JP6493800B2 - Surface coated cutting tool with excellent wear resistance in high speed cutting - Google Patents
Surface coated cutting tool with excellent wear resistance in high speed cutting Download PDFInfo
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- 238000005520 cutting process Methods 0.000 title claims description 67
- 239000013078 crystal Substances 0.000 claims description 189
- 239000011247 coating layer Substances 0.000 claims description 95
- 239000002245 particle Substances 0.000 claims description 70
- 239000010410 layer Substances 0.000 claims description 59
- 239000000758 substrate Substances 0.000 claims description 23
- 239000000203 mixture Substances 0.000 claims description 15
- 229910052582 BN Inorganic materials 0.000 claims description 13
- PZNSFCLAULLKQX-UHFFFAOYSA-N Boron nitride Chemical compound N#B PZNSFCLAULLKQX-UHFFFAOYSA-N 0.000 claims description 13
- 150000004767 nitrides Chemical class 0.000 claims description 13
- 238000001887 electron backscatter diffraction Methods 0.000 claims description 11
- 239000011230 binding agent Substances 0.000 claims description 10
- 239000013598 vector Substances 0.000 claims description 7
- 239000002131 composite material Substances 0.000 claims description 6
- 239000012535 impurity Substances 0.000 claims description 3
- JMANVNJQNLATNU-UHFFFAOYSA-N oxalonitrile Chemical compound N#CC#N JMANVNJQNLATNU-UHFFFAOYSA-N 0.000 claims 1
- 230000015572 biosynthetic process Effects 0.000 description 19
- 238000005259 measurement Methods 0.000 description 12
- 230000000052 comparative effect Effects 0.000 description 9
- 238000000034 method Methods 0.000 description 9
- 238000012545 processing Methods 0.000 description 9
- 238000004458 analytical method Methods 0.000 description 8
- 239000000463 material Substances 0.000 description 8
- 239000000843 powder Substances 0.000 description 8
- 238000004626 scanning electron microscopy Methods 0.000 description 7
- 238000012935 Averaging Methods 0.000 description 6
- 238000010586 diagram Methods 0.000 description 6
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 5
- 229910045601 alloy Inorganic materials 0.000 description 5
- 239000000956 alloy Substances 0.000 description 5
- 230000007423 decrease Effects 0.000 description 5
- 238000000682 scanning probe acoustic microscopy Methods 0.000 description 5
- 230000008020 evaporation Effects 0.000 description 4
- 238000001704 evaporation Methods 0.000 description 4
- 239000002994 raw material Substances 0.000 description 4
- 229910001018 Cast iron Inorganic materials 0.000 description 3
- 229910000831 Steel Inorganic materials 0.000 description 3
- 229910004349 Ti-Al Inorganic materials 0.000 description 3
- 229910004692 Ti—Al Inorganic materials 0.000 description 3
- 238000005299 abrasion Methods 0.000 description 3
- 230000005540 biological transmission Effects 0.000 description 3
- 238000000227 grinding Methods 0.000 description 3
- 238000007733 ion plating Methods 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 229910052755 nonmetal Inorganic materials 0.000 description 3
- 238000005245 sintering Methods 0.000 description 3
- 239000010959 steel Substances 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 238000005219 brazing Methods 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 229910001873 dinitrogen Inorganic materials 0.000 description 2
- 238000010891 electric arc Methods 0.000 description 2
- 238000010894 electron beam technology Methods 0.000 description 2
- 238000002149 energy-dispersive X-ray emission spectroscopy Methods 0.000 description 2
- 238000010191 image analysis Methods 0.000 description 2
- 238000000465 moulding Methods 0.000 description 2
- 230000001737 promoting effect Effects 0.000 description 2
- 238000010791 quenching Methods 0.000 description 2
- 230000000171 quenching effect Effects 0.000 description 2
- 239000012495 reaction gas Substances 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 230000003746 surface roughness Effects 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- XKRFYHLGVUSROY-UHFFFAOYSA-N argon Substances [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- -1 argon ions Chemical class 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 238000005255 carburizing Methods 0.000 description 1
- 239000011195 cermet Substances 0.000 description 1
- 239000008199 coating composition Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000002050 diffraction method Methods 0.000 description 1
- 238000005553 drilling Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000001941 electron spectroscopy Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000010884 ion-beam technique Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000013507 mapping Methods 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000005121 nitriding Methods 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 235000002639 sodium chloride Nutrition 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
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- Drilling Tools (AREA)
- Cutting Tools, Boring Holders, And Turrets (AREA)
Description
本発明は、鋼や鋳鉄などの高速切削加工に供した場合に、硬質被覆層がすぐれた耐摩耗性を備え、長期の使用に亘ってすぐれた切削性能を発揮する表面被覆切削工具（以下、被覆工具という）に関する。 The present invention provides a surface-coated cutting tool (hereinafter referred to as “a surface-coated cutting tool”) that exhibits excellent wear resistance over a long period of use when it is subjected to high-speed cutting processing such as steel and cast iron. (Referred to as a coated tool).
一般に、被覆工具には、各種の鋼や鋳鉄などの被削材の旋削加工や平削り加工にバイトの先端部に着脱自在に取り付けて用いられるインサート、被削材の穴あけ切削加工などに用いられるドリルやミニチュアドリル、さらに被削材の面削加工や溝加工、肩加工などに用いられるソリッドタイプのエンドミルなどがあり、またインサートを着脱自在に取り付けてソリッドタイプのエンドミルと同様に切削加工を行うインサート式エンドミルなどが知られている。 In general, coated tools are used for turning and planing of work materials such as various types of steel and cast iron, inserts that can be used detachably attached to the tip of a cutting tool, drilling processing of work materials, etc. There are drills, miniature drills, solid type end mills used for chamfering, grooving, shoulder processing, etc. of the work material, etc. Also, inserts are detachably attached and cutting is performed in the same way as solid type end mills An insert type end mill is known.
従来、被覆工具としては、例えば、ＷＣ基超硬合金、ＴｉＣＮ基サーメット、ｃＢＮ焼結体を工具基体とし、これに硬質被覆層を形成した被覆工具が知られており、切削性能の改善を目的として種々の提案がなされている。
例えば、特許文献１には、重切削加工での硬質被覆層の耐欠損性を高めるため、工具基体表面に、組成式（Ｔｉ１−ＸＡｌＸ）Ｎ（ただし、原子比で、Ｘは０．４〜０．６５）を満足するＴｉとＡｌの複合窒化物層からなり、かつ、該層についてＥＢＳＤによる結晶方位解析を行った場合、表面研磨面の法線方向から０〜１５度の範囲内に結晶方位＜１００＞を有する結晶粒の面積割合が５０％以上であり、また、隣り合う結晶粒同士のなす角を測定した場合に、小角粒界（０＜θ≦１５゜）の割合が５０％以上であるような結晶配列を示すＴｉとＡｌの複合窒化物層からなる硬質被覆層を被覆した被覆工具が提案されている。
Conventionally, as a coated tool, for example, a coated tool in which a WC-based cemented carbide alloy, a TiCN-based cermet, and a cBN sintered body are used as a tool base and a hard coating layer is formed on the tool base is known. Various proposals have been made.
For example, in Patent Document 1, in order to increase the fracture resistance of a hard coating layer in heavy cutting, a composition formula (Ti 1-X Al X ) N (however, atomic ratio, X is 0) .4 to 0.65), and when the crystal orientation analysis by EBSD is performed on the layer, the range of 0 to 15 degrees from the normal direction of the surface polished surface. The area ratio of crystal grains having crystal orientation <100> is 50% or more, and the ratio of small-angle grain boundaries (0 <θ ≦ 15 °) when the angle between adjacent crystal grains is measured There has been proposed a coated tool coated with a hard coating layer composed of a composite nitride layer of Ti and Al that exhibits a crystal arrangement such that is 50% or more.
また、特許文献２には、切刃に高負荷が作用する乾式断続重切削加工での硬質被覆層の耐欠損性、靭性を高めるため、ＴｉＮ層からなる硬質被覆層のＴｉＮ結晶粒を硬質被覆層の層厚と等しい高さを有する柱状晶組織とし、さらに、ＴｉＮ層の水平断面における結晶粒組織を観察した場合、粒径が１０〜１００ｎｍの結晶粒が占有する面積を測定面積のうちの９０％以上とし、かつ、電子線後方散乱回折装置で表面の結晶粒の結晶方位を測定した場合、隣り合う測定点との結晶方位の差が１５度以上となる結晶界面によって囲まれた直径０．２〜４μｍの区分が占有する面積を、測定された全体の面積のうち２０％以上とした被覆工具が提案されている。 Further, in Patent Document 2, in order to improve the chipping resistance and toughness of the hard coating layer in the dry interrupted heavy cutting process in which a high load acts on the cutting blade, the TiN crystal grains of the hard coating layer made of the TiN layer are hard-coated. When the columnar crystal structure has a height equal to the layer thickness of the layer, and the crystal grain structure in the horizontal section of the TiN layer is observed, the area occupied by the crystal grains having a grain size of 10 to 100 nm is When the crystal orientation of the crystal grains on the surface is measured by an electron beam backscattering diffractometer with a diameter of 90% or more, the diameter 0 surrounded by the crystal interface where the difference in crystal orientation between adjacent measurement points is 15 degrees or more. A coated tool is proposed in which the area occupied by sections of 2 to 4 μm occupies 20% or more of the measured total area.
前記従来技術で提案されているＴｉとＡｌの複合窒化物層あるいはＴｉの窒化物層からなる硬質被覆層を備えた被覆工具は、重切削加工条件下では、すぐれた耐欠損性を発揮するが、高速切削加工に供した場合、耐摩耗性が必ずしも十分であるとはいえなかった。
そこで、高速切削加工条件下でも、長期の使用にわたってすぐれた耐摩耗性を発揮する被覆工具が求められている。
The coated tool provided with the hard coating layer composed of the composite nitride layer of Ti and Al or the nitride layer of Ti proposed in the above prior art exhibits excellent fracture resistance under heavy cutting conditions. When subjected to high-speed cutting, the wear resistance is not always sufficient.
Therefore, there is a need for a coated tool that exhibits excellent wear resistance over a long period of use even under high-speed cutting conditions.
そこで、本発明者らは、前記課題を解決すべく硬質被覆層の構造について鋭意検討したところ、次のような知見を得たのである。 Therefore, the present inventors diligently studied about the structure of the hard coating layer in order to solve the above problems, and obtained the following knowledge.
