JP5176659B2 - Surface coated cutting tool whose hard coating layer exhibits excellent chipping resistance and wear resistance in high speed heavy cutting - Google Patents
Surface coated cutting tool whose hard coating layer exhibits excellent chipping resistance and wear resistance in high speed heavy cutting Download PDFInfo
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この発明は、各種の鋼や鋳鉄などの被削材の切削加工を、高熱発生を伴うと共に、切刃部に高負荷が作用する高送り、高切り込み等の高速重切削条件で行った場合にも、硬質被覆層がすぐれた耐チッピング性、耐摩耗性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。 This invention is used when cutting various work materials such as steel and cast iron under high-speed heavy cutting conditions such as high feed and high cutting with high heat generation and high load on the cutting edge. The present invention also relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) that exhibits excellent chipping resistance and wear resistance with a hard coating layer.
特許文献１に示されるように、従来、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）下部層は、炭化チタン層、窒化チタン層、炭窒化チタン層、酸化チタン層、炭酸化チタン層、窒酸化チタン層、炭窒酸化チタン層等のＴｉ化合物層、
（ｂ）上部層は、その下部層側を酸化アルミニウムで構成し、一方、その表面側は、酸化アルミニウム相の素地に酸化ジルコニウム相が分散分布した混合組織層、
上記（ａ）、（ｂ）からなる硬質被覆層を蒸着形成した表面被覆切削工具（以下、これを従来被覆工具という）が知られており、この従来被覆工具が、断続重切削加工においてすぐれた耐チッピング性を示すことが知られている。
As shown in Patent Document 1, conventionally, a substrate (hereinafter collectively referred to as tungsten carbide (hereinafter referred to as WC) based cemented carbide or titanium carbonitride (hereinafter referred to as TiCN) based cermet. On the surface of the tool base)
(A) The lower layer is a titanium compound layer such as a titanium carbide layer, a titanium nitride layer, a titanium carbonitride layer, a titanium oxide layer, a titanium carbonate layer, a titanium nitride oxide layer, a titanium carbonitride oxide layer,
(B) The upper layer is composed of aluminum oxide on the lower layer side, while the surface side is a mixed structure layer in which the zirconium oxide phase is dispersed and distributed on the base material of the aluminum oxide phase,
A surface-coated cutting tool (hereinafter referred to as a conventional coated tool) in which a hard coating layer comprising the above (a) and (b) is formed by vapor deposition is known, and this conventional coated tool is excellent in intermittent heavy cutting. It is known to exhibit chipping resistance.
また、特許文献２に示されるように、工具基体の表面に、
（ａ）下部層は、炭化チタン層、窒化チタン層、炭窒化チタン層、酸化チタン層、炭酸化チタン層、窒酸化チタン層、炭窒酸化チタン層等のＴｉ化合物層、
（ｂ）上部層は、α型の結晶構造を有するＡｌ−Ｚｒ複合酸化物層であって、しかも、該Ａｌ−Ｚｒ複合酸化物層について、電界放出型走査電子顕微鏡を用い、表面研磨面の測定範囲内に存在する六方晶結晶格子を有する結晶粒個々に電子線を照射して、前記表面研磨面の法線に対して、前記結晶粒の結晶面である（０００１）面および（１０-１０）面の法線がなす傾斜角を測定し、この場合前記結晶粒は、格子点にＡｌ、Ｚｒ、および酸素からなる構成原子がそれぞれ存在するコランダム型六方最密晶の結晶構造を有し、この結果得られた測定傾斜角に基づいて、相互に隣接する結晶粒の界面で、前記構成原子のそれぞれが前記結晶粒相互間で１つの構成原子を共有する格子点（構成原子共有格子点）の分布を算出し、前記構成原子共有格子点間に構成原子を共有しない格子点がＮ個（ただし、Ｎはコランダム型六方最密晶の結晶構造上２以上の偶数となるが、分布頻度の点からＮの上限を２８とした場合、４、８、１４、２４、および２６の偶数は存在せず）存在する構成原子共有格子点形態をΣＮ＋１で現した場合、個々のΣＮ＋１がΣＮ＋１全体に占める分布割合を示す構成原子共有格子点分布グラフにおいて、Σ３に最高ピークが存在し、かつ前記Σ３のΣＮ＋１全体に占める分布割合が６０〜８０％である構成原子共有格子点分布グラフを示すΣ３対応粒界の分布割合が高いＡｌ−Ｚｒ複合酸化物層、
上記（ａ）、（ｂ）からなる下部層、上部層を蒸着形成することにより、高速断続切削加工における表面被覆切削工具の耐チッピング性の向上を図ることも知られている。
(A) The lower layer is a titanium compound layer such as a titanium carbide layer, a titanium nitride layer, a titanium carbonitride layer, a titanium oxide layer, a titanium carbonate layer, a titanium nitride oxide layer, a titanium carbonitride oxide layer,
(B) The upper layer is an Al—Zr composite oxide layer having an α-type crystal structure, and the Al—Zr composite oxide layer is subjected to surface polishing using a field emission scanning electron microscope. Each crystal grain having a hexagonal crystal lattice existing in the measurement range is irradiated with an electron beam, and the (0001) plane and (10 − 10) The inclination angle formed by the normal of the plane is measured. In this case, the crystal grains have a crystal structure of a corundum hexagonal close-packed crystal in which constituent atoms composed of Al, Zr, and oxygen are present at lattice points. Based on the measurement inclination angle obtained as a result, lattice points (constituent atom shared lattice points) in which each of the constituent atoms shares one constituent atom between the crystal grains at the interface between adjacent crystal grains. ) Distribution and the constituent atom sharing case There are N lattice points that do not share constituent atoms between points (where N is an even number of 2 or more on the crystal structure of the corundum hexagonal close-packed crystal, but when the upper limit of N is 28 in terms of distribution frequency, (Even numbers of 4, 8, 14, 24, and 26 do not exist) When a constituent atomic shared lattice point form that is present is represented by ΣN + 1, a constituent atomic shared lattice point distribution indicating a distribution ratio of each ΣN + 1 in the entire ΣN + 1 In the graph, an Al-Zr composite having a high distribution ratio of grain boundaries corresponding to Σ3, which shows a constituent atom shared lattice point distribution graph in which the distribution ratio of Σ3 has a maximum peak in Σ3 and the distribution ratio of Σ3 to the entire ΣN + 1 is 60 to 80%. Oxide layer,
It is also known to improve the chipping resistance of a surface-coated cutting tool in high-speed intermittent cutting by depositing and forming the lower layer and the upper layer composed of (a) and (b).
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断続切削加工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、切刃に対して高負荷が作用する高送り、高切り込み等の高速重加工条件で行うのに用いた場合には、硬質被覆層を構成する上記従来の酸化アルミニウム相の素地に酸化ジルコニウム相が分散分布した混合組織層あるいは同じく従来のα型の結晶構造を有するＡｌ−Ｚｒ複合酸化物層では、高温強度が十分とはいえないためチッピング（微少欠け）を発生し易く、あるいは、耐熱塑性変形性が十分ではないために偏摩耗等が発生しやすく、この結果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 equipment has been remarkable. On the other hand, there is a strong demand for labor saving and energy saving and further cost reduction for cutting, and along with this, cutting tends to be faster. In tools, there is no problem when this is used for intermittent cutting under normal conditions such as steel and cast iron, but this is accompanied by high heat generation and a high load acts on the cutting edge. When used in high-speed heavy cutting conditions such as high feed and high cutting, a mixed structure layer in which the zirconium oxide phase is dispersed and distributed on the base of the above conventional aluminum oxide phase constituting the hard coating layer, or the conventional The Al-Zr composite oxide layer having an α-type crystal structure does not have sufficient high-temperature strength, so chipping (slight chipping) is likely to occur, or uneven heat resistance due to insufficient heat-resistant plastic deformation. Etc. are likely to occur, the reach this result relatively short time service life at present.
そこで、本発明者等は、上述のような観点から、上記の従来被覆工具のα型酸化アルミニウム相の素地に酸化ジルコニウム相が分散分布した混合組織層（以下、これを従来（Ａｌ，Ｚｒ）Ｏ層という）に着目し、耐チッピング性と耐摩耗性の両者の改善を図るべく鋭意研究を行った結果、以下の知見を得た。 In view of the above, the inventors of the present invention have a mixed structure layer in which the zirconium oxide phase is dispersed and distributed on the base of the α-type aluminum oxide phase of the above-mentioned conventional coated tool (hereinafter referred to as conventional (Al, Zr)). The following findings were obtained as a result of intensive research aimed at improving both chipping resistance and wear resistance.
