JPH0822730B2 - Method for producing silicon nitride powder - Google Patents
Method for producing silicon nitride powderInfo
- Publication number
- JPH0822730B2 JPH0822730B2 JP1288549A JP28854989A JPH0822730B2 JP H0822730 B2 JPH0822730 B2 JP H0822730B2 JP 1288549 A JP1288549 A JP 1288549A JP 28854989 A JP28854989 A JP 28854989A JP H0822730 B2 JPH0822730 B2 JP H0822730B2
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- Japan
- Prior art keywords
- silicon nitride
- nitride powder
- amount
- oxygen
- sintered body
- Prior art date
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Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、高温強度と耐摩耗性に優れた窒化ケイ素焼
結体を与え得る易焼結性の窒化ケイ素粉末を金属シリコ
ン直接窒化法で製造する方法に関する。DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention uses a metal silicon direct nitriding method to sinter easily sinterable silicon nitride powder capable of providing a silicon nitride sintered body excellent in high-temperature strength and wear resistance. It relates to a method of manufacturing.
窒化ケイ素焼結体は、高温強度、硬度、耐腐食性、耐
熱衝撃性などに優れた素材であり、各種構造部材として
幅広い用途が期待されている。The silicon nitride sintered body is a material excellent in high-temperature strength, hardness, corrosion resistance, thermal shock resistance, and the like, and is expected to have a wide range of uses as various structural members.
窒化ケイ素焼結体は、通常窒化ケイ素粉末に焼結助剤
を混合し、プレス成形、射出成形、押し出し成形などに
よって成形体とし、この成形体を焼結することによって
製造される。The silicon nitride sintered body is usually manufactured by mixing a silicon nitride powder with a sintering aid to obtain a molded body by press molding, injection molding, extrusion molding or the like, and sintering the molded body.
これらの各手法において窒化ケイ素焼結体を製造する
場合、原料となる窒化ケイ素粉末の粉体特性、特に酸素
量が焼結性及び得られた焼結体の特性に大きく影響する
ことが知られている。すなわち、一般に酸素量の多い窒
化ケイ素粉末（例えば金属シリコン直接窒化法で製造さ
れた窒化ケイ素粉末）は易焼結性であるが十分な高温強
度が得られない。また、酸素量の少ない窒化ケイ素粉末
（例えばハロゲン化ケイ素法で製造された窒化ケイ素粉
末）は難焼結性であり、十分に緻密化させることが難し
い。When producing a silicon nitride sintered body by each of these methods, it is known that the powder characteristics of the silicon nitride powder as a raw material, particularly the amount of oxygen, greatly affects the sinterability and the characteristics of the obtained sintered body. ing. That is, generally, a silicon nitride powder having a large amount of oxygen (for example, a silicon nitride powder manufactured by a metal silicon direct nitriding method) is easily sinterable, but sufficient high temperature strength cannot be obtained. Further, a silicon nitride powder having a small amount of oxygen (for example, a silicon nitride powder produced by the silicon halide method) is difficult to sinter, and it is difficult to sufficiently densify it.
特公昭61−43311号公報には、窒化ケイ素粉末の酸素
量と高温曲げ強度との関係が記載されているが、固溶体
の形態で存在する酸素量と水酸化物若しくは酸化物の形
態で存在する酸素量が高温曲げ強度に及ぼす影響につい
ては開示がない。Japanese Examined Patent Publication No. 61-43311 describes the relationship between the oxygen content of silicon nitride powder and the high-temperature bending strength, but it exists in the form of a solid solution and in the form of a hydroxide or oxide. There is no disclosure about the effect of oxygen content on high temperature bending strength.
本発明者らは、窒化ケイ素粉末における酸素量及び酸
素の形態が、焼結性及び焼結体特性特に高温強度に及ぼ
す影響について種々検討した結果、易焼結性で高温強度
等の焼結体特性に優れた窒化ケイ素焼結体を得ることが
できる窒化ケイ素粉末を、コスト的に有利な金属シリコ
ン直接窒化法で製造できることを見いだし、本発明を提
案するに至ったものである。As a result of various studies on the influence of the amount of oxygen and the morphology of oxygen in the silicon nitride powder on the sinterability and the properties of the sintered body, particularly the high temperature strength, the present inventors have found that the sintered body is easily sintered and has high temperature strength. The inventors have found that a silicon nitride powder capable of obtaining a silicon nitride sintered body having excellent characteristics can be produced by a cost-effective metal silicon direct nitriding method, and have proposed the present invention.
