JP2004115881A

JP2004115881A - TiCN-BASED CERMET AND ITS MANUFACTURING METHOD

Info

Publication number: JP2004115881A
Application number: JP2002282971A
Authority: JP
Inventors: Takashi Tokunaga; 徳永　隆司
Original assignee: Kyocera Corp
Current assignee: Kyocera Corp
Priority date: 2002-09-27
Filing date: 2002-09-27
Publication date: 2004-04-15
Anticipated expiration: 2022-09-27
Also published as: JP4280048B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting tool made of TiCN-based cermet having excellent wear resistance and fracture resistance. <P>SOLUTION: In the TiCN-based cermet, a hard phase in which TiCN and a part of WC, MoC, etc., are made into solid solution is bonded by 1 to 30wt.% of a binder phase of Co and/or Ni, and the hard phase consists of a first hard phase of black color and a second hard phase of grayish white color. The TiCN-based cermet is formed so that the average grain size d<SB>1in</SB>of the first hard phase in the inner part, is 0.05 to 0.5μm; the area ratio S<SB>1in</SB>of the first hard phase, is 40 to 80 area%; the average grain size d<SB>2in</SB>of the second hard phase, is 0.6 to 2μm; and the area ratio S<SB>2in</SB>of the second hard phase, is 5 to 40 area%. Moreover, a surface region existing at the surface of the cermet has the following characteristics: the average grain size d<SB>1sf</SB>of the first hard phase, is 0.3 to 1μm and larger than the d<SB>1in</SB>; the area ratio S<SB>1sf</SB>of the first hard phase, is 5 to 20 area%; the average grain size d<SB>2sf</SB>of the second hard phase, is 1 to 2μm and larger than the d<SB>2in</SB>; and the area ratio S<SB>2sf</SB>of the second hard phase, is 50 to 80 area%. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、切削工具部材、耐摩耗性工具部材等に適する靱性と硬度をともに備えたＴｉＣＮ基サーメットとその製造方法に関するものである。
【０００２】
【従来の技術】
従来より、耐摩耗性工具や切削工具用合金としてＴｉＣ基サーメットやＴｉＣＮ基サーメットが開発されており、特に靭性を改善したＴｉＣＮ基サーメットが広く用いられている。
【０００３】
かかるＴｉＣＮ基サーメットにおいては、特に耐欠損性を向上させることが求められており、例えば、特開平８−１９９２８３号公報（特許文献１）では、硬質相の固溶状態、具体的には芯部が黒色の有芯構造をなす硬質相と芯部が白色の有芯構造をなす硬質相との存在割合、およびその粒度を最適化することによって高速切削等にて発生する熱衝撃に対して優れた耐久性を改善できることが開示されている。
【０００４】
【特許文献１】
特開平８−１９９２８３号公報
【０００５】
【発明が解決しようとする課題】
しかしながら、上記特開平８−１９９２８３号公報にて開示されたサーメットにおいても熱衝撃に対する耐久性は未だ不十分で切削性能の改良に限界があり、更なる耐熱衝撃性の改善および耐欠損性、耐摩耗性の向上が求められていた。
【０００６】
本発明は、上記課題を解決するためのもので、その目的はＴｉＣＮ基サーメットの硬質相の固溶状態を場所毎に適正化して組織の最適化を図ることにより更なる耐欠損性の向上および耐欠損性、耐摩耗性の向上を図ることにある。
【０００７】
【課題を解決するための手段】