上記従来被覆工具（特許文献１）においては、α型酸化アルミニウム層（以下、これを従来Ａｌ２Ｏ３層という）の表面側に、前記従来（Ａｌ，Ｚｒ）Ｏ層を蒸着形成するにあたり、通常の化学蒸着装置を用いて、Ｔｉ化合物層からなる下部層の表面に、例えば、
反応ガス組成：容量％で、ＡｌＣｌ3 ：１〜１０％、ＣＯ2 ：３〜１０％、Ｈ2 Ｓ：０．０２〜２％、ＨＣｌ：０．５〜５％、Ｈ2 ：残り、
反応雰囲気温度：１０００〜１０５０℃、
反応雰囲気圧力：５．３〜５３ｋＰａ、
の条件（以下、通常条件という）でまず従来Ａｌ２Ｏ３層を形成した後、
引き続き、上記の反応ガスにＺｒＣｌ4 を加えて、反応ガス組成を、例えば、
反応ガス組成：容量％で、ＡｌＣｌ3 ：１〜１０％、ＣＯ2 ：３〜１０％、Ｈ2 Ｓ：０．０２〜２％、ＨＣｌ：０．５〜５％、ＺｒＣｌ4 ：０．０５〜３％、Ｈ2 ：残り、
として、反応雰囲気温度および反応雰囲気圧力については同条件で化学蒸着を行うことにより、下部層側は従来Ａｌ２Ｏ３層からなり、一方、表面側は、従来（Ａｌ，Ｚｒ）Ｏ層からなる硬質被覆層が形成されていた。
In the conventional coated tool (Patent Document 1), when the conventional (Al, Zr) O layer is formed by vapor deposition on the surface side of an α-type aluminum oxide layer (hereinafter referred to as a conventional Al 2 O 3 layer), Using a normal chemical vapor deposition apparatus, on the surface of the lower layer made of a Ti compound layer, for example,
Reaction gas composition: by volume%, AlCl 3: 1~10%, CO 2: 3~10%, H 2 S: 0.02~2%, HCl: 0.5~5%, H 2: remainder,
Reaction atmosphere temperature: 1000 to 1050 ° C.
Reaction atmosphere pressure: 5.3 to 53 kPa,
After first forming a conventional Al 2 O 3 layer under the conditions (hereinafter referred to as normal conditions),
Subsequently, ZrCl 4 is added to the above reaction gas, and the reaction gas composition is, for example,
Reaction gas composition: by volume%, AlCl 3: 1~10%, CO 2: 3~10%, H 2 S: 0.02~2%, HCl: 0.5~5%, ZrCl 4: 0.05 ~3%, H 2: remainder,
As for the reaction atmosphere temperature and the reaction atmosphere pressure, by performing chemical vapor deposition under the same conditions, the lower layer side is made of a conventional Al 2 O 3 layer, while the surface side is made of a conventional (Al, Zr) O layer. A hard coating layer was formed.
そこで、上記従来Ａｌ２Ｏ３層の蒸着条件を変更し、通常の化学蒸着装置にて、Ｔｉ化合物層からなる下部層の表面に、例えば、
反応ガス組成：容量％で、ＡｌＣｌ3：３〜１０％、ＣＯ2：０．５〜３％、Ｃ２Ｈ４：０．０１〜０．３％、Ｈ2：残り、
反応雰囲気温度：７５０〜９００℃、
反応雰囲気圧力：３〜１３ｋＰａ、
の低温条件で、Ａｌ2Ｏ3核を形成し、この場合、前記Ａｌ2Ｏ3核は２０〜２００ｎｍの平均層厚を有するＡｌ2Ｏ3核薄膜であるのが望ましく、引き続いて、反応雰囲気を圧力：３〜１３ｋＰａの水素雰囲気に変え、反応雰囲気温度を１１００〜１２００℃に昇温した条件で前記Ａｌ2Ｏ3核薄膜に加熱処理を施した状態で、α型Ａｌ2Ｏ3層を通常の条件で形成すると、この結果の前記加熱処理Ａｌ2Ｏ3核薄膜上に蒸着形成されたα型Ａｌ2Ｏ3層は、電界放出型走査電子顕微鏡を用い、図１（ａ）、（ｂ）に概略説明図で示されるとおり、断面研磨面の測定範囲内に存在する六方晶結晶格子を有するα型Ａｌ2Ｏ3結晶粒個々に電子線を照射して、基体表面の法線に対して、前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、前記測定傾斜角のうち、０〜４５度の範囲内にある測定傾斜角を０．２５度のピッチ毎に区分すると共に、各区分内に存在する度数を集計してなる傾斜角度数分布グラフを作成した場合、前記従来Ａｌ2Ｏ3層は、図４に例示される通り、（０００１）面の測定傾斜角の分布は０〜４５度の範囲内で不偏的な傾斜角度数分布グラフを示すのに対して、前記加熱処理Ａｌ2Ｏ3核薄膜上に蒸着形成されたα型Ａｌ2Ｏ3層は、図３に例示されるとおり、傾斜角区分の特定位置にシャープな最高ピークが現れ、このシャープな最高ピークの位置は、前記Ａｌ2Ｏ3核薄膜の平均層厚を変化させることによりグラフ横軸の傾斜角区分に現れる位置が変わる。
つまり、前記加熱処理Ａｌ2Ｏ3核薄膜上に蒸着形成されたα型Ａｌ2Ｏ3層は、（０００１）面配向率が高いα型Ａｌ2Ｏ3層（以下、改質Ａｌ2Ｏ3層という）であることがわかる。
Therefore, the conventional Al 2 O 3 layer deposition conditions are changed, and the surface of the lower layer made of the Ti compound layer is changed, for example, by a normal chemical vapor deposition apparatus.
Reaction gas composition: volume%, AlCl 3 : 3 to 10%, CO 2 : 0.5 to 3%, C 2 H 4 : 0.01 to 0.3%, H 2 : remaining,
Reaction atmosphere temperature: 750 to 900 ° C.
Reaction atmosphere pressure: 3 to 13 kPa,
At low temperature conditions, to form a Al 2 O 3 nuclei. In this case, the Al 2 O 3 nuclei is desirably in the range of Al 2 O 3 nuclei thin film with an average layer thickness of 20 to 200 nm, and subsequently, reaction atmosphere pressure: changed to a hydrogen atmosphere of 3～13KPa, the reaction atmosphere temperature in a state subjected to heat treatment to the Al 2 O 3 nuclei film under conditions the temperature was raised to 1100 to 1200 ° C., the α type the Al 2 O 3 layer When formed under normal conditions, the α-type Al 2 O 3 layer deposited on the heat-treated Al 2 O 3 nuclear thin film as a result of this was formed using a field emission scanning electron microscope, as shown in FIGS. As shown in the schematic explanatory diagram in b), each α-type Al 2 O 3 crystal grain having a hexagonal crystal lattice existing within the measurement range of the cross-sectional polished surface is irradiated with an electron beam to obtain a normal to the substrate surface. On the other hand, the inclination angle formed by the normal line of the (0001) plane that is the crystal plane of the crystal grain is Measured and divided the measured inclination angle within the range of 0 to 45 degrees among the measured inclination angles for each pitch of 0.25 degrees, and the number of inclination angles obtained by totalizing the frequencies existing in each section When a distribution graph is created, the conventional Al 2 O 3 layer has an unbiased inclination angle number distribution within the range of 0 to 45 degrees in the measured inclination angle distribution of the (0001) plane as illustrated in FIG. In contrast to the graph, the α-type Al 2 O 3 layer deposited on the heat-treated Al 2 O 3 nuclear thin film has a sharp peak at a specific position in the tilt angle section as illustrated in FIG. A peak appears, and the position of the sharp peak is changed by changing the average layer thickness of the Al 2 O 3 nuclear thin film.
That is, the α-type Al 2 O 3 layer deposited on the heat-treated Al 2 O 3 nuclear thin film is an α-type Al 2 O 3 layer (hereinafter referred to as modified Al 2 O 3 ) having a high (0001) plane orientation ratio. It is understood that it is a layer).
次に、上記の如く蒸着形成した（０００１）面配向率が高い改質Ａｌ2Ｏ3層を中間層として、その表面に、通常の化学蒸着装置にて、例えば、
反応ガス組成：容量％で、ＡｌＣｌ３：２〜５％、ＺｒＣｌ４：０．９〜１．６％、ＣＯ２：２〜６％、ＨＣｌ：２〜５％、Ｈ2Ｓ：０．１〜０．６％、Ｈ2：残り、
反応雰囲気温度：９８０〜１０４０℃、
反応雰囲気圧力：６〜１０ｋＰａ、
の条件で上部層を蒸着形成すると、該上部層として、α型酸化アルミニウム相の素地に酸化ジルコニウム相が均一に分散分布した均一混合組織層が形成された。
Next, a modified Al 2 O 3 layer having a high (0001) plane orientation ratio formed by vapor deposition as described above is used as an intermediate layer, and the surface thereof is subjected to, for example, a normal chemical vapor deposition apparatus.
Reaction gas composition: volume%, AlCl 3 : 2 to 5%, ZrCl 4 : 0.9 to 1.6%, CO 2 : 2 to 6%, HCl: 2 to 5%, H 2 S: 0.1 ~0.6%, H 2: remainder,
Reaction atmosphere temperature: 980-1040 ° C.
Reaction atmosphere pressure: 6 to 10 kPa,
When the upper layer was formed by vapor deposition under the above conditions, a uniform mixed structure layer in which the zirconium oxide phase was uniformly dispersed and distributed on the base of the α-type aluminum oxide phase was formed as the upper layer.
