JP2008264971A - Hard coat cutting tool - Google Patents
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Abstract
Description
本発明は、金属材料等の切削加工に使用される硬質皮膜切削工具に関する。 The present invention relates to a hard film cutting tool used for cutting a metal material or the like.
近年、切削加工の高速化や乾式化、そして被加工物の高硬度化に伴い、ＴｉＡｌＮ皮膜で被覆された切削工具に替わる、より耐酸化性と長寿命を備えた被覆切削工具として、ＴｉＮ、ＴｉＡｌＮ等にＳｉを添加したＳｉ含有皮膜を被覆した切削工具の採用が検討されている。
このような被覆切削工具として例えば特許文献１に記載されたものがある。この被覆切削工具は切削工具の母材上にＴｉＡｌに第三元素としてＢ，Ｓｉ，Ｖ，Ｃｒ，Ｙ，Ｚｒ，Ｎｂ，Ｍｏ，Ｈｆ，Ｔａ，Ｗの１種または２種以上の１０原子％未満で構成される窒化物等からなる皮膜を被覆し、その直上にＴｉＮにＳｉを添加した皮膜を被覆した硬質皮膜層を形成している。これによって、耐酸化性と耐摩耗性を向上させて乾式高速切削加工で長寿命を発揮できるようにしている。
この場合、第三元素が金属成分のみを１０原子％以上添加すると硬質皮膜がもろくなり母材に対する密着性も悪くなるとしている。
In recent years, TiN, a coated cutting tool with higher oxidation resistance and longer life, which replaces a cutting tool coated with a TiAlN film as the cutting speed is increased and dry, and the hardness of the workpiece is increased. Adoption of a cutting tool coated with a Si-containing film obtained by adding Si to TiAlN or the like has been studied.
An example of such a coated cutting tool is described in Patent Document 1. This coated cutting tool has 10 atomic% of one or more of B, Si, V, Cr, Y, Zr, Nb, Mo, Hf, Ta, and W as the third element on the base material of the cutting tool. A hard film layer is formed by coating a film made of nitride or the like composed of less than this, and coating a film obtained by adding Si to TiN directly thereon. As a result, the oxidation resistance and the wear resistance are improved, and a long life can be exhibited by dry high-speed cutting.
In this case, if the third element adds only 10 atomic% or more of the metal component, the hard film becomes brittle and the adhesion to the base material also deteriorates.
また、特許文献２では切削工具の基体に、Ｓｉ含有硬質皮膜と非Ｓｉ含有硬質皮膜とからなる２層の硬質皮膜を被覆してなり、Ｓｉ含有硬質皮膜は高Ｓｉ濃度領域相と低Ｓｉ濃度領域相とを含有している。Ｓｉ含有硬質皮膜はマトリックスとなる結晶質に高Ｓｉ濃度領域相を偏析させた組成偏析多結晶体とされている。
そして、高Ｓｉ濃度領域相をアモルファス相として結晶質を偏析させることで密着性と皮膜の強度を上げているとしている。
また、特許文献３では、切削工具の基体上にＳｉ含有硬質皮膜を被覆してなり、このＳｉ含有硬質皮膜は、ＴｉＡｌＳｉ系皮膜の同一相内に高Ｓｉ濃度領域と低Ｓｉ濃度領域とを有する相を設けている。この場合、高Ｓｉ濃度領域を有する相はアモルファス相であり、低Ｓｉ濃度領域を有する相は結晶質である。高Ｓｉ濃度領域を有する相を皮膜内に設けることによって皮膜内に残留する圧縮応力を低減させて、高硬度と耐酸化性を改善したとしている。
The adhesion and the strength of the film are increased by segregating the crystalline material with the high Si concentration region phase as an amorphous phase.
Further, in Patent Document 3, a Si-containing hard film is coated on a base of a cutting tool, and this Si-containing hard film has a high Si concentration region and a low Si concentration region in the same phase of the TiAlSi-based film. There is a phase. In this case, the phase having a high Si concentration region is an amorphous phase, and the phase having a low Si concentration region is crystalline. It is said that by providing a phase having a high Si concentration region in the film, the compressive stress remaining in the film is reduced, and the high hardness and oxidation resistance are improved.
しかしながら、特許文献１に記載され硬質皮膜では、ＴｉＡｌＮ系皮膜とＴｉＳｉＮ系皮膜を交互に積層させることで結晶構造に整合性をもたせ、ＴｉＳｉＮの耐摩耗性、耐酸化性を維持したまま密着性も向上させるとしているが、工具によっては各皮膜の膜厚を均一にすることが困難であり、整合性が十分に取れない膜厚で二層以上積層される部分が発生したり、ＴｉＳｉＮの耐酸化性が十分に発揮されない膜厚で積層される部分ができる可能性があり、工具寿命にばらつきが生じてしまう欠点があった。
特に、ＴｉＡｌＮ系皮膜側のＡｌの量を増加させたり第３元素を加えてＴｉＡｌＮ系皮膜側の耐酸化性を向上させた皮膜ではこの傾向が顕著にみられ、単純にＴｉＡｌＮ皮膜にＴｉＳｉＮ皮膜を成膜したものに比べて性能が低下することがあるという欠点があった。
また、特許文献２と特許文献３に記載された皮膜では、この皮膜の被覆製造に際して、Ｓｉ濃度の異なる皮膜を同一層内に形成するために、パルスバイアスを使用し、基体に印加するバイアス電圧は負バイアス電圧と正バイアス電圧を周期的に変化させながら成膜を行う必要があった。
そのため、このような電源を使用すると、量産用のコーティング装置では電源が非常に高価なものになってしまうため、実用化が困難であった。
However, in the hard coating described in Patent Document 1, the TiAlN-based coating and the TiSiN-based coating are alternately laminated to make the crystal structure consistent, and the adhesion is maintained while maintaining the wear resistance and oxidation resistance of TiSiN. Although it is said to improve, it is difficult to make the thickness of each film uniform depending on the tool, and there are portions where two or more layers are laminated with a film thickness that is not sufficiently consistent, or oxidation resistance of TiSiN There is a possibility that a portion to be laminated with a film thickness that does not sufficiently exhibit the properties may be formed, and there is a disadvantage that the tool life varies.
In particular, this tendency is remarkable in the film in which the amount of Al on the TiAlN-based film side is increased or the oxidation resistance on the TiAlN-based film side is improved by adding a third element, and a TiSiN film is simply applied to the TiAlN film. There was a drawback that the performance may be lower than that of the film formed.
In the coatings described in Patent Document 2 and Patent Document 3, a bias voltage is applied to the substrate using a pulse bias in order to form a coating having a different Si concentration in the same layer when the coating is manufactured. It was necessary to perform film formation while periodically changing the negative bias voltage and the positive bias voltage.
For this reason, when such a power supply is used, the power supply becomes very expensive in a mass production coating apparatus, and it is difficult to put it to practical use.
本発明は、このような実情に鑑みて、切削加工の高速化、乾式化、被加工物の高硬度化による摩耗を抑制することができて密着性と耐熱性に優れた被覆切削工具を提供することを目的とする。 In view of such circumstances, the present invention provides a coated cutting tool that can suppress wear due to high-speed cutting, dry processing, and high hardness of a workpiece and has excellent adhesion and heat resistance. The purpose is to do.
本発明による硬質皮膜切削工具は、工具の基材の表面に硬質被膜を積層して形成された硬質皮膜切削工具であって、硬質皮膜は基材上に形成されて被覆するＡ層と該Ａ層の直上に形成されるＢ層とを有しており、Ａ層はＴｉＡｌＣｒの窒化物、酸窒化物、炭窒化物または酸炭窒化物のＳｉ非含有皮膜であって、立方晶からなる微細な柱状晶で構成されていて該柱状晶の成長方向に略直交する方向の各柱状晶の幅が３００ｎｍ以下に形成され、Ｂ層はＳｉＴｉの窒化物を主体としてなるＳｉ含有皮膜であることを特徴とする。
本発明によれば、Ａ層をＴｉＡｌＣｒの窒化物、酸窒化物、炭窒化物または酸炭窒化物のＳｉ非含有皮膜で形成することで高い硬度と良好な耐酸化性が得られ、しかも立方晶で幅が３００ｎｍ以下の微細で緻密な柱状晶の結晶構造を形成するので、その上に形成されるＢ層はＡ層の微細な結晶構造に倣ってエピタキシャル成長が促進されてＳｉの偏析がない微細で緻密なＳｉＴｉ固溶体の結晶構造となり、密着性と耐摩耗性が高い。
The hard film cutting tool according to the present invention is a hard film cutting tool formed by laminating a hard film on the surface of a base material of the tool, and the hard film is formed on the base material and coated with the A layer and the A layer. B layer formed immediately above the layer, and the A layer is a Ti-AlCr nitride, oxynitride, carbonitride or oxycarbonitride non-Si-containing film, and has a fine cubic structure. The width of each columnar crystal in a direction substantially orthogonal to the growth direction of the columnar crystal is formed to be 300 nm or less, and the B layer is a Si-containing film mainly composed of a nitride of SiTi. Features.
