JP3658949B2 - Coated cemented carbide - Google Patents
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- JP3658949B2 JP3658949B2 JP30159997A JP30159997A JP3658949B2 JP 3658949 B2 JP3658949 B2 JP 3658949B2 JP 30159997 A JP30159997 A JP 30159997A JP 30159997 A JP30159997 A JP 30159997A JP 3658949 B2 JP3658949 B2 JP 3658949B2
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Description
【０００１】
【発明の属する技術分野】
本発明は、被覆超硬合金に関し、より特定的には、切削工具などに使用される強靱かつ耐摩耗性に優れる被覆超硬合金に関するものである。
【０００２】
【従来の技術および発明が解決しようとする課題】
超硬合金の表面に炭化チタン、窒化チタン、炭窒化チタンあるいは酸化アルミニウムなどの被覆層を蒸着することにより切削工具の寿命を向上させることが行なわれており、一般に化学蒸着法、プラズマＣＶＤ（Chemical Vapor Deposition ）法、物理蒸着法などを用いて生成された被覆層などが広く普及している。
【０００３】
しかし、これらの被覆切削工具を用いて加工を行なった場合、特に鋼の高速切削加工や高速でのダクタイル鋳鉄の加工のように高温での被覆層の耐摩耗性が必要な加工、あるいは小物部品加工のように加工数が多く被削材への食いつき回数が多い加工などで被覆層の耐摩耗性が不足したり、被覆層の損傷、剥離が発生することによる工具寿命の低下が発生していた。
【０００４】
これらの課題を克服するために、これまでに被覆技術については、被覆層の組織制御あるいは、特開平８−１３２１３０号公報や特開平５−２６９６０６号公報に示されるような被覆層の配向性の制御など、多くの改良が試みられてきた。しかし、その効果は十分とは言えないのが現状であった。
【０００５】
それゆえ、本発明の目的は、優れた耐剥離性、耐摩耗性および耐クレータ性と優れた破壊強度とを有し、切削工具に適した被覆超硬合金を提供することである。
【０００６】
【課題を解決するための手段】
本願発明者らは、上記問題点を解決すべく鋭意検討した結果、従来の被覆切削工具用の被覆超硬合金に比較して、切削における被覆層の耐剥離性を大きく向上させるとともに、膜自体の耐摩耗性を向上させ、膜の破壊強度の向上を可能にすることにより、工具の寿命を安定して飛躍的に向上させ得る被覆超硬合金を見出した。
【０００７】
このため、本発明の被覆超硬合金は以下の構成を有する。
本発明の被覆超硬合金は、炭化タングステンを主成分とし、ＩＶａ、Ｖａ、ＶＩａ族金属の炭化物、窒化物、炭窒化物の少なくとも１種を含む硬質相とＣｏを主成分とする結合相とからなる超硬合金を基材とし、その基材の表面に形成された内層および外層を有するセラミックス被覆層を有し、内層および外層は以下の特徴を有する。
【０００８】
外層は、少なくとも酸化アルミニウム層を含み、その酸化アルミニウム層の結晶構造がα型を有している。
【０００９】
内層は、炭窒化チタン層および窒化チタン層を有する多層構造を有し、その炭窒化チタン層は１０μｍ以上の厚みを有する柱状組織からなり、炭窒化チタン層の配向性指数ＴＣを、
【００１０】
【数３】
と定義したとき、この式で表わされる（４２２）面と（３１１）面との配向性指数ＴＣ（４２２）、ＴＣ（３１１）がともに１．３以上３以下である。
【００１２】
本発明の被覆超硬合金において、炭窒化チタン層の配向性指数ＴＣ（４２２）、ＴＣ（３１１）をともに１．３以上とし、その組織を柱状組織とすることにより、１０μｍ以上の膜厚でも膜の耐破壊性を大きく向上させつつ耐摩耗性を向上させることが可能となる。ただし、配向性指数ＴＣ（４２２）、ＴＣ（３１１）が３を超えると、一定方向の配向が強くなりすぎることにより、逆に膜の耐破壊性が低下する。
【００１３】
また、耐摩耗性が向上するのは、１０μｍ以上の厚膜とした柱状組織の効果以外にも、膜の耐破壊性の向上により切削中に膜中のチッピングによる摩耗の進行が抑制される効果も大きいと考えられる。さらに、膜中のチッピングが生じにくくなることにより、これに起因する切削中の被削材の溶着が起こりにくくなり、膜にかかる切削応力の増大が防げることから耐剥離性が大幅に向上できる。
