JP2004114219A

JP2004114219A - Coated hard tool

Info

Publication number: JP2004114219A
Application number: JP2002279956A
Authority: JP
Inventors: Shinya Imamura; 今村　晋也; Haruyo Fukui; 福井　治世; Makoto Setoyama; 瀬戸山　誠; Kazuo Yamagata; 山縣　一夫; Hideki Moriguchi; 森口　秀樹
Original assignee: Sumitomo Electric Industries Ltd
Current assignee: Sumitomo Electric Industries Ltd
Priority date: 2002-09-25
Filing date: 2002-09-25
Publication date: 2004-04-15
Anticipated expiration: 2022-09-25
Also published as: JP4116382B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coated hard tool which contributes to improvement in abrasion resistance of cutting tools such as a drill, an end mill, a cutting edge exchangeable tip for milling and turning, a metal saw, a gear cutting tool, a reamer, and a tap. <P>SOLUTION: The coated hard tool consists of a base material and a coating formed on the same, and the coated film is formed of (Ti<SB>x</SB>Si<SB>y</SB>)(C<SB>a</SB>N<SB>b</SB>O<SB>c</SB>), where x, y, a, b, and c are in the following ranges; 0.1≤y≤0.8, x+y=1, 0≤ a ≤0.6, 0≤b≤1.0, 0≤c≤0.5, a+b+c=1. According to the coated hard tool, the amount of C in the coating is sequentially or stepwise increased from a location closer to the base material to a location closer to a surface of the coating, to thereby improve the abrasion resistance and lubricity of the tool. Selectively an intermediate layer may be interposed between the base material and the coating to increase the adhesive strength between the same. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、被覆硬質工具に関し、具体的には耐摩耗性の要求される切削工具やその他の耐摩工具として利用される被覆硬質合金工具のなかで、耐摩耗性、耐溶着性に優れる被覆硬質工具に関するものである。
【０００２】
【従来の技術】
耐摩耗性および表面保護機能改善のため、ＷＣ基超硬合金、サーメット、高速度鋼等の切削工具や耐摩耗工具などの硬質基材の表面に、硬質被覆層としてＴｉＡｌの窒化物を単層または複層形成することはよく知られている（例えば、非特許文献１参照）。
【０００３】
また、ＴｉＳｉ系の被覆膜である（Ｔｉ_１ ₋ _ｘＳｉ_ｘ）（Ｃ_１ ₋ _ｙＮ_ｙ）_ｚ（ただし、０．０１≦ｘ≦０．４５、０．０１≦ｙ≦０．１、０．５≦ｚ≦１．３４）は、高速連続切削に用いた場合、耐摩耗性に優れ、使用寿命を延長できることが知られている（例えば、特許文献１参照）。
【０００４】
【特許文献１】
特開平８−１１８１０６号公報（第２頁）
【非特許文献１】
「神戸製鋼技報」Ｖｏｌ．４１、Ｎｏ．３（１９９１）ｐ．１０
【０００５】
【発明が解決しようとする課題】
最近の切削工具の動向は、地球環境保全の観点から切削油剤を用いないドライ加工が求められていること、被削材が多様化していること、加工能率を一層向上させるため切削速度がより高速になってきていることなどである。従って、工具刃先温度はますます高温になる傾向にあり、工具材料に要求される特性は厳しくなる一方である。工具材料に要求される特性のうち、高温での被覆膜安定性、すなわち耐酸化特性や被覆膜の密着性は特に重要である。
【０００６】
さらに、切削工具寿命に関係する耐摩耗性、すなわち被覆膜の高温における硬度の向上や、潤滑油剤（切削油剤）に代わり被覆膜の潤滑特性が一段と重要となっているが、前記の非特許文献１に記載のＴｉＡｌの窒化物では不十分である。また、前記の特許文献１に記載される（Ｔｉ_１ ₋ _ｘＳｉ_ｘ）（Ｃ_１ ₋ _ｙＮ_ｙ）_ｚは、Ｃ量が少なければ高硬度ではあるが、摩擦係数が高く、被削材が工具表面に溶着し、工具が欠損するという問題があった。加えて、ドライ加工時に問題となる被覆膜の潤滑性は確認されていない。
【０００７】
【課題を解決するための手段】
発明者らはＴｉＳｉ系の被覆膜の耐摩耗性と潤滑性の両方を向上させるためには、耐摩耗性に優れた層の上に潤滑性を付与すれば、さらに切削性能が向上するという知見を得て本発明に至った。すなわち、本発明の被覆硬質工具は、基材と前記基材上に形成された被覆膜とを備え、前記被覆膜は（Ｔｉ_ｘＳｉ_ｙ）（Ｃ_ａＮ_ｂＯ_ｃ）（ただし、０．１≦ｙ≦０．８、ｘ＋ｙ＝１、０≦ａ≦０．６、０≦ｂ≦１．０、０≦ｃ≦０．５、ａ＋ｂ＋ｃ＝１）の組成であり、被覆膜中のＣ量が被覆膜中で基材側から表面側へかけて連続的または段階的に増加しているものである。
【０００８】
