JP2005007503A

JP2005007503A - Cutting tool made of surface covered cubic crystal boron nitride group sintered material with hard covered layer exhibiting excellent chipping resistance in heavy cutting work

Info

Publication number: JP2005007503A
Application number: JP2003172763A
Authority: JP
Inventors: Keiji Nakamura; 惠滋中村; Itsuro Tajima; 逸郎田嶋; Hidemitsu Takaoka; 秀充高岡
Original assignee: Mitsubishi Materials Corp; Mitsubishi Materials Kobe Tools Corp
Current assignee: Mitsubishi Materials Corp; Mitsubishi Materials Kobe Tools Corp
Priority date: 2003-06-18
Filing date: 2003-06-18
Publication date: 2005-01-13
Anticipated expiration: 2023-06-18
Also published as: JP4284506B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting tool a hard covered layer of which exhibits excellent chipping resistance in heavy cutting work. <P>SOLUTION: In the cutting tool, the composite nitride hard covered layer of Ti, Al and Y is physically deposited in 0.5 to 10 μm average layer thickness on a surface of a cubic crystal boron nitride group sintered material base substance, Al maximum including points and Al minimum including points are made to repeatedly exist with specified intervals along the layer thickness direction on the hard covered layer, the hard covered layer has a component concentration distribution structure in which Ti and Al including ratios respectively and continuously change to the Al minimum including point from the Al maximum including point and to the Al maximum including point from the Al minimum including point, and it is characterised in that the Al maximum including point satisfies a composition formula: [Ti<SB>1-(E+Z)</SB>Al<SB>E</SB>Y<SB>Z</SB>]N (E shows 0.45 to 0.65, Z shows 0.002 to 0.10 in atomic ratio) and the Al minimum including point satisfies a composition formula: [Ti<SB>1-(F+Z)</SB>Al<SB>F</SB>Y<SB>Z</SB>]N (F shows 0.10 to 0.35, Z shows 0.002 to 0.10 in atomic ratio), and an interval between the adjacent Al maximum including point and Al minimum including point is made 0.01 to 0.1 μm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
この発明は、硬質被覆層がすぐれた高温強度および耐熱塑性変形性を有し、かつ高温硬さと耐熱性にもすぐれ、したがって特に各種の鋼や鋳鉄などの切削加工を、高い機械的熱的衝撃を伴う高切り込みや高送りなどの重切削条件で行なった場合にも、硬質被覆層がすぐれた耐チッピング性を発揮する表面被覆立方晶窒化硼素基焼結材料製切削工具（以下、被覆ＢＮ基工具という）に関するものである。
【０００２】
【従来の技術】
一般に、被覆ＢＮ基工具には、各種の鋼や鋳鉄などの被削材の旋削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や、前記スローアウエイチップを着脱自在に取り付けて、面削加工や溝加工、さらに肩加工などに用いられる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などが知られている。
【０００３】
