JP5850402B2 - Surface coated cutting tool with excellent chipping resistance due to hard coating layer - Google Patents
Surface coated cutting tool with excellent chipping resistance due to hard coating layer Download PDFInfo
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本発明は、高熱発生を伴うとともに、切れ刃に断続的・衝撃的負荷が作用する各種の鋼や鋳鉄の高速断続切削加工において、硬質被覆層がすぐれた耐チッピング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発揮する表面被覆切削工具（以下、被覆工具という）に関するものである。 In the present invention, high-speed intermittent cutting of various steels and cast irons with high heat generation and intermittent / impact loads acting on the cutting edge, the hard coating layer has excellent chipping resistance, which makes it possible to The present invention relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) that exhibits excellent cutting performance over use.
従来、一般に、炭化タングステン（以下、ＷＣで示す）基超硬合金または炭窒化チタン（以下、ＴｉＣＮで示す）基サーメットで構成された工具基体（以下、これらを総称して工具基体という）の表面に、
（ａ）下部層が、いずれも化学蒸着形成された、Ｔｉの炭化物（以下、ＴｉＣで示す）層、窒化物（以下、ＴｉＮで示す）層、炭窒化物（以下、ＴｉＣＮで示す）層、炭酸化物（以下、ＴｉＣＯで示す）層および炭窒酸化物（以下、ＴｉＣＮＯで示す）層のうちの１層または２層以上からなるＴｉ化合物層、
（ｂ）上部層が、化学蒸着形成された酸化アルミニウム層、
以上（ａ）および（ｂ）で構成された硬質被覆層を形成してなる被覆工具が知られており、この被覆工具は、各種の鋼や鋳鉄などの切削加工に用いられていることが知られている。
ただ、前記被覆工具は、切れ刃に大きな負荷がかかる切削条件では、チッピングや欠損等を発生しやすく、工具寿命が短命であるという問題があるため、これを解消するために、従来からいくつかの提案がなされている。
Conventionally, the surface of a tool substrate (hereinafter collectively referred to as a tool substrate) generally composed of tungsten carbide (hereinafter referred to as WC) -based cemented carbide or titanium carbonitride (hereinafter referred to as TiCN) -based cermet. In addition,
(A) Ti carbide (hereinafter referred to as TiC) layer, nitride (hereinafter referred to as TiN) layer, carbonitride (hereinafter referred to as TiCN) layer, all of which are formed by chemical vapor deposition of the lower layer, A Ti compound layer comprising one or more of a carbon oxide (hereinafter referred to as TiCO) layer and a carbonitride oxide (hereinafter referred to as TiCNO) layer;
(B) the upper layer is an aluminum oxide layer formed by chemical vapor deposition;
A coated tool formed by forming a hard coating layer composed of (a) and (b) above is known, and this coated tool is known to be used for cutting various steels and cast irons. It has been.
However, the above-mentioned coated tool has problems that chipping and chipping are likely to occur under cutting conditions in which a heavy load is applied to the cutting edge, and the tool life is short-lived. Proposals have been made.
例えば、特許文献１には、硬質被覆層をＴｉＣＮの単層または２層以上の積層で構成すると共に、これら構成層のうちの１層または２層以上を、（ａ）粒状結晶組織から縦長成長結晶組織へ変る結晶構造、（ｂ）粒状結晶組織から縦長成長結晶組織へ、さらにこの縦長成長結晶組織から粒状結晶組織へ変る結晶構造、（ｃ）縦長成長結晶組織から粒状結晶組織へ変る結晶構造のうちのいずれか、または２種以上の結晶構造で構成することによって、耐チッピング性にすぐれた被覆工具を提供することが開示されている。 For example, in Patent Document 1, a hard coating layer is composed of a single layer of TiCN or a laminate of two or more layers, and one or two or more of these constituent layers are (a) vertically grown from a granular crystal structure. A crystal structure that changes to a crystal structure, (b) a crystal structure that changes from a granular crystal structure to a vertically grown crystal structure, and further changes from this vertically grown crystal structure to a granular crystal structure, and (c) a crystal structure that changes from a vertically elongated crystal structure to a granular crystal structure. It is disclosed that a coated tool having excellent chipping resistance can be provided by constituting one of the above or two or more crystal structures.
また、特許文献２には、超硬合金またはサーメットからなる基体表面にセラミック皮膜を形成した表面被覆切削工具において、前記セラミック被覆が柱状晶のＴｉＣＮ層を必ず含む単層または多層で構成され、該ＴｉＣＮ層の上端から該ＴｉＣＮ層の厚さの１／５の距離の位置におけるＴｉＣＮ柱状結晶粒の水平方向の平均粒径ｄ１と、該ＴｉＣＮ層の下端から該ＴｉＣＮ層の厚さの２／５の距離の位置におけるＴｉＣＮ柱状結晶粒の水平方向の平均粒径ｄ２の比を１≦ｄ１／ｄ２≦１．３とするように構成することによって、耐摩耗性、耐欠損性の両方にすぐれ、断続切削を含む長時間の切削加工に耐えることが開示されている。 Further, in Patent Document 2, in a surface-coated cutting tool in which a ceramic film is formed on the surface of a substrate made of cemented carbide or cermet, the ceramic coating is composed of a single layer or a multilayer that necessarily includes a columnar TiCN layer, The horizontal average grain size d1 of the TiCN columnar crystal grains at a position 1/5 of the thickness of the TiCN layer from the upper end of the TiCN layer, and 2/5 of the thickness of the TiCN layer from the lower end of the TiCN layer By configuring the ratio of the horizontal average grain size d2 of the TiCN columnar crystal grains at a distance of 1 ≦ d1 / d2 ≦ 1.3, both the wear resistance and the fracture resistance are excellent. It is disclosed that it can withstand long-time cutting including intermittent cutting.
さらに、特許文献３には、硬質被覆層として、少なくともＴｉＣＮ層と酸化アルミニウム層を有する被覆工具において、該ＴｉＣＮ層は、下部ＴｉＣＮ層と上部ＴｉＣＮ層とからなり、下部ＴｉＣＮ層の膜厚ｔ１は１μｍ≦ｔ１≦１０μｍ、上部ＴｉＣＮ層の膜厚ｔ２は０．５μｍ≦ｔ２≦５μｍであって、かつ、１＜ｔ１／ｔ２≦５の関係を満足し、さらに、上部ＴｉＣＮ層のＴｉＣＮ粒子の平均結晶幅ｗ２は０．２〜１．５μｍであって、下部ＴｉＣＮ層のＴｉＣＮ粒子の平均結晶幅ｗ１はｗ２の０．７倍以下とすることによって、硬質被覆層の密着性を高め、層間剥離を防止し、断続切削加工等における耐欠損性、耐摩耗性の改善を図ることが開示されている。 Furthermore, in Patent Document 3, in a coated tool having at least a TiCN layer and an aluminum oxide layer as a hard coating layer, the TiCN layer is composed of a lower TiCN layer and an upper TiCN layer, and the film thickness t1 of the lower TiCN layer is 1 μm ≦ t1 ≦ 10 μm, the film thickness t2 of the upper TiCN layer is 0.5 μm ≦ t2 ≦ 5 μm, satisfies the relationship of 1 <t1 / t2 ≦ 5, and further the average of TiCN particles in the upper TiCN layer The crystal width w2 is 0.2 to 1.5 μm, and the average crystal width w1 of the TiCN particles in the lower TiCN layer is 0.7 times or less of w2, thereby improving the adhesion of the hard coating layer and delamination It is disclosed to improve the chipping resistance and wear resistance in intermittent cutting and the like.