すなわち、本発明は、固溶体の形態で存在する酸素量
（以下、内部酸素量という）が0.5重量％以下の窒化ケ
イ素粉末を金属ケイ素直接窒化法で製造し、それをPO2
0.05〜0.8atmの雰囲気中、温度600〜1200℃で熱処理す
ることを特徴とする内部酸素量0.5重量％以下、水酸化
物若しくは酸化物の形態で存在する酸素量（以下、外部
酸素量という）が0.5〜2.0重量％である窒化ケイ素粉末
の製造方法である。That is, according to the present invention, a silicon nitride powder having an amount of oxygen present in the form of a solid solution (hereinafter, referred to as an internal oxygen amount) of 0.5% by weight or less is produced by a metal silicon direct nitriding method, and PO 2
Heat treatment at a temperature of 600 to 1200 ° C. in an atmosphere of 0.05 to 0.8 atm, the amount of internal oxygen is 0.5 wt% or less, the amount of oxygen present in the form of hydroxide or oxide (hereinafter referred to as the amount of external oxygen) Is 0.5 to 2.0% by weight.
本発明における窒化ケイ素粉末の内部酸素量は0.5重
量％以下好ましくは0.3重量％以下である。内部酸素量
が0.5重量％を超えると、窒化ケイ素の焼結過程におい
て窒化ケイ素粒子が焼結助剤等から成る粒界相に溶解す
る際に粒界相の組成を変化させ、β−柱状晶の折出と成
長を阻害し、焼結体特性特に高温強度の十分な発現が望
めなくなる。The internal oxygen content of the silicon nitride powder in the present invention is 0.5% by weight or less, preferably 0.3% by weight or less. If the amount of internal oxygen exceeds 0.5% by weight, the composition of the grain boundary phase is changed when the silicon nitride particles are dissolved in the grain boundary phase composed of a sintering aid in the sintering process of silicon nitride, resulting in β-columnar crystals. Of the sintered body, and it becomes impossible to expect sufficient development of the properties of the sintered body, especially the high temperature strength.
窒化ケイ素粉末の焼結特に常圧焼結の場合、窒化ケイ
素粉末の酸素量と焼結性には密接な関係があり、一般に
酸素量が増加するに従って焼結性は向上する。しかし、
一方で、酸素量が増加し過ぎると焼結体における粒界相
の量が増え高温強度等の焼結体特性の低下が起こる。In the case of sintering the silicon nitride powder, particularly in the case of normal pressure sintering, there is a close relationship between the oxygen content of the silicon nitride powder and the sinterability, and the sinterability generally improves as the oxygen content increases. But,
On the other hand, if the amount of oxygen increases too much, the amount of grain boundary phase in the sintered body increases and the characteristics of the sintered body such as high temperature strength deteriorate.
本発明は、窒化ケイ素粉末の酸素量をその存在形態よ
り、内部酸素量と表面酸素量にわけ、窒化ケイ素粉末の
焼結時にどのように関与するかについて種々検討を行っ
た結果、窒化ケイ素粉末の焼結性には、主として表面酸
素量が関与していることをつきとめた。つまり、窒化ケ
イ素粉末の初期焼結段階においては、表面酸素量が増加
するに伴い窒化ケイ素粒子と焼結助剤から成る液相との
ぬれ性が向上し、粒界相への窒化ケイ素粒子の溶解・折
出が促進され焼結性が向上することを見い出したもので
ある。The present invention divides the amount of oxygen of a silicon nitride powder into the amount of internal oxygen and the amount of surface oxygen from its existing form, and as a result of various studies on how they are involved in the sintering of the silicon nitride powder, the silicon nitride powder It was found that the surface oxygen content was mainly involved in the sinterability of. That is, in the initial sintering stage of the silicon nitride powder, the wettability between the silicon nitride particles and the liquid phase consisting of the sintering aid is improved as the surface oxygen amount is increased, and the silicon nitride particles in the grain boundary phase It has been found that melting and cracking are promoted and sinterability is improved.
