JPH1160355A - Silicon nitride composite material having multilayer structure and its production - Google Patents

Silicon nitride composite material having multilayer structure and its production

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Publication number
JPH1160355A
JPH1160355A JP21088297A JP21088297A JPH1160355A JP H1160355 A JPH1160355 A JP H1160355A JP 21088297 A JP21088297 A JP 21088297A JP 21088297 A JP21088297 A JP 21088297A JP H1160355 A JPH1160355 A JP H1160355A
Authority
JP
Japan
Prior art keywords
silicon nitride
layer
composite material
powder
porosity
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
Application number
JP21088297A
Other languages
Japanese (ja)
Inventor
Chihiro Kawai
千尋 河合
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sumitomo Electric Industries Ltd
Original Assignee
Sumitomo Electric Industries Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Sumitomo Electric Industries Ltd filed Critical Sumitomo Electric Industries Ltd
Priority to JP21088297A priority Critical patent/JPH1160355A/en
Publication of JPH1160355A publication Critical patent/JPH1160355A/en
Pending legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
    • C04B41/009—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone characterised by the material treated
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
    • C04B41/45—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
    • C04B41/50—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials
    • C04B41/5022—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials with vitreous materials
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
    • C04B41/45—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
    • C04B41/50—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials
    • C04B41/5025—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials with ceramic materials
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
    • C04B41/45—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
    • C04B41/50—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials
    • C04B41/51—Metallising, e.g. infiltration of sintered ceramic preforms with molten metal

Abstract

PROBLEM TO BE SOLVED: To obtain a silicon nitride composite material lighter in weight and having a low coefft. of friction. SOLUTION: The silicon nitride composite material consists of a silicon nitride porous body (support layer) consisting of columnar silicon nitride particles having an average aspect ratio of >=3 and an oxide bonding phase and having 30-70% porosity, <=12 μm average pore diameter and >=100 MPa three-point bending strength and a ceramic, glass or metallic layer (surface layer) having $20% porosity and >=1 μm thickness formed on at least one surface part of the porous body.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【発明の属する技術分野】本発明は、軽量、高強度、低
摩擦特性、高気密性を持つ窒化ケイ素複合材料とその製
法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicon nitride composite material having light weight, high strength, low friction characteristics and high airtightness, and a method for producing the same.

【０００２】[0002]

【従来の技術】近年の環境問題への対応から、自動車関
連分野では燃費の向上を図るため、エンジンの軽量化や
高効率化のために動弁系等のエンジン材料としてセラミ
ックスを使用する試みがおこなわれている。特に窒化ケ
イ素系セラミックスは高強度、低比重、低摩擦材料のた
め最も有望視されている。セラミックス化が有望なエン
ジン部品の例としては、排気バルブ、タペットシム等が
ある。これらの材料は、実用時の強度的負荷に耐えるこ
とができれば、軽量であればあるほど燃費向上に対する
効果は高い。2. Description of the Related Art In response to recent environmental problems, attempts have been made to use ceramics as an engine material for a valve train or the like in order to improve fuel efficiency in the automobile-related field, and to reduce the weight and increase the efficiency of the engine. It is being done. In particular, silicon nitride ceramics are regarded as the most promising because of their high strength, low specific gravity, and low friction material. Examples of promising engine parts include exhaust valves, tappet shims, and the like. As long as these materials can withstand the strength load at the time of practical use, the lighter the weight, the higher the effect on fuel efficiency improvement.

【０００３】しかし、緻密な窒化ケイ素系焼結体を用い
る限りこれ以上の軽量化はできない。比重を低下させる
方法として窒化ケイ素材料を多孔質化することが考えら
れるが、気孔率の増加に伴い強度が大きく低下すること
に加え、多孔体であるために上記のような動弁系の摺動
部材として使用した場合に摩擦係数が高くなり磨耗や焼
き付きを発生させる。However, a further reduction in weight cannot be achieved as long as a dense silicon nitride-based sintered body is used. As a method of reducing the specific gravity, it is conceivable to make the silicon nitride material porous. However, in addition to the significant decrease in strength with an increase in porosity, the sliding of the valve train described above due to the porous body is considered. When used as a moving member, the coefficient of friction increases, causing wear and seizure.

【０００４】セラミックス多孔体の表面部に気孔率の低
い層を形成して高強度化する方法も考えられている。例
えば、粉体および粉末冶金第４１巻第３号のＰ３１３〜
Ｐ３１６にはＡｌ2Ｏ3多孔体ではＡｌ2Ｏ3スラリーを鋳
込み法等で表面に堆積後焼成して両面に緻密層を設けて
サンドイッチ構造のセラミックスを創製することによ
り、高強度化に成功した研究もある。A method of forming a layer having a low porosity on the surface of a porous ceramic body to increase the strength has been considered. For example, Powder and Powder Metallurgy Vol. 41, No. 3, P313-
In P316, for Al 2 O 3 porous material, Al 2 O 3 slurry was deposited on the surface by a casting method or the like and fired, and dense layers were provided on both surfaces to create a sandwich-structured ceramic, thereby achieving high strength. There is also research.

【０００５】しかし、このような従来のセラミックス多
孔体を用いた場合、大きな強度向上は達成できない。そ
の理由は以下に説明される。However, when such a conventional porous ceramic body is used, a great improvement in strength cannot be achieved. The reason is explained below.

【０００６】Ａｌ2Ｏ3多孔体に代表される従来のセラ
ミックス多孔体の粒子は球状に近い形状をしている。そ
のため、表面に気孔率の低い層を形成しても、表面層と
支持層の密着強度が充分でないために応力が負荷された
時に両層間で剥離が起きやすく結果として充分な強化効
果が発揮できない。[0006] Particles of a conventional ceramic porous body represented by a porous body of Al 2 O 3 have a shape close to a sphere. Therefore, even if a layer having a low porosity is formed on the surface, the adhesion between the surface layer and the support layer is not sufficient, so that separation is likely to occur between the two layers when stress is applied, and as a result, a sufficient reinforcing effect cannot be exhibited. .

【０００７】球状粒子からなる多孔体の細孔形状は同
様に球状に近い形状となるため、表面に堆積層を形成す
る際、支持層の細孔径とほぼ同じ粒径以上の粒子しか堆
積させることができない。なぜなら、細孔径以下の粒子
は支持層を透過してしまうからである。粒径の大きな粒
子は焼結しにくいために緻密化させにくく、結果として
表面層の気孔率を充分に低下させることができず充分な
高強度化ができない。Since the pore shape of the porous body composed of spherical particles is also similar to a spherical shape, when forming a deposition layer on the surface, it is necessary to deposit only particles having a diameter substantially equal to or larger than the pore diameter of the support layer. Can not. This is because particles having a diameter equal to or smaller than the pore diameter pass through the support layer. Particles having a large particle diameter are difficult to be sintered and thus are difficult to be densified. As a result, the porosity of the surface layer cannot be sufficiently reduced and sufficient strength cannot be obtained.