近年の切削加工における省力化および省エネ化の要求は強く、これに伴い、被覆工具は一段と過酷な条件下で使用されるようになってきているが、例えば、前記特許文献１乃至３に示される被覆工具においても、高熱発生を伴うとともに、より一段と切れ刃に断続的・衝撃的負荷が作用する高速断続切削加工に用いられた場合には、下部層の熱伝導率が高く、熱遮蔽効果が十分ではなく、また、靭性においても十分でないために、切削加工時の高負荷によって切れ刃にチッピング、欠損が発生しやすく、その結果、比較的短時間で使用寿命に至るのが現状である。 In recent years, there is a strong demand for energy saving and energy saving in cutting, and along with this, coated tools have come to be used under severer conditions. For example, Patent Documents 1 to 3 show the above. Even when a coated tool is used for high-speed intermittent cutting with high heat generation and more intermittent and impact loads on the cutting edge, the thermal conductivity of the lower layer is high and the heat shielding effect is high. Since it is not sufficient and the toughness is not sufficient, chipping and chipping are likely to occur at the cutting edge due to a high load during cutting, and as a result, the service life is reached in a relatively short time.
そこで、本発明者らは、前述のような観点から、高熱発生を伴い、かつ、切れ刃に断続的・衝撃的負荷が作用する高速断続切削加工に用いられた場合でも、硬質被覆層がすぐれた靭性および熱遮蔽効果を備え、その結果、長期の使用に亘ってすぐれた耐チッピング性、耐欠損性を発揮する被覆工具について鋭意研究を行った結果、以下の知見を得たのである。 In view of the above, the inventors of the present invention have an excellent hard coating layer even when used in high-speed intermittent cutting with high heat generation and intermittent and impact loads acting on the cutting edge. As a result of earnest research on a coated tool that has excellent toughness and heat shielding effect, and as a result, exhibits excellent chipping resistance and fracture resistance over a long period of use, the following knowledge has been obtained.
即ち、硬質被覆層として、従来の少なくとも１層のＴｉＣＮ層を含み、かつ所定の合計平均層厚を有する１層または２層以上からなるＴｉ化合物層からなる下部層を形成したものにおいては、ＴｉＣＮ層が基体的に垂直方向に柱状をなして形成されている。そのため、耐摩耗性および熱伝導率は向上する。その反面、ＴｉＣＮ層の異方性が高くなるほどＴｉＣＮ層の靭性および熱遮蔽効果が低下し、その結果、耐チッピング性、耐欠損性が低下し、長期の使用に亘って十分な耐摩耗性を発揮することができず、また、工具寿命も満足できるものであるとはいえなかった。
そこで、本発明者らは、硬質被覆層の下部層を構成するＴｉＣＮ層について鋭意研究したところ、ＴｉＣＮ層の異方性を緩和し靭性および熱遮蔽効果を高めることによって、硬質被覆層の耐チッピング性、耐欠損性を向上させることができるという新規な知見を見出したのである。
That is, in the case where the hard coating layer includes at least one conventional TiCN layer and has a lower layer composed of one or two or more Ti compound layers having a predetermined total average layer thickness, The layer is formed in a columnar shape in the vertical direction as a base. Therefore, wear resistance and thermal conductivity are improved. On the other hand, the higher the anisotropy of the TiCN layer, the lower the toughness and heat shielding effect of the TiCN layer. As a result, chipping resistance and chipping resistance are reduced, and sufficient wear resistance is ensured over a long period of use. It could not be demonstrated, and the tool life was not satisfactory.
Therefore, the present inventors conducted extensive research on the TiCN layer that constitutes the lower layer of the hard coating layer. As a result, the chipping resistance of the hard coating layer was improved by reducing the anisotropy of the TiCN layer and improving the toughness and heat shielding effect. The inventors have found a novel finding that it is possible to improve the property and fracture resistance.
具体的には、下部層を構成する少なくとも１層のＴｉＣＮ層が、柱状縦長成長ＴｉＣＮ結晶組織を有しており、その組織内に微粒ＴｉＣＮからなる副層を少なくとも２層以上存在させることにより、ＴｉＣＮ層の異方性が緩和され、靭性および熱遮蔽効果が高められる。 Specifically, at least one TiCN layer constituting the lower layer has a columnar vertically grown TiCN crystal structure, and by having at least two or more sublayers made of fine TiCN in the structure, The anisotropy of the TiCN layer is relaxed, and the toughness and the heat shielding effect are enhanced.
そして、前述のような構成のＴｉＣＮ層は、例えば、以下の化学蒸着法によって成膜することができる。
（ａ）工具基体表面に、反応ガス組成（容量％）を、ＴｉＣｌ４：１．６〜２．０％、ＣＨ３ＣＮ：０．６〜１．０％、Ｎ２：２０％、Ｈ２：残、として、反応雰囲気圧力を５〜１０ｋＰａ、反応雰囲気温度を８００〜９４０℃として、化学蒸着法を行うことにより、柱状縦長成長ＴｉＣＮ結晶組織を成膜し、
（ｂ）次いで、前記（ａ）の成膜工程を停止し、その後、ＴＤＭＡＴ（テトラキスジメチルアミノチタン）：０．１〜０．２％、Ｎ２：５〜７％、Ｈ２：残、とした副層形成条件で１〜１０分間化学蒸着法を行うことにより微粒ＴｉＣＮの副層を形成し、
（ｃ）次いで、前記（ｂ）の工程後、前記（ａ）と同様の条件で化学蒸着法を行うことにより柱状縦長成長ＴｉＣＮ結晶組織を成膜し、
（ｄ）前記（ｂ）、（ｃ）の工程を繰り返し行なうことによって、微粒ＴｉＣＮの副層が少なくとも２層以上存在する柱状縦長成長ＴｉＣＮ結晶組織からなる下部層を得ることができる。
この時、副層により柱状縦長成長ＴｉＣＮ結晶組織が完全に分断されることなく、柱状組織のまま成長することを見出した。その結果、柱状縦長成長ＴｉＣＮ結晶組織が有する耐摩耗性を低下させることなく、靭性および熱遮蔽効果を向上させることができるため、耐チッピング性、耐欠損性が飛躍的に向上する。
The TiCN layer having the above-described configuration can be formed by, for example, the following chemical vapor deposition method.
