JP5838789B2 - Surface coated cutting tool whose hard coating layer exhibits excellent chipping resistance in high-speed intermittent cutting - Google Patents
Surface coated cutting tool whose hard coating layer exhibits excellent chipping resistance in high-speed intermittent cutting Download PDFInfo
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この発明は、各種の鋼や鋳鉄などの切削加工を、高速で、かつ、切刃に断続的・衝撃的負荷が作用する断続切削条件で行った場合でも、硬質被覆層がすぐれた耐チッピング性、耐剥離性を発揮し、長期に亘ってすぐれた耐摩耗性を示す表面被覆切削工具（以下、被覆工具という）に関するものである。 The present invention provides excellent chipping resistance even when cutting various steels and cast irons at high speeds and under intermittent cutting conditions in which intermittent and impact loads are applied to the cutting edge. The present invention relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) that exhibits peeling resistance and exhibits excellent wear resistance over a long period of time.
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、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１層または２層以上からなるＴｉ化合物層、
（ｂ）上部層が、化学蒸着した状態でα型の結晶構造を有する酸化アルミニウム層（以下、Ａｌ２Ｏ３層で示す）、
以上（ａ）および（ｂ）で構成された硬質被覆層を蒸着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) The lower layer is a Ti carbide (hereinafter referred to as TiC) layer, a nitride (hereinafter also referred to as TiN) layer, a carbonitride (hereinafter referred to as TiCN) layer, a carbon oxide (hereinafter referred to as TiCO). And a Ti compound layer composed of one or more of a carbonitride oxide (hereinafter referred to as TiCNO) layer,
(B) an aluminum oxide layer (hereinafter referred to as an Al 2 O 3 layer) having an α-type crystal structure in a state where the upper layer is chemically vapor-deposited
A coated tool formed by vapor-depositing the hard coating layer constituted by (a) and (b) is known.
しかし、上記従来の被覆工具は、例えば各種の鋼や鋳鉄などの連続切削や断続切削では優れた耐摩耗性を発揮するが、これを、高速断続切削に用いた場合には、被覆層の剥離やチッピングが発生しやすく、工具寿命が短命になるという問題点があった。
そこで、被覆層の剥離、チッピングを抑制するために、上部層あるいは下部層に改良を加えた各種の被覆工具が提案されている。
However, the above conventional coated tools exhibit excellent wear resistance in continuous cutting and intermittent cutting of various steels and cast irons, for example, but when this is used for high-speed intermittent cutting, the coating layer is peeled off. And chipping are likely to occur, and the tool life is short.
Accordingly, various types of coating tools have been proposed in which the upper layer or the lower layer is improved in order to suppress peeling and chipping of the coating layer.
例えば、上部層の改善に関するものとしては、例えば、特許文献１に、上部層を構成するＡｌ２Ｏ３層を、Ｘ線回折における（０３０）面のピーク強度Ｉ（０３０）が、（１０４）面のピーク強度Ｉ（１０４）よりも大であるＡｌ２Ｏ３層で構成することによって、耐摩耗性、耐欠損性の向上を図った被覆工具が提案されている。
また、特許文献２には、上部層を構成するＡｌ２Ｏ３層を、それぞれ下位層と上位層からなる２層構造とし、さらに電界放出型走査電子顕微鏡を用い、（０００１）面の法線がなす傾斜角を測定し、上位層については０〜４５度、下位層については４５〜９０度の範囲内で傾斜角度数分布グラフを作成した場合、前記上位層は、０〜１５度の範囲内の傾斜角区分に最高ピークが存在し、該傾斜角区分内の度数合計が５０％以上の割合を占め、一方、前記下位層は、７５〜９０度の範囲内の傾斜角区分に最高ピークが存在し、該傾斜角区分内の度数合計が５０％以上の割合を占める２層構造とすることにより、耐チッピング性を改善した被覆工具が提案されている。
For example, as for the improvement of the upper layer, for example, in Patent Document 1, the Al 2 O 3 layer constituting the upper layer has an (030) plane peak intensity I (030) in X-ray diffraction of (104). There has been proposed a coated tool which is composed of an Al 2 O 3 layer which is larger than the peak intensity I (104) of the surface, thereby improving wear resistance and fracture resistance.
In Patent Document 2, the Al 2 O 3 layer constituting the upper layer has a two- layer structure composed of a lower layer and an upper layer, respectively, and a normal line on the (0001) plane using a field emission scanning electron microscope. When the inclination angle number distribution graph is created in the range of 0 to 45 degrees for the upper layer and 45 to 90 degrees for the lower layer, the upper layer is in the range of 0 to 15 degrees. The highest peak exists in the inclination angle section, and the total frequency in the inclination angle section occupies a ratio of 50% or more, while the lower layer has the highest peak in the inclination angle section in the range of 75 to 90 degrees. There has been proposed a coated tool with improved chipping resistance by adopting a two-layer structure in which the total frequency in the inclined angle section occupies a ratio of 50% or more.
特許文献３、４には、微量のＴｉを含有するＴｉ含有Ａｌ２Ｏ３層を上部層として形成することにより、耐チッピング性、耐欠損性を向上させた被覆工具が提案されている。 Patent Documents 3 and 4 propose a coated tool in which chipping resistance and fracture resistance are improved by forming a Ti-containing Al 2 O 3 layer containing a small amount of Ti as an upper layer.
一方、下部層の改善に関するものとしては、例えば、特許文献５に、下部層のＴｉＣＮ層の粒子幅を小さくし、かつ、硬質被覆層の表面を適正な表面粗さとすることによって、耐衝撃性、耐欠損性、耐摩耗性の向上を図った被覆工具が提案されており、また、特許文献６には、Ｔｉ化合物層として少なくとも膜厚が２〜１８μｍのＴｉＣＮＯ層を形成し、該ＴｉＣＮＯ層のＸ線回折ピーク最強度面が、（４２２）面または（３１１）面であり、該ＴｉＣＮＯ層中の酸素量を０．０５〜３．０２質量％とし、さらに、ＴｉＣＮ結晶粒幅を小さくすることによって、硬質被覆層表面の結晶粒粗大化、局所的突起の形成を防止するとともに、ＴｉＣＮＯ自体の強度の向上、上部層との密着性向上を図った被覆工具が提案されている。 On the other hand, as for the improvement of the lower layer, for example, in Patent Document 5, the impact resistance is reduced by reducing the particle width of the TiCN layer of the lower layer and making the surface of the hard coating layer have an appropriate surface roughness. In addition, Patent Document 6 proposes a TiCNO layer having a film thickness of at least 2 to 18 μm formed as a Ti compound layer, and a TiCNO layer is proposed. The maximum intensity surface of the X-ray diffraction peak is (422) plane or (311) plane, the amount of oxygen in the TiCNO layer is 0.05 to 3.02 mass%, and the TiCN crystal grain width is further reduced. Thus, a coated tool has been proposed which prevents the coarsening of the surface of the hard coating layer and the formation of local protrusions, and improves the strength of TiCNO itself and the adhesion with the upper layer.
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すると共に、断続切削等で切刃に高負荷が作用する傾向にあるが、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、特にこれを高速断続切削条件で用いた場合には、硬質被覆層を構成するＴｉ化合物層からなる下部層とＡｌ２Ｏ３層あるいはＴｉ含有Ａｌ２Ｏ３層からなる上部層の密着強度が不十分となり、上部層と下部層間での剥離、チッピング等の異常損傷の発生により、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 dramatically improved, while on the other hand, there is a strong demand for labor saving and energy saving and further cost reduction for cutting work. However, in the above-mentioned conventional 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. When used under high-speed interrupted cutting conditions, the adhesion strength between the lower layer composed of the Ti compound layer constituting the hard coating layer and the upper layer composed of the Al 2 O 3 layer or the Ti-containing Al 2 O 3 layer becomes insufficient. At present, the service life is reached in a relatively short time due to occurrence of abnormal damage such as peeling and chipping between the upper layer and the lower layer.
そこで、本発明者等は、上述のような観点から、下部層と上部層の密着性を改善し、もって、剥離、チッピング等の異常損傷の発生を防止するとともに、工具寿命の長寿命化を図るべく鋭意研究を行った結果、
Ｔｉ化合物層からなる下部層と、Ｔｉ含有Ａｌ２Ｏ３層からなる中間層と、Ａｌ２Ｏ３層からなる上部層とを被覆形成した被覆工具において、下部層の最表面層直上のＴｉ含有Ａｌ２Ｏ３結晶粒の配向性と粒径を制御することで、下部層と中間層、また、中間層と上部層の密着性を向上させ得るとともに、さらに、上部層全体のＡｌ２Ｏ３結晶粒についての配向性と結晶粒径を制御することで、上部層全体の高温硬さと高温強度を維持することができるため、切刃に断続的・衝撃的負荷が作用する高速断続切削に用いた場合でも、下部層、中間層および上部層からなる硬質被覆層間でのチッピング、剥離等の異常損傷の発生が抑え、長期の使用にわたってすぐれた切削性能を発揮する被覆工具を得られることを見出したのである。
Therefore, the inventors have improved the adhesion between the lower layer and the upper layer from the above viewpoint, thereby preventing the occurrence of abnormal damage such as peeling and chipping, and extending the tool life. As a result of earnest research to try,
In a coated tool formed by coating a lower layer made of a Ti compound layer, an intermediate layer made of a Ti-containing Al 2 O 3 layer, and an upper layer made of an Al 2 O 3 layer, the Ti content immediately above the outermost surface layer of the lower layer By controlling the orientation and grain size of the Al 2 O 3 crystal grains, the adhesion between the lower layer and the intermediate layer and between the intermediate layer and the upper layer can be improved, and further, the Al 2 O 3 of the entire upper layer can be improved. By controlling the orientation and grain size of the crystal grains, it is possible to maintain the high-temperature hardness and high-temperature strength of the entire upper layer, which is used for high-speed intermittent cutting where intermittent and impact loads are applied to the cutting edge. Even when there is a problem, it has been found that the occurrence of abnormal damage such as chipping and peeling between the hard coating layers consisting of the lower layer, intermediate layer and upper layer can be suppressed, and a coated tool that exhibits excellent cutting performance over a long period of use can be obtained. It was.