According to the present invention, the layer A is formed of a TiAlCr nitride, oxynitride, carbonitride, or oxycarbonitride non-Si-containing film, so that high hardness and good oxidation resistance can be obtained. Since the crystal structure of a fine and dense columnar crystal with a width of 300 nm or less is formed in the crystal, the B layer formed thereon is promoted by epitaxial growth following the fine crystal structure of the A layer, and there is no segregation of Si It has a fine and dense crystal structure of SiTi solid solution, and has high adhesion and wear resistance.
また、Ｂ層におけるＳｉ含有皮膜は、立方晶からなる微細な柱状晶で構成されていて該柱状晶の成長方向に略直交する方向の各柱状晶の幅が５０ｎｍ以下に形成されている。
Ａ層が微細で緻密な結晶構造であることによって、Ｂ層も立方晶からなる幅５０ｎｍ以下の更に微細で緻密な柱状晶による結晶構造となり、耐酸化性と耐摩耗性が高く長寿命になる。
Further, the Si-containing film in the B layer is composed of fine columnar crystals composed of cubic crystals, and the width of each columnar crystal in a direction substantially perpendicular to the growth direction of the columnar crystals is formed to be 50 nm or less.
Due to the fine and dense crystal structure of the A layer, the B layer also has a fine and dense columnar crystal structure with a width of 50 nm or less made of cubic crystals, and has high oxidation resistance and wear resistance and a long life. .
また、Ａ層の組成ＴｉａＡｌｂＣｒｃにおける金属成分の成分比ａ，ｂ，ｃは原子比で、
０．１≦ａ≦０．３５、
０．４５≦ｂ≦０．７、
０．１≦ｃ≦０．３５、
ａ＋ｂ＋ｃ＝１
であることを特徴とする。
Ａｌが４５原子％から７０原子％とすることで立方晶の結晶構造になり、ＴｉとＣｒの原子比をバランスさせることで柱状晶の幅を微細にできる。第３元素のＣｒが１０原子％以上であっても密着性が良好になる。
また、Ａ層は、Ｘ線回折において、強度が
０．５＜Ｉ（２００）／Ｉ（１１１）＜３、
Ｉ（２００）＞Ｉ（２２０）、
Ｉ（１１１）＞Ｉ（２２０）、
を満たした立方晶構造である。
In addition, the component ratios a, b, and c of the metal component in the composition TiaAlbCrc of the A layer are atomic ratios,
0.1 ≦ a ≦ 0.35,
0.45 ≦ b ≦ 0.7,
0.1 ≦ c ≦ 0.35,
a + b + c = 1
It is characterized by being.
When the Al content is 45 atomic% to 70 atomic%, a cubic crystal structure is obtained, and by balancing the atomic ratio of Ti and Cr, the width of the columnar crystal can be made fine. Even when the third element Cr is 10 atomic% or more, the adhesion is improved.
The A layer has an intensity of 0.5 <I (200) / I (111) <3 in X-ray diffraction,
I (200)> I (220),
I (111)> I (220),
Is a cubic structure satisfying
また、Ｂ層の組成ＳｉｘＴｉ（１−ｘ）における金属成分の成分比ｘは原子比で
０．１≦ｘ≦０．３
であることを特徴とする。
ここで、Ｓｉが１０原子％から３０原子％の範囲内で柱状晶の幅が十分微細でＳｉの偏析のない結晶構造を形成でき、１０原子％未満では柱状晶の幅が大きくなり易く、３０原子％を越えるとアモルファス相が柱状晶の粒界中に形成され密着性と耐摩耗性が低下してしまう。
また、Ａ層とＢ層からなる硬質皮膜のＸ線回折において、回折パターンの強度が、
Ｉ（２００）／Ｉ（１１１）＞２
Ｉ（２００）＞Ｉ（２２０）、
Ｉ（１１１）＞Ｉ（２２０）、
を満たした立方晶構造である。
Further, the component ratio x of the metal component in the composition SixTi ( 1- x) of the B layer is an atomic ratio of 0.1 ≦ x ≦ 0.3.
It is characterized by being.
Here, a crystal structure in which the width of the columnar crystals is sufficiently fine and Si is not segregated can be formed when Si is in the range of 10 atomic% to 30 atomic%. When the Si content is less than 10 atomic%, the width of the columnar crystals tends to be large. If the atomic percentage is exceeded, an amorphous phase is formed in the grain boundaries of the columnar crystals, and adhesion and wear resistance are reduced.
Moreover, in the X-ray diffraction of the hard film consisting of the A layer and the B layer, the intensity of the diffraction pattern is
I (200) / I (111)> 2
I (200)> I (220),
I (111)> I (220),
Is a cubic structure satisfying
また、Ａ層の膜厚をＴａとし、Ｂ層の膜厚をＴｂとすると、Ａ層とＢ層の膜厚比率は
３≧Ｔｂ／Ｔａ≧０．７
であり、Ａ層とＢ層の膜厚（Ｔａ＋Ｔｂ）が０．５μｍ以上１０μｍ以下であることが好ましい。
この範囲内でＢ層はＳｉの偏析のないアモルファス相のない結晶構造を形成でき、密着性と耐摩耗性を向上できる。
また、Ｂ層の直上に、金属元素として少なくともＣｒとＡｌを含むと共に非金属元素として少なくともＮを含むＣｒＡｌ系被膜を０．１μｍ以上０．８μｍ以下の膜厚で被覆して積層してなることが好ましい。
これによって切削に伴う刃先温度の上昇に耐性を持たせると共に、高硬度のＢ層よりも低硬度であるために刃先への衝撃緩和効果を持たせて性能を向上させる。
Further, when the thickness of the A layer is Ta and the thickness of the B layer is Tb, the thickness ratio of the A layer and the B layer is 3 ≧ Tb / Ta ≧ 0.7
The film thickness (Ta + Tb) of the A layer and the B layer is preferably 0.5 μm or more and 10 μm or less.
Within this range, the B layer can form a crystal structure without Si segregation and without an amorphous phase, and can improve adhesion and wear resistance.
Further, a CrAl-based film containing at least Cr and Al as metallic elements and at least N as nonmetallic elements is coated and laminated with a film thickness of 0.1 μm or more and 0.8 μm or less immediately above the B layer. Is preferred.
As a result, resistance to an increase in the temperature of the cutting edge due to cutting is given, and since the hardness is lower than that of the high-hardness B layer, an impact mitigating effect on the cutting edge is given to improve performance.
また、Ｂ層のＳｉ濃度分配が、エネルギー分散型蛍光Ｘ線分析における０．１７μｍ２の面積内で均一に分散していることが好ましい。
また、Ｂ層の電子線回折が結晶質のみで回折されることが好ましい。
Moreover, it is preferable that the Si concentration distribution of the B layer is uniformly dispersed within an area of 0.17 μm 2 in energy dispersive X-ray fluorescence analysis.
Moreover, it is preferable that the electron beam diffraction of B layer is diffracted only by crystalline substance.
本発明による硬質皮膜切削工具によれば、Ａ層を緻密で微細なＳｉ非含有被膜の結晶構造に形成することで、その上に積層するＢ層も更に微細で緻密な結晶構造に形成できてＳｉの偏析を抑制して耐酸化性と密着性を向上でき、切削加工における高速化、乾式化、被加工物の高硬度化による摩耗を抑制できて長寿命を得られ、生産性向上並びにコスト低減に有効である。 According to the hard coating cutting tool according to the present invention, by forming the A layer into a fine and fine crystal structure of the Si-free coating, the B layer laminated thereon can also be formed into a fine and dense crystal structure. Suppresses the segregation of Si and improves oxidation resistance and adhesion. It can reduce wear due to high-speed and dry machining, and high hardness of the workpiece, resulting in a long life, improving productivity and cost. Effective for reduction.