(A) On the surface of the tool base, the reaction gas composition (volume%) is TiCl 4 : 1.6 to 2.0%, CH 3 CN: 0.6 to 1.0%, N 2 : 20%, H 2 : As the rest, a columnar vertically grown TiCN crystal structure was formed by performing chemical vapor deposition with a reaction atmosphere pressure of 5 to 10 kPa and a reaction atmosphere temperature of 800 to 940 ° C.
(B) Then, stop the film forming process of the (a), then, TDMAT (tetrakis-dimethylamino titanium): 0.1~0.2%, N 2: 5~7%, H 2: remainder, and Forming a sub-layer of fine TiCN by performing chemical vapor deposition for 1 to 10 minutes under the sub-layer forming conditions
(C) Next, after the step (b), a columnar vertically grown TiCN crystal structure is formed by performing chemical vapor deposition under the same conditions as in (a),
(D) By repeating the steps (b) and (c), a lower layer composed of a columnar vertically grown TiCN crystal structure in which at least two fine TiCN sublayers are present can be obtained.
At this time, it was found that the columnar vertically-grown TiCN crystal structure was grown in the columnar structure without being completely divided by the sublayer. As a result, since the toughness and the heat shielding effect can be improved without reducing the wear resistance of the columnar vertically grown TiCN crystal structure, the chipping resistance and fracture resistance are dramatically improved.
そして、柱状縦長成長ＴｉＣＮ層中の微粒ＴｉＣＮの副層が層厚方向１μｍあたり１〜５層存在する場合には、特に、高熱発生を伴い、かつ、切れ刃に断続的・衝撃的負荷が作用する鋼や鋳鉄の高速断続切削加工に用いた場合でも、硬質被覆層が耐チッピング性、耐欠損性にすぐれ、長期の使用に亘ってすぐれた耐摩耗性を発揮し得ることを見出した。 And, when the sub-layer of fine TiCN in the columnar vertically grown TiCN layer is present in 1 to 5 layers per 1 μm in the layer thickness direction, it is accompanied by high heat generation, and intermittent and impact loads act on the cutting edge. It has been found that even when used for high-speed intermittent cutting of steel and cast iron, the hard coating layer has excellent chipping resistance and chipping resistance, and can exhibit excellent wear resistance over a long period of use.
（ｅ）前記下部層の形成後、反応ガス組成（容量％）を、ＡｌＣｌ３：２〜３％、ＣＯ２：４〜６％、ＨＣｌ：２〜３％、Ｈ２Ｓ：０．１〜０．５％、Ｈ２：残、として、反応雰囲気圧力を５〜１０ｋＰａ、反応雰囲気温度を８７０〜１０４０℃として、化学蒸着法を行うことにより酸化アルミニウム層からなる上部層を成膜することにより、高温硬さと耐熱性を付与することができ、前記下部層が奏する効果と相俟って、一層すぐれた耐チッピング性、耐欠損性を有する硬質被覆層が得られることを見出した。 (E) After the formation of the lower layer, the reaction gas composition (volume%) is AlCl 3 : 2-3%, CO 2 : 4-6%, HCl: 2-3%, H 2 S: 0.1 By forming a top layer made of an aluminum oxide layer by performing chemical vapor deposition at 0.5%, H 2 : the rest, with a reaction atmosphere pressure of 5 to 10 kPa and a reaction atmosphere temperature of 870 to 1040 ° C. The present inventors have found that a hard coating layer having excellent chipping resistance and chipping resistance can be obtained in combination with the effects exerted by the lower layer, which can impart high temperature hardness and heat resistance.
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で構成された工具基体の表面に硬質被覆層を設けた表面被覆切削工具において、
前記硬質被覆層が下部層と上部層とからなるとともに、
（ａ）前記下部層は、少なくとも１層のＴｉの炭窒化物層を含み、かつ、３〜２０μｍの合計平均層厚を有する１層または２層以上からなるＴｉ化合物層、
（ｂ）前記上部層は、２〜２５μｍの平均層厚を有する酸化アルミニウム層、
からなり、
前記（ａ）の下部層を構成する少なくとも１層のＴｉの炭窒化物層は、柱状縦長成長ＴｉＣＮ結晶組織を有しており、その組織内に微粒ＴｉＣＮからなる副層が少なくとも２層以上、柱状縦長成長ＴｉＣＮ結晶組織を完全に分断せずに存在しており、該微粒ＴｉＣＮが粒状ＴｉＣＮ結晶相又はアモルファスＴｉＣＮ相若しくは粒状ＴｉＣＮ結晶相とアモルファスＴｉＣＮ相との混合相であり、前記柱状縦長成長ＴｉＣＮ結晶の最大粒子幅は５０〜２０００ｎｍ、前記最大粒子幅と膜厚方向の最大粒子長さとのアスペクト比が５〜５０であり、前記微粒ＴｉＣＮからなる副層の層厚が、５ｎｍ〜３０ｎｍであることを特徴とする表面被覆切削工具。
（２） 前記下部層を構成する少なくとも１層のＴｉの炭窒化物層に存在する微粒ＴｉＣＮからなる副層が層厚方向１μｍあたり１〜５層存在することを特徴とする（１）に記載の表面被覆切削工具。」
に特徴を有するものである。
The present invention has been made based on the above findings,
“(1) In a surface-coated cutting tool in which a hard coating layer is provided on the surface of a tool base composed of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet,
Together with the hard coating layer is composed of a lower portion layer and the upper layer,
(A) The lower layer includes at least one Ti carbonitride layer, and has a total average layer thickness of 3 to 20 μm, a Ti compound layer composed of one layer or two or more layers,
(B) the upper layer is an aluminum oxide layer having an average layer thickness of 2 to 25 μm;
Consists of
The at least one Ti carbonitride layer constituting the lower layer of (a) has a columnar vertically grown TiCN crystal structure, and at least two or more sublayers made of fine TiCN in the structure, The columnar vertically grown TiCN crystal structure exists without being completely divided, and the fine TiCN is a granular TiCN crystal phase or an amorphous TiCN phase or a mixed phase of a granular TiCN crystal phase and an amorphous TiCN phase, and the columnar vertically grown The maximum particle width of the TiCN crystal is 50 to 2000 nm, the aspect ratio of the maximum particle width and the maximum particle length in the film thickness direction is 5 to 50, and the layer thickness of the sublayer made of the fine TiCN is 5 nm to 30 nm. A surface-coated cutting tool characterized in that there is.
(2) The sublayer consisting of fine TiCN present in at least one Ti carbonitride layer constituting the lower layer is present in 1 to 5 layers per 1 μm in the layer thickness direction. Surface coated cutting tool. "
It has the characteristics.
本発明について、以下に詳細に説明する。 The present invention will be described in detail below.
