JP2019119000A - Surface-coated cutting tool having hard coating layer exerting excellent wear resistance and peeling resistance - Google Patents
Surface-coated cutting tool having hard coating layer exerting excellent wear resistance and peeling resistance Download PDFInfo
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本発明は、難削材である合金工具鋼やＴｉ合金などの高速切削加工に用いた場合においても、硬質被覆層がすぐれた耐摩耗性および耐剥離性を備えることにより、長期の使用に亘ってすぐれた切削性能を有する表面被覆切削工具（以下、「被覆工具」ともいう。）に関するものである。 The present invention is applicable to long-term use even when used for high-speed cutting of hard-to-cut materials such as alloy tool steel and Ti alloy by providing the hard coating with excellent abrasion resistance and peeling resistance. The present invention relates to a surface-coated cutting tool having excellent cutting performance (hereinafter also referred to as "coated tool").
従来、被覆工具において、摩耗特性の向上を図るとの観点から、例えば、特許文献１においては、炭化タングステン基の超硬合金基体表面に下部層として化学蒸着により形成された、特に、チタン等の元素の２ホウ化物（ＴｉＢ２）層を有し、上部層として化学蒸着により形成されたα酸化アルミニウム層を有してなる硬質被覆層が形成された被覆工具を用いることが提案されているが、成膜時の高温、高真空の条件下において超硬合金基体中の接合層およびＴｉＢ２層中の硼素の拡散により、硼素含有脆化層が生じ、そのため、耐摩耗性成分素材の寿命を著しく低下させるという問題を生じていた。
これに対し、例えば、特許文献２では、合金工具鋼や軸受鋼の焼き入れ材など高硬度鋼の高速切削加工に用いた際においても、すぐれた耐摩耗性を発揮する被覆工具として、炭化タングステン基の超硬合金基体表面に、下部層として組成式：（Ａｌ１−ＸＴｉＸ）Ｎ（ただし、原子比で、Ｘは０．２５〜０．６０を示す）を満足するＡｌとＴｉの複合窒化物層からなる下部層を有し、前記下部層の上には、ＺｒＢＮ（硼窒化ジルコニウム）層からなる密着接合層を有し、さらに、前記密着接合層の上には、ＺｒＢ２（硼化ジルコニウム）層からなる上部層を有する硬質被覆層を形成した被覆工具を用いることが提案されている。
また、特許文献３では、炭化タングステン基の超硬合金基体の最表面に、少なくともＺｒ硼化物（ＺｒＢ２）層からなる被覆層を形成してなる被覆工具において、前記Ｚｒ硼化物（ＺｒＢ２）層を複数の平均粒径を有する結晶粒組織の複合組織として構成し、具体的には、５〜３０ｎｍの平均粒径を有する一次結晶粒の集合体からなる平均粒径５０〜１００ｎｍの二次結晶粒と、該二次結晶粒の集合体からなる平均粒径２００〜１０００ｎｍの三次結晶粒とからなり、高い膜強度（例えば、荷重２００ｍｇにて測定した場合のナノインデンテーション硬さが３６００ｋｇｆ／ｍｍ２以上（＝３５．３ＧＰａ以上））を有する複合組織とすることにより、特許文献２に記載された切削条件よりもさらに厳しい切削条件、すなわち、各種のＴｉ系合金や高Ｓｉ含有Ａｌ−Ｓｉ系合金などの硬質難削材に対する切削加工を高速切削条件にて用いた場合においても、すぐれた耐摩耗性および耐剥離性を発揮する被覆工具が提案されている。
Conventionally, in a coated tool, from the viewpoint of improving wear characteristics, for example, in Patent Document 1, titanium, etc. formed as a lower layer on the surface of a tungsten carbide-based cemented carbide base as a lower layer, for example It has been proposed to use a coated tool with an elemental diboride (TiB 2 ) layer and a hard overlayer comprising an alpha aluminum oxide layer formed by chemical vapor deposition as the upper layer. At the time of film formation, diffusion of boron in the bonding layer and TiB 2 layer in the cemented carbide substrate under the conditions of high temperature and high vacuum generates a boron-containing embrittled layer, and hence the life of the wear resistant component material There was a problem that it was significantly reduced.
On the other hand, for example, in Patent Document 2, tungsten carbide is used as a coated tool which exhibits excellent wear resistance even when used for high-speed cutting of high hardness steel such as alloy tool steel and hardened steel of bearing steel. Base cemented carbide substrate surface, Al and Ti satisfying the compositional formula: (Al 1-x Ti x ) N (where, in atomic ratio, X represents 0.25 to 0.60) as the lower layer It has a lower layer made of a composite nitride layer, and has an adhesion bonding layer made of a ZrBN (boron zirconium nitride) layer on the lower layer, and further, ZrB 2 ( It has been proposed to use coated tools which have a hard coated layer with a top layer consisting of a zirconium (zirconium) layer.
Further, in Patent Document 3, in the coated tool formed by forming a covering layer comprising at least a Zr boride (ZrB 2 ) layer on the outermost surface of a tungsten carbide based cemented carbide substrate, the Zr boride (ZrB 2 ) The layer is formed as a composite structure of grain structures having a plurality of average grain sizes, and specifically, a secondary of 50 to 100 nm average grain size comprising an aggregate of primary crystal grains having an average grain size of 5 to 30 nm A high film strength (for example, a nanoindentation hardness of 3600 kgf when measured at a load of 200 mg) consisting of crystal grains and tertiary crystal grains with an average particle size of 200 to 1000 nm consisting of aggregates of the secondary crystal grains mm 2 or more (= more 35.3GPa)) by a composite structure having a more severe cutting conditions than has been cutting conditions described in Patent Document 2, i.e., various T A coated tool has been proposed that exhibits excellent wear resistance and peel resistance even when cutting hard hard materials such as Al-Si alloys and high Si-containing alloys under high-speed cutting conditions. There is.
ところで、近年の切削加工における省力化および省エネ化への要求は強く、これに伴い、被覆工具は一段と過酷な条件下にて使用されるようになってきており、前記硬質難削材に対して、さらなる高速切削条件においても、すぐれた耐摩耗性および耐剥離性を有することが求められている。
しかしながら、前記特許文献２や特許文献３にて提案されている、Ｚｒ硼化物（ＺｒＢ２）層を有する被覆層からなる被覆工具を用いて、前記難削材に対し、さらなる高速切削条件にて切削加工を行った場合においては、これらの被覆層が塑性変形に耐えられず、被覆層から粒子が脱落するため、耐摩耗性に劣り、その結果、異常摩耗が発生し、膜剥離を起こすため、早期に寿命に至るという問題を有していた。
By the way, there is a strong demand for labor saving and energy saving in cutting processing in recent years, and along with this, coated tools have come to be used under more severe conditions, and for the above hard hard-to-cut materials It is required to have excellent wear resistance and peeling resistance even at higher speed cutting conditions.
However, with the use of a coated tool comprising a coating layer having a Zr boride (ZrB 2 ) layer, which has been proposed in Patent Document 2 or Patent Document 3, the above-mentioned difficult-to-cut materials are subjected to further high-speed cutting conditions In the case of cutting, these coating layers can not withstand plastic deformation and the particles fall off from the coating layer, resulting in inferior wear resistance, resulting in abnormal wear and film peeling. , Had the problem of reaching the life early.