本発明においては、原料粉末の粒径、焼成条件の適正化によって、上記硬質相の固溶状態を各部分に合わせてそれぞれ最適化し、サーメット内部において硬質相の微粒化による強度、硬度向上と、サーメット表面における耐熱衝撃性向上とをともに満足させることができる結果、サーメット全体としての耐欠損性および耐摩耗性がともに向上することを知見した。
【０００８】
すなわち、本発明のＴｉＣＮ基サーメットは、ＴｉＣＮとＴｉ以外の周期律表ＩＶａ、ＶａおよびＶＩａ族の金属の中から選択される少なくとも１種の金属の炭化物、窒化物および炭窒化物の少なくとも一部とが固溶してなる硬質相を、Ｃｏおよび／またはＮｉの結合相１〜３０重量％にて結合してなるものであって、該ＴｉＣＮ基サーメット任意断面の走査型電子顕微鏡写真（ＳＥＭ）において、前記硬質相が黒色の第１硬質相と灰白色の第２硬質相とからなり、前記サーメット内部における第１硬質相の平均粒径ｄ_１ｉｎが０．０５〜０．５μｍで、前記サーメット内部の全体に占める第１硬質相の面積比率Ｓ_１ｉｎが４０〜８０面積％からなり、かつ前記サーメット内部における前記第２硬質相の平均粒径ｄ_２ｉｎが０．６〜２μｍで、前記サーメット内部の全体に占める第２硬質相の面積比率Ｓ_２ｉｎが５〜４０面積％からなるとともに、前記サーメット表面に前記第１硬質相の平均粒径ｄ_１ｓｆが０．３〜１μｍでｄ_１ｉｎより大きく、前記サーメット表面部の全体に占める第１硬質相の面積比率Ｓ_１ｓｆが５〜４０面積％からなり、かつ前記サーメット表面における前記第２硬質相の平均粒径ｄ_２ｓｆが１〜３μｍでｄ_２ｉｎより大きく、前記サーメット表面部の全体に占める第２硬質相の面積比率Ｓ_２ｓｆが５０〜８０面積％からなる表面領域が存在することを特徴とするものである。
【０００９】
ここで、前記灰白色の第２硬質相の中心に白色部が存在するとともに、前記サーメット内部における白色部の存在割合が前記サーメット表面における白色部の存在割合よりも多いことが望ましい。
【００１０】
また、前記第１硬質相が金属成分としてＴｉを８０重量％以上含有するとともに、前記灰白色の第２硬質相が前記第１硬質相に対してＴｉ以外の周期律表ＩＶａ、ＶａおよびＶＩａ族の金属の中から選択される少なくとも１種の金属を多く含有することが望ましい。
【００１１】
また、本発明のＴｉＣＮ基サーメットの製造方法は、平均粒径０．１〜１．２μｍのＴｉＣＮ粉末と、Ｔｉ以外の周期律表ＩＶａ、ＶａおよびＶＩａ族の金属の中から選択される少なくとも１種の金属の炭化物、窒化物および炭窒化物の粉末と、Ｃｏおよび／またはＮｉとを調合して所定形状に加工した後、０．７〜２℃／ｍｉｎの昇温速度で１１５０〜１２５０℃まで昇温し、次いで５〜１５℃／ｍｉｎの昇温速度で１４００〜１５００℃まで昇温し、さらに４〜１４℃／ｍｉｎの昇温速度で１５００〜１６００℃まで昇温して所定時間維持し、不活性ガスを１０〜１５０Ｐａ充填した状態で降温することを特徴とする。
【００１２】
【発明の実施の形態】本発明のＴｉＣＮ基サーメット（以下、単にサーメットと略す。）について、その内部の任意断面についての走査型電子顕微鏡写真（ＳＥＭ）である図１および表面を含む任意断面についてのＳＥＭ写真である図２を基に説明する。
【００１３】
図１、２によれば、本発明のＴｉＣＮ基サーメット（以下、単にサーメットと略す。）１は、ＴｉＣＮとＴｉ以外の周期律表ＩＶａ、ＶａおよびＶＩａ族の金属の中から選択される少なくとも１種の金属の炭化物、窒化物および炭窒化物の少なくとも一部とが固溶してなる硬質相２を、１〜３０重量％のＣｏおよび／またはＮｉの結合相３で硬質相２を結合した構成からなり、図１、２によれば、硬質相２は、黒色の第１硬質相２ａと灰白色の第２硬質相２ｂとからなる。
【００１４】
本発明によれば、サーメット１内部（図１）における第１硬質相２ａの平均粒径ｄ_１ｉｎが０．０５〜０．５μｍで、サーメット１内部の全体に占める第１硬質相２ａの面積比率Ｓ_１ｉｎが４０〜８０面積％からなり、かつサーメット１内部における第２硬質相２ｂの平均粒径ｄ_２ｉｎが０．６〜２μｍで、サーメット１内部の全体に占める第２硬質相２ｂの面積比率Ｓ_２ｉｎが５〜４０面積％からなるとともに、サーメット１表面（図２）における第１硬質相２ａの平均粒径ｄ_１ｓｆが０．３〜１μｍで、サーメット１表面部の全体に占める第１硬質相２ａの面積比率Ｓ_１ｓｆが５〜４０面積％からなり、かつサーメット１表面における第２硬質相２ｂの平均粒径ｄ_２ｓｆが１〜３μｍで、サーメット１表面部の全体に占める第２硬質相２ｂの面積比率Ｓ_２ｓｆが５０〜８０面積％からなることが大きな特徴であり、これによって、サーメット１の強度を高めることができるとともに、サーメット１表面における熱伝導率、ヤング率を高めてサーメット１の表面における耐熱衝撃性を向上できることによって、特に高速切削、高送り切削や湿式切削等過酷な熱衝撃が発生するような条件においてもサーメット１の耐摩耗性および耐欠損性を向上させることができる。
【００１５】
なお、上記平均粒径（ｄ_１、ｄ_２）および面積比率（Ｓ_１、Ｓ_２）は、走査型電子顕微鏡（ＳＥＭ）写真に対して市販の画像解析装置を用いることによって測定することができる。
【００１６】
ここで、上記サーメット１内部における第１硬質相２ａの平均粒径ｄ_１ｉｎが０．０５μｍより小さいと、硬質相同士の凝集によって組織が不均質となり強度低下を招くとともに、サーメット１内部の熱伝導率が低下する。逆に、ｄ_１ｉｎが０．５μｍを超えると、サーメット１の強度、硬度が低下していずれも耐欠損性、耐摩耗性が低下する。ｄ_１ｉｎの望ましい範囲は０．１〜０．３μｍである。また、第１硬質相２ａの面積比率Ｓ_１ｉｎが４０面積％より少ないかまたは８０面積％より多いと、サーメット１の強度、硬度が低下する。Ｓ_１ｉｎの望ましい範囲は５０〜７０面積％である。
