JPS6319472B2 - - Google Patents
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- Publication number
- JPS6319472B2 JPS6319472B2 JP58111489A JP11148983A JPS6319472B2 JP S6319472 B2 JPS6319472 B2 JP S6319472B2 JP 58111489 A JP58111489 A JP 58111489A JP 11148983 A JP11148983 A JP 11148983A JP S6319472 B2 JPS6319472 B2 JP S6319472B2
- Authority
- JP
- Japan
- Prior art keywords
- oxide
- weight
- sintering
- silicon nitride
- aid
- 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
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- 238000005245 sintering Methods 0.000 claims description 28
- 239000012752 auxiliary agent Substances 0.000 claims description 21
- 229910052581 Si3N4 Inorganic materials 0.000 claims description 19
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims description 19
- 239000000843 powder Substances 0.000 claims description 11
- 239000000203 mixture Substances 0.000 claims description 10
- 229910000420 cerium oxide Inorganic materials 0.000 claims description 9
- BMMGVYCKOGBVEV-UHFFFAOYSA-N oxo(oxoceriooxy)cerium Chemical compound [Ce]=O.O=[Ce]=O BMMGVYCKOGBVEV-UHFFFAOYSA-N 0.000 claims description 9
- MRELNEQAGSRDBK-UHFFFAOYSA-N lanthanum(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[La+3].[La+3] MRELNEQAGSRDBK-UHFFFAOYSA-N 0.000 claims description 7
- 239000012535 impurity Substances 0.000 claims description 6
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 claims description 6
- 229910001928 zirconium oxide Inorganic materials 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 claims description 5
- PLDDOISOJJCEMH-UHFFFAOYSA-N neodymium(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Nd+3].[Nd+3] PLDDOISOJJCEMH-UHFFFAOYSA-N 0.000 claims description 5
- 229910052779 Neodymium Inorganic materials 0.000 claims description 3
- 238000000465 moulding Methods 0.000 claims description 3
- QEFYFXOXNSNQGX-UHFFFAOYSA-N neodymium atom Chemical compound [Nd] QEFYFXOXNSNQGX-UHFFFAOYSA-N 0.000 claims description 3
- SIWVEOZUMHYXCS-UHFFFAOYSA-N oxo(oxoyttriooxy)yttrium Chemical compound O=[Y]O[Y]=O SIWVEOZUMHYXCS-UHFFFAOYSA-N 0.000 claims description 3
- MMKQUGHLEMYQSG-UHFFFAOYSA-N oxygen(2-);praseodymium(3+) Chemical compound [O-2].[O-2].[O-2].[Pr+3].[Pr+3] MMKQUGHLEMYQSG-UHFFFAOYSA-N 0.000 claims description 3
- 229910003447 praseodymium oxide Inorganic materials 0.000 claims description 3
- 229910052777 Praseodymium Inorganic materials 0.000 claims description 2
- 229910052746 lanthanum Inorganic materials 0.000 claims description 2
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 claims description 2
- PUDIUYLPXJFUGB-UHFFFAOYSA-N praseodymium atom Chemical compound [Pr] PUDIUYLPXJFUGB-UHFFFAOYSA-N 0.000 claims description 2
- 229910001404 rare earth metal oxide Inorganic materials 0.000 claims description 2
