JP2004106102A

JP2004106102A - Hard film coated tool

Info

Publication number: JP2004106102A
Application number: JP2002270940A
Authority: JP
Inventors: Kazuyuki Kubota; 久保田　和幸
Original assignee: Hitachi Tool Engineering Ltd
Current assignee: Moldino Tool Engineering Ltd
Priority date: 2002-09-18
Filing date: 2002-09-18
Publication date: 2004-04-08
Anticipated expiration: 2022-09-18
Also published as: JP3679076B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hard film coated tool wherein welding resistance under a high temperature state and diffusion of workpiece elements in a hard film are improved without sacrificing the abrasion resistance and adhesion performance of the hard film having conventional superior oxidation resistance, and drying, speeding up, and high-speed feeding of a cutting work are obtained. <P>SOLUTION: A single or more (a) layers comprising either of nitride, carbonitride, oxynitride, or oxycarbonitride, whose metal components are composed of Ti and B, and a single or more (b) layers comprising either of nitride, carbonitride, oxynitride, or oxycarbonitride, whose metal components are composed of Al and Ti, are alternately coated respectively. A lattice constant A of a surface in an X-ray diffraction of the (a) layer 200 is within the range of 0.4200≤A≤0.4270nm, peaks of c-BN and h-BN are detected in Raman spectroscopy of the (a) layer and, when the peak strength of the c-BN and the peak strength of the h-BN at that time are set to Q1 and Q2 respectively, the peak strength raio is Q1/Q2≥1.0. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明が属する技術分野】
本発明は、金属材料等の切削加工に使用される硬質皮膜被覆工具に関するものである。
【０００２】
【従来の技術】
従来はＴｉＮ、Ｔｉ（ＣＮ）等を被覆した切削工具が汎用的かつ一般的であった。ＴｉＮは比較的耐酸化性に優れるため、切削時の発熱によって生じる工具のすくい面摩耗に対して、優れた耐摩耗性を示すだけでなく、基体との密着性も良好であることが特長である。また、Ｔｉ（ＣＮ）は、ＴｉＮに比べ高硬度かつ被加工物から排出される切り粉との接触抵抗が低いため工具表面の発熱が抑制される。このことから、被削材との機械的な擦り摩耗によって工具逃げ面に生じるフランク摩耗を抑制することができる。しかしながら、金属加工の高能率化を目的とした切削速度の高速化傾向に対し、上記硬質皮膜では、十分な耐酸化性、耐摩耗性を示さなくなった。この様な背景から、皮膜の耐酸化性、耐摩耗性をより向上させる研究がなされ、その結果、特許第３２４８８９７号公報には（ＴｉＳｉ）Ｎ皮膜をａ層とし、（ＴｉＡｌ）Ｎ皮膜をｂ層として、ａ層とｂ層とを１層以上交互に被覆することによって得られた皮膜が耐酸化性、耐摩耗性を有するという技術が開示されている。一方、特開２００１−２９３６０１号公報では、耐摩耗性皮膜中に、ＢＮ、ＴｉＢ_２、ＴｉＢ等の超微粒化合物を含む皮膜についての開示があり、この超微粒化合物が非晶質構造を有し、皮膜の硬度を向上させる働きがあると記載されている。これにより耐摩耗性、高滑り性、高焼き付き性、被削材の加工精度向上が図れるとのことであるが、超微粒化合物の特性や存在状態についての詳細な記述はなされていない。
【０００３】
（ＴｉＡｌ）Ｎ皮膜は、その皮膜中に含有するＴｉとＡｌの成分比率又はＳｉやＣの皮膜中の含有量により異なるが、概略２３００〜２８００のビッカース硬さを有する。また、耐酸化性が前記ＴｉＮ、Ｔｉ（ＣＮ）に比べ著しく優れるため、刃先が高温に達する切削条件下においては、切削工具の性能をめざましく向上させる。また、（ＴｉＡｌＳｉ）（ＣＮ）皮膜は、（ＴｉＡｌ）Ｎ皮膜よりも耐酸化性を向上させようとＳｉを含有させたものである。更に、同じ効果を目論み、（ＴｉＡｌ）系に第３元素としてＺｒやＨｆ、Ｂの含有が試みられている。近年では、こうした硬質皮膜被覆切削工具が使用される環境は益々過酷になり、例えば、切削速度の高速化傾向、また従来使用されていた湿式での切削加工が環境問題上重要視されるなかで、乾式での切削加工が注目されている。また、金型用鋼材の多種含有元素の影響による鋼材の難削化、高能率加工を重視した高送り加工の傾向にあり、硬質皮膜被覆切削工具の使用環境は益々過酷なものとなってきている。
【０００４】
本発明者の研究によれば、大気中における（ＴｉＡｌ）Ｎ皮膜の酸化開始温度は、ＴｉＮの４５０℃に対し、Ａｌの含有量に依存して７５０〜９００℃に向上する。しかしながら、前述の乾式高速切削加工においては、使用する工具の刃先温度が９００℃以上の高温に達する。このような過酷の条件下で行われている切削加工では、硬質皮膜の耐酸化性が重要であることは言うまでもないが、それよりも先に硬質皮膜被覆切削工具の刃先部と被加工物が化学反応を起こすことで発生する、溶着現象を防ぐことが不可欠である。近年の金型用鋼材には金型の性能を著しく向上させるために様々な元素の含有が行われるようになり、切削工具への溶着現象は益々発生しやすくり、硬質皮膜の酸化による摩耗よりも先に硬質皮膜中への被加工物元素の拡散が発生しやすい状況になってきている。このため、従来のＴｉとＡｌの窒化物などは、大気中における酸化抵抗は著しく優れるものの、高温状態での切削においては、前記化学反応の１種である溶着や被加工物の拡散を防ぐことが困難であり、十分な工具寿命が得られないのが現状である。
【０００５】
【発明が解決しようとする課題】
本発明はこうした事情に鑑みなされたものであって、従来の耐酸化性の優れる（ＴｉＡｌ）Ｎ皮膜など、耐酸化性の優れる硬質皮膜の耐摩耗性並びに密着性を犠牲にすること無く、更に高温状態での耐溶着性並びに硬質皮膜中への被加工物元素の拡散を改善し、切削加工の乾式化、高速化、高送り化に対応する硬質皮膜被覆工具を提供することが目的である。
【０００６】
【課題を解決するための手段】
