JP4095286B2

JP4095286B2 - Multi-core composite structure

Info

Publication number: JP4095286B2
Application number: JP2001358397A
Authority: JP
Inventors: 謙二野田
Original assignee: Kyocera Corp
Current assignee: Kyocera Corp
Priority date: 2001-11-22
Filing date: 2001-11-22
Publication date: 2008-06-04
Anticipated expiration: 2021-11-22
Also published as: JP2003160388A

Description

【０００１】
【発明の属する技術分野】
本発明は、ダイヤモンド焼結体からなる芯材の外周を、焼結合金からなる表皮部材にて被覆してなる複合構造体に関する。
【０００２】
【従来の技術】
従来より、繊維等長尺状の芯材の外周を他の部材にて被覆することにより、構造体の硬度や強度に加えて靭性を改善する技術が研究されており、例えば、特開平１１−１３９８８４号公報では、セラミックスからなる芯材（線状セラミックス）の外周に第２相成分の被覆層を吹き付け、これを一方向に収束して圧縮成形して焼成した複合セラミック焼結体が記載されており、構造体の破壊抵抗が増大することが開示されている。
【０００３】
一方、ダイヤモンドは、高い硬度を有するという特性を生かして、ダイヤモンド粒子間を鉄族金属にて結合したダイヤモンド焼結体が、切削工具または掘削用の工具や耐摩耗部材として利用されている。
【０００４】
【発明が解決しようとする課題】
しかしながら、上記従来のダイヤモンド焼結体では、硬度は高いものの靭性および耐衝撃性が低く、例えば切削工具または掘削工具等として使用すると耐欠損性が劣るという問題があった。
【０００５】
また、上述した複合構造体として芯材にダイヤモンド焼結体を用い表皮部材に超硬合金（ＷＣ）等の周期律表４ａ、５ａ、６ａ族金属を主成分とする焼結合金にて被覆した複合構造体が考えられるが、構造体の高強度と高靭性を両立させる組成については検討されておらず、さらに、単純に上記ダイヤモンド焼結体と焼結金属を組み合わせただけでは、芯部のダイヤモンドと表皮部材の主成分である硬質粒子との熱膨張係数差が大きいために、芯部と表皮部材との界面に部分的にクラックや剥離が発生する場合があり、靭性の低下につながるという問題があった。
【０００６】
本発明は上記課題を解決するためになされたもので、その目的は、高硬度と高靭性とを両立できる複合構造体を提供することにある。
【０００７】
【課題を解決するための手段】
本発明者らは上記課題について検討した結果、芯材であるダイヤモンド焼結体中の鉄族金属の含有比率を表皮部材である焼結合金中の鉄族金属の含有比率よりも多くすることによって、両者間の熱膨張係数差を小さくでき、高硬度と高靭性を両立できる複合構造体が得られることを知見した。
【０００８】
すなわち、本発明の複合構造体は、ダイヤモンド粒子間を鉄族金属にて結合したダイヤモンド焼結体からなる中実で平均直径Ｄ _１が２〜２００μｍの長尺状の芯材の外周を、周期律表４ａ、５ａ、６ａ族金属の群から選ばれる少なくとも１種以上の金属元素（Ｍ）の炭化物、窒化物および炭窒化物の群から選ばれる少なくとも１種以上の硬質粒子を鉄族金属にて結合した焼結合金からなる表皮部材にて被覆してなる複合構造体を複数本収束したマルチフィラメント構造の多芯複合構造体であって、前記芯材の平均直径Ｄ _１と前記表皮部材の平均厚みＤ _２との比Ｄ _２／Ｄ _１が０．０１〜０．５であり、前記芯材中の鉄族金属の含有比率が前記表皮部材中の鉄族金属の含有比率よりも多いことを特徴とする多芯複合構造体である。
【０００９】
【発明の実施の形態】
本発明の多芯複合構造体を構成する複合構造体について、その一実施例である図１の概略図およびその要部拡大図である図２を基に説明する。
【００１０】
図１によれば、複合構造体１は、ダイヤモンド粒子２、２間を鉄族金属３にて結合したダイヤモンド焼結体４からなる長尺状の芯材（４）の外周を、周期律表４ａ、５ａ、６ａ族金属の群から選ばれる少なくとも１種以上の金属元素（Ｍ）の炭化物、窒化物および炭窒化物のうちの１種以上のからなる硬質粒子６を鉄族金属７にて結合した焼結合金８からなる表皮部材（８）にて被覆してなる。
【００１１】
本発明によれば、芯材（ダイヤモンド焼結体）４中の鉄族金属３の量が表皮部材（焼結合金）８中の鉄族金属７の量よりも多いことが大きな特徴であり、これによって、両者間の熱膨張係数差を小さくでき、高硬度と高靭性を両立できる複合構造体となる。ここで、本発明における鉄族金属の含有比率とは、構造体１断面のエネルギー分散型Ｘ線マイクロアナリシスにおける鉄族金属のピーク強度の合計であり、特に、ダイヤモンド焼結体４中の鉄族金属３の含有比率Ｍｄと、焼結合金８中の鉄族金属７の含有比率Ｍｃとの比（Ｍｄ／Ｍｃ）が１．２以上、特に１．５〜１００であることが望ましい。
