JP4034931B2 - Coated cemented carbide member and method for producing the same - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は被覆超硬合金部材およびその製造方法に関し、特に切削工具などに使用される強靭かつ耐摩耗性に優れた被覆超硬合金部材およびその製造方法に関する。
【０００２】
【従来の技術】
超硬合金の表面に炭化チタンなどの被覆層を蒸着した被覆超硬合金は、母材の靭性と表面の耐摩耗性を兼備えるため、鋼や鋳物などの切削用工具として多く用いられている。
【０００３】
近年、切削工具における切削効率の高効率化が進んでいる。切削効率は、切削速度（Ｖ）と送り量（ｆ）との積によって決定される。切削速度（Ｖ）を上昇させると、工具寿命が急速に低下する。そのため、送り量（ｆ）を大きくすることによって切削効率の向上が図られてきた。送り量（ｆ）を大きくすることによって切削効率を向上させるためには、切削工具の母材として、高い切削応力に対応できる強靭な材料を用いることが要求される。
【０００４】
切削工具において、耐摩耗性と耐欠損性という相反する特性を両立させて切削特性を向上させるために、従来からいくつかの提案がなされている。その例として、超硬合金の最表面に鉄族金属の量が部材内部に比べて多い層（結合相富化層）を有するもの、超硬合金の最表面にＷＣと結合相金属のみからなる層（脱β層）を有するものをそれぞれ母材とすることにより、耐摩耗性と耐欠損性の向上を図ることが提案されてきた。また、それらを補うための技術として、刃先の稜線部分の表面にも脱β層を形成することや（特開平６−７３５６０号：従来は刃先の稜線部分には脱β層は形成されなかった）、結合相富化層より表面に結合相減少層を設けること（特許２７６２７４５号）等が提案されてきた。
【０００５】
【発明が解決しようとする課題】
しかしながら、切削条件が厳しくなるなか、耐摩耗性と靭性を有する工具を提供するには、表面に脱β層を設けるだけでは対応できなくなってきた。すなわち、脱β層中には、Ｔｉ、Ｔａ、あるいはＮｂ化合物などの硬質相成分が内部に対して減少している層が存在するが、それら硬質相成分の減少は超硬合金の耐熱性を低下させる欠点がある。
【０００６】
また、超硬合金の強度を向上させる方法として、母材中の結合相成分の量を多くする方法がある。ところが、母材中の結合相成分の量が増加すると靭性は向上するものの、高い切削速度の条件下においては刃先温度が高くなるため、刃先に塑性変形が生じるという問題があった。
【０００７】
本発明はこのような従来技術の問題点に鑑みてなされたものであり、その目的は、耐摩耗性を劣化させることなく、耐欠損性を向上させた被覆超硬合金部材とその製造方法を提供することにある。また、本発明の他の目的は、高能率の切削加工においても、耐摩耗性と靭性との両方を兼備えた被覆超硬合金部材とその製造方法を提供することにある。
【０００８】
【課題を解決するための手段】
上記目的を達成するために、請求項１に係る被覆超硬合金部材では、１種以上の鉄族金属を結合相とし、Ｚｒを必須とし、さらに、Ｔａ、ＴｉおよびＮｂのうちの１種以上を含有する周期律表４ａ、５ａ、６ａ族金属を含む化合物を硬質相とする超硬合金母材の表面に、周期律表４ａ、５ａ、６ａ族金属の化合物またはＡｌ２Ｏ３から選ばれた１種以上の単層または複層から成る被覆層を形成した被覆超硬合金部材において、前記Ｚｒと、Ｔａ、ＴｉおよびＮｂのうちの１種以上の原子とが前記母材の内部領域よりも表面領域において減少しているとともに、前記Ｔａ、ＴｉおよびＮｂのうちの１種以上の原子の減少割合が前記Ｚｒ原子の減少割合よりも小さいことを特徴とする。
【０００９】
上記被覆超硬合金部材では、前記表面領域の厚さが５〜２００μｍであることが望ましい。
【００１０】
また、上記被覆超硬合金部材では、前記結合相が前記母材の内部領域よりも表面領域において減少していることが望ましい。