ここで、被覆膜中のＣ量の変化のさせ方であるが、図１（１）、（２）に示す通り、被覆膜中で基材側から表面に向かって、連続的にまたは段階的に増加させることができる。但し、図１（１）に示したＣ量の変化は直線で表されているが、その直線を単調に増加する曲線で置き換えることが出来る。
【０００９】
前記被覆膜中において、Ｓｉは被覆膜構成元素として不可欠である。要因は特定できていないが、Ｓｉを含有することで被覆膜硬度が向上するのでＳｉ量（ｙ）を０．１≦ｙ≦０．８とすると良好である。被覆膜中にＳｉ量（ｙ）が０．１以上存在すると、被覆膜の硬度が向上するので好ましいが、０．８を超えて含有すると被覆膜が脆くなり逆に摩耗が促進される。
【００１０】
また、Ｔｉ_ｘＳｉ_ｙの合金ターゲットを熱間静水圧加圧処理で作製する場合、ｙが０．８を超えてＳｉを含有させると、ターゲットが作製中に割れてしまいコーティングに使用可能な材料強度が得られないことがわかった。さらに好ましくは、被覆膜中のＳｉ量（ｙ）は０．１を越え０．３以下であることが好ましい。
【００１１】
また、（Ｔｉ_ｘＳｉ_ｙ）（Ｃ_ａＮ_ｂＯ_ｃ）（ただし、０．１≦ｙ≦０．８、ｘ＋ｙ＝１、０≦ａ≦０．６、０≦ｂ≦１．０、０≦ｃ≦０．５、ａ＋ｂ＋ｃ＝１）のなかでＣ量が被覆膜中で基材側から表面側へかけて増加すると、以下の効果がある。すなわち、基材と接する部分のＣ量を低くして基材との密着性を向上させ、表面のＣ量の多い部分で潤滑機能を持たせることができ、密着性と潤滑性を共に高めることができる。
【００１２】
本発明者らは、本発明の被覆硬質工具と鋼などの鉄系材料との焼きつき状態をピンオンディスク試験で評価したところ、被覆膜中のＣ量が多いほど被覆膜と鋼の焼きつきがなく、しかも摩擦係数が小さくなることを発見した。即ち、この被覆膜が工具に被覆されていると切削抵抗が小さく、工具寿命の延長が図れることがわかった。そこで前記被覆膜中のＣ量を基材側から表面に向かって連続的または段階的に増加させることにより、密着性と潤滑性の両方を高く維持でき、更なる工具の寿命延長が図れた。また、酸素を少量含有させることで、被覆膜の耐酸化性を向上することができる。高速切削では刃先温度が著しく高くなるため、酸素を含有していない被覆膜は酸化して体積変化し摩耗が進行するが、あらかじめ酸素を被覆膜中に含有させると、上記の現象が起こりにくく被覆膜を安定化することができる。
【００１３】
また、被覆硬質工具は基材表面と耐摩耗性を持つ被覆膜との間に形成されたＴｉもしくはＣｒの金属またはＴｉもしくはＣｒの窒化物を含む中間層をさらに備えることが好ましい。この場合の中間層は、基材表面と耐摩耗性を持つ被覆膜との両方に密着性が良いので、基材と耐摩耗性を持つ被覆膜の密着性を一層向上させることができる。
【００１４】
そのため、被覆膜が基材から剥がれることなく切削工具寿命をさらに向上させることができる。さらに、上記の中間層の厚みが０．０５μｍ以上１μｍ以下であることが好ましい。０．０５μｍ未満では密着強度の向上が見られず、逆に１μｍを越えても密着強度の更なる向上は見られなかった。
【００１５】
さらに、最表面層として（Ｔｉ_ｘＳｉ_ｙ）（Ｃ_ａＮ_ｂ）（ただし、ｘ＋ｙ＝１、０．１≦ｙ≦０．８、ａ＋ｂ＝１、０．１≦ａ≦０．６）で示される化合物層がさらに被覆されていることが望ましい。しかしながら、被覆膜と中間層と最表面層との合計厚み（被覆膜の総厚み）は０．５μｍ以上１０μｍ以下であることが好ましい。総厚みが０．５μｍ未満では耐摩耗性の向上が見られず、逆に１０μｍを越えると被覆膜中の残留応力が大きくなり基材との密着強度が低下するので好ましくない。
【００１６】
基材はＷＣ基超硬合金、サーメット、高速度鋼、セラミックス（炭化珪素、窒化珪素、窒化アルミニウム、酸化アルミニウムなど）、立方晶窒化硼素（ｃＢＮ）焼結体、ダイヤモンド焼結体、窒化珪素焼結体、酸化アルミニウムと炭化チタンの焼結体からなる基材のいずれかであることが好ましい。
【００１７】
本発明の被覆膜を基材表面に被覆するためには、結晶性の高い化合物を形成することができる成膜プロセスで作製されることが不可欠である。そこで、種々の成膜方法を検討した結果、物理的蒸着法を用いることが好ましい。
【００１８】
物理的蒸着法には、スパッタリング法、イオンプレーティング法などがあるが、特に、原料元素のイオン化率が高いアーク式イオンプレーティング法が一番適していることがわかった。このアーク式イオンプレーティング法を用いると、被覆膜を形成する前に、基材表面に対して金属のイオンボンバードメント処理が可能となるため、被覆膜の密着性が格段によくなるので、密着性という意味からも好ましいプロセスである。
【００１９】
【発明の実施の形態】
以下、本発明の実施の形態を説明する。
（実施例１）
本発明と比較例のサンプルを以下に説明する方法で作製した。発明品の基材として、ＳＤＫＮ４２形状のＩＳＯ　Ｐ３０の超硬合金を用いた。
（ｉ）本発明品の作製
図２はこの発明で用いた成膜装置の模式図である。成膜装置はチャンバー１とガスを供給するためのガス導入口２と、基板ホルダー４と、アーク式蒸発源６、７と、可変電源としての直流電源８、９と、基板バイアス直流電源１０とを備える。
【００２０】
チャンバー１は図示されない真空ポンプと連結されており、排気口３を通して、チャンバー１内の圧力を変化させることが可能である。チャンバー１内に基材５を保持するための基材ホルダー４が設けられている。基材ホルダー４には基板バイアス用の直流電源１０の負極と電気的に接続されている。基板バイアス電源１０の正極はアースされている。
【００２１】
チャンバー１の側壁には、アーク式蒸発源６、７が取り付けられている。アーク式蒸発源６、７は、直流電源８、９の負極と電気的に接続されている。直流電源８、９の正極はアースされ、かつチャンバー１と電気的に接続されている。アーク式蒸発源６、７とチャンバー１との間のアーク放電によって、アーク式蒸発源６、７を部分的に溶解させて蒸発源物質を基材方向に蒸発させるものである。アーク式蒸発源６、７とチャンバー１との間には数十から数百Ｖ程度の電圧が印加される。
【００２２】
チャンバー１にガスを供給するガス導入口２には、図示していないマスフローコントローラーを介して様々なガスが導入される。このガスの例として、アルゴン、窒素ガス、酸素ガスまたは、例えばメタン、アセチレン、ベンゼンなどの炭化水素ガスなどがある。
【００２３】