そして、上記α型酸化アルミニウム相の素地に酸化ジルコニウム相が分散分布した均一混合組織層（以下、改質（Ａｌ，Ｚｒ）Ｏ層という）からなる上部層について、電界放出型走査電子顕微鏡を用い、断面研磨面の測定範囲内に存在する六方晶結晶格子を有する結晶粒個々に電子線を照射して、前記断面研磨面の法線に対して、前記結晶粒の結晶面である（０００１）面および（１０−１０）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、相互に隣接する結晶粒の界面で、前記構成原子のそれぞれが前記結晶粒相互間で１つの構成原子を共有する格子点（構成原子共有格子点）の分布を算出し、前記構成原子共有格子点間に構成原子を共有しない格子点がＮ個（ただし、Ｎはコランダム型六方最密晶の結晶構造上２以上の偶数となるが、分布頻度の点からＮの上限を２８とした場合、４、８、１４、２４、および２６の偶数は存在せず）存在する構成原子共有格子点形態をΣＮ＋１で表し、個々のΣＮ＋１がΣＮ＋１全体に占める分布割合を示す構成原子共有格子点分布グラフを作成した場合（この場合前記の結果から、Σ５、Σ９、Σ１５、Σ２５、およびΣ２７の構成原子共有格子点形態は存在しないことになる）、図５に示されるとおり、Σ３に最高ピークが存在し、かつ前記Σ３のΣＮ＋１全体に占める分布割合が４０〜６０％である構成原子共有格子点分布グラフを示し、しかも、この改質（Ａｌ，Ｚｒ）Ｏ層は、前記従来（Ａｌ，Ｚｒ）Ｏ層に比して、一段とすぐれた高温強度および耐熱塑性変形性を有することがわかった。 A field emission scanning electron microscope is used for the upper layer composed of a uniform mixed structure layer (hereinafter referred to as a modified (Al, Zr) O layer) in which the zirconium oxide phase is dispersed and distributed on the substrate of the α-type aluminum oxide phase. The crystal grains having a hexagonal crystal lattice existing within the measurement range of the cross-section polished surface are irradiated with an electron beam, and the crystal plane of the crystal grains is normal to the cross-section polished plane (0001) The tilt angle formed by the normal of the plane and the (10-10) plane is measured, and based on the measured tilt angle obtained as a result, each of the constituent atoms is the crystal grain at the interface between the crystal grains adjacent to each other. The distribution of lattice points (constituent atom shared lattice points) that share one constituent atom between them is calculated, and N lattice points that do not share constituent atoms between the constituent atom shared lattice points (where N is a corundum type) Crystal structure of hexagonal close-packed crystal Even if the upper limit of N is 28 from the point of distribution frequency, the even number of 4, 8, 14, 24, and 26 does not exist). When the constituent atomic shared lattice point distribution graph showing the distribution ratio of each ΣN + 1 in the entire ΣN + 1 is created (in this case, from the above result, the constituent atomic shared lattice point forms of Σ5, Σ9, Σ15, Σ25, and Σ27) As shown in FIG. 5, as shown in FIG. 5, a constitutive atomic shared lattice point distribution graph in which the highest peak exists in Σ3 and the distribution ratio of the Σ3 to the entire ΣN + 1 is 40 to 60%, Moreover, it was found that this modified (Al, Zr) O layer has much higher temperature strength and heat-resistant plastic deformation than the conventional (Al, Zr) O layer.
なお、前記特許文献１における従来（Ａｌ，Ｚｒ）Ｏ層について、上記と同様にして、個々のΣＮ＋１がΣＮ＋１全体に占める分布割合を示す構成原子共有格子点分布グラフを作成したところ、図６に示される通り、Σ３の分布割合は２０％以下の相対的に低い構成原子共有格子点分布グラフを示した。つまり、改質（Ａｌ，Ｚｒ）Ｏ層は、従来（Ａｌ，Ｚｒ）Ｏ層と異なり、改質Ａｌ2Ｏ3層が中間層として蒸着形成されていることによって、Σ３対応粒界の分布割合が非常に高くなり、その結果として、従来（Ａｌ，Ｚｒ）Ｏ層に比して高温強度および耐熱塑性変形性が一段と向上することがわかった。 For the conventional (Al, Zr) O layer in Patent Document 1, a constituent atomic shared lattice distribution graph showing the distribution ratio of individual ΣN + 1 to the entire ΣN + 1 was created in the same manner as described above. As shown, the distribution ratio of Σ3 is a relatively low constituent atom shared lattice point distribution graph of 20% or less. In other words, the modified (Al, Zr) O layer is different from the conventional (Al, Zr) O layer in that the modified Al 2 O 3 layer is formed as an intermediate layer by vapor deposition. As a result, it was found that the high-temperature strength and the heat-resistant plastic deformation are further improved as compared with the conventional (Al, Zr) O layer.
上記のとおり、硬質被覆層として、Ｔｉ化合物層からなる下部層の表面に、中間層として前記改質Ａｌ2Ｏ3層を蒸着形成し、その上に更に上部層としての改質（Ａｌ，Ｚｒ）Ｏ層を蒸着形成した本発明の被覆工具は、従来被覆工具に比して、一段とすぐれた高温強度および耐熱塑性変形性を有することから、高熱発生を伴うと共に、切刃部に高負荷が作用する高送り、高切り込み等の高速重切削条件に用いた場合にも、すぐれた耐チッピング性とすぐれた耐摩耗性を発揮する。 As described above, the modified Al 2 O 3 layer is vapor-deposited as an intermediate layer on the surface of the lower layer made of the Ti compound layer as the hard coating layer, and further modified as the upper layer (Al, Zr) ) The coated tool of the present invention in which the O layer is formed by vapor deposition has higher temperature strength and heat-resistant plastic deformation than the conventional coated tool. Even when used in high-speed heavy cutting conditions such as high feed and high depth of cut, it exhibits excellent chipping resistance and excellent wear resistance.
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、下部層と中間層と上部層とからなる硬質被覆層を蒸着形成した表面被覆切削工具において、
（ａ）下部層は、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層以上からなり、かつ、３〜２０μｍの全体平均層厚を有するＴｉ化合物層、
（ｂ）中間層は、化学蒸着した状態でα型の結晶構造を有し、かつ、１〜３μｍの平均層厚を有するα型酸化アルミニウム層であって、
該中間層について、電界放出型走査電子顕微鏡を用い、断面研磨面の測定範囲内に存在する六方晶結晶格子を有する結晶粒個々に電子線を照射して、基体表面の法線に対して、前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、前記測定傾斜角のうち、０〜４５度の範囲内にある測定傾斜角を０．２５度のピッチ毎に区分すると共に、各区分内に存在する度数を集計してなる傾斜角度数分布グラフで現した場合、０〜１０度の範囲内の傾斜角区分に最高ピークが存在すると共に、前記０〜１０度の範囲内に存在する度数の合計が、傾斜角度数分布グラフにおける度数全体の４５％以上の割合を占める傾斜角度数分布グラフを示すα型酸化アルミニウム層、
（ｃ）上部層は、化学蒸着した状態でα型の結晶構造を有し、かつ、２〜１５μｍの平均層厚を有し、さらに、α型酸化アルミニウム相の素地に酸化ジルコニウム相が均一に分散分布した均一混合組織層であって、
該上部層について、電界放出型走査電子顕微鏡を用い、断面研磨面の測定範囲内に存在する六方晶結晶格子を有する結晶粒個々に電子線を照射して、前記断面研磨面の法線に対して、前記結晶粒の結晶面である（０００１）面および（１０−１０）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、相互に隣接する結晶粒の界面で、前記構成原子のそれぞれが前記結晶粒相互間で１つの構成原子を共有する格子点（構成原子共有格子点）の分布を算出し、前記構成原子共有格子点間に構成原子を共有しない格子点がＮ個（ただし、Ｎはコランダム型六方最密晶の結晶構造上２以上の偶数となるが、分布頻度の点からＮの上限を２８とした）存在する構成原子共有格子点形態をΣＮ＋１で表した場合、個々のΣＮ＋１がΣＮ＋１全体に占める分布割合を示す構成原子共有格子点分布グラフにおいて、Σ３に最高ピークが存在し、かつ前記Σ３のΣＮ＋１全体に占める分布割合が４０〜６０％である構成原子共有格子点分布グラフを示すα型酸化アルミニウム相と酸化ジルコニウム相の均一混合組織層、
以上（ａ）〜（ｃ）で構成された硬質被覆層を蒸着形成してなる、硬質被覆層が高速重切削加工ですぐれた耐チッピング性、耐摩耗性を発揮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,
In a surface-coated cutting tool in which a hard coating layer composed of a lower layer, an intermediate layer, and an upper layer is vapor-deposited on the surface of a tool base composed of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet,
(A) The lower layer is composed of one or more of a Ti carbide layer, a nitride layer, a carbonitride layer, a carbonate layer, and a carbonitride layer, and has a total thickness of 3 to 20 μm. A Ti compound layer having an average layer thickness;
(B) The intermediate layer is an α-type aluminum oxide layer having an α-type crystal structure in a chemical vapor deposited state and having an average layer thickness of 1 to 3 μm,
For the intermediate layer, using a field emission scanning electron microscope, each crystal grain having a hexagonal crystal lattice existing within the measurement range of the cross-sectional polished surface is irradiated with an electron beam, The inclination angle formed by the normal line of the (0001) plane, which is the crystal plane of the crystal grain, is measured, and the measurement inclination angle within the range of 0 to 45 degrees out of the measurement inclination angles is set to a pitch of 0.25 degrees. In addition, the maximum peak exists in the inclination angle division within the range of 0 to 10 degrees, and the above 0 to 10 are expressed in the inclination angle number distribution graph obtained by adding up the frequencies existing in each division. An α-type aluminum oxide layer showing a tilt angle number distribution graph in which the total number of frequencies existing in the range of degrees occupies a ratio of 45% or more of the total frequency in the tilt angle number distribution graph,
(C) The upper layer has an α-type crystal structure in the state of chemical vapor deposition, has an average layer thickness of 2 to 15 μm, and further has a uniform zirconium oxide phase on the base of the α-type aluminum oxide phase. A uniform mixed tissue layer distributed and distributed,
For the upper layer, using a field emission scanning electron microscope, each crystal grain having a hexagonal crystal lattice existing within the measurement range of the cross-sectional polished surface is irradiated with an electron beam to Then, the inclination angles formed by the normal lines of the (0001) plane and the (10-10) plane, which are the crystal planes of the crystal grains, are measured, and the crystal grains adjacent to each other are measured based on the measured inclination angles. The distribution of lattice points (constituent atom shared lattice points) in which each of the constituent atoms shares one constituent atom between the crystal grains is calculated at the interface, and the constituent atoms are shared between the constituent atom shared lattice points. There are N lattice points (N is an even number of 2 or more on the crystal structure of the corundum hexagonal close-packed crystal, but the upper limit of N is 28 in terms of distribution frequency). Is represented by ΣN + 1, each ΣN + 1 is Σ In the constituent atom shared lattice point distribution graph showing the distribution ratio in the entire +1, the constituent atom shared lattice point distribution graph in which the highest peak exists in Σ3 and the distribution ratio in the entire ΣN + 1 of the Σ3 is 40 to 60%. A uniform mixed structure layer of α-type aluminum oxide phase and zirconium oxide phase shown,
A surface-coated cutting tool in which a hard coating layer composed of the above (a) to (c) is formed by vapor deposition, and the hard coating layer exhibits excellent chipping resistance and wear resistance in high-speed heavy cutting. "
It has the characteristics.
