JP5682500B2 - Surface coated cutting tool with excellent chipping resistance and wear resistance due to hard coating layer - Google Patents
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この発明は、鋼や鋳鉄等の高速断続切削加工において、硬質被覆層がすぐれた耐チッピング性と耐摩耗性を備え、長期の使用に亘ってすぐれた切削性能を発揮する表面被覆切削工具（以下、被覆工具という）に関するものである。 The present invention provides a surface-coated cutting tool (hereinafter referred to as a surface-coated cutting tool) which has excellent chipping resistance and wear resistance with a hard coating layer in high-speed intermittent cutting of steel, cast iron, etc., and exhibits excellent cutting performance over a long period of use. , Referred to as a coated tool).
従来、一般に、炭化タングステン（以下、ＷＣで示す）基超硬合金または炭窒化チタン（以下、ＴｉＣＮで示す）基サーメットで構成された基体（以下、これらを総称して工具基体という）の表面に、
（ａ）下部層が、いずれも化学蒸着形成された、Ｔｉの炭化物（以下、ＴｉＣで示す）層、窒化物（以下、同じくＴｉＮで示す）層、炭窒化物（以下、ＴｉＣＮで示す）層、炭酸化物（以下、ＴｉＣＯで示す）層、および炭窒酸化物（以下、ＴｉＣＮＯで示す）層のうちの２層以上からなり、かつ３〜２０μｍの合計平均層厚を有するＴｉ化合物層、
（ｂ）上部層が、化学蒸着形成された、１〜１５μｍの平均層厚を有する酸化アルミニウム（以下、Ａｌ２Ｏ３で示す）層、
以上（ａ）および（ｂ）で構成された硬質被覆層を形成してなる被覆工具が知られている。
Conventionally, generally on the surface of a substrate (hereinafter collectively referred to as a tool substrate) composed of a tungsten carbide (hereinafter referred to as WC) -based cemented carbide or titanium carbonitride (hereinafter referred to as TiCN) -based cermet. ,
(A) Ti carbide (hereinafter referred to as TiC) layer, nitride (hereinafter also referred to as TiN) layer, carbonitride (hereinafter referred to as TiCN) layer formed by chemical vapor deposition of the lower layers. A Ti compound layer consisting of two or more of a carbon oxide (hereinafter referred to as TiCO) layer and a carbonitride oxide (hereinafter referred to as TiCNO) layer and having a total average layer thickness of 3 to 20 μm,
(B) an aluminum oxide (hereinafter referred to as Al 2 O 3 ) layer having an average layer thickness of 1 to 15 μm, in which the upper layer is formed by chemical vapor deposition;
A coated tool formed by forming a hard coating layer composed of (a) and (b) above is known.
また、特許文献１に示すように、上記の従来被覆工具において、下部層であるＴｉ化合物層を構成するＴｉＣＮ層を、通常の化学蒸着装置にて、反応ガスとして有機炭窒化物を含む混合ガスを使用し、７００〜９５０℃の中温温度域で化学蒸着し縦長成長結晶組織をもつＴｉＣＮ層を形成することにより、硬質被覆層自身の強度向上を図ることが知られている。 Moreover, as shown in Patent Document 1, in the above-mentioned conventional coated tool, a TiCN layer constituting the lower layer Ti compound layer is mixed gas containing organic carbonitride as a reaction gas in an ordinary chemical vapor deposition apparatus. It is known to improve the strength of the hard coating layer itself by forming a TiCN layer having a vertically grown crystal structure by chemical vapor deposition at a medium temperature range of 700 to 950 ° C.
さらに、特許文献２、３に示すように、上記の従来被覆工具において、下部層であるＴｉ化合物層を構成するＴｉＣＮ層について、工具基体側に位置するＴｉ化合物層の水平方向の結晶粒径（結晶幅）と、上部層側に位置するＴｉ化合物層の水平方向の結晶粒径（結晶幅）とに所定の関係を維持せしめることにより、硬質被覆層の耐チッピング性、耐欠損性、耐摩耗性の向上を図ることも知られている。 Furthermore, as shown in Patent Documents 2 and 3, in the above-described conventional coated tool, the horizontal grain size of the Ti compound layer located on the tool base side (TiCN layer constituting the lower Ti compound layer) By maintaining a predetermined relationship between the crystal width) and the horizontal crystal grain size (crystal width) of the Ti compound layer located on the upper layer side, the chipping resistance, chipping resistance, and abrasion resistance of the hard coating layer are maintained. It is also known to improve the performance.
近年の切削装置の高性能化はめざましく、一方で切削加工に対する省力化および省エネ化、さらに低コスト化の要求は強く、これに伴い、切削加工は一段と高速化の傾向にあるが、上記の従来被覆工具においては、これを鋼や鋳鉄などの通常の条件での連続切削や断続切削に用いた場合には問題はないが、特にこれを、高熱発生を伴い、かつ、切刃部に断続的・衝撃的負荷がかかる高速断続切削に用いた場合には、硬質被覆層にはチッピング（微小欠け）、欠損等が発生し易くなり、また、耐摩耗性も十分であるとは言えないため、比較的短時間で使用寿命に至るのが現状である。 In recent years, the performance of cutting machines has been remarkable. On the other hand, there is a strong demand for labor saving, energy saving, and cost reduction for cutting work, and along with this, cutting work tends to be further accelerated. In the case of a coated tool, there is no problem when it is used for continuous cutting or intermittent cutting under normal conditions such as steel or cast iron, but this is accompanied by high heat generation and intermittently at the cutting edge. -When used for high-speed intermittent cutting that requires an impact load, the hard coating layer is likely to have chipping (microchips), chipping, etc., and it cannot be said that the wear resistance is sufficient. At present, the service life is reached in a relatively short time.
そこで、本発明者等は、上述のような観点から、上記の被覆工具の硬質被覆層の耐チッピング性、耐摩耗性向上を図るべく、これの下部層、特に、上部層に隣接し相対的に高い高温硬さと高温強度を有し、かつ図１（ａ）に模式図で示される通り、格子点にＴｉ、炭素、および窒素からなる構成原子がそれぞれ存在するＮａＣｌ型面心立方晶の結晶構造（なお、図１（ｂ）は（０１１）面で切断した状態を示す）を有する縦長成長結晶組織をもつＴｉＣＮ層（以下、ｌ−ＴｉＣＮ層という）に着目し、鋭意研究を行った。 In view of the above, the inventors of the present invention have made it possible to improve the chipping resistance and the wear resistance of the hard coating layer of the above-mentioned coated tool by adjoining the lower layer, in particular, the upper layer. As shown in the schematic diagram of FIG. 1A, NaCl-type face-centered cubic crystals having constituent atoms composed of Ti, carbon, and nitrogen, respectively, at the lattice points. Focusing on a TiCN layer having a vertically grown crystal structure (hereinafter referred to as an l-TiCN layer) having a structure (note that FIG. 1B shows a state cut along the (011) plane), intensive research was conducted.
（ａ）まず、従来被覆工具の硬質被覆層は、例えば、通常の化学蒸着装置にて、
反応ガス組成：容量％で、ＴｉＣｌ４：２〜１０％、ＣＨ３ＣＮ：０．５〜３％、Ｎ２：１０〜３０％、Ｈ2：残り、
反応雰囲気温度：８００〜９００℃、
反応雰囲気圧力：６〜２０ｋＰａ、
の条件（通常条件という）でｌ−ＴｉＣＮ層からなる下部層を蒸着した後、この上に、Ａｌ２Ｏ３層を上部層として蒸着することにより形成される。
本発明者らは、上記ｌ−ＴｉＣＮ層を通常条件で蒸着する成膜工程の途中段階で、上記反応雰囲気圧力を低下させ、同時に、微量のＣＯ２成分を短時間反応ガス中に添加して成膜を行い、その後は、上記通常条件にしたがって、所定目標層厚のｌ−ＴｉＣＮ層が形成されるまで蒸着を継続し、その後、この上にＡｌ２Ｏ３層からなる上部層を蒸着形成したところ、
成膜されたｌ−ＴｉＣＮ層の表層近傍には酸素濃化領域が形成され、しかも、成膜されたｌ−ＴｉＣＮ層の酸素濃化領域における結晶粒は微細化組織となり、そして、この上に蒸着形成されたＡｌ２Ｏ３層の結晶粒も微細化されることを見出したのである。
(A) First, the hard coating layer of the conventional coated tool is, for example, an ordinary chemical vapor deposition apparatus.