下部層のＴｉ化合物層：
少なくとも１層のＴｉの炭窒化物層を含み、かつ、３〜２０μｍの合計平均層厚を有する１層または２層以上のＴｉ化合物層からなる下部層は、通常の化学蒸着条件で形成することができるが、少なくとも１層のＴｉの炭窒化物層については後述するような別の方法によって形成する。下部層を構成するＴｉ化合物層は、それ自体が高温強度を有し、これの存在によって硬質被覆層が高温強度を具備するようになるほか、工具基体と酸化アルミニウムからなる上部層のいずれにも強固に密着し、よって硬質被覆層の工具基体に対する密着性向上に寄与する作用をもつが、特に合計平均層厚が３〜２０μｍのとき、その効果が際立って発揮される。その理由は、合計平均層厚が３μｍ未満では、層厚が薄いため前記作用を発揮させるには十分でなく、一方、その合計平均層厚が２０μｍを越えると、Ｔｉ化合物の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。したがって、その合計平均層厚を３〜２０μｍと定めた。
また、前記下部層の少なくとも１層のＴｉの炭窒化物層は、柱状縦長成長ＴｉＣＮ結晶組織を有しており、その組織内に微粒ＴｉＣＮからなる副層が少なくとも２層以上、柱状縦長成長ＴｉＣＮ結晶を完全に分断せずに存在する構成とする。このような構成にすることによって、ＴｉＣＮ層の異方性が緩和されるため靭性および熱遮蔽効果が向上し、すぐれた耐チッピング性および耐欠損性を示すようになる。
Lower Ti compound layer:
The lower layer composed of one or more Ti compound layers including at least one Ti carbonitride layer and having a total average layer thickness of 3 to 20 μm should be formed under normal chemical vapor deposition conditions. However, at least one Ti carbonitride layer is formed by another method as described later. The Ti compound layer constituting the lower layer itself has a high temperature strength, and the presence of the Ti compound layer makes the hard coating layer have a high temperature strength, as well as both the tool base and the upper layer made of aluminum oxide. Although it adheres firmly and thus contributes to improving the adhesion of the hard coating layer to the tool substrate, the effect is particularly prominent when the total average layer thickness is 3 to 20 μm. The reason is that if the total average layer thickness is less than 3 μm, the layer thickness is so thin that it is not sufficient to exert the above-mentioned effect. On the other hand, if the total average layer thickness exceeds 20 μm, the Ti compound crystal grains become coarse. It becomes easy to generate chipping. Therefore, the total average layer thickness was set to 3 to 20 μm.
The at least one Ti carbonitride layer of the lower layer has a columnar vertically grown TiCN crystal structure, and at least two or more sublayers made of fine TiCN are included in the structure, and the columnar vertically grown TiCN. The crystal is present without being completely divided. By adopting such a configuration, the anisotropy of the TiCN layer is relaxed, so that the toughness and the heat shielding effect are improved, and excellent chipping resistance and fracture resistance are exhibited.
上部層の酸化アルミニウム層：
上部層を構成する酸化アルミニウム層が、高温硬さと耐熱性を備えることは既に良く知られているが、特にその平均層厚が２〜２５μｍのとき、その効果が際立って発揮される。その理由は、平均層厚が２μｍ未満では、層厚が薄いため長期の使用に亘っての耐摩耗性を確保するには十分でなく、一方、平均層厚が２５μｍを越えると酸化アルミニウム結晶粒が粗大化し易くなり、高温硬さ、高温強度の低下に加え、高速断続切削加工時の耐チッピング性、耐欠損性が低下するようになる。したがって、その平均層厚を２〜２５μｍと定めた。
Upper aluminum oxide layer:
It is already well known that the aluminum oxide layer constituting the upper layer has high-temperature hardness and heat resistance, but the effect is particularly remarkable when the average layer thickness is 2 to 25 μm. The reason is that if the average layer thickness is less than 2 μm, the layer thickness is so thin that it is not sufficient to ensure wear resistance over a long period of use, while if the average layer thickness exceeds 25 μm, the aluminum oxide crystal grains As a result, the chipping resistance and chipping resistance at the time of high-speed intermittent cutting are reduced in addition to the decrease in high-temperature hardness and high-temperature strength. Therefore, the average layer thickness was set to 2 to 25 μm.
更に本発明は、前記の構成に加えて、以下の条件を併せ持つとき、より一層、すぐれた効果を発揮する。 Furthermore, in addition to the above-described configuration, the present invention exhibits a further excellent effect when it has the following conditions.
柱状縦長成長ＴｉＣＮ結晶組織内の副層の層厚：
前記副層の層厚は、５〜３０ｎｍのとき、その効果が際立って発揮される。その理由は、副層の層厚が５ｎｍ未満であると副層の微粒ＴｉＣＮ層の異方性を緩和し、靭性および熱遮蔽効果を高めるという副層の持つ作用が十分に発揮されない。一方、副層の層厚が３０ｎｍを超えると柱状縦長成長ＴｉＣＮ結晶組織を完全に分断させてしまい、その結果、柱状縦長成長ＴｉＣＮ結晶組織が有する高い耐摩耗性を維持できなくなる。したがって、副層の層厚は、５〜３０ｎｍと定めた。
Layer thickness of sublayer in columnar vertically grown TiCN crystal structure:
When the sublayer has a thickness of 5 to 30 nm, the effect is remarkably exhibited. The reason for this is that if the thickness of the sublayer is less than 5 nm, the anisotropy of the fine TiCN layer of the sublayer is relaxed, and the function of the sublayer to enhance the toughness and the heat shielding effect is not sufficiently exhibited. On the other hand, if the thickness of the sub-layer exceeds 30 nm, the columnar vertically grown TiCN crystal structure is completely divided, and as a result, the high wear resistance of the columnar vertically grown TiCN crystal structure cannot be maintained. Therefore, the layer thickness of the sublayer was determined to be 5 to 30 nm.
副層の層厚方向１μｍあたりの層数：
さらに、前記副層は層厚方向１μｍあたりの最も好ましい層数を鋭意研究したところ１〜５層であることを見出した。その理由について解析すると、１層未満であると、前述した少なくとも１層のＴｉの炭窒化物層の異方性を緩和し、靭性および熱遮蔽効果を高めるという効果が十分に発揮されず、一方、５層を超えると柱状縦長成長ＴｉＣＮ結晶組織が有する高い耐摩耗性を維持できなくなる。したがって、副層は層厚方向１μｍあたり１〜５層存在するように構成することが好ましい。
Number of layers per 1 μm in the thickness direction of the sublayer:
Furthermore, when the said sublayer earnestly investigated the most preferable number of layers per 1 micrometer of layer thickness, it discovered that it was 1-5 layers. When the reason is analyzed, if it is less than one layer, the effect of relaxing the anisotropy of the at least one Ti carbonitride layer described above and enhancing the toughness and the heat shielding effect is not sufficiently exhibited, If it exceeds 5 layers, the high wear resistance of the columnar vertically grown TiCN crystal structure cannot be maintained. Therefore, the sub-layer is preferably configured so that there are 1 to 5 layers per 1 μm in the layer thickness direction.