- 239000003795 chemical substances by application Substances 0.000 claims 1
- 238000000034 method Methods 0.000 description 18
- 230000000052 comparative effect Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 238000001272 pressureless sintering Methods 0.000 description 4
- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 238000007731 hot pressing Methods 0.000 description 3
- 230000001737 promoting effect Effects 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 229910052684 Cerium Inorganic materials 0.000 description 2
- 238000005452 bending Methods 0.000 description 2
- 239000000919 ceramic Substances 0.000 description 2
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 229910001873 dinitrogen Inorganic materials 0.000 description 2
- 229920000609 methyl cellulose Polymers 0.000 description 2
- 239000001923 methylcellulose Substances 0.000 description 2
- 235000010981 methylcellulose Nutrition 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 229910052761 rare earth metal Inorganic materials 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- 229910052772 Samarium Inorganic materials 0.000 description 1
- HGNKUPTVPAMREU-UHFFFAOYSA-N [Nd].[Pr].[La] Chemical compound [Nd].[Pr].[La] HGNKUPTVPAMREU-UHFFFAOYSA-N 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000006355 external stress Effects 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000001746 injection moulding Methods 0.000 description 1
- 229910052747 lanthanoid Inorganic materials 0.000 description 1
- 150000002602 lanthanoids Chemical class 0.000 description 1
- 239000000395 magnesium oxide Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000013001 point bending Methods 0.000 description 1
- 150000002910 rare earth metals Chemical class 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
- FKTOIHSPIPYAPE-UHFFFAOYSA-N samarium(III) oxide Inorganic materials [O-2].[O-2].[O-2].[Sm+3].[Sm+3] FKTOIHSPIPYAPE-UHFFFAOYSA-N 0.000 description 1
- XGVXKJKTISMIOW-ZDUSSCGKSA-N simurosertib Chemical compound N1N=CC(C=2SC=3C(=O)NC(=NC=3C=2)[C@H]2N3CCC(CC3)C2)=C1C XGVXKJKTISMIOW-ZDUSSCGKSA-N 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Landscapes
- Ceramic Products (AREA)
Description
本発明は、靭性および強度にすぐれた窒化けい
素焼結体の製造法に関する。
窒化けい素（Si3N4）焼結体は、高温域での強
度・耐摩耗性等にすぐれ、熱膨張係数が小さく、
かつ化学的にも安定なことから、昨今内燃機関、
ガスタービン、ラジアントチユーブ、その他の高
温用途において従来の耐熱合金に代る新材料とし
て注目されている。窒化けい素粉末はそれ自体で
は焼結性に乏しいので、焼結体の製造には焼結助
剤を配合するのが一般である。これまでにも焼結
の促進、焼結体の高温強度改善等を目的として焼
結助剤の配合組成について種々研究がなされてお
り、例えば、イツトリウム酸化物（Y2O3）、マグ
ネシア（MgO）、あるいはアルミナ（Al2O3）な
どが有用な助剤として知られている。
しかるに、一般にセラミツクは構成原子の結合
が主として共有結合またはイオン結合（通常はこ
れらの結合の混成）であるため、高弾性率、高強
度を有する反面、結晶構造が複雑で、空間的に隙
間の多い構造を有する。このため一般のセラミツ
クは金属と異なり低温での転位の移動が不可能
で、脆性と呼ばれる挙動を示すのが大きな欠点と
なつている。この脆性に対しては、例えば焼結体
内に不均質相を形成させておけば、外部からの応
力によるクラツク進展の際に、分散する不均質相
によつて破壊エネルギーが吸収され破壊靭性値の
向上をみる、との見解も発表されており、また添
