JP2007196351A - Surface coated cermet cutting tool having hard coating layer exhibiting excellent chipping resistance in high-speed cutting difficult-to-cut material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface coated cermet cutting tool having a hard coating layer exhibiting excellent chipping resistance in high-speed cutting difficult-to-cut material. <P>SOLUTION: This surface coated cermet tool is constructed by forming the hard coating layer including: a lower layer formed of a Ti compound layer; an interlayer contact layer of a contact type α-type Al<SB>2</SB>O<SB>3</SB>layer and an upper layer formed of a reformed α-type Al<SB>2</SB>O<SB>3</SB>layer on the surface of a tool base. In the case of measuring an angle of inclination made by a normal of (0001) face, which is a crystal plane of a crystal grain, using a field emission type scanning electron microscope to create an inclination angle frequency distribution graph, the upper layer and the interlayer contact layer of the tool show an inclination angle frequency distribution graph in which the highest peak exists in an inclination angle section within the ranges of 30 to 45 and 75 to 90 degrees, respectively, and the total of frequencies existing in the inclination angle sections occupies 50% or more of the whole frequency, and also the surface roughness of the reformed α-type Al<SB>2</SB>O<SB>3</SB>layer is set to Ra: 0.2 μm or less. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

この発明は、自身が高い粘性を有し、かつ切削時の切削工具表面部の硬質被覆層に対する粘着性も高く、この結果切削抵抗のきわめて高いものとなる軟鋼やステンレス鋼、さらに高マンガン鋼などの難削材の高速切削加工で、硬質被覆層がすぐれた耐チッピング性を示し、長期に亘ってすぐれた耐摩耗性を発揮する表面被覆サーメット製切削工具（以下、被覆サーメット工具という）に関するものである。   This invention has a high viscosity, and has a high adhesion to the hard coating layer on the surface of the cutting tool during cutting. As a result, mild steel, stainless steel, and high manganese steel that have extremely high cutting resistance. This is a surface-coated cermet cutting tool (hereinafter referred to as a coated cermet tool) that exhibits excellent chipping resistance with a hard coating layer in high-speed cutting of difficult-to-cut materials, and exhibits excellent wear resistance over a long period of time. It is.

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層以上からなり、かつ３〜２０μｍの合計平均層厚を有するＴｉ化合物層、
（ｂ）上部層が、１〜１５μｍの平均層厚を有し、かつ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、従来α型Ａｌ₂Ｏ₃層という）、
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サーメット工具が知られており、この被覆サーメット工具が、例えば各種の鋼や鋳鉄などの切削加工に用いられることは良く知られるところである。 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). A Ti compound layer having a total average layer thickness of 3 to 20 μm, including one or two or more of a layer and a carbonitride oxide (hereinafter referred to as TiCNO) layer,
(B) The upper layer has an average layer thickness of 1 to 15 μm and has an α-type crystal structure in a state of chemical vapor deposition (hereinafter referred to as a conventional α-type Al ₂ O ₃ layer),
A coated cermet tool formed by vapor-depositing a hard coating layer composed of (a) and (b) above is known, and this coated cermet tool is used for cutting various steels and cast irons, for example. Is well known.

また、上記の被覆サーメット工具において、これの硬質被覆層の構成層は、一般に粒状結晶組織を有し、さらに、下部層であるＴｉ化合物層を構成するＴｉＣＮ層を、層自身の強度向上を目的として、通常の化学蒸着装置にて、反応ガスとして有機炭窒化物を含む混合ガスを使用し、７００〜９５０℃の中温温度域で化学蒸着することにより形成して縦長成長結晶組織をもつようにすることも知られている。
特開平６−３１５０３号公報 特開平６−８０１０号公報 Further, in the above-described coated cermet tool, the constituent layer of the hard coating layer generally has a granular crystal structure, and further, the TiCN layer constituting the Ti compound layer as the lower layer is intended to improve the strength of the layer itself. In a normal chemical vapor deposition apparatus, a gas mixture containing organic carbonitrides is used as a reaction gas, and it is formed by chemical vapor deposition at an intermediate temperature range of 700 to 950 ° C. so that it has a vertically grown crystal structure. It is also known to do.
Japanese Unexamined Patent Publication No. 6-31503 Japanese Patent Laid-Open No. 6-8010

近年の切削装置の高性能化はめざましく、一方で切削加工に対する省力化および省エネ化、さらに低コスト化の要求は強く、これに伴い、切削加工は一段と高速化の傾向にあるが、上記の従来被覆サーメット工具においては、特にこれを軟鋼やステンレス鋼、さらに高マンガン鋼などの難削材の切削加工を高速切削条件で行なうのに用いた場合には、前記難削材自身が高い粘性を有し、かつ切削時の切削工具表面部の硬質被覆層に対する粘着性も高く、この傾向は高速切削時に発生する高熱によって一段と増大することと相俟って、切削抵抗のきわめて高いものとなり、一方硬質被覆層を構成する従来α型Ａｌ₂Ｏ₃層の高温強度はこれに耐えるに十分なものではなく、この結果切刃部にチッピング（微少欠け）が発生し易くなり、これが原因で比較的短時間で使用寿命に至るのが現状である。 In recent years, the performance of cutting machines has been remarkable. On the other hand, there is a strong demand for labor saving, energy saving, and cost reduction for cutting work, and along with this, cutting work tends to be further accelerated. In the case of coated cermet tools, especially when they are used to cut difficult-to-cut materials such as mild steel, stainless steel, and high-manganese steel under high-speed cutting conditions, the difficult-to-cut materials themselves have high viscosity. However, the adhesiveness to the hard coating layer on the surface of the cutting tool during cutting is also high, and this tendency, combined with the further increase due to the high heat generated during high-speed cutting, results in extremely high cutting resistance, while hard The high-temperature strength of the conventional α-type Al ₂ O ₃ layer that constitutes the coating layer is not sufficient to withstand this, and as a result, chipping (slight chipping) tends to occur at the cutting edge. At present, the service life is reached in a relatively short time.

そこで、本発明者等は、上述のような観点から、上記の従来α型Ａｌ₂Ｏ₃層が硬質被覆層の上部層を構成する被覆サーメット工具に着目し、特に前記従来α型Ａｌ₂Ｏ₃層の耐チッピング性向上を図るべく研究を行った結果、
（ａ）上記の従来被覆サーメット工具の硬質被覆層としての従来α型Ａｌ₂Ｏ₃層は、一般に、通常の化学蒸着装置にて、
反応ガス組成：容量％で、ＡｌＣｌ₃：１〜５％、ＣＯ₂：３〜７％、ＨＣｌ：０．３〜３％、Ｈ₂Ｓ：０．０２〜０．４％、Ｈ₂：残り、
反応雰囲気温度：９５０〜１１００℃、
反応雰囲気圧力：６〜１３ｋＰａ、
の条件（以下、通常条件という）で形成されるが、この通常条件形成の従来α型Ａｌ₂Ｏ₃層について、電界放出型走査電子顕微鏡を用い、図１（ａ），（ｂ）および図２（ａ），（ｂ）に概略説明図で示される通り、工具基体表面と平行な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、前記研磨面の法線に対して、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、それぞれ０〜４５度および４５〜９０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すると、図５（測定傾斜角：０〜４５度）および図６（測定傾斜角：４５〜９０度）に例示される通り、（０００１）面の測定傾斜角の分布が０〜４５度および４５〜９０度のいずれの範囲内でも不偏的な傾斜角度数分布グラフを示すこと。 In view of the above, the present inventors have focused on the coated cermet tool in which the conventional α-type Al ₂ O ₃ layer constitutes the upper layer of the hard coating layer, and particularly the conventional α-type Al ₂ O 3. As a result of research to improve chipping resistance of _three layers,
(A) The conventional α-type Al ₂ O ₃ layer as the hard coating layer of the conventional coated cermet tool is generally a normal chemical vapor deposition apparatus,
Reaction gas composition: by _{volume%, AlCl 3: 1~5%,} CO 2: 3~7%, HCl: 0.3~3%, H 2 S: 0.02~0.4%, H 2: remainder ,
Reaction atmosphere temperature: 950-1100 ° C.
Reaction atmosphere pressure: 6-13 kPa,
The conventional α-type Al ₂ O ₃ layer formed under the normal conditions is formed using a field emission scanning electron microscope, and is shown in FIGS. 1 (a), 1 (b) and FIG. 2 (a) and (b), as schematically shown in the drawing, each crystal grain having a hexagonal crystal lattice existing within the measurement range of the polished surface parallel to the tool substrate 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 with respect to the normal line of the polished surface. Of the measured inclination angles, 0 to 45 degrees and 45 to 90 degrees, respectively. When the measured inclination angle within the range is divided for each pitch of 0.25 degrees, and an inclination angle number distribution graph is created by summing up the frequencies existing in each division, FIG. 45 degrees) and FIG. 6 (measurement tilt angle: 45 to 90 degrees), The distribution of the measured inclination angle of the (0001) plane should be an unbiased inclination angle number distribution graph regardless of the range of 0 to 45 degrees and 45 to 90 degrees.