また、被覆ＢＮ基工具として、すぐれた高温硬さおよび耐熱性を具備する反面、高温強度の低いものであるために、切削速度は高いが、切り込みや送りを著しく小さくした条件の高速表面仕上げ加工にしか用いられていなかった立方晶窒化硼素基焼結材料からなる切削工具を基体（以下、ＢＮ基基体という）とし、このＢＮ基基体の表面に、切削工具自体の強度向上を図る目的で、
組成式：（Ｔｉ_１−ＥＡｌ_Ｅ）Ｎ（ただし、原子比で、Ｅは０．４５〜０．６５を示す）、
を満足するＴｉとＡｌの複合窒化物［以下、（Ｔｉ，Ａｌ）Ｎで示す］からなる硬質被覆層を０．５〜１０μｍの平均層厚で物理蒸着して、通常の条件での切り込みや送りで各種の鋼や鋳鉄などの連続切削加工や断続切削加工を行なっても、切刃部に欠けやチッピング（微小欠け）などが発生しないようにした被覆ＢＮ基工具が知られている（例えば特許文献１参照）。
【０００４】
さらに、上記の被覆ＢＮ基工具が、例えば図２に概略説明図で示される物理蒸着装置の１種であるアークイオンプレーティング装置に上記のＢＮ基基体を装入し、ヒータで装置内を、例えば５０５℃の温度に加熱した状態で、アノード電極と所定組成を有するＴｉ−Ａｌ合金がセットされたカソード電極（蒸発源）との間に、例えば電流：１４５Ａの条件でアーク放電を発生させ、同時に装置内に反応ガスとして窒素ガスを導入して、例えば２Ｐａの反応雰囲気とし、一方上記ＢＮ基基体には、例えば−９５Ｖのバイアス電圧を印加した条件で、前記ＢＮ基基体の表面に、上記（Ｔｉ，Ａｌ）Ｎ層からなる硬質被覆層を蒸着することにより製造されることも知られている。
【０００５】
【特許文献１】
特開平８−１１９７７４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は強く、これに伴い、切削加工は高速で、かつ高切り込みや高送りなどの重切削条件で行なわれる傾向にあるが、上記の従来被覆ＢＮ基工具においては、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、切削加工を、高い機械的熱的衝撃を伴なう高切り込みや高送りなどの重切削条件で行なった場合には、特に硬質被覆層の高温強度不足が原因で切刃部にチッピング（微小割れ）が発生し易くなることから、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、特に鋼や鋳鉄などの重切削加工で硬質被覆層がすぐれた耐チッピング性を発揮する被覆ＢＮ基工具を開発すべく、上記の従来被覆ＢＮ基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２に示されるアークイオンプレーティング装置を用いて形成された従来被覆ＢＮ基工具の硬質被覆層を構成する（Ｔｉ，Ａｌ）Ｎ層は、層厚全体に亘って実質的に均一な組成を有し、したがって均質な高温硬さと耐熱性、および高温強度を有するが、例えば図１（ａ）に概略平面図で、同（ｂ）に概略正面図で示される構造のアークイオンプレーティング装置、すなわち装置中央部にＢＮ基基体装着用回転テーブルを設け、前記回転テーブルを挟んで、一方側に相対的にＡｌ含有割合の高いＴｉ−Ａｌ−Ｙ合金、他方側に相対的にＡｌ含有割合の低いＴｉ−Ａｌ−Ｙ合金をカソード電極（蒸発源）として対向配置したアークイオンプレーティング装置を用い、この装置の前記回転テーブル上の中心軸から半径方向に所定距離離れた位置に、外周部に沿って複数のＢＮ基基体をリング状に装着し、この状態で装置内雰囲気を窒素雰囲気として前記回転テーブルを回転させると共に、蒸着形成される硬質被覆層の層厚均一化を図る目的でＢＮ基基体自体も自転させながら、前記の両側のカソード電極（蒸発源）とアノード電極との間にアーク放電を発生させて、前記ＢＮ基基体の表面にＴｉとＡｌとＹの複合窒化物［以下、（Ｔｉ，Ａｌ，Ｙ）Ｎで示す］からなる硬質被覆層を形成すると、この結果の（Ｔｉ，Ａｌ，Ｙ）Ｎ層においては、回転テーブル上にリング状に配置された前記ＢＮ基基体が上記の一方側の相対的にＡｌ含有割合の高いＴｉ−Ａｌ−Ｙ合金のカソード電極（蒸発源）に最も接近した時点で層中にＡｌ最高含有点が形成され、また前記ＢＮ基基体が上記の他方側の相対的にＡｌ含有割合の低いＴｉ−Ａｌ−Ｙ合金のカソード電極に最も接近した時点で層中にＡｌ最低含有点が形成され、上記回転テーブルの回転によって層中には層厚方向にそって前記Ａｌ最高含有点とＡｌ最低含有点が所定間隔をもって交互に繰り返し現れると共に、前記Ａｌ最高含有点から前記Ａｌ最低含有点、前記Ａｌ最低含有点から前記Ａｌ最高含有点へＴｉおよびＡｌの含有割合がそれぞれ連続的に変化する成分濃度分布構造をもつようになること。
【０００８】
（ｂ）上記（ａ）の繰り返し連続変化成分濃度分布構造の（Ｔｉ，Ａｌ，Ｙ）Ｎ層において、例えば対向配置のカソード電極（蒸発源）のそれぞれの組成を調製すると共に、ＢＮ基基体が装着されている回転テーブルの回転速度を制御して、
上記Ａｌ最高含有点が、
組成式：［Ｔｉ_{１−（Ｅ＋Ｚ）}Ａｌ_ＥＹ_Ｚ］Ｎ（ただし、原子比で、Ｅは０．４５〜０．６５、Ｚは０．００２〜０．１０を示す）、
上記Ａｌ最低含有点が、
組成式：［Ｔｉ_{１−（Ｆ＋Ｚ）}Ａｌ_ＦＹ_Ｚ］Ｎ（ただし、原子比で、Ｆは０．１０〜０．３５、Ｚは０．００２〜０．１０を示す）、
をそれぞれ満足し、かつ隣り合う上記Ａｌ最高含有点とＡｌ最低含有点の厚さ方向の間隔を０．０１〜０．１μｍとすると、
上記Ａｌ最高含有点部分では、上記の従来（Ｔｉ，Ａｌ）Ｎ層のもつ高温硬さおよび耐熱性と同等の高温硬さと耐熱性を有し、一方上記Ａｌ最低含有点部分では、前記Ａｌ最高含有点部分に比してＡｌ含有割合が低く、Ｔｉ含有割合の高いものとなるので、相対的にきわめて高い高温強度が確保され、この場合高Ｔｉ含有によって偏摩耗の原因となる熱塑性変形が発生し易くなるが、共存含有のＹ成分の作用によって、その発生が著しく抑制されるようになり、かつこれらＡｌ最高含有点とＡｌ最低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上記従来（Ｔｉ，Ａｌ）Ｎ層に相当する高温硬さと耐熱性に加えて、これより一段と高い高温強度と耐熱塑性変形性を具備するようになり、したがって、硬質被覆層がかかる構成の（Ｔｉ，Ａｌ，Ｙ）Ｎ層からなる被覆ＢＮ基工具は、特に各種の鋼や鋳鉄などの切削加工を、機械的熱的衝撃の高い高切り込みや高送りなどの重切削条件で行なった場合にも、硬質被覆層がすぐれた耐チッピング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、ＢＮ基基体の表面に、（Ｔｉ，Ａｌ，Ｙ）Ｎからなる硬質被覆層を０．５〜１０μｍの平均層厚で物理蒸着してなる被覆ＢＮ基工具において、
