム系焼結助剤及びその他の助
剤の添加量が40重量％を超えると、窒化珪素が60重量％
未満に相当することになり、前記したとおり、強度が低
下し、窒化ケイ素質焼結体本来の特性(機械的特性、耐
熱性、耐熱衝撃性)を十分に発揮し難いので好ましくな
い。In the present invention, when the addition amount of the cerium-based sintering aid and other additives is less than 1% by weight, it corresponds to the case where silicon nitride exceeds 99% by weight. Not only is it difficult to sinter, but the corrosion resistance to alkaline aqueous solution is not improved, and the densification promoting effect and strength improving effect do not occur, which is not preferable. On the other hand, if the amount of cerium-based sintering additive and other additives exceeds 40% by weight, 60% by weight of silicon nitride
This is not preferable since the strength is lowered as described above, and it is difficult to sufficiently exhibit the original characteristics (mechanical characteristics, heat resistance, thermal shock resistance) of the silicon nitride sintered body, as described above.
【００２０】本発明に係る窒化ケイ素質焼結体は、理論
密度に対する相対比が90％以上であり、且つ焼成中に生
成したセリウム化合物が粒界相に存在し、アルカリ水溶
液に対する耐食性が向上した窒化ケイ素質焼結体を提供
するものである。本発明に係る窒化ケイ素質焼結体にお
いて、本発明で規定する組成範囲内であれば、結果的に
窒化珪素の一部がα−サイアロン、β−サイアロン又は
これらの混相となっていても、本発明の効果に大きな変
化はないので、これも本発明に包含されるものである。In the silicon nitride sintered body according to the present invention, the relative ratio to the theoretical density is 90% or more, and the cerium compound produced during firing is present in the grain boundary phase, and the corrosion resistance to the alkaline aqueous solution is improved. A silicon nitride sintered body is provided. In the silicon nitride sintered body according to the present invention, so long as it is within the composition range specified in the present invention, even if a part of silicon nitride is α-sialon, β-sialon or a mixed phase thereof, Since the effect of the present invention is not significantly changed, this is also included in the present invention.
【００２１】本発明で使用する窒化珪素としては、α
型、β型の何れでも使用することができ、また、平均粒
径が3μｍ以下の窒化珪素微粉末の使用が好適である。3
μｍを越える窒化珪素粉末では、焼結性や強度が低下す
るので好ましくない。The silicon nitride used in the present invention is α
Type and β type can be used, and it is preferable to use silicon nitride fine powder having an average particle size of 3 μm or less. 3
A silicon nitride powder exceeding μm is not preferable because the sinterability and strength decrease.
【００２２】また、本発明で添加するセリウム系焼結助
剤のセリウム源としては、セリウムの単体、又は、例え
ばセリア“CeO2”、セリウムカ−バイト“CeC2”、セリ
ウムハイドロオキサイド“2Ce(OH)3・3H2O”、セリウム
ナイトライド“Ce(NO3)3・6H2O”、セリウムカ−ボネ−
ト“Ce(CO3)3・5H2O”、セリウムオキサイド“Ce2O3”
等のセリウム化合物を使用することができる。Further, as the cerium source of cerium sintering aid to be added in the present invention, a single cerium, or, for example, ceria "CeO 2", Seriumuka - byte "CEC 2", cerium hydroxide "2Ce (OH ) 3 · 3H 2 O ", cerium nitride" Ce (NO 3) 3 · 6H 2 O ", Seriumuka - Bonnet -
Doo "Ce (CO 3) 3 · 5H 2 O", cerium oxide "Ce 2 O 3"
Cerium compounds such as
【００２３】また、本発明で上記セリウム系焼結助剤と
併用するその他の助剤としては、マグネシウム、カルシ
ウム、ストロンチウム、アルミニウム、ジルコニウム、
ハフニウム、イットリウム及びその他の希土類元素（例
えばランタニウム、ネオジウム、ジスプロシウム、ガド
リウム、サマリウム、イッテリビウム等）の単体もしく
はその酸化物、窒化物、炭化物などの化合物又はこれら
の混合物である。具体的には、後記表１に示すように、
その他の助剤Ａ、Ｂ（MgO，Al2O3，SrO，CaO，ZrO2，Al
N，Y2O3，HfO2，La2O3）を併用することができる。この
うち例えばAlNの存在下ではサイアロンが生成する。Other auxiliary agents used in combination with the above cerium-based sintering auxiliary agent in the present invention include magnesium, calcium, strontium, aluminum, zirconium,
It is a simple substance of hafnium, yttrium, and other rare earth elements (for example, lanthanum, neodymium, dysprosium, gadolinium, samarium, ytterbium, etc.), or compounds thereof such as oxides, nitrides and carbides, or a mixture thereof. Specifically, as shown in Table 1 below,
Other auxiliaries A, B (MgO, Al 2 O 3 , SrO, CaO, ZrO 2 , Al
N, Y 2 O 3 , HfO 2 , La 2 O 3 ) can be used together. Of these, for example, sialon is produced in the presence of AlN.