【０００８】[0008]

【発明が解決しようとする課題】本発明は、軽量で強度
が大きく、かつ、表面層が平滑で剥離し難い窒化ケイ素
複合材料とその製造方法を提供しようとするものであ
る。SUMMARY OF THE INVENTION An object of the present invention is to provide a silicon nitride composite material which is lightweight, has high strength, has a smooth surface layer and is difficult to peel off, 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、発明者らは鋭意探求の結果特開平７−５００４７０
号に記載のように支持層として三次元絡み合い構造を持
つ柱状窒化ケイ素粒子と酸化物系結合相からなる多孔体
を用いることにより、軽量で極めて強度が高く、低摩擦
特性を持つ窒化ケイ素系複合材料が得られることを見い
だした。Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have made intensive searches and have found a result of Japanese Patent Laid-Open No. 7-500470.
By using a porous body composed of columnar silicon nitride particles having a three-dimensional entangled structure and an oxide-based binder phase as a support layer as described in the above item, a silicon nitride composite with light weight, extremely high strength, and low friction characteristics We found that the material was obtained.

【００１０】すなわち、本発明の構成は特許請求の範囲
に記載のとおりの窒化ケイ素系複合材料とその製法であ
る。窒化ケイ素系複合材料の基本的な構成は、平均アス
ペクト比が３以上の柱状窒化ケイ素粒子と酸化物系結合
相からなる、気孔率３０％以上７０％以下、平均細孔径
が１２μｍ以下、３点曲げ強度が１００ＭＰａ以上の窒
化ケイ素多孔体（支持層）と、少なくともその一方の表
面部に形成された気孔率が２０％以下、厚さが１μｍ以
上のセラミックス、カラスまたは金属層（表面層）から
なる、多層構造を持つ窒化ケイ素系複合材料である。That is, the constitution of the present invention is a silicon nitride-based composite material and a method for producing the same as described in the claims. The basic structure of the silicon nitride-based composite material is composed of columnar silicon nitride particles having an average aspect ratio of 3 or more and an oxide-based binder phase, a porosity of 30% or more and 70% or less, and an average pore diameter of 12 μm or less. A silicon nitride porous body (support layer) having a bending strength of 100 MPa or more and a ceramic, crow or metal layer (surface layer) having a porosity formed on at least one surface of which is 20% or less and a thickness of 1 μm or more. Is a silicon nitride-based composite material having a multilayer structure.

【００１１】このような材料は、セラミックスまたは金
属の粉末を溶媒に分散させた懸濁液を、該三次元絡み合
い構造を持つ柱状窒化ケイ素粒子と酸化物系結合相から
なる窒化ケイ素多孔体で濾過して、該多孔体の少なくと
も一方の表面にセラミックスまたは金属の粉末のケーキ
層を形成し、これを高温で焼結させて該多孔体の一方の
表面あるいは両表面に気孔率の低いセラミックスまたは
金属の表面層を形成させて得られる。Such a material is obtained by filtering a suspension of a ceramic or metal powder dispersed in a solvent through a porous silicon nitride body comprising columnar silicon nitride particles having a three-dimensional entangled structure and an oxide-based binder phase. Forming a cake layer of ceramic or metal powder on at least one surface of the porous body, sintering the cake layer at a high temperature, and forming a ceramic or metal having low porosity on one or both surfaces of the porous body. Is obtained by forming a surface layer.

【００１２】すなわち、この窒化ケイ素系複合材料の基
本的な製造方法はセラミックス、ガラスまたは金属粉末
を溶媒に分散させた懸濁液を調整する工程と、平均アス
ペクト比が３以上の柱状窒化ケイ素粒子と酸化物系結合
相からなる気孔率３０％以上７０％以下の窒化ケイ素多
孔体で上記懸濁液を濾過して、該多孔体の少なくとも一
方の表面に該粉末のケーキ層を形成する工程と、該ケー
キ層を高温で溶融または焼結させて該多孔体の少なくと
も一方の表面に気孔率の低いセラミックス、ガラスまた
は金属の層を形成する工程を含む多層構造を持つ窒化ケ
イ素系複合材料の製造法である。That is, a basic method for producing the silicon nitride-based composite material includes a step of preparing a suspension in which ceramics, glass or metal powder is dispersed in a solvent, and a method of preparing columnar silicon nitride particles having an average aspect ratio of 3 or more. Forming a cake layer of the powder on at least one surface of the porous body by filtering the suspension with a silicon nitride porous body having a porosity of 30% or more and 70% or less comprising an oxide-based binder phase. Producing a silicon nitride-based composite material having a multilayer structure including a step of melting or sintering the cake layer at a high temperature to form a low-porosity ceramic, glass or metal layer on at least one surface of the porous body. Is the law.

【００１３】形成する表面の層の厚さは１μｍ以上必要
である。なぜなら支持層であるＳｉ3Ｎ4多孔体の表面粗
度がＲａで約１μｍであるため、それ未満ではケーキ層
が完全に多孔体を覆わず、表面層の気孔率を２０％以下
にできない。最大厚さは特に制限がないが、厚すぎると
多孔体の軽量性を生かせないため１ｍｍ以下が好まし
い。The thickness of the surface layer to be formed must be 1 μm or more. Because the surface roughness of the porous Si 3 N 4 material as the support layer is about 1 μm in Ra, if it is less than this, the cake layer does not completely cover the porous material and the porosity of the surface layer cannot be reduced to 20% or less. The maximum thickness is not particularly limited, but if it is too thick, the lightness of the porous body cannot be utilized, so that the thickness is preferably 1 mm or less.

【００１４】支持層の平均細孔径は１２μｍ以下とす
る。これを越えるとケーキ層を形成するために使用する
粉末の粒径が３μｍを越えてしまい、緻密化が起こりに
くく、表面層の気孔率を２０％以下にできない。The average pore size of the support layer is 12 μm or less. If it exceeds this, the particle size of the powder used for forming the cake layer exceeds 3 μm, so that it is difficult for the powder to be densified, and the porosity of the surface layer cannot be reduced to 20% or less.

【００１５】表面層の材質としては、金属、ガラス、セ
ラミックスが考えられる。窒化ケイ素系以外の表面層を
形成する場合には、その材質が緻密化しやすい条件を選
べばよい。例えば、金属Ａｌの場合、非酸化性雰囲気で
４８０〜５５０℃程度で焼成すればよい。例えば通常の
ホウケイ酸ガラスの場合、６００〜１４００℃程度であ
る。As the material of the surface layer, metal, glass and ceramics can be considered. In the case of forming a surface layer other than silicon nitride, conditions may be selected under which the material is easily densified. For example, in the case of metal Al, firing may be performed at about 480 to 550 ° C. in a non-oxidizing atmosphere. For example, in the case of ordinary borosilicate glass, the temperature is about 600 to 1400 ° C.