以下、本発明の実施の形態について図１乃至図６に沿って詳述する。図１は硬質皮膜のＡ層の画像を示すもので（ａ）は実施形態によるＡ層の画像、（ｂ）は従来例によるＡ層の画像、図２はＡ層における柱状晶の幅を示す図、図３は実施形態によるＢ層の画像、図４はＢ層のＥＤＸマッピング結果画像の図で（ａ）はＳＴＥＭ像、（ｂ）はＳｉ組成像、（ｃ）はＮ組成像、（ｄ）はＴｉ組成像、図５（ａ）〜（ｆ）はＢ層についてＴＥＭによる電子線回折像を示す図、図６はＡ層が立方晶構造であることを裏付けるＸ線回折の強度分布図である。
本実施形態においては、工具として例えばボールエンドミル等の切削工具を用いて、切削工具を基材としてその基材の上に、硬質皮膜としてＡ層とＢ層の二層を被覆したものである。図１は透過型電子顕微鏡（ＴＥＭ）で３００００倍の倍率で撮影したＡ層の側断面画像である。
切削工具の基材として例えば超硬合金、高速度鋼またはサーメットを用いる。そして基材の表面には下層としてＡ層を被覆し、Ａ層の直上に上層としてＢ層を被覆する。
図１（ａ）に示すＡ層は、例えばＴｉａＡｌｂＣｒｃの窒化物からなるＳｉを含有しないＳｉ非含有皮膜で構成される。Ｓｉ非含有皮膜はＴｉａＡｌｂＣｒｃの窒化物でなくてもよく、炭素Ｃや酸素Ｏが不可避的に含まれ得ることを考慮してＴｉａＡｌｂＣｒｃの酸窒化物、炭窒化物、酸炭窒化物のいずれかであってもよい。Ａ層はＴｉとＡｌとＣｒとＮ等の固溶体からなる結晶質とされ、Ｂ層との積層方向に成長する極微細な幅の柱状晶からなる粒が緻密に配列されて構成されている。なお、これら柱状晶は立方晶で構成されている。
Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. FIG. 1 shows an image of the A layer of the hard coating, where (a) shows the image of the A layer according to the embodiment, (b) shows the image of the A layer according to the conventional example, and FIG. 2 shows the width of the columnar crystals in the A layer. FIG. 3 is an image of a B layer according to the embodiment, FIG. 4 is a diagram of an EDX mapping result image of the B layer, (a) is a STEM image, (b) is an Si composition image, (c) is an N composition image, ( d) is a Ti composition image, FIGS. 5A to 5F are diagrams showing electron diffraction images by TEM for the B layer, and FIG. 6 is an intensity distribution of X-ray diffraction confirming that the A layer has a cubic structure. FIG.
In this embodiment, for example, a cutting tool such as a ball end mill is used as a tool, and the cutting tool is used as a base material, and the base material is coated with two layers of a layer A and a layer B as a hard film. FIG. 1 is a side cross-sectional image of layer A taken at a magnification of 30000 times with a transmission electron microscope (TEM).
For example, cemented carbide, high speed steel or cermet is used as the base material of the cutting tool. The surface of the base material is coated with the A layer as a lower layer, and the B layer is coated as an upper layer directly on the A layer.
The layer A shown in FIG. 1 (a) is composed of a Si-free coating that does not contain Si, for example, made of a nitride of TiaAlbCrc. The Si-free coating may not be a nitride of TiaAlbCrc, and in consideration of the fact that carbon C and oxygen O may be inevitably contained, any of oxynitride, carbonitride, and oxycarbonitride of TiaAlbCrc There may be. The A layer is made of a crystalline material made of a solid solution such as Ti, Al, Cr, and N, and is composed of finely arranged grains made of columnar crystals having a very fine width that grow in the stacking direction with the B layer. These columnar crystals are composed of cubic crystals.
ここで、柱状晶の幅は、図２に示すＡ層の任意の側断面位置において、緻密に配列された棒状の柱状晶の隣接する柱状晶との間で、柱状晶の成長方向の任意位置での成長方向に略直交する方向の幅ｗで測定され、この幅は３００ｎｍ以下、好ましくは２００ｎｍ以下、更に好ましくは１００ｎｍ以下とされている。
なお、本実施形態における柱状晶の幅ｗは、Ａ層の硬質皮膜の側断面において緻密に配列されている柱状晶間の幅であり、しかも成長（長手）方向で幅の大きさが変化しているため、必ずしも任意位置における柱状晶の直径を示すものではない。
Here, the width of the columnar crystal is an arbitrary position in the growth direction of the columnar crystal between the adjacent columnar crystals of the rod-shaped columnar crystals arranged densely at an arbitrary side cross-sectional position of the layer A shown in FIG. The width w is measured in a direction substantially perpendicular to the growth direction at, and this width is 300 nm or less, preferably 200 nm or less, more preferably 100 nm or less.
In addition, the width w of the columnar crystals in the present embodiment is a width between the columnar crystals densely arranged in the side cross section of the hard coating of the A layer, and the width changes in the growth (longitudinal) direction. Therefore, it does not necessarily indicate the diameter of the columnar crystal at an arbitrary position.
また、Ａ層におけるＳｉ非含有皮膜のＴｉａＡｌｂＣｒｃにおいて、ａ，ｂ，ｃは各金属元素の成分比を示すものであり、次式のように規定されている。
０．１≦ａ≦０．３５、
０．４５≦ｂ≦０．７、
０．１≦ｃ≦０．３５、
ａ＋ｂ＋ｃ＝１
ここで、Ａ層の粒（柱状晶）の幅ｗはＡ層中に存在するＡｌ量により大きく左右される。Ａｌ量が４５原子％以下では粒の幅が大きくなり、７０原子％以上では六方晶が形成され、耐摩耗性、密着性が劣る。そのため、Ａｌは４５原子％〜７０原子％の範囲内に設定することが好ましい。
なお、本実施形態において、組成ＴｉＡｌＮ、ＣｒＡｌＮでも本実施形態によるものと上記同様の効果がみられるが、一般的に硬度の高いＴｉＡｌＮと耐酸化性の良好なＣｒＡｌＮの両方の利点を生かしたＴｉＡｌＣｒＮを使用することが好ましい。
その際のＴｉＡｌＣｒＮの組成比で、Ｔｉ、Ｃｒはそれぞれ１０原子％〜３５原子％の範囲に設定することが好ましい。ＴｉとＣｒのいずれかが３５原子％を越えるとＴｉＡｌＮ、ＣｒＡｌＮのいずれかの特性に偏ってしまう。粒の幅に関しても、Ｔｉ、Ｃｒいずれか一方が３５原子％を越えて組成の偏りができると、粒の幅が微細ではなくなる。一方、Ｔｉ、Ｃｒのいずれかが１０原子％未満になると、やはりＴｉＡｌＮまたはＣｒＡｌＮのいずれかの特性に偏ってしまう不具合がある。また、Ｔｉ、Ｃｒの両方が１０原子％未満になると皮膜硬度と耐熱性が著しく低下し、切削工具向けの硬質皮膜として十分に機能しないという不具合が発生する。
Further, in TiaAlbCrc of the Si-free film in the A layer, a, b, and c indicate component ratios of the respective metal elements, and are defined by the following equations.
0.1 ≦ a ≦ 0.35,
0.45 ≦ b ≦ 0.7,
0.1 ≦ c ≦ 0.35,
a + b + c = 1
Here, the width w of the grains (columnar crystals) of the A layer greatly depends on the amount of Al present in the A layer. When the Al content is 45 atomic% or less, the grain width becomes large, and when it is 70 atomic% or more, hexagonal crystals are formed, and the wear resistance and adhesion are inferior. Therefore, Al is preferably set within the range of 45 atomic% to 70 atomic%.
In this embodiment, the composition TiAlN and CrAlN have the same effects as those of the present embodiment, but generally TiAlCrN taking advantage of both high hardness TiAlN and good oxidation resistance CrAlN. Is preferably used.