本発明者は、硬質皮膜の耐溶着性、耐摩耗性、母材との密着性に及ぼす、様々な元素との影響および皮膜の最適な層構造について鋭意研究を重ねた結果、金属成分が、ＴｉとＢで構成される窒化物、炭窒化物、酸窒化物、酸炭窒化物のいずれかであるａ層と、金属成分がＡｌとＴｉで構成される窒化物、炭窒化物、酸窒化物、酸炭窒化物のいずれかであるｂ層とが、それぞれ一層以上交互に被覆され、該ａ層のＸ線回折における（２００）面の格子定数Ａが、０．４２００≦Ａ≦０．４２７０ｎｍの範囲にあり、かつ該ａ層のラマン分光分析において、ｃ−ＢＮ並びにｈ−ＢＮのピークが検出され、そのときのｃ−ＢＮのピーク強度をＱ１、またｈ−ＢＮのピーク強度をＱ２としたときに、ピーク強度比Ｑ１／Ｑ２≧１．０であることを特徴とする硬質皮膜被覆工具とすることで、乾式の高速切削加工、高送り加工において、切削工具の性能が極めて良好となることをつきとめ本発明に到達した。ここでの高送り加工とは、切削条件中の１刃当たりの送り量が０．３ｍｍ／刃を越えるような切削と定義する。また、本発明は、該ａ層がＴｉとＢの合金ターゲットを用いて被覆され、皮膜の組成が、該ａ層に含まれるＢの含有量Ｍを金属成分のみの原子％で示すと、０．１≦Ｍ≦４０であり、該ａ層の膜厚Ｄが、Ｄ≧０．１μｍであることが好ましい。
【０００７】
【発明の実施の形態】
ａ層の構成について詳細を述べる。一般に（ＴｉＡｌ）Ｎ皮膜は、大気中で酸化テストを行うと、皮膜表面近傍のＡｌが最表面に向かって外向拡散し、Ａｌ_２Ｏ_３層を形成する。この現象により、その後の皮膜内への酸素の進入が抑制される。本発明者の研究によれば、このことが耐酸化性向上の理由と考えられるが、この時、最表層に形成されるＡｌ_２Ｏ_３層直下には、Ａｌを含有しない非常にポーラスなＴｉ酸化物が形成する。静的な酸化テストにおいては、酸化の進行である酸素の内向拡散に対し、最表面に形成されたＡｌ_２Ｏ_３層が、酸化保護膜として機能するものの、動的な切削においては、最表面のＡｌ_２Ｏ_３層は、その直下のポーラスなＴｉ酸化物層より容易に剥離してしまい、酸化の進行に対し十分な効果を発揮しない。また、この最表面に形成されたＡｌ_２Ｏ_３層が動的な切削に対し、剥離しなければ、Ａｌ_２Ｏ_３の化学的安定性から被加工物との溶着現象を防ぐことができるのだが、現状この化学的に安定なＡｌ_２Ｏ_３の剥離を防ぐことは困難である。つまり、高温下で発生する溶着現象は最表層に形成されるＡｌ_２Ｏ_３が剥離してしまうために発生することが明らかとなった。また、（ＴｉＡｌＳｉ）（ＣＮ）膜や（ＴｉＡｌＺｒＢ）Ｎ、（ＴｉＡｌＢ）Ｎ、（ＴｉＡｌＳｉＢ）Ｎについても、従来の（ＴｉＡｌ）Ｎ膜にＳｉ、Ｚｒ、Ｂなどを含有させることで硬質皮膜そのものの高硬度化や耐酸化性を若干良好にさせるが、前述同様、酸化物に対する生成自由エネルギーの差から表面の酸化保護膜のＡｌ_２Ｏ_３層が直ちに形成され、更にその直下にポーラスなＴｉの酸化物を形成してしまい、その結果切削中の皮膜剥離をもたらす。よって、動的な切削における溶着現象を防ぐには至らないのである。
【０００８】
しかしながら、溶着現象の原因となるＡｌを除く、ＴｉとＢで構成される窒化物、炭窒化物、酸窒化物、酸炭窒化物等は、皮膜自体の耐酸化性は、従来のＴｉとＡｌの窒化物と同程度であり、高温下における溶着現象に対しては、ＴｉとＡｌの窒化物などよりも優れている。本発明者は、各種元素の溶着発生現象への抵抗性、つまり鋼に含まれる元素と、硬質皮膜中に含まれる元素との濡れ性という観点から鋭意研究を重ねた結果、本発明硬質皮膜は高温下における被加工物の溶着を防ぐのに効果があることをつきとめた。本発明者は、硬質皮膜中に含有させるＢについて、切削工具に適用した際に生じる現象を詳細に調査した結果、Ｂの有効性は、硬質皮膜の高硬度化や耐酸化性向上ではなく、切削時におけるＦｅとの親和性が低いことや被加工物の膜中への拡散現象がほとんど発生しないことである。図１に本発明のａ層を用いた硬質皮膜被覆切削工具の切削加工後の切刃近傍を、基体方向に元素分析を行った結果を示す。また、図２に従来の（ＴｉＡｌ）Ｎを同様に分析した結果を示す。図１、２の比較により、図１には皮膜内部に被加工物であるＦｅ元素は見られないが、図２の従来膜である（ＴｉＡｌ）Ｎでは膜の最表層にＡｌの酸化物が形成されており、被加工物であるＦｅが膜中に拡散していることがわかる。図２に示した傾向は従来の（ＴｉＡｌＳｉ）（ＣＮ）や（ＴｉＡｌＺｒＢ）Ｎ、（ＴｉＡｌＢ）Ｎなどにも見られることを確認した。つまり、本発明のａ層を使用することで、被加工物との高温下における化学反応が発生しにくい特性を持っているのである。また、同時に、耐酸化性も従来のＴｉとＡｌの窒化物とほぼ同程度であることを見出したのである。本発明者等は更に、鋭意研究を重ね、（ＴｉＡｌＢ）Ｎといった耐酸化性の優れる従来の（ＴｉＡｌ）ＮにＢを含有させる実験を試み、その硬質皮膜の耐溶着性に着目し、評価を行った結果、前述Ａｌを含有させている従来の皮膜は、そのなかに含まれるＡｌはＴｉやＢよりも高温下におけるＦｅとの親和性が高いため、最表層に酸素の内部拡散を防ぐＡｌ_２Ｏ_３層を形成させる前に、被加工物中の含有物と化学反応が発生していることを得た。切削工具にこのようなＡｌを含有させている硬質皮膜を適用した場合、この溶着現象により、工具すくい面に異常なクレーター摩耗の進行促進、更に境界部には溶着物が多量に貯め込まれ、チッピングをもたらすのである。このような実験結果からも硬質皮膜被覆工具の最表面には耐酸化性を十分にもった皮膜を被覆するよりも、従来使用してきたＴｉとＡｌの窒化物などの特異的な酸化機構を発生させるまでに硬質皮膜被覆工具表面に溶着を防ぐための、いわば自己潤滑皮膜が必要になるのである。つまり、本発明の硬質皮膜を切削工具最表層に被覆させることで、被加工物との溶着を防ぎ、その結果異常摩耗を防ぐことで、従来使用してきたＴｉとＡｌの窒化物などを被覆した硬質皮膜被覆工具の寿命よりも著しく伸びることを確認した。
【０００９】
ａ層は、静的及び動的条件下において優れた耐溶着性を有すものの、皮膜自身がもつ残留圧縮応力が大きいため基体との密着性においては十分でない。そのため、基体表面直上には、密着性、耐摩耗性、耐酸化性等をバランス良く適度に付与するため、ＡｌとＴｉで構成される窒化物、炭窒化物、酸窒化物、酸炭窒化物等のｂ層を被覆することが好ましい。また、基体表面直上には、上記記載の硬質皮膜の他に元素周期表に記載される４ａ、５ａ、６ａ族の金属を１種以上含んだ合金膜をもちいてもよい。（ＴｉＡｌ）系窒化物等の皮膜であるｂ層におけるＡｌの役割は、皮膜の耐摩耗性及び耐酸化性を向上させることである。そのため、密着性、耐摩耗性、耐酸化性をバランス良く得るためには、好ましくはｂ層のＡｌ含有量Ｆを、皮膜の金属成分のみの原子％で、３０≦Ｆ≦７５に調整することが好ましい。ｂ層における好ましいＡｌの含有量Ｆを設定した理由については、Ｆが３０原子％以上のときに耐酸化性が著しく向上し始めるためである。また、７５原子％以下に調整する理由は、耐酸化性が向上しても、皮膜硬度が著しく低下し耐摩耗性が劣化してしまうためである。
【００１０】