（ｂ）一方、α型Ａｌ₂Ｏ₃層を、同じく通常の化学蒸着装置を用い、
反応ガス組成：容量％で、ＡｌＣｌ₃：３〜１０％、ＣＯ₂：０．５〜３％、ＨＣｌ：０．３〜３％、ＳＦ_６：０．０１〜０．２％、Ｃ_２Ｈ_４：０．０１〜０．３％、Ｈ₂：残り、
反応雰囲気温度：９５０〜１０５０℃、
反応雰囲気圧力：２０〜３０ｋＰａ、
の条件、すなわち反応ガス組成を調整して上記の通常条件の反応ガス組成とは異なった反応ガス組成とすると共に、同じく上記の通常条件の反応雰囲気の温度および圧力に比して、相対的に低温高圧条件した条件で形成すると、この結果形成されたα型Ａｌ₂Ｏ₃層は、同じく電界放出型走査電子顕微鏡を用い、図１（ａ），（ｂ）に示される通り、工具基体表面と平行な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、前記研磨面の法線に対して、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、図３に例示される通り、傾斜角区分の特定位置にシャープな最高ピークが現れ、試験結果によれば、上記のα型Ａｌ₂Ｏ₃層の形成条件、すなわち上記の反応ガス組成および反応雰囲気条件のうちの少なくともいずれかの条件を、上記の範囲内で変化させると、上記シャープな最高ピークの現れる位置が傾斜角区分の３０〜４５度の範囲内で変化すると共に、前記３０〜４５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５０％以上の割合を占めるようになり、この結果の傾斜角度数分布グラフにおいて３０〜４５度の範囲内に傾斜角区分の最高ピークが現れるα型Ａｌ₂Ｏ₃層（以下、改質α型Ａｌ₂Ｏ₃層という）は、上記の通常条件形成の従来α型Ａｌ₂Ｏ₃層に比して、一段とすぐれた高温強度を有するものであること。 (B) On the other hand, the α-type Al ₂ O ₃ layer was similarly used with a normal chemical vapor deposition apparatus,
Reaction gas composition:% by volume, AlCl ₃ : 3 to 10%, CO ₂ : 0.5 to 3%, HCl: 0.3 to 3%, SF ₆ : 0.01 to 0.2%, C ₂ H _{4: 0.01~0.3%,} H _2: remainder,
Reaction atmosphere temperature: 950 to 1050 ° C.
Reaction atmosphere pressure: 20-30 kPa,
In other words, the reaction gas composition is adjusted to a reaction gas composition different from the reaction gas composition under the normal conditions described above, and in comparison with the temperature and pressure of the reaction atmosphere under the normal conditions. When formed under the conditions of low temperature and high pressure, the α-type Al ₂ O ₃ layer formed as a result of the same was obtained using the field emission scanning electron microscope, as shown in FIGS. 1 (a) and 1 (b). The crystal grains having a hexagonal crystal lattice existing in the measurement range of the polished surface parallel to the electron beam are irradiated with an electron beam, and are the crystal planes of the crystal grains with respect to the normal line of the polished surface (0001) The tilt angle formed by the normal of the surface is measured, and among the measured tilt angles, the measured tilt angles within the range of 0 to 45 degrees are divided for each pitch of 0.25 degrees and exist in each section. When represented by a graph showing the distribution of the number of tilt angles In this case, as illustrated in FIG. 3, a sharp maximum peak appears at a specific position of the tilt angle section. According to the test results, the formation conditions of the α-type Al ₂ O ₃ layer, that is, the reaction gas composition and When at least one of the reaction atmosphere conditions is changed within the above range, the position at which the sharpest peak appears changes within the range of 30 to 45 degrees of the tilt angle section, and the above 30 to The total of the frequencies existing in the 45 degree range occupies a ratio of 50% or more of the entire frequency in the inclination angle frequency distribution graph, and in the resulting inclination angle frequency distribution graph, it is in the range of 30 to 45 degrees. The α-type Al ₂ O ₃ layer (hereinafter referred to as a modified α-type Al ₂ O ₃ layer) in which the highest peak of the tilt angle section appears is compared with the conventional α-type Al ₂ O ₃ layer formed under the above normal conditions, Excellent high temperature strength It must be something.

（ｃ）さらに、同じく、通常の化学蒸着装置を用い、
反応ガス組成：容量％で、ＡｌＣｌ₃：１〜５％、ＣＯ₂：３〜７％、ＨＣｌ：０．３〜３％、Ｈ₂Ｓ：０．０２〜０．４％、Ｈ₂：残り、
反応雰囲気温度：７５０〜９００℃、
反応雰囲気圧力：２０〜３０ｋＰａ、
の条件でα型Ａｌ₂Ｏ₃層を０．１〜１．９μｍの平均層厚で形成すると、この結果形成されたα型Ａｌ₂Ｏ₃層は、同じくα型の結晶構造を有し、電界放出型走査電子顕微鏡を用い、図２（ａ），（ｂ）に示される通り、同じく上記工具基体表面と平行な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、前記研磨面の法線に対して、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、４５〜９０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、図４に例示される通り、傾斜角区分の特定位置にシャープな最高ピークが現れ、試験結果によれば、化学蒸着装置における反応雰囲気温度および圧力を、上記の通り７５０〜９００℃および２０〜３０ｋＰａの範囲内で変化させると、上記シャープな最高ピークの現れる位置が傾斜角区分の７５〜９０度の範囲内で変化すると共に、前記７５〜９０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５０％以上の割合を占めるようになり、この結果の傾斜角度数分布グラフにおいて７５〜９０度の範囲内に傾斜角区分の最高ピークが現れるＡｌ₂Ｏ₃層（以下、密着α型Ａｌ₂Ｏ₃層という）は、上記の改質α型Ａｌ₂Ｏ₃層（上部層）およびＴｉ化合物層（下部層）のいずれにも著しく強固に密着する特性を具備すること。 (C) Furthermore, using a normal chemical vapor deposition apparatus,
Reaction gas composition: by _{volume%, AlCl 3: 1~5%,} CO 2: 3~7%, HCl: 0.3~3%, H 2 S: 0.02~0.4%, H 2: remainder ,
Reaction atmosphere temperature: 750 to 900 ° C.
Reaction atmosphere pressure: 20-30 kPa,
When the α type the Al ₂ O ₃ layer at conditions to form with an average layer thickness of 0.1～1.9Myuemu, the result formed α-type Al ₂ O ₃ layer is also has a α-type crystal structure, Using a field emission scanning electron microscope, as shown in FIGS. 2A and 2B, each crystal grain having a hexagonal crystal lattice, which is also present in the measurement range of the polished surface parallel to the tool substrate surface, is used. By irradiating 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 with respect to the normal line of the polished surface. FIG. 4 shows an example of a tilt angle distribution graph in which the measured tilt angles within a range of degrees are divided into pitches of 0.25 degrees and the frequencies existing in each section are tabulated. A sharp peak appears at a specific position in the slope angle section. When the reaction atmosphere temperature and pressure are changed within the range of 750 to 900 ° C. and 20 to 30 kPa as described above, the position at which the sharpest peak appears changes within the range of 75 to 90 degrees of the inclination angle section. At the same time, the sum of the frequencies existing within the range of 75 to 90 degrees occupies a ratio of 50% or more of the entire frequencies in the inclination angle distribution graph, and 75 to 90 in the inclination angle distribution graph as a result. The Al ₂ O ₃ layer (hereinafter referred to as the adhesion α-type Al ₂ O ₃ layer) in which the highest peak of the tilt angle section appears in the range of degrees is the above-mentioned modified α-type Al ₂ O ₃ layer (upper layer) and Ti It must have the property of adhering remarkably firmly to any of the compound layers (lower layers).