そこで、本発明者らは、前述の観点から、前記難削材の高速切削加工に用いた場合であっても、長期の使用にわたり、すぐれた耐摩耗性と耐剥離性を兼ね備え、工具寿命の向上をもたらす、被覆工具について、鋭意研究を行った結果、以下の知見を得た。
すなわち、本発明者らは、限定された条件にて、Ｚｒ硼化物（ＺｒＢ２）層を成膜することにより、縦長柱状結晶組織を備えた高硬度のＺｒ硼化物（ＺｒＢ２）層を得ることができ、かかるＺｒ硼化物（ＺｒＢ２）層では、基体と並行な方向の粒界が少なくなるため、結晶粒の脱落が生じにくい特性を有することを見出し、さらに、Ｚｒ硼化物（ＺｒＢ２）層を構成する結晶粒の配向性に着目し、Ｘ線回折により、各結晶格子面からの回折ピーク強度を測定したところ、（１００）面に最大ピーク強度を有し、また、配向性指数Ｔｃ（ｈｋｌ）を求めたところ、Ｔｃ（１００）が、２．０以上である場合には、耐摩耗性および耐剥離性にすぐれた硬質被覆層が得られることを見出したものである。
そして、かかるＺｒ硼化物（ＺｒＢ２）層を硬質被覆層として有する被覆切削工具は、耐摩耗性と耐剥離性を兼ね備えているため、合金工具鋼やＴｉ合金のような難削材の高速切削加工に用いた場合に、すぐれた切削特性を有し、さらなる工具寿命の向上をもたらすものであることを見出したものである。
Therefore, from the viewpoint described above, the present inventors have excellent wear resistance and peeling resistance over long-term use even when used for high-speed cutting of the above-mentioned difficult-to-cut materials, and the tool life is long The following findings were obtained as a result of intensive studies on coated tools that bring about improvement.
That is, the present inventors have at limited condition, by depositing Zr boride (ZrB 2) layer, obtaining a high hardness of Zr boride having a vertically long columnar crystal structure (ZrB 2) layer it can, in such Zr boride (ZrB 2) layer, since the substrate and the parallel direction of the grain boundary is reduced, found to have crystal grain falling hardly occurs properties, further, Zr boride (ZrB 2 When the diffraction peak intensity from each crystal lattice plane was measured by X-ray diffraction, paying attention to the orientation of the crystal grains constituting the layer, it has the maximum peak intensity on the (100) plane, and the orientation index When Tc (hkl) was determined, it was found that when Tc (100) is 2.0 or more, a hard coating layer excellent in abrasion resistance and peeling resistance can be obtained.
And, since the coated cutting tool having such a Zr boride (ZrB 2 ) layer as a hard coating layer has both wear resistance and peeling resistance, high-speed cutting of difficult-to-cut materials such as alloy tool steel and Ti alloy It has been found that when used for machining, it has excellent cutting properties and leads to further improvement in tool life.
本発明は、前記知見に基づいてなされたものであって、
「（１） 炭化タングステン基超硬合金または炭窒化チタン基サーメットからなる工具基体の表面に、硬質被覆層が形成されてなる表面被覆切削工具において、
（ａ）前記硬質被覆層は、前記工具基体の表面側から下部層および上部層を有してなり、
（ｂ）前記下部層は、Ｔｉの炭化物層、窒化物層、炭窒化物層、炭酸化物層および炭窒酸化物層のうちの１層または２層以上からなり、かつ、０．１〜３．０μｍの合計平均層厚を有するＴｉ化合物層を有し、
（ｃ）前記上部層は、１．０〜１５．０μｍの平均層厚を有するＺｒ硼化物層を有し、
（ｄ）前記上部層の縦断面において、アスペクト比が３以上である縦長柱状結晶粒が、面積割合で８０％以上である縦長柱状結晶組織を有し、
（ｅ）前記上部層は、（１００）面にＸ線回折による最大ピークが現れるＺｒ硼化物層であり、以下の式（Ａ）で表されるＺｒ硼化物層の配向性指数Ｔｃ（ｈｋｌ）がＴｃ（１００）≧２．０を満たすことを特徴とする表面被覆切削工具。
式（Ａ）
式（Ａ）において、Ｉ（ｈｋｌ）は（ｈｋｌ）面のＸ線回折強度を示し、Ｉ０（ｈｋｌ）はＩＣＤＤカード００−０３４−０４２３によるＺｒＢ２の（ｈｋｌ）面のＸ線回折標準強度を示す。
また、（ｈｋｌ）は（００１）、（１００）、（１０１）、（１１０）、（１０２）、（１１１）、（２０１）、（１１２）の８面であり、式（Ａ）の中括弧内は各面におけるＸ線回折強度のＸ線回折標準強度に対する比の平均値を示す。
（２）前記上部層の前記Ｚｒ硼化物層におけるナノインデンテーション押し込み硬さが、押し込み荷重２００ｍｇｆのとき、４５．０ＧＰａ以上であることを特徴とする（１）に記載の表面被覆切削工具。
（３）（１）または（２）に記載の表面被覆切削工具において、前記上部層であるＺｒ硼化物層の上層として、０．３〜２．０μｍの平均層厚を有するα型もしくはκ型のＡｌ２Ｏ３層を有す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。」
を特徴とするものである。
The present invention was made based on the above findings, and
“(1) A surface-coated cutting tool in which a hard coating layer is formed on the surface of a tool base consisting of a tungsten carbide-based cemented carbide or titanium carbonitride-based cermet
(A) The hard coating layer has a lower layer and an upper layer from the surface side of the tool substrate,
(B) The lower layer is composed of one or more layers of a carbide layer, a nitride layer, a carbonitride layer, a carbon oxide layer and a carbon oxynitride layer of Ti, and 0.1 to 3 With a Ti compound layer having a total average layer thickness of 0 μm,
(C) the upper layer comprises a Zr boride layer having an average layer thickness of 1.0 to 15.0 μm;
(D) In the longitudinal section of the upper layer, longitudinally elongated columnar crystal grains having an aspect ratio of 3 or more have a longitudinally elongated columnar crystal structure having an area ratio of 80% or more,
(E) The upper layer is a Zr boride layer in which the maximum peak appears in the (100) plane by X-ray diffraction, and the orientation index Tc (hkl) of the Zr boride layer represented by the following formula (A) A surface-coated cutting tool characterized by satisfying Tc (100) ≧ 2.0.
Formula (A)
In the formula (A), I (hkl) represents the X-ray diffraction intensity of the (hkl) plane, and I 0 (hkl) represents the standard X-ray diffraction intensity of the (hkl) plane of ZrB 2 by ICDD card 00-034-0423. Indicates
Further, (hkl) is the eight faces of (001), (100), (101), (110), (102), (111), (201), (112), and the braces of the formula (A) The inside shows the average value of the ratio of the X-ray diffraction intensity to the X-ray diffraction standard intensity in each surface.
(2) The surface-coated cutting tool according to (1), wherein the nanoindentation indentation hardness in the Zr boride layer of the upper layer is 45.0 GPa or more when the indentation load is 200 mgf.
