JP2014018886A - Surface coated cutting tool with hard coating layer exhibiting superior initial conformability and chipping resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coated tool with a hard coating layer having superior initial conformability in high-speed intermittent cutting work, and consequently exhibiting excellent chipping resistance and breakage resistance over a long period of use.SOLUTION: A hard coating layer consists of a lower layer and an upper layer that are chemically vapor-deposited. In the hard coating layer, (a) the lower layer consists of one layer or two or more layers out of a Ti carbide layer, a nitride layer, a carbonitride layer, a carbonate layer, and a carbonitroxide layer, and is a Ti compound layer having a total average layer thickness of 3-20 μm; and (b) the upper layer is an aluminium oxide layer including an α type crystalline structure having an average layer thickness of 3-25 μm, and the upper layer includes a flat surface composition having a carbon content of 0.1-5 at% in a region at a depth equivalent to an average layer thickness of 5-10% from a surface side, a chlorine content of 0.05 at% or less, and surface roughness Ra within a range of 0.05-0.2 μm.

Description

  In the present invention, in the high-speed intermittent cutting of various steels and cast irons that are accompanied by high heat generation and intermittent / impact loads are applied to the cutting edge, the hard coating layer has excellent initial conformability, thereby enabling chipping ( The present invention relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) that prevents occurrence of microchips and exhibits excellent cutting performance over a long period of use.

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 also referred to as TiN) layer, carbonitride (hereinafter referred to as TiCN) layer formed by chemical vapor deposition of the lower layers. A Ti compound layer consisting of 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 the above (a) and (b) is known, and this coated tool is suitably used for continuous cutting and intermittent cutting of various types of steel and cast iron. It is known.
However, the above-described coated tool has a problem that chipping is likely to occur under high-speed intermittent cutting conditions in which a heavy load is applied to the cutting edge, and there is a problem that the tool life is short. Proposals have been made.

For example, Patent Document 1 discloses that on the surface of a tool base, (a) a Ti compound layer as a lower layer, (b) an α-type Al ₂ O ₃ layer as an intermediate layer, and (c) a flat plate polygonal and vertically long shape as an upper layer. In the surface-coated cutting tool formed by vapor-depositing a hard coating layer composed of a Zr-containing α-type Al ₂ O ₃ layer having a crystal grain structure of the above, the intermediate layer and the upper layer are each α having a high (0001) plane orientation ratio. Type Al ₂ O ₃ layer and Zr-containing α-type Al ₂ O ₃ layer, and the inside of the crystal grains having an area ratio of 60% or more among the crystal grains of the upper layer is represented by at least one Σ3. It is disclosed that the hard coating layer exhibits excellent chipping resistance even in high-speed intermittent cutting by being divided by a crystal lattice interface composed of the constituent atomic shared lattice points.

Further, in Patent Document 2, a surface-coated cemented carbide cutting tip has (a) an average layer thickness of 1.5 to 20 μm on the surface of a WC-based cemented carbide substrate, and a TiC layer and a TiN layer. An inner layer of a Ti compound layer composed of one or more of TiCN layer, Ti ₂ O ₃ layer, TiCO layer, TiNO layer, and TiCNO layer, and (b) having an average layer thickness of 1 to 20 μm And, on the surface side, from the surface to the depth corresponding to 10 to 40% of the average layer thickness, the Al ₂ O ₃ substrate accounts for 1 to 15 wt% in the total amount with Al ₂ O ₃ % Of ZrO _{2 as} well as a toughened lubrication zone having a structure in which 1 to 15% by weight of free carbon (however, the total amount of ZrO ₂ and free carbon is 20% by weight or less) is dispersed and distributed. an outer layer side consists essentially of _Al 2 _{O 3,} optionally (c) 0. Excellent initial conformability by chemical vapor deposition and / or physical vapor deposition of a hard coating layer composed of an outermost layer of TiN layer having an average layer thickness of ˜5 μm and an overall average layer thickness of 3 to 35 μm It is disclosed that even if the cutting is performed under heavy cutting conditions such as high cutting and high feed, chipping does not occur on the cutting edge and excellent cutting performance is exhibited over a long period of time.