以下に、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。 Below, the constituent layer of the hard coating layer of the coated tool of this invention is demonstrated in detail.
下部層のＴｉ化合物層：
Ｔｉ化合物層は、改質Ａｌ2Ｏ3層の下部層として存在し、自身の具備するすぐれた高温強度によって硬質被覆層の高温強度向上に寄与するほか、工具基体と改質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を向上させる作用を有するが、その平均層厚が３μｍ未満では、前記作用を十分に発揮させることができず、一方その平均層厚が２０μｍを越えると、特に高熱発生を伴なう高負荷が作用する高速重切削では熱塑性変形を起し易くなり、これが偏摩耗の原因となることから、その平均層厚を３〜２０μｍと定めた。
Lower Ti compound layer:
Ti compound layer exists as a lower layer of the reformer the Al 2 O 3 layer, in addition contributes to the improvement of the high temperature strength of the hard coating layer by excellent high temperature strength which includes its own tool substrate and the reformed the Al 2 O 3 layer However, if the average layer thickness is less than 3 μm, the above-mentioned effect cannot be fully exerted, while the adhesion of the hard coating layer to the tool base is improved. When the average layer thickness exceeds 20 μm, it becomes easy to cause thermoplastic deformation in high-speed heavy cutting in which a high load with high heat generation acts, and this causes uneven wear. It was determined to be 20 μm.
中間層の改質Ａｌ2Ｏ3層：
中間層を構成する改質Ａｌ2Ｏ3層は、通常の化学蒸着装置にて、Ｔｉ化合物層からなる下部層の表面に、例えば、
反応ガス組成：容量％で、ＡｌＣｌ3：３〜１０％、ＣＯ2：０．５〜３％、Ｃ２Ｈ４：０．０１〜０．３％、Ｈ2：残り、
反応雰囲気温度：７５０〜９００℃、
反応雰囲気圧力：３〜１３ｋＰａ、
の低温条件で、Ａｌ2Ｏ3核を形成し、この場合、前記Ａｌ2Ｏ3核は２０〜２００ｎｍの平均層厚を有するＡｌ2Ｏ3核薄膜であるのが望ましく、引き続いて、反応雰囲気を圧力：３〜１３ｋＰａの水素雰囲気に変え、反応雰囲気温度を１１００〜１２００℃に昇温した条件で前記Ａｌ2Ｏ3核薄膜に加熱処理を施した状態で、α型Ａｌ2Ｏ3層を通常の条件で蒸着することにより形成することができる。
中間層の改質Ａｌ2Ｏ3層はすぐれた高温硬さを備え、耐摩耗性の向上に寄与するばかりか、下部層のＴｉ化合物層および上部層の改質（Ａｌ，Ｚｒ）Ｏ層のいずれにも強固に密着し、硬質被覆層全体としての剥離強度を向上させる。
Modified Al 2 O 3 layer of the intermediate layer:
The modified Al 2 O 3 layer constituting the intermediate layer is formed on the surface of the lower layer made of the Ti compound layer by a normal chemical vapor deposition apparatus, for example,
Reaction gas composition: volume%, AlCl 3 : 3 to 10%, CO 2 : 0.5 to 3%, C 2 H 4 : 0.01 to 0.3%, H 2 : remaining,
Reaction atmosphere temperature: 750 to 900 ° C.
Reaction atmosphere pressure: 3 to 13 kPa,
At low temperature conditions, to form a Al 2 O 3 nuclei. In this case, the Al 2 O 3 nuclei is desirably in the range of Al 2 O 3 nuclei thin film with an average layer thickness of 20 to 200 nm, and subsequently, reaction atmosphere pressure: changed to a hydrogen atmosphere of 3～13KPa, the reaction atmosphere temperature in a state subjected to heat treatment to the Al 2 O 3 nuclei film under conditions the temperature was raised to 1100 to 1200 ° C., the α type the Al 2 O 3 layer It can be formed by vapor deposition under normal conditions.
The modified Al 2 O 3 layer of the intermediate layer has excellent high-temperature hardness and contributes to the improvement of wear resistance, as well as the Ti compound layer of the lower layer and the modified (Al, Zr) O layer of the upper layer. It adheres firmly to both and improves the peel strength of the entire hard coating layer.
さらに、上記改質Ａｌ2Ｏ3層は、電界放出型走査電子顕微鏡を用い、断面研磨面の測定範囲内に存在する六方晶結晶格子を有する結晶粒個々に電子線を照射して、基体表面の法線に対して、前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、前記測定傾斜角のうち、０〜４５度の範囲内にある測定傾斜角を０．２５度のピッチ毎に区分すると共に、各区分内に存在する度数を集計してなる傾斜角度数分布グラフで現した場合、０〜１０度の範囲内の傾斜角区分に最高ピークが存在すると共に、前記０〜１０度の範囲内に存在する度数の合計が、傾斜角度数分布グラフにおける度数全体の４５％以上の割合を占める傾斜角度数分布グラフを示し、（０００１）面配向率が高いものとなっている。
そして、このような（０００１）面配向率が高い改質Ａｌ2Ｏ3層の上に、上部層としての改質（Ａｌ，Ｚｒ）Ｏ層（α型酸化アルミニウム相と酸化ジルコニウム相の均一混合組織層）を蒸着形成することによって、該改質（Ａｌ，Ｚｒ）Ｏ層にはＺｒ成分が含有されているにもかかわらず、Σ３対応粒界が高い割合で形成されて粒界強度が向上し、その結果として、改質（Ａｌ，Ｚｒ）Ｏ層が、すぐれた耐熱塑性変形性とともにすぐれた高温強度を備えるようになる。
すなわち、中間層の改質Ａｌ2Ｏ3層は、配向性のない従来Ａｌ2Ｏ3層を中間層として設けた場合に比して、上部層の改質（Ａｌ，Ｚｒ）Ｏ層のΣ３対応粒界の割合を高めるという大きな役割を担っている。
上記改質Ａｌ2Ｏ3層についての傾斜角度数分布グラフにおいて、０〜１０度の範囲内に存在する度数の合計が、傾斜角度数分布グラフにおける度数全体の４５％未満の場合には、上部層におけるΣ３対応粒界の割合の増加を期待できないので、加熱処理Ａｌ2Ｏ3核薄膜上にさらにα型Ａｌ2Ｏ3層を蒸着することによって改質Ａｌ2Ｏ3層を形成するに際しては、Ａｌ2Ｏ3核薄膜の平均層厚を２０〜２００ｎｍとすることが望ましい。
なお、改質Ａｌ2Ｏ3層からなる中間層の平均層厚が１μｍ未満では、（０００１）面配向率が４５％未満となってしまい、一方、平均層厚が３μｍを超える場合には、上部層である改質（Ａｌ，Ｚｒ）Ｏ層との付着強度が低下するため、その平均層厚は１〜３μｍと定めた。
Further, the modified Al 2 O 3 layer is formed by irradiating individual crystal grains having a hexagonal crystal lattice existing within the measurement range of the cross-section polished surface with a field emission scanning electron microscope, The inclination angle formed by the normal line of the (0001) plane which is the crystal plane of the crystal grain is measured, and the measurement inclination angle within the range of 0 to 45 degrees is measured among the measurement inclination angles. When divided into 0.25 degree pitches and represented in a slope angle distribution graph obtained by counting the frequencies present in each part, the highest peak exists in the slope angle range within the range of 0 to 10 degrees. In addition, an inclination angle number distribution graph in which the total of the frequencies existing in the range of 0 to 10 degrees occupies a ratio of 45% or more of the entire degrees in the inclination angle number distribution graph is shown, and the (0001) plane orientation ratio is It is expensive.
Then, on such a modified Al 2 O 3 layer having a high (0001) plane orientation ratio, a modified (Al, Zr) O layer (an α-type aluminum oxide phase and a zirconium oxide phase are uniformly mixed) as an upper layer By forming the texture layer), the modified (Al, Zr) O layer has a high proportion of Σ3-compatible grain boundaries and improves the grain boundary strength, despite the fact that the Zr component is contained. As a result, the modified (Al, Zr) O layer has excellent high temperature strength as well as excellent heat plastic deformation.
