JP4126449B2

JP4126449B2 - Multi-core composite structure

Info

Publication number: JP4126449B2
Application number: JP2002008820A
Authority: JP
Inventors: 謙二野田
Original assignee: Kyocera Corp
Current assignee: Kyocera Corp
Priority date: 2002-01-17
Filing date: 2002-01-17
Publication date: 2008-07-30
Anticipated expiration: 2022-01-17
Also published as: JP2003213359A

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で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で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、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、高い硬度を有するというダイヤモンドの特性を生かして、ダイヤモンド粒子間を鉄族金属で結合したダイヤモンド焼結体は、切削工具または掘削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、例えば切削工具や掘削工具として使用すると耐欠損性が低下す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で被覆した複合構造体が考えられるが、特に高硬度化のために構造体中の結合金属量が少ない場合には結合金属の濃度分布が生じて局所的な特性ばらつきが発生し、特に破壊靭性Ｋ_ICのばらつきが大きくなる場合があった。
【０００６】
また、ダイヤモンド焼結体を用いた複合構造体では、切削工具や掘削工具などに用いる場合、ワイヤー放電加工により切刃に合わせた形状にカットするのが一般的であるが、構造体の硬度を高めるために導電性である鉄族金属量を少なめに抑えると、鉄族金属が不均一に分布しやすく、結合相である鉄族金属の欠乏した部分がワイヤーの突発的な切断や出力上昇によるチッピングの発生などの原因となり、加工性が著しく低下していた。
【０００７】
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、かつ高靭性を維持しつつ、破壊靭性のばらつきを低減し、さらに加工性を向上できる複合構造体を提供することにある。
【０００８】
【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、構造体中の結合材成分である鉄族金属量を所定量以下に低減するとともに、ダイヤモンド焼結体中の鉄族金属量と焼結合金中のそれとを同じ量とした構成のダイヤモンド焼結体を芯材とし焼結合金を表皮部材とした複合構造体とすることによって、構造体中に局所的に靭性が極端に低下する領域が発生することなく、構造体の破壊靭性Ｋ_ICのばらつきを低減でき、さらに加工性が向上することを知見した。
【０００９】
すなわち、本発明の多芯複合構造体は、ダイヤモンド粒子間を鉄族金属で結合したダイヤモンド焼結体からなる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種以上の金属元素の炭化物、窒化物および炭窒化物のうちの１種以上の硬質粒子を鉄族金属で結合した焼結合金からなる表皮部材で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、前記複合構造体中の前記鉄族金属の含有量が全体として３０重量％以下であるとともに、前記芯材中の鉄族金属の含有割合Ｍ_ｄと前記表皮部材中の鉄族金属の含有割合Ｍ_ｃとの比（Ｍ_ｄ／Ｍ_ｃ）が０．８〜１．２であることを特徴とするものである。
【００１０】
ここで、前記ダイヤモンド粒子の平均粒径ｄ₁が３．５μｍ以下であること、前記ダイヤモンド粒子の平均粒径ｄ₁と、前記硬質粒子の平均粒径ｄ₂との比（ｄ₁／ｄ₂）が０．８〜１．２であること、前記芯材の平均直径Ｄ₁と前記表皮部材の平均厚みＤ₂との比（Ｄ₂／Ｄ₁）が０．０１〜０．５であることが望ましい。
【００１１】
【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、その一実施形態を示す図１の概略断面図およびその要部拡大図である図２を基に説明する。
【００１２】
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で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種以上の金属元素の炭化物、窒化物および炭窒化物のうちの１種以上の硬質粒子６を鉄族金属７で結合した焼結合金８の表皮部材（８）で被覆してなる。
【００１３】