この発明は、上記知見に基づいてなされたものであって、
「（１） 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）下部層が、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の合計平均層厚を有するＴｉ化合物層、
（ｂ）中間層が０．５〜２．０μｍの平均層厚およびα型の結晶構造を有するＴｉ含有α型Ａｌ２Ｏ３層（但し、原子比で、Ｔｉ／（Ａｌ＋Ｔｉ＋Ｏ）の比の値は０．０００１〜０．００１）、
（ｃ）上部層が、１〜１５μｍの平均層厚を有し、α型の結晶構造を有するＡｌ２Ｏ３層、
以上（ａ）〜（ｃ）からなる硬質被覆層が形成された表面被覆切削工具において、
（ｄ）上記中間層を構成する結晶粒(以下、「Ｔｉ含有Ａｌ２Ｏ３結晶粒」という)について、電子線後方散乱回折装置を用いて、その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、前記工具基体の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た場合、その傾斜角が０〜１０度であるＴｉ含有Ａｌ２Ｏ３結晶粒（以下、「（０００１）配向Ｔｉ含有Ａｌ２Ｏ３結晶粒」という）の占める面積割合は、前記測定範囲の面積の１５〜３５面積％であり、かつ、該（０００１）配向Ｔｉ含有Ａｌ２Ｏ３結晶粒の横方向平均粒径は０．３〜１．０μｍであって、膜厚方向に成長した柱状結晶組織を有し、
（ｅ）また、上記中間層のＴｉ含有Ａｌ２Ｏ３結晶粒について、電子線後方散乱回折装置を用いて、その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、前記工具基体の表面の法線に対して、前記結晶粒の結晶面である（１１−２０）面の法線がなす傾斜角を測定した場合、その傾斜角が０〜１０度であるＴｉ含有Ａｌ２Ｏ３結晶粒（以下、「（１１−２０）配向Ｔｉ含有Ａｌ２Ｏ３結晶粒」という）の占める面積割合は、前記測定範囲の面積の５５〜７５面積％であり、かつ、該（１１−２０）配向Ｔｉ含有Ａｌ２Ｏ３結晶粒の横方向平均粒径は１．０〜２．０μｍであって、膜厚方向に成長した柱状結晶組織を有し、
（ｆ）上記上部層のＡｌ２Ｏ３結晶粒について、電子線後方散乱回折装置を用いて、その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、前記工具基体の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た場合、その傾斜角が０〜１０度であるＡｌ２Ｏ３結晶粒の占める面積割合は、前記測定範囲の面積の７０面積％以上であり、かつ、上部層のＡｌ２Ｏ３結晶粒の横方向平均粒径は１．０〜２．０μｍであって、膜厚方向に成長した柱状結晶組織を有する、
ことを特徴とする表面被覆切削工具。
（２）上記下部層の最表面層が、少なくとも５００ｎｍ以上の層厚を有するＴｉ炭窒化物層からなり、該Ｔｉ炭窒化物層と上部層との界面から、該Ｔｉ炭窒化物層の層厚方向に５００ｎｍまでの深さ領域にのみ酸素が含有されており、かつ、該深さ領域に含有される平均酸素含有量は、該深さ領域に含有されるＴｉ，Ｃ，Ｎ，Ｏの合計含有量の０．５〜３原子％であることを特徴とする請求項１に記載の表面被覆切削工具。」
に特徴を有するものである。
This invention has been made based on the above findings,
“(1) On the surface of a tool base made of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet,
(A) The lower layer is composed of one or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer and carbonitride oxide layer, and a total average of 3 to 20 μm A Ti compound layer having a layer thickness,
(B) the ratio of the Ti-containing α-type the Al 2 O 3 layer which intermediate layer has an average layer thickness and α-type crystal structure of 0.5 to 2.0 [mu] m (where, in terms of atomic ratio, Ti / (Al + Ti + O) Is 0.0001 to 0.001),
(C) an Al 2 O 3 layer in which the upper layer has an average layer thickness of 1 to 15 μm and has an α- type crystal structure;
In the surface-coated cutting tool in which the hard coating layer composed of (a) to (c) is formed ,
(D) The hexagonal crystal grains that constitute the intermediate layer (hereinafter referred to as “Ti-containing Al 2 O 3 crystal grains”) exist within the measurement range of the cross-section polished surface using an electron beam backscattering diffractometer. Each crystal grain having a crystal lattice was irradiated with an electron beam, and an inclination angle formed by a normal line of the (0001) plane which is a crystal plane of the crystal grain was measured with respect to a normal line of the surface of the tool base. In this case, the area ratio occupied by Ti-containing Al 2 O 3 crystal grains (hereinafter referred to as “(0001) oriented Ti-containing Al 2 O 3 crystal grains”) having an inclination angle of 0 to 10 degrees is the area of the measurement range. And the (0001) -oriented Ti-containing Al 2 O 3 crystal grains have a lateral average grain size of 0.3 to 1.0 μm, and are columnar crystals grown in the film thickness direction. Have an organization,
(E) Further, with respect to the Ti-containing Al 2 O 3 crystal grains of the intermediate layer, each crystal grain having a hexagonal crystal lattice existing within the measurement range of the cross-sectional polished surface is measured using an electron beam backscattering diffractometer. When the tilt angle formed by the normal of the (11-20) plane, which is the crystal plane of the crystal grain, is measured with respect to the normal of the surface of the tool base by irradiating an electron beam, the tilt angle is 0. The area ratio occupied by Ti-containing Al 2 O 3 crystal grains (hereinafter referred to as “(11-20) -oriented Ti-containing Al 2 O 3 crystal grains”) of −10 degrees is 55 to 75 area of the area of the measurement range. And the (11-20) oriented Ti-containing Al 2 O 3 crystal grains have an average lateral grain size of 1.0 to 2.0 μm and a columnar crystal structure grown in the film thickness direction. And
(F) The upper layer Al 2 O 3 crystal grains are irradiated with an electron beam on each crystal grain having a hexagonal crystal lattice existing within the measurement range of the cross-section polished surface using an electron beam backscattering diffractometer. Then, when 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 surface of the tool base, the inclination angle is 0 to 10 degrees. The area ratio occupied by 2 O 3 crystal grains is 70 area% or more of the area of the measurement range, and the average average grain size of Al 2 O 3 crystal grains in the upper layer is 1.0 to 2.0 μm. And having a columnar crystal structure grown in the film thickness direction,
A surface-coated cutting tool characterized by that.
(2) The outermost surface layer of the lower layer is made of a Ti carbonitride layer having a layer thickness of at least 500 nm, and the Ti carbonitride layer is formed from the interface between the Ti carbonitride layer and the upper layer. Oxygen is contained only in the depth region up to 500 nm in the thickness direction, and the average oxygen content contained in the depth region is that of Ti, C, N, O contained in the depth region. The surface-coated cutting tool according to claim 1, wherein the content is 0.5 to 3 atomic% of the total content. "
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。
下部層のＴｉ化合物層：
Ｔｉ化合物層（例えば、ＴｉＣ層、ＴｉＮ層、ＴｉＣＮ層、ＴｉＣＯ層およびＴｉＣＮＯ層）は、基本的には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が高温強度を具備するようになるほか、工具基体、Ａｌ２Ｏ３層のいずれにも密着し、硬質被覆層の工具基体に対する密着性を維持する作用を有するが、その合計平均層厚が３μｍ未満では、前記作用を十分に発揮させることができず、一方その合計平均層厚が２０μｍを越えると、特に高熱発生を伴う高速重切削・高速断続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、その合計平均層厚を３〜２０μｍと定めた。
Hereinafter, the constituent layers of the hard coating layer of the coated tool of the present invention will be described in detail.
Lower Ti compound layer:
Ti compound layers (eg, TiC layer, TiN layer, TiCN layer, TiCO layer and TiCNO layer) basically exist as the lower layer of Al 2 O 3 layer, and are hard-coated by their excellent high-temperature strength. In addition to the high temperature strength of the layer, the layer adheres to both the tool substrate and the Al 2 O 3 layer, and maintains the adhesion of the hard coating layer to the tool substrate, but the total average layer thickness is If the thickness is less than 3 μm, the above-mentioned effect cannot be sufficiently exerted. On the other hand, if the total average layer thickness exceeds 20 μm, it becomes easy to cause thermoplastic deformation particularly in high-speed heavy cutting and high-speed intermittent cutting with high heat generation. Since it causes uneven wear, the total average layer thickness was determined to be 3 to 20 μm.
