JP2004306216A

JP2004306216A - Coated cemented carbide end mill

Info

Publication number: JP2004306216A
Application number: JP2003104854A
Authority: JP
Inventors: Takashi Ishikawa; 剛史石川
Original assignee: Hitachi Tool Engineering Ltd
Current assignee: Moldino Tool Engineering Ltd
Priority date: 2003-04-09
Filing date: 2003-04-09
Publication date: 2004-11-04
Anticipated expiration: 2023-04-09
Also published as: JP4247032B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coated cemented carbide end mill, remarkably improved in wear resistance to exhibit excellent tool life by heightening the hardness which is the disadvantage of an (AlCr)N-series coating. <P>SOLUTION: In this coated cemented carbide end mill, the covering is a hard coating covered by an arc discharge type ion plating method. The hard coating includes at least one or more layers of (AlxCrl-x-ySiy)(Nl-α-β-γBαCβOγ), wherein (200)face thereof has diffraction strength, the half-power band width thereof is from 0.5 degrees to 2.0 degrees, both inclusive, and binding energy of at least Al, Cr and/or Si and oxygen is within a range from 525eV to 535eV in X-ray photoelectric spectral analysis. In (AlxCrl-x-ySiy)(Nl-α-β-γBαCβOγ), x, y, α, β and γ respectively indicates atomic percentage, 0.45<x<0.85, 0≤y<0.35, 0.50≤x+y<1.0, 0≤α<0.15, 0<β<0.65, 0<γ<0.65, and 0<α+β+γ≤1.0. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明が属する技術分野】
本発明は、金型、機械部品等の切削加工に使用される超硬エンドミルの表面被覆材として有用な硬質皮膜を被覆することにより、優れた耐摩耗性を発揮する被覆超硬エンドミルに関する。
【０００２】
【従来の技術】
ＡｌＣｒ系皮膜は、耐高温酸化特性に優れた硬質皮膜材として、下記に示す特許文献１から３が開示されている。
【特許文献１】特許第３０２７５０２号公報（第６頁、図１）
【特許文献２】特許第３０３９３８１号公報（第４頁、図１）
【特許文献３】特開平２００２−１６０１２９号公報（第３頁、図１）
【０００３】
切削加工の低コスト化に伴い、高能率切削加工すなわち高速切削加工、高送り切削加工が行なわれ、超硬エンドミル切刃近傍の切削温度は、著しく向上した。このことにより超硬エンドミル表面に被覆される硬質皮膜においても、さらに高温及びもしくは高圧摩耗環境下で優れた耐摩耗性を有することが望まれており、更に皮膜硬度が高く、耐高温酸化特性に優れた硬質皮膜を被覆した被覆超硬エンドミルの開発が望まれていた。特許文献１は金属成分としてＡｌＣｒとＣ、Ｎ、Ｏの１種より選択されるＡｌＣｒ系硬質膜において、高硬度を有する非晶質膜に関する事例が開示されている。しかしこの非晶質膜の硬度は最大でもヌープ硬さ２１ＧＰａ程度であり、超硬エンドミルとして、耐摩耗効果は改善されず、密着性に関しても十分ではない。特許文献２及び特許文献３に開示されている硬質皮膜はＡｌＣｒの窒化物であり、約１０００℃の耐高温酸化特性を有しているが、１０００℃以上の耐酸化特性の検討は行われていない。また硬度はビッカ−ス硬さ２１ＧＰａ程度で硬度の改善が不十分であり耐摩耗性に乏しい。
【０００４】
【発明が解決しようとする課題】
本願発明は、上記の問題点を改善し、（ＡｌＣｒ）Ｎ系皮膜の欠点である硬度を高めることにより耐摩耗性を著しく改善し、その結果優れた工具寿命を発揮する被覆超硬エンドミルを提供することを目的とする。
【０００５】
【課題を解決するために手段】
本発明は、被覆超硬エンドミルにおいて、該被覆はアーク放電式イオンプレーティング法により被覆された硬質皮膜であり、該硬質皮膜は、（Ａｌ_ｘＣｒ_{１−ｘ−ｙ}Ｓｉ_ｙ）（Ｎ_{１−α−β−γ}Ｂ_αＣ_βＯ_γ）、但し、ｘ、ｙ、α、β、γは夫々原子比率を示し、０．４５＜ｘ＜０．８５、０≦ｙ＜０．３５、０．５０≦ｘ＋ｙ＜１．０、０≦α＜０．１５、０≦β＜０．６５、０＜γ＜０．６５、０＜α＋β＋γ≦１．０で示される少なくとも１層以上からなり、θ−２θ法によるＸ線回折において測定される岩塩構造型の（２００）面に回折強度を有し、その回折ピークの半価幅が、０．５度以上、２．０度以下であり、Ｘ線光電子分光分析における５２５ｅＶから５３５ｅＶの範囲に、少なくともＡｌ、Ｃｒ及び／又はＳｉと酸素との結合エネルギーを有し、該超硬エンドミルの被覆基体はＣｏ含有量が重量％で２．０＜Ｃｏ＜１４．０であり、更にＣｒ、Ｔａ、Ｔｉ、Ｚｒから選択される１種以上の金属、炭化物、窒化物、酸化物もしくはその組み合わせから選択される金属及び／又は化合物を少なくとも１種以上含有することを特徴とする被覆超硬エンドミルである。上記構成を採用することにより、基体と硬質皮膜との密着性に優れ、高硬度化することが可能となり、その結果、優れた耐摩耗性を発揮する本発明の被覆超硬エンドミルを完成させた。