上記硬質被覆層が、層厚方向にそって、Ａｌ最高含有点とＡｌ最低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最高含有点から前記Ａｌ最低含有点、前記Ａｌ最低含有点から前記Ａｌ最高含有点へＴｉおよびＡｌの含有割合がそれぞれ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最高含有点が、
組成式：［Ｔｉ_{１−（Ｅ＋Ｚ）}Ａｌ_ＥＹ_Ｚ］Ｎ（ただし、原子比で、ＥＸは０．４５〜０．６５、Ｚは０．００２〜０．１０を示す）、
上記Ａｌ最低含有点が、
組成式：［Ｔｉ_{１−（Ｆ＋Ｚ）}Ａｌ_ＦＹ_ＺＮ］（ただし、原子比で、Ｆは０．１０〜０．３５、Ｚは０．００２〜０．１０を示す）、
をそれぞれ満足し、かつ隣り合う上記Ａｌ最高含有点とＡｌ最低含有点の間隔が、０．０１〜０．１μｍである、
重切削加工で硬質被覆層がすぐれた耐チッピング性を発揮する被覆ＢＮ基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ＢＮ基工具において、これを構成する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最高含有点の組成
（Ｔｉ，Ａｌ，Ｙ）Ｎ層において、上記の通りＴｉは高温強度を向上させ、Ａｌは高温硬さおよび耐熱性を向上させ、さらにＹは耐熱塑性変形性を向上させる作用を有するものであり、したがってＡｌ成分の含有割合が相対的に高いＡｌ最高含有点では上記の従来（Ｔｉ，Ａｌ）Ｎ層に相当する高温硬さおよび耐熱性と、Ｙ成分含有による耐熱塑性変形性を具備し、耐摩耗性向上に寄与するが、Ａｌの含有割合を示すＥ値がＴｉとＹの合量に占める割合（原子比、以下同じ）で０．４５未満では所望の高温硬さおよび耐熱性を確保することができず、一方前記Ｅ値が同じく０．６５を越えて高くなると、高い高温強度を有するＡｌ最低含有点が隣接して存在しても層自体の高温強度の低下は避けられず、この結果チッピングなどが発生し易くなることから、Ｅ値を０．４５〜０．６５と定めた。
また、Ｙの含有割合を示すＺ値がＴｉとＡｌの合量に占める割合が０．００２未満では所望の耐熱塑性変形性向上効果が得られず、一方前記Ｚ値が０．１０を越えると高温強度が急激に低下するようになることから、Ａｌ最高含有点におけるＺ値を０．００２〜０．１０と定めた。
【００１１】
（ｂ）Ａｌ最低含有点の組成
上記の通りＡｌ最高含有点は相対的に高い高温硬さおよび耐熱性を有するが、反面高温強度の劣るものであるため、このＡｌ最高含有点の高温強度不足を補う目的で、相対的にＴｉ含有割合を高くし、かつこれに伴なう耐熱塑性変形性の低下をＹ成分含有によって抑制し、この結果として熱塑性変形がない状態で、すぐれた高温強度を有するようになるＡｌ最低含有点を厚さ方向に交互に介在させ、機械的熱的衝撃の高い重切削条件でもチッピングなどの発生が起らないようにするものであるが、Ａｌの含有割合を示すＦ値がＴｉとＹの合量に占める割合で０．１０未満になると、Ａｌ最低含有点の高温硬さおよび耐熱性が低くなり過ぎ、これが摩耗促進の原因となり、一方前記Ｙ値が０．３５を越えると、高温強度が急激に低下し、切刃部にチッピングが発生し易くなることから、Ｙ値を０．１０〜０．３５と定めた。
さらに、Ｙの含有割合を示すＺ値がＴｉとＡｌの合量に占める割合で０．００２未満では、高Ｔｉ含有に伴なう熱塑性変形の発生を十分に抑制するすることができず、一方同Ｚ値が０．１０を越えると、高温強度に低下傾向が現れることから、Ａｌ最低含有点におけるＺ値を０．００２〜０．１０と定めた。
【００１２】
（ｃ）Ａｌ最高含有点とＡｌ最低含有点間の間隔
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、この結果層に所望の高温硬さと耐熱性、さらにすぐれた高温強度を確保することができなくなり、またその間隔が０．１μｍを越えるとそれぞれの点がもつ欠点、すなわちＡｌ最高含有点であれば高温強度不足、Ａｌ最低含有点であれば高温硬さおよび耐熱性不足が層内に局部的に現れ、これが原因で切刃にチッピングが発生し易くなったり、摩耗が促進されるようになることから、その間隔を０．０１〜０．１μｍと定めた。
【００１３】
（ｄ）硬質被覆層の平均層厚
その平均層厚が０．５μｍ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１０μｍを越えると、切刃部ににチッピングが発生し易くなることから、その平均層厚を０．５〜１０μｍと定めた。
【００１４】
【発明の実施の形態】
つぎに、この発明の被覆ＢＮ基工具を実施例により具体的に説明する。