下部層の最表面：
この発明において、下部層上に中間層を形成するに先立って、例えば、下部層の最表面に以下のような処理を施すことにより、中間層のＴｉ含有α型Ａｌ２Ｏ３に所定の配向性および横方向平均粒径を付与することができる。
即ち、まず、通常の化学蒸着装置を使用して、ＴｉＣ層、ＴｉＮ層、ＴｉＣＮ層、ＴｉＣＯ層およびＴｉＣＮＯ層のうちの１層または２層以上からなる種々のＴｉ化合物層を蒸着形成（なお、ＴｉＣＮ層のみを蒸着形成することも勿論可能である）した後、同じく通常の化学蒸着装置を使用して、
反応ガス組成（容量％）：ＴｉＣｌ４ ２．５〜１０％、ＣＨ３ＣＮ ０．５〜１．０％、Ｎ２ ４０〜６０％、残部Ｈ２、
反応雰囲気温度：８００〜９００℃、
反応雰囲気圧力：６〜１０ｋＰａ、
の条件で化学蒸着して、下部層の最表面層として、例えば、酸素を含有するＴｉＣＮ（以下、酸素含有ＴｉＣＮという）層を形成する。
この際、所定層厚を得るに必要とされる蒸着時間終了前の５分〜３０分の間は、全反応ガス量に対して１〜５容量％となるようにＣＯガスを添加して化学蒸着を行うことにより、層厚方向に５００ｎｍまでの深さ領域にのみ０．５〜３原子％の酸素を含有する酸素含有ＴｉＣＮ層を蒸着形成する。
The outermost surface of the lower layer:
In the present invention, prior to the formation of the intermediate layer on the lower layer, for example, the following treatment is performed on the outermost surface of the lower layer so that the Ti-containing α-type Al 2 O 3 of the intermediate layer has a predetermined orientation. And lateral average particle size can be imparted.
That is, first, using a normal chemical vapor deposition apparatus, various Ti compound layers consisting of one or more of TiC layer, TiN layer, TiCN layer, TiCO layer and TiCNO layer are formed by vapor deposition (in addition, (It is of course possible to vapor-deposit only the TiCN layer), and then using a normal chemical vapor deposition apparatus,
Reaction gas composition (volume%): TiCl 4 2.5 to 10%, CH 3 CN 0.5 to 1.0%, N 2 40 to 60%, balance H 2 ,
Reaction atmosphere temperature: 800 to 900 ° C.
Reaction atmosphere pressure: 6 to 10 kPa,
For example, a TiCN layer containing oxygen (hereinafter referred to as oxygen-containing TiCN) layer is formed as the outermost surface layer of the lower layer.
At this time, for 5 to 30 minutes before the end of the deposition time required to obtain a predetermined layer thickness, the chemical gas is added by adding CO gas so as to be 1 to 5% by volume with respect to the total reaction gas amount. By performing vapor deposition, an oxygen-containing TiCN layer containing 0.5 to 3 atomic% of oxygen is vapor-deposited only in the depth region up to 500 nm in the layer thickness direction.
酸素含有ＴｉＣＮ層からなる上記下部層の最表面層は、例えば、その上に、本発明で規定する配向性および横方向平均粒径を有する中間層を形成するためには、少なくとも５００ｎｍ以上の層厚として形成するとともに、さらに、該酸素含有ＴｉＣＮ層と中間層との界面から、該酸素含有ＴｉＣＮ層の層厚方向に５００ｎｍまでの深さ領域にのみ、０．５〜３原子％の酸素を含有させ、５００ｎｍを超える深さ領域には酸素を含有させていない酸素含有ＴｉＣＮ層で構成することが望ましい。
ここで、酸素含有ＴｉＣＮ層の５００ｎｍまでの深さ領域における平均酸素含有量を上記のように限定したのは、膜の深さ方向に５００ｎｍより深い領域において酸素が含有されていると、ＴｉＣＮ最表面の組織形態が柱状組織から粒状組織に変化するとともに、中間層のＴｉ含有Ａｌ２Ｏ３結晶粒の配向性、横方向平均粒径を所望のものとできなくなるためである。
ただ、深さ領域５００ｎｍまでの平均酸素含有量が０．５原子％未満では、上部層と下部層ＴｉＣＮの付着強度の向上を望むことはできないばかりか、中間層のＴｉ含有Ａｌ２Ｏ３結晶粒の配向性、横方向平均粒径を満足させることはできず、一方、該深さ領域における平均酸素含有量が３原子％を超えると、中間層のＴｉ含有Ａ
ｌ２Ｏ３において、（０００１）配向Ａｌ２Ｏ３結晶粒の占める面積割合が少なくなり、上部層の高温強度が低下するからである。
ここで、平均酸素含有量は、下部層の最表面層を構成する上記ＴｉＣＮ層と上部層との界面から、該ＴｉＣＮ層の層厚方向に５００ｎｍまでの深さ領域におけるチタン（Ｔｉ），炭素（Ｃ），窒素（Ｎ）及び酸素（Ｏ）の合計含有量に占める酸素（Ｏ）含有量を原子％（＝Ｏ／（Ｔｉ＋Ｃ＋Ｎ＋Ｏ）×１００）で表したものをいう。
The outermost surface layer of the lower layer made of the oxygen-containing TiCN layer is, for example, a layer of at least 500 nm or more in order to form an intermediate layer having an orientation and a lateral average particle size defined in the present invention on it. In addition, the oxygen-containing TiCN layer and the intermediate layer are formed with a thickness of 0.5 to 3 atomic% only in the depth region up to 500 nm in the thickness direction of the oxygen-containing TiCN layer from the interface between the oxygen-containing TiCN layer and the intermediate layer. It is desirable to include an oxygen-containing TiCN layer that does not contain oxygen in the depth region exceeding 500 nm.
Here, the average oxygen content in the depth region up to 500 nm of the oxygen-containing TiCN layer is limited as described above because when oxygen is contained in a region deeper than 500 nm in the depth direction of the film, This is because the surface structure changes from a columnar structure to a granular structure, and the orientation and lateral average particle diameter of the Ti-containing Al 2 O 3 crystal grains in the intermediate layer cannot be made desired.
However, if the average oxygen content up to a depth region of 500 nm is less than 0.5 atomic%, it is not only possible to improve the adhesion strength between the upper layer and the lower layer TiCN, but also the Ti-containing Al 2 O 3 crystal in the intermediate layer. The grain orientation and the transverse average particle diameter cannot be satisfied. On the other hand, if the average oxygen content in the depth region exceeds 3 atomic%, the Ti-containing A in the intermediate layer
This is because in l 2 O 3 , the area ratio occupied by (0001) -oriented Al 2 O 3 crystal grains decreases, and the high-temperature strength of the upper layer decreases.
Here, the average oxygen content is determined from titanium (Ti) and carbon in a depth region up to 500 nm in the layer thickness direction of the TiCN layer from the interface between the TiCN layer and the upper layer constituting the outermost surface layer of the lower layer. The oxygen (O) content in the total content of (C), nitrogen (N) and oxygen (O) is expressed in atomic% (= O / (Ti + C + N + O) × 100).
上記した処理は、下部層の最表面層として、酸素含有ＴｉＣＮ層を形成するものであるが、以下に示すように、別の形態の下部層の最表面層を形成することもできる。
即ち、まず、通常の化学蒸着装置を使用して、下部層として、ＴｉＣ層、ＴｉＮ層、ＴｉＣＮ層、ＴｉＣＯ層およびＴｉＣＮＯ層のうちの１層または２層以上からなる種々のＴｉ化合物層を蒸着形成した後、該蒸着形成した下部層の表面に対して、
反応ガス組成（容量％）：ＣＯ ５〜１０％、ＣＯ２ ５〜１０％、残部Ｈ２、
雰囲気温度：９００〜９７０℃、
雰囲気圧力：５〜１５ｋＰａ、
時間：１〜５ｍｉｎ、
という条件でＣＯとＣＯ２混合ガスによる酸化処理を行うことによって、α-Ａｌ２Ｏ３核生成に必要なＡｌ化合物の核をＴｉ化合物層最表面に均一分散させることで、Ａｌ２Ｏ３核生成前の工程において、Ｔｉ化合物層最表面にα-Ａｌ２Ｏ３核を均一分散させることができる。
In the above-described treatment, the oxygen-containing TiCN layer is formed as the outermost surface layer of the lower layer. However, as shown below, the outermost surface layer of the lower layer in another form can be formed.
That is, first, various Ti compound layers consisting of one or more of TiC layer, TiN layer, TiCN layer, TiCO layer and TiCNO layer are deposited as a lower layer using a normal chemical vapor deposition apparatus. After forming, with respect to the surface of the deposited lower layer,
Reaction gas composition (volume%): CO 5-10%, CO 2 5-10%, balance H 2 ,
Atmospheric temperature: 900-970 ° C
Atmospheric pressure: 5-15 kPa,
Time: 1-5 min
By performing oxidation treatment with a mixed gas of CO and CO 2 under the condition of the above, Al 2 O 3 nuclei are uniformly dispersed on the outermost surface of the Ti compound layer by uniformly dispersing Al compound nuclei necessary for α-Al 2 O 3 nucleation. In the step before generation, α-Al 2 O 3 nuclei can be uniformly dispersed on the outermost surface of the Ti compound layer.
