JP5464494B2 - Surface coated cutting tool with excellent chipping resistance and peeling resistance of hard coating layer - Google Patents

Description

  The present invention relates to a surface-coated cutting tool in which a hard coating layer including at least a TiAlN layer is formed by physical vapor deposition on a cutting tool substrate surface made of a WC-based cemented carbide alloy. The surface of the hard coating layer has excellent chipping resistance and peeling resistance in small-diameter low-speed cutting processing where welding chipping is likely to occur or high-speed heavy cutting processing in which a high load acts on the cutting edge. The present invention relates to a coated cutting tool (hereinafter referred to as a coated tool).

  In general, for coated tools, inserts that are detachably attached to the tip of a cutting tool for turning of work materials such as various types of steel and cast iron, and the inserts are detachably attached to be used for chamfering and grooving. An insert-type end mill that performs cutting as well as a solid-type end mill that is used for processing and shoulder processing, and a drill that performs drilling are known.

  For example, in Patent Document 1, when forming a TiCN layer as a hard coating layer by chemical vapor deposition (CVD) on the surface of a cutting tool base made of a WC-based cemented carbide, the WC crystal grains and the TiCN crystal grains An epitaxial interface (for example, an interface in which the (0001) plane of WC and the (111) plane of TiCN are parallel and the [11-20] orientation of WC and the [−110] orientation of TiCN are parallel) is formed between them. By doing so, it is known to improve the adhesion between the tool base and the hard coating layer.

  Further, for example, in Patent Document 2, an arc, which is a kind of physical vapor deposition (PVD) method, has a hard coating layer having a TiN layer and an intermediate layer made of a TiCN layer on the surface of a cutting tool base made of a WC-based cemented carbide. In a coated tool (hereinafter referred to as a conventional coated tool) formed by vapor deposition by an ion plating (AIP) method, the (0001) plane of WC and the (1-11) plane of the intermediate layer are parallel, and <11- It is known that by forming an epitaxial interface in which the 20> orientation and the <110> orientation of the intermediate layer are parallel, the chipping resistance and peeling resistance of the intermediate layer (hard coating layer) are improved.

JP 2000-234172 A Japanese Patent No. 3333081

In recent years, FA of cutting devices has been remarkable, and in addition, there has been a strong demand for labor saving, energy saving, cost reduction and efficiency for cutting, and cutting under more severe conditions has come to be performed. Therefore, a coated tool having a cutting performance suitable for these cutting conditions is required.
For example, in the coated tool shown in Patent Document 1, an attempt is made to improve the adhesion of the hard coating layer by forming an epitaxial interface by a chemical vapor deposition (CVD) method between the tool base and the hard coating layer. However, when an epitaxial interface is formed by a chemical vapor deposition (CVD) method, the formation of the epitaxial interface is substantially limited to the (0001) plane or the (10-10) plane of the WC crystal grain. On the surface of a general tool substrate where higher order WC crystal planes are exposed, the area ratio in which the epitaxial interface is formed is not sufficient, and a non-epitaxial interface with weak adhesion is widely formed. Since the weak interface at the time of heavy cutting is the starting point of film peeling, the desired peeling resistance cannot be obtained, and the substrate is exposed to a high temperature (about 1000 ° C.) during vapor deposition. Since the η phase is formed in the substrate structure, residual stress cannot be introduced, and cracks are likely to occur, so that even if the adhesion is improved, the cutting performance as a coated tool is satisfactory. I can't say that.
Further, in the conventional coated tool shown in Patent Document 2, the (0001) plane of WC and the (111) plane of TiN are parallel and the [11-20] orientation of WC is determined by physical vapor deposition (PVD). By forming an epitaxial interface parallel to the [110] orientation of TiN, it is possible to improve the chipping resistance and peeling resistance of the hard coating layer in cutting under normal conditions. For example, in high-speed heavy cutting such as steel and cast iron, where high load is applied to the cutting edge with high heat generation, the tool life is reduced due to insufficient chipping resistance and peeling resistance of the hard coating layer. There was the problem of being short-lived. In addition, since the base material of the conventional coated tool is required to have a special composition containing a large amount of plate-like WC particles on which the (0001) plane has been grown, a commercially available super Application to a general tool base made of a hard alloy powder or a tool base having a fine or complicated shape such as a small diameter drill has been substantially difficult.

  In view of the above, the present inventors, from the above-mentioned viewpoint, have a high load on the cutting edge accompanied by a small-diameter low-speed cutting process in which welding chipping is likely to occur, or a high-speed heavy cutting process in which a high load acts on the cutting edge. As a result of earnest research to provide a coated tool with excellent fracture resistance and exfoliation resistance even when used for high-speed heavy cutting of steel, cast iron, etc., the following knowledge was obtained.