本発明によれば、複合構造体１中の鉄族金属３、７の含有量が全体として３０重量％以下、特に１５重量％以下、さらには２〜１０重量％であり、全体として硬度の高いものであるが、芯材（ダイヤモンド焼結体）４中の鉄族金属３の含有割合Ｍ_ｄと表皮部材（焼結合金）８中の鉄族金属７の含有割合Ｍ_ｃとの比（Ｍ_ｄ／Ｍ_ｃ）が０．８〜１．２であること、すなわち焼結体全体の鉄族金属３、７の分布が均一となることが大きな特徴である。これによって、鉄族金属３、７の偏在による構造体中の破壊靭性Ｋ_ＩＣのばらつきが低減され、耐欠損性のばらつきが低減される。さらに、鉄族金属３、７の著しく少ない領域が消失し、全体的に連続した電気伝導性を示し、ワイヤー放電加工による加工性が向上する。
【００１４】
ここで、本発明における鉄族金属量とは、構造体１断面の波長分散型Ｘ線マイクロアナリシスにおける鉄族金属３、７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の含有割合Ｍ_ｄと焼結合金８中の鉄族金属７の含有割合Ｍ_ｃとの比（Ｍ_ｄ／Ｍ_ｃ）が０．９〜１．１であること、特に、０．９５〜１．０５であることが望ましい。
【００１５】
また、本発明によれば、構造体１の強度を向上させるために、ダイヤモンド粒子２の平均粒径ｄ₁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ｄ₂との比（ｄ₁／ｄ₂）が０．９〜１．２、特に０．９５〜１．１であることが望ましい。このとき、特に１４００℃以上の高温で複合構造体１を焼成すれば、焼結合金８とダイヤモンド焼結体４の毛細管力を均一にして一部溶融した結合材である鉄族金属３、７のダイヤモンド焼結体４と焼結合金８との含浸力を均一とすることができる結果、鉄族金属３、７の分布を構造体中全体で所定の範囲内とすることができる。
【００１６】
また、上記方法以外にも、鉄族金属３、７の分布状態を最適化するためには、原料中に芯材４中のダイヤモンド粒子２より鉄族金属３との濡れ性がよい黒鉛を適量添加せしめ、または表皮部材８中の硬質粒子６より濡れ性のよい炭素を適量添加せしめることにより、芯材４および表皮部材８中の硬質粒子６に対する溶融時の鉄族金属３、７の濡れ性を制御して鉄族金属３、７の分布を所定の範囲内にすることができる。また、芯材４中に黒鉛を添加する方法としては、黒鉛粒子を添加する以外に、ダイヤモンド粒子２表面を黒鉛化する方法も適応可能である。一方、表皮部材８中に炭素を添加するには、カーボンブラックなどの炭素源を添加する方法や、炭化物原料中の炭素量を調整するなどの方法がある。
【００１７】
さらに、構造体１中の鉄族金属３、７の含有割合を制御する方法としては、（芯材４用原料中の鉄族金属３量／表皮部材８用原料中の鉄族金属７量）（ただし、バインダ等の焼成によって揮発する成分は除く。）が０．８〜１．２となるように調整し、特に１４００℃未満の低温で焼成するか、または、芯材４と表皮部材８との間に鉄族金属３、７の拡散を防止するＴｉ等を主体とする拡散防止層を介層することによっても鉄族金属３、７の分布状態を制御することが可能である。
【００１８】
また、例えば、芯材４の平均直径は５００μｍ以下、特に２〜２００μｍ、さらに、表皮部材８の平均厚みは５００μｍ以下、特に２〜２００μｍからなるが、高硬度を達成するためには、芯材４の平均直径Ｄ₁と表皮部材８の平均厚みＤ₂との比Ｄ₂／Ｄ₁が０．０１〜０．５であることが望ましい。
【００１９】
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が被覆された場合について示したが、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からなる。
【００２０】
次に、本発明の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。
【００２１】
まず、平均粒径０．０１〜３．５μｍのダイヤモンド粉末を５０〜９８重量％と平均粒径１０μｍ以下の鉄族金属粉末を２〜５０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４'に成形する（工程（ａ）参照）。
【００２２】
一方、平均粒径０．０１〜１０μｍ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、この表皮部材用成形体８'を上記芯材用成形体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）参照）。
【００２３】
そして、上記複合成形体４'、８'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）参照）。また、マルチフィラメント構造の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１'を複数本収束して再度共押出し成形すればよい（工程（ｃ）参照）。
【００２４】
さらに、上記伸延された長尺状の成形体１０'を所望により円柱、三角柱、四角柱に成形する。また、上記長尺状の成形体１０'を整列させてシートとし、このシートの長尺状の成形体１０'同士が平行、直行または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、さらに、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この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。
【００２５】