（ｄ）また、上記の被覆サーメット工具の硬質被覆層の上部層を構成する改質α型Ａｌ₂Ｏ₃層は、相対的に蒸着表面が粗いのが現状である。そこで、前記改質α型Ａｌ₂Ｏ₃層の全面に、
通常の化学蒸着装置を用い、通常の条件、例えば表３に示される条件で、かつ、０．５〜５μｍの平均層厚で、窒化チタン（以下、ＴｉＮで示す）層を蒸着形成した状態で、
ウエットブラストにて、噴射研磨材として、水との合量に占める割合で１５〜６０質量％の酸化アルミニウム微粒（以下、Ａｌ₂Ｏ₃微粒で示す）を配合した研磨液を噴射すると、上記ＴｉＮ層（以下、ＴｉＮ研磨材層という）は、前記Ａｌ₂Ｏ₃微粒によって粉砕微粒化し、ＴｉＮ微粒となって前記Ａｌ₂Ｏ₃微粒の共存下で研磨材として作用し、硬質被覆層の上部層を構成する改質α型Ａｌ₂Ｏ₃層の表面を研磨することになり、この結果研磨後の前記改質α型Ａｌ₂Ｏ₃層の表面は、準拠規格ＪＩＳ・Ｂ０６０１−１９９４に基いた測定（以下の表面粗さは全てかかる準拠規格に基いた測定値を示す）で、Ｒａ：０．２μｍ以下の表面粗さにまで平滑化されるようになり、この上部層である改質α型Ａｌ₂Ｏ₃層の表面がＲａ：０．２μｍ以下の表面粗さに平滑化した上記の被覆サーメット工具を用いて、難削材の高速切削加工を行った場合、３５０ｍ／ｍｉｎ．を越える切削速度でも前記表面粗さの平滑化によって前記改質α型Ａｌ₂Ｏ₃層の摩耗進行が抑制されるようになり、この結果工具の使用寿命の一段の延命化が可能となること。
なお、この場合、上記改質α型Ａｌ₂Ｏ₃層の表面に、上記のＴｉＮ研磨材層を形成することなく、これに同じくウエットブラストにて、噴射研磨材として、水との合量に占める割合で１５〜６０質量％のＡｌ₂Ｏ₃微粒を配合した研磨液を直接噴射して、研磨しても、前記改質α型Ａｌ₂Ｏ₃層の表面は、Ｒａ：０．３〜０．６μｍの表面粗さにしか研磨されず、この結果の表面粗さがＲａ：０．３〜０．６μｍの改質α型Ａｌ₂Ｏ₃層で上部層を構成した被覆サーメット工具を用いても、切削速度が３５０ｍ／ｍｉｎ．を越えた難削材の高速切削加工では表面平滑化による摩耗抑制効果が十分に発揮されず、満足な使用寿命の延命化は図れないこと。 (D) In addition, the modified α-type Al ₂ O ₃ layer constituting the upper layer of the hard coating layer of the above-described coated cermet tool has a relatively rough deposition surface. Therefore, on the entire surface of the modified α-type Al ₂ O ₃ layer,
In a state in which a titanium nitride (hereinafter referred to as TiN) layer is formed by vapor deposition under normal conditions, for example, conditions shown in Table 3 and an average layer thickness of 0.5 to 5 μm, using a normal chemical vapor deposition apparatus. ,
When a polishing liquid containing 15 to 60% by mass of aluminum oxide fine particles (hereinafter referred to as Al ₂ O ₃ fine particles) is injected as a polishing material by wet blasting as a proportion of the total amount with water, the above TiN The layer (hereinafter referred to as TiN abrasive layer) is pulverized and pulverized by the Al ₂ O ₃ fine particles, becomes TiN fine particles and acts as an abrasive in the presence of the Al ₂ O ₃ fine particles, and is an upper layer of the hard coating layer. It will be polishing the surface of the modified α type the Al ₂ O ₃ layer constituting the surface of the reformed α-type the Al ₂ O ₃ layer after the results polishing, based on compliance JIS · B0601-1994 In measurement (the following surface roughnesses are all measured values based on such standards), Ra is smoothed to a surface roughness of 0.2 μm or less. Type Al ₂ O ₃ layer surface is Ra: 0.2 μm or less When the above-mentioned coated cermet tool smoothed to a surface roughness of 5 mm was subjected to high-speed cutting of a difficult-to-cut material, 350 m / min. Even at cutting speeds exceeding 1, the progress of wear of the modified α-type Al ₂ O ₃ layer can be suppressed by smoothing the surface roughness, and as a result, the life of the tool can be further increased. .
In this case, the TiN abrasive layer is not formed on the surface of the modified α-type Al ₂ O ₃ layer, and the same amount of water as the spray abrasive is also formed by wet blasting. Even if the polishing liquid containing 15 to 60% by mass of Al ₂ O ₃ fine particles is directly sprayed and polished, the surface of the modified α-type Al ₂ O ₃ layer is Ra: 0.3 to Using a coated cermet tool whose upper surface is composed of a modified α-type Al ₂ O ₃ layer whose surface roughness is Ra: 0.3 to 0.6 μm, which is polished only to a surface roughness of 0.6 μm. However, the cutting speed is 350 m / min. In the high-speed cutting of difficult-to-cut materials that exceed the limit, the wear suppression effect due to surface smoothing cannot be fully exhibited, and the life of the satisfactory service life cannot be extended.

（ｅ）したがって、上部層を、１．５〜５．９μｍの相対的に薄い平均層厚に特定した上で、すぐれた高温強度を有する上記改質α型Ａｌ₂Ｏ₃層で構成すると共に、前記上部層と下部層であるＴｉ化合物層の間に、これら両者と著しく強固に密着する上記密着α型Ａｌ₂Ｏ₃層を、０．１〜１．９μｍの平均層厚で介在させ、さらに、前記改質α型Ａｌ₂Ｏ₃層の少なくとも切刃稜線部を含むすくい面部分および逃げ面部分を研磨して、これら研磨面の表面粗さをＲａ：０．２μｍ以下とした構造の硬質被覆層を、上記工具基体の表面に蒸着形成してなる被覆サーメット工具は、特に切刃部にきわめて高い切削抵抗が加わる難削材の高速切削加工でも、前記硬質被覆層の高温強度が向上し、かつ前記上部層の改質α型Ａｌ₂Ｏ₃層がすぐれた表面平滑性を具備することと相俟って、すぐれた耐チッピング性を発揮し、長期に亘ってすぐれた耐摩耗性を示すようになること。
以上（ａ）〜（ｅ）に示される研究結果を得たのである。 (E) Therefore, the upper layer is specified by a relatively thin average layer thickness of 1.5 to 5.9 μm, and is composed of the modified α-type Al ₂ O ₃ layer having excellent high-temperature strength. In addition, the adhesion α-type Al ₂ O ₃ layer that is extremely firmly adhered to both the upper layer and the lower Ti compound layer is interposed with an average layer thickness of 0.1 to 1.9 μm, Further, the rake face portion and the flank face portion including at least the cutting edge ridge line portion of the modified α-type Al ₂ O ₃ layer are polished, and the surface roughness of these polished surfaces is set to Ra: 0.2 μm or less. The coated cermet tool formed by vapor-depositing a hard coating layer on the surface of the tool base improves the high-temperature strength of the hard coating layer, especially in high-speed cutting of difficult-to-cut materials that add extremely high cutting resistance to the cutting edge. And the modified α-type Al ₂ O ₃ layer of the upper layer is excellent in surface flatness. Combined with the lubricity, it exhibits excellent chipping resistance and exhibits excellent wear resistance over a long period of time.
The research results shown in (a) to (e) above were obtained.