中間層：
本発明では、下部層と上部層との間に、０．５〜２．０μｍの平均層厚および化学蒸着した状態でα型の結晶構造を有するＴｉ含有α型Ａｌ２Ｏ３層（但し、原子比で、Ｔｉ／（Ａｌ＋Ｔｉ＋Ｏ）の比の値は０．０００１〜０．００１）からなる中間層が介在形成することにより、下部層と中間層、さらには、中間層と上部層の密着性を向上することができ、その結果として、被覆工具の耐チッピング性、耐剥離性はさらに向上する。
中間層Ｔｉ含有α型Ａｌ２Ｏ３層の層厚が０．５μｍよりも小さいと、（１１−２０）配向を有したＴｉ含有α型Ａｌ２Ｏ３結晶粒を得ることが難しくなり、Ｔｉ含有α型Ａｌ２Ｏ３層の層厚が２．０μｍよりも大きいと、上部層の（０００１）配向Ａｌ２Ｏ３結晶粒の占める面積割合が、全体の７０面積％以下になり、上部層Ａｌ２Ｏ３の高温強度が低下する。
Middle layer:
In the present invention, a Ti-containing α-type Al 2 O 3 layer having an average layer thickness of 0.5 to 2.0 μm and a chemical vapor deposition state between the lower layer and the upper layer (provided that The intermediate layer composed of Ti / (Al + Ti + O) having an atomic ratio of 0.0001 to 0.001) intervenes to form an adhesion between the lower layer and the intermediate layer, and further, the intermediate layer and the upper layer. As a result, the chipping resistance and peeling resistance of the coated tool are further improved.
When the layer thickness of the intermediate layer Ti-containing α-type Al 2 O 3 layer is smaller than 0.5 μm, it becomes difficult to obtain Ti-containing α-type Al 2 O 3 crystal grains having the (11-20) orientation. When the layer thickness of the containing α-type Al 2 O 3 layer is larger than 2.0 μm, the area ratio of the (0001) -oriented Al 2 O 3 crystal grains in the upper layer becomes 70% by area or less of the entire upper layer. The high temperature strength of Al 2 O 3 decreases.
上記組成式において、Ｔｉの含有割合Ｘを０．０００１≦Ｘ≦０．００１（原子比）と限定したのは、次のような理由による。
つまり、Ｔｉ成分は、Ｔｉ含有Ａｌ２Ｏ３の結晶粒界面強度を向上させ、高温強度の向上に寄与するが、Ｔｉ成分の含有割合Ｘが０．０００１未満では、このような作用を期待することはできず、一方、Ｔｉ成分の含有割合が０．００１を超えた場合には、層中にＴｉ酸化物の析出が始まるとによって粒界面強度が低下するため、Ａｌ成分との合量に占めるＴｉ成分の含有割合Ｘは、０．０００１〜０．００１（但し、原子比）であることが必要である。
In the composition formula, the Ti content ratio X is limited to 0.0001 ≦ X ≦ 0.001 (atomic ratio) for the following reason.
That is, the Ti component improves the crystal grain interface strength of the Ti-containing Al 2 O 3 and contributes to the improvement of the high-temperature strength. However, when the content ratio X of the Ti component is less than 0.0001, such an effect is expected. On the other hand, when the content ratio of the Ti component exceeds 0.001, the grain interface strength decreases due to the start of precipitation of the Ti oxide in the layer. The content ratio X of the occupied Ti component needs to be 0.0001 to 0.001 (however, the atomic ratio).
上記Ｔｉ含有Ａｌ２Ｏ３は、酸素含有ＴｉＣＮ層を形成した後、あるいは、下部層最表面にα-Ａｌ２Ｏ３核を均一分散させた下部層の上に、例えば、
反応ガス組成：容量％で、ＡｌＣｌ３：１．５〜５％、ＴｉＣｌ４：０．１〜０．４％、ＣＯ２：１〜５％、ＨＣｌ：１．５〜３％、Ｈ２：残り、
反応雰囲気温度：９００〜９７０℃、
反応雰囲気圧力：５〜１５ｋＰａ、
時間：５〜３０ｍｉｎ
の条件で蒸着することにより、α型の結晶構造を有するＴｉ含有α型Ａｌ２Ｏ３層（但し、原子比で、Ｔｉ／（Ａｌ＋Ｔｉ＋Ｏ）の比の値は０．０００１〜０．００１）からなる中間層を形成し得る。
The Ti-containing Al 2 O 3 is formed after the oxygen-containing TiCN layer is formed or on the lower layer in which α-Al 2 O 3 nuclei are uniformly dispersed on the outermost surface of the lower layer, for example,
Reaction gas composition: by volume%, AlCl 3: 1.5~5%, TiCl 4: 0.1~0.4%, CO 2: 1~5%, HCl: 1.5~3%, H 2: remaining,
Reaction atmosphere temperature: 900-970 ° C.
Reaction atmosphere pressure: 5 to 15 kPa,
Time: 5-30min
The Ti-containing α-type Al 2 O 3 layer having an α-type crystal structure (however, the atomic ratio of Ti / (Al + Ti + O) is from 0.0001 to 0.001). An intermediate layer can be formed.
このＴｉ含有Ａｌ２Ｏ３層は、それ自体で、高温強度を向上させ、かつ、耐衝撃性に優れるが、これに加えて、上記Ｔｉ含有Ａｌ２Ｏ３からなる中間層は、特定の配向性と特定の横方向平均粒径を有し、このため、中間層の上に形成する上部層の配向性および横方向平均粒径に対して、好ましい影響を与える。
より具体的にいえば、上記で形成されたＴｉ含有Ａｌ２Ｏ３層は、該中間層を構成するＴｉ含有Ａｌ２Ｏ３結晶粒について、電子線後方散乱回折装置を用いて、その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、工具基体の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た場合、その傾斜角が０〜１０度であるＴｉ含有Ａｌ２Ｏ３結晶粒（「（０００１）配向Ｔｉ含有Ａｌ２Ｏ３結晶粒」）の占める面積割合は、測定範囲の面積の１５〜３５面積％であり、かつ、該（０００１）配向Ｔｉ含有Ａｌ２Ｏ３結晶粒の工具基体表面に平行方向（横方向）の平均粒径は０．３〜１．０μｍであって、膜厚方向に成長した柱状結晶組織を有している。
（０００１）配向Ｔｉ含有Ａｌ２Ｏ３結晶粒の占める面積割合が、測定範囲の面積の１５面積％以下である場合は、上部層の（０００１）配向Ａｌ２Ｏ３結晶粒の占める面積割合が全体の７０％以下になり、上部層Ａｌ２Ｏ３の高温強度が低下する。一方、（０００１）配向Ｔｉ含有Ａｌ２Ｏ３結晶粒の占める面積割合が、測定範囲の面積の３５面積％以上である場合は、上部層Ａｌ２Ｏ３結晶粒の柱状組織が層厚方向に対して、傾斜した状態で形成され、所望の（０００１）配向の面積割合を得ることができない。また、（０００１）配向Ｔｉ含有Ａｌ２Ｏ３結晶粒の横方向の平均粒径が０．３μｍ未満の場合は、粒径が小さすぎて、下部層直上Ｔｉ化合物表面の凹凸との結合性が悪くなるため、上部層Ａｌ２Ｏ３結晶粒との付着強度が弱くなる。平均粒径が１．０μｍ以上の場合は、上部層のＡｌ２Ｏ３結晶粒が粗粒化し、耐チッピング性が低下してしまう。
The Ti-containing Al 2 O 3 layer itself improves the high-temperature strength and is excellent in impact resistance. In addition, the intermediate layer made of the Ti-containing Al 2 O 3 has a specific orientation. And has a specific lateral average particle size, and thus has a positive effect on the orientation and lateral average particle size of the upper layer formed on the intermediate layer.
More specifically, the Ti-containing Al 2 O 3 layer formed above is subjected to cross-sectional polishing of the Ti-containing Al 2 O 3 crystal grains constituting the intermediate layer using an electron beam backscattering diffractometer. An electron beam is irradiated to each crystal grain having a hexagonal crystal lattice existing within the measurement range of the face, and the method of the (0001) face that is the crystal face of the crystal grain with respect to the normal of the surface of the tool base When the inclination angle formed by the line is measured, the area ratio occupied by Ti-containing Al 2 O 3 crystal grains (“(0001) oriented Ti-containing Al 2 O 3 crystal grains”) whose inclination angle is 0 to 10 degrees is The average grain size in the direction parallel to the tool substrate surface (lateral direction) of the (0001) -oriented Ti-containing Al 2 O 3 crystal grains is 0.3 to 1. 0 μm, which has a columnar crystal structure grown in the film thickness direction .
When the area ratio occupied by (0001) oriented Ti-containing Al 2 O 3 crystal grains is 15 area% or less of the area of the measurement range, the area ratio occupied by (0001) oriented Al 2 O 3 crystal grains in the upper layer is It becomes 70% or less of the whole, and the high temperature strength of the upper layer Al 2 O 3 is lowered. On the other hand, when the area ratio occupied by the (0001) oriented Ti-containing Al 2 O 3 crystal grains is 35% by area or more of the area of the measurement range, the columnar structure of the upper layer Al 2 O 3 crystal grains is in the layer thickness direction. On the other hand, it is formed in an inclined state, and an area ratio of a desired (0001) orientation cannot be obtained. In addition, when the average grain size in the lateral direction of the (0001) oriented Ti-containing Al 2 O 3 crystal grains is less than 0.3 μm, the grain size is too small and the bonding with the irregularities on the surface of the Ti compound directly above the lower layer Since it gets worse, the adhesion strength with the upper layer Al 2 O 3 crystal grains becomes weaker. When the average particle diameter is 1.0 μm or more, the Al 2 O 3 crystal grains in the upper layer are coarsened, and chipping resistance is lowered.