Formation of an epitaxial interface between the tool substrate surface and the hard coating layer is performed by chemical vapor deposition (CVD) with the coated tool disclosed in Patent Document 1 and physical vapor deposition (PVD) with the coated tool disclosed in Patent Document 2. The arc ion plating (AIP) method, which is one of the above.
However, the present inventors have shown, for example, the formation of a TiAlN layer as a hard coating layer adjacent to the surface of a tool substrate (hereinafter referred to as a WC carbide substrate) made of a WC-based cemented carbide in a schematic explanatory view in FIG. By forming with an ion plating apparatus using a pressure gradient type Ar plasma gun which is one of the physical vapor deposition (PVD) apparatuses shown, a specific surface is formed between the surface of the WC carbide substrate and the hard coating layer (TiAlN layer). It has been found that a heteroepitaxial interface satisfying the epitaxial relationship can be formed.
That is, a WC carbide substrate is mounted in an ion plating apparatus using the pressure gradient Ar plasma gun, for example,
WC carbide substrate temperature: 240-450 ° C.
Plasma gun discharge power: 3kW
Discharge gas flow rate: Argon (Ar) gas 25-40 sccm,
DC bias voltage applied to the tool base: -600V
After pre-processing under the specific conditions
WC carbide substrate temperature: 240-450 ° C.
Evaporation source: Metal Ti, Metal Al
Plasma gun discharge power (for metal Ti): 8-12 kW,
Plasma gun discharge power (relative to metal Al): 6-9 kW,
Reaction gas flow rate: nitrogen _{(N 2)} gas 80～120Sccm,
Discharge gas flow rate: Argon (Ar) gas 55-60 sccm,
DC bias voltage applied to the tool base: 0V
When the vapor deposition is performed under the specific conditions of the following, between the TiAlN crystal grains in the TiAlN layer formed as a result (hereinafter referred to as a modified TiAlN layer) and the WC crystal grains in the WC carbide substrate, A heteroepitaxial interface that satisfies the epitaxial relationship is formed.
That is, for the cross section of the interface between the WC cemented carbide substrate and the modified TiAlN layer, the [0001] orientation of the WC crystal grains and the TiAlN crystal grains obtained by measuring with a field emission scanning electron microscope and an electron beam backscattering diffractometer. [110] orientation is parallel, and the WC grain [10-10] orientation and TiAlN grains [001] orientation is a crystal grain of the interface length is parallel to the _{X a,}
Similarly, the [0001] orientation of the WC crystal grain and the [111] orientation of the TiAlN crystal grain obtained by measurement using a field emission scanning electron microscope and an electron beam backscatter diffraction apparatus are parallel, and the [ 11-20] orientation and TiAlN grains [110] orientation is a crystal grain of the interface length is parallel to the case of the _{X C,}
Between the surface of the WC carbide substrate and the modified TiAlN layer adjacent thereto,
1> (X _A + X _C ) /X≧0.3,
(Where X represents the total length of the interface), a heteroepitaxial interface is formed.
And, by forming the heteroepitaxial interface between the WC carbide substrate surface and the modified TiAlN layer adjacent thereto, the adhesion strength between the WC carbide substrate and the hard coating layer is greatly improved, Excellent chipping resistance even when such a coated tool is used for small-diameter low-speed cutting, where welding chipping is likely to occur, or high-speed heavy-duty cutting where a high load is applied to the cutting edge and high cutting force. It has been found that it exhibits peel resistance and exhibits excellent cutting performance over a long period of use.

The present invention has been made based on the above findings,
A surface-coated cutting tool in which a hard coating layer including at least a TiAlN layer is formed on a surface of a cutting tool base made of a tungsten carbide-based cemented carbide by physical vapor deposition,
Adjacent to the surface of the cutting tool base, a TiAlN layer having a layer thickness of 0.2 to 2 μm and having a columnar crystal structure with a width of 10 to 100 nm is formed,
Further, with respect to the tungsten carbide crystal grains and TiAlN crystal grains in the cross section of the interface between the cutting tool base and the TiAlN layer, the respective crystal planes and crystal orientations are changed using a field emission scanning electron microscope and an electron beam backscatter diffraction apparatus. Seeking
(A) The [0001] orientation of the tungsten carbide crystal grains and the [110] orientation of the TiAlN crystal grains are parallel, and the [10-10] orientation of the tungsten carbide crystal grains and the [001] orientation of the TiAlN crystal grains are parallel. Let X _A be the interface length of a crystal grain,
(B) The [0001] orientation of the tungsten carbide crystal grains and the [111] orientation of the TiAlN crystal grains are parallel, and the [11-20] orientation of the tungsten carbide crystal grains and the [110] orientation of the TiAlN crystal grains are parallel. the interface length of certain crystal grains in case of the X _C,
At the interface between the cutting tool base surface and the TiAlN layer adjacent thereto,
1> (X _A + X _C ) /X≧0.3,
A surface-coated cutting tool characterized in that a heteroepitaxial interface is formed (where X represents the total length of the interface). "
It has the characteristics.