原料粉末として、いずれも０．５〜４μｍの範囲内の平均粒径を有する立方晶窒化硼素（以下、ｃ−ＢＮで示す）粉末、炭化チタン（以下、ＴｉＣで示す）粉末、窒化チタン（以下、ＴｉＮで示す）粉末、炭窒化チタン（以下、ＴｉＣＮで示す）粉末、炭化タングステン（以下、ＷＣで示す）粉末、Ａｌ粉末、Ｃｏ粉末、ＴｉとＡｌの金属間化合物粉末であるＴｉ_３Ａｌ粉末、ＴｉＡｌ粉末、およびＴｉＡｌ_３粉末、さらに組成式：Ｔｉ_２ＡｌＮを有する複合金属窒化物粉末、硼化チタン（以下、ＴｉＢ_２で示す）粉末、窒化アルミニウム（以下、ＡｌＮで示す）粉末、硼化アルミニウム（以下、ＡｌＢ_２で示す）粉末、酸化アルミニウム（Ａｌ_２Ｏ_３で示す）粉末を用意し、これら原料粉末を表１に示される配合組成に配合し、ボールミルで７２時間湿式混合し、乾燥した後、１２０ＭＰａの圧力で直径：５０ｍｍ×厚さ：１．５ｍｍの寸法をもった圧粉体にプレス成形し、ついでこの圧粉体を、圧力：１Ｐａの真空雰囲気中、９００〜１３００℃の範囲内の所定温度に６０分間保持の条件で焼結して切刃片用予備焼結体とし、この予備焼結体を、別途用意した、Ｃｏ：８質量％、ＷＣ：残りの組成、並びに直径：５０ｍｍ×厚さ：２ｍｍの寸法をもったＷＣ基超硬合金製支持片と重ね合わせた状態で、通常の超高圧焼結装置に装入し、通常の条件である圧力：５ＧＰａ、温度：１２００〜１４００℃の範囲内の所定温度に保持時間：０．８時間の条件で超高圧焼結し、焼結後上下面をダイヤモンド砥石を用いて研摩し、ワイヤー放電加工装置にて一辺３ｍｍの正三角形状に分割し、さらにＣｏ：５質量％、ＴａＣ：５質量％、ＷＣ：残りの組成およびＣＩＳ規格ＳＮＧＡ１２０４１２の形状（厚さ：４．７６ｍｍ×一辺長さ：１２．７ｍｍの正三角形）をもったＷＣ基超硬合金製チップ本体のろう付け部（コーナー部）に、質量％で、Ｃｕ：３０％、Ｚｎ：２８％、Ｎｉ：２％、Ａｇ：残りからなる組成を有するＡｇ合金のろう材を用いてろう付けし、所定寸法に外周加工した後、切刃部に幅：０．１５ｍｍ、角度：２５°のホーニング加工を施し、さらに仕上げ研摩を施すことによりＩＳＯ規格ＳＮＧＡ１２０４１２のチップ形状をもったＢＮ基基体Ａ〜Ｐをそれぞれ製造した。
【００１５】
ついで、上記のＢＮ基基体Ａ〜Ｐのそれぞれを、アセトン中で超音波洗浄し、乾燥した状態で、図１に示されるアークイオンプレーティング装置内の回転テーブル上の中心軸から半径方向に所定距離離れた位置に、外周部に沿って所定間隔をもって設けた多段回転支持板上に載置し、一方側のカソード電極（蒸発源）として、種々の成分組成をもったＡｌ最低含有点形成用Ｔｉ−Ａｌ−Ｙ合金、他方側のカソード電極（蒸発源）として、種々の成分組成をもったＡｌ最高含有点形成用Ｔｉ−Ａｌ−Ｙ合金を前記回転テーブルを挟んで対向配置し、まず装置内を排気して０．５Ｐａ以下の真空に保持しながら、ヒーターで装置内を４５０℃に加熱した後、Ａｒガスを導入して１．５ＰａのＡｒガス雰囲気とし、前記回転テーブル上で自転しながら回転するＢＮ基基体に−９００Ｖの直流バイアス電圧を印加して、前記ＢＮ基基体表面をＡｒボンバード洗浄し、ついで装置内に反応ガスとして窒素ガスを導入して３Ｐａの反応雰囲気とすると共に、前記回転テーブル上で自転しながら回転するＢＮ基基体に−２５Ｖの直流バイアス電圧を印加して、それぞれのカソード電極（前記Ａｌ最低含有点形成用Ｔｉ−Ａｌ−Ｙ合金およびＡｌ最高含有点形成用Ｔｉ−Ａｌ−Ｙ合金）とアノード電極との間に１２５Ａの電流を流してアーク放電を発生させ、もって前記ＢＮ基基体の表面に、層厚方向に沿って表３，４に示される目標組成のＡｌ最低含有点とＡｌ最高含有点とが交互に同じく表３，４に示される目標間隔で繰り返し存在し、かつ前記Ａｌ最高含有点から前記Ａｌ最低含有点、前記Ａｌ最低含有点から前記Ａｌ最高含有点へＡｌおよびＴｉの含有割合が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３，４に示される目標層厚の硬質被覆層を蒸着形成することにより、本発明被覆ＢＮ基工具１〜１６をそれぞれ製造した。
【００１６】
また、比較の目的で、上記のＢＮ基チップ基体Ａ〜Ｐの表面への硬質被覆層の形成を、図２に示される通常のアークイオンプレーティング装置を用い、カソード電極（蒸発源）として種々の成分組成をもったＴｉ−Ａｌ合金およびＴｉ−Ａｌ−Ｙ合金をそれぞれ装着し、装置内を排気して０．５Ｐａ以下の真空に保持しながら、ヒーターで装置内を５００℃に加熱した後、Ａｒガスを装置内に導入して２．５ＰａのＡｒ雰囲気とし、この状態でＢＮ基基体に−８００Ｖのバイアス電圧を印加してＢＮ基基体表面をＡｒガスボンバード洗浄し、ついで装置内に反応ガスとして窒素ガスを導入して３．５Ｐａの反応雰囲気とすると共に、前記ＢＮ基基体に印加するバイアス電圧を−１００Ｖに下げて、前記カソード電極とアノード電極との間にアーク放電を発生させる条件にて行なって、前記ＢＮ基基体Ａ〜Ｐのそれぞれの表面に、表５，６に示される目標組成および目標層厚を有し、かつ上記の従来被覆ＢＮ基工具を構成する硬質被覆層に相当する（Ｔｉ，Ａｌ）Ｎ層、すなわち層厚方向に沿って実質的に組成変化のない（Ｔｉ，Ａｌ）Ｎ層、および同じく層厚方向に沿って実質的に組成変化のない（Ｔｉ，Ａｌ，Ｙ）Ｎ層からなる硬質被覆層を蒸着形成する以外は、上記の本発明被覆ＢＮ基工具１〜１６の製造条件と同じ条件で比較被覆ＢＮ基工具１〜１６をそれぞれ製造した。
【００１７】
つぎに、上記本発明被覆ＢＮ基工具１〜１６および比較被覆ＢＮ基工具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・ＳＣＭ４１５の浸炭焼入れ丸棒（表面硬さ：ＨＲＣ６０）、
切削速度：１２０ｍ／ｍｉｎ．、
切り込み：０．５１ｍｍ、
送り：０．０９ｍｍ／ｒｅｖ．、
切削時間：２０分、
の条件での合金鋼の乾式高切り込み切削加工試験、
被削材：ＪＩＳ・Ｓ１５Ｃの高周波焼入れ丸棒（表面硬さ：ＨＲＣ５５）、
切削速度：１３０ｍ／ｍｉｎ．、
切り込み：０．２０ｍｍ、
送り：０．５３ｍｍ／ｒｅｖ．、
切削時間：２０分、
の条件での炭素鋼の乾式高送り切削加工試験、さらに、
被削材：ＪＩＳ・ＦＣ３００の丸棒、
切削速度：６００ｍ／ｍｉｎ．、
切り込み：０．６５ｍｍ、
送り：０．１５ｍｍ／ｒｅｖ．、
切削時間：３０分、
の条件での鋳鉄の乾式高切り込み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２〜５に示した。
【００１８】
【表１】