【００１４】
本構造において、炭窒化チタン層は、その被覆時の雰囲気をＴｉＣｌ4 、ＣＨ3 ＣＮ、Ｎ2 およびＨ2 とし、前半と後半との条件を次のように変更して成膜される。すなわち、成膜初期から１２０分の間は、（ＴｉＣｌ4 ＋ＣＨ3 ＣＮ）／トータルガス量の比率を後半に比べて小さくし、かつ前半のＮ2 ／トータルガス量の比率を後半の２倍以上とすることにより炭窒化チタン層は成膜される。
【００１５】
本発明の被覆超硬合金において、内層は炭窒化チタン層および窒化チタン層以外に、硼窒化チタン層を有し、外層は酸化アルミニウム層以外に炭化チタン層、炭窒化チタン層および窒化チタン層の少なくとも１層を有することが好ましい。
【００１６】
本発明の被覆超硬合金において、配向性指数ＴＣ（４２２）とＴＣ（３１１）とを除く配向性指数ＴＣ（ｈｋｌ）がすべて１．５以下であることが好ましい。
【００１７】
本発明の被覆超硬合金の構造において、炭窒化チタン層の配向性が、ＴＣ（４２２）とＴＣ（３１１）のみで強く、これらを除く結晶面の配向性指数ＴＣ（ｈｋｌ）がすべて１．５以下であることにより、より顕著な効果が得られる。
【００１８】
本発明の被覆超硬合金において、外層の酸化アルミニウム層の直下の層が、硼窒化チタン層であることが好ましい。
【００１９】
本発明の被覆超硬合金において、α型結晶構造の酸化アルミニウム層の配向性指数ＴＣａを、
【００２０】
【数４】
と定義したとき、この式で表わされる（１１０）面と（１０４）面との配向性指数は、ＴＣａ（１１０）≧１．２かつＴＣａ（１０４）≧１．２であることが好ましい。
【００２２】
本発明の被覆超硬合金の構造では、外層として上記の配向を有するα型結晶構造を主とする酸化アルミニウム層を被覆することにより、さらなる性能向上効果が得られる。
【００２３】
またさらなる性能向上効果の観点より、α型結晶構造の酸化アルミニウム層の配向性指数ＴＣａが、ＴＣａ（１０４）≧１．３かつＴＣａ（１１６）≧１．３であることが好ましい。
【００２４】
この構造により、すくい面で生じるクレータ摩耗を抑制する効果が向上する。これは、従来の膜質で生じていたクレータ摩耗は、一般に言われる化学摩耗と切り粉により生じた膜の剥離および膜の破壊といった機械的損傷の複合として現れていたのに対し、本発明の構造では酸化アルミニウム層の下地の膜強度、硬度が著しく向上している効果により、機械的損傷が抑制され、かつ酸化アルミニウム層の効果により化学的摩耗も抑制されることによる。
【００２５】
ここで、α型の酸化アルミニウム層は、ＡｌＣｌ3 およびＣＯ2 を原料ガスとする通常のＣＶＤプロセスにより製造される。一般に本原料ガスによるＣＶＤプロセスでは、酸化アルミニウムの結晶構造は、α、κあるいはθ構造が得られる。一般に酸化アルミニウムの中でκ型の酸化アルミニウムにおいて、最も微粒の酸化アルミニウムが得られやすく、高強度でかつ高密着度化が得られやすいとされている。しかし、κ型酸化アルミニウムは、比較的低温で安定な準安定相であるためか、硬度、特に高温硬度がα型酸化アルミニウムに比較して低く耐摩耗性に劣る傾向にあった。
【００２６】
本発明の内層の配向性との組合せと、α型酸化アルミニウム層の組合せにより、従来の問題点の１つであった密着強度の低下を抑制することに成功したものである。また、本発明の酸化アルミニウム層では、配向性を本発明の範囲とすることにより、α型酸化アルミニウムであるにもかかわらず、κ型並みの高強度を実現しつつ、酸化アルミニウム層の高硬度、高耐摩耗化することに成功したものである。
【００２７】
具体的なα型酸化アルミニウムの配向性の制御は、以下の方法による。まず、酸化アルミニウム層直下層まで被覆した後、酸化アルミニウム層の成膜を開始する前に、ＣＯ2 とキャリアとしてのＨ2 のみの雰囲気とし、この際のＣＯ2 分圧ＰCO2 を、ＰCO2 ＝０．３〜０．６ｔｏｒｒとし、５〜１０分間直下層を表面を部分的にわずかに酸化させ、その後、１０００〜１０５０℃の温度で酸化アルミニウム層を成膜する。これにより、酸化アルミニウム層の成膜温度にかかわらず、α型の酸化アルミニウム層の成膜が可能となるが、この際の直下層表面の酸化条件の選定により、酸化アルミニウム層の配向性の制御が可能である。また、同じ酸化条件を用いて酸化アルミニウム層の膜厚を変えることによっても配向性を変化させることが可能である。
【００２８】
なお、この直下層としてＴｉＮに硼素を微量添加したＴｉＢＮ層を用いることにより、上層の酸化アルミニウム層の密着度向上により有効である。
【００２９】
本発明の被覆超硬合金において、切刃稜線部付近のみにおいて酸化アルミニウム層が存在しないことが好ましい。