【０００６】
本発明硬質皮膜は、θ−２θ法によるＸ線回折で測定される岩塩構造型の（１１１）面の回折強度をＩ（１１１）、（２００）面の回折強度をＩ（２００）とした時、０．３＜Ｉ（２００）／Ｉ（１１１）＜１２である場合、硬質皮膜内に残留する圧縮応力が低減され、基体との密着性に優れるとともに、皮膜硬度並びに耐酸化性改善への寄与が大きい。また、ナノインデンテーションによる硬度測定法により接触深さと最大荷重時の最大変位量が求められる（Ｗ．Ｃ．ＯｌｉｖｅｒａｎｄＧ．Ｍ．Ｐｈａｒｒ：Ｊ．Ｍａｔｅｒ．Ｒｅｓ．，Ｖｏｌ．７，Ｎｏ．６，Ｊｕｎｅ、１９９２、１５６４−１５８３）。
この数値を用いて、
Ｅ＝１００−｛（接触深さ）／（最大荷重時の最大変位量）｝
の数式で、弾性回復率Ｅを定義し、２８％≦Ｅ≦４０％とすることにより、耐摩耗性と密着性のバランスが最適となる。更に、該硬質皮膜の最表面から深さ方向に５００ｎｍ以内の深さ領域で酸素濃度が最大となる場合、耐高温酸化特性並びに耐摩耗特性改善に極めて有効である。また、本願発明の硬質皮膜は、硬質皮膜表面の凸部を機械的処理により平滑にすると、表面の摩擦係数が低減しこれによって切屑排出性が改善される。本発明の基体に用いる超硬合金母材は、タングステンカーバイドの平均粒径が０．２μｍ以上、０．７μｍ未満であり、且つＣｏ含有量が重量％で３．０以上８．２未満であり、ロックウェル硬度がＨＲＡで９３．０以上９４．５未満であることが好ましい。
【０００７】
【発明の実施の形態】
本発明の硬質皮膜を構成する金属元素の組成は、（Ａｌ_ｘＣｒ_{１−ｘ−ｙ}Ｓｉ_ｙ）において、ｘが０．４５＜ｘ＜０．８５、ｙが０≦ｙ＜０．３５、０．５０≦ｘ＋ｙ＜１．０を満足する必要がある。ｘの値が０．４５以下、またｘ＋ｙの値が０．５よりも少なくなる場合では皮膜硬度並びに耐高温酸化特性の改善効果が十分ではなく、ｘの値が０．８５以上またはｘ＋ｙの値が１の場合、皮膜硬度の著しい低下を招き耐摩耗性に劣る。またｙの値が０．３５以上では、硬質皮膜内に残留する圧縮応力が過大になり、被覆直後に自己破壊を誘発するなどの基体密着強度を著しく低下させる場合がある。非金属元素の組成は、（Ｎ_{１−α−β−γ}Ｂ_αＣ_βＯ_γ）において、αは０．１５以上では皮膜が脆化し、好ましいαの上限値は０．０７である。硼素の添加は被加工物との耐溶着性と高温環境下での摩擦係数を低減し、潤滑性を向上させる効果がある。βは０．６５以上で皮膜が著しく脆化する。炭素の含有量の上限値は、炭素を含有する層厚に依存する。炭素を含有する層厚が０．５μｍ未満であれば、βの上限値は０．５である。炭素の添加は硬質皮膜の硬度を高めると同時に、摩擦係数を低減し、潤滑性を向上させる効果がある。γは０を超えて大きく、０．６５未満にすることが必要である。γが０の場合、耐高温酸化特性並びに皮膜硬度が充分ではなく耐摩耗性に乏しい。０．６５以上でも皮膜硬度が低下する。好ましいγの値は、酸素を含有する層厚に依存するが、０．５μｍ未満であれば、γの上限値は０．３である。酸素の添加は、硬質皮膜内に残留する圧縮応力を低減し、基体と皮膜との密着性を向上させる作用に加え、皮膜が緻密化することによる高硬度化と酸素の拡散経路である基体と垂直方向の結晶粒界を減少させることより、耐高温酸化性の改善に効果的である。更に、金属元素のＡｌ、Ｃｒ、Ｓｉに対する非金属元素のＮ、Ｂ、Ｃ、Ｏの比は、化学量論的に（Ｎ、Ｂ、Ｃ、Ｏ）／（Ａｌ、Ｃｒ、Ｓｉ）＞１．０がより好ましい。
【０００８】
本発明の硬質皮膜はθ−２θ法によるＸ線回折において測定される岩塩構造型の（２００）面に回折強度を有し、その回折ピークの２の半価幅が、０．５度以上、２．０度以下とした。その理由は、０．５未満の場合は結晶粒が粗大化し、皮膜硬度並びに高温酸化特性が充分ではなく、耐摩耗性に乏しく、２．０を超えると皮膜が脆化し、基体密着強度を著しく劣化させるためである。
【０００９】
硬質皮膜はＸ線光電子分光分析にて、５２５ｅＶから５３５ｅＶの範囲に少なくともＡｌ、Ｃｒ及び／又はＳｉと酸素との結合エネルギーを有することが必要である。これは、これら金属元素が酸素との結合を有することにより、皮膜が緻密化し高硬度化され、さらに酸化雰囲気において酸素の拡散経路となる基体に対して垂直方向の結晶粒界が減少し、酸素の内向拡散を抑制する機能を有することによるものである。本発明皮膜の特徴である、Ｃｒ、Ａｌ及び／又はＳｉと酸素との結合状態を形成するには、最適な被覆条件と一定以上の酸素を硬質皮膜内に含有させることが必要である。
【００１０】
超硬エンドミルの被覆基体は、Ｃｏ含有量が重量％で２．０＜Ｃｏ＜１４．０の範囲であり、Ｃｒ、Ｔａ、Ｔｉ、Ｚｒから選択される１種以上の金属、炭化物、窒化物、酸化物もしくはその組み合わせから選択される金属及び／又は化合物を少なくとも１種以上含有することとする。Ｃｏ含有量が２．０重量％以下となる場合は、切刃のチッピングが発生し易くなり、超硬エンドミルとしての特性を充分に発揮できない場合がある。１４．０重量％以上の場合、切刃の塑性変形が大きくなる傾向にあり、異常摩耗が発生し易くなる。好ましくは、３．０以上８．２未満である。これらの構成により、エンドミルによる切削加工の高速化並びに長寿命化を達成することが可能となる。
【００１１】
被覆超硬エンドミルにおいて、該硬質皮膜のθ−２θ法によるＸ線回折で測定される岩塩構造型の（１１１）面の回折強度をＩ（１１１）、（２００）面の回折強度をＩ（２００）とした時、０．３＜Ｉ（２００）／Ｉ（１１１）＜１２とすることが好ましい。皮膜の密着性は残留圧縮応力に強く依存し、この残留圧縮応力は被覆条件であるイオンエネルギーに強く依存している。即ち、イオンエネルギーが低い条件下では皮膜の残留圧縮応力は低い結果となる。逆に、イオンエネルギーが高い条件下では皮膜の残留圧縮応力は高い結果となる。ここで、イオンエネルギーを決定する要素は、具体的には成膜条件であるバイアス電圧、反応ガス圧力であり、これによって制御することができる。本発明は、残留圧縮応力が高い場合、Ｘ線回折において皮膜は（１１１）面に強く配向し、皮膜の硬度も、この高い残留圧縮応力の影響を受けて高硬度とする事が可能となる。一方、皮膜の密着性に着目すると、硬質皮膜内の残留圧縮応力を高くすると、皮膜の高硬度化を達成できるが、基体と皮膜界面近傍においてせん断応力が増大する方向に作用するため、密着性を損なうこととなり、好ましくない。従って、基体と皮膜との密着性及び皮膜硬度とのバランスを最適に制御することが重要となる。本発明では、０．３＜Ｉ（２００）／Ｉ（１１１）＜１２とすることにより、両者のバランスを最適に制御することを可能にした。