以下表１の発明品１を中心に、製造方法を詳細に説明する。まず、図２の蒸発源６に金属チタン、蒸発源７に（Ｔｉ_０．７Ｓｉ_０．３）を配置し、真空ポンプによりチャンバー１内を減圧するとともに、ヒーター（図示せず）により基材５を温度４５０℃に加熱し、チャンバー１内の圧力が１．０×１０⁻ ^３Ｐａとなるまで真空引きを行なった。次に、ガス導入口２からアルゴンガスを導入してチャンバー内の圧力を３．０Ｐａに保持し、基板バイアス電源１０の電圧を徐々に上げながら、−１０００Ｖとし、基材５の表面のクリーニングを１５分間行なった。その後、アルゴンガスを排気した。
【００２４】
次に、基板バイアス電源１０の電圧を−１０００Ｖに維持したまま、チャンバー１内にガス導入口２を通して１００ＳＣＣＭのアルゴンと、窒素の混合ガスを導入した。直流電源８から１００Ａのアーク電流を供給し、アーク式蒸発源６から金属イオンであるＴｉイオンを２分間発生させた。これにより、金属イオンが基材５の表面をスパッタクリーニングし、基材５の表面の強固な汚れや酸化膜が除去された。
【００２５】
その後、チャンバー１内の圧力が２．７Ｐａになるように、ガス導入口２から窒素ガスを導入し、基板バイアス電源１０の電圧を−１５０Ｖとした。すると、基材５の表面において金属窒化膜の形成が始まった。ＴｉＮの金属窒化膜が、０．３μｍの厚みに達するまでこの状態を維持した。これにより、中間層としてＴｉＮの金属窒化膜を形成した。ここで、窒素ガスを導入しなければ、中間層としてＴｉなどの金属膜が得られる。また、発明品２のようにＣｒＮを中間層とする場合は、蒸発源６に金属クロムを用いる。
【００２６】
中間層としてＴｉＮの金属窒化膜の形成が終了すると、直流電源９に通電しアーク式蒸発源７を構成するＴｉとＳｉの化合物を前方方向に蒸発させ、基材５の表面に所定の厚みの被覆膜を形成した。このようにして、表１に示す本発明の被覆硬質工具を作製した。また、発明品３は、蒸発源に（Ｔｉ_０．５Ｓｉ_０．５）を用いて上記と同様にして製造できる。別の方法としては、蒸発源６、７を併用して作製することもできる。一般的には、基板バイアス電圧を−２０〜−１００Ｖ、圧力を１〜４Ｐａ、アーク電流を１００Ａ程度の条件で被覆膜を形成する。
【００２７】
一方非金属元素は、例えば表１の酸炭窒化物を製造する場合、酸素、炭素、窒素の各元素を供給するガスである酸素ガス、メタンガス、窒素ガスなどの混合ガスで供給する。目的とする被覆膜の組成にあわせたガス組成で混合ガスを供給するので、本発明のように膜の組成を厚さ方向に変える場合は被覆膜生成の間にガス組成を変えていく。本発明では炭素濃度を次第に増加させるので、メタン、アセチレンなどの炭化水素ガスの流量を連続的に増加させることにより図１（１）のように被覆膜中のＣ量が連続的に増加する被覆膜が得られる。また、図１（２）のような被覆膜を得るためには段階的に炭化水素ガスの流量を増加させればよい。
【００２８】
（ｉｉ）比較品１の作製
比較品１の作製にあたっては、まず、本発明品と同じ基材を準備した。この基材を図２で示す基材ホルダー４にセットした。アーク式蒸発源６にチタン、アーク蒸発源７の材料をチタンアルミニウムの化合物（Ｔｉ_０．５、Ａｌ_０．５）とした。（Ｔｉ_０．５、Ａｌ_０．５）とは、ＴｉとＡｌの原子％が５０：５０の化合物をいう。その他の成膜装置の構成については、本発明品の製造と同様にした。
【００２９】
すなわち、本発明品を製造したのと同様の装置を用いて、同様の手法でアルゴンで基材５の表面をスパッタクリーニングし、その後、チタンでスパッタクリーニングした。さらに、本発明品を製造した工程と同様に基材５の表面に厚さが０．３μｍのＴｉＮ膜による中間層を形成した。
【００３０】
ＴｉＮ膜の形成が終了すると、直流電源９からアーク式蒸発源７へ１００Ａの電流を供給して、アーク式蒸発源７からチタンイオン、アルミニウムイオンを発生させた。また、同時に上部ガス導入口２から窒素ガスを導入した。これらが基材５の表面で反応して基材５上の中間層であるＴｉＮ膜上に膜厚が３μｍの（Ｔｉ_０．５Ａｌ_０．５）Ｎ膜が得られた。成膜中、基板バイアス電圧は６０Ｖ一定とした。これにより、従来製法による、ＴｉＡｌＮの耐摩耗性を有する比較品１を得た。
【００３１】
（ｉｉｉ）比較品２の作製
比較品２の作製の場合も、本発明品と同じ基材を準備した。この基材を図２で示す基材ホルダー４にセットした。アーク式蒸発源６にチタン、アーク式蒸発源７の材料をチタンシリコンの化合物（Ｔｉ_０．７Ｓｉ_０．３）とした。（Ｔｉ_０．７Ｓｉ_０．３）とは、ＴｉとＳｉの原子％が７０：３０の化合物をいう。その他の成膜装置の構成については本発明品の製造と同様にした。
【００３２】
図２に示す装置を用いて、本発明品を製造したのと同様の手法でアルゴンで基材５の表面をスパッタクリーニングし、その後、チタンでスパッタクリーニングした。さらに、本発明品を製造した工程と同様に基材５の表面に厚さが０．３μｍのＴｉＮ膜による中間層を形成した。
【００３３】
ＴｉＮ膜の形成が終了すると、直流電源９からアーク式蒸発源７へ１００Ａの電流を供給して、アーク式蒸発源７からチタンイオン、シリコンイオンを発生させた。また、同時に上部ガス導入口２から窒素ガスを導入した。これらが基材５の表面で反応して基材５上の中間層であるＴｉＮ膜上に膜厚が３μｍの（Ｔｉ_０．７ _、Ｓｉ_０．３）Ｎ膜が得られた。成膜中、基板バイアス電圧は６０Ｖ一定とした。これにより、従来製法によるＴｉＳｉＮの耐摩耗性を有する比較品２を得た。
【００３４】
（ｉｖ）比較品３の作製
比較品３は、比較品１と中間層形成までは全く同じ方法で製造した。その後、ＴｉＮ膜の形成が終了すると、直流電源９からアーク式蒸発源７へ１００Ａの電流を供給して、アーク式蒸発源７からチタンイオン、シリコンイオンを発生させると同時に、上部ガス導入口２から窒素ガスおよびメタンガスを導入した。これらが基材５の表面で反応して基材５上の中間層であるＴｉＮ膜上に膜厚が３μｍの（Ｔｉ_０． _７Ｓｉ_０．３）（Ｃ_０．５Ｎ_０．５）膜が得られた。成膜中基板バイアス電圧は１００Ｖ一定とした。これにより、従来製法によるＴｉＳｉＣＮの耐摩耗性を有する比較品３を得た。
【００３５】
（２）被覆硬質工具の寿命評価
上述の工程で製造したサンプルである本発明品、比較品１、２、３のそれぞれについて、実際に表２の条件による乾式の連続切削試験および断続切削試験を行い、刃先の逃げ面摩耗幅を測定した。寿命評価結果を表３に示す。表３から明らかなように本発明において切削工具の寿命が大きく向上したことが確認された。
【００３６】
【表１】