【００３０】
被覆層を被覆した後、その被覆層の表面にブラスト処理あるいは、ブラシ処理などの機械的処理により、切刃稜線部のみで酸化アルミニウム層が除去されるまで表面を処理することにより、上述の効果はより大きくなる。この際の処理の程度は、切刃稜線部の中でも実際に切削時に切り粉が接触する刃先部で確実に酸化アルミニウム層が除去されていることが必要である。しかし、処理の程度により、刃先から離れた位置の稜線部で酸化アルミニウム層が一部除去されずに残留していても全く問題はなく、本発明の効果は得られる。また、本発明では、酸化アルミニウム層が存在しないのは切刃稜線部のみとしているが、処理法によってはチップの座面周辺などの切削と関係ない角張った場所でも除去されることがあるが、これについても実質的には、本発明の効果には全く影響しない。
【００３１】
本発明の被覆超硬合金において、切刃稜線部において内層の炭窒化チタン層の引張り残留応力が１０ｋｇ／ｍｍ2 以下であることが好ましい。
【００３２】
上記のような膜表面処理により、被覆後、被覆層中に存在する引張り残留応力を内層のＴｉＣＮ層で１０ｋｇ／ｍｍ2 以下まで低減させることにより、膜の耐破壊に対する効果を向上させることが可能となる。
【００３３】
本発明の被覆超硬合金において、超硬合金の基材の表面部で炭化タングステンを除く硬質相が減少または消失した層を有し、その層の厚みが平坦部において５０μｍ以下であることが好ましい。
【００３４】
超硬合金基材の表面部で炭化タングステンを除く硬質相が減少または消失した層を有し、その厚みが平坦部において５０μｍ以下である表層部が強靱化された超硬合金と本発明の被覆層および表面処理とを組合せることにより、超硬合金部表層付近ごと被覆層が脱落するような損傷に対し、非常に効果がある。
【００３５】
基材表層領域の厚みを５０μｍ以下としたのは、５０μｍを超えると切削中に表層部でやや塑性変形あるいは弾性変形が生じる傾向があるためで、５０μｍ以下でより効果的であるためである。
【００３６】
なお、表層領域は、従来より知られているような窒素含有硬質相原料を用いる方法、または焼結時の昇温過程で加窒雰囲気とし結合相の液相出現後に脱窒、脱炭雰囲気とする方法で製造できる。
【００３７】
【実施例】
以下、本発明の実施例について説明する。
【００３８】
実施例１
基材として以下のＡ〜Ｄの組成でＣＮＭＧ１２０４０８の形状を有するＷＣ基超硬合金基材を準備した。
【００３９】
Ａ：ＷＣ−１０％Ｃｏ−３％ＺｒＣＮ−６％ＮｂＣ
Ｂ：ＷＣ−６％Ｃｏ−３％ＺｒＣＮ−２％ＴｉＣＮ
Ｃ：ＷＣ−１０％Ｃｏ−５％ＴｉＣＮ−３％ＮｂＣ
Ｄ：ＷＣ−６％Ｃｏ−２％ＺｒＣ−３％ＴｉＣ
この基材の表面に表１に示す内層および外層の構造の被覆膜を生成した。
【００４０】
【表１】
サンプルＡ〜Ｃの基材表層部には、ＷＣとＣｏのみからなる層が存在し、それぞれのサンプルにおけるその層の厚みは平坦部厚みで、Ａ：２５μｍ、Ｂ：５０μｍ、Ｃ：５５μｍであった。サンプルＤの基材表面には表層領域は存在しなかった。以下に本発明品の各層の被覆条件を示す。
【００４２】
（ＴｉＮ層）
温度：８８０℃、圧力：１２０ｔｏｒｒ、
反応ガス組成：容量％で、４６％Ｈ2 −４％ＴｉＣｌ4 −５０％Ｎ2
（本発明品１〜５のＴｉＣＮ層）
ＴｉＣＮ層（前半１２０分）：
温度：８８０℃、圧力：６８ｔｏｒｒ、
反応ガス組成：容量％で、６８．６％Ｈ2 −１．２％ＴｉＣｌ4 −０．２％ＣＨ3 ＣＮ−３０％Ｎ2
ＴｉＣＮ層（後半残り）：
温度：８８０℃、圧力：６８ｔｏｒｒ、
反応ガス組成：容量％で、７６．６％Ｈ2 −７．２％ＴｉＣｌ4 −１．２％ＣＨ3 ＣＮ−１５％Ｎ2
（ＴｉＢＮ層）
温度：９９０℃、圧力：１５０ｔｏｒｒ、
反応ガス組成：容量％で、４５．５％Ｈ2 −４％ＴｉＣｌ4 −４９％Ｎ2 −１．５％ＢＣｌ3
（Ａｌ2 Ｏ3 層）
温度：１０３０℃、圧力：６８ｔｏｒｒ、
反応ガス組成：容量％で、８５％Ｈ2 −９％ＡｌＣｌ3 −６％ＣＯ2
（ＴｉＣ層）
温度：１０３０℃、圧力：６８ｔｏｒｒ、
反応ガス組成：容量％で、９０％Ｈ2 −３％ＴｉＣｌ4 −７％ＣＨ4
ここで、内層のＴｉＣＮ層の配向性指数は、Ｘ線回折による回折ピークから求めた。この際、ＴｉＣＮの（３１１）面の回折ピークは基材のＷＣの（１１１）面ピークと重なり、（１１１）面のピーク強度は、（ＷＣの最強ピークである（１０１）面の強度）×０．２５であることから、ＴｉＣＮの（３１１）面の強度からこれを減じてＷＣ（１１１）面による強度分を差し引いた。
【００４３】
また、各試料のＴｉＣＮ層の配向性を表２に示す。またアルミナの配向性を表３に示す。