Reaction gas composition: by volume%, TiCl 4: 2~10%, CH 3 CN: 0.5~3%, N 2: 10~30%, H 2: remainder,
Reaction atmosphere temperature: 800 to 900 ° C.
Reaction atmosphere pressure: 6-20 kPa,
After forming a lower layer made of an l-TiCN layer under the above conditions (referred to as normal conditions), an Al 2 O 3 layer is deposited thereon as an upper layer.
The inventors reduced the reaction atmosphere pressure in the middle of the film forming process for depositing the l-TiCN layer under normal conditions, and simultaneously added a small amount of CO 2 component to the reaction gas for a short time. After film formation, vapor deposition is continued until an l-TiCN layer having a predetermined target layer thickness is formed in accordance with the above-described normal conditions, and then an upper layer composed of an Al 2 O 3 layer is vapor-deposited thereon. When I did
An oxygen-enriched region is formed in the vicinity of the surface layer of the deposited l-TiCN layer, and the crystal grains in the oxygen-enriched region of the deposited l-TiCN layer have a refined structure, and on this, It has been found that the crystal grains of the deposited Al 2 O 3 layer are also refined.
（ｂ）また、本発明者らは、上記の酸素濃化領域が形成されているｌ−ＴｉＣＮ層について、その縦断面研磨面に沿ってオージェ電子分光法により、その層厚方向に酸素含有量を線分析したところ、Ａｌ２Ｏ３層（上部層）とｌ−ＴｉＣＮ層（下部層）の界面から、ｌ−ＴｉＣＮ層の内部側に酸素濃化領域が形成されると同時に、図２に示すようにｌ−ＴｉＣＮ層の結晶組織が微細化されており、さらに、該ｌ−ＴｉＣＮ層の内部側の深さ０．５〜２．０μｍの範囲内において、酸素含有量のピークが現れ、また、該ピーク位置における酸素含有量ＯＭＡＸを測定したところ、ＯＭＡＸ＝３〜８原子％であるｌ−ＴｉＣＮ層（以下、「改質ｌ−ＴｉＣＮ層」という）が形成されることを見出した。 (B) In addition, the inventors of the l-TiCN layer in which the oxygen-enriched region is formed have an oxygen content in the layer thickness direction by Auger electron spectroscopy along the vertical cross-section polished surface. As a result of a line analysis, an oxygen-concentrated region is formed on the inner side of the l-TiCN layer from the interface between the Al 2 O 3 layer (upper layer) and the l-TiCN layer (lower layer). As shown in the figure, the crystal structure of the l-TiCN layer is refined, and the peak of the oxygen content appears within a depth of 0.5 to 2.0 μm on the inner side of the l-TiCN layer. Further, when the oxygen content O MAX at the peak position was measured, it was found that an l-TiCN layer (hereinafter referred to as “modified l-TiCN layer”) having O MAX = 3 to 8 atomic% was formed. It was.
（ｃ）また、本発明者らは、上記改質ｌ−ＴｉＣＮ層の上に蒸着形成されるＡｌ２Ｏ３層について、電界放出型走査電子顕微鏡を用い、その縦断面研磨面の測定範囲内に存在する結晶粒個々に電子線を照射して、上記縦断面研磨面の法線に対して、上記結晶粒の結晶面である（０００１）面の法線がなす傾斜角を測定し、この測定傾斜角から、それぞれ隣接する結晶粒相互間の界面における（０００１）面の法線同士の交わる角度を求め、前記（０００１）面の法線同士の交わる角度が２度以上の界面を粒界であるとして、上記縦断面研磨面の測定範囲内における粒界の全長ＧＢＬ（μｍ）を求め、さらに、測定した粒界の全長ＧＢＬ（μｍ）と、測定した縦断面研磨面の面積ＧＡ（μｍ２）との比の値を求めたところ、
ＧＢＬ／ＧＡ＝１２〜２８
の関係を満足する微細結晶粒からなるＡｌ２Ｏ３層が形成されていることを見出した。
(C) Further, the present inventors have for the Al 2 O 3 layer is deposited formed on the reforming l-TiCN layer, using a field emission scanning electron microscope, within the measuring range of the longitudinal section polished surface An electron beam is irradiated to each of the crystal grains existing in the surface, and the inclination angle formed by the normal line of the (0001) plane that is the crystal plane of the crystal grain is measured with respect to the normal line of the vertical cross-section polished surface. The angle at which the normals of the (0001) plane intersect at the interface between adjacent crystal grains is determined from the measured tilt angle, and the interface at which the angle between the normals of the (0001) plane intersects is 2 ° or more. As a result, the total length GB L (μm) of the grain boundary within the measurement range of the above-mentioned vertical cross-section polished surface is obtained, and the measured total length GB L (μm) of the grain boundary and the measured area G of the vertical cross-section polished surface When the value of the ratio with A (μm 2 ) was obtained,
GB L / G A = 12 to 28
It was found that an Al 2 O 3 layer made of fine crystal grains satisfying the above relationship was formed.
（ｄ）そして、少なくとも、上記酸素濃化領域を備えかつ微細化された組織を有する改質ｌ−ＴｉＣＮ層（下部層）の上に、上記微細結晶粒からなるＡｌ２Ｏ３層（上部層）を蒸着形成した硬質被覆層を備えた本発明の被覆工具は、下部層と上部層の密着性が向上すると同時に、上部層のＡｌ２Ｏ３の結晶粒粗大化が抑制されることから、高熱発生を伴い、かつ、切刃部に断続的・衝撃的負荷がかかる高速断続切削に用いた場合でも、すぐれた耐チッピング性を発揮し、長期の使用に亘ってすぐれた耐摩耗性を発揮するのである。 (D) At least the Al 2 O 3 layer (upper layer) made of the fine crystal grains on the modified l-TiCN layer (lower layer) having the oxygen-concentrated region and having a refined structure. The coating tool of the present invention having a hard coating layer formed by vapor deposition)) improves the adhesion between the lower layer and the upper layer, and at the same time suppresses the coarsening of Al 2 O 3 crystal grains in the upper layer. Exhibits excellent chipping resistance and excellent wear resistance over a long period of use, even when used for high-speed intermittent cutting that generates high heat and requires intermittent and impact loads on the cutting edge. To do.