【００２４】次に、本発明の窒化ケイ素質焼結体の製造
方法について説明すると、まず、所定量の窒化ケイ素粉
末と、同じく所定量のセリウム系焼結助剤及びその他の
助剤を配合し、これを有機媒体(例えばエチルアルコ−
ル等)中で好ましくは窒化ケイ素質メディアと共に粉砕
混合し、スラリ−を調製する。次に、このスラリ−を乾
燥し、得られた混合粉末を、例えば金型プレス成形、ラ
バ−プレス、押し出し成形、泥しょう鋳込み成形、射出
成形、圧縮成形、ホットプレスなどの通常のセラミック
スの成形手段により目的とする形状に成形し、続いてこ
の成形体を焼成して窒化ケイ素質焼結体を製造する。Next, the method for producing a silicon nitride sintered body of the present invention will be described. First, a predetermined amount of silicon nitride powder and a predetermined amount of cerium-based sintering additive and other auxiliary agents are mixed. , An organic medium such as ethyl alcohol
And the like), preferably by pulverization and mixing with a silicon nitride media to prepare a slurry. Next, this slurry is dried, and the resulting mixed powder is molded into usual ceramics such as die press molding, rubber press, extrusion molding, mud casting, injection molding, compression molding, hot pressing, etc. A desired shape is formed by a means, and then the formed body is fired to produce a silicon nitride sintered body.
【００２５】本発明の方法では、焼成条件として、窒化
珪素の分解を防ぐため、少なくとも0.1MPa(1気圧)以上
で焼成することを特徴とする。0.1MPa未満では、高温下
で窒化珪素が分解するので好ましくない。The method of the present invention is characterized in that the firing condition is to fire at least 0.1 MPa (1 atm) or more in order to prevent decomposition of silicon nitride. If it is less than 0.1 MPa, silicon nitride is decomposed at high temperature, which is not preferable.
【００２６】焼結温度としては、原料粉末及びその混合
比並びに焼結手段によって異なるが、焼結体の緻密化に
は、少なくとも1600℃以上の温度で行う必要がある。焼
結手段としては、公知のいずれの方法も採用することが
できるが、特にガス圧焼結法、ホットプレス法、熱間等
方圧プレス法、常圧焼結法が好ましい。上記製造法によ
れば、理論密度90％以上の焼結体を得ることができ、か
つ焼結体の粒界にセリウム元素が存在することからアル
カリ水溶液に対する耐食性が優れた窒化ケイ素質焼結体
を得ることができる。The sintering temperature varies depending on the raw material powder, the mixing ratio thereof and the sintering means, but it is necessary to densify the sintered body at a temperature of at least 1600 ° C. or higher. As a sintering means, any known method can be adopted, but a gas pressure sintering method, a hot pressing method, a hot isostatic pressing method and an atmospheric pressure sintering method are particularly preferable. According to the above-mentioned production method, a sintered body having a theoretical density of 90% or more can be obtained, and since the cerium element is present in the grain boundaries of the sintered body, the silicon nitride sintered body has excellent corrosion resistance to an alkaline aqueous solution. Can be obtained.