【００１２】
ナノインデンテーションによる硬度測定法によるＥは、２８％≦Ｅ≦４０％であり、皮膜の成膜条件であるバイアス電圧、反応ガス圧やその分圧比、成膜時の基体温度を最適に制御することにより達成でき好ましい。Ｅが４０％を超える場合、硬質皮膜内に残留圧縮応力が高くなり過ぎて靭性に乏しくなり密着性を劣化させる場合がある。３０％よりも小さくなる場合は強度不足による異常摩耗等により耐摩耗性が十分でない場合が確認された。さらに好ましいＥの値は３０％〜３５％である。
【００１３】
更に、該硬質皮膜の最表面から深さ方向に５００ｎｍ以内の深さ領域で酸素濃度が最大となる場合、特に切削寿命に優れ好ましい。切削過程における硬質皮膜の酸化は硬質皮膜最表面からの酸素の拡散が支配的である。従って、硬質皮膜表面を酸素リッチにすることにより、結晶が緻密化し酸素の拡散経路となる基体と垂直方向成分の結晶粒界を減少させることができ、より耐高温酸化特性に優れ切削寿命が向上する。また、硬質皮膜最表面を酸素リッチにすることにより、切り屑流れを助長する効果も確認され、潤滑特性を改善することが可能となり好ましい。
【００１４】
本発明の皮膜を被覆し、被覆基体表面の研磨面や研削面に沿った硬質皮膜表面の凸部や、被覆中に発生したマクロ粒子等の付着により凸部が形成される場合があるため、その凸部を機械的処理により平滑にすることにより、切屑除去効果に更に優れ望ましい。更に、被覆後に切刃エッジに機械的処理を施すことにより、なじみ効果も確認され、耐欠損、耐チッピング特性を改善することができ、より好ましい皮膜超硬エンドミルを得ることができる。
【００１５】
被覆超硬エンドミルの超硬合金母材内におけるタングステンカーバイドの平均粒径が０．２μｍ以上０．７μｍ未満、ロックウェル硬度がＨＲＡで９３．０以上９４．５未満である場合、本発明の硬質皮膜との密着強度に特に優れるとともに、高速切削加工で安定した切削寿命を示し、より好ましい被覆超硬エンドミルが得られる。
【００１６】
本発明である該硬質皮膜は、アークイオンプレーティング法による被覆により、基体との密着性に特に優れ、緻密で耐高温酸化特性、高硬度を有する極めて長寿命を有する被覆超硬エンドミルが得られる。
【００１７】
該硬質皮膜の結晶粒のアスペクト比について、本発明の皮膜破断面の膜厚Ｔについて、膜厚Ｔの２５％から５０％の厚みであるＴ１に相当する上下膜厚方向の上端位置と下端位置とを求める。この時、上端位置と下端位置は、Ｔ／２に相当する基準位置より上下膜厚方向に略均等となる様に割り振る。各上下端位置における水平方向の上端側粒径Ｋと下端側粒径Ｌを求める。そこで、アスペクト比をＴ１／（（Ｋ＋Ｌ）／２）とすると、柱状結晶構造からなる該硬質皮膜の結晶粒のアスペクト比が、０．２から１２である。アスペクト比が１２を超えて大きくなると、結晶粒が膜厚方向に細長くなり、皮膜の靭性が低下し好ましくない。０．２未満では粒状結晶が増加する傾向となり、皮膜硬度が低下し好ましくない。更に、該硬質皮膜の残留圧縮応力が、０．５ＧＰａ以上、４．０ＧＰａ以下であることが、硬質皮膜に靭性を持たせ、皮膜硬度と基体密着性とのバランスに適した範囲となり、性能の改善に効果的である。
【００１８】
更に、本発明の硬質皮膜において金属成分の１０原子％未満を周期律表の４ａ、５ａ、６ａ族の金属成分の少なくとも１種以上で置き換えた場合、また本発明に関わる硬質皮膜を１層以上含有する複層構造においても、同様な効果が確認され好ましく、本発明の技術的範囲に含まれるものである。以下、実施例に基づき、本発明を具体的に説明する。
【００１９】
【実施例】
（実施例１）
成膜には酸素を３２００ｐｐｍ含有した粉末法により作成した合金ターゲットを用い、基本となる被覆条件は、反応ガスを真空装置内に導入後、全圧を１０Ｐａ、バイアス電圧を−１２０Ｖ、被覆温度を４５０℃、膜厚を約３．５ｍとし、（Ａｌ０．６５Ｃｒ０．３５）（Ｎ０．８０Ｃ０．０８Ｏ０．１０Ｂ０．０２）からなる硬質皮膜を被覆し、本発明例１とした。皮膜組成は、電子プローブＸ線マイクロアナリシス及びオージェ電子分光法により決定した。硬質皮膜の酸素との結合状態を解析するためのＸ線光電子分光分析は、ＰＨＩ社製１６００Ｓ型Ｘ線光電子分光分析装置を用い、Ｘ線源はＭｇＫαを用い４００Ｗとし、分析領域を直径０．４ｍｍの円内部を分析した。十分に脱脂洗浄した後、真空装置内で硬質皮膜表面に付着した汚染物質等を除去するために５分間Ａｒイオンガンを用いて表面をエッチングした後、ワイドスペクトルを測定し、更に３０秒間エッチングした後、ナロースペクトルを測定した。ＡｒイオンガンによるエッチングレートはＳｉＯ２換算で１．９ｎｍ／分であった。本発明例１のＸ線光電子分光分析結果を図１に示す。図１は結合エネルギーが５３０ｅＶ近傍のナロースペクトル示し、Ｃｒ−Ｏ及びＡｌ−Ｏの結合の存在を示す。図２はＣｒ−Ｎ及びＣｒ−Ｏの結合の存在を示す。図３はＡｌ−Ｎ及びＡｌ−Ｏの結合の存在を示す。図４は、本発明例１のθ−２θ法によるＸ線回折結果を示す。
【００２０】
（実施例２）