【００１９】
【表２】

【００２０】
【表３】

【００２１】
【表４】

【００２２】
【表５】

【００２３】
この結果得られた本発明被覆ＢＮ基工具１〜１６を構成する硬質被覆層におけるＡｌ最高含有点とＡｌ最低含有点の組成、並びに比較被覆ＢＮ基工具１〜１６の硬質被覆層の組成について、厚さ方向に沿ってＴｉ、Ａｌ、およびＹ成分の含有量をオージェ分光分析装置を用いて測定したところ、本発明被覆ＢＮ基工具１〜１６の硬質被覆層では、Ａｌ最高含有点とＡｌ最低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、かつ前記Ａｌ最高含有点から前記Ａｌ最低含有点、前記Ａｌ最低含有点から前記Ａｌ最高含有点へＴｉおよびＡｌ成分の含有割合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が確認され、また硬質被覆層の平均層厚も目標層厚と実質的に同じ値を示した。
一方前記比較被覆ＢＮ基工具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層厚と実質的に同じ平均層厚を示すことが確認された。
【００２４】
【発明の効果】
表２〜５に示される結果から、硬質被覆層が層厚方向にＡｌ最低含有点とＡｌ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最高含有点から前記Ａｌ最低含有点、前記Ａｌ最低含有点から前記Ａｌ最高含有点へＡｌおよびＴｉの含有割合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ＢＮ基工具は、いずれも各種の鋼や鋳鉄などの切削加工を、機械的熱的衝撃の高い高切り込みや高送りなどの重切削条件で行なった場合にも、硬質被覆層がすぐれた耐チッピング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（Ｔｉ，Ａｌ）Ｎ層または（Ｔｉ，Ａｌ，Ｙ）Ｎ層からなる比較被覆ＢＮ基工具においては、前記硬質被覆層が高温硬さと耐熱性を有するものの、十分な高温強度を具備するものでないために、チッピングが発生し、これが原因で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ＢＮ基工具は、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重切削条件で行なった場合にも、すぐれた耐チッピング性を発揮し、長期に亘ってすぐれた耐摩耗性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】この発明の被覆ＢＮ基工具を構成する硬質被覆層を形成するのに用いたアークイオンプレーティング装置を示し、（ａ）は概略平面図、（ｂ）は概略正面図である。
【図２】比較被覆ＢＮ基工具を構成する硬質被覆層を形成するのに用いた通常のアークイオンプレーティング装置の概略説明図である。[0001]
BACKGROUND OF THE INVENTION
This invention has a high temperature strength and heat-resistant plastic deformability with excellent hard coating layer, and also has excellent high-temperature hardness and heat resistance. Therefore, cutting of various types of steel and cast iron, in particular, has a high mechanical and thermal shock. Cutting tool made of surface-coated cubic boron nitride based sintered material (hereinafter referred to as coated BN group) that exhibits excellent chipping resistance even when performed under heavy cutting conditions such as high cutting with high cutting and high feed. Tool).
[0002]
[Prior art]
In general, a coated BN base tool is provided with a throwaway tip that is detachably attached to the tip of a cutting tool for turning a work material such as various types of steel and cast iron, and the throwaway tip is detachably attached. In addition, there is known a slow-away end mill that performs cutting in the same manner as a solid type end mill used for chamfering, grooving, and shoulder machining.
[0003]
Moreover, as a coated BN-based tool, it has excellent high-temperature hardness and heat resistance, but because it has low high-temperature strength, it has a high cutting speed and high-speed surface finishing under conditions where cutting and feeding are significantly reduced. For the purpose of improving the strength of the cutting tool itself on the surface of the BN base substrate, a cutting tool made of a cubic boron nitride base sintered material used only in
Composition formula: (Ti _1-E Al _E ) N (however, in atomic ratio, E represents 0.45 to 0.65),
A hard coating layer made of a composite nitride of Ti and Al satisfying the following [hereinafter referred to as (Ti, Al) N] is physically vapor-deposited with an average layer thickness of 0.5 to 10 μm. A coated BN-based tool is known in which chipping or chipping (micro chipping) does not occur in the cutting edge portion even when continuous cutting or intermittent cutting of various types of steel or cast iron is performed (for example, Patent Document 1).
[0004]
Further, the above-mentioned coated BN-based tool is, for example, the above-mentioned BN-based substrate is loaded into an arc ion plating apparatus which is one type of physical vapor deposition apparatus schematically shown in FIG. For example, in the state heated to a temperature of 505 ° C., an arc discharge is generated between the anode electrode and a cathode electrode (evaporation source) in which a Ti—Al alloy having a predetermined composition is set, for example, under a current of 145 A, At the same time, nitrogen gas is introduced into the apparatus as a reaction gas to form a reaction atmosphere of, for example, 2 Pa, while the BN base substrate is subjected to the above-described BN base substrate on the surface of the BN base substrate under the condition that a bias voltage of, for example, −95 V is applied. It is also known that it is produced by vapor-depositing a hard coating layer composed of a (Ti, Al) N layer.
[0005]
[Patent Document 1]
JP-A-8-119774 [0006]
[Problems to be solved by the invention]
In recent years, there has been a remarkable improvement in the performance of cutting devices. On the other hand, there has been a strong demand for labor saving and energy saving and further cost reduction for cutting, and with this, cutting is performed at high speed and high cutting depth, high feed, etc. Although there is a tendency to be performed under heavy cutting conditions, the conventional coated BN-based tool has no problem when it is used under normal cutting conditions, but the cutting work is performed with a high mechanical thermal shock. When performed under heavy cutting conditions such as high cutting depth and high feed, chipping (microcracking) is likely to occur at the cutting edge due to insufficient high-temperature strength of the hard coating layer. The current situation is that the service life is reached in a short time.
[0007]
[Means for Solving the Problems]
In view of the above, the present inventors have developed the above-described conventional coating to develop a coated BN-based tool that exhibits excellent chipping resistance with a hard coating layer particularly in heavy cutting such as steel and cast iron. As a result of conducting research by focusing on the hard coating layer constituting the BN-based tool,
(A) The (Ti, Al) N layer constituting the hard coating layer of the conventional coated BN-based tool formed using the arc ion plating apparatus shown in FIG. For example, an arc having a structure shown in FIG. 1 (a) in a schematic plan view and in FIG. 1 (b) in a schematic front view. An ion plating apparatus, that is, a rotating table for mounting a BN base substrate is provided at the center of the apparatus, and a Ti—Al—Y alloy having a relatively high Al content is disposed on one side with the rotating table interposed therebetween, and the other is relatively disposed on the other side. An arc ion plating apparatus in which a Ti-Al-Y alloy having a low Al content is disposed as a cathode electrode (evaporation source) is opposed to the center axis of the apparatus on the rotary table at a predetermined distance in the radial direction. At this position, a plurality of BN bases are mounted in a ring shape along the outer periphery, and in this state, the rotary table is rotated with the atmosphere inside the apparatus as a nitrogen atmosphere, and the layer thickness of the hard coating layer formed by vapor deposition is uniform. While the BN base substrate itself is rotated for the purpose of achieving the above, arc discharge is generated between the cathode electrode (evaporation source) and the anode electrode on both sides, and Ti, Al, and Y are formed on the surface of the BN base substrate. When a hard coating layer made of a composite nitride of [hereinafter, referred to as (Ti, Al, Y) N] is formed, the resulting (Ti, Al, Y) N layer is arranged in a ring shape on the rotary table. When the formed BN-based substrate is closest to the cathode electrode (evaporation source) of the Ti—Al—Y alloy having a relatively high Al content ratio on one side, the highest Al content point is formed in the layer, Also, the BN base substrate is At the point closest to the cathode electrode of the Ti-Al-Y alloy having a relatively low Al content on the other side of the layer, the lowest Al content point is formed in the layer. The highest Al content point and the lowest Al content point appear alternately with a predetermined interval along the direction, Ti from the highest Al content point to the lowest Al content point, from the lowest Al content point to the highest Al content point, Ti and It has a component concentration distribution structure in which the Al content ratio changes continuously.
