JP2004237425A

JP2004237425A - Cutting tool made of surface coated cemented carbide coated with hard coating layer having excellent wear resistance at high cutting speed

Info

Publication number: JP2004237425A
Application number: JP2003031929A
Authority: JP
Inventors: Tetsuhiko Honma; 哲彦本間; Akira Osada; 晃長田; Makoto Nishida; 西田　　真
Original assignee: Mitsubishi Materials Corp
Current assignee: Mitsubishi Materials Corp
Priority date: 2003-02-10
Filing date: 2003-02-10
Publication date: 2004-08-26

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting tool made of surface coated cemented carbide coated with a hard coating layer having excellent wear resistance at a high cutting speed. <P>SOLUTION: The cutting tool made of surface coated cemented carbide has a hard coating layer, which is composed of compound carbonitride layer of Al and Ti and has been deposited by vapor deposition so as to have an overall average layer thickness of 2-20 μm. The hard coating layer is configured so as to have such a concentration distribution of component that the maximum content point of Al and C and the maximum content point of Ti and N exist alternately and repeatedly at required intervals in the direction of the layer thickness, and further the content of Al and C and the content of Ti and N vary continuously between both maximum content points. In addition, the hard coating layer is configured such that the maximum content point of Al and C satisfies the following composition formula, (Al<SB>1-X</SB>Ti<SB>X</SB>)C<SB>1-Y</SB>N<SB>Y</SB>, (where X=0.02 to 0.20, Y=0.02 to 0.20 at atomic ratio), and the maximum content point of Ti and N satisfies the following composition formula, (Ti<SB>1-A</SB>Al<SB>A</SB>)C<SB>1-B</SB>N<SB>B</SB>, (where A=0.30 to 0.50, B=0.30 to 0.50 at atomic ratio), and the distant between both of the neighboring maximum content points is 0.01 to 0.2 μm. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
この発明は、硬質被覆層が高硬度を有し、したがって各種の鋼や鋳鉄などの切削加工を、特に高速切削条件で行なった場合に、硬質被覆層がすぐれた耐摩耗性を発揮する表面被覆超硬合金製切削工具（以下、被覆超硬工具という）に関するものである。
【０００２】
【従来の技術】
一般に、被覆超硬工具には、各種の鋼や鋳鉄などの被削材の旋削加工や平削り加工にバイトの先端部に着脱自在に取り付けて用いられるスローアウエイチップ、穴あけ切削加工などに用いられるドリルやミニチュアドリル、さらに面削加工や溝加工、肩加工などに用いられるソリッドタイプのエンドミルなどがあり、また前記スローアウエイチップを着脱自在に取り付けて前記ソリッドタイプのエンドミルと同様に切削加工を行うスローアウエイエンドミル工具などが知られている。
【０００３】
また、被覆超硬工具として、炭化タングステン（以下、ＷＣで示す）基超硬合金または炭窒化チタン（以下、ＴｉＣＮで示す）基サーメットからなる基体（以下、これらを総称して超硬基体と云う）の表面に、
組成式：（Ｔｉ_１−ＡＡｌ_Ａ）Ｃ_１−ＢＮ_Ｂ、
（ただし、原子比で、Ａ：０．３０〜０．５０、Ｂ：０．３０〜０．５０）