この発明は、上記の知見に基づいてなされたものであって、
「 炭化タングステン基超硬合金または炭窒化チタン基サーメットで構成された工具基体の表面に、
（ａ）５〜２０μｍの合計平均層厚を有し、Ｔｉの炭化物層、窒化物層、炭窒化物層、炭酸化物層および炭窒酸化物層のうちの１層または２層以上のＴｉ化合物層からなり、かつ、上部層と接する下部層は３μｍ以上の平均層厚の縦長成長結晶組織をもつ改質Ｔｉ炭窒化物層からなる下部層、
（ｂ）１〜１５μｍの平均層厚を有する酸化アルミニウム層からなる上部層、
上記（ａ）、（ｂ）の硬質被覆層が化学蒸着により形成された表面被覆切削工具において、
（ｃ）上部層と接する上記縦長成長結晶組織をもつ改質Ｔｉ炭窒化物層は、その縦断面研磨面について、オージェ電子分光法により、その層厚方向に沿って酸素含有量を線分析した場合、上部層と下部層の界面から、上記縦長成長結晶組織をもつ改質Ｔｉ炭窒化物層の内部側の深さ０．５〜２．０μｍの範囲内において、酸素含有量のピークが現れ、該ピーク位置における酸素含有量ＯＭＡＸは、ＯＭＡＸ＝３〜８原子％である酸素濃化領域を備え、
（ｄ）酸化アルミニウム層からなる上記上部層は、電界放出型走査電子顕微鏡を用い、その縦断面研磨面の測定範囲内に存在する結晶粒個々に電子線を照射して、上記縦断面研磨面の法線に対して、上記結晶粒の結晶面である（０００１）面の法線がなす傾斜角を測定し、この測定傾斜角から、それぞれ隣接する結晶粒相互間の界面における（０００１）面の法線同士の交わる角度を求め、前記（０００１）面の法線同士の交わる角度が２度以上の界面を粒界であるとして、上記縦断面研磨面の測定範囲内における粒界の全長ＧＢＬ（μｍ）を求めた場合、測定した粒界の全長ＧＢＬ（μｍ）と、測定した縦断面研磨面の面積ＧＡ（μｍ２）との比の値が、ＧＢＬ／ＧＡ＝１２〜２８の関係を満足する微細結晶酸化アルミニウム層である、
ことを特徴とする表面被覆切削工具。」
に特徴を有するものである。
This invention has been made based on the above findings,
"On the surface of the tool base made of tungsten carbide base cemented carbide or titanium carbonitride base cermet,
(A) Ti compound having a total average layer thickness of 5 to 20 μm, and one or two or more layers of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer and carbonitride oxide layer A lower layer made of a modified Ti carbonitride layer having a vertically grown crystal structure with an average layer thickness of 3 μm or more, and the lower layer in contact with the upper layer,
(B) an upper layer comprising an aluminum oxide layer having an average layer thickness of 1 to 15 μm,
In the surface-coated cutting tool in which the hard coating layer (a) or (b) is formed by chemical vapor deposition,
(C) The modified Ti carbonitride layer having the above vertically grown crystal structure in contact with the upper layer was subjected to a line analysis of the oxygen content along the layer thickness direction by Auger electron spectroscopy on the polished surface of the longitudinal section. In this case, a peak of the oxygen content appears in the range of a depth of 0.5 to 2.0 μm on the inner side of the modified Ti carbonitride layer having the vertically elongated crystal structure from the interface between the upper layer and the lower layer. The oxygen content O MAX at the peak position comprises an oxygen concentration region where O MAX = 3 to 8 atomic%,
(D) The upper layer made of an aluminum oxide layer is irradiated with an electron beam on each crystal grain existing within the measurement range of the vertical cross section polished surface using a field emission scanning electron microscope, and the vertical cross section polished surface The tilt angle formed by the normal line of the (0001) plane, which is the crystal plane of the crystal grain, is measured with respect to the normal line, and the (0001) plane at the interface between the adjacent crystal grains is determined from the measured tilt angle. The angle at which the normal lines intersect each other is obtained, and assuming that the interface where the angle between the normal lines on the (0001) plane intersects is 2 degrees or more is the grain boundary, the total length GB of the grain boundary within the measurement range of the vertical cross-section polished surface When L (μm) is determined, the value of the ratio between the total length GB L (μm) of the measured grain boundary and the measured area G A (μm 2 ) of the longitudinal cross-section polished surface is GB L / G A = 12 A fine crystal aluminum oxide layer satisfying the relationship of ~ 28 ,
A surface-coated cutting tool characterized by that. "
It has the characteristics.
つぎに、この発明の被覆工具の硬質被覆層の構成層について、詳細に説明する。
（ａ）下部層（Ｔｉ化合物層）
ＴｉＣ層、ＴｉＮ層、ＴｉＣＮ層（ｌ−ＴｉＣＮ層も含む）、ＴｉＣＯ層、ＴｉＣＮＯ層と後記改質ＴｉＣＮ層からなるＴｉ化合物層は、自体が高温強度を有し、これの存在によって硬質被覆層が高温強度を具備するようになるほか、工具基体と上部層であるＡｌ２Ｏ３層のいずれにも強固に密着し、よって硬質被覆層の工具基体に対する密着性向上に寄与する作用をもつが、その合計平均層厚が５μｍ未満では、前記作用を十分に発揮させることができず、一方その合計平均層厚が２０μｍを越えると、特に高熱発生を伴う高速断続切削でチッピングを起し易くなることから、その合計平均層厚を５〜２０μｍと定めた。
Next, the constituent layers of the hard coating layer of the coated tool of the present invention will be described in detail.
(A) Lower layer (Ti compound layer)
Ti compound layer consisting of TiC layer, TiN layer, TiCN layer (including 1-TiCN layer), TiCO layer, TiCNO layer and modified TiCN layer described later has high-temperature strength itself, and due to its presence, hard coating layer In addition to having high-temperature strength, it firmly adheres to both the tool base and the upper Al 2 O 3 layer, thereby contributing to improved adhesion of the hard coating layer to the tool base. When the total average layer thickness is less than 5 μm, the above-mentioned effect cannot be sufficiently exerted. On the other hand, when the total average layer thickness exceeds 20 μm, chipping is likely to occur particularly in high-speed intermittent cutting with high heat generation. Therefore, the total average layer thickness was determined to be 5 to 20 μm.
（ｂ）下部層の改質ｌ−ＴｉＣＮ層
下部層は上記のとおりＴｉ化合物層で構成するが、上部層に隣接する下部層については、少なくとも、３μｍ以上の平均層厚の改質ｌ−ＴｉＣＮ層で構成することが必要である。
既述のとおり、改質ｌ−ＴｉＣＮ層は、ｌ−ＴｉＣＮ層を通常条件で蒸着する成膜工程の途中段階、例えば、所定目標層厚のｌ−ＴｉＣＮ層の成膜が完了する６０〜８０分前の時点で、反応雰囲気圧力を２．５〜３ｋＰａに低下させ、同時に、反応ガスに占める割合を０．５〜１．８容量％となるようにＣＯ２を５０〜７０秒間反応ガス中に添加して成膜を行い、その後は、通常条件にしたがって、所定目標層厚になるまでｌ−ＴｉＣＮ層を成膜することによって形成することができる。
図２に示すように、成膜された改質ｌ−ＴｉＣＮ層の表層近傍には酸素濃化領域が形成され、しかも、酸素濃化領域における改質ｌ−ＴｉＣＮ層の結晶粒は微細化組織となる。
改質ｌ−ＴｉＣＮ層の縦断面研磨面について、オージェ電子分光法により、その層厚方向に沿って酸素含有量を線分析すると、上部層（Ａｌ２Ｏ３層）と下部層（改質ｌ−ＴｉＣＮ層）の界面から、改質ｌ−ＴｉＣＮ層の内部側の深さ０．５〜２．０μｍの範囲内において、酸素含有量のピークが現れる酸素濃化領域が存在し、そして、該ピーク位置における酸素含有量ＯＭＡＸは、ＯＭＡＸ＝３〜８原子％である。
酸素含有量のピークが０．５μｍ未満の深さ位置にある場合には、新たなＴｉＣＮ結晶の核形成により成長した改質ｌ−ＴｉＣＮ層の強度が不十分であり、加工時における層内破壊による剥離を発生しやすくなり、一方、酸素含有量のピーク位置が、２．０μｍを超える内部側にある場合には、新たなＴｉＣＮ結晶の核形成により成長した改質ｌ−ＴｉＣＮ層の粒径が大きくなり過ぎ、この上に蒸着形成されたＡｌ２Ｏ３層の結晶粒が微細化されなくなる。
また、ピーク位置における酸素含有量ＯＭＡＸが３原子％未満の場合には、新たなＴｉＣＮ結晶の核形成が十分でないため、酸素濃化領域より上部層側の改質ｌ−ＴｉＣＮ層における結晶粒微細化効果が少なく、一方、ピーク位置における酸素含有量ＯＭＡＸが８原子％を超える場合には、結晶構造の異なるＴｉ２Ｏ３が形成され、剥離発生の原因になるので、ピーク位置における酸素含有量ＯＭＡＸは、ＯＭＡＸ＝３〜８原子％であることが必要である。
なお、この発明の改質ｌ−ＴｉＣＮ層について、その表層から、例えば２．５μｍ以上の深さの内部側での平均酸素含有量ＯＡＶを測定したところ、ＯＭＡＸの値とＯＡＶの値には、２ＯＡＶ≦ＯＭＡＸ≦５ＯＡＶの関係が成立することを確認した。
従来から、下部層を形成するＴｉ化合物層の一種としてＴｉＣＮＯ層がよく知られているが、ＴｉＣＮＯの蒸着条件の調整によっては、上記の如きＯＭＡＸ＝３〜８原子％かつ２ＯＡＶ≦ＯＭＡＸ≦５ＯＡＶの関係を満足するＴｉＣＮＯ層を形成することはできないから、この意味で、本発明でいう酸素濃化領域が存在する改質ｌ−ＴｉＣＮ層は、従来知られているＴｉＣＮＯ層とは明確に区別し得るものである。
さらに、この発明では、上部層（Ａｌ２Ｏ３層）に隣接する改質ｌ−ＴｉＣＮ層において、上記所定の深さ位置に酸素含有量のピークが存在する酸素濃化領域が形成されることによって、この酸素濃化領域における改質ｌ−ＴｉＣＮ層の結晶粒が微細化し、上部層のＡｌ２Ｏ３層との密着性が向上するとともに、形成されるＡｌ２Ｏ３層の結晶粒も微細化され、結晶粒の粗大化による耐チッピング性、耐摩耗性の低下を抑制することができる。
(B) Lower-layer modified l-TiCN layer The lower layer is composed of the Ti compound layer as described above, but the lower layer adjacent to the upper layer is at least an average layer thickness of 3 μm or more modified l-TiCN. It is necessary to compose in layers.