【００１６】表面層に高い機械的強度を付与して材料全
体を高強度化するためには窒化ケイ素が好ましい。窒化
ケイ素表面層を形成するには、窒化ケイ素粉末と適量の
焼結助剤の混合粉末をケーキ層にすればよい。焼結温度
は焼結助剤種によっても若干異なるが、通常は１５００
〜１８００℃程度でよい。このようにして表面層を形成
した多孔体の曲げ強度は、形成前の多孔体と比べて格段
に高くなる。表面層が窒化ケイ素の場合、ＪＩＳ１６０
１に規定された３点曲げ強度で１００ＭＰａ以上１００
ＭＰａ以下の範囲程度の値が得られる。Silicon nitride is preferred for imparting high mechanical strength to the surface layer to increase the strength of the entire material. In order to form a silicon nitride surface layer, a mixed powder of silicon nitride powder and an appropriate amount of a sintering aid may be used as a cake layer. The sintering temperature varies slightly depending on the type of sintering aid, but is usually 1500
About 1800 ° C. The bending strength of the porous body having the surface layer formed in this way is significantly higher than that of the porous body before the formation. When the surface layer is made of silicon nitride, JIS160
100 MPa or more and 100 at three-point bending strength specified in 1.
A value in the range of about MPa or less can be obtained.

【００１７】表面層に気密性を持たせることを目的とす
る場合、ガラス粉末のケーキ層を形成後、溶融させれば
完全に緻密なガラス層が得られる。この応用として高速
の流体と接触する航空機部品の表面処理がある。これを
以下に説明する。例えばこのような部品にはレドームと
呼ばれるドーム形状に加工したレーダー透過材料が用い
られる。レドーム材料として必要な特性は誘電率と誘電
損失が小さいことであり、その点でＳｉ3Ｎ4多孔体は有
望であるが、雨中で高速巡航する場合、水滴が多孔体に
侵入してレーダー透過特性を劣化させる場合がある。こ
の対策として例えば特開平８−１６４６８９号に記載の
ように多孔体表面にガラスを被覆する方法が取られる。
ガラス被覆法としては、ガラス粉末の分散液を塗布、焼
成したり、エチルシリケートのような金属アルコキシド
を塗布、焼成してガラス層を形成するなどがある。しか
し、これらの方法では多孔体表面に完全に緻密なガラス
層を形成することは困難である。When the surface layer is intended to be airtight, a completely dense glass layer can be obtained by forming a cake layer of glass powder and then fusing it. One application is surface treatment of aircraft parts that come into contact with high speed fluids. This will be described below. For example, a radar permeable material processed into a dome shape called a radome is used for such a component. The properties required as a radome material are low dielectric constant and dielectric loss. In that respect, porous Si 3 N 4 material is promising, but when cruising at high speed in rain, water droplets enter the porous material and pass through the radar. The characteristics may be degraded. As a countermeasure, for example, a method of coating the surface of a porous body with glass as described in JP-A-8-164689 is adopted.
Examples of the glass coating method include a method of applying and firing a dispersion liquid of glass powder, and an example of applying and firing a metal alkoxide such as ethyl silicate to form a glass layer. However, it is difficult to form a completely dense glass layer on the surface of the porous body by these methods.

【００１８】なぜなら、上記の方法では、ガラス粉末の
分散液や金属アルコキシドを塗布後、焼成する際、溶媒
の急激な乾燥によってガラス成分が急激に収縮し、それ
によってガラス膜にクラックやピンホールが入るためで
ある。基材が多孔体の場合、この現象は著しく、形成し
たガラス膜の気密性は低い。また、これらの方法では、
原料液中のガラス成分が少なく厚いガラス膜を形成でき
ないことも大きな要因である。原料液中のガラス成分を
多くすると、塗布時にムラができ表面に均一なガラス膜
を形成できない。 これに対し、本発明の方法を用いる
と、完全に緻密なガラス膜を均一な厚さで被覆できる。
例えば、ホウケイ酸ガラス粉末の懸濁液を調整し、これ
をドーム形状の多孔体の凸面から凹面に濾過させて、凸
面にケーキ層を形成後、これを溶融温度で加熱して溶融
させればよい。In the above method, when a glass powder dispersion or a metal alkoxide is applied and then fired, the glass component shrinks sharply due to rapid drying of the solvent, thereby causing cracks and pinholes in the glass film. To enter. This phenomenon is remarkable when the substrate is a porous body, and the formed glass film has low airtightness. Also, with these methods,
Another major factor is that a thick glass film cannot be formed due to a small amount of glass components in the raw material liquid. When the glass component in the raw material liquid is increased, unevenness is caused at the time of coating, and a uniform glass film cannot be formed on the surface. On the other hand, when the method of the present invention is used, a completely dense glass film can be coated with a uniform thickness.
For example, by preparing a suspension of borosilicate glass powder, filtering this from the convex surface of the dome-shaped porous body to the concave surface, forming a cake layer on the convex surface, and then heating and melting it at the melting temperature, Good.

【００１９】また、このようにして表面層を形成後、試
料表面を機械的に研磨することにより、その表面粗度Ｒ
ａを０．３０μｍ以下に小さくすることができる。気孔
率が２０％を越えると気孔による凹凸が大きくなるため
にＲａ値は０．３０μｍを越えてしまい、摩擦係数を低
下させる効果が小さくなる。After the surface layer is formed in this manner, the surface of the sample is mechanically polished to obtain a surface roughness R.
a can be reduced to 0.30 μm or less. If the porosity exceeds 20%, the Ra value exceeds 0.30 μm because the irregularities due to the pores increase, and the effect of lowering the friction coefficient decreases.

【００２０】表面層を金属にすると、強度が上る、摩擦
係数が低下する以外に、金属部材との接合性が向上する
という利点もある。セラミックスと金属をろうづけ接合
する場合、通常はセラミックス表面にメタライズ層を形
成して表面を金属化してなじみをよくした後、ろうづけ
するが、多孔体の場合はメタライズしても表面が金属化
しないのでろうづけしても接合強度が弱かった。本発明
を用いると、表面をメタライズしなくても直接ろうづけ
接合でき、高い接合強度が得られる。When the surface layer is made of metal, there is an advantage that, in addition to an increase in strength and a decrease in friction coefficient, the joining property with a metal member is improved. When brazing ceramic and metal, it is common to form a metallized layer on the ceramic surface and metallize the surface to improve familiarity, and then braze it. The bonding strength was low even when brazing was not performed. According to the present invention, brazing can be directly performed without metallizing the surface, and high bonding strength can be obtained.

【００２１】このようにして作製した多孔体が高強度特
性を持つ理由は以下のとおりである。The reason why the porous body thus produced has high strength characteristics is as follows.