実施例１と同様に、（Ａｌ_ｘＣｒ_{１−ｘ−ｙ}Ｓｉ_ｙ）（Ｎ_０．９５Ｏ_０．０５）を成膜し、比較例２、ｘ＝０．２０、ｙ＝０、比較例３、ｘ＝０．３０、ｙ＝０、本発明例４、ｘ＝０．５０、ｙ＝０、本発明例５、ｘ＝０．６０、ｙ＝０、本発明例６、ｘ＝０．７０、ｙ＝０、本発明例７、ｘ＝０．８０、ｙ＝０及び（ＡｌｘＣｒ１−ｘ）Ｎ系の比較例８、ｘ＝９０、ｙ＝０、従来例９、ｘ＝０．２０、従来例１０、ｘ＝０．５０、従来例１１、ｘ＝０．７０、を製作し、押込硬さを測定した。試験機は微小押込み硬さ試験機を用い、圧子はダイヤモンド製の対稜角１１５度の三角錐圧子を用い、最大荷重を４９ｍＮ、荷重負荷ステップ４．９ｍＮ／ｓｅｃ、最大荷重時の保持時間は１秒とした。測定試料は、硬質皮膜断面を５度で傾斜させ鏡面加工したものを用い、膜厚が２〜３μｍになる測定位置において、１０点測定しその平均値を求めた。尚、本発明皮例４〜７のＸ線光電子分光分析結果から５２５ｅＶから５３５ｅＶの範囲に、Ａｌ、Ｃｒ及び／又はＳｉと酸素との結合エネルギーが存在することを確認した。図５より、本発明例４〜７、Ａｌ添加量、４５〜８５原子％の範囲で、酸素を含有しない従来例より著しい硬化が確認された。本発明の硬質皮膜は、酸素を含有し、且つ金属元素と酸素の結合を形成する事により、高硬度となり、４０ＧＰａ以上の硬度を得ることが出来る。これによって密着性並びに耐摩耗性に優れた被覆超硬エンドミルが得られる。
【００２１】
（実施例３）
超硬合金を基体に用い、表１に示す皮膜組成の、本発明例１２〜２２、比較例２３〜３０及び従来例１０を製作した。被覆条件は実施例１に準ずる。表１に皮膜の組成等を示す。
【００２２】
【表１】

【００２３】
表１の試料を用いて、大気中１１００℃の酸化条件で処理した皮膜の酸化層の厚さ、実施例２同様に微小押込み硬さ、薄板の変形量より算出した残留圧縮応力、弾性回復率を測定した。表１より、酸化層厚さは、本発明例１２〜２２は、殆ど酸化進行が無く、耐高温酸化特性に優れていることが確認された。従来例１０は酸化進行が著しく、硬質皮膜は殆ど酸化物となり、酸素の内向拡散が激しく、酸化層は基体まで到達していた。押込み硬さも炭素、硼素を含有させることにより、更に高硬度となる。残留圧縮応力は、本発明例１２〜２２は低く、更に、図６に示す、本発明例１２及び従来例１０の荷重変位曲線より、本発明例１２は、最大荷重時における最大変位量が大きいにもかかわらず、塑性変形量が小さい。すなわち、同一応力が硬質皮膜に作用した際、弾性回復する割合が大きく、被覆基体の塑性変形に追従し易く、また塑性変形し難いことを示すものである。この荷重変位曲線より弾性回復率Ｅを求めた。Ｅが大きい程、弾性回復特性に優れる。表１より、本発明例１２〜２２は弾性回復特性に優れ、硬質皮膜の剥離やクラックの低減が可能となり、密着性に優れた硬質皮膜を得ることができる。これは、皮膜硬度差よりも大きな効果がある。
【００２４】
次に、表１の本発明例及び比較例を用いて圧痕試験による皮膜剥離状況を併記する。測定はロックウェル硬度計により１４７０Ｎの荷重で圧痕を形成し、光学顕微鏡により圧痕周辺部の剥離状況を観察した。本発明例１２〜２２は剥離が無く、優れた密着性を示した。これは本発明例が適正なＥ値の範囲内にあるためである。比較例２３〜３０、従来例１０は被覆基体の塑性変形に追従することができず、圧痕周辺部に膜剥離が発生した。
【００２５】
（実施例４）
表１に示す本発明例１２から２２、比較例２３から３０及び従来例１０の硬質皮膜を外径８ｍｍ、６枚刃、超硬エンドミルに被覆した。被覆条件は実施例１に準ずる。表１に示す本発明例１２から２２、比較例２３から３０及び従来例１０の被覆超硬エンドミルを用いて、下記条件の切削試験を行いエンドミルが切削不能に至るまでの時間を表１に併記する。
（切削諸元）
切削方法：側面加工
被削材：ＳＫＤ１１（硬さＨＲＣ６３）
切り込み：Ａｄ８ｍｍ、Ｒｄ０．２ｍｍ
切削速度：２００ｍ／ｍｉｎ
送り：０．０６ｍｍ／刃
切削油：無し（乾式エアーブロー）
【００２６】
表１より、本発明例１２から２２の超硬合金を基体とした被覆超硬エンドミルは、従来例１０と比較して切削不能に至るまでの切削時間が長く、耐摩耗性に優れている。本発明例１３は本発明皮膜被覆後にダイヤモンド粒子を含有した粒子を工具すくい面に投射することにより、硬質皮膜表面を平滑にしたが、本発明例１２と比較しても、より切削寿命が延長している。本発明例２１は硬質皮膜最表面の酸素濃度が高く、硬質皮膜内部が硬質皮膜最表面に比べ、低い場合の発明例を示すが、極めて寿命が長い。比較例２３は被覆条件をバイアス電圧−５００Ｖで被覆した硬質皮膜のＸ線回折による最強強度面指数が（２２０）面を示し、Ｉ（２００）／Ｉ（１１１）の値が０．２となり、本発明例に比べて切削寿命が短い。比較例２４はターゲットに含有する酸素濃度が１２００ｐｐｍからなるターゲットを使用した場合を示すが、Ｘ線光電子分光分析により酸化物としての結合状態が確認されず、本発明例に比べて切削寿命が短い。比較例２５は超硬母材中のＣｏ含有量が１５．０重量％の場合の比較例であるが本発明例に比較して、寿命が短い。比較例２６は、超硬合金母材中にＷＣ−Ｃｏ以外に添加元素がない場合の比較例であるが寿命が短い。比較例２７はＡｌ含有量が２０原子％の場合であり、弾性回復率が２８よりも低く、切削寿命が短く、耐摩耗性が十分ではないことを示す。比較例２８はＡｌ含有量が９０原子％の場合であり、切削寿命が短く耐摩耗性に劣る。比較例２９は酸素含有量が６８原子％の場合であるが、耐摩耗性が十分ではない。比較例３０はＡｌ含有量が４３原子％の場合であるが耐摩耗性が十分ではない。
【００２７】
【発明の効果】
本願発明の被覆超硬エンドミルを適用することにより、過酷な切削加工に用いても十分な耐摩耗性を有し、基体表面とその直上の硬質皮膜との密着性改善を図り、更に高硬度で耐高温酸化特性に優れた被覆超硬エンドミルを得ることが出来た。
【図面の簡単な説明】
【図１】図１は、本発明例のＣｒ−Ｏ及びＡｌ−Ｏの結合エネルギーを示す。
【図２】図２は、本発明例のＣｒ−Ｎ及びＣｒ−Ｏの結合エネルギーを示す。
【図３】図３は、本発明例のＡｌ−Ｎ及びＡｌ−Ｏの結合エネルギーを示す。
【図４】図４は、本発明例のＸ線回折結果を示す。
【図５】図５は、本発明例と従来例のＡｌ添加量と皮膜硬度の関係を示す。
【図６】図６は、本発明例１２及び従来例１０の荷重変位曲線を示す。[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a coated carbide end mill that exhibits excellent wear resistance by coating a hard coating useful as a surface coating material of a carbide end mill used for cutting a mold, a machine component, and the like.