また、同様に、該中間層のＴｉ含有Ａｌ２Ｏ３結晶粒について、電子線後方散乱回折装置を用いて、その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、工具基体の表面の法線に対して、前記結晶粒の結晶面である（１１−２０）面の法線がなす傾斜角を測定した場合、その傾斜角が０〜１０度であるＴｉ含有Ａｌ２Ｏ３結晶粒（「（１１−２０）配向Ｔｉ含有Ａｌ２Ｏ３結晶粒」）の占める面積割合は、測定範囲の面積の５５〜７５面積％であり、かつ、該（１１−２０）配向Ｔｉ含有Ａｌ２Ｏ３結晶粒の横方向平均粒径は１．０〜２．０μｍであって、膜厚方向に成長した柱状結晶組織を有している。
（１１−２０）配向Ｔｉ含有Ａｌ２Ｏ３結晶粒の占める面積割合が５５％未満である、または該Ｔｉ含有Ａｌ２Ｏ３結晶粒の横方向平均粒径が１．０μｍ未満である場合、上部層Ａｌ２Ｏ３結晶粒の柱状組織が層厚方向に対して、傾斜した状態で形成され、所望の（０００１）配向の面積割合を得ることができない。また、（１１−２０）配向Ｔｉ含有Ａｌ２Ｏ３結晶粒の占める面積割合が７５％以上である、または該Ｔｉ含有Ａｌ２Ｏ３結晶粒の横方向平均粒径が２．０μｍ以上である場合、上部層（０００１）配向Ａｌ２Ｏ３結晶粒の占める面積割合が全体の７０％以下になり、上部層Ａｌ２Ｏ３の高温強度が低下する。
Similarly, for the Ti-containing Al 2 O 3 crystal grains of the intermediate layer, each crystal grain having a hexagonal crystal lattice existing within the measurement range of the cross-sectional polished surface is measured using an electron beam backscattering diffractometer. When the tilt angle formed by the normal of the (11-20) plane, which is the crystal plane of the crystal grain, is measured with respect to the normal of the surface of the tool base by irradiating an electron beam, the tilt angle is 0 to 0. The area ratio occupied by Ti-containing Al 2 O 3 crystal grains (“(11-20) oriented Ti-containing Al 2 O 3 crystal grains”) that is 10 degrees is 55 to 75 area% of the area of the measurement range, and The (11-20) oriented Ti-containing Al 2 O 3 crystal grains have a lateral average grain size of 1.0 to 2.0 μm and have a columnar crystal structure grown in the film thickness direction.
(11-20) When the area ratio occupied by oriented Ti-containing Al 2 O 3 crystal grains is less than 55%, or the transverse average particle size of the Ti-containing Al 2 O 3 crystal grains is less than 1.0 μm, The columnar structure of the upper layer Al 2 O 3 crystal grains is formed in an inclined state with respect to the layer thickness direction, and a desired area ratio of (0001) orientation cannot be obtained. Also, is the (11-20) oriented Ti area ratio occupied by the containing Al 2 O 3 crystal grains is 75% or more, or the Ti-containing Al 2 O 3 laterally average grain size of 2.0μm or more In this case, the area ratio occupied by the upper layer (0001) -oriented Al 2 O 3 crystal grains becomes 70% or less of the whole, and the high-temperature strength of the upper layer Al 2 O 3 decreases.
中間層のＴｉ含有Ａｌ２Ｏ３結晶粒が、前記のような配向性と特定の横方向平均粒径を有することにより、この上に蒸着形成された上部層との界面の付着強度が一段と向上するとともに、上部層に所定の配向性、横方向平均粒径を有するＡｌ２Ｏ３結晶粒が形成され、上部層はより高硬度となり、耐摩耗性も向上する。
その結果、この発明の被覆工具は、高速断続切削加工時の断続的・衝撃的負荷に対してすぐれた耐チッピング性、耐剥離性を発揮するようになる。
The Ti-containing Al 2 O 3 crystal grains in the intermediate layer have the above-mentioned orientation and a specific lateral average grain size, thereby further improving the adhesion strength at the interface with the upper layer deposited thereon. In addition, Al 2 O 3 crystal grains having a predetermined orientation and a lateral average grain size are formed in the upper layer, so that the upper layer has higher hardness and improved wear resistance.
As a result, the coated tool of the present invention exhibits excellent chipping resistance and peeling resistance against intermittent / impact loads during high-speed intermittent cutting.
上部層のＡｌ２Ｏ３層：
Ｔｉ化合物層からなる下部層の最表面層に、例えば、０．５〜３原子％の酸素を含有する酸素含有ＴｉＣＮ層を形成し、該下部層の最表面層の上に、所定の配向性と横方向平均粒径を有するＴｉ含有Ａｌ２Ｏ３層を中間層として介在形成し、この表面に、例えば、次のような条件でＡｌ２Ｏ３を蒸着することによって、本発明で規定する配向性を備えた、また、制御された横方向平均粒径を備えた柱状結晶組織のＡｌ２Ｏ３層からなる上部層が得られる。
上部層は、中間層の表面に、例えば、
反応ガス組成（容量％）：ＡｌＣｌ３ １〜５％、ＣＯ２ ５〜１０％、ＨＣｌ １〜５％、Ｈ２Ｓ ０．５〜１％、残部Ｈ２、
反応雰囲気温度：９６０〜１０４０℃、
反応雰囲気圧力：５〜１５ｋＰａ、
時間：（目標とする上部層層厚になるまで）
という条件で蒸着することにより、層厚方向とほぼ平行に成長した微細な縦長柱状Ａｌ２Ｏ３結晶粒で構成され、（０００１）配向Ａｌ２Ｏ３結晶粒の面積割合が、上部層全体のＡｌ２Ｏ３結晶粒に対して７０面積％以上を占めるＡｌ２Ｏ３層からなる上部層が形成される。
しかも、この上部層においては、Ａｌ２Ｏ３結晶粒の横方向平均粒径は１．０〜２．０μｍであって、膜厚方向に成長した柱状結晶組織を有している。
ここで、「（０００１）配向Ａｌ２Ｏ３結晶粒」とは、上部層のＡｌ２Ｏ３結晶粒について、電子線後方散乱回折装置を用いて、その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、前記工具基体の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た場合、その傾斜角が０〜１０度であるＡｌ２Ｏ３結晶粒のことをいう。
Upper layer Al 2 O 3 layer:
For example, an oxygen-containing TiCN layer containing 0.5 to 3 atom% of oxygen is formed on the outermost surface layer of the lower layer made of the Ti compound layer, and a predetermined orientation is formed on the outermost surface layer of the lower layer. And a Ti-containing Al 2 O 3 layer having an average particle size in the transverse direction as an intermediate layer, and Al 2 O 3 is vapor-deposited on the surface under the following conditions, for example. An upper layer consisting of an Al 2 O 3 layer of columnar crystal structure with an orientation and a controlled lateral average grain size is obtained.
The upper layer is formed on the surface of the intermediate layer, for example,
Reaction gas composition (volume%): AlCl 3 1-5%, CO 2 5-10%, HCl 1-5%, H 2 S 0.5-1%, balance H 2 ,
Reaction atmosphere temperature: 960-1040 ° C.
Reaction atmosphere pressure: 5 to 15 kPa,
Time: (until the target upper layer thickness is reached)
By depositing under the condition of the above, it is composed of fine vertical columnar Al 2 O 3 crystal grains grown almost parallel to the layer thickness direction, and the area ratio of (0001) oriented Al 2 O 3 crystal grains is An upper layer composed of an Al 2 O 3 layer occupying 70 area% or more with respect to the Al 2 O 3 crystal grains is formed.
Moreover, in this upper layer, the Al 2 O 3 crystal grains have a lateral average grain size of 1.0 to 2.0 μm and have a columnar crystal structure grown in the film thickness direction.
Here, “(0001) -oriented Al 2 O 3 crystal grains” means that the Al 2 O 3 crystal grains in the upper layer exist within the measurement range of the cross-sectional polished surface using an electron beam backscattering diffractometer. Irradiate each crystal grain having a hexagonal crystal lattice with an electron beam, and measure the inclination angle formed by the normal line of the (0001) plane that is the crystal plane of the crystal grain with respect to the normal line of the surface of the tool base. In this case, it means Al 2 O 3 crystal grains having an inclination angle of 0 to 10 degrees.