(3) In the surface-coated cutting tool according to (1) or (2), an α-type or κ-type having an average layer thickness of 0.3 to 2.0 μm as an upper layer of the Zr boride layer which is the upper layer. The surface-coated cutting tool according to (1) or (2), having an Al 2 O 3 layer of "
It is characterized by
つぎに、本発明の被覆工具について、詳細に説明する。 Below, the coated tool of this invention is demonstrated in detail.
硬質被覆層；
本発明に係る硬質被覆層は、工具基体側より、１層または２層以上のＴｉ化合物層からなる下部層と、Ｚｒ硼化物層である上部層とを有し、さらに必要に応じて、上部層の上層として、α型もしくはκ型の酸化アルミニウム層（Ａｌ２Ｏ３層）を有するものである。
硬質被覆層の平均層厚は、１．１μｍ未満では、長期にわたり耐摩耗性を発揮することができず、一方、２０．０μｍを超えると全体被膜層として欠損やチッピングが発生し易くなるため、１．１〜２０．０μｍとすることが望ましい。
硬質被覆層の平均層厚は、例えば、工具基体に対し垂直方向断面において、ＳＥＭ（走査型電子顕微鏡）またはＴＥＭ（透過型電子顕微鏡）を用いて測定することができる。
Hard coating layer;
The hard coating layer according to the present invention comprises, from the tool substrate side, a lower layer consisting of one or two or more Ti compound layers and an upper layer which is a Zr boride layer, and, if necessary, an upper layer. As an upper layer of the layer, an α-type or κ-type aluminum oxide layer (Al 2 O 3 layer) is provided.
If the average layer thickness of the hard coating layer is less than 1.1 μm, the wear resistance can not be exhibited over a long period of time, while if it exceeds 20.0 μm, defects and chipping easily occur as the entire coating layer. It is desirable to set it as 1.1-20.0 micrometers.
The average layer thickness of the hard covering layer can be measured, for example, using a SEM (scanning electron microscope) or a TEM (transmission electron microscope) in a cross section perpendicular to the tool substrate.
下部層；
工具基体上に形成する下部層は、Ｔｉの炭化物層、窒化物層、炭窒化物層、炭酸化物層および炭窒酸化物層のうちの１層または２層以上のＴｉ化合物層からなり、工具基体と上部層である、Ｚｒ硼化物層との密着性を高めることができるため、欠損、剥離等の異常損傷の発生を抑制することができる。
Ｔｉ化合物層からなる下部層の合計平均層厚は、０．１μｍ未満では、下部層の効果が十分発揮されず、一方、３．０μｍを超えると結晶粒が粗大化し易くなり、チッピングを発生しやすくなるため、０．１μｍ〜３．０μｍとすることが望ましい。
Lower layer;
The lower layer formed on the tool substrate comprises one or more Ti compound layers of a carbide layer, a nitride layer, a carbonitride layer, a carbon oxide layer and a carbon oxynitride layer of Ti, Since the adhesion between the substrate and the Zr boride layer, which is the upper layer, can be enhanced, the occurrence of abnormal damage such as defects and peeling can be suppressed.
If the total average layer thickness of the lower layer composed of the Ti compound layer is less than 0.1 μm, the effect of the lower layer is not sufficiently exhibited, while if it exceeds 3.0 μm, the crystal grains are easily coarsened and chipping occurs. It is desirable to set it as 0.1 micrometer-3.0 micrometers in order to become easy.
上部層（Ｚｒ硼化物層）；
（１）平均層厚
下部層上に形成する上部層（Ｚｒ硼化物層）は、高硬度であり、すぐれた耐摩耗性を有し、特に、平均層厚が１．０〜１５．０μｍであるときに硬度および耐摩耗性の観点からすぐれた効果を発揮する。
上部層の平均層厚は、走査型電子顕微鏡（倍率５０００倍）を用いて、工具基体に垂直な方向の断面の観察視野内の５点の層厚を測り、これらを平均して平均層厚を求めることができる。
（２）縦長柱状結晶組織
前記のとおり、本発明に係る上部層を構成するＺｒ硼化物（ＺｒＢ２）層は、縦長柱状結晶組織を有することにより、被覆層からの粒子の脱落が抑制され、耐摩耗性および耐剥離性にすぐれた特性を発揮する。
なお、ここでいう縦長柱状結晶組織とは、Ｚｒ硼化物（ＺｒＢ２）層の縦断面を観察した際に、結晶粒の長軸が縦方向に配向し、結晶粒の長軸径に対する短軸径の比として定義されるアスペクト比が３以上であり、縦長結晶粒の組織中に占める面積率が８０％以上である組織を指すものとする。
アスペクト比が３未満のものでは、形状が等軸結晶に近づくために脱落を招くおそれがあり、また、アスペクト比が３以上であっても、それら結晶粒が占める面積割合が８０％未満では、十分な効果を発揮することができないため、縦長柱状結晶粒のアスペクト比を３以上と規定し、その縦長柱状結晶粒が占める面積割合を８０％以上と規定することにより、耐摩耗性、および、耐剥離性にすぐれたものとした。
アスペクト比および縦長結晶粒の面積割合の測定は、例えば、走査型電子顕微鏡（ＳＥＭ）を用い、倍率５０００にて断面観察により得られた縦断面画像について、電子線後方散乱回折法（ＥＢＳＤ）により、個々の結晶粒につき、長軸径、短軸径、および、縦断面の面積を測定し、長軸径および短軸径よりアスペクト比を求め、次いで、アスペクト比が３以上である結晶粒の縦断面における面積の総和に対する測定対象となった縦断面の面積の比率を面積割合として求めた。
Upper layer (Zr boride layer);
(1) Average layer thickness
The upper layer (Zr boride layer) formed on the lower layer has high hardness and excellent abrasion resistance, and in particular, hardness and resistance when the average layer thickness is 1.0 to 15.0 μm. It exerts excellent effects from the viewpoint of wear resistance.
The average layer thickness of the upper layer is obtained by measuring the layer thickness of five points in the observation field of the cross section in the direction perpendicular to the tool substrate using a scanning electron microscope (magnification 5000) and averaging these to obtain an average layer thickness. You can ask for
(2) Longitudinal Columnar Crystal Structure As described above, the Zr boride (ZrB 2 ) layer constituting the upper layer according to the present invention has the longitudinally long columnar crystal structure, whereby the detachment of particles from the coating layer is suppressed. It exhibits excellent wear resistance and peeling resistance.
In addition, when the longitudinal cross-section of the Zr boride (ZrB 2 ) layer is observed, the major axis of the crystal grain is vertically oriented and the minor axis with respect to the major axis diameter of the crystal grain is referred to as the longitudinally elongated columnar crystal structure here. The aspect ratio defined as the ratio of the diameter is 3 or more, and the area ratio of the longitudinally elongated crystal grains in the structure is 80% or more.
If the aspect ratio is less than 3, the shape may come close to an equiaxed crystal, which may cause detachment, and even if the aspect ratio is 3 or more, the area ratio occupied by those crystal grains is less than 80%, Since sufficient effects can not be exhibited, the aspect ratio of the longitudinally elongated columnar crystal grains is defined to be 3 or more, and the area ratio occupied by the longitudinally elongated columnar crystal grains is defined to be 80% or more. It was excellent in peeling resistance.