  Further, Patent Document 3 is a wear-resistant film that is formed on a substrate and has a surface layer made of a metal nitride, and on the surface layer, an outermost layer that covers the surface layer is provided, and the outermost layer is It is disclosed that by using alumina in which carbon is dissolved, wear resistance is exhibited even at high temperatures.

JP 2010-110833 A JP 2000-246508 A JP 2008-126334 A

  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, which involves high heat generation and more intermittent and impact loads on the cutting edge, the surface flatness of the upper layer is poor and the initial cutting time is low. Since the conformability 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.

  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 initial conformability and, as a result, excellent chipping resistance and fracture resistance over a long period of use, the following knowledge was obtained.

  That is, in the case where the conventional upper layer made of aluminum oxide is formed as the hard coating layer, the aluminum oxide is formed in a columnar shape in the vertical direction as a base. Therefore, although the wear resistance is improved, on the other hand, the flatness of the surface portion of the aluminum oxide is lowered. As a result, the chipping resistance and fracture resistance could not be exhibited, and the tool life could not be satisfied.

Therefore, the present inventors have conducted intensive research on the aluminum oxide layer that constitutes the upper layer of the hard coating layer, and when forming an Al ₂ O ₃ crystal having an α-type crystal structure, as in the conventional case, AlCl 2 is used. _{3 is formed} by a CVD method, but a flat surface structure can be obtained by forming a film using only trimethylaluminum (Al (CH ₃ ) ₃ ) (hereinafter referred to as TMA). I got the knowledge.

Further, it was found that the surface portion was formed using TMA, so that the surface portion contained almost no Cl derived from AlCl ₃ and contained C derived from TMA. And the knowledge that the hard coating layer excellent in initial conformability was obtained by prescribing | regulating Cl content and C content in this surface part was acquired.

  It has also been found that the initial conformability can be further improved by forming an outermost layer made of an amorphous aluminum oxide layer on the upper layer.

The aluminum oxide layer having the above-described configuration can be formed by, for example, the following chemical vapor deposition method.
A predetermined total consisting of one or more of a Ti carbide layer, a nitride layer, a carbonitride layer, a carbonate layer and a carbonitride oxide layer on the surface of the tool substrate using a normal vapor deposition method. After forming a lower layer composed of a Ti compound layer having an average layer thickness, the reaction gas composition (volume%) was changed to AlCl ₃ : 2.0 to 3.0%, CO ₂ : 4.0 to 6.0%, HCl _{: 2.0~3.0%, H 2 S:} 0.1~0.5%, H 2: remainder, as the reaction atmosphere pressure, as 6～8KPa, the reaction atmosphere temperature, a 900 to 1000 ° C. Then, an aluminum oxide layer having an α-type crystal structure having a predetermined average layer thickness is formed by performing chemical vapor deposition for a predetermined time. Thereafter, the reaction gas composition (volume%) is set to TMA: 0.1 to 0.5%, O ₂ : 5.0 to 10.0%, Ar: remaining, and the reaction atmosphere pressure is set to 2 to 5 kPa. A depth region corresponding to 5 to 10% of the average layer thickness on the surface side of the aluminum oxide layer having the α-type crystal structure by performing a chemical vapor deposition method at a reaction atmosphere temperature of 820 to 950 ° C. for a predetermined time. Surface having a surface roughness Ra in the range of 0.05 to 0.2 μm, with a carbon content of 0.1 to 5 at% and a chlorine content of 0.05 at% or less An upper layer constituting a region having a flat structure is formed. Thereby, it was confirmed that the initial conformability of the hard coating layer was improved, and as a result, chipping resistance and chipping resistance could be improved.

  Furthermore, the present inventors have confirmed that initial conformability is further improved by providing an outermost layer made of an amorphous aluminum oxide layer having a predetermined average layer thickness on the upper layer.