[0002]
[Prior art]
Patent Literatures 1 to 3 shown below are disclosed as AlCr-based coatings as hard coating materials having excellent resistance to high-temperature oxidation.
[Patent Document 1] Japanese Patent No. 3027502 (page 6, FIG. 1)
[Patent Document 2] Japanese Patent No. 3039381 (page 4, FIG. 1)
[Patent Document 3] JP-A-2002-160129 (page 3, FIG. 1)
[0003]
With the cost reduction of cutting, high-efficiency cutting, that is, high-speed cutting and high-feed cutting, have been performed, and the cutting temperature near the carbide end mill cutting edge has been significantly improved. As a result, it is desired that the hard coating coated on the surface of the carbide end mill also has excellent wear resistance under high-temperature and / or high-pressure wear environments. Development of a coated carbide end mill coated with an excellent hard coating has been desired. Patent Literature 1 discloses an AlCr-based hard film selected from AlCr and one of C, N, and O as a metal component, and an example relating to an amorphous film having high hardness. However, the hardness of this amorphous film is at most about 21 GPa Knoop hardness, and the wear resistance is not improved as a carbide end mill, and the adhesion is not sufficient. The hard coatings disclosed in Patent Literature 2 and Patent Literature 3 are nitrides of AlCr and have a high-temperature oxidation resistance of about 1000 ° C, but the oxidation resistance at a temperature of 1000 ° C or higher has been studied. Absent. The hardness is about 21 GPa Vickers hardness, the hardness is not sufficiently improved, and the wear resistance is poor.
[0004]
[Problems to be solved by the invention]
The present invention provides a coated carbide end mill that solves the above problems and significantly improves wear resistance by increasing hardness, which is a disadvantage of (AlCr) N-based coatings, and as a result, exhibits excellent tool life. The purpose is to do.
[0005]
[Means for solving the problem]
The present invention provides a coated cemented carbide end mill, the coating is a hard film coated by arc discharge type ion plating method, the rigid _{_{_{coating, (Al x Cr 1-x}}} -y Si y) (N 1- _{_{α-β-γ B α C}} β O γ), where, x, y, α, β , γ represents a respective atomic ratio, 0.45 <x <0.85,0 ≦ y <0.35,0 .50 ≦ x + y <1.0, 0 ≦ α <0.15, 0 ≦ β <0.65, 0 <γ <0.65, 0 <α + β + γ ≦ 1.0 has a diffraction intensity on the (200) plane of the rock salt structure type measured by X-ray diffraction by the θ-2θ method, and a half-value width of a diffraction peak thereof is 0.5 degrees or more and 2.0 degrees or less; In the range of 525 eV to 535 eV in the X-ray photoelectron spectroscopy, at least the bonding between Al, Cr and / or Si and oxygen is performed. Energy, the coated substrate of the cemented carbide end mill has a Co content of 2.0 <Co <14.0% by weight, and one or more metals selected from Cr, Ta, Ti, and Zr; A coated carbide end mill comprising at least one or more metals and / or compounds selected from carbides, nitrides, oxides or combinations thereof. By adopting the above configuration, excellent adhesion between the substrate and the hard coating can be achieved, and high hardness can be obtained. As a result, a coated carbide end mill of the present invention exhibiting excellent wear resistance has been completed. .
[0006]
In the hard coating of the present invention, when the diffraction intensity of the (111) plane of the rock salt structure type measured by X-ray diffraction by the θ-2θ method is I (111), and the diffraction intensity of the (200) plane is I (200). , 0.3 <I (200) / I (111) <12, the compressive stress remaining in the hard coating is reduced, the adhesion to the substrate is excellent, and the hardness of the coating and the improvement of the oxidation resistance are improved. Large contribution. The contact depth and the maximum displacement at the time of the maximum load are determined by a hardness measurement method using nanoindentation (WC Oliver and GM Phar: J. Mater. Res., Vol. 7, No. 6). , June, 1992, 1564-1584).
Using this number,
E = 100-{(contact depth) / (maximum displacement at maximum load)}
The elastic recovery ratio E is defined by the following formula, and by setting 28% ≦ E ≦ 40%, the balance between wear resistance and adhesion is optimized. Furthermore, when the oxygen concentration is maximum in a depth region within 500 nm in the depth direction from the outermost surface of the hard coating, it is extremely effective for improving high-temperature oxidation resistance and wear resistance. Further, in the hard coating of the present invention, when the projections on the surface of the hard coating are smoothed by mechanical treatment, the coefficient of friction of the surface is reduced, thereby improving the chip dischargeability. The cemented carbide base material used for the substrate of the present invention has an average particle size of tungsten carbide of 0.2 μm or more and less than 0.7 μm, and a Co content of 3.0% or more and less than 8.2 in weight%. It is preferable that the Rockwell hardness is 93.0 or more and less than 94.5 in HRA.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
The composition of the metal elements constituting the hard coating of the present _{_{invention, (Al x Cr 1-x}} -y Si y) in, x is from 0.45 <x <0.85, y is 0 ≦ y <0.35, It is necessary to satisfy 0.50 ≦ x + y <1.0. When the value of x is 0.45 or less and the value of x + y is less than 0.5, the effect of improving the film hardness and the high-temperature oxidation resistance is not sufficient, and the value of x is 0.85 or more or the value of x + y. Is 1, the hardness of the film is remarkably reduced, and the wear resistance is poor. If the value of y is 0.35 or more, the compressive stress remaining in the hard film becomes excessive, and the self-destruction may be induced immediately after coating, and the substrate adhesion strength may be significantly reduced. As for the composition of the nonmetal element, in (N1- [ _{alpha]-[beta]-[gamma]} B [ _alpha] C [ _beta] O [ _gamma] ), when [alpha] is 0.15 or more, the coating becomes brittle, and the preferable upper limit of [alpha] is 0.07. The addition of boron has the effect of reducing the welding resistance to the workpiece and the coefficient of friction in a high-temperature environment, and improving the lubricity. When β is 0.65 or more, the film becomes extremely brittle. The upper limit of the carbon content depends on the thickness of the layer containing carbon. If the thickness of the layer containing carbon is less than 0.5 μm, the upper limit of β is 0.5. The addition of carbon has the effect of increasing the hardness of the hard coating, reducing the coefficient of friction, and improving lubricity. γ is larger than 0 and must be less than 0.65. When γ is 0, the high-temperature oxidation resistance and the film hardness are insufficient and the wear resistance is poor. Even with 0.65 or more, the film hardness decreases. The preferred value of γ depends on the thickness of the layer containing oxygen, but if it is less than 0.5 μm, the upper limit of γ is 0.3. The addition of oxygen reduces the compressive stress remaining in the hard coating and improves the adhesion between the base and the coating. The reduction of the vertical grain boundaries is effective in improving the high-temperature oxidation resistance. Further, the ratio of N, B, C, O of the non-metallic element to Al, Cr, Si of the metal element is stoichiometrically ((N, B, C, O) / (Al, Cr, Si)> 1). .0 is more preferred.