この発明は、上記の研究結果に基づいてなされたものであって、工具基体の表面に、
（１）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層以上からなり、かつ３〜２０μｍの合計平均層厚を有するＴｉ化合物層、
（２）上記下部層と下記上部層の層間密着層として、化学蒸着した状態でα型の結晶構造を有し、電界放出型走査電子顕微鏡を用い、上記工具基体表面と平行な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、前記研磨面の法線に対して、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、４５〜９０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において、
７５〜９０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７５〜９０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５０％以上の割合を占める傾斜角度数分布グラフを示し、かつ０．１〜１．９μｍの平均層厚を有する密着α型Ａｌ₂Ｏ₃層、
（３）上部層として、同じく、化学蒸着した状態でα型の結晶構造を有し、電界放出型走査電子顕微鏡を用い、上記工具基体表面と平行な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、前記研磨面の法線に対して、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において、
３０〜４５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３０〜４５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５０％以上の割合を占める傾斜角度数分布グラフを示し、かつ１．５〜５．９μｍの平均層厚を有する改質α型Ａｌ₂Ｏ₃層、
以上（１）〜（３）で構成された硬質被覆層を蒸着形成してなり、
さらに、上記硬質被覆層の上部層である改質α型Ａｌ₂Ｏ₃層の全面に、
０．５〜５μｍの平均層厚で、ＴｉＮ研磨材層を蒸着形成した状態で、
ウエットブラストにて、噴射研磨材として、水との合量に占める割合で１５〜６０質量％のＡｌ₂Ｏ₃微粒を配合した研磨液を噴射し、
上記のＴｉＮ研磨材層のウエットブラストによる粉砕化ＴｉＮ微粒と、噴射研磨材としてのＡｌ₂Ｏ₃微粒の共存下で、上記硬質被覆層の上部層を構成する改質α型Ａｌ₂Ｏ₃層の少なくとも切刃稜線部を含むすくい面部分および逃げ面部分を研磨して、これら研磨面の表面粗さをＲａ：０．２μｍ以下としてなる、
難削材の高速切削加工で硬質被覆層がすぐれた耐チッピング性を発揮する被覆サーメット工具に特徴を有するものである。 This invention was made based on the above research results, and on the surface of the tool base,
(1) As a lower layer, a Ti compound layer composed of one or more of a TiC layer, a TiN layer, a TiCN layer, a TiCO layer, and a TiCNO layer, and having a total average layer thickness of 3 to 20 μm,
(2) As an interlayer adhesion layer between the lower layer and the upper layer described below, a polished surface parallel to the tool base surface is obtained using a field emission scanning electron microscope having an α-type crystal structure in the state of chemical vapor deposition. Inclination made by irradiating an electron beam to each crystal grain having a hexagonal crystal lattice existing in the range and a normal line of the (0001) plane being the crystal plane of the crystal grain with respect to the normal line of the polished surface An angle is measured, and the measured inclination angle within the range of 45 to 90 degrees is divided into 0.25 degree pitches among the measured inclination angles, and the degrees existing in each division are totaled. In the angle distribution graph,
The highest peak exists in the inclination angle section in the range of 75 to 90 degrees, and the total of the frequencies existing in the range of 75 to 90 degrees represents a ratio of 50% or more of the entire degrees in the inclination angle frequency distribution graph. A close contact α-type Al ₂ O ₃ layer showing an inclination angle number distribution graph and having an average layer thickness of 0.1 to 1.9 μm;
(3) As an upper layer, a hexagonal crystal having an α-type crystal structure in the state of chemical vapor deposition and existing in a measurement range of a polished surface parallel to the tool base surface using a field emission scanning electron microscope By irradiating each crystal grain having a crystal lattice 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 with respect to the normal line of the polished surface. In the inclination angle number distribution graph formed by totaling the frequencies existing in each division, while dividing the measurement inclination angle in the range of 0 to 45 degrees among the inclination angles for each pitch of 0.25 degrees,
The highest peak exists in the inclination angle section within the range of 30 to 45 degrees, and the total of the frequencies existing within the range of 30 to 45 degrees represents a ratio of 50% or more of the entire degrees in the inclination angle frequency distribution graph. A modified α-type Al ₂ O ₃ layer showing an occupying inclination number distribution graph and having an average layer thickness of 1.5 to 5.9 μm;
The hard coating layer composed of the above (1) to (3) is formed by vapor deposition,
Furthermore, on the entire surface of the modified α-type Al ₂ O ₃ layer, which is the upper layer of the hard coating layer,
With an average layer thickness of 0.5-5 μm, with a TiN abrasive layer deposited,
In wet blasting, as a spraying abrasive, a polishing liquid containing 15 to 60% by mass of Al ₂ O ₃ fine particles in a proportion of the total amount with water is sprayed,
The modified α-type Al ₂ O ₃ layer constituting the upper layer of the hard coating layer in the presence of the TiN fine particles pulverized by wet blasting of the TiN abrasive layer and the Al ₂ O ₃ fine particles as the spray abrasive The rake face portion including at least the cutting edge ridge line portion and the flank portion are polished, and the surface roughness of these polished surfaces is Ra: 0.2 μm or less.
It is characterized by a coated cermet tool that exhibits excellent chipping resistance with a hard coating layer in high-speed cutting of difficult-to-cut materials.

以下に、この発明の被覆サーメット工具の硬質被覆層、研磨材層、さらにウエットブラストで用いられる研磨液のＡｌ₂Ｏ₃微粒に関して、上記の通りに数値限定した理由を説明する。
（Ａ）硬質被覆層
（ａ−１）Ｔｉ化合物層（下部層）
Ｔｉ化合物層は、基本的には改質α型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するほか、工具基体と密着α型Ａｌ₂Ｏ₃層のいずれにも強固に密着し、よって硬質被覆層の工具基体に対する密着性向上に寄与する作用を有するが、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、特に高熱発生を伴なう難削材の高速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。 The reason why the hard coating layer of the coated cermet tool of the present invention, the abrasive layer, and the Al ₂ O ₃ fine particles of the polishing liquid used in wet blasting are numerically limited as described above will be described below.
(A) Hard coating layer (a-1) Ti compound layer (lower layer)
The Ti compound layer basically exists as a lower layer of the modified α-type Al ₂ O ₃ layer, and allows the hard coating layer to have high-temperature strength by its excellent high-temperature strength. And tightly adhere to any of the α-type Al ₂ O ₃ layers, and thus contribute to improving the adhesion of the hard coating layer to the tool substrate. However, when the total average layer thickness is less than 3 μm, On the other hand, if the total average layer thickness exceeds 20 μm, it becomes easy to cause thermoplastic deformation particularly in high-speed cutting of difficult-to-cut materials with high heat generation, which causes uneven wear. Therefore, the total average layer thickness was determined to be 3 to 20 μm.

（ａ−２）改質α型Ａｌ₂Ｏ₃層（上部層）
上記の通り、改質α型Ａｌ₂Ｏ₃層の傾斜角度数分布グラフにおける測定傾斜角の最高ピーク位置および度数分布割合は、反応ガス組成および反応雰囲気条件のうちの少なくともいずれかの条件を、上記の範囲内で変化させることによって変化するが、試験結果によれば、最高ピークが、３０〜４５度の範囲内の傾斜角区分に現れると共に、前記３０〜４５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５０％以上の割合を占める傾斜角度数分布グラフを示す場合に、α型Ａｌ₂Ｏ₃自身のもつすぐれた高温硬さおよび耐熱性に加えて、すぐれた高温強度を具備するようになるものである。
また、その平均層厚が１．５μｍ未満では、上記の特性を硬質被覆層に十分に具備せしめることができず、一方、その平均層厚が５．９μｍを越えると、難削材の高速切削加工ではチッピングが発生し易くなることから、その平均層厚を１．５〜５．９μｍと定めた。 (A-2) Modified α-type Al ₂ O ₃ layer (upper layer)
As described above, the maximum peak position and the frequency distribution ratio of the measured inclination angle in the inclination angle number distribution graph of the modified α-type Al ₂ O ₃ layer are at least one of the reaction gas composition and the reaction atmosphere conditions. Although it changes by changing within the above range, according to the test results, the highest peak appears in the inclination angle section within the range of 30 to 45 degrees and the frequency existing within the range of 30 to 45 degrees. In addition to the excellent high-temperature hardness and heat resistance of α-type Al ₂ O ₃ itself, when the inclination angle distribution graph occupies 50% or more of the total frequency in the inclination angle distribution graph It will have excellent high temperature strength.
If the average layer thickness is less than 1.5 μm, the hard coating layer cannot be sufficiently provided with the above characteristics. On the other hand, if the average layer thickness exceeds 5.9 μm, high-speed cutting of difficult-to-cut materials is possible. Since chipping is likely to occur during processing, the average layer thickness is set to 1.5 to 5.9 μm.

（ａ−３）密着α型Ａｌ₂Ｏ₃層（層間密着層）
上記の通り、密着α型Ａｌ₂Ｏ₃層の傾斜角度数分布グラフにおける測定傾斜角の最高ピーク位置および度数分布割合は、化学蒸着装置における反応雰囲気温度および圧力を、上記の通り７５０〜９００℃および２０〜３０ｋＰａの範囲内で変化させることによって変化するが、試験結果によれば、最高ピークが７５〜９０度の範囲内の傾斜角区分に現れると共に、前記７５〜９０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５０％以上の割合を占める傾斜角度数分布グラフを示す場合に、上記の上部層（改質α型Ａｌ₂Ｏ₃層）および下部層（Ｔｉ化合物）のいずれに対しても、すぐれた密着性を示すようになるのである。
また、その平均層厚が０．１μｍ未満では、所望のすぐれた密着性を確保することができず、一方、その平均層厚が１．９μｍを越えると、難削材の高速切削加工ではチッピングが発生し易くなることから、その平均層厚を０．１〜１．９μｍと定めた。 (A-3) Adhesive α-type Al ₂ O ₃ layer (interlayer adhesion layer)
As described above, the maximum peak position and the frequency distribution ratio of the measured inclination angle in the inclination angle number distribution graph of the contact α-type Al ₂ O ₃ layer are the reaction atmosphere temperature and pressure in the chemical vapor deposition apparatus as described above, 750 to 900 ° C. However, according to the test results, the highest peak appears in the inclination angle section in the range of 75 to 90 degrees, and exists in the range of 75 to 90 degrees. summing the power is to indicate an inclination angle frequency distribution graph in a proportion of 50% or more of the total power at the inclination angle frequency distribution graph, the above upper layer (reformed α-type the Al ₂ O ₃ layer) and a lower layer For any of the (Ti compounds), excellent adhesion is exhibited.
On the other hand, if the average layer thickness is less than 0.1 μm, the desired excellent adhesion cannot be ensured. On the other hand, if the average layer thickness exceeds 1.9 μm, chipping is required for high-speed cutting of difficult-to-cut materials. Therefore, the average layer thickness was determined to be 0.1 to 1.9 μm.