【００１１】
また、請求項４に係る被覆超硬合金部材の製造方法では、１種以上の鉄族金属と、Ｚｒを必須とし、さらに、Ｔａ、ＴｉおよびＮｂのうちの１種以上を含有する周期律表４ａ、５ａ、６ａ族金属を含む化合物とを調合して焼成して超硬合金母材を形成した後に、この母材の表面に周期律表４ａ、５ａ、６ａ族金属の化合物またはＡｌ２Ｏ３から選ばれた１種以上の単層または複層から成る被覆層を形成する被覆超硬合金部材の製造方法において、前記調合物を焼成する際に１３５０℃以下における昇温速度を５℃／分以下とし、その後１２．５℃／分の昇温速度で昇温して１４００〜１６００℃で焼成する工程を有することを特徴とする。
【００１２】
【発明の実施の形態】
以下、各請求項に係る被覆超硬合金部材とその製造方法を説明する。
本発明の被覆超硬合金部材は、主として１種以上の鉄族金属から成る結合相と周期律表４ａ、５ａ、６ａ族金属の化合物から成る硬質相とで構成される。
【００１３】
結合相を構成する鉄族金属にはＣｏ、Ｎｉ、Ｆｅなどがあり、硬質相成分の溶解度などとの関係からＣｏ、Ｎｉがよく使用される。その添加量は２〜２０ｗｔ％が適当である。
【００１４】
硬質相を構成する周期律表４ａ、５ａ、６ａ族金属の化合物には、Ｗ、Ｔａ、Ｔｉ、Ｎｂ、Ｚｒのうちの１種以上からなる炭化物、窒化物、炭窒化物、酸化物、炭酸化物、窒酸化物、炭酸窒化物などがあり、耐摩耗性と靭性を向上させるには、ＷＣを主成分とすることが好ましい。また、Ｖ、Ｃｒ、Ｍｏのうちの１種以上からなる炭化物、窒化物、炭窒化物、酸化物、炭酸化物、窒酸化物、炭酸窒化物などを用いてもよい。
【００１５】
この硬質相には一種以上のＺｒ化合物を含む。このＺｒ化合物には、例えばＺｒＣ、ＺｒＣＮ、ＺｒＯ、（Ｚｒ、Ｗ）Ｃ、（Ｚｒ、Ｔｉ、Ｗ）Ｃ、（Ｚｒ、Ｔｉ、Ｔａ、Ｗ）Ｃ、あるいは（Ｚｒ、Ｔｉ、Ｔａ、Ｎｂ、Ｗ）ＣなどようにＺｒを含む炭化物、窒化物、炭窒化物、酸化物、炭酸化物、窒酸化物、炭酸窒化物より選ばれた１種以上がある。Ｚｒ化合物は０．２〜１０ｗｔ％添加することが望ましい。この添加量が０．２ｗｔ％未満になるとＺｒ添加による切削性能の向上の効果が無くなり、１０ｗｔ％を超えると焼結不良等の問題が起こり、合金自体の強度が低下してしまう。
【００１６】
この超硬合金母材の表面には、周期律表４ａ、５ａ、６ａ族金属の化合物から成る硬質相が内部に対して減少している表面領域が形成される。
内部に対して減少する硬質相元素には、Ｚｒを必須とし、Ｔａ、ＴｉおよびＮｂのうちの１種以上が含まれ、さらにはＶ、Ｃｒ等がある。
【００１７】
この表面領域の厚みは５〜２００μｍが望ましい。この表面領域の厚みが５μｍ以下であると、表面付近までβ層が残ることとなり、そのβ層が破壊源となって強度が低下する。また、２００μｍより大きいときは、表面付近においてβ層が無いことにより、刃先の耐熱性が低下する。この表面領域の厚みは、後述する焼成条件によって変化する。
【００１８】
本発明では、Ｚｒと、Ｔａ、ＴｉおよびＮｂのうちの１種以上の原子とが母材の内部領域よりも表面領域において減少しているとともに、Ｔａ、ＴｉおよびＮｂのうちの１種以上の原子の減少割合がＺｒ原子の減少割合よりも小さいことを特徴とする。ここで内部領域とは母材表面より脱β層の影響が無い十分内部のことであり、一例として脱β層の厚みが８０〜１００μｍのときは約１０００〜２０００μｍ程度となる。これらの値は焼成条件（昇温速度、焼成雰囲気）、窒化物添加量等により変化する。
【００１９】
Ｔａ、Ｔｉ、およびＮｂ化合物はＺｒ化合物に比べて母材の耐熱性を向上させることができる利点がある。
しかしそれらがβ層の形で母材の表面に存在すると破壊源となって強度が低下する問題がでてくる。
そこで、それら化合物を脱β層内に固溶させて、脱β層を強化させ、それらのなかでもより耐熱性に影響があるＴａ、ＴｉおよびＮｂのうちの１種の化合物を耐熱性に影響しにくいＺｒ化合物より多く存在させることで、より効果が増すことがわかった。
【００２０】