【００３７】
【表２】

【００３８】
【表３】

【００３９】
（実施例２）
実施例１と全く同じ方法により、リーマー（ＪＩＳ　Ｋ１０　超硬合金）にそれぞれコーティングした。試料は、表１に示す本発明品１、５、９および比較品１、２、３の膜を基材にコーティングして作製した。次に、これらのサンプルを用いて、実際に鋳鉄の穴開け加工を行いその寿命評価を行なった。
【００４０】
切削条件は、リーマー径２０ｍｍ、切削速度５ｍ／ｍｉｎ、送り０．４ｍｍ／刃、切り込み０．１５ｍｍ、湿式切削とした。なお寿命の判定は、被加工材の寸法精度が規定の範囲をはずれるまでに切削した個数で判定した。その寿命評価結果を表４に示す。その結果、本発明のリーマーの寿命が大きく向上していることが確認された。
【００４１】
【表４】

【００４２】
（実施例３）
実施例１に示した方法を用いて、エンドミル（ＪＩＳ　ＫｌＯ　超硬合金）にそれぞれにコーティングした。試料は、表１に示す本発明品１、５、９および比較品１、２、３の膜を基材にコーティングして作製した。次に、これらのサンプルを用いて、実際に鋳鉄のエンドミル側面削り（切削幅１５ｍｍ）加工を行いその寿命評価を行なった。
【００４３】
被削材はＳＫＤ６１、切削条件は、切削速度２００ｍ／ｍｉｎ、送り０．０７ｍｍ／刃、切り込みＡｄ＝１０ｍｍ，Ｒｄ＝０．２ｍｍ、湿式切削とし１０分間加工後の逃げ面摩耗量を測定した。その寿命評価結果を表４に示す。その結果、本発明のエンドミルの寿命が大きく向上していることが確認された。
【００４４】
（実施例４）
実施例１と全く同じ方法により、旋削用刃先交換型チップ（ＪＩＳ　Ｐ１０　超硬合金、刃先形状はスクイ角８°、逃げ角６°である）にそれぞれにコーティングした。試料は、表１に示す本発明品１、５、９および比較品１、２、３の膜を基材にコーティングして作製した。次に、これらのサンプルを用いて、実際に鋼の中仕上げ旋削加工を行いその寿命評価を行なった。
【００４５】
被削材はＳＣＭ４３５、切削条件は、切削速度１００ｍ／ｍｉｎ、送り０．０８ｍｍ／ｒｅｖ、切り込み２ｍｍ、湿式切削とし、３０分切削後の逃げ面摩耗量を測定した。その評価結果を表４に示す。その結果、本発明の旋削用刃先交換型チップの寿命が大きく向上していることが確認された。
【００４６】
（実施例５）
次に、ｃＢＮ焼結体からなる基材を用いた試料を作製し、切削性能を調べてみた。試料は、以下のようにして得た。まず、超硬合金製ポットおよびボールを用いて、重量で４０％のＴｉＮと１０％のＡｌからなる結合材粉末と５０％の平均粒径２．５μｍのｃＢＮ粉末を混ぜ合わせ、超硬合金製容器に充填し、圧力５ＧＰａ、温度１４００℃で６０分焼結した。このｃＢＮ焼結体を加工し、ＩＳＯ規格ＳＮＧＡ１２０４０８の形状の切削用チップを得た。そのチップに、実施例１と全く同じ方法により、表１に示す本発明品１の膜を成膜した。
【００４７】
この切削チップを用い、焼入鋼の１種であるＳＵＪ２の丸棒（ＨＲＣ６２）の外周切削を行った。切削速度１００ｍ／ｍｉｎ、切り込み０．２ｍｍ、送り０．１ｍｍ／ｒｅｖ、乾式で４０分間の条件で切削を行い、逃げ面摩耗量を調べた。比較として、基材表面に被覆膜を成膜していない試料についても、同様の切削試験を行い、逃げ面摩耗量を調べた。その結果、表１に示す本発明品１の膜を成膜した試料は、摩耗量が０．０８９ｍｍであったのに対し、表面に硬質膜が被覆されていないｃＢＮ焼結体チップの摩耗量は０．２２１ｍｍであった。
【００４８】
【発明の効果】
この発明に従えば、ドリル、エンドミル、フライス加工用および旋削用刃先交換型チップ、メタルソー、歯切工具、リーマー、タップなどの切削工具における耐摩耗性の向上が図れる。このため、寿命の長い被覆硬質工具を提供することができる。
【図面の簡単な説明】
【図１】基材表面から被覆膜表面に向かってＣ量の変化を示すグラフであり、（１）は、被覆膜中のＣ量が基材から膜表面に向かって連続的に増える場合、（２）は、被覆膜中のＣ量が基材から膜表面に向かって段階的に増える場合である。
【図２】本発明で用いた成膜装置の模式図である。
【符号の説明】
１　チャンバー
２　ガス導入口
３　排気口
４　基材ホルダー
５　基材
６、７　蒸発源
８、９　直流電源
１０　基板バイアス電源[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a coated hard tool, and more particularly to a coated hard alloy having excellent wear resistance and welding resistance among coated hard alloy tools used as cutting tools and other wear-resistant tools requiring wear resistance. It is about tools.
[0002]
[Prior art]
In order to improve wear resistance and surface protection function, a single layer of TiAl nitride is used as a hard coating layer on the surface of hard base materials such as cutting tools such as WC-based cemented carbide, cermet, and high-speed steel, and wear tools. Alternatively, it is well known to form multiple layers (for example, see Non-Patent Document 1).
[0003]
Further, a coating film of TiSi-based _{_{_{_{_{_{(Ti 1 - x Si x)}}}}}} (C 1 - y N y) z ( however, 0.01 ≦ x ≦ 0.45,0.01 ≦ y ≦ 0.1, (0.5 ≦ z ≦ 1.34) is known to be excellent in wear resistance and extend the service life when used for high-speed continuous cutting (for example, see Patent Document 1).
[0004]
[Patent Document 1]
JP-A-8-118106 (page 2)
[Non-patent document 1]
"Kobe Steel Engineering Report" Vol. 41, no. 3 (1991) p. 10
[0005]
[Problems to be solved by the invention]
Recent trends in cutting tools include the need for dry machining that does not use cutting oil from the viewpoint of global environmental conservation, the diversification of work materials, and higher cutting speeds to further improve machining efficiency. And so on. Accordingly, the tool edge temperature tends to be higher and higher, and the characteristics required for the tool material are becoming stricter. Among the characteristics required for the tool material, the stability of the coating film at a high temperature, that is, the oxidation resistance and the adhesion of the coating film are particularly important.
[0006]
Furthermore, the wear resistance related to the life of the cutting tool, that is, the improvement of the hardness of the coating film at a high temperature and the lubricating properties of the coating film have become more important in place of the lubricating oil (cutting oil). The nitride of TiAl described in Patent Document 1 is insufficient. Also, which are described in Patent Document 1 of the _{_{_{_{_{_{(Ti 1 - x Si x)}}}}}} (C 1 - y N y) z , albeit with fewer if high hardness C content, high coefficient of friction, the workpiece There is a problem that the tool is welded to the tool surface and the tool is broken. In addition, lubricity of the coating film, which is a problem during dry processing, has not been confirmed.
[0007]
[Means for Solving the Problems]
In order to improve both the wear resistance and the lubricity of the TiSi-based coating film, the inventors say that if lubricity is provided on a layer having excellent wear resistance, the cutting performance will be further improved. The present invention was obtained based on the findings. That is, coated hard tool of the present invention is provided with a coating film formed on the a substrate base material, the coating film _{_{_{_{(Ti x Si y) (C}}}} a N b O c) ( where 0.1 ≦ y ≦ 0.8, x + y = 1, 0 ≦ a ≦ 0.6, 0 ≦ b ≦ 1.0, 0 ≦ c ≦ 0.5, a + b + c = 1), and the coating film The C content in the coating film increases continuously or stepwise from the substrate side to the surface side in the coating film.
[0008]