[0008]
(B) In the (Ti, Al, Y) N layer having the repeated continuous change component concentration distribution structure of (a) above, for example, the respective compositions of the cathode electrodes (evaporation sources) arranged opposite to each other are prepared, and the BN base substrate is prepared. By controlling the rotation speed of the mounted rotary table,
The Al highest content point is
Composition formula: [Ti _{1- (E + Z)} Al _E Y _Z ] N (however, in atomic ratio, E is 0.45 to 0.65, Z is 0.002 to 0.10),
The minimum Al content point is
Composition formula: [Ti _{1- (F + Z)} Al _F Y _Z ] N (however, in atomic ratio, F represents 0.10 to 0.35, Z represents 0.002 to 0.10),
And the interval in the thickness direction of the adjacent Al highest content point and Al lowest content point adjacent to each other is 0.01 to 0.1 μm,
The Al highest content point has high temperature hardness and heat resistance equivalent to the high temperature hardness and heat resistance of the conventional (Ti, Al) N layer, while the Al minimum content point has the highest Al content. Since the Al content is lower than the content point and the Ti content is high, relatively high high-temperature strength is ensured. In this case, thermoplastic deformation that causes uneven wear occurs due to the high Ti content. However, due to the action of the coexisting Y component, the generation of the component is remarkably suppressed, and the distance between the Al highest content point and the Al lowest content point is extremely small. In addition to the high-temperature hardness and heat resistance corresponding to the conventional (Ti, Al) N layer, it has a higher high-temperature strength and heat-resistant plastic deformation than the conventional (Ti, Al) N layer. The coated BN-based tool consisting of the (Ti, Al, Y) N layer of the above, especially cutting of various steels and cast iron was performed under heavy cutting conditions such as high cutting and high feed with high mechanical thermal shock Even in this case, the hard coating layer should exhibit excellent chipping resistance.
The research results shown in (a) and (b) above were obtained.
[0009]
The present invention has been made based on the above research results. A hard coating layer made of (Ti, Al, Y) N is physically applied on the surface of a BN base substrate with an average layer thickness of 0.5 to 10 μm. In the coated BN base tool formed by vapor deposition,
In the hard coating layer, the highest Al content point and the lowest Al content point are present alternately at predetermined intervals along the thickness direction, and the lowest Al content point, the Al content point, from the highest Al content point. A component concentration distribution structure in which the content ratios of Ti and Al continuously change from the lowest content point to the Al highest content point,
Furthermore, the above Al highest content point,
Composition formula: [Ti _{1- (E + Z)} Al _E Y _Z ] N (however, EX is 0.45 to 0.65 and Z is 0.002 to 0.10 in atomic ratio),
The minimum Al content point is
Composition formula: [Ti _{1- (F + Z)} Al _F Y _Z N] (wherein F represents 0.10 to 0.35 and Z represents 0.002 to 0.10 in atomic ratio),
And the distance between the adjacent Al highest content point and Al lowest content point adjacent to each other is 0.01 to 0.1 μm.
It is characterized by a coated BN-based tool that exhibits excellent chipping resistance with a hard coating layer in heavy cutting.
[0010]
Next, the reason why the configuration of the hard coating layer constituting the coated BN-based tool of the present invention is limited as described above.
(A) Composition of the highest Al content point (Ti, Al, Y) In the N layer, as described above, Ti improves high-temperature strength, Al improves high-temperature hardness and heat resistance, and Y further shows heat-resistant plastic deformability. Therefore, at the highest Al content point where the content ratio of the Al component is relatively high, the high temperature hardness and heat resistance corresponding to the conventional (Ti, Al) N layer and the Y component content are included. Although it contributes to the improvement of wear resistance due to the heat-resistant plastic deformability by E, the E value indicating the Al content ratio is the ratio (atomic ratio, the same shall apply hereinafter) to the total amount of Ti and Y, and less than 0.45. The high temperature hardness and heat resistance of the layer cannot be ensured. On the other hand, if the E value is also higher than 0.65, even if the Al minimum content point having a high high temperature strength exists adjacent to the layer itself, As a result, a decrease in high-temperature strength is inevitable. Since such mappings are easily generated, defining the E value 0.45 to 0.65.
Further, if the Z value indicating the Y content ratio is less than 0.002 in the total amount of Ti and Al, the desired heat-resistant plastic deformation improvement effect cannot be obtained, while if the Z value exceeds 0.10, Since the high-temperature strength suddenly decreases, the Z value at the Al highest content point is determined to be 0.002 to 0.10.
[0011]
(B) Composition of Al minimum content point As described above, the Al maximum content point has relatively high high-temperature hardness and heat resistance, but on the other hand, it is inferior in high-temperature strength. In order to compensate for this, the Ti content ratio is relatively increased, and the accompanying decrease in heat-resistant plastic deformation is suppressed by the inclusion of the Y component. As a result, excellent high-temperature strength is obtained in the absence of thermoplastic deformation. It is intended to prevent the occurrence of chipping even under heavy cutting conditions with high mechanical and thermal shock, by alternately interposing the lowest Al content points to be included in the thickness direction. When the F value shown is less than 0.10 as a percentage of the total amount of Ti and Y, the high temperature hardness and heat resistance of the Al minimum content point become too low, which causes wear promotion, while the Y value is 0. Higher than 35, high temperature Degree decreases rapidly, determined from the easily chipping occurs in the cutting edge, the Y value as 0.10 to 0.35.
Furthermore, if the Z value indicating the Y content ratio is less than 0.002 in the total amount of Ti and Al, the occurrence of thermoplastic deformation accompanying high Ti content cannot be sufficiently suppressed, When the Z value exceeds 0.10, a tendency to decrease in high-temperature strength appears. Therefore, the Z value at the Al minimum content point was determined to be 0.002 to 0.10.
[0012]
(C) Interval between the highest Al content point and the lowest Al content point If the distance is less than 0.01 μm, it is difficult to clearly form each point with the above composition. Heat resistance, excellent high temperature strength cannot be secured, and if the interval exceeds 0.1 μm, each point has a defect, that is, if Al is the highest content point, insufficient high temperature strength, Al minimum content point If so, high-temperature hardness and insufficient heat resistance appear locally in the layer, which makes it easier for chipping to occur on the cutting edge and promotes wear. It was determined to be 0.1 μm.
[0013]
(D) Average thickness of hard coating layer If the average layer thickness is less than 0.5 μm, the desired wear resistance cannot be ensured. On the other hand, if the average layer thickness exceeds 10 μm, Since chipping easily occurs, the average layer thickness is set to 0.5 to 10 μm.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Next, the coated BN-based tool of the present invention will be specifically described with reference to examples.