すなわち、本発明における窒化ケイ素粉の表面酸素量
は0.5〜2.0重量％好ましくは0.7〜1.2重量％の範囲であ
る。表面酸素量が0.5重量％未満では、焼結時における
窒化ケイ素粒子と焼結助剤から成る液相とのぬれ性が低
下し、十分緻密化した焼結体を得ることが難しくなる。
一方、表面酸素量が2.0重量％を超えると、緻密化した
焼結体を得ることはできるが、窒化ケイ素粉末の全酸素
量（内部酸素量と表面酸素量の和）が増加し、焼結体に
おける粒界相の量が増え、高温強度等の焼結体特性の低
下が起こる。That is, the surface oxygen content of the silicon nitride powder in the present invention is in the range of 0.5 to 2.0% by weight, preferably 0.7 to 1.2% by weight. If the amount of surface oxygen is less than 0.5% by weight, the wettability between the silicon nitride particles and the liquid phase consisting of the sintering aid during sintering will deteriorate, and it will be difficult to obtain a sufficiently densified sintered body.
On the other hand, if the surface oxygen content exceeds 2.0% by weight, a densified sintered body can be obtained, but the total oxygen content (sum of internal oxygen content and surface oxygen content) of the silicon nitride powder increases and sintering The amount of grain boundary phase in the body increases, and the characteristics of the sintered body such as high temperature strength deteriorate.
以上の本発明に係る表面酸素量と内部酸素量は、以下
の方法により測定することができる。まず窒化ケイ素粉
末の全酸素量をO/N同時分析計（LECO社製TC−136）によ
り測定する。次に窒化ケイ素粉末に10重量％フッ化水素
酸水溶液を加え恒温水槽中で20分間撹拌する。No.5Cの
濾紙を用いて、この溶液から未分解残渣を濾別して溶出
液を得る。この一部を原子吸光分析計にて溶出SiO2量を
求める。The surface oxygen content and the internal oxygen content according to the present invention described above can be measured by the following method. First, the total oxygen content of the silicon nitride powder is measured by an O / N simultaneous analyzer (TC-136 manufactured by LECO). Next, a 10 wt% hydrofluoric acid aqueous solution is added to the silicon nitride powder, and the mixture is stirred in a constant temperature water tank for 20 minutes. The undecomposed residue is filtered off from this solution using No. 5C filter paper to obtain an eluate. A part of this is determined with an atomic absorption spectrometer to determine the amount of eluted SiO 2 .
この場合、次式に示す反応により一部窒化ケイ素の溶
出が考えられる。In this case, it is considered that the silicon nitride is partly eluted by the reaction represented by the following equation.
Si3N4＋4H2O＋18HF→3H2SiF6＋4NH4OH このため、別に溶出液を水蒸気蒸留後NH4 +量をインド
フェノール青吸光光度法にり求め、そのNH4 +に相当する
SiO2量を溶出SiO2量より差し引いた値より表面SiO2量を
求め、表面酸素量を算出する。内部酸素量は、窒化ケイ
素粉末の全酸素量より表面酸素量を差し引くことによっ
て得られる。Si 3 N 4 ＋ 4H 2 O ＋ 18HF → 3H 2 SiF 6 ＋ 4NH 4 OH Therefore, after evaporating the eluate separately, the NH 4 + amount is determined by the indophenol blue absorptiometry and corresponds to that NH 4 +
The amount of surface SiO 2 is obtained from the value obtained by subtracting the amount of SiO 2 from the amount of eluted SiO 2, and the amount of surface oxygen is calculated. The internal oxygen content is obtained by subtracting the surface oxygen content from the total oxygen content of the silicon nitride powder.