In this case, Ti and Cr are preferably set in a range of 10 atomic% to 35 atomic% in the composition ratio of TiAlCrN. If either Ti or Cr exceeds 35 atomic%, the characteristics tend to be either TiAlN or CrAlN. Regarding the grain width, if either Ti or Cr exceeds 35 atomic% and the composition is biased, the grain width is not fine. On the other hand, when either Ti or Cr is less than 10 atomic%, there is a problem that the characteristic is biased to either TiAlN or CrAlN. Moreover, when both Ti and Cr are less than 10 atomic%, the film hardness and the heat resistance are remarkably lowered, and there is a problem that the film does not function sufficiently as a hard film for a cutting tool.
ここで、Ａ層の断面画像が図１（ａ）に示されており、電子線をＡ層の断面に照射して回折像や実像を撮像しており、回折の方向によって白と黒の濃淡の画像として撮影できる。本実施形態では図１（ａ）に示す実像画像において白と黒の境界が明瞭に確認できるものについて柱状晶の幅として測定できる。柱状晶における幅は上述したように３００ｎｍ以下、好ましくは２００ｎｍ以下、更に好ましくは１００ｎｍ以下とされている。
図１（ａ）では白と黒の濃淡の境界が明瞭でない部分もあるが、この場合には電子線の照射角度を変えることで明瞭でない部分について柱状晶の境界が明瞭になり、同様に幅寸法が測定可能である。図１（ｂ）に示す上述した従来技術によるＳｉ非含有皮膜のＴＥＭによる断面写真では、Ｔｉ，Ａｌ以外の第３元素が１０原子％未満に設定されている皮膜と、Ｓｉが偏析してアモルファス相が偏析している皮膜との結晶質の部分における柱状晶の幅を測定すると３００ｎｍより大きくなっており、粒の幅が本実施形態と比較して大きい。
Here, a cross-sectional image of the A layer is shown in FIG. 1A, and a diffraction image and a real image are taken by irradiating the cross section of the A layer with an electron beam. Can be taken as an image. In the present embodiment, the width of the columnar crystal can be measured for the real image shown in FIG. As described above, the width of the columnar crystal is 300 nm or less, preferably 200 nm or less, and more preferably 100 nm or less.
In FIG. 1 (a), there is a portion where the boundary between white and black is not clear, but in this case, the boundary of the columnar crystal becomes clear for the unclear portion by changing the irradiation angle of the electron beam. Dimensions can be measured. In the cross-sectional photograph by TEM of the above-described conventional Si-free coating shown in FIG. 1B, the coating in which the third element other than Ti and Al is set to less than 10 atomic%, and Si is segregated to be amorphous. When the width of the columnar crystal in the crystalline part with the film in which the phase is segregated is measured, it is larger than 300 nm, and the grain width is larger than that of the present embodiment.
そして、一の皮膜の上に組成の異なる別の皮膜を積層させる場合、上層の結晶成長は下層の結晶の具合に影響を受けることになる。本実施形態では、下層であるＡ層の粒の幅が３００ｎｍ以下と極微細であるため、その直上に形成されるＢ層がＴｉＮにＳｉを固溶したＳｉ含有被膜であっても、Ａ層の微細な構造上にエピタキシャル成長を促進して結晶質を保って完全な形でエピタキシャル成長が進行し、微細で緻密な構造の立方晶からなる結晶質の柱状晶を析出する。そのためアモルファス相即ちＳｉの偏析を含まない。 When another film having a different composition is laminated on one film, the crystal growth of the upper layer is affected by the condition of the crystal of the lower layer. In this embodiment, since the width of the grain of the A layer which is the lower layer is as extremely small as 300 nm or less, even if the B layer formed immediately above is a Si-containing film in which Si is dissolved in TiN, the A layer Epitaxial growth is promoted on this fine structure, and the crystal growth is maintained while maintaining the crystallinity to complete the crystal growth, thereby depositing crystalline columnar crystals composed of cubic crystals having a fine and dense structure. Therefore, it does not include an amorphous phase, that is, Si segregation.
ここで、Ｂ層の結晶質である柱状晶の幅はＡ層の粒の幅に大きく影響されるが、Ｂ層の組成比により更に大きく左右される。Ｂ層は組成がＳｉｘＴｉ１−ｘの窒化物からなるＳｉ含有被膜である。ｘと１−ｘは成分比を表す。
Ｂ層の組成ＳｉｘＴｉ１−ｘにおける金属成分の成分比ｘは原子比で次のように設定されている。
０．１≦ｘ≦０．３
Ｓｉは１０原子％未満では粒の幅が大きくなりやすく、３０原子％を越えるとアモルファス相が粒界中に形成され、密着性、耐摩耗性が低下してしまう。
図３は透過型電子顕微鏡（ＴＥＭ）で６００００倍の倍率で撮影したＢ層の断面画像である。図３に示すＢ層におけるＳｉ含有被膜の粒（柱状晶）は、Ａ層の柱状晶の幅が３００ｎｍ以下となる極微細で緻密な配列となることに起因して、柱状晶の成長方向の任意の位置での成長方向に略直交する方向の幅が５０ｎｍ以下となる微細で緻密な配列に形成されることになる。
そのため、Ｂ層は、上述の従来技術で問題のあった皮膜の脆さ、剥離、粒界を通した酸素の拡散を抑制し、さらに固溶強化による改善が著しい皮膜ができ、耐酸化性、対摩耗性が飛躍的に向上するという驚くべき知見を得るに至った。
Here, the width of the columnar crystals which are the crystalline material of the B layer is greatly influenced by the width of the grains of the A layer, but is further greatly influenced by the composition ratio of the B layer. The B layer is a Si-containing film made of a nitride having a composition of SixTi1-x. x and 1-x represent component ratios.
The component ratio x of the metal component in the composition SixTi1-x of the B layer is set as follows in terms of atomic ratio.
0.1 ≦ x ≦ 0.3
If the Si content is less than 10 atomic%, the width of the grains tends to be large, and if it exceeds 30 atomic%, an amorphous phase is formed in the grain boundary, resulting in a decrease in adhesion and wear resistance.
FIG. 3 is a cross-sectional image of layer B taken at a magnification of 60000 times with a transmission electron microscope (TEM). The grains (columnar crystals) of the Si-containing coating in the B layer shown in FIG. 3 are aligned in the growth direction of the columnar crystals due to the extremely fine and dense arrangement in which the width of the columnar crystals in the A layer is 300 nm or less. It is formed in a fine and dense arrangement in which the width in a direction substantially orthogonal to the growth direction at an arbitrary position is 50 nm or less.
Therefore, the B layer suppresses the brittleness, peeling, and diffusion of oxygen through the grain boundary, which has been problematic in the above-described prior art, and can further improve the coating by solid solution strengthening. As a result, the inventors have obtained a surprising finding that the wear resistance is dramatically improved.
本発明の実施形態においては、Ｂ層の被膜形成に関し、ＳｉあるいはＳｉ３Ｎ４が単独でＳｉＴｉＮ皮膜中にできるだけ存在しないことが望ましい。仮に、ＳｉあるいはＳｉ３Ｎ４が単独で存在する場合にはアモルファス状になることが多く、また結晶構造をとる場合でもＳｉＴｉＮやＴｉＡｌＣｒＮの立方晶と整合性をとりにくく、ＳｉＴｉＮのエピタキシャル成長を阻害してしまう。
なお、Ｓｉなどがマトリクスを覆うように存在すると酸素の拡散が抑制されるが、結晶構造が微細であればＳｉの偏析が無くても十分な耐酸化性が得られ、さらに微細化による耐摩耗性、密着性も一層の向上が得られる。このことは、エネルギー分散型蛍光Ｘ線分析における０．１７μｍ２の面積内でＳｉ濃度分配が均一に分散していることで確認できる（図４（ｂ）参照）。
In the embodiment of the present invention, it is desirable that Si or Si3N4 is not present in the SiTiN film as much as possible with respect to the formation of the B layer. If Si or Si3N4 is present alone, it is often amorphous, and even in the case of a crystal structure, it is difficult to achieve consistency with the cubic structure of SiTiN or TiAlCrN, thereby inhibiting the epitaxial growth of SiTiN.