【００４４】
【表２】
【表３】
ここでアルミナ成膜前のＴｉＢＮ膜表面の酸化状態を変えることにより、アルミナの配向性を変えたサンプルを同時に作製し、これをたとえば１ａ、１ｂ、１ｃというように表記して表中に示した。ここで、ａの試料はＰCO2 ＝０．３ｔｏｒｒ、５分、ｂの試料はＰCO2 ＝０．４ｔｏｒｒ、１０分、ｃの試料はＰCO2 ＝０．６ｔｏｒｒ，１０分の酸化条件を用いたものである。
【００４７】
なお、本発明のＴｉＣＮ層は被覆後破断し、破断面のＳＥＭ（走査型電子顕微鏡）観察で柱状組織となっていることを確認した。
【００４８】
表１および２には比較のために比較品も併せて載せた。比較品６および７のＴｉＣＮ膜の成膜は、以下に示す条件で行なった。
【００４９】
（ＴｉＣＮ層（比較品６））
温度：８８０℃、圧力：６８ｔｏｒｒ、
反応ガス組成：容量％で、７６．６％Ｈ2 −７．２％ＴｉＣｌ4 −１．２％ＣＨ3 ＣＮ−１５％Ｎ2
（ＴｉＣＮ層（比較品７））
温度：１０００℃、圧力：１５０ｔｏｒｒ、
反応ガス組成：容量％で、９０％Ｈ2 −４％ＴｉＣｌ4 −４％ＣＨ4 −２％Ｎ2
また、比較品８のアルミナ層は、以下に示す成膜条件でκ型アルミナを生成した。なお、比較品８においては、アルミナ層以外は本発明品の条件で成膜を実施した。
【００５０】
（アルミナ層（比較品８））
温度：９８０℃、圧力：６８ｔｏｒｒ、
反応ガス組成：容量％で、８５％Ｈ2 −９％ＡｌＣｌ3 −６％ＣＯ2
（アルミナ生成前のＴｉＢＮ層表面の酸化処理は行なわず、アルミナの反応ガス組成で同時にアルミナ生成を開始）
以上のサンプルを用い、次に示す切削条件１および２で切削評価を行なった。
【００５１】
（切削条件１）
被削材：ＳＣＭ４１５（４溝材）
切削速度：２５０ｍ／ｍｉｎ
送り：０．２０ｍｍ／ｒｅｖ
切り込み：１．５ｍｍ
衝撃回数：５００回
切削油：水溶性
（切削条件２）
被削材：ＦＣＤ７０
切削速度：２５０ｍ／ｍｉｎ
送り：０．３ｍｍ／ｒｅｖ
切り込み：１．５ｍｍ
切削時間：１０分
切削油：水溶性
この評価結果を表４および表５に示す。
【００５２】
【表４】
【表５】
この結果から、本発明品では、従来品に比較して、膜の耐摩耗性、耐チッピング性と、耐クレータ性のいずれにおいても優れていることがわかる。
【００５５】
実施例２
実施例１で作製したサンプル１ａおよび２ａを用い、これに被覆層を被覆した後、稜線部のアルミナ層が除去されるまでＳｉＣ砥粒を含有するナイロンブラシで、膜表面に処理を施した。表面を処理した試料を作製し、これらを１ａＨおよび２ａＨとした。また、さらにこれに鉄粉を用いたブラスト処理を施した試料１ａＨＢおよび２ａＨＢを作製し、これらについてＸ線回折装置を用いて、ｓｉｎ2 ψ法により内層のＴｉＣＮ層の残留応力を測定した。応力測定結果を表６に、実施例１の切削条件１および２の条件で切削評価した結果を表７および表８に示す。
【００５６】
【表６】
【表７】
【表８】
これらの結果から、ブラスト処理を施さない試料１ａＨおよび２ａＨでは引張り残留応力がすべて１０ｋｇ／ｍｍ2 より大きかったのに対し、ブラスト処理を施した試料１ａＨＢおよび２ａＨＢでは引張り残留応力は１０ｋｇ／ｍｍ2 以下となることが判明した。またブラスト処理を施した試料１ａＨＢ、２ａＨＢでは、切削条件１および２の双方においてブラスト処理を施さない試料１ａＨ、２ａＨよりも逃げ面摩耗およびチッピングの双方が改善されることが判明した。
【００６０】
今回開示された実施例はすべての点で例示であって制限的なものではないと考えられるべきである。本発明の範囲は上記した説明ではなくて特許請求の範囲によって示され、特許請求の範囲と均等の意味および範囲内でのすべての変更が含まれることが意図される。
【００６１】
【発明の効果】
以上説明したように、本発明の被覆超硬合金においてはセラミックス被覆層の内層に含まれる炭窒化チタン層の配向性を所定の範囲とすることにより、優れた耐剥離性、耐摩耗性および耐クレータ性と優れた破壊強度とを有し、切削工具に適した被覆超硬合金を得ることができる。これにより、切削工具の寿命を安定して飛躍的に向上させることが可能となる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a coated cemented carbide, and more particularly to a coated cemented carbide that is used in cutting tools and the like and has excellent toughness and wear resistance.