加剤の配合による脆性改善のこころみもなされて
いる。
しかしながら、窒化けい素焼結体については、
これまで靭性向上について充分な成果をみるに到
らず、その破壊靭性値（KIC）は6MN・m-3/2を
越えず、通常３〜4MN・m-3/2程度にとどまつて
いるのが実情である。
本発明は、窒化けい素焼結体の破壊靭性値を改
善し、かつ強度を高めるためになされたものであ
る。
本発明の窒化けい素焼結体の製造法は、窒化け
い素粉末に、焼結助剤として、
イツトリウム酸化物（Y2O3）〔以下、「Ａ助剤」
と称する〕と、
ランタン・ネオジム・プラセオジム複酸化物も
しくはランタン酸化物・ネオジム酸化物・プラセ
オジム酸化物混合物（以下、「Ｂ助剤」と称する）
と、
ジルコニウム酸化物（ZrO2）もしくは部分安
定化ジルコニウム酸化物（以下、「Ｃ助剤」と称
する）とを、Ａ助剤は２〜13重量％、Ｂ助剤は２
〜18重量％、Ａ助剤とＢ助剤の合計量は５〜28重
量％、およびＣ助剤は７〜30重量％となるように
窒化けい素粉末に配合し、成形・焼結するもので
ある。
焼結助剤として配合されるＡ助剤およびＢ助剤
は焼結の促進および焼結体の強度改善等の効果を
有する。この添加効果を十分に得るためには、少
くともＡ助剤は２重量％、Ｂ助剤は２重量％で、
両者の合計量は５重量％であることを要する。好
ましくは、Ａ助剤は３重量％以上、Ｂ助剤は４重
量％以上であつて、その合計量は７重量％以上で
ある。
Ｂ助剤であるランタン・ネオジム・プラセオジ
ム複酸化物もしくは酸化物混合物は、焼結体の品
質の点から、酸化物換算値で、20〜80重量％のラ
ンタン酸化物（La2O3）、20〜50重量％のネオジ
ム酸化物（Nd2O3）および３〜20重量％のプラセ
オジム酸化物（Pr6O11）からなり、不純物とし
て付随するセリウム酸化物（CeO）は15重量％以
下、その他の希土類酸化物は５重量％以下である
ものが好ましく使用される。このものは、天然に
産出するランタニド系列希土類（酸化物）からセ
リウム（酸化物）を除去することにより得られる
ものであり、希土類単金属の酸化物よりも安価に
製造することができる。の複酸化物もしくは酸化
物混合物にセリウム（酸化物）が含まれること
は、焼結体の品質上好ましくないが、酸化物換算
で15重量％以下であれば実害はなく、またサマリ
ウム（Sm）その他の希土類元素の残留も５重量
％以下なら差支えない。
Ｃ助剤は、焼結促進のほかに、焼結体の破壊靭
性値の向上に奏効する助剤であり、このためには
少くとも７重量％を必要とする。更に好ましくは
９重量％以上配合される。なお、Ｃ助剤であるジ
ルコニウム酸化物を部分安定化ジルコニウム酸化
物とは、破壊靭性値の改善、焼結性向上の点では
同効物質とみなし得るもので、両者は複合的に使
用してもよい。
上記各助剤は、それぞれ配合割合の増加ととも
に添加効果の向上をみるが、あまり多く配合して
も、配合量の割に効果の増加が少く、かつ混合物
中に占める窒化けい素粉末の比率が低下すること
に伴つて窒化けい素焼結体としての特徴が弱ま
る。このために、Ａ助剤は13重量％、Ｂ助剤は18
重量％、Ａ助剤とＢ助剤の合計量は28重量％、お
よびＣ助剤は30重量％をそれぞれ上限とすべきで
ある。一般的には、Ａ助剤は８重量％まで、Ｂ助
剤は16重量％まで、Ａ助剤とＢ助剤の合計は20重
量％まで、またＣ助剤は20重量％までの配合によ
り好結果を得ることができる。
主原料である窒化けい素粉末には、結晶構造に
α型とβ型とがあり、周知のように焼結体の強度
等の点から焼結体内粒界層の結晶化助長のために
α型が有利であり、好ましくはα化率約90％以上
のものが使用される。
本発明によれば、窒化けい素粉末に、前記各助
剤を各々所要量配合し、なお必要ならば適当な成
形助剤を添加した混合物を、常法に従つて成形、
焼結することにより目的とする焼結体を得る。
「成形・焼結する」と言うのは、適用されるプロ
セスにより、例えばホツトプレス法や熱間静水圧
焼結法などのように、成形と焼結とが一工程で行
なわれる場合や、常圧焼結法のように所定形状へ
の成形と、成形体の焼結とが各別の工程として行
なわれる場合を含む。いづれのプロセスも通常の
条件で行なえばよく、例えばホツトプレス法で
は、所定形状の型内に混合物を充填し、適当な加
圧力、焼結温度（例えば200〜400Kgｆ／cm2、1600
〜1850℃）にて焼結を達成する。熱間静水圧焼結
法では、例えば加圧力500〜2500Kgｆ／cm2、温度
1600〜1850℃で行なわれる。また、常圧焼結法で
は、前記助剤とともにメチルセルロースなどの成
形助剤が適量加えられた混合物を適宜の成形法、
例えば一軸プレス、ラバープレス、射出成形など
に付して所望の成形体を得たのち、窒素ガスなど
の不活性雰囲気下、例えば雰囲気圧力１〜10Kg
ｆ／cm2、温度1600〜1850℃にて焼結を完了する。
次に本発明の実施例について説明する。
実施例
〔A〕 ホツトプレス法
窒化けい素粉末（α化率95％、平均粒径0.6μ
ｍ）に焼結助剤を配合し、ホツトプレス法によ
り、加圧力400Kgｆ／cm2、温度1800℃に１時間
保持して焼結体（40mm×20mm×６mm）を得た。
〔B〕 常圧焼結法
窒化けい素粉末（α化率95％、平均粒径0.6μ
ｍ）に焼結助剤、および成形助剤として0.5％
メチルセルロース水溶液を配合（窒化けい素粉
末30ｇに対して10c.c.）、混合し、一軸プレス法
にて円板体を成形したのち、常圧焼結法によ
り、窒素ガス雰囲気（圧力1.3Kgｆ／cm2）中、
1750℃に２時間保持して円板状焼結体（直径50
mm×厚さ６mm）を得た。
上記各焼結法により得られた焼結体のそれぞれ
について破壊靭性値（KIC）および曲げ強度を測
定した。破壊靭性値の測定はKnoop―Inden―
tation―Strength法に準処した。曲げ強度試験
は、３mm×３mm×40mmの試片を使用し、３点曲げ
法（スパン距離30mm）にて行つた。
焼結助剤の配合および試験結果を第１表に示
す。
表中、「製法」欄の「Ａ」はホツトプレス法、
「Ｂ」は常圧焼結法を意味する。試番(1)〜(6)は発
明例、101〜109は比較例である。発明例６におけ
るＢ助剤に占める不純分CeOの割合は7.9％、
Sm2O3のそれは2.6％である。他方、比較例101〜
109のうち、101はＣ助剤が欠けている例、102と
106はＢ助剤とＣ助剤が欠けている例、103と107