【００２７】本発明に係る窒化ケイ素質焼結体は、窒化
ケイ素質焼結体が本来有している特性(破壊靱性等の機
械的特性、耐熱性、耐熱衝撃性)を損なうことがなく、
しかも高温高圧のアルカリ水溶液に対する耐食性に優れ
たものであり、そのため、従来の窒化ケイ素質焼結体で
は適用できなかった常温又は高温高圧のアルカリ水溶液
を使用する特殊な環境下の構造材料(例えばパルプスラ
リ−用部材、その他アルカリ腐食環境下で使用されるパ
イプ、ベアリング等の構成部材や導電率測定用セル部材
又は導電率測定用電極部材などの耐食性構造部材)とし
て利用できる。The silicon nitride sintered body according to the present invention does not impair the characteristics inherent to the silicon nitride sintered body (mechanical characteristics such as fracture toughness, heat resistance, thermal shock resistance),
Moreover, it has excellent corrosion resistance to high-temperature and high-pressure alkaline aqueous solution, and therefore, it cannot be applied to conventional silicon nitride sintered bodies, and structural materials under a special environment using normal-temperature or high-temperature and high-pressure alkaline aqueous solution (e.g. pulp slurry). -Members, other components such as pipes and bearings used in an alkaline corrosive environment, and corrosion-resistant structural members such as conductivity measuring cell members or conductivity measuring electrode members).
【００２８】[0028]
【実施例】以下、本発明の実施例を比較例及び従来例と
共に挙げ、本発明をより詳細に説明する。EXAMPLES The present invention will be described in more detail below with reference to examples of the present invention together with comparative examples and conventional examples.
【００２９】実施例（試料No.1〜16） 平均粒径：1.0μｍのα型窒化ケイ素粉末と、平均粒
径：0.8μｍの酸化セリウム、炭化セリウム粉末及びそ
の他の助剤粉末Ａ、同Ｂとを表１に示す割合で配合し
(表１、試料No.1〜16参照)、これをエチルアルコ−ル中
で窒化ケイ素質メディアと共に10時間粉砕混合し、スラ
リ−を調製した。このスラリ−を乾燥した後粉末とし、
これを１軸プレスによって100Kgf／cm2の圧力で仮成形
し、続いてCIP(Cold Isostatical Press：冷間等方加工
プレス)により1.5ton／cm2の圧力で本成形した。次に、
この成形体を表２に示す焼成条件下で焼成し、窒化ケイ
素質焼結体を作製した。なお、表２中の“GPS”はガス
圧焼結、“PLS”は常圧焼結、“HIP”は熱間静水圧プレ
ス、“HP”はホットプレスを示す。Examples (Sample Nos. 1 to 16) α-type silicon nitride powder having an average particle diameter of 1.0 μm, cerium oxide, cerium carbide powder and other auxiliary agent powders A and B having an average particle diameter of 0.8 μm. And in the proportions shown in Table 1
(See Table 1, Sample Nos. 1 to 16), and this was pulverized and mixed with the silicon nitride media in ethyl alcohol for 10 hours to prepare a slurry. After drying this slurry into a powder,
This was preliminarily molded under a pressure of 100 Kgf / cm 2 by uniaxial pressing, followed by CIP: were present molded at a pressure of 1.5 ton / cm 2 by (Cold Isostatical Press cold isostatic pressing). next,
This compact was fired under the firing conditions shown in Table 2 to produce a silicon nitride sintered body. In Table 2, “GPS” indicates gas pressure sintering, “PLS” indicates normal pressure sintering, “HIP” indicates hot isostatic pressing, and “HP” indicates hot pressing.