ＴｉとＡｌの複合窒化物（以下、「（Ｔｉ，Ａｌ）Ｎ」で示す場合もある）からなる硬質被覆層の結晶組織を制御し、工具基体表面近傍の（Ｔｉ，Ａｌ）Ｎ層を微粒組織とし、一方、硬質被覆層表面側の（Ｔｉ，Ａｌ）Ｎ層を柱状組織として形成するとともに、硬質被覆層表面の柱状組織の少なくとも一部に、複数の結晶粒の集合体からなる結晶方位の近い粒子が集まった領域を形成することによって、隣り合う結晶粒同士の結合を強靭なものとすることで、高速切削加工において、すぐれた耐摩耗性（特に、擦れ摩耗）を発揮する被覆工具が得られることを見出したのである。 Controls the crystal structure of a hard coating layer made of a composite nitride of Ti and Al (hereinafter also referred to as “(Ti, Al) N”), and finely forms a (Ti, Al) N layer near the tool base surface. On the other hand, the (Ti, Al) N layer on the hard coating layer surface side is formed as a columnar structure, and at least a part of the columnar structure on the hard coating layer surface is a crystal orientation consisting of an aggregate of a plurality of crystal grains By forming a region in which particles close to each other are gathered, the bonding tool between adjacent crystal grains is strengthened, so that the coated tool exhibits excellent wear resistance (especially abrasion wear) in high-speed cutting. It was found that can be obtained.
ここで、前記「結晶方位の近い粒子が集まった領域」とは、以下で定義される複数の結晶粒の集合体からなる領域をいう。
即ち、結晶方位の近い粒子が集まった領域とは、
（１）硬質被覆層表面の結晶粒の集合体からなる領域内の各結晶粒の工具基体表面の法線方向に対して最も傾斜角度が少ない結晶方位＜１００＞のベクトルを平均した方位と基体表面の法線方向のなす角度が１０度以下である。
（２）領域内の各結晶粒の結晶方位の差は２度以上１０度以下である。
上記（１）、（２）の条件を同時に満足するような複数の結晶粒の集合体からなる領域を「結晶方位の近い粒子が集まった領域」と定義する。
Here, the “region where grains having similar crystal orientations gather” refers to a region composed of an aggregate of a plurality of crystal grains defined below.
In other words, the region where particles with similar crystal orientation gathered is
(1) Orientation and substrate obtained by averaging the vectors of crystal orientation <100> having the smallest inclination angle with respect to the normal direction of the tool substrate surface of each crystal grain in the region consisting of the aggregate of crystal grains on the surface of the hard coating layer The angle formed by the normal direction of the surface is 10 degrees or less.
(2) The difference in crystal orientation of each crystal grain in the region is not less than 2 degrees and not more than 10 degrees.
A region composed of an aggregate of a plurality of crystal grains that satisfies the above conditions (1) and (2) at the same time is defined as “a region where particles having close crystal orientations gather”.
また、硬質被覆層を構成する前記（Ｔｉ，Ａｌ）Ｎ層について電子線後方散乱回折法（Ｅｌｅｃｔｏｒｏｎ ＢａｃｋＳｃａｔｔｅｒ Ｄｉｆｆｒａｃｔｉｏｎ：ＥＢＳＤ）による結晶方位解析を行った場合、基体表面の法線方向から０〜１０度の範囲内に結晶方位＜１００＞を有する結晶粒の面積割合が４０〜９０面積％を満足する配向性を有するように結晶組織を制御することによって、硬質被覆層表面側における（Ｔｉ，Ａｌ）Ｎ層の結晶粒の柱状化を促進し得ること、また、その結果として、結晶方位の近い粒子が集まった領域の形成を促進し得ることを見出したのである。
さらに、工具基体である立方晶窒化硼素（以下、「ｃＢＮ」で示す）焼結体におけるｃＢＮ粒子の平均粒径、含有割合が、硬質被覆層表面側における（Ｔｉ，Ａｌ）Ｎ層の結晶粒の柱状化促進、また、結晶方位の近い粒子が集まった領域の形成を促進する上で、重要な要素であることを見出したのである。
When the crystal orientation analysis is performed on the (Ti, Al) N layer constituting the hard coating layer by electron backscatter diffraction (EBSD), 0 to 10 degrees from the normal direction of the substrate surface. (Ti, Al) on the surface side of the hard coating layer by controlling the crystal structure so that the crystal grains have an orientation satisfying an area ratio of 40 to 90% by area with crystal orientation <100> within the range of It has been found that columnarization of crystal grains of the N layer can be promoted, and as a result, formation of a region where grains having similar crystal orientations gather can be promoted.
Furthermore, the average particle diameter and content ratio of the cBN particles in the cubic boron nitride (hereinafter referred to as “cBN”) sintered body as the tool base are the crystal grains of the (Ti, Al) N layer on the hard coating layer surface side. It was found that this is an important factor in promoting the columnar formation of particles and the formation of a region in which grains having similar crystal orientations gather.
本発明は、前記知見に基づいてなされたものであって、
「（１）立方晶窒化硼素焼結体からなる工具基体の表面に、１．０〜４．０μｍの平均層厚の硬質被覆層が蒸着形成された表面被覆切削工具において、
（ａ）前記硬質被覆層は、
組成式：（Ｔｉ１−ｘＡｌｘ）Ｎで表した場合、０．４≦ｘ≦０．７（但し、ｘは原子比）を満足するＴｉとＡｌの複合窒化物層であり、
（ｂ）前記硬質被覆層の結晶組織は、工具基体との界面側では結晶粒の平均幅が０．０１〜０．０５μｍの微粒組織、また、硬質被覆層表面側では結晶粒の平均幅が０．０５〜１．０μｍの柱状組織であって、該柱状組織の層厚方向の平均厚さは、硬質被覆層の層厚より薄く、かつ、０．３〜１．５μｍの平均厚さで形成されており、
（ｃ）前記硬質被覆層の表面には、複数の結晶粒の集合体からなり、該集合体の平均幅が０．５〜２．０μｍである結晶方位の近い粒子が集まった領域が形成され、該結晶方位の近い粒子が集まった領域が硬質被覆層の表面に占める面積割合は３０〜８０面積％であり、
（ｄ）前記結晶方位の近い粒子が集まった領域は、該領域内の各結晶粒の結晶方位の差が２度以上１０度以下である領域であって、しかも、工具基体表面の法線方向に対する該領域内の各結晶粒の結晶方位の傾斜角度差が最も小さい結晶方位＜１００＞のベクトルを平均した方位と基体表面の法線方向のなす角度が１０度以下であることを特徴とする表面被覆切削工具。
（２）前記硬質被覆層の結晶粒について、電子線後方散乱回折法による結晶方位解析を行ったとき、基体表面の法線方向から０〜１０度の範囲内に結晶方位＜１００＞を有する結晶粒の面積割合が４０〜９０面積％を満足するような結晶配向性を有することを特徴とする（１）に記載の表面被覆切削工具。
（３）前記（１）または（２）に記載の工具基体は、少なくとも切削に使用する刃先が立方晶窒化硼素焼結体からなり、前記立方晶窒化硼素焼結体は立方晶窒化硼素粒子とＴｉの窒化物、炭化物、炭窒化物、硼化物およびＡｌの窒化物、酸化物からなる群から選ばれた少なくとも１種以上の粒子と不可避不純物とを含む結合相とからなり、前記立方晶窒化硼素粒子は平均粒径２．０〜４．０μｍかつ立方晶窒化硼素焼結体全体に占める含有割合が５０〜８０体積％であることを特徴とする（１）または（２）に記載の表面被覆切削工具。」
に特徴を有するものである。
The present invention has been made based on the above findings,
“(1) In a surface-coated cutting tool in which a hard coating layer having an average layer thickness of 1.0 to 4.0 μm is vapor-deposited on the surface of a tool base made of a cubic boron nitride sintered body,
(A) The hard coating layer is
When represented by a composition formula: (Ti 1-x Al x ) N, it is a composite nitride layer of Ti and Al that satisfies 0.4 ≦ x ≦ 0.7 (where x is an atomic ratio),
(B) The crystal structure of the hard coating layer has a fine grain structure in which the average width of crystal grains is 0.01 to 0.05 μm on the interface side with the tool base, and the average width of crystal grains on the hard coating layer surface side. It is a columnar structure of 0.05 to 1.0 μm, and the average thickness in the layer thickness direction of the columnar structure is smaller than the layer thickness of the hard coating layer and is an average thickness of 0.3 to 1.5 μm. Formed,
(C) On the surface of the hard coating layer, there is formed a region composed of aggregates of a plurality of crystal grains, in which grains having close crystal orientation and an average width of the aggregates of 0.5 to 2.0 μm are collected. In addition, the area ratio of the area where the grains having similar crystal orientations gather to the surface of the hard coating layer is 30 to 80 area%,
(D) The region where grains having similar crystal orientations gather is a region in which the difference in crystal orientation of each crystal grain in the region is 2 degrees or more and 10 degrees or less, and the normal direction of the tool base surface The angle between the orientation of the average of the crystal orientation <100> vectors and the normal direction of the substrate surface is 10 degrees or less. Surface coated cutting tool.
(2) A crystal having a crystal orientation <100> in the range of 0 to 10 degrees from the normal direction of the substrate surface when the crystal orientation analysis by electron beam backscatter diffraction method is performed on the crystal grains of the hard coating layer. The surface-coated cutting tool according to (1), which has a crystal orientation such that an area ratio of grains satisfies 40 to 90 area%.
(3) In the tool base according to (1) or (2), at least a cutting edge used for cutting is made of a cubic boron nitride sintered body, and the cubic boron nitride sintered body includes cubic boron nitride particles. The cubic nitriding, comprising a binder phase containing at least one kind of particles selected from the group consisting of Ti nitride, carbide, carbonitride, boride and Al nitride, oxide, and inevitable impurities The surface according to (1) or (2), wherein the boron particles have an average particle size of 2.0 to 4.0 μm and a content ratio of 50 to 80% by volume in the entire cubic boron nitride sintered body Coated cutting tool. "
It has the characteristics.
次に、本発明の被覆工具について、より詳細に説明する。 Next, the coated tool of the present invention will be described in more detail.