  In the modified TiAlN layer constituting the hard coating layer adjacent to the surface of the WC carbide substrate of the coated tool of the present invention, the Ti component improves the high temperature strength, Al improves the hardness, and the N component includes Due to the effect of improving the strength of the layer, the modified TiAlN layer has high hardness and excellent strength, and contributes to the improvement of the wear resistance of the coated tool. In the coated tool of the present invention, in addition to this, Furthermore, since a heteroepitaxial interface is formed on the surface of the modified TiAlN layer and the WC carbide substrate, and the adhesion strength between the modified TiAlN layer and the surface of the WC carbide substrate is improved, the fracture resistance of the hard coating layer, The peel resistance and adhesion strength are greatly improved, and the tool life is extended.

When depositing a TiAlN layer on a WC carbide substrate, ion plating using a pressure gradient type Ar plasma gun shown in FIG.
WC carbide substrate temperature: 240-450 ° C.
Plasma gun discharge power: 3kW
Discharge gas flow rate: Argon (Ar) gas 25-40 sccm,
DC bias voltage applied to the tool base: -600V
After pre-processing under the specific conditions
WC carbide substrate temperature: 240-450 ° C.
Evaporation source: Metal Ti, Metal Al
Plasma gun discharge power (for metal Ti): 8-12 kW,
Plasma gun discharge power (relative to metal Al): 6-9 kW,
Reaction gas flow rate: nitrogen _{(N 2)} gas 80～120Sccm,
Discharge gas flow rate: Argon (Ar) gas 55-60 sccm,
DC bias voltage applied to the tool base: 0V
When the modified TiAlN layer is vapor-deposited by adjusting to the specific condition, in the arbitrary cross section perpendicular to the WC carbide substrate surface, the interface between the WC carbide substrate surface and the modified TiAlN layer adjacent thereto is
(A) The [0001] orientation of the tungsten carbide crystal grains and the [110] orientation of the TiAlN crystal grains are parallel, and the [10-10] orientation of the tungsten carbide crystal grains and the [001] orientation of the TiAlN crystal grains are parallel. Let X _A be the interface length of a crystal grain,
(B) The [0001] orientation of the tungsten carbide crystal grains and the [111] orientation of the TiAlN crystal grains are parallel, and the [11-20] orientation of the tungsten carbide crystal grains and the [110] orientation of the TiAlN crystal grains are parallel. the interface length of certain crystal grains in case of the X _C,
1> (X _A + X _C ) /X≧0.3,
(Where X represents the total length of the interface), and an interface having a heteroepitaxial relationship is formed.
When the modified TiAlN layer is observed with a scanning electron microscope, formation of columnar crystal modified TiAlN having a width of 10 to 100 nm and a height of 0.2 to 2 μm is observed.
Further, the width and height of the columnar crystals of the modified TiAlN are particularly affected by the deposition time among the deposition conditions, but the columnar crystals having the width and height are modified by the deposition of 40 to 320 min. Quality TiAlN is formed.
The layer thickness of 0.2 to 2 μm of the modified TiAlN layer corresponds to the columnar crystal height of 0.2 to 2 μm.
Here, if the layer thickness (columnar crystal height) of the modified TiAlN layer is less than 0.2 μm, it is insufficient to ensure the desired adhesion strength, while the layer thickness (columnar crystal height). If the thickness exceeds 2 μm, the columnar crystals become coarse, surface smoothness is lost, and the fracture resistance is lowered. Therefore, the layer thickness (columnar crystal height) of the modified TiAlN layer is 0.2-2 μm. It was determined.