The measurement of the aspect ratio and the area ratio of longitudinally elongated crystal grains is carried out, for example, by electron backscattering diffraction (EBSD) on a longitudinal sectional image obtained by cross-sectional observation at a magnification of 5000 using a scanning electron microscope (SEM) For each crystal grain, the major axis diameter, minor axis diameter, and area of the longitudinal cross section are measured, and the aspect ratio is determined from the major axis diameter and minor axis diameter, and then the aspect ratio is 3 or more. The ratio of the area of the longitudinal section to be measured to the sum of the areas in the longitudinal section was determined as the area ratio.
（３）最大ピーク強度、配向性指数
前記したとおり、本発明は、上部層（Ｚｒ硼化物層）において、Ｘ線回折を行った際に（１００）面において最大ピークを有するものであり、その（１００）面における配向性指数であるＴｃ（１００）が、２．０以上であるときに、すぐれた耐摩耗性および耐チッピング性を発揮することを見出したものである。
図１に、本発明被覆工具のＺｒ硼化物層について、Ｘ線回折により測定した各結晶格子面からの回折ピーク強度のチャートの一例を示す。
図１からも明らかなように、本発明被覆工具のＺｒ硼化物層は、（１００）面についての回折ピーク強度が、他の結晶格子面のピーク強度に比して最大であることがわかる。
なお、Ｘ線回折は、Ｘ線回折装置としてスペクトリス社ＰＡＮａｌｙｔｉｃａｌ Ｅｍｐｙｒｅａｎを用いて、ＣｕＫα線による２θ‐θ法で測定し、測定条件として、測定範囲（２θ）：１５〜１３０度、Ｘ線出力：４５ｋＶ、４０ｍＡ、発散スリット：０．５度、スキャンステップ：０．０１３度、１ステップ辺り測定時間：０．４８ｓｅｃ／ｓｔｅｐという条件で測定した。
さらに、Ｚｒ硼化物層について、配向性指数Ｔｃ（ｈｋｌ）を求めたところ、Ｔｃ（１００）の値が、２．０以上であり、（１００）面に高配向を有するものであった。
なお、配向性指数Ｔｃ（ｈｋｌ）は、以下の式にて定義されるものである。
式（Ａ）
上記式（Ａ）において、Ｉ（ｈｋｌ）は測定された（ｈｋｌ）面のＸ線回折強度を示し、Ｉ０（ｈｋｌ）はＩＣＤＤカード００−０３４−０４２３によるＺｒＢ２の（ｈｋｌ）面のＸ線回折標準強度を示す。
また、（ｈｋｌ）は（００１）、（１００）、（１０１）、（１１０）、（１０２）、（１１１）、（２０１）、（１１２）の８面であり、式（Ａ）の中括弧内は各面におけるＸ線回折強度のＸ線回折標準強度に対する比の平均値を示す。
本発明被覆工具においては、少なくとも前記Ｚｒ硼化物層は、（１００）面にＸ線回折による最大ピーク強度を有し、かつ、配向性指数Ｔｃ（１００）≧２．０という高い配向性を有することにより、切削加工時にＺｒ硼化物層に大きなせん断力が働いた場合においても、耐塑性変形性を有するため、Ｚｒ硼化物層からの結晶粒の脱落の発生や、これに伴うチッピング、欠損、剥離の発生、さらには、偏摩耗等の異常損傷の発生を抑制することができるため、耐摩耗性の向上が図られる。
(3) Maximum peak intensity, orientation index As described above, the present invention has a maximum peak in the (100) plane when X-ray diffraction is performed in the upper layer (Zr boride layer), It has been found that when the orientation index Tc (100) on the (100) plane is 2.0 or more, excellent abrasion resistance and chipping resistance are exhibited.
FIG. 1 shows an example of a chart of diffraction peak intensity from each crystal lattice plane measured by X-ray diffraction for the Zr boride layer of the coated tool of the present invention.
As apparent from FIG. 1, the Zr boride layer of the coated tool of the present invention is found to have the maximum diffraction peak intensity for the (100) plane relative to the peak intensities of other crystal lattice planes.
In addition, X-ray diffraction is measured by 2θ-θ method using CuKα ray, using PANalytical Empyrean as an X-ray diffractometer, measurement range (2θ): 15 to 130 degrees, X-ray output: The measurement was performed under the conditions of 45 kV, 40 mA, a divergence slit: 0.5 degrees, a scan step: 0.013 degrees, and a measurement time per one step: 0.48 sec / step.
Furthermore, when the orientation index Tc (hkl) was determined for the Zr boride layer, the value of Tc (100) was 2.0 or more, and the (100) plane had high orientation.
The orientation index Tc (hkl) is defined by the following equation.
Formula (A)
In the above-mentioned formula (A), I (hkl) shows the X-ray diffraction intensity of the measured (hkl) plane, and I 0 (hkl) is the X of (hkl) plane of ZrB 2 by ICDD card 00-034-0423. The line diffraction standard intensity is shown.
Further, (hkl) is the eight faces of (001), (100), (101), (110), (102), (111), (201), (112), and the braces of the formula (A) The inside shows the average value of the ratio of the X-ray diffraction intensity to the X-ray diffraction standard intensity in each surface.
In the coated tool of the present invention, at least the Zr boride layer has the maximum peak intensity by X-ray diffraction in the (100) plane, and has high orientation such as the orientation index Tc (100) ≧ 2.0. By this, even when a large shear force acts on the Zr boride layer during cutting, it has plastic deformation resistance, and therefore, the generation of the dropout of crystal grains from the Zr boride layer, the chipping, the defects, and the like associated therewith. Since the occurrence of peeling and the occurrence of abnormal damage such as uneven wear can be suppressed, the wear resistance can be improved.
（４）硬度
上記のとおり、上部層（Ｚｒ硼化物層）は、高硬度であり、しかも、すぐれた耐摩耗性を有するものであるが、さらに、ナノインデンテーション押し込み硬さ（押し込み荷重２００ｍｇｆ）が４５．０ＧＰａ以上の場合には、よりすぐれた効果を発揮することができる。
ナノインデンテーション硬さについては、ナノインデンテーション試験法（ＩＳＯ １４５７７）に基づき、前記Ｚｒ硼化物層の表面を研磨し、ダイヤモンド製のBerkovich圧子を用いて、押し込み荷重２００ｍｇｆで測定を行なった。
(4) Hardness As described above, the upper layer (Zr boride layer) is high in hardness and has excellent wear resistance, but furthermore, nano indentation indentation hardness (indentation load: 200 mgf) In the case of 45.0 GPa or more, better effects can be exhibited.
Regarding the nano-indentation hardness, the surface of the Zr boride layer was polished based on the nano-indentation test method (ISO 14577), and measurement was performed with an indentation load of 200 mgf using a Berkovich indenter made of diamond.