以上のように本発明においては、基体との密着性、皮膜自体の耐摩耗性および耐酸化性をバランス良く有するｂ層を基体表面直上に被覆し、その上に著しく耐溶着性や被加工物元素拡散性に優れるａ層を被覆することが極めて重要であり、その結果、乾式の高速切削並びに高送り切削に対応する切削工具を得ることが可能となる。また、ａ層の結晶格子の大きさを限定した理由について述べる。本発明の硬質皮膜を硬質皮膜被覆切削工具として成り立たせるためには硬質皮膜物性中の結晶格子の大きさ、つまり格子定数は重要である。高い密着性を保つためには、第１として、物理蒸着法特有に発生する残留圧縮応力を低減させなければならない。本発明に至るまでの鋭意研究の結果、本発明の硬質皮膜の格子定数と残留圧縮応力の相関性を導き出すに至った。第２として、硬質皮膜同士の密着性を確保するために本発明に使用される異種硬質皮膜をヘテロエピタキシャルの関係に保たなければならない。この両者の条件を満足させるために、本発明者は、ａ層のＸ線回折における（２００）面の格子定数Ａが０．４２００≦Ａ≦０．４２７０の範囲になるよう制御することで成し得たのである。つまり硬質皮膜の特長を最大限に導き出すためには、Ａの数値が０．４２７０を越えてしまうと硬質皮膜の残留圧縮応力が顕著に増大し、切削加工中の剥離が発生し満足な切削性能が得られないのである。また、基体表面直上にｂ層を被覆した後、ａ層並びにｂ層をそれぞれ交互に積層した多層皮膜によっても同様の効果が得られた。ａ層はラマン分光分析において、ｃ−ＢＮとｈ−ＢＮのピークを検出することができ、そのときのｃ−ＢＮのピーク強度をＱ１、ｈ−ＢＮのピーク強度をＱ２としたときに、ピーク強度比がＱ１／Ｑ２≧１．０の関係でなければならない。これは、硬質皮膜の潤滑性を維持したまま硬度を向上させるためである。本発明の硬質皮膜におけるａ層内部には、図３に示すようにｃ−ＢＮとｈ−ＢＮのピークが検出される。ｃ−ＢＮとｈ−ＢＮの硬度を比較すると、ｃ−ＢＮの方が高い硬度を示す。従って、硬質皮膜中にｃ−ＢＮが多く含まれるようにコーティング条件を制御することによって皮膜硬度が高くなり、耐摩耗性を向上させることができるのである。また、各層は必要に応じて窒化物、炭窒化物、酸窒化物、酸炭窒化物のいずれかに調整でき、それらを被覆した工具についても同様の切削性能が得られる。
【００１１】
金属成分がＴｉとＢで構成される窒化物、炭窒化物、酸窒化物、酸炭窒化物ある硬質皮膜のＢの含有量Ｍについて限定した理由を述べる。Ｔｉに対してＢの含有量が０．１原子％未満の場合、本発明の目的とする溶着や元素拡散を防ぐ効果が得られない。従って、目標とする近年の過酷な切削加工に対応できないため、著しく効果の出はじめる０．１原子％以上としたのである。また、ＴｉとＢで構成される本発明の硬質皮膜は、ＴｉＮなどで良く見られるような柱状晶を呈するが、Ｂの含有量が４０原子％を越えると柱状晶から微細粒状結晶構造に変化することが認められた。このようにＢの含有量が多い硬質皮膜は、内部の欠陥が多く、密度も低くなることが認められた。また、皮膜密着性を阻害する内部応力が非常に大きくなり容易に剥離現象が発生することを確認した。更には、硬質皮膜の結晶が微細であるために切削加工中に発生する粒界破壊の頻度が高く、それに起因する異常摩耗が認められた。本発明者等は、以上の様な知見を得るに至り、本発明の硬質皮膜中のＢ含有量Ｍを、原子％で、０．１≦Ｍ≦４０に限定したのである。本発明の硬質皮膜を作成するにあたっては、物理蒸着法が好ましい。従って成膜のもととなるターゲットが必要になる。そのターゲットはＴｉとＢからなる２種を用いても良いが、組成のばらつきや、放電の安定性を考慮するとＴｉとＢの合金ターゲットがより好ましい。
【００１２】
硬質皮膜中に含有させるＢ含有量によって、ＴｉとＢで構成される硬質皮膜中の金属元素の存在形態に特徴があることを確認した。従来の硬質皮膜であるＴｉとＡｌの窒化物などは、その組成によって異なるが、実用化されている皮膜を取り上げると、一般にＴｉＮと同じ結晶格子形態であるＮａＣｌ型Ｂ１構造をとることがわかっており、ＴｉＮ格子中のＴｉがＡｌに置き換わっている形態をとり、いわば、Ａｌが固溶された状態にある。しかしながら、本発明のＴｉとＢで構成される硬質皮膜は、Ｂの含有量に左右されるものの、その含有量が０．１原子％以上になると、前記ＴｉとＡｌの窒化物などとは異なった形態を示す。Ｂの含有量が０．１原子％以上になるとＢはＴｉＮ格子中のＴｉに置き換わる形態の他に、Ｂの化合物が単独で存在するような形態になる。つまり、Ｂの含有量が０．１原子％以上になると、例えば、本発明の硬質皮膜であるＴｉとＢの窒化物の場合、硬質皮膜中にはＴｉＮの結晶とＢＮの結晶が混在する形態をとるのである。Ｂの含有量が０．１原子％未満ではＢがＴｉＮ結晶格子の中に完全に取り込まれ、固溶体の形態を呈する。この結晶形態の変化が切削性能に多大な影響を及ぼす。本発明の組成範囲にある窒化物の場合、ＴｉＮ類似の結晶のほかにＢＮの結晶が存在する。このＢＮは自己潤滑が優れるという事やＦｅとの濡れ性が低いという事が知られており、このＢＮ結晶の存在が、主として化学反応が起因のクレーター摩耗を著しく抑制させる効果があるものと考えられる。また、ＢＮは酸化に対する自由生成エネルギーの面からも酸化に対する抵抗力があるため、高温下における硬質皮膜の特性が劣化しない。これらの驚くべき事実は、本発明者が鋭意研究を重ねることで得られた結果である。しかしながら、Ｂの含有量が４０原子％を越えると、上記ＢＮの結晶は存在するが、内部応力が非常に大きくなるために、良好な密着性を維持することが困難となる。つまり、切削加工の様に硬質皮膜に外部からの衝撃を与えると硬質皮膜が自身の内部応力に耐えられず、容易に剥離が発生してしまい、硬質皮膜被覆工具としての役割を果たさなくなることが認められた。従って、本発明者等の目標である切削工具を提供するためには、硬質皮膜中に含有されるＢの量は４０原子％を越えてはいけないことになり、かつ、硬質皮膜中にＢＮの結晶を存在させるような、新しい技術を創生しなければならないのである。
【００１３】
本発明の硬質皮膜について、その膜厚Ｄを規定した理由について述べる。本硬質皮膜の特性が近年の過酷な切削加工に対応するためには、Ｄ≧０．１μｍを被覆しなければならない。つまり、それよりも薄い場合は、硬質皮膜の特性が発揮されないのである。また、本発明に記載の硬質皮膜を工具すくい面に厚く被覆し、すくい面摩耗が著しく発生するような切削加工に適用した場合、従来の硬質皮膜である（ＴｉＡｌ）Ｎや（ＴｉＡｌＳｉ）（ＣＮ）、（ＴｉＡｌＺｒＢ）Ｎ、（ＴｉＡｌＢ）Ｎでは、すでに説明したようにクレーター摩耗が容易に発生し、高能率加工を満足させるにいたらない。本発明者は、適用する金属成分がＴｉとＢで構成される硬質皮膜の効果を十分に発揮させるための最適膜厚を詳細に調査した結果、その膜厚ＤがＤ≧０．１μｍであることを明らかにした。この調査に基づき、被覆される工具すくい面の膜厚ＤがＤ≧０．１μｍであることがより好ましい。
【００１４】
本発明の硬質皮膜被覆工具は、その被覆方法については、特に限定されるものではないが、被覆基体への熱影響、工具の疲労強度、皮膜の密着性等を考慮した場合、比較的低温で被覆でき、被覆した皮膜に圧縮応力が残留するアーク放電方式イオンプレーティング、もしくはスパッタリング等の被覆基体側にバイアス電圧を印加する物理蒸着法であることが望ましい。以下、本発明を実施例に基づいて説明する。
【００１５】
【実施例】
小型アークイオンプレーティング装置を用い、金属成分の蒸発源である各種合金製ターゲット、並びに反応ガスであるＮ_２ガス、ＣＨ_４ガス、ＡｒとＯ_２混合ガスから目的の皮膜が得られるものを選択し、被覆基体温度４００℃にて、被覆基体である外径８ｍｍφの超硬合金製インサートに−１５０Ｖの電位を印加させて被覆を行った。
【００１６】
得られた硬質皮膜被覆インサートを用い、次に示す乾式の高能率切削条件にて、刃先の欠けないしは摩耗等により工具が切削不能となるまで加工を行い、その時の切削長を工具寿命とした。表１に本発明例、比較例及び従来例に関する硬質皮膜の詳細及びその切削結果を示す。
【００１７】
【表１】

【００１８】
インサート切削条件は、切削工具は正面フライス（インサート形状：ＳＥＥ４２ＴＮ特殊形）を使用し、切削方法はセンターカット方式、被削材形状は巾１００ｍｍ、長さ２５０ｍｍ、被削材はＳ５０Ｃ（ＨＲＣ３０）、切り込みは２．０ｍｍ、切削速度は１５０ｍ／ｍｉｎ、１刃送り量は０．３０ｍｍ／刃、切削油は無しである。
【００１９】