【００１７】
さらに、サーメット１内部における第２硬質相２ｂの平均粒径ｄ_２ｉｎが０．６μｍより小さいと硬質相２が凝集して不均一な組織となり、ｄ_２ｉｎが２μｍを超えると第２硬質相２ｂの分散状態が悪くなり強度が低下する。ｄ_２ｉｎの望ましい範囲は０．８〜１．５μｍである。また、サーメット１内部における第２硬質相２ｂの面積比率Ｓ_２ｉｎが５面積％より少ないとサーメット１が焼結不良状態となって強度が低下し、Ｓ_２ｉｎが４０面積％より多いとサーメット１が硬質相２全体の平均粒径が大きくなって強度が低下する。Ｓ_２ｉｎの望ましい範囲は１０〜３０面積％である。
【００１８】
一方、サーメット１表面領域においては、第１硬質相２ａの平均粒径ｄ_１ｓｆが０．３μｍより小さいと、熱伝導率および耐塑性変形性が低下し、逆に、ｄ_１ｓｆが１μｍを超えると、サーメット１表面の耐欠損性が低下する。ｄ_１ｓｆの望ましい範囲は０．３〜０．７μｍである。また、サーメット１表面部における第１硬質相２ａの面積比率Ｓ_１ｓｆが５面積％より少ないと、サーメット１の耐塑性変形性が低下し、逆に４０面積％より多いとサーメット１表面の熱伝導性が損なわれて耐熱衝撃性が低下する。Ｓ_１ｓｆの望ましい範囲は７〜２５面積％である。
【００１９】
さらに、サーメット１表面領域における第２硬質相２ｂの平均粒径ｄ_２ｓｆが１μｍより小さいと熱伝導率および耐塑性変形性が低下し、ｄ_２ｓｆが３μｍを超えるとサーメット１表面の耐欠損性が低下する。ｄ_２ｓｆの望ましい範囲は１．２〜２μｍである。また、サーメット１表面部における第２硬質相２ｂの面積比率Ｓ_２ｓｆが５０面積％より少ないとサーメット１の熱伝導率および耐塑性変形性が低下し、Ｓ_２ｓｆが８０面積％より多いと第１硬質相および結合相不足によってサーメット１表面の耐欠損性が低下する。Ｓ_２ｓｆの望ましい範囲は６０〜７５面積％である。
【００２０】
また、本発明によれば、灰白色の第２硬質相２ｂの中心には白色部３ｃが存在するとともに、サーメット１内部（図１）における白色部３ｃの存在割合がサーメット１表面（図２）における白色部３ｃの存在割合よりも多いことが、サーメット１内部の硬質相２（３ａ、３ｂ）を微粒化してサーメット１の強度を高めるとともにサーメット１表面における硬質相２（３ａ、３ｂ）の固溶状態を最適化してサーメット１の耐熱衝撃性を高める点で望ましい。
【００２１】
また、第１硬質相２ａとしては、金属成分としてＴｉを８０重量％以上含有することが望ましく、特に、Ｔｉが８０〜９８重量％、Ｔｉ以外の周期律表ＩＶａ、ＶａおよびＶＩａ族の金属の中から選択される少なくとも１種の金属、特にＷ、Ｍｏ、Ｃｒ、ＮｂおよびＶの一種以上、さらにＷ（本発明では固溶体金属と称す。）の総量が１〜１５重量％、Ｃｏおよび／またはＮｉの結合相金属の総量が０〜３重量％の割合からなることが望ましい。
【００２２】
さらに、前記灰白色の第２硬質相２ｂとしては、第１硬質相２ａに対して固溶体金属を多く含有することが望ましく、特に、Ｔｉが３０〜７０重量％、固溶体金属の総量が７０〜３０重量％、Ｃｏおよび／またはＮｉの結合相金属の総量が０〜３重量％の割合からなることが望ましい。なお、上記硬質相中の金属成分の含有比率は透過型電子顕微鏡（ＴＥＭ）のエネルギー分散分光分析（ＥＤＳ）にて測定可能である。
【００２３】
また、本発明によれば、硬質相２は、第１硬質相２ａを芯部とし、第２硬質相２ｂを周辺部とする２重有芯構造をなしていることが、粒成長抑制効果を有しサーメット１が微細で均一な組織となるとともに、結合相３との濡れ性に優れるためにサーメット１の高強度化に寄与する点で望ましいが、全ての硬質相２が有芯構造をなしていなくてもよい。有芯構造の場合、第２硬質相２ｂの面積は、中心部の第１硬質相２ａの面積を除いた環状部の面積である。
【００２４】
また、本発明によれば、サーメット１の強度、硬度、耐熱衝撃性のバランスを最適化する上で、ｄ_１ｓｆ／ｄ_１ｉｎ＝１〜６、ｄ_２ｓｆ／ｄ_２ｉｎ＝１．５〜１．７、Ｓ_１ｓｆ／Ｓ_１ｉｎ＝０．３〜０．５、Ｓ_２ｓｆ／Ｓ_２ｉｎ＝１．５〜４であることが望ましい。
【００２５】
さらに、サーメット１の耐欠損性および耐摩耗性の両立を図るために前記表面領域の厚みは２０〜１００μｍ、特に３０〜５０μｍとすることが望ましい。
【００２６】
なお、サーメット１におけるビッカース硬度は表面領域内で最大値をとり、内部に向かって次第にビッカース硬度が低下していくことが望ましい。これにより、高い耐摩耗性と耐欠損性の両方を有することができる。
【００２７】
（製造方法）　次に、本発明のＴｉＣＮ基サーメットの製造方法について説明する。
【００２８】
まず、平均粒径０．１〜１．２μｍ、特に０．２〜０．９μｍのＴｉＣＮ粉末と、平均粒径０．１〜２μｍのＴｉＮ粉末、上述した固溶体金属の炭化物粉末、窒化物粉末または炭窒化物粉末のいずれか１種と、Ｃｏ粉末および／またはＮｉ粉末とを混合した混合粉末を調整する。
【００２９】
本発明によれば、上記ＴｉＣＮ原料粉末の平均粒径を０．１〜１．２μｍの範囲に制御することが重要であり、この平均粒径が０．１μｍより小さいと原料が凝集してサーメットが不均質な組織となり、逆に１．２μｍを超えるとサーメットを上述した組織とすることができない。
【００３０】
そして、この混合粉末にバインダーを添加して、プレス成形、押出成形、射出成形等の公知の成形方法によって所定形状に成形する。
【００３１】