【００２２】すなわち、該支持層は三次元的にお互いに
絡み合った柱状結晶からなる構造のため、表面層を形成
した場合、表面層との結合が極めて強く、支持層と表面
層の界面はいわゆる繊維強化複合材料のような構造にな
る。応力負荷時のエネルギーは柱状結晶を引き抜くため
に費される。この結合力のために表面層が剥離しにく
い。そのため、従来にはない高強度特性を発揮する。That is, since the support layer has a structure composed of columnar crystals intertwined with each other three-dimensionally, when the surface layer is formed, the bond with the surface layer is extremely strong, and the interface between the support layer and the surface layer is so-called. The structure becomes like a fiber reinforced composite material. The energy at the time of stress loading is used to pull out the columnar crystal. Due to this bonding force, the surface layer does not easily peel off. Therefore, it exhibits a high strength characteristic that has not been achieved in the past.

【００２３】これに対して従来のセラミックス多孔体の
細孔は球状に近い形状をしている。そのため、表面に気
孔率の低い層を形成しても、表面層と支持層の密着強度
が充分でないために応力が負荷された時に両層間で剥離
が起きやすく結果として充分な強度効果が発揮できな
い。On the other hand, the pores of the conventional ceramic porous body have a nearly spherical shape. Therefore, even if a layer having a low porosity is formed on the surface, the adhesion between the surface layer and the support layer is not sufficient, so that when a stress is applied, peeling easily occurs between the two layers, and as a result, a sufficient strength effect cannot be exhibited. .

【００２４】従って、支持層を構成する粒子の平均アス
ペクト比は３以上必要である。それ未満だと表面層との
密着強度が低く、表面層を形成しても強度向上効果が小
さい。また、摺動時に表面層が剥離して摩擦係数が大き
くなってしまう。Therefore, the particles constituting the support layer must have an average aspect ratio of 3 or more. If it is less than this, the adhesion strength to the surface layer is low, and even if the surface layer is formed, the strength improvement effect is small. In addition, the surface layer peels off during sliding and the friction coefficient increases.

【００２５】支持層の気孔率は３０％以上とする。それ
未満だと気孔率が低下しても支持層の強度がほとんど上
がらない。さらに柱状結晶の引き抜き効果が小さく表面
層を形成しても強度向上の効果があまりない。上限は７
０％である。それを越えると単位体積当たりの柱状結晶
の数が少なくなり表面層との結合力が低く表面層を形成
しても強度向上効果が小さい。The porosity of the support layer is 30% or more. If it is less than this, the strength of the support layer hardly increases even if the porosity decreases. Further, the effect of pulling out columnar crystals is small, and even if a surface layer is formed, there is not much effect of improving strength. Upper limit is 7
0%. If it exceeds this, the number of columnar crystals per unit volume is reduced, and the bonding strength with the surface layer is low, so that the strength improvement effect is small even if the surface layer is formed.

【００２６】[0026]

【作用】本発明の窒化ケイ素系複合材料の作用を要約す
ると支持層がランダムに配列した柱状粒子から構成され
るため、形成した表面層との密着強度が大きく、応力負
荷時に表面層が剥離することがない。したがって、多孔
体であるにも関わらず、極めて強度が大きい。更に、表
面層は気孔率が小さい構造であるので面粗度を小さくす
ることができる。The function of the silicon nitride composite material of the present invention can be summarized as follows. Since the support layer is composed of randomly arranged columnar particles, the adhesion strength to the formed surface layer is large, and the surface layer peels off when stress is applied. Nothing. Therefore, the strength is extremely high despite being a porous body. Furthermore, since the surface layer has a structure with a small porosity, the surface roughness can be reduced.

【００２７】[0027]

【実施例】以下、実施例および比較例によって本発明を
具体的に説明する。The present invention will be specifically described below with reference to examples and comparative examples.

【００２８】（１）平均粒径０．４μｍのα型窒化珪素
粉末に平均粒径０．０１５μｍのＹ2Ｏ3３粉末を添加し
た混合粉末を形成密度１．２〜１．８ｇ／ｃｍ3で成形
し、５気圧の窒素中、温度１８００℃で２ｈｒ焼成して
気孔率２５〜７２％、平均細孔径０．０７〜０．８４μ
ｍのＳｉ3Ｎ4多孔体を得た。(1) A mixed powder obtained by adding Y 2 O 3 3 powder having an average particle size of 0.015 μm to α-type silicon nitride powder having an average particle size of 0.4 μm was formed at a density of 1.2 to 1.8 g / cm 3. And baked in nitrogen at 5 atm at a temperature of 1800 ° C. for 2 hours, with a porosity of 25 to 72% and an average pore size of 0.07 to 0.84 μm.
m of porous Si 3 N 4 was obtained.

【００２９】比較例として同じα型窒化珪素粉末に平均
粒径０．０１５μｍのＹ2Ｏ3粉末を５ｗｔ％、平均粒系
０．０５μｍのＡｌ2Ｏ3粉末を３ｗｔ％添加した混合、
粉末を成形密度１．３／ｃｍ3で成形し、圧力５気圧の
窒素中、温度１７００℃で２ｈｒ焼成して気孔率５０
％、平均細孔径０．５μｍのＳｉ3Ｎ4多孔体を得た。As a comparative example, 5 wt% of Y 2 O 3 powder having an average particle size of 0.015 μm and 3 wt% of Al 2 O 3 powder having an average grain size of 0.05 μm were added to the same α-type silicon nitride powder.
The powder was molded at a molding density of 1.3 / cm 3 , and calcined in nitrogen at a pressure of 5 atm at a temperature of 1700 ° C. for 2 hours to give a porosity of 50/50.
%, And an Si 3 N 4 porous body having an average pore diameter of 0.5 μm was obtained.

【００３０】これらの多孔体（支持層）を９０℃の１０
％ＨＦ液に６ｈｒ浸漬して粒界相を溶出させて、結晶粒
子が分散する状態にした後、５００個の粒子について電
子顕微鏡により各粒子のアスペクト比（長さ／直径）を
測定し、平均アスペクト比を算出した。The porous body (support layer) was heated at 90 ° C. for 10 hours.
% HF solution for 6 hours to elute the grain boundary phase to make the crystal particles dispersed, measure the aspect ratio (length / diameter) of each of the 500 particles by an electron microscope, and average The aspect ratio was calculated.

【００３１】別途、平均粒径０．３μｍのα型窒化珪素
粉末に平均径０．５μｍのＡｌ2Ｏ3、Ｙ2Ｏ3、ＭｇＯ粉
末をそれぞれＳｉＮに対し２，５，１ｗｔ％添加した混
合粉末をエタノールに分散させた懸濁液（濃度は１５ｖ
ｏｌ％）を作製し、Ｓｉ3Ｎ4多孔体で濾過して、表面に
ケーキ層を厚さ４μｍ〜２ｍｍ形成した。これを窒素
中、温度１５００℃、圧力１気圧で２ｈｒ焼成して表面
層を形成したＳｉ3Ｎ4多孔体を作製した。Separately, 2,5,1 wt% of Al 2 O 3 , Y 2 O 3 , MgO powder having an average diameter of 0.5 μm is added to α-type silicon nitride powder having an average particle diameter of 0.3 μm to SiN, respectively. A suspension in which the powder is dispersed in ethanol (concentration is 15 v
ol%), and filtered through a porous Si 3 N 4 material to form a cake layer on the surface with a thickness of 4 μm to 2 mm. This was fired in nitrogen at a temperature of 1500 ° C. and a pressure of 1 atm for 2 hours to produce a Si 3 N 4 porous body having a surface layer formed thereon.