Here, how to change the amount of C in the coating film, as shown in FIGS. 1 (1) and (2), continuously or from the substrate side to the surface in the coating film. Can be increased stepwise. However, although the change of the C amount shown in FIG. 1A is represented by a straight line, the straight line can be replaced by a curve that increases monotonically.
[0009]
In the coating film, Si is indispensable as a constituent element of the coating film. Although the cause has not been identified, since the coating film hardness is improved by containing Si, it is preferable to set the Si amount (y) to 0.1 ≦ y ≦ 0.8. It is preferable that the Si amount (y) is 0.1 or more in the coating film because the hardness of the coating film is improved. However, if the Si content (y) exceeds 0.8, the coating film becomes brittle and conversely, abrasion is promoted. You.
[0010]
Also, in the case where a Ti _x Si _y alloy target is produced by hot isostatic pressing, if y exceeds 0.8 and Si is contained, the target is cracked during production and a material that can be used for coating. It was found that strength could not be obtained. More preferably, the Si amount (y) in the coating film is more than 0.1 and not more than 0.3.
[0011]
_{_{_{_{Further, (Ti x Si y) (}}}} C a N b O c) ( although, 0.1 ≦ y ≦ 0.8, x + y = 1,0 ≦ a ≦ 0.6,0 ≦ b ≦ 1.0,0 ≦ c ≦ 0.5, a + b + c = 1), when the C content increases from the substrate side to the surface side in the coating film, the following effects are obtained. That is, it is possible to improve the adhesion with the base material by lowering the C content in the portion in contact with the base material, to provide a lubricating function in the portion with a large C content on the surface, and to improve both the adhesion and the lubricity. Can be.
[0012]
The present inventors have evaluated the seizure state between the coated hard tool of the present invention and an iron-based material such as steel by a pin-on-disk test. As the C content in the coating film increases, the coating film and the steel It was found that there was no seizure and the coefficient of friction was small. That is, it was found that when the coating film was coated on the tool, the cutting resistance was small and the tool life could be extended. Therefore, by continuously or stepwise increasing the amount of C in the coating film from the base material side to the surface, both the adhesion and the lubricity can be maintained high, and the life of the tool can be further extended. . Further, by including a small amount of oxygen, the oxidation resistance of the coating film can be improved. In high-speed cutting, the temperature of the cutting edge becomes extremely high, so the coating film that does not contain oxygen oxidizes and changes in volume and wear progresses.However, if oxygen is contained in the coating film in advance, the above phenomenon occurs. It is difficult to stabilize the coating film.
[0013]
Further, the coated hard tool preferably further includes an intermediate layer containing a metal of Ti or Cr or a nitride of Ti or Cr formed between the surface of the substrate and the coating film having wear resistance. In this case, since the intermediate layer has good adhesion to both the substrate surface and the wear-resistant coating film, the adhesion between the substrate and the wear-resistant coating film can be further improved. .
[0014]
Therefore, the life of the cutting tool can be further improved without the coating film coming off the base material. Further, it is preferable that the thickness of the intermediate layer is 0.05 μm or more and 1 μm or less. If the thickness is less than 0.05 μm, no improvement in the adhesion strength is seen, and if it exceeds 1 μm, no further improvement in the adhesion strength is seen.
[0015]
Further, in the outermost surface layer _{_{_{(Ti x Si y) (C}}} a N b) ( provided that, x + y = 1,0.1 ≦ y ≦ 0.8, a + b = 1,0.1 ≦ a ≦ 0.6) It is desirable that the indicated compound layer be further coated. However, the total thickness (total thickness of the coating film) of the coating film, the intermediate layer, and the outermost layer is preferably 0.5 μm or more and 10 μm or less. If the total thickness is less than 0.5 μm, no improvement in abrasion resistance is observed, while if it exceeds 10 μm, the residual stress in the coating film increases, and the adhesion strength to the substrate decreases, which is not preferable.
[0016]
The base material is WC based cemented carbide, cermet, high speed steel, ceramics (silicon carbide, silicon nitride, aluminum nitride, aluminum oxide, etc.), cubic boron nitride (cBN) sintered body, diamond sintered body, silicon nitride sintered body It is preferable that the substrate is any one of a sintered body and a sintered body of aluminum oxide and titanium carbide.
[0017]
In order to coat the surface of the substrate with the coating film of the present invention, it is indispensable that the film is formed by a film forming process capable of forming a compound having high crystallinity. Therefore, as a result of studying various film formation methods, it is preferable to use a physical vapor deposition method.
[0018]