As described above, the modified l-TiCN layer is formed in the middle of the film forming process in which the l-TiCN layer is deposited under normal conditions, for example, the film formation of the l-TiCN layer having a predetermined target layer thickness is completed. The reaction atmosphere pressure was reduced to 2.5 to 3 kPa at a time before 5 minutes, and at the same time, CO 2 was kept in the reaction gas for 50 to 70 seconds so that the proportion of the reaction gas was 0.5 to 1.8% by volume. Then, the film can be formed by forming an l-TiCN layer according to normal conditions until a predetermined target layer thickness is reached.
As shown in FIG. 2, an oxygen-enriched region is formed in the vicinity of the surface layer of the formed modified l-TiCN layer, and the crystal grains of the modified l-TiCN layer in the oxygen-enriched region have a refined structure. It becomes.
When the oxygen content of the modified l-TiCN layer polished surface is analyzed by Auger electron spectroscopy along the layer thickness direction, the upper layer (Al 2 O 3 layer) and the lower layer (modified l) are analyzed. -TiCN layer), an oxygen concentration region where an oxygen content peak appears in a depth range of 0.5 to 2.0 μm on the inner side of the modified l-TiCN layer, and The oxygen content O MAX at the peak position is O MAX = 3 to 8 atomic%.
When the peak of oxygen content is at a depth of less than 0.5 μm, the strength of the modified l-TiCN layer grown by nucleation of a new TiCN crystal is insufficient, and in-layer breakdown during processing When the peak position of the oxygen content is on the inner side exceeding 2.0 μm, the grain size of the modified l-TiCN layer grown by nucleation of new TiCN crystals Becomes too large, and the crystal grains of the Al 2 O 3 layer deposited thereon are not refined.
Further, when the oxygen content O MAX at the peak position is less than 3 atomic%, the nucleation of new TiCN crystals is not sufficient, so that the crystal grains in the modified l-TiCN layer on the upper layer side from the oxygen concentration region On the other hand, when the oxygen content O MAX at the peak position exceeds 8 atomic%, Ti 2 O 3 having a different crystal structure is formed and causes peeling, so that the oxygen at the peak position is small. The content O MAX needs to be O MAX = 3 to 8 atomic%.
As for reforming l-TiCN layer of the present invention, from the surface layer, for example, the average oxygen content O AV at 2.5μm or more depth inside of was measured, the O MAX values and O AV value It was confirmed that the relationship of 2O AV ≦ O MAX ≦ 5O AV was established.
Conventionally, a TiCNO layer is well known as a kind of Ti compound layer that forms the lower layer. However, depending on the adjustment of the deposition conditions of TiCNO, O MAX = 3 to 8 atomic% and 2O AV ≦ O MAX as described above. Since it is not possible to form a TiCNO layer satisfying the relation of ≦ 5O AV , in this sense, the modified l-TiCN layer having an oxygen-enriched region as referred to in the present invention is a conventionally known TiCNO layer. It can be clearly distinguished.
Furthermore, in the present invention, in the modified l-TiCN layer adjacent to the upper layer (Al 2 O 3 layer), an oxygen-concentrated region where an oxygen content peak exists at the predetermined depth position is formed. As a result, the crystal grains of the modified l-TiCN layer in this oxygen-concentrated region become finer, the adhesion with the upper Al 2 O 3 layer is improved, and the crystal grains of the formed Al 2 O 3 layer are also It is refined and the fall of chipping resistance and wear resistance due to coarsening of crystal grains can be suppressed.
（ｃ）上部層（Ａｌ２Ｏ３層）
Ａｌ２Ｏ３層からなる上部層は、すぐれた高温硬さと耐熱性を有し、硬質被覆層の耐摩耗性向上に寄与するが、この発明では、上記改質ｌ−ＴｉＣＮ層の酸素濃化領域における微細結晶粒に隣接してＡｌ２Ｏ３層を形成することから、形成されたＡｌ２Ｏ３層における結晶粒も微細なものとなり、耐摩耗性が一段と向上する。
結晶粒の微細化の程度を定量化すべく、改質ｌ−ＴｉＣＮ層上に形成されたＡｌ２Ｏ３層について、電界放出型走査電子顕微鏡を用い、その縦断面研磨面の測定範囲内に存在する結晶粒個々に電子線を照射して、上記縦断面研磨面の法線に対して、上記結晶粒の結晶面である（０００１）面の法線がなす傾斜角を測定し、この測定傾斜角から、それぞれ隣接する結晶粒相互間の界面における（０００１）面の法線同士の交わる角度を求め、前記（０００１）面の法線同士の交わる角度が２度以上の界面を粒界であるとして、上記縦断面研磨面の測定範囲内における粒界の全長ＧＢＬ（μｍ）を求め、また、測定した粒界の全長ＧＢＬ（μｍ）と、測定した縦断面研磨面の面積ＧＡ（μｍ２）との比の値を求めたところ、ＧＢＬ／ＧＡ＝１２〜２８の関係を満足することがわかった。
参考のため、通常条件でｌ−ＴｉＣＮ層を蒸着形成し、さらにこの上に、通常条件でＡｌ２Ｏ３層を蒸着形成した場合についても上記ＧＢＬ／ＧＡの値を求めたところ、ＧＢＬ／ＧＡ＝３〜１０であった。
したがって、この発明におけるＡｌ２Ｏ３層は、従来のＡｌ２Ｏ３層に比して、単位面積当たりの結晶粒界長さが長いことから、結晶粒が微細化していることが明らかである。
なお、Ａｌ２Ｏ３層からなる上部層の平均層厚が１μｍ未満では、硬質被覆層に十分な耐摩耗性を発揮せしめることができず、一方その平均層厚が１５μｍを越えて厚くなりすぎると、チッピングが発生し易くなることから、その平均層厚を１〜１５μｍと定めた。
(C) Upper layer (Al 2 O 3 layer)
The upper layer composed of the Al 2 O 3 layer has excellent high-temperature hardness and heat resistance and contributes to the improvement of the wear resistance of the hard coating layer. In the present invention, the oxygen concentration of the modified l-TiCN layer is achieved. Since the Al 2 O 3 layer is formed adjacent to the fine crystal grains in the region, the crystal grains in the formed Al 2 O 3 layer also become fine, and wear resistance is further improved.
