JP4172754B2 - TiCN-based cermet and method for producing the same - Google Patents
TiCN-based cermet and method for producing the same Download PDFInfo
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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】
耐摩耗性工具や切削工具用合金として超硬合金（ＷＣ基焼結合金）が知られているが、鉄鋼の切削におけるクレータ摩耗を改善するためにサーメット合金が開発されている。サーメットとしては、ＴｉＣを主成分とするＴｉＣ基サーメットが開発されたが、靱性が不充分であるとしてＴｉＮを添加したＴｉＣＮ基サーメットが多く提案されている。
【０００３】
また、ＴｉＣＮ基サーメットにおいては、その機械的特性に最も影響を与える硬質分散相を芯部と周辺部からなる２重もしくは３重の有芯構造とすることにより、硬度及び靱性を向上できることが知られている。
【０００４】
【発明が解決しようとする課題】
しかしながら、上記従来の有芯構造からなる硬質分散相では機械的特性や切削性能の改良に限界があり、特に表面に硬質コーティング膜を備えたＷＣ基焼結合金に匹敵する耐熱衝撃性および耐欠損性の向上が望まれていた。
【０００５】
本発明は上記従来の技術で解決し得なかった課題を解決するためのもので、その目的はＴｉＣＮ基サーメットの破壊靱性の向上により更なる耐熱衝撃性および耐欠損性の向上を図ることにある。
【０００６】
【課題を解決するための手段】
本発明者は上記課題に対し、有芯構造を呈する硬質分散相の組織構成について検討した結果、前記硬質分散相内に平均粒径が１〜６０ｎｍのＴｉＮ微粒子を分散せしめることによって耐熱衝撃性、耐欠損性が向上することを知見した。
【０００７】
すなわち、本発明のＴｉＣＮ基サーメットは、Ｃｏおよび／またはＮｉを主体とする結合相５〜３０重量％で硬質分散相を結合してなるＴｉＣＮ基サーメットにおいて、前記硬質分散相内に平均粒径が１〜６０ｎｍのＴｉＮ微粒子が分散していることを特徴とするものである。
【０００８】
ここで、電子顕微鏡写真にて観察した場合、前記硬質分散相が、ＴｉＣＮからなる芯部と、Ｔｉと、Ｗ、Ｍｏ、Ｔａ、Ｖ、ＺｒおよびＮｂのうちの１種以上との複合化合物からなる周辺部とから構成される有芯構造をなすとともに、前記周辺部内に前記ＴｉＮ微粒子が分散していることが望ましい。
【０００９】
また、電子顕微鏡写真にて観察した場合、前記ＴｉＮ微粒子の平均粒径が１〜６０ｎｍであること、前記ＴｉＮ微粒子を含む硬質分散相が、硬質分散相全体に対して１０面積％〜８０面積％の割合で存在することが望ましい。
【００１１】
さらに、本発明のＴｉＣＮ基サーメットの製造方法は、ＴｉＣＮ粉末と、ＴｉＮ粉末と、Ｗ、Ｍｏ、Ｔａ、Ｖ、ＺｒおよびＮｂのうちの１種以上を含有する炭化物粉末、窒化物粉末、炭窒化物粉末の少なくとも１種と、金属Ｗ粉末と、Ｃｏ粉末および／またはＮｉ粉末を混合した混合粉末を成形した後、室温から８００〜１１００℃の第１の焼成温度まで昇温し、前記第１の焼成温度から１３００℃までを０．１℃／ｍｉｎ〜３℃／ｍｉｎで昇温し、ついで、１３００℃から１４００〜１５００℃の第２の焼成温度まで５℃／ｍｉｎ〜１５℃／ｍｉｎで昇温して保持し、さらに、１５００〜１６００℃の第３の焼成温度まで４℃／ｍｉｎ〜１４℃／ｍｉｎの範囲内で前記第２の焼成温度に昇温したときの昇温速度より遅い速度で昇温して保持し、前記第３の焼成温度から１０００℃までを１０℃／ｍｉｎ〜２０℃／ｍｉｎで降温し、さらに１０００℃から室温まで降温する条件で焼成することを特徴とするものである。
【００１２】
ここで、前記混合粉末中に平均粒径５μｍ以下の金属Ｗ粉末を０．１〜１．２重量％の割合で添加することが望ましい。
【００１３】