That is, the intermediate layer reforming the Al 2 O 3 layer of, in comparison with the case of providing the orientation without prior the Al 2 O 3 layer as an intermediate layer, modification of the upper layer (Al, Zr) O-layer Σ3 It plays a major role in increasing the proportion of corresponding grain boundaries.
In the inclination angle frequency distribution graph for the modified Al 2 O 3 layer, when the sum of the frequencies existing in the range of 0 to 10 degrees is less than 45% of the entire frequency in the inclination angle frequency distribution graph, the upper part Since an increase in the proportion of Σ3-compatible grain boundaries in the layer cannot be expected, when forming a modified Al 2 O 3 layer by further depositing an α-type Al 2 O 3 layer on the heat-treated Al 2 O 3 core thin film, The average layer thickness of the Al 2 O 3 core thin film is preferably 20 to 200 nm.
When the average layer thickness of the intermediate layer composed of the modified Al 2 O 3 layer is less than 1 μm, the (0001) plane orientation ratio is less than 45%, while when the average layer thickness exceeds 3 μm, Since the adhesion strength with the modified (Al, Zr) O layer, which is the upper layer, decreases, the average layer thickness was determined to be 1 to 3 μm.
上部層の改質（Ａｌ，Ｚｒ）Ｏ層：
上部層を構成する改質（Ａｌ，Ｚｒ）Ｏ層は、通常の化学蒸着装置にて、改質Ａｌ2Ｏ3層からなる中間層の表面に、例えば、
反応ガス組成：容量％で、ＡｌＣｌ３：２〜５％、ＺｒＣｌ４：０．９〜１．６％、ＣＯ２：２〜６％、ＨＣｌ：２〜５％、Ｈ2Ｓ：０．１〜０．６％、Ｈ2：残り、
反応雰囲気温度：９８０〜１０４０℃、
反応雰囲気圧力：６〜１０ｋＰａ、
の条件で蒸着することにより形成することができる。
上部層の改質（Ａｌ，Ｚｒ）Ｏ層は、α型酸化アルミニウム相の素地に酸化ジルコニウム相が均一に分散分布した均一混合組織を示し、特に、素地を構成するα型酸化アルミニウム相は層の高温硬さおよび耐熱性を向上させ、また、素地中に均一分散分布する酸化ジルコニウム相は高温強度と耐熱塑性変形性を向上させる。
Upper layer modified (Al, Zr) O layer:
The modified (Al, Zr) O layer constituting the upper layer is formed on the surface of the intermediate layer composed of the modified Al 2 O 3 layer by a normal chemical vapor deposition apparatus, for example,
Reaction gas composition: volume%, AlCl 3 : 2 to 5%, ZrCl 4 : 0.9 to 1.6%, CO 2 : 2 to 6%, HCl: 2 to 5%, H 2 S: 0.1 ~0.6%, H 2: remainder,
Reaction atmosphere temperature: 980-1040 ° C.
Reaction atmosphere pressure: 6 to 10 kPa,
It can form by vapor-depositing on condition of this.
The modified (Al, Zr) O layer of the upper layer shows a uniform mixed structure in which the zirconium oxide phase is uniformly dispersed and distributed on the base of the α-type aluminum oxide phase. In particular, the α-type aluminum oxide phase constituting the base is a layer. The high-temperature hardness and heat resistance of the zirconium oxide phase and the zirconium oxide phase uniformly dispersed in the substrate improve the high-temperature strength and heat-resistant plastic deformation.
また、改質（Ａｌ，Ｚｒ）Ｏ層からなる上部層について、電界放出型走査電子顕微鏡を用い、断面研磨面の測定範囲内に存在する六方晶結晶格子を有する結晶粒個々に電子線を照射して、前記断面研磨面の法線に対して、前記結晶粒の結晶面である（０００１）面および（１０−１０）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、相互に隣接する結晶粒の界面で、前記構成原子のそれぞれが前記結晶粒相互間で１つの構成原子を共有する格子点（構成原子共有格子点）の分布を算出し、前記構成原子共有格子点間に構成原子を共有しない格子点がＮ個（ただし、Ｎはコランダム型六方最密晶の結晶構造上２以上の偶数となるが、分布頻度の点からＮの上限を２８とした）存在する構成原子共有格子点形態をΣＮ＋１で表した場合、個々のΣＮ＋１がΣＮ＋１全体に占める分布割合を示す構成原子共有格子点分布グラフにおいて、Σ３に最高ピークが存在し、かつ前記Σ３のΣＮ＋１全体に占める分布割合が４０〜６０％である構成原子共有格子点分布グラフを示すようになる。
即ち、上部層の改質（Ａｌ，Ｚｒ）Ｏ層は、改質Ａｌ2Ｏ3層を中間層として設け、この上に蒸着形成されることによって、Σ３対応粒界の割合が増加し粒界強度が高められため、その結果として、改質（Ａｌ，Ｚｒ）Ｏ層は高温強度、耐熱塑性変形性が一段とすぐれたものとなり、耐チッピング性、耐欠損性を向上させる。
In addition, the upper layer composed of the modified (Al, Zr) O layer is irradiated with an electron beam on each crystal grain having a hexagonal crystal lattice existing within the measurement range of the cross-sectional polished surface using a field emission scanning electron microscope. Then, the inclination angle formed by the normal lines of the (0001) plane and the (10-10) plane, which are crystal planes of the crystal grains, is measured with respect to the normal line of the cross-section polished surface, and the measurement obtained as a result Based on the tilt angle, the distribution of lattice points (constituent atom shared lattice points) in which each of the constituent atoms shares one constituent atom between the crystal grains at the interface between adjacent crystal grains is calculated, There are N lattice points that do not share constituent atoms between the constituent atomic shared lattice points (where N is an even number of 2 or more on the crystal structure of the corundum hexagonal close-packed crystal, but the upper limit of N is limited in terms of distribution frequency. 28) The existing configuration atom shared lattice point form is ΣN In the constituent atom shared lattice point distribution graph showing the distribution ratio of each ΣN + 1 in the entire ΣN + 1 when represented by 1, the highest peak exists in Σ3, and the distribution ratio of the Σ3 in the entire ΣN + 1 is 40 to 60%. The constituent atomic shared lattice point distribution graph is shown.
That is, the modified (Al, Zr) O layer of the upper layer is provided with a modified Al 2 O 3 layer as an intermediate layer, and is formed by vapor deposition on this, thereby increasing the proportion of the Σ3 corresponding grain boundary and increasing the grain boundary. Since the strength is increased, as a result, the modified (Al, Zr) O layer is further improved in high-temperature strength and heat-resistant plastic deformability, and improves chipping resistance and chipping resistance.
そして、Σ３対応粒界の分布割合を上記４０〜６０％とするためには、上部層におけるＡｌとの合量に占めるＺｒの含有割合（Ｚｒ／（Ａｌ＋Ｚｒ））は０．００３〜０．２原子％であることが必要であり、Ｚｒ含有割合が０．００３原子％未満である場合には、Σ３対応粒界の分布割合を増加させることができたとしても、上部層の耐熱塑性変形性が不十分となり、偏摩耗の発生等による耐摩耗性劣化の恐れがある。一方、Ｚｒ含有割合が０．２原子％を超えるような場合には、Σ３対応粒界の分布割合が４０％未満となってしまい、高温強度の向上を期待できなくなる。そして、上部層におけるＺｒ成分の含有量が上記０．００３〜０．２原子％の範囲内である場合には、酸化ジルコニウム相は素地中に均一微細な分散相として存在することから、硬質被覆層の耐チッピング性、耐欠損性、耐剥離性に悪影響を及ぼすことはない。 And in order to make the distribution ratio of (SIGMA) 3 corresponding | compatible grain boundary into the said 40 to 60%, the content rate (Zr / (Al + Zr)) which occupies for the total amount with Al in an upper layer is 0.003-0.2. When the Zr content is less than 0.003 atomic%, even if the distribution ratio of the grain boundary corresponding to Σ3 can be increased, the heat resistant plastic deformation property of the upper layer is required. Is insufficient, and there is a risk of wear resistance deterioration due to the occurrence of uneven wear. On the other hand, when the Zr content ratio exceeds 0.2 atomic%, the distribution ratio of the Σ3-corresponding grain boundary is less than 40%, and improvement in high-temperature strength cannot be expected. When the content of the Zr component in the upper layer is within the range of 0.003 to 0.2 atomic%, the zirconium oxide phase exists as a uniform fine dispersed phase in the substrate. It does not adversely affect the chipping resistance, chipping resistance, and peel resistance of the layer.
改質（Ａｌ，Ｚｒ）Ｏ層からなる上部層は、その平均層厚が１μｍ未満では、すぐれた高温強度を発揮することができず、一方、その平均層厚が１４μｍを超えるとチッピング等を発生しやすくなるので、その平均層厚は、１〜１４μｍと定めた。 The upper layer composed of the modified (Al, Zr) O layer cannot exhibit excellent high-temperature strength when the average layer thickness is less than 1 μm, while chipping or the like occurs when the average layer thickness exceeds 14 μm. Since it becomes easy to generate | occur | produce, the average layer thickness was defined as 1-14 micrometers.
なお、改質Ａｌ2Ｏ3層からなる中間層と改質（Ａｌ，Ｚｒ）Ｏ層からなる上部層との合計平均層厚は、チッピング発生防止等との観点から、２〜１５μｍとすることが望ましい。 The total average layer thickness of the intermediate layer composed of the modified Al 2 O 3 layer and the upper layer composed of the modified (Al, Zr) O layer should be 2 to 15 μm from the viewpoint of preventing chipping and the like. Is desirable.