図１に、本発明被覆工具の概略模式図を示す。
図１（ａ）は、本発明被覆工具の硬質被覆層表面の概略模式図であり、図１（ｂ）は、本発明被覆工具の縦断面の概略模式図である。
図１（ｂ）に示すように、本発明の被覆工具は、立方晶窒化硼素焼結体からなる工具基体（以下、「ｃＢＮ工具基体」で示す）の表面に、（Ｔｉ，Ａｌ）Ｎ層からなる硬質被覆層が形成されており、しかも、該（Ｔｉ，Ａｌ）Ｎ層の結晶組織は、工具基体との界面側では微粒組織、また、硬質被覆層表面側では柱状組織であり、該柱状組織は、層厚方向に０．３〜１．５μｍの平均厚みで形成されている。
また、図１（ａ）に示すように、本発明の被覆工具の硬質被覆層をその表面から観察したとき、硬質被覆層表面には、結晶方位の近い複数の結晶粒の集合体からなる結晶方位の近い粒子が集まった領域が形成されている。そして、「結晶方位の近い粒子が集まった領域」をより厳密に言えば、領域内の各結晶粒の結晶方位の差が２度以上１０度以下である領域であって、しかも、工具基体表面の法線方向に対する該領域内の各結晶粒の結晶方位の傾斜角度差が最も小さい結晶方位＜１００＞のベクトルを平均した方位と基体表面の法線方向のなす角度が１０度以下である領域をいう。
In FIG. 1, the schematic model of this invention coated tool is shown.
Fig.1 (a) is a schematic schematic diagram of the hard coating layer surface of this invention coated tool, FIG.1 (b) is a schematic schematic diagram of the longitudinal cross-section of this invention coated tool.
As shown in FIG. 1 (b), the coated tool of the present invention has a (Ti, Al) N layer on the surface of a tool base made of a cubic boron nitride sintered body (hereinafter referred to as "cBN tool base"). And the crystal structure of the (Ti, Al) N layer is a fine grain structure on the interface side with the tool base, and a columnar structure on the hard coating layer surface side, The columnar structure is formed with an average thickness of 0.3 to 1.5 μm in the layer thickness direction.
Further, as shown in FIG. 1 (a), when the hard coating layer of the coated tool of the present invention is observed from its surface, the hard coating layer surface has a crystal composed of an aggregate of a plurality of crystal grains having close crystal orientations. A region in which particles of close orientation are gathered is formed. Strictly speaking, the “region where grains having close crystal orientations gather” is a region in which the difference in crystal orientation of each crystal grain in the region is 2 degrees or more and 10 degrees or less, and the tool base surface A region in which the angle formed by the average of the vectors of crystal orientation <100> having the smallest tilt angle difference between the crystal orientations of the crystal grains in the region with respect to the normal direction is 10 degrees or less. Say.
硬質被覆層の組成および平均層厚：
本発明の被覆工具の硬質被覆層は、
組成式：（Ｔｉ１−ｘＡｌｘ）Ｎ
で表した場合、０．４≦ｘ≦０．７（但し、ｘは原子比）を満足する組成のＴｉとＡｌの複合窒化物層からなる。
上記組成式において、ｘの値を０．４（原子比）以上とすることによって、（Ｔｉ，Ａｌ）Ｎ層における高温硬さと高温耐酸化性が向上するが、一方、ｘの値が０．７（原子比）を超えると、岩塩型結晶構造を維持することが困難になるばかりか、アモルファス化し易くなり、硬さが低下してくることから、ＴｉとＡｌの合量に占めるＡｌの含有割合（但し、原子比）は、０．４≦ｘ≦０．７と定めた。
なお、上記組成式では、ＴｉとＡｌからなる金属元素とＮからなる非金属元素が、恰も、原子比で１：１であるかのような形式で記載しているが、大事なのは、ＴｉとＡｌとの比率であって、金属元素［Ｔｉ、Ａｌ］と非金属元素［Ｎ］の割合は１：１に限定されるものではなく、１：１の場合と同一の結晶構造が維持されるのであれば金属元素［Ｔｉ、Ａｌ］と非金属元素［Ｎ］の割合は１：１を外れていてもよい。
また、上記（Ｔｉ，Ａｌ）Ｎ層は、その平均層厚が１．０μｍ未満であると、硬質被覆層の表面における結晶方位の近い粒子が集まった領域を十分な面積割合で形成することができず、一方、（Ｔｉ，Ａｌ）Ｎ層の平均層厚が４．０μｍを超えると、高速切削加工においてチッピング、欠損を発生しやすくなるので、（Ｔｉ，Ａｌ）Ｎ層からなる硬質被覆層の平均層厚は、１．０〜４．０μｍと定めた。
硬質被覆層の組成および層厚は工具基体表面に垂直な硬質被覆層の縦断面について、工具基体表面に平行な方向の幅が１０μｍであり、硬質被覆層の厚み領域が全て含まれるよう設定された視野について、走査型電子顕微鏡（Ｓｃａｎｎｉｎｇ Ｅｌｅｃｔｒｏｎ Ｍｉｃｒｏｓｃｏｐｙ：ＳＥＭ）、透過型電子顕微鏡（Ｔｒａｎｓｍｉｓｓｉｏｎ Ｅｌｅｃｔｒｏｎ Ｍｉｃｒｏｓｃｏｐｅ：ＴＥＭ）、エネルギー分散型Ｘ線分光法（Ｅｎｅｒｇｙ Ｄｉｓｐｅｒｓｉｖｅ Ｘ−ｒａｙ Ｓｐｅｃｔｒｏｓｃｏｐｙ：ＥＤＳ）、オージェ電子分光法（Ａｕｇｅｒ ｅｌｅｃｔｒｏｎ ｓｐｅｃｔｒｏｓｃｏｐｙ：ＡＥＳ）を用いた断面測定により、測定する。層厚を複数箇所で測定し、これを平均することにより、平均層厚を算出した。なお、工具基体表面とは、基体の硬質被覆層と接する面の面方向に垂直な断面の観察像における、基体と硬質被覆層の界面粗さの基準線とする。
Hard coating composition and average layer thickness:
The hard coating layer of the coated tool of the present invention is
Composition formula: (Ti 1-x Al x ) N
In this case, it is composed of a composite nitride layer of Ti and Al having a composition satisfying 0.4 ≦ x ≦ 0.7 (where x is an atomic ratio).
In the above composition formula, by setting the value of x to 0.4 (atomic ratio) or more, the high temperature hardness and high temperature oxidation resistance in the (Ti, Al) N layer are improved. If it exceeds 7 (atomic ratio), not only is it difficult to maintain the rock salt crystal structure, but it becomes amorphous easily and the hardness decreases, so Al content in the total amount of Ti and Al The ratio (however, the atomic ratio) was determined to be 0.4 ≦ x ≦ 0.7.
In the above composition formula, the metal element composed of Ti and Al and the non-metal element composed of N are described in a form as if the atomic ratio is 1: 1, but the important thing is that Ti and The ratio between the metal element [Ti, Al] and the non-metal element [N] is not limited to 1: 1, and the same crystal structure as in the case of 1: 1 is maintained. In this case, the ratio of the metal element [Ti, Al] and the non-metal element [N] may be out of 1: 1.
Further, when the (Ti, Al) N layer has an average layer thickness of less than 1.0 μm, a region in which particles having close crystal orientations gather on the surface of the hard coating layer can be formed with a sufficient area ratio. On the other hand, if the average layer thickness of the (Ti, Al) N layer exceeds 4.0 μm, chipping and defects are likely to occur in high-speed cutting, so a hard coating layer composed of a (Ti, Al) N layer The average layer thickness was determined to be 1.0 to 4.0 μm.
The composition and thickness of the hard coating layer are set so that the width in the direction parallel to the tool substrate surface is 10 μm in the longitudinal section of the hard coating layer perpendicular to the tool substrate surface, and the entire thickness region of the hard coating layer is included. Scanning Electron Microscopy (SEM), Transmission Electron Microscope (TEM), Energy Dispersive X-ray Spectroscopy (SEM), Energy Dispersive X-ray Spectroscopy Electron Spectroscopy It measures by the cross-sectional measurement using (Auger electron spectroscopy: AES). The layer thickness was measured at a plurality of locations and averaged to calculate the average layer thickness. The surface of the tool base is a reference line for the roughness of the interface between the base and the hard coating layer in an observation image of a cross section perpendicular to the surface direction of the surface of the base that contacts the hard coating layer.
硬質被覆層の結晶組織および柱状組織の平均厚さ：
図１（ｂ）の模式図に示すように、本発明の被覆工具の硬質被覆層を構成する（Ｔｉ，Ａｌ）Ｎ層の結晶組織は、工具基体との界面側（工具基体との界面近傍）で結晶粒の平均幅が０．０１〜０．０５μｍの微粒組織、また、硬質被覆層表面側では結晶粒の平均幅が０．０５〜１．０μｍの柱状組織である。
工具基体との界面側の結晶組織を微粒組織としたのは、工具基体と硬質被覆層との密着強度を高めるためであり、また、硬質被覆層表面側で柱状組織としたのは、結晶粒界を少なくすることで粒界を起点とする破壊を抑制すると同時に、硬質被覆層表面に前記結晶方位の近い粒子が集まった領域を形成し、隣り合う結晶粒同士の結合を強固なものとして、耐チッピング性、耐欠損性を高めるとともに、より一段と耐摩耗性（特に、耐擦れ摩耗性）を高めるためである。
ここで、工具基体との界面側（工具基体との界面近傍）に形成される微粒組織において、結晶粒の平均幅が０．０１μｍ未満であると、硬質被覆層表面側に所定の平均幅の柱状組織が形成されず、一方、平均幅が０．０５μｍを超えると、結晶粒の粗大化が進行し粗粒が形成され、結晶粒界が少なくなることで皮膜-基体界面で生じたクラックが分散されにくくなり、所望の密着強度を得られなくなることから、工具基体との界面側（工具基体との界面近傍）に形成される微粒組織における結晶粒の平均幅は０．０１〜０．０５μｍと定めた。
また、硬質被覆層表面側においては、結晶粒の平均幅が０．０５μｍ以上の柱状組織を形成することによって、切削加工時の負荷による粒界からの破壊に起因するチッピング、欠損、剥離等の発生が抑制されるとともに耐摩耗性の向上が図られるが、結晶粒の平均幅が１．０μｍを超えると、粗大な柱状組織の形成により硬さが低下し、耐摩耗性が低下することから、硬質被覆層表面側に形成される柱状組織における結晶粒の平均幅は０．０５〜１．０μｍと定めた。
Average thickness of crystal structure and columnar structure of hard coating layer:
As shown in the schematic diagram of FIG. 1B, the crystal structure of the (Ti, Al) N layer constituting the hard coating layer of the coated tool of the present invention is the interface side with the tool base (near the interface with the tool base). ) In which the average width of the crystal grains is 0.01 to 0.05 μm, and the average width of the crystal grains is 0.05 to 1.0 μm on the hard coating layer surface side.