【００３０】得られた各窒化ケイ素質焼結体(試料No.1
〜16)について、密度、強度、耐アルカリ腐食性の材料
特性を評価するため、該焼結体をJIS R 1601に準じてテ
ストピ−ス(試験片)形状に加工し、この試験片の“相対
密度”“強度”“重量減少量”“腐食後強度変化率”を
測定し、その結果を表２に示した。Each of the obtained silicon nitride sintered bodies (Sample No. 1
~ 16), in order to evaluate the material properties of density, strength and alkali corrosion resistance, the sintered body was processed into a test piece (test piece) shape in accordance with JIS R 1601, and the "relative The density, "strength", "weight loss" and "rate of change in strength after corrosion" were measured, and the results are shown in Table 2.
【００３１】“強度”は３点曲げ強度の値(MPa)であ
り、また、“重量減少量”及び“腐食後強度変化率”
は、テフロンセルを有するオ−トクレ−ブ中で「温度：
180℃、圧力：8.6MPa、5重量％水酸化ナトリウム水溶
液、保存時間：7日」の条件下における試験片の“腐食
後重量減少量(％)＝(腐食後の試験片重量／腐食前の試
験片重量)×100”及び“腐食後の強度変化率(％)＝(腐
食後の試験片強度／腐食前の試験片強度)×100”を測定
した値である。なお、重量減少量(％)が小である程、ま
た、腐食後の強度残留率に相当する腐食後の強度変化率
(％)が大である程、アルカリ溶液に対する耐食性が優れ
ていることを示す。"Strength" is the value of three-point bending strength (MPa), and also "weight reduction amount" and "rate of change in strength after corrosion".
In an autoclave with a Teflon cell, "temperature:
180 ° C, pressure: 8.6MPa, 5% by weight sodium hydroxide aqueous solution, storage time: 7 days "," weight loss after corrosion (%) = (weight of test piece after corrosion / before corrosion " It is a value obtained by measuring “test piece weight) × 100” and “strength change rate (%) after corrosion = (test piece strength after corrosion / test piece strength before corrosion) × 100”. The smaller the weight loss (%), the higher the rate of change in strength after corrosion, which is equivalent to the residual rate of strength after corrosion.
The larger (%) indicates that the corrosion resistance to an alkaline solution is more excellent.
【００３２】また、得られた各窒化ケイ素質焼結体(試
料No.1〜16)について、EPMA(Electron probe micro ana
lysis)で観察したところ、粒界相にセリウムを含むシリ
ケ−トなどのセリウム化合物が形成されていることが認
められ、これによって粒界相の溶出が抑制されるものと
考えられる。Further, with respect to each of the obtained silicon nitride sintered bodies (Sample Nos. 1 to 16), EPMA (Electron probe microana
As a result of observation by lysis), it is recognized that a cerium compound such as silicate containing cerium is formed in the grain boundary phase, and this is considered to suppress the elution of the grain boundary phase.
【００３３】そして、該窒化ケイ素質焼結体(試料No.1
〜16)に対するアルカリ水溶液腐食試験(5重量％NaOH水
溶液、180℃／7日間における腐食試験)後の焼結体表面
に表れる腐食相は、極めて薄く、EPMAによればセリウム
元素が濃縮した相となっていること及び腐食後表面粗さ
に大きな変化が表れないことが認められ、腐食後の残留
強度が極めて高いことが認められた。Then, the silicon nitride sintered body (Sample No. 1
~ 16), the corrosion phase appearing on the surface of the sintered body after the alkaline aqueous solution corrosion test (5% by weight NaOH aqueous solution, corrosion test at 180 ° C / 7 days) is extremely thin, and according to EPMA, it is a phase enriched with cerium element. It was confirmed that no significant change was observed in the surface roughness after corrosion, and the residual strength after corrosion was extremely high.
【００３４】上記「EPMAでの観察」及び「アルカリ水溶
液腐食試験」での結果から、セリウム系焼結助剤の添加
により窒化ケイ素焼結体のアルカリ水溶液に対する耐食
性が優れていることが認められた。また、具体的には5
重量％NaOH水溶液、180℃／7日間における腐食減量が0.