はＢ助剤が欠けている例、104はＡ，ＢおよびＣ
助剤を含んでいるが、Ａ助剤とＢ助剤の合計が不
足している例、105と108はＡ，ＢおよびＣ助剤を
含んでいるが、Ｂ助剤に付随する不純分（CeO，
Sm2O3）が本発明の上限規定からはずれている
例、109はマグネシアを助剤とした例である。な
お、比較例105における不純分CeOのＢ助剤に占
める割合は18.2％であり、108における不純分
CeOのＢ助剤に占める割合は22.2％、Sm2O3のそ
れは8.3％である。
表に示されるように、本発明により得られる焼
結体は、成形・焼結法のいかんにかかわらず、従
来の水準を大きく越える高破壊靭性値を有し、か
つ強度についても同じ成形・焼結法による従来材
にまさつている。
The present invention relates to a method for producing a silicon nitride sintered body having excellent toughness and strength. Silicon nitride (Si 3 N 4 ) sintered bodies have excellent strength and wear resistance in high temperature ranges, and have a small coefficient of thermal expansion.
Because it is also chemically stable, internal combustion engines are becoming popular these days.
It is attracting attention as a new material to replace conventional heat-resistant alloys in gas turbines, radiant tubes, and other high-temperature applications. Since silicon nitride powder itself has poor sintering properties, it is common to add a sintering aid to it when producing a sintered body. Various studies have been conducted on the composition of sintering aids for the purpose of promoting sintering and improving the high-temperature strength of sintered bodies. For example, yttrium oxide (Y 2 O 3 ), magnesia (MgO ) or alumina (Al 2 O 3 ) are known as useful auxiliaries. However, in general, the bonds of the constituent atoms of ceramics are mainly covalent bonds or ionic bonds (usually a hybrid of these bonds), so while they have high elastic modulus and high strength, they have a complex crystal structure and are prone to spatial gaps. It has many structures. For this reason, unlike metals, general ceramics are unable to move dislocations at low temperatures, and exhibit a behavior called brittleness, which is a major drawback. To prevent this brittleness, for example, if a heterogeneous phase is formed in the sintered body, when a crack develops due to external stress, the fracture energy will be absorbed by the dispersed heterogeneous phase and the fracture toughness value will decrease. It has also been announced that there will be an improvement in the strength, and efforts have also been made to improve brittleness by adding additives. However, regarding silicon nitride sintered bodies,
Until now, sufficient results have not been achieved in improving toughness, and the fracture toughness value (K IC ) does not exceed 6 MN・m -3/2 , and usually remains at around 3 to 4 MN・m -3/2 . That is the reality. The present invention was made in order to improve the fracture toughness value and increase the strength of silicon nitride sintered bodies. The method for producing a silicon nitride sintered body of the present invention includes adding yttrium oxide (Y 2 O 3 ) as a sintering aid to silicon nitride powder (hereinafter referred to as "A aid").