【００３２】これらの試料の表面層形成前後の３点曲げ
強度Ｒａを表面粗さ計により測定した。その後、Ｂａｌ
ｌ ｏｎ Ｄｉｓｋ方式により以下の条件で摩擦試験を
行い、摩擦係数を測定するとともに焼き付き状態を調べ
た。The three-point bending strengths Ra of these samples before and after the formation of the surface layer were measured by a surface roughness meter. Then Bal
A friction test was performed by the lon Disk method under the following conditions to measure the friction coefficient and to examine the seizure state.

【００３３】 潤 滑 油 ：エンジンオイル（ＳＨ１０Ｗ３０） 相手材（Ｂａｌｌ）：ＳＣＭ４１５（浸炭処理材） 速 度 ：３．２ｍ／ｓ 荷 重 ：１９．６Ｎ 摺動距離 ：１６０００００ｍ 摩擦係数測定とは別に、試料をタペットシムとして鋼製
カムシャフトと組み合わせて１５００ｃｃ排気量のガソ
リンエンジン車に搭載して１０モード燃費を測定した。
比較試料として、鏡面研磨した相対密度１００％の緻密
質Ｓｉ3Ｎ4タペットシム（強度１５００ＭＰａ、比重
３．２４）を用いた。Lubricating oil: engine oil (SH10W30) Counterpart material (Ball): SCM415 (carburized material) Speed: 3.2 m / s Load: 19.6 N Sliding distance: 1600000 m Apart from friction coefficient measurement, The sample was mounted on a gasoline engine vehicle with a displacement of 1500 cc in combination with a steel camshaft as a tappet shim, and 10-mode fuel consumption was measured.
As a comparative sample, a mirror-polished dense Si 3 N 4 tappet shim (strength 1500 MPa, specific gravity 3.24) having a relative density of 100% was used.

【００３４】結果を表１に示す。Table 1 shows the results.

【００３５】[0035]

【表１】 [Table 1]

【００３６】[0036]

【表２】 [Table 2]

【００３７】同表の結果より、アスペクト比が３以上の
Ｓｉ3Ｎ4多孔体を支持層とし、表面層を形成することに
より摩擦係数が低下して焼き付きが起こらず、またタペ
ットシムとして用いると燃費は大きく向上することが分
かった。From the results in the table, it can be seen that by forming a surface layer of a Si 3 N 4 porous material having an aspect ratio of 3 or more as a support layer, the friction coefficient is reduced and seizure does not occur. Was found to be greatly improved.

【００３８】（２）平均粒径２．０μｍのα型窒化珪素
粉末に平均粒径０．２５μｍのＹ2Ｏ3粉末を添加した混
合粉末を成形密度１．４〜１．６ｇ／ｃｍ3で成形し、
圧力５気圧の窒素中、温度１８５０℃で２〜１２ｈｒ焼
成して気孔率４０〜５０％、平均細孔径３．０〜１４μ
ｍのＳｉ3Ｎ4多孔体を得た。(2) A mixed powder obtained by adding Y 2 O 3 powder having an average particle diameter of 0.25 μm to α-type silicon nitride powder having an average particle diameter of 2.0 μm at a molding density of 1.4 to 1.6 g / cm 3 . Molded,
Baking in nitrogen at a pressure of 5 atm at a temperature of 1850 ° C. for 2 to 12 hours, a porosity of 40 to 50%, and an average pore diameter of 3.0 to 14 μm
m of porous Si 3 N 4 was obtained.

【００３９】比較として、平均粒径２．０μｍのＳｉＣ
粉末に平均粒径０．５μｍのＢ4Ｃ粉末を５ｗｔ％添加
した混合粉末を成形密度１．３ｇ／ｃｍ3で成形し、圧
力１気圧の窒素中、温度２１００℃で２ｈｒ焼成して気
孔率５０％、平均細孔径０．５μｍのＳｉ3Ｎ4多孔体を
得た。For comparison, SiC having an average particle size of 2.0 μm was used.
A mixed powder obtained by adding 5 wt% of B 4 C powder having an average particle size of 0.5 μm to the powder is molded at a molding density of 1.3 g / cm 3 , and is calcined in nitrogen at a pressure of 1 atm at a temperature of 2100 ° C. for 2 hours and a porosity. A 50% Si 3 N 4 porous body having an average pore diameter of 0.5 μm was obtained.

【００４０】これらの多孔体（支持層）を９０℃の１０
％ＨＦ液に６ｈｒ浸漬して粒界相を溶出させて、結晶粒
子が分散する状態にした後、５００個の粒子について電
子顕微鏡により各粒子のアスペクト比（長さ／直径）を
測定し、平均アスペクト比を算出した。These porous bodies (support layers) were heated at 90 ° C. for 10 hours.
% HF solution for 6 hours to elute the grain boundary phase to make the crystal particles dispersed, measure the aspect ratio (length / diameter) of each of the 500 particles by an electron microscope, and average The aspect ratio was calculated.

【００４１】別途、平均粒径３．０〜５．０μｍのα型
珪素粉末に平均粒径０．５μｍのＡｌ2Ｏ3粉末をＳｉ3
Ｎ4に対し０．２〜２．０ｗｔ％、Ｙ2Ｏ3粉末をＳｉ3Ｎ
4に対し５ｗｔ％添加した混合粉末をエタノールに分散
させた懸濁液（濃度は１５ｖｏｌ％）を作製し、Ｓｉ3
Ｎ4多孔体で濾過して、表面にケーキ層を厚さ４００μ
ｍ形成した。これを圧力４気圧の窒素中、温度１７００
℃で２ｈｒ焼成して厚さ２００〜３００μｍの表面層を
形成したＳｉ3Ｎ4多孔体を作製した。[0041] Separately, the α-type silicon powder having an average particle diameter of 3.0~5.0μm average particle diameter 0.5 [mu] m Al 2 O 3 powder Si 3
0.2～2.0Wt% to N 4, Y 2 O 3 powder Si 3 N
A suspension (concentration: 15 vol%) was prepared by dispersing a mixed powder in which 5 wt% was added to 4 in ethanol, and Si 3
Filter through a N 4 porous material to form a cake layer on the surface with a thickness of 400μ.
m was formed. This is placed in a nitrogen atmosphere at a pressure of 4 atm.
To prepare a Si 3 N 4 porous body to form a surface layer of 2hr calcined to thickness 200~300μm at ° C..