ここで周期律表４ａ、５ａ、６ａ族金属の化合物が内部に対して減少している層、その層におけるＺｒと、Ｔｉ、ＴａおよびＮｂのうちの１種以上の化合物の内部に対する減少割合は、ＸＭＡ（Ｘ線マイクロアナライシス）等により求めることができる。
ここではより精度の高いＷＤＳ（波長分散型Ｘ線マイクロアナライザー）分析装置（（株）日本電子製：ＪＸＡ−８６００Ｍ）で分析した。分析エリアは測定のバラツキをなくすために、表面部に平行に約２５０μｍの範囲をもたせて行い、深さ方向に分析を行った。分析個所については少なくとも同一試料の４ヶ所以上を測定し、それらの平均値を利用した。試料にはＣＮＭＡ１２０４１２の工具を平面研削盤等ですくい面側から約２，０００μｍほど研削した後、その研削面を鏡面加工してその面を分析した。
分析結果を図１に示す。すなわち、図１はＷＤＳによる分析結果を示し、表面から内部への深さ方向の原子の分布状態を示す。横軸０μｍは母材表面部を表し、横軸は表面からの深さである。縦軸は内部に対するカウント値の比率である。
【００２１】
本発明の被覆超硬合金部材の好ましい実施例においては、超硬合金母材の表面部における周期律表４ａ、５ａ、６ａ族金属の化合物が内部に対して減少している領域の厚さが５〜２００μｍになっている。これは５μｍ未満では脱β層としての効果（表面までβ層が残ることとなり、そのβ層が破壊源となる強度の低下）が無くなり、２００μｍより大きいときは、刃先の耐熱性が低下するからである。
【００２２】
また、従来の脱β層では、結合相富化層があることにより、高い切削速度においては刃先温度が高くなる条件下において、刃先の塑性変形が生じる問題があった。この問題は合金中の鉄族金属の量を減少する方法で解決することができる。ここでいう結合相富化層とは内部に対して鉄族金属量が多い層であり、これらの分析方法は前記ＸＭＡで求めることができる。この分析結果を図１に示す。
【００２３】
超硬合金母材の表面には被覆層を設ける。被覆層は、周期律表４ａ、５ａ、６ａ族金属の炭化物、窒化物、炭窒化物、酸化物、硼化物およびＡｌ2Ｏ3（酸化アルミニウム）から選ばれた１種以上の単層または複層から成り、ＣＶＤ法、ＰＶＤ法、あるいはＰＣＶＤ法等の化学蒸着法や物理蒸着法で形成される。この被覆層によって、高速切削における耐摩耗性と耐欠損性をバランス良く向上させることができる。
【００２４】
上記超硬合金母材は、１４００〜１６００℃程度の温度で維持することにより焼成される。この焼成の際に、１３５０℃以下における昇温速度を５℃／分以下とし、その後１２．５℃／分の昇温速度で昇温して１４００〜１６００℃で焼成することが重要である。Ｚｒは高温でのＣｏの溶解度がＴａ、Ｔｉに比べて多いのに対し、低温でのＣｏの溶解度はＴａ、Ｔｉに比べて少ないことから、通常液相出現温度といわれている１３５０℃以下の昇温速度を変化させる。
本発明ではＺｒ化合物を調合時に添加して、１３５０℃以下における昇温速度を５℃／分以下とすることで脱β層を作成し、その層におけるＺｒ化合物の内部に対する減少割合に対し、Ｔａ、Ｔｉ、またはＮｂ化合物の内部に対する減少割合が少ない層を含む層、望ましくは前記結合相成分（鉄族金属）も内部に対して減少する層を作成することができる。
その後、超硬合金母材の表面に被覆層を形成する。
【００２５】
【実施例】
以下、本発明の実施例について説明する。
表１に示す１〜５の組成（重量％）からなる原料粉をＩＳＯ規格ＣＮＭＧ１２０４０８の形状を有するチップに成形して脱脂した後、１３５０℃まで表１に示す昇温速度条件にて昇温し、その後１４５０℃までを１２．５℃／分の昇温速度で昇温して１時間保持した後に冷却した。こうして表1に示す試料１〜５を作製した。
【００２６】
【表１】
表1に示す試料１〜２（本発明品）は、Ｚｒ原子の内部に対する減少割合に対し、Ｔａ、Ｔｉ、Ｎｂ原子の内部に対する減少割合が少ない層が存在した。この層厚みおよびそれらの原子の減少量の比の大小をＷＤＳで測定した。その結果を表１の減少量の比の大小に示す。
【００２８】