[0002]
[Background Art and Problems to be Solved by the Invention]
The lifetime of cutting tools is improved by depositing a coating layer of titanium carbide, titanium nitride, titanium carbonitride, or aluminum oxide on the surface of cemented carbide. Generally, chemical vapor deposition, plasma CVD (Chemical CVD) Vapor Deposition) method, physical vapor deposition, etc. are widely used.
[0003]
However, when machining with these coated cutting tools, processing that requires wear resistance of the coating layer at high temperatures, such as high-speed machining of steel and ductile cast iron at high speed, or small parts There is a decrease in tool life due to insufficient wear resistance of the coating layer, damage to the coating layer, or peeling due to processing such as machining that involves a large number of processes and a high number of bites on the work material. It was.
[0004]
In order to overcome these problems, with respect to the coating technology so far, the texture control of the coating layer or the orientation of the coating layer as disclosed in JP-A-8-132130 and JP-A-5-269606 has been proposed. Many improvements have been attempted, such as control. However, the current situation is that the effect is not sufficient.
[0005]
Therefore, an object of the present invention is to provide a coated cemented carbide having excellent peeling resistance, wear resistance, crater resistance and excellent fracture strength, and suitable for a cutting tool.
[0006]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the inventors of the present application have greatly improved the peeling resistance of the coating layer in cutting compared to conventional coated cemented carbide for coated cutting tools, and the film itself. The present inventors have found a coated cemented carbide that can stably and dramatically improve the tool life by improving the wear resistance of the film and enabling the fracture strength of the film to be improved.
[0007]
For this reason, the coated cemented carbide of the present invention has the following configuration.
The coated cemented carbide of the present invention is mainly composed of tungsten carbide, a hard phase containing at least one of carbides, nitrides, and carbonitrides of group IVa, Va, and VIa metals, and a binder phase mainly containing Co. And a ceramic coating layer having an inner layer and an outer layer formed on the surface of the substrate. The inner layer and the outer layer have the following characteristics.
[0008]
The outer layer includes at least an aluminum oxide layer, and the crystal structure of the aluminum oxide layer has an α type.
[0009]
The inner layer, a titanium carbonitride layer and has a multilayer structure having a titanium nitride layer, the carbon nitride titanium layer consists columnar structure having a thickness of at least 10 [mu] m, the orientation index TC titanium carbonitride layer,
[0010]
[Equation 3]
The orientation indices TC (422) and TC (311) between the (422) plane and the (311) plane represented by this formula are both 1.3 or more and 3 or less.
[0012]
In the coated cemented carbide of the present invention, the orientation index TC (422) and TC (311) of the titanium carbonitride layer are both 1.3 or more, and the structure is a columnar structure. It is possible to improve the wear resistance while greatly improving the fracture resistance of the film. However, if the orientation indices TC (422) and TC (311) exceed 3, the orientation in a certain direction becomes too strong, and the fracture resistance of the film is reduced.
[0013]
In addition to the effect of the columnar structure having a thick film of 10 μm or more, the wear resistance is improved by the effect of suppressing the progress of wear due to chipping in the film during cutting by improving the fracture resistance of the film. Is also considered large. Further, since chipping in the film is less likely to occur, it is difficult to cause welding of the work material during cutting due to this, and an increase in cutting stress applied to the film can be prevented, so that the peel resistance can be greatly improved.
[0014]
In this structure, the titanium carbonitride layer is formed with TiCl 4 , CH 3 CN, N 2 and H 2 as the atmosphere at the time of coating, and the conditions of the first half and the second half are changed as follows. That is, for 120 minutes from the initial stage of film formation, the ratio of (TiCl 4 + CH 3 CN) / total gas amount is made smaller than the latter half, and the ratio of N 2 / total gas amount in the first half is more than twice that of the latter half. By doing so, the titanium carbonitride layer is formed.
[0015]
In coated cemented carbide of the present invention, the inner layer in addition to titanium carbonitride layer and the titanium nitride layer has a titanium boric nitride layer, the outer layer of titanium carbide layer other than the aluminum oxide layer, a titanium carbonitride layer and the titanium nitride layer It preferably has at least one layer.
[0016]
In the coated cemented carbide of the present invention, all of the orientation indices TC (hkl) excluding the orientation indices TC (422) and TC (311) are preferably 1.5 or less.
[0017]
In the structure of the coated cemented carbide of the present invention, the orientation of the titanium carbonitride layer is strong only with TC (422) and TC (311), and the orientation index TC (hkl) of the crystal plane excluding these is 1. By being 5 or less, a more remarkable effect can be obtained.