In addition, for the WC crystal grains and TiAlN crystal grains in the cross section of the interface between the cutting tool base and the TiAlN layer, the respective crystal plane alignment is performed by the following procedure using a field emission scanning electron microscope and an electron beam backscatter diffraction apparatus. , Crystal orientation orientation, interface length X _A , interface length X _C , and total interface length X were determined.
That is, after the cross section of the cutting tool base and the TiAlN layer is polished by ion polishing, the WC crystal grains and TiAlN crystal grains on the polished surface are irradiated with an electron beam to determine the regions of the individual WC crystal grains and TiAlN crystal grains. Furthermore, for a pair of WC grains and TiAlN grains adjacent to each other at the interface between the cutting tool base and the TiAlN layer in the measurement region,
(A1) An angle formed by the [10-10] orientation of the WC crystal grains and the [100] orientation of the TiAlN crystal grains,
(A2) An angle formed by the [0001] orientation of the WC crystal grains and the [110] orientation of the TiAlN crystal grains,
(C1) An angle formed by the [11-20] orientation of the WC crystal grains and the [110] orientation of the TiAlN crystal grains,
(C2) An angle formed by the [0001] orientation of the WC crystal grains and the [111] orientation of the TiAlN crystal grains,
When measuring each
(A) The distance along the substrate surface in a specific interface region formed by a pair of WC crystal grains and TiAlN crystal grains in which both the angle obtained in (a1) and the angle obtained in (a2) are 10 degrees or less. measured, the for all satisfy WC crystal grains and TiAlN grains pair of (a), the distance plus the length of the interface region and X _a,
further,
(C) A distance along the substrate surface in a specific interface region formed by a pair of WC crystal grains and TiAlN crystal grains in which both the angle obtained in (c1) and the angle obtained in (c2) are 10 degrees or less. measured, the for all satisfy WC crystal grains and TiAlN grains pair of (C), the distance plus the length of the interface region and X _C, further, the interface of the measured tool substrate and TiAlN layer , X is the length of the entire interface region along the tool base surface.
When calculated based on the values of X _A , X _C , and X obtained in the above measurement, the interface between the WC carbide substrate surface and the TiAlN layer adjacent thereto is as follows:
1> (X _A + X _C ) /X≧0.3,
It is confirmed that a heteroepitaxial interface satisfying the above is formed.
Here, if (X _A + X _C ) / X is smaller than 0.3, the proportion of the heteroepitaxial interface decreases, the fracture starting point of the TiAlN layer increases, and the desired fracture resistance cannot be obtained. The value of X _A + X _C ) / X was determined as 1> (X _A + X _C ) /X≧0.3.

  The coated tool of the present invention has a TiAlN layer so that the crystal planes and crystal orientations of the WC crystal grains and TiAlN crystal grains present at the interface between the WC carbide substrate and the TiAlN layer in contact with the WC carbide substrate satisfy a specific heteroepitaxial relationship. This makes it possible to achieve excellent chipping resistance and resistance even in small-diameter, low-speed cutting processes where welding chipping is likely to occur, or in high-speed heavy cutting processes where high loads are applied to the cutting blade and high loads are applied. It exhibits peelability and adhesion strength, exhibits excellent cutting performance over a long period of use, and contributes to prolonging the tool life.

1 is a schematic view of an ion plating apparatus using a pressure gradient type Ar plasma gun for vapor deposition formation of a modified TiAlN layer of a surface-coated cutting tool of the present invention (a coated drill of the present invention). The schematic diagram of the crystal orientation relationship of the interface vicinity of the WC super hard substrate surface of the surface coating cutting tool of this invention and a modified TiAlN layer is shown. The schematic diagram of the crystal structure and interface length in the layer thickness direction cross section of the vicinity of the interface of the WC super hard substrate surface and the modified TiAlN layer of the surface-coated cutting tool of the present invention is shown.

  Next, the coated tool of the present invention will be specifically described with reference to examples.

As raw material powders, WC powder, TiC powder, VC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, and Co powder, all having an average particle diameter of 1 to 3 μm, were prepared. And then wet-mixed with a ball mill for 72 hours, dried, and press-molded into a green compact at a pressure of 100 MPa. The green compact was vacuumed at 6 Pa at a temperature of 1400 ° C. for 1 hour. Sintering is performed under the holding conditions, and after sintering, the cutting edge part is subjected to a honing process of R: 0.03 to form WC carbide substrates A-1 to A-10 having an ISO standard / CNMG120408 insert shape. did.

Next, the WC carbide substrates A-1 to A-10 were ultrasonically washed in acetone and dried, and then mounted on an ion plating apparatus using a pressure gradient type Ar plasma gun shown in FIG. First, metal Ti and metal Al are mounted as evaporation sources, and first, the inside of the apparatus is evacuated and maintained at a vacuum of 1.0 × 10 ⁻³ Pa or less, and Ar gas is introduced to 2.3 × 10 ⁻ After setting the pressure to ² Pa, the discharge power of the pressure gradient type Ar plasma gun is set to 3 kW, the plasma beam is irradiated into the chamber to ionize Ar, and a bias voltage of −600 V is applied to the WC cemented carbide substrate. WC cemented carbide substrate was Ar bombardment for 10 minutes, then, after once 1 × ¹⁰ -3 Pa vacuum of about in the apparatus, of the pressure gradient type Ar plasma gun, plasma to Ti The discharge power of cancer 10～12KW, and 8kW the discharge power of the plasma gun relative to Al, the Ar gas 45 sccm, while passing 100sccm of nitrogen gas, the pressure in the furnace to ^{3 × 10 -2 ~6 × 10 -2} Pa Then, a plasma beam is incident on the evaporation source to generate vapors of metal Ti and metal Al and ionize with the plasma beam, and the target layer thickness shown in Table 3 is changed to the surface of the WC carbide substrate maintained at a predetermined temperature. The coated inserts 1 to 10 of the present invention as the coated tool of the present invention were manufactured by vapor-depositing a high quality TiAlN layer as a hard coated layer.
Table 2 shows various conditions for ion plating using a pressure gradient type Ar plasma gun, which are conditions for forming the modified TiAlN layers of the coated inserts 1 to 10 of the present invention.