【００１２】
また、本発明によれば、ダイヤモンド焼結体４中の鉄族金属３の含有比率と焼結合金８中の鉄族金属７の含有比率とを所定量に抑制して複合構造体の破壊靱性値を向上させるために、ダイヤモンド粒子２の平均粒径ｄ_１が３．５μｍ以下、特に０．０１〜２．５μｍであることが望ましく、さらに、ダイヤモンド粒子２の平均粒径ｄ１と、硬質粒子６の平均粒径ｄ_２との比（ｄ_１／ｄ_２）が０．００１〜１．０、特に０．０１〜０．９、さらに０．０５〜０．８であることが望ましい。これによって、ダイヤモンド焼結体４の毛細管力を焼結合金８のそれよりも大きくして、結合材である鉄族金属３の含浸力に差をつけることができることから、焼成時に溶融した鉄族金属を十分に浸透させることによって容易に鉄族金属の分布をダイヤモンド焼結体側にシフトさせることができる。このようにダイモンド粒子の平均粒径ｄ_１を３．５μｍ以下とするか、ダイヤモンド粒子の平均粒径ｄ_１と硬質粒子の平均粒径ｄ_２との比（ｄ_１／ｄ_２）を０．００１〜１．０とすると、複合構造体の破壊靱性値を２０ＭＰａ√ｍ以上とすることができる。
【００１３】
なお、ｄ_１／ｄ_２が１．０より大きい場合であっても、鉄族金属の添加量をダイヤモンド焼結体側が多くなる所定の比率に調整し、かつ焼成温度を例えば１４００℃未満とするか、または芯材と表皮部材間に鉄族金属の拡散を阻害する中間層を配して焼結時の鉄族金属の拡散を抑制することにより、芯材中の鉄族金属の含有比率を焼結合金のそれよりも多くすることが可能である。
【００１４】
さらには、芯材４と被皮部材８との界面における密着性を高めるとともに、局所的な応力集中を抑制するために、図２の鉄族金属の含有比率の分布に示すように、鉄族金属３の含有比率が芯材４から表皮部材８に向かって次第に、換言すれば連続的または段階的に減少することが望ましい。
【００１５】
また、例えば、芯材４の平均直径は２〜２００μｍ、表皮部材８の平均厚みは０．１〜１００μｍからなるが、硬度５０ＧＰａ以上、靭性１８ＭＰａ√ｍ以上とするためには、芯材４の平均直径Ｄ_１と表皮部材８の平均厚みＤ_２との比Ｄ_２／Ｄ_１が０．０１〜０．５、特に０．０２〜０．２であることが重要である。
【００１６】
さらに、図１では芯材４が１本、すなわち単体の周囲に表皮部材８が被覆された構造について示したが、本発明は図３に示すように、図１の構造体１を例えば４本以上の複数本収束したマルチフィラメント構造である。
【００１７】
次に、本発明の多芯複合構造体を構成する複合構造体を製造する方法について図４の模式図をもとに説明する。
【００１８】
まず、平均粒径０．０１〜３．５μｍのダイヤモンド粉末を５０重量％以上と平均粒径１０μｍ以下の鉄族金属粉末を５０重量％以下を混合し、これにパラフィンワックス、ポリスチレン、ポリエチレン、エチレン−エチルアクリレ−ト、エチレン−ビニルアセテート、ポリブチルメタクリレート、ポリエチレングリコール、ジブチルフタレート等の有機バインダを添加して混錬して、プレス成形、押出成形または鋳込成形等の成形方法により円柱形状の芯材用成形体４’を成形する（工程（ａ））。
【００１９】
一方、平均粒径０．０２〜１０μｍの硬質粒子または硬質粒子形成成分を７０〜９５重量％と平均粒径１０μｍ以下の鉄族金属粉末を５〜３０重量％との割合で混合し、これに前述のバインダ等を添加して混錬して、プレス成形、押出成形または鋳込成形等の成形方法により半割円筒形状の２本の表皮部材用成形体８’を作製し、該表皮部材用成形体８’を前記芯材用成形体４’の外周を覆うように配置した複合成形体を作製する（工程（ａ））。
【００２０】
そして、上記複合成形体を共押出成形することにより芯材４’の周囲に表皮部材８’が被覆された細い径に伸延された複合成形体１’を作製する（工程（ｂ））。
また、マルチフィラメント構造の本発明の多芯複合構造体を作製するには、上記共押出しした長尺状の成形体を複数本収束して再度共押出し成形すれば良い（工程（ｃ））。
【００２１】
さらに、上記伸延された長尺状の成形体を所望により円柱や三角柱、四角柱、六角柱等の多角形に成形することもできる。また、長尺状の成形体を整列させてシートとなし、該シートの長尺状の成形体同士が平行、直交または４５°等の所定の角度をなすように積層させた積層体とすることもできる。また、公知のラピッドプロトダイビング法等の成形方法によって任意の形状に成形することも可能である。さらには、上記整列したシートまたは該シートを断面方向にスライスした複合構造体シートを従来の超硬合金等の硬質合金焼結体（塊状体）の表面に貼り合わせ、または接合することも可能である。
【００２２】
その後、前記成形体を脱バインダ処理した後、超高圧焼成することにより本発明の多芯複合構造体を作製することができる。本発明によれば、芯材４と表皮部材８との鉄族金属の含有比率を所定の範囲内に制御するために、前記焼成条件として、圧力４ＧＰａ以上、温度１３００℃以上で５分〜１時間とすることが望ましい。特に、ダイヤモンド粒子２の平均粒径ｄ_１と、硬質粒子６の平均粒径ｄ_２との比（ｄ_１／ｄ_２）が０．０１〜１．０である場合には１４００℃〜１８００℃であることが望ましく、１．０より大きい場合、１４００℃未満であることが望ましい。