[0008]
The hard coating of the present invention has a diffraction intensity on the (200) plane of the rock salt structure type measured by X-ray diffraction by the θ-2θ method, and the half width of the diffraction peak 2 is 0.5 ° or more, 2.0 degrees or less. The reason is that if it is less than 0.5, the crystal grains become coarse, the film hardness and high-temperature oxidation characteristics are not sufficient, and the abrasion resistance is poor, and if it exceeds 2.0, the film becomes brittle and the substrate adhesion strength is remarkably increased. This is for deteriorating.
[0009]
The hard coating needs to have at least the binding energy between Al, Cr and / or Si and oxygen in the range of 525 eV to 535 eV by X-ray photoelectron spectroscopy analysis. This is because these metal elements have a bond with oxygen, so that the film becomes denser and harder, and furthermore, in an oxidizing atmosphere, crystal grain boundaries in a direction perpendicular to a substrate serving as a diffusion path of oxygen are reduced, and oxygen is reduced. This has the function of suppressing the inward diffusion of the In order to form the bonding state of Cr, Al and / or Si and oxygen, which are the characteristics of the coating of the present invention, it is necessary to contain optimal coating conditions and a certain amount or more of oxygen in the hard coating.
[0010]
The coated substrate of the carbide end mill has a Co content in the range of 2.0 <Co <14.0 in weight%, and at least one metal, carbide, or nitride selected from Cr, Ta, Ti, and Zr. , An oxide or a combination thereof, at least one metal and / or compound. If the Co content is 2.0% by weight or less, chipping of the cutting edge is likely to occur, and the characteristics as a carbide end mill may not be sufficiently exhibited. When the content is 14.0% by weight or more, the plastic deformation of the cutting edge tends to increase, and abnormal wear easily occurs. Preferably, it is 3.0 or more and less than 8.2. According to these configurations, it is possible to achieve high-speed cutting and long life of cutting by the end mill.
[0011]
In the coated carbide end mill, the diffraction intensity of the (111) plane of the rock salt structure type measured by X-ray diffraction by the θ-2θ method of the hard coating is I (111), and the diffraction intensity of the (200) plane is I (200). ), It is preferable that 0.3 <I (200) / I (111) <12. The adhesion of the film strongly depends on the residual compressive stress, and the residual compressive stress strongly depends on the ion energy which is a coating condition. That is, under the condition that the ion energy is low, the result is that the residual compressive stress of the film is low. Conversely, under conditions of high ion energy, the residual compressive stress of the coating is high. Here, the factors that determine the ion energy are, specifically, the bias voltage and the reaction gas pressure, which are the film forming conditions, and can be controlled by this. According to the present invention, when the residual compressive stress is high, the film is strongly oriented to the (111) plane in X-ray diffraction, and the hardness of the film can be made high due to the influence of the high residual compressive stress. . On the other hand, focusing on the adhesion of the coating, if the residual compressive stress in the hard coating is increased, the hardness of the coating can be increased. However, since the shear stress acts in the direction near the interface between the base and the coating, the adhesion increases. Is impaired, which is not preferable. Therefore, it is important to optimally control the balance between the adhesion between the substrate and the coating and the hardness of the coating. In the present invention, by setting 0.3 <I (200) / I (111) <12, it is possible to optimally control the balance between the two.
[0012]
E according to a hardness measurement method by nanoindentation is 28% ≦ E ≦ 40%, and optimally controls a bias voltage, a reaction gas pressure, a partial pressure ratio thereof, and a substrate temperature during film formation, which are film formation conditions. This is preferable because it can be achieved. If E exceeds 40%, the residual compressive stress in the hard coating may be too high, resulting in poor toughness and poor adhesion. When it is less than 30%, it was confirmed that the wear resistance was not sufficient due to abnormal wear due to insufficient strength. A more preferred value of E is 30% to 35%.
[0013]
Furthermore, when the oxygen concentration becomes maximum in a depth region within 500 nm in the depth direction from the outermost surface of the hard coating, the cutting life is particularly excellent, which is preferable. Oxidation of the hard coating in the cutting process is dominated by diffusion of oxygen from the outermost surface of the hard coating. Therefore, by making the surface of the hard coating oxygen-rich, the crystal becomes denser and the crystal grain boundary of the component in the vertical direction with respect to the substrate serving as the diffusion path of oxygen can be reduced, and the high-temperature oxidation resistance is excellent and the cutting life is improved. I do. Further, by making the outermost surface of the hard coating oxygen-rich, an effect of promoting the flow of chips is also confirmed, and lubrication characteristics can be improved, which is preferable.
[0014]
Coating the coating of the present invention, the convex portion of the hard coating surface along the polished surface or the ground surface of the coated substrate surface, since convex portions may be formed by adhesion of macroparticles and the like generated during coating, By smoothing the projections by mechanical treatment, it is desirable to further improve the chip removal effect. Further, by applying a mechanical treatment to the cutting edge after coating, a conforming effect is also confirmed, and the fracture resistance and chipping resistance can be improved, and a more preferable coated carbide end mill can be obtained.
[0015]
When the average particle size of tungsten carbide in the cemented carbide base material of the coated cemented carbide end mill is 0.2 μm or more and less than 0.7 μm and the Rockwell hardness is 93.0 or more and less than 94.5 in HRA, the hardness of the present invention is obtained. The adhesive strength with the film is particularly excellent, and a stable cutting life is exhibited by high-speed cutting, so that a more preferable coated carbide end mill can be obtained.