As raw material powders, cubic boron nitride (hereinafter referred to as c-BN) powder, titanium carbide (hereinafter referred to as TiC) powder, titanium nitride (hereinafter referred to as “c-BN”) having an average particle diameter in the range of 0.5 to 4 μm. , TiN) powder, titanium carbonitride (hereinafter referred to as TiCN) powder, tungsten carbide (hereinafter referred to as WC) powder, Al powder, Co powder, and Ti ₃ Al intermetallic compound powder Ti ₃ Al powder , TiAl powder, and TiAl ₃ powder, further composition formula: composite metal nitride powder having Ti ₂ AlN, titanium boride (hereinafter referred to as TiB ₂ ) powder, aluminum nitride (hereinafter referred to as AlN) powder, boride aluminum (hereinafter, indicated by AlB ₂₎ powder, prepared powders (indicated by _Al 2 _{O 3)} of aluminum oxide, are blended raw material powder formulation compositions shown in Table 1, Bo After wet-mixing for 72 hours in a mill and drying, it was pressed into a green compact having a diameter of 50 mm × thickness: 1.5 mm at a pressure of 120 MPa, and this green compact was then pressed at a pressure of 1 Pa. In a vacuum atmosphere, sintering was performed at a predetermined temperature in the range of 900 to 1300 ° C. for 60 minutes to obtain a pre-sintered body for a cutting edge piece, and this pre-sintered body was prepared separately, Co: 8 mass %, WC: remaining composition, diameter: 50 mm × thickness: in a state of being overlapped with a support piece made of a WC-based cemented carbide having a dimension of 2 mm, it was charged into a normal ultra-high pressure sintering apparatus, The pressure is 5 GPa, the temperature is 1200 to 1400 ° C., the holding time is 0.8 hours, and the upper and lower surfaces are polished with a diamond grindstone after sintering. , In the shape of a regular triangle with a side of 3mm using a wire electrical discharge machine Further, Co: 5% by mass, TaC: 5% by mass, WC: remaining composition and WC with the shape of CIS standard SNGA12041 (thickness: 4.76 mm × one side length: 12.7 mm equilateral triangle) A brazing material of an Ag alloy having a composition consisting of Cu: 30%, Zn: 28%, Ni: 2%, and Ag: the remainder in the brazing portion (corner portion) of the chip body made of the base cemented carbide. After brazing and processing the outer periphery to a predetermined size, the cutting edge was subjected to honing with a width of 0.15 mm and an angle of 25 °, and further polished to obtain a chip shape conforming to ISO standard SNGA120412. BN-based substrates A to P were produced, respectively.
[0015]
Next, each of the above BN-based substrates A to P is ultrasonically cleaned in acetone and dried, and then in a radial direction from the central axis on the rotary table in the arc ion plating apparatus shown in FIG. For the formation of the lowest Al content point with various component compositions as a cathode electrode (evaporation source) on one side, placed on a multi-stage rotating support plate provided at a predetermined interval along the outer periphery at a distance Ti-Al-Y alloy, Ti-Al-Y alloy for forming the highest Al content point having various composition as opposed cathode electrode (evaporation source) are arranged opposite to each other with the rotary table interposed therebetween. The inside of the apparatus is heated to 450 ° C. with a heater while evacuating the interior and maintaining a vacuum of 0.5 Pa or less, and then Ar gas is introduced to form an Ar gas atmosphere of 1.5 Pa, which rotates on the rotary table. Naga A DC bias voltage of −900 V is applied to the rotating BN base substrate, the surface of the BN base substrate is cleaned with Ar bombardment, and nitrogen gas is introduced into the apparatus as a reaction gas to obtain a reaction atmosphere of 3 Pa. A DC bias voltage of −25 V is applied to a BN base substrate that rotates while rotating on a turntable, and each cathode electrode (Ti-Al-Y alloy for forming the lowest Al content point and Ti for forming the highest Al content point) is applied. -A1 -Y alloy) and an anode electrode are caused to flow an electric current of 125 A to generate an arc discharge, thereby forming the target composition shown in Tables 3 and 4 along the layer thickness direction on the surface of the BN base substrate. Al minimum content point and Al maximum content point are alternately repeatedly present at the target intervals shown in Tables 3 and 4, and from the Al maximum content point to the Al minimum content point, the A A hard coating layer having a component concentration distribution structure in which the content ratio of Al and Ti continuously changes from the lowest content point to the highest Al content point and also having a target layer thickness shown in Tables 3 and 4 is formed by vapor deposition. By this, this invention coated BN base tool 1-16 was manufactured, respectively.
[0016]
For the purpose of comparison, the formation of the hard coating layer on the surface of the BN-based chip bases A to P is variously performed as a cathode electrode (evaporation source) using a normal arc ion plating apparatus shown in FIG. Each of the Ti-Al alloy and Ti-Al-Y alloy having the composition of 1 is mounted, and the inside of the apparatus is heated to 500 ° C. with a heater while evacuating the apparatus and maintaining a vacuum of 0.5 Pa or less. Then, Ar gas is introduced into the apparatus to form an Ar atmosphere of 2.5 Pa, and in this state, a bias voltage of −800 V is applied to the BN base substrate to clean the surface of the BN base substrate with Ar gas bombardment, and then react in the apparatus. Nitrogen gas is introduced as a gas to make a reaction atmosphere of 3.5 Pa, and the bias voltage applied to the BN-based substrate is lowered to −100 V so that the anode electrode is connected between the cathode electrode and the anode electrode. The above-mentioned conventional coated BN-based tool having the target composition and the target layer thickness shown in Tables 5 and 6 on the surface of each of the BN-based substrates A to P is performed. The (Ti, Al) N layer corresponding to the hard coating layer to be formed, that is, the (Ti, Al) N layer having substantially no composition change along the layer thickness direction, and the composition substantially along the layer thickness direction. Comparative coated BN base tools 1-16 under the same conditions as the manufacturing conditions of the present invention coated BN base tools 1-16 except that a hard coating layer consisting of a (Ti, Al, Y) N layer without change is deposited. Were manufactured respectively.
[0017]
Next, with the present invention coated BN base tools 1-16 and comparative coated BN base tools 1-16, this is screwed to the tip of the tool steel tool with a fixing jig,
Work material: Carburized and hardened round bar of JIS / SCM415 (surface hardness: HRC60),
Cutting speed: 120 m / min. ,
Cutting depth: 0.51 mm,
Feed: 0.09 mm / rev. ,
Cutting time: 20 minutes,
High-cut cutting test of alloy steel under the conditions of
Work material: JIS S15C induction hardening round bar (surface hardness: HRC55),
Cutting speed: 130 m / min. ,
Cutting depth: 0.20mm,
Feed: 0.53 mm / rev. ,
Cutting time: 20 minutes,
Carbon steel dry high feed cutting test under the conditions of
Work material: JIS / FC300 round bar,
Cutting speed: 600 m / min. ,
Cutting depth: 0.65 mm,
Feed: 0.15 mm / rev. ,
Cutting time: 30 minutes,
The dry high-cut cutting test of cast iron was performed under the conditions described above, and the flank wear width of the cutting edge was measured in any cutting test. The measurement results are shown in Tables 2-5.
[0018]
[Table 1]