この発明の被覆工具は、各種の鋼や鋳鉄などの切削加工を、高い発熱を伴うと共に、切刃部に高負荷が作用する高送り、高切り込みの高速重切削条件で行うのに用いた場合にも、硬質被覆層の中間層として改質Ａｌ2Ｏ3層が設けられ、さらにこの上にΣ３対応粒界の分布割合の高められた改質（Ａｌ，Ｚｒ）Ｏ層が設けられたことによって、硬質被覆層がすぐれた高温強度と耐熱塑性変形性を備え、その結果、長期の使用に亘って一段とすぐれた耐チッピング性と耐摩耗性を発揮するものである。 The coated tool of the present invention is used when cutting various steels and cast irons, etc., under high-speed heavy cutting conditions with high feed and high cutting with high heat generation and high load on the cutting edge. In addition, a modified Al 2 O 3 layer was provided as an intermediate layer of the hard coating layer, and a modified (Al, Zr) O layer with an increased distribution ratio of Σ3-compatible grain boundaries was further provided thereon. Thus, the hard coating layer has excellent high-temperature strength and heat-resistant plastic deformation, and as a result, exhibits excellent chipping resistance and 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２〜４μｍ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・ＣＮＭＧ１６０４１２に規定するスローアウエイチップ形状をもった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 2 to 4 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 processing, tool bases A to F made of a WC-based cemented carbide having a throwaway tip shape defined in ISO · CNMG 160412 were produced.
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・ＣＮＭＧ１６０４１２のチップ形状をもった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 standard / CNMG 160412 chip shapes were formed.
ついで、これらの工具基体Ａ〜Ｆおよび工具基体ａ〜ｆのそれぞれを、通常の化学蒸着装置に装入し、まず、表３（表３中のｌ−ＴｉＣＮは特開平６−８０１０号公報に記載される縦長成長結晶組織をもつＴｉＣＮ層の形成条件を示すものであり、これ以外は通常の粒状結晶組織の形成条件を示すものである）に示される条件にて、表６に示される組み合わせおよび目標層厚でＴｉ化合物層を硬質被覆層の下部層として蒸着形成し、ついで、同じく表４に示される条件で、表６に示される組み合わせおよび目標層厚で改質Ａｌ2Ｏ3層を硬質被覆層の中間層として蒸着形成し、さらに、表５に示される条件で、表６に示される組み合わせおよび目標層厚で改質（Ａｌ，Ｚｒ）Ｏ層を硬質被覆層の上部層として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, each of the tool bases A to F and the tool bases a to f was charged into a normal chemical vapor deposition apparatus. First, Table 3 (l-TiCN in Table 3 is disclosed in JP-A-6-8010). The combinations shown in Table 6 under the conditions shown in Table 6 are the conditions for forming the TiCN layer having the vertically elongated crystal structure described, and other conditions for forming the normal granular crystal structure. And a Ti compound layer with a target layer thickness as a lower layer of the hard coating layer, and then, under the same conditions as shown in Table 4, a modified Al 2 O 3 layer with the combinations and target layer thicknesses shown in Table 6 is formed. Evaporation is formed as an intermediate layer of the hard coating layer, and further, a modified (Al, Zr) O layer is deposited as the upper layer of the hard coating layer under the conditions shown in Table 5 with the combinations and target layer thicknesses shown in Table 6. By forming the present invention The tool 1 to 13 were produced, respectively.
比較の目的で、表７に示される通り、硬質被覆層の中間層として、表４に示される条件で、表７に示される目標層厚で従来Ａｌ2Ｏ3層を形成する以外は本発明被覆工具１〜１３と同一の条件で比較被覆工具１〜１３をそれぞれ製造した。 For comparison purposes, as shown in Table 7, the present invention except that the conventional Al 2 O 3 layer is formed as the intermediate layer of the hard coating layer under the conditions shown in Table 4 and with the target layer thickness shown in Table 7. Comparative coated tools 1 to 13 were produced under the same conditions as the coated tools 1 to 13, respectively.
ついで、上記の本発明被覆工具１〜１３および比較被覆工具１〜１３の硬質被覆層の中間層を構成する改質Ａｌ2Ｏ3層および従来Ａｌ2Ｏ3層のそれぞれについて、電界放出型走査電子顕微鏡を用いて、断面研磨面の測定範囲内に存在する六方晶結晶格子を有する結晶粒個々に電子線を照射して、基体表面の法線に対して、前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、前記測定傾斜角のうち、０〜４５度の範囲内にある測定傾斜角を０．２５度のピッチ毎に区分すると共に、各区分内に存在する度数を集計してなる傾斜角度数分布グラフを作成した。
すなわち、工具基体表面と垂直な面をそれぞれ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、それぞれの前記研磨面の測定範囲内に存在する六方晶結晶格子を有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、３０×５０μｍの領域を０．１μｍ／ｓｔｅｐの間隔で、基体表面の法線に対して、前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、この測定結果に基づいて、前記測定傾斜角のうち０〜４５度の範囲内にある測定傾斜角を０．２５度のピッチ毎に区分すると共に、各区分内に存在する度数を集計することにより作成した。
Next, field emission scanning is performed on each of the modified Al 2 O 3 layer and the conventional Al 2 O 3 layer constituting the intermediate layer of the hard coating layer of the present invention coated tools 1 to 13 and comparative coated tools 1 to 13. Using an electron microscope, each crystal grain having a hexagonal crystal lattice existing within the measurement range of the cross-sectional polished surface is irradiated with an electron beam, and is a crystal plane of the crystal grain with respect to the normal of the substrate surface The inclination angle formed by the normal of the (0001) plane is measured, and among the measurement inclination angles, the measurement inclination angles in the range of 0 to 45 degrees are divided for each pitch of 0.25 degrees, and within each division An inclination angle frequency distribution graph was created by counting the frequencies existing in.
That is, in a state where each surface perpendicular to the tool base surface is a polished surface, it is set in a barrel of a field emission scanning electron microscope, and an electron beam with an acceleration voltage of 15 kV is applied to the polished surface at an incident angle of 70 degrees. With an irradiation current of 1 nA, each crystal grain having a hexagonal crystal lattice existing within the measurement range of each polished surface is irradiated, and an electron backscatter diffraction image apparatus is used to divide a 30 × 50 μm region to 0.1 μm. 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 substrate surface at intervals of / step, and based on the measurement result, Among them, the measurement inclination angle in the range of 0 to 45 degrees was divided for each pitch of 0.25 degrees, and the frequency existing in each section was totaled.
この結果得られた各種の改質Ａｌ2Ｏ3層および従来Ａｌ2Ｏ3層の傾斜角度数分布グラフから、最高ピークが存在する傾斜角区分、および、０〜１０度の範囲内に存在する度数の合計が傾斜角度数分布グラフにおける度数全体に占める割合を求め、この値をそれぞれ表６，表７に示した。 From the gradient angle distribution graphs of the various modified Al 2 O 3 layers and the conventional Al 2 O 3 layers obtained as a result of this, the gradient angle segment in which the highest peak exists and the range of 0 to 10 degrees exist. The ratio of the total frequency to the total frequency in the inclination angle frequency distribution graph was determined, and these values are shown in Tables 6 and 7, respectively.
上記の各種の傾斜角度数分布グラフにおいて、表６にそれぞれ示される通り、本発明被覆工具の改質Ａｌ2Ｏ3層は、いずれも０〜１０度の範囲内に最高ピークが存在し、かつ、傾斜角度数分布グラフにおける度数全体に占める０〜１０度の範囲内に存在する度数の合計の割合は、４５％以上を示すのに対して、従来被覆工具の従来Ａｌ2Ｏ3層は、表７にそれぞれ示される通り、いずれも０〜１０度の範囲内に最高ピークは存在せず、しかも、０〜１０度の範囲内に存在する度数の合計の割合も高々１０％という小さな割合であって、特定方向への（０００１）面の配向性はなかった。
なお、図３は、本発明被覆工具１３の改質Ａｌ2Ｏ3層の傾斜角度数分布グラフ、図４は、従来被覆工具１の従来Ａｌ2Ｏ3層の傾斜角度数分布グラフをそれぞれ示すものである。
In each of the above-mentioned various inclination angle number distribution graphs, as shown in Table 6, each of the modified Al 2 O 3 layers of the coated tool of the present invention has a maximum peak in the range of 0 to 10 degrees, and The ratio of the total frequency existing in the range of 0 to 10 degrees in the entire frequency in the inclination angle frequency distribution graph shows 45% or more, whereas the conventional Al 2 O 3 layer of the conventional coated tool is As shown in Table 7, there is no highest peak in the range of 0 to 10 degrees, and the ratio of the total frequencies existing in the range of 0 to 10 degrees is as small as 10% at most. There was no orientation of the (0001) plane in a specific direction.
3 shows an inclination angle number distribution graph of the modified Al 2 O 3 layer of the present coated tool 13, and FIG. 4 shows an inclination angle number distribution graph of the conventional Al 2 O 3 layer of the conventional coated tool 1. Is.