[0016]
The hard coating according to the present invention is coated with an arc ion plating method, whereby a coated carbide end mill having particularly excellent adhesion to a substrate, dense, high-temperature oxidation resistance, high hardness and extremely long life can be obtained. .
[0017]
Regarding the aspect ratio of the crystal grains of the hard coating, the upper and lower positions in the upper and lower film thickness directions corresponding to T1, which is 25% to 50% of the film thickness T of the film fracture surface of the present invention. And ask. At this time, the upper end position and the lower end position are allocated so as to be substantially equal in the upper and lower film thickness directions from the reference position corresponding to T / 2. The upper-side particle diameter K and the lower-side particle diameter L in the horizontal direction at each upper and lower end position are obtained. Therefore, assuming that the aspect ratio is T1 / ((K + L) / 2), the aspect ratio of the crystal grains of the hard coating having a columnar crystal structure is 0.2 to 12. If the aspect ratio exceeds 12 and becomes large, the crystal grains become elongated in the film thickness direction, and the toughness of the film decreases, which is not preferable. If it is less than 0.2, the number of granular crystals tends to increase, and the hardness of the film is undesirably reduced. Further, when the residual compressive stress of the hard film is 0.5 GPa or more and 4.0 GPa or less, the hard film has toughness, and is in a range suitable for a balance between the film hardness and the substrate adhesion. It is effective for improvement.
[0018]
Further, when less than 10 atomic% of the metal component in the hard coating of the present invention is replaced by at least one of the metal components belonging to groups 4a, 5a and 6a of the periodic table, one or more hard coatings according to the present invention are used. A similar effect is also confirmed in a multilayer structure containing the same, which is preferable and included in the technical scope of the present invention. Hereinafter, the present invention will be specifically described based on examples.
[0019]
【Example】
(Example 1)
An alloy target prepared by a powder method containing 3200 ppm of oxygen was used for the film formation. The basic coating conditions were as follows: after introducing a reaction gas into a vacuum apparatus, the total pressure was 10 Pa, the bias voltage was -120 V, and the coating temperature was At 450 ° C., the film thickness was set to about 3.5 m, and a hard coating made of (Al0.65Cr0.35) (N0.80C0.08O0.10B0.02) was applied to prepare Example 1 of the present invention. The coating composition was determined by electron probe X-ray microanalysis and Auger electron spectroscopy. The X-ray photoelectron spectroscopy for analyzing the bonding state of the hard film with oxygen was performed using a PHI 1600S type X-ray photoelectron spectrometer, the X-ray source was 400 KW using MgKα, and the analysis area was 0.4 mm in diameter. The inside of the 4 mm circle was analyzed. After sufficient degreasing and cleaning, the surface was etched using an Ar ion gun for 5 minutes in order to remove contaminants and the like adhering to the hard film surface in a vacuum device, and then a wide spectrum was measured. , And a narrow spectrum was measured. The etching rate by the Ar ion gun was 1.9 nm / min in terms of SiO2. FIG. 1 shows the results of X-ray photoelectron spectroscopy analysis of Example 1 of the present invention. FIG. 1 shows a narrow spectrum in which the binding energy is around 530 eV, and shows the presence of Cr—O and Al—O bonds. FIG. 2 shows the presence of Cr-N and Cr-O bonds. FIG. 3 shows the presence of Al—N and Al—O bonds. FIG. 4 shows an X-ray diffraction result of the present invention example 1 by the θ-2θ method.
[0020]
(Example 2)
In the same manner as in Example 1, (Al _x Cr _1-xy Si _y ) (N _0.95 O _0.05 ) was formed, and Comparative Example 2, x = 0.20, y = 0, Comparative Example 3, x = 0.30, y = 0, present invention example 4, x = 0.50, y = 0, present invention example 5, x = 0.60, y = 0, present invention example 6, x = 0 .70, y = 0, present invention example 7, x = 0.80, y = 0 and (AlxCr1-x) N-based comparative example 8, x = 90, y = 0, conventional example 9, x = 0. 20, Conventional Example 10, x = 0.50 and Conventional Example 11, x = 0.70, and the indentation hardness was measured. The tester used was a micro indentation hardness tester, and the indenter used was a triangular pyramid indenter made of diamond with a 115 ° confronting angle. The maximum load was 49 mN, the load step was 4.9 mN / sec, and the holding time at the maximum load was 1 Seconds. As the measurement sample, a hard film having a cross section inclined at 5 degrees and mirror-finished was used, and 10 points were measured at measurement positions where the film thickness became 2 to 3 μm, and the average value was obtained. From the results of X-ray photoelectron spectroscopy of the skin examples 4 to 7, it was confirmed that the binding energy of Al, Cr and / or Si and oxygen was present in the range of 525 eV to 535 eV. From FIG. 5, it was confirmed that in Examples 4 to 7 of the present invention and in the range of the addition amount of Al of 45 to 85 atomic%, remarkable hardening was observed as compared with the conventional example containing no oxygen. The hard coating of the present invention contains oxygen and forms a bond between a metal element and oxygen, thereby achieving a high hardness and a hardness of 40 GPa or more. As a result, a coated carbide end mill having excellent adhesion and wear resistance can be obtained.
[0021]
(Example 3)
Using cemented carbide for the substrate, Examples 12 to 22 of the present invention, Comparative Examples 23 to 30 and Conventional Example 10 having the coating compositions shown in Table 1 were produced. The coating conditions are the same as in Example 1. Table 1 shows the composition of the film and the like.
[0022]
[Table 1]

[0023]
Using the samples shown in Table 1, the thickness of the oxide layer of the film treated under the oxidation conditions of 1100 ° C. in the air, the microindentation hardness, the residual compressive stress calculated from the deformation of the thin plate as in Example 2, and the elastic recovery rate Was measured. From Table 1, it was confirmed that the oxidation layer thicknesses of Examples 12 to 22 of the present invention hardly proceeded with oxidation and were excellent in high-temperature oxidation resistance. In Conventional Example 10, the oxidation progressed remarkably, the hard film almost became an oxide, the inward diffusion of oxygen was intense, and the oxide layer reached the substrate. The indentation hardness is further increased by containing carbon and boron. Residual compressive stress is low in Examples 12 to 22 of the present invention. Further, from the load displacement curves of Examples 12 and 10 of the present invention shown in FIG. Nevertheless, the amount of plastic deformation is small. That is, when the same stress acts on the hard coating, the elastic recovery rate is large, indicating that it is easy to follow the plastic deformation of the coated substrate, and it is difficult to perform the plastic deformation. The elastic recovery rate E was determined from the load displacement curve. The larger the E, the better the elastic recovery characteristics. From Table 1, it can be seen that Examples 12 to 22 of the present invention are excellent in elastic recovery characteristics, enable peeling of the hard film and reduce cracks, and can provide a hard film having excellent adhesion. This has a greater effect than the film hardness difference.