柱状縦長成長ＴｉＣＮ結晶の最大粒子幅とアスペクト比：
また、前述のような本発明の下部層を構成する柱状縦長成長ＴｉＣＮ結晶の形状・サイズについても硬質被膜層の耐チッピング性、耐欠損性の向上という観点から鋭意研究した。その結果、最大粒子幅を５０〜２０００ｎｍとするとともに、前記最大粒子幅と膜厚方向の最大粒子長さとのアスペクト比を５〜５０とすることによって、前記の効果が著しく向上することを見出した。その理由を解析すると次のように説明することができる。すなわち、最大粒子幅が５０ｎｍよりも小さいと、長期間使用した際に耐摩耗性が低下する傾向があり、一方、２０００ｎｍを超えると、粒子の粗大化により耐チッピング性、耐欠損性が低下する傾向がある。したがって、柱状縦長成長ＴｉＣＮ結晶の最大粒子幅は、５０〜２０００ｎｍとすることがより好ましい。さらに、最大粒子幅と膜厚方向の最大粒子長さの比として定義されるアスペクト比が５より小さいと、柱状縦長成長ＴｉＣＮの特徴である耐摩耗性が低下する傾向があり、一方、５０を超えると、かえって靭性が低下し、耐チッピング性、耐欠損性が低下する傾向がある。したがって、柱状縦長成長ＴｉＣＮ結晶の最大粒子幅と膜厚方向の最大粒子長さとのアスペクト比は５〜５０とすることがより好ましい。
ここで、本発明における最大粒子幅と最大粒子長さとは、柱状縦長成長ＴｉＣＮ結晶の１つの粒子を計測したとき、粒子の幅（短辺）で最も大きい値を最大粒子幅と呼び、一方、粒子の高さ（長辺）で最も大きい値を最大粒子長さと呼ぶ。
Maximum grain width and aspect ratio of columnar vertically grown TiCN crystal:
In addition, the shape and size of the columnar vertically grown TiCN crystals constituting the lower layer of the present invention as described above were also intensively studied from the viewpoint of improving the chipping resistance and chipping resistance of the hard coating layer. As a result, it has been found that the above effect is remarkably improved by setting the maximum particle width to 50 to 2000 nm and the aspect ratio between the maximum particle width and the maximum particle length in the film thickness direction to 5 to 50. . If the reason is analyzed, it can be explained as follows. That is, if the maximum particle width is smaller than 50 nm, the wear resistance tends to decrease when used for a long period of time. On the other hand, if it exceeds 2000 nm, the chipping resistance and chipping resistance decrease due to particle coarsening. Tend. Therefore, the maximum particle width of the columnar vertically grown TiCN crystal is more preferably 50 to 2000 nm. Furthermore, if the aspect ratio defined as the ratio of the maximum particle width and the maximum particle length in the film thickness direction is smaller than 5, the wear resistance characteristic of the columnar vertically grown TiCN tends to be reduced, whereas 50 When it exceeds, toughness will fall on the contrary, there exists a tendency for chipping resistance and a fracture resistance to fall. Therefore, the aspect ratio between the maximum grain width of the columnar vertically grown TiCN crystal and the maximum grain length in the film thickness direction is more preferably 5-50.
Here, the maximum particle width and the maximum particle length in the present invention, when one particle of columnar vertically grown TiCN crystal is measured, the largest value of the particle width (short side) is called the maximum particle width, The largest value of the particle height (long side) is called the maximum particle length.
副層を構成する微粒ＴｉＣＮの形成：
本発明の副層を構成する微粒ＴｉＣＮは、通常の化学蒸着条件で成膜した下部層の形成過程の間に原料としてＴＤＭＡＴを用いた副層形成条件で化学蒸着法を行うことによって形成することができる。
すなわち、下記に示すような、通常の柱状縦長成長ＴｉＣＮの化学蒸着条件と副層形成条件を交互に行うことにより、柱状縦長成長ＴｉＣＮ結晶組織に微粒ＴｉＣＮからなる少なくとも２層以上の副層が形成される。
化学蒸着条件：
反応ガス組成（容量％）：
ＴｉＣｌ４：１．６〜２．０％、
ＣＨ３ＣＮ：０．６〜１．０％、
Ｎ２：２０％、
Ｈ２：残、
反応雰囲気圧力：５〜１０ｋＰａ、
反応雰囲気温度を：８００〜９４０℃、
副層形成条件：
反応ガス組成（容量％）：
ＴＤＭＡＴ（テトラキスジメチルアミノチタン）：０．１〜０．２％、
Ｎ２：５〜７％、
Ｈ２：残、
反応雰囲気圧力：５〜１０ｋＰａ、
反応雰囲気温度を：８００〜９４０℃、
ここで、微粒ＴｉＣＮからなる副層はＴＤＭＡＴを用いた副層形成条件により形成されるので、成膜中に副層形成条件による工程を行った回数が副層の層数に対応している。したがって、副層の層数、すなわち副層形成条件による工程を行った回数を下部層全体の層厚（μｍ）で除した値が、層厚方向１μｍあたりに存在する副層となる。
本発明の下部層を構成するＴｉ化合物層中の柱状縦長成長ＴｉＣＮ結晶組織の成長状態を模式的に表した図を図１に示す。
前記化学蒸着条件で形成された本発明の下部層を構成する柱状縦長成長ＴｉＣＮ結晶組織内に存在する前記副層形成条件で形成された微粒ＴｉＣＮからなる副層の存在形態の概略模式図を図２に示す。
Formation of fine TiCN constituting the sublayer:
The fine TiCN constituting the sublayer of the present invention is formed by performing chemical vapor deposition under the sublayer forming conditions using TDMAT as a raw material during the formation process of the lower layer formed under normal chemical vapor deposition conditions. Can do.
That is, by alternately performing the chemical vapor deposition conditions and sublayer formation conditions of normal columnar vertically grown TiCN as shown below, at least two or more sublayers made of fine grain TiCN are formed in the columnar vertically grown TiCN crystal structure. Is done.
Chemical vapor deposition conditions:
Reaction gas composition (volume%):
TiCl 4: 1.6~2.0%,
CH 3 CN: 0.6~1.0%,
N 2 : 20%
H 2 : remaining,
Reaction atmosphere pressure: 5 to 10 kPa,
Reaction atmosphere temperature: 800-940 ° C.
Sublayer formation conditions:
Reaction gas composition (volume%):
TDMAT (tetrakisdimethylaminotitanium): 0.1-0.2%
N 2: 5~7%,
H 2 : remaining,
Reaction atmosphere pressure: 5 to 10 kPa,
Reaction atmosphere temperature: 800-940 ° C.