【００４２】これらの試料について、表面層形成前後の
３点曲げ強度（ＪＩＳ１６０１）測定、およびＳｉ3Ｎ4
多孔体（形状は直径３０ｍｍ、厚さ３ｍｍ）の表面を研
磨し、表面粗さ計により測定した。その後、Ｂａｌｌ
ｏｎ Ｄｉｓｋ方式により以下の条件で摩擦試験を行
い、摩擦係数を測定するとともに焼き付き状態を調べ
た。For these samples, three-point bending strength (JIS 1601) measurement before and after formation of the surface layer, and Si 3 N 4
The surface of the porous body (having a diameter of 30 mm and a thickness of 3 mm) was polished and measured with a surface roughness meter. Then, Ball
A friction test was performed by the on-disk method under the following conditions to measure the friction coefficient and to examine the seizure state.

【００４３】 潤 滑 油 ：エンジンオイル（ＳＨ１０Ｗ３０） 相手材（Ｂａｌｌ）：ＳＣＭ４１５（浸炭処理材） 速 度 ：３．２ｍ／ｓ 荷 重 ：１９．６Ｎ 摺動距離 ：１６０００００ｍ 摩擦係数測定とは別に、試料をタペットシムとして鋼製
カムシャフトと組み合わせて１５００ｃｃ排気量のガソ
リンエンジン車に搭載して１０モード燃費を測定した。
比較として、鏡面研磨した相対密度１００％の緻密質Ｓ
ｉ3Ｎ4タペットシム（強度１５００ＭＰa、比重３．２
４）を用いた。Lubricating oil: engine oil (SH10W30) Counterpart material (Ball): SCM415 (carburized material) Speed: 3.2 m / s Load: 19.6 N Sliding distance: 1600000 m Apart from friction coefficient measurement, The sample was mounted on a gasoline engine vehicle with a displacement of 1500 cc in combination with a steel camshaft as a tappet shim, and 10-mode fuel consumption was measured.
As a comparison, a mirror-polished dense S with a relative density of 100%
i 3 N 4 tappet shim (strength 1500 MPa, specific gravity 3.2
4) was used.

【００４４】結果を表２に示す。Table 2 shows the results.

【００４５】[0045]

【表３】 [Table 3]

【００４６】[0046]

【表４】 [Table 4]

【００４７】同表の結果より、アスペクト比が３以上の
Ｓｉ3Ｎ4多孔体を支持層とし、表面層を形成することに
より摩擦係数が低下して焼き付きが起こらず、またタペ
ットシムとして用いると燃費は大きく向上することが分
かった。From the results shown in the table, it was found that the porous layer of Si 3 N 4 having an aspect ratio of 3 or more was used as a support layer and the surface layer was formed to reduce the coefficient of friction to prevent seizure. Was found to be greatly improved.

【００４８】（３）平均粒径０．４μｍのα型窒化珪素
粉末に平均粒径０．０１５μｍのＹ2Ｏ3粉末を８ｗｔ％
添加した混合粉末を形成密度１．６ｇ／ｃｍ3で成形
し、５気圧の窒素中、温度１８００℃で２ｈｒ焼成して
気孔率５０％、平均細孔径０．５４μｍのＳｉ3Ｎ4多孔
体を得た。これを図１のドーム形状に機械加工した。(3) 8 wt% of Y 2 O 3 powder having an average particle size of 0.015 μm is added to α-type silicon nitride powder having an average particle size of 0.4 μm.
The added mixed powder was molded at a formation density of 1.6 g / cm 3 , and calcined in nitrogen at 5 atm at a temperature of 1800 ° C. for 2 hours to produce a porous Si 3 N 4 having a porosity of 50% and an average pore diameter of 0.54 μm. Obtained. This was machined into the dome shape of FIG.

【００４９】別途、７０ｗｔ％ＳｉＯ2−２２ｗｔ％−
８ｗｔ％Ｎａ2Ｏ系ガラスを作製、ボールミルにより粉
砕し、平均粒径０．９μｍの粉末を作製した。これらを
エチルアルコールに分散させて、濃度１０ｇ／ｌの懸濁
液を調整した。これを上記ドーム状Ｓｉ3Ｎ4多孔体外周
側の凸面から内周側凹面に濾過させて凸面にガラス粉末
のケーキ層を１０μｍ形成した。これらを温度１２００
℃、０．００１気圧の真空下で０．５ｈｒ加熱し、室温
まで急冷した。急冷後のガラス膜表面をＳＥＭ観察し
た。Separately, 70 wt% SiO 2 -22 wt%
An 8 wt% Na 2 O-based glass was prepared and pulverized by a ball mill to prepare a powder having an average particle size of 0.9 μm. These were dispersed in ethyl alcohol to prepare a suspension having a concentration of 10 g / l. This was filtered from the convex surface on the outer peripheral side of the dome-shaped porous Si 3 N 4 body to the concave surface on the inner peripheral side to form a 10 μm glass cake layer on the convex surface. These are heated to 1200
The mixture was heated at a temperature of 0.001 atm and under a vacuum of 0.001 atm for 0.5 hr and rapidly cooled to room temperature. The surface of the glass film after quenching was observed by SEM.

【００５０】比較例として、同じガラス粉末の懸濁液を
濃度１０ｇ／ｌ、１ｇ／ｌ、０．１ｇ／ｌの懸濁液を調
整した。これらの懸濁液にドーム状Ｓｉ3Ｎ4多孔体を１
０分浸漬して、引き上げ、温度１２００℃、１気圧の大
気中で０．５ｈｒ加熱し、室温まで急冷した。この工程
を複数回繰り返し行った後のガラス膜表面をＳＥＭ観察
した。As a comparative example, suspensions of the same glass powder having a concentration of 10 g / l, 1 g / l and 0.1 g / l were prepared. A dome-shaped porous Si 3 N 4 is added to these suspensions in one.
It was immersed for 0 minutes, pulled up, heated in an atmosphere of 1200 ° C. and 1 atm for 0.5 hr, and rapidly cooled to room temperature. After repeating this step a plurality of times, the surface of the glass film was observed by SEM.

【００５１】これらの試料を恒温槽に入れ、ガラス膜を
形成した面のみを５００℃、湿度８５％の条件で１ｈｒ
暴露した後、２５ＧＨｚの周波数で電波透過率を測定し
た。These samples were placed in a thermostat, and only the surface on which the glass film was formed was kept at 500 ° C. and 85% humidity for 1 hour.
After the exposure, the radio wave transmittance was measured at a frequency of 25 GHz.

【００５２】結果を表３に示す。Table 3 shows the results.

【００５３】[0053]

【表５】 [Table 5]

【００５４】[0054]

【表６】 [Table 6]

【００５５】同表の結果より、本法により表面ガラス層
を形成することにより、気密性が高くなり、電波透過率
は大きく向上することが分かった。また、浸析するのみ
で濾過していない引き上げ法のものは表面が緻密になら
ないため、耐湿試験により、試料内部に水分が浸透し、
このため電波透過率が本法に比べ顕著に低いことが分か
った。From the results shown in the table, it was found that by forming the surface glass layer by this method, the airtightness was improved and the radio wave transmittance was greatly improved. In addition, since the surface of the lifting method that is only immersed but not filtered does not become dense, moisture permeates into the sample by a moisture resistance test,
Therefore, it was found that the radio wave transmittance was significantly lower than that of the present method.