表１に示したように、本発明の硬質皮膜は、その格子定数の大きさとラマン分光分析におけるｈ−ＢＮとｃ−ＢＮのピーク強度比が切削性能に大きく影響を及ぼすことは明らかである。つまり、本発明例１〜２０に示す様に、ａ層のＸ線回折における（２００）面の格子定数Ａが、０．４２００≦Ａ≦０．４２７０ｎｍの範囲を満たし、更にラマン分光分析によるｃ−ＢＮ、ｈ−ＢＮが検出され、そのときのｃ−ＢＮのピーク強度Ｑ１並びにｈ−ＢＮのピーク強度Ｑ２の比、Ｑ１／Ｑ２≧１．０の時は、材料の特性を如何なく発揮し、大幅な切削寿命の向上をもたらし、十分満足できる結果が得られている。しかし例えば、比較例２１、２２、２５は、ａ層のＸ線回折における（２００）面の格子定数Ａが、０．４２００≦Ａ≦０．４２７０ｎｍの範囲を満足していないのに加え、ラマン分光分析においてｈ−ＢＮのピーク強度が強いため、ピーク強度比も満足されていないことから、従来例２８から３４と比較しても効果が認められなかった。更に、比較例２３、２４、２６、２７は、ａ層のＸ線回折における（２００）面の格子定数Ａが、０．４２００≦Ａ≦０．４２７０ｎｍの範囲を満足しない状態で、しかもラマン分光分析におけるｃ−ＢＮのピーク強度が強くなると硬質皮膜の内部応力が著しく増大し、早期剥離発生後、欠損に至ってしまった。表１に示したように、本発明の硬質皮膜は、ＢＮの結晶の存在と、その化学構造の制御によって、耐溶着性はもとより、耐熱性も優れるため、著しい工具性能向上をもたらすことは明らかである。しかし例えば、比較例２１、２４は硬質皮膜中に添加されるＢ量が微量のため、ＴｉＮ結晶格子の中に取り込まれ、固溶体の形態をとっており、その結果、膜としてはＴｉとＢで構成される硬質皮膜であるが、本発明の目的である工具性能の改善には遠く至らないのである。また、比較例２２、２３、２５、２６、２７では、ＴｉとＢで構成される硬質皮膜中にＢＮの結晶が存在することが認められても、添加されるＢ添加量がＴｉに対して５０原子％を越えてしまっている。このような場合、切削加工においては、硬質皮膜が自身の内部応力に負けて、容易に剥離が発生する。特に、比較例２６は、硬質皮膜全体の内部応力が最も高くなり、約−６ＧＰａにも到達してしまうことが認められ、切削試験では、インサートの切削初期に工具逃げ面、すくい面に大きな剥離が発生し、切削続行が不可能となった。従って、本発明の硬質皮膜は、膜中のＢＮ結晶を存在させることも非常に重要な技術であるが、単に存在させるのではなく、添加するＢの量も含め、硬質皮膜被覆工具の設計を行わない限り、著しく優れた性能を発揮する工具の提供は不可能であることは明らかである。一方、従来例２８の（ＴｉＳｉ）Ｎ皮膜と（ＴｉＡｌ）Ｎ皮膜との２層膜とした試料、また従来例２９から３４の（ＴｉＡｌ）系の窒化物層に第３元素としてＺｒ、Ｂ、Ｓｉを添加した試料に対し、本発明例は、いずれの場合も工具寿命で優っていることが確認された。本発明皮膜の成膜実施にあたっては、使用する導入ガスの検討も同時に行った。その結果、著しく優れた耐溶着性を保つためには、金属成分がＴｉとＢで構成される窒化物、炭窒化物、酸窒化物、酸炭窒化物いずれかで、Ｂの含有量Ｍが金属成分のみの原子％で、０．１≦Ｍ≦４０．０であることが望ましいが、工具の発熱並びに被加工物との摩擦を考慮した場合、成膜時に上記記載の皮膜を製膜する上で必要となる窒素、酸素を含むガスの他に、炭素を含むガスを導入し、炭窒化物、酸炭窒化物を被覆することにより更に優れた工具性能を発揮する。本発明硬質皮膜の適用は、実施例で示したインサートだけでなく、旋削用途など他の高能率切削加工にも十分対応できうるものである。
【００２０】
【発明の効果】
本発明の硬質皮膜被覆工具は、ＴｉとＢで構成される窒化物、炭窒化物、酸窒化物、酸炭窒化物のいずれかである層にラマン分光分析においてｃ−ＢＮとｈ−ＢＮのピークが検出される皮膜が被覆され、この皮膜が優れた耐溶着、耐拡散性、耐酸化性、耐摩耗性を達成することにより、乾式高能率切削加工において著しく長い工具寿命が得られ、切削加工における生産性の向上に極めて有効である。
【図面の簡単な説明】
【図１】図１は、本発明例の皮膜を被覆した工具の切削後の刃先近傍における元素分析結果を示す。
【図２】図２は、従来例の皮膜を被覆した工具の切削後の刃先近傍における元素分析結果を示す。
【図３】図３は、本発明例の皮膜のラマン分光解析結果で、ｃ―ＢＮとｈ―ＢＮとの回折ピークを示す。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a hard film-coated tool used for cutting a metal material or the like.
[0002]
[Prior art]
Conventionally, cutting tools coated with TiN, Ti (CN), and the like have been widely used. Since TiN has relatively excellent oxidation resistance, it not only exhibits excellent wear resistance against rake surface wear of tools caused by heat generated during cutting, but also has good adhesion to the substrate. is there. Further, since Ti (CN) has higher hardness than TiN and lower contact resistance with cutting powder discharged from the workpiece, heat generation on the tool surface is suppressed. From this, it is possible to suppress the flank wear generated on the tool flank due to mechanical rubbing wear with the work material. However, in response to the tendency to increase the cutting speed for the purpose of increasing the efficiency of metal working, the hard coating does not exhibit sufficient oxidation resistance and wear resistance. From such a background, studies have been made to further improve the oxidation resistance and wear resistance of the film. As a result, Japanese Patent No. 3248897 discloses that the (TiSi) N film is an a layer and the (TiAl) N film is a b layer. There is disclosed a technique in which a film obtained by alternately coating one or more layers a and b as layers has oxidation resistance and abrasion resistance. On the other hand, in JP 2001-293601, in abrasion-resistant films, _BN, there is disclosure about film containing ultrafine compounds such TiB 2, TiB, the ultrafine compound has an amorphous structure It is described as having a function of improving the hardness of the film. According to the report, wear resistance, high slipping property, high seizure property, and improvement in processing accuracy of a work material can be achieved. However, no detailed description is given of the characteristics and the state of existence of the ultrafine compound.