を満足するＴｉとＡｌの複合炭窒化物［以下、（Ｔｉ，Ａｌ）ＣＮで示す］層からなる硬質被覆層を、例えば２〜２０μｍの平均層厚で蒸着してなる被覆超硬工具が提案され、各種の鋼や鋳鉄などの連続切削や断続切削加工に用いた場合にすぐれた切削性能を発揮することも知られている（例えば特許文献１参照）。
【０００４】
さらに、上記の被覆超硬工具が、例えば図１に概略縦断面図で示される通り、中央部にステンレス鋼製の反応ガス吹き出し管が立設され、前記反応ガス吹き出し管には、図２（ａ）に概略斜視図で、同（ｂ）に概略平面図で例示される黒鉛製の超硬基体支持パレットが串刺し積層嵌着され、かつこれらがステンレス鋼製のカバーを介してヒーターで加熱される構造を有する化学蒸着装置を用い、超硬基体を前記超硬基体支持パレットの底面に形成された多数の反応ガス通過穴位置に図示される通りに載置した状態で前記化学蒸着装置に装入し、
反応ガス組成（容量％で）−ＴｉＣｌ_４：０．０４〜２．５％、ＡｌＣｌ_３：０．４〜６％、ＣＨ_４：２〜１０％、Ｎ_２：０．５〜２０％、Ｈ_２：残り、
反応雰囲気温度：１０００〜１０５０℃、
反応雰囲気圧力：１０〜２０ｋＰａ、
の条件で（Ｔｉ，Ａｌ）ＣＮからなる硬質被覆層を形成することにより製造されることも知られている（例えば特許文献１参照）。
【０００５】
【特許文献１】
特開昭６２−５６５６５号公報
【０００６】
【発明が解決しようとする課題】
近年の切削加工装置の高性能化はめざましく、一方で切削加工に対する省力化および省エネ化、さらに低コスト化の要求も強く、これに伴い、切削加工は高速化の傾向にあるが、上記の従来被覆超硬工具においては、これを通常の切削加工条件で用いた場合には問題はないが、特に切削加工を高速切削条件で行なった場合には、硬質被覆層の硬さ不足が原因で、硬質被覆層の摩耗進行が一段と促進するようになることから、比較的短時間で使用寿命に至るのが現状である。
【０００７】
【課題を解決するための手段】
そこで、本発明者等は、上述のような観点から、特に高速切削加工条件で硬質被覆層がすぐれた耐摩耗性を発揮する被覆超硬工具を開発すべく、上記の従来被覆超硬工具を構成する硬質被覆層に着目し、研究を行った結果、
（ａ）上記の図１，２に示される化学蒸着図装置を用いて形成された従来被覆超硬工具を構成する（Ｔｉ，Ａｌ）ＣＮ層は、厚さ全体に亘って実質的に均一な組成を有し、したがって均質な硬さと強度を有するが、（Ｔｉ，Ａｌ）ＣＮ層を形成するに際して、例えば図３に反応ガス組成自動制御システムが概略チャート図で示される通り、反応ガス組成および流量中央制御装置に、前記（Ｔｉ，Ａｌ）ＣＮ層からなる硬質被覆層に層厚方向にそってＡｌおよび炭素の最高含有点とＴｉおよび窒素の最高含有点とを所定間隔をおいて交互に繰り返し形成させる目的で、前記Ａｌおよび炭素の最高含有点並びにＴｉおよび窒素の最高含有点に対応した反応ガス組成、並びに前記両点間のＡｌと炭素の連続変化に対応した反応ガス組成（この場合Ａｌおよび炭素の連続変化に対応してＴｉおよび窒素の含有量も変化することは当然である）、さらに前記両点間の間隔および硬質被覆層の全体層厚を、過去の実績データに基づいてインプットし、この反応ガス組成および流量中央制御装置からの制御信号にしたがって、原料ガスボンベからのＨ_２ガス、ＣＨ_４ガス、Ｎ_２ガス、およびＨＣｌガスの流量、さらにＡｌＣｌ_３ガスおよびＴｉＣｌ_４ガスの流量をそれぞれの原料流量自動制御装置にて制御しながら、化学蒸着装置の反応ガス吹き出し管に導入すると、層厚方向にそって、Ａｌおよび炭素の最高含有点とＴｉおよび窒素の最高含有点とが所定間隔をおいて交互に繰り返し存在し、かつ前記Ａｌおよび炭素の最高含有点から前記Ｔｉおよび窒素の最高含有点、前記Ｔｉおよび窒素の最高含有点から前記Ａｌおよび炭素の最高含有点へＡｌと炭素、並びにＴｉと窒素の含有量が連続的に変化する成分濃度分布構造をもつたＡｌとＴｉの複合炭窒化物［以下、（Ａｌ，Ｔｉ）ＣＮで示す］層からなる硬質被覆層が形成されるようになること。
【０００８】
（ｂ）上記（ａ）の繰り返し連続変化成分濃度分布構造の（Ａｌ，Ｔｉ）ＣＮ層において、
上記Ａｌおよび炭素の最高含有点が、
組成式：（Ａｌ_１−ＸＴｉ_Ｘ）Ｃ_１−ＹＮ_Ｙ、
（ただし、原子比で、Ｘ：０．０２〜０．２０、Ｙ：０．０２〜０．２０）、
上記Ｔｉおよび窒素の最高含有点が、
組成式：（Ｔｉ_１−ＡＡｌ_Ａ）Ｃ_１−ＢＮ_Ｂ、
（ただし、原子比で、Ａ：０．３０〜０．５０、Ｂ：０．３０〜０．５０）
を満足し、かつ隣り合う上記Ａｌおよび炭素の最高含有点と上記Ｔｉおよび窒素の最高含有点の厚さ方向の間隔を０．０１〜０．２μｍとすると、
上記Ａｌおよび炭素の最高含有点部分では、相対的に多量含有のＡｌ成分による高温硬さおよび耐熱性の向上、さらに同炭素成分による硬さの著しい向上が見られ、一方上記Ｔｉおよび窒素の最高含有点部分では、上記の従来（Ｔｉ，Ａｌ）ＣＮ層のもつ硬さと強度に相当する硬さと強度が確保され、かつこれらＡｌおよび炭素の最高含有点と上記Ｔｉおよび窒素の最高含有点の間隔をきわめて小さくしたことから、層全体の特性として前記従来（Ｔｉ，Ａｌ）ＣＮ層に比して、強度は同等で、高温硬さと耐熱性、さらに硬さが一段と向上したものになり、したがって、硬質被覆層がかかる構成の（Ａｌ，Ｔｉ）ＣＮ層からなる被覆超硬工具は、各種の鋼や鋳鉄などの切削加工を、特に高熱発生を伴なう高速切削条件で行なった場合にも、硬質被覆層がすぐれた耐摩耗性を発揮するようになること。
以上（ａ）および（ｂ）に示される研究結果を得たのである。
【０００９】