次に、上記成形体を、０．７℃／ｍｉｎ〜２℃／ｍｉｎの昇温速度Ａで室温から１１５０〜１２５０℃の焼成温度Ａまで昇温し、１１５０〜１２５０℃から１４００〜１５００℃の焼成温度Ｂまで５℃／ｍｉｎ〜１５℃／ｍｉｎの昇温速度Ｂで昇温し、さらに、１５００〜１６００℃の焼成温度Ｃまで４℃／ｍｉｎ〜１４℃／ｍｉｎの昇温速度Ｂよりも遅い昇温速度Ｃで昇温して所定時間保持した後、不活性ガスを１０〜１５０Ｐａ充填した状態で降温する。
【００３２】
本発明によれば、上記焼成時の昇温速度、および降温時に所定量の不活性ガスを充填した状態で降温することが重要であり、以上の製造方法によって上述した組織のサーメットを作製することができる。
【００３３】
【実施例】平均粒径０．７μｍ、または２μｍのＴｉＣＮ粉末、平均粒径１．５μｍのＴｉＮ粉末、平均粒径２μｍのＴａＣ粉末、平均粒径１．５μｍのＮｂＣ粉末、平均粒径１．１μｍのＷＣ粉末、平均粒径１．８μｍのＺｒＣ粉末、平均粒径１．０μｍのＶＣ粉末、平均粒径２．４μｍのＮｉ粉末、および平均粒径１．９μｍのＣｏ粉末を表１に示す割合で調整した混合粉末をステンレス製ボールミルと超硬ボールを用いて、ＩＰＡにて湿式混合し、パラフィンを３重量％添加、混合した後、２００ＭＰａでＣＮＭＧ１２０４０８にプレス成形し、表１に示す焼成条件で焼成した。なお、降温時にはＨｅガスを表１に示す量だけ注入した。
【００３４】
得られたサーメットをダイヤモンド砥石によって加工し、下記条件にて切削性能を評価した。また、各試料について走査型電子顕微鏡（ＳＥＭ）観察を行い、７０００倍の写真任意５箇所について市販の画像解析ソフトを用いて７ｍｍ×７ｍｍの領域で画像解析を行い、硬質相（第１硬質相、第２硬質相）の存在状態を確認した。結果は表２に示した。
（切削条件）
切削評価１
切削方法：旋削　連続切削（耐摩耗性評価）
切削速度：２３０ｍ／ｍｉｎ
送り　　：０．２５ｍｍ／ｒｅｖ
切込み　：２．０ｍｍ
被削材　：ＳＣＭ４３５
切削状態：湿式（エマルジョン）
切削時間：１０分
評価項目：逃げ面摩耗幅（ｍｍ）
切削評価２
切削方法：旋削　断続切削（耐欠損性評価）
被削材：Ｓ４５Ｃ
被削材：４本溝入り丸棒、
切削速度：１００ｍ／ｍｉｎ、
送りおよび切削時間：０．１ｍｍ／ｒｅｖで１０秒間切削後、送りを０．０５ｍｍ／ｒｅｖずつ上げて各１０秒間ずつ切削（最大送り０．５ｍｍ／ｒｅｖまで）
切込み：２ｍｍ、
評価項目：欠損するまでの総切削時間
切削状態：湿式（エマルジョン）
【００３５】
【表１】

【００３６】
【表２】

【００３７】
表１、２より、本発明品である試料Ｎｏ．１〜１２では、耐摩耗性と耐欠損性のともに優れた結果を示した。これに対して、単純な焼成パターンで焼成した試料Ｎｏ．１３では、表面に所定の表面領域が形成されず、耐摩耗性および耐欠損性がともに低下した。また、焼成温度Ｃが１６００℃を超え、降温時に不活性ガスを大量に導入した試料Ｎｏ．１４、およびＴｉＣＮ原料粒径が１．２μｍを超える試料Ｎｏ．１５では第１または第２硬質相の平均粒径が内部および表面領域ともに所定の範囲を超えてしまい耐欠損性が低下した。さらに、昇温速度Ｂが４℃／ｍｉｎより遅く、焼成温度Ｃが１６００℃を超え、降温時に不活性ガスを導入しなかった試料Ｎｏ．１６では第１硬質相の面積比率が内部において少なくなり、耐欠損性が低下した。また、昇温速度が１４℃／ｍｉｎよりも速く、焼成温度Ｃが１５００℃よりも低い試料Ｎｏ．１７では表面部の第２硬質相の粒径が小さく、かつ表面部の第１硬質相の占める割合が多く、耐摩耗性が低下した。また、焼成温度Ａまで５℃／ｍｉｎで昇温した試料Ｎｏ．１８では内部と表面における第１硬質相の面積比率が多すぎて耐摩耗性が低下した。さらにまた、昇温速度Ａが０．７℃／ｍｉｎより遅く、焼成温度Ｃが１６００℃より高い試料Ｎｏ．１９では表面における第１硬質相の粒径が大きく、かつ第２硬質相の粒径が小さいため、耐摩耗性が低下した。
【００３８】
【発明の効果】
以上、詳述したとおり、本発明のＴｉＣＮ基サーメットによれば、硬質相の固溶状態を各部分に合わせてそれぞれ最適化し、サーメット内部において硬質相の微粒化による強度、硬度向上と、サーメット表面における耐熱衝撃性向上とをともに満足させることができる結果、サーメット全体としての耐欠損性および耐摩耗性がともに向上する。
【００３９】
また、本発明のＴｉＣＮ基サーメットの製造方法によれば、原料粉末の粒径、焼成条件の適正化によって、硬質相の固溶状態を各部分に合わせてそれぞれ最適化し、サーメット内部において硬質相の微粒化による強度、硬度向上と、サーメット表面における耐熱衝撃性向上とをともに満足させることができる結果、サーメット全体としての耐欠損性および耐摩耗性がともに向上する。
【図面の簡単な説明】
【図１】本発明のＴｉＣＮ基サーメットの内部についての走査型電子顕微鏡写真の模写図である。
【図２】本発明のＴｉＣＮ基サーメットの表面付近についての走査型電子顕微鏡写真の模写図である。
【符号の説明】１：ＴｉＣＮ基サーメット
２：硬質相
３：硬質相
４：芯部
５：周辺部[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a TiCN-based cermet having both toughness and hardness suitable for cutting tool members, wear-resistant tool members, and the like, and a method for producing the same.