そして、上記成形体１０'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３、７量を所定の範囲内に制御するために、上記焼成条件として、超高圧装置等を用いて圧力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ｄ₁と硬質粒子６の平均粒径ｄ₂との比（ｄ₁／ｄ₂）が０．８〜１．２である場合には、焼成温度は１４００℃〜１８００℃であることが望ましく、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ｄ₂との比（ｄ₁／ｄ₂）が上記範囲以外である場合には焼成温度が１４００℃未満であるのが望ましい。
【００２６】
【実施例】
（実施例）
表１に示す平均粒径および添加量のダイヤモンド粒子に対し、平均粒径２μｍのコバルト粉末を表１に示す割合で添加し、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１８ｍｍの芯材用成形体を作製した。
【００２７】
一方、表１に示す平均粒径および添加量の硬質粒子粉末に対し、平均粒径２μｍのコバルト粉末を表１に示す割合で添加し、これにバインダと滑剤を添加して混錬した後、プレス成形により肉厚１ｍｍで半割円筒状の表皮部材用成形体を２本作製し、上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。
【００２８】
そして、上記複合成形体を共押出して伸延された成形体を作製した後、この伸延された成形体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、この成形体に対して脱バインダ処理を行い、続いて試料を超高圧装置内にセットして圧力５ＧＰａで、表１の温度条件で焼成して複合構造体を作製した。
【００２９】
得られた複合構造体に対して、ビッカース硬度（ＪＩＳＲ１６０１に準じる）を測定した。さらに、試料の研磨断面の５箇所について波長分散型Ｘ線マイクロアナリシス分析を行い、鉄族金属（Ｃｏ）のピーク強度を芯材と表皮部材の部分についてそれぞれの平均値（Ｍ_d、Ｍ_c）を見積もり、Ｍ_d／Ｍ_cを算出した。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。また、上記複合構造体用成形体を作製し、その断面方向に厚さ３ｍｍにスライスしたシートを超硬合金と貼り合わせて上記同様の条件で超高圧焼結し、得られた試料をワイヤー放電加工機を用いて１０ｍｍ×１０ｍｍの正方形に切り出した。加工は、ワイヤーを切断しないように送り速度を調節し、その時に加工に要した時間をもとに加工性を比較した。また、加工後の試料の稜線を観察し、そのチッピングの有無を確認した。その結果を表１に示す。
【００３０】
【表１】

【００３１】
試料Ｎｏ．１〜８の複合構造体を有する工具では、５０ＧＰａ以上の高硬度を維持しつつ、加工時間が３分以下と優れた放電加工性能を示し、また、その加工稜線はチッピングすることもなく、優れた靭性をもつことが確認された。一方、本発明範囲外の試料Ｎｏ．９では、鉄族金属の含有量が多いため、非常に低い硬度となった。試料Ｎｏ．１０〜１２では、放電加工に２倍以上の時間を要し、加工性能が非常に悪く、また、その加工稜線には、多くのチッピングが観察され、破壊靭性にばらつきがあることが確認された。
【００３２】
【発明の効果】
以上詳述したとおり、本発明の多芯複合構造体によれば、ダイヤモンド粒子間を鉄族金属で結合したダイヤモンド焼結体からなる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種以上の金属元素の炭化物、窒化物および炭窒化物のうちの１種以上の硬質粒子を鉄族金属で結合した焼結合金からなる表皮部材で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、上記複合構造体中の上記鉄族金属の含有量が全体として３０重量％以下であるとともに、上記芯材中の鉄族金属の含有割合Ｍ_ｄと上記表皮部材中の鉄族金属の含有割合Ｍ_ｃとの比（Ｍ_ｄ／Ｍ_ｃ）が０．８〜１．２としたことから、芯材であるダイヤモンド焼結体中の鉄族金属量と表皮部材である焼結合金中の鉄族金属量を均一になり、複合構造体中の靭性および電気導電性が均一となって、高硬度を維持しつつ、加工性能の優れた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断面図である。
【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断面図である。
【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. Gazette 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 ceramics) 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, a diamond sintered body in which diamond particles are bonded with an iron group metal by utilizing the characteristics of diamond having high hardness is used as a cutting tool, a drilling tool, or a wear-resistant member.