この発明は、上記の研究結果に基づいてなされたものであって、超硬基体の表面に、（Ａｌ，Ｔｉ）ＣＮ層からなる硬質被覆層を２〜２０μｍの全体平均層厚で蒸着してなる被覆超硬工具において、
上記硬質被覆層が、層厚方向にそって、Ａｌおよび炭素の最高含有点とＴｉおよび窒素の最高含有点とが所定間隔をおいて交互に繰り返し存在し、かつ前記Ａｌおよび炭素の最高含有点から前記Ｔｉおよび窒素の最高含有点、前記Ｔｉおよび窒素の最高含有点から前記Ａｌおよび炭素の最高含有点へＡｌとＴｉの含有量、並びに炭素と窒素の含有量が連続的に変化する成分濃度分布構造を有し、
さらに、上記Ａｌおよび炭素の最高含有点が、
組成式：（Ａｌ_１−ＸＴｉ_Ｘ）Ｃ_１−ＹＮ_Ｙ、
（ただし、原子比で、Ｘ：０．０２〜０．２０、Ｙ：０．０２〜０．２０）、
上記Ｔｉおよび窒素の最高含有点が、
組成式：（Ｔｉ_１−ＡＡｌ_Ａ）Ｃ_１−ＢＮ_Ｂ、
（ただし、原子比で、Ａ：０．３０〜０．５０、Ｂ：０．３０〜０．５０）、
を満足し、かつ隣り合う上記Ａｌおよび炭素の最高含有点と上記Ｔｉおよび窒素の最高含有点の間隔が、０．０１〜０．２μｍである、
高速切削条件で硬質被覆層がすぐれた耐摩耗性を発揮する被覆超硬工具に特徴を有するものである。
【００１０】
つぎに、この発明の被覆超硬工具において、硬質被覆層の構成を上記の通りに限定した理由を説明する。
（ａ）Ａｌおよび炭素の最高含有点
上記の通り硬質被覆層である（Ａｌ，Ｔｉ）ＣＮ層の厚さ方向に沿ってＡｌおよび炭素成分の相対的に高い部分を繰り返し形成して層自体の高温硬さと耐熱性、さらに硬さを一段と向上させ、一方上記の従来（Ｔｉ，Ａｌ）ＣＮ層と同等の組成を有するＴｉおよび炭素の最高含有点部分を繰り返し形成して層自体に強度を確保するものであり、したがって、この結果高速切削での耐摩耗性が前記従来（Ｔｉ，Ａｌ）ＣＮ層に比して著しく向上するようになるが、この場合ＴｉのＡｌとの相対含有割合を示すＸ値が、原子比で（以下同じ）０．０２未満であったり、また同じく窒素の炭素との相対含有割合を示すＹ値が、０．０２未満であったりすると、Ａｌおよび炭素の最高含有点が、実質的にＡｌと炭素で構成されるようになるので、一段とすぐれた高温硬さと耐熱性、さらに硬さを有するようになるが、強度の低下は著しく、高強度を有するＴｉと窒素の最高含有点が隣接して存在しても前記の実質的にＡｌと炭素からなるＡｌおよび炭素の最高含有点部分が破壊の起点となり、切刃部にチッピング（微少欠け）が発生し易くなるのが避けられず、一方同Ｘ値が０．２０を越えたり、また同Ｙ値が同じく０．２０を越えたりすると、高温硬さと耐熱性、さらに硬さが急激に低下し、すぐれた耐摩耗性を期待することができないことから、Ｘ値を０．０２〜０．２０、Ｙ値を０．０２〜０．２０と定めた。
【００１１】
（ｂ）Ｔｉおよび窒素の最高含有点
上記の通りＡｌおよび炭素の最高含有点は相対的にきわめてすぐれた高温硬さと耐熱性、さらに硬さを有するが、反面相対的に強度が不十分であるため、このＡｌおよび炭素の最高含有点の強度不足を補う目的で、上記の従来（Ｔｉ，Ａｌ）ＣＮ層のもつ強度と同等の相対的に高い強度を有するＴｉおよび窒素の最高含有点を厚さ方向に交互に介在させるものである。しかし、ＡｌのＴｉとの相対含有割合を示すＡ値が０．３０未満になったり、窒素の炭素との相対含有割合を示すＢ値が、０．５０を越えたりすると、すぐれた高温硬さと耐熱性、さらに硬さを有するＡｌおよび炭素の最高含有点が隣接して存在しても、層自体の高温硬さと耐熱性、さらに硬さの低下が避けられず、この結果摩耗進行が促進するようになり、一方同Ａ値が０．５０を越えたり、Ｂ値が０．３０未満になったりすると、層自体の強度低下が避けられず、切刃部にチッピング（微少欠け）が発生し易くることから、Ａ値を０．３０〜０．５０、Ｂ値を０．３０〜０．５０と定めた。
【００１２】
（ｃ）Ａｌおよび炭素の最高含有点とＴｉおよび窒素の最高含有点間の間隔
その間隔が０．０１μｍ未満ではそれぞれの点を上記の組成で明確に形成することが困難であり、この結果層に所定の強度を確保した上で、一段と高い高温硬さと耐熱性、さらに硬さを確保することができなくなり、またその間隔が０．２μｍを越えるとそれぞれの点がもつ欠点、すなわちＡｌおよび炭素の最高含有点であれば強度不足、Ｔｉおよび窒素の最高含有点であれば高温硬さおよび耐熱性不足、さらに硬さ不足が層内に局部的に現れ、これが原因でチッピングが発生し易くなったり、摩耗進行が促進されるようになることから、その間隔を０．０１〜０．２μｍと定めた。
【００１３】
（ｄ）硬質被覆層の全体平均層厚
その層厚が２μｍ未満では、所望の耐摩耗性を確保することができず、一方その平均層厚が２０μｍを越えると、チッピングが発生し易くなることから、その平均層厚を２〜２０μｍと定めた。
【００１４】
【発明の実施の形態】
つぎに、この発明の被覆超硬工具を実施例により具体的に説明する。
原料粉末として、平均粒径：６．５μｍを有する粗粒ＷＣ粉末、同３．５μｍを有する中粒ＷＣ粉末、同０．８μｍの微粒ＷＣ粉末、同１．３μｍのＴａＣ粉末、同１．２μｍのＮｂＣ粉末、同１．２μｍのＺｒＣ粉末、同２．３μｍのＣｒ_３Ｃ_２粉末、同１．０μｍの（Ｔｉ，Ｗ）ＣＮ（質量比で、ＴｉＣ／ＴｉＮ／ＷＣ＝２４／２０／５６）粉末、および同１．８μｍのＣｏ粉末を用意し、これら原料粉末をそれぞれ表１に示される配合組成に配合し、ボールミルで７２時間混合し、減圧乾燥した後、１００ＭＰａの圧力で圧粉体にプレス成形し、この圧粉体を、表面部にＣｏ富化層を形成するものについては１３．３Ｐａ、そして全体に亘って均一組織を有するものについては６．７Ｐａの真空中、温度：１４３０℃に１時間保持の条件で焼結し、焼結後、切刃部分にＲ：０．０８のホーニング加工を施してＩＳＯ規格・ＣＮＭＧ１６０６０８のチップ形状をもったＷＣ基超硬合金製の超硬基体Ａ１〜Ａ１０を形成した。なお、超硬基体Ａ−１、Ａ−３、Ａ−４、Ａ−６、Ａ−７、およびＡ−９の表面部にＣｏ富化層の形成が見られた。