[0024]
Next, the peeling state of the film by the indentation test will be described together with the present invention examples and comparative examples in Table 1. In the measurement, an indent was formed with a load of 1470 N using a Rockwell hardness tester, and the peeling state around the indent was observed using an optical microscope. Inventive Examples 12 to 22 showed no peeling and exhibited excellent adhesion. This is because the example of the present invention is within the range of an appropriate E value. Comparative Examples 23 to 30 and Conventional Example 10 could not follow the plastic deformation of the coated substrate, and film peeling occurred around the indentation.
[0025]
(Example 4)
The hard coatings of Inventive Examples 12 to 22, Comparative Examples 23 to 30 and Conventional Example 10 shown in Table 1 were coated on an 8 mm outer diameter, 6-flute, carbide end mill. The coating conditions are the same as in Example 1. Using the coated carbide end mills of Examples 12 to 22 of the present invention, Comparative Examples 23 to 30 and Conventional Example 10 shown in Table 1, a cutting test was performed under the following conditions, and the time until the end mill became uncuttable is also shown in Table 1. I do.
(Cutting specifications)
Cutting method: Side work material: SKD11 (hardness HRC63)
Cut: Ad8mm, Rd0.2mm
Cutting speed: 200m / min
Feed: 0.06 mm / blade Cutting oil: none (dry air blow)
[0026]
As shown in Table 1, the coated cemented carbide end mills using the cemented carbides of Examples 12 to 22 of the present invention as bases have a longer cutting time until cutting is impossible and are superior in wear resistance as compared with Conventional Example 10. In Invention Example 13, the hard coating surface was smoothed by projecting particles containing diamond particles onto the tool rake surface after coating the invention film, but the cutting life was longer than that of Invention Example 12. are doing. Invention Example 21 shows an invention example in which the oxygen concentration on the outermost surface of the hard film is high and the inside of the hard film is lower than the outermost surface of the hard film, but the life is extremely long. In Comparative Example 23, the strongest surface index by X-ray diffraction of a hard film coated at a bias voltage of -500 V under coating conditions shows a (220) plane, and the value of I (200) / I (111) becomes 0.2, The cutting life is shorter than that of the present invention. Comparative Example 24 shows the case where a target having an oxygen concentration of 1200 ppm contained in the target was used. However, the bonding state as an oxide was not confirmed by X-ray photoelectron spectroscopy, and the cutting life was shorter than that of the present invention. . Comparative Example 25 is a comparative example in which the Co content in the cemented carbide base material is 15.0% by weight, but has a shorter life than the inventive example. Comparative Example 26 is a comparative example in which there is no additional element other than WC-Co in the cemented carbide base material, but the life is short. Comparative Example 27 is a case where the Al content is 20 atom%, the elastic recovery is lower than 28, the cutting life is short, and the wear resistance is not sufficient. Comparative Example 28 was a case where the Al content was 90 atomic%, and the cutting life was short and the wear resistance was poor. Comparative Example 29 is a case where the oxygen content is 68 atomic%, but the abrasion resistance is not sufficient. In Comparative Example 30, the Al content was 43 atomic%, but the abrasion resistance was not sufficient.
[0027]
【The invention's effect】
By applying the coated carbide end mill of the present invention, it has sufficient abrasion resistance even when used for severe cutting, improves the adhesion between the substrate surface and the hard coating immediately above it, and further increases the hardness. A coated carbide end mill excellent in high temperature oxidation resistance was obtained.
[Brief description of the drawings]
FIG. 1 shows the binding energies of Cr—O and Al—O according to the present invention.
FIG. 2 shows the binding energies of Cr—N and Cr—O of the present invention.
FIG. 3 shows binding energies of Al—N and Al—O of the present invention.
FIG. 4 shows an X-ray diffraction result of an example of the present invention.
FIG. 5 shows the relationship between the amount of Al added and the film hardness of the present invention and the conventional example.
FIG. 6 shows load displacement curves of Example 12 of the present invention and Conventional Example 10.

Claims

In a coated carbide end mill, the coating is a hard coating coated by an arc discharge ion plating method, and the hard coating is (Al _x Cr _1-xy Si _y ) (N _{1-α-β- γ} B _α C _β O _γ , wherein x, y, α, β, and γ each represent an atomic ratio, and 0.45 <x <0.85, 0 ≦ y <0.35, 0.50 ≦ x + y <1.0, 0 ≦ α <0.15, 0 ≦ β <0.65, 0 <γ <0.65, 0 <α + β + γ ≦ 1.0. Has a diffraction intensity on the (200) plane of the rock salt structure type measured in X-ray diffraction by X-ray diffraction, and the half width of the diffraction peak is 0.5 degrees or more and 2.0 degrees or less, The binding energy of at least Al, Cr and / or Si and oxygen in the range of 525 eV to 535 eV in the analysis. Wherein the coated substrate of the cemented carbide end mill has a Co content of 2.0 <Co <14.0 by weight%, and at least one metal or carbide selected from Cr, Ta, Ti, and Zr. A coated carbide end mill comprising at least one metal and / or compound selected from a group consisting of a metal, a nitride, an oxide and a combination thereof.

2. The coated carbide end mill according to claim 1, wherein the diffraction intensity of the (111) plane of the rock salt structure type measured by X-ray diffraction according to the θ-2θ method of the hard coating is the diffraction of the I (111) and (200) planes. A coated carbide end mill characterized in that 0.3 <I (200) / I (111) <12 when the strength is I (200).

The coated superhard end mill according to claim 1 or 2, wherein the hard coating has an elastic recovery rate E obtained by measuring hardness by nanoindentation of 28% ≦ E ≦ 40%. Hard end mill.

4. The coated carbide end mill according to claim 1, wherein the oxygen concentration is maximum in a depth region within 500 nm in a depth direction from the outermost surface of the hard coating.

The coated carbide end mill according to any one of claims 1 to 4, wherein the projections on the surface of the hard coating are smoothed by mechanical treatment.

The coated cemented carbide end mill according to any one of claims 1 to 5, wherein the tungsten carbide in the cemented carbide base material has an average particle size of 0.2 µm or more and less than 0.7 µm, and has a Rockwell hardness of HRA of 93. A coated carbide end mill characterized by being at least 0.0 and less than 94.5.