5％以下を示し、強度低下が極めて少なかった。From the results of the "observation with EPMA" and the "alkali aqueous solution corrosion test" described above, it was confirmed that the corrosion resistance of the silicon nitride sintered body to the alkaline aqueous solution was excellent by adding the cerium-based sintering aid. . Also, specifically 5
Weight% NaOH aqueous solution, corrosion loss at 180 ℃ / 7 days is 0.
The strength was 5% or less, and the decrease in strength was extremely small.
【００３５】比較例（試料No.17〜21） 比較のため、本発明の範囲外の組成(表１の試料No.17〜
21に示す組成)で前記実施例と同一方法で成形体を作製
し、これを表２に示す焼成条件下で焼成し、窒化ケイ素
質焼結体を得た。この焼結体について、前記実施例と同
様材料特性を測定し、その測定結果を表２に示した。Comparative Examples (Sample Nos. 17 to 21) For comparison, compositions outside the scope of the present invention (Sample No. 17 to Table 1 in Table 1)
The composition shown in FIG. 21) was formed in the same manner as in the above-mentioned example, and the compact was fired under the firing conditions shown in Table 2 to obtain a silicon nitride sintered body. The material properties of this sintered body were measured in the same manner as in the above example, and the measurement results are shown in Table 2.
【００３６】従来例（試料No.22〜25） また、従来の窒化ケイ素質焼結体(従来例)として、従来
よく知られている組成(表１の試料No.22〜25に示す組
成)で前記実施例と同一方法で成形体を作製し、これを
表２に示す焼成条件下で焼成し、窒化ケイ素質焼結体を
得た。この焼結体についても前記実施例と同様材料特性
を測定し、その測定結果を表２に示した。Conventional Example (Sample Nos. 22 to 25) Further, as a conventional silicon nitride sintered body (conventional example), a composition well known in the past (composition shown in Sample Nos. 22 to 25 in Table 1) was used. Then, a molded body was prepared by the same method as in the above-mentioned example, and was fired under the firing conditions shown in Table 2 to obtain a silicon nitride sintered body. The material properties of this sintered body were measured in the same manner as in the above example, and the measurement results are shown in Table 2.
【００３７】[0037]
【表１】 [Table 1]
【００３８】[0038]
【表２】 [Table 2]
【００３９】表２より明らかなように、本発明で特徴と
するセリウム系焼結助剤を特定範囲内で配合した試料N
o.1〜4の実施例では、アルカリ溶液に対する耐食性が優
れた窒化ケイ素質焼結体が得られることが理解できる。
また、セリウム系焼結助剤にその他の助剤Ａ、Ｂを併用
し、セリウム成分比を本発明で特定する範囲内で配合し
た試料No.5〜16の実施例では、アルカリ溶液に対する耐
食性が優れているばかりでなく、より高強度の窒化ケイ
素質焼結体が得られることが理解できる。さらに、試料
No.1〜16の実施例では、具体的には5重量％NaOH水溶
液、180℃／7日間における腐食減量が0.7％以下を示
し、強度低下が極めて少ないことが認められた。As is clear from Table 2, sample N containing the cerium-based sintering aid characterized in the present invention in a specific range
It can be understood that in the examples of o.1 to 4, silicon nitride sintered bodies excellent in corrosion resistance against an alkaline solution can be obtained.
In addition, in the examples of Sample Nos. 5 to 16 in which the other auxiliary agents A and B were used in combination with the cerium-based sintering auxiliary agent and the cerium component ratio was blended within the range specified in the present invention, the corrosion resistance to the alkaline solution was high. It can be understood that not only excellent but also higher strength silicon nitride sintered bodies can be obtained. In addition, the sample
In Examples Nos. 1 to 16, specifically, 5% by weight NaOH aqueous solution, the corrosion weight loss at 180 ° C./7 days was 0.7% or less, and it was confirmed that the strength reduction was extremely small.