【００１５】
また、原料粉末として、いずれも０．５〜２μｍの平均粒径を有するＴｉＣＮ（重量比でＴｉＣ／ＴｉＮ＝５０／５０）粉末、Ｍｏ_２Ｃ粉末、ＺｒＣ粉末、ＮｂＣ粉末、ＴａＣ粉末、ＷＣ粉末、Ｃｏ粉末、およびＮｉ粉末を用意し、これら原料粉末を、表２に示される配合組成に配合し、ボールミルで２４時間湿式混合し、乾燥した後、１００ＭＰａの圧力で圧粉体にプレス成形し、この圧粉体を２ｋＰａの窒素雰囲気中、温度：１５００℃に１時間保持の条件で焼結し、焼結後、切刃部分にＲ：０．１０のホーニング加工を施してＩＳＯ規格・ＣＮＭＧ１６０６１２のチップ形状をもったＡｌＣＮ系サーメット製の超硬基体Ｂ１〜Ｂ６を形成した。
【００１６】
つぎに、上記の超硬基体Ａ１〜Ａ１０およびＢ１〜Ｂ６のそれぞれを、アセトン中で超音波洗浄し、乾燥した後、図１に示される化学蒸着装置内に、第２図に示される超硬基体支持パレットの位置決め穴に載置した状態で装入し、まず、装置内をヒーターで９００℃に加熱したところで、ＴｉＣｌ_４：４．２％、Ｎ_２：３０％、Ｈ_２：残りからなる組成を有する反応ガスを反応ガス吹き出し管を通して導入して、装置内の反応雰囲気圧力を１５ｋＰａとし、この状態で３０分間保持して前記超硬基体表面に、下地密着層として０．３μｍの平均層厚をもった窒化チタン（ＴｉＮ）層を形成し、ついで、同じく装置内の雰囲気温度をヒーターにて加熱して１０２０℃とした後、図３に示される反応ガス組成自動制御システムの反応ガス組成および流量中央制御装置に、過去の実績データにしたがって、表３に示されるＡｌおよび炭素の最高含有点：Ａｌ／Ｃ最高点１〜１０の目標組成、並びに表４に示されるＴｉおよび窒素の最高含有点：Ｔｉ／Ｎ最高点１〜１０の目標組成に対応する反応ガス組成、前記Ａｌおよび炭素の最高含有点とＴｉおよび窒素の最高含有点間のＡｌとＴｉおよび炭素と窒素の含有量の連続変化に対応する反応ガス組成、さらに表４，６に示される前記両点間の目標間隔および硬質被覆層の目標全体層厚をインプットし、この反応ガス組成および流量中央制御装置からの信号にしたがって作動するコントロールバルブ内蔵の原料ガス流量自動制御装置を通して、原料ガスであるＨ_２ガス、Ｎ_２ガス、ＣＨ_４ガス、ＡｌＣｌ_３ガス、およびＴｉＣｌ_４ガス（この場合、前記ＴｉＣｌ_４ガスは図示の通り流量制御されたＨ_２ガスをキャリアガスとしてＴｉＣｌ_４ガス気化器に送り、ここで液体から気化されたＴｉＣｌ_４と共に原料ガス流量自動制御装置に送られ、また前記ＡｌＣｌ_３ガスは、ＡｌＣｌ_３発生器で金属Ａｌと流量制御されたＨＣｌガスを反応させることにより形成される）を、それぞれのガス流量を自動制御しながら、図１の化学蒸着装置の反応ガス吹き出し管から装置内に導入し（装置内の反応雰囲気圧力は常に７ｋＰａに保持される）、もって前記超硬基体の表面に、層厚方向に沿って表３，４に示される目標組成のＡｌおよび炭素の最高含有点と、Ｔｉおよび窒素の最高含有点とが交互に表５，５に示される目標間隔で繰り返し存在し、かつ前記Ａｌおよび炭素の最高含有点から前記Ｔｉおよび窒素の最高含有点、前記Ｔｉおよび窒素の最高含有点から前記Ａｌおよび炭素の最高含有点へＡｌと炭素の含有量、並びにＴｉと窒素の含有量がそれぞれ連続的に変化する成分濃度分布構造を有し、かつ同じく表５，６に示される目標全体層厚の硬質被覆層を蒸着することにより、本発明被覆超硬工具としての本発明表面被覆超硬合金製スローアウエイチップ（以下、本発明被覆超硬チップと云う）１〜１６をそれぞれ製造した。
【００１７】
また、比較の目的で、上記の超硬基体Ａ１〜Ａ１０およびＢ１〜Ｂ６を、アセトン中で超音波洗浄し、乾燥した後、同じくそれぞれ図１，２に示される通常の化学蒸着装置に装入し、上記したＴｉＮ層形成条件と同じ条件で下地密着層として０．３μｍの平均層厚を有するＴｉＮ層を形成し、ついで反応雰囲気温度を１０２０℃に加熱した後、それぞれ表４のＴｉおよび窒素の最高含有点：Ｔｉ／Ｎ最高点１〜１０の目標組成と同じ組成の反応ガスを反応ガス吹き出し管から導入し、反応雰囲気圧力を７ｋＰａに一定とした条件で、前記超硬基体Ａ１〜Ａ１０およびＢ１〜Ｂ６のそれぞれの表面に、表７に示される目標全体層厚を有し、かつ層厚方向に沿って実質的に組成変化のない（Ｔｉ，Ａｌ）ＣＮ層からなる硬質被覆層を蒸着することにより、従来被覆超硬工具としての従来表面被覆超硬合金製スローアウエイチップ（以下、従来被覆超硬チップと云う）１〜１６をそれぞれ製造した。
【００１８】
つぎに、上記本発明被覆超硬チップ１〜１６および従来被覆超硬チップ１〜１６について、これを工具鋼製バイトの先端部に固定治具にてネジ止めした状態で、
被削材：ＪＩＳ・ＳＣＭ４３０の丸棒、
切削速度：４３０ｍ／ｍｉｎ．、
切り込み：２．５ｍｍ、
送り：０．２５ｍｍ／ｒｅｖ．、
切削時間：５分、
の条件での合金鋼の乾式連続高速切削加工試験、
被削材：ＪＩＳ・Ｓ３５Ｃの長さ方向等間隔４本縦溝入り丸棒、
切削速度：３６０ｍ／ｍｉｎ．、
切り込み：２．０ｍｍ、
送り：０．１５ｍｍ／ｒｅｖ．、
切削時間：５分、
の条件での炭素鋼の乾式断続高速切削加工試験、さらに、
被削材：ＪＩＳ・ＦＣ２５０の丸棒、
切削速度：４８０ｍ／ｍｉｎ．、
切り込み：３．０ｍｍ、
送り：０．３０ｍｍ／ｒｅｖ．、
切削時間：５分、
の条件での鋳鉄の乾式連続高速切削加工試験を行い、いずれの切削加工試験でも切刃の逃げ面摩耗幅を測定した。この測定結果を表４〜７に示した。
【００１９】
【表１】