（Ｂ）ＴｉＮ研磨材層
上記の通り、ＴｉＮ研磨材層は、ウエットブラスト時に、研磨液に噴射研磨材として配合したＡｌ₂Ｏ₃微粒によって粉砕微粒化し、ＴｉＮ微粒となって前記Ａｌ₂Ｏ₃微粒との共存下で研磨材として作用し、硬質被覆層の上部層を構成する改質α型Ａｌ₂Ｏ₃層の表面を研磨するが、この場合、その平均層厚が０．５μｍ未満では、ウエットブラスト時における粉砕化ＴｉＮ微粒の割合が少な過ぎて、研磨機能を十分に発揮することができず、一方、その平均層厚が５μｍを越えると、研磨液に噴射研磨材として配合したＡｌ₂Ｏ₃微粒とのバランスがくずれて、相対的に多くなり過ぎ、この場合も研磨機能が急激に低下するようになり、いずれの場合もα型Ａｌ₂Ｏ₃層の表面をＲａ：０．２μｍ以下の表面粗さに研磨することができなくなるという理由で、その平均層厚を０．５〜５μｍと定めた。 (B) TiN abrasive layer As described above, TiN abrasive layer during wet blasting, the Al ₂ O ₃ fine formulated as injection abrasive in the polishing liquid milled micronized, the Al ₂ O ₃ becomes TiN fine Acts as an abrasive in the presence of fine particles and polishes the surface of the modified α-type Al ₂ O ₃ layer constituting the upper layer of the hard coating layer. In this case, if the average layer thickness is less than 0.5 μm When the average layer thickness exceeds 5 μm, the proportion of pulverized TiN fine particles at the time of wet blasting is too small to sufficiently exert the polishing function. The balance with the ₂ O ₃ fine particles is lost and becomes relatively large. In this case as well, the polishing function is suddenly lowered. In either case, the surface of the α-type Al ₂ O ₃ layer is set to Ra: 0. Polish to a surface roughness of 2 μm or less It because it becomes impossible to determine the average layer thickness and 0.5 to 5 [mu] m.

（Ｃ）研磨液のＡｌ₂Ｏ₃微粒
研磨液のＡｌ₂Ｏ₃微粒には、ウエットブラスト時にＴｉＮ研磨材層の粉砕化ＴｉＮ微粒と共存した状態で、改質α型Ａｌ₂Ｏ₃層の表面を研磨する作用があるが、その割合が水との合量に占める割合で１５質量％未満でも、また６０質量％を越えても研磨機能が急激に低下するようになることから、その割合を１５〜６０質量％と定めた。 (C) Polishing Al ₂ O ₃ Fine Particles In the polishing liquid Al ₂ O ₃ fine particles, the modified α-type Al ₂ O ₃ layer coexists with the ground TiN fine particles of the TiN abrasive layer during wet blasting. There is an action to polish the surface, but even if the ratio is less than 15% by mass or more than 60% by mass with respect to the total amount with water, the polishing function will rapidly decrease, so that ratio Was determined to be 15 to 60% by mass.

この発明の被覆サーメット工具は、硬質被覆層の上部層を構成する改質α型Ａｌ₂Ｏ₃層がα型Ａｌ₂Ｏ₃自身のもつすぐれた高温硬さおよび耐熱性に加えて、すぐれた高温強度を有し、かつ前記改質α型Ａｌ₂Ｏ₃層とＴｉ化合物層との間に介在させた密着α型Ａｌ₂Ｏ₃層がこれら両者ときわめて強固に密着し、さらに前記改質α型Ａｌ₂Ｏ₃層の表面をＲａ：０．２μｍ以下の表面粗さに研磨することにより、特に切粉の粘性が高く、かつ工具表面に溶着し易いステンレス鋼や高マンガン鋼、さらに軟鋼などの難削材（被削材）の切削加工を高熱発生を伴う高速切削条件で行ない、前記被削材および切粉が高温に加熱されて粘性および溶着性が一段と増大し、これに伴なって硬質被覆層表面に対する切削抵抗が増すようになっても、前記硬質被覆層のもつすぐれた高温強度および平滑な表面粗さによって前記硬質被覆層のチッピング発生が著しく抑制され、かつ摩耗抑制効果も発揮され、この結果長期に亘ってすぐれた耐摩耗性を示すようになるものである。 In the coated cermet tool of the present invention, the modified α-type Al ₂ O ₃ layer constituting the upper layer of the hard coating layer is excellent in addition to the excellent high-temperature hardness and heat resistance of the α-type Al ₂ O ₃ itself. The contact α-type Al ₂ O ₃ layer having high-temperature strength and interposed between the modified α-type Al ₂ O ₃ layer and the Ti compound layer is extremely firmly adhered to both of them, and the modified By polishing the surface of the α-type Al ₂ O ₃ layer to a surface roughness of Ra: 0.2 μm or less, stainless steel, high-manganese steel, and even mild steel that have particularly high chip viscosity and are easily welded to the tool surface When cutting difficult-to-cut materials (work materials) such as high-speed cutting conditions with high heat generation, the work material and chips are heated to a high temperature, which further increases the viscosity and weldability. Even if the cutting resistance against the surface of the hard coating layer increases, the hard coating The excellent high-temperature strength and smooth surface roughness of the covering layer significantly suppresses the occurrence of chipping of the hard coating layer and also exerts an effect of suppressing wear, and as a result, exhibits excellent wear resistance over a long period of time. It will be.

つぎに、この発明の被覆サーメット工具を実施例により具体的に説明する。   Next, the coated cermet 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、中心部に工具取り付け用ボルト貫通孔を有する形式で、ＩＳＯ規格にＣＮＭＧ１２０４１２として規定され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。 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. Thus, a tool base made of a WC-based cemented carbide having a throwaway tip shape defined as CNMG12041 in the ISO standard in the form of having a tool mounting bolt through hole in the center. Each of the bodies A to F was 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Ｒ：０．０７ｍｍのホーニング加工を施すことにより、工具本体にクランプ駒による挟み締めにより取り付けられる穴なし形式で、ＩＳＯ規格にＣＮＭＮ１２０４１２として規定されるスローアウエイ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。 Further, as raw material powders, TiCN (mass ratio, TiC / TiN = 50/50) powder, Mo ₂ C powder, ZrC powder, NbC powder, TaC powder, WC, all having an average particle diameter of 0.5 to 2 μm. Prepare powder, Co powder, and Ni powder, blend these raw material powders into the composition shown in Table 2, wet mix with a ball mill for 24 hours, dry, and press-mold into a green compact at 98 MPa pressure The green compact is sintered in a nitrogen atmosphere of 1.3 kPa at a temperature of 1540 ° C. for 1 hour, and after sintering, the cutting edge portion is subjected to a honing process of R: 0.07 mm. Made of TiCN-based cermet with a throwaway tip shape that is defined as CNMN12041 in the ISO standard, with no holes attached to the tool body by clamping with clamp pieces To form a tool substrate a~f.