[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 an excavating tool, there is a problem that the fracture resistance is lowered.
[0005]
Further, as the composite structure described above, a composite in which a diamond sintered body is used as a core material and a skin member is coated with a sintered alloy mainly composed of a periodic table 4a, 5a, 6a metal such as cemented carbide (WC). Structures are conceivable, but especially when the amount of bonded metal in the structure is small due to high hardness, the concentration distribution of the bonded metal is generated, resulting in local variation in characteristics, especially variation in fracture toughness K _IC May become larger.
[0006]
Moreover, in composite structures using diamond sintered bodies, when used for cutting tools, drilling tools, etc., it is common to cut them into a shape that matches the cutting edge by wire electric discharge machining. If the amount of iron group metal that is electrically conductive is suppressed to a small level, the iron group metal is likely to be unevenly distributed, and the portion lacking the iron group metal that is the binder phase is caused by sudden cutting of the wire or increased output. This caused chipping and the workability was significantly reduced.
[0007]
The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a composite structure capable of reducing variation in fracture toughness and further improving workability while maintaining high hardness and high toughness. There is.
[0008]
[Means for Solving the Problems]
As a result of studying the above problems, the present inventors have reduced the amount of iron group metal, which is a binder component in the structure, to a predetermined amount or less, and the amount of iron group metal in the diamond sintered body and the sintered alloy. By creating a composite structure with a diamond sintered body with the same amount as the core material and a sintered alloy as the skin member, there will be a region where the toughness is extremely lowered locally in the structure. It was also found that the variation in fracture toughness K _IC of the structure can be reduced and the workability is further improved.
[0009]
That is, in the multi-core composite structure of the present invention, the outer periphery of a long core material composed of a diamond sintered body in which diamond particles are bonded with an iron group metal is formed on a group of periodic table 4a, 5a, and 6a group metals. at least one kind of carbide metal elements, nitrides and complex structure in which one or more hard particles become coated with skin member made of sintered alloy bonded with iron group metals of the carbonitride selected from A multifilament structure having a multifilament structure in which a plurality of the iron group metals in the composite structure is 30% by weight or less as a whole, and the iron group metals in the core material The ratio (M _d / M _c ) of the content ratio M _d of the iron group metal and the content ratio M _c of the iron group metal in the skin member is 0.8 to 1.2.
[0010]
Here, the average particle diameter d ₁ of the diamond particles is 3.5 μm or less, and the ratio (d ₁ / d ₂ ) between the average particle diameter d ₁ of the diamond particles and the average particle diameter d ₂ of the hard particles. ) Is 0.8 to 1.2, and the ratio (D ₂ / D ₁ ) between the average diameter D _{1 of the} core material and the average thickness D ₂ of the skin member is 0.01 to 0.5. It is desirable.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The composite structure constituting the multi-core composite structure of the present invention will be described based on the schematic cross-sectional view of FIG. 1 showing one embodiment thereof and FIG.