The reason why the crystal structure on the interface side with the tool base is a fine grain structure is to increase the adhesion strength between the tool base and the hard coating layer, and the columnar structure on the hard coating layer surface side is the crystal grain. At the same time as suppressing the fracture starting from the grain boundary by reducing the boundaries, forming a region where the grains near the crystal orientation gathered on the surface of the hard coating layer, as a strong bond between adjacent crystal grains, This is to increase chipping resistance and chipping resistance, and to further improve wear resistance (particularly abrasion resistance).
Here, in the fine grain structure formed on the interface side with the tool base (near the interface with the tool base), if the average width of the crystal grains is less than 0.01 μm, a predetermined average width is formed on the hard coating layer surface side. On the other hand, when the columnar structure is not formed and the average width exceeds 0.05 μm, the coarsening of the crystal grains proceeds and coarse grains are formed, and the cracks generated at the film-substrate interface are reduced by reducing the crystal grain boundaries. Since it becomes difficult to disperse and desired adhesion strength cannot be obtained, the average width of crystal grains in the fine grain structure formed on the interface side with the tool base (near the interface with the tool base) is 0.01 to 0.05 μm. It was determined.
In addition, on the hard coating layer surface side, by forming a columnar structure with an average width of crystal grains of 0.05 μm or more, chipping, chipping, peeling, etc. caused by breakage from the grain boundary due to load during cutting processing Although generation is suppressed and wear resistance is improved, if the average width of the crystal grains exceeds 1.0 μm, the hardness decreases due to the formation of a coarse columnar structure, and the wear resistance decreases. The average width of crystal grains in the columnar structure formed on the hard coating layer surface side was determined to be 0.05 to 1.0 μm.
前記工具基体との界面側に存在する微粒組織を構成する結晶粒の幅、また、硬質被覆層表面側で柱状組織を構成する結晶粒の幅は、以下の方法によって測定することができ、また、その測定値を平均化することによって、微粒組織あるいは柱状組織の結晶粒の平均幅を求めることができる。
具体的には、まず、工具基体表面に垂直な縦断面のＳＥＭを用いた断面観察により得られた縦断面画像について、ＥＢＳＤを用いて層を形成する各粒子の形状を決定し、一つ一つの結晶粒子について最大結晶粒長さＬを決定する。そして、最大結晶粒長さＬを対角線とし、工具基体表面に垂直な縦断面における断面積が等価となるように結晶粒子の形状を長方形近似し、得られた長方形の短辺をそれぞれの結晶粒の幅とした。
The width of the crystal grains constituting the fine grain structure existing on the interface side with the tool substrate, and the width of the crystal grains constituting the columnar structure on the hard coating layer surface side can be measured by the following method, and By averaging the measured values, the average width of crystal grains of a fine grain structure or a columnar structure can be obtained.
Specifically, first, the shape of each particle forming a layer is determined for each longitudinal cross-sectional image obtained by cross-sectional observation using an SEM having a vertical cross-section perpendicular to the tool substrate surface, using EBSD. The maximum grain length L is determined for one crystal grain. The maximum crystal grain length L is a diagonal line, and the shape of the crystal grains is approximated to a rectangle so that the cross-sectional areas in the vertical cross section perpendicular to the tool base surface are equivalent. And the width.
以上のように、硬質被覆層を構成する（Ｔｉ，Ａｌ）Ｎ層の結晶組織は、工具基体との界面側では所定平均幅の微粒組織、また、硬質被覆層表面側では所定平均幅の柱状組織からなるが、硬質被覆層表面に、所定面積割合の結晶方位の近い粒子が集まった領域を形成するためには、柱状組織の層厚方向の平均厚さは、０．３〜１．５μｍ（但し、硬質被覆層の層厚より当然に薄い）の範囲内の平均厚さで形成することが必要である。
柱状組織の層厚方向の平均厚さが０．３μｍ未満である場合には、平均幅が０．５〜２．０μｍであり、かつ、硬質被覆層表面に占める面積割合が３０〜８０面積％となる結晶方位の近い粒子が集まった領域を形成することができず、一方、柱状組織の層厚方向の平均厚さが１．５μｍを超えると、粗大柱状晶の形成による耐摩耗性の低下が生じるからである。
As described above, the crystal structure of the (Ti, Al) N layer constituting the hard coating layer is a fine grain structure with a predetermined average width on the interface side with the tool base, and a columnar structure with a predetermined average width on the hard coating layer surface side. Although it is composed of a structure, the average thickness in the layer thickness direction of the columnar structure is 0.3 to 1.5 μm in order to form a region where grains having a predetermined area ratio and near crystal orientations gather on the surface of the hard coating layer. However, it is necessary to form with an average thickness within the range of (though naturally thinner than the layer thickness of the hard coating layer).
When the average thickness in the layer thickness direction of the columnar structure is less than 0.3 μm, the average width is 0.5 to 2.0 μm, and the area ratio in the hard coating layer surface is 30 to 80 area%. When the average thickness in the layer thickness direction of the columnar structure exceeds 1.5 μm, the wear resistance decreases due to the formation of coarse columnar crystals. This is because.
前記柱状組織の層厚方向の厚さは、以下の方法によって測定することができ、その測定値を平均化することによって、層厚方向の平均厚さを求めることができる。まず、工具基体表面に垂直な硬質被覆層の縦断面について、各結晶粒の形状を決定し、それぞれの結晶幅を決定する。縦断面画像において、工具基体表面に平行な直線を引き、直線にかかる結晶の結晶幅の平均値をａとしたとき、ａが０．０５μｍ以上となる直線のうち、最も基材の表面側に近い直線を、本願における柱状組織と粒状組織の境界とする。この境界から硬質被覆層表面までの長さを前記柱状組織の層厚とし、複数視野において測定した層厚を平均することで、前記柱状組織の平均厚さを求める。 The thickness of the columnar structure in the layer thickness direction can be measured by the following method, and the average thickness in the layer thickness direction can be obtained by averaging the measured values. First, regarding the longitudinal section of the hard coating layer perpendicular to the tool base surface, the shape of each crystal grain is determined, and the respective crystal widths are determined. In the longitudinal cross-sectional image, when a straight line parallel to the surface of the tool base is drawn and the average value of the crystal width of the crystal applied to the straight line is a, the straight line on which the a is 0.05 μm or more is closest to the surface side of the substrate. A near straight line is defined as a boundary between the columnar structure and the granular structure in the present application. The length from this boundary to the hard coating layer surface is taken as the layer thickness of the columnar structure, and the average thickness of the columnar structure is obtained by averaging the layer thicknesses measured in a plurality of fields of view.
硬質被覆層表面の結晶方位の近い粒子が集まった領域：
硬質被覆層表面には、前述したように、複数の結晶粒の集合体からなり、領域内の各結晶粒の結晶方位の差が２度以上１０度以下である領域であって、しかも、工具基体表面の法線方向に対する該領域内の各結晶粒の結晶方位の傾斜角度差が最も小さい結晶方位＜１００＞のベクトルを平均した方位と基体表面の法線方向のなす角度が１０度以下である結晶方位の近い粒子が集まった領域を形成する。
前記結晶方位の近い粒子が集まった領域は、その平均幅が０．５μｍ未満であると耐擦れ摩耗性を向上させる効果が十分でなく、一方、その平均幅が２．０μｍを超えると結晶方位が広範囲で揃うため、結晶粒界を起点にしたクラックが進展しやすくなり、耐チッピング性が低下する。
このため、前記結晶方位の近い粒子が集まった領域の平均幅は、０．５〜２．０μｍとする。
また、硬質被覆層表面に占める前記結晶方位の近い粒子が集まった領域の面積割合が３０面積％未満であると耐摩耗性を向上させる効果が十分でなく、一方、８０面積％を超えると結晶方位が広範囲で揃うため、結晶粒界を起点にしたクラックが進展しやすくなり、耐チッピング性が低下する。
このため、前記結晶方位の近い粒子が集まった領域が硬質被覆層表面に占める面積割合は、３０〜８０面積％とする。
また、前記結晶方位の近い粒子が集まった領域について、工具基体表面に垂直な断面方向の該領域内の結晶粒の結晶方位を平均したとき、隣り合う領域同士の平均した結晶方位の差が１５度以下あるいは７５度以上であると、隣り合う領域同士の結晶粒界の向きが近くなるため、隣り合う領域間において結晶粒界を起点としたクラックが進展しやすくなり、突発的なチッピングが生じやすくなる。このため、隣り合う領域同士の結晶方位の差は１５度を超え、７５度未満であることがより好ましい。
Area where particles of close crystal orientation gather on the surface of the hard coating layer:
As described above, the surface of the hard coating layer is an area composed of an aggregate of a plurality of crystal grains, and the difference in crystal orientation of each crystal grain in the area is not less than 2 degrees and not more than 10 degrees. The angle between the orientation of the average of the crystal orientation <100> vectors and the normal direction of the substrate surface that is the smallest difference in the tilt angle of the crystal orientation of each crystal grain in the region with respect to the normal direction of the substrate surface is 10 degrees or less. A region in which grains having a certain crystal orientation are gathered is formed.
When the average width is less than 0.5 μm, the region where the grains having similar crystal orientations gather is not sufficient in improving the abrasion and wear resistance, whereas when the average width exceeds 2.0 μm, the crystal orientation Therefore, cracks starting from the grain boundaries are likely to progress, and chipping resistance is reduced.
For this reason, the average width of the region where the grains having similar crystal orientations gather is set to 0.5 to 2.0 μm.
Further, if the area ratio of the region where the grains having close crystal orientation occupy on the surface of the hard coating layer is less than 30% by area, the effect of improving the wear resistance is not sufficient. Since the orientations are aligned over a wide range, cracks starting from the grain boundaries are likely to progress, and chipping resistance is reduced.
For this reason, the area ratio which the area | region where the particle | grains with the near crystal orientation gathered occupies for the hard coating layer surface shall be 30-80 area%.
Further, when the crystal orientation of the crystal grains in the region in the cross-sectional direction perpendicular to the tool base surface is averaged in the region where the grains having close crystal orientations gather, the difference in average crystal orientation between adjacent regions is 15 If the angle is less than 75 degrees or greater than 75 degrees, the direction of the crystal grain boundary between adjacent regions becomes closer, so that cracks starting from the crystal grain boundary are likely to progress between adjacent regions, causing sudden chipping. It becomes easy. For this reason, the difference in crystal orientation between adjacent regions is more preferably greater than 15 degrees and less than 75 degrees.