次に、上記の本発明被覆工具１〜１３および比較被覆工具１〜１３の硬質被覆層の上部層を構成する改質（Ａｌ，Ｚｒ）Ｏ層および従来（Ａｌ，Ｚｒ）Ｏ層のそれぞれについて、電界放出型走査電子顕微鏡を用いて、構成原子共有格子点分布グラフをそれぞれ作成した。
すなわち、上記構成原子共有格子点分布グラフは、上記の改質（Ａｌ，Ｚｒ）Ｏ層および従来（Ａｌ，Ｚｒ）Ｏ層の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、３０×５０μｍの領域を０．１μｍ／ｓｔｅｐの間隔で、前記断面研磨面の法線に対して、前記結晶粒の結晶面である（０００１）面および（１０-１０）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、図２に示されるように、相互に隣接する結晶粒の界面で、前記構成原子のそれぞれが前記結晶粒相互間で１つの構成原子を共有する格子点（構成原子共有格子点）の分布を算出し、前記構成原子共有格子点間に構成原子を共有しない格子点がＮ個（ただし、Ｎはコランダム型六方最密晶の結晶構造上２以上の偶数となるが、分布頻度の点からＮの上限を２８とした場合、４、８、１４、２４、および２６の偶数は存在せず）存在する構成原子共有格子点形態をΣＮ＋１で現した場合、個々のΣＮ＋１がΣＮ＋１全体に占める分布割合を求めることにより作成した。
Next, each of the modified (Al, Zr) O layer and the conventional (Al, Zr) O layer constituting the upper layer of the hard coating layer of the present invention coated tools 1 to 13 and comparative coated tools 1 to 13 Using the field emission scanning electron microscope, the constituent atom shared lattice point distribution graphs were respectively prepared.
That is, the constituent atomic shared lattice point distribution graph shows a mirror of a field emission scanning electron microscope in a state where the cross sections of the modified (Al, Zr) O layer and the conventional (Al, Zr) O layer are polished surfaces. An electron beam with an acceleration voltage of 15 kV at an incident angle of 70 degrees is applied to the polished surface at an irradiation current of 1 nA to each crystal grain existing within the measurement range of the cross-sectional polished surface. Using a backscatter diffraction image apparatus, a region of 30 × 50 μm is spaced at a spacing of 0.1 μm / step with respect to the normal line of the cross-section polished surface (0001) plane and (10 − 10) Measure the tilt angle formed by the normals of the surface, and based on the measured tilt angle obtained as a result, as shown in FIG. Lattice sharing one constituent atom between the crystal grains The distribution of points (constituent atom shared lattice points) is calculated, and there are N lattice points that do not share constituent atoms between the constituent atom shared lattice points (where N is two or more on the crystal structure of the corundum hexagonal close-packed crystal) (Even if the upper limit of N is 28 from the point of distribution frequency, the even number of 4, 8, 14, 24, and 26 does not exist) When the existing constituent atom shared lattice point form is expressed as ΣN + 1 Each ΣN + 1 was created by calculating the distribution ratio of the entire ΣN + 1.
この結果得られた各種の改質（Ａｌ，Ｚｒ）Ｏ層および従来（Ａｌ，Ｚｒ）Ｏ層の構成原子共有格子点分布グラフにおいて、ΣＮ＋１全体（上記の結果からΣ３、Σ７、Σ１１、Σ１３、Σ１７、Σ１９、Σ２１、Σ２３、およびΣ２９のそれぞれの分布割合の合計）に占めるΣ３の分布割合をそれぞれ求め、この値をそれぞれ表６，表７に示した。 In the resulting atomic atom lattice distribution graph of various modified (Al, Zr) O layers and conventional (Al, Zr) O layers obtained as a result, the entire ΣN + 1 (from the above results, Σ3, Σ7, Σ11, Σ13, The distribution ratio of Σ3 in each of the distribution ratios of Σ17, Σ19, Σ21, Σ23, and Σ29) was determined, and these values are shown in Tables 6 and 7, respectively.
上記の各種の構成原子共有格子点分布グラフにおいて、表６にそれぞれ示される通り、本発明被覆工具の改質（Ａｌ，Ｚｒ）Ｏ層は、いずれもΣ３の占める分布割合が４０〜６０％である構成原子共有格子点分布グラフを示すのに対して、従来被覆工具の従来（Ａｌ，Ｚｒ）Ｏ層は、表７にそれぞれ示される通り、いずれもΣ３の分布割合が２０％以下の構成原子共有格子点分布グラフを示すものであり、Σ３対応粒界の分布割合が小さいものであった。
なお、図５は、本発明被覆工具１３の改質（Ａｌ，Ｚｒ）2Ｏ3層の構成原子共有格子点分布グラフ、図６は、従来被覆工具１の従来（Ａｌ，Ｚｒ）Ｏ層の構成原子共有格子点分布グラフをそれぞれ示すものである。
In each of the above-mentioned various constituent atomic shared lattice point distribution graphs, as shown in Table 6, each of the modified (Al, Zr) O layers of the coated tool of the present invention has a distribution ratio of 40 to 60% of Σ3. In contrast to the graph showing the distribution of the constituent atomic shared lattice points, the conventional (Al, Zr) O layer of the conventional coated tool has constituent atoms having a Σ3 distribution ratio of 20% or less as shown in Table 7. The shared lattice point distribution graph is shown, and the distribution ratio of the grain boundaries corresponding to Σ3 is small.
FIG. 5 is a graph showing the distribution of constituent atomic shared lattice points of the modified (Al, Zr) 2 O 3 layer of the present coated tool 13, and FIG. 6 is a graph of the conventional (Al, Zr) O layer of the conventional coated tool 1. The constituent atom shared lattice point distribution graphs are respectively shown.
また、本発明被覆工具１〜１３および従来被覆工具１〜１３の硬質被覆層の各構成層の厚さを、走査型電子顕微鏡を用いて測定（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。 Moreover, when the thickness of each structural layer of the hard coating layer of this invention coated tool 1-13 and the conventional coated tool 1-13 was measured using the scanning electron microscope (longitudinal section measurement), all were target layer thickness. The average layer thickness (average value of 5-point measurement) was substantially the same.
つぎに、上記の本発明被覆工具１〜１３および従来被覆工具１〜１３について、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、
被削材：ＪＩＳ・Ｓ２０Ｃの丸棒、
切削速度： ４５５ ｍ／ｍｉｎ、
切り込み： ２．７ ｍｍ、
送り： ０．８ ｍｍ／ｒｅｖ、
切削時間： １０ 分、
の条件（切削条件Ａという）での炭素鋼の乾式高速高送り切削試験（通常の切削速度および送りは、それぞれ、３５０ｍ／ｍｉｎ、０．３ｍｍ／ｒｅｖ）、
被削材：ＪＩＳ・ＳＣＭ４２０の丸棒、
切削速度： ３１０ ｍ／ｍｉｎ、
切り込み： ２ ｍｍ、
送り： ０．３５ ｍｍ／ｒｅｖ、
切削時間： ５ 分、
の条件（切削条件Ｂという）での合金鋼の乾式高速高切り込み切削試験（通常の切削速度および切り込みは、それぞれ、２５０ｍ／ｍｉｎ、１．５ｍｍ）、
被削材：ＪＩＳ・ＦＣ３００の丸棒、
切削速度： ５４０ ｍ／ｍｉｎ、
切り込み： ５．７ ｍｍ、
送り： ０．４ ｍｍ／ｒｅｖ、
切削時間： ５ 分、
の条件（切削条件Ｃという）での鋳鉄の乾式高速高切り込み切削試験（通常の切削速度および切り込みは、それぞれ、４００ｍ／ｍｉｎ、４ｍｍ）、
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８に示した。
Next, for the present invention coated tools 1-13 and the conventional coated tools 1-13, both are screwed with a fixing jig to the tip of the tool steel tool,
Work material: JIS / S20C round bar,
Cutting speed: 455 m / min,
Incision: 2.7 mm,
Feed: 0.8 mm / rev,
Cutting time: 10 minutes,
Dry high-speed high-feed cutting test of carbon steel under the following conditions (referred to as cutting condition A) (normal cutting speed and feed are 350 m / min and 0.3 mm / rev, respectively)
Work material: JIS / SCM420 round bar,
Cutting speed: 310 m / min,
Incision: 2 mm,
Feed: 0.35 mm / rev,
Cutting time: 5 minutes,
Dry high-speed high-cut cutting test of alloy steel under the conditions (cutting condition B) (normal cutting speed and cutting are 250 m / min and 1.5 mm, respectively)
Work material: JIS / FC300 round bar,
Cutting speed: 540 m / min,
Cutting depth: 5.7 mm,
Feed: 0.4 mm / rev,
Cutting time: 5 minutes,
A dry high-speed, high-cut cutting test of cast iron under the conditions (referred to as cutting conditions C) (normal cutting speed and cutting are 400 m / min and 4 mm, respectively),
In each cutting test, the flank wear width of the cutting edge was measured. The measurement results are shown in Table 8.