【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、その任意箇所についての拡大イメージ像である図１を基に説明する。
【００１４】
図１によれば、本発明のサーメット１は、Ｃｏおよび／またはＮｉを主体とする結合相２を５〜３０重量％で硬質分散相３を結合した構成からなり、図１によれば、硬質分散相３は、ＴｉＣＮからなる芯部４と、Ｔｉと、Ｗ、Ｍｏ、Ｔａ、Ｖ、ＺｒおよびＮｂのうちの１種以上との複合化合物からなる周辺部５とから構成される２重有芯構造をなしている。かかる有芯構造をなす硬質分散相３は、粒成長制御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２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。
【００１５】
また、本発明によれば、結合相２の含有量が５重量％より少ないと、靱性の劣化が激しく、耐欠損性が著しく低下し、逆に、結合相２の含有量が３０重量％を超えると、サーメット１の耐摩耗性および耐塑性変形性が低下する。
【００１６】
なお、サーメット１中には上記結合相２、硬質分散相３以外に不可避不純物が含まれていてもよい。また、芯部４は基本的にＴｉＣＮからなるがＴｉ以外の他の金属元素が１０ａｔｏｍ％以下、特に５ａｔｏｍ％以下、さらに２ａｔｏｍ％以下、の割合で含有されていてもよい。また、硬質分散相３は芯部４と周辺部５からなる２重有芯構造であるが、芯部３と周辺部５の間に周辺部５とは異なる構成からなる他の周囲部が存在する３重有芯構造をなすものであってもよい。
【００１７】
本発明によれば、図１に示されるように硬質分散相３内にＴｉＮ微粒子７が分散してなることが大きな特徴であり、これによって高靭性のＴｉＮ微粒子７がクラックを偏向してクラックの進展を抑制する結果、硬質分散相３の耐熱衝撃性と耐欠損性が向上するという効果が得られる。
【００１８】
さらに、ＴｉＮ微粒子７は硬質分散相３内の芯部４または周辺部５のいずれに存在していてもよいが、ＴｉＮ微粒子７のなじみがよく剥離等を生じない点で周辺部５内に分散することが望ましい。
【００１９】
また、ＴｉＮ微粒子７の粒径は、硬度を向上させるために１〜６０ｎｍとすることが重要であり、特に３０〜５０ｎｍとすることが望ましく、かかる微小な粒径に制御するためにはＴｉＮ微粒子７が焼成中に析出したものであることが望ましい。
【００２０】
さらに、電子顕微鏡写真にて観察した場合、ＴｉＮ微粒子７は四角形や六角形等の多角形形状をなすことがクラックの偏向効果が高まって耐欠損性が向上する点で望ましい。
【００２１】
また、硬度および靭性、耐熱衝撃性を向上させるためには、硬質分散相３全体に対してＴｉＮ微粒子７を含有する硬質分散相３が硬質分散相全体に対して３０面積％〜８０面積％、特に４０面積％〜６０面積％の割合で存在することが望ましい。なお、ＴｉＮ微粒子７を含有する硬質分散相の硬質分散相全体に対する面積％とは、透過型電子顕微鏡（ＴＥＭ）５×１０4倍で観察したときに、ＴｉＮ微粒子が析出している硬質分散相の面積の割合である。
【００２２】
さらに、クラックの進展を抑制して耐熱衝撃性を向上させるという点で、ＴｉＮ微粒子７は硬質分散相３の周辺部５内に１μｍ2あたり１０個〜１００００個の密度割合で存在することが望ましい。
【００２３】
また、ＴｉＮ微粒子７の結晶方位は該ＴｉＮ微粒子７の周囲を包み込む硬質分散相３の結晶方位とは異なる方位をなすことが、クラックの偏向性がより向上してクラックの進展をより抑制できる点で望ましい。なお、粒子の結晶方位は透過型電子顕微鏡（ＴＥＭ）の制限視野電子線回折像にて解析することができる。
【００２４】
（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。
【００２５】
まず、ＴｉＣＮ粉末とＴｉＮ粉末、Ｗ、Ｍｏ、Ｔａ、Ｖ、ＺｒおよびＮｂのうちの１種以上を含有する炭化物粉末、窒化物粉末、炭窒化物粉末の少なくとも１種、Ｃｏ粉末および／またはＮｉ粉末を混合して混合粉末を調整する。