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６に示される目標層厚のＴｉ化合物層を硬質被覆層の下部層として蒸着形成し、
（ｂ）ついで、反応ガス組成：容量％で、ＡｌＣｌ₃：４％、ＣＯ₂：１．５％、ＨＣｌ：２％、ＳＦ_６：０．１％、Ｃ_２Ｈ_４：０．１５％、Ｈ₂：残り、
反応雰囲気温度：１０００℃、
反応雰囲気圧力：２０〜３０ｋＰａの範囲内の所定の圧力、
の条件で表６に示される目標層厚で、密着α型Ａｌ₂Ｏ₃層を蒸着形成し、
（ｃ）引き続いて、反応ガス組成：容量％で、ＡｌＣｌ₃：２．２％、ＣＯ₂：１．５％、ＨＣｌ：２％、Ｈ₂Ｓ：０．７５％、Ａｒ：２６．５％、Ｈ₂：残り、
反応雰囲気温度：１０７０℃、
反応雰囲気圧力：２０〜３０ｋＰａの範囲内の所定の圧力、
の条件で同じく表５に示される目標層厚で、同じく上部層として改質α型Ａｌ₂Ｏ₃層を蒸着形成し、
（ｄ）さらに、同じく表３に示される条件でＴｉＮ研磨材層を、同じく表５に示される目標層厚で蒸着形成し、
引き続いて、表４に示されるブラスト条件で、かつ表５に示される組み合わせでウエットブラストを施して、上記工具基体Ａ〜Ｆについては、中心部の工具取り付け用ボルト貫通孔周辺部の上記ＴｉＮ研磨材層は除去せずに残した状態、また、上記の工具基体ａ〜ｆについては、クランプ駒当接面部分（すくい面中心部）の上記ＴｉＮ研磨材層は除去せずに残した状態で、前記改質α型Ａｌ₂Ｏ₃層（上部層）の切刃稜線部を含むすくい面および逃げ面を、同じく表５に示される表面粗さに研磨することにより本発明被覆サーメット工具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. Under the conditions shown in Table 6), the Ti compound layer having the target layer thickness shown in Table 6 is deposited as the lower layer of the hard coating layer,
(B) Next, reaction gas composition: volume%, AlCl ₃ : 4%, CO ₂ : 1.5%, HCl: 2%, SF ₆ : 0.1%, C ₂ H ₄ : 0.15%, H ₂ : Remaining
Reaction atmosphere temperature: 1000 ° C.
Reaction atmosphere pressure: a predetermined pressure in the range of 20-30 kPa,
The adhesion α-type Al ₂ O ₃ layer is formed by vapor deposition at the target layer thickness shown in Table 6 under the conditions of
(C) Subsequently, reaction gas composition: volume%, AlCl ₃ : 2.2%, CO ₂ : 1.5%, HCl: 2%, H ₂ S: 0.75%, Ar: 26.5% , H ₂ : remaining,
Reaction atmosphere temperature: 1070 ° C.
Reaction atmosphere pressure: a predetermined pressure in the range of 20-30 kPa,
The modified α-type Al ₂ O ₃ layer is also formed by vapor deposition with the target layer thickness shown in Table 5 under the same conditions as above,
(D) Furthermore, a TiN abrasive material layer is formed by vapor deposition with the target layer thickness also shown in Table 5 under the same conditions as shown in Table 3.
Subsequently, wet blasting is performed under the blasting conditions shown in Table 4 and in the combinations shown in Table 5, and for the tool bases A to F, the above-described TiN polishing at the peripheral part of the tool mounting bolt through hole is performed. The material layer is left without being removed, and the tool bases a to f are left without removing the TiN abrasive material layer at the clamp piece abutting surface portion (the center portion of the rake face). The rake face and flank face including the cutting edge ridge line portion of the modified α-type Al ₂ O ₃ layer (upper layer) are polished to the surface roughness shown in Table 5 to obtain the coated cermet tool 1 to 1 of the present invention. 13 were produced respectively.

また、比較の目的で、硬質被覆層の上部層である従来α型Ａｌ₂Ｏ₃層の形成を、
反応ガス組成：容量％で、ＡｌＣｌ₃：２．２％、ＣＯ₂：５％、ＨＣｌ：２％、Ｈ₂Ｓ：０．１５％、Ｈ₂：残り、
反応雰囲気温度：１０２０℃、
反応雰囲気圧力：６〜１３ｋＰａの範囲内の所定の圧力、
の通常条件で、表６に示される通りの目標層厚で形成し、同じく表６に示される通り、前記従来α型Ａｌ₂Ｏ₃層と下部層であるＴｉ化合物層の間に層間密着層の形成を行なわず、さらに上記の研磨材層の形成およびウエットブラストによる表面研磨処理も行なわない以外は同一の条件で、従来被覆サーメット工具１〜１３をそれぞれ製造した。 For comparison purposes, the formation of the conventional α-type Al ₂ O ₃ layer, which is the upper layer of the hard coating layer,
Reaction gas composition: volume%, AlCl ₃ : 2.2%, CO ₂ : 5%, HCl: 2%, H ₂ S: 0.15%, H ₂ : remaining,
Reaction atmosphere temperature: 1020 ° C.
Reaction atmosphere pressure: a predetermined pressure in the range of 6 to 13 kPa,
The target layer thickness is as shown in Table 6, and the interlayer adhesion layer is formed between the conventional α-type Al ₂ O ₃ layer and the lower Ti compound layer as shown in Table 6. Conventionally, coated cermet tools 1 to 13 were manufactured under the same conditions except that the above-described abrasive layer formation and surface polishing treatment by wet blasting were not performed.

ついで、上記の本発明被覆サーメット工具１〜１３と従来被覆サーメット工具１〜１３の硬質被覆層の上部層をそれぞれ構成する改質α型Ａｌ₂Ｏ₃層および従来α型Ａｌ₂Ｏ₃層、さらに上記の本発明被覆サーメット工具１〜１３の密着α型Ａｌ₂Ｏ₃層について、電界放出型走査電子顕微鏡を用いて、傾斜角度数分布グラフをそれぞれ作成した。
すなわち、上記傾斜角度数分布グラフは、上記の本発明被覆サーメット工具１〜１３と従来被覆サーメット工具１〜１３の硬質被覆層を構成する各種のα型Ａｌ₂Ｏ₃層について、それぞれ工具基体表面と平行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、前記研磨面の法線に対して、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、前記改質α型Ａｌ₂Ｏ₃層については０〜４５度、前記密着α型Ａｌ₂Ｏ₃層については４５〜９０度、さらに前記従来α型Ａｌ₂Ｏ₃層については０〜４５度および４５〜９０度の範囲内にそれぞれ存在する測定傾斜角を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, a modified α-type Al ₂ O ₃ layer and a conventional α-type Al ₂ O ₃ layer that respectively constitute upper layers of the hard coating layers of the present invention coated cermet tools 1 to 13 and the conventional coated cermet tools 1 to 13, Further, with respect to the close contact α-type Al ₂ O ₃ layers of the above-described coated cermet tools 1 to 13 of the present invention, gradient angle number distribution graphs were respectively prepared using a field emission scanning electron microscope.
That is, the inclination angle number distribution graph shows the surface of the tool base for the various α-type Al ₂ O ₃ layers constituting the hard coating layers of the above-described coated cermet tools 1 to 13 and the conventional coated cermet tools 1 to 13, respectively. With the surfaces parallel to each other as polished surfaces, they are set in the barrel of a field emission scanning electron microscope, and an electron beam with an acceleration voltage of 15 kV at an incident angle of 70 degrees is applied to the polished surfaces with an irradiation current of 1 nA. Each of the crystal grains 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 form a 30 × 50 μm region at an interval of 0.1 μm / step. Then, an inclination angle formed by a normal line of the (0001) plane, which is a crystal plane of the crystal grain, is measured with respect to a normal line of the polished surface. Α-type Al ₂ O 0-45 ° for ₃ layers, 45-90 degrees for the contact α type the Al ₂ O ₃ layer, further wherein for the conventional α type the Al ₂ O ₃ layer in the range of 0-45 degrees and 45-90 degrees Each of the measured inclination angles was divided into pitches of 0.25 degrees, and the frequency existing in each section was totaled.