【００２３】
【実施例】
（実施例）
表１に示す平均粒径のダイヤモンド粒子８５〜１００重量％に対し、平均粒径２μｍのコバルト粉末を０〜１５重量％添加し、これにバインダと滑剤を添加して混錬した後、プレス成形により直径２０ｍｍの芯材用成形体を作製した。
【００２４】
一方、表１に示す硬質粒子粉末８０〜９５重量％に対し、平均粒径２μｍのコバルト粉末を５〜１５重量％添加し、これにバインダ、滑剤を添加、混錬した後、プレス成形により肉厚１ｍｍで半割円筒状の表皮部材用成形体を２本作製し、前記芯材用成形体の周囲に被覆した複合成形体を作製した。
【００２５】
そして、前記複合成形体を共押出した伸延された成形体を作製した後、該伸延された成形体１００本を収束して再度共押出し成形し、マルチフィラメントタイプの成形体を作製した。その後、該成形体に対して脱バインダ処理を行い、続いて超高圧装置内にセットして圧力５ＧＰａにて、表１の温度条件で焼成して多芯複合構造体を作製した。
【００２６】
得られた多芯複合構造体に対して、ヴィッカース硬度（ＪＩＳＲ１６０１に準じる）およびＩＦ法にて試料の靭性を測定した。さらに、試料の研磨断面について波長分散型Ｘ線マイクロアナリシス分析（ＥＰＭＡ）を行い、鉄族金属のピーク強度の合計量を芯材と表皮部材のそれぞれの平均値について大小を比較した。ＥＰＭＡの条件は、加速電圧１５ｋＶ、プローブ電流３×１０−７Ａ、スポットサイズ２μｍである。その結果を表１に示す。
【００２７】
【表１】

【００２８】
表１の結果より、芯材と表皮部材における鉄族金属の含有比率が同じで、Ｃｏ総量の少ない試料Ｎｏ．１、２では、ダイヤモンド粒子径の大きいＮｏ．１は、硬度は５８ＧＰａと高いものの破壊靭性が１２ＭＰａ√ｍと低く、ダイヤモンド粒子径の小さいＮｏ．２は、圧痕の剥離により測定不能であった。また、芯材と表皮部材における鉄族金属の含有量が同じで、Ｃｏ総量の多い試料Ｎｏ．３では、破壊靭性が１６ＭＰａ√ｍと高いものの硬度は４０ＧＰａと低いものであった。
【００２９】
これに対して、本発明に従い、芯材の鉄族金属の含有比率が表皮部材の鉄族金属の含有比率よりも多い試料Ｎｏ．４〜１１では、いずれも硬度５０ＧＰａ以上、靭性１８ＭＰａ√ｍ以上の優れた特性を有するものであった。
【００３０】
なお、試料Ｎｏ．４〜１１の構造体における寸法を顕微鏡で測定したところ、平均で芯材の直径１４０〜１６０μｍ、表皮部材の平均厚み８〜１２μｍであった。なお、焼結体中のＣｏ量は、Ｃｏの移動後の結果として、不等号で記載してある。
【００３１】
【発明の効果】
以上詳述したとおり、本発明の複合構造体によれば、芯材であるダイヤモンド焼結体中の鉄族金属の含有比率を表皮部材である焼結合金中のそれよりも多くすることによって、両者間の熱膨張係数差を小さくでき、高硬度と高靭性を両立できる多芯複合構造体となる。
【図面の簡単な説明】
【図１】本発明の多芯複合構造体を構成する複合構造体の一例を示す概略図である。
【図２】図１の複合構造体の要部拡大図である。
【図３】本発明の多芯複合構造体の一例を示す概略斜視図である。
【図４】本発明の多芯複合構造体の製造方法を説明するための概念図である。
【符号の説明】
１複合構造体
２ダイヤモンド粒子
３鉄族金属
４芯材（ダイヤモンド焼結体）
６硬質粒子
７鉄族金属
８表皮部材（焼結合金）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a composite structure formed by coating the outer periphery of a core material made of a diamond sintered body with a skin member made of a sintered alloy.
[0002]
[Prior art]
Conventionally, a technique for improving toughness in addition to hardness and strength of a structure by coating the outer periphery of a long core material such as a fiber with another member has been studied. No. 139884 describes a composite ceramic sintered body in which a coating layer of a second phase component is sprayed on the outer periphery of a core material (linear ceramic) made of ceramics, and this is converged in one direction, compression molded, and fired. It is disclosed that the fracture resistance of the structure is increased.