上部層（Ｚｒ硼化物（ＺｒＢ２）層）の成膜方法：
本発明に係る、縦長柱状結晶組織、（１００）面における最大ピーク、および、（１００）面に対する高い配向性指数を有するＺｒ硼化物層は、例えば、工具基体に前記下部層を成膜後、以下の化学蒸着法を用い、以下の各工程に示す条件にて順次処理を行うことにより、形成することができる。
すなわち、Ｚｒ硼化物（ＺｒＢ２）層の成膜方法は、第１工程であるＺｒＢ２初期核形成工程においては、第２工程であるＺｒＢ２結晶成長工程に対し、反応雰囲気温度を比較的低温とし、また、原料ガス濃度比を低くすることにより、初期核として、（１００）配向性が高く、縦長柱状組織が形成されやすい反応雰囲気とし、第２工程である、ＺｒＢ２結晶成長工程においては、反応雰囲気温度を上げ、あわせて、原料ガス濃度比を高め、縦長柱状組織が成長しやすい反応雰囲気とすることにより、（１００）配向性が高く、所望の高アスペクト比を有する、縦長柱状組織を得ることができる。
［成膜条件］
１）第１工程（ＺｒＢ２初期核形成工程）
処理方法：ＣＶＤ法を用いた成膜
反応ガス組成（容量％）：
ガス群Ａ：ＢＣｌ３：０．２５〜１．００％、ＺｒＣｌ４：０．１０〜１．００％、
Ｈ２：残部
反応雰囲気温度：９００℃〜９５０℃
反応雰囲気圧力：３ｋＰａ〜１０ｋＰａ
反応時間 ：２０〜９０分
２）第２工程（ＺｒＢ２結晶成長工程）
処理方法：ＣＶＤ法を用いた成膜
反応ガス組成（容量％）：
ガス群Ｂ：ＢＣｌ３：０．２５〜３．００％、ＺｒＣｌ４：０．２０〜２．００％、
Ｈ２：残部
反応雰囲気温度：９００℃〜１０５０℃
反応雰囲気圧力：３ｋＰａ〜１０ｋＰａ
反応時間 ：目的膜厚に到達するまで
Method of forming upper layer (Zr boride (ZrB 2 ) layer):
The Zr boride layer according to the present invention having a vertically elongated columnar crystal structure, a maximum peak in the (100) plane, and a high orientation index with respect to the (100) plane is, for example, after depositing the lower layer on the tool substrate It can form by processing sequentially using the following chemical vapor deposition methods on the conditions shown to the following each process.
That is, in the film formation method of the Zr boride (ZrB 2 ) layer, the reaction atmosphere temperature is relatively low in the ZrB 2 crystal growth step which is the second step in the ZrB 2 initial nucleation step which is the first step. Also, by setting the raw material gas concentration ratio low, the reaction atmosphere has a high (100) orientation as an initial nucleus, and a reaction atmosphere in which a longitudinally long columnar structure is easily formed, and in the second step, the ZrB 2 crystal growth step By raising the reaction atmosphere temperature and increasing the raw material gas concentration ratio to make the reaction atmosphere easy to grow the longitudinal columnar structure, the longitudinal columnar structure has high (100) orientation and a desired high aspect ratio. You can get
[Deposition condition]
1) First step (ZrB 2 initial nucleation step)
Processing method: Film formation using CVD method Reaction gas composition (volume%):
Gas group A: BCl 3 : 0.25 to 1.00%, ZrCl 4 : 0.10 to 1.00%,
H 2 : Remainder
Reaction atmosphere temperature: 900 ° C. to 950 ° C.
Reaction atmosphere pressure: 3 kPa to 10 kPa
Reaction time: 20 to 90 minutes
2) Second step (ZrB 2 crystal growth step)
Processing method: Film formation using CVD method Reaction gas composition (volume%):
Gas group B: BCl 3 : 0.25 to 3.00%, ZrCl 4 : 0.20 to 2.00%,
H 2 : Remainder
Reaction atmosphere temperature: 900 ° C. to 1050 ° C.
Reaction atmosphere pressure: 3 kPa to 10 kPa
Reaction time: Until the target film thickness is reached
酸化アルミニウム層(上層)；
本発明被覆工具は、上部層であるＺｒ硼化物層の上層として酸化アルミニウム層を成膜することができる。
酸化アルミニウム層は、通常の化学蒸着法によって、０．３〜２．０μｍの平均層厚を有するα型Ａｌ２Ｏ３層もしくはκ型Ａｌ２Ｏ３層を形成することとした。
上部層に対し、上層として、α型Ａｌ２Ｏ３層もしくはκ型Ａｌ２Ｏ３層を形成することにより、さらに、硬質被覆層の高温硬さおよび耐熱性の向上を図ることができる。
かかる酸化アルミニウム層の平均層厚について、０．３μｍ未満では、耐摩耗性向上による寿命延長効果が少なく、また、その平均層厚が、２．０μｍを超えると、酸化アルミニウムの結晶粒が粗大化し易くなり、高温硬さ、高温強度の低下や、溶着チッピングや剥離等が発生するおそれがあるため、上記のとおり、その平均層厚は、０．３〜２．０μｍとすることが望ましい。
Aluminum oxide layer (upper layer);
The coated tool of the present invention can form an aluminum oxide layer as the upper layer of the Zr boride layer which is the upper layer.
The aluminum oxide layer was to form an α-type Al 2 O 3 layer or an κ-type Al 2 O 3 layer having an average layer thickness of 0.3 to 2.0 μm by a conventional chemical vapor deposition method.
By forming the α-type Al 2 O 3 layer or the κ-type Al 2 O 3 layer as the upper layer on the upper layer, it is possible to further improve the high temperature hardness and heat resistance of the hard coating layer.
With respect to the average layer thickness of such an aluminum oxide layer, if it is less than 0.3 μm, the life extension effect due to the improvement of the wear resistance is small, and if the average layer thickness exceeds 2.0 μm, the crystal grains of aluminum oxide become coarse. Since it becomes easy and there is a possibility that high temperature hardness, a fall of high temperature strength, welding chipping, exfoliation, etc. may occur, it is desirable for the average layer thickness to be 0.3-2.0 micrometers as mentioned above.
本発明に係る表面被覆切削工具は、工具基体の表面に形成されている硬質被覆層として、縦長柱状結晶組織を備えた高硬度のＺｒ硼化物（ＺｒＢ２）層を有することにより、結晶粒の脱落が生じにくい特性を有し、さらに、かかるＺｒ硼化物（ＺｒＢ２）層を構成する結晶粒は、（１００）面に最大ピーク強度を有し、また、（１００）面における配向性指数Ｔｃ（１００）が２．０以上であることにより、耐摩耗性および耐剥離性にすぐれた硬質被覆層を形成することから、合金工具鋼やＴｉ合金のような難削材の高速切削加工に用いた場合に、すぐれた切削特性を有し、さらなる工具寿命の向上をもたらすものである。 The surface-coated cutting tool according to the present invention is characterized by having a high hardness Zr boride (ZrB 2 ) layer provided with a longitudinally long columnar crystal structure as a hard coating layer formed on the surface of a tool substrate. The crystal grains which have the property of being less likely to drop off and which constitute such a Zr boride (ZrB 2 ) layer have the maximum peak intensity in the (100) plane, and the orientation index Tc in the (100) plane. When (100) is 2.0 or more, a hard coating layer excellent in wear resistance and peeling resistance is formed, so it is suitable for high-speed cutting of difficult-to-cut materials such as alloy tool steel and Ti alloy. If it has, it has excellent cutting characteristics and leads to further improvement of the tool life.