つまり、上部層のＡｌ２Ｏ３結晶粒は、層厚方向とほぼ平行な方向に微細な縦長柱状Ａｌ２Ｏ３結晶粒として成長し、しかも、（０００１）配向Ａｌ２Ｏ３結晶粒が形成される。上部層全体のＡｌ２Ｏ３結晶粒に対する（０００１）配向Ａｌ２Ｏ３結晶粒の面積割合は、上記蒸着条件のうちの、特に、ＡｌＣｌ３ガス量とＣＯ２ガス量が影響する。
形成される（０００１）配向Ａｌ２Ｏ３結晶粒の面積割合が、７０面積％以上を占める場合に、上部層Ａｌ２Ｏ３の高温硬さ、高温強度が維持されることから、本発明では、上部層の（０００１）配向Ａｌ２Ｏ３結晶粒の面積割合を、７０面積％以上と定めた。
That is, the Al 2 O 3 crystal grains in the upper layer grow as fine vertical columnar Al 2 O 3 crystal grains in a direction substantially parallel to the layer thickness direction, and (0001) -oriented Al 2 O 3 crystal grains are formed. Is done. Area ratio of relative Al 2 O 3 crystal grains of the whole upper layer (0001) oriented Al 2 O 3 crystal grains, of the above deposition conditions, in particular, AlCl 3 gas amount and the amount of CO 2 gas is affected.
In the present invention, the high-temperature hardness and high-temperature strength of the upper layer Al 2 O 3 are maintained when the area ratio of the formed (0001) -oriented Al 2 O 3 crystal grains occupies 70 area% or more. The area ratio of (0001) -oriented Al 2 O 3 crystal grains in the upper layer was determined to be 70 area% or more.
上記（０００１）配向Ａｌ２Ｏ３結晶粒の面積割合は、上部層全体のＡｌ２Ｏ３結晶粒について、電界放出型走査電子顕微鏡を用い、その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、前記工具基体の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、その傾斜角が０〜１０度である結晶粒の面積割合の測定平均値として求められる。 The area ratio of the (0001) -oriented Al 2 O 3 crystal grains was determined by using a field emission scanning electron microscope for the Al 2 O 3 crystal grains of the entire upper layer, and presenting a hexagonal crystal in the measurement range of the cross-sectional polished surface. Irradiating each crystal grain having a crystal lattice with an electron beam, and measuring an inclination angle formed by a normal line of a (0001) plane that is a crystal plane of the crystal grain with respect to a normal line of the surface of the tool base; It is obtained as a measurement average value of the area ratio of crystal grains whose inclination angle is 0 to 10 degrees.
さらに、この発明の上部層においては、Ａｌ２Ｏ３結晶粒の横方向平均粒径が１．０〜２．０μｍの範囲である縦長の柱状結晶組織を形成する。
Ａｌ２Ｏ３結晶粒の横方向平均粒径が１．０μｍ未満では、上部層と下部層、あるいは、上部層と中間層の界面における結晶粒の結晶面の凹凸の結合性が悪くなり、付着強度の低下を招きやすくなるとともにポアが発生しやすくなる。一方、横方向平均粒径が２．０μｍを超えると、相対的に上部層のＡｌ２Ｏ３結晶粒のサイズが大きすぎて、上部層のＡｌ２Ｏ３形成時にポアが形成されやすくなり、そのため上部層の硬さ、強度が低下するともに、上部層と中間層との付着強度が低下する。
そこで、この発明においては、上部層のＡｌ２Ｏ３結晶粒の横方向平均粒径を１．０〜２．０μｍの範囲に定めた。
Furthermore, in the upper layer of the present invention, a vertically long columnar crystal structure in which the average average grain size of Al 2 O 3 crystal grains is in the range of 1.0 to 2.0 μm is formed.
If the average grain size in the lateral direction of the Al 2 O 3 crystal grains is less than 1.0 μm, the bonding of the irregularities on the crystal planes of the crystal grains at the interface between the upper layer and the lower layer or between the upper layer and the intermediate layer is deteriorated and adhered. The strength is likely to decrease, and pores are easily generated. On the other hand, when the lateral average particle size exceeds 2.0 μm, the size of the Al 2 O 3 crystal grains in the upper layer is relatively large, and pores are easily formed during the formation of the Al 2 O 3 in the upper layer. For this reason, the hardness and strength of the upper layer are lowered, and the adhesion strength between the upper layer and the intermediate layer is lowered.
Therefore, in the present invention, the average lateral grain size of the Al 2 O 3 crystal grains in the upper layer is set in the range of 1.0 to 2.0 μm.
上部層のＡｌ２Ｏ３結晶粒の横方向平均粒径は、上部層の測定領域において、電子線後方散乱回折装置を用いて、その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することにより横方向粒径を測定し、その測定値の平均値を算出することにより求めることができる。 The average lateral grain size of the Al 2 O 3 crystal grains in the upper layer is determined by the hexagonal crystal lattice existing in the measurement range of the cross-sectional polished surface in the measurement region of the upper layer using an electron beam backscattering diffractometer. It can be determined by measuring the lateral grain size by irradiating an electron beam to each of the crystal grains, and calculating the average value of the measured values.
また、上部層の層厚については、１μｍ未満であると長期の使用にわたってすぐれた高温強度および高温硬さを発揮することができず、一方、１５μｍを越えると、チッピングが発生し易くなることから、上部層の層厚は１〜１５μｍと定めた。 In addition, if the thickness of the upper layer is less than 1 μm, excellent high-temperature strength and high-temperature hardness cannot be exhibited over a long period of use, whereas if it exceeds 15 μm, chipping is likely to occur. The layer thickness of the upper layer was determined to be 1 to 15 μm.
この発明の被覆工具は、硬質被覆層の下部層最表面に、例えば、酸素含有ＴｉＣＮ層を形成し、そしてこの上に、所定面積割合、所定横方向平均粒径を有するＴｉ含有Ａｌ２Ｏ３結晶粒からなる中間層を形成し、さらに、上部層として、所定面積割合、所定横方向平均粒径のＡｌ２Ｏ３結晶粒からなる縦長の柱状結晶組織を形成することにより、下部層、中間層、上部層の密着強度を高めることができるため、各種の鋼や鋳鉄などの切削加工を、切れ刃に対して断続的・衝撃的負荷が作用する高速断続切削条件で行っても、すぐれた高温強度と高温硬さを示し、硬質被覆層の剥離・チッピングの発生もなく、長期の使用にわたって切削性能を発揮するものである。 In the coated tool of the present invention, for example, an oxygen-containing TiCN layer is formed on the outermost surface of the lower layer of the hard coating layer, and a Ti-containing Al 2 O 3 having a predetermined area ratio and a predetermined transverse average particle size is formed thereon. An intermediate layer made of crystal grains is formed, and further, as an upper layer, a vertically long columnar crystal structure made of Al 2 O 3 crystal grains having a predetermined area ratio and a predetermined average transverse grain size is formed. Since the adhesion strength of the upper layer and the upper layer can be increased, it is excellent even when cutting various steels and cast irons under high-speed intermittent cutting conditions where intermittent and impact loads are applied to the cutting edge. It exhibits high temperature strength and high temperature hardness, exhibits no cutting and chipping of the hard coating layer, and exhibits cutting performance 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、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。 As raw material powders, WC powder, TiC powder, ZrC powder, VC powder, TaC powder, NbC powder, Cr 3 C 2 powder, TiN powder, and Co powder each having an average particle diameter of 1 to 3 μm are prepared. The raw material powder is blended in the blending composition shown in Table 1, added with wax, ball mill mixed in acetone for 24 hours, dried under reduced pressure, and press-molded into a green compact of a predetermined shape at a pressure of 98 MPa. The green compact is vacuum-sintered in a vacuum of 5 Pa at a predetermined temperature within a range of 1370 to 1470 ° C. for 1 hour. After sintering, the cutting edge is subjected to a honing process of R: 0.07 mm. As a result, tool bases A to F made of WC-base cemented carbide having an insert shape specified in ISO · CNMG120408 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、Ｍｏ2 Ｃ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、切刃部分に幅：０．１ｍｍ、角度：２０度のチャンファーホーニング加工を施すことによりＩＳＯ規格・ＣＮＭＧ１２０４０８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 sintering, a chamfer with a width of 0.1 mm and an angle of 20 degrees at the cutting edge portion. By performing honing, tool bases a to f made of TiCN-based cermet having an ISO standard / CNMG120408 insert shape 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、
（ａ）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５に示される目標層厚のＴｉ化合物層を蒸着形成した。
（ｂ）表４に示される条件にて、下部層の最表面層としての酸素含有ＴｉＣＮ層（即ち、該層の表面から５００ｎｍまでの深さ領域にのみ、０．５〜３原子％（Ｏ／（Ｔｉ＋Ｃ＋Ｎ＋Ｏ）×１００）の酸素が含有される）を表５に示される目標層厚で形成し、
（ｃ）ついで、表６に示される条件にて、中間層のＴｉ含有Ｔｉ含有Ａｌ２Ｏ３層を目標層厚で形成し、
（ｄ）ついで、表７に示される条件にて、上部層のＡｌ２Ｏ３層を表８に示される目標層厚で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。
Then, each of these tool bases A to F and tool bases a to f is charged into a normal chemical vapor deposition apparatus,
(A) First, Table 3 (l-TiCN in Table 3 indicates the conditions for forming a TiCN layer having a vertically elongated crystal structure described in JP-A-6-8010, and the other conditions are ordinary granularity. The Ti compound layer having the target layer thickness shown in Table 5 was formed by vapor deposition under the conditions shown in FIG.