【００２６】
本発明によれば、上記混合粉末に対して、平均粒径５μｍ以下の金属Ｗ粉末を０．５〜１．２重量％の割合で添加することが、上述した所定の形状、サイズ、密度のＴｉＮ微粒子を硬質分散相中に析出、分散せしめる点で重要である。
【００２７】
そして、上記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。
【００２８】
次に、本発明によれば、下記の条件にて焼成することにより、上述した所定の形状、サイズ、密度のＴｉＮ微粒子を硬質分散相中に析出、分散させることができる。焼成条件としては、（ａ）例えば、圧力が１Ｐａ〜１５Ｐａの真空中で室温から８００〜１１００℃の第１の焼成温度まで昇温する。（ｂ）前記第１の焼成温度から１３００℃までを０．１℃／ｍｉｎ〜３℃／ｍｉｎ昇温する。（ｃ）ついで１３００℃から１４００〜１５００℃の第２の焼成温度まで５℃／ｍｉｎ〜１５℃／ｍｉｎで昇温して（ｄ）特に０．５〜３時間保持し、（ｅ）さらに１５００℃〜１６００℃の第３の焼成温度まで４℃／ｍｉｎ〜１４℃／ｍｉｎの範囲内で前記第２の焼成温度に昇温したときの昇温速度とは異なる速度で昇温して、（ｆ）その温度を特に０．５〜２時間保持し、（ｇ）前記第３の焼成温度から１０００℃までを１０℃／ｍｉｎ〜２０℃／ｍｉｎで降温し、（ｈ）さらに１０００℃から室温まで降温する、（ａ）〜（ｈ）の条件にて行うことが重要である。
【００２９】
すなわち、上記焼成条件のうち、（ｂ）の昇温速度が０．１℃／ｍｉｎより遅いと炭素の一部が揮発してしまいＴｉＮ微粒子が析出せず、逆に（ｂ）の昇温速度が３℃／ｍｉｎより速いと炭素の硬質分散相への固溶が十分に進行せず、ＴｉＮ微粒子が析出せず焼結不良となる。また、（ｃ）の昇温速度が５℃／ｍｉｎより遅いと、表面付近のＴｉＮ微粒子が存在する硬質分散相の成長が不充分となり、耐摩耗性が低下し、逆に（ｃ）の昇温速度が１５℃／ｍｉｎより速いと表面付近の硬質分散相が過剰に増加することで、耐欠損性が低下する。また、（ｃ）工程においては窒素分圧０〜１３５０Ｐａ下で焼成することが表面状態が荒れることなく焼結体全体が緻密化する点で望ましい。
【００３０】
本発明によれば、上記焼成工程のうち（ｃ）〜（ｆ）工程のように１４００〜１６００℃の間に第２の焼成温度と第３の焼成温度との２つの保持温度およびその温度にいたる昇温速度を上記のとおりに制御することによって、焼結体表面にボイドが発生する等の不具合なく焼成でき、かつ、硬質分散相内にＴｉＮ微粒子を分散せしめることができる。すなわち、第２の焼成温度において、ＴｉＣＮ粉末と金属Ｗ粉末とが反応してＴｉＮ＋ＷＣを析出せしめることができるとともに、各昇温速度を上記範囲とすることによって局部的な過焼結や金属粉末の溶融、蒸発を抑制して均質で制御された特性を有するサーメットを作製することができる。また、（ｇ）の降温速度が１０℃／ｍｉｎより遅いと、表面付近の結合相が揮散し焼肌にボイドを発生させる。逆に（ｇ）の降温速度が２０℃／ｍｉｎより速いとＴｉＮ微粒子が析出せず焼結体表面付近に異常粒成長が起こり、破壊源となる。
【００３１】
【実施例】
（実施例） 平均粒径１．０μｍのＴｉＣＮ粉末、平均粒径１．５μｍのＴｉＮ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２．０μｍ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２．４μｍのＮｉ粉末、平均粒径１．９μｍのＣｏ粉末、平均粒径１．４μｍの金属Ｗ粉末、平均粒径１．０μｍのＣ粉末を用いて表１に示すような成分組成に配合し、これをステンレス製ボールミルと超硬ボールを用いて、ＩＰＡ（イソプロピルアルコール）にて湿式混合し、パラフィンを３重量％添加、混合した後、この混合粉末を２００ＭＰａでＣＮＭＧ１２０４０８にプレス成形し、表１に示す条件で焼成した。
【００３２】