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。 Below, an Example demonstrates the coating tool of this invention concretely.
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、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、ＩＳＯ規格ＣＮＭＧ１２０４０８のインサート形状をもったＷＣ基超硬合金製の工具基体Ａ〜Ｃをそれぞれ製造した。 Prepare WC powder, TiC powder, ZrC powder, TaC powder, NbC powder, Cr 3 C 2 powder, TiN powder, and Co powder all having an average particle diameter of 1 to 3 μm as raw material powders, and these raw material powders are prepared Further, a wax is added, and the mixture is ball mill mixed in acetone for 24 hours, dried under reduced pressure, and pressed into a green compact having a predetermined shape at a pressure of 98 MPa, and this green compact Is vacuum sintered at a predetermined temperature in the range of 1370 ° C. to 1470 ° C. for 1 hour in a vacuum of 5 Pa, and after sintering, a WC base cemented carbide tool having an insert shape of ISO standard CNMG120408 Substrates A to C were produced respectively.
また、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、ＮｂＣ粉末、Ｃｒ３Ｃ２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、ＩＳＯ規格ＳＥＭＴ１３Ｔ３ＡＧＳＮインサート形状をもったＷＣ基超硬合金製の工具基体Ｄを作製した。 In addition, WC powder, TiC powder, NbC powder, Cr 3 C 2 powder, and Co powder all having an average particle diameter of 1 to 3 μm are prepared as raw material powders, and these raw material powders are compounded as shown in Table 1 Add to the composition, add a wax, mix in a ball mill in acetone for 24 hours, dry under reduced pressure, press-mold into a green compact of a predetermined shape at a pressure of 98 MPa, and press the green compact in a vacuum of 5 Pa 1370 Vacuum sintering was performed under the condition of holding for 1 hour at a predetermined temperature in the range of 1470 ° C., and after sintering, a tool substrate D made of WC-based cemented carbide having an ISO standard SEMT13T3AGSN insert shape 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、ＺｒＣ粉末、ＴａＣ粉末、ＮｂＣ粉末、Ｍｏ2Ｃ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：１５００℃に１時間保持の条件で焼結し、焼結後、ＩＳＯ規格ＣＮＭＧ１２０４０８インサート形状をもったＴｉＣＮ基サーメット製の工具基体Ｅを作製した。 Also, as raw material powders, TiCN powder (TiC / TiN = 50/50 by mass ratio), ZrC powder, TaC powder, NbC powder, Mo 2 C powder, WC powder all having an average particle diameter of 0.5 to 2 μm. , Co powder and Ni powder are prepared, these raw material powders are compounded into the composition shown in Table 2, wet mixed in a ball mill for 24 hours, dried and then pressed into a green compact at a pressure of 98 MPa, This green compact is sintered in a nitrogen atmosphere of 1.3 kPa at a temperature of 1500 ° C. for 1 hour, and after sintering, a tool base E made of TiCN-based cermet having an ISO standard CNMG120408 insert shape is produced. did.
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、ＺｒＣ粉末、ＴａＣ粉末、ＮｂＣ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：１５００℃に１時間保持の条件で焼結し、焼結後、ＩＳＯ規格ＳＥＭＴ１３Ｔ３ＡＧＳＮインサート形状をもったＴｉＣＮ基サーメット製の工具基体Ｆを作製した。 Moreover, as raw material powders, TiCN powder (TiC / TiN = 50/50 by mass ratio), ZrC powder, TaC powder, NbC powder, WC powder, Co powder and Ni powder having an average particle diameter of 0.5 to 2 μm in all cases. Powders are prepared, these raw material powders are compounded to the composition shown in Table 2, wet mixed in a ball mill for 24 hours, dried, and then pressed into a green compact at a pressure of 98 MPa, this green compact Sintering was performed in a nitrogen atmosphere of 1.3 kPa at a temperature of 1500 ° C. for 1 hour, and after sintering, a tool base F made of a TiCN-based cermet having an ISO standard SEMT13T3AGSN insert shape was produced.
ついで、これらの工具基体Ａ〜Ｆのそれぞれを、通常の化学蒸着装置に装入し、以下の手順にて本発明被覆工具１〜１４を製造した。
（ａ）まず、表６の工具基体記号にて示される表１もしくは表２の工具基体に対し、下部層として、表６にて示される目標層厚のＴｉ化合物層を表３にて示される形成条件にて、蒸着形成を行った。
（ｂ）次いで、表６の形成記号に基づき、表４にて示される形成条件により、目標層厚の上部層（Ｚｒ硼化物層）を蒸着形成し、酸化アルミニウム層を有するものについては、さらに、表５にて示される形成条件にて、目標層厚の酸化アルミニウム層を蒸着形成することにより、本発明被覆工具１〜１４をそれぞれ製造した。
Next, each of these tool substrates A to F was loaded into a conventional chemical vapor deposition apparatus, and coated tools 1 to 14 of the present invention were manufactured in the following procedure.
(A) First, with respect to the tool base of Table 1 or Table 2 shown by the tool base symbol of Table 6, as a lower layer, the Ti compound layer of the target layer thickness shown by Table 6 is shown by Table 3 Vapor deposition was performed under the forming conditions.
(B) Then, based on the formation symbols of Table 6, under the formation conditions shown in Table 4, the upper layer (Zr boride layer) of the target layer thickness is vapor deposited, and for those having an aluminum oxide layer, The coated tools 1 to 14 of the present invention were manufactured by vapor deposition of an aluminum oxide layer having a target layer thickness under the forming conditions shown in Table 5, respectively.
また、比較の目的で、本発明被覆工具１〜１４と同様の手順にて、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、以下の手順にて比較例被覆工具１〜１４を製造した。すなわち、
（ａ）表７の工具基体記号にて示される表１もしくは表２の工具基体に対し、下部層として、表７にて示される目標層厚のＴｉ化合物層を表３にて示される形成条件にて、蒸着形成を行った。
（ｂ）次いで、表７の形成記号に基づき、表４にて示される形成条件により、目標層厚の上部層（Ｚｒ硼化物層）を蒸着形成し、酸化アルミニウム層を有するものについては、さらに、表５にて示される形成条件にて、目標層厚の酸化アルミニウム層を蒸着形成することにより、比較例被覆工具１〜１４をそれぞれ製造した。
Further, for the purpose of comparison, each of the tool substrates A to F is loaded into a normal chemical vapor deposition apparatus in the same procedure as the coated tools 1 to 14 of the present invention, To 14 were produced. That is,
(A) For the tool base of Table 1 or Table 2 shown by the tool base symbol of Table 7, forming conditions shown by Table 3 as a lower layer, Ti compound layer of target layer thickness shown by Table 7 Deposition was performed.
(B) Then, based on the formation symbols of Table 7, the upper layer (Zr boride layer) of the target layer thickness is vapor deposited under the forming conditions shown in Table 4, and for those having an aluminum oxide layer, Comparative examples coated tools 1 to 14 were manufactured by vapor deposition of an aluminum oxide layer having a target layer thickness under the forming conditions shown in Table 5, respectively.