【００５６】（４）平均粒径０．４μｍのα型窒化珪素
粉末に平均粒径０．０１５μｍのＹ2Ｏ3粉末を８ｗｔ％
添加した混合粉末を形成密度１．６ｇ／ｃｍ3で成形
し、５気圧の窒素中、温度１８００℃で２ｈｒ焼成して
気孔率５０％、平均細孔径０．５４μｍのＳｉ3Ｎ4多孔
体を得た。(4) 8 wt% of Y 2 O 3 powder having an average particle size of 0.015 μm is added to α-type silicon nitride powder having an average particle size of 0.4 μm.
The added mixed powder was molded at a formation density of 1.6 g / cm 3 , and calcined in nitrogen at 5 atm at a temperature of 1800 ° C. for 2 hours to produce a porous Si 3 N 4 having a porosity of 50% and an average pore diameter of 0.54 μm. Obtained.

【００５７】比較例して、平均粒径２．０μｍのＳｉＣ
粉末に平均粒径０．５μｍのＢ4Ｃ粉末を５ｗｔ％添加
した混合粉末を成形密度１．３ｇ／ｃｍ3で成形し、圧
力１気圧の窒素中、温度２１００℃で２ｈｒ焼成して気
孔率５０％、平均細孔径０．５μｍのＳｉ3Ｎ4多孔体を
得た。As a comparative example, SiC having an average particle size of 2.0 μm
A mixed powder obtained by adding 5 wt% of B 4 C powder having an average particle size of 0.5 μm to the powder is molded at a molding density of 1.3 g / cm 3 , and is calcined in nitrogen at a pressure of 1 atm at a temperature of 2100 ° C. for 2 hours and a porosity. A 50% Si 3 N 4 porous body having an average pore diameter of 0.5 μm was obtained.

【００５８】これらの多孔体（支持層）を９０℃の１０
％ＨＦ液に６ｈｒ浸漬して粒界相を溶出させて、結晶粒
子が分散する状態にした後、５００個の粒子について電
子顕微鏡により各粒子のアスペクト比（長さ／直径）を
測定し、平均アスペクト比を算出した。These porous bodies (supporting layers) were heated at 90 ° C. for 10 hours.
% HF solution for 6 hours to elute the grain boundary phase to make the crystal particles dispersed, measure the aspect ratio (length / diameter) of each of the 500 particles by an electron microscope, and average The aspect ratio was calculated.

【００５９】別途、平均粒径３．０μｍのＡｌ粉をエタ
ノールに分散させた懸濁液（濃度は１５ｖｏｌ％）を作
製し、上記多孔体で濾過して、表面にケーキ層を厚さ４
００μｍ形成した。これを圧力４気圧の窒素中、温度１
７００℃で２ｈｒ焼成して厚さ２００μｍの表面層を形
成したＳｉ3Ｎ4多孔体を作製した。Separately, a suspension (concentration: 15 vol%) in which Al powder having an average particle diameter of 3.0 μm was dispersed in ethanol was prepared, and the suspension was filtered through the porous material to form a cake layer having a thickness of 4 μm on the surface.
A thickness of 00 μm was formed. This is placed in a nitrogen atmosphere at a pressure of 4 atm.
Firing at 700 ° C. for 2 hours produced a Si 3 N 4 porous body having a surface layer having a thickness of 200 μm.

【００６０】これらの試料について、表面層形成前後の
３点曲げ強度（ＪＩＳ１６０１）測定、およびＳｉ3Ｎ4
多孔体（形状は直径３０ｍｍ、厚さ３ｍｍ)の表面を研
磨し、表面粗度Ｒａを表面粗さ計により測定した。その
後、Ｂａｌｌ ｏｎ Ｄｉｓｋ方式により以下の条件で
摩擦試験を行い、摩擦係数を測定するとともに焼き付き
状態を調べた。For these samples, three-point bending strength (JIS 1601) measurement before and after formation of the surface layer, and Si 3 N 4
The surface of the porous body (shape was 30 mm in diameter and 3 mm in thickness) was polished, and the surface roughness Ra was measured by a surface roughness meter. Thereafter, a friction test was performed by the ball-on-disk method under the following conditions to measure the friction coefficient and to examine the seizure state.

【００６１】 潤 滑 油 ：エンジンオイル（ＳＨ１０Ｗ３０） 相手材（Ｂａｌｌ）：ＳＣＭ４１５（浸炭処理材） 速 度 ：３．２ｍ／ｓ 荷 重 ：１９．６Ｎ 摺動距離 ：１６０００００ｍ 摩擦係数測定とは別に、試料をタペットシムとして鋼製
カムシャフトと組み合わせて１５００ｃｃ排気量のガソ
リンエンジン車に搭載して１０モード燃費を測定した。
比較として、鏡面研磨した相対密度１００％の緻密質Ｓ
ｉ3Ｎ4タペットシム（強度１５００ＭＰａ、比重３．２
４）を用いた。Lubricating oil: Engine oil (SH10W30) Counterpart material (Ball): SCM415 (carburized material) Speed: 3.2 m / s Load: 19.6 N Sliding distance: 1600000 m Apart from friction coefficient measurement, The sample was mounted on a gasoline engine vehicle with a displacement of 1500 cc in combination with a steel camshaft as a tappet shim, and 10-mode fuel consumption was measured.
As a comparison, a mirror-polished dense S with a relative density of 100%
i 3 N 4 tappet shim (strength 1500 MPa, specific gravity 3.2
4) was used.

【００６２】結果を表４に示す。Table 4 shows the results.

【００６３】[0063]

【表７】 [Table 7]

【００６４】[0064]

【表８】 [Table 8]

【００６５】同表の結果より、アスペクト比が３以上の
Ｓｉ3Ｎ4多孔体を支持層とし、表面層を形成することに
より摩擦係数が低下して焼き付きが起こらず、またタペ
ットシムとして用いると燃費は大きく向上することが分
かった。From the results in the table, it can be seen that by forming a porous layer of Si 3 N 4 having an aspect ratio of 3 or more as a support layer and forming a surface layer, the friction coefficient is reduced so that seizure does not occur. Was found to be greatly improved.

【００６６】[0066]

【発明の効果】以上説明したように、本発明の窒化ケイ
素材料は、軽量で強度が高い材料であるため、例えば低
摩擦が要求される摺動部材例えば内燃機関の部材である
タペットシムとして用いると燃費向上の効果が高い。As described above, the silicon nitride material of the present invention is a lightweight and high-strength material, and is used, for example, as a sliding member requiring low friction, for example, a tappet shim as a member of an internal combustion engine. High fuel efficiency.