] and a lanthanum-neodymium-praseodymium double oxide or a mixture of lanthanum oxide, neodymium oxide, and praseodymium oxide (hereinafter referred to as "Auxiliary B")
and zirconium oxide (ZrO 2 ) or partially stabilized zirconium oxide (hereinafter referred to as "C auxiliary agent"), 2 to 13% by weight of A auxiliary agent and 2 to 13% by weight of B auxiliary agent.
~18% by weight, the total amount of A and B auxiliaries is 5 to 28% by weight, and C auxiliary is 7 to 30% by weight, mixed with silicon nitride powder, and then molded and sintered. It is. A auxiliary agent and B auxiliary agent blended as sintering aids have effects such as promoting sintering and improving the strength of the sintered body. In order to fully obtain this addition effect, at least 2% by weight of auxiliary agent A and 2% by weight of auxiliary agent B,
The total amount of both is required to be 5% by weight. Preferably, the amount of auxiliary agent A is 3% by weight or more, the amount of auxiliary agent B is 4% or more by weight, and the total amount thereof is 7% or more by weight. From the viewpoint of the quality of the sintered body, the lanthanum/neodymium/praseodymium double oxide or oxide mixture that is the auxiliary agent B contains 20 to 80% by weight of lanthanum oxide (La 2 O 3 ) in terms of oxide value. Consisting of 20-50% by weight of neodymium oxide (Nd 2 O 3 ) and 3-20% by weight of praseodymium oxide (Pr 6 O 11 ), with 15% by weight or less of cerium oxide (CeO) accompanying as an impurity, Other rare earth oxides are preferably used in an amount of 5% by weight or less. This material is obtained by removing cerium (oxide) from naturally occurring lanthanide series rare earths (oxides), and can be produced at a lower cost than rare earth single metal oxides. Containing cerium (oxide) in the double oxide or oxide mixture is not desirable in terms of the quality of the sintered body, but if it is less than 15% by weight in terms of oxide, there is no actual harm, and samarium (Sm) There is no problem if the remaining rare earth elements are 5% by weight or less. The C auxiliary agent is an auxiliary agent that is effective in improving the fracture toughness value of the sintered body in addition to promoting sintering, and for this purpose, at least 7% by weight is required. More preferably, it is blended in an amount of 9% by weight or more. In addition, zirconium oxide, which is a C auxiliary agent, and partially stabilized zirconium oxide can be considered to be equivalent substances in terms of improving fracture toughness and improving sinterability, and both can be used in combination. Good too. The effect of adding each of the above auxiliary agents improves as the mixing ratio increases, but even if too much is added, the effect increases little compared to the mixing amount, and the ratio of silicon nitride powder in the mixture increases. As the value decreases, the characteristics of the silicon nitride sintered body weaken. For this, the A auxiliary is 13% by weight and the B auxiliary is 18% by weight.
By weight, the total amount of A and B coagents should be up to 28 wt.%, and C coagent 30 wt.%, respectively. In general, the amount of A auxiliary is up to 8% by weight, the B auxiliary is up to 16% by weight, the total of A and B auxiliaries is up to 20% by weight, and the C auxiliary is up to 20% by weight. Good results can be obtained. Silicon nitride powder, which is the main raw material, has an α-type crystal structure and a β-type crystal structure.As is well known, from the viewpoint of the strength of the sintered body, α Types are advantageous, and those with a pregelatinization rate of about 90% or more are preferably used. According to the present invention, a mixture of silicon nitride powder mixed with the required amounts of each of the above-mentioned auxiliary agents and, if necessary, an appropriate molding auxiliary agent, is molded according to a conventional method.