(B) Under the conditions shown in Table 4, the oxygen-containing TiCN layer as the outermost surface layer of the lower layer (i.e., 0.5 to 3 atomic% (O 2 only in the depth region from the surface of the layer to 500 nm) / (Ti + C + N + O) × 100) containing oxygen) with the target layer thickness shown in Table 5,
(C) Next, under the conditions shown in Table 6, a Ti-containing Ti-containing Al 2 O 3 layer as an intermediate layer is formed with a target layer thickness,
(D) Then, under the conditions shown in Table 7, by forming the upper Al 2 O 3 layer with the target layer thickness shown in Table 8,
The present coated tools 1 to 13 were produced, respectively.
また、比較の目的で、上記本発明被覆工具１〜１３の上記工程（ｃ），（ｄ）から外れた条件で、あるいは、これらの工程を行わずに、表６〜７に示される条件にて硬質被覆層を形成することにより、表９に示す比較被覆工具１〜７を製造した。 Moreover, for the purpose of comparison, the conditions shown in Tables 6 to 7 are satisfied under conditions deviating from the steps (c) and (d) of the inventive coated tools 1 to 13 or without performing these steps. Then, comparative coating tools 1 to 7 shown in Table 9 were manufactured by forming a hard coating layer.
ついで、上記の本発明被覆工具１〜１３と比較被覆工具１〜１３について、下部層の最表面層を構成するＴｉＣＮ層について、該ＴｉＣＮ層の層厚方向に５００ｎｍまでの深さ領域における平均酸素含有量（＝Ｏ／（Ｔｉ＋Ｃ＋Ｎ＋Ｏ）×１００）、さらに、５００ｎｍを超える深さ領域における平均酸素含有量（＝Ｏ／（Ｔｉ＋Ｃ＋Ｎ＋Ｏ）×１００）を、オージェ電子分光分析器を用い、被覆工具の断面研磨面に下部層Ｔｉ炭窒化物層の最表面からＴｉ炭化物層の膜厚相当の距離の範囲に直径１０ｎｍの電子線を照射させていき、Ｔｉ,Ｃ,Ｎ,Ｏのオージェピークの強度を測定し、それらのピーク強度の総和からＯのオージェピークの割合から算出した。
表５にこれらの値を示す。
Next, for the above-described inventive coated tools 1 to 13 and comparative coated tools 1 to 13, with respect to the TiCN layer constituting the outermost surface layer of the lower layer, the average oxygen in the depth region up to 500 nm in the layer thickness direction of the TiCN layer The content (= O / (Ti + C + N + O) × 100), and the average oxygen content (= O / (Ti + C + N + O) × 100) in a depth region exceeding 500 nm were measured using an Auger electron spectrometer. The polished surface is irradiated with an electron beam having a diameter of 10 nm from the outermost surface of the lower Ti carbonitride layer to a distance corresponding to the thickness of the Ti carbide layer, and the intensity of the Auger peaks of Ti, C, N, and O is increased. Measured, and calculated from the ratio of O Auger peaks from the sum of the peak intensities.
Table 5 shows these values.
上記の本発明被覆工具１〜１３と比較被覆工具１〜１３について、中間層のＴｉ含有Ａｌ２Ｏ３結晶粒の（０００１）配向Ｔｉ含有Ａｌ２Ｏ３、（１１−２０）配向Ｔｉ含有Ａｌ２Ｏ３の面積割合、横方向平均粒径、さらには、上部層の（０００１）配向Ａｌ２Ｏ３結晶粒の面積割合、横方向平均粒径を測定し求めた。
より具体的にいえば、中間層のＴｉ含有Ａｌ２Ｏ３結晶粒、（１１−２０）配向Ｔｉ含有Ａｌ２Ｏ３粒、上部層の（０００１）配向Ａｌ２Ｏ３結晶粒の面積割合については、工具基体表面と平行方向に５０μｍの断面研磨面の上部層の測定範囲（０．３μｍ×５０μｍ）を、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、工具基体の表面の法線に対して、前記結晶粒の結晶面である（０００１）面の法線あるいは（１１−２０）がなす傾斜角を測定し、その傾斜角が０〜１０度である結晶粒の面積割合を測定することによって求めた。
表８、表９にこれらの値を示す。
About said invention coated tools 1-13 and comparative coated tools 1-13, (0001) oriented Ti-containing Al 2 O 3 and (11-20) oriented Ti-containing Al of Ti-containing Al 2 O 3 crystal grains of the intermediate layer The area ratio of 2 O 3 and the average grain size in the horizontal direction were measured, and the area ratio of the (0001) -oriented Al 2 O 3 crystal grains in the upper layer and the average grain diameter in the horizontal direction were measured.
More specifically, the area ratio of Ti-containing Al 2 O 3 crystal grains in the intermediate layer, (11-20) oriented Ti-containing Al 2 O 3 grains, and (0001) oriented Al 2 O 3 crystal grains in the upper layer. Set the measuring range (0.3 μm × 50 μm) of the upper layer of the 50 μm cross-section polished surface in the direction parallel to the tool substrate surface in the barrel of the field emission scanning electron microscope, An electron beam with an acceleration voltage of 15 kV at an incident angle is irradiated with an irradiation current of 1 nA on each crystal grain having a hexagonal crystal lattice existing in the measurement range of each of the polished surfaces, so that the normal of the surface of the tool substrate is obtained. In contrast, the inclination angle formed by the normal line of the (0001) plane which is the crystal plane of the crystal grain or (11-20) is measured, and the area ratio of the crystal grain whose inclination angle is 0 to 10 degrees is measured. Sought by.
Tables 8 and 9 show these values.
また、横方向平均粒径については、Ａｌ２Ｏ３結晶粒について、電界放出型走査電子顕微鏡と電子後方散乱回折像装置を用い、断面研磨面の測定範囲内に存在するＡｌ２Ｏ３結晶粒の六方晶結晶格子を有する結晶粒個々に電子線を照射する。観察倍率１０，０００倍で測定し、その菊池線回折図形から、工具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、および（１０−１０）面の法線同士の交わる角度を求め、さらに、前記（０００１）面の法線同士、および（１０−１０）面の法線同士の交わる角度が２度以上の場合を結晶粒として定義し、（０００１）配向Ａｌ２Ｏ３結晶粒における横方向の線分測定点１０箇所の測定値の平均から、それぞれのＡｌ２Ｏ３結晶粒の横方向平均粒径を求めた。
表８、表９にこれらの値を示す。
As for the average grain size in the transverse direction, Al 2 O 3 crystal grains existing within the measurement range of the cross-sectional polished surface were obtained using Al 2 O 3 crystal grains using a field emission scanning electron microscope and an electron backscatter diffraction image apparatus. Each crystal grain having a hexagonal crystal lattice is irradiated with an electron beam. Measured at an observation magnification of 10,000 times, and from the Kikuchi line diffraction pattern, the normal lines of the (0001) plane and the (10-10) plane, which are crystal planes of the crystal grains, with respect to the normal line of the tool base surface The angle formed is measured, and the angle at which the normals of the (0001) plane and the normals of the (10-10) plane intersect each other at the interface between adjacent crystal grains is determined from the resulting measured tilt angle. Furthermore, the case where the angle between the normals of the (0001) planes and the normals of the (10-10) planes is 2 degrees or more is defined as a crystal grain, and (0001) oriented Al 2 O 3 The average lateral grain size of each Al 2 O 3 crystal grain was determined from the average of the measured values at the 10 horizontal line segment measurement points in the crystal grain.
Tables 8 and 9 show these values.
また、本発明被覆工具１〜１３、比較被覆工具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観察倍率２，０００倍にて観察したところ、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 comparative coated tool 1-13 was observed with the observation magnification of 2,000 times using the scanning electron microscope, all were. The average layer thickness (average value of 5-point measurement) substantially the same as the target layer thickness was shown.
つぎに、上記の本発明被覆工具１〜１３、比較被覆工具１〜１３の各種の被覆工具について、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・ＳＣＭ４４５の長さ方向等間隔８本縦溝入り、
切削速度：４００ｍ／ｍｉｎ．、
切り込み：２．５ｍｍ、
送り：０．３２ｍｍ／ｒｅｖ．、
切削時間：５分、
の条件（切削条件Ａという）での合金鋼の湿式高速断続切削試験（通常の切削速度は、２００ｍ／ｍｉｎ．、）、
被削材：ＪＩＳ・ＦＣＤ５００の長さ方向等間隔８本縦溝入り、
切削速度：４２０ｍ／ｍｉｎ．、
切り込み：３．０ｍｍ、
送り：０．４０ｍｍ／ｒｅｖ．、
切削時間：５分、
の条件（切削条件Ｂという）でのダグタイル鋳鉄の乾式高速断続切削試験（通常の切削速度は、１８０ｍ／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。
表１０にこの測定結果を示した。
Next, for the various coated tools of the present invention coated tools 1 to 13 and comparative coated tools 1 to 13, all of them are screwed with a fixing jig to the tip of the tool steel tool,
Work material: Eight longitudinally spaced grooves in the length direction of JIS / SCM445,
Cutting speed: 400 m / min. ,
Incision: 2.5mm,
Feed: 0.32 mm / rev. ,
Cutting time: 5 minutes
Wet high-speed intermittent cutting test (normal cutting speed is 200 m / min.) Of alloy steel under the following conditions (referred to as cutting conditions A),
Work material: Eight longitudinally spaced grooves in the length direction of JIS / FCD500
Cutting speed: 420 m / min. ,
Cutting depth: 3.0 mm,
Feed: 0.40 mm / rev. ,
Cutting time: 5 minutes
Dry high-speed intermittent cutting test (normal cutting speed is 180 m / min.) Of ductile cast iron under the following conditions (referred to as cutting condition B),
In each cutting test, the flank wear width of the cutting edge was measured.