[0003]
The (TiAl) N film has a Vickers hardness of approximately 2300 to 2800, although it varies depending on the component ratio of Ti and Al contained in the film or the content of Si or C in the film. Further, since the oxidation resistance is remarkably superior to those of TiN and Ti (CN), the performance of the cutting tool is remarkably improved under cutting conditions in which the cutting edge reaches a high temperature. The (TiAlSi) (CN) film contains Si so as to improve the oxidation resistance more than the (TiAl) N film. Further, in consideration of the same effect, attempts have been made to include Zr, Hf, and B as a third element in the (TiAl) system. In recent years, the environment in which such hard film-coated cutting tools are used has become increasingly harsh. For example, as cutting speeds tend to increase and wet cutting, which has been used conventionally, is regarded as an important environmental issue. Attention has been paid to dry cutting. In addition, there is a tendency for steel materials to be difficult to cut due to the effects of various types of elements contained in mold steel and high feed machining with an emphasis on high efficiency machining, and the use environment of hard film coated cutting tools is becoming increasingly severe. I have.
[0004]
According to the study of the present inventor, the oxidation start temperature of the (TiAl) N film in the air increases from 750 ° C. to 750 ° C. to 900 ° C. depending on the Al content, compared to 450 ° C. of TiN. However, in the dry high-speed cutting described above, the temperature of the cutting edge of the tool used reaches a high temperature of 900 ° C. or higher. It is needless to say that the oxidation resistance of the hard coating is important in the cutting work performed under such severe conditions, but the cutting edge of the hard coating coating cutting tool and the workpiece are earlier than that. It is essential to prevent the welding phenomenon that occurs due to the occurrence of a chemical reaction. In recent years, steel materials for molds contain various elements in order to significantly improve the performance of molds, and the phenomenon of welding to cutting tools is more likely to occur. In this case, the state in which the element of the workpiece is easily diffused into the hard coating has come into being. For this reason, conventional nitrides of Ti and Al have remarkably excellent oxidation resistance in the air, but when cutting in a high temperature state, it is necessary to prevent welding and diffusion of a workpiece, which are one of the chemical reactions. At present, it is difficult to obtain a sufficient tool life.
[0005]
[Problems to be solved by the invention]
The present invention has been made in view of such circumstances, and furthermore, without sacrificing the wear resistance and adhesion of a hard coating having excellent oxidation resistance, such as a conventional (TiAl) N film having excellent oxidation resistance, and It is an object of the present invention to provide a hard film coated tool which improves welding resistance in a high temperature state and diffusion of a work element into a hard film, and is suitable for dry cutting, high speed, and high feed cutting. .
