JPH11217272A - Silicon nitride sintered member having oriented crystal and its production - Google Patents
Silicon nitride sintered member having oriented crystal and its productionInfo
- Publication number
- JPH11217272A JPH11217272A JP10021132A JP2113298A JPH11217272A JP H11217272 A JPH11217272 A JP H11217272A JP 10021132 A JP10021132 A JP 10021132A JP 2113298 A JP2113298 A JP 2113298A JP H11217272 A JPH11217272 A JP H11217272A
- Authority
- JP
- Japan
- Prior art keywords
- silicon nitride
- magnetic field
- sintered
- shaped
- sintering
- 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
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、高温構造材料や高
熱伝導性基板となる高熱伝導窒化珪素焼結体及びその製
造方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-thermal-conductivity silicon nitride sintered body used as a high-temperature structural material or a high-thermal-conductivity substrate, and a method for producing the same.
【０００２】[0002]
【従来の技術】窒化珪素（Ｓｉ3Ｎ4）焼結体は、高い熱
伝導性と機械的強度が要求される熱機関、熱交換器等の
高温構造材料や、ＩＣの放熱基板材料等の高熱伝導材料
として注目されている。2. Description of the Related Art Silicon nitride (Si3N4) sintered bodies are high-temperature structural materials, such as heat engines and heat exchangers, which require high thermal conductivity and mechanical strength, and high heat conductive materials, such as IC heat dissipation substrate materials. It is attracting attention.
【０００３】一般的な金属材料は、５００℃を超える条
件下において強度、耐酸化性、耐食性が著しく低下する
ため、冷却を行わずに使用することは不可能である。ま
た。一方、１００℃以下で使用されるＩＣ等の放熱基板
材料においては、絶縁性が必要とされるため、これも適
用が困難であった。そこで、焼結体（セラミックス）で
あるＡｌ2Ｏ3、ＡｌＮ、ＳｉＯ2 等の適用が試みられた
が、機械的強度の点で問題があって実用化が困難であ
り、これらに代わる材料として窒化珪素焼結体が注目さ
れるようになってきた。[0003] Since general metal materials have significantly reduced strength, oxidation resistance and corrosion resistance under conditions exceeding 500 ° C, they cannot be used without cooling. Also. On the other hand, heat-dissipating substrate materials such as ICs used at 100 ° C. or lower require insulating properties, and thus have been difficult to apply. Therefore, application of sintered bodies (ceramics) such as Al2O3, AlN, and SiO2 has been attempted, but there is a problem in mechanical strength, and practical application is difficult. The body is getting attention.
【０００４】一般に窒化珪素焼結体は、αあるいはβ型
窒化珪素粉末にＭｇＯ、ＣａＯ、Ａｌ2Ｏ3、Ｙ2Ｏ3、Ｙ
ｂ2Ｏ3、ＨｆＯ2、Ｓｃ2Ｏ3、ＣｅＯ2、Ｌａ2Ｏ3、Ｚｒ
Ｏ2、ＳｉＯ2、Ｃｒ2Ｏ3、ＡｌＮ等から選択された焼結
助剤を添加し、得られた混合粉末を成形後、１〜１００
気圧の窒素雰囲気中で１６００〜２１００℃で焼結して
製造される。あるいは、これら混合粉末をガラスカプセ
ルに封入後、１０００気圧程度のガス圧力下でＨＩＰ
（Hot Isostatic Pressing）焼結、あるいは１気圧の窒
素雰囲気中で２０〜４０ＭＰａ程度の圧力下１６００〜
１８００℃でホットプレス（ＨＰ）焼結して製造され
る。しかし、これら従来手法で得られた窒化珪素焼結体
においては、強度及び靱性は十分ではなく、また、熱伝
導率も１０〜７０Ｗ／ｍＫと低かったため、このような
特性を向上させるべく種々の研究、開発がなされてき
た。In general, a silicon nitride sintered body is obtained by adding MgO, CaO, Al2O3, Y2O3, Y
b2O3, HfO2, Sc2O3, CeO2, La2O3, Zr
After adding a sintering aid selected from O2, SiO2, Cr2O3, AlN, etc., and molding the resulting mixed powder,
It is manufactured by sintering at 1600 to 2100 ° C. in a nitrogen atmosphere at atmospheric pressure. Alternatively, after encapsulating these mixed powders in a glass capsule, HIP is performed under a gas pressure of about 1000 atm.
(Hot Isostatic Pressing) Sintering or 1600 to 1 MPa under a pressure of about 20 to 40 MPa in a nitrogen atmosphere
It is manufactured by hot press (HP) sintering at 1800 ° C. However, in the silicon nitride sintered bodies obtained by these conventional methods, the strength and toughness are not sufficient, and the thermal conductivity is as low as 10 to 70 W / mK. Research and development have been done.
【０００５】強度及び靱性の向上を図った公知例として
は、特開平５−１８６２６９号が挙げられる。ここで
は、α窒化珪素粉末に鉄成分を微量添加することにより
焼結中のβ窒化珪素柱状晶の成長を促進させ、破壊靱性
値８ＭＰａ√ｍ以上の窒化珪素焼結体を得ている。ま
た、特開平８−３４６７０号においては、β窒化珪素粉
末にβ窒化珪素の棒状種結晶を添加した後に成形、焼結
することによって、高強度、高靱性の窒化珪素焼結体を
得ている。[0005] A known example for improving the strength and toughness is disclosed in JP-A-5-186269. Here, by adding a small amount of iron component to the α silicon nitride powder, the growth of β silicon nitride columnar crystals during sintering is promoted, and a silicon nitride sintered body having a fracture toughness value of 8 MPa√m or more is obtained. In Japanese Patent Application Laid-Open No. 8-34670, a silicon nitride sintered body having high strength and high toughness is obtained by adding a rod-shaped seed crystal of β silicon nitride to β silicon nitride powder and then molding and sintering. .
【０００６】上記の公知例においては熱伝導度について
の言及はなされていなかったが、これらに対し、熱伝導
度の改善を図った公知例として、特開平９−１６５２６
５号が挙げられる。ここでは、図９に示すごとく窒化珪
素原料２３中にβ窒化珪素の微小な柱状又は針状種結晶
２２を添加して成形し、これを焼結する過程での種結晶
２２のエピタキシャル成長により、繊維状の窒化珪素柱
状結晶２６が一方向に配向した組織を持つ窒化珪素焼結
部材２８を得ている。この焼結部材２８は、特定方向
（窒化珪素柱状結晶２６の配向方向、すなわち板面に平
行な方向）において、高い強度及び１００〜１５０Ｗ／
ｍＫの高熱伝導度を示す。すなわちこの公知例において
は、 （１）得られる窒化珪素焼結体の材料特性が優れている （２）そのような材料特性がある特定の方向性を持つ という特徴があった。[0006] In the above-mentioned known examples, there is no mention of the thermal conductivity. However, as a known example in which the thermal conductivity is improved, Japanese Patent Application Laid-Open No. Hei 9-16526 is used.
No. 5 is mentioned. Here, as shown in FIG. 9, a fine columnar or needle-like seed crystal 22 of β silicon nitride is added to a silicon nitride raw material 23, and the seed crystal 22 is formed. A silicon nitride sintered member 28 having a structure in which silicon nitride columnar crystals 26 are oriented in one direction is obtained. The sintered member 28 has high strength and 100 to 150 W / in a specific direction (the direction of orientation of the silicon nitride columnar crystals 26, that is, the direction parallel to the plate surface).
Shows a high thermal conductivity of mK. That is, in this known example, (1) the material characteristics of the obtained silicon nitride sintered body were excellent (2) such material characteristics had a specific directionality.
【０００７】[0007]
【発明が解決しようとする課題】しかしながら上記公知
例においては、棒状又は針状のβ型窒化珪素種結晶２２
を配向する手段が押出し又はドクターブレード法による
成形であるため、得られる成形品の形状は板状に限定さ
れていた。そこで、塊状の厚肉製品を製造するために
は、図１０に示すごとく、いったん板状成形体２９を複
数製造した上でこれを積層し、その後ホットプレス（Ｈ
Ｐ）する必要があり、作業工数が多く煩雑である点に問
題があった。また、窒化珪素柱状結晶２６の配向は板面
に対して平行方向のみに限定されていたため、製品の応
用範囲の拡大のためにはさらなる改善が必要であった。However, in the above-mentioned known example, a rod-shaped or needle-shaped β-type silicon nitride seed crystal 22 is provided.
Because the means for orienting is extrusion or molding by a doctor blade method, the shape of the obtained molded product is limited to a plate shape. Therefore, in order to manufacture a lump-shaped thick product, as shown in FIG. 10, a plurality of plate-like formed bodies 29 are first manufactured and then laminated, and then hot-pressed (H
P), which is problematic in that the number of work steps is large and complicated. In addition, since the orientation of the silicon nitride columnar crystal 26 was limited only to the direction parallel to the plate surface, further improvement was necessary to expand the application range of the product.
【０００８】本発明はの課題は、板状、塊状等の形状の
如何を問わず、任意の方向に配向された窒化珪素焼結体
及びその製造方法を提供することである。An object of the present invention is to provide a silicon nitride sintered body oriented in an arbitrary direction irrespective of a plate shape, a lump shape or the like, and a method for producing the same.