Table 10 shows the measurement results.
表５、８〜１０に示される結果から、本発明被覆工具１〜１３は、下部層と上部層の間に、所定面積割合の（１１−２０）配向Ｔｉ含有Ａｌ２Ｏ３結晶粒および（０００１）配向Ｔｉ含有Ａｌ２Ｏ３結晶粒を形成し、さらに、それぞれの結晶粒の横方向平均粒径を、それぞれ、１・０〜２．０μｍ、０．３〜１．０μｍとして、さらに、上部層全体のＡｌ２Ｏ３結晶粒に占める（０００１）配向Ａｌ２Ｏ３結晶粒の面積割合は７０面積％以上であって、しかも、Ａｌ２Ｏ３結晶粒の横方向平均粒径は１．０〜２．０μｍであって、縦長柱状結晶構造を有することから、高熱発生を伴い、かつ、切刃に断続的・衝撃的負荷が作用する高速断続切削条件に用いた場合でも、硬質被覆層の各層間の付着強度がすぐれ、その結果、硬質被覆層の耐チッピング性、耐剥離性に優れるとともに、すぐれた耐摩耗性を発揮する。
これに対して、比較被覆工具１〜１３では、高速断続切削加工においては、硬質被覆層のチッピング発生、剥離発生により、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 and 8 to 10, the coated tools 1 to 13 of the present invention have (11-20) oriented Ti-containing Al 2 O 3 crystal grains having a predetermined area ratio between the lower layer and the upper layer, and ( 0001) oriented Ti-containing Al 2 O 3 crystal grains, and the average grain size in the transverse direction of each crystal grain is 1.0 to 2.0 μm and 0.3 to 1.0 μm, respectively, occupying the Al 2 O 3 crystal grains of the whole upper layer (0001) an area ratio of alignment Al 2 O 3 crystal grains is a 70 area% or more, yet, lateral average particle size of the Al 2 O 3 crystal grains 1 Even if it is used for high-speed interrupted cutting conditions with high heat generation and intermittent / impact load acting on the cutting edge because it has a vertically long columnar crystal structure. Excellent adhesion strength between layers, resulting in hard coating layer Chipping resistance is excellent in peeling resistance, exhibits excellent wear resistance.
On the other hand, it is clear that the comparative coated tools 1 to 13 reach the service life in a relatively short time due to occurrence of chipping and peeling of the hard coating layer in high-speed intermittent cutting.
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通常の条件での連続切削や断続切削は勿論のこと、切刃に断続的・衝撃的負荷が作用する高速断続切削という厳しい切削条件下でも、硬質被覆層の剥離、チッピングが発生することはなく、長期の使用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 continuous cutting and interrupted cutting under normal conditions such as various steels and cast irons, but also severe cutting such as high-speed intermittent cutting in which intermittent and impact loads act on the cutting edge. Even under cutting conditions, no peeling or chipping of the hard coating layer will occur, and excellent cutting performance will be demonstrated over long-term use. It can cope with energy saving and cost reduction sufficiently satisfactorily.
Claims (2)
（ａ）下部層が、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の合計平均層厚を有するＴｉ化合物層、
（ｂ）中間層が０．５〜２．０μｍの平均層厚およびα型の結晶構造を有するＴｉ含有α型Ａｌ２Ｏ３層（但し、原子比で、Ｔｉ／（Ａｌ＋Ｔｉ＋Ｏ）の比の値は０．０００１〜０．００１）、
（ｃ）上部層が、１〜１５μｍの平均層厚を有し、α型の結晶構造を有するＡｌ２Ｏ３層、
以上（ａ）〜（ｃ）からなる硬質被覆層が形成された表面被覆切削工具において、
（ｄ）上記中間層を構成する結晶粒(以下、「Ｔｉ含有Ａｌ２Ｏ３結晶粒」という)について、電子線後方散乱回折装置を用いて、その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、前記工具基体の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た場合、その傾斜角が０〜１０度であるＴｉ含有Ａｌ２Ｏ３結晶粒（以下、「（０００１）配向Ｔｉ含有Ａｌ２Ｏ３結晶粒」という）の占める面積割合は、前記測定範囲の面積の１５〜３５面積％であり、かつ、該（０００１）配向Ｔｉ含有Ａｌ２Ｏ３結晶粒の横方向平均粒径は０．３〜１．０μｍであって、膜厚方向に成長した柱状結晶組織を有し、
（ｅ）また、上記中間層のＴｉ含有Ａｌ２Ｏ３結晶粒について、電子線後方散乱回折装置を用いて、その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、前記工具基体の表面の法線に対して、前記結晶粒の結晶面である（１１−２０）面の法線がなす傾斜角を測定した場合、その傾斜角が０〜１０度であるＴｉ含有Ａｌ２Ｏ３結晶粒（以下、「（１１−２０）配向Ｔｉ含有Ａｌ２Ｏ３結晶粒」という）の占める面積割合は、前記測定範囲の面積の５５〜７５面積％であり、かつ、該（１１−２０）配向Ｔｉ含有Ａｌ２Ｏ３結晶粒の横方向平均粒径は１．０〜２．０μｍであって、膜厚方向に成長した柱状結晶組織を有し、
（ｆ）上記上部層のＡｌ２Ｏ３結晶粒について、電子線後方散乱回折装置を用いて、その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、前記工具基体の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た場合、その傾斜角が０〜１０度であるＡｌ２Ｏ３結晶粒の占める面積割合は、前記測定範囲の面積の７０面積％以上であり、かつ、上部層のＡｌ２Ｏ３結晶粒の横方向平均粒径は１．０〜２．０μｍであって、膜厚方向に成長した柱状結晶組織を有する、
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) The lower layer is composed of one or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer and carbonitride oxide layer, and a total average of 3 to 20 μm A Ti compound layer having a layer thickness,
(B) the ratio of the Ti-containing α-type the Al 2 O 3 layer which intermediate layer has an average layer thickness and α-type crystal structure of 0.5 to 2.0 [mu] m (where, in terms of atomic ratio, Ti / (Al + Ti + O) Is 0.0001 to 0.001),
(C) an Al 2 O 3 layer in which the upper layer has an average layer thickness of 1 to 15 μm and has an α- type crystal structure;
In the surface-coated cutting tool in which the hard coating layer composed of (a) to (c) is formed ,
(D) The hexagonal crystal grains that constitute the intermediate layer (hereinafter referred to as “Ti-containing Al 2 O 3 crystal grains”) exist within the measurement range of the cross-section polished surface using an electron beam backscattering diffractometer. Each crystal grain having a crystal lattice was irradiated with an electron beam, and an inclination angle formed by a normal line of the (0001) plane which is a crystal plane of the crystal grain was measured with respect to a normal line of the surface of the tool base. In this case, the area ratio occupied by Ti-containing Al 2 O 3 crystal grains (hereinafter referred to as “(0001) oriented Ti-containing Al 2 O 3 crystal grains”) having an inclination angle of 0 to 10 degrees is the area of the measurement range. And the (0001) -oriented Ti-containing Al 2 O 3 crystal grains have a lateral average grain size of 0.3 to 1.0 μm, and are columnar crystals grown in the film thickness direction. Have an organization,
(E) Further, with respect to the Ti-containing Al 2 O 3 crystal grains of the intermediate layer, each crystal grain having a hexagonal crystal lattice existing within the measurement range of the cross-sectional polished surface is measured using an electron beam backscattering diffractometer. When the tilt angle formed by the normal of the (11-20) plane, which is the crystal plane of the crystal grain, is measured with respect to the normal of the surface of the tool base by irradiating an electron beam, the tilt angle is 0. The area ratio occupied by Ti-containing Al 2 O 3 crystal grains (hereinafter referred to as “(11-20) -oriented Ti-containing Al 2 O 3 crystal grains”) of −10 degrees is 55 to 75 area of the area of the measurement range. And the (11-20) oriented Ti-containing Al 2 O 3 crystal grains have an average lateral grain size of 1.0 to 2.0 μm and a columnar crystal structure grown in the film thickness direction. And
(F) The upper layer Al 2 O 3 crystal grains are irradiated with an electron beam on each crystal grain having a hexagonal crystal lattice existing within the measurement range of the cross-section polished surface using an electron beam backscattering diffractometer. Then, when 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 surface of the tool base, the inclination angle is 0 to 10 degrees. The area ratio occupied by 2 O 3 crystal grains is 70 area% or more of the area of the measurement range, and the average average grain size of Al 2 O 3 crystal grains in the upper layer is 1.0 to 2.0 μm. And having a columnar crystal structure grown in the film thickness direction,
A surface-coated cutting tool characterized by that.
The outermost surface layer of the lower layer is made of a Ti carbonitride layer having a layer thickness of at least 500 nm, and from the interface between the Ti carbonitride layer and the upper layer, in the layer thickness direction of the Ti carbonitride layer Oxygen is contained only in the depth region up to 500 nm, and the average oxygen content contained in the depth region is the total content of Ti, C, N, and O contained in the depth region. The surface-coated cutting tool according to claim 1, wherein the content is 0.5 to 3 atomic%.
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