[0003]
On the other hand, diamond has been used as a cutting tool, a tool for excavation, or a wear-resistant member by utilizing a characteristic that diamond has high hardness, and a diamond sintered body in which diamond particles are bonded with an iron group metal.
[0004]
[Problems to be solved by the invention]
However, the conventional diamond sintered body has high hardness but low toughness and impact resistance. For example, when used as a cutting tool or a drilling tool, there is a problem that the fracture resistance is inferior.
[0005]
In addition, a diamond sintered body is used as the core material as the composite structure described above, and the skin member is coated with a sintered alloy mainly composed of a periodic table 4a, 5a, 6a metal such as cemented carbide (WC). A composite structure is conceivable, but a composition that achieves both high strength and high toughness of the structure has not been studied. Furthermore, simply combining the above-mentioned diamond sintered body and sintered metal, Because the thermal expansion coefficient difference between diamond and the hard particles that are the main component of the skin member is large, cracks and peeling may occur partially at the interface between the core and the skin member, leading to reduced toughness. There was a problem.
[0006]
The present invention has been made to solve the above problems, and an object of the present invention is to provide a composite structure that can achieve both high hardness and high toughness.
[0007]
[Means for Solving the Problems]
As a result of examining the above problems, the present inventors have made the content ratio of the iron group metal in the diamond sintered body as the core material larger than the content ratio of the iron group metal in the sintered alloy as the skin member. It was found that a composite structure capable of reducing the difference in thermal expansion coefficient between the two and achieving both high hardness and high toughness can be obtained.