In order to quantify the degree of crystal grain refinement, Al 2 O 3 layer formed on the modified l-TiCN layer is present within the measurement range of its vertical cross-section polished surface using a field emission scanning electron microscope Each crystal grain to be irradiated is irradiated with an electron beam, and the inclination angle formed by the normal line of the (0001) plane, which is the crystal plane of the crystal grain, is measured with respect to the normal line of the vertical section polished surface. From the corner, the angle at which the normal lines of the (0001) plane intersect each other at the interface between adjacent crystal grains is obtained, and the interface at which the angle between the normal lines of the (0001) plane intersects is a grain boundary. As above, the total length GB L (μm) of the grain boundary within the measurement range of the vertical cross-section polished surface is obtained, and the total length GB L (μm) of the measured grain boundary and the measured area GA of the vertical cross-sectional polished surface G A ( was determined values of the ratio of the μm 2), GB L / G a It has been found to satisfy the relationship of 12 to 28.
For reference, when the l-TiCN layer was vapor deposited under normal conditions, on further this was calculated the value of the GB L / G A also when deposited form the Al 2 O 3 layer in the normal condition, GB It was L / G a = 3~10.
Therefore, it is clear that the Al 2 O 3 layer in the present invention has finer crystal grains because the grain boundary length per unit area is longer than that of the conventional Al 2 O 3 layer. .
If the average layer thickness of the upper layer composed of the Al 2 O 3 layer is less than 1 μm, the hard coating layer cannot exhibit sufficient wear resistance, while the average layer thickness exceeds 15 μm and becomes too thick. Then, since chipping is likely to occur, the average layer thickness is determined to be 1 to 15 μm.
この発明の被覆工具は、酸素濃化領域を備えかつ微細化された組織を有する改質ｌ−ＴｉＣＮ層（下部層）の上に、微細結晶粒からなるＡｌ２Ｏ３層（上部層）を蒸着形成されていることにより、下部層と上部層の密着性が向上すると同時に、上部層のＡｌ２Ｏ３の結晶粒粗大化が抑制されることから、高熱発生を伴い、かつ、切刃部に断続的・衝撃的負荷がかかる高速断続切削に用いた場合でも、すぐれた耐チッピング性を発揮し、長期の使用に亘ってすぐれた耐摩耗性を発揮するのである。 In the coated tool of the present invention, an Al 2 O 3 layer (upper layer) made of fine crystal grains is formed on a modified l-TiCN layer (lower layer) having an oxygen-concentrated region and having a refined structure. By being formed by vapor deposition, adhesion between the lower layer and the upper layer is improved, and at the same time, coarsening of crystal grains of Al 2 O 3 in the upper layer is suppressed. Even when used for high-speed intermittent cutting that requires intermittent and impact loads, it exhibits excellent chipping resistance and excellent wear resistance over a long period of use.
つぎに、この発明の被覆工具を実施例により具体的に説明する。 Next, the coated tool of the present invention will be specifically described with reference to examples.
原料粉末として、いずれも１〜３μｍの平均粒径を有するＷＣ粉末、ＴｉＣ粉末、ＺｒＣ粉末、ＶＣ粉末、ＴａＣ粉末、ＮｂＣ粉末、Ｃｒ3Ｃ2粉末、ＴｉＮ粉末、ＴａＮ粉末、およびＣｏ粉末を用意し、これら原料粉末を、表１に示される配合組成に配合し、さらにワックスを加えてアセトン中で２４時間ボールミル混合し、減圧乾燥した後、９８ＭＰａの圧力で所定形状の圧粉体にプレス成形し、この圧粉体を５Ｐａの真空中、１３７０〜１４７０℃の範囲内の所定の温度に１時間保持の条件で真空焼結し、焼結後、切刃部にＲ：０．０７ｍｍのホーニング加工を施すことによりＩＳＯ・ＣＮＭＧ１２０４０８に規定するインサート形状をもったＷＣ基超硬合金製の工具基体Ａ〜Ｆをそれぞれ製造した。 WC powder, TiC powder, ZrC powder, VC powder, TaC powder, NbC powder, Cr 3 C 2 powder, TiN powder, TaN powder, and Co powder all having an average particle diameter of 1 to 3 μm are prepared as raw material powders. These raw material powders were blended into the composition shown in Table 1, added with wax, ball milled in acetone for 24 hours, dried under reduced pressure, and pressed into a green compact with a predetermined shape at a pressure of 98 MPa. The green compact was vacuum sintered at a predetermined temperature in the range of 1370 to 1470 ° C. for 1 hour in a vacuum of 5 Pa. After sintering, the cutting edge portion was R: 0.07 mm honing By performing the processing, tool bases A to F made of WC-based cemented carbide having an insert shape specified in ISO · CNMG120408 were manufactured.
また、原料粉末として、いずれも０．５〜２μｍの平均粒径を有するＴｉＣＮ（質量比でＴｉＣ／ＴｉＮ＝５０／５０）粉末、Ｍｏ2Ｃ粉末、ＺｒＣ粉末、ＮｂＣ粉末、ＴａＣ粉末、ＷＣ粉末、Ｃｏ粉末、およびＮｉ粉末を用意し、これら原料粉末を、表２に示される配合組成に配合し、ボールミルで２４時間湿式混合し、乾燥した後、９８ＭＰａの圧力で圧粉体にプレス成形し、この圧粉体を１．３ｋＰａの窒素雰囲気中、温度：１５４０℃に１時間保持の条件で焼結し、焼結後、切刃部分にＲ：０．０７ｍｍのホーニング加工を施すことによりＩＳＯ規格・ＣＮＭＧ１２０４１２のインサート形状をもったＴｉＣＮ基サーメット製の工具基体ａ〜ｆを形成した。 In addition, as raw material powders, TiCN (mass ratio TiC / TiN = 50/50) powder, Mo 2 C powder, ZrC powder, NbC powder, TaC powder, WC powder, all having an average particle diameter of 0.5 to 2 μm. Co powder and Ni powder are prepared, and these raw material powders are blended in the blending composition shown in Table 2, wet mixed by a ball mill for 24 hours, dried, and pressed into a compact at a pressure of 98 MPa. The green compact was sintered in a nitrogen atmosphere of 1.3 kPa at a temperature of 1540 ° C. for 1 hour, and after the sintering, the cutting edge portion was subjected to a honing process of R: 0.07 mm. Tool bases a to f made of TiCN-based cermet having an insert shape of standard / CNMG12041 were formed.