[0018]
In the coated cemented carbide of the present invention, the layer immediately below the outer aluminum oxide layer is preferably a titanium boronitride layer.
[0019]
In the coated cemented carbide of the present invention, the orientation index TCa of the aluminum oxide layer having an α-type crystal structure is
[0020]
[Expression 4]
The orientation index between the (110) plane and the (104) plane represented by this formula is preferably TCa (110) ≧ 1.2 and TCa (104) ≧ 1.2.
[0022]
In the structure of the coated cemented carbide of the present invention, a further performance improvement effect can be obtained by coating an aluminum oxide layer mainly having an α-type crystal structure having the above orientation as an outer layer.
[0023]
From the viewpoint of further improving the performance, the orientation index TCa of the aluminum oxide layer having the α-type crystal structure is preferably TCa (104) ≧ 1.3 and TCa (116) ≧ 1.3.
[0024]
This structure improves the effect of suppressing crater wear that occurs on the rake face. This is because the crater wear that occurred in the conventional film quality appeared as a composite of chemical damage generally called chemical wear and mechanical damage such as film peeling and film breakage caused by chips, whereas the structure of the present invention Then, mechanical damage is suppressed by the effect that the film strength and hardness of the base of the aluminum oxide layer are remarkably improved, and chemical wear is also suppressed by the effect of the aluminum oxide layer.
[0025]
Here, the α-type aluminum oxide layer is manufactured by a normal CVD process using AlCl 3 and CO 2 as source gases. In general, in the CVD process using this raw material gas, the crystal structure of aluminum oxide can be an α, κ or θ structure. In general, among κ-type aluminum oxides among aluminum oxides, the finest aluminum oxide is most easily obtained, and it is said that high strength and high adhesion can be easily obtained. However, because κ-type aluminum oxide is a metastable phase that is stable at a relatively low temperature, its hardness, particularly high-temperature hardness, is lower than that of α-type aluminum oxide and tends to be inferior in wear resistance.
[0026]
The combination of the orientation of the inner layer of the present invention and the combination of the α-type aluminum oxide layer succeeded in suppressing a decrease in adhesion strength, which was one of the conventional problems. In addition, in the aluminum oxide layer of the present invention, by setting the orientation within the range of the present invention, the high hardness of the aluminum oxide layer is achieved while realizing the high strength of the κ type in spite of being α-type aluminum oxide. It has succeeded in achieving high wear resistance.
[0027]
The specific control of the orientation of the α-type aluminum oxide is performed by the following method. First, after coating the aluminum oxide layer immediately below, and before starting the film formation of the aluminum oxide layer, an atmosphere of only CO 2 and H 2 as a carrier is set, and the CO 2 partial pressure P CO2 at this time is changed to P CO2 = 0.3 to 0.6 torr, the surface of the immediate lower layer is partially oxidized for 5 to 10 minutes, and then an aluminum oxide layer is formed at a temperature of 1000 to 1050 ° C. This makes it possible to form an α-type aluminum oxide layer regardless of the film formation temperature of the aluminum oxide layer. However, the orientation of the aluminum oxide layer can be controlled by selecting the oxidation conditions on the surface immediately below the surface. Is possible. The orientation can also be changed by changing the film thickness of the aluminum oxide layer using the same oxidation conditions.
[0028]
By using a TiBN layer in which a slight amount of boron is added to TiN as the immediate lower layer, it is effective to improve the adhesion of the upper aluminum oxide layer.
[0029]
In the coated cemented carbide of the present invention, it is preferable that an aluminum oxide layer does not exist only in the vicinity of the cutting edge ridge.
[0030]
After the coating layer is coated, the above-mentioned effect is obtained by treating the surface of the coating layer by mechanical treatment such as blasting or brushing until the aluminum oxide layer is removed only at the edge portion of the cutting edge. Becomes bigger. The degree of the treatment at this time requires that the aluminum oxide layer be surely removed at the cutting edge ridge line portion at the cutting edge portion where the cutting chips actually contact during cutting. However, there is no problem even if the aluminum oxide layer remains without being partially removed at the ridge line portion at a position away from the blade edge depending on the degree of treatment, and the effect of the present invention can be obtained. Further, in the present invention, the aluminum oxide layer is not present only in the cutting edge ridge line portion, but depending on the processing method, it may be removed even in an angular place unrelated to cutting such as the periphery of the seat surface of the chip, This also substantially does not affect the effect of the present invention.
[0031]
In the coated cemented carbide of the present invention, it is preferable that the tensile residual stress of the inner titanium carbonitride layer is 10 kg / mm 2 or less at the edge portion of the cutting edge.
[0032]
With the film surface treatment as described above, after coating, the tensile residual stress existing in the coating layer can be reduced to 10 kg / mm 2 or less with the TiCN layer of the inner layer, thereby improving the effect of the film against breakage. It becomes.