Here, the sublayer made of fine TiCN is formed under the sublayer formation conditions using TDMAT, and therefore the number of times of performing the process according to the sublayer formation conditions during film formation corresponds to the number of sublayers. Therefore, the value obtained by dividing the number of sub-layers, that is, the number of times of performing the process according to the sub-layer formation conditions, by the layer thickness (μm) of the entire lower layer is the sub-layer existing per 1 μm in the layer thickness direction.
FIG. 1 schematically shows the growth state of the columnar vertically grown TiCN crystal structure in the Ti compound layer constituting the lower layer of the present invention.
FIG. 4 is a schematic diagram showing the existence form of a sublayer made of fine grain TiCN formed under the sublayer formation conditions existing in the columnar vertically grown TiCN crystal structure constituting the lower layer of the present invention formed under the chemical vapor deposition conditions. It is shown in 2.
本発明は、炭化タングステン基超硬合金または炭窒化チタン基サーメットで構成された工具基体の表面に硬質被覆層を設けた表面被覆切削工具において、硬質被覆層が下部層と上部層とからなるとともに、（ａ）下部層は、少なくとも１層のＴｉの炭窒化物層を含み、かつ、３〜２０μｍの合計平均層厚を有する１層または２層以上からなるＴｉ化合物層、（ｂ）上部層は、２〜２５μｍの平均層厚を有する酸化アルミニウム層、からなり、（ａ）の下部層を構成する少なくとも１層のＴｉの炭窒化物層は、柱状縦長成長ＴｉＣＮ結晶組織を有しており、その組織内に微粒ＴｉＣＮからなる副層が少なくとも２層以上、柱状縦長成長ＴｉＣＮ結晶組織を完全に分断せずに存在しており、該微粒ＴｉＣＮが粒状ＴｉＣＮ結晶相又はアモルファスＴｉＣＮ相若しくは粒状ＴｉＣＮ結晶相とアモルファスＴｉＣＮ相との混合相であることにより、微粒ＴｉＣＮの副層の存在によって、柱状縦長成長ＴｉＣＮ結晶組織に力が加わった際に、１つ１つの柱状縦長成長ＴｉＣＮ結晶にずれが生じるため、大きな靭性を生じることになる。また、ＴｉＣＮ層の異方性が緩和される結果、熱遮蔽効果が向上する。その結果、耐チッピング性、耐欠損性向上という効果が発揮され、長期の使用に亘ってすぐれた切削性能を発揮し、被覆工具の長寿命化が達成されるものである。 The present invention provides a surface-coated cutting tool having a hard coating layer on the surface of the configured tool substrate with tungsten carbide based cemented carbide or titanium carbonitride-based cermet, the hard coating layer is composed of a lower portion layer and the upper layer And (a) the lower layer includes at least one Ti carbonitride layer and has a total average layer thickness of 3 to 20 μm, and is composed of one or more Ti compound layers, (b) the upper portion The layer comprises an aluminum oxide layer having an average layer thickness of 2 to 25 μm, and at least one Ti carbonitride layer constituting the lower layer of (a) has a columnar vertically grown TiCN crystal structure In the structure, at least two or more sub-layers made of fine TiCN are present without completely dividing the columnar vertically grown TiCN crystal structure, and the fine TiCN is in a granular TiCN crystal phase or amorphous T By being a mixed phase of iCN phase or granular TiCN crystal phase and amorphous TiCN phase, when a force is applied to the columnar vertically grown TiCN crystal structure due to the presence of a sub-layer of fine TiCN, each columnar vertically elongated growth Since a shift occurs in the TiCN crystal, a large toughness is generated. Moreover, as a result of relaxing the anisotropy of the TiCN layer, the heat shielding effect is improved. As a result, an effect of improving chipping resistance and fracture resistance is exhibited, excellent cutting performance is exhibited over a long period of use, and a long tool life is achieved.
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.
原料粉末として、いずれも１〜３μｍの平均粒径を有するＷＣ粉末、ＴｉＣ粉末、ＺｒＣ粉末、ＶＣ粉末、ＴａＣ粉末、ＮｂＣ粉末、Ｃｒ3Ｃ2粉末、ＴｉＮ粉末およびＣｏ粉末を用意し、これら原料粉末を、表１に示される配合組成に配合し、さらにワックスを加えてアセトン中で２４時間ボールミル混合し、減圧乾燥した後、９８ＭＰａの圧力で所定形状の圧粉体にプレス成形し、この圧粉体を５Ｐａの真空中、１３７０〜１４７０℃の範囲内の所定の温度に１時間保持の条件で真空焼結し、焼結後、切刃部にＲ：０．０７ｍｍのホーニング加工を施すことによりＩＳＯ・ＣＮＭＧ１２０４０８に規定するインサート形状をもったＷＣ基超硬合金製の工具基体Ａ〜Ｅをそれぞれ製造した。 WC powder, TiC powder, ZrC powder, VC powder, TaC powder, NbC powder, Cr 3 C 2 powder, TiN powder and Co powder all having an average particle diameter of 1 to 3 μm are prepared as raw material powders. The powder was blended into the blending composition shown in Table 1, further added with wax, ball mill mixed in acetone for 24 hours, dried under reduced pressure, and then press-molded into a compact of a predetermined shape at a pressure of 98 MPa. The powder is sintered in a vacuum of 5 Pa at a predetermined temperature within a range of 1370 to 1470 ° C. for 1 hour, and after sintering, the cutting edge is subjected to a honing process of R: 0.07 mm. Thus, tool bases A to E made of a WC-base cemented carbide having an insert shape specified in ISO · CNMG120408 were manufactured.
また、原料粉末として、いずれも０．５〜２μｍの平均粒径を有するＴｉＣＮ（質量比でＴｉＣ／ＴｉＮ＝５０／５０）粉末、Ｍｏ2Ｃ粉末、ＺｒＣ粉末、ＮｂＣ粉末、ＴａＣ粉末、ＷＣ粉末、Ｃｏ粉末、およびＮｉ粉末を用意し、これら原料粉末を、表２に示される配合組成に配合し、ボールミルで２４時間湿式混合し、乾燥した後、９８ＭＰａの圧力で圧粉体にプレス成形し、この圧粉体を１．３ｋＰａの窒素雰囲気中、温度：１５４０℃に１時間保持の条件で焼結し、焼結後、切刃部分にＲ：０．０７ｍｍのホーニング加工を施すことによりＩＳＯ規格・ＣＮＭＧ１２０４０８のインサート形状をもったＴｉＣＮ基サーメット製の工具基体ａ〜ｅを形成した。 In addition, as raw material powders, TiCN (mass ratio TiC / TiN = 50/50) powder, Mo 2 C powder, ZrC powder, NbC powder, TaC powder, WC powder, all having an average particle diameter of 0.5 to 2 μm. Co powder and Ni powder are prepared, and these raw material powders are blended in the blending composition shown in Table 2, wet mixed by a ball mill for 24 hours, dried, and pressed into a compact at a pressure of 98 MPa. The green compact was sintered in a nitrogen atmosphere of 1.3 kPa at a temperature of 1540 ° C. for 1 hour, and after the sintering, the cutting edge portion was subjected to a honing process of R: 0.07 mm. Tool bases a to e made of TiCN-based cermet having an insert shape of standard / CNMG120408 were formed.