【００２０】
【表２】

【００２１】
【表３】

【００２２】
【表４】

【００２３】
【表５】

【００２４】
【表６】

【００２５】
【表７】

【００２６】
この結果得られた本発明被覆超硬チップ１〜１６および従来被覆超硬チップ１〜１６を構成する硬質被覆層について、厚さ方向に沿ってＡｌ、Ｔｉ、炭素、および窒素の含有量をオージェ分光分析装置を用いて測定しところ、本発明被覆超硬チップ１〜１６の硬質被覆層では、Ａｌおよび炭素の最高含有点と、Ｔｉおよび窒素の最高含有点とがそれぞれ目標値と実質的に同じ組成および間隔で交互に繰り返し存在し、かつＡｌおよび炭素の最高含有点からＴｉおよび窒素の最高含有点、前記Ｔｉおよび窒素の最高含有点からＡｌおよび炭素の最高含有点へＡｌと炭素の含有量、並びにＴｉと窒素の含有量がそれぞれ連続的に変化する成分濃度分布構造を有することも確認され、また、硬質被覆層の全体平均層厚も目標全体層厚と実質的に同じ値を示した。一方前記従来被覆超硬チップ１〜１６の硬質被覆層では厚さ方向に沿って組成変化が見られず、かつ目標組成と実質的に同じ組成および目標全体層厚と実質的に同じ全体平均層厚を示すことが確認された。
【００２７】
【発明の効果】
表３〜７に示される結果から、硬質被覆層が層厚方向に、相対的に一段と高い高温硬さと耐熱性、さらに硬さを有するＡｌおよび炭素の最高含有点と上記の従来（Ｔｉ，Ａｌ）ＣＮ層のもつ強度に相当する相対的に高い強度を有するＴｉおよび窒素の最高含有点とが交互に所定間隔をおいて繰り返し存在し、かつ前記Ａｌおよび炭素の最高含有点から前記Ｔｉおよび窒素の最高含有点、前記Ｔｉおよび窒素の最高含有点から前記Ａｌおよび炭素の最高含有点へＡｌと炭素の含有量、並びにＴｉと窒素の含有量がそれぞれ連続的に変化する成分濃度分布構造を有する本発明被覆超硬チップ１〜１６は、いずれも各種の鋼や鋳鉄などの切削加工を、高速切削条件で行なった場合にも、硬質被覆層がすぐれた耐摩耗性を発揮するのに対して、硬質被覆層が層厚方向に沿って実質的に組成変化のない従来被覆超硬チップ１〜１６においては、特に高速切削条件では高温硬さと耐熱性不足、さらに硬さ不足が原因で摩耗の進行がきわめて速くなり、比較的短時間で使用寿命に至ることが明らかである。
上述のように、この発明の被覆超硬工具は、通常の条件での切削加工は勿論のこと、特に各種の鋼や鋳鉄などの切削加工を、高速で行なった場合にも、すぐれた耐摩耗性を発揮し、長期に亘ってすぐれた切削性能を示すものであるから、切削加工の省力化および省エネ化、さらに低コスト化に十分満足に対応できるものである。
【図面の簡単な説明】
【図１】被覆超硬工具を構成する硬質被覆層を形成するのに用いられている化学蒸着装置を例示する概略縦断面図である。
【図２】化学蒸着装置の構造部材である超硬基体支持パレットを示し、（ａ）が概略斜視図、（ｂ）が概略平面図である。
【図３】この発明の被覆超硬工具を構成する硬質被覆層の形成に用いられる反応ガス組成自動制御システムの概略チャート図である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a surface coating in which the hard coating layer has high hardness, and therefore, the hard coating layer exhibits excellent wear resistance when cutting various kinds of steel and cast iron, particularly when high-speed cutting conditions are performed. The present invention relates to a cemented carbide cutting tool (hereinafter referred to as a coated cemented carbide tool).
[0002]
[Prior art]
In general, coated carbide tools are used for turning or flat cutting of various materials such as steel and cast iron. There are solid type end mills used for drilling and miniature drills, as well as for face milling, grooving, shoulder processing, etc., and also performs cutting in the same manner as the solid type end mill by detachably attaching the throw-away tip. A throw-away end mill tool and the like are known.
[0003]
Further, as a coated cemented carbide tool, a substrate made of tungsten carbide (hereinafter, referred to as WC) -based cemented carbide or titanium carbonitride (hereinafter, referred to as TiCN) -based cermet (hereinafter, these are collectively referred to as a cemented carbide substrate) ) On the surface,
_{_{_{Formula: (Ti 1-A Al A}}} ) C 1-B N B,
(However, in atomic ratio, A: 0.30 to 0.50, B: 0.30 to 0.50)
Coated carbide tools formed by evaporating a hard coating layer composed of a composite carbonitride of Ti and Al [hereinafter, referred to as (Ti, Al) CN] with an average layer thickness of 2 to 20 μm satisfying It is also known that when used for continuous cutting or intermittent cutting of various kinds of steel or cast iron, excellent cutting performance is exhibited (for example, see Patent Document 1).
[0004]
Further, as shown in the schematic vertical sectional view of FIG. 1, for example, the above coated carbide tool is provided with a reaction gas blowing pipe made of stainless steel at the center thereof, and the reaction gas blowing pipe is provided with a reaction gas blowing pipe shown in FIG. Graphite carbide substrate support pallets exemplified in a schematic perspective view in a) and a schematic plan view in b) are skewered, stacked and fitted, and heated by a heater via a stainless steel cover. Using a chemical vapor deposition apparatus having a structure as shown in the figure, the cemented carbide substrate is mounted on the chemical vapor deposition apparatus in a state where it is placed as shown in a number of reaction gas passage holes formed on the bottom surface of the cemented carbide support pallet. Enter
Reaction gas composition (by _{_{_{volume%) -TiCl 4: 0.04~2.5%,}}} AlCl 3: 0.4~6%, CH 4: 2~10%, N 2: 0.5~20%, H ₂ : Rest,
Reaction atmosphere temperature: 1000 to 1050 ° C,
Reaction atmosphere pressure: 10 to 20 kPa,
It is also known that the device is manufactured by forming a hard coating layer made of (Ti, Al) CN under the following conditions (for example, see Patent Document 1).
[0005]
[Patent Document 1]
JP-A-62-56565
[Problems to be solved by the invention]
In recent years, the performance of cutting equipment has been remarkably improved, and on the other hand, there is a strong demand for labor saving, energy saving, and lower cost for the cutting work. In coated carbide tools, there is no problem when using this under normal cutting conditions, but especially when cutting is performed under high-speed cutting conditions, due to insufficient hardness of the hard coating layer, Since the progress of abrasion of the hard coating layer is further accelerated, the service life of the hard coating layer can be reached in a relatively short time at present.
[0007]
[Means for Solving the Problems]
In view of the above, the present inventors have developed the above-mentioned conventional coated carbide tool in order to develop a coated carbide tool in which the hard coating layer exhibits excellent wear resistance particularly under high-speed cutting conditions. As a result of conducting research, focusing on the constituent hard coating layer,
(A) The (Ti, Al) CN layer constituting the conventional coated carbide tool formed by using the chemical vapor deposition apparatus shown in FIGS. 1 and 2 is substantially uniform throughout its thickness. Although having a composition and thus a uniform hardness and strength, in forming the (Ti, Al) CN layer, for example, the reaction gas composition automatic control system shown in FIG. In the flow rate central controller, the highest content points of Al and carbon and the highest content points of Ti and nitrogen are alternately arranged at predetermined intervals on the hard coating layer composed of the (Ti, Al) CN layer in the thickness direction. For the purpose of repeated formation, the reaction gas composition corresponding to the highest content points of Al and carbon, the highest content point of Ti and nitrogen, and the reaction gas composition corresponding to the continuous change of Al and carbon between the two points (in this case, A Naturally, the contents of Ti and nitrogen also change in accordance with the continuous change of carbon), and the distance between the two points and the total thickness of the hard coating layer are input based on past actual data. According to the control signal from the reaction gas composition and flow rate central controller, the flow rates of H ₂ gas, CH ₄ gas, N ₂ gas, and HCl gas, and the flow rates of AlCl ₃ gas and TiCl ₄ gas from the raw material gas cylinder Is introduced into the reaction gas blow-out pipe of the chemical vapor deposition apparatus while controlling the respective raw material flow automatic controllers, the highest content points of Al and carbon and the highest content points of Ti and nitrogen along the layer thickness direction. Present alternately at predetermined intervals, and from the highest content point of the Al and carbon to the highest content point of the Ti and nitrogen, A composite carbonitride of Al and Ti having a component concentration distribution structure in which the contents of Al and carbon, and Ti and nitrogen continuously change from the highest content point to the highest content point of Al and carbon [hereinafter, (Al , Ti) CN] to form a hard coating layer.
[0008]
(B) In the (Al, Ti) CN layer having the above-mentioned (a) repeated and continuously changing component concentration distribution structure,