また、表1に示す試料３（本発明品）は、Ｚｒ原子の内部に対する減少割合に対し、Ｔａ、Ｔｉ、Ｎｂ原子の内部に対する減少割合が少ない層が存在し、なおかつＣｏ減少層が存在した。この層厚みおよびそれらの原子の減少量の比の大小をＷＤＳで測定した。
【００２９】
また、表1の試料４、５（従来品）では、Ｚｒ原子の内部に対する減少割合に対し、Ｔａ、Ｔｉ、Ｎｂ原子の内部に対する減少割合が多くなっている。
【００３０】
これらの焼結体の切刃稜線部にホーニング処理を行なった後、その焼結体表面に通常のＣＶＤ法で内層にＴｉの窒化物および炭窒化物を計９μｍ、外層に酸化アルミニウムを３μｍの厚さで被覆層を形成した。
【００３１】
これらの試料を用いて、下記の条件で切削時の耐チッピング性テスト及び耐摩耗性テストを行った。これらのテスト結果を表２に示す。
耐チッピング性テスト：
切削速度 ３５０ｍ／ｍｉｎ
被削材 ＦＣ２５０
送り ０．５ｍｍ／ｒｅｖ
切込み ２．０ｍｍ
切削時間 ２ｓｅｃ
耐摩耗性テスト：
切削速度 ５００ｍ／ｍｉｎ
被削材 ＦＣ２５０
送り ０．５ｍｍ／ｒｅｖ
切込み ２．０ｍｍ
切削時間 １．２ｍｉｎ
【００３２】
【表２】
表２の結果から、Ｚｒ原子の内部に対する減少割合に対し、Ｔａ、Ｔｉ、Ｎｂ原子の内部に対する減少割合が少ない層を好ましい範囲に調製した試料（試料Ｎｏ．１、２、３）は、その他の試料（試料Ｎｏ．４、５）に比較して耐チッピング性がともに優れていることが分かる。
【００３４】
また、表２の結果から、Ｃｏが内部に対して減少している層を含む試料（試料Ｎｏ．３）は、その他の試料（試料Ｎｏ．２）に比較して耐摩耗性が優れていることが分かる。
【００３５】
【発明の効果】
以上のように、請求項１に係る被覆超硬合金部材では、Ｚｒと、Ｔａ、ＴｉおよびＮｂのうちの１種以上の原子とが前記母材の内部領域よりも表面領域において減少しているとともに、前記Ｔａ、ＴｉおよびＮｂのうちの１種以上の原子の減少割合が前記Ｚｒ原子の減少割合よりも小さいことから、超硬合金の耐熱性の低下を最小限に抑えることができる。
【００３６】
また、請求項２に係る被覆超硬合金では、表面領域の厚さが５〜２００μｍであることから、この表面層を脱β層として充分に作用させることができ、刃先の耐熱性を向上させることができる。
【００３７】
また、請求項３に係る被覆超硬合金では、結合相が母材の内部領域よりも表面領域において減少していることから、高い切削速度においても刃先温度が高くなることを極力防止でき、もって刃先の塑性変形を防止できる。
【００３８】
さらに、請求項４に係る被覆超硬合金の製造方法によれば、１種以上の鉄族金属と、Ｚｒを必須とし、さらに、Ｔａ、ＴｉおよびＮｂのうちの１種以上を含有する周期律表４ａ、５ａ、６ａ族金属を含む化合物との調合物を焼成する際に１３５０℃以下における昇温速度を５℃／分以下とし、その後１２．５℃／分の昇温速度で昇温して１４００〜１６００℃で焼成する工程を有することから、脱β層中の組成をＴａ、ＴｉおよびＮｂのうちの１種以上の原子の減少割合がＺｒ原子の減少割合よりも小さくなるようにコントロールすることができ、超硬合金の耐熱性の低下を最小限に抑えることができる。
【図面の簡単な説明】
【図１】本発明に係る被覆超硬合金部材の波長分散型Ｘ線マイクロアナライザーによる分析結果を示す図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a coated cemented carbide member and a method for producing the same, and more particularly to a coated cemented carbide member having excellent toughness and wear resistance used for a cutting tool and the like and a method for producing the same.