A desired sintered body is obtained by sintering.
“Forming and sintering” depends on the process being applied, for example, when forming and sintering are performed in one step, such as hot pressing or hot isostatic sintering, or when forming and sintering are performed in one step, such as in hot pressing or hot isostatic sintering, or This includes a case where forming into a predetermined shape and sintering the molded body are performed as separate steps, such as in a sintering method. Either process can be carried out under normal conditions; for example, in the hot press method, the mixture is filled into a mold of a predetermined shape, and the pressure and sintering temperature are adjusted to an appropriate pressure (e.g. 200 to 400 Kgf/cm 2 , 1600 kgf/cm 2 ).
Achieve sintering at ~1850℃). In the hot isostatic pressure sintering method, for example, the pressure is 500 to 2500 Kgf/cm 2 and the temperature is
It is carried out at 1600-1850℃. In addition, in the pressureless sintering method, a mixture to which an appropriate amount of a forming aid such as methyl cellulose is added together with the above-mentioned aid is processed by an appropriate forming method,
For example, after obtaining a desired molded body by uniaxial press, rubber press, injection molding, etc., under an inert atmosphere such as nitrogen gas, for example, at an atmospheric pressure of 1 to 10 kg.
Sintering is completed at f/cm 2 and a temperature of 1600 to 1850°C. Next, examples of the present invention will be described. Example [A] Hot press method Silicon nitride powder (gelatinization rate 95%, average particle size 0.6μ
A sintering aid was added to m), and a sintered body (40 mm x 20 mm x 6 mm) was obtained by hot pressing at a pressure of 400 Kgf/cm 2 and a temperature of 1800° C. for 1 hour. [B] Pressureless sintering method Silicon nitride powder (gelatinization rate 95%, average particle size 0.6μ
m) as a sintering aid and a forming aid of 0.5%
A methyl cellulose aqueous solution (10 c.c. for 30 g of silicon nitride powder) was mixed and formed into a disc using a uniaxial press method, followed by pressureless sintering in a nitrogen gas atmosphere (pressure 1.3 Kgf/ cm2 ) medium,
The disc-shaped sintered body (diameter 50
mm x thickness 6 mm) was obtained. The fracture toughness value (K IC ) and bending strength of each of the sintered bodies obtained by the above-mentioned sintering methods were measured. Measurement of fracture toughness value is done by Knoop―Inden―
tation-Strength method. The bending strength test was conducted using a 3 mm x 3 mm x 40 mm specimen using a three-point bending method (span distance 30 mm). The formulation of the sintering aid and the test results are shown in Table 1. In the table, “A” in the “Manufacturing method” column indicates the hot press method.
"B" means pressureless sintering method. Trial numbers (1) to (6) are invention examples, and trial numbers 101 to 109 are comparative examples. The proportion of impurity CeO in the B auxiliary agent in Invention Example 6 was 7.9%,
That of Sm2O3 is 2.6%. On the other hand, comparative example 101~
Out of 109, 101 are cases where C auxiliary is missing, 102 and
106 is an example where B and C auxiliaries are missing, 103 and 107
is an example where B auxiliary is missing, 104 is A, B and C
Examples 105 and 108 contain auxiliaries, but the total of auxiliary A and auxiliary B is insufficient. Examples 105 and 108 contain auxiliaries A, B, and C, but impurities accompanying auxiliary B ( CeO,
Sm 2 O 3 ) is outside the upper limit of the present invention, and No. 109 is an example in which magnesia is used as an auxiliary agent. In addition, the ratio of impurity CeO to B auxiliary agent in Comparative Example 105 is 18.2%, and the ratio of impurity CeO in Comparative Example 108 is 18.2%.
The proportion of CeO in the B auxiliary agent is 22.2%, and that of Sm 2 O 3 is 8.3%. As shown in the table, the sintered body obtained by the present invention has a high fracture toughness value that far exceeds the conventional level, regardless of the forming and sintering method, and has the same strength as the forming and sintering method. It is superior to conventional materials made using the binding method.