  For the purpose of comparison, the WC carbide substrates A-1 to A-10 are ultrasonically cleaned in acetone and dried, and attached to a normal arc ion plating apparatus as a cathode electrode (evaporation source). Attach metal Ti and metal Al, and first heat the interior of the apparatus to 500 ° C. with a heater while evacuating the apparatus and maintaining a vacuum of 0.1 Pa or less, then introduce Ar gas, 0.7 Pa At the same time, a DC bias voltage of −200 V was applied to the WC carbide substrate, the surface of the WC carbide substrate was treated with Ar bombardment, and then nitrogen gas was introduced into the apparatus as a reaction gas to generate a reaction atmosphere of 3 Pa. In addition, a DC bias voltage of −50 V is applied to the WC carbide substrate, and a current of 120 A is passed between the cathode electrode and the anode electrode of the metal Ti and metal Al to discharge the arc. Thus, conventional coated inserts 1 to 10 as conventional coated tools are manufactured by depositing a conventional TiAlN layer having a target layer thickness shown in Table 4 on the surface of the WC carbide substrate as a hard coated layer, respectively. did.

For reference, the WC carbide substrates A-1 to A-5 were ultrasonically cleaned in acetone and dried, and then the WC carbide substrates A-1 to A-5 were subjected to normal chemical vapor deposition (CVD). ) Install in the device,
Reaction gas composition: volume%, TiCl ₄ : 2.2%, AlCl ₃ : 2.5%, N ₂ : 30%, H ₂ : remaining,
Reaction atmosphere temperature: 900 ° C.
Reaction atmosphere pressure: 30 kPa,
Under these conditions, TiAlN layers (hereinafter referred to as chemical vapor deposition TiAlN layers) formed by CVD were vapor-deposited with the target layer thicknesses shown in Table 5 to produce reference coating inserts 1 to 5 as reference coating tools.
Regarding the modified TiAlN layer of the present invention coated inserts 1 to 10, the conventional TiAlN layer of the conventional coated inserts 1 to 10 and the chemical vapor deposited TiAlN layer of the reference coated inserts 1 to 5, the layer thickness and the size of the columnar crystals are determined by scanning electron. It measured by observing the torn surface of a film | membrane using the microscope (Carl Zeiss Ultra55). This measurement is an average value of five-point measurement.
Each measured value was shown to Tables 3-5.

  Further, the vicinity of the interface between the WC cemented carbide substrate of the present invention coated inserts 1 to 10 and the modified TiAlN layer, the vicinity of the interface between the WC cemented carbide substrate of the conventional coated inserts 1 to 10 and the conventional TiAlN layer, and the reference coated insert Using a field emission scanning electron microscope and an electron beam backscattering diffraction device, the crystal plane arrangement and crystal orientation of WC crystal grains and TiAlN crystal grains in the vicinity of the interface between 1 to 5 WC carbide substrate and chemical vapor deposition TiAlN layer Measured.