【０００９】[0009]
【課題を解決するための手段】上記課題を解決するため
の、本発明の窒化珪素焼結部材は、任意の方向に窒化珪
素（Ｓｉ3Ｎ4）結晶を配向したことを特徴とする。Means for Solving the Problems To solve the above-mentioned problems, a sintered silicon nitride member of the present invention is characterized in that silicon nitride (Si3N4) crystals are oriented in an arbitrary direction.
【００１０】また、本発明の窒化珪素焼結部材は、表面
に磁性金属をコーティングした棒状又は針状の窒化珪素
結晶を窒化珪素粉末及び焼結助剤を含む窒化珪素焼結原
料中に添加して分散させ、磁場中において成形を行い、
その後、焼結して得られることを特徴とする。Further, the silicon nitride sintered member of the present invention is obtained by adding a rod-shaped or needle-shaped silicon nitride crystal having a surface coated with a magnetic metal to a silicon nitride sintering raw material containing silicon nitride powder and a sintering aid. Disperse, molding in a magnetic field,
Then, it is characterized by being obtained by sintering.
【００１１】また、本発明の窒化珪素焼結部材は、表面
に磁性金属をコーティングした棒状又は針状の窒化珪素
結晶を窒化珪素粉末及び焼結助剤を含む窒化珪焼結原料
中に添加して分散させ、磁場中において成形を行った後
にコーティングした金属を溶解、又は蒸発によって除去
し、その後、焼結して得られることを特徴とする。Further, the silicon nitride sintered member of the present invention is obtained by adding a rod-like or needle-like silicon nitride crystal having a surface coated with a magnetic metal to a silicon nitride sintering raw material containing silicon nitride powder and a sintering aid. After forming and dispersing in a magnetic field, the coated metal is removed by dissolving or evaporating, followed by sintering.
【００１２】また、本発明の窒化珪素焼結部材は、磁性
金属を窒化珪素結晶の表面にコーティングする方法が、
蒸着、スパッタリング、又は湿式の化学メッキのいずれ
かであることを特徴とする。Further, in the silicon nitride sintered member of the present invention, a method of coating a surface of a silicon nitride crystal with a magnetic metal comprises:
It is one of vapor deposition, sputtering, and wet chemical plating.
【００１３】また、本発明の窒化珪素焼結部材は、表面
に磁性金属をコーティングした窒化珪素結晶の添加量が
１ｗｔ％から１００ｗｔ％であることを特徴とする。Further, the silicon nitride sintered member of the present invention is characterized in that the addition amount of silicon nitride crystal having a surface coated with a magnetic metal is 1 wt% to 100 wt%.
【００１４】また、本発明の窒化珪素焼結部材は、磁場
中における成形法がプレス、射出、鋳込み、押出し、ド
クターブレード法、又はＣＩＰ（Cold Isostatic Press
ing）のいずれかにであることを特徴とする。The silicon nitride sintered member of the present invention can be formed by a press, injection, casting, extrusion, doctor blade, or CIP (Cold Isostatic Press) method in a magnetic field.
ing).
【００１５】また、本発明の窒化珪素焼結部材は、成形
時の磁場の強さが５Ｋｏｅ以上であることを特徴とす
る。表面に磁性金属をコーティングした棒状又は針状の
窒化珪素種結晶を特定方向に配向するためには、成形磁
場の強度を５Ｋｏｅ以上、より好ましくは１０Ｋｏｅ、
特に好ましくは１５Ｋｏｅとするのが良い。さらに言え
ば、図１において、種結晶２１の平均直径（ｘ）を０．
５〜３μｍ、平均長さ（ｙ）との比ｙ／ｘを３〜１０と
することが、その形状異方性を反映した良好な磁場配向
性を獲得するために好ましい。上記（ｘ）、（ｙ）の範
囲を外れると、後述の１０°以内の配向体を得ることが
困難である。Further, the silicon nitride sintered member of the present invention is characterized in that the strength of the magnetic field during molding is 5 Koe or more. In order to orient a rod-shaped or needle-shaped silicon nitride seed crystal having a surface coated with a magnetic metal in a specific direction, the intensity of a molding magnetic field is 5 Koe or more, more preferably 10 Koe,
Especially preferably, it is set to 15 Koe. Furthermore, in FIG. 1, the average diameter (x) of the seed crystal 21 is set to 0.
It is preferable to set the ratio y / x to 5 to 3 μm and the average length (y) to 3 to 10 in order to obtain good magnetic field orientation reflecting the shape anisotropy. If the ratio is out of the ranges (x) and (y), it is difficult to obtain an oriented body within 10 ° described later.
【００１６】また、本発明の窒化珪素焼結部材は、窒化
珪素焼結原料が粉体状又はスラリー状であることを特徴
とする。The silicon nitride sintered member according to the present invention is characterized in that the silicon nitride sintered raw material is in the form of powder or slurry.
【００１７】また、本発明の窒化珪素焼結部材は、形状
が塊状であることを特徴とする。The silicon nitride sintered member of the present invention is characterized in that the shape is a lump.
【００１８】また、本発明の窒化珪素焼結部材は、形状
が板状であり、板面に対して垂直方向に窒化珪素結晶を
配向し、この方向の熱伝導率が１００Ｗ／ｍＫ以上であ
ることを特徴とする。Further, the silicon nitride sintered member of the present invention has a plate shape and the silicon nitride crystal is oriented in a direction perpendicular to the plate surface, and the thermal conductivity in this direction is 100 W / mK or more. It is characterized by the following.
【００１９】また、本発明の窒化珪素焼結部材の製造方
法は、任意の方向に窒化珪素結晶を配向させることを特
徴とする。The method for manufacturing a silicon nitride sintered member according to the present invention is characterized in that the silicon nitride crystal is oriented in an arbitrary direction.
【００２０】また、本発明の窒化珪素焼結部材の製造方
法は、表面に磁性金属をコーティングした棒状又は針状
の窒化珪素結晶を窒化珪素粉末及び焼結助剤を含む窒化
珪焼結原料中に添加して分散させ、磁場中において成形
を行い、その後、焼結することを特徴とする。Further, according to the method for producing a silicon nitride sintered member of the present invention, a rod-shaped or needle-shaped silicon nitride crystal having a surface coated with a magnetic metal is prepared by mixing a silicon nitride powder and a sintering aid with a silicon nitride sintered material. , Dispersed in the mixture, molded in a magnetic field, and then sintered.
【００２１】また、本発明の窒化珪素焼結部材の製造方
法は、表面に磁性金属をコーティングした棒状又は針状
の窒化珪素結晶を窒化珪素粉末及び焼結助剤を含む窒化
珪焼結原料中に添加して分散させ、磁場中において成形
を行った後に、コーティングした金属を、溶解、又は蒸
発により除去し、その後、焼結することを特徴とする。Further, according to the method for producing a silicon nitride sintered member of the present invention, a rod-shaped or needle-shaped silicon nitride crystal having a surface coated with a magnetic metal is formed by mixing silicon nitride powder and a sintering aid with a silicon nitride sintered material. , And after forming in a magnetic field, the coated metal is removed by dissolving or evaporating, followed by sintering.
【００２２】また、本発明の窒化珪素焼結部材の製造方
法は、蒸着、スパッタリング、又は湿式化学めっきのい
ずれかによって磁性金属を窒化珪素結晶の表面にコーテ
ィングすることを特徴とする。The method for manufacturing a silicon nitride sintered member according to the present invention is characterized in that a magnetic metal is coated on the surface of the silicon nitride crystal by any one of vapor deposition, sputtering, and wet chemical plating.
【００２３】また、本発明の窒化珪素焼結部材の製造方
法は、表面に磁性金属をコーティングした窒化珪素結晶
を１ｗｔ％から１００ｗｔ％添加することを特徴とす
る。Further, the method for manufacturing a silicon nitride sintered member according to the present invention is characterized in that 1 wt% to 100 wt% of a silicon nitride crystal having a surface coated with a magnetic metal is added.
【００２４】また、本発明の窒化珪素焼結部材の製造方
法は、プレス、射出、鋳込み、押出し、ドクターブレー
ド法、又はＣＩＰのいずれかの成形を磁場中において行
うことを特徴とする。The method for manufacturing a silicon nitride sintered member according to the present invention is characterized in that any one of pressing, injection, casting, extrusion, doctor blade method, or CIP is performed in a magnetic field.
【００２５】また、本発明の窒化珪素焼結部材の製造方
法は、５Ｋｏｅ以上の強さの磁場中において成形を行う
ことを特徴とする。The method for manufacturing a silicon nitride sintered member according to the present invention is characterized in that the forming is performed in a magnetic field having a strength of 5 Koe or more.
【００２６】また、本発明の窒化珪素焼結部材の製造方
法は、粉体状又はスラリー状の窒化珪素焼結原料を用い
ることを特徴とする。Further, the method for manufacturing a silicon nitride sintered member of the present invention is characterized in that a powdery or slurry-like silicon nitride sintered raw material is used.