得られた焼結体表面をダイヤモンド砥石によって加工し、得られた切削工具で下記条件にて耐欠損性を評価する切削評価をおこなった。また、各試料について透過型電子顕微鏡（ＴＥＭ）観察を行い、硬質分散相中のＴｉＮ微粒子の有無、存在状態を確認した。さらに、各試料の破壊靭性（ＫiC）を測定した。結果はそれぞれ表２に示した。
切削条件
切削方法：旋削
切削速度：２５０ｍ／ｍｉｎ
送り ：０．４０ｍｍ／ｒｅｖ
切込み ：２．０ｍｍ
被削材 ：ＳＣＭ４３５ ４本溝付き
切削状態：湿式（エマルジョン）
上記の切削条件において、切削工具が欠損するまで切削しつづけて、欠損するまでの切削時間を測定した。
【００３３】
【表１】
【００３４】
【表２】
【００３５】
表１より、硬質分散相の周辺部に平均粒径が１〜６０ｎｍのＴｉＮ微粒子の存在を確認できた試料Ｎｏ．１〜６では、破壊靭性が１０．０よりも高い値で、切削寿命が６５秒以上と長かった。
【００３６】
これに対して、硬質分散相の周辺部にＴｉＮ微粒子が確認できなかった試料Ｎｏ．８〜１０では、破壊靭性も９．０以下と低い値をとり、切削寿命がすべて５０秒以下と短かった。
【００３７】
【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、所定の比率からなる硬質分散相と結合相のうちの硬質分散相内に平均粒径が１〜６０ｎｍのＴｉＮ微粒子を分散せしめることによって、硬質分散相の破壊靭性を向上させることができるとともに、熱膨張係数を低めて熱履歴に対する耐久性を高めることができる結果、サーメットの耐熱衝撃性、耐欠損性が向上する。
【００３８】
また、本発明のＴｉＣＮ基サーメットの製造方法によれば、ＴｉＣＮ粉末と、ＴｉＮ粉末と、Ｗ、Ｍｏ、Ｔａ、Ｖ、ＺｒおよびＮｂのうちの１種以上を含有する炭化物粉末、窒化物粉末、炭窒化物粉末の少なくとも１種と、金属Ｗ粉末と、Ｃｏ粉末および／またはＮｉ粉末を混合した混合粉末を成形した後、室温から８００〜１１００℃の第１の焼成温度まで昇温し、上記第１の焼成温度から１３００℃までを０．１℃／ｍｉｎ〜３℃／ｍｉｎで昇温し、ついで、１３００℃から１４００〜１５００℃の第２の焼成温度まで５℃／ｍｉｎ〜１５℃／ｍｉｎで昇温して保持し、さらに、１５００〜１６００℃の第３の焼成温度まで４℃／ｍｉｎ〜１４℃／ｍｉｎの範囲内で上記第２の焼成温度に昇温したときの昇温速度より遅い速度で昇温して保持し、上記第３の焼成温度から１０００℃までを１０℃／ｍｉｎ〜２０℃／ｍｉｎで降温し、さらに１０００℃から室温まで降温する条件で焼成することから、硬質分散相内にＴｉＮ微粒子が分散したＴｉＣＮ基サーメットを容易に製造することができ、もって破壊靭性が大きく、熱履歴に対する耐久性の高いＴｉＣＮ基サーメットを提供できる。
【図面の簡単な説明】
【図１】本発明のＴｉＣＮ基サーメットの任意箇所における拡大イメージである。
【符号の説明】
１：ＴｉＣＮ基サーメット（サーメット）
２：結合相
３：硬質分散相
４：芯部
５：周辺部
７：ＴｉＮ微粒子[0001]
BACKGROUND 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]
A cemented carbide (WC-based sintered alloy) is known as an alloy for wear-resistant tools and cutting tools, but a cermet alloy has been developed to improve crater wear in steel cutting. As the cermet, a TiC-based cermet containing TiC as a main component has been developed. However, many TiCN-based cermets to which TiN is added have been proposed because of insufficient toughness.
