JP4280037B2

JP4280037B2 - Method for producing Ti-based cermet

Info

Publication number: JP4280037B2
Application number: JP2002222428A
Authority: JP
Inventors: 隆司徳永
Original assignee: Kyocera Corp
Current assignee: Kyocera Corp
Priority date: 2002-07-31
Filing date: 2002-07-31
Publication date: 2009-06-17
Anticipated expiration: 2022-07-31
Also published as: JP2004060021A

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Ｔｉ基サーメット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した、超硬合金よりも耐磨耗性に優れたＴｉ基サーメット合金が開発されている。
【０００３】
【発明が解決しようとする課題】
しかしながら、上記従来のＴｉ基サーメットでは超硬合金と比較して熱伝導性が悪く、熱膨張係数が大きいために、特に湿式で長時間切削するような場合には、熱衝撃による欠損が発生しやすくなってしまうことから、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が望まれていた。また、乾式切削では熱伝導率が低いことに起因して切削途中の刃先部分が高温になることで塑性変形を引き起こし、その結果切削抵抗が増大し欠損してしまうため、耐塑性変形性の向上が望まれていた。
【０００４】
本発明は上記従来技術の課題を解決するためのもので、その目的はＴｉ基サーメット耐熱衝撃性に優れ、かつ耐塑性変形性にも優れたＴｉ基サーメットを提供することにある。
【０００５】
【課題を解決するための手段】
本発明者は上記課題に対し、Ｔｉ基サーメットの耐熱衝撃性および耐塑性変形性を高める構成について検討した結果、主としてＣｏおよび／またはＮｉを主体とする結合相が溶け込んだ溶出溶液中にＴｉ、Ｚｒ、ＶおよびＷの特定金属を特定の比率で含有せしめることによって結合相の耐塑性変形性および耐熱衝撃性が向上することを知見した。
【０００９】
また、本発明のＴｉ基サーメットの製造方法によれば、ＴｉまたはＴｉ以外の周期律表４ａ、５ａ、６ａ族金属の１種または２種以上で表される炭化物、窒化物、炭窒化物および複合炭窒化物のうちの１種または２種以上から成る硬質分散相を、Ｃｏおよび／またはＮｉを主体としてＴｉ、Ｚｒ、Ｖ、Ｗ、Ｃｏ、Ｎｉの金属元素を含有する結合相５〜３０質量％で結合してなるＴｉ基サーメットの製造方法において、ＴｉＣＮを１９−４５質量％、ＴｉＮを１３−４０質量％、ＷＣを２−２０質量％、ＺｒＣを２−５質量％、ＶＣを０−５質量％とＣｏ及びＮｉからなる結合相５−３０質量％からなる成分組成からなる前記Ｔｉ基サーメットの生成形体を（ａ）室温から８００〜１１００℃の第１の焼成温度まで昇温し、（ｂ）前記第１の焼成温度から１３００℃までを０．１〜３℃／ｍｉｎ昇温し、（ｃ）ついで窒素分圧０〜１３５０Ｐａの雰囲気下１３００℃から１４００〜１６００℃の第２の焼成温度まで５〜１５℃／ｍｉｎで昇温して（ｄ）保持し、（ｅ）前記第２の焼成温度から１３００℃までを１〜３Ｐａの窒素減圧中で１０〜２０℃／ｍｉｎで降温し、（ｆ）１３００℃から１２００℃までを１〜５℃／ｍｉｎで降温し（ｇ）１０００℃から室温まで降温して焼成することを特徴とする。
【００１０】
【発明の実施の形態】