[0002]
[Prior art]
Coated cemented carbide with a titanium carbide coating layer deposited on the surface of cemented carbide has many toughnesses for the base metal and wear resistance of the surface, so it is often used as a cutting tool for steel and castings. .
[0003]
In recent years, cutting efficiency in cutting tools has been increasing. The cutting efficiency is determined by the product of the cutting speed (V) and the feed amount (f). When the cutting speed (V) is increased, the tool life is rapidly reduced. Therefore, the cutting efficiency has been improved by increasing the feed amount (f). In order to improve the cutting efficiency by increasing the feed amount (f), it is required to use a tough material that can cope with high cutting stress as the base material of the cutting tool.
[0004]
In the cutting tool, several proposals have been made in order to improve the cutting characteristics by satisfying the conflicting characteristics of wear resistance and fracture resistance. As an example, the outermost surface of the cemented carbide has a layer (bonded phase enriched layer) in which the amount of iron group metal is larger than that inside the member, and the outermost surface of the cemented carbide consists only of WC and the binder phase metal. It has been proposed to improve wear resistance and fracture resistance by using a base material for each layer having a layer (de-β layer). Further, as a technique for supplementing them, a deβ layer is also formed on the surface of the ridge line portion of the blade edge (Japanese Patent Laid-Open No. 6-73560: Conventionally, a de β layer was not formed on the ridge line portion of the blade edge. ), Providing a binder phase reducing layer on the surface of the binder phase enriched layer (Japanese Patent No. 2762745) has been proposed.
[0005]
[Problems to be solved by the invention]
However, in order to provide a tool having wear resistance and toughness under severe cutting conditions, it has become impossible to respond only by providing a de-β layer on the surface. That is, in the de-β layer, there is a layer in which hard phase components such as Ti, Ta, or Nb compounds are reduced with respect to the inside, but the reduction of these hard phase components reduces the heat resistance of the cemented carbide. There are drawbacks to reduce.
[0006]
Further, as a method for improving the strength of the cemented carbide, there is a method for increasing the amount of the binder phase component in the base material. However, although the toughness is improved when the amount of the binder phase component in the base material is increased, the cutting edge temperature is increased under the conditions of a high cutting speed, so that there is a problem that plastic deformation occurs in the cutting edge.
[0007]
The present invention has been made in view of such problems of the prior art, and an object thereof is to provide a coated cemented carbide member with improved fracture resistance without deteriorating wear resistance and a method for producing the same. It is to provide. Another object of the present invention is to provide a coated cemented carbide member having both wear resistance and toughness even in high-efficiency cutting, and a method for producing the same.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, in the coated cemented carbide member according to claim 1, at least one iron group metal is used as a binder phase, Zr is essential, and at least one of Ta, Ti, and Nb is used. periodic table 4a containing, 5a, a compound containing a 6a group metal on the surface of the cemented carbide base material and the hard phase, selected periodic table 4a, 5a, from the compound or Al 2 O 3 of 6a group metal In the coated cemented carbide member in which a coating layer composed of one or more single layers or multiple layers is formed, the Zr and one or more atoms of Ta, Ti, and Nb are contained in an inner region of the base material. Is also reduced in the surface region, and the reduction ratio of one or more of Ta, Ti and Nb is smaller than the reduction ratio of the Zr atoms.
[0009]
In the said coated cemented carbide member, it is desirable that the thickness of the said surface area | region is 5-200 micrometers.
[0010]
Moreover, in the said coated cemented carbide member, it is desirable for the said binder phase to reduce in the surface area | region rather than the internal area | region of the said base material.