本発明被覆工具１〜１４および比較例被覆工具１〜１４の上部層（Ｚｒ硼化物層）について、Ｘ線回折により、各格子面からの回折ピーク強度を測定した。
図１に、本発明被覆工具１について求めたチャートを示す。
なお、Ｘ線回折は、装置としてスペクトリス社ＰＡＮａｌｙｔｉｃａｌ Ｅｍｐｙｒｅａｎを用い、ＣｕＫα線による２θ‐θ法で測定した。
測定条件は、測定範囲（２θ）：１５〜１３０度、Ｘ線出力：４５ｋＶ、４０ｍＡ、発散スリット：０．５度、スキャンステップ：０．０１３度、１ステップ辺り測定時間：０．４８ｓｅｃ／ｓｔｅｐである。
上記で求めたチャートから、最大の回折ピーク強度を有する格子面を示すことにより、（１００）面からの回折ピーク強度が最大であるか否かを判定した。（表６、表７を参照）
With respect to upper layers (Zr boride layers) of the coated tools 1 to 14 of the present invention and the comparative example coated tools 1 to 14, diffraction peak intensities from respective lattice planes were measured by X-ray diffraction.
FIG. 1 shows a chart obtained for the coated tool 1 of the present invention.
The X-ray diffraction was measured by a 2θ-θ method using CuKα ray, using a PANElytical Empyrean manufactured by Spectris as an apparatus.
Measurement conditions are: measurement range (2θ): 15 to 130 degrees, X-ray output: 45 kV, 40 mA, divergence slit: 0.5 degrees, scan step: 0.013 degrees, measurement time per one step: 0.48 sec / step It is.
From the chart determined above, it was judged whether or not the diffraction peak intensity from the (100) plane was the maximum by showing the lattice plane having the maximum diffraction peak intensity. (See Table 6, Table 7)
また、上記回折ピーク強度の測定結果に基づき、配向性指数Ｔｃ（１００）を求めた。
配向性指数Ｔｃ（１００）は、以下の式（Ａ）によって算出し、表６、表７に示す。
式（Ａ）
上記式（Ａ）において、Ｉ（ｈｋｌ）は測定された（ｈｋｌ）面のＸ線回折強度を示し、Ｉ０（ｈｋｌ）はＩＣＤＤカード００−０３４−０４２３によるＺｒＢ２の（ｈｋｌ）面のＸ線回折標準強度を示す。
また、（ｈｋｌ）は（００１）、（１００）、（１０１）、（１１０）、（１０２）、（１１１）、（２０１）、（１１２）の８面であり、式（Ａ）の中括弧内は８面の各面におけるＸ線回折強度のＸ線回折標準強度に対する比の平均値を示す。
Moreover, based on the measurement result of the said diffraction peak intensity, orientation index Tc (100) was calculated | required.
The orientation index Tc (100) was calculated by the following formula (A), and is shown in Tables 6 and 7.
Formula (A)
In the above-mentioned formula (A), I (hkl) shows the X-ray diffraction intensity of the measured (hkl) plane, and I 0 (hkl) is the X of (hkl) plane of ZrB 2 by ICDD card 00-034-0423. The line diffraction standard intensity is shown.
Further, (hkl) is the eight faces of (001), (100), (101), (110), (102), (111), (201), (112), and the braces of the formula (A) The inside shows the average value of the ratio of the X-ray diffraction intensity to the X-ray diffraction standard intensity in each of the eight planes.
また、本発明被覆工具１〜１４および比較例被覆工具１〜１４の上部層（Ｚｒ硼化物層）の縦断面について、走査型電子顕微鏡（ＳＥＭ）を用い、倍率５０００にて断面観察により得られた縦断面画像について、電子線後方散乱回折法（ＥＢＳＤ）により、個々の結晶粒につき、長軸径、短軸径、および、縦断面の面積を測定し、長軸径および短軸径よりアスペクト比を求め、次いで、アスペクト比が３以上である結晶粒の縦断面における面積の総和に対する測定対象となった縦断面の面積の比率を面積割合として求め、表６、表７に示した。 In addition, the longitudinal section of the upper layer (Zr boride layer) of the coated tools 1 to 14 of the present invention and the comparative example coated tools 1 to 14 is obtained by cross-sectional observation at a magnification of 5000 using a scanning electron microscope (SEM). The major axis diameter, the minor axis diameter, and the area of the longitudinal cross section of each crystal grain are measured by electron beam backscattering diffraction (EBSD), and the aspect from the major axis diameter and minor axis diameter The ratio was determined, and then the ratio of the area of the longitudinal section to be measured to the total area of the longitudinal sections of crystal grains having an aspect ratio of 3 or more was determined as the area ratio, and is shown in Tables 6 and 7.
また、本発明被覆工具１〜１４および比較例被覆工具１〜１４の硬質被覆層の各構成層の厚さを、走査型電子顕微鏡（ＳＥＭ）を用いて縦断面測定を行い５点測定の平均値より求めたところ、いずれも目標層厚と実質的に同じ平均層厚を示した。 In addition, the thickness of each constituent layer of the hard coating layers of the coated tools 1 to 14 of the present invention and the coated tools of comparative examples 1 to 14 is subjected to longitudinal cross-sectional measurement using a scanning electron microscope (SEM). As determined from the values, all showed substantially the same average layer thickness as the target layer thickness.
また、本発明被覆工具１〜１４および比較例被覆工具１〜１４の上部層（Ｚｒ硼化物層）について、ナノインデンテーション試験法（ＩＳＯ １４５７７）に基づき、Ｚｒ硼化物層の表面を研磨し、ダイヤモンド製のBerkovich圧子を用いて、押し込み荷重２００ｍｇｆにて、測定を行った。測定点数はそれぞれの試料で２０点ずつとし、その平均値を表６、表７に示した。 In addition, with respect to upper layers (Zr boride layers) of the present invention coated tools 1 to 14 and comparative example coated tools 1 to 14, the surface of the Zr boride layer is polished based on the nanoindentation test method (ISO 14577), The measurement was performed using a Berkovich indenter made of diamond with a pushing load of 200 mgf. The number of measurement points was 20 for each sample, and the average value is shown in Table 6 and Table 7.
つぎに、前記各種の被覆工具を工具鋼製バイト先端部に固定治具にてクランプした状態で、本発明被覆工具１〜１０、比較例被覆工具１〜１０について、以下に示す、インコネル７１８の乾式連続切削試験を実施し、切刃の逃げ面摩耗幅を測定するとともに、溶着の発生等の有無について観察を行い、結果を表８に示した。 Next, in a state in which the above various coated tools are clamped by a fixing jig at the tip of a tool steel cutting tool, Inconel 718 shown below for the coated tools according to the present invention 1-10 and comparative examples coated tools 1-10. The dry continuous cutting test was conducted to measure the flank wear width of the cutting edge, and the occurrence of welding was observed, and the results are shown in Table 8.