つぎに、これらの工具基体Ａ〜Ｅおよび工具基体ａ〜ｅの表面に、通常の化学蒸着装置を用い、
（ａ）硬質被覆層の下部層として、表３および表４に示される条件かつ表６に示される目標層厚（μｍ）でＴｉ化合物層を蒸着形成する。
（ｂ）この時、表４に示される条件でＴｉＣＮ層を成膜する際に、表４に示される反応ガス種別欄上段側の柱状縦長成長ＴｉＣＮ結晶組織形成条件と下段側の副層形成条件を交互に行いながらＴｉＣＮ層を蒸着形成することにより本発明被覆工具１〜１５を製造した。そして、下部層成膜中にＴＤＭＡＴを用いた副層形成条件による工程を行った回数を下部層の合計平均層厚（μｍ）で割ることによって、下部層における層厚方向１μｍあたりの副層の層数を求めた。
（ｃ）次いで、表３に示される条件かつ表６に示される目標層厚（μｍ）の酸化アルミニウム層からなる上部層を蒸着形成することにより、表６の本発明被覆工具１〜１５を作製した。
Next, a normal chemical vapor deposition apparatus is used on the surfaces of these tool bases A to E and tool bases a to e,
(A) As a lower layer of the hard coating layer, a Ti compound layer is formed by vapor deposition under the conditions shown in Tables 3 and 4 and the target layer thickness (μm) shown in Table 6.
(B) At this time, when the TiCN layer is formed under the conditions shown in Table 4, the columnar vertically grown TiCN crystal structure forming conditions on the upper side of the reaction gas type column and the sublayer forming conditions on the lower side shown in Table 4 The present coated tools 1 to 15 were manufactured by forming a TiCN layer by vapor deposition while alternately performing the above steps. Then, by dividing the number of times of performing the process under the sublayer formation condition using TDMAT during the lower layer formation by the total average layer thickness (μm) of the lower layer, the sublayer per 1 μm in the layer thickness direction of the lower layer The number of layers was determined.
(C) Next, the coated tools 1 to 15 of the present invention shown in Table 6 are prepared by vapor-depositing an upper layer composed of an aluminum oxide layer having the conditions shown in Table 3 and the target layer thickness (μm) shown in Table 6. did.
前記本発明被覆工具１〜１５の下部層を構成するＴｉＣＮ層について、走査型電子顕微鏡（倍率５００００倍）を用いて複数視野に亘って観察したところ、図２に示した膜構成模式図に示される柱状縦長成長ＴｉＣＮ結晶組織内に微粒ＴｉＣＮからなる副層が存在する膜構造が確認された。
さらに、前記本発明被覆工具１〜１５の下部層を構成するＴｉＣＮ層について、透過型電子顕微鏡（倍率２０００００倍）を用いて複数の視野に亘って観察したところ、前記微粒ＴｉＣＮは、粒状ＴｉＣＮ結晶相又はアモルファスＴｉＣＮ相若しくは粒状ＴｉＣＮ結晶相とアモルファスＴｉＣＮ相の混合相であることが確認された。
The TiCN layer constituting the lower layer of the coated tools 1 to 15 of the present invention was observed over a plurality of fields using a scanning electron microscope (magnification 50000 times), and shown in the schematic diagram of the film configuration shown in FIG. Thus, a film structure in which a sub-layer made of fine TiCN exists in the columnar vertically grown TiCN crystal structure was confirmed.
Further, when the TiCN layer constituting the lower layer of the coated tools 1 to 15 of the present invention was observed over a plurality of fields using a transmission electron microscope (magnification 200000 times), the fine TiCN was a granular TiCN crystal. It was confirmed that the phase was a mixed phase of an amorphous TiCN phase or a granular TiCN crystal phase and an amorphous TiCN phase.
また、比較の目的で、工具基体Ａ〜Ｅおよび工具基体ａ〜ｅの表面に、表３および表５に示される条件かつ表７に示される目標層厚（μｍ）で本発明被覆工具１〜１５と同様に、硬質被覆層の下部層としてのＴｉ化合物層を蒸着形成した。この時には、副層形成条件を行わずに、柱状縦長成長ＴｉＣＮ結晶組織を有するＴｉ化合物層を形成した。次いで、硬質被覆層の上部層として、表３に示される条件かつ表７に示される目標層厚（μｍ）で酸化アルミニウム層からなる上部層を蒸着形成することにより、表７の比較被覆工具１〜１５を作製した。 For comparison purposes, the coated tools 1 to 5 of the present invention are applied to the surfaces of the tool bases A to E and the tool bases a to e under the conditions shown in Tables 3 and 5 and the target layer thickness (μm) shown in Table 7. Similarly to 15, a Ti compound layer as a lower layer of the hard coating layer was formed by vapor deposition. At this time, a Ti compound layer having a columnar vertically grown TiCN crystal structure was formed without performing sublayer formation conditions. Next, as an upper layer of the hard coating layer, a comparative coating tool 1 in Table 7 was formed by vapor-depositing an upper layer made of an aluminum oxide layer under the conditions shown in Table 3 and the target layer thickness (μm) shown in Table 7. ~ 15 were made.
また、本発明被覆工具１〜１５および比較被覆工具１〜１５の各構成層の平均層厚を、走査型電子顕微鏡（倍率５０００倍）を用いて測定したところ、いずれも表６および表７に示される目標層厚と実質的に同じ平均層厚を示した。
また、本発明被覆工具１〜１５および比較被覆工具１〜１５については、同じく走査型電子顕微鏡（倍率５０００倍）を用いて、上部層のＴｉＣＮ層を構成する柱状縦長成長ＴｉＣＮ結晶の最大粒子幅及び膜厚方向の最大粒子長さを、工具基体と水平方向に長さ合計１０μｍの範囲に存在する柱状縦長成長ＴｉＣＮ結晶について測定し、最大粒子幅及び膜厚方向の最大粒子長さの比からアスペクト比を求めた。
また、本発明被覆工具１〜１５については、同じく走査型電子顕微鏡（倍率５００００倍）を用いて、下部層のＴｉＣＮ層に存在する微粒ＴｉＣＮからなる副層を工具基体と垂直方向はＴｉＣＮ層の層厚分の厚さに亘って、一方、工具基体と水平方向は長さ合計１０μｍに亘って測定し、下部層中に存在する全ての副層について層厚を求め、その平均値として副層の平均層厚を求めた。
Moreover, when the average layer thickness of each component layer of this invention coated tool 1-15 and comparative coated tool 1-15 was measured using the scanning electron microscope (5000-times multiplication factor), all are shown in Table 6 and Table 7. It showed an average layer thickness substantially the same as the target layer thickness shown.