【００６７】一方、支持層表面にガラス層を形成するこ
とによって気密性が高くなり、電波透過率も優れている
ので例えばレドーム材料として効果が著しい。On the other hand, by forming a glass layer on the surface of the support layer, the airtightness is improved and the radio wave transmittance is excellent, so that the effect is remarkable, for example, as a radome material.

【図面の簡単な説明】[Brief description of the drawings]

【図１】本願発明の一例である実施例１２〜１７で形成
したドームの斜視図である。FIG. 1 is a perspective view of a dome formed in Examples 12 to 17, which are an example of the present invention.

Claims (8)

【特許請求の範囲】[Claims] 【請求項１】 平均アスペクト比が３以上の柱状窒化ケ
イ素粒子と酸化物系結合相からなる、気孔率３０％以上
７０％以下、平均細孔径が１２μｍ以下、３点曲げ強度
が１００ＭＰａ以上の窒化ケイ素多孔体（支持層）と、
少なくともその一方の表面部に形成された気孔率が２０
％以下、厚さが１μｍ以上のセラミックス、ガラスまた
は金属層（表面層）からなることを特徴とする、多層構
造を持つ窒化ケイ素系複合材料。1. A nitride comprising columnar silicon nitride particles having an average aspect ratio of 3 or more and an oxide-based binder phase and having a porosity of 30% or more and 70% or less, an average pore diameter of 12 μm or less, and a three-point bending strength of 100 MPa or more. A silicon porous body (support layer);
The porosity formed on at least one of the surface portions is 20
% Or less, comprising a ceramic, glass or metal layer (surface layer) having a thickness of 1 μm or more, a silicon nitride-based composite material having a multilayer structure. 【請求項２】 ３点曲げ強度が、１００ＭＰａ以上１０
００ＭＰａ以下であることを特徴とする請求項１の多層
構造を持つ窒化ケイ素系複合材料。2. A three-point bending strength of 100 MPa or more and 10
The silicon nitride-based composite material having a multilayer structure according to claim 1, wherein the pressure is not more than 00 MPa. 【請求項３】 表面部の面粗度（Ｒａ）が０．３μｍ以
下であることを特徴とする請求項１または２記載の多層
構造を持つ窒化ケイ素系複合材料。3. The silicon nitride-based composite material having a multilayer structure according to claim 1, wherein the surface has a surface roughness (Ra) of 0.3 μm or less. 【請求項４】 請求項１記載の自動車動弁系に用いるタ
ペットシム。4. A tappet shim for use in an automobile valve train according to claim 1. 【請求項５】 請求項１記載のドーム。5. The dome according to claim 1, wherein: 【請求項６】 請求項１記載の窒化ケイ素系複合材料の
製法であって、セラミックス、ガラスまたは金属の粉末
を溶媒に分散させた懸濁液を調整する工程と、平均アス
ペクト比が３以上の柱状窒化ケイ素粒子と酸化物系結合
相からなる気孔率３０％以上７０％以下の窒化ケイ素多
孔体で上記懸濁液を濾過して、該多孔体の少なくとも一
方の表面に該粉末のケーキ層を形成する工程と、該ケー
キ層を高温で溶融または焼結させて該多孔体の少なくと
も一方の表面に気孔率の低いセラミックス、ガラスまた
は金属の層を形成する工程を含むことを特徴とする多層
構造を持つ窒化ケイ素系複合材料の製造法。6. The method for producing a silicon nitride-based composite material according to claim 1, wherein a step of preparing a suspension in which ceramic, glass, or metal powder is dispersed in a solvent, and wherein the average aspect ratio is 3 or more. The suspension is filtered through a porous silicon nitride having a porosity of 30% or more and 70% or less composed of columnar silicon nitride particles and an oxide-based binder phase, and a powder cake layer is formed on at least one surface of the porous body. A multi-layer structure comprising a step of forming and a step of melting or sintering the cake layer at a high temperature to form a ceramic, glass or metal layer having a low porosity on at least one surface of the porous body. Of producing a silicon nitride-based composite material having 【請求項７】 ケーキ層を形成する粉末が平均粒径３．
０μｍ以下の窒化ケイ素と酸化物系焼結助剤からなるこ
とを特徴とする請求項６記載の多層構造を持つ窒化ケイ
素系複合材料の製造法。7. The powder forming the cake layer has an average particle size of 3.
7. The method for producing a silicon nitride-based composite material having a multilayer structure according to claim 6, comprising a silicon nitride having a thickness of 0 μm or less and an oxide-based sintering aid. 【請求項８】 ケーキ層を形成する粉末がＳｉＯ2系ガ
ラスからなることを特徴とする請求項６記載の多層構造
を持つ窒化ケイ素系複合材料の製造法。8. The method for producing a silicon nitride-based composite material having a multilayer structure according to claim 6, wherein the powder forming the cake layer is made of SiO 2 -based glass.
JP21088297A 1997-08-05 1997-08-05 Silicon nitride composite material having multilayer structure and its production Pending JPH1160355A (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002226285A (en) * 2000-11-29 2002-08-14 Kyocera Corp Lightweight ceramic member and method for manufacturing the same
JP2005055329A (en) * 2003-08-06 2005-03-03 Toyota Motor Corp Molding placed in beam course of radar device, and its manufacturing method
EP1443030A3 (en) * 2003-01-21 2006-06-21 Sumitomo Electric Industries, Ltd. Porous Si3N4 and producing method thereof
CN109560381A (en) * 2018-11-28 2019-04-02 北京遥感设备研究所 A kind of ceramic radome improves the pre- Enhancement Method of intensity
CN114292130A (en) * 2021-12-21 2022-04-08 山东工业陶瓷研究设计院有限公司 Ceramic part and processing method thereof

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002226285A (en) * 2000-11-29 2002-08-14 Kyocera Corp Lightweight ceramic member and method for manufacturing the same
JP4671501B2 (en) * 2000-11-29 2011-04-20 京セラ株式会社 Lightweight ceramic member and manufacturing method thereof
EP1443030A3 (en) * 2003-01-21 2006-06-21 Sumitomo Electric Industries, Ltd. Porous Si3N4 and producing method thereof
US7153484B2 (en) 2003-01-21 2006-12-26 Sumitomo Electric Industries, Ltd. Porous Si3N4 producing method
JP2005055329A (en) * 2003-08-06 2005-03-03 Toyota Motor Corp Molding placed in beam course of radar device, and its manufacturing method
US7824782B2 (en) 2003-08-06 2010-11-02 Toyota Jidosha Kabushiki Kaisha Molded article located in the beam path of radar device, and method of manufacturing the same
CN109560381A (en) * 2018-11-28 2019-04-02 北京遥感设备研究所 A kind of ceramic radome improves the pre- Enhancement Method of intensity
CN114292130A (en) * 2021-12-21 2022-04-08 山东工业陶瓷研究设计院有限公司 Ceramic part and processing method thereof
CN114292130B (en) * 2021-12-21 2022-11-15 山东工业陶瓷研究设计院有限公司 Ceramic part and processing method thereof

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