[0033]
The coated cemented carbide of the present invention preferably has a layer in which the hard phase excluding tungsten carbide is reduced or eliminated at the surface portion of the cemented carbide substrate, and the thickness of the layer is preferably 50 μm or less in the flat portion. .
[0034]
Cemented carbide having a layer in which the hard phase excluding tungsten carbide is reduced or eliminated at the surface portion of the cemented carbide base material, and the surface layer portion having a thickness of 50 μm or less in the flat portion is toughened, and the coating of the present invention By combining the layer and the surface treatment, it is very effective against damage that causes the coating layer to fall off in the vicinity of the surface layer of the cemented carbide part.
[0035]
The reason why the thickness of the substrate surface layer region is set to 50 μm or less is that when it exceeds 50 μm, there is a tendency for slight plastic deformation or elastic deformation to occur in the surface layer part during cutting, and it is more effective at 50 μm or less.
[0036]
Note that the surface layer region is a method using a nitrogen-containing hard phase raw material as conventionally known, or a denitrification or decarburization atmosphere after the appearance of a liquid phase of a binder phase as a nitriding atmosphere in a temperature rising process during sintering. It can manufacture by the method to do.
[0037]
【Example】
Examples of the present invention will be described below.
[0038]
Example 1
A WC-based cemented carbide substrate having the shape of CNMG120408 was prepared as a substrate with the following compositions A to D.
[0039]
A: WC-10% Co-3% ZrCN-6% NbC
B: WC-6% Co-3% ZrCN-2% TiCN
C: WC-10% Co-5% TiCN-3% NbC
D: WC-6% Co-2% ZrC-3% TiC
A coating film having an inner layer structure and an outer layer structure shown in Table 1 was formed on the surface of the substrate.
[0040]
[Table 1]
In the base material surface layer portion of Samples A to C, there is a layer composed only of WC and Co, and the thickness of each layer in each sample is a flat portion thickness, A: 25 μm, B: 50 μm, C: 55 μm. It was. There was no surface layer region on the surface of the sample D substrate. The coating conditions for each layer of the product of the present invention are shown below.
[0042]
(TiN layer)
Temperature: 880 ° C., pressure: 120 torr,
Reaction gas composition: 46% H 2 -4% TiCl 4 -50% N 2 in volume%
(TiCN layer of products 1 to 5 of the present invention)
TiCN layer (first half 120 minutes):
Temperature: 880 ° C., pressure: 68 torr,
Reaction gas composition:% by volume, 68.6% H 2 -1.2% TiCl 4 -0.2% CH 3 CN-30% N 2
TiCN layer (second half remaining):
Temperature: 880 ° C., pressure: 68 torr,
Reactive gas composition:% by volume, 76.6% H 2 -7.2% TiCl 4 -1.2% CH 3 CN-15% N 2
(TiBN layer)
Temperature: 990 ° C., pressure: 150 torr,
Reaction gas composition:% by volume, 45.5% H 2 -4% TiCl 4 -49% N 2 -1.5% BCl 3
(Al 2 O 3 layer)
Temperature: 1030 ° C., pressure: 68 torr,
Reaction gas composition: volume%, 85% H 2 -9% AlCl 3 -6% CO 2
(TiC layer)
Temperature: 1030 ° C., pressure: 68 torr,
Reaction gas composition: volume%, 90% H 2 -3% TiCl 4 -7% CH 4
Here, the orientation index of the inner TiCN layer was determined from a diffraction peak by X-ray diffraction. At this time, the diffraction peak of the (311) plane of TiCN overlaps with the (111) plane peak of the WC of the substrate, and the peak intensity of the (111) plane is (the intensity of the (101) plane which is the strongest peak of WC) × Since it was 0.25, this was subtracted from the strength of the (311) plane of TiCN, and the strength due to the WC (111) plane was subtracted.
[0043]
Table 2 shows the orientation of the TiCN layer of each sample. Table 3 shows the orientation of alumina.
[0044]
[Table 2]
[Table 3]
Here, by changing the oxidation state of the TiBN film surface before the alumina film formation, samples with different alumina orientations were produced at the same time, which were expressed as 1a, 1b, 1c, for example, in the table. . Here, the sample a was P CO2 = 0.3 torr, 5 minutes, the sample b was P CO2 = 0.4 torr, 10 minutes, and the sample c was P CO2 = 0.6 torr, 10 minutes. Is.
[0047]
The TiCN layer of the present invention was fractured after coating, and it was confirmed that the fractured surface had a columnar structure by SEM (scanning electron microscope) observation.
[0048]
Tables 1 and 2 also show comparative products for comparison. The TiCN films of comparative products 6 and 7 were formed under the following conditions.
[0049]
(TiCN layer (Comparative product 6))
Temperature: 880 ° C., pressure: 68 torr,
Reactive gas composition:% by volume, 76.6% H 2 -7.2% TiCl 4 -1.2% CH 3 CN-15% N 2
(TiCN layer (Comparative product 7))
Temperature: 1000 ° C., pressure: 150 torr,
Reaction gas composition:% by volume, 90% H 2 -4% TiCl 4 -4% CH 4 -2% N 2
Moreover, the alumina layer of the comparative product 8 produced κ-type alumina under the following film forming conditions. In Comparative Product 8, the film was formed under the conditions of the product of the present invention except for the alumina layer.