The physical vapor deposition method includes a sputtering method, an ion plating method, and the like. In particular, it has been found that an arc ion plating method having a high ionization rate of a raw material element is most suitable. By using this arc ion plating method, before forming the coating film, it becomes possible to perform ion bombardment treatment of the metal on the substrate surface, so that the adhesion of the coating film is significantly improved, This is a preferable process from the viewpoint of adhesion.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described.
(Example 1)
Samples of the present invention and comparative examples were produced by the method described below. As a substrate of the invention, a cemented carbide of ISOP30 in the shape of SDKN42 was used.
(I) Preparation of the product of the present invention FIG. 2 is a schematic view of a film forming apparatus used in the present invention. The film forming apparatus includes a chamber 1, a gas inlet 2 for supplying gas, a substrate holder 4, arc evaporation sources 6 and 7, DC power supplies 8 and 9 as variable power supplies, and a substrate bias DC power supply 10. Is provided.
[0020]
The chamber 1 is connected to a vacuum pump (not shown), and the pressure in the chamber 1 can be changed through the exhaust port 3. A substrate holder 4 for holding a substrate 5 in the chamber 1 is provided. The substrate holder 4 is electrically connected to a negative electrode of a DC power source 10 for substrate bias. The positive electrode of the substrate bias power supply 10 is grounded.
[0021]
Arc evaporation sources 6 and 7 are attached to the side wall of the chamber 1. The arc evaporation sources 6 and 7 are electrically connected to the negative electrodes of the DC power supplies 8 and 9. The positive electrodes of the DC power supplies 8 and 9 are grounded and are electrically connected to the chamber 1. An arc discharge between the arc type evaporation sources 6, 7 and the chamber 1 partially dissolves the arc type evaporation sources 6, 7 to evaporate the evaporation source material toward the base material. A voltage of about several tens to several hundreds V is applied between the arc evaporation sources 6 and 7 and the chamber 1.
[0022]
Various gases are introduced into a gas inlet 2 for supplying a gas to the chamber 1 via a mass flow controller (not shown). Examples of this gas include argon, nitrogen gas, oxygen gas or a hydrocarbon gas such as methane, acetylene, benzene and the like.
[0023]
Hereinafter, the manufacturing method will be described in detail with reference to Invention 1 shown in Table 1. First, metal titanium is placed in the evaporation source 6 and (Ti _0.7 Si _0.3 ) is placed in the evaporation source 7 in FIG. 2, and the inside of the chamber 1 is depressurized by a vacuum pump, and the substrate is heated by a heater (not shown). 5 is heated to a temperature 450 ° C., the pressure in the chamber 1 is 1.0 × ¹⁰ ^- was performed evacuated until 3 Pa. Next, argon gas is introduced from the gas inlet 2 to maintain the pressure in the chamber at 3.0 Pa, and while the voltage of the substrate bias power supply 10 is gradually increased, the voltage is set to −1000 V to clean the surface of the substrate 5. Performed for 15 minutes. Thereafter, the argon gas was exhausted.
[0024]
Next, while maintaining the voltage of the substrate bias power supply 10 at −1000 V, a mixed gas of 100 SCCM of argon and nitrogen was introduced into the chamber 1 through the gas inlet 2. An arc current of 100 A was supplied from the DC power supply 8, and Ti ions as metal ions were generated from the arc evaporation source 6 for 2 minutes. As a result, the metal ions sputter-cleaned the surface of the substrate 5, and strong dirt and oxide films on the surface of the substrate 5 were removed.
[0025]
Thereafter, nitrogen gas was introduced from the gas inlet 2 so that the pressure in the chamber 1 became 2.7 Pa, and the voltage of the substrate bias power supply 10 was set to -150 V. Then, the formation of the metal nitride film on the surface of the substrate 5 started. This state was maintained until the metal nitride film of TiN reached a thickness of 0.3 μm. Thus, a metal nitride film of TiN was formed as an intermediate layer. Here, if nitrogen gas is not introduced, a metal film such as Ti is obtained as an intermediate layer. When CrN is used as the intermediate layer as in Invention 2, metal chromium is used for the evaporation source 6.
[0026]
When the formation of the metal nitride film of TiN as the intermediate layer is completed, the DC power supply 9 is energized to evaporate the compound of Ti and Si constituting the arc-type evaporation source 7 in the forward direction. A coating film was formed. Thus, the coated hard tool of the present invention shown in Table 1 was produced. The invention product 3 can be manufactured in the same manner as described above using (Ti _0.5 Si _0.5 ) as the evaporation source. As another method, it can also be produced by using the evaporation sources 6 and 7 together. Generally, a coating film is formed under the conditions of a substrate bias voltage of -20 to -100 V, a pressure of 1 to 4 Pa, and an arc current of about 100A.
[0027]