[0012]
According to FIG. 1, the composite structure 1 has an outer periphery of a long core material (4) composed of a diamond sintered body 4 in which diamond particles 2 and 2 are bonded with an iron group metal 3. A sintered alloy 8 in which one or more hard particles 6 of carbide, nitride, and carbonitride of at least one metal element selected from the group of 5a and 6a group metals are bonded with an iron group metal 7. Covered with a skin member (8).
[0013]
According to the present invention, the content of the iron group metals 3 and 7 in the composite structure 1 is 30% by weight or less, particularly 15% by weight or less, more preferably 2 to 10% by weight, and the overall hardness is high. while those, the core material (diamond sintered body) the ratio between the proportion M _c of the iron group metals 7 of the iron group content M _d and the skin member of metal 3 (sintered alloy) 8 in 4 (M _d / M _c ) is 0.8 to 1.2, that is, the distribution of the iron group metals 3 and 7 in the entire sintered body is uniform. Thereby, the variation in fracture toughness K _{IC in} the structure due to the uneven distribution of the iron group metals 3 and 7 is reduced, and the variation in fracture resistance is reduced. Furthermore, the region where the iron group metals 3 and 7 are remarkably small disappears, shows continuous electric conductivity as a whole, and improves the workability by wire electric discharge machining.
[0014]
Here, the iron group metal amount in the present invention is the sum of the peak intensities of the iron group metals 3 and 7 in the wavelength dispersive X-ray microanalysis of the cross section of the structure 1, and in particular, iron in the diamond sintered body 4. the ratio between the proportion M _c of the iron group metal 7 in the content M _d and sintered alloy 8 families metal 3 _(M d / _{M c)} is from 0.9 to 1.1, in particular, 0. It is desirable that it is 95-1.05.
[0015]
In addition, according to the present invention, in order to improve the strength of the structure 1, 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, it the average particle diameter d ₁ of the diamond particles 2, the ratio of the average particle size d ₂ of the hard particles 6 (d ₁ / d ₂₎ is 0.9 to 1.2, in particular 0.95 to 1.1 Is desirable. At this time, in particular, if the composite structure 1 is fired at a high temperature of 1400 ° C. or higher, the iron group metals 3 and 7 which are binders in which the capillary forces of the sintered alloy 8 and the diamond sintered body 4 are made uniform and partially melted. As a result of the uniform impregnation force between the diamond sintered body 4 and the sintered alloy 8, the distribution of the iron group metals 3 and 7 can be within a predetermined range throughout the structure.
[0016]
In addition to the above method, in order to optimize the distribution state of the iron group metals 3 and 7, an appropriate amount of graphite having better wettability with the iron group metal 3 than the diamond particles 2 in the core material 4 is contained in the raw material. By adding or adding an appropriate amount of carbon having better wettability than the hard particles 6 in the skin member 8, the wettability of the iron group metals 3 and 7 when melted to the core material 4 and the hard particles 6 in the skin member 8. To control the distribution of the iron group metals 3 and 7 within a predetermined range. Moreover, as a method for adding graphite to the core material 4, in addition to adding graphite particles, a method of graphitizing the surface of the diamond particles 2 is also applicable. On the other hand, to add carbon to the skin member 8, there are a method of adding a carbon source such as carbon black, and a method of adjusting the amount of carbon in the carbide raw material.
[0017]
Furthermore, as a method of controlling the content ratio of the iron group metals 3 and 7 in the structure 1 (3 amount of iron group metal in the raw material for the core material 4/7 amount of iron group metal in the raw material for the skin member 8) (However, the component which volatilizes by baking, such as a binder, is excluded.) Is adjusted to be 0.8 to 1.2, and is particularly fired at a low temperature of less than 1400 ° C., or the core material 4 and the skin member 8 It is also possible to control the distribution state of the iron group metals 3 and 7 by interposing an anti-diffusion layer mainly composed of Ti or the like that prevents the diffusion of the iron group metals 3 and 7 therebetween.