【００２７】本発明における窒化珪素焼結体及びその製
造方法に関して詳細を以下に記述する。まず、棒状又は
針状の窒化珪素（Ｓｉ3Ｎ4）種結晶に、磁性金属をコー
ティングする。このとき用いる磁性金属はＦｅ、Ｎｉ、
Ｃｏ等であり、またコーティングの方法としてはスパッ
タリング、蒸着、湿式化学メッキが用いられる。The details of the silicon nitride sintered body and the method for producing the same according to the present invention will be described below. First, a rod-shaped or needle-shaped silicon nitride (Si3N4) seed crystal is coated with a magnetic metal. The magnetic metal used at this time is Fe, Ni,
Co or the like, and as a coating method, sputtering, vapor deposition, or wet chemical plating is used.
【００２８】次に、窒化珪素粉末に所定量の焼結助剤を
添加、混合する。窒化珪素粉末はα、βいずれの結晶系
のものを用いても良いが、平均粒径１μm以下の微粉末
を用いることが望ましい。また、焼結助剤としては、Ｍ
ｇＯ、ＣａＯ、Ｙ2Ｏ3、Ｙｂ2Ｏ3、ＨｆＯ2、Ｓｃ2Ｏ
3、ＣｅＯ2、Ｌａ2Ｏ3、ＺｒＯ2、ＳｉＯ2、Ｃｒ2Ｏ3等
一般に用いられるものが使用される。特に、焼結中にお
いて窒化珪素を特定の磁場異方性化方向へと柱状に異方
成長させるために、Ｙ2Ｏ3、Ｌａ2Ｏ3、ＣｅＯ2等の希
土類酸化物を含むことが望ましい。なお、Ａｌ2Ｏ3ある
いはＡｌＮは焼結時に窒化珪素中に固溶し、熱伝導率を
著しく低下させるので使用をさけた方が良い。これら焼
結助剤の組み合わせ及び添加量は後の工程に応じて調整
するが、多量に添加すると熱伝導低下の原因となるの
で、可能な限り最小量にとどめるのが望ましい。Next, a predetermined amount of a sintering aid is added to the silicon nitride powder and mixed. As the silicon nitride powder, any of α and β crystal systems may be used, but it is preferable to use fine powder having an average particle diameter of 1 μm or less. As a sintering aid, M
gO, CaO, Y2O3, Yb2O3, HfO2, Sc2O
3, generally used materials such as CeO2, La2O3, ZrO2, SiO2, Cr2O3, etc. are used. In particular, it is preferable to include a rare earth oxide such as Y2O3, La2O3, or CeO2 in order to grow silicon nitride in a columnar direction in a specific magnetic field anisotropy direction during sintering. Since Al2O3 or AlN forms a solid solution in silicon nitride during sintering and significantly lowers the thermal conductivity, it is better to avoid using Al2O3 or AlN. The combination and addition amount of these sintering aids are adjusted according to the subsequent steps. However, if added in large amounts, heat conduction is reduced, so it is desirable to keep the amounts as small as possible.
【００２９】また、これらの原料の混合にあたっては、
粉体の混合あるいは混練に用いられる通常の機械を使用
し、乾式又は湿式のいずれかにおいて行われる。湿式混
合においては、水、メタノール、エタノール、トルエ
ン、シクロヘキサン等の溶媒が用いられるが、窒化珪素
の酸化を抑えるために有機溶媒を用いることが望まし
い。またこのとき、水、メタノール、及びエタノールに
はアンモニウム塩を、トルエン及びシクロヘキサンには
アミン系の分散剤を用いることにより混合の効果を高め
ることができる。In mixing these raw materials,
Using a usual machine used for mixing or kneading of powder, it is carried out either in a dry system or a wet system. In the wet mixing, a solvent such as water, methanol, ethanol, toluene, or cyclohexane is used, and it is preferable to use an organic solvent to suppress oxidation of silicon nitride. At this time, the effect of mixing can be enhanced by using an ammonium salt for water, methanol, and ethanol, and an amine-based dispersant for toluene and cyclohexane.
【００３０】このようにして得られた粉末状あるいはス
ラリー状の窒化珪素原料に、上記、磁性金属をコーティ
ングした棒状又は針状の窒化珪素結晶を種結晶として添
加する。このとき添加量が１ｗｔ％以下では焼結体中に
十分な柱状結晶が成長せず、希望する配向の結晶を持っ
た部材を得ることができない。また、１００ｗｔ％まで
緻密で強度に優れた焼結体が得られる。従って、添加量
は１ｗｔ％から１００ｗｔ％が望ましい。また、種結晶
の形状は、短径が窒化珪素原料の粉末の平均粒径よりも
小さいと、焼結中に助剤中に溶解してしまうので、これ
より大きいことが望ましい。また種結晶は、α型よりも
安定であって助剤中に溶解しづらいβ型窒化珪素とする
ことが望ましい。粉末状の窒化珪素原料への種結晶の添
加は、通常粉体の混合に用いられる機械を使用して、ま
た、スラリー状の窒化珪素原料への添加は、超音波分
散、樹脂ポットと樹脂コートボールを用いたポット混合
等の手法により、いずれも種結晶を破壊しないように行
うことが重要である。The rod-like or needle-like silicon nitride crystals coated with a magnetic metal are added as seed crystals to the powdery or slurry-like silicon nitride raw material thus obtained. At this time, if the addition amount is 1 wt% or less, sufficient columnar crystals do not grow in the sintered body, and a member having crystals of a desired orientation cannot be obtained. Further, a sintered body that is dense and has excellent strength can be obtained up to 100 wt%. Therefore, the addition amount is desirably 1 wt% to 100 wt%. If the minor axis is smaller than the average particle diameter of the powder of the silicon nitride raw material, the seed crystal is dissolved in the auxiliary during sintering. The seed crystal is desirably β-type silicon nitride which is more stable than the α-type and is hardly dissolved in the auxiliary agent. The seed crystal is added to the powdered silicon nitride raw material using a machine usually used for powder mixing, and the addition to the slurry silicon nitride raw material is performed by ultrasonic dispersion, resin pot and resin coating. It is important that any method such as pot mixing using a ball is performed so as not to destroy the seed crystal.
【００３１】また、より緻密な焼結体を得るには、窒化
珪素にに対して焼結助剤を全体の１〜１５ｗｔ％添加し
た原料を用いることが望ましい。焼結助剤が１ｗｔ％未
満では添加の効果が認められず、１５ｗｔ％を超えると
窒化珪素焼結部剤の強度低下等につながる。In order to obtain a denser sintered body, it is desirable to use a raw material obtained by adding a sintering aid to silicon nitride in an amount of 1 to 15% by weight based on silicon nitride. If the amount of the sintering aid is less than 1% by weight, the effect of addition is not recognized, and if it exceeds 15% by weight, the strength of the silicon nitride sintered component is reduced.
【００３２】以上のようにして得られた混合物に対して
必要に応じて適量の有機バインダー例えばポリビニルブ
チラール等を添加混合した後、磁場中において成形を行
う。成形の方法としては、プレス、射出、鋳込み、押出
し、ドクターブレード法、又はＣＩＰがある。After adding and mixing an appropriate amount of an organic binder such as polyvinyl butyral as necessary to the mixture obtained as described above, molding is performed in a magnetic field. Molding methods include pressing, injection, casting, extrusion, doctor blade method, and CIP.
【００３３】磁場中において上記の成形を行う場合の作
用について、図１及び図２に示すとともに以下詳述す
る。図１（ａ）に示すように、成形される窒化珪素原料
２３中には、磁性金属２４によって表面をコーティング
された窒化珪素種結晶２１が含まれている。この窒化珪
素原料２３を磁場中に置くと、図１（ｂ）に示すように
窒化珪素種結晶２１表面の磁性金属２４に磁力線２５が
作用し、窒化珪素種結晶２１はある一定の方向に配向す
る。この配向方向は、専ら磁力線２５の方向によって決
定されるものであるから、図１の場合とは磁力線の方向
が異なる場合、例えば図２に示すような場合では結晶の
配向方向は自ずと異なったものになる。このような磁場
中において各種成形を行うと、窒化珪素種結晶がそれぞ
れの磁場における磁力線の方向に配向した成形体が得ら
れる。すなわち、成形時に磁力線の方向をコントロール
することにより、任意の方向に配向した窒化珪素種結晶
を持つ成形体が得られるものである。The operation when the above-mentioned molding is performed in a magnetic field will be described in detail with reference to FIGS. 1 and 2. As shown in FIG. 1A, the silicon nitride raw material 23 to be formed contains a silicon nitride seed crystal 21 whose surface is coated with a magnetic metal 24. When this silicon nitride raw material 23 is placed in a magnetic field, magnetic force lines 25 act on the magnetic metal 24 on the surface of the silicon nitride seed crystal 21 as shown in FIG. 1 (b), and the silicon nitride seed crystal 21 is oriented in a certain direction. I do. Since this orientation direction is determined solely by the direction of the magnetic field lines 25, when the direction of the magnetic field lines is different from that of FIG. 1, for example, as shown in FIG. 2, the crystal orientation direction is naturally different. become. When various types of molding are performed in such a magnetic field, a molded body in which the silicon nitride seed crystal is oriented in the direction of the line of magnetic force in each magnetic field is obtained. That is, by controlling the direction of the lines of magnetic force during molding, a molded article having a silicon nitride seed crystal oriented in an arbitrary direction can be obtained.