[0008]
That is, the composite structure of the present invention has a periodic outer periphery of a long core material having a solid average diameter D1 of ₂ to 200 μm made of a diamond sintered body in which diamond particles are bonded with an iron group metal. At least one hard particle selected from the group of carbides, nitrides, and carbonitrides of at least one metal element (M) selected from the group of groups 4a, 5a, and 6a is used as the iron group metal. the composite structure formed by coating with skin member made of sintered alloy bonded to a plurality of convergence Te a multi-core composite structure of the multi-filament structure, the average diameter D ₁ and the skin member of the core material The ratio D ₂ / D ₁ with respect to the average thickness D ₂ is 0.01 to 0.5, and the content ratio of the iron group metal in the core material is larger than the content ratio of the iron group metal in the skin member. Is a multi-core composite structure characterized by
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The composite structure constituting the multicore composite structure of the present invention will be described with reference to the schematic diagram of FIG. 1 as an example and FIG.
[0010]
According to FIG. 1, the composite structure 1 includes a periodic table of the outer periphery of a long core material (4) composed of a diamond sintered body 4 in which the diamond particles 2 and 2 are bonded by an iron group metal 3. The hard particles 6 composed of one or more of carbides, nitrides and carbonitrides of at least one metal element (M) selected from the group of 4a, 5a, and 6a metals are used as the iron group metal 7. It is covered with a skin member (8) made of a bonded sintered alloy 8.
[0011]
According to the present invention, the main feature is that the amount of the iron group metal 3 in the core material (diamond sintered body) 4 is larger than the amount of the iron group metal 7 in the skin member (sintered alloy) 8. As a result, the difference in thermal expansion coefficient between them can be reduced, and a composite structure can be obtained that can achieve both high hardness and high toughness. Here, the content ratio of the iron group metal in the present invention is the total peak intensity of the iron group metal in the energy dispersive X-ray microanalysis of the cross section of the structure 1, and in particular, the iron group in the diamond sintered body 4 The ratio (Md / Mc) of the content ratio Md of the metal 3 and the content ratio Mc of the iron group metal 7 in the sintered alloy 8 is preferably 1.2 or more, particularly 1.5 to 100.
[0012]
Further, according to the present invention, fracture toughness of the diamond sintered body iron group of 4 and the content ratio of the metal 3 and the content of iron group metals 7 in the sintered alloy 8 is suppressed to a predetermined amount composite structure In order to improve the value, it is desirable that the average particle diameter d ₁ of the diamond particles 2 is 3.5 μm or less, particularly 0.01 to 2.5 μm. Furthermore, the average particle diameter d1 of the diamond particles 2 and the hard particles The ratio (d ₁ / d ₂ ) of 6 to the average particle diameter d ₂ is preferably 0.001 to 1.0, particularly 0.01 to 0.9, and more preferably 0.05 to 0.8. Thus, the capillary force of the diamond sintered body 4 is made larger than that of the sintered alloy 8, since it is possible to differentiate the impregnation force in the iron group metal 3 is a bond material, iron group melted during firing By sufficiently permeating the metal, the distribution of the iron group metal can be easily shifted to the diamond sintered body side. Thus if the average particle size _{d 1} of Dimond particles to 3.5μm or less, the ratio of the average particle size _{d 2} of an average particle diameter _{d 1} and the hard particles of diamond particles _(d 1 / _{d 2)} 0. If it is set to 001 to 1.0, the fracture toughness value of the composite structure can be set to 20 MPa√m or more.
[0013]
Even when d ₁ / d ₂ is greater than 1.0, the amount of iron group metal added is adjusted to a predetermined ratio that increases on the diamond sintered body side, and the firing temperature is, for example, less than 1400 ° C. Or by arranging an intermediate layer that inhibits the diffusion of iron group metal between the core material and the skin member to suppress the diffusion of iron group metal during sintering , the content ratio of the iron group metal in the core material can be reduced. It can be more than that of the sintered alloy.
[0014]
Furthermore, to increase the adhesion at the interface between the core 4 and Hikawa member 8, in order to suppress the local stress concentration, as shown in the distribution of the content of the iron group metals in FIG. 2, the iron group It is desirable that the content ratio of the metal 3 gradually decreases from the core material 4 toward the skin member 8, in other words, continuously or stepwise.