本発明のＴｉ基サーメット（以下、単にサーメットと略す。）とその製造方法について、Ｔｉ基サーメットの任意箇所についての透過型電子顕微鏡写真（ＴＥＭ像）のプロット図である図１を基に説明する。
【００１１】
図１に示すように、本発明のサーメット１は、Ｔｉ、またはＴｉおよびＴｉ以外の周期律表４ａ、５ａ、６ａ属金属の１種または２種以上で表される炭化物、窒化物、炭窒化物および複合炭窒化物のうちの１種または２種以上から硬質分散相３を５〜３０重量％のＣｏおよび／またはＮｉを主体とする結合相２で結合してなるサーメットである。このとき、サーメット１の主結晶相はＴｉＣＮからなることが望ましく、（Ｔｉ、Ｍ）ＣＮの一部にＴｉＣ、ＴｉＮ、ＴｉＣＮの群より選ばれる１種以上を３０重量％以下の割合で含有してもよい。
【００１２】
本発明によれば、サーメット１の粉末０．２ｇを塩酸（１＋１）２０ｍｌにて５０℃、１時間加熱溶出させた主として結合相２が溶け込んだ溶出溶液中に、０．４＜（ｂ＋ｄ）／（ａ＋ｂ＋ｃ＋ｄ）＜０．８（ただしａ、ｂ、ｃ、ｄはそれぞれＴｉ、Ｚｒ、Ｖ、Ｗの重量比）の金属成分を含有せしめることが大きな特徴であり、これによって、硬質分散相３が微細（平均粒径０．１〜２．０μｍ）で均一な組織になるとともに、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結果、かかる硬質分散相３を結合する結合相２にＺｒかつＷが固溶することにより結合相２中の耐塑性変形性が向上し、特に乾式切削においてもサーメット１の耐欠損性が向上する。
【００１３】
一方、前記溶出溶液中の（ｂ＋ｄ）／（ａ＋ｂ＋ｃ＋ｄ）が０．４を下回ると、特に乾式切削によって切刃部が高温になるような場合に金属相の耐塑性変形性が低下して、サーメット自体の耐塑性変形性が低下して耐欠損性および耐摩耗性が低下してしまう。他方、前記溶出溶液中の（ｂ＋ｄ）／（ａ＋ｂ＋ｃ＋ｄ）が０．８を上回ると、金属相の揮散や金属相の濡れ不良によってボイド等の焼結不良が発生してしまい、そこが破壊源となって耐欠損性が低下してしまう。また、硬質分散相の粒径を０．５〜３μｍの微粒にすることでサーメット１の強度を向上させることができるが、結合相に良好な濡れ性が必要となるため、前記関係式の値が０．８以下であることが重要である。
【００１４】
さらに、前記溶出溶液中の０＜ｂ／（ａ＋ｂ＋ｃ＋ｄ）＜０．１５以下であることが焼結不良の発生による耐欠損性の低下を防ぐ点で望ましい。
【００１５】
さらに、前記溶出溶液中の金属元素が０．１＜（ｂ＋ｄ）／（ａ＋ｂ＋ｃ＋ｄ＋ｅ＋ｆ）＜０．２５（ただしａ、ｂ、ｃ、ｄ、ｅ、ｆはそれぞれ結合相中のＴｉ、Ｚｒ、Ｖ、Ｗ、Ｃｏ、Ｎｉの重量比）の関係を満たすことが耐塑性変形性の向上および焼結性改善による焼結体強度の向上の点で望ましい。
【００１６】
また、本発明によれば、結合相２および溶出溶液中にＺｒ、Ｗに加えてＶを固溶させることにより、硬質分散相の成長が抑制されることになり、硬質分散相３間の平均結合相厚みが薄くなることによってサーメット１の熱伝導率が向上し、かつ硬質分散相３と結合相２の熱膨張係数による歪が小さくなるため、湿式切削時に生じる熱疲労に伴う亀裂の発生を抑制することができる。特に前記溶出溶液中の０．０１＜ｃ／（ａ＋ｂ＋ｃ＋ｄ）＜０．１であるとき耐熱衝撃性が改善され、長時間の湿式切削が可能となる点で望ましい。
【００１７】
また、図１によれば、硬質分散相３は、ＴｉＣＮからなる芯部４と、Ｔｉと、Ｚｒ、Ｖ、Ｗ、Ｍｏ、Ｔａ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。このように、硬質分散相３が２重有芯構造をなすことでサーメット１の硬度および靭性を向上させることができる。
【００１８】
なお、これらの有芯構造は芯部４と周辺部５との間に異なる組成からなる他の周辺部が存在する３重有芯構造であってもよい。
【００１９】