The highest content points of Al and carbon are
Composition _{_{_{formula: (Al 1-X Ti X}}} ) C 1-Y N Y,
(However, in atomic ratio, X: 0.02 to 0.20, Y: 0.02 to 0.20),
The maximum content of Ti and nitrogen is
_{_{_{Formula: (Ti 1-A Al A}}} ) C 1-B N B,
(However, in atomic ratio, A: 0.30 to 0.50, B: 0.30 to 0.50)
And the distance in the thickness direction between the adjacent highest content points of Al and carbon and the highest content points of Ti and nitrogen is 0.01 to 0.2 μm,
At the highest content points of Al and carbon, improvement in high-temperature hardness and heat resistance due to a relatively large amount of Al component and further remarkable improvement in hardness due to the same carbon component are observed. In the content point portion, hardness and strength corresponding to the hardness and strength of the conventional (Ti, Al) CN layer are secured, and the interval between the highest content point of Al and carbon and the highest content point of Ti and nitrogen is determined. Is extremely small, so that the properties of the whole layer are the same as those of the conventional (Ti, Al) CN layer, and the hardness is high, the high-temperature hardness and heat resistance, and the hardness are further improved. The coated carbide tool composed of the (Al, Ti) CN layer having such a hard coating layer can be used for cutting various kinds of steel and cast iron under high-speed cutting conditions accompanied by high heat generation. Hard To become possible to exert wear resistant coating layer is excellent.
The research results shown in (a) and (b) above were obtained.
[0009]
The present invention has been made on the basis of the above research results, and comprises depositing a hard coating layer composed of an (Al, Ti) CN layer on the surface of a superhard substrate with a total average layer thickness of 2 to 20 μm. Coated carbide tools,
In the hard coating layer, the highest content points of Al and carbon and the highest content points of Ti and nitrogen are alternately present at predetermined intervals along the layer thickness direction, and the highest content points of Al and carbon are present. From the highest content point of Ti and nitrogen, the content of Al and Ti from the highest content point of Ti and nitrogen to the highest content point of Al and carbon, and the component concentration at which the content of carbon and nitrogen continuously changes Has a distribution structure,
Furthermore, the highest content points of Al and carbon are
Composition _{_{_{formula: (Al 1-X Ti X}}} ) C 1-Y N Y,
(However, in atomic ratio, X: 0.02 to 0.20, Y: 0.02 to 0.20),
The maximum content of Ti and nitrogen is
_{_{_{Formula: (Ti 1-A Al A}}} ) C 1-B N B,
(However, in atomic ratio, A: 0.30 to 0.50, B: 0.30 to 0.50),
And the interval between the adjacent highest content points of Al and carbon and the highest content points of Ti and nitrogen is 0.01 to 0.2 μm,
The present invention is characterized by a coated carbide tool in which a hard coating layer exhibits excellent wear resistance under high-speed cutting conditions.
[0010]
Next, the reason why the configuration of the hard coating layer is limited as described above in the coated cemented carbide tool of the present invention will be described.
(A) Maximum content of Al and carbon As described above, a relatively high portion of the Al and carbon components is repeatedly formed along the thickness direction of the (Al, Ti) CN layer, which is a hard coating layer, to form the layer itself. High temperature hardness, heat resistance, and hardness are further improved, while strength of the layer itself is secured by repeatedly forming the highest content portions of Ti and carbon having the same composition as the above conventional (Ti, Al) CN layer. Therefore, as a result, the wear resistance in high-speed cutting is remarkably improved as compared with the conventional (Ti, Al) CN layer. In this case, the relative content ratio of Ti to Al is shown. When the X value is less than 0.02 in atomic ratio (the same applies hereinafter) or the Y value indicating the relative content ratio of nitrogen to carbon is less than 0.02, the maximum content of Al and carbon is reduced. The point is substantially Al and carbon Since it is constituted, it has higher temperature hardness and heat resistance, and further hardness, but the strength is significantly reduced, and the highest content points of Ti and nitrogen having high strength are present adjacently. However, the highest content point of Al and carbon substantially consisting of Al and carbon is a starting point of fracture, and it is inevitable that chipping (small chipping) easily occurs in the cutting edge portion. If the value exceeds 0.20, or if the Y value also exceeds 0.20, the high-temperature hardness and heat resistance, as well as the hardness, rapidly decrease, and it is not possible to expect excellent wear resistance. , X value was set to 0.02 to 0.20, and Y value was set to 0.02 to 0.20.
[0011]
(B) The highest content points of Ti and nitrogen As described above, the highest content points of Al and carbon have relatively excellent high-temperature hardness, heat resistance, and hardness, but have relatively insufficient strength. Therefore, in order to compensate for the lack of strength at the highest content points of Al and carbon, the highest content points of Ti and nitrogen having relatively high strength equivalent to the strength of the above-mentioned conventional (Ti, Al) CN layer are increased. It is interposed alternately in the vertical direction. However, when the A value indicating the relative content ratio of Al to Ti is less than 0.30 or the B value indicating the relative content ratio of nitrogen to carbon exceeds 0.50, excellent high-temperature hardness is obtained. Even if the highest content points of heat resistance and hardness of Al and carbon are present adjacent to each other, a decrease in the high-temperature hardness and heat resistance of the layer itself, and further decrease in hardness are inevitable, and as a result, the progress of wear is accelerated. On the other hand, when the A value exceeds 0.50 or the B value becomes less than 0.30, the strength of the layer itself is inevitably reduced, and chipping (small chipping) occurs at the cutting edge. For ease, the A value was set to 0.30 to 0.50 and the B value was set to 0.30 to 0.50.
[0012]
(C) Spacing between the highest content points of Al and carbon and the highest content points of Ti and nitrogen If the spacing is less than 0.01 μm, it is difficult to clearly form each point with the above composition. In addition, it is not possible to ensure higher high-temperature hardness and heat resistance and further hardness after securing a predetermined strength, and when the interval exceeds 0.2 μm, the disadvantages of each point, namely, Al and carbon At the highest content point, insufficient high-temperature hardness and heat resistance at the highest content point of Ti and nitrogen, and insufficient hardness appear locally in the layer, thereby causing chipping easily. In addition, the interval is set to 0.01 to 0.2 μm because the wear and the progress of wear are promoted.
[0013]
(D) If the average thickness of the hard coating layer is less than 2 μm, the desired wear resistance cannot be ensured. On the other hand, if the average thickness exceeds 20 μm, chipping is likely to occur. Therefore, the average layer thickness was determined to be 2 to 20 μm.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, the coated cemented carbide tool of the present invention will be specifically described with reference to examples.