FIG. 2 shows, as an example, a schematic diagram showing the crystal plane arrangement and crystal orientation of WC crystal grains and TiAlN crystal grains in the vicinity of the interface between the cemented carbide substrate and the modified TiAlN layer for the coated insert 1 of the present invention. .
The specific measurement procedure is as follows.
That is, after the cross section of the cutting tool base and the TiAlN layer is polished by ion polishing, it is set in a lens barrel of a field emission scanning electron microscope, and an electron beam with an acceleration voltage of 10 kV is applied to the polished surface at an incident angle of 70 degrees. Irradiate each TiN crystal grain existing within the measurement range of each surface polished surface with an irradiation current of 1.8 nA, and use an electron backscatter diffraction image apparatus, centering on the interface and having a width substantially parallel to the interface. The normal of the polished surface for each of the [10-10] and [0001] orientations of the individual WC crystal grains in the region of 30 μm and the height of 3 μm and the [100] and [110] orientations of the TiAlN crystal grains And an arbitrary angle orthogonal to the normal line and an inclination angle between the normal line and the direction orthogonal to the arbitrary direction are measured at intervals of 0.02 μm / step, and further, cutting in the measurement region is performed. For pairs of adjacent WC crystal grains and TiAlN grains at the interface of the tool substrate and TiAlN layer,
(A1) An angle formed by the [10-10] orientation of the WC crystal grains and the [100] orientation of the TiAlN crystal grains,
(A2) An angle formed by the [0001] orientation of the WC crystal grains and the [110] orientation of the TiAlN crystal grains,
(C1) An angle formed by the [11-20] orientation of the WC crystal grains and the [110] orientation of the TiAlN crystal grains,
(C2) An angle formed by the [0001] orientation of the WC crystal grains and the [111] orientation of the TiAlN crystal grains,
When measuring each
(A) The distance along the substrate surface in a specific interface region formed by a pair of WC crystal grains and TiAlN crystal grains in which both the angle obtained in (a1) and the angle obtained in (a2) are 10 degrees or less. measured, the for all satisfy WC crystal grains and TiAlN grains pair of (a), the distance plus the length of the interface region and X _a,
further,
(C) A distance along the substrate surface in a specific interface region formed by a pair of WC crystal grains and TiAlN crystal grains in which both the angle obtained in (c1) and the angle obtained in (c2) are 10 degrees or less. measured, the for all satisfy WC crystal grains and TiAlN grains pair of (C), the distance plus the length of the interface region and X _C,
Furthermore, the length of the entire interface region along the tool substrate surface at the measured interface between the tool substrate and the TiAlN layer was X.
The [0001] orientation of the tungsten carbide crystal grains and the [110] orientation of the TiAlN crystal grains determined by the measurement are parallel, and the [10-10] orientation of the tungsten carbide crystal grains and the [001] orientation of the TiAlN crystal grains are The interface length X _A of the parallel crystal grains,
and,
[0001] orientation of tungsten carbide crystal grains and [111] orientation of TiAlN crystal grains are parallel, and [11-20] orientation of tungsten carbide crystal grains and [110] orientation of TiAlN crystal grains are parallel. Interface length X _C ,
From the value of
Value of (X _A + X _C ) / X (where X is the total length of the interface)
The value of was calculated.
These values are shown in Tables 3 to 5, respectively.

From Table 3, the modified TiAlN layers of the coated inserts 1-10 of the present invention have columnar crystals with a width of 10 to 100 nm and a height of 0.2 to 2 μm, and between the WC carbide substrate and the modified TiAlN layer. ,
1> (X _A + X _C ) /X≧0.3,
It can be seen that a heteroepitaxial interface satisfying the above is formed.
On the other hand, from Table 4, the conventional TiAlN layer of the conventional coated inserts 1 to 10 has columnar crystals with a width of 100 to 500 nm and a height of 0.2 to 2.0 μm, but the WC carbide substrate and the conventional TiAlN interlayer In
1> (X _A + X _C ) /X≧0.3,
It can be seen that the heteroepitaxial interface satisfying the above is not formed, and the adhesion strength is insufficient.
Also from Table 5, the chemical vapor deposition TiAlN layers of the reference coating inserts 1 to 5
1> (X _A + X _C ) /X≧0.3,
It can be seen that the heteroepitaxial interface satisfying the above is not formed, and the adhesion strength is insufficient.

Next, welding chipping of the present invention coated inserts 1 to 10, the conventional coated inserts 1 to 10 and the reference coated inserts 1 to 5 are screwed to the tip of the tool steel tool with a fixing jig. A turning test was conducted under the following conditions assuming small diameter part machining that is likely to occur.
Work material: JIS / S25C round bar,
Cutting speed: 80 m / min. ,
Cutting depth: 2mm,
Feed: 0.1 mm / rev. ,
Cutting time: 45 minutes,
Carbon steel dry low-speed continuous cutting test under the following conditions (normal cutting speed and feed are 250 m / min. And 0.6 mm / rev., Respectively),
The flank wear width of the cutting blade was measured.
The measurement results of the cutting test are shown in Table 6.

From the results shown in Tables 3 to 6, in the coated inserts 1 to 10 of the present invention, the modified TiAlN layer is composed of columnar crystals having a width of 10 to 100 nm and a height of 0.2 to 2 μm, and further, field emission type scanning electrons When the crystal plane alignment and crystal orientation are measured with a microscope and an electron beam backscatter diffraction apparatus, a specific heteroepitaxial interface is formed at the interface between the WC carbide substrate and the modified TiAlN layer. Since it has excellent adhesion strength, it exhibits excellent chipping resistance and peeling resistance under small-diameter low-speed cutting conditions where welding chipping is likely to occur, and exhibits excellent cutting performance over a long period of use. The tool life can be extended.
On the other hand, in the conventional coated inserts 1 to 10 and the reference coated inserts 1 to 5, since the formation of a specific heteroepitaxial interface is not sufficient, a defect occurs under low-speed machining conditions of small diameter or small parts that are likely to cause welding chipping. It is clear that the service life is reached in a relatively short time due to peeling or the like.