[0003]
Moreover, in TiCN-based cermets, it is known that the hardness and toughness can be improved by forming a double or triple cored structure consisting of a core part and a peripheral part as the hard dispersed phase that has the greatest influence on the mechanical properties. It has been.
[0004]
[Problems to be solved by the invention]
However, the hard dispersed phase consisting of the above conventional cored structure has limitations in improving mechanical properties and cutting performance, and in particular, thermal shock resistance and fracture resistance comparable to a WC-based sintered alloy having a hard coating film on the surface. Improvement of the property was desired.
[0005]
The present invention is to solve the above-mentioned problems that cannot be solved by the prior art, and its purpose is to further improve the thermal shock resistance and fracture resistance by improving the fracture toughness of TiCN-based cermets. .
[0006]
[Means for Solving the Problems]
As a result of examining the structure of the hard dispersed phase exhibiting a cored structure, the present inventor has obtained thermal shock resistance by dispersing TiN fine particles having an average particle diameter of 1 to 60 nm in the hard dispersed phase. It was found that the fracture resistance was improved.
[0007]
That, TiCN-based cermet of the present invention, the TiCN based cermet formed by bonding a hard dispersed phase with binder phase from 5 to 30% by weight composed mainly of Co and / or Ni, average particle size in the hard dispersed phase in the TiN fine particles of 1 to 60 nm are dispersed.
[0008]
Here, when observed with an electron micrograph, the hard dispersed phase is composed of a core composed of TiCN and a composite compound of Ti and one or more of W, Mo, Ta, V, Zr and Nb. Preferably, the TiN fine particles are dispersed in the peripheral portion.
[0009]
Further, when observed with an electron microscope photograph, the average particle diameter before Symbol TiN fine particles are. 1 to 60 nm, the hard dispersed phase containing the TiN fine particles, 10 area% based on the total hard dispersed phase 80 and there child at a ratio of area percent is desirable.
[0011]
Furthermore, the manufacturing method of the TiCN-based cermet of the present invention includes a TiCN powder, a TiN powder, and a carbide powder, a nitride powder, and a carbonitriding containing at least one of W, Mo, Ta, V, Zr and Nb. After molding a mixed powder obtained by mixing at least one kind of product powder, metal W powder, Co powder and / or Ni powder, the temperature is raised from room temperature to a first firing temperature of 800 to 1100 ° C. The temperature is raised from 1 ℃ to 1300 ℃ at 0.1 ℃ / min to 3 ℃ / min, and then from 1300 ℃ to the second calcination temperature of 1400 to 1500 ℃ at 5 ℃ / min to 15 ℃ / min. The temperature is raised and held, and further, the temperature rise rate is slower than the temperature rise rate when the temperature is raised to the second firing temperature within the range of 4 ° C./min to 14 ° C./min up to the third firing temperature of 1500 to 1600 ° C. Keep it warmed at a speed And, wherein the third firing temperature to 1000 ° C. the temperature was lowered at 10 ℃ / min~20 ℃ / min, is characterized in that calcined under conditions in which lowered from 1000 ° C. to room temperature.
[0012]
Here, it is desirable to add metal W powder having an average particle size of 5 μm or less to the mixed powder in a proportion of 0.1 to 1.2% by weight.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
The TiCN-based cermet of the present invention (hereinafter simply referred to as cermet) will be described with reference to FIG.
[0014]
According to FIG. 1, the cermet 1 of the present invention has a configuration in which a hard dispersed phase 3 is bound at 5 to 30% by weight of a binder phase 2 mainly composed of Co and / or Ni. The disperse phase 3 is composed of a core portion 4 made of TiCN and a peripheral portion 5 made of a composite compound of Ti and one or more of W, Mo, Ta, V, Zr and Nb. It has a core structure. The hard dispersed phase 3 having such a cored structure has a grain growth control effect, and the cermet 1 has a fine and uniform structure, and also has excellent wettability with the binder phase 2, thereby contributing to an increase in strength of the cermet 1. To do.