As raw material powders, coarse WC powder having an average particle size of 6.5 μm, medium WC powder having an average particle size of 3.5 μm, fine WC powder having an average particle size of 0.8 μm, TaC powder having an average particle size of 1.3 μm, and 1.2 μm NbC powder, 1.2 μm ZrC powder, 2.3 μm Cr ₃ C ₂ powder, 1.0 μm (Ti, W) CN (TiC / TiN / WC = 24/20/56 by mass ratio) ) Powder and Co powder of 1.8 μm were prepared, and each of these raw material powders was blended to the composition shown in Table 1, mixed with a ball mill for 72 hours, dried under reduced pressure, and then compacted at a pressure of 100 MPa. This compact is press-formed in a vacuum of 13.3 Pa for those forming a Co-enriched layer on the surface and 6.7 Pa for those having a uniform structure over the entire surface at a temperature of 1430. At 1 ° C for 1 hour After sintering, after sintering, the cutting edge portion was subjected to a honing process of R: 0.08 to form cemented carbide substrates A1 to A10 made of a WC-based cemented carbide having a tip shape of ISO standard CNMG160608. Note that formation of a Co-enriched layer was observed on the surface portions of the carbide substrates A-1, A-3, A-4, A-6, A-7, and A-9.
[0015]
Further, as raw material powder, TiCN (TiC / TiN = 50/50 by weight) powder, Mo ₂ C powder, ZrC powder, NbC powder, TaC powder, WC powder each having an average particle diameter of 0.5 to 2 μm , Co powder, and Ni powder were prepared, and these raw material powders were blended in the composition shown in Table 2, wet-mixed in a ball mill for 24 hours, dried, and then pressed into a green compact at a pressure of 100 MPa. This green compact was sintered in a nitrogen atmosphere of 2 kPa at a temperature of 1500 ° C. for one hour, and after sintering, the cutting edge portion was subjected to honing processing with an R of 0.10 to conform to ISO standard CNMG160612. Carbide bases B1 to B6 made of AlCN-based cermet having the chip shape described above were formed.
[0016]
Next, each of the above-mentioned super-hard substrates A1 to A10 and B1 to B6 is subjected to ultrasonic cleaning in acetone, dried, and then placed in a chemical vapor deposition apparatus shown in FIG. It was loaded while being placed in the positioning holes of the substrate supporting pallet. First, when the inside of the apparatus was heated to 900 ° C. with a heater, TiCl ₄ : 4.2%, N ₂ : 30%, and H ₂ : remainder. A reaction gas having a composition is introduced through a reaction gas blowing pipe, the reaction atmosphere pressure in the apparatus is set to 15 kPa, and this state is maintained for 30 minutes. After forming a thick titanium nitride (TiN) layer and then heating the atmosphere in the apparatus to 1020 ° C. with a heater, the reaction gas composition of the reaction gas composition automatic control system shown in FIG. According to the past performance data, the maximum content of Al and carbon shown in Table 3: the target composition of Al / C maximum points 1 to 10 and the maximum composition of Ti and nitrogen shown in Table 4 Content point: the reaction gas composition corresponding to the target composition of Ti / N maximum points 1 to 10, the content of Al and Ti and the content of carbon and nitrogen between the maximum content points of Al and carbon and the maximum content points of Ti and nitrogen. The reaction gas composition corresponding to the continuous change, and the target distance between the two points and the target total layer thickness of the hard coating layer shown in Tables 4 and 6 are input. Thus through the raw material gas flow automatic control of the control valve built to operate, _{H 2} gas as a source gas, _{N 2} gas, CH ₄ gas, AlCl ₃ gas and TiCl ₄ gas In this case, the TiCl ₄ gas is sent through the flow controlled H ₂ gas shown feeding into the TiCl ₄ gas vaporizer as a carrier gas, wherein the raw material gas flow automatic control device with TiCl ₄ which has been vaporized from the liquid, The AlCl ₃ gas is formed by reacting a metal Al with a HCl gas whose flow rate is controlled by an AlCl ₃ generator. The reaction of the chemical vapor deposition apparatus of FIG. The gas was introduced into the apparatus through a gas blow-out pipe (the pressure of the reaction atmosphere in the apparatus was always maintained at 7 kPa), and the target composition shown in Tables 3 and 4 was applied to the surface of the cemented carbide substrate along the layer thickness direction. The highest content points of Al and carbon and the highest content points of Ti and nitrogen are alternately present at target intervals shown in Tables 5 and 5; From the point, the highest content points of Ti and nitrogen, the highest content points of Ti and nitrogen to the highest content points of Al and carbon, the content of Al and carbon, and the content of Ti and nitrogen continuously change, respectively. By depositing a hard coating layer having a component concentration distribution structure and also having a target overall layer thickness also shown in Tables 5 and 6, the surface coated cemented carbide alloy throw-away tip as the coated carbide tool of the present invention (Hereinafter referred to as coated carbide tips of the present invention) 1 to 16 were produced.
[0017]
For the purpose of comparison, the above-mentioned super-hard substrates A1 to A10 and B1 to B6 were ultrasonically cleaned in acetone, dried, and then loaded into a normal chemical vapor deposition apparatus also shown in FIGS. Then, a TiN layer having an average thickness of 0.3 μm was formed as a base adhesion layer under the same conditions as the TiN layer formation conditions described above, and then the reaction atmosphere was heated to a temperature of 1020 ° C. The highest content point of Ti: N: a reactive gas having the same composition as the target composition of the highest points 1 to 10 is introduced from a reaction gas blow-out pipe, and the pressure of the reaction atmosphere is kept constant at 7 kPa. And a hard coating layer composed of a (Ti, Al) CN layer having a target total layer thickness shown in Table 7 and having substantially no composition change along the layer thickness direction on each surface of B1 to B6. Depositing More conventional coating conventional surface-coated cemented carbide indexable as cemented carbide (hereinafter, conventional coating called carbide inserts) were 1-16 were prepared, respectively.
[0018]
Next, with respect to the above-mentioned coated carbide tips 1 to 16 of the present invention and conventional coated carbide tips 1 to 16, in a state where they were screwed to the tip of a tool steel tool with a fixing jig,
Work material: JIS SCM430 round bar,
Cutting speed: 430 m / min. ,
Cut: 2.5mm,
Feed: 0.25 mm / rev. ,
Cutting time: 5 minutes,
Dry continuous high-speed cutting test of alloy steel under the conditions of
Work material: JIS S35C lengthwise round bar with 4 equally spaced longitudinal grooves,
Cutting speed: 360 m / min. ,
Notch: 2.0 mm,
Feed: 0.15 mm / rev. ,
Cutting time: 5 minutes,
Intermittent high-speed cutting test of carbon steel under the following conditions,
Work material: JIS FC250 round bar,
Cutting speed: 480 m / min. ,
Cut: 3.0 mm,
Feed: 0.30 mm / rev. ,
Cutting time: 5 minutes,
The dry continuous high-speed cutting test of the cast iron was performed under the following conditions, and the flank wear width of the cutting edge was measured in each cutting test. The measurement results are shown in Tables 4 to 7.
[0019]
[Table 1]