硬質被覆層表面の結晶方位の近い粒子が集まった領域の特定：
前記結晶方位の近い粒子が集まった領域の特定、また、結晶方位の近い粒子が集まった領域の幅、面積割合は、例えば、以下の方法で測定し、測定値の平均を算出することによって、結晶方位の近い粒子が集まった領域の平均幅、面積割合を求めることができる。
具体的には、まず、工具基体表面の法線方向からＥＢＳＤを用いて分析を行い、硬質被覆層を形成する各粒子を決定し、一つ一つの結晶粒子の工具基体表面に垂直な方向の結晶方位を決定する。次に隣り合う結晶粒同士の結晶方位の差が２度以上１０度以下である領域を決定する。そして、ここで決定した各領域内の各々の結晶粒に対して、工具基体表面の法線方向に対する結晶方位の傾斜角度差が最も小さい結晶方位＜１００＞のベクトルを求め、各領域のうち、これらのベクトルを平均した方位と基体表面の法線方向のなす角度が１０度以下である領域を定める。こうして決定した領域が本発明における、結晶方位の近い粒子が集まった領域、である。該領域に対して、面積が等価になるような円形状近似を行い、こうして決定した円の直径および面積を該領域の幅および面積とする。測定視野内の結晶方位の近い粒子が集まった領域それぞれに対する幅を平均した値を平均幅、それぞれの面積を合計したものを測定視野の面積で除した値を面積割合とし、複数視野で測定した値を平均し、本発明品における、結晶方位の近い粒子が集まった領域の平均幅、面積割合を求める。
Identifying the area of particles with close crystal orientation on the hard coating surface:
Identification of the region where the particles having near crystal orientation are gathered, and the width and area ratio of the region where the particles having close crystal orientation are gathered are measured by, for example, the following method, and by calculating the average of the measured values, The average width and area ratio of the region where grains having similar crystal orientations gather can be obtained.
Specifically, first, analysis is performed from the normal direction of the tool base surface using EBSD to determine each particle forming the hard coating layer, and each crystal grain in the direction perpendicular to the tool base surface. Determine crystal orientation. Next, a region where the difference in crystal orientation between adjacent crystal grains is 2 degrees or more and 10 degrees or less is determined. Then, for each crystal grain in each region determined here, a vector of crystal orientation <100> having the smallest inclination angle difference of the crystal orientation with respect to the normal direction of the surface of the tool base is obtained, and among each region, A region is defined in which the angle formed by the average of these vectors and the normal direction of the substrate surface is 10 degrees or less. The region thus determined is a region in the present invention in which particles having similar crystal orientations gather. A circular shape approximation is performed on the region so that the area is equivalent, and the diameter and area of the circle thus determined are set as the width and area of the region. The value obtained by averaging the width for each region where particles with similar crystal orientation in the measurement field gathered is the average width, and the value obtained by dividing the total area by the area of the measurement field is the area ratio, and measured in multiple fields. The values are averaged, and the average width and area ratio of the region in which the grains having similar crystal orientations gather in the present invention are obtained.
硬質被覆層の結晶配向性：
本発明では、硬質被覆層表面近傍の柱状組織の形成および硬質被覆層表面の結晶方位の近い粒子が集まった領域の形成を促進するため、硬質被覆層の結晶配向性を制御することが望ましい。
即ち、成膜パラメータの調整により成膜速度を低減することで表面エネルギーの小さい(１００)面が優先的に成長するように操作し、ＥＢＳＤによる結晶方位解析を行ったとき、基体表面の法線方向から０〜１０度の範囲内に結晶方位＜１００＞を有する結晶粒の面積割合を４０面積％以上とすることで、柱状組織が形成されやすくなり、その結果、硬質被覆層表面における結晶方位の近い粒子が集まった領域の形成が促進される。しかし、基体表面の法線方向から０〜１０度の範囲内に結晶方位＜１００＞を有する結晶粒の面積割合が９０面積％を超えると結晶方位が広範囲で揃うため、結晶粒界を起点にしたクラックが進展しやすくなり、高負荷切削における耐欠損性が低下する。
したがって、基体表面の法線方向から０〜１０度の範囲内に結晶方位＜１００＞を有する結晶粒の面積割合は４０面積％以上９０面積％以下とすることが望ましい。
Crystal orientation of the hard coating layer:
In the present invention, it is desirable to control the crystal orientation of the hard coating layer in order to promote the formation of a columnar structure in the vicinity of the hard coating layer surface and the formation of a region in which particles having similar crystal orientations gather on the hard coating layer surface.
That is, when the film orientation is reduced by adjusting the film formation parameters, the (100) plane having a small surface energy is preferentially grown and the crystal orientation analysis by EBSD is performed. By making the area ratio of crystal grains having a crystal orientation <100> within a range of 0 to 10 degrees from the direction to be 40% by area or more, a columnar structure is easily formed. As a result, the crystal orientation on the surface of the hard coating layer Formation of a region where particles close to each other gather is promoted. However, if the area ratio of the crystal grains having the crystal orientation <100> within the range of 0 to 10 degrees from the normal direction of the substrate surface exceeds 90 area%, the crystal orientations are aligned in a wide range. Cracks tend to develop, and the fracture resistance in high-load cutting decreases.
Therefore, the area ratio of crystal grains having a crystal orientation <100> within a range of 0 to 10 degrees from the normal direction of the substrate surface is desirably 40 area% or more and 90 area% or less.
工具基体：
硬質被覆層表面の結晶方位の近い粒子が集まった領域の形成を促進する上で、基体表面の法線方向から０〜１０度の範囲内に結晶方位＜１００＞を有する結晶粒の面積割合が重要であることは前記のとおりであるが、ｃＢＮ焼結体からなる工具基体におけるｃＢＮ粒子の平均粒径、含有割合も、工具基体表面近傍の微粒組織、硬質被覆層表面近傍の柱状組織および硬質被覆層表面の結晶方位の近い粒子が集まった領域の形成に影響を及ぼす。
即ち、ｃＢＮ粒子を起点として（Ｔｉ，Ａｌ）Ｎ結晶粒が成長する場合は、ｃＢＮと（Ｔｉ，Ａｌ）Ｎは化学結合の種類が異なるため、（Ｔｉ，Ａｌ）Ｎ結晶粒が成長する際の結晶方位はｃＢＮ粒子から受ける影響が少なく、成膜条件に応じた方位に優先的に成長し、しかも、ランダムに形成された微細な結晶核が結晶成長の初期から競合しながら成長するため、結晶方位の近い結晶粒がまとまって成長しやすくなる。
一方、ｃＢＮ焼結体の結合相として用いられるＴｉＮなどは（Ｔｉ，Ａｌ）Ｎ結晶粒と同じ化学結合であるため、ｃＢＮ粒子上ではなくｃＢＮ焼結体の結合相上の成長核から成長した場合には、（Ｔｉ，Ａｌ）Ｎ結晶粒の成長は、起点となる結合相の結晶サイズおよび結晶方位に強く影響される。このため、成膜条件に応じた方位と結合相の影響を受けた方位でそれぞれ結晶粒が成長し、その後成長した結晶粒同士が競合しながら成長するため、本発明品のような層厚の範囲内では、結晶方位の近い結晶粒が成長しにくくなる。 したがって、工具基体表面近傍の微粒組織、硬質被覆層表面近傍の柱状組織および硬質被覆層表面の結晶方位の近い粒子が集まった領域を適正に形成するためには、工具基体として、平均粒径が２．０〜４．０μｍのｃＢＮ粒子が５０〜８０体積％存在し、かつｃＢＮ粒子とＴｉの窒化物、炭化物、炭窒化物、硼化物およびＡｌの窒化物、酸化物からなる群から選ばれた少なくとも１種以上の粒子と不可避不純物とを含む結合相とからなるｃＢＮ焼結体を用いることが望ましく、ｃＢＮ粒子の平均粒径、体積割合、ひいては成膜時の基体表面におけるｃＢＮ粒子と結合相の露出状態を操作することで、結晶方位の近い粒子が集まった領域の形成を制御することができる。
なお、ｃＢＮ焼結体中のｃＢＮ粒子の粒径およびｃＢＮ粒子の含有割合（体積％）は、以下の方法で測定することができ、得られた測定値を平均化することにより、ｃＢＮ粒子の平均粒径およびｃＢＮ粒子の含有割合（体積％）求めることができる。 具体的には、作製したｃＢＮ焼結体の断面組織を走査型電子顕微鏡（Ｓｃａｎｎｉｎｇ Ｅｌｅｃｔｒｏｎ Ｍｉｃｒｏｓｃｏｐｙ：ＳＥＭ）にて観察して得られた二次電子画像内のｃＢＮ粒子の部分を画像処理にて抜き出し、画像解析によって各ｃＢＮ粒子の最大長を求め、それを各ｃＢＮ粒子の直径とし、１画像におけるｃＢＮ粒子の直径の平均値を求め、少なくとも３画像について求めた平均値の平均をｃＢＮの平均粒径［μｍ］とした。また同様に、画像解析によって観察領域におけるｃＢＮ焼結体の全体の面積に対するｃＢＮ粒子が占める面積を算出し、少なくとも３画像を処理し求めた値の平均値をｃＢＮ粒子の含有割合（体積％）とした。画像処理に用いる観察領域は予備観察を行うことによって定めたが、ｃＢＮ粒子の平均粒径が２．０〜４．０μｍであることをかんがみ、１５μｍ×１５μｍ程度の視野領域とすることが望ましい。
Tool base:
In promoting the formation of a region in which grains having close crystal orientation on the surface of the hard coating layer are collected, the area ratio of crystal grains having a crystal orientation <100> within a range of 0 to 10 degrees from the normal direction of the substrate surface is As described above, what is important is that the average particle size and content ratio of cBN particles in the tool base made of a cBN sintered body are also a fine grain structure near the tool base surface, a columnar structure near the hard coating layer surface, and a hard structure. Affects the formation of a region where grains having similar crystal orientations gather on the surface of the coating layer.
That is, when (Ti, Al) N crystal grains are grown starting from cBN particles, since the types of chemical bonds are different between cBN and (Ti, Al) N, the (Ti, Al) N crystal grains are grown. The crystal orientation is less affected by the cBN grains, grows preferentially in the orientation according to the film formation conditions, and the randomly formed fine crystal nuclei grow while competing from the initial stage of crystal growth. Crystal grains with similar crystal orientations are easily grown together.