この結果得られた各種のα型Ａｌ₂Ｏ₃層の傾斜角度数分布グラフにおいて、表７，８にそれぞれ示される通り、本発明被覆サーメット工具１〜１３の改質α型Ａｌ₂Ｏ₃層および密着α型Ａｌ₂Ｏ₃層は、（０００１）面の測定傾斜角の分布が、それぞれ前者では３０〜４５度、後者では７５〜９０度の範囲内の傾斜角区分に最高ピークが現れる傾斜角度数分布グラフを示すのに対して、従来被覆サーメット工具１〜１３の従来α型Ａｌ₂Ｏ₃層は、（０００１）面の測定傾斜角の分布が０〜４５度および４５〜９０度の範囲内で不偏的で、最高ピークが存在しない傾斜角度数分布グラフを示すものであった。
また表７，８には、上記の各種のα型Ａｌ₂Ｏ₃層の傾斜角度数分布グラフにおいて、それぞれ３０〜４５度および７５〜９０度の範囲内の傾斜角区分に存在する全傾斜角度数の傾斜角度数分布グラフ全体に占める割合を示した。
なお、図３は、本発明被覆サーメット工具５の改質α型Ａｌ₂Ｏ₃層（上部層）の傾斜角度数分布グラフ、図４は同密着α型Ａｌ₂Ｏ₃層（層間密着層）の傾斜角度数分布グラフ、図５，６は従来被覆サーメット工具６の従来α型Ａｌ₂Ｏ₃層のそれぞれ０〜４５度および４５〜９０度の傾斜角区分を示す傾斜角度数分布グラフである。 In the inclination angle number distribution graphs of the various α-type Al ₂ O ₃ layers obtained as a result, as shown in Tables 7 and 8, respectively, the modified α-type Al ₂ O ₃ layers of the coated cermet tools 1 to 13 of the present invention. And the close contact α-type Al ₂ O ₃ layer, in which the distribution of the measured inclination angle on the (0001) plane is 30 to 45 degrees in the former and 75 to 90 degrees in the latter, and the inclination in which the highest peak appears in the inclination angle section. In contrast to the angle distribution graph, the conventional α-type Al ₂ O ₃ layer of the conventional coated cermet tools 1 to 13 has a distribution of measured inclination angles on the (0001) plane of 0 to 45 degrees and 45 to 90 degrees. An inclination angle number distribution graph that is unbiased within the range and does not have the highest peak is shown.
Tables 7 and 8 also show the total inclination angles existing in the inclination angle sections in the range of 30 to 45 degrees and 75 to 90 degrees in the inclination angle number distribution graphs of the various α-type Al ₂ O ₃ layers. The ratio of the number to the whole angle distribution graph is shown.
3 is an inclination angle number distribution graph of the modified α-type Al ₂ O ₃ layer (upper layer) of the coated cermet tool 5 of the present invention, and FIG. 4 is the same contact α-type Al ₂ O ₃ layer (interlayer adhesion layer). 5 and 6 are inclination angle distribution graphs showing inclination angle sections of 0 to 45 degrees and 45 to 90 degrees of the conventional α-type Al ₂ O ₃ layer of the conventional coated cermet tool 6, respectively. .

また、この結果得られた本発明被覆サーメット工具１〜１３および従来被覆サーメット工具１〜１３の硬質被覆層の構成層の厚さを、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 the constituent layer of the hard coating layer of the present coated cermet tools 1 to 13 and the conventional coated cermet tools 1 to 13 obtained as a result was measured using a scanning electron microscope (longitudinal section measurement). , Each showed an average layer thickness (average value of 5-point measurement) substantially the same as the target layer thickness.

つぎに、上記の本発明被覆サーメット工具１〜１３および従来被覆サーメット工具１〜１３各種の被覆サーメット工具について、いずれも工具鋼製バイトの先端部にボルト止めまたはクランプ駒による挟み締め止めした状態で、
被削材：ＪＩＳ・ＳＵＳ３０４の丸棒、
切削速度：３６０ｍ／ｍｉｎ．、
切り込み：２ｍｍ、
送り：０．２ｍｍ／ｒｅｖ．、
の条件（切削条件Ａという）でのステンレス鋼の乾式連続高速切削試験（通常の切削速度１５０ｍ／ｍｉｎ．）、
被削材：ＪＩＳ・ＳＳ４００の長さ方向等間隔４本縦溝入り丸棒、
切削速度：３９０ｍ／ｍｉｎ．、
切り込み：２ｍｍ、
送り：０．２ｍｍ／ｒｅｖ．、
の条件（切削条件Ｂという）での軟鋼の乾式断続高速切削試験（通常の切削速度は２００ｍ／ｍｉｎ．）、さらに、
被削材：ＪＩＳ・ＳＣＭｎＨ１の丸棒、
切削速度：３８０ｍ／ｍｉｎ．、
切り込み：３ｍｍ、
送り：０．２５ｍｍ／ｒｅｖ．、
の条件（切削条件Ｃという）での高マンガン鋼の乾式連続高速切削試験（通常の切削速度は２５０ｍ／ｍｉｎ．）を行い、いずれの切削試験でも切刃の逃げ面摩耗幅が、一般に切削工具の使用寿命の目安とされている０．３ｍｍに至るまでの切削時間を測定した。この測定結果を表９に示した。 Next, with respect to the above-described coated cermet tools 1 to 13 of the present invention and the various coated cermet tools 1 to 13 of the present invention, all of them are clamped and clamped to the tip of the tool steel tool by a bolt or a clamp piece. ,
Work material: JIS / SUS304 round bar,
Cutting speed: 360 m / min. ,
Cutting depth: 2mm,
Feed: 0.2 mm / rev. ,
Dry continuous high-speed cutting test (normal cutting speed 150 m / min.) Of stainless steel under the following conditions (referred to as cutting conditions A),
Work material: JIS / SS400 lengthwise equidistant 4 round bars with flutes,
Cutting speed: 390 m / min. ,
Cutting depth: 2mm,
Feed: 0.2 mm / rev. ,
Dry interrupted high-speed cutting test (normal cutting speed is 200 m / min.) Of mild steel under the following conditions (referred to as cutting conditions B),
Work material: JIS / SCMnH1 round bar,
Cutting speed: 380 m / min. ,
Incision: 3mm,
Feed: 0.25 mm / rev. ,
The dry continuous high-speed cutting test (normal cutting speed is 250 m / min.) Of high manganese steel under the above conditions (referred to as cutting condition C), and the flank wear width of the cutting edge is generally a cutting tool in any cutting test. The cutting time up to 0.3 mm, which is regarded as a standard for the service life of the steel, was measured. The measurement results are shown in Table 9.

表５〜９に示される結果から、本発明被覆サーメット工具１〜１３は、いずれも（０００１）面の傾斜角度数分布グラフで、硬質被覆層の上部層である改質α型Ａｌ₂Ｏ₃層が３０〜４５度の範囲内の傾斜角区分で、また前記上部層と下部層であるＴｉ化合物層の間に介在させた密着α型Ａｌ₂Ｏ₃層が７５〜９０度の範囲内の傾斜角区分でそれぞれ最高ピークを示し、かつそれぞれの前記傾斜角区分における度数分布割合が５０％以上を示し、この結果前記改質α型Ａｌ₂Ｏ₃層はすぐれた高温硬さおよび耐熱性に加えて、すぐれた高温強度を具備するようになると共に、前記密着α型Ａｌ₂Ｏ₃層はすぐれた密着性を示し、さらに、前記改質α型Ａｌ₂Ｏ₃層の少なくとも切刃稜線部を含むすくい面部分および逃げ面部分の表面がＲａ：０．２μｍ以下の表面粗さに研磨され、摩耗進行抑制効果が発揮されることと相俟って、特に切刃部にきわめて高い切削抵抗が加わる難削材の高速切削加工でも、切刃部におけるチッピング発生が著しく抑制され、すぐれた耐摩耗性を長期に亘って示すのに対して、硬質被覆層の上部層が、（０００１）面の測定傾斜角の分布が０〜４５度および４５〜９０度の範囲内で不偏的で、最高ピークが存在しない傾斜角度数分布グラフを示すと共に、表面平滑性の低い従来α型Ａｌ₂Ｏ₃層からなり、かつ前記密着α型Ａｌ₂Ｏ₃層の介在形成のない従来被覆サーメット工具１〜１３においては、いずれも硬質被覆層の強度不足が原因で、難削材の高速切削加工では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 5 to 9, all of the coated cermet tools 1 to 13 of the present invention are graphs of inclination angle number distribution on the (0001) plane, and the modified α-type Al ₂ O ₃ that is the upper layer of the hard coating layer. The layer is inclined at an angle in the range of 30 to 45 degrees, and the contact α-type Al ₂ O ₃ layer interposed between the upper and lower Ti compound layers is in the range of 75 to 90 degrees. Each of the inclination angle sections shows the highest peak, and the frequency distribution ratio in each of the inclination angle sections shows 50% or more. As a result, the modified α-type Al ₂ O ₃ layer has excellent high-temperature hardness and heat resistance. In addition, the adhesive α-type Al ₂ O ₃ layer has excellent high-temperature strength and exhibits excellent adhesion, and at least the cutting edge ridge line portion of the modified α-type Al ₂ O ₃ layer The surface of the rake face portion and the flank face portion containing Ra is 0.2 μm In combination with the fact that the surface roughness is less than or equal to m and the effect of suppressing the progress of wear is demonstrated, chipping at the cutting edge part is particularly effective even in high-speed cutting of difficult-to-cut materials that add extremely high cutting resistance to the cutting edge part. While the generation is remarkably suppressed and excellent wear resistance is exhibited over a long period of time, the upper layer of the hard coating layer has a distribution of measured inclination angles on the (0001) plane of 0 to 45 degrees and 45 to 90 degrees. Inclination angle number distribution graph that is unbiased within the range of No. 1 and has a conventional α-type Al ₂ O ₃ layer with low surface smoothness, and the interposition of the adhesive α-type Al ₂ O ₃ layer In the conventional coated cermet tools 1 to 13 that are not formed, due to insufficient strength of the hard coating layer, chipping occurs in the hard coating layer in high-speed cutting of difficult-to-cut materials, and the service life is shortened in a relatively short time. It is clear that

上述のように、この発明の被覆サーメット工具は、各種鋼や鋳鉄などの高速切削加工は勿論のこと、特に自身が高い粘性を有し、かつ切削時の切削工具表面部の硬質被覆層に対する粘着性も高く、この結果切削抵抗のきわめて高いものとなる軟鋼やステンレス鋼、さらに高マンガン鋼などの難削材の高速切削加工でも、チッピングの発生なく、すぐれた耐摩耗性を示し、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 cermet tool of the present invention has high viscosity in addition to high-speed cutting such as various types of steel and cast iron, and particularly has a high viscosity and adheres to the hard coating layer on the surface of the cutting tool during cutting. Even in high-speed cutting of difficult-to-cut materials such as mild steel, stainless steel, and high manganese steel, which has extremely high cutting resistance, it exhibits excellent wear resistance without chipping. Since it exhibits excellent cutting performance, it can sufficiently satisfy the high performance of the cutting device, the labor saving and energy saving of cutting, and the cost reduction.