[0019]
[Table 2]

[0020]
[Table 3]

[0021]
[Table 4]

[0022]
[Table 5]

[0023]
About the composition of the Al highest content point and the Al lowest content point in the hard coating layer constituting the present invention coated BN base tool 1-16 obtained as a result, and the composition of the hard coating layer of the comparative coated BN base tool 1-16, When the contents of Ti, Al, and Y components were measured along the thickness direction using an Auger spectroscopic analyzer, in the hard coating layers of the coated BN-based tools 1 to 16 of the present invention, the Al highest content point and the Al minimum content were measured. The content points are alternately and repeatedly present at substantially the same composition and interval as the target value, and Ti and Al from the Al highest content point to the Al lowest content point, from the Al lowest content point to the Al highest content point It was confirmed that each component content ratio had a component concentration distribution structure that changed continuously, and the average thickness of the hard coating layer showed substantially the same value as the target layer thickness.
On the other hand, in the hard coating layers of the comparative coating BN base tools 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 average layer thickness is substantially the same as the target layer thickness. It was confirmed to show.
[0024]
【The invention's effect】
From the results shown in Tables 2 to 5, in the hard coating layer, the lowest Al content point and the highest Al content point are repeatedly present at predetermined intervals in the thickness direction, and the lowest Al content from the highest Al content point. The present invention coated BN-based tool having a component concentration distribution structure in which the content ratio of Al and Ti continuously changes from the content point, the lowest Al content point to the highest Al content point, all of which are various steels, cast irons, etc. Even when cutting is performed under heavy cutting conditions such as high cutting and high feed with high mechanical and thermal shock, the hard coating layer exhibits excellent chipping resistance, whereas the hard coating layer In a comparatively coated BN-based tool composed of a (Ti, Al) N layer or a (Ti, Al, Y) N layer that has substantially no composition change along the layer thickness direction, the hard coating layer has high-temperature hardness and heat resistance. But enough For not intended to include a temperature strength, chipping occurs and this is apparent that lead to a relatively short time service life due.
As described above, the coated BN-based tool of the present invention has excellent resistance not only to cutting under normal conditions, but also when cutting various steels and cast irons under heavy cutting conditions. Since it exhibits chipping properties and exhibits excellent wear resistance over a long period of time, it can sufficiently satisfactorily cope with labor saving and energy saving of cutting work and cost reduction.
[Brief description of the drawings]
FIG. 1 shows an arc ion plating apparatus used for forming a hard coating layer constituting a coated BN-based tool of the present invention, wherein (a) is a schematic plan view and (b) is a schematic front view.
FIG. 2 is a schematic explanatory view of a normal arc ion plating apparatus used for forming a hard coating layer constituting a comparative coated BN-based tool.

Claims

Surface coating formed by physical vapor deposition of a hard coating layer made of a composite nitride of Ti, Al, and Y (yttrium) on the surface of a substrate made of a cubic boron nitride-based sintered material with an average layer thickness of 0.5 to 10 μm. In cemented carbide cutting tools,
In the hard coating layer, the highest Al content point and the lowest Al content point are present alternately at predetermined intervals along the thickness direction, and the lowest Al content point, the Al content point, from the highest Al content point. A component concentration distribution structure in which the content ratios of Ti and Al continuously change from the lowest content point to the Al highest content point,
Furthermore, the Al highest content point, composition _{_{formula: [Ti 1- (E + Z}} ) Al E Y Z] N ( provided that an atomic ratio, E is 0.45 to 0.65, Z is from 0.002 to 0. 10),
The Al minimum content point is the composition formula: [Ti _{1- (F + Z)} Al _F Y _Z ] N (wherein the atomic ratio, F is 0.10 to 0.35, Z is 0.002 to 0.10. The distance between the Al highest content point and the Al lowest content point adjacent to each other is 0.01 to 0.1 μm,
A cutting tool made of a surface-coated cubic boron nitride-based sintered material that exhibits excellent chipping resistance with a hard coating layer that is characterized by heavy cutting.