[0020]
[Table 2]

[0021]
[Table 3]

[0022]
[Table 4]

[0023]
[Table 5]

[0024]
[Table 6]

[0025]
[Table 7]

[0026]
For the hard coating layers constituting the coated carbide tips 1 to 16 of the present invention and the conventional coated carbide tips 1 to 16 obtained as a result, the contents of Al, Ti, carbon, and nitrogen along the thickness direction were determined by Auger. When measured using a spectroscopic analyzer, in the hard coating layers of the coated superhard tips 1 to 16 of the present invention, the highest content points of Al and carbon, and the highest content points of Ti and nitrogen are substantially the target values, respectively. Al and carbon which are present alternately and repeatedly with the same composition and interval, and from the highest content of Al and carbon to the highest content of Ti and nitrogen, from the highest content of Ti and nitrogen to the highest content of Al and carbon It has also been confirmed that the hard coating layer has a component concentration distribution structure in which the amount and the content of Ti and nitrogen are continuously changed, and the overall average layer thickness of the hard coating layer is substantially the same as the target overall layer thickness. It is shown. On the other hand, in the hard coating layers of the conventional coated carbide tips 1 to 16, no composition change is observed along the thickness direction, and the composition is substantially the same as the target composition and the overall average layer is substantially the same as the target total layer thickness. It was confirmed that the film showed a thickness.
[0027]
【The invention's effect】
From the results shown in Tables 3 to 7, it can be seen from the results shown in Tables 3 to 7 that the hard coating layer has relatively higher high-temperature hardness and heat resistance in the layer thickness direction, and the highest content points of Al and carbon having higher hardness and the above conventional (Ti, Al). ) The highest content points of Ti and nitrogen having a relatively high strength corresponding to the strength of the CN layer are alternately and repeatedly present at a predetermined interval, and the highest content points of Al and carbon are used to determine the highest content points of Ti and nitrogen. Has a component concentration distribution structure in which the contents of Al and carbon, and the contents of Ti and nitrogen continuously change from the highest content point of Ti and nitrogen to the highest content point of Al and carbon, respectively. The coated carbide tips 1 to 16 of the present invention are characterized in that the hard coating layer exhibits excellent wear resistance even when cutting various kinds of steel or cast iron under high-speed cutting conditions. , Hard coat In the conventional coated carbide tips 1 to 16 in which the layer does not substantially change in composition along the layer thickness direction, particularly under high-speed cutting conditions, high temperature hardness and insufficient heat resistance, and further wear progression is extremely caused by insufficient hardness. It is evident that it is faster and has a shorter service life in a relatively short time.
As described above, the coated cemented carbide tool of the present invention has excellent wear resistance, not only when cutting under normal conditions, but especially when cutting various kinds of steel and cast iron at a high speed. Since it exhibits excellent cutting performance over a long period of time, it can sufficiently cope with labor saving and energy saving of the cutting process, and furthermore, cost reduction.
[Brief description of the drawings]
FIG. 1 is a schematic longitudinal sectional view illustrating a chemical vapor deposition apparatus used for forming a hard coating layer constituting a coated carbide tool.
FIGS. 2A and 2B show a super hard substrate supporting pallet as a structural member of the chemical vapor deposition apparatus, wherein FIG. 2A is a schematic perspective view and FIG.
FIG. 3 is a schematic chart of a reaction gas composition automatic control system used for forming a hard coating layer constituting the coated carbide tool of the present invention.

Claims

A surface-coated cemented carbide obtained by depositing a hard coating layer composed of a composite carbonitride layer of Al and Ti on the surface of a tungsten carbide-based cemented carbide substrate or a titanium carbonitride-based cermet substrate with a total average layer thickness of 2 to 20 μm. In cutting tools made of alloy,
In the hard coating layer, the highest content points of Al and carbon and the highest content points of Ti and nitrogen are alternately present at predetermined intervals along the layer thickness direction, and the highest content points of the Al and carbon are present. From the highest content point of Ti and nitrogen, the content of Al and Ti from the highest content point of Ti and nitrogen to the highest content point of Al and carbon, and the component concentration at which the content of carbon and nitrogen continuously changes Has a distribution structure,
Furthermore, the highest content points of Al and carbon are
Composition _{_{_{formula: (Al 1-X Ti X}}} ) C 1-Y N Y,
(However, in atomic ratio, X: 0.02 to 0.20, Y: 0.02 to 0.20),
The maximum content of Ti and nitrogen is
_{_{_{Formula: (Ti 1-A Al A}}} ) C 1-B N B,
(However, in atomic ratio, A: 0.30 to 0.50, B: 0.30 to 0.50)
And the interval between the adjacent highest content points of Al and carbon and the highest content points of Ti and nitrogen is 0.01 to 0.2 μm,
Surface coated cemented carbide cutting tool with a hard coating layer that exhibits excellent wear resistance under high speed cutting conditions.