【００４０】これに対して、セリウム成分比を本発明で
特定する範囲外で配合した試料No.17、18の比較例及び
セリウム系焼結助剤を配合しない試料No.19〜21の比較
例では、アルカリ溶液に対する耐食性が極めて劣るもの
であった。また、従来の窒化ケイ素質焼結体である試料
No.22〜25の従来例でも、上記比較例と同様アルカリ溶
液に対する耐食性が極めて劣るものであった。On the other hand, Comparative Examples of Samples Nos. 17 and 18 in which the cerium component ratio is out of the range specified in the present invention and Comparative Examples of Samples Nos. Then, the corrosion resistance to the alkaline solution was extremely poor. In addition, a sample that is a conventional silicon nitride sintered body
Also in the conventional examples of Nos. 22 to 25, the corrosion resistance to the alkaline solution was extremely poor as in the comparative example.
【００４１】なお、表２から、焼結後に構成される窒化
ケイ素粒子がαサイアロンやβサイアロン粒子に変化し
ていても、セリウム成分比が本発明の範囲内であれば同
様にアルカリ溶液に対する耐食性の向上が認められる
(表１、表２の試料No.13〜15参照)。It should be noted from Table 2 that even if the silicon nitride particles formed after sintering are changed to α-sialon and β-sialon particles, if the cerium component ratio is within the range of the present invention, the corrosion resistance to an alkaline solution is the same. Improvement is recognized
(See Sample Nos. 13 to 15 in Tables 1 and 2).
【００４２】[0042]
【発明の効果】本発明は、以上詳記したとおり、窒化ケ
イ素と焼結助剤を含む添加剤からなる窒化ケイ素質焼結
体において、 ・焼結助剤としてセリウムの単体又はその化合物を使用
する点、及び ・焼結助剤を含む添加剤に対するセリウム成分比を適性
範囲とする点、を特徴とし、これにより窒化ケイ素質焼
結体が本来有している特性(破壊靱性などの機械的特
性、耐熱性、耐熱衝撃性)を損なうことがなく、アルカ
リ水溶液に対する耐食性に優れた窒化ケイ素質焼結体を
提供することができる。INDUSTRIAL APPLICABILITY As described in detail above, the present invention provides a silicon nitride-based sintered body comprising silicon nitride and an additive containing a sintering aid, wherein cerium alone or a compound thereof is used as the sintering aid. And that the cerium component ratio with respect to the additive including the sintering aid is in an appropriate range, which allows the silicon nitride sintered body to have its own characteristics (mechanical properties such as fracture toughness). It is possible to provide a silicon nitride-based sintered body that is excellent in corrosion resistance to an alkaline aqueous solution without impairing its properties, heat resistance, and thermal shock resistance.
【００４３】そして、本発明の窒化ケイ素質焼結体は、
従来の窒化ケイ素質焼結体では適用できなかった常温又
は高温高圧のアルカリ水溶液を使用する特殊な環境下の
構造材料(例えばパルプスラリ−用部材、その他アルカ
リ腐食環境下で使用されるパイプ、ベアリング等の構成
部材や導電率測定用セル部材又は導電率測定用電極部材
などの耐食性構造部材)として利用できるものであっ
て、その工業的価値は極めて大きい。The silicon nitride sintered body of the present invention is
Structural materials under a special environment that uses alkaline aqueous solution at room temperature or high temperature and pressure, which could not be applied to conventional silicon nitride sintered bodies (e.g. pulp slurry members, other pipes used in alkaline corrosive environments, bearings, etc.) (Corrosion-resistant structural member such as a constituent member of, a conductivity measuring cell member, or a conductivity measuring electrode member), and its industrial value is extremely large.