つぎに、これらの工具基体Ａ〜Ｆおよび工具基体ａ〜ｆの表面に、通常の化学蒸着装置を用い、硬質被覆層の下部層として、表３に示される条件で、Ｔｉ化合物層（但し、改質ｌ−ＴｉＣＮ層を除く）を蒸着形成し、
ついで、改質ｌ−ＴｉＣＮ層を、表４に示される条件で、表５に示される組み合わせ、かつ同じく表５に示される目標層厚で蒸着形成し、その後、表３に示される条件にて、上部層としてのＡｌ２Ｏ３層を同じく表５に示される組み合わせ、かつ目標層厚で蒸着形成することにより本発明被覆工具１〜１３をそれぞれ製造した。
Next, on the surface of these tool bases A to F and tool bases a to f, using a normal chemical vapor deposition apparatus, as a lower layer of the hard coating layer, under the conditions shown in Table 3, a Ti compound layer (however, Vapor deposition of the modified l-TiCN layer)
Subsequently, the modified l-TiCN layer was formed by vapor deposition with the combination shown in Table 5 and the target layer thickness shown in Table 5 under the conditions shown in Table 4, and then under the conditions shown in Table 3. The inventive coated tools 1 to 13 were produced by vapor-depositing Al 2 O 3 layers as upper layers in the same combination as shown in Table 5 and with a target layer thickness.
また、比較の目的で、硬質被覆層の下部層として、表３に示される条件で、表６に示される組み合わせ、かつ同じく表６に示される目標層厚でＴｉ化合物層を蒸着形成し（但し、上部層と隣接する下部層は、通常のｌ−ＴｉＣＮ層を蒸着形成）、
その後、表３に示される条件にて、上部層としてのＡｌ２Ｏ３層を、表６に示される組み合わせ、かつ同じく表６に示される目標層厚で蒸着形成することにより従来被覆工具１〜１３をそれぞれ製造した。
For comparison purposes, as a lower layer of the hard coating layer, a Ti compound layer is formed by vapor deposition under the conditions shown in Table 3 and with the combinations shown in Table 6 and also with the target layer thicknesses shown in Table 6 (however, The lower layer adjacent to the upper layer is formed by depositing a normal l-TiCN layer).
Thereafter, under the conditions shown in Table 3, the Al 2 O 3 layer as the upper layer is formed by vapor deposition with the combination shown in Table 6 and the target layer thickness also shown in Table 6. 13 were produced respectively.
ついで、上記の本発明被覆工具の改質ｌ−ＴｉＣＮ層について、縦断面研磨面について、オージェ電子分光法により、その層厚方向に沿って酸素含有量を線分析し、酸素含有量のピークが現れるピーク位置を求めるとともに、該ピーク位置における酸素含有量ＯＭＡＸの値を求めた。
また、参考のため、改質ｌ−ＴｉＣＮ層の酸素濃化領域より内部側の深さ位置における酸素含有量についても測定し、その平均酸素含有量ＯＡＶ（但し、５点測定の平均値）を求めた。
表５に、上記酸素含有量ＯＭＡＸ、平均酸素含有量ＯＡＶの値を示す。
同様に従来被覆工具のｌ−ＴｉＣＮ層についても酸素含有量を測定し、その平均酸素含有量ＯＡＶ（但し、５点測定の平均値）を求めた。
表６に、平均酸素含有量ＯＡＶの値を示す。
Next, for the modified l-TiCN layer of the above-mentioned coated tool of the present invention, the oxygen content was linearly analyzed along the layer thickness direction by Auger electron spectroscopy on the longitudinal cross-section polished surface, and the peak of the oxygen content was The peak position that appeared was determined, and the value of the oxygen content O MAX at the peak position was determined.
For reference, the oxygen content at a depth position inside the oxygen enrichment region of the modified l-TiCN layer is also measured, and the average oxygen content O AV (however, the average value of five-point measurement) Asked.
Table 5 shows values of the oxygen content O MAX and the average oxygen content O AV .
Similarly, the oxygen content of the l-TiCN layer of the conventional coated tool was also measured, and the average oxygen content O AV (however, the average value of five-point measurement) was obtained.
Table 6 shows the values of the average oxygen content O AV.
さらに、本発明被覆工具の改質ｌ−ＴｉＣＮ層について、電界放出型走査電子顕微鏡及び電子後方散乱回折像装置を用いて、酸素濃化領域における改質ｌ−ＴｉＣＮ結晶粒の単位面積当たりの粒界長さを求め、また、酸素濃化領域より内部側にある結晶粒の単位面積当たりの粒界長さを求め、結晶微細化率ＲＴｉＣＮ（但し、Ｒ＝（酸素濃化領域における改質ｌ−ＴｉＣＮ結晶粒の単位面積当たりの粒界長さ）／（酸素濃化領域より内部側にある改質ｌ−ＴｉＣＮ結晶粒の単位面積当たりの粒界長さ）を算出した。
ここで、改質ｌ−ＴｉＣＮ結晶粒の単位面積当たりの粒界長さは、以下のようにして測定算出することができる。
すなわち、上記の改質ｌ−ＴｉＣＮ層の縦断面を研磨面とした状態で、電界放出型走査電子顕微鏡の鏡筒内にセットし、前記研磨面に７０度の入射角度で１５ｋＶの加速電圧の電子線を１ｎＡの照射電流で、前記縦断面研磨面の測定範囲内に存在する結晶粒個々に照射して、電子後方散乱回折像装置を用い、所定測定領域を０．１μｍ／ｓｔｅｐの間隔で、前記縦断面研磨面の法線に対して、前記結晶粒の結晶面である（００１）面および（０１１）面の法線がなす傾斜角を測定し、この結果得られた測定傾斜角に基づいて、それぞれ隣接する結晶粒相互間の界面における（００１）面の法線同士、および（０１１）面の法線同士の交わる角度を求め、さらに、前記（００１）面の法線同士、および（０１１）面の法線同士の交わる角度が２度以上の場合を粒界であるとして設定した上で、電界放出型走査電子顕微鏡により、改質ｌ−ＴｉＣＮ層の酸素濃化領域における縦断面測定領域を走査し、該測定領域内で粒界として識別される部分の長さＧＢＬＯ（μｍ）を求め、そして、測定した縦断面研磨面の面積ＧＡＯ（μｍ２）との比の値ＧＢＬＯ／ＧＡＯを求めた。
また、同様に、改質ｌ−ＴｉＣＮ層の酸素濃化領域より内部側における縦断面測定領域を走査し、該測定領域内で粒界として識別される部分の長さＧＢＬＩ（μｍ）を求め、そして、測定した縦断面研磨面の面積ＧＡＩ（μｍ２）との比の値ＧＢＬＩ／ＧＡＩを求めた。
ついで、上記ＧＢＬＯ／ＧＡＯ（酸素濃化領域における単位面積当たりの粒界長さに相当）と、上記ＧＢＬＩ／ＧＡＩ（酸素濃化領域より内部側における単位面積当たりの粒界長さに相当）との比の値を求め、これを、改質ｌ−ＴｉＣＮ層の結晶微細化率ＲＴｉＣＮであると定義した。
即ち、結晶微細化率ＲＴｉＣＮ
＝（酸素濃化領域における改質ｌ−ＴｉＣＮ結晶粒の単位面積当たりの粒界長さ）／（酸素濃化領域より内部側にある改質ｌ−ＴｉＣＮ結晶粒の単位面積当たりの粒界長さ）
＝（ＧＢＬＯ／ＧＡＯ）／（ＧＢＬＩ／ＧＡＩ）
である。
表５に、本発明被覆工具の改質ｌ−ＴｉＣＮ層についての結晶微細化率ＲＴｉＣＮの値を示す。
Further, for the modified l-TiCN layer of the coated tool of the present invention, grains per unit area of the modified l-TiCN crystal grains in the oxygen concentration region using a field emission scanning electron microscope and an electron backscatter diffraction image apparatus. The boundary length is obtained, and the grain boundary length per unit area of the crystal grains on the inner side from the oxygen concentration region is obtained, and the crystal refinement ratio R TiCN (where R = (modification in the oxygen concentration region) The grain boundary length per unit area of l-TiCN crystal grains) / (the grain boundary length per unit area of modified l-TiCN crystal grains on the inner side from the oxygen-enriched region) was calculated.