【００３４】さらに重要なことに、このような作用はプ
レス、射出、鋳込み、押出し、ドクターブレード法、又
はＣＩＰ（Cold Isostatic Pressing ）のいずれの成形
法においても得られるものであるから、これら多様な成
形法により、板状、塊状いずれの形状においても、任意
の方向に配向した種結晶を持つ成形体が得られる。従っ
て、従来、いったん板状成形体を複数製造したうえでそ
れらを必要な厚さとなるよう積層して圧着していた塊状
成形体が、一回の成形によって得られるようになる。More importantly, since such an action can be obtained by any of the pressing, injection, casting, extrusion, doctor blade, or CIP (Cold Isostatic Pressing) molding methods, these various effects can be obtained. By the molding method, a molded article having a seed crystal oriented in an arbitrary direction can be obtained in any of a plate shape and a lump shape. Therefore, a block-shaped compact, which has conventionally been produced in the form of a plurality of plate-shaped compacts and then laminated and pressed to a required thickness, can be obtained by a single molding.
【００３５】前記成形体が得られた後に、窒化珪素結晶
の表面にコーティングされた磁性金属を除去することが
望ましい。窒化珪素結晶の表面に磁性金属をコーティン
グしたままであると、焼結製が悪くなり、気孔等の欠陥
が生じ易いという問題が起こりうる。そこで、溶解、蒸
発によって磁性金属を除去し、これらの問題が起こらな
いようにすることが望ましい。具体的には、成形体を
酸、アルカリ等の液中に浸漬することにより磁性金属を
溶解させて除去する方法や、成形体を真空中にて加熱す
ることにより磁性金属を蒸発させて除去する方法を用い
る。さらに成形体の強度及び緻密度を向上するために、
この工程の後にプレス又はＣＩＰによる再加圧を行うこ
とが望ましい。After the compact is obtained, it is desirable to remove the magnetic metal coated on the surface of the silicon nitride crystal. If the surface of the silicon nitride crystal is kept coated with the magnetic metal, sintering may be poor and defects such as pores may easily occur. Therefore, it is desirable to remove the magnetic metal by dissolution and evaporation so that these problems do not occur. Specifically, a method of dissolving and removing the magnetic metal by immersing the molded body in a liquid such as an acid or an alkali, or evaporating and removing the magnetic metal by heating the molded body in a vacuum Method. In order to further improve the strength and compactness of the molded body,
After this step, it is desirable to perform re-pressing by press or CIP.
【００３６】次に、前記成形体は、まず６００〜１００
０℃程度の温度で仮焼を行い、成形バインダーを除去し
た後、ホットプレス手法等により焼結して緻密化する。
このときの圧力、温度、時間等の諸条件は、ホットプレ
ス後の焼結体が相対密度９７％以上に緻密化するように
選定される。一般的には窒素雰囲気中１６００〜１８５
０℃、２０〜４０ＭＰａにおいて行う。また、助剤系を
選択することにより、窒素中での加熱だけで緻密化が可
能な場合は、ホットプレス処理は省略することが可能で
ある。Next, the above-mentioned molded body is firstly 600 to 100
After calcination is performed at a temperature of about 0 ° C. to remove the molding binder, sintering is performed by a hot press technique or the like to densify.
Various conditions such as pressure, temperature, and time at this time are selected so that the sintered body after hot pressing is densified to a relative density of 97% or more. Generally 1600 to 185 in a nitrogen atmosphere
Performed at 0 ° C. and 20 to 40 MPa. In addition, when the densification can be performed only by heating in nitrogen by selecting the auxiliary system, the hot press treatment can be omitted.
【００３７】この焼結体において、種結晶を核として粗
大柱状結晶を成長させる。このようにして得られた窒化
珪素焼結体は、図１（ｄ）及び図２（ｄ）に示されるよ
うに、窒化珪素種結晶２１を核としてエピタキシャル成
長した粗大な窒化珪素柱状結晶２６が特定の方向に配向
した微構造を有する。ここでいう特定の方向とは、前述
の磁場中における成形によって得られた成形体の、種結
晶の配向方向に等しい。従って、磁場の設定をコントロ
ールして任意の方向に配向した種結晶を持つ成形体を得
て、これを焼結することにより、窒化珪素の柱状結晶が
上記任意の方向に配向した窒化珪素焼結部材を得ること
ができる。In this sintered body, coarse columnar crystals are grown with seed crystals as nuclei. In the silicon nitride sintered body thus obtained, as shown in FIGS. 1D and 2D, a coarse silicon nitride columnar crystal 26 epitaxially grown with the silicon nitride seed crystal 21 as a nucleus is specified. Has a microstructure oriented in the direction of. Here, the specific direction is equal to the orientation direction of the seed crystal of the molded body obtained by molding in the above-described magnetic field. Therefore, by controlling the setting of the magnetic field, a molded body having a seed crystal oriented in an arbitrary direction is obtained, and this is sintered, so that the silicon nitride columnar crystal is oriented in the above-mentioned arbitrary direction. A member can be obtained.
【００３８】このように、成形磁場の印加によって異方
性を付与された組織を持つ窒化珪素焼結部材は、繊維状
に発達した窒化珪素柱状結晶の繊維方向に対して高い熱
伝導性を示す。特に本発明においては、磁場中での成形
により任意の方向に種結晶を配向させられるので、従来
得られなかった方向においても高い熱伝導性を得ること
ができる。例えば従来板状部材において板面に平行な方
向にしか得られなかった高い熱伝導性が、板面に垂直な
方向においても１００Ｗ／ｍＫ以上と高い値を示し、こ
のような窒化珪素焼結部材はより広い用途への適用が期
待される。また、成形法が多種多様であり任意の形状を
得ることが可能なので、この点でも形状が板状に限定さ
れていた従来法に比較して適用範囲が広いといえる。さ
らには、従来板状の部材を積層、圧着して得ていた塊状
部材を一回の成形のみで得られるので、時間、手間、コ
ストの面で優れているといえる。As described above, a silicon nitride sintered member having a structure provided with anisotropy by application of a molding magnetic field exhibits high thermal conductivity in the fiber direction of a silicon nitride columnar crystal developed in a fibrous form. . In particular, in the present invention, since the seed crystal can be oriented in an arbitrary direction by molding in a magnetic field, high thermal conductivity can be obtained even in a direction that has not been obtained conventionally. For example, high thermal conductivity, which was conventionally obtained only in a direction parallel to the plate surface in a plate-like member, shows a high value of 100 W / mK or more even in a direction perpendicular to the plate surface. Is expected to be applied to a wider range of applications. In addition, since there are various molding methods and it is possible to obtain an arbitrary shape, it can be said that the applicable range is wider than that of the conventional method in which the shape is limited to a plate shape. Furthermore, since a lump-shaped member obtained by laminating and pressing a plate-shaped member in the past can be obtained only by one molding, it can be said that it is excellent in terms of time, labor, and cost.
【００３９】[0039]
【実施例】(実施例1)本発明の第一の実施例について以
下に説明する。平均粒径０．５μｍのα型窒化珪素粉末
９５重量部及び平均粒径０．４μｍのＹ2Ｏ3粉末５重量
部を、溶媒である水、及び焼結助剤であるアンモニウム
塩系分散剤、及び窒化珪素ボールとともに、ボールミル
用樹脂製ポットに充填し、９６時間粉砕及び混合するこ
とにより、α型窒化珪素粉末と焼結助剤とが十分に混合
及び分散したスラリーを得て、これを別の樹脂製ポット
に移した。次に、無電解めっき法にて表面上に平均厚さ
約０．１μｍの層状Ｆｅめっきを施した平均長さ５μ
ｍ、平均直径１．５μｍの棒状β型窒化珪素（Ｓｉ3Ｎ
4）種結晶を、前記α型窒化珪素粉末１００重量部に対
して２５重量部秤量して前記ポットに投入し、さらに防
錆剤及び樹脂コートボールを加えて１０時間ボールミル
混合を行い、前記各原料粉末が十分に混合及び分散した
スラリーを得た。ここでは溶媒として水を使用したが、
水に代えてエタノール等の有機溶媒を用いても良いこと
は言うまでもない。また、ＰＶＡ（ポリビニルアルコー
ル）やＰＶＢ（ポリビニルブチラール）等のバインダー
を添加してもかまわない。(Embodiment 1) A first embodiment of the present invention will be described below. 95 parts by weight of α-type silicon nitride powder having an average particle diameter of 0.5 μm and 5 parts by weight of Y 2 O 3 powder having an average particle diameter of 0.4 μm were mixed with water as a solvent, an ammonium salt dispersant as a sintering aid, and nitriding. Along with the silicon balls, the mixture was filled in a ball mill resin pot, crushed and mixed for 96 hours to obtain a slurry in which the α-type silicon nitride powder and the sintering aid were sufficiently mixed and dispersed, and this was mixed with another resin. Transferred to pot. Next, a layered Fe plating having an average thickness of about 0.1 μm was formed on the surface by electroless plating to have an average length of 5 μm.
m, rod-shaped β-type silicon nitride (Si3N
4) 25 parts by weight of the seed crystal was weighed with respect to 100 parts by weight of the α-type silicon nitride powder, added to the pot, further added with a rust preventive and a resin-coated ball, and mixed in a ball mill for 10 hours. A slurry in which the raw material powders were sufficiently mixed and dispersed was obtained. Here, water was used as the solvent,
Needless to say, an organic solvent such as ethanol may be used instead of water. Further, a binder such as PVA (polyvinyl alcohol) or PVB (polyvinyl butyral) may be added.