On the other hand, TiN used as the binder phase of the cBN sintered body has the same chemical bond as the (Ti, Al) N crystal grains, so it grew from the growth nucleus on the binder phase of the cBN sintered body, not on the cBN particles. In some cases, the growth of (Ti, Al) N crystal grains is strongly influenced by the crystal size and crystal orientation of the binder phase as a starting point. For this reason, crystal grains grow in the orientation according to the film formation conditions and the orientation affected by the binder phase, and then the grown crystal grains grow while competing with each other. Within the range, crystal grains having close crystal orientations are difficult to grow. Therefore, in order to properly form a region in which the fine grain structure near the surface of the tool base, the columnar structure near the surface of the hard coating layer, and the grains having close crystal orientation on the surface of the hard coating layer are gathered, 50 to 80% by volume of cBN particles of 2.0 to 4.0 μm are present and are selected from the group consisting of cBN particles and Ti nitride, carbide, carbonitride, boride, Al nitride, and oxide. It is desirable to use a cBN sintered body comprising at least one kind of particles and a binder phase containing inevitable impurities. The cBN particles have an average particle diameter, a volume ratio, and bonded to the cBN particles on the substrate surface during film formation. By manipulating the phase exposure state, the formation of a region in which grains having similar crystal orientations gather can be controlled.
In addition, the particle size of cBN particles in the cBN sintered body and the content ratio (volume%) of the cBN particles can be measured by the following method, and by averaging the obtained measurement values, The average particle diameter and the content ratio (volume%) of cBN particles can be determined. Specifically, the cBN particle portion in the secondary electron image obtained by observing the cross-sectional structure of the produced cBN sintered body with a scanning electron microscope (SEM) is extracted by image processing. Then, the maximum length of each cBN particle is determined by image analysis, the diameter of each cBN particle is used as the diameter of each cBN particle, the average value of the diameter of cBN particles in one image is determined, and the average of the average values determined for at least three images is the average particle size of cBN The diameter was [μm]. Similarly, the area occupied by the cBN particles relative to the entire area of the cBN sintered body in the observation region is calculated by image analysis, and the average value of the values obtained by processing at least three images is the content ratio (volume%) of the cBN particles. It was. The observation area used for the image processing is determined by performing preliminary observation. However, it is desirable that the viewing area is about 15 μm × 15 μm in view of the average particle size of the cBN particles being 2.0 to 4.0 μm.
本発明の被覆工具は、工具基体表面近傍の（Ｔｉ，Ａｌ）Ｎ層を微粒組織とし、一方、硬質被覆層表面側の（Ｔｉ，Ａｌ）Ｎ層を柱状組織として形成するとともに、硬質被覆層表面の柱状組織の少なくとも一部に、複数の結晶粒の集合体からなり、該集合体の平均幅が０．５〜２．０μｍであり、硬質被覆層の表面に占める面積割合が３０〜８０面積％である結晶方位の近い粒子が集まった領域を形成することによって、隣り合う結晶粒同士の結合が強靭になるため、切れ刃に高負荷が作用する高速切削加工に供された場合においても、チッピング、欠損等の発生もなく長期の使用にわたってすぐれた耐摩耗性を発揮する。 The coated tool of the present invention has a (Ti, Al) N layer near the surface of the tool base as a fine grain structure, while a (Ti, Al) N layer on the hard coating layer surface side is formed as a columnar structure, and a hard coating layer. At least part of the surface columnar structure is composed of an aggregate of a plurality of crystal grains, the average width of the aggregate is 0.5 to 2.0 μm, and the area ratio of the surface of the hard coating layer is 30 to 80 By forming a region where grains with close crystal orientation, which are area%, gather, the bonds between adjacent crystal grains become tough, so even when subjected to high-speed cutting where a high load acts on the cutting edge Excellent wear resistance over a long period of use without chipping or chipping.
つぎに、本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.
工具基体の作製：
原料粉末として、２．０〜４．０μｍの平均粒径を有するｃＢＮ粒子を硬質相形成用原料粉末として用意するとともに、いずれも２．０μｍ以下の平均粒径を有するＴｉＮ粉末、ＴｉＣ粉末、ＴｉＣＮ粉末、Ａｌ粉末、ＡｌＮ粉末、Ａｌ２Ｏ３粉末を結合相形成用原料粉末として用意した。
次いで、所定の表１に示す配合組成となるように配合したこの原料粉末を、ボールミルで７２時間湿式混合し、乾燥した後、成形圧１００ＭＰａで直径：５０ｍｍ×厚さ：１．５ｍｍの寸法にプレス成形し、ついでこの成形体を、圧力：１Ｐａ以下の真空雰囲気中、９００〜１３００℃の範囲内の所定温度に保持して仮焼結し、その後、超高圧焼結装置に装入して、圧力：５ＧＰa、温度：１２００〜１４００℃の範囲内の所定の温度で焼結することにより、ｃＢＮ焼結体１〜９を作製した。
Tool substrate production:
As the raw material powder, cBN particles having an average particle diameter of 2.0 to 4.0 μm are prepared as a raw material powder for forming a hard phase, and all of them are TiN powder, TiC powder, TiCN having an average particle diameter of 2.0 μm or less. Powder, Al powder, AlN powder, and Al 2 O 3 powder were prepared as binder phase forming raw material powders.
Next, the raw material powder blended so as to have the blending composition shown in Table 1 was wet-mixed for 72 hours with a ball mill, dried, and then formed into a size of diameter: 50 mm × thickness: 1.5 mm at a molding pressure of 100 MPa. Then press molding, and then pre-sintering this compact in a vacuum atmosphere with a pressure of 1 Pa or less at a predetermined temperature within a range of 900 to 1300 ° C., and then inserting it into an ultra-high pressure sintering apparatus. CBN sintered bodies 1 to 9 were prepared by sintering at a predetermined temperature within a range of pressure: 5 GPa and temperature: 1200 to 1400 ° C.
上記で得られたｃＢＮ焼結体をワイヤー放電加工機で所定寸法に切断し、Ｃｏ：５質量％、ＴａＣ：５質量％、ＷＣ：残りの組成およびＩＳＯ規格ＣＮＧＡ１２０４０８のインサート形状をもったＷＣ基超硬合金製インサート本体のろう付け部（コーナー部）に、質量％で、Ｃｕ：２６％、Ｔｉ：５％、Ａｇ：残りからなる組成を有するＡｇ系ろう材を用いてろう付けし、上下面および外周研磨、ホーニング処理を施すことによりＩＳＯ規格ＣＮＧＡ１２０４０８のインサート形状をもった工具基体１〜９を製造した。 The cBN sintered body obtained above was cut to a predetermined size with a wire electric discharge machine, Co: 5 mass%, TaC: 5 mass%, WC: remaining composition and WC base having an insert shape of ISO standard CNGA120408 Brazing the brazed part (corner part) of the cemented carbide alloy insert body using an Ag-based brazing material having a composition of Cu: 26%, Ti: 5%, and Ag: the rest, The tool bases 1 to 9 having the insert shape of ISO standard CNGA120408 were manufactured by subjecting the lower surface and outer periphery to grinding and honing.
硬質被覆層の成膜：
前述の工程によって作製した工具基体１〜９に対して、図２に示すアークイオンプレーティング装置を用いて、硬質被覆層を形成した。
（ａ）まず、工具基体１〜９を、アセトン中で超音波洗浄し、乾燥した状態で、アークイオンプレーティング装置内の回転テーブル上の中心軸から半径方向に所定距離離れた位置に外周部にそって装着する。また、カソード電極（蒸発源）として、所定組成のＴｉ−Ａｌ合金ターゲットを配置した。
（ｂ）次に、装置内を排気して１０−２Ｐａ以下の真空に保持しながら、ヒーターで装置内を５００℃に加熱した後、０．５〜４．０ＰａのＡｒガス雰囲気に設定し、前記回転テーブル上で自転しながら回転する工具基体に−４００〜−１０００Ｖの直流バイアス電圧を印加し、もって工具基体表面をアルゴンイオンによって５〜３０分間ボンバード処理した。
（ｃ）次に、工具基体表面に、まず、粒状組織の（Ｔｉ，Ａｌ）Ｎ層の成膜を、次のとおり行った。
装置内に反応ガスとして窒素ガスを導入して表２に示す０．５〜６Ｐａの所定の反応雰囲気とすると共に、前記回転テーブル上で自転しながら回転する工具基体に表２に示す−１０〜−１００Ｖの所定の直流バイアス電圧を印加し、かつ、前記Ｔｉターゲットからなるカソード電極（蒸発源）および前記所定組成のＴｉ−Ａｌ合金ターゲットからなるカソード電極（蒸発源）とアノード電極との間に表２に示す９０〜２００Ａの所定の電流を同時に所定時間流してアーク放電を発生させ、前記工具基体の表面に、表４に示される目標平均層厚の粒状組織からなる（Ｔｉ，Ａｌ）Ｎ層を蒸着形成した。
（ｄ）次いで、上記粒状組織の（Ｔｉ，Ａｌ）Ｎ層の上に、成膜条件を変更して柱状組織の（Ｔｉ，Ａｌ）Ｎ層の成膜を、次のとおり行った。
装置内に反応ガスとして窒素ガスを導入して表２に示す４〜１０Ｐａの範囲内の所定の反応雰囲気とすると共に、前記回転テーブル上で自転しながら回転する工具基体に表２に示す−１０〜−７５Ｖの範囲内の所定の直流バイアス電圧を印加し、かつ、前記Ｔｉ−Ａｌ合金ターゲットからなるカソード電極（蒸発源）とアノード電極との間に表２に示す９０〜１４０Ａの範囲内の所定の電流を流してアーク放電を発生させ、前記粒状組織の（Ｔｉ，Ａｌ）Ｎ層の上に、表４に示される目標平均層厚の柱状組織からなる（Ｔｉ，Ａｌ）Ｎを蒸着形成した。
上記（ａ）〜（ｄ）の工程により、本発明被覆工具（以下、「本発明工具」という）１〜９を作製した。
なお、本発明の皮膜組織の形成に関して、ｃＢＮ粒子の平均粒径、体積割合が重要な役割を果たすことは前述の通りであるが、成膜時の基体表面におけるｃＢＮ粒子と結合相の露出状態を制御するために、工具刃先を形成するｃＢＮ焼結体部分の研削後の表面粗度に関して、算術平均粗さＲａを０．０１〜１．０μｍの範囲となるようにすることがより好ましい。工具基体を作製する際、表面を研削することで硬さの小さい結合相が優先的に除去され、表面にｃＢＮ粒子が露出する。さらに、前記（ｂ）のように成膜前にボンバード処理を施すことで、表面のｃＢＮ粒子の露出状態を制御することができ、その結果、より本発明の皮膜組織を形成しやすくすることができる。本発明工具においては、レーザー顕微鏡によって研削後のｃＢＮ焼結体部分の表面粗度を確認した。
Formation of hard coating layer:
A hard coating layer was formed on the tool bases 1 to 9 produced by the above-described process using the arc ion plating apparatus shown in FIG.