Here, the grain boundary length per unit area of the modified l-TiCN crystal grains can be measured and calculated as follows.
That is, the modified l-TiCN layer is set in a lens barrel of a field emission scanning electron microscope in a state where the longitudinal section of the modified l-TiCN layer is a polished surface, and an acceleration voltage of 15 kV is applied to the polished surface at an incident angle of 70 degrees. An electron beam is irradiated at an irradiation current of 1 nA to each crystal grain existing within the measurement range of the vertical cross-section polished surface, and an electron backscatter diffraction image apparatus is used to set a predetermined measurement region at an interval of 0.1 μm / step. The inclination angle formed by the normal lines of the (001) plane and the (011) plane, which are the crystal planes of the crystal grains, is measured with respect to the normal line of the vertical cross-section polished surface. Based on the angle between the normal lines of the (001) plane and the normal lines of the (011) plane at the interface between adjacent crystal grains, and the normal lines of the (001) plane, and The angle at which the normals of the (011) plane intersect is 2 After setting the above case as a grain boundary, a field emission scanning electron microscope is used to scan the longitudinal cross-sectional measurement region in the oxygen-enriched region of the modified l-TiCN layer, and as a grain boundary in the measurement region The length GB LO (μm) of the part to be identified was obtained, and the value GB LO / G AO of the ratio to the measured area G AO (μm 2 ) of the polished surface of the longitudinal section was obtained.
Similarly, the longitudinal cross section measurement region on the inner side of the oxygen concentration region of the modified l-TiCN layer is scanned to obtain the length GB LI (μm) of the portion identified as the grain boundary in the measurement region. and it was determined values GB LI / G AI ratio between the area G AI of the measured longitudinal sectional polished surface (μm 2).
Next, GB LO / G AO (corresponding to the grain boundary length per unit area in the oxygen concentrated region) and GB LI / G AI (grain boundary length per unit area on the inner side from the oxygen concentrated region) And defined as the crystal refinement rate R TiCN of the modified l-TiCN layer.
That is, the crystal refinement ratio R TiCN
= (Grain boundary length per unit area of modified l-TiCN crystal grains in oxygen-enriched region) / (grain boundary length per unit area of modified l-TiCN crystal grains located on the inner side of the oxygen-enriched region) Sa)
= (GB LO / G AO ) / (GB LI / G AI )
It is.
Table 5 shows the value of the crystal refinement ratio R TiCN for the modified l-TiCN layer of the coated tool of the present invention.
また、上記の本発明被覆工具と従来被覆工具の硬質被覆層の上部層を構成するＡｌ２Ｏ３層についても、上記改質ｌ−ＴｉＣＮ層の場合と同様にして、縦断面研磨面測定範囲内における粒界の全長ＧＢＬ（μｍ）を求め、測定した縦断面研磨面の面積ＧＡ（μｍ２）との値から、単位面積当たりの粒界長さＧＢＬ／ＧＡを算出した。
表５、表６に、本発明被覆工具と従来被覆工具のＡｌ２Ｏ３層についての、単位面積当たりの粒界長さＧＢＬ／ＧＡを示す。
Further, the Al 2 O 3 layer constituting the upper layer of the hard coating layer of the present invention-coated tool and the conventional coated tool is also measured in the longitudinal cross-section polished surface measurement range in the same manner as in the case of the modified l-TiCN layer. grain boundaries determine the total length GB L (μm) of the inner, from the value of the area G a of the measured longitudinal sectional polished surface ([mu] m 2), was calculated grain boundary length GB L / G a per unit area.
Table 5, Table 6 shows, for the Al 2 O 3 layer of the present invention coated tools and conventional coated tool, the grain boundary length GB L / G A per unit area.
表５、６にそれぞれ示される通り、本発明被覆工具の改質ｌ−ＴｉＣＮ層は、結晶微細化率ＲＴｉＣＮがいずれも５．８より大きく、酸素濃化領域においては結晶粒が微細化していることが分かる。
また、本発明被覆工具のＡｌ２Ｏ３層の単位面積当たりの粒界長さＧＢＬ／ＧＡは、従来被覆工具のＡｌ２Ｏ３層の単位面積当たりの粒界長さＧＢＬ／ＧＡより大であって、従来被覆工具のＡｌ２Ｏ３層に比して、本発明被覆工具のＡｌ２Ｏ３層が微細化していることが分かる。
As shown in Tables 5 and 6, respectively, the modified l-TiCN layer of the coated tool of the present invention has a crystal refinement ratio R TiCN larger than 5.8, and crystal grains are refined in the oxygen concentration region. I understand that.
Further, the grain boundary length GB L / G A per unit area of the Al 2 O 3 layer of the present invention coated tool, the grain boundary length GB L / G per unit area of the Al 2 O 3 layer of conventional coated tool It is larger than A , and it can be seen that the Al 2 O 3 layer of the present coated tool is made finer than the Al 2 O 3 layer of the conventional coated tool.
なお、本発明被覆工具および従来被覆工具の下部層、上部層の厚さを、走査型電子顕微鏡を用いて測定（同じく縦断面測定）したところ、いずれも目標層厚と実質的に同じ平均層厚（５点測定の平均値）を示した。 In addition, when the thickness of the lower layer and the upper layer of the coated tool of the present invention and the conventional coated tool was measured using a scanning electron microscope (same longitudinal section measurement), the average layer was substantially the same as the target layer thickness. The thickness (average value of 5-point measurement) was shown.
つぎに、上記の各種の被覆工具をいずれも工具鋼製バイトの先端部に固定治具にてネジ止めした状態で、本発明被覆工具１〜１３および従来被覆工具１〜１３について、
被削材：ＪＩＳ・Ｓ４５Ｃの長さ方向等間隔４本縦溝入り丸棒、
切削速度：３００ｍ／ｍｉｎ、
切り込み：１．８ｍｍ、
送り：０．３５ｍｍ／ｒｅｖ、
切削時間：１８分、
の条件（切削条件Ａ）での炭素鋼の乾式高速断続切削試験
（通常の切削速度は、２５０ｍ／ｍｉｎ）、
被削材：ＪＩＳ・ＳＮＣＭ４３９の長さ方向等間隔４本縦溝入り丸棒、
切削速度：３２０ｍ／ｍｉｎ、
切り込み：２．０ｍｍ、
送り：０．３ｍｍ／ｒｅｖ、
切削時間：１３分、
の条件（切削条件Ｂ）での合金鋼の乾式高速断続切削試験
（通常の切削速度は、２５０ｍ／ｍｉｎ）、
被削材：ＪＩＳ・ＦＣ３００の長さ方向等間隔４本縦溝入り丸棒、
切削速度：４００ｍ／ｍｉｎ、
切り込み：１．５ｍｍ、
送り：０．３ｍｍ／ｒｅｖ、
切削時間：２０分、
の条件（切削条件Ｃ）での鋳鉄の乾式高速断続切削試験
（通常の切削速度は、３００ｍ／ｍｉｎ）、
を行い、いずれの切削試験でも切刃の逃げ面摩耗幅を測定した。
この測定結果を表７に示した。
Next, in the state where all of the above various coated tools are screwed to the tip of the tool steel tool with a fixing jig, the present coated tools 1 to 13 and the conventional coated tools 1 to 13,
Work material: JIS · S45C lengthwise equal 4 round grooved round bars,
Cutting speed: 300 m / min,
Cutting depth: 1.8mm,
Feed: 0.35mm / rev,
Cutting time: 18 minutes
Dry high-speed intermittent cutting test of carbon steel under the conditions (cutting condition A) (normal cutting speed is 250 m / min),
Work material: JIS / SNCM439 round direction bar with 4 equal intervals in the length direction,
Cutting speed: 320 m / min,
Cutting depth: 2.0 mm
Feed: 0.3mm / rev,
Cutting time: 13 minutes
Dry high-speed intermittent cutting test (normal cutting speed is 250 m / min) of alloy steel under the above conditions (cutting condition B),
Work material: JIS / FC300 lengthwise equidistant 4 bars with vertical grooves,
Cutting speed: 400 m / min,
Incision: 1.5mm,
Feed: 0.3mm / rev,
Cutting time: 20 minutes,
A dry high-speed intermittent cutting test of cast iron under the above conditions (cutting condition C) (normal cutting speed is 300 m / min),
In each cutting test, the flank wear width of the cutting edge was measured.