（製造方法）次に、本発明のＴｉ基サーメットの製造方法について説明する。
【００２０】
まず、ＴｉＣＮ粉末とＴｉＮ粉末、Ｗ、Ｖ、Ｔａ、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、ＴｉＣＮを１９−４５質量％、ＴｉＮを１３−４０質量％、ＷＣを２−２０質量％、ＺｒＣを２−５質量％、ＶＣを０−５質量％とＣｏ及びＮｉからなる結合相５−３０質量％からなる成分組成に混合した混合粉末および固溶体、共沈体を調整する。
【００２１】
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して生成形体を形成する。
【００２２】
次に、この生成形体を下記の条件にて焼成することにより、上述した所定の組成比で結合相にＴｉ、Ｚｒ、Ｖ、Ｗを固溶させることができる。焼成条件としては、（ａ）室温から８００〜１１００℃の第１の焼成温度まで昇温し、（ｂ）第１の焼成温度から１３００℃までを０．１〜３℃／ｍｉｎで昇温（昇温速度Ｉ）し、（ｃ）ついで窒素分圧０〜１３５０Ｐａの雰囲気下１３００℃から１４００〜１６００℃の第２の焼成温度まで５〜１５℃／ｍｉｎで昇温（昇温速度ＩＩ）して（ｄ）保持し、（ｅ）前記第２の焼成温度から１３００℃までを１〜３Ｐａの窒素減圧中で１０〜２０℃／ｍｉｎで降温（降温速度Ｉ）し、（ｆ）１３００℃から１２００℃までを１〜５℃／ｍｉｎで降温（降温速度ＩＩ）し（ｇ）１０００℃から室温まで降温する条件で焼成することが重要である。
【００２３】
すなわち、上記焼成条件のうち、（ｂ）の昇温速度が０．１℃／ｍｉｎより遅いと結合相中への炭窒化物の拡散が不充分になり、逆に（ｂ）の昇温速度が３℃／ｍｉｎより速いと結合相中へ過剰に金属元素が固溶する。さらに、（ｅ）の窒素減圧が１Ｐａより低いときは、表面から脱窒が起こり、それにともない結合相中に存在する金属元素が不均一な分布となり（ｂ＋ｄ）／（ａ＋ｂ＋ｃ＋ｄ）が０．４未満となってしまう。逆に３Ｐａより高い場合においても金属元素が過剰に移動するため、不均一な分布となり（ｂ＋ｄ）／（ａ＋ｂ＋ｃ＋ｄ）が０．８以上となってしまう。（ｆ）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（ｆ）の降温速度が２０℃／ｍｉｎより速いと焼結体表面付近に異常粒成長が起こり、破壊源となる。
【００２４】
【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１．０μｍ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。
【００２５】
【表１】

【００２６】
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、下記条件にて切削性能を評価した。
切削条件I
切削速度：２５０ｍ／ｍｉｎ
送り：０．２５ｍｍ／ｒｅｖ
切込み：２．０ｍｍ
被削材：ＳＣＭ４３５
切削時間：欠損するまでの時間（ｍｉｎ）
切削状態：湿式（エマルジョン）
切削条件II
切削速度：２５０ｍ／ｍｉｎ
送り：０．２５ｍｍ／ｒｅｖ
切込み：２．０ｍｍ
被削材：ＳＣＭ４３５
切削時間：欠損するまでの時間（ｍｉｎ）
切削状態：乾式
また、各試料について結合相中の金属元素の組成を以下の方法にて測定した。まず、上記焼結体（サーメット）を超硬合金製乳鉢に入れて４０メッシュにてメッシュパスした状態で残渣がないように粉砕し、この粉末０．２ｇを塩酸（１＋１）２０ｍｌにて５０℃、１時間加熱溶出させた後、塩酸（１＋１）にて１００ｍｌ定容とした。この溶出溶液中に含まれる金属元素をＩＣＰ分析によってそれぞれ算出し、（ｂ＋ｄ）／（ａ＋ｂ＋ｃ＋ｄ）、ｃ／（ａ＋ｂ＋ｃ＋ｄ）、（ｂ＋ｄ）／（ａ＋ｂ＋ｃ＋ｄ＋ｅ＋ｆ）の値を求めた。その結果を表２に示す。
【００２７】