[0050]
(Alumina layer (Comparative product 8))
Temperature: 980 ° C., pressure: 68 torr,
Reaction gas composition: volume%, 85% H 2 -9% AlCl 3 -6% CO 2
(The TiBN layer surface is not oxidized before the alumina is produced, and alumina production starts simultaneously with the reaction gas composition of alumina.)
Using the above samples, cutting evaluation was performed under the following cutting conditions 1 and 2.
[0051]
(Cutting condition 1)
Work material: SCM415 (4 groove material)
Cutting speed: 250 m / min
Feed: 0.20mm / rev
Cutting depth: 1.5mm
Number of impacts: 500 times Cutting oil: Water-soluble (Cutting condition 2)
Work material: FCD70
Cutting speed: 250 m / min
Feed: 0.3mm / rev
Cutting depth: 1.5mm
Cutting time: 10 minutes Cutting oil: Water-soluble Table 4 and Table 5 show the evaluation results.
[0052]
[Table 4]
[Table 5]
From this result, it can be seen that the product of the present invention is superior in film abrasion resistance, chipping resistance, and crater resistance as compared with the conventional product.
[0055]
Example 2
Samples 1a and 2a produced in Example 1 were used, and the coating layer was coated thereon, and then the membrane surface was treated with a nylon brush containing SiC abrasive grains until the ridgeline alumina layer was removed. Samples whose surfaces were treated were prepared and designated as 1aH and 2aH. Furthermore, samples 1aHB and 2aHB, which were further subjected to blasting using iron powder, were prepared, and the residual stress of the inner TiCN layer was measured by the sin 2 ψ method using an X-ray diffractometer. The stress measurement results are shown in Table 6, and the results of cutting evaluation under the conditions of cutting conditions 1 and 2 of Example 1 are shown in Tables 7 and 8.
[0056]
[Table 6]
[Table 7]
[Table 8]
From these results, the tensile residual stresses of samples 1aH and 2aH without blasting were all greater than 10 kg / mm 2 , whereas the tensile residual stresses of blasted samples 1aHB and 2aHB were 10 kg / mm 2 or less. Turned out to be. Further, it was found that samples 1aHB and 2aHB subjected to blasting were improved in both flank wear and chipping over samples 1aH and 2aH not subjected to blasting in both cutting conditions 1 and 2.
[0060]
It should be understood that the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
[0061]
【The invention's effect】
As described above, in the coated cemented carbide of the present invention, by setting the orientation of the titanium carbonitride layer contained in the inner layer of the ceramic coating layer within a predetermined range, excellent peeling resistance, wear resistance and resistance to wear are achieved. A coated cemented carbide having crater properties and excellent fracture strength and suitable for a cutting tool can be obtained. As a result, the life of the cutting tool can be stably and dramatically improved.
Claims (9)
前記内層が、炭窒化チタン層および窒化チタン層を有する多層構造を有し、
前記外層が、少なくとも酸化アルミニウム層を含み、前記酸化アルミニウム層の結晶構造がα型を有し、
前記内層の炭窒化チタン層は１０μｍ以上の厚みを有する柱状組織からなり、前記炭窒化チタン層の配向性において、以下の式で表される（４２２）面と（３１１）面との配向性指数ＴＣ（４２２）、ＴＣ（３１１）がともに１．３以上３以下であることを特徴とする、被覆超硬合金。
The inner layer has a multilayer structure having a titanium carbonitride layer and a titanium nitride layer ;
The outer layer includes at least an aluminum oxide layer, and the crystal structure of the aluminum oxide layer has an α-type;
The inner titanium carbonitride layer has a columnar structure having a thickness of 10 μm or more, and the orientation index of the (422) plane and the (311) plane represented by the following formula in the orientation of the titanium carbonitride layer. A coated cemented carbide characterized in that TC (422) and TC (311) are both 1.3 or more and 3 or less.
前記外層は前記酸化アルミニウム層以外に、炭化チタン層、炭窒化チタン層および窒化チタン層の少なくとも１層を有する、請求項１に記載の被覆超硬合金。The inner layer in addition to the titanium carbonitride layer and the titanium nitride layer has a titanium boric nitride layer,
2. The coated cemented carbide according to claim 1, wherein the outer layer includes at least one of a titanium carbide layer, a titanium carbonitride layer, and a titanium nitride layer in addition to the aluminum oxide layer.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP30159997A JP3658949B2 (en) | 1997-11-04 | 1997-11-04 | Coated cemented carbide |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP30159997A JP3658949B2 (en) | 1997-11-04 | 1997-11-04 | Coated cemented carbide |
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-
1997
- 1997-11-04 JP JP30159997A patent/JP3658949B2/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP3195959A4 (en) * | 2014-08-01 | 2018-03-21 | Tungaloy Corporation | Coated cutting tool |
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|---|---|
| JPH11140647A (en) | 1999-05-25 |
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