[0002]
[Prior art]
Hitherto, TiC-based cermets and TiCN-based cermets have been developed as wear-resistant tools and alloys for cutting tools, and TiCN-based cermets with particularly improved toughness have been widely used.
[0003]
In such a TiCN-based cermet, it is particularly required to improve the fracture resistance. For example, Japanese Patent Application Laid-Open No. 8-199283 (Patent Document 1) discloses a solid solution state of a hard phase, specifically, a core portion. Excellent in thermal shock generated by high-speed cutting, etc. by optimizing the proportion of the hard phase having a black cored structure and the hard phase having a white cored structure, and by optimizing the particle size It is disclosed that the durability can be improved.
[0004]
[Patent Document 1]
JP-A-8-199283
[Problems to be solved by the invention]
However, even in the cermet disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 8-199283, the durability against thermal shock is still insufficient, and there is a limit to the improvement of cutting performance. There has been a demand for improved wear properties.
[0006]
The present invention has been made to solve the above-mentioned problems, and the object is to further improve the fracture resistance by optimizing the structure by optimizing the solid solution state of the hard phase of the TiCN-based cermet for each location, and The purpose is to improve fracture resistance and wear resistance.
[0007]
[Means for Solving the Problems]
In the present invention, by optimizing the particle size of the raw material powder and the firing conditions, the solid solution state of the hard phase is optimized according to each part, and the strength and hardness are improved by atomizing the hard phase inside the cermet. As a result of being able to satisfy both the improvement of the thermal shock resistance on the cermet surface, it was found that both the fracture resistance and the wear resistance of the cermet as a whole are improved.
[0008]
That is, the TiCN-based cermet of the present invention comprises at least a part of carbides, nitrides, and carbonitrides of at least one metal selected from metals of Group IVa, Va, and VIa other than TiCN and Ti. A solid phase in which a solid phase is formed by solid-solution bonding of 1 to 30% by weight of a Co and / or Ni binder phase, and a scanning electron micrograph (SEM) of an arbitrary cross section of the TiCN-based cermet. Wherein the hard phase comprises a black first hard phase and a gray-white second hard phase, wherein the average particle diameter d _1in of the first hard phase in the cermet is 0.05 to 0.5 μm, and The area ratio _S1in of the first hard phase in the whole of the cermet is 40 to 80% by area, and the average particle size d2in of the second hard phase in the cermet is 0.6 to ₂ μm. The area ratio S _2in of the second hard phase in the entire cermet is 5 to 40% by area, and the average particle diameter d _1sf of the first hard phase is 0.3 to 1 μm on the cermet surface. The area ratio S _1sf of the first hard phase to the entire cermet surface portion is larger than _{1 in} , and the area ratio S _1sf of the first hard phase is 5 to 40% by area, and the average particle size d 2 _sf of the second hard phase on the cermet surface is 1 to ₃ μm. And a surface region in which the area ratio S _2sf of the second hard phase occupying the entire cermet surface portion is 50 to 80 area%, which is larger than d _{2 in} .
[0009]
Here, it is desirable that a white portion is present at the center of the gray-white second hard phase, and that an existing ratio of the white portion inside the cermet is larger than an existing ratio of the white portion on the cermet surface.
[0010]
Further, the first hard phase contains 80% by weight or more of Ti as a metal component, and the gray-white second hard phase is different from the first hard phase in the periodic table IVa, Va, and VIa group other than Ti. It is desirable to contain a large amount of at least one metal selected from metals.
[0011]
Further, the method for producing a TiCN-based cermet of the present invention comprises the steps of: providing a TiCN powder having an average particle diameter of 0.1 to 1.2 μm and at least one metal selected from metals of Group IVa, Va and VIa other than Ti; After mixing the powders of the carbides, nitrides and carbonitrides of the seed metals with Co and / or Ni and processing them into a predetermined shape, the mixture is processed at a rate of 0.7-2 ° C./min at a rate of 1150-1250 ° C. To 1500 to 1500 ° C at a rate of 5 to 15 ° C / min, and then to 1500 to 1600 ° C at a rate of 4 to 14 ° C / min and maintain for a predetermined time. In addition, the temperature is reduced in a state where the inert gas is filled with 10 to 150 Pa.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION A TiCN-based cermet of the present invention (hereinafter simply abbreviated as a cermet) is a scanning electron micrograph (SEM) of an arbitrary cross section inside the cermet, and FIG. 2 will be described with reference to FIG.
[0013]
According to FIGS. 1 and 2, a TiCN-based cermet (hereinafter simply referred to as a cermet) 1 of the present invention is composed of at least one selected from metals of Group IVa, Va and VIa of the periodic table other than TiCN and Ti. Hard phase 2 in which at least a part of carbides, nitrides and carbonitrides of the same kind of metal forms a solid solution, and hard phase 2 is bound with 1 to 30% by weight of Co and / or Ni binding phase 3 According to FIGS. 1 and 2, the hard phase 2 includes a black first hard phase 2a and an off-white second hard phase 2b.