【表２】

【００２８】
表２より、所定の条件で焼成した試料Ｎｏ．１〜１０では、いずれも溶出溶液中の金属元素が０．４＜（ｂ＋ｄ）／（ａ＋ｂ＋ｃ＋ｄ）＜０．８の範囲内であり、切削試験での切削寿命が２０分以上と長いものであった。中でも溶出溶液中の０．０１＜ｃ／（ａ＋ｂ＋ｃ＋ｄ）＜０．１の関係を満たす試料Ｎｏ．１〜５は、湿式切削においても超硬工具並みの高い切削性能を発揮するものであった。
【００２９】
また、乾式切削においても同様においても優れた切削性能を示した。これに対して、窒素分圧が１Ｐａより低い雰囲気で焼成を行った試料Ｎｏ．１１では、溶出溶液中の（ｂ＋ｄ）／（ａ＋ｂ＋ｃ＋ｄ）の値が０．４よりも小さくなり、湿式では切削寿命も１２分と短いものだった。乾式でも同様に他の工具と比較して８分と短い工具寿命であった。
【００３０】
また、昇温を１回だけ行い、窒素分圧を０．５Ｐａとして焼成を行った試料Ｎｏ．１２でも、溶出溶液中の（ｂ＋ｄ）／（ａ＋ｂ＋ｃ＋ｄ）の値が０．４よりも小さくなり切削寿命も５分とかなり短いものであった。
【００３１】
さらに、第２の焼成温度を１６００℃と高くし、かつ窒素分圧を５Ｐａと高い雰囲気にして焼成を行った試料Ｎｏ．１３でも試料Ｎｏ．１１，１２と同様に溶出溶液中の（ｂ＋ｄ）／（ａ＋ｂ＋ｃ＋ｄ）の値が０．４よりも小さくなり切削寿命も７分と短かった。
【００３２】
また、第１の降温速度を２０℃／ｍｉｎより高くし、降温時に窒素減圧を行わずに焼成を行った試料Ｎｏ．１４も溶出溶液中の（ｂ＋ｄ）／（ａ＋ｂ＋ｃ＋ｄ）の値が０．４よりも小さくなり切削寿命も３分と短かった。
【００３３】
さらに、第１の昇温速度を３℃／ｍｉｎ以上で焼成した試料Ｎｏ．１５では、結合相中の金属元素が過剰に固溶してしまい、溶出溶液中の（ｂ＋ｄ）／（ａ＋ｂ＋ｃ＋ｄ）の値が０．８を超え、焼結体表面にボイドが発生してしまった。切削性能も湿式で１分と非常に短かった。
【００３５】
【発明の効果】
本発明のＴｉ基サーメットの製造方法によれば、ＴｉＣＮを１９−４５質量％、ＴｉＮを１３−４０質量％、ＷＣを２−２０質量％、ＺｒＣを２−５質量％、ＶＣを０−５質量％とＣｏ及びＮｉからなる結合相５−３０質量％からなる成分組成の生成形体を用いて、（ａ）室温から８００〜１１００℃の第１の焼成温度まで昇温し、（ｂ）前記第１の焼成温度から１３００℃までを０．１〜３℃／ｍｉｎ昇温し、（ｃ）ついで窒素分圧０〜１３５０Ｐａの雰囲気下１３００℃から１４００〜１６００℃の第２の焼成温度まで５〜１５℃／ｍｉｎで昇温して（ｄ）保持し、（ｅ）前記第２の焼成温度から１３００℃までを１〜３Ｐａの窒素減圧中で１０〜２０℃／ｍｉｎで降温し、（ｆ）１３００℃から１２００℃までを１〜５℃／ｍｉｎで降温し（ｇ）１０００℃から室温まで降温して焼成することから、Ｃｏおよび／またはＮｉを主体とする結合相中に０．４＜（ｂ＋ｄ）／（ａ＋ｂ＋ｃ＋ｄ）＜０．８（ただしａ、ｂ、ｃ、ｄはそれぞれ結合相中のＴｉ、Ｚｒ、Ｖ、Ｗの重量）の関係を満たす金属元素を固溶させることができ、もって結合相の耐塑性変形性が高まり、サーメットの耐欠損性、耐熱衝撃性を向上させることができる。
【図面の簡単な説明】
【図１】本発明のＴｉ基サーメットの任意箇所における透過型電子顕微鏡イメージ（ＴＥＭイメージ像）である。
【符号の説明】
１：Ｔｉ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[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a Ti-based cermet having both toughness and hardness suitable for cutting tool members, wear-resistant tool members, and the like.