【００４０】次に、得られたスラリーを磁場中において
プレス成形した。用いたプレス成形装置の要部断面図を
図３に示す。外型（ダイス）３２、上パンチ３３、及び
下パンチ３４はいずれも金属材料製である。配向磁場用
コイル３９及び３９’から発した磁力線は、前記スラリ
ー３５を充填したキャビティ３１と、上／下パンチ３３
及び３４と、ダイス３２と、ポールピース３８とを通る
閉磁路（図示省略）を形成し、成形時においてキャビテ
ィ３１に対して５Ｋｏｅ以上の縦磁場を印加し、その結
果、キャビティ３１に充填されたスラリー３５中の種結
晶が配向される。さらに、キャビティ３１に充填された
スラリー３５に対して圧力を印加すると、スラリー３５
に含まれる溶媒成分は、下パンチ３４に設けられた溶媒
排出穴３７から大部分が外部に排出され、その結果、種
結晶が磁場印加（Ｍ）方向に配向した成形体が得られ
る。成形体の亀裂発生を押さえ、かつ脱溶媒を円滑に行
うためには、図３に示されるように、スラリー３５と下
パンチ３４との間に目の細かいフィルター３６を配置す
ることが好ましい。Next, the obtained slurry was press-formed in a magnetic field. FIG. 3 is a cross-sectional view of a main part of the press forming apparatus used. The outer die (die) 32, the upper punch 33, and the lower punch 34 are all made of a metal material. The magnetic lines of force generated from the coils 39 and 39 ′ for the alignment magnetic field are formed by the cavity 31 filled with the slurry 35 and the upper / lower punch 33.
, 34, the die 32, and the pole piece 38, a closed magnetic path (not shown) is formed, and a vertical magnetic field of 5 Koe or more is applied to the cavity 31 during molding. As a result, the cavity 31 is filled. The seed crystals in the slurry 35 are oriented. Further, when pressure is applied to the slurry 35 filled in the cavity 31, the slurry 35
Of the solvent component contained in the lower punch 34 is discharged to the outside through a solvent discharge hole 37 provided in the lower punch 34, and as a result, a molded body in which the seed crystal is oriented in the direction of the magnetic field application (M) is obtained. As shown in FIG. 3, it is preferable to dispose a fine filter 36 between the slurry 35 and the lower punch 34 in order to suppress the occurrence of cracks in the molded body and smoothly remove the solvent.
【００４１】図５の磁場成形装置において、キャビティ
３１に充填するスラリー３５の量を調節することによ
り、それぞれ異なる厚み寸法を持った円盤状ないしは円
筒状の成形体を製作した。このとき、縦磁場強度は１５
Ｋｏｅ、パンチ圧力は２０ＭＰａとした。この成形体を
一旦大気中において自然乾燥した後、１０ｍＰａの真空
中にて１０００℃で２時間加熱し、その後希塩酸水溶液
中に浸漬して種結晶表面上のＦｅを溶解除去した。希塩
酸水溶液中に浸漬する前に加熱を行うのは、成形体の安
定性を高めて希塩酸水溶液浸漬時における成形体中の粒
子流出を防ぐためである。従って自然乾燥のままでも成
形体の安定性が高い場合には、前記加熱を省略しても良
い。また、前記加熱を真空中で行うのは、原料である窒
化珪素及び窒化珪素表面上にコーティングされたＦｅの
酸化を防ぐためである。従って、非酸化性ガス、例えば
窒素ガス、アルゴンガス等を使用しても良い。なお、バ
インダーを添加した場合には、この工程において脱バイ
ンダーを行うことが望ましい。In the magnetic field forming apparatus shown in FIG. 5, by adjusting the amount of the slurry 35 to be filled in the cavity 31, disk-shaped or cylindrical shaped bodies having different thickness dimensions were manufactured. At this time, the longitudinal magnetic field intensity is 15
Koe and the punch pressure were 20 MPa. The formed body was once air-dried in the air, heated at 1000 ° C. for 2 hours in a vacuum of 10 mPa, and then immersed in a dilute hydrochloric acid aqueous solution to dissolve and remove Fe on the surface of the seed crystal. The reason why the heating is performed before immersion in the dilute hydrochloric acid aqueous solution is to enhance the stability of the molded body and prevent particles from flowing out of the molded body during immersion in the dilute hydrochloric acid aqueous solution. Therefore, the heating may be omitted when the stability of the molded body is high even if it is naturally dried. The reason why the heating is performed in a vacuum is to prevent oxidation of silicon nitride as a raw material and Fe coated on the surface of the silicon nitride. Therefore, a non-oxidizing gas, for example, a nitrogen gas, an argon gas or the like may be used. When a binder is added, it is desirable to remove the binder in this step.
【００４２】次に、得られた成形体を大気中において自
然乾燥した後、ゴム袋中に充填し、圧力１００ＭＰａに
おいてＣＩＰ（冷間静水圧プレス）処理を行った。この
処理は、前記成形体においてＦｅを溶解除去した際、そ
の部分に生じた空隙を押し潰すための処理であり、高密
度の焼結体を得るための望ましい処理であるが、省略す
ることも可能である。Next, the obtained molded body was air-dried in the air, filled in a rubber bag, and subjected to a CIP (cold isostatic pressing) treatment at a pressure of 100 MPa. This process is a process for crushing the voids generated in the portion when Fe is dissolved and removed in the compact, and is a desirable process for obtaining a high-density sintered body, but may be omitted. It is possible.
【００４３】次に、得られたＣＩＰ処理品を黒鉛ダイス
中に装填し、１気圧のＮ2雰囲気中で１９００℃、２０
ＭＰａにおいて３時間ホットプレス焼結を行い、外径が
５０ｍｍで厚さがそれぞれ１ｍｍ、３０ｍｍ、５０ｍｍ
である３種類の焼結体を製作した。得られた焼結体をそ
れぞれ切断し、微細構造（ミクロ組織）を観察した結
果、種結晶が磁場印加方向に沿って配向及び成長したこ
とが確認できた。また、上記焼結体はいずれも、理論密
度に対する相対密度が９８％以上で緻密なことがわかっ
た。次に、上記各焼結体より試験片を切り出して、それ
ぞれについて曲げ強さ、破壊靱性値（Ｋic）、及び熱伝
導率を測定した。種結晶の配向平均方向に沿って引張応
力を加える試験において、３点曲げ強さは９００ＭＰａ
以上、破壊靱性値は８ＭＰａ√ｍ以上であった。また、
レーザーフラッシュ法によって熱伝導率を測定した結
果、種結晶の配向平均方向において１２０〜１３０Ｗ／
ｍＫ、種結晶の配向平均方向に直角な方向において８０
〜９０Ｗ／ｍＫであった。Next, the obtained CIP-treated product was charged into a graphite die, and was heated at 1900 ° C. and 20 ° C. in a 1 atm N 2 atmosphere.
Perform hot press sintering at 3MPa for 3 hours, outer diameter 50mm, thickness 1mm, 30mm, 50mm respectively
The following three types of sintered bodies were manufactured. Each of the obtained sintered bodies was cut, and the microstructure (microstructure) was observed. As a result, it was confirmed that the seed crystal was oriented and grown along the direction in which the magnetic field was applied. In addition, it was found that all of the above sintered bodies were dense with a relative density to the theoretical density of 98% or more. Next, a test piece was cut out from each of the above sintered bodies, and the bending strength, fracture toughness value (Kic), and thermal conductivity were measured for each. In a test in which a tensile stress is applied along the average orientation direction of the seed crystal, the three-point bending strength is 900 MPa.