【表】【table】
【表】
以上のように、本発明により得られる窒化けい
素焼結体は、従来材に著しくまさる高破壊靭性
値、高強度を有するので、各種構造部材、工具な
どに好適で、従来材では得られぬ安定した耐久性
を保証することができる。[Table] As described above, the silicon nitride sintered body obtained by the present invention has high fracture toughness and high strength that are significantly superior to conventional materials, so it is suitable for various structural members, tools, etc. It can guarantee unparalleled and stable durability.
Claims (1)
焼結を行う焼結体の製造法において、 イツトリウム酸化物（以下、「Ａ助剤」と称す
る）と、 酸化物換算値で20〜80重量％のランタン酸化
物、20〜50重量％のネオジム酸化物および３〜20
重量％のプラセオジム酸化物からなり、不純物と
して付随するセリウム酸化物は15重量％以下、そ
の他の希土類酸化物は５重量％以下であるランタ
ン・ネオジム・プラセオジム複酸化物もしくはラ
ンタン酸化物・ネオジム酸化物・プラセオジム酸
化物の混合物（以下、「Ｂ助剤」と称する）と、 ジルコニウム酸化物もしくは部分安定化ジルコ
ニウム酸化物（以下、「Ｃ助剤）と称する）とを
焼結助剤として、 Ａ助剤は２〜13重量％、Ｂ助剤は２〜18重量
％、Ａ助剤とＢ助剤との合計量は５〜28重量％、
およびＣ助剤は７〜30重量％となるように窒化け
い素粉末に配合されることを特徴とする窒化けい
素焼結体の製造方法。[Claims] 1. Molding and molding by adding a sintering aid to silicon nitride powder
In the method for producing a sintered body, yttrium oxide (hereinafter referred to as "A aid"), 20 to 80% by weight of lanthanum oxide, and 20 to 50% by weight of neodymium in oxide equivalent value are used. oxide and 3-20
Lanthanum/neodymium/praseodymium double oxide or lanthanum oxide/neodymium oxide, consisting of 15% by weight or less of cerium oxide and 5% or less of other rare earth oxides by weight, including cerium oxide as an impurity.・A mixture of praseodymium oxide (hereinafter referred to as “A aid”) and zirconium oxide or partially stabilized zirconium oxide (hereinafter referred to as “C aid”) as a sintering aid; The agent is 2 to 13% by weight, the B auxiliary is 2 to 18% by weight, the total amount of A and B auxiliaries is 5 to 28% by weight,
A method for producing a silicon nitride sintered body, characterized in that the auxiliary agent C is blended into the silicon nitride powder in an amount of 7 to 30% by weight.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58111489A JPS605076A (en) | 1983-06-21 | 1983-06-21 | Manufacture of silicon nitride sintered body |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58111489A JPS605076A (en) | 1983-06-21 | 1983-06-21 | Manufacture of silicon nitride sintered body |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS605076A JPS605076A (en) | 1985-01-11 |
| JPS6319472B2 true JPS6319472B2 (en) | 1988-04-22 |
Family
ID=14562560
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP58111489A Granted JPS605076A (en) | 1983-06-21 | 1983-06-21 | Manufacture of silicon nitride sintered body |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS605076A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0772106B2 (en) * | 1985-11-20 | 1995-08-02 | 京セラ株式会社 | Silicon nitride sintered body and method for manufacturing the same |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS553397A (en) * | 1978-06-15 | 1980-01-11 | Gte Laboratories Inc | Si3n4 having high temperature strength and its manufacture |
| JPS5771871A (en) * | 1980-10-20 | 1982-05-04 | Sumitomo Electric Industries | Tenacious ceramic tool material and manufacture |
-
1983
- 1983-06-21 JP JP58111489A patent/JPS605076A/en active Granted
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS553397A (en) * | 1978-06-15 | 1980-01-11 | Gte Laboratories Inc | Si3n4 having high temperature strength and its manufacture |
| JPS5771871A (en) * | 1980-10-20 | 1982-05-04 | Sumitomo Electric Industries | Tenacious ceramic tool material and manufacture |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS605076A (en) | 1985-01-11 |
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