[0002]
[Prior art]
Although cemented carbide (WC-based sintered alloy) is known as an alloy for wear-resistant tools and cutting tools, it has improved crater wear in steel cutting, and has superior wear resistance than cemented carbide. Base cermet alloys have been developed.
[0003]
[Problems to be solved by the invention]
However, the conventional Ti-based cermet has poor thermal conductivity compared to cemented carbide and has a large coefficient of thermal expansion. Therefore, especially when wet cutting is performed for a long time, defects due to thermal shock occur. Therefore, thermal shock resistance comparable to that of a WC-based sintered alloy having a hard coating film on the surface has been desired. Also, in dry cutting, because the thermal conductivity is low, the cutting edge part in the middle of cutting causes high temperature plastic deformation, resulting in increased cutting resistance and chipping, resulting in improved plastic deformation resistance. Was desired.
[0004]
The present invention is to solve the above-mentioned problems of the prior art, and an object thereof is to provide a Ti-based cermet having excellent Ti-based cermet thermal shock resistance and excellent plastic deformation resistance.
[0005]
[Means for Solving the Problems]
As a result of investigating the structure for improving the thermal shock resistance and plastic deformation resistance of Ti-based cermets, the present inventors have studied Ti, in an elution solution in which a binder phase mainly composed of Co and / or Ni is dissolved. It has been found that the plastic deformation resistance and the thermal shock resistance of the binder phase are improved by containing specific metals of Zr, V and W in a specific ratio.
[0009]
According to the manufacturing method of Ti-based cermet of the present invention, the Periodic Table 4a other than Ti or Ti, 5a, carbides represented by the one or more kinds of 6a group metal, nitrides, carbonitrides And a hard dispersed phase composed of one or more of the composite carbonitrides, a binder phase 5 containing a metal element of Ti, Zr, V, W, Co, Ni mainly containing Co and / or Ni. In a method for producing a Ti-based cermet formed by bonding at 30 % by mass , TiCN is 19-45% by mass, TiN is 13-40% by mass, WC is 2-20% by mass, ZrC is 2-5% by mass, and VC is The Ti-based cermet product formed from the component composition consisting of 0-5% by mass and 5-30% by mass of Co and Ni binder phase is heated from (a) room temperature to a first firing temperature of 800-1100 ° C. (B) the first firing The temperature is raised from the formation temperature to 1300 ° C. by 0.1 to 3 ° C./min, (c) and then from 1300 ° C. to 1400 to 1600 ° C. under a nitrogen partial pressure of 0 to 1350 Pa to 5 to 15 ° C. (D) hold at (d), and (e) lower the temperature from the second firing temperature to 1300 ° C. at 10-20 ° C./min in a nitrogen reduced pressure of 1 to 3 Pa, and (f) 1300 ° C. The temperature is lowered from 1 to 1200 ° C. at 1 to 5 ° C./min (g), and the temperature is lowered from 1000 ° C. to room temperature.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The Ti-based cermet of the present invention (hereinafter simply abbreviated as cermet) and the method for producing the Ti-based cermet will be described with reference to FIG. 1, which is a plot of a transmission electron micrograph (TEM image) of an arbitrary portion of the Ti-based cermet. .
[0011]
As shown in FIG. 1, the cermet 1 of the present invention is composed of carbides, nitrides, carbonitrides represented by Ti, or one or more of Periodic Tables 4a, 5a, 6a metals other than Ti and Ti. Cermet obtained by bonding the hard dispersed phase 3 with a binder phase 2 mainly composed of 5 to 30% by weight of Co and / or Ni. At this time, the main crystal phase of cermet 1 is preferably composed of TiCN, and (Ti, M) CN contains one or more selected from the group of TiC, TiN, and TiCN in a proportion of 30% by weight or less. May be.
[0012]
According to the present invention, 0.2 g of cermet powder 1 was heated and eluted with 20 ml of hydrochloric acid (1 + 1) at 50 ° C. for 1 hour in an elution solution in which mainly the binder phase 2 was dissolved, 0.4 <(b + d) / The main feature is that it contains a metal component of (a + b + c + d) <0.8 (where a, b, c and d are weight ratios of Ti, Zr, V and W, respectively). As a result of contributing to the increase in strength of the cermet 1 because it is fine (average particle size 0.1 to 2.0 μm) and has a uniform structure and excellent wettability with the binder phase 2, the hard dispersed phase 3 is bonded. When Zr and W are dissolved in the binder phase 2 to be formed, the plastic deformation resistance in the binder phase 2 is improved. In particular, the fracture resistance of the cermet 1 is also improved in dry cutting.