[0006]
[Means for Solving the Problems]
The present inventor has conducted extensive studies on the effects of various elements and the optimal layer structure of the coating on the welding resistance of the hard coating, the wear resistance, and the adhesion to the base material. A layer which is any one of nitride, carbonitride, oxynitride and oxycarbonitride composed of Ti and B, and nitride, carbonitride and oxynitride whose metal components are composed of Al and Ti Layer or a layer of oxycarbonitride is alternately coated one or more times, and the lattice constant A of the (200) plane in X-ray diffraction of the layer a is 0.4200 ≦ A ≦ 0. The c-BN and h-BN peaks were detected in the range of 4270 nm and Raman spectroscopy of the a layer, and the c-BN peak intensity at that time was Q1, and the h-BN peak intensity was Q2. Where the peak intensity ratio Q1 / Q2 ≧ 1.0 It is to be hard-coated tool of high-speed cutting of dry, at high feed machining, we have reached the present invention found that the performance of the cutting tool becomes extremely good. Here, high feed machining is defined as cutting in which the feed amount per blade in the cutting conditions exceeds 0.3 mm / tooth. Further, according to the present invention, when the a layer is coated using an alloy target of Ti and B, and the composition of the film indicates the content M of B contained in the a layer by atomic% of only the metal component, 1 ≦ M ≦ 40, and the thickness D of the a layer is preferably D ≧ 0.1 μm.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
The configuration of the a layer will be described in detail. Generally, when an oxidation test is performed on the (TiAl) N film in the air, Al near the surface of the film diffuses outward toward the outermost surface to form an Al ₂ O ₃ layer. This phenomenon suppresses the subsequent entry of oxygen into the film. According to the study of the present inventor, this is considered to be the reason for the improvement in oxidation resistance. At this time, immediately below the Al ₂ O ₃ layer formed on the outermost layer, very porous Ti containing no Al is contained. An oxide forms. In the static oxidation test, the Al ₂ O ₃ layer formed on the outermost surface functions as an oxidation protection film against the inward diffusion of oxygen, which is the progress of oxidation. The Al ₂ O ₃ layer is easily separated from the porous Ti oxide layer immediately below the Al ₂ O ₃ layer, and does not exert a sufficient effect on the progress of oxidation. In addition, if the Al ₂ O ₃ layer formed on the outermost surface does not peel off during dynamic cutting, it is possible to prevent the phenomenon of welding with the workpiece due to the chemical stability of Al ₂ O ₃ . However, at present, it is difficult to prevent the separation of this chemically stable Al ₂ O ₃ . That is, it has been clarified that the welding phenomenon occurring at a high temperature occurs because Al ₂ O ₃ formed on the outermost layer is peeled off. Also, regarding the (TiAlSi) (CN) film, (TiAlZrB) N, (TiAlB) N, and (TiAlSiB) N, the conventional (TiAl) N film contains Si, Zr, B, etc., so that the hard coating itself can be formed. Although the hardness and the oxidation resistance are slightly improved, the Al ₂ O ₃ layer of the oxide protective film on the surface is immediately formed due to the difference in the free energy of formation with respect to the oxide, and the porous Ti It forms oxides, which results in coating delamination during cutting. Therefore, the welding phenomenon in dynamic cutting cannot be prevented.
[0008]
However, nitrides, carbonitrides, oxynitrides, oxycarbonitrides, etc., composed of Ti and B, excluding Al, which causes the welding phenomenon, have the oxidation resistance of the film itself of the conventional Ti and Al And is superior to the nitride of Ti and Al, etc., against the welding phenomenon at high temperatures. The present inventors have conducted intensive studies from the viewpoint of the resistance of various elements to the occurrence of welding, that is, the elements contained in steel and the wettability of the elements contained in the hard coating. It has been found that it is effective in preventing welding of a workpiece under high temperature. The present inventor has conducted a detailed investigation on the phenomena occurring when applied to a cutting tool with respect to B contained in a hard coating. As a result, the effectiveness of B is not increased hardness or improved oxidation resistance of the hard coating, That is, the affinity with Fe during cutting is low, and the phenomenon of diffusion of the workpiece into the film hardly occurs. FIG. 1 shows the results of elemental analysis of the vicinity of the cutting edge after cutting of the hard film-coated cutting tool using the a layer according to the present invention in the direction of the substrate. FIG. 2 shows the result of a similar analysis of conventional (TiAl) N. According to the comparison between FIG. 1 and FIG. 2, the Fe element which is the workpiece is not seen in the inside of the film in FIG. 1, but the oxide of Al is present on the outermost layer of the film in (TiAl) N which is the conventional film in FIG. It can be seen that Fe, which is formed, is diffused in the film. It has been confirmed that the tendency shown in FIG. 2 is also observed in conventional (TiAlSi) (CN), (TiAlZrB) N, (TiAlB) N and the like. That is, by using the layer a of the present invention, it has a characteristic that a chemical reaction with a workpiece under high temperature is unlikely to occur. At the same time, they also found that the oxidation resistance was almost the same as that of the conventional nitride of Ti and Al. The present inventors have further conducted diligent research, tried an experiment in which B is contained in conventional (TiAl) N such as (TiAlB) N, which has excellent oxidation resistance, focused on the welding resistance of the hard coating, and evaluated the hard coating. As a result, the conventional film containing Al described above has a higher affinity for Fe at high temperatures than Ti and B, and therefore, Al which prevents internal diffusion of oxygen in the outermost layer. Before forming the ₂ O ₃ layer, it was found that a chemical reaction had occurred with the contents in the workpiece. When such a hard coating containing Al is applied to a cutting tool, this welding phenomenon promotes the abnormal progress of crater wear on the tool rake face, and a large amount of deposited material is stored at the boundary, It causes chipping. Based on these experimental results, a unique oxidation mechanism such as the conventionally used nitrides of Ti and Al occurs rather than coating the outermost surface of the hard coating tool with a coating with sufficient oxidation resistance. In other words, a self-lubricating film is required to prevent welding on the surface of the tool coated with the hard film before the coating is performed. In other words, by coating the hard coating of the present invention on the outermost layer of the cutting tool, it prevented welding with the workpiece, and as a result, prevented abnormal wear, thereby coating the conventionally used nitrides of Ti and Al. It was confirmed that the life of the tool coated with the hard coating was significantly extended.
[0009]
The layer a has excellent adhesion resistance under static and dynamic conditions, but has insufficient adhesion to a substrate because the film itself has a large residual compressive stress. Therefore, a nitride, a carbonitride, an oxynitride, an oxycarbonitride composed of Al and Ti is provided directly above the surface of the substrate in order to impart a good balance of adhesion, wear resistance, oxidation resistance, etc. It is preferable to cover the layer b such as Further, an alloy film containing one or more metals of the 4a, 5a, and 6a groups described in the periodic table may be used directly on the surface of the base in addition to the hard coating described above. The role of Al in the b layer, which is a coating of (TiAl) -based nitride or the like, is to improve the wear resistance and oxidation resistance of the coating. Therefore, in order to obtain a good balance of adhesion, abrasion resistance, and oxidation resistance, preferably, the Al content F of the b layer is adjusted to 30 ≦ F ≦ 75 by atomic% of only the metal component of the film. Is preferred. The reason why the preferable Al content F in the b layer is set is that when F is 30 atomic% or more, the oxidation resistance starts to significantly improve. The reason for adjusting the content to 75 atomic% or less is that even if the oxidation resistance is improved, the hardness of the film is significantly reduced and the wear resistance is deteriorated.