Note that when Si or the like is present so as to cover the matrix, oxygen diffusion is suppressed. However, if the crystal structure is fine, sufficient oxidation resistance can be obtained even if there is no segregation of Si, and further wear resistance due to miniaturization. Property and adhesion can be further improved. This can be confirmed by the fact that the Si concentration distribution is uniformly dispersed within the area of 0.17 μm 2 in the energy dispersive X-ray fluorescence analysis (see FIG. 4B).
Ｓｉ含有皮膜であるＢ層は電子線回折分析においてアモルファス相を含まない結晶質のみで回折されることが好ましい。この場合に電子線回折分析によれば回折パターンを確認できる。また、前述したようにＢ層への酸素の侵入による酸化を防ぐためには均一なＳｉ濃度に構成する必要があり、ＳｉＴｉＮの固溶体でなければＳｉは均一に存在しない。
一方、従来技術に示したの単純な固溶体では結晶質である柱状晶の幅が３００ｎｍと大きく、格子単位で発生する内部応力により皮膜が脆くなるという欠点があったが、本発明によって、下層２の硬質皮膜の結晶質を緻密かつ微細化することにより、上層であるＢ層のＳｉＴｉＮ固溶体でも更に微細化と緻密化を達成できて内部応力の発生が抑えられ、密着性のある硬質皮膜の作製に成功した。
本実施形態では、上述のようにＡ層が粒の幅３００ｎｍ以下に設定されており、Ｂ層もＡ層の結晶構造に倣ってその影響を受けて一層微細な粒の幅５０ｎｍ以下に設定されていてそれぞれ微細で緻密な構成であるために、Ｓｉ含有被膜の粒界からの酸素の進入を抑制して酸化を抑制できる。
The B layer, which is a Si-containing film, is preferably diffracted only by a crystalline material that does not contain an amorphous phase in electron diffraction analysis. In this case, the diffraction pattern can be confirmed by electron beam diffraction analysis. Further, as described above, in order to prevent oxidation due to oxygen intrusion into the B layer, it is necessary to configure the Si concentration to be uniform. Si is not uniformly present unless it is a solid solution of SiTiN.
On the other hand, the simple solid solution shown in the prior art has a disadvantage that the width of the crystalline columnar crystal is as large as 300 nm and the film becomes brittle due to internal stress generated in lattice units. By making the crystal of the hard film dense and fine, even the SiTiN solid solution of the B layer, which is the upper layer, can be further refined and densified, and the generation of internal stress is suppressed, producing a hard film with adhesion succeeded in.
In the present embodiment, as described above, the A layer is set to have a grain width of 300 nm or less, and the B layer is also set to have a finer grain width of 50 nm or less following the influence of the crystal structure of the A layer. In addition, since each has a fine and dense structure, it is possible to suppress oxidation by suppressing the ingress of oxygen from the grain boundary of the Si-containing coating.
図４はＢ層の表面におけるＥＤＸマッピング結果を示す画像である。ＥＤＸは試料表面の元素分析を行う装置であり、エネルギー分散型の元素分析によるマッピング結果を示している。図４（ａ）はＢ層断面の皮膜組成ＳｉＴｉＮのＳＴＥＭ画像を示している。図４（ｂ）は図４（ａ）のＳＴＥＭ画像におけるＳｉ組成の画像であり、ＳｉはＳｉＴｉＮ固溶体からなる結晶質の柱状晶として、偏析することなく一様に分散して存在しており、アモルファス相が形成されない微細で緻密な柱状晶として存在することを表している。図４（ｃ）は同じくＮ組成の画像であり、同様にＳｉＴｉＮ固溶体からなる結晶質として均等に分散して存在している。図４（ｄ）は同じくＴｉ組成の画像であり、同様にＳｉＴｉＮ固溶体からなる結晶質として均等に分散して存在している。 FIG. 4 is an image showing an EDX mapping result on the surface of the B layer. EDX is a device that performs elemental analysis of the sample surface, and shows a mapping result by energy dispersive elemental analysis. FIG. 4A shows a STEM image of the coating composition SiTiN of the B layer cross section. FIG. 4 (b) is an image of the Si composition in the STEM image of FIG. 4 (a). Si is present as a crystalline columnar crystal composed of a SiTiN solid solution and is uniformly dispersed without segregation. It shows that it exists as a fine and dense columnar crystal in which an amorphous phase is not formed. FIG. 4C is also an image of N composition, which is equally dispersed as a crystalline material made of a SiTiN solid solution. FIG. 4 (d) is an image having the same Ti composition, which is equally dispersed as a crystalline material composed of a SiTiN solid solution.
図５（ａ）〜（ｆ）はＢ層の縦断面におけるＴＥＭによる観察結果を示す電子線回折画像である。これらの画像は、電子線による回折像によってＢ層の回折スポットが明瞭に観察される領域とＢ層の回折スポットが明瞭に観察されない領域とをＢ層断面の３カ所（上部、中部、下部）の画像として図５（ａ）（ｂ）（ｃ）と（ｄ）（ｅ）（ｆ）をそれぞれ得た。
各画像において、中央の輝度の高い部分がビームスポットであり、その周囲に分散している輝度の高い部分は回折スポットであり、結晶質によって回折されたことを示している。回折スポットを確認できない領域は電子線が別の方向に射出している状態を示しており、この場合には電子線の照射角度を変更すれば回折スポットを確認できる。Ｂ層の断面にアモルファス相が形成されている場合には回折スポットは確認できない。
各図５（ａ）〜（ｆ）に示す各分析箇所毎に回折スポットの配置が異なるのは結晶の方位がそれぞれ微妙に異なるからである。そのため、これらの電子線回折像によってＢ層の断面全体に結晶質が緻密に形成されていることを確認できる。
FIGS. 5A to 5F are electron beam diffraction images showing observation results by TEM in the longitudinal section of the B layer. In these images, there are three areas (upper, middle and lower) of the cross section of the B layer: a region where the diffraction spot of the B layer is clearly observed by a diffraction image by an electron beam and a region where the diffraction spot of the B layer is not clearly observed. 5 (a), (b), (c), and (d), (e), and (f), respectively, were obtained as images of.
In each image, the high-brightness portion at the center is a beam spot, and the high-brightness portion dispersed around it is a diffraction spot, which indicates that it has been diffracted by the crystalline material. The region where the diffraction spot cannot be confirmed shows a state in which the electron beam is emitted in another direction. In this case, the diffraction spot can be confirmed by changing the irradiation angle of the electron beam. When an amorphous phase is formed in the cross section of the B layer, a diffraction spot cannot be confirmed.
The reason why the diffraction spots are arranged differently for each analysis site shown in FIGS. 5A to 5F is because the crystal orientations are slightly different. Therefore, it can be confirmed from these electron beam diffraction images that the crystalline material is densely formed in the entire cross section of the B layer.
硬質皮膜の膜厚は切削工具の刃径によって適切に設定される。本実施形態による硬質皮膜におけるＡ層とＢ層の膜厚について、Ａ層の膜厚をＴａ、Ｂ層の膜厚をＴｂとすると、膜厚ＴａとＴｂの膜厚比率は、
３≧Ｔｂ／Ｔａ≧０．７
であることが好ましい。０．７未満では、微細で緻密な結晶質構造を有していて密着性と耐摩耗性が高いＢ層の性能を発揮することはできない。より好ましくはＴｂ／Ｔａ≧０．９である。
また、Ａ層とＢ層を積層してなる硬質皮膜の全体膜厚は、切削工具の刃径により適宜設定する。本実施形態による硬質皮膜では０．５μｍ以上１０μｍ以下であることが好ましい。これは０．５μｍ未満ではその薄さから皮膜の性能を十分発揮できず、１０μｍ以上では膜厚が厚すぎて膜自身の破壊につながるからである。より好ましくは１μｍ以上７μｍ以下である。
The film thickness of the hard coating is appropriately set depending on the blade diameter of the cutting tool. Regarding the film thicknesses of the A layer and the B layer in the hard film according to the present embodiment, when the film thickness of the A layer is Ta and the film thickness of the B layer is Tb, the film thickness ratio of the film thickness Ta and Tb is
3 ≧ Tb / Ta ≧ 0.7
It is preferable that If the ratio is less than 0.7, the performance of the B layer having a fine and dense crystalline structure and high adhesion and wear resistance cannot be exhibited. More preferably, Tb / Ta ≧ 0.9.