[0014]
According to the present invention, the average particle diameter d _1in of the first hard phase 2a inside the cermet 1 (FIG. 1) is 0.05 to 0.5 μm, and the area ratio of the first hard phase 2a to the whole inside the cermet 1 S _{1 in} is _composed of 40 to 80 area%, and the average particle size d ₂ in of the second hard phase 2 b inside the cermet 1 is 0.6 to ₂ μm, and the area ratio of the second hard phase 2 b to the whole inside the cermet 1 S _{2 in} is 5 to 40% by area, and the average particle size d _1sf of the first hard phase 2a on the surface of the cermet 1 (FIG. 2) is 0.3 to 1 μm, and the first hard phase occupies the entire surface of the cermet 1. area ratio _{S 1SF} phase 2a consists 5-40 area%, and an average particle diameter _{d 2SF} in the second hard phase 2b is 1~3μm in the cermet 1 surface, a second hard phase in the total of the cermet 1 surface portion b area ratio S _2SF is a significant feature that consists of 50 to 80 area%, thereby, it is possible to increase the strength of the cermet 1, the thermal conductivity of the cermet 1 surface, to increase the Young's modulus cermet 1 By improving the thermal shock resistance on the surface of the cermet 1, the wear resistance and chipping resistance of the cermet 1 can be improved even under severe thermal shock conditions such as high-speed cutting, high-feed cutting and wet cutting. .
[0015]
The average particle size (d ₁ , d ₂ ) and the area ratio (S ₁ , S ₂ ) can be measured by using a commercially available image analyzer for a scanning electron microscope (SEM) photograph. .
[0016]
Here, if the average particle diameter d _1in of the first hard phase 2a inside the cermet ₁ is smaller than 0.05 μm, the structure becomes inhomogeneous due to agglomeration of the hard phases, causing a decrease in strength and the heat conduction inside the cermet 1. The rate drops. Conversely, if d _1in exceeds 0.5 μm, the strength and hardness of the cermet 1 decrease, and both the fracture resistance and the wear resistance decrease. A desirable range of d ₁ in is 0.1 to 0.3 μm. If the area ratio S _1in of the first hard phase 2a is less than 40 area% or more than 80 area%, the strength and hardness of the cermet 1 decrease. The desirable range of S ₁ in is 50 to 70 area%.
[0017]
Further, when the average particle diameter d _2in of the second hard phase 2b inside the cermet 1 is smaller than 0.6 μm, the hard phase 2 aggregates to form a non-uniform structure, and when d _2in exceeds ₂ μm, the second hard phase 2b Dispersion deteriorates and strength decreases. desired range of d _2in is 0.8 to 1.5 .mu.m. Also, if the area ratio S _2in of the second hard phase 2b inside the cermet 1 is less than 5 area%, the cermet 1 will be in a poor sintering state and the strength will be reduced, and if the S _2in is more than 40 area%, the cermet 1 will be poor. The average particle size of the entire hard phase 2 increases, and the strength decreases. Desirable range of S _2in is 10 to 30 area%.
[0018]
On the other hand, in the cermet 1 surface region, when the average particle diameter d _1sf of the first hard phase 2a is smaller than 0.3 μm, the thermal conductivity and the plastic deformation resistance decrease, and conversely, when d _1sf exceeds 1 μm. In addition, the fracture resistance of the surface of the cermet 1 decreases. A desirable range of d _1sf is 0.3 to 0.7 μm. When the area ratio S _1sf of the first hard phase 2a on the surface of the cermet 1 is less than 5% by area, the plastic deformation resistance of the cermet 1 is reduced. Properties are impaired and thermal shock resistance is reduced. A desirable range of S _1sf is 7 to 25 area%.
[0019]
Further, when the average particle size d _2sf of the second hard phase 2b in the cermet 1 surface region is smaller than 1 μm, the thermal conductivity and the plastic deformation resistance decrease, and when the d _2sf exceeds 3 μm, the fracture resistance of the cermet 1 surface decreases. descend. desired range of d _2SF is 1.2～2Myuemu. The area ratio S _2SF in the second hard phase 2b in the cermet 1 surface portion is reduced less as the thermal conductivity and plastic deformation resistance of the cermet 1 50 area%, the the S _2SF is more than 80 area% 1 The shortage of the hard phase and the binder phase lowers the fracture resistance of the cermet 1 surface. A desirable range of _S2sf is 60 to 75 area%.
[0020]
According to the present invention, the white portion 3c exists at the center of the gray-white second hard phase 2b, and the ratio of the white portion 3c inside the cermet 1 (FIG. 1) is determined on the surface of the cermet 1 (FIG. 2). When the proportion of the white portion 3c is larger than that, the hard phase 2 (3a, 3b) inside the cermet 1 is atomized to increase the strength of the cermet 1, and the solid phase of the hard phase 2 (3a, 3b) on the surface of the cermet 1 is dissolved. This is desirable in that the state is optimized and the thermal shock resistance of the cermet 1 is increased.
[0021]
Further, the first hard phase 2a preferably contains 80% by weight or more of Ti as a metal component, and particularly contains 80 to 98% by weight of Ti and a metal of a group IVa, Va or VIa group other than Ti. The total amount of at least one metal selected from among them, particularly one or more of W, Mo, Cr, Nb and V, and further W (referred to as solid solution metal in the present invention) is 1 to 15% by weight, Co and / or It is desirable that the total amount of the binder phase metal of Ni be in the ratio of 0 to 3% by weight.