[0018]
For example, the average diameter of the core material 4 is 500 μm or less, particularly 2 to 200 μm, and the average thickness of the skin member 8 is 500 μm or less, particularly 2 to 200 μm. It is desirable that the ratio D ₂ / D ₁ of the average diameter D _{1 of} 4 and the average thickness D ₂ of the skin member 8 is 0.01 to 0.5.
[0019]
Furthermore, one core 4 in FIG. 1, that is shown for the case where the skin member 8 is coated on the periphery of a single, the present invention is, as shown in FIG. 3, for example 4 structure 1 of FIG. 1 It consists of a multifilament structure that converges more than one.
[0020]
Next, a method for producing the composite structure of the present invention will be described based on the schematic view of FIG.
[0021]
First, 50 to 98% by weight of diamond powder having an average particle size of 0.01 to 3.5 μm and 2 to 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, An organic binder such as polyethylene, ethylene-ethyl acrylate, ethylene-vinyl acetate, polybutyl methacrylate, polyethylene glycol, and dibutyl phthalate is added and kneaded, and the cylinder is formed by a molding method such as press molding, extrusion molding, or casting molding. It shape | molds in shape 4 '(refer process (a)).
[0022]
On the other hand, 70 to 95% by weight of hard particles having an average particle diameter of 0.01 to 10 μm or hard particle forming components and an iron group metal powder having an average particle diameter of 10 μm or less are mixed at 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. 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 (see step (a)).
[0023]
The composite molded bodies 4 ′ and 8 ′ are coextruded to produce a composite molded body 1 ′ that is elongated to a thin diameter in which the skin member 8 ′ is covered around the core material 4 ′ (step (step ( b)). In order to produce a multifilament structure, a plurality of the coextruded long shaped bodies 1 ′ may be converged and coextruded again (see step (c)).
[0024]
Further, the elongated elongated shaped body 10 'is formed into a cylindrical, triangular, or quadrangular column as desired. Further, a laminate in which the long shaped bodies 10 ′ are aligned to form a sheet, and the long shaped bodies 10 ′ of the sheet are laminated so as to form a predetermined angle such as parallel, perpendicular, or 45 °. It can also be formed into a body, and can also be formed into an arbitrary shape by a known method such as rapid protodiving. 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.
[0025]
And after carrying out binder removal processing of the said molded object 10 ', the composite structure of this invention can be produced by carrying out ultra high pressure baking. According to the present invention, in order to control the amount of the iron group metals 3 and 7 between the core material 4 ′ and the skin member 8 ′ within a predetermined range, the pressure is 4 GPa or more using an ultrahigh pressure device or the like as the firing condition. The temperature is preferably 1300 ° C. or more and 5 minutes to 1 hour. In particular, when the ratio between the average particle size d ₂ of an average particle diameter d ₁ and the hard particles 6 of the diamond particles 2 (d ₁ / d ₂₎ is 0.8 to 1.2, the firing temperature is 1400 ° C. it is desirable to 1800 is ° C., when the ratio between the average particle size d ₂ of an average particle diameter d ₁ and the hard particles 6 of the diamond particles 2 (d ₁ / d ₂₎ is other than the above range firing temperature It is desirable that the temperature is less than 1400 ° C.
[0026]
【Example】
(Example)
Cobalt powder having an average particle diameter of 2 μm is added to the diamond particles having an average particle diameter and an addition amount shown in Table 1 at a ratio shown in Table 1, and a binder and a lubricant are added thereto and kneaded. A molded body for core material having a diameter of 18 mm was produced.