Moreover, the whole film thickness of the hard film formed by laminating the A layer and the B layer is appropriately set according to the blade diameter of the cutting tool. In the hard film according to the present embodiment, it is preferably 0.5 μm or more and 10 μm or less. This is because if the thickness is less than 0.5 μm, the performance of the film cannot be exhibited sufficiently due to its thinness, and if it is 10 μm or more, the film thickness is too thick, leading to the destruction of the film itself. More preferably, they are 1 micrometer or more and 7 micrometers or less.
次に本実施形態による硬質皮膜切削工具の硬質皮膜の成膜方法について説明する。
成膜方法は例えばアークイオンプレーティング方法やスパッタリング法等の物理蒸着方法があるが、これに限定されるものではない。本実施形態ではアークイオンプレーティング方法による成膜方法を用いるものとする。
Ａ層の成膜方法では、反応ガス圧力が３Ｐａ以上７Ｐａ以下、基盤負バイアス電圧は７５Ｖ以上１７５Ｖ未満であれば、密着力が高く粒の幅３００ｎｍ以下となる微細な幅をもった皮膜を成膜できる。ここで、基盤負バイアス電圧が７５Ｖ未満では皮膜の密着性が劣り、１７５Ｖ以上では微細な粒の幅が得られない。同様に反応ガス圧力は３Ｐａ未満では微細な粒の幅が得られず、７Ｐａを越えると密着性が劣る。
そして、ＴｉＡｌＣｒターゲットを放電させ、基盤バイアスを−１７５Ｖ以上−７５Ｖ未満印加してボールエンドミルの刃部表面に所望のＴｉＡｌＣｒＮ皮膜をＡ層として作製した。
これらの条件にてＡ層を成膜した状態でＸ線回折によって結晶の方位を検索すれば、Ｘ線回折結果において次の条件を満たす立方晶構造になる。
０．５＜１（２００）／Ｉ（１１１）＜３、
Ｉ（２００）＞Ｉ（２２０）、
Ｉ（１１１）＞Ｉ（２２０）
Next, a method for forming a hard film of the hard film cutting tool according to the present embodiment will be described.
Examples of the film forming method include physical vapor deposition methods such as arc ion plating and sputtering, but are not limited thereto. In this embodiment, a film forming method using an arc ion plating method is used.
In the method of forming the A layer, if the reaction gas pressure is 3 Pa or more and 7 Pa or less and the base negative bias voltage is 75 V or more and less than 175 V, a film having a fine width with high adhesion and a grain width of 300 nm or less is formed. I can make a film. Here, when the substrate negative bias voltage is less than 75 V, the adhesion of the film is inferior, and when it is 175 V or more, a fine grain width cannot be obtained. Similarly, when the reaction gas pressure is less than 3 Pa, a fine grain width cannot be obtained, and when it exceeds 7 Pa, the adhesion is inferior.
Then, the TiAlCr target was discharged, and a base bias was applied at −175 V or more and less than −75 V to prepare a desired TiAlCrN film as an A layer on the surface of the blade end of the ball end mill.
If the crystal orientation is searched by X-ray diffraction with the A layer formed under these conditions, a cubic structure that satisfies the following condition in the X-ray diffraction result is obtained.
0.5 <1 (200) / I (111) <3,
I (200)> I (220),
I (111)> I (220)
また、Ｂ層の成膜方法では、反応ガスを用いてチャンバー内の圧力を１Ｐａ以上６Ｐａ以下に設定し、基盤負バイアス電圧は３５Ｖ以上１００Ｖ未満とする。そしてＳｉＴｉターゲットを放電させ、基盤バイアス電圧を印加して所望のＳｉＴｉＮ皮膜をＢ層としてＡ層の直上に成膜する。エピタキシャル成長は下地層であるＡ層の晶幅に倣って成長するため、Ａ層を緻密で微細な幅の柱状晶の結晶構造に形成することで、Ｂ層の結晶構造も密着力が高く粒の幅５０ｎｍ以下となる微細な幅の柱状晶をもった皮膜を成膜できる。
そして、Ａ層にＢ層を積層して硬質皮膜を成膜してＸ線回折によって結晶の方位を検索すれば、Ｘ線回折結果は次の条件を満たす立方晶構造になる。
Ｉ（２００）／Ｉ（１１１）＞２
１（２００）＞Ｉ（２２０）、
Ｉ（１１１）＞Ｉ（２２０）、
In the method for forming the B layer, the pressure in the chamber is set to 1 Pa or more and 6 Pa or less using a reaction gas, and the base negative bias voltage is set to 35 V or more and less than 100 V. Then, the SiTi target is discharged, a base bias voltage is applied, and a desired SiTiN film is formed as a B layer immediately above the A layer. Epitaxial growth grows following the crystal width of the underlying layer A. Therefore, by forming the layer A into a dense and fine columnar crystal structure, the crystal structure of the layer B also has high adhesion and is A film having columnar crystals with a fine width of 50 nm or less can be formed.
Then, by laminating the B layer on the A layer to form a hard film and searching for the crystal orientation by X-ray diffraction, the X-ray diffraction result has a cubic structure that satisfies the following conditions.
I (200) / I (111)> 2
1 (200)> I (220),
I (111)> I (220),
なお、図６はＡ層の皮膜の結晶配向性を示すＸ線回折パターンであり、立方晶構造であることを裏付ける強度分布を示している。横軸２θにおける面方位（１１１）、（２００）、（２２０）のピーク位置からＡ層が立方晶であることを確認できる。なお、このＸ線回折試験では超硬合金を切削工具の基体としてＡ層を被覆したため、上記の面方位以外に他のピーク位置が出現している。 FIG. 6 is an X-ray diffraction pattern showing the crystal orientation of the coating of the A layer, and shows the intensity distribution that confirms the cubic structure. From the peak positions of the plane orientations (111), (200), and (220) on the horizontal axis 2θ, it can be confirmed that the A layer is cubic. In this X-ray diffraction test, since the layer A is coated with cemented carbide as the base of the cutting tool, other peak positions appear in addition to the above-mentioned plane orientation.
次に本発明の実施例について説明する。
切削工具として超硬合金製のボールエンドミルを用いる。成膜装置としてアークイオンプレーティング装置を用い、合金ターゲットとしてＴｉＡｌＣｒターゲットとＳｉＴｉターゲットを使用した。
まず、真空ポンプによってアークイオンプレーティング装置のチャンバー内を８．０×１０−４Ｐａまで排気した後、チャンバー内にアルゴンガスを導入してチャンバー内を１Ｐａに保持し、基盤バイアス電圧を−３００Ｖとし、基盤表面の清浄化処理を３０分間行った。
次に、反応ガスとして窒素ガスを用いてチャンバー内が５Ｐａになるように導入し、ＴｉＡｌＣｒターゲットを放電させ、基盤負バイアスを１５０Ｖ印加してボールエンドミルの刃部表面に所望のＴｉＡｌＣｒＮ皮膜をＡ層として作製した。
Next, examples of the present invention will be described.
A ball end mill made of cemented carbide is used as a cutting tool. An arc ion plating apparatus was used as a film forming apparatus, and a TiAlCr target and a SiTi target were used as alloy targets.
First, the inside of the chamber of the arc ion plating apparatus is evacuated to 8.0 × 10 −4 Pa by a vacuum pump, and then argon gas is introduced into the chamber to keep the inside of the chamber at 1 Pa, and the base bias voltage is −300 V. The substrate surface was cleaned for 30 minutes.
Next, nitrogen gas is introduced as a reaction gas so that the inside of the chamber becomes 5 Pa, the TiAlCr target is discharged, a base negative bias is applied 150 V, and a desired TiAlCrN film is applied to the surface of the blade end of the ball end mill. As produced.
次に、反応ガスとして窒素ガスを用いてチャンバー内が３Ｐａになるように導入し、ＳｉＴｉターゲットを放電させ、基盤負バイアスを９０Ｖ印加して所望のＳｉＴｉＮ皮膜をＢ層としてＡ層の直上に成膜した。
このようにして得られた硬質皮膜工具における硬質皮膜について、Ａ層、Ｂ層についてそれぞれ下記表１に示す実施例１〜５と比較例６〜１２からなる試料を作製した。これらＡ層、Ｂ層の組成、粒（柱状晶）の幅、Ａ層＋Ｂ層の総膜厚、膜厚比率Ｔａ／Ｔｂを表１に示す。
Next, nitrogen gas is introduced as a reaction gas so that the inside of the chamber becomes 3 Pa, the SiTi target is discharged, a substrate negative bias is applied at 90 V, and a desired SiTiN film is formed directly on the A layer as the B layer. Filmed.