Moreover, about this invention coated tool 1-15 and comparative coated tool 1-15, the maximum particle width of the columnar vertically grown TiCN crystal which comprises the TiCN layer of an upper layer is similarly used for a scanning electron microscope (magnification 5000 times). And the maximum grain length in the film thickness direction was measured for the columnar vertically grown TiCN crystal existing in the range of a total length of 10 μm in the horizontal direction with respect to the tool base. From the ratio of the maximum grain width and the maximum grain length in the film thickness direction The aspect ratio was determined.
In addition, for the coated tools 1 to 15 of the present invention, using a scanning electron microscope (magnification of 50000 times), a sub-layer made of fine TiCN existing in the TiCN layer of the lower layer is placed in the direction perpendicular to the tool base in the TiCN layer. On the other hand, the tool substrate and the horizontal direction are measured over a total length of 10 μm over the thickness of the layer thickness, and the layer thickness is obtained for all sublayers present in the lower layer, and the average value of the sublayers is obtained. The average layer thickness was determined.
つぎに、前記本発明被覆工具１〜１５および比較被覆工具１〜１５について、表８に示す条件で切削加工試験を実施し、いずれの切削試験でも切刃の逃げ面摩耗幅を測定した。
表９に、この測定結果を示した。
Next, with respect to the inventive coated tools 1-15 and comparative coated tools 1-15, a cutting test was performed under the conditions shown in Table 8, and the flank wear width of the cutting edge was measured in any cutting test.
Table 9 shows the measurement results.
表６および表９に示される結果から、本発明の被覆工具は、硬質被覆層の下部層を構成するＴｉＣＮ層が、柱状縦長成長ＴｉＣＮ結晶組織を有しており、その組織内に微粒ＴｉＣＮからなる副層が少なくとも２層以上存在していることにより、靱性が向上し、熱伝導率が抑制され熱遮蔽効果が向上するため、鋼や鋳鉄等の高熱発生を伴い、しかも、切れ刃に断続的・衝撃的高負荷が作用する高速断続切削加工に用いた場合でも、耐チッピング性、耐欠損性にすぐれ、その結果、長期の使用に亘ってすぐれた耐摩耗性を発揮することが明らかである。 From the results shown in Table 6 and Table 9, in the coated tool of the present invention, the TiCN layer constituting the lower layer of the hard coating layer has a columnar vertically grown TiCN crystal structure, and the fine TiCN layer is formed in the structure. Because there are at least two or more sublayers, the toughness is improved, the thermal conductivity is suppressed, and the heat shielding effect is improved, resulting in high heat generation of steel, cast iron, etc. Even when used for high-speed interrupted cutting with high impact and impact, it is clear that it has excellent chipping resistance and fracture resistance, and as a result, it exhibits excellent wear resistance over a long period of use. is there.
これに対して、硬質被覆層の下部層を構成するＴｉＣＮ層に微粒ＴｉＣＮからなる副層が存在していない比較被覆工具１〜１５については、高熱発生を伴い、しかも、切れ刃に断続的・衝撃的高負荷が作用する高速断続切削加工に用いた場合、チッピング、欠損等の発生により短時間で寿命にいたることが明らかである。 On the other hand, the comparative coated tools 1 to 15 in which the sublayer made of fine TiCN does not exist in the TiCN layer constituting the lower layer of the hard coating layer is accompanied by high heat generation, and is intermittently applied to the cutting edge. When used in high-speed interrupted cutting where an impact high load acts, it is clear that chipping, chipping, etc. will lead to short life.
前述のように、本発明の被覆工具は、例えば、鋼や鋳鉄等の高熱発生を伴い、かつ、切れ刃に断続的・衝撃的高負荷が作用する高速断続切削加工において、すぐれた耐チッピング性、耐欠損性を発揮し、使用寿命の延命化を可能とするものであるが、高速断続切削加工条件ばかりでなく、高速切削加工条件、高切込み、高送りの高速重切削加工条件等で使用することも勿論可能である。 As described above, the coated tool of the present invention has excellent chipping resistance in high-speed intermittent cutting with high heat generation such as steel and cast iron and intermittent and impact high load acting on the cutting edge. Demonstrate fracture resistance and extend the service life, but not only for high-speed interrupted cutting conditions, but also for high-speed cutting conditions, high cutting depth, high-feed, high-speed heavy cutting conditions, etc. Of course, it is also possible.
Claims (2)
前記硬質被覆層が下部層と上部層とからなるとともに、
（ａ）前記下部層は、少なくとも１層のＴｉの炭窒化物層を含み、かつ、３〜２０μｍの合計平均層厚を有する１層または２層以上からなるＴｉ化合物層、
（ｂ）前記上部層は、２〜２５μｍの平均層厚を有する酸化アルミニウム層、
からなり、
前記（ａ）の下部層を構成する少なくとも１層のＴｉの炭窒化物層は、柱状縦長成長ＴｉＣＮ結晶組織を有しており、その組織内に微粒ＴｉＣＮからなる副層が少なくとも２層以上、柱状縦長成長ＴｉＣＮ結晶組織を完全に分断せずに存在しており、該微粒ＴｉＣＮが粒状ＴｉＣＮ結晶相又はアモルファスＴｉＣＮ相若しくは粒状ＴｉＣＮ結晶相とアモルファスＴｉＣＮ相との混合相であり、前記柱状縦長成長ＴｉＣＮ結晶の最大粒子幅は５０〜２０００ｎｍ、前記最大粒子幅と膜厚方向の最大粒子長さとのアスペクト比が５〜５０であり、前記微粒ＴｉＣＮからなる副層の層厚が、５ｎｍ〜３０ｎｍ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 is provided on the surface of a tool base composed of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet,
Together with the hard coating layer is composed of a lower portion layer and the upper layer,
(A) The lower layer includes at least one Ti carbonitride layer, and has a total average layer thickness of 3 to 20 μm, a Ti compound layer composed of one layer or two or more layers,
(B) the upper layer is an aluminum oxide layer having an average layer thickness of 2 to 25 μm;
Consists of
The at least one Ti carbonitride layer constituting the lower layer of (a) has a columnar vertically grown TiCN crystal structure, and at least two or more sublayers made of fine TiCN in the structure, The columnar vertically grown TiCN crystal structure exists without being completely divided, and the fine TiCN is a granular TiCN crystal phase or an amorphous TiCN phase or a mixed phase of a granular TiCN crystal phase and an amorphous TiCN phase, and the columnar vertically grown The maximum particle width of the TiCN crystal is 50 to 2000 nm, the aspect ratio of the maximum particle width and the maximum particle length in the film thickness direction is 5 to 50, and the layer thickness of the sublayer made of the fine TiCN is 5 nm to 30 nm. A surface-coated cutting tool characterized in that there is.
2. The surface coating according to claim 1, wherein there are 1 to 5 sublayers of fine TiCN existing in at least one Ti carbonitride layer constituting the lower layer per 1 [mu] m in the layer thickness direction. Cutting tools.
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