本発明の窒化ケイ素粉末を取得するには、金属ケイ素
粉末を原料として合成された内部酸素量0.5重量％以下
の窒化ケイ素粉末を、回転炉、スクリュー炉、バッチ炉
等によりPO20.05〜0.8atmの雰囲気中、600〜1200℃の温
度で熱処理することにより製造することができる。そし
て、その際における内部酸素量0.重量％以下の窒化ケイ
素粉末は、特願昭64−43079号及び特願昭64−47431号の
明細書に記載されている方法、又は市販の金属ケイ素法
による窒化ケイ素粉末を特公昭61−43311号公報に記載
の手法で処理することにより得ることができる。In order to obtain the silicon nitride powder of the present invention, a silicon nitride powder having an internal oxygen content of 0.5% by weight or less synthesized from metallic silicon powder as a raw material is subjected to PO 2 0.05 to 0.8 atm by a rotary furnace, a screw furnace, a batch furnace or the like. Can be manufactured by heat treatment at a temperature of 600 to 1200 ° C. in the atmosphere. And, the silicon nitride powder having an internal oxygen content of 0% by weight or less is the method described in the specifications of Japanese Patent Application No. 64-43079 and Japanese Patent Application No. 64-47431, or a commercially available metal silicon method. It can be obtained by treating the silicon nitride powder according to the method described in Japanese Patent Publication No. 61-43311.
以下、実施例と比較例を挙げて更に具体的に本発明を
説明するが、本発明はこれに限定されない。Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited thereto.
実施例１〜6,比較例１〜４ 第１表に示す金属ケイ素直接窒化法で製造された各種
窒化ケイ素粉末を原料として第２表に示す各種条件にて
処理を行い同表に示す物性値を持った窒化ケイ素粉末を
合成した。Examples 1 to 6 and Comparative Examples 1 to 4 Various silicon nitride powders produced by the direct silicon nitriding method shown in Table 1 were used as raw materials and treated under the various conditions shown in Table 2 and physical property values shown in the same table. A silicon nitride powder having
次に、この窒化ケイ素粉末93重量部に焼結助剤として
平均粒径1.5μｍのY2O3 5重量部と平均粒径0.8μｍのAl
2O3 2重量部を添加し、1,1,1−トリクロロエタンを加え
４時間ボールミルで湿式混合し、乾燥後100kg/cm2の成
形圧で６×10×60mm形状に金型成形し、それを2700kg/c
m2の成形圧でCIP成形した。これらの成形体をカーボン
ルツボにセットし、N2ガス雰囲気中、1800℃の温度で４
時間焼成して焼結体を得た。得られた焼結体は研削後、
相対密度、室温（σRT）及び1200℃（σ1200）における
３点曲げ強度を測定した。それらの結果を第３表に示
す。Next, 93 parts by weight of this silicon nitride powder was added as a sintering aid with 5 parts by weight of Y 2 O 3 having an average particle size of 1.5 μm and Al having an average particle size of 0.8 μm.
2 O 3 2 parts by weight is added, 1,1,1-trichloroethane is added, and the mixture is wet mixed in a ball mill for 4 hours, dried, and then molded into a 6 × 10 × 60 mm shape at a molding pressure of 100 kg / cm 2 , which 2700 kg / c
CIP molding was performed at a molding pressure of m 2 . These compacts were set in a carbon crucible and placed in a N 2 gas atmosphere at a temperature of 1800 ° C for 4 hours.
It was fired for a time to obtain a sintered body. After the obtained sintered body is ground,
Relative density, room temperature (σ RT ) and three-point bending strength at 1200 ° C. (σ 1200 ) were measured. The results are shown in Table 3.
第３表に示した測定値は次の方法によった。 The measured values shown in Table 3 were measured by the following method.
（１） 相対密度（％） ：アルキメデス法によ
る。(1) Relative density (%): By Archimedes method.
（２） ３点曲げ強度（MPa）：島津製作所社製，オー
トグラフ AG−2000Aによる。(2) Three-point bending strength (MPa): According to Autograph AG-2000A manufactured by Shimadzu Corporation.