[0011]
Moreover, in the manufacturing method of the covering cemented carbide member which concerns on Claim 4, 1 or more types of iron group metals , Zr are essential, Furthermore, the periodic table containing 1 or more types of Ta, Ti, and Nb After a compound containing 4a, 5a, and 6a group metal is prepared and fired to form a cemented carbide base material, a periodic table 4a, 5a, and 6a group metal compound or Al 2 O is formed on the surface of the base material. In the method for producing a coated cemented carbide member for forming a coating layer composed of one or more single layers or multiple layers selected from 3 , a temperature increase rate at 1350 ° C. or lower when firing the preparation is 5 ° C. / It is characterized by having a step of heating at 1400 to 1600 ° C. after heating at 12.5 ° C./min .
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the coated cemented carbide member according to each claim and the manufacturing method thereof will be described.
The coated cemented carbide member of the present invention is mainly composed of a binder phase composed of one or more iron group metals and a hard phase composed of a compound of periodic table 4a, 5a, 6a group metals.
[0013]
The iron group metal constituting the binder phase includes Co, Ni, Fe, and the like, and Co and Ni are often used in view of the solubility of the hard phase component. The addition amount is suitably 2 to 20 wt%.
[0014]
The periodic table 4a, 5a, and 6a group metal compounds constituting the hard phase include carbides, nitrides, carbonitrides, oxides, carbonic acids composed of one or more of W, Ta, Ti, Nb, and Zr. In order to improve wear resistance and toughness, it is preferable that WC is a main component. Moreover, you may use the carbide | carbonized_material, nitride, carbonitride, oxide, carbonate, nitride oxide, carbonitride etc. which consist of 1 or more types among V, Cr, and Mo.
[0015]
This hard phase contains one or more Zr compounds. Examples of the Zr compound include ZrC, ZrCN, ZrO, (Zr, W) C, (Zr, Ti, W) C, (Zr, Ti, Ta, W) C, or (Zr, Ti, Ta, Nb, W) One or more selected from carbides, nitrides, carbonitrides, oxides, carbonates, nitrides, and carbonitrides containing Zr, such as C. It is desirable to add 0.2 to 10 wt% of the Zr compound. If the amount added is less than 0.2 wt%, the effect of improving the cutting performance due to the addition of Zr is lost, and if it exceeds 10 wt%, problems such as poor sintering occur and the strength of the alloy itself is reduced.
[0016]
On the surface of the cemented carbide base material, a surface region is formed in which the hard phase composed of the compounds of the periodic table 4a, 5a, and 6a group metals decreases with respect to the inside.
The hard phase element that decreases with respect to the inside requires Zr , includes one or more of Ta, Ti, and Nb, and further includes V, Cr, and the like.
[0017]
The thickness of this surface region is preferably 5 to 200 μm. When the thickness of the surface region is 5 μm or less, the β layer remains up to the vicinity of the surface, and the β layer becomes a source of destruction and the strength is lowered. Moreover, when larger than 200 micrometers, the heat resistance of a blade edge falls because there is no (beta) layer in the surface vicinity. The thickness of this surface region varies depending on the firing conditions described later.
[0018]
In the present invention, Zr and one or more atoms of Ta, Ti, and Nb are reduced in the surface region rather than the inner region of the base material, and one or more of Ta, Ti, and Nb The reduction ratio of atoms is smaller than the reduction ratio of Zr atoms. Here, the internal region is a sufficiently internal region that is not affected by the de-β layer from the surface of the base material. For example, when the thickness of the de-β layer is 80 to 100 µm, the inner region is about 1000 to 2000 µm. These values vary depending on firing conditions (temperature increase rate, firing atmosphere), nitride addition amount, and the like.
[0019]
Ta, Ti, and Nb compounds have the advantage that the heat resistance of the base material can be improved compared to Zr compounds.
However, if they are present on the surface of the base material in the form of a β layer, there arises a problem that the strength decreases due to a fracture source.
Therefore, these compounds are solid-dissolved in the de-β layer to strengthen the de-β layer, and among them, one of Ta, Ti and Nb , which has an effect on heat resistance, affects the heat resistance. It has been found that the effect is further increased by the presence of more Zr compounds that are difficult to form.
[0020]
Here the periodic table 4a, 5a, a layer compound of 6a group metal is reduced with respect to the interior, and Zr in the layer, Ti, reduction ratio inside of one or more compounds of Ta and Nb is , XMA (X-ray microanalysis) or the like.