As raw material powders, WC powder having an average particle size of 0.2 μm, 2.3 μm Cr ₃ C ₂ powder, 1.5 μm VC powder, and 1.8 μm Co powder were prepared. 7 and added to wax, ball mill mixed in acetone for 24 hours, dried under reduced pressure, press-molded into various compacts of a predetermined shape at a pressure of 100 MPa, and these compacts The body is heated to a predetermined temperature in the range of 1370 to 1470 ° C. at a heating rate of 7 ° C./min in a vacuum atmosphere of 6 Pa, held at this temperature for 1 hour, and then sintered under furnace cooling conditions. Then, a tool bar forming round bar sintered body is formed, and from this round bar sintered body, a groove forming portion diameter × length of 6 mm × 81 mm and a twist angle of 30 degrees are obtained by grinding. WC carbide substrate (drill) D-1 to D- with blade shape It was prepared.

  Next, the WC carbide substrates D-1 to D-4 were ultrasonically washed in acetone and dried, and then mounted on an ion plating apparatus using a pressure gradient type Ar plasma gun shown in FIG. In the same manner as in Example 1, a modified TiAlN layer having a target layer thickness shown in Table 8 is formed by vapor deposition as a hard coating layer. 1-8 were produced.

  For the purpose of comparison, the WC carbide substrates D-1 to D-4 were ultrasonically cleaned in acetone and dried and mounted on a normal arc ion plating apparatus. Thus, conventional coated drills 1 to 8 as conventional coated tools were manufactured by vapor-depositing a conventional TiAlN layer having a target layer thickness shown in Table 9 as a hard coating layer.

  For reference, the WC carbide substrates D-1 to D-4 are ultrasonically cleaned in acetone and dried, and then the WC carbide substrates D-1 to D-4 are subjected to normal chemical vapor deposition (CVD) equipment. A hard coating layer comprising a chemical vapor deposition TiAlN layer having a target layer thickness shown in Table 10 was formed by vapor deposition of a chemical vapor deposition TiAlN layer by a CVD method in the same manner as in Example 1 Reference coated drills 1 to 4 as coated tools were manufactured.

Regarding the modified TiAlN layer of the present invention coated drills 1-8, the conventional TiAlN layer of the conventional coated drills 1-8, and the chemical vapor deposited TiAlN layer of the reference coated drills 1-4, the layer thickness, the size of the columnar crystals, the examples Measurement was performed in the same manner as in 1.
Each measured value was shown to Tables 8-10.

Furthermore, the vicinity of the interface between the WC carbide substrate of the inventive coated drills 1-8 and the modified TiAlN layer, the vicinity of the interface between the WC carbide substrate of the conventional coated drills 1-8 and the conventional TiAlN layer, and a reference coated drill In the same manner as in Example 1, field emission scanning electrons were also used for the crystal plane arrangement and crystal orientation of the WC crystal grains and TiAlN crystal grains in the vicinity of the interface between the WC carbide substrate of 1-4 and the chemical vapor deposition TiAlN layer. X _A , X _C , and X were measured using a microscope and an electron beam backscatter diffractometer, and the value of (X _A + X _C ) / X was determined.
These values are shown in Tables 8 to 10, respectively.

From Table 8, the modified TiAlN layer of the present invention coated drills 1 to 8 has columnar crystals with a width of 10 to 100 nm and a height of 0.2 to 2 μm, and between the WC carbide substrate and the modified TiAlN layer. ,
1> (X _A + X _C ) /X≧0.3,
It can be seen that a heteroepitaxial interface satisfying the above is formed.
On the other hand, from Table 9, the conventional TiAlN layer of the conventional coated drills 1 to 8 has columnar crystals with a width of 100 to 500 nm and a height of 0.2 to 2.0 μm, but the WC carbide substrate and the conventional TiAlN interlayer In
1> (X _A + X _C ) /X≧0.3,
It can be seen that the heteroepitaxial interface satisfying the above is not formed, and the adhesion strength is insufficient.
Similarly, from Table 10, the chemical vapor deposition TiAlN layers of the reference coated drills 1 to 4
1> (X _A + X _C ) /X≧0.3,
It can be seen that the heteroepitaxial interface satisfying the above is not formed, and the adhesion strength is insufficient.