The measurement results are shown in Table 7.
表５〜７に示される結果から、本発明被覆工具１〜１３は、酸素濃化領域を備えかつ微細化された組織を有する改質ｌ−ＴｉＣＮ層（下部層）の上に、微細結晶粒からなるＡｌ２Ｏ３層（上部層）が形成されていることにより、下部層と上部層の密着性が向上すると同時に、上部層のＡｌ２Ｏ３の結晶粒粗大化が抑制されることから、高熱発生を伴い、かつ、切刃部に断続的・衝撃的負荷がかかる高速断続切削に用いた場合でも、すぐれた耐チッピング性を発揮し、長期の使用に亘ってすぐれた耐摩耗性を示す。
これに対して、硬質被覆層の下部層として、酸素濃化領域を備えかつ微細化された組織を有する改質ｌ−ＴｉＣＮ層が形成されていない従来被覆工具１〜１３においては、下部層と上部層において結晶粒の粗大化が生じやすく、そのため、下部層と上部層の密着性、耐摩耗性が十分でないため、高熱発生を伴い、かつ、切刃部に断続的・衝撃的負荷がかかる高速断続切削では、チッピング、欠損、剥離等が発生し、比較的短時間で使用寿命に至ることが明らかである。
From the results shown in Tables 5 to 7, the coated tools 1 to 13 of the present invention have fine crystal grains on the modified l-TiCN layer (lower layer) having an oxygen-concentrated region and having a refined structure. By forming the Al 2 O 3 layer (upper layer) made of the material, adhesion between the lower layer and the upper layer is improved, and at the same time, coarsening of Al 2 O 3 crystal grains in the upper layer is suppressed. Even when used for high-speed intermittent cutting with high heat generation and intermittent / impact loads on the cutting edge, it exhibits excellent chipping resistance and excellent wear resistance over a long period of use. Show.
In contrast, in the conventional coated tools 1 to 13 in which the modified l-TiCN layer having an oxygen-concentrated region and having a refined structure is not formed as the lower layer of the hard coating layer, Grain coarsening is likely to occur in the upper layer, and therefore the adhesion and wear resistance between the lower layer and the upper layer are not sufficient, resulting in high heat generation and intermittent and impact loads on the cutting edge. In high-speed intermittent cutting, it is clear that chipping, chipping, peeling, etc. occur and the service life is reached in a relatively short time.
上述のように、この発明の被覆工具は、各種鋼や鋳鉄などの高速断続切削ですぐれた耐チッピング性、耐摩耗性を示し、長期に亘ってすぐれた切削性能を発揮するものであるから、切削装置の高性能化並びに切削加工の省力化および省エネ化、さらに低コスト化に十分満足に対応できるものである。 As described above, the coated tool of the present invention exhibits excellent chipping resistance and wear resistance in high-speed intermittent cutting such as various steels and cast irons, and exhibits excellent cutting performance over a long period of time. It can cope with high performance of cutting equipment, labor saving and energy saving of cutting, and cost reduction.
Claims (1)
（ａ）５〜２０μｍの合計平均層厚を有し、Ｔｉの炭化物層、窒化物層、炭窒化物層、炭酸化物層および炭窒酸化物層のうちの１層または２層以上のＴｉ化合物層からなり、かつ、上部層と接する下部層は３μｍ以上の平均層厚の縦長成長結晶組織をもつ改質Ｔｉ炭窒化物層からなる下部層、
（ｂ）１〜１５μｍの平均層厚を有する酸化アルミニウム層からなる上部層、
上記（ａ）、（ｂ）の硬質被覆層が化学蒸着により形成された表面被覆切削工具において、
（ｃ）上部層と接する上記縦長成長結晶組織をもつ改質Ｔｉ炭窒化物層は、その縦断面研磨面について、オージェ電子分光法により、その層厚方向に沿って酸素含有量を線分析した場合、上部層と下部層の界面から、上記縦長成長結晶組織をもつ改質Ｔｉ炭窒化物層の内部側の深さ０．５〜２．０μｍの範囲内において、酸素含有量のピークが現れ、該ピーク位置における酸素含有量ＯＭＡＸは、ＯＭＡＸ＝３〜８原子％である酸素濃化領域を備え、
（ｄ）酸化アルミニウム層からなる上記上部層は、電界放出型走査電子顕微鏡を用い、その縦断面研磨面の測定範囲内に存在する結晶粒個々に電子線を照射して、上記縦断面研磨面の法線に対して、上記結晶粒の結晶面である（０００１）面の法線がなす傾斜角を測定し、この測定傾斜角から、それぞれ隣接する結晶粒相互間の界面における（０００１）面の法線同士の交わる角度を求め、前記（０００１）面の法線同士の交わる角度が２度以上の界面を粒界であるとして、上記縦断面研磨面の測定範囲内における粒界の全長ＧＢＬ（μｍ）を求めた場合、測定した粒界の全長ＧＢＬ（μｍ）と、測定した縦断面研磨面の面積ＧＡ（μｍ２）との比の値が、ＧＢＬ／ＧＡ＝１２〜２８の関係を満足する微細結晶酸化アルミニウム層である、
ことを特徴とする表面被覆切削工具。 On the surface of the tool base composed of tungsten carbide based cemented carbide or titanium carbonitride based cermet,
(A) Ti compound having a total average layer thickness of 5 to 20 μm, and one or two or more layers of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer and carbonitride oxide layer A lower layer made of a modified Ti carbonitride layer having a vertically grown crystal structure with an average layer thickness of 3 μm or more, and the lower layer in contact with the upper layer,
(B) an upper layer comprising an aluminum oxide layer having an average layer thickness of 1 to 15 μm,
In the surface-coated cutting tool in which the hard coating layer (a) or (b) is formed by chemical vapor deposition,
(C) The modified Ti carbonitride layer having the above vertically grown crystal structure in contact with the upper layer was subjected to a line analysis of the oxygen content along the layer thickness direction by Auger electron spectroscopy on the polished surface of the longitudinal section. In this case, a peak of the oxygen content appears in the range of a depth of 0.5 to 2.0 μm on the inner side of the modified Ti carbonitride layer having the vertically elongated crystal structure from the interface between the upper layer and the lower layer. The oxygen content O MAX at the peak position comprises an oxygen concentration region where O MAX = 3 to 8 atomic%,
(D) The upper layer made of an aluminum oxide layer is irradiated with an electron beam on each crystal grain existing within the measurement range of the vertical cross section polished surface using a field emission scanning electron microscope, and the vertical cross section polished surface The tilt angle formed by the normal line of the (0001) plane, which is the crystal plane of the crystal grain, is measured with respect to the normal line, and the (0001) plane at the interface between adjacent crystal grains is determined from the measured tilt angle. The angle at which the normal lines intersect each other is obtained, and assuming that the interface where the angle between the normal lines on the (0001) plane intersects is 2 degrees or more is the grain boundary, the total length GB of the grain boundary within the measurement range of the vertical cross-section polished surface When L (μm) is determined, the value of the ratio between the total length GB L (μm) of the measured grain boundary and the measured area G A (μm 2 ) of the longitudinal cross-section polished surface is GB L / G A = 12 A fine crystal aluminum oxide layer satisfying the relationship of ~ 28 ,
A surface-coated cutting tool characterized by that.
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