硬質被覆層を構成する各種α型Ａｌ₂Ｏ₃層における結晶粒の（０００１）面を測定する場合の０〜４５度の傾斜角の測定範囲を示す概略説明図である。It is a schematic diagram illustrating a measurement range of the inclination angle of 0 to 45 degrees when measuring the crystal grain of the various α-type the Al ₂ O ₃ layer constituting the hard coating layer (0001) plane. 硬質被覆層を構成する各種α型Ａｌ₂Ｏ₃層における結晶粒の（０００１）面を測定する場合の４５〜９０度の傾斜角の測定範囲を示す概略説明図である。It is a schematic diagram illustrating a measurement range of the inclination angle of 45 to 90 degrees when measuring the crystal grain of the various α-type the Al ₂ O ₃ layer constituting the hard coating layer (0001) plane. 本発明被覆サーメット工具５の硬質被覆層の上部層を構成する改質α型Ａｌ₂Ｏ₃層の０〜４５度の傾斜角区分を示す傾斜角度数分布グラフである。The inclination angle frequency distribution graph showing the tilt angle sections of 0 to 45 degrees of the modified α type the Al ₂ O ₃ layer constituting the upper layer of the hard coating layer of the present invention coated cermet tool 5. 本発明被覆サーメット工具５の硬質被覆層の層間密着層を構成する密着α型Ａｌ₂Ｏ₃層の４５〜９０度の傾斜角区分を示す傾斜角度数分布グラフである。The inclination angle frequency distribution graph showing the tilt angle sections of 45 to 90 degrees of the contact α type the Al ₂ O ₃ layer constituting the interlayer adhesion layer of the hard coating layer of the present invention coated cermet tool 5. 従来被覆サーメット工具６の硬質被覆層の上部層を構成する従来α型Ａｌ₂Ｏ₃層の０〜４５度の傾斜角区分を示す傾斜角度数分布グラフである。The inclination angle frequency distribution graph showing the tilt angle sections of 0 to 45 degrees of conventional α form the Al ₂ O ₃ layer constituting the upper layer of the hard coating layer of the conventional coated cermet tool 6. 従来被覆サーメット工具６の硬質被覆層を構成する従来α型Ａｌ₂Ｏ₃層の４５〜９０度の傾斜角区分を示す傾斜角度数分布グラフである。The inclination angle frequency distribution graph showing the tilt angle sections of 45 to 90 degrees to the conventional coated cermet conventional α type the Al ₂ O ₃ layer constituting the hard coating layer of the tool 6.

Claims (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、
（１）下部層として、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、
（２）上記下部層と下記上部層の層間密着層として、化学蒸着した状態でα型の結晶構造を有し、電界放出型走査電子顕微鏡を用い、上記工具基体表面と平行な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、前記研磨面の法線に対して、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、４５〜９０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において、
７５〜９０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７５〜９０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５０％以上の割合を占める傾斜角度数分布グラフを示し、かつ０．１〜１．９μｍの平均層厚を有する密着α型酸化アルミニウム層、
（３）上部層として、化学蒸着した状態でα型の結晶構造を有し、電界放出型走査電子顕微鏡を用い、上記工具基体表面と平行な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、前記研磨面の法線に対して、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において、
３０〜４５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３０〜４５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５０％以上の割合を占める傾斜角度数分布グラフを示し、かつ１．５〜５．９μｍの平均層厚を有する改質α型酸化アルミニウム層、
以上（１）〜（３）で構成された硬質被覆層を蒸着形成してなり、
さらに、上記硬質被覆層の上部層である改質α型酸化アルミニウム層の全面に、
０．５〜５μｍの平均層厚を有する窒化チタン層で構成された研磨材層を蒸着形成した状態で、
ウエットブラストにて、噴射研磨材として、水との合量に占める割合で１５〜６０質量％の酸化アルミニウム微粒を配合した研磨液を噴射し、
上記の研磨材層のウエットブラストによる粉砕化窒化チタン微粒と、噴射研磨材としての酸化アルミニウム微粒の共存下で、上記硬質被覆層の上部層を構成する改質α型酸化アルミニウム層の少なくとも切刃稜線部を含むすくい面部分および逃げ面部分を研磨して、これら研磨面の表面粗さを準拠規格ＪＩＳ・Ｂ０６０１−１９９４に基いた測定で、Ｒａ：０．２μｍ以下としたこと、
を特徴とする難削材の高速切削加工で硬質被覆層がすぐれた耐チッピング性を発揮する表面被覆サーメット製切削工具。 On the surface of the tool base composed of tungsten carbide based cemented carbide or titanium carbonitride based cermet,
(1) As a lower layer, it is composed of one or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer, and carbonitride layer, and a total average of 3 to 20 μm A Ti compound layer having a layer thickness,
(2) As an interlayer adhesion layer between the lower layer and the upper layer described below, a polished surface parallel to the tool base surface is obtained using a field emission scanning electron microscope having an α-type crystal structure in the state of chemical vapor deposition. Inclination made by irradiating an electron beam to each crystal grain having a hexagonal crystal lattice existing in the range and a normal line of the (0001) plane being the crystal plane of the crystal grain with respect to the normal line of the polished surface An angle is measured, and the measured inclination angle within the range of 45 to 90 degrees is divided into 0.25 degree pitches among the measured inclination angles, and the degrees existing in each division are totaled. In the angle distribution graph,
The highest peak exists in the inclination angle section in the range of 75 to 90 degrees, and the total of the frequencies existing in the range of 75 to 90 degrees represents a ratio of 50% or more of the entire degrees in the inclination angle frequency distribution graph. A close contact α-type aluminum oxide layer showing an inclination angle number distribution graph and having an average layer thickness of 0.1 to 1.9 μm;
(3) As an upper layer, a hexagonal crystal lattice having an α-type crystal structure in a chemical vapor deposited state and existing in a measurement range of a polished surface parallel to the tool base surface using a field emission scanning electron microscope And measuring the inclination angle formed by the normal line of the (0001) plane, which is the crystal plane of the crystal grain, with respect to the normal line of the polished surface. In the inclination angle number distribution graph formed by dividing the measured inclination angles in the range of 0 to 45 degrees for each pitch of 0.25 degrees and totaling the frequencies existing in each section,
The highest peak exists in the inclination angle section within the range of 30 to 45 degrees, and the total of the frequencies existing within the range of 30 to 45 degrees represents a ratio of 50% or more of the entire degrees in the inclination angle frequency distribution graph. A modified α-type aluminum oxide layer showing an inclination angle number distribution graph and having an average layer thickness of 1.5 to 5.9 μm;
The hard coating layer composed of the above (1) to (3) is formed by vapor deposition,
Furthermore, on the entire surface of the modified α-type aluminum oxide layer, which is the upper layer of the hard coating layer,
In a state where an abrasive layer composed of a titanium nitride layer having an average layer thickness of 0.5 to 5 μm is formed by vapor deposition,
In wet blasting, as a spraying abrasive, a polishing liquid containing 15 to 60% by mass of aluminum oxide fine particles in a proportion of the total amount with water is sprayed,
At least the cutting edge of the modified α-type aluminum oxide layer constituting the upper layer of the hard coating layer in the presence of finely divided titanium nitride fine particles by wet blasting of the abrasive layer and aluminum oxide fine particles as a spray abrasive The rake face part including the ridge line part and the flank face part are polished, and the surface roughness of these polished surfaces is Ra: 0.2 μm or less in the measurement based on the compliant standard JIS B0601-1994.
A surface-coated cermet cutting tool that exhibits excellent chipping resistance in high-speed cutting of difficult-to-cut materials characterized by

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