As described above, the fracture toughness value was 8 MPa√m or more. Also,
As a result of measuring the thermal conductivity by the laser flash method, 120 to 130 W / in the average orientation direction of the seed crystal.
mK, 80 in the direction perpendicular to the average orientation direction of the seed crystal
９０90 W / mK.
【００４４】（実施例2）次に、本発明の第二の実施例
について説明する。平均粒径０．５μｍのα型窒化珪素
粉末９５重量部、及び焼結助剤として平均粒径０．３μ
ｍのＭｇＯ粉末５重量部を、溶媒である水、及びアンモ
ニウム塩系の分散剤、及びバインダーであるメチルセル
ロースとともにボールミル用樹脂製ポットに充填して９
６時間粉砕及び混合することにより、上記各材料が十分
に混合及び分散したスラリーを得て、これを別の樹脂製
ポットに移した。次に、無電解めっき法にて表面上に平
均厚さ約０．１μｍの層状Ｎｉめっきを施した平均長さ
２μｍ、平均直径０．５μｍの棒状β型窒化珪素（Ｓｉ
3Ｎ4）種結晶を、前記α型窒化珪素粉末１００重量部に
対して１０重量部秤量して前記ポットに投入し、さらに
樹脂コートボールを加えて１０時間ボールミル混合を行
い、前記各原料粉末が十分に混合及び分散したスラリー
を得た。(Embodiment 2) Next, a second embodiment of the present invention will be described. 95 parts by weight of α-type silicon nitride powder having an average particle diameter of 0.5 μm, and an average particle diameter of 0.3 μm as a sintering aid
5 parts by weight of MgO powder of m, together with water as a solvent, an ammonium salt-based dispersant, and methylcellulose as a binder, were charged into a resin pot for ball milling, and then 9
By crushing and mixing for 6 hours, a slurry in which the above-mentioned materials were sufficiently mixed and dispersed was obtained, and this was transferred to another resin pot. Next, a rod-shaped β-type silicon nitride (Si) having an average length of 2 μm and an average diameter of 0.5 μm obtained by applying a layered Ni plating having an average thickness of about 0.1 μm on the surface by electroless plating.
3N4) Seed crystal was weighed at 10 parts by weight with respect to 100 parts by weight of the α-type silicon nitride powder, added to the pot, and further added with a resin-coated ball and mixed with a ball mill for 10 hours. To obtain a slurry mixed and dispersed.
【００４５】次に、得られたスラリーを、図６に示す装
置を用いてドクターブレード法により成形した。まず、
前記スラリー３５を貯蔵容器４１に投入する。スラリー
３５は貯蔵容器４１の下部に形成された開口部４２から
排出され、ローラー４３により供給されるフィルム４４
上に載せられて板状成形体２９を形成する。このとき、
板状成形体２９の厚さは開口部４２の開口サイズにより
規定されたほぼ一定の厚さとなる。板状成形体２９は、
ローラー４３の回転に従ってさらに移動する。その移動
方向には磁場配向装置４５が配置されている。磁場配向
装置４５は、板状成形体２９を載せたフィルム４４を磁
場配向空間４６内に導く案内開口部４７と磁場配向空間
４６外に送り出す案内開口部４７’とを有しているが、
他の構成は図５に示した装置と同様である。移動してき
た板状成形体２９を一旦停止させ、Ｍ方向に平行磁場を
印加しながら、上パンチ３３及び下パンチ３４によりそ
の間にある長さｌ分の板状成形体２９を加圧し、その
後、再び板状成形体２９を長さｌ分だけ移動させる。こ
のサイクルを連続して行うことにより、板状成形体２９
を全長にわたって効率よく磁場配向させることができ
る。本実施例においては、板状成形体２９の板厚方向に
対して実質的な垂直方向に２０Ｋｏｅの静磁場を印加し
て、板状成形体２９中に含まれる種結晶をフィルム４４
面に対してほぼ垂直方向（磁場印加方向Ｍに対してほぼ
平行方向）に配向させた。その後、板状成形体２９はロ
ーラー４３の回転に従ってさらに移動し、ロール上に巻
き取られるが、その途上において空中で自然乾燥され
る。なお、このとき乾燥を速めるために赤外ヒータ、フ
ァンヒータ等の乾燥器を設けても良い。Next, the obtained slurry was formed by a doctor blade method using an apparatus shown in FIG. First,
The slurry 35 is put into the storage container 41. The slurry 35 is discharged from an opening 42 formed in the lower part of the storage container 41 and is supplied by a roller 43 to a film 44.
The plate-shaped molded body 29 is formed on the upper surface. At this time,
The thickness of the plate-like molded body 29 is substantially constant, which is defined by the size of the opening 42. The plate-like molded body 29 is
It further moves according to the rotation of the roller 43. A magnetic field alignment device 45 is arranged in the moving direction. The magnetic field orientation device 45 has a guide opening 47 that guides the film 44 on which the plate-shaped formed body 29 is placed into the magnetic field orientation space 46 and a guide opening 47 ′ that sends the film 44 out of the magnetic field orientation space 46.
Other configurations are the same as those of the device shown in FIG. While temporarily moving the plate-like molded body 29 that has moved, while applying a parallel magnetic field in the M direction, the upper punch 33 and the lower punch 34 press the plate-like molded body 29 for a length l therebetween, and thereafter, The plate-shaped molded body 29 is moved again by the length l. By continuously performing this cycle, the plate-like molded body 29
Can be efficiently magnetically oriented over the entire length. In the present embodiment, a static magnetic field of 20 Koe is applied in a direction substantially perpendicular to the thickness direction of the plate-shaped molded body 29, so that the seed crystal contained in the plate-shaped molded body 29 is
It was oriented in a direction substantially perpendicular to the plane (in a direction substantially parallel to the magnetic field application direction M). Thereafter, the plate-like molded body 29 further moves in accordance with the rotation of the roller 43 and is wound on a roll, and is naturally dried in the air on the way. At this time, a dryer such as an infrared heater or a fan heater may be provided to speed up the drying.
【００４６】次に、ロール状に巻き取った板状成形体２
９を、大気中において５００℃で１０時間加熱し、バイ
ンダーであるメチルセルロースを分解及び除去した。そ
の後、窒素ガス雰囲気中において、１７５０℃で５時間
加熱することにより、厚さ０．７ｍｍの平板状焼結体を
得た。この焼結体から試験片を切り出し、実施例１と同
様の手段で曲げ強さ及び熱伝導率を測定した。表面研削
仕上げを施した平板材について３点曲げテストを行った
結果、７００Ｍｐａ以上の曲げ強さであった。また、こ
の平板の垂直方向（種結晶の配向平均方向と同一の方
向）における熱伝導率は１３０Ｗ／ｍＫであった。Next, the plate-like molded product 2 wound into a roll shape
9 was heated in the air at 500 ° C. for 10 hours to decompose and remove methylcellulose as a binder. Thereafter, by heating in a nitrogen gas atmosphere at 1750 ° C. for 5 hours, a flat sintered body having a thickness of 0.7 mm was obtained. A test piece was cut out from this sintered body, and the bending strength and the thermal conductivity were measured by the same means as in Example 1. As a result of performing a three-point bending test on the flat-plate material subjected to the surface grinding finish, the bending strength was 700 Mpa or more. The thermal conductivity of this flat plate in the vertical direction (the same direction as the average orientation direction of the seed crystal) was 130 W / mK.
【００４７】（実施例３）次に、本発明の第三の実施例
について説明する。平均粒径０．５μｍのα型窒化珪素
粉末９５重量部、及び焼結助剤として平均粒径０．３μ
ｍのＹ2Ｏ3粉末５重量部を、溶媒である水、及びアンモ
ニウム塩系の分散剤、及び窒化珪素ボールとともにボー
ルミル用樹脂製ポットに充填して９６時間粉砕及び混合
することにより、上記各材料が十分に混合及び分散した
スラリーを得て、これを別の樹脂製ポットに移した。次
に、無電解めっき法にて表面上に平均厚さ約０．２μｍ
の層状Ｎｉめっきを施した平均長さ４μｍ、平均直径
１．０μｍの棒状β型窒化珪素（Ｓｉ3Ｎ4）種結晶を、
前記焼結助剤に対して１０重量部秤量して前記ポットに
投入し、さらに防錆剤及び樹脂コートボールを加えて１
０時間ボールミル混合を行い、前記各原料粉末が十分に
混合及び分散したスラリーを得た。以後は実施例１と同
様にして厚さ４０ｍｍの円筒形焼結部材を得た。この焼
結部材をブロック状に切り出して研磨したものを図５に
示した。焼結部材２８の破面を走査電子顕微鏡で観察し
たところ、窒化珪素柱状結晶２６は、図５に示した特定
のＰ方向に対して±１０°以内に配向していた。また、
窒化珪素柱状結晶２６間に粒界相５１が観察された。窒
化珪素柱状結晶２６と粒界相５１との体積比率を断面写
真により計測した結果、９５：５であった。また、実施
例１と同様の手段により、配向方向Ｐに対して垂直方向
に荷重を印加したときの３点曲げ強さを測定した結果、
１５００Ｍｐａであった。また、実施例１と同様の手段
により熱伝導率を測定した結果は１４０Ｗ／ｍＫであ
り、きわめて良好であった。(Embodiment 3) Next, a third embodiment of the present invention will be described. 95 parts by weight of α-type silicon nitride powder having an average particle diameter of 0.5 μm, and an average particle diameter of 0.3 μm as a sintering aid
5 parts by weight of Y 2 O 3 powder together with water as a solvent, an ammonium salt-based dispersant, and a silicon nitride ball are charged into a resin pot for a ball mill, and crushed and mixed for 96 hours. To obtain a slurry which was mixed and dispersed in the above, and transferred to another resin pot. Next, the average thickness is about 0.2 μm on the surface by electroless plating.
A rod-shaped β-type silicon nitride (Si 3 N 4) seed crystal having an average length of 4 μm and an average diameter of 1.0 μm on which a layered Ni plating of
10 parts by weight of the sintering aid was weighed and put into the pot, and a rust inhibitor and a resin-coated ball were added thereto to add 1 part.