[0013]
On the other hand, when (b + d) / (a + b + c + d) in the elution solution is less than 0.4, the plastic deformation resistance of the metal phase is lowered particularly when the cutting edge becomes hot due to dry cutting, and the cermet As a result, the plastic deformation resistance of itself decreases, and the fracture resistance and wear resistance decrease. On the other hand, if (b + d) / (a + b + c + d) in the elution solution is more than 0.8, sintering failure such as voids may occur due to volatilization of the metal phase or poor wetting of the metal phase, As a result, the fracture resistance is lowered. Further, the strength of the cermet 1 can be improved by making the particle size of the hard dispersed phase 0.5 to 3 μm, but the binder phase needs to have good wettability. Is less than or equal to 0.8.
[0014]
Further, it is desirable that 0 <b / (a + b + c + d) <0.15 or less in the elution solution from the viewpoint of preventing a decrease in fracture resistance due to the occurrence of sintering failure.
[0015]
Further, the metal element in the elution solution is 0.1 <(b + d) / (a + b + c + d + e + f) <0.25 (where a, b, c, d, e, and f are Ti, Zr, V, It is desirable to satisfy the relationship of (weight ratio of W, Co, Ni) in terms of improving the plastic deformation resistance and improving the strength of the sintered body by improving the sinterability.
[0016]
In addition, according to the present invention, the growth of the hard dispersed phase is suppressed by dissolving V in addition to Zr and W in the binder phase 2 and the elution solution. Since the thermal conductivity of the cermet 1 is improved by reducing the thickness of the binder phase, and the strain due to the thermal expansion coefficient of the hard dispersed phase 3 and the binder phase 2 is reduced, the generation of cracks due to thermal fatigue that occurs during wet cutting. Can be suppressed. In particular, it is preferable that 0.01 <c / (a + b + c + d) <0.1 in the elution solution is improved in thermal shock resistance and enables long-time wet cutting.
[0017]
Further, according to FIG. 1, the hard dispersed phase 3 includes a core portion 4 made of TiCN and a peripheral portion made of a composite compound of Ti and one or more of Zr, V, W, Mo, Ta, and Nb. 5 to form a double cored structure. Thus, the hardness and toughness of the cermet 1 can be improved because the hard dispersed phase 3 has a double-core structure.
[0018]
These cored structures may be a triple cored structure in which another peripheral part having a different composition exists between the core part 4 and the peripheral part 5.
[0019]
(Manufacturing method) Next, the manufacturing method of Ti group cermet of this invention is demonstrated.
[0020]
First, at least one of TiCN powder and TiN powder, carbide powder, nitride powder, carbonitride powder containing one or more of W, V, Ta, Zr and Nb, Co powder and / or Ni powder. , TiCN 19-45 mass%, TiN 13-40 mass%, WC 2-20 mass%, ZrC 2-5 mass%, VC 0-5 mass%, and a binder phase 5- A mixed powder, a solid solution, and a coprecipitate mixed in a component composition of 30% by mass are prepared.
[0021]
And a binder is added to this mixed powder, and it shape | molds by the well-known shaping | molding methods, such as press molding, extrusion molding, and injection molding, and forms a production | generation form.
[0022]
Next, by firing this formed shape under the following conditions, Ti, Zr, V, and W can be dissolved in the binder phase at the predetermined composition ratio described above. As firing conditions, (a) the temperature is raised from room temperature to a first firing temperature of 800 to 1100 ° C., and (b) the temperature is raised from the first firing temperature to 1300 ° C. at 0.1 to 3 ° C./min ( (C) Next, the temperature was raised from 1300 ° C. to a second firing temperature of 1400 to 1600 ° C. in a nitrogen partial pressure of 0 to 1350 Pa at a rate of 5 to 15 ° C./min (temperature raising rate II). (D) holding, (e) lowering the temperature from the second firing temperature to 1300 ° C. at a rate of 10 to 20 ° C./min in a reduced pressure of 1 to 3 Pa at a rate of 10 to 20 ° C./min (f) from 1300 ° C. It is important that the temperature is lowered to 1200 ° C. at a rate of 1 to 5 ° C./min (temperature-decreasing rate II) (g) and fired under the condition of decreasing the temperature from 1000 ° C. to room temperature.