≪切削条件Ａ≫
切削試験：インコネル７１８の乾式連続切削試験
被削材： インコネル７１８丸棒
切削速度：６０ｍ／ｍｉｎ、
切り込み：１．０ｍｍ、
送り量：０．２ｍｍ／ｒｅｖ．
切削時間：５分、
«Cutting condition A»
Cutting test: Inconel 718 dry continuous cutting test Work material: Inconel 718 round bar
Cutting speed: 60 m / min,
Cut: 1.0 mm,
Feeding amount: 0.2 mm / rev.
Cutting time: 5 minutes,
また、前記各種の被覆工具を工具鋼製カッタ先端部に固定治具にてクランプした状態で、本発明被覆工具１１〜１４、比較例被覆工具１１〜１４について、以下に示す、高速断続重切削の一種である乾式高速正面フライス、センターカット切削加工試験を実施し、切刃の逃げ面摩耗幅測定を行い、結果を表９に示した。
≪切削条件Ｂ≫
切削試験：金型鋼ＳＫＤ６１の乾式高速正面フライス切削試験
被削材： ＪＩＳ・ＳＫＤ６１ 幅６０ｍｍ、長さ４００ｍｍのブロック材
回転速度：１２００ｍｉｎ−１、
切削速度：３００ｍ／ｍｉｎ、
切り込み：１．５ｍｍ、
一刃送り量：０．２ｍｍ／刃、
切削時間：５分、
Further, in the state where the above various coated tools are clamped by a fixing jig to the tip end portion of a tool steel cutter, high-speed interrupted heavy cutting shown below for coated tools 11 to 14 of the present invention and comparative examples coated tools 11 to 14 The dry-type high-speed face milling machine, which is one of the above, and the center cut cutting test were conducted, the flank wear width measurement of the cutting edge was conducted, and the results are shown in Table 9.
«Cutting condition B»
Cutting test: Dry high-speed face milling cutting test of mold steel SKD61 Work material: JIS · SKD 61 Block material of width 60 mm, length 400 mm Rotational speed: 1200 min -1 ,
Cutting speed: 300 m / min,
Cut: 1.5 mm,
Single blade feed amount: 0.2 mm / blade,
Cutting time: 5 minutes,
表８および表９に示される結果から、本発明の表面被覆切削工具は、高配向性を示す縦長柱状結晶組織を有するＺｒ硼化物層を硬質被覆層として含むことにより、難削材である合金工具鋼やＴｉ合金の高速切削加工において、すぐれた耐チッピング性および耐摩耗性を発揮するものである。
これに対し、比較例被覆工具は、いずれも、柱状結晶組織を有していないなど、所望の構造を有していないため、摩耗の進展、溶着の発生、チッピングの発生等により、短時間で寿命に至るものであった。
From the results shown in Tables 8 and 9, the surface-coated cutting tool of the present invention is an alloy which is a hard-to-cut material by including a Zr boride layer having a longitudinally oriented columnar crystal structure exhibiting high orientation as a hard coating layer. It exhibits excellent chipping resistance and wear resistance in high-speed cutting of tool steel and Ti alloy.
On the other hand, all the coated tools according to the comparative example do not have a desired structure such as having no columnar crystal structure, and therefore, in a short time due to the progress of wear, the occurrence of welding, the occurrence of chipping, etc. It reached the end of life.
前述のとおり、本発明の表面被覆切削工具は、合金工具鋼やＴｉ合金のような難削材の高速切削加工においてもすぐれた、耐溶着性、耐チッピング性、耐摩耗性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、さらには、低コスト化に十分満足するものである。 As described above, the surface-coated cutting tool of the present invention exhibits excellent adhesion resistance, chipping resistance, and wear resistance, which is excellent even in high-speed cutting of difficult-to-cut materials such as alloy tool steels and Ti alloys. Because of this, it is sufficiently satisfactory to improve the performance of cutting devices, save labor and energy for cutting, and reduce costs.
Claims (3)
（ａ）前記硬質被覆層は、前記工具基体の表面側から下部層および上部層を有してなり、
（ｂ）前記下部層は、Ｔｉの炭化物層、窒化物層、炭窒化物層、炭酸化物層および炭窒酸化物層のうちの１層または２層以上からなり、かつ、０．１〜３．０μｍの合計平均層厚を有するＴｉ化合物層を有し、
（ｃ）前記上部層は、１．０〜１５．０μｍの平均層厚を有するＺｒ硼化物層を有し、
（ｄ）前記上部層の縦断面において、アスペクト比が３以上である縦長柱状結晶粒が、面積割合で８０％以上である縦長柱状結晶組織を有し、
（ｅ）前記上部層は、（１００）面にＸ線回折による最大ピークが現れるＺｒ硼化物層であり、以下の式（Ａ）で表されるＺｒ硼化物層の配向性指数Ｔｃ（ｈｋｌ）がＴｃ（１００）≧２．０を満たすことを特徴とする表面被覆切削工具。
式（Ａ）
式（Ａ）において、Ｉ（ｈｋｌ）は（ｈｋｌ）面のＸ線回折強度を示し、Ｉ０（ｈｋｌ）はＩＣＤＤカード００−０３４−０４２３によるＺｒＢ２の（ｈｋｌ）面のＸ線回折標準強度を示す。
また、（ｈｋｌ）は（００１）、（１００）、（１０１）、（１１０）、（１０２）、（１１１）、（２０１）、（１１２）の８面であり、式（１）の中括弧内は各面におけるＸ線回折強度のＸ線回折標準強度に対する比の平均値を示す。 In a surface-coated cutting tool in which a hard coating layer is formed on the surface of a tool base consisting of a tungsten carbide-based cemented carbide or titanium carbonitride-based cermet,
(A) The hard coating layer has a lower layer and an upper layer from the surface side of the tool substrate,
(B) The lower layer is composed of one or more layers of a carbide layer, a nitride layer, a carbonitride layer, a carbon oxide layer and a carbon oxynitride layer of Ti, and 0.1 to 3 With a Ti compound layer having a total average layer thickness of 0 μm,
(C) the upper layer comprises a Zr boride layer having an average layer thickness of 1.0 to 15.0 μm;
(D) In the longitudinal section of the upper layer, longitudinally elongated columnar crystal grains having an aspect ratio of 3 or more have a longitudinally elongated columnar crystal structure having an area ratio of 80% or more,
(E) The upper layer is a Zr boride layer in which the maximum peak appears in the (100) plane by X-ray diffraction, and the orientation index Tc (hkl) of the Zr boride layer represented by the following formula (A) A surface-coated cutting tool characterized by satisfying Tc (100) ≧ 2.0.
Formula (A)
In the formula (A), I (hkl) represents the X-ray diffraction intensity of the (hkl) plane, and I 0 (hkl) represents the standard X-ray diffraction intensity of the (hkl) plane of ZrB 2 by ICDD card 00-034-0423. Indicates
Further, (hkl) is the eight faces of (001), (100), (101), (110), (102), (111), (201), (112), and the braces of the formula (1) The inside shows the average value of the ratio of the X-ray diffraction intensity to the X-ray diffraction standard intensity in each surface.
The surface-coated cutting tool according to claim 1 or 2, wherein an α or 型 -type Al 2 having an average layer thickness of 0.3 to 2.0 μm as an upper layer of the Zr boride layer which is the upper layer. The surface-coated cutting tool according to claim 1 or 2, further comprising an O 3 layer.
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