About the hard film | membrane in the hard film tool obtained in this way, the sample which consists of Examples 1-5 and Comparative Examples 6-12 shown in following Table 1 about A layer and B layer was produced, respectively. Table 1 shows the composition of these A layers and B layers, the width of the grains (columnar crystals), the total film thickness of the A layer + B layer, and the film thickness ratio Ta / Tb.
そして、実施例１〜５と比較例６〜１２の各硬質皮膜についてＡ層と（Ａ層＋Ｂ層）の皮膜についてＸ線を照射してＸ線回折パターンを計測し、Ｘ線回折強度比を算出した。またＡ層について結晶構造を検査した。この結果を表２に示す
次に、これら実施例１〜５と比較例６〜１２による硬質皮膜で被覆した工具（２枚刃ボールエンドミル）を用いて切削試験を行い、耐摩耗性の評価と工具寿命の切削評価を実施した。その切削評価条件を示すと下記の通りになる。
（切削評価条件）
工具：２枚刃ボールエンドミル（半径１ｍｍ、先端径φ２ｍｍ）
披削材：ＳＫＤ１１（ＨＲＣ６０）
切り込み条件：軸方向０．２ｍｍ 径方向０．５ｍｍ
回転数：３０，０００ｍｉｎ−１
切削油：オイルミスト
切削長さは切削加工機のプログラム上、１ポケットあたり３０ｍと設定し、１ポケット切削終了ごとに刃の摩耗状態を確認した。
And about each hard film | membrane of Examples 1-5 and Comparative Examples 6-12, X-ray | X_line diffraction pattern is measured about the film | membrane of A layer and (A layer + B layer), X-ray diffraction intensity ratio is calculated | required. Calculated. The crystal structure of the A layer was examined. The results are shown in Table 2. Next, a cutting test was performed using a tool (two-blade ball end mill) coated with a hard coating according to Examples 1 to 5 and Comparative Examples 6 to 12, and the wear resistance was evaluated. Cutting evaluation of tool life was performed. The cutting evaluation conditions are as follows.
(Cutting evaluation conditions)
Tool: 2-flute ball end mill (radius 1mm, tip diameter φ2mm)
Cutting material: SKD11 (HRC60)
Cutting condition: axial direction 0.2mm radial direction 0.5mm
Rotational speed: 30,000 min -1
Cutting oil: Oil mist The cutting length was set to 30 m per pocket in the cutting machine program, and the wear state of the blade was confirmed at the end of one pocket cutting.
切削試験の結果、表１に示す実施例１〜５は切削長が２７０ｍ〜３６０ｍとなり、いずれも従来の切削工具と比べて寿命が著しく向上しており、高い耐摩耗性を確認できた。しかも、切削加工における高速化、被加工物の高硬度化においても十分な切削性能を発揮することができた。 As a result of the cutting test, the cutting lengths of Examples 1 to 5 shown in Table 1 were 270 m to 360 m, and the lifetime was significantly improved as compared with the conventional cutting tools, and high wear resistance was confirmed. In addition, sufficient cutting performance was able to be exhibited even at high speed in cutting and high hardness of the workpiece.
一方、比較例６、７はＡ層の組成が本発明の範囲を外れ、特性がＡｌＣｒＮ或いはＴｉＡｌＮの一方に偏り、且つ粒の幅５００ｎｍ、６００ｎｍとなり微細にならないためＢ層に微細な柱状晶を形成できない。そのため、十分な耐摩耗性と耐酸化性が得られず、切削寿命が短かった。
比較例１１もＡ層の組成が本発明の範囲を外れておりＡｌが７０原子％より大きいリッチな組成であるため、皮膜中に密着力の劣る六方晶が形成されてしまい、切削の初期に剥離に至った。比較例８、９、１０、１２のＡ層とＢ層の組成は本発明の範囲に含まれるものであるが、比較例８はＢ層の膜厚が薄すぎるため耐摩耗性に劣り、比較例９はＢ層の膜厚が厚すぎるため、刃先に内部応力に起因するチッピングが生じ、急激に進行する局所的な摩耗により十分な性能が発揮されない。比較例１０は全体膜厚が薄すぎるため耐摩耗性が十分ではなく、比較例１２は全体膜厚が厚すぎるため皮膜の内部応力により切削初期に剥離が生じた。
On the other hand, in Comparative Examples 6 and 7, the composition of the A layer is out of the range of the present invention, the characteristics are biased to one of AlCrN or TiAlN, and the grain widths are 500 nm and 600 nm. It cannot be formed. Therefore, sufficient wear resistance and oxidation resistance could not be obtained, and the cutting life was short.
In Comparative Example 11, since the composition of the A layer is out of the range of the present invention and Al is a rich composition larger than 70 atomic%, hexagonal crystals with poor adhesion are formed in the film, and at the initial stage of cutting. It came off. The compositions of the A layer and the B layer in Comparative Examples 8, 9, 10, and 12 are included in the scope of the present invention, but Comparative Example 8 is inferior in wear resistance because the B layer is too thin. In Example 9, since the thickness of the layer B is too thick, chipping due to internal stress occurs at the cutting edge, and sufficient performance is not exhibited due to local wear that proceeds rapidly. In Comparative Example 10, the entire film thickness was too thin, so that the wear resistance was not sufficient. In Comparative Example 12, the entire film thickness was too thick, and peeling occurred at the beginning of cutting due to the internal stress of the film.
上述のように本実施形態による硬質皮膜切削工具によれば、Ａ層を立方晶からなる結晶質に形成して緻密で幅３００ｎｍ以下の微細な柱状晶で構成したから、Ａ層の硬度が高く耐酸化性が良好である上にＡ層の上に積層されるＢ層のエピタキシャル成長を促進させて固溶体からなる緻密で幅５０ｎｍ以下の微細な柱状晶を立方晶として形成できて、第３元素であるＣｒが１０原子％以上であっても、密着性が良く耐酸化性と耐摩耗性が高くなる。そのため、切削加工の高速化、乾式化、被加工物の高硬度化による摩耗を抑制し、密着性と耐熱性に優れた長寿命の被覆切削工具が得られる。
しかも、Ｓｉ濃度の異なる皮膜を同一層内に形成することはないから、製造コストを低廉に抑えることができる。
As described above, according to the hard film cutting tool according to the present embodiment, the A layer is formed of cubic crystals and is composed of dense columnar crystals having a width of 300 nm or less. Therefore, the hardness of the A layer is high. In addition to having good oxidation resistance, the epitaxial growth of the B layer laminated on the A layer is promoted to form fine columnar crystals of solid solution with a width of 50 nm or less as cubic crystals. Even if Cr is 10 atomic% or more, the adhesion is good and the oxidation resistance and wear resistance are high. For this reason, wear due to high-speed cutting, dry processing, and high hardness of the workpiece is suppressed, and a long-life coated cutting tool having excellent adhesion and heat resistance can be obtained.
In addition, since the films having different Si concentrations are not formed in the same layer, the manufacturing cost can be reduced.
以上、本発明の実施形態を説明したが、これはあくまでも一実施形態でありこれに限定されることなく、本発明の趣旨を逸脱しない範囲内で種々の形態や態様を採用できることはいうまでもない。
次に本発明の実施形態の変形例について説明する。
上述の実施形態で説明したように、Ａ層とＢ層の積層構造からなる硬質皮膜を被覆することで工具の切削性能は著しく向上するが、本変形例ではＢ層直上に更に第３層を成膜している。この第３層は、金属元素として少なくともＣｒとＡｌを含み、非金属元素として少なくとも窒素を含む耐酸化性に優れたＣｒＡｌ系皮膜、例えばＴｉＡｌＣｒＮ皮膜を膜厚０．１μｍ以上０，８μｍ以下の薄膜で形成している。これによって、高硬度で相対的に耐熱性の劣るＢ層に対して、切削に伴う刃先温度の上昇に耐性を持たせると共にＢ層よりも低硬度ゆえの刃先への衝撃緩和効果を持たせて、切削工具の性能向上を図っている。
このように、本発明による硬質皮膜は、皮膜の最適化を図り皮膜そのものの性能を最大限に引き出すことで、性能向上を達成することができる。
As mentioned above, although embodiment of this invention was described, this is only one embodiment, and it is needless to say that various forms and aspects can be adopted without departing from the gist of the present invention without being limited thereto. Absent.