実施例７〜8,比較例６〜８ 第１表に示す窒化ケイ素粉末ＣをN2雰囲気1700℃で２
時間加熱処理を行い、第４表に示す粉体特性を有する窒
化ケイ素粉末Ｅを得た。 Examples 7 to 8 and Comparative Examples 6 to 8 Silicon nitride powder C shown in Table 1 was used for 2 at 1700 ° C. in N 2 atmosphere.
After heat treatment for a period of time, a silicon nitride powder E having the powder characteristics shown in Table 4 was obtained.
この窒化ケイ素粉末Ｅ及び未処理の窒化ケイ素粉末Ｃ
を第５表に示す各種条件にて処理を行い、第５表に示す
物性値を有する窒化ケイ素粉末を合成した。次に、この
窒化ケイ素粉末を用い実施例１と同様にして焼結体を製
造し、それらの焼結体特性を測定した。それらの結果を
第６表に示す。This silicon nitride powder E and untreated silicon nitride powder C
Was treated under various conditions shown in Table 5 to synthesize silicon nitride powder having physical properties shown in Table 5. Next, using this silicon nitride powder, sintered bodies were manufactured in the same manner as in Example 1, and the characteristics of these sintered bodies were measured. The results are shown in Table 6.
〔発明の効果〕 本発明によって製造された窒化ケイ素粉末はコスト的
に有利であり、しかも表面酸素量が特定範囲内にあるた
め、焼結製が改善され、容易に緻密化した焼結体を、ま
た、内部酸素量が少ないため、高温強度の優れた焼結体
を得ることができる。 [Effects of the Invention] The silicon nitride powder produced by the present invention is cost-effective, and since the amount of surface oxygen is within a specific range, the sintered product is improved and an easily densified sintered body is obtained. Moreover, since the amount of internal oxygen is small, a sintered body having excellent high temperature strength can be obtained.
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 平２−107509（ＪＰ，Ａ) ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-107509 (JP, A)
Claims (1)
％以下の窒化ケイ素粉末を金属ケイ素直接窒化法で製造
し、それをPO2 0.05〜0.8atmの雰囲気中、温度600〜120
0℃で熱処理することを特徴とする固溶体の形態で存在
する酸素量が0.5重量％以下、水酸化物若しくは酸化物
の形態で存在する酸素量が0.5〜2.0重量％である窒化ケ
イ素粉末の製造方法。1. A silicon nitride powder containing 0.5% by weight or less of oxygen, which is present in the form of a solid solution, is produced by a direct silicon nitriding method, and the powder is produced in an atmosphere of PO 2 0.05 to 0.8 atm at a temperature of 600 to 120.
Production of a silicon nitride powder characterized by being heat treated at 0 ° C., wherein the amount of oxygen present in the form of solid solution is 0.5 wt% or less, and the amount of oxygen present in the form of hydroxide or oxide is 0.5 to 2.0 wt%. Method.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1288549A JPH0822730B2 (en) | 1989-11-06 | 1989-11-06 | Method for producing silicon nitride powder |
| US07/510,587 US5126295A (en) | 1989-06-07 | 1990-04-18 | Silicon nitride powder, silicon nitride sintered body and processes for their production |
| DE4013923A DE4013923C2 (en) | 1989-06-07 | 1990-04-30 | Silicon nitride powder, process for its preparation and use of a silicon nitride powder |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1288549A JPH0822730B2 (en) | 1989-11-06 | 1989-11-06 | Method for producing silicon nitride powder |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH03150212A JPH03150212A (en) | 1991-06-26 |
| JPH0822730B2 true JPH0822730B2 (en) | 1996-03-06 |
Family
ID=17731684
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1288549A Expired - Fee Related JPH0822730B2 (en) | 1989-06-07 | 1989-11-06 | Method for producing silicon nitride powder |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0822730B2 (en) |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3829504A1 (en) * | 1988-08-31 | 1990-03-01 | Bayer Ag | SILICON NITRIDE POWDER WITH IMPROVED SURFACE PROPERTIES AND METHOD FOR THE PRODUCTION THEREOF |
-
1989
- 1989-11-06 JP JP1288549A patent/JPH0822730B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH03150212A (en) | 1991-06-26 |
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