(A) First, the tool bases 1 to 9 are ultrasonically cleaned in acetone and dried, and the outer peripheral portion is positioned at a predetermined distance in the radial direction from the central axis on the rotary table in the arc ion plating apparatus. Wear along. In addition, a Ti—Al alloy target having a predetermined composition was disposed as a cathode electrode (evaporation source).
(B) Next, the inside of the apparatus is evacuated and kept at a vacuum of 10 −2 Pa or less, and the inside of the apparatus is heated to 500 ° C. with a heater and then set to an Ar gas atmosphere of 0.5 to 4.0 Pa. A DC bias voltage of −400 to −1000 V was applied to the tool base rotating while rotating on the rotary table, and the tool base surface was bombarded with argon ions for 5 to 30 minutes.
(C) Next, a (Ti, Al) N layer having a granular structure was first formed on the tool base surface as follows.
Nitrogen gas is introduced into the apparatus as a reaction gas to obtain a predetermined reaction atmosphere of 0.5 to 6 Pa shown in Table 2, and the tool base that rotates while rotating on the rotary table is shown in Table 2 as shown in Table 2. A predetermined DC bias voltage of −100 V is applied, and a cathode electrode (evaporation source) made of the Ti target and a cathode electrode (evaporation source) made of a Ti—Al alloy target of the predetermined composition and the anode electrode A predetermined current of 90 to 200 A shown in Table 2 is simultaneously supplied for a predetermined time to generate an arc discharge, and the surface of the tool base is composed of a granular structure having a target average layer thickness shown in Table 4 (Ti, Al) N. Layers were deposited.
(D) Next, a (Ti, Al) N layer having a columnar structure was formed as follows on the (Ti, Al) N layer having the above-mentioned granular structure by changing the film forming conditions.
Nitrogen gas is introduced as a reaction gas into the apparatus to obtain a predetermined reaction atmosphere within the range of 4 to 10 Pa shown in Table 2, and the tool base that rotates while rotating on the rotary table is shown in Table-10. A predetermined DC bias voltage within the range of -75V is applied, and the cathode electrode (evaporation source) made of the Ti-Al alloy target and the anode electrode are within the range of 90-140A shown in Table 2. An arc discharge is generated by applying a predetermined current, and (Ti, Al) N having a columnar structure having a target average layer thickness shown in Table 4 is formed on the (Ti, Al) N layer having the granular structure by vapor deposition. did.
The coated tools of the present invention (hereinafter referred to as “the tool of the present invention”) 1 to 9 were produced by the steps (a) to (d).
As described above, the average particle diameter and volume ratio of the cBN particles play an important role in the formation of the coating structure of the present invention. However, the exposed state of the cBN particles and the binder phase on the substrate surface during film formation. In order to control the surface roughness after grinding of the cBN sintered body portion forming the tool cutting edge, it is more preferable that the arithmetic average roughness Ra be in the range of 0.01 to 1.0 μm. When producing the tool base, the surface is ground to preferentially remove the binder phase having a low hardness, and the cBN particles are exposed on the surface. Furthermore, by performing the bombardment before film formation as in (b) above, the exposed state of cBN particles on the surface can be controlled, and as a result, the film structure of the present invention can be more easily formed. it can. In the tool of the present invention, the surface roughness of the cBN sintered body after grinding was confirmed by a laser microscope.
比較のため、工具基体１〜９に対して、表３に示す条件で前記（ａ）〜（ｄ）の工程を行うことによって、表５に示す比較例被覆工具（以下、「比較例工具」という）１〜９を作製した。 For comparison, by performing the steps (a) to (d) on the tool bases 1 to 9 under the conditions shown in Table 3, a comparative example-coated tool shown in Table 5 (hereinafter referred to as “Comparative Tool”). 1-9 were produced.
上記で作製した本発明工具１〜９および比較例工具１〜９について、オージェ電子分光法（ＡＥＳ）を用いた硬質被覆層の断面測定により、硬質被覆層の組成を複数箇所で測定し、これを平均することにより、硬質被覆層の組成を求めた。
また、得られたｃＢＮ焼結体中のｃＢＮ粒子の含有割合（体積％）およびｃＢＮ粒子の平均粒径は、以下の測定法で測定することにより求めた。
本発明切削工具１〜９、比較切削工具１〜９の逃げ面を集束イオンビーム（Ｆｏｃｕｓｅｄ Ｉｏｎ Ｂｅａｍ：ＦＩＢ）を用いて断面加工し、刃先稜線に垂直な断面を形成し、断面組織を走査型電子顕微鏡（Ｓｃａｎｎｉｎｇ Ｅｌｅｃｔｒｏｎ Ｍｉｃｒｏｓｃｏｐｙ：ＳＥＭ）により観察し、二次電子画像を取得する。
観察領域は、１５μｍ×１５μｍ程度であって、ｃＢＮ焼結体中のｃＢＮ粒子および硬質被覆層の全体が観察できる倍率とする。
この二次電子画像から前述したような方法を用いて、ｃＢＮ粒子の平均粒径およびｃＢＮ粒子の含有割合（体積％）を測定した。
About this invention tool 1-9 produced above and comparative example tools 1-9, the composition of a hard coating layer is measured in several places by section measurement of a hard coating layer using Auger electron spectroscopy (AES), and this Was averaged to determine the composition of the hard coating layer.
Moreover, the content ratio (volume%) of the cBN particles in the obtained cBN sintered body and the average particle size of the cBN particles were determined by measuring with the following measuring method.
The cutting surfaces of the present cutting tools 1-9 and comparative cutting tools 1-9 are cross-sectioned using a focused ion beam (FIB) to form a cross section perpendicular to the edge of the cutting edge, and the cross-sectional structure is scanned. A secondary electron image is acquired by observing with an electron microscope (Scanning Electron Microscopy: SEM).
The observation area is about 15 μm × 15 μm, and the magnification is such that the entire cBN particles and the hard coating layer in the cBN sintered body can be observed.
From this secondary electron image, the average particle diameter of the cBN particles and the content ratio (volume%) of the cBN particles were measured using the method described above.
また、硬質被覆層の微粒組織あるいは柱状組織の結晶粒の平均幅、柱状組織の層厚方向の厚さ及び硬質被覆層の平均層厚を以下の測定法で測定することにより求めた。
本発明切削工具１〜９、比較切削工具１〜９の逃げ面をＦＩＢを用いて断面加工し、刃先稜線に垂直な断面を形成し、断面組織をＳＥＭにより観察し、二次電子画像を取得するとともにＥＢＳＤを用いて結晶方位の解析を行った。
観察領域は、１５μｍ×１５μｍ程度であって、ｃＢＮ焼結体中のｃＢＮ粒子および硬質被覆層の全体が観察できる倍率とする。ＥＢＳＤによる測定・解析は、観察領域に対してステップ間隔０．０２μｍの条件で実施し、測定点のうち、隣り合う点で結晶方位が２°以上異なる境目を結晶粒界として判断し、各結晶の形状を決定した。また、０．０２μｍ以下の結晶粒については観察領域をＦＩＢ加工によって薄片化し、透過型電子顕微鏡（ＴＥＭ）によって結晶粒の形状を直接観察し、画像のコントラストから結晶粒界を定めた。なお、ＥＢＳＤ測定を実施した視野と同じ画像視野において、０．０２μｍ以上の結晶粒形状についても透過型電子顕微鏡（ＴＥＭ）を用いた測定によって結晶形状を確認し、いずれの手法でも同等の結果が得られることを確認している。また、工具基体表面については、硬質被覆層の工具基体表面に垂直な縦断面においてＡＥＳを用いた元素マッピングを実施することによって硬質被覆層と工具基体の界面を定め、こうして得られた硬質被覆層と工具基体との界面の粗さ曲線について、平均線を算術的に求め、これを工具基体表面とした。
この二次電子画像およびＥＢＳＤ解析の結果から、前述したような方法を用いて、硬質被覆層の微粒組織あるいは柱状組織の結晶粒の平均幅、柱状組織の層厚方向の厚さ及び硬質被覆層の平均層厚を測定した。
Further, the average width of fine grains of the hard coating layer or the crystal grains of the columnar structure, the thickness in the layer thickness direction of the columnar structure, and the average layer thickness of the hard coating layer were determined by the following measurement methods.
The cutting surfaces of the present cutting tools 1-9 and comparative cutting tools 1-9 are cross-sectioned using FIB, a cross section perpendicular to the edge of the cutting edge is formed, the cross-sectional structure is observed by SEM, and a secondary electron image is acquired. In addition, the crystal orientation was analyzed using EBSD.
The observation area is about 15 μm × 15 μm, and the magnification is such that the entire cBN particles and the hard coating layer in the cBN sintered body can be observed. Measurement and analysis by EBSD is performed under the condition of a step interval of 0.02 μm with respect to the observation region, and a boundary where the crystal orientation differs by 2 ° or more at adjacent points among the measurement points is determined as a crystal grain boundary. The shape of was determined. For crystal grains of 0.02 μm or less, the observation region was sliced by FIB processing, and the shape of the crystal grains was directly observed by a transmission electron microscope (TEM), and the crystal grain boundaries were determined from the contrast of the image. In addition, in the same image field as the field of view where the EBSD measurement was performed, the crystal shape of the crystal grain shape of 0.02 μm or more was confirmed by measurement using a transmission electron microscope (TEM). It is confirmed that it can be obtained. In addition, for the tool base surface, element mapping using AES is performed in a longitudinal section perpendicular to the tool base surface of the hard coating layer to define the interface between the hard coating layer and the tool base, and the hard coating layer thus obtained For the roughness curve of the interface between the tool base and the tool base, an average line was obtained arithmetically and used as the tool base surface.
From the results of the secondary electron image and EBSD analysis, the method as described above is used to determine the average width of the fine grain structure or columnar structure crystal grains, the thickness of the columnar structure in the layer thickness direction, and the hard coating layer. The average layer thickness of was measured.