Next, a modification of the embodiment of the present invention will be described.
As described in the above embodiment, the cutting performance of the tool is remarkably improved by coating a hard coating composed of a laminated structure of the A layer and the B layer, but in this modification, a third layer is further provided immediately above the B layer. A film is being formed. This third layer is a thin film having a film thickness of 0.1 μm or more and 0.8 μm or less formed of a CrAl-based film excellent in oxidation resistance containing at least Cr and Al as metal elements and at least nitrogen as a nonmetal element, for example, a TiAlCrN film. It is formed with. As a result, the B layer having high hardness and relatively inferior heat resistance is made resistant to the rise in cutting edge temperature accompanying cutting and has an impact mitigating effect on the cutting edge due to lower hardness than the B layer. The performance of cutting tools is improved.
Thus, the hard coating according to the present invention can achieve improved performance by optimizing the coating and maximizing the performance of the coating itself.
Claims (10)
前記硬質皮膜は基材上に形成されて被覆するＡ層と該Ａ層の直上に形成されるＢ層とを有しており、
前記Ａ層はＴｉＡｌＣｒの窒化物、酸窒化物、炭窒化物、酸炭窒化物のいずれかのＳｉ非含有皮膜であって、立方晶からなる微細な柱状晶で構成されていて該柱状晶の成長方向に略直交する方向の各柱状晶の幅が３００ｎｍ以下に形成され、
前記Ｂ層はＳｉＴｉの窒化物を主体としてなるＳｉ含有皮膜であることを特徴とする硬質皮膜切削工具。 A hard coating cutting tool formed by laminating a hard coating on the surface of a tool substrate,
The hard coating has an A layer that is formed and coated on a substrate, and a B layer that is formed immediately above the A layer,
The layer A is a Si-free film of any of TiAlCr nitride, oxynitride, carbonitride, and oxycarbonitride, and is composed of fine columnar crystals composed of cubic crystals. The width of each columnar crystal in a direction substantially perpendicular to the growth direction is formed to be 300 nm or less,
The hard coating cutting tool, wherein the B layer is a Si-containing coating mainly composed of a nitride of SiTi.
０．１≦ａ≦０．３５、
０．４５≦ｂ≦０．７、
０．１≦ｃ≦０．３５、
ａ＋ｂ＋ｃ＝１
であることを特徴とする請求項１または２に記載の硬質皮膜切削工具。 The component ratios a, b, and c of the metal components in the composition TiaAlbCrc of the A layer are atomic ratios,
0.1 ≦ a ≦ 0.35,
0.45 ≦ b ≦ 0.7,
0.1 ≦ c ≦ 0.35,
a + b + c = 1
The hard-film cutting tool according to claim 1 or 2, wherein
０．５＜Ｉ（２００）／Ｉ（１１１）＜３、
Ｉ（２００）＞Ｉ（２２０）、
Ｉ（１１１）＞Ｉ（２２０）、
を満たした立方晶構造であることを特徴とする請求項３に記載の硬質被覆工具。 In the X-ray diffraction, the A layer is
0.5 <I (200) / I (111) <3,
I (200)> I (220),
I (111)> I (220),
The hard-coated tool according to claim 3, which has a cubic structure satisfying the requirements.
０．１≦ｘ≦０．３
であることを特徴とする請求項１乃至４のいずれかに記載の硬質皮膜切削工具。 The component ratio x of the metal component in the composition SixTi 1- x of the B layer is an atomic ratio of 0.1 ≦ x ≦ 0.3.
The hard-film cutting tool according to any one of claims 1 to 4, wherein
Ｉ（２００）／Ｉ（１１１）＞２
Ｉ（２００）＞Ｉ（２２０）、
Ｉ（１１１）＞Ｉ（２２０）、
を満たした立方晶構造を有することを特徴とする請求項５に記載の硬質皮膜切削工具。 In the X-ray diffraction of the hard film composed of the A layer and the B layer,
I (200) / I (111)> 2
I (200)> I (220),
I (111)> I (220),
The hard film cutting tool according to claim 5, which has a cubic structure satisfying
３≧Ｔｂ／Ｔａ≧０．７
であり、Ａ層とＢ層の膜厚（Ｔａ＋Ｔｂ）が０．５μｍ以上１０μｍ以下であることを特徴とする請求項１乃至６のいずれかに記載の硬質皮膜切削工具。 When the film thickness of the A layer is Ta and the film thickness of the B layer is Tb, the film thickness ratio of the A layer and the B layer is 3 ≧ Tb / Ta ≧ 0.7
The hard film cutting tool according to any one of claims 1 to 6, wherein the film thickness (Ta + Tb) of the A layer and the B layer is 0.5 µm or more and 10 µm or less.
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009167498A (en) * | 2008-01-18 | 2009-07-30 | Hitachi Tool Engineering Ltd | Hard film-coated member, and method for producing hard film-coated member |
| JP2010208007A (en) * | 2009-03-10 | 2010-09-24 | Hitachi Tool Engineering Ltd | Hard film-coated tool |
| WO2012069475A1 (en) * | 2010-11-23 | 2012-05-31 | Seco Tools Ab | Coated cutting tool insert |
| WO2017170536A1 (en) * | 2016-03-30 | 2017-10-05 | 三菱日立ツール株式会社 | Coated cutting tool |
| JP2018039045A (en) * | 2016-09-07 | 2018-03-15 | 和田山精機株式会社 | Covering cold metal mold |
| JP2020020030A (en) * | 2018-07-31 | 2020-02-06 | 和田山精機株式会社 | Hard film coated member and hard film coated tool |
| CN114929415A (en) * | 2020-01-08 | 2022-08-19 | 住友电工硬质合金株式会社 | Cutting tool |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009167498A (en) * | 2008-01-18 | 2009-07-30 | Hitachi Tool Engineering Ltd | Hard film-coated member, and method for producing hard film-coated member |
| JP2010208007A (en) * | 2009-03-10 | 2010-09-24 | Hitachi Tool Engineering Ltd | Hard film-coated tool |
| WO2012069475A1 (en) * | 2010-11-23 | 2012-05-31 | Seco Tools Ab | Coated cutting tool insert |
| CN103249869A (en) * | 2010-11-23 | 2013-08-14 | 山高刀具公司 | Coated cutting tool insert |
| US9180522B2 (en) | 2010-11-23 | 2015-11-10 | Seco Tools Ab | Coated cutting tool insert |
| CN103249869B (en) * | 2010-11-23 | 2016-05-18 | 山高刀具公司 | Coated cutting tool insert |
| WO2017170536A1 (en) * | 2016-03-30 | 2017-10-05 | 三菱日立ツール株式会社 | Coated cutting tool |
| JPWO2017170536A1 (en) * | 2016-03-30 | 2018-06-28 | 三菱日立ツール株式会社 | Coated cutting tool |
| CN108883481A (en) * | 2016-03-30 | 2018-11-23 | 三菱日立工具株式会社 | coated cutting tool |
| CN108883481B (en) * | 2016-03-30 | 2020-01-14 | 三菱日立工具株式会社 | Coated cutting tool |
| US11465214B2 (en) | 2016-03-30 | 2022-10-11 | Moldino Tool Engineering, Ltd. | Coated cutting tool |
| JP2018039045A (en) * | 2016-09-07 | 2018-03-15 | 和田山精機株式会社 | Covering cold metal mold |
| JP2020020030A (en) * | 2018-07-31 | 2020-02-06 | 和田山精機株式会社 | Hard film coated member and hard film coated tool |
| JP7029700B2 (en) | 2018-07-31 | 2022-03-04 | 和田山精機株式会社 | Hard film coating member and hard film coating tool |
| CN114929415A (en) * | 2020-01-08 | 2022-08-19 | 住友电工硬质合金株式会社 | Cutting tool |
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