[0023]
That is, among the firing conditions described above, if the heating rate of (b) is slower than 0.1 ° C./min, the diffusion of carbonitride into the binder phase becomes insufficient, and conversely, the heating rate of (b) If it is faster than 3 ° C./min, the metal element is excessively dissolved in the binder phase. Further, when the nitrogen pressure reduction in (e) is lower than 1 Pa, denitrification occurs from the surface, and accordingly, the metal elements present in the binder phase are unevenly distributed, and (b + d) / (a + b + c + d) is less than 0.4. End up. Conversely, even when the pressure is higher than 3 Pa, the metal element moves excessively, resulting in non-uniform distribution and (b + d) / (a + b + c + d) is 0.8 or more. When the temperature lowering rate of (f) is slower than 10 ° C./min, the binder phase near the surface is volatilized and voids are generated on the skin. On the other hand, when the rate of temperature decrease in (f) is faster than 20 ° C./min, abnormal grain growth occurs near the surface of the sintered body, which becomes a fracture source.
[0024]
【Example】
(Example) TiCN powder with an average particle diameter of 1.0 μm, TiN powder with an average particle diameter of 1.5 μm, ZrC powder with an average particle diameter of 1.8 μm, VC powder with an average particle diameter of 1.0 μm), average particle diameter of 1. Using 1 μm WC powder, Ni powder having an average particle size of 2.4 μm, Co powder having an average particle size of 1.9 μm, and C powder having an average particle size of 1.0 μm, the composition shown in Table 1 was blended. Was wet mixed with IPA using a stainless steel ball mill and cemented carbide balls, 3% by weight of paraffin was added and mixed, and then the mixed powder was press-molded into CNMG120408 at 200 MPa and fired under the conditions shown in Table 1. .
[0025]
[Table 1]

[0026]
The surface of the obtained sintered body was processed with a diamond grindstone, and the cutting performance was evaluated under the following conditions.
Cutting condition I
Cutting speed: 250 m / min
Feeding: 0.25mm / rev
Cutting depth: 2.0mm
Work material: SCM435
Cutting time: Time until chipping (min)
Cutting state: wet (emulsion)
Cutting condition II
Cutting speed: 250 m / min
Feeding: 0.25mm / rev
Cutting depth: 2.0mm
Work material: SCM435
Cutting time: Time until chipping (min)
Cutting state: dry type Moreover, the composition of the metal element in the binder phase of each sample was measured by the following method. First, the sintered body (cermet) was put in a cemented carbide mortar and pulverized so that there was no residue in a state of being passed through a mesh with 40 mesh, and 0.2 g of this powder was added at 50 ° C. with 20 ml of hydrochloric acid (1 + 1). After elution with heating for 1 hour, the volume was adjusted to 100 ml with hydrochloric acid (1 + 1). The metal elements contained in this elution solution were calculated by ICP analysis, and the values of (b + d) / (a + b + c + d), c / (a + b + c + d), (b + d) / (a + b + c + d + e + f) were obtained. The results are shown in Table 2.
[0027]
[Table 2]

[0028]
From Table 2, sample No. baked under the predetermined conditions. 1 to 10, all of the metal elements in the elution solution were within the range of 0.4 <(b + d) / (a + b + c + d) <0.8, and the cutting life in the cutting test was as long as 20 minutes or longer. . Among them, sample No. 1 satisfying the relationship of 0.01 <c / (a + b + c + d) <0.1 in the elution solution. Nos. 1 to 5 exhibited high cutting performance similar to that of carbide tools even in wet cutting.
[0029]
In addition, the dry cutting showed excellent cutting performance in the same manner. On the other hand, sample No. 1 fired in an atmosphere having a nitrogen partial pressure lower than 1 Pa. 11, the value of (b + d) / (a + b + c + d) in the elution solution was smaller than 0.4, and the wet cutting life was 12 minutes. Similarly, the dry tool life was as short as 8 minutes compared to other tools.
[0030]
In addition, sample No. 1 was heated only once and baked with a nitrogen partial pressure of 0.5 Pa. No. 12, the value of (b + d) / (a + b + c + d) in the elution solution was smaller than 0.4, and the cutting life was as short as 5 minutes.