[0015]
Further, according to the present invention, when the content of the binder phase 2 is less than 5% by weight, the toughness is severely deteriorated and the fracture resistance is remarkably lowered. Conversely, the binder phase 2 content is 30% by weight. When it exceeds, the abrasion resistance and plastic deformation resistance of the cermet 1 will fall.
[0016]
The cermet 1 may contain inevitable impurities in addition to the binder phase 2 and the hard dispersed phase 3. Further, the core 4 is basically made of TiCN, but other metal elements other than Ti may be contained in a proportion of 10 atom% or less, particularly 5 atom% or less, and further 2 atom% or less. The hard dispersed phase 3 has a double cored structure composed of a core part 4 and a peripheral part 5, but there is another peripheral part between the core part 3 and the peripheral part 5, which has a different configuration from the peripheral part 5. It may be a triple core structure.
[0017]
According to the present invention, as shown in FIG. 1, the main feature is that the TiN fine particles 7 are dispersed in the hard dispersed phase 3, whereby the high toughness TiN fine particles 7 deflect the cracks and cause cracks. As a result of suppressing the progress, the effect of improving the thermal shock resistance and fracture resistance of the hard dispersed phase 3 is obtained.
[0018]
Further, the TiN fine particles 7 may be present in either the core 4 or the peripheral portion 5 in the hard dispersed phase 3, but are dispersed in the peripheral portion 5 in that the TiN fine particles 7 are familiar and do not cause peeling. It is desirable to do.
[0019]
The particle diameter of the TiN fine particles 7 is important to be 1 to 60 nm in order to improve the hardness , and is particularly preferably 30 to 50 nm. In order to control such a fine particle diameter, TiN It is desirable that the fine particles 7 are precipitated during firing.
[0020]
Further, when observed with an electron micrograph, it is desirable that the TiN fine particles 7 have a polygonal shape such as a quadrangle or a hexagon because the crack deflection effect is enhanced and the fracture resistance is improved.
[0021]
Moreover, in order to improve hardness, toughness, and thermal shock resistance, the hard dispersed phase 3 containing TiN fine particles 7 with respect to the entire hard dispersed phase 3 is 30 to 80 area% with respect to the entire hard dispersed phase, In particular, it is desirable to exist in a ratio of 40 area% to 60 area%. The area% of the hard dispersed phase containing TiN fine particles 7 with respect to the entire hard dispersed phase is a hard dispersed phase in which TiN fine particles are precipitated when observed with a transmission electron microscope (TEM) 5 × 10 4 times. Is the ratio of the area.
[0022]
Furthermore, it is desirable that the TiN fine particles 7 are present in the peripheral portion 5 of the hard dispersed phase 3 at a density ratio of 10 to 10000 per 1 μm 2 in terms of suppressing the progress of cracks and improving the thermal shock resistance. .
[0023]
Further, the crystal orientation of the TiN fine particles 7 is different from the crystal orientation of the hard dispersed phase 3 enclosing the periphery of the TiN fine particles 7, so that the crack deflection is further improved and the progress of the cracks can be further suppressed. Is desirable. The crystal orientation of the particles can be analyzed by a limited field electron diffraction image of a transmission electron microscope (TEM).
[0024]
(Manufacturing method) Next, the manufacturing method of the TiCN group cermet of this invention is demonstrated.
[0025]
First, at least one of carbide powder, nitride powder, carbonitride powder containing at least one of TiCN powder and TiN powder, W, Mo, Ta, V, Zr and Nb, Co powder and / or Ni The powder is mixed to prepare the mixed powder.
[0026]
According to the present invention, adding the metal W powder having an average particle diameter of 5 μm or less to the mixed powder in a proportion of 0.5 to 1.2% by weight has the predetermined shape, size, and density described above. This is important in that the TiN fine particles are precipitated and dispersed in the hard dispersed phase.
[0027]
And a binder is added to the said mixed powder, and it shape | molds in a predetermined shape by well-known shaping | molding methods, such as press molding, extrusion molding, and injection molding.