硬質被覆層表面の結晶方位の近い粒子が集まった領域について、結晶方位の近い粒子が集まった領域の平均幅、面積割合を以下の測定によって求めた。
本発明切削工具１〜９、比較切削工具１〜９の逃げ面に対して、硬質被覆層表面をＦＩＢを用いて加工し、工具基体表面に平行な面を作製し、加工面に対してＥＢＳＤ解析を行い、前述した方法を用いて、結晶方位の近い粒子が集まった領域の平均幅、面積割合を求めた。測定領域は、結晶方位の近い粒子が集まった領域の平均幅が０．５〜２．０μｍであることを鑑み、１５μｍ×１５μｍ程度とし、それぞれの工具について３視野ずつ測定した平均値を該工具の測定値とした。
The average width and area ratio of the region where the grains having close crystal orientation gathered were determined by the following measurement for the region where the grains having close crystal orientation gathered on the surface of the hard coating layer.
The cutting surfaces 1 to 9 of the present invention and the flank surfaces of the comparative cutting tools 1 to 9 are processed using a FIB on the surface of the hard coating layer to produce a surface parallel to the surface of the tool base, and the EBSD is applied to the processing surface. Analysis was performed, and the average width and area ratio of a region where particles having similar crystal orientations gathered were obtained using the method described above. The measurement area is about 15 μm × 15 μm in view of the average width of the area where particles with close crystal orientation gathered, and the average value measured for each field of view for each tool is about 3 μm. Was measured.
硬質被覆層について、Ｃｕ管球を用いたＸ線回折により、（２００）面の回折ピーク強度Ｉ（２００）と、（１１１）面の回折ピーク強度Ｉ（１１１）を測定し、Ｉ（２００）／Ｉ（１１１）から回折ピーク強度比を算出した。
表４、表５に、上記で求めた各種の値を示す。
For the hard coating layer, the diffraction peak intensity I (200) on the (200) plane and the diffraction peak intensity I (111) on the (111) plane are measured by X-ray diffraction using a Cu tube, and I (200) The diffraction peak intensity ratio was calculated from / I (111).
Tables 4 and 5 show the various values obtained above.
次いで、本発明工具１〜９および比較例工具１〜９について、以下の条件で切削試験を実施した。
切削条件Ａ：
被削材：ＪＩＳ・ＳＣＭ４１５の浸炭焼入れ材（ＨＲＣ６０）の丸棒、
切削速度：２７５ ｍ／ｍｉｎ．、
切り込み：０．１５ ｍｍ、
送り：０．１ ｍｍ、
の乾式連続切削条件で切削試験を行い、切削長２７５０ｍまで切削し、逃げ面摩耗幅を測定した。
切削条件Ｂ：
被削材：ＪＩＳ・ＳＣｒ４２０の浸炭焼入れ材（ＨＲＣ６０）の丸棒、
切削速度：１９０ ｍ／ｍｉｎ．、
切り込み：０．２０ ｍｍ、
送り：０．２０ ｍｍ、
の乾式連続切削条件で切削試験を行い、切削長２８５０ｍまで切削し、逃げ面摩耗幅を測定した。
表６に、その結果を示す。
Next, cutting tests were performed on the present invention tools 1 to 9 and the comparative tools 1 to 9 under the following conditions.
Cutting condition A:
Work material: Round bar of carburizing and quenching material (HRC60) of JIS / SCM415,
Cutting speed: 275 m / min. ,
Cutting depth: 0.15 mm,
Feed: 0.1 mm,
A cutting test was performed under the dry continuous cutting conditions, cutting to a cutting length of 2750 m, and the flank wear width was measured.
Cutting condition B:
Work material: JIS / SCr420 carburized quenching material (HRC60) round bar,
Cutting speed: 190 m / min. ,
Cutting depth: 0.20 mm,
Feed: 0.20 mm,
A cutting test was performed under the dry continuous cutting conditions, and the cutting length was cut to 2850 m, and the flank wear width was measured.
Table 6 shows the results.
表６の結果によれば、本発明工具は、逃げ面摩耗幅の平均は切削条件Ａで約０．１２ｍｍ、また、切削条件Ｂで約０．０８ｍｍあるのに対して、比較例工具は逃げ面摩耗が進行し、あるいは、短時間でチッピング、欠損、剥離等による寿命となるものも生じた。
この結果から、切れ刃に高負荷が作用する高速切削加工において、本発明工具は、比較例工具に比して、耐摩耗性にすぐれていることが分かる。
According to the results of Table 6, the tool according to the present invention has an average flank wear width of about 0.12 mm under the cutting condition A and about 0.08 mm under the cutting condition B, while the comparative example tool has the flank. Surface wear progressed, or there was a product with a lifetime due to chipping, chipping, peeling, etc. in a short time.
From this result, it can be seen that the tool of the present invention is superior in wear resistance as compared with the comparative tool in high-speed cutting in which a high load acts on the cutting edge.
本発明の表面被覆切削工具は、切刃部に大きな負荷がかかる鋼や鋳鉄の高速切削加工においても、すぐれた耐摩耗性を発揮し、長期に亘ってすぐれた切削性能を示すものであるから、切削加工装置の高性能化、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。
The surface-coated cutting tool of the present invention exhibits excellent wear resistance and exhibits excellent cutting performance over a long period of time even in high-speed cutting of steel or cast iron in which a large load is applied to the cutting edge portion. Therefore, it is possible to satisfactorily meet the demands for higher performance of the cutting device, labor saving and energy saving of the cutting work, and cost reduction.
Claims (3)
（ａ）前記硬質被覆層は、
組成式：（Ｔｉ１−ｘＡｌｘ）Ｎで表した場合、０．４≦ｘ≦０．７（但し、ｘは原子比）を満足するＴｉとＡｌの複合窒化物層であり、
（ｂ）前記硬質被覆層の結晶組織は、工具基体との界面側では結晶粒の平均幅が０．０１〜０．０５μｍの微粒組織、また、硬質被覆層表面側では結晶粒の平均幅が０．０５〜１．０μｍの柱状組織であって、該柱状組織の層厚方向の平均厚さは、硬質被覆層の層厚より薄く、かつ、０．３〜１．５μｍの平均厚さで形成されており、
（ｃ）前記硬質被覆層の表面には、複数の結晶粒の集合体からなり、該集合体の平均幅が０．５〜２．０μｍである結晶方位の近い粒子が集まった領域が形成され、該結晶方位の近い粒子が集まった領域が硬質被覆層の表面に占める面積割合は３０〜８０面積％であり、
（ｄ）前記結晶方位の近い粒子が集まった領域は、該領域内の各結晶粒の結晶方位の差が２度以上１０度以下である領域であって、しかも、工具基体表面の法線方向に対する該領域内の各結晶粒の結晶方位の傾斜角度差が最も小さい結晶方位＜１００＞のベクトルを平均した方位と基体表面の法線方向のなす角度が１０度以下であることを特徴とする表面被覆切削工具。 In a surface-coated cutting tool in which a hard coating layer having an average layer thickness of 1.0 to 4.0 μm is vapor-deposited on the surface of a tool substrate made of a cubic boron nitride sintered body,
(A) The hard coating layer is
When represented by a composition formula: (Ti 1-x Al x ) N, it is a composite nitride layer of Ti and Al that satisfies 0.4 ≦ x ≦ 0.7 (where x is an atomic ratio),
(B) The crystal structure of the hard coating layer has a fine grain structure in which the average width of crystal grains is 0.01 to 0.05 μm on the interface side with the tool base, and the average width of crystal grains on the hard coating layer surface side. It is a columnar structure of 0.05 to 1.0 μm, and the average thickness in the layer thickness direction of the columnar structure is smaller than the layer thickness of the hard coating layer and is an average thickness of 0.3 to 1.5 μm. Formed,
(C) On the surface of the hard coating layer, there is formed a region composed of aggregates of a plurality of crystal grains, in which grains having close crystal orientation and an average width of the aggregates of 0.5 to 2.0 μm are collected. In addition, the area ratio of the area where the grains having similar crystal orientations gather to the surface of the hard coating layer is 30 to 80 area%,
(D) The region where grains having similar crystal orientations gather is a region in which the difference in crystal orientation of each crystal grain in the region is 2 degrees or more and 10 degrees or less, and the normal direction of the tool base surface The angle between the orientation of the average of the crystal orientation <100> vectors and the normal direction of the substrate surface is 10 degrees or less. Surface coated cutting tool.
The tool base according to claim 1 or 2, wherein at least a cutting edge used for cutting is made of a cubic boron nitride sintered body, and the cubic boron nitride sintered body is made of cubic boron nitride particles, Ti nitride, carbide. , Carbon nitride, boride, Al nitride, and at least one kind of particles selected from the group consisting of oxides and a binder phase containing inevitable impurities, and the cubic boron nitride particles have an average particle size The surface-coated cutting tool according to claim 1 or 2, wherein a content ratio of 2.0 to 4.0 µm and a total content of the cubic boron nitride sintered body is 50 to 80% by volume.
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|---|---|---|---|---|
| JP4960149B2 (en) * | 2007-05-29 | 2012-06-27 | 京セラ株式会社 | Surface coated cutting tool |
| JP5207109B2 (en) * | 2007-08-31 | 2013-06-12 | 三菱マテリアル株式会社 | Surface-coated cutting tool with excellent fracture resistance due to hard coating layer |
| JP2011152602A (en) * | 2010-01-27 | 2011-08-11 | Mitsubishi Materials Corp | Surface-coated cutting tool provided with hard coated layer demonstrating superior chipping resistance |
| JP5594575B2 (en) * | 2010-04-20 | 2014-09-24 | 三菱マテリアル株式会社 | Surface coated cutting tool with excellent wear resistance due to hard coating layer |
| JP5124793B2 (en) * | 2010-07-16 | 2013-01-23 | 住友電工ハードメタル株式会社 | Surface coated cutting tool |
| CN103249869B (en) * | 2010-11-23 | 2016-05-18 | 山高刀具公司 | Coated cutting tool insert |
| JP6459391B2 (en) * | 2013-10-31 | 2019-01-30 | 三菱マテリアル株式会社 | Surface coated cutting tool with excellent chipping resistance |
| EP3000913B1 (en) * | 2014-09-26 | 2020-07-29 | Walter Ag | Coated cutting tool insert with MT-CVD TiCN on TiAI(C,N) |
-
2015
- 2015-06-26 JP JP2015129283A patent/JP6493800B2/en not_active Expired - Fee Related
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| JP2017013145A (en) | 2017-01-19 |
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