[0027]
On the other hand, cobalt powder having an average particle diameter of 2 μm is added to the hard particle powder having an average particle diameter and an addition amount shown in Table 1 at a ratio shown in Table 1, and a binder and a lubricant are added thereto and kneaded. Two half-cylindrical skin member molded bodies having a thickness of 1 mm were produced by press molding, and a composite molded body covering the core material molded body was produced.
[0028]
Then, after the composite molded body was coextruded to produce a stretched molded body, 100 stretched molded bodies were converged and coextruded to form a multifilament type molded body. Thereafter, the molded body was subjected to binder removal processing, and then the sample was 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 composite structure.
[0029]
Vickers hardness (according to JISR1601) was measured for the obtained composite structure. Further, wavelength dispersive X-ray microanalysis analysis was performed at five locations on the polished cross section of the sample, and the peak intensity of the iron group metal (Co) was averaged for each of the core member and the skin member (M _d , M _c ). Was estimated, and M _d / M _c was calculated. 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. Also, the above-mentioned composite structure molded body was prepared, and a sheet sliced to a thickness of 3 mm in the cross-sectional direction was bonded to a cemented carbide and sintered at a high pressure under the same conditions as described above. A 10 mm × 10 mm square was cut out using a processing machine. For processing, the feed rate was adjusted so as not to cut the wire, and the processability was compared based on the time required for processing. Moreover, the ridgeline of the sample after a process was observed and the presence or absence of the chipping was confirmed. The results are shown in Table 1.
[0030]
[Table 1]

[0031]
Sample No. The tool having a composite structure of 1 to 8 exhibits excellent electric discharge machining performance with a machining time of 3 minutes or less while maintaining a high hardness of 50 GPa or more, and the machining ridge line is excellent without chipping. It was confirmed that it has high toughness. On the other hand, sample no. In No. 9, since the content of iron group metal was large, the hardness was very low. Sample No. 10 to 12, it took twice or more time for electric discharge machining, the machining performance was very poor, and many chippings were observed on the machining ridge line, and it was confirmed that the fracture toughness varied. .
[0032]
【The invention's effect】
As described above in detail, according to the multicore composite structure of the present invention, the outer periphery of the long core material made of a diamond sintered body in which diamond particles are bonded with an iron group metal is formed on the periodic table 4a, 5a. And a skin member made of a sintered alloy in which one or more hard particles of carbide, nitride and carbonitride of at least one metal element selected from the group of group 6a metals are bonded with an iron group metal A multifilament composite structure having a multifilament structure in which a plurality of composite structures are converged, wherein the total content of the iron group metal in the composite structure is 30% by weight or less, and the core since the ratio between the proportion M _c of the iron group metals of iron group content M _d and the skin member in the metal in the wood _(M d / _{M c)} is 0.8 to 1.2, the core material The amount of iron group metal in the diamond sintered body and the skin member Becomes uniform iron group metals of sintered alloy, it becomes uniform toughness and electrical conductivity in the composite structure, while maintaining a high hardness, an excellent multi-core composite structure machining performance.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional 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 cross-sectional 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

Carbide of at least one metal element selected from the group of the periodic table 4a, 5a, and 6a group metals on the outer periphery of a long core made of a diamond sintered body in which diamond particles are bonded with an iron group metal A multifilament composite having a multifilament structure in which a plurality of composite structures formed by coating a skin member made of a sintered alloy in which one or more hard particles of nitride and carbonitride are bonded with an iron group metal are converged It is a structure, and the content of the iron group metal in the composite structure is 30% by weight or less as a whole, and the content ratio M _d of the iron group metal in the core material and iron in the skin member The multi-core composite structure, wherein the ratio (M _d / M _c ) to the group metal content ratio M _c is 0.8 to 1.2.

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 0.8 to 1.2 The multicore composite structure described.

4. The ratio (D ₂ / D ₁ ) between an average diameter D _{1 of the} core material and an average thickness D ₂ of the skin member is 0.01 to 0.5. 5. The multicore composite structure described.