The mixture was subjected to ball mill mixing for 0 hour to obtain a slurry in which the respective raw material powders were sufficiently mixed and dispersed. Thereafter, a cylindrical sintered member having a thickness of 40 mm was obtained in the same manner as in Example 1. FIG. 5 shows the sintered member cut out into a block shape and polished. When the fracture surface of the sintered member 28 was observed with a scanning electron microscope, the silicon nitride columnar crystals 26 were oriented within ± 10 ° with respect to the specific P direction shown in FIG. Also,
A grain boundary phase 51 was observed between the columnar silicon nitride crystals 26. The volume ratio between the silicon nitride columnar crystals 26 and the grain boundary phase 51 was measured by a cross-sectional photograph, and as a result, was 95: 5. Further, as a result of measuring the three-point bending strength when a load was applied in the direction perpendicular to the orientation direction P by the same means as in Example 1,
It was 1500 Mpa. The result of measuring the thermal conductivity by the same means as in Example 1 was 140 W / mK, which was extremely good.
【００４８】以上、実施例１〜３に示されるように、本
発明の窒化珪素焼結部材において、窒化珪素柱状結晶の
体積比率は５０％以上、より好ましくは７０％以上、特
に好ましくは９０％以上とすると良い。このとき、その
平均の配向方向において、３点曲げ強さは１００ＭＰａ
以上、熱伝導率は８０Ｗ／（ｍ・Ｋ）以上となる。As described above, as shown in Examples 1 to 3, in the silicon nitride sintered member of the present invention, the volume ratio of the columnar silicon nitride crystal is at least 50%, more preferably at least 70%, particularly preferably at least 90%. It is good to do above. At this time, in the average orientation direction, the three-point bending strength is 100 MPa.
As described above, the thermal conductivity is 80 W / (m · K) or more.
【００４９】次に、図６〜図８において、本発明の窒化
珪素焼結部材における別の態様を模式的に示す。図６は
板状部材２８において、窒化珪素柱状結晶２９が板面６
１に対して垂直に配向している場合である。図７はリン
グ状部材７１において、軸方向に沿って窒化珪素柱状結
晶２９が配向している場合である。図８は不定形部材８
１において、突起部８２の突出方向に沿って窒化珪素柱
状結晶２９が配向している場合である。Next, FIGS. 6 to 8 schematically show another embodiment of the silicon nitride sintered member of the present invention. FIG. 6 shows a plate member 28 in which silicon nitride columnar crystals 29
This is the case where they are oriented perpendicular to 1. FIG. 7 shows a case where the silicon nitride columnar crystals 29 are oriented along the axial direction in the ring-shaped member 71. FIG. 8 shows an irregular shaped member 8.
1, the case where the silicon nitride columnar crystals 29 are oriented along the direction in which the projections 82 project.
【００５０】上記実施例において用いた配向磁場は、ず
べて加圧方向と磁場印加方向とが平行（縦磁場成形）で
あったが、加圧方向と磁場印加方向とが直交する横磁場
成形を適用すれば、最終的に得られる本発明の焼結部材
において、窒化珪素柱状結晶の配向をさらに均一化する
ことができる。In the orientation magnetic field used in the above-described embodiment, the pressing direction and the magnetic field applying direction were all parallel (vertical magnetic field forming), but the horizontal magnetic field forming in which the pressing direction and the magnetic field applying direction were orthogonal was performed. When applied, the orientation of the silicon nitride columnar crystals can be further uniformed in the finally obtained sintered member of the present invention.
【００５１】[0051]
【発明の効果】以上示したように、本発明によれば、結
晶が任意の方向に配向した窒化珪素部材を板状、塊状の
形状によらず得られる。このような窒化珪素焼結体は、
結晶の配向方向に高い熱伝導性を示す。特に、板面に垂
直な方向に１００Ｗ／ｍＫの熱伝導度を示す板状材料を
得ることができ、これらは高温構造材料や高熱伝導性材
料として有用である。As described above, according to the present invention, a silicon nitride member having crystals oriented in an arbitrary direction can be obtained irrespective of a plate-like or lump-like shape. Such a silicon nitride sintered body is
Shows high thermal conductivity in the crystal orientation direction. In particular, a plate-like material having a thermal conductivity of 100 W / mK in a direction perpendicular to the plate surface can be obtained, and these are useful as a high-temperature structural material or a high thermal conductive material.
【図１】本発明の原理の概略を示す説明図である。FIG. 1 is an explanatory view schematically showing the principle of the present invention.
【図２】本発明の原理の概略を示す説明図である。FIG. 2 is an explanatory view schematically showing the principle of the present invention.
【図３】本発明に用いる磁場配向装置の一例を示す要部
断面図である。FIG. 3 is a sectional view of a main part showing an example of a magnetic field alignment device used in the present invention.
【図４】本発明に用いる成形方法の一例を示す要部断面
図である。FIG. 4 is a sectional view of a main part showing an example of a molding method used in the present invention.
【図５】本発明の焼結材における一例を示す模式図であ
る。FIG. 5 is a schematic view showing an example of the sintered material of the present invention.
【図６】本発明の焼結材における別の例を示す模式図で
ある。FIG. 6 is a schematic view showing another example of the sintered material of the present invention.
【図７】本発明の焼結材におけるさらに別の例を示す模
式図である。FIG. 7 is a schematic view showing still another example of the sintered material of the present invention.
【図８】本発明の焼結材におけるさらに別の例を示す模
式図である。FIG. 8 is a schematic view showing still another example of the sintered material of the present invention.
【図９】従来方法の原理の概略を示す説明図である。FIG. 9 is an explanatory view schematically showing the principle of a conventional method.
【図１０】従来方法の原理の概略を示す説明図である。FIG. 10 is an explanatory view schematically showing the principle of a conventional method.
２１ 窒化珪素種結晶 ２２ β型窒化珪素種結晶 ２３ 窒化珪素原料 ２４ 磁性金属 ２５ 磁力線 ２６ 窒化珪素柱状結晶 ２７ 窒化珪素粒状結晶母相 ２８ 焼結部材 ２９ 板状成形体 ３１ キャビティ ３２ ダイス（外型） ３３ 上パンチ ３４ 下パンチ ３５ スラリー ３６ フィルター ３７ 溶媒排出穴 ３８ ポールピース ３９，３９’配向磁場用コイル ４１ 貯蔵容器 ４２ 開口部 ４３ ローラー ４４ フィルム ４５ 磁場配向装置 ４６ 磁場配向空間 ４７，４７’案内開口部 ５１ 粒界相 ６１ 板面 ７１ リング状部材 ８１ 不定形部材 ８２ 突起部 Reference Signs List 21 silicon nitride seed crystal 22 β-type silicon nitride seed crystal 23 silicon nitride raw material 24 magnetic metal 25 magnetic field line 26 silicon nitride columnar crystal 27 silicon nitride granular crystal mother phase 28 sintered member 29 plate-shaped formed body 31 cavity 32 die (outer die) 33 Upper punch 34 Lower punch 35 Slurry 36 Filter 37 Solvent discharge hole 38 Pole piece 39, 39 'Orienting magnetic field coil 41 Storage container 42 Opening 43 Roller 44 Film 45 Magnetic field aligner 46 Magnetic field aligning space 47, 47' Guide opening 51 Grain Boundary Phase 61 Plate Surface 71 Ring Member 81 Irregular Member 82 Projection
Claims (18)
を配向したことを特徴とする窒化珪素焼結部材。1. A silicon nitride sintered member wherein silicon nitride (Si3 N4) crystals are oriented in an arbitrary direction.
又は針状の窒化珪素結晶を窒化珪素粉末及び焼結助剤を
含む窒化珪素焼結原料中に添加して分散させ、磁場中に
おいて成形を行い、その後、焼結して得られることを特
徴とする請求項１に記載の窒化珪素焼結部材。2. A rod-shaped or needle-shaped silicon nitride crystal having a surface coated with a magnetic metal is added and dispersed in a silicon nitride sintering raw material containing silicon nitride powder and a sintering aid, and molded in a magnetic field. 2. The silicon nitride sintered member according to claim 1, obtained by sintering.
又は針状の窒化珪素結晶を窒化珪素粉末及び焼結助剤を
含む窒化珪素焼結原料中に添加して分散させ、磁場中に
おいて成形を行った後にコーティングした金属を溶解、
又は蒸発によって除去し、その後、焼結して得られるこ
とを特徴とする請求項１に記載の窒化珪素焼結部材。3. A rod-shaped or needle-shaped silicon nitride crystal having a surface coated with a magnetic metal is dispersed in a silicon nitride sintering raw material containing silicon nitride powder and a sintering aid, and is molded in a magnetic field. After dissolving the coated metal,
The silicon nitride sintered member according to claim 1, wherein the silicon nitride sintered member is obtained by removing by evaporation and thereafter sintering.
ィングする方法が、蒸着、スパッタリング、又は湿式の
化学メッキのいずれかであることを特徴とする請求項２
又は請求項４に記載の窒化珪素焼結部材。4. The method according to claim 2, wherein the method of coating the surface of the silicon nitride crystal with the magnetic metal is any one of vapor deposition, sputtering, and wet chemical plating.