Here, the analysis was performed with a more accurate WDS (wavelength dispersion type X-ray microanalyzer) analyzer (JXA-8600M, manufactured by JEOL Ltd.). In order to eliminate variation in measurement, the analysis area was provided with a range of about 250 μm parallel to the surface portion, and analysis was performed in the depth direction. As for the analysis location, at least 4 locations of the same sample were measured, and the average value was used. As a sample, a tool of CNMA120412 was ground with a surface grinder or the like from the rake face side by about 2,000 μm, and then the ground surface was mirror-finished to analyze the face.
The analysis results are shown in FIG. That is, FIG. 1 shows the analysis result by WDS, and shows the distribution state of atoms in the depth direction from the surface to the inside. The horizontal axis represents 0 μm of the base material surface, and the horizontal axis represents the depth from the surface. The vertical axis represents the ratio of the count value to the inside.
[0021]
In a preferred embodiment of the coated cemented carbide member of the present invention, the thickness of the region where the compound of the periodic table 4a, 5a, 6a group metal in the surface portion of the cemented carbide base material is reduced relative to the inside is It is 5 to 200 μm. This is because if it is less than 5 μm, the effect as a β-free layer (the β layer remains on the surface, and the β layer becomes a source of destruction), and if it is larger than 200 μm, the heat resistance of the cutting edge decreases. It is.
[0022]
Further, the conventional de-β layer has a problem that the cutting edge is plastically deformed under the condition that the cutting edge temperature becomes high at a high cutting speed due to the presence of the binder phase enriched layer. This problem can be solved by reducing the amount of iron group metal in the alloy. The term “bond phase enriched layer” as used herein refers to a layer having a large amount of iron group metal relative to the inside, and these analytical methods can be determined by the XMA. The analysis result is shown in FIG.
[0023]
A coating layer is provided on the surface of the cemented carbide base material. The coating layer is composed of one or more single layer or multiple layers selected from carbides, nitrides, carbonitrides, oxides, borides and Al 2 O 3 (aluminum oxide) of the periodic table 4a, 5a, 6a metals. It consists of layers and is formed by chemical vapor deposition or physical vapor deposition such as CVD, PVD, or PCVD. With this coating layer, wear resistance and fracture resistance in high-speed cutting can be improved in a well-balanced manner.
[0024]
The cemented carbide base material is sintered by maintaining at a temperature of about 1400 to 1600 ° C.. In this firing, it is important to set the temperature rising rate at 1350 ° C. or lower to 5 ° C./min or lower, and then raise the temperature at 12.5 ° C./min and fire at 1400 to 1600 ° C. Zr has higher Co solubility at high temperatures than Ta and Ti, while Co solubility at low temperatures is lower than Ta and Ti, so it is usually called 1350 ° C or less, which is said to be the liquid phase appearance temperature. Change the heating rate.
In the present invention, a Zr compound is added at the time of preparation, and a de-β layer is prepared by setting the temperature rising rate at 1350 ° C. or less to 5 ° C./min or less. It is possible to create a layer including a layer having a small reduction ratio with respect to the inside of Ti, Ti, or Nb compound, preferably a layer in which the binder phase component (iron group metal) is also reduced with respect to the inside.
Thereafter, a coating layer is formed on the surface of the cemented carbide base material.
[0025]
【Example】
Examples of the present invention will be described below.
The raw material powder having the composition (weight%) of 1 to 5 shown in Table 1 was formed into a chip having the shape of ISO standard CNMG120408 and degreased, and then heated up to 1350 ° C. under the heating rate condition shown in Table 1. Thereafter, the temperature was raised to 1450 ° C. at a rate of 12.5 ° C./min and held for 1 hour, followed by cooling. Thus, samples 1 to 5 shown in Table 1 were produced.
[0026]
[Table 1]
In Samples 1 and 2 (product of the present invention) shown in Table 1, there was a layer in which the rate of decrease with respect to the inside of Ta, Ti, Nb atoms was small with respect to the rate of decrease with respect to the inside of Zr atoms. The magnitude of the ratio of the layer thickness and the reduction amount of those atoms was measured by WDS. The results are shown in Table 1 in the magnitude of the reduction ratio.