[0022]
Further, it is desirable that the gray-white second hard phase 2b contains a large amount of solid solution metal with respect to the first hard phase 2a. In particular, the content of Ti is 30 to 70% by weight, and the total amount of solid solution metal is 70 to 30% by weight. %, The total amount of Co and / or Ni binder phase metals is desirably comprised between 0 and 3% by weight. The content ratio of the metal component in the hard phase can be measured by energy dispersive spectroscopy (EDS) of a transmission electron microscope (TEM).
[0023]
Further, according to the present invention, the hard phase 2 has a double cored structure in which the first hard phase 2a has a core portion and the second hard phase 2b has a peripheral portion. It is desirable that the cermet 1 has a fine and uniform structure and contributes to increasing the strength of the cermet 1 because of its excellent wettability with the binder phase 3. However, all the hard phases 2 have a cored structure. It does not have to be. In the case of a cored structure, the area of the second hard phase 2b is the area of the annular portion excluding the area of the first hard phase 2a at the center.
[0024]
Further, according to the present invention, the strength of the cermet 1, the hardness, in order to optimize the balance between thermal shock _{_{_{_{resistance, d 1sf / d 1in = 1~6}}}} , d 2sf / d 2in = 1.5~1.7 _{_{_{, S 1sf / S 1in = 0.3~0.5}}} , it is desirable that the _{S 2sf} / _S 2in = _1.5~4.
[0025]
Further, in order to achieve both the fracture resistance and wear resistance of the cermet 1, the thickness of the surface region is desirably 20 to 100 μm, particularly preferably 30 to 50 μm.
[0026]
It is desirable that the Vickers hardness of the cermet 1 has a maximum value in the surface region, and the Vickers hardness gradually decreases toward the inside. Thereby, both high wear resistance and fracture resistance can be obtained.
[0027]
(Production Method) Next, a method for producing the TiCN-based cermet of the present invention will be described.
[0028]
First, a TiCN powder having an average particle diameter of 0.1 to 1.2 μm, particularly 0.2 to 0.9 μm, a TiN powder having an average particle diameter of 0.1 to 2 μm, a carbide powder, a nitride powder or A mixed powder is prepared by mixing any one of the carbonitride powders with the Co powder and / or the Ni powder.
[0029]
According to the present invention, it is important to control the average particle size of the TiCN raw material powder in the range of 0.1 to 1.2 μm. If the average particle size is smaller than 0.1 μm, the raw material aggregates and cermet Has a heterogeneous structure, and if it exceeds 1.2 μm, the cermet cannot be the above-described structure.
[0030]
Then, a binder is added to the mixed powder and molded into a predetermined shape by a known molding method such as press molding, extrusion molding, or injection molding.
[0031]
Next, the molded body is heated from room temperature to a firing temperature A of 1150 to 1250 ° C at a heating rate A of 0.7 ° C / min to 2 ° C / min. The temperature is raised to a firing temperature B at a heating rate B of 5 ° C./min to 15 ° C./min, and further to a firing temperature C of 1500 to 1600 ° C. than that of 4 ° C./min to 14 ° C./min. After the temperature is increased at a slow temperature increasing rate C and maintained for a predetermined time, the temperature is decreased while the inert gas is filled at 10 to 150 Pa.
[0032]
According to the present invention, it is important to lower the temperature in a state in which a predetermined amount of inert gas is filled at the time of the temperature rise rate during the firing and the predetermined amount of the inert gas at the time of the temperature decrease, and to produce a cermet having the above-described structure by the above manufacturing method. Can be.
[0033]
EXAMPLES The average particle diameter 0.7μm or 2 [mu] m TiCN powder,, TiN powder having an average particle diameter of 1.5 [mu] m, TaC powder having an average particle diameter of 2 [mu] m, NbC powder having an average particle diameter of 1.5 [mu] m, an average particle diameter of 1 Table 1 shows WC powder having an average particle diameter of 0.1 μm, ZrC powder having an average particle diameter of 1.8 μm, VC powder having an average particle diameter of 1.0 μm, Ni powder having an average particle diameter of 2.4 μm, and Co powder having an average particle diameter of 1.9 μm. Using a stainless steel ball mill and carbide balls, the mixed powder adjusted in the ratio shown was wet-mixed with IPA, paraffin was added in an amount of 3% by weight, mixed, press-molded at 200 MPa into CNMG120408, and baked as shown in Table 1. It was fired under the conditions. At the time of cooling, He gas was injected in an amount shown in Table 1.
[0034]
The obtained cermet was processed with a diamond grindstone, and the cutting performance was evaluated under the following conditions. In addition, a scanning electron microscope (SEM) observation was performed on each sample, and image analysis was performed on five arbitrary 7000-fold photographs in a 7 mm × 7 mm area using commercially available image analysis software to obtain a hard phase (first hard phase). , The second hard phase). The results are shown in Table 2.