On the other hand, in the case of producing the oxycarbonitride shown in Table 1, for example, the nonmetallic element is supplied by a mixed gas such as oxygen gas, methane gas, or nitrogen gas, which is a gas for supplying oxygen, carbon, and nitrogen. Since the gas mixture is supplied with a gas composition that matches the composition of the target coating film, when the composition of the film is changed in the thickness direction as in the present invention, the gas composition is changed during the formation of the coating film. . In the present invention, since the carbon concentration is gradually increased, the C amount in the coating film is continuously increased as shown in FIG. 1 (1) by continuously increasing the flow rate of the hydrocarbon gas such as methane and acetylene. A coating film is obtained. Further, in order to obtain a coating film as shown in FIG. 1 (2), the flow rate of the hydrocarbon gas may be increased stepwise.
[0028]
(Ii) Preparation of Comparative Product 1 In preparing Comparative Product 1, first, the same base material as the product of the present invention was prepared. This substrate was set on the substrate holder 4 shown in FIG. The arc evaporation source 6 was made of titanium, and the material of the arc evaporation source 7 was made of a titanium aluminum compound (Ti _0.5 , Al _0.5 ). (Ti _0.5 , Al _0.5 ) refers to a compound in which the atomic percentage of Ti and Al is 50:50. Other configurations of the film forming apparatus were the same as in the manufacture of the product of the present invention.
[0029]
That is, the surface of the substrate 5 was sputter-cleaned with argon by the same method using the same apparatus as that used to manufacture the product of the present invention, and then sputter-cleaned with titanium. Further, an intermediate layer made of a 0.3 μm-thick TiN film was formed on the surface of the substrate 5 in the same manner as in the step of manufacturing the product of the present invention.
[0030]
When the formation of the TiN film was completed, a current of 100 A was supplied from the DC power supply 9 to the arc evaporation source 7 to generate titanium ions and aluminum ions from the arc evaporation source 7. At the same time, nitrogen gas was introduced from the upper gas inlet 2. These react on the surface of the base material 5 to obtain a (Ti _0.5 Al _0.5 ) N film having a thickness of 3 μm on the TiN film as an intermediate layer on the base material 5. During the film formation, the substrate bias voltage was kept constant at 60V. As a result, a comparative product 1 having abrasion resistance of TiAlN was obtained by a conventional manufacturing method.
[0031]
(Iii) Production of Comparative Product 2 In the case of producing Comparative Product 2, the same base material as the product of the present invention was prepared. This substrate was set on the substrate holder 4 shown in FIG. The arc evaporation source 6 was made of titanium, and the material of the arc evaporation source 7 was made of a titanium silicon compound (Ti _0.7 Si _0.3 ). (Ti _0.7 Si _0.3 ) refers to a compound in which the atomic percentage of Ti and Si is 70:30. Other configurations of the film forming apparatus were the same as in the manufacture of the product of the present invention.
[0032]
Using the apparatus shown in FIG. 2, the surface of the substrate 5 was sputter-cleaned with argon in the same manner as in the manufacture of the product of the present invention, and then sputter-cleaned with titanium. Further, an intermediate layer made of a 0.3 μm-thick TiN film was formed on the surface of the substrate 5 in the same manner as in the step of manufacturing the product of the present invention.
[0033]
When the formation of the TiN film was completed, a current of 100 A was supplied from the DC power supply 9 to the arc evaporation source 7 to generate titanium ions and silicon ions from the arc evaporation source 7. At the same time, nitrogen gas was introduced from the upper gas inlet 2. These react on the surface of the substrate 5 to form a (Ti _0.7 _, Si _0.3 ) N film having a thickness of 3 μm on the TiN film as an intermediate layer on the substrate 5. During the film formation, the substrate bias voltage was kept constant at 60V. Thus, a comparative product 2 having abrasion resistance of TiSiN by a conventional manufacturing method was obtained.
[0034]
(Iv) Production of Comparative Product 3 Comparative Product 3 was manufactured in exactly the same manner as Comparative Product 1 until the formation of the intermediate layer. Thereafter, when the formation of the TiN film is completed, a current of 100 A is supplied from the DC power supply 9 to the arc-type evaporation source 7 to generate titanium ions and silicon ions from the arc-type evaporation source 7 and at the same time, the upper gas inlet 2 , A nitrogen gas and a methane gas were introduced. These are on the TiN film thickness 3μm of an intermediate layer on the reaction and a substrate 5 on the surface of the substrate _{_{_{_{5 (Ti 0. 7 Si 0.3)}}}} (C 0.5 N 0.5) film was gotten. The substrate bias voltage was kept constant at 100 V during the film formation. Thus, a comparative product 3 having abrasion resistance of TiSiCN by a conventional manufacturing method was obtained.
[0035]
(2) Life evaluation of coated hard tool The dry continuous cutting test and the intermittent cutting test under the conditions shown in Table 2 were actually performed on each of the sample of the present invention and the