[0015]
Further, for example, the average diameter of the core material 4 is 2 to 200 μm, and the average thickness of the skin member 8 is 0 . 1 to 100 μm, but in order to achieve a hardness of 50 GPa or more and a toughness of 18 MPa√m or more, the ratio D ₂ / D ₁ between the average diameter D ₁ of the core material 4 and the average thickness D ₂ of the skin member 8 is 0. It is important that it is 0.01-0.5, especially 0.02-0.2.
[0016]
Further, FIG. 1 shows a structure in which one core member 4 is formed, that is, a structure in which a skin member 8 is covered around a single body . However, as shown in FIG. Ru multi-filament structure der in which a plurality of the convergence of more.
[0017]
Next, a method for producing a composite structure constituting the multicore composite structure of the present invention will be described with reference to the schematic view of FIG.
[0018]
First, 50% by weight or more of diamond powder having an average particle size of 0.01 to 3.5 μm and 50% by weight or less of iron group metal powder having an average particle size of 10 μm or less are mixed, and this is mixed with paraffin wax, polystyrene, polyethylene, ethylene. -An organic binder such as ethyl acrylate, ethylene-vinyl acetate, polybutyl methacrylate, polyethylene glycol, and dibutyl phthalate is added and kneaded, and then a cylindrical core is formed by a molding method such as press molding, extrusion molding, or casting molding. The material molded body 4 ′ is molded (step (a)).
[0019]
On the other hand, 70 to 95% by weight of hard particles having an average particle size of 0.02 to 10 μm or a hard particle forming component and an iron group metal powder having an average particle size of 10 μm or less are mixed in a ratio of 5 to 30% by weight. The above-mentioned binder and the like are added and kneaded to produce two half-cylindrical shaped member 8 'for the skin member by a molding method such as press molding, extrusion molding or cast molding, and for the skin member A composite molded body in which the molded body 8 ′ is arranged so as to cover the outer periphery of the core body molded body 4 ′ is produced (step (a)).
[0020]
Then, the composite molded body 1 ′ is produced by coextrusion molding of the composite molded body 1 and extended to a thin diameter in which the skin member 8 ′ is coated around the core material 4 ′ (step (b)).
In order to produce the multifilamentary composite structure of the present invention having a multifilament structure, a plurality of the coextruded long shaped articles may be converged and coextruded again (step (c)).
[0021]
Furthermore, the elongated elongated shaped body can be formed into a polygon such as a cylinder, a triangular prism, a quadrangular prism, or a hexagonal prism as desired. In addition, the long shaped bodies are aligned to form a sheet, and the long shaped bodies of the sheet are laminated such that the long shaped bodies are parallel, orthogonal, or at a predetermined angle such as 45 °. You can also. Moreover, it is also possible to shape | mold into arbitrary shapes by shaping | molding methods, such as a well-known rapid proto diving method. Furthermore, the above-described aligned sheet or a composite structure sheet obtained by slicing the sheet in the cross-sectional direction can be bonded to or bonded to the surface of a conventional hard alloy sintered body (lumped body) such as cemented carbide. is there.
[0022]
Thereafter, after the binder is treated to remove the binder, the multi-core composite structure of the present invention can be produced by firing at a high pressure. According to the present invention, in order to control the content ratio of the iron group metal between the core material 4 and the skin member 8 within a predetermined range, the firing condition is 5 minutes to 1 at a pressure of 4 GPa or more and a temperature of 1300 ° C. or more. Time is desirable. In particular, the average particle diameter _{d 1} of the diamond particles 2, 1400 ° C. if the ratio between the average particle size _{d 2} of the hard particles 6 _(d 1 / _{d 2)} is 0.01 to 1.0 to 1800 ° C. When it is larger than 1.0, it is desirable that the temperature is lower than 1400 ° C.
[0023]
【Example】
(Example)
0-15 wt% of cobalt powder having an average particle size of 2 μm is added to 85-100 wt% of diamond particles having an average particle size shown in Table 1, and a binder and a lubricant are added thereto and kneaded, followed by press molding. Thus, a core material molded body having a diameter of 20 mm was produced.
[0024]
On the other hand, 5 to 15% by weight of cobalt powder having an average particle diameter of 2 μm is added to 80 to 95% by weight of the hard particle powder shown in Table 1, and a binder and a lubricant are added to the kneaded material. Two half-cylindrical skin member molded bodies having a thickness of 1 mm were prepared, and a composite molded body coated around the core material molded body was produced.