[0028]
Sample 3 shown in Table 1 (product of the present invention) had a layer with a small reduction rate with respect to the inside of Ta, Ti, Nb atoms, and a Co reduction layer with respect to the reduction rate with respect to the inside of Zr atoms. . The magnitude of the ratio of the layer thickness and the reduction amount of those atoms was measured by WDS.
[0029]
Further, in Samples 4 and 5 (conventional products) in Table 1, the rate of decrease with respect to the inside of Ta, Ti, and Nb atoms is larger than the rate of decrease with respect to the inside of Zr atoms.
[0030]
After performing a honing process on the cutting edge ridges of these sintered bodies, a total of 9 μm of Ti nitride and carbonitride in the inner layer and 3 μm of aluminum oxide in the outer layer are formed on the surface of the sintered body by a normal CVD method. A coating layer was formed with a thickness.
[0031]
Using these samples, a chipping resistance test and an abrasion resistance test during cutting were performed under the following conditions. These test results are shown in Table 2.
Chipping resistance test:
Cutting speed 350m / min
Work material FC250
Feed 0.5mm / rev
Cutting depth 2.0mm
Cutting time 2sec
Abrasion resistance test:
Cutting speed 500m / min
Work material FC250
Feed 0.5mm / rev
Cutting depth 2.0mm
Cutting time 1.2min
[0032]
[Table 2]
From the results shown in Table 2, samples (samples Nos. 1, 2, and 3) prepared in a preferable range with layers having a small reduction ratio with respect to the inside of Ta, Ti, Nb atoms with respect to the reduction ratio with respect to the inside of Zr atoms, It can be seen that both the chipping resistance is superior to the samples (Sample Nos. 4 and 5).
[0034]
Moreover, from the result of Table 2, the sample (sample No. 3) including the layer in which Co is decreased with respect to the inside is superior in wear resistance as compared with the other samples (sample No. 2). I understand that.
[0035]
【The invention's effect】
As described above, in the coated cemented carbide member according to claim 1, Zr and one or more kinds of atoms of Ta, Ti, and Nb are reduced in the surface region than in the inner region of the base material. At the same time, the reduction rate of one or more of Ta, Ti, and Nb is smaller than the reduction rate of the Zr atoms, so that a decrease in the heat resistance of the cemented carbide can be minimized.
[0036]
Further, in the coated cemented carbide according to claim 2, since the thickness of the surface region is 5 to 200 μm, the surface layer can sufficiently act as a β-free layer, and the heat resistance of the cutting edge is improved. be able to.
[0037]
Further, in the coated cemented carbide according to claim 3, since the binder phase is reduced in the surface region than in the inner region of the base material, it is possible to prevent the cutting edge temperature from being increased even at a high cutting speed as much as possible. The plastic deformation of the cutting edge can be prevented.
[0038]
Furthermore, according to the method for producing a coated cemented carbide according to claim 4, one or more iron group metals , Zr is essential, and further contains one or more of Ta, Ti and Nb. Table 4a, 5a, 6a When firing a compound containing a compound containing a group 6a metal, the heating rate at 1350 ° C. or lower is 5 ° C./min or lower, and then the temperature is increased at 12.5 ° C./min. Therefore , the composition in the de-β layer is controlled so that the reduction rate of one or more of Ta, Ti and Nb is smaller than the reduction rate of Zr atoms. And a decrease in heat resistance of the cemented carbide can be minimized.
[Brief description of the drawings]
FIG. 1 is a view showing an analysis result of a coated cemented carbide member according to the present invention by a wavelength dispersion type X-ray microanalyzer.
Claims (4)
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| US7977234B2 (en) | 2001-04-17 | 2011-07-12 | Renesas Electronics Corporation | Fabrication method of semiconductor integrated circuit device |
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| JP2009120902A (en) * | 2007-11-14 | 2009-06-04 | Sumitomo Electric Ind Ltd | Laminated structure type cemented carbide, its manufacturing method, and tool made of the cemented carbide |
| JP5561522B2 (en) * | 2010-02-26 | 2014-07-30 | 三菱マテリアル株式会社 | Surface-coated WC-based cemented carbide insert |
| JP5561607B2 (en) * | 2010-09-15 | 2014-07-30 | 三菱マテリアル株式会社 | Surface-coated WC-based cemented carbide insert |
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