[0028]
Next, according to the present invention, the TiN fine particles having the predetermined shape, size and density described above can be precipitated and dispersed in the hard dispersed phase by firing under the following conditions. As firing conditions, (a) For example, the temperature is raised from room temperature to a first firing temperature of 800 to 1100 ° C. in a vacuum of 1 to 15 Pa. (B) The temperature is raised from the first firing temperature to 1300 ° C. by 0.1 ° C./min to 3 ° C./min. (C) Then, the temperature is raised from 1300 ° C. to a second firing temperature of 1400 to 1500 ° C. at 5 ° C./min to 15 ° C./min. (D) In particular, held for 0.5 to 3 hours. (E) Further 1500 The temperature is raised at a rate different from the rate of temperature rise when the temperature is raised to the second firing temperature within the range of 4 ° C./min to 14 ° C./min up to a third firing temperature of 1600 ° C. f) Hold the temperature in particular for 0.5 to 2 hours, (g) Decrease the temperature from the third baking temperature to 1000 ° C. at 10 ° C./min to 20 ° C./min, (h) Furthermore, 1000 ° C. to room temperature It is important to carry out under the conditions (a) to (h) where the temperature is lowered to the temperature.
[0029]
That is, among the above firing conditions, if the rate of temperature increase in (b) is slower than 0.1 ° C./min, part of the carbon is volatilized and TiN fine particles are not deposited. If it is faster than 3 ° C./min, solid solution of carbon in the hard dispersed phase does not proceed sufficiently, and TiN fine particles do not precipitate, resulting in poor sintering. On the other hand, when the rate of temperature increase in (c) is slower than 5 ° C./min, the growth of the hard dispersed phase in which TiN fine particles near the surface are present becomes insufficient, and the wear resistance is lowered. When the temperature rate is higher than 15 ° C./min, the hard dispersed phase in the vicinity of the surface is excessively increased, so that the fracture resistance is lowered. In the step (c), firing at a nitrogen partial pressure of 0 to 1350 Pa is desirable because the entire sintered body is densified without roughening the surface state.
[0030]
According to the present invention, the two holding temperatures of the second baking temperature and the third baking temperature are set between 1400 to 1600 ° C. as in the steps (c) to (f) among the baking steps, and the temperature thereof. By controlling the overall rate of temperature rise as described above, firing can be performed without problems such as generation of voids on the surface of the sintered body, and TiN fine particles can be dispersed in the hard dispersed phase. That is, at the second firing temperature, the TiCN powder and the metal W powder can react to precipitate TiN + WC, and local oversintering and metal powder It is possible to produce a cermet having homogeneous and controlled characteristics by suppressing melting and evaporation. Moreover, when the temperature-fall rate of (g) is slower than 10 degree-C / min, the binder phase near the surface will volatilize and a void will be generated in a burnt skin. On the other hand, if the temperature decrease rate of (g) is faster than 20 ° C./min, TiN fine particles do not precipitate and abnormal grain growth occurs near the surface of the sintered body, which becomes a fracture source.
[0031]
【Example】
(Example) TiCN powder having an average particle diameter of 1.0 μm, TiN powder having an average particle diameter of 1.5 μm, ZrC powder having an average particle diameter of 1.8 μm, VC powder having an average particle diameter of 1.0 μm, and an average particle diameter of 2.0 μm TaC powder, NbC powder having an average particle size of 1.5 μm, WC powder having an average particle size of 1.1 μm, Ni powder having an average particle size of 2.4 μm, Co powder having an average particle size of 1.9 μm, and an average particle size of 1.4 μm A metal W powder and a C powder having an average particle diameter of 1.0 μm were blended into the component composition as shown in Table 1, and this was wet with IPA (isopropyl alcohol) using a stainless steel ball mill and carbide balls. After mixing, 3% by weight of paraffin was added and mixed, this mixed powder was press-molded into CNMG120408 at 200 MPa and fired under the conditions shown in Table 1.