Next, about the said invention coated drills 1-8, the conventional coated drills 1-8, and the reference coated drills 1-4,
Work material-planar dimensions: 100 mm × 250 mm, thickness: 50 mm, JIS / S25C plate,
Cutting speed: 100 m / min. ,
Feed: 0.40 mm / rev. ,
Hole depth: 10mm,
Wet high-speed drilling test of carbon under the following conditions (normal cutting speed and feed are 85 m / min. And 0.20 mm / rev., Respectively),
(Using water-soluble cutting oil), and the number of drilling operations was measured until the flank wear width of the cutting edge surface reached 0.3 mm.
The measurement results are shown in Table 11, respectively.

From the results shown in Tables 3, 6, 8, and 11, the coated inserts 1 to 10 and the coated drills 1 to 8 of the present invention are columnar with a modified TiAlN layer having a width of 10 to 100 nm and a height of 0.2 to 2 μm. In addition, when the crystal plane alignment and crystal orientation are measured by a field emission scanning electron microscope and an electron beam backscatter diffraction device, the interface between the WC carbide substrate and the modified TiAlN layer is specified. As a result, it has excellent adhesion strength, so it has excellent fracture resistance even under conditions of small diameter low-speed cutting or high-speed heavy cutting, where welding chipping is likely to occur. It exhibits peeling resistance, exhibits excellent cutting performance over a long period of use, and extends the tool life.
On the other hand, from the results shown in Tables 4-6 and 9-11, in the conventional coated inserts 1-10, the reference coated inserts 1-5, the conventional coated drills 1-8, and the reference coated drills 1-4 Because the formation of a specific heteroepitaxial interface is not sufficient, the service life is shortened in a relatively short time due to defects, delamination, etc. under small diameter low speed cutting conditions or high speed heavy cutting conditions where welding chipping is likely to occur. It is clear that

  As described above, the coated tool of the present invention has high adhesion strength between the WC cemented carbide substrate and the modified TiAlN layer formed adjacent to the WC cemented carbide substrate. When used in high-speed heavy cutting where a high load acts on the blade, it exhibits excellent fracture resistance and peeling resistance, and can be used as various coated tools such as coated inserts and coated drills. This can prevent the occurrence of chipping and delamination of the hard coating layer, so that it is possible to respond satisfactorily to cost reductions, exhibit excellent cutting performance over a long period of time, and extend the tool life. Can be realized.

1: Modified TiAlN layer 2: Tool substrate 3: Measurement range of 30 μm in width and 3 μm in height parallel to 3 centering on a substantially flat surface 4: 3 of the tool substrate surface 5: [0001] orientation of tungsten carbide crystal grains And the [110] orientation of TiAlN crystal grains and the [10-10] orientation of tungsten carbide crystal grains and the [001] orientation of TiAlN crystal grains are parallel to the interface length X _A
6: The [0001] orientation of the tungsten carbide crystal grain and the [111] orientation of the TiAlN crystal grain are parallel, and the [11-20] orientation of the tungsten carbide crystal grain and the [110] orientation of the TiAlN crystal grain are parallel. Crystal interface length X _C
7 (solid line in 4): Total interface length X

Claims (1)

A surface-coated cutting tool in which a hard coating layer including at least a TiAlN layer is formed by physical vapor deposition on the surface of a cutting tool base made of a tungsten carbide-based cemented carbide,
Adjacent to the surface of the cutting tool base, a TiAlN layer having a layer thickness of 0.2 to 2 μm and having a columnar crystal structure with a width of 10 to 100 nm is formed,
Further, with respect to the tungsten carbide crystal grains and TiAlN crystal grains in the cross section of the interface between the cutting tool base and the TiAlN layer, the respective crystal planes and crystal orientations are changed using a field emission scanning electron microscope and an electron beam backscatter diffraction apparatus. Seeking
(A) The [0001] orientation of the tungsten carbide crystal grains and the [110] orientation of the TiAlN crystal grains are parallel, and the [10-10] orientation of the tungsten carbide crystal grains and the [001] orientation of the TiAlN crystal grains are parallel. Let X _A be the interface length of a crystal grain,
(B) The [0001] orientation of the tungsten carbide crystal grains and the [111] orientation of the TiAlN crystal grains are parallel, and the [11-20] orientation of the tungsten carbide crystal grains and the [110] orientation of the TiAlN crystal grains are parallel. the interface length of certain crystal grains in case of the X _C,
At the interface between the cutting tool base surface and the TiAlN layer adjacent thereto,
1> (X _A + X _C ) /X≧0.3,
A surface-coated cutting tool characterized in that a heteroepitaxial interface is formed (where X represents the total length of the interface).

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