comparative products

1, 2, and 3 which were manufactured in the above-described steps. The flank wear width of the cutting edge was measured. Table 3 shows the life evaluation results. As is clear from Table 3, it was confirmed that the life of the cutting tool was significantly improved in the present invention.
[0036]
[Table 1]

[0037]
[Table 2]

[0038]
[Table 3]

[0039]
(Example 2)
The reamer (JIS K10 cemented carbide) was coated in exactly the same manner as in Example 1. Samples were prepared by coating films of the

present invention products

1, 5, and 9 and

comparative products

1, 2, and 3 shown in Table 1 on a substrate. Next, using these samples, drilling of cast iron was actually performed to evaluate the service life.
[0040]
The cutting conditions were a reamer diameter of 20 mm, a cutting speed of 5 m / min, a feed of 0.4 mm / tooth, a cutting depth of 0.15 mm, and wet cutting. The life was determined based on the number of pieces cut before the dimensional accuracy of the workpiece was out of the specified range. Table 4 shows the life evaluation results. As a result, it was confirmed that the life of the reamer of the present invention was greatly improved.
[0041]
[Table 4]

[0042]
(Example 3)
Using the method shown in Example 1, each of the end mills (JIS K10 cemented carbide) was coated. Samples were prepared by coating films of the

present invention products

1, 5, and 9 and

comparative products

1, 2, and 3 shown in Table 1 on a substrate. Next, using these samples, end mill side milling (cutting width 15 mm) of cast iron was actually performed to evaluate the life thereof.
[0043]
The work material was SKD61, the cutting conditions were a cutting speed of 200 m / min, a feed of 0.07 mm / blade, a cutting Ad = 10 mm, Rd = 0.2 mm, a wet cutting, and the flank wear after processing for 10 minutes was measured. Table 4 shows the life evaluation results. As a result, it was confirmed that the life of the end mill of the present invention was greatly improved.
[0044]
(Example 4)
In the exactly same manner as in Example 1, a tip-changing insert for turning (JIS P10 cemented carbide, the cutting edge shape of which is a rake angle of 8 ° and a relief angle of 6 °) was coated on each. Samples were prepared by coating films of the

present invention products

1, 5, and 9 and

comparative products

1, 2, and 3 shown in Table 1 on a substrate. Next, using these samples, semi-finishing turning of steel was actually performed to evaluate the life thereof.
[0045]
The work material was SCM435, the cutting conditions were a cutting speed of 100 m / min, a feed of 0.08 mm / rev, a depth of cut of 2 mm, and wet cutting, and the flank wear after cutting for 30 minutes was measured. Table 4 shows the evaluation results. As a result, it was confirmed that the life of the turning insert with a replaceable cutting edge of the present invention was greatly improved.
[0046]
(Example 5)
Next, a sample using a substrate made of a cBN sintered body was prepared, and cutting performance was examined. The sample was obtained as follows. First, using a cemented carbide pot and a ball, a binder powder composed of 40% TiN and 10% Al by weight and 50% cBN powder having an average particle diameter of 2.5 μm are mixed, and the cemented carbide alloy is used. The container was filled and sintered at a pressure of 5 GPa and a temperature of 1400 ° C. for 60 minutes. This cBN sintered body was processed to obtain a cutting tip having a shape of ISO standard SNGA120408. The film of the product 1 of the present invention shown in Table 1 was formed on the chip by the same method as in Example 1.
[0047]
Using this cutting tip, the outer periphery of a round bar (HRC62) of SUJ2, which is a kind of hardened steel, was cut. Cutting was performed under the conditions of a cutting speed of 100 m / min, a cutting depth of 0.2 mm, a feed of 0.1 mm / rev, and a dry system for 40 minutes, and the amount of flank wear was examined. For comparison, the same cutting test was performed on a sample in which a coating film was not formed on the substrate surface, and the flank wear amount was examined. As a result, the wear amount of the sample on which the film of the present invention product 1 shown in Table 1 was formed was 0.089 mm, whereas the wear amount of the cBN sintered body chip whose surface was not coated with the hard film was measured. Was 0.221 mm.
[0048]
【The invention's effect】
According to the present invention, the wear resistance of a cutting tool such as a drill, an end mill, a tip-changing insert for milling and turning, a metal saw, a tooth cutting tool, a reamer, and a tap can be improved. Therefore, a coated hard tool having a long life can be provided.
[Brief description of the drawings]
FIG. 1 is a graph showing a change in the amount of C from the surface of a base material to the surface of a coating film. FIG. 1 (1) shows that the amount of C in the coating film continuously increases from the substrate to the film surface. In the case (2), the amount of C in the coating film increases stepwise from the substrate toward the film surface.
FIG. 2 is a schematic diagram of a film forming apparatus used in the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Chamber 2 Gas inlet 3 Exhaust port 4 Substrate holder 5 Substrate 6, 7 Evaporation source 8, 9 DC power supply 10 Substrate bias power supply

Claims

And a coating film formed on the a substrate base material, the coating film _{_{_{_{(Ti x Si y) (C}}}} a N b O c) ( although, 0.1 ≦ y ≦ 0.8, x + y = 1, 0 ≦ a ≦ 0.6, 0 ≦ b ≦ 1.0, 0 ≦ c ≦ 0.5, a + b + c = 1), and the amount of C in the coating film is A coated hard tool which continuously increases from a base material side to a surface side.

And a coating film formed on the a substrate base material, the coating film _{_{_{_{(Ti x Si y) (C}}}} a N b O c) ( although, 0.1 ≦ y ≦ 0.8, x + y = 1, 0 ≦ a ≦ 0.6, 0 ≦ b ≦ 1.0, 0 ≦ c ≦ 0.5, a + b + c = 1), and the amount of C in the coating film is A coated hard tool characterized by increasing stepwise from a substrate side to a surface side.

3. The method according to claim 1, further comprising an intermediate layer made of a metal of Ti or Cr or a nitride of Ti or Cr having a thickness of 0.05 μm or more and 1.0 μm or less as a lowermost layer of the coating film. A coated hard tool as described.

On the surface of the coating film _{_{_{(Ti x Si y) (C}}} a N b) ( provided that x + y = 1,0.1 ≦ y ≦ 0.8, a + b = 1,0.1 ≦ a ≦ 0.6) The coated hard tool according to any one of claims 1 to 3, further comprising an outermost surface layer having a composition.

The coated hard tool according to any one of claims 1 to 4, wherein a total thickness of the coating film is 0.5 µm or more and 10 µm or less.

The coated hard tool according to any one of claims 1 to 5, wherein the coating film is coated by a physical vapor deposition method.

The coated hard tool according to claim 6, wherein the coating film is coated by an arc ion plating method.

The base material is any one of a base material made of WC-based cemented carbide, cermet, high-speed steel, ceramics, cubic boron nitride sintered body, diamond sintered body, silicon nitride sintered body, aluminum oxide and titanium carbide The coated hard tool according to any one of claims 1 to 7, wherein:

The coated hard tool is any one of a drill, an end mill, a tip-changeable insert for milling and turning, a metal saw, a tooth cutting tool, a reamer, and a tap. Coated hard tools.