[0031]
Further, Sample No. No. 1 was fired in an atmosphere in which the second firing temperature was increased to 1600 ° C. and the nitrogen partial pressure was increased to 5 Pa. 13 also sample no. Similar to 11 and 12, the value of (b + d) / (a + b + c + d) in the elution solution was smaller than 0.4 and the cutting life was as short as 7 minutes.
[0032]
Sample No. 1 was fired without first reducing the nitrogen pressure when the first temperature-decreasing rate was higher than 20 ° C./min. 14, the value of (b + d) / (a + b + c + d) in the elution solution was smaller than 0.4, and the cutting life was as short as 3 minutes.
[0033]
Furthermore, sample No. 1 fired at a first heating rate of 3 ° C./min or more. 15, the metal element in the binder phase was excessively dissolved, the value of (b + d) / (a + b + c + d) in the elution solution exceeded 0.8, and voids were generated on the surface of the sintered body. . Cutting performance was also very short at 1 minute when wet.
[0035]
【The invention's effect】
According to the method for producing a Ti-based cermet of the present invention, TiCN is 19-45% by mass, TiN is 13-40% by mass, WC is 2-20% by mass, ZrC is 2-5% by mass, and VC is 0-5. Using a product having a component composition consisting of 5% by mass of a binder phase consisting of 5% by mass and Co and Ni, (a) raising the temperature from room temperature to a first firing temperature of 800-1100 ° C., (b) The temperature is raised from the first firing temperature to 1300 ° C. by 0.1 to 3 ° C./min, (c) and then from 1300 ° C. to 1400 to 1600 ° C. under a nitrogen partial pressure of 0 to 1350 Pa. The temperature is raised at ˜15 ° C./min and held (d), and (e) the temperature from the second firing temperature to 1300 ° C. is lowered at 10 to 20 ° C./min in a nitrogen reduced pressure of 1 to 3 Pa, and (f ) From 1300 ° C to 1200 ° C at 1-5 ° C / min (G) Since the sintering is performed by lowering the temperature from 1000 ° C. to room temperature, 0.4 <(b + d) / (a + b + c + d) <0.8 (where a, b, c, and d can each dissolve a metal element satisfying the relationship of the weight of Ti, Zr, V, and W in the binder phase, thereby increasing the plastic deformation resistance of the binder phase and increasing the resistance to fracture of the cermet. And thermal shock resistance can be improved.
[Brief description of the drawings]
FIG. 1 is a transmission electron microscope image (TEM image) at an arbitrary position of a Ti-based cermet according to the present invention.
[Explanation of symbols]
1: Ti-based cermet (cermet)
2: Binder phase 3: Hard dispersed phase 4: Core part 5: Peripheral part

Claims

Ti or 4a in the periodic table other than Ti and Ti,, 5a, carbides represented by the one or more kinds of 6a group metal, nitride, one of carbonitride and composite carbonitride or Ti-based cermet obtained by bonding a hard dispersed phase composed of two or more kinds with a binding phase of 5 to 30 % by mass containing a metal element of Ti, Zr, V, W, Co, and Ni mainly containing Co and / or Ni. In this manufacturing method, TiCN is 19-45% by mass, TiN is 13-40% by mass, WC is 2-20% by mass, ZrC is 2-5% by mass, VC is 0-5% by mass, and Co and Ni are included. The Ti-based cermet formed body having a component composition consisting of 5-30% by mass of a binder phase is heated from (a) room temperature to a first firing temperature of 800 to 1100 ° C., and (b) the first firing temperature. 0 to 1300 ° C. (C) Then, the temperature was raised from 1300 ° C. to a second firing temperature of 1400 to 1600 ° C. at a rate of 5 to 15 ° C./min in an atmosphere with a nitrogen partial pressure of 0 to 1350 Pa (d And (e) the temperature from the second firing temperature to 1300 ° C. is decreased at 10 to 20 ° C./min in a nitrogen reduced pressure of 1 to 3 Pa, and (f) the temperature from 1300 ° C. to 1200 ° C. is 1 to 5 ° C. (G) A method for producing a Ti-based cermet, wherein the temperature is lowered from 1000 ° C. to room temperature and firing is performed.