Or the sintered silicon nitride member according to claim 4.
又は針状の窒化珪素結晶の添加量が１ｗｔ％から１００
ｗｔ％であることを特徴とする請求項２〜４のいずれか
一に記載の窒化珪素焼結部材。5. An addition amount of a rod-like or needle-like silicon nitride crystal whose surface is coated with a magnetic metal is from 1 wt% to 100 wt%.
The sintered silicon nitride member according to any one of claims 2 to 4, wherein the content is wt%.
鋳込み、押出し、ドクターブレード法、又はＣＩＰ（Co
ld Isostatic Pressing ）のいずれかであることを特徴
とする請求項２〜５のいずれか一に記載の窒化珪素焼結
部材。6. The method of molding in a magnetic field includes pressing, injection,
Casting, extrusion, doctor blade method or CIP (Co
ld Isostatic Pressing). The sintered silicon nitride member according to any one of claims 2 to 5, wherein:
ることを特徴とする請求項２〜６のいずれか一に記載の
窒化珪素焼結部材。7. The silicon nitride sintered member according to claim 2, wherein the strength of the magnetic field during molding is 5 Koe or more.
状であることを特徴とする請求項２〜７のいずれか一に
記載の窒化珪素焼結部材。8. The silicon nitride sintered member according to claim 2, wherein the silicon nitride sintering raw material is in the form of powder or slurry.
項１〜８のいずれか一に記載の窒化珪素焼結部材。9. The silicon nitride sintered member according to claim 1, wherein the shape is a lump.
方向に窒化珪素結晶を配向し、この方向の熱伝導率が１
００Ｗ／ｍＫ以上であることを特徴とする請求項１〜９
のいずれか一に記載の窒化珪素焼結部材。10. A silicon nitride crystal having a plate-like shape and oriented in a direction perpendicular to a plate surface, and having a thermal conductivity of 1 in this direction.
10. It is at least 00 W / mK.
The sintered silicon nitride member according to any one of the above.
ることを特徴とする窒化珪素焼結部材の製造方法。11. A method for manufacturing a silicon nitride sintered member, wherein a silicon nitride crystal is oriented in an arbitrary direction.
状又は針状の窒化珪素結晶を窒化珪素粉末及び焼結助剤
を含む窒化珪素焼結原料中に添加して分散させ、磁場中
において成形を行い、その後、焼結することを特徴とす
る請求項１１に記載の窒化珪焼結部材の製造方法。12. A rod-shaped or needle-shaped silicon nitride crystal having a surface coated with a magnetic metal is added and dispersed in a silicon nitride sintering raw material containing silicon nitride powder and a sintering aid, and molded in a magnetic field. The method of manufacturing a silicon nitride sintered member according to claim 11, further comprising sintering.
状又は針状の窒化珪素結晶を窒化珪素粉末及び焼結助剤
を含む窒化珪素焼結原料中に添加して分散させ、磁場中
において成形を行った後に、コーティングした金属を溶
解、又は蒸発により除去し、その後、焼結することを特
徴とする請求項１１に記載の窒化珪素焼結部材の製造方
法。13. A rod-shaped or needle-shaped silicon nitride crystal having a surface coated with a magnetic metal is added and dispersed in a silicon nitride sintering raw material containing silicon nitride powder and a sintering aid, and is formed in a magnetic field. The method for manufacturing a silicon nitride sintered member according to claim 11, wherein after coating, the coated metal is removed by melting or evaporation, and thereafter, sintering is performed.
めっきのいずれかによって磁性金属を窒化珪素結晶の表
面にコーティングすることを特徴とする請求項１２又は
請求項１３に記載の窒化珪素部材の製造方法。14. The method according to claim 12, wherein the surface of the silicon nitride crystal is coated with a magnetic metal by one of vapor deposition, sputtering, and wet chemical plating.
状又は針状の窒化珪素結晶を１ｗｔ％から１００ｗｔ％
添加することを特徴とする請求項１２〜１４のいずれか
一に記載の窒化珪素焼結体の製造方法。15. A rod-shaped or needle-shaped silicon nitride crystal having a surface coated with a magnetic metal in an amount of 1 wt% to 100 wt%.
The method for producing a silicon nitride sintered body according to any one of claims 12 to 14, wherein the addition is performed.
ターブレード法、又はＣＩＰのいずれかの成形を磁場中
において行うことを特徴とする請求項１２〜１５のいず
れか一に記載の窒化珪素焼結部材の製造方法。16. The silicon nitride sinter according to claim 12, wherein any one of pressing, injection, casting, extrusion, doctor blade method, and CIP is performed in a magnetic field. Manufacturing method of the member.
成形を行うことを特徴とする請求項１２〜１６のいずれ
か一に記載の窒化珪素焼結部材の製造方法。17. The method for producing a silicon nitride sintered member according to claim 12, wherein the forming is performed in a magnetic field having a strength of 5 Koe or more.
原料を用いることを特徴とする請求項１２〜１７のいず
れか一に記載の窒化珪素焼結部材の製造方法。18. The method for producing a silicon nitride sintered member according to claim 12, wherein a powdery or slurry-like silicon nitride sintered material is used.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10021132A JPH11217272A (en) | 1998-02-02 | 1998-02-02 | Silicon nitride sintered member having oriented crystal and its production |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10021132A JPH11217272A (en) | 1998-02-02 | 1998-02-02 | Silicon nitride sintered member having oriented crystal and its production |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH11217272A true JPH11217272A (en) | 1999-08-10 |
Family
ID=12046379
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10021132A Pending JPH11217272A (en) | 1998-02-02 | 1998-02-02 | Silicon nitride sintered member having oriented crystal and its production |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH11217272A (en) |
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|---|---|---|---|---|
| JP2002128568A (en) * | 2000-10-18 | 2002-05-09 | Ngk Insulators Ltd | Corrosion-resistant component |
| JP2007153645A (en) * | 2005-12-01 | 2007-06-21 | National Institute For Materials Science | Laminate for nanotechnology formed by using flaky powder and method for manufacturing the same |
| JP2011184288A (en) * | 2010-02-10 | 2011-09-22 | Canon Inc | Method for producing oriented oxide ceramic, oriented oxide ceramic, piezoelectric element, liquid ejection head, ultrasonic motor and dust removing device |
| WO2011136131A1 (en) | 2010-04-27 | 2011-11-03 | Canon Kabushiki Kaisha | Method of manufacturing ceramics and piezoelectric material |
| JP2012236743A (en) * | 2011-05-12 | 2012-12-06 | Mitsubishi Materials Corp | CERAMIC SINTERED PLATE CONTAINING UNIAXIALLY ORIENTED ACICULAR Si3N4 PARTICLE |
| WO2016140359A1 (en) * | 2015-03-05 | 2016-09-09 | 公益財団法人神奈川科学技術アカデミー | Ceramic including aligned crystals, production process therefor, and heat radiation material |
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1998
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Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002128568A (en) * | 2000-10-18 | 2002-05-09 | Ngk Insulators Ltd | Corrosion-resistant component |
| JP4641609B2 (en) * | 2000-10-18 | 2011-03-02 | 日本碍子株式会社 | Corrosion resistant material |
| JP2007153645A (en) * | 2005-12-01 | 2007-06-21 | National Institute For Materials Science | Laminate for nanotechnology formed by using flaky powder and method for manufacturing the same |
| JP2011184288A (en) * | 2010-02-10 | 2011-09-22 | Canon Inc | Method for producing oriented oxide ceramic, oriented oxide ceramic, piezoelectric element, liquid ejection head, ultrasonic motor and dust removing device |
| WO2011136131A1 (en) | 2010-04-27 | 2011-11-03 | Canon Kabushiki Kaisha | Method of manufacturing ceramics and piezoelectric material |
| US8702885B2 (en) | 2010-04-27 | 2014-04-22 | Canon Kabushiki Kaisha | Method of manufacturing ceramics and piezoelectric material |
| KR101431369B1 (en) * | 2010-04-27 | 2014-08-19 | 캐논 가부시끼가이샤 | Method of manufacturing ceramics and piezoelectric material |
| JP2012236743A (en) * | 2011-05-12 | 2012-12-06 | Mitsubishi Materials Corp | CERAMIC SINTERED PLATE CONTAINING UNIAXIALLY ORIENTED ACICULAR Si3N4 PARTICLE |
| WO2016140359A1 (en) * | 2015-03-05 | 2016-09-09 | 公益財団法人神奈川科学技術アカデミー | Ceramic including aligned crystals, production process therefor, and heat radiation material |
| JPWO2016140359A1 (en) * | 2015-03-05 | 2018-01-11 | 地方独立行政法人神奈川県立産業技術総合研究所 | CRYSTAL-ORIENTED CERAMIC, ITS MANUFACTURING METHOD, AND HEAT-RELEASE MATERIAL |
| US10323168B2 (en) | 2015-03-05 | 2019-06-18 | Kanagawa Institute Of Industrial Science And Technology | Crystal oriented ceramicscrystal oriented ceramics, the production process, and heat radiation material |
| JP2017214264A (en) * | 2016-06-02 | 2017-12-07 | 住友電気工業株式会社 | Production method of nitride sintered compact |
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