[0010]
As described above, in the present invention, the b layer having a good balance between the adhesion to the substrate and the abrasion resistance and oxidation resistance of the film itself is coated directly on the surface of the substrate, and remarkably welding resistance and workpiece It is extremely important to coat the layer a having excellent element diffusivity, and as a result, it becomes possible to obtain a cutting tool that supports dry high-speed cutting and high-feed cutting. The reason for limiting the size of the crystal lattice of the a-layer will be described. In order to make the hard coating of the present invention a cutting tool coated with a hard coating, the size of the crystal lattice in the physical properties of the hard coating, that is, the lattice constant is important. First, in order to maintain high adhesiveness, it is necessary to reduce the residual compressive stress that is peculiar to the physical vapor deposition method. As a result of intensive studies leading to the present invention, a correlation between the lattice constant of the hard coating of the present invention and the residual compressive stress has been derived. Secondly, in order to ensure the adhesion between the hard films, the different types of hard films used in the present invention must be maintained in a heteroepitaxial relationship. In order to satisfy both conditions, the inventor of the present invention controlled the lattice constant A of the (200) plane in the X-ray diffraction of the a layer so as to be in the range of 0.4200 ≦ A ≦ 0.4270. I could do it. In other words, in order to maximize the characteristics of the hard coating, if the value of A exceeds 0.4270, the residual compressive stress of the hard coating will increase significantly, and peeling will occur during cutting, and satisfactory cutting performance will occur. Cannot be obtained. The same effect was obtained by a multilayer coating in which a layer b and a layer b were alternately laminated after coating the layer b directly on the surface of the base. The a layer can detect c-BN and h-BN peaks in Raman spectroscopic analysis. When the c-BN peak intensity at that time is Q1 and the h-BN peak intensity is Q2, the peak is The intensity ratio must satisfy the relationship Q1 / Q2 ≧ 1.0. This is to improve the hardness while maintaining the lubricity of the hard film. As shown in FIG. 3, peaks of c-BN and h-BN are detected inside the layer a in the hard coating of the present invention. When comparing the hardness of c-BN and h-BN, c-BN shows higher hardness. Therefore, by controlling the coating conditions so that a large amount of c-BN is contained in the hard coating, the coating hardness increases and the wear resistance can be improved. In addition, each layer can be adjusted to any of nitride, carbonitride, oxynitride, and oxycarbonitride as needed, and the same cutting performance can be obtained for a tool coated therewith.
[0011]
The reason for limiting the B content M of the hard coating in which the metal component is composed of a nitride, a carbonitride, an oxynitride, and an oxycarbonitride composed of Ti and B will be described. When the content of B is less than 0.1 atomic% with respect to Ti, the effect of preventing welding and element diffusion, which is the object of the present invention, cannot be obtained. Therefore, since it is not possible to cope with the target severe cutting work in recent years, the content is set to 0.1 atomic% or more, at which a remarkable effect starts to be obtained. In addition, the hard coating of the present invention composed of Ti and B exhibits columnar crystals as often seen in TiN and the like, but when the B content exceeds 40 atomic%, the structure changes from the columnar crystals to a fine granular crystal structure. Was allowed to do so. As described above, it was recognized that the hard coating having a large B content had many internal defects and a low density. In addition, it was confirmed that the internal stress that hindered the film adhesion was extremely large and the peeling phenomenon easily occurred. Furthermore, since the crystal of the hard film was fine, the frequency of grain boundary destruction occurring during cutting was high, and abnormal wear caused by the fracture was recognized. The present inventors have obtained the above knowledge, and have limited the B content M in the hard coating of the present invention to 0.1 ≦ M ≦ 40 in atomic%. In preparing the hard coating of the present invention, a physical vapor deposition method is preferable. Therefore, a target for forming a film is required. As the target, two kinds consisting of Ti and B may be used, but an alloy target of Ti and B is more preferable in consideration of variation in composition and stability of discharge.
[0012]
It was confirmed that the presence of the metal element in the hard film composed of Ti and B was characterized by the B content contained in the hard film. Conventional hard coatings such as nitrides of Ti and Al differ depending on their compositions. However, taking up practical coatings, it is known that they generally have a NaCl-type B1 structure that has the same crystal lattice form as TiN. In this case, Al in the TiN lattice is replaced with Al, so to speak, Al is in a solid solution state. However, although the hard coating composed of Ti and B according to the present invention depends on the content of B, when the content is 0.1 atomic% or more, it differs from the nitride of Ti and Al. Shows the form. When the content of B is 0.1 atomic% or more, B has a form in which the compound of B exists alone in addition to a form in which Ti is replaced by Ti in the TiN lattice. That is, when the content of B is 0.1 atomic% or more, for example, in the case of the nitride of Ti and B, which is the hard coating of the present invention, the hard coating contains a mixture of TiN crystals and BN crystals. Because If the content of B is less than 0.1 atomic%, B is completely taken into the TiN crystal lattice and exhibits a form of a solid solution. This change in crystal morphology has a great effect on cutting performance. In the case of nitrides within the composition range of the present invention, BN crystals exist in addition to TiN-like crystals. It is known that this BN has excellent self-lubrication and low wettability with Fe. It is considered that the presence of this BN crystal has an effect of significantly suppressing crater wear mainly caused by a chemical reaction. Can be Further, BN has resistance to oxidation in terms of free generation energy for oxidation, so that the characteristics of the hard film at high temperatures are not deteriorated. These surprising facts are the results obtained by the inventor's intensive studies. However, when the content of B exceeds 40 atomic%, the above-mentioned BN crystals are present, but the internal stress becomes very large, so that it becomes difficult to maintain good adhesion. In other words, when an external impact is applied to the hard coating as in the case of cutting, the hard coating cannot withstand its own internal stress, easily peels off, and does not serve as a hard coating tool. Admitted. Therefore, in order to provide a cutting tool which is the target of the present inventors, the amount of B contained in the hard coating must not exceed 40 atomic%, and the amount of BN contained in the hard coating is New technologies must be created to make the crystals exist.
[0013]
The reason for defining the thickness D of the hard coating of the present invention will be described. In order for the characteristics of this hard coating to correspond to severe cutting work in recent years, it is necessary to cover D ≧ 0.1 μm. In other words, when the thickness is smaller than that, the characteristics of the hard coating are not exhibited. When the hard coating according to the present invention is thickly coated on a tool rake face and applied to a cutting process in which rake face wear is remarkably generated, conventional hard coatings such as (TiAl) N and (TiAlSi) (CN) are used. ), (TiAlZrB) N, and (TiAlB) N, as described above, crater wear easily occurs, and high efficiency processing is not satisfied. The present inventor has investigated in detail the optimum film thickness for sufficiently exerting the effect of the hard film composed of Ti and B as the metal component to be applied, and as a result, the film thickness D is D ≧ 0.1 μm. It revealed that. Based on this investigation, it is more preferable that the thickness D of the tool rake face to be coated is D ≧ 0.1 μm.