[0025]
And after producing the extended molded object which coextruded the said composite molded object, 100 said extended molded objects were converged and coextruded again, and the multifilament type molded object was produced. Thereafter, the molded body was subjected to a binder removal treatment, and subsequently set in an ultrahigh pressure apparatus and fired at a pressure of 5 GPa under the temperature conditions shown in Table 1 to produce a multicore composite structure.
[0026]
With respect to the obtained multi-core composite structure, the toughness of the sample was measured by Vickers hardness (according to JISR1601) and IF method. Furthermore, wavelength dispersive X-ray microanalysis analysis (EPMA) was performed on the polished cross section of the sample, and the total amount of the peak intensity of the iron group metal was compared with the average value of each of the core material and the skin member. The EPMA conditions are an acceleration voltage of 15 kV, a probe current of 3 × 10 −7 A, and a spot size of 2 μm. The results are shown in Table 1.
[0027]
[Table 1]

[0028]
From the results shown in Table 1, sample Nos. 1 and 2 having the same iron group metal content ratio in the core material and the skin member and a small total amount of Co. In Nos. 1 and 2, no. No. 1 has a hardness as high as 58 GPa but a fracture toughness as low as 12 MPa√m and a diamond particle size of no. 2 could not be measured due to peeling of the indentation. In addition, the iron group metal content in the core material and the skin member is the same, and the sample No. In No. 3, although the fracture toughness was as high as 16 MPa√m, the hardness was as low as 40 GPa.
[0029]
In contrast, in accordance with the present invention, the content ratio of the iron group metals of the core material is higher than the content ratio of the iron group metals of the skin member Sample No. 4 to 11 , all had excellent properties of hardness 50 GPa or more and toughness 18 MPa√m or more.
[0030]
Sample No. When the dimensions of structures 4 to 11 were measured with a microscope, the average diameter of the core material was 140 to 160 μm, and the average thickness of the skin member was 8 to 12 μm. The amount of Co in the sintered body is indicated by an inequality sign as a result after the movement of Co.
[0031]
【The invention's effect】
As detailed above, according to the composite structure of the present invention, by increasing the content ratio of the iron group metal in the diamond sintered body as the core material than in the sintered alloy as the skin member, The difference in thermal expansion coefficient between them can be reduced, and a multi-core composite structure that can achieve both high hardness and high toughness can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an example of a composite structure constituting a multicore composite structure of the present invention.
FIG. 2 is an enlarged view of a main part of the composite structure of FIG.
FIG. 3 is a schematic perspective view showing an example of the multi-core composite structure of the present invention.
FIG. 4 is a conceptual diagram for explaining a method for producing a multicore composite structure according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Composite structure 2 Diamond particle 3 Iron group metal 4 Core material (diamond sintered compact)
6 Hard particles 7 Iron group metal 8 Skin member (sintered alloy)

Claims

The outer circumference of a solid core material made of a diamond sintered body in which diamond particles are bonded with an iron group metal and having an average diameter D1 of ₂ to 200 μm is made of the periodic table 4a, 5a, and 6a group metal. A skin member comprising a sintered alloy in which at least one hard particle selected from the group of carbides, nitrides and carbonitrides of at least one metal element (M) selected from the group is bonded with an iron group metal a multi-core composite structure multifilament structure composite structures were plurality of convergence formed by coating at an average of the mean diameter D ₁ and the skin member of the core thickness D ₂ and the ratio D ₂ / D ₁ is 0.01 to 0.5, multi-core composite structure content of the iron group metals in the core material, characterized in that more than the content ratio of the iron group metals of the skin member in.

2. The multi-core composite structure according to claim 1, wherein an average particle diameter d ₁ of the diamond particles is 3.5 μm or less.

Wherein the average particle diameter _{d 1} of the diamond particles, the claim 1 or 2 the ratio of the average particle size _{d 2} of the hard particles _(d 1 / _{d 2)} is characterized in that 0.001 to 1.0 The multicore composite structure described.

The multi-core composite structure according to any one of claims 1 to 3, wherein a content ratio of the iron group metal gradually decreases from the core material toward the skin member.