[0032]
The surface of the obtained sintered body was processed with a diamond grindstone, and cutting evaluation was performed to evaluate fracture resistance under the following conditions with the obtained cutting tool. Moreover, the transmission electron microscope (TEM) observation was performed about each sample, and the presence or absence of TiN microparticles | fine-particles in a hard dispersed phase was confirmed. Furthermore, the fracture toughness (K iC ) of each sample was measured. The results are shown in Table 2.
Cutting conditions Cutting method: Turning Cutting speed: 250 m / min
Feeding: 0.40mm / rev
Cutting depth: 2.0mm
Work material: SCM435 Four grooved cutting condition: Wet (emulsion)
Under the above cutting conditions, cutting was continued until the cutting tool was chipped, and the cutting time until chipping was measured.
[0033]
[Table 1]
[0034]
[Table 2]
[0035]
From Table 1, Sample No. which has confirmed the presence of TiN fine particles having an average particle diameter of 1 to 60 nm in the periphery of the hard dispersed phase. In Nos. 1 to 6 , the fracture toughness was a value higher than 10.0, and the cutting life was as long as 65 seconds or longer.
[0036]
On the other hand, Sample No. in which TiN fine particles could not be confirmed in the periphery of the hard dispersed phase. In 8-10, the fracture toughness was as low as 9.0 or less, and the cutting life was as short as 50 seconds or less.
[0037]
【The invention's effect】
As described above in detail, according to the TiCN-based cermet of the present invention, by dispersing TiN fine particles having an average particle diameter of 1 to 60 nm in the hard dispersed phase of the hard dispersed phase and the binder phase having a predetermined ratio. As a result, the fracture toughness of the hard dispersed phase can be improved, and the thermal expansion coefficient can be lowered to increase the durability against thermal history. As a result, the thermal shock resistance and fracture resistance of the cermet are improved.
[0038]
Further, according to the method for producing a TiCN-based cermet of the present invention, TiCN powder, TiN powder, carbide powder containing at least one of W, Mo, Ta, V, Zr and Nb, nitride powder, After forming a mixed powder obtained by mixing at least one kind of carbonitride powder, metal W powder, Co powder and / or Ni powder, the temperature is raised from room temperature to a first firing temperature of 800 to 1100 ° C., The temperature is raised from the first firing temperature to 1300 ° C. at 0.1 ° C./min to 3 ° C./min, and then from 1300 ° C. to 1400 ° C. to the second firing temperature of 1400 to 1500 ° C. The rate of temperature rise when the temperature is raised and held at min and further raised to the second firing temperature within a range of 4 ° C./min to 14 ° C./min up to a third firing temperature of 1500 to 1600 ° C. Raise the temperature at a slower rate Holding and lowering the temperature from the third firing temperature to 1000 ° C. at 10 ° C./min to 20 ° C./min, and further firing from 1000 ° C. to room temperature, so that the TiN fine particles are contained in the hard dispersed phase. A dispersed TiCN-based cermet can be easily produced, and thus a TiCN-based cermet having high fracture toughness and high durability against thermal history can be provided.
[Brief description of the drawings]
FIG. 1 is an enlarged image of an arbitrary portion of a TiCN-based cermet of the present invention.
[Explanation of symbols]
1: TiCN-based cermet (cermet)
2: Binder phase 3: Hard dispersed phase 4: Core part 5: Peripheral part 7: TiN fine particles
Claims (5)
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| KR20100014804A (en) * | 2007-05-28 | 2010-02-11 | 쿄세라 코포레이션 | Cermet |
| JP5284684B2 (en) * | 2008-05-12 | 2013-09-11 | ダイジ▲ェ▼ット工業株式会社 | Super hard alloy |
| JP5928806B2 (en) * | 2011-06-29 | 2016-06-01 | 三菱マテリアル株式会社 | Surface coated cutting tool with excellent chipping resistance due to hard coating layer |
| JP5928807B2 (en) * | 2011-09-20 | 2016-06-01 | 三菱マテリアル株式会社 | Surface coated cutting tool with excellent chipping resistance due to hard coating layer |
| CN109457162B (en) * | 2018-12-29 | 2020-03-06 | 重庆文理学院 | Ti (C, N) -based superhard metal composite material and preparation method thereof |
| EP4006202A1 (en) * | 2020-11-26 | 2022-06-01 | AB Sandvik Coromant | A coated cutting tool |
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