表６〜８に示される結果から、本発明被覆工具１〜１３は、改質Ａｌ2Ｏ3層からなる中間層の上に、Σ３対応粒界の分布割合が高い改質（Ａｌ，Ｚｒ）Ｏ層からなる上部層が形成されていることによって、高熱発生を伴い、かつ、切刃部に高負荷が作用する高速重切削でも、硬質被覆層がすぐれた高温硬さおよび耐熱性に加えて、一段とすぐれた高温強度と耐熱塑性変形性を有し、すぐれた耐チッピング性と耐摩耗性を示すのに対して、従来Ａｌ2Ｏ3層の上に、Σ３対応粒界の分布割合が少ない従来（Ａｌ，Ｚｒ）Ｏ層が形成された従来被覆工具は、高速重切削加工では、硬質被覆層の特に高温強度、耐熱塑性変形性が不十分であるために、硬質被覆層にチッピングが発生し、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 6 to 8, the coated tools 1 to 13 of the present invention are modified (Al, Zr) with a high distribution ratio of Σ3-compatible grain boundaries on the intermediate layer composed of the modified Al 2 O 3 layer. In addition to high-temperature hardness and heat resistance, the hard coating layer is excellent even in high-speed heavy cutting with high heat generation and high load acting on the cutting edge due to the formation of the upper layer composed of the O layer. In addition to having excellent high-temperature strength and heat-resistant plastic deformation, and excellent chipping resistance and wear resistance, the distribution ratio of Σ3-compatible grain boundaries is small on the conventional Al 2 O 3 layer. Conventional coated tools with a conventional (Al, Zr) O layer have chipping in the hard coating layer due to insufficient high temperature strength and heat-resistant plastic deformation of the hard coating layer in high speed heavy cutting. It is clear that 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、各種の鋼や鋳鉄などの通常の条件での連続切削加工や断続切削加工は勿論のこと、特に高い高温強度と耐熱塑性変形性が要求される高送り、高切り込み等の高速重切削加工でも硬質被覆層がすぐれた耐チッピング性と耐摩耗性を示し、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 is not only required for continuous cutting and interrupted cutting under normal conditions such as various steels and cast irons, but also requires high high-temperature strength and heat-resistant plastic deformation. Even in high-speed heavy cutting such as feed and high cutting, the hard coating layer exhibits excellent chipping resistance and wear resistance, and exhibits excellent cutting performance over a long period of time. It can fully satisfy the labor-saving and energy-saving of cutting and cost reduction.
Claims (1)
（ａ）下部層は、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層以上からなり、かつ、３〜２０μｍの全体平均層厚を有するＴｉ化合物層、
（ｂ）中間層は、化学蒸着した状態でα型の結晶構造を有し、かつ、１〜３μｍの平均層厚を有するα型酸化アルミニウム層であって、
該中間層について、電界放出型走査電子顕微鏡を用い、断面研磨面の測定範囲内に存在する六方晶結晶格子を有する結晶粒個々に電子線を照射して、基体表面の法線に対して、前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、前記測定傾斜角のうち、０〜４５度の範囲内にある測定傾斜角を０．２５度のピッチ毎に区分すると共に、各区分内に存在する度数を集計してなる傾斜角度数分布グラフで現した場合、０〜１０度の範囲内の傾斜角区分に最高ピークが存在すると共に、前記０〜１０度の範囲内に存在する度数の合計が、傾斜角度数分布グラフにおける度数全体の４５％以上の割合を占める傾斜角度数分布グラフを示すα型酸化アルミニウム層、
（ｃ）上部層は、化学蒸着した状態でα型の結晶構造を有し、かつ、１〜１４μｍの平均層厚を有し、さらに、α型酸化アルミニウム相の素地に酸化ジルコニウム相が均一に分散分布した均一混合組織層であって、しかも、該均一混合組織層におけるアルミニウムとの合量に占めるジルコニウムの含有割合は０．００３〜０．２（但し、原子比）であり、
該上部層について、電界放出型走査電子顕微鏡を用い、断面研磨面の測定範囲内に存在する六方晶結晶格子を有する結晶粒個々に電子線を照射して、前記断面研磨面の法線に対して、前記結晶粒の結晶面である（０００１）面および（１０−１０）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、相互に隣接する結晶粒の界面で、前記構成原子のそれぞれが前記結晶粒相互間で１つの構成原子を共有する格子点（構成原子共有格子点）の分布を算出し、前記構成原子共有格子点間に構成原子を共有しない格子点がＮ個（ただし、Ｎはコランダム型六方最密晶の結晶構造上２以上の偶数となるが、分布頻度の点からＮの上限を２８とした）存在する構成原子共有格子点形態をΣＮ＋１で表した場合、個々のΣＮ＋１がΣＮ＋１全体に占める分布割合を示す構成原子共有格子点分布グラフにおいて、Σ３に最高ピークが存在し、かつ前記Σ３のΣＮ＋１全体に占める分布割合が４０〜６０％である構成原子共有格子点分布グラフを示すα型酸化アルミニウム相と酸化ジルコニウム相の均一混合組織層、
以上（ａ）〜（ｃ）で構成された硬質被覆層を蒸着形成してなる、硬質被覆層が高速重切削加工ですぐれた耐チッピング性、耐摩耗性を発揮する表面被覆切削工具。 In a surface-coated cutting tool in which a hard coating layer composed of a lower layer, an intermediate layer, and an upper layer is vapor-deposited on the surface of a tool base composed of a tungsten carbide-based cemented carbide or a titanium carbonitride-based cermet,
(A) The lower layer is composed of one or more of a Ti carbide layer, a nitride layer, a carbonitride layer, a carbonate layer, and a carbonitride layer, and has a total thickness of 3 to 20 μm. A Ti compound layer having an average layer thickness;
(B) The intermediate layer is an α-type aluminum oxide layer having an α-type crystal structure in a chemical vapor deposited state and having an average layer thickness of 1 to 3 μm,
For the intermediate layer, using a field emission scanning electron microscope, each crystal grain having a hexagonal crystal lattice existing within the measurement range of the cross-sectional polished surface is irradiated with an electron beam, The inclination angle formed by the normal line of the (0001) plane, which is the crystal plane of the crystal grain, is measured, and the measurement inclination angle within the range of 0 to 45 degrees out of the measurement inclination angles is set to a pitch of 0.25 degrees. In addition, the maximum peak exists in the inclination angle division within the range of 0 to 10 degrees, and the above 0 to 10 are expressed in the inclination angle number distribution graph obtained by adding up the frequencies existing in each division. An α-type aluminum oxide layer showing a tilt angle number distribution graph in which the total number of frequencies existing in the range of degrees occupies a ratio of 45% or more of the total frequency in the tilt angle number distribution graph,
(C) The upper layer has an α-type crystal structure in the state of chemical vapor deposition, has an average layer thickness of 1 to 14 μm, and further has a uniform zirconium oxide phase on the base of the α-type aluminum oxide phase. The uniformly mixed structure layer is distributed and distributed, and the content ratio of zirconium in the total amount of aluminum in the uniform mixed structure layer is 0.003 to 0.2 (however, atomic ratio),
For the upper layer, using a field emission scanning electron microscope, each crystal grain having a hexagonal crystal lattice existing within the measurement range of the cross-sectional polished surface is irradiated with an electron beam to Then, the inclination angles formed by the normal lines of the (0001) plane and the (10-10) plane, which are the crystal planes of the crystal grains, are measured, and the crystal grains adjacent to each other are measured based on the measured inclination angles. The distribution of lattice points (constituent atom shared lattice points) in which each of the constituent atoms shares one constituent atom between the crystal grains is calculated at the interface, and the constituent atoms are shared between the constituent atom shared lattice points. There are N lattice points (N is an even number of 2 or more on the crystal structure of the corundum hexagonal close-packed crystal, but the upper limit of N is 28 in terms of distribution frequency). Is represented by ΣN + 1, each ΣN + 1 is Σ In the constituent atom shared lattice point distribution graph showing the distribution ratio in the entire +1, the constituent atom shared lattice point distribution graph in which the highest peak exists in Σ3 and the distribution ratio in the entire ΣN + 1 of the Σ3 is 40 to 60%. A uniform mixed structure layer of α-type aluminum oxide phase and zirconium oxide phase shown,
A surface-coated cutting tool in which a hard coating layer composed of the above (a) to (c) is formed by vapor deposition, and the hard coating layer exhibits excellent chipping resistance and wear resistance in high-speed heavy cutting.
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| JP4232333B2 (en) * | 2000-09-18 | 2009-03-04 | 三菱マテリアル株式会社 | Surface coated cemented carbide cutting tool with excellent surface lubricity against chips |
| JP4019243B2 (en) * | 2000-09-21 | 2007-12-12 | 三菱マテリアル株式会社 | Surface coated cemented carbide cutting tool with excellent surface lubricity against chips |
| JP4281262B2 (en) * | 2001-06-11 | 2009-06-17 | 三菱マテリアル株式会社 | Cutting tool made of surface-coated cemented carbide with high viscosity and excellent surface lubricity against cutting chips in high-speed cutting of difficult-to-cut materials where cutting chips easily adhere to the cutting edge surface |
| JP4591752B2 (en) * | 2004-02-05 | 2010-12-01 | 三菱マテリアル株式会社 | Surface coated cermet cutting tool with excellent chipping resistance with hard coating layer |
| JP4645983B2 (en) * | 2005-04-12 | 2011-03-09 | 三菱マテリアル株式会社 | Surface coated cermet cutting tool whose hard coating layer exhibits excellent chipping resistance in high-speed intermittent cutting |
| JP4984513B2 (en) * | 2005-12-14 | 2012-07-25 | 三菱マテリアル株式会社 | Manufacturing method of surface-coated cermet cutting tool that exhibits excellent chipping resistance in high-speed cutting of difficult-to-cut materials |
| JP4863053B2 (en) * | 2005-12-20 | 2012-01-25 | 三菱マテリアル株式会社 | Manufacturing method of surface-coated cermet cutting tool that exhibits excellent chipping resistance in high-speed cutting of difficult-to-cut materials |
| JP4822120B2 (en) * | 2006-07-21 | 2011-11-24 | 三菱マテリアル株式会社 | Surface-coated cutting tool whose hard coating layer exhibits excellent chipping resistance in high-speed heavy cutting |
| JP4836202B2 (en) * | 2007-07-20 | 2011-12-14 | 日立ツール株式会社 | Coated tool |
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