(Cutting conditions)
Cutting evaluation 1
Cutting method: Turning Continuous cutting (evaluation of wear resistance)
Cutting speed: 230m / min
Feed: 0.25mm / rev
Cut: 2.0mm
Work material: SCM435
Cutting state: wet (emulsion)
Cutting time: 10 minutes Evaluation item: flank wear width (mm)
Cutting evaluation 2
Cutting method: Turning Intermittent cutting (Evaluation of fracture resistance)
Work material: S45C
Work material: Round bar with 4 grooves,
Cutting speed: 100m / min,
Feed and cutting time: After cutting at 0.1 mm / rev for 10 seconds, feed is increased by 0.05 mm / rev and cut for 10 seconds each (up to a maximum feed of 0.5 mm / rev)
Cut: 2mm,
Evaluation item: Total cutting time until breakage Cutting condition: Wet (emulsion)
[0035]
[Table 1]

[0036]
[Table 2]

[0037]
From Tables 1 and 2, it can be seen that Sample No. Nos. 1 to 12 showed excellent results in both abrasion resistance and fracture resistance. On the other hand, Sample No. fired in a simple firing pattern. In No. 13, the predetermined surface area was not formed on the surface, and both the wear resistance and the fracture resistance were reduced. In addition, the sample No. in which the sintering temperature C exceeded 1600 ° C. and a large amount of inert gas was introduced when the temperature was lowered. Sample No. 14 and TiCN raw material particle size exceeding 1.2 μm. In No. 15, the average particle size of the first or second hard phase exceeded the predetermined range in both the internal and surface regions, and the fracture resistance was reduced. Further, Sample No. in which the heating rate B was lower than 4 ° C./min, the firing temperature C exceeded 1600 ° C., and no inert gas was introduced at the time of cooling. In No. 16, the area ratio of the first hard phase was reduced inside, and the fracture resistance was reduced. Further, Sample No. whose heating rate was higher than 14 ° C./min and whose firing temperature C was lower than 1500 ° C. In No. 17, the particle size of the second hard phase on the surface portion was small, and the ratio of the first hard phase on the surface portion was large, and the wear resistance was reduced. Further, the sample No. which was heated to the firing temperature A at 5 ° C./min. In No. 18, the area ratio of the first hard phase between the inside and the surface was too large, and the wear resistance was reduced. Furthermore, the sample No. having a temperature rising rate A lower than 0.7 ° C./min and a firing temperature C higher than 1600 ° C. In No. 19, since the particle size of the first hard phase on the surface was large and the particle size of the second hard phase was small, the wear resistance was reduced.
[0038]
【The invention's effect】
As described above in detail, according to the TiCN-based cermet of the present invention, the solid solution state of the hard phase is optimized according to each part, and the strength and hardness are improved by atomizing the hard phase inside the cermet, and the cermet surface is improved. As a result, both the fracture resistance and the wear resistance of the cermet as a whole can be improved.
[0039]
According to the method for producing a TiCN-based cermet of the present invention, the solid solution state of the hard phase is optimized according to each part by optimizing the particle size of the raw material powder and the firing conditions, and the hard phase of the hard phase is formed inside the cermet. As a result, both improvement in strength and hardness by atomization and improvement in thermal shock resistance on the cermet surface can be satisfied, both the fracture resistance and the wear resistance of the cermet as a whole are improved.
[Brief description of the drawings]
FIG. 1 is a schematic drawing of a scanning electron micrograph of the inside of a TiCN-based cermet of the present invention.
FIG. 2 is a schematic drawing of a scanning electron micrograph of the vicinity of the surface of a TiCN-based cermet of the present invention.
[Explanation of Signs] 1: TiCN-based cermet 2: hard phase 3: hard phase 4: core part 5: peripheral part

Claims

A hard phase formed by solid solution of TiCN and at least a part of carbides, nitrides and carbonitrides of at least one metal selected from metals of Group IVa, Va and VIa of the periodic table other than Ti , Co and / or Ni bonded phase in 1-30% by weight of a TiCN-based cermet, wherein the hard phase is black in a scanning electron micrograph (SEM) of an arbitrary cross section of the TiCN-based cermet. A first hard phase comprising a first hard phase and an off-white second hard phase, wherein the first hard phase in the cermet has an average particle diameter d _1in of 0.05 to 0.5 μm, and the first hard phase occupies the whole of the cermet; area ratio _{S 1in} of consists of 40 to 80 area%, and the average particle size _{d 2in} of the second hard phase in the cermet interior in 0.6～2Myuemu, entire interior of the cermet The area ratio S _2in of the second hard phase to the cermet is 5 to 40% by area, and the average particle diameter d _1sf of the first hard phase is 0.3 to ₁ μm larger than d _{1 in} on the cermet surface; The area ratio S _1sf of the first hard phase to the entire surface portion is 5 to 40% by area, and the average particle diameter d _2sf of the second hard phase on the cermet surface is 1 to ₃ μm and is larger than d _{2 in} , A TiCN-based cermet, wherein there is a surface region in which an area ratio S _2sf of the second hard phase occupying the entire cermet surface portion is 50 to 80 area%.

2. The TiCN according to claim 1, wherein a white portion is present at the center of the gray-white second hard phase, and an existing ratio of the white portion inside the cermet is higher than an existing ratio of the white portion on the cermet surface. 3. Base cermet.

The first hard phase contains 80% by weight or more of Ti as a metal component, and the off-white second hard phase is composed of a group IVa, Va, and VIa group metal other than Ti with respect to the first hard phase. The TiCN-based cermet according to any one of claims 1 to 3, wherein the cermet contains a large amount of at least one metal selected from the group consisting of:

TiCN powder having an average particle size of 0.1 to 1.2 μm, and carbides, nitrides, and carbonitrides of at least one metal selected from metals of Group IVa, Va and VIa other than Ti. After the powder and Co and / or Ni are mixed and processed into a predetermined shape, the temperature is raised to 1150 to 1250 ° C. at a rate of 0.7 to 2 ° C./min, and then 5 to 15 ° C./min. The temperature is raised to 1400 to 1500 ° C. at a rate of temperature increase, further raised to 1500 to 1600 ° C. at a rate of 4 to 14 ° C./min, maintained for a predetermined time, and filled with 10 to 150 Pa of inert gas. A method for producing a TiCN-based cermet to be cooled.