[0014]
The hard film-coated tool of the present invention is not particularly limited in its coating method.However, in consideration of the thermal effect on the coated substrate, the fatigue strength of the tool, the adhesion of the film, etc., the tool is formed at a relatively low temperature. It is desirable to use a physical vapor deposition method in which a bias voltage is applied to the coated substrate side, such as arc discharge ion plating, which can be coated and compressive stress remains in the coated film, or sputtering. Hereinafter, the present invention will be described based on examples.
[0015]
【Example】
Using a small arc ion plating device selection, various alloy target having an evaporation source of the metal component, and N ₂ gas as the reaction gas, CH ₄ gas, those coating object from Ar and O ₂ mixed gas is obtained Then, at a coating substrate temperature of 400 ° C., coating was performed by applying a potential of −150 V to a cemented carbide insert having an outer diameter of 8 mmφ as the coating substrate.
[0016]
Using the obtained hard coating-coated insert, processing was performed under the following dry high-efficiency cutting conditions until the tool could not be cut due to chipping or wear of the cutting edge, and the cutting length at that time was defined as the tool life. Table 1 shows the details of the hard coatings of the present invention, comparative examples, and conventional examples and the cutting results.
[0017]
[Table 1]

[0018]
For insert cutting conditions, a cutting tool uses a face mill (insert shape: SEE42TN special type), cutting method is center cut method, work material shape is width 100mm, length 250mm, work material is S50C (HRC30), The depth of cut is 2.0 mm, the cutting speed is 150 m / min, the feed amount of one blade is 0.30 mm / blade, and there is no cutting oil.
[0019]
As shown in Table 1, it is clear that the hard coating of the present invention has a large influence on the cutting performance by the size of the lattice constant and the peak intensity ratio between h-BN and c-BN in Raman spectroscopy. That is, as shown in Examples 1 to 20 of the present invention, the lattice constant A of the (200) plane in the X-ray diffraction of the a layer satisfies the range of 0.4200 ≦ A ≦ 0.4270 nm, and furthermore, c is determined by Raman spectroscopy. -BN and h-BN are detected, and the ratio of the peak intensity Q1 of c-BN and the peak intensity Q2 of h-BN at that time, and when Q1 / Q2 ≧ 1.0, the characteristics of the material are exhibited. , Greatly improving the cutting life, and obtaining satisfactory results. However, for example, in Comparative Examples 21, 22, and 25, the lattice constant A of the (200) plane in the X-ray diffraction of the a layer does not satisfy the range of 0.4200 ≦ A ≦ 0.4270 nm, and the Raman Since the peak intensity of h-BN was strong in the spectroscopic analysis and the peak intensity ratio was not satisfied, no effect was observed even in comparison with Conventional Examples 28 to 34. Further, Comparative Examples 23, 24, 26, and 27 show that the lattice constant A of the (200) plane in the X-ray diffraction of the a layer does not satisfy the range of 0.4200 ≦ A ≦ 0.4270 nm, and the Raman spectroscopy is used. When the peak intensity of c-BN in the analysis was increased, the internal stress of the hard coating was significantly increased, leading to loss after early peeling. As shown in Table 1, it is apparent that the hard coating of the present invention has excellent heat resistance as well as welding resistance due to the presence of BN crystals and the control of its chemical structure, so that the tool performance is remarkably improved. It is. However, for example, in Comparative Examples 21 and 24, since the amount of B added to the hard coating was very small, it was taken into the TiN crystal lattice and was in the form of a solid solution. Although it is a constituted hard coating, the improvement of the tool performance, which is the object of the present invention, is not far. Further, in Comparative Examples 22, 23, 25, 26, and 27, even though it was recognized that BN crystals were present in the hard coating composed of Ti and B, the amount of B added was It has exceeded 50 atomic%. In such a case, in the cutting process, the hard coating loses its own internal stress and peels off easily. In particular, in Comparative Example 26, it was recognized that the internal stress of the entire hard coating became the highest and reached about −6 GPa. Occurred, making it impossible to continue cutting. Therefore, in the hard coating of the present invention, the existence of BN crystals in the coating is also a very important technique. Obviously, without this, it is impossible to provide a tool that performs significantly better. On the other hand, a sample formed as a two-layer film of the (TiSi) N film and the (TiAl) N film of Conventional Example 28, and Zr, B, as the third element in the (TiAl) -based nitride layers of Conventional Examples 29 to 34. In each case, it was confirmed that the tool life was superior to the sample to which Si was added in each case. In forming the film of the present invention, the introduced gas to be used was also examined. As a result, in order to maintain extremely excellent welding resistance, the metal component is any of nitride, carbonitride, oxynitride, or oxycarbonitride composed of Ti and B, and the content M of B is increased. It is preferable that 0.1 ≦ M ≦ 40.0 in atomic% of the metal component alone, but in consideration of heat generation of the tool and friction with the workpiece, the above-described film is formed at the time of film formation. In addition to the gas containing nitrogen and oxygen required above, a gas containing carbon is introduced to coat carbonitrides and oxycarbonitrides, thereby exhibiting more excellent tool performance. The application of the hard coating of the present invention can sufficiently cope with not only the inserts shown in the examples but also other high-efficiency cutting processes such as turning applications.
[0020]
【The invention's effect】
The hard-coated tool of the present invention is characterized in that a layer composed of any of nitride, carbonitride, oxynitride, and oxycarbonitride composed of Ti and B has c-BN and h-BN in Raman spectroscopic analysis. The coating whose peak is detected is coated, and this coating achieves excellent welding resistance, diffusion resistance, oxidation resistance, and abrasion resistance, resulting in extremely long tool life in dry high efficiency cutting. This is extremely effective in improving productivity in processing.
[Brief description of the drawings]
FIG. 1 shows the results of elemental analysis of a tool coated with a coating of the present invention near a cutting edge after cutting.
FIG. 2 shows the results of elemental analysis near the cutting edge after cutting of a conventional tool coated with a coating.
FIG. 3 shows diffraction peaks of c-BN and h-BN as a result of Raman spectroscopic analysis of the film of the present invention.

Claims

An a layer in which the metal component is any of nitride, carbonitride, oxynitride, and oxycarbonitride composed of Ti and B; B layer, which is any one of a material, an oxynitride, and an oxycarbonitride, is alternately coated one or more times, and the lattice constant A of the (200) plane in the X-ray diffraction of the a layer is 0.4200 ≦ A ≦ 0.4270 nm, and the c-BN and h-BN peaks are detected in the Raman spectroscopic analysis of the a layer, and the c-BN peak intensity at this time is Q1, the h-BN peak is A hard-coated tool, characterized in that when the strength is Q2, the peak strength ratio Q1 / Q2 ≧ 1.0.

2. The tool according to claim 1, wherein the a layer is coated using an alloy target of Ti and B, and the composition of the a layer is such that the content M of B is represented by atomic% of only the metal component. A hard-coated tool, wherein 0.1 ≦ M ≦ 40.

The hard-coated tool according to claim 1 or 2, wherein the thickness D of the a-layer is D ≧ 0.1 μm.