Claims (3)
ウムの単体又はその化合物及び(2)マグネシウム、カル
シウム、アルミニウム、ジルコニウム、ハフニウム、イ
ットリウム又はその他の希土類元素の単体もしくはその
酸化物、窒化物、炭化物などの化合物ないしはこれらの
混合物、よりなる焼結助剤を含む添加剤であって、添加
した全ての添加剤に対するセリウム成分の酸化物換算重
量比「CeO2／(CeO2＋X)、X：セリウム成分以外に添加し
た全ての添加成分の酸化物換算重量」が0.1〜1.0である
添加剤：1〜40重量％(酸化物換算)からなる窒化ケイ素
質焼結体であって、理論密度に対する相対比が90％以上
の焼結体で、且つ焼成中に生成したセリウム成分が粒界
相に存在してなることを特徴とする窒化ケイ素質焼結
体。1. Silicon nitride: 60 to 99% by weight, (1) a simple substance of cerium or a compound thereof, and (2) a simple substance of magnesium, calcium, aluminum, zirconium, hafnium, yttrium or other rare earth elements or an oxide thereof. , A compound such as a nitride or a carbide, or a mixture thereof, and an additive containing a sintering aid, wherein the oxide conversion weight ratio of the cerium component to all the added additives is “CeO 2 / (CeO 2 + X ), X: 0.1 to 1.0 in terms of oxide equivalent weight of all added components other than cerium component: 1 to 40% by weight (in terms of oxide) of a silicon nitride sintered body. A silicon nitride sintered body characterized by being a sintered body having a relative ratio to the theoretical density of 90% or more, and having a cerium component generated during firing in a grain boundary phase.
ウムの単体又はその化合物及び(2)マグネシウム、カル
シウム、アルミニウム、ジルコニウム、ハフニウム、イ
ットリウム又はその他の希土類元素の単体もしくはその
酸化物、窒化物、炭化物などの化合物ないしはこれらの
混合物、よりなる焼結助剤を含む添加剤であって、添加
した全ての添加剤に対するセリウム成分の酸化物換算重
量比「CeO2／(CeO2＋X)、X：セリウム成分以外に添加し
た全ての添加成分の酸化物換算重量」が0.1〜1.0である
添加剤を酸化物換算で1〜40重量％配合し、0.1MPa以上
で非酸化雰囲気中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。2. In 60 to 99% by weight of silicon nitride, (1) a simple substance of cerium or a compound thereof and (2) a simple substance of magnesium, calcium, aluminum, zirconium, hafnium, yttrium or other rare earth elements or an oxide thereof. , A compound such as a nitride or a carbide, or a mixture thereof, and an additive containing a sintering aid, wherein the oxide conversion weight ratio of the cerium component to all the added additives is “CeO 2 / (CeO 2 + X ), X: 1 to 40% by weight in terms of oxide of an additive having an oxide equivalent weight of 0.1 to 1.0 of all the added components other than the cerium component, and at 0.1 MPa or more in a non-oxidizing atmosphere. A method for manufacturing a silicon nitride sintered body, which comprises firing.
アルカリ水溶液に対する耐食性を必要とするパイプ、ノ
ズル、ベアリングなどの構成部材、導電率測定用セル部
材又は導電率測定用電極部材などの耐食性構造部材とし
て利用する方法。3. The silicon nitride sintered body according to claim 1,
A method of using as a corrosion-resistant structural member such as a pipe, a nozzle, a constituent member such as a bearing, a cell member for conductivity measurement or an electrode member for conductivity measurement, which requires corrosion resistance to an alkaline aqueous solution.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6183909A JPH0826830A (en) | 1994-07-13 | 1994-07-13 | Silicon nitride-based sintered compact, its production and method for its utilization |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6183909A JPH0826830A (en) | 1994-07-13 | 1994-07-13 | Silicon nitride-based sintered compact, its production and method for its utilization |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0826830A true JPH0826830A (en) | 1996-01-30 |
Family
ID=16143942
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP6183909A Pending JPH0826830A (en) | 1994-07-13 | 1994-07-13 | Silicon nitride-based sintered compact, its production and method for its utilization |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0826830A (en) |
-
1994
- 1994-07-13 JP JP6183909A patent/JPH0826830A/en active Pending
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