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,
The hard coating layer is composed of a lower layer and an upper layer chemically vapor-deposited,
(A) The lower layer is composed of one or more of a Ti carbide layer, a nitride layer, a carbonitride layer, a carbonate layer, and a carbonitride layer, and a total of 3 to 20 μm. A Ti compound layer having an average layer thickness;
(B) The upper layer is an aluminum oxide layer having an α-type crystal structure having an average layer thickness of 2 to 25 μm,
The upper layer (b) has a carbon content of 0.1 to 5 at% in a depth region corresponding to 5 to 10% of the average layer thickness of the upper layer from the surface side, and a chlorine content. A surface-coated cutting tool having a surface flat structure having a surface roughness Ra in a range of 0.05 to 0.2 μm and having a surface roughness Ra of 0.05 at% or less.
(2) The upper layer of (b) has two phases having different carbon and chlorine contents in a depth region corresponding to 5 to 10% of the average layer thickness from the surface side. Is the region A phase and the region B phase, α _C / β _C which is the ratio of the average carbon content α _C of the region A phase and the average carbon content β _C of the region B phase is 5 or more, and the region B The surface-coated cutting tool according to (1), wherein β _Cl / α _Cl, which is a ratio of the average chlorine content β _Cl of the phase and the average chlorine content α _Cl of the region A phase, is 5 or more.
(3) In a surface-coated cutting tool in which a hard coating layer is provided on the surface of a tool base made of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet,
The hard coating layer comprises a lower layer, an upper layer and an outermost layer, which are chemically vapor-deposited,
(C) The lower layer is composed of one or more of a Ti carbide layer, a nitride layer, a carbonitride layer, a carbonate layer and a carbonitride layer, and a total of 3 to 20 μm. A Ti compound layer having an average layer thickness;
(D) The upper layer is an aluminum oxide layer having an α-type crystal structure having an average layer thickness of 2 to 25 μm,
(E) the outermost layer is an amorphous aluminum oxide layer having an average layer thickness of 0.5 to 5 μm;
The upper layer (d) has a carbon content of 0.1 to 5 at% in a depth region corresponding to 5 to 10% of the average layer thickness of the upper layer from the interface between the upper layer and the outermost layer. The content of chlorine is 0.05 at% or less, and the outermost layer of (e) has a surface flat structure having a surface roughness Ra in the range of 0.05 to 0.2 μm. A surface-coated cutting tool.
(4) The upper layer of (d) has a carbon and chlorine content in a depth region corresponding to 5 to 10% of the average layer thickness of the upper layer from the interface between the upper layer and the outermost layer. When two different phases exist, and these two phases are the region A phase and the region B phase, α is a ratio of the average carbon content α _C of the region A phase and the average carbon content β _C of the region B phase. _{C /} beta _C is 5 or more, and wherein the ratio a is beta _{Cl /} alpha _Cl with an average chlorine content alpha _Cl average area B phase chlorine content beta _Cl and region a phase is 5 or more The surface-coated cutting tool according to (3). "
It has the characteristics.

  The present invention will be described in detail below.

Lower Ti compound layer:
Ti compound layer composed of one or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer and carbonitride oxide layer, and having a total average layer thickness of 3 to 20 μm The lower layer can be formed under normal chemical vapor deposition conditions. 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. It has an effect of firmly adhering, and thus contributing to an improvement in the adhesion of the hard coating layer to the tool substrate. However, when the total average layer thickness is less than 3 μm, the above-mentioned effect cannot be exhibited sufficiently, while the total When the average layer thickness exceeds 20 μm, chipping tends to occur. Therefore, the total average layer thickness is set to 3 to 20 μm.

Aluminum oxide layer having an α-type crystal structure in the upper layer:
It is well known that the aluminum oxide layer having an α-type crystal structure constituting the upper layer has high-temperature hardness and heat resistance. However, if the average layer thickness is less than 2 μm, the aluminum oxide layer has a long-term use. Wear resistance cannot be ensured. On the other hand, if the average layer thickness exceeds 25 μm, the aluminum oxide crystal grains are likely to be coarsened. As a result, in addition to the decrease in high-temperature hardness and strength, high-speed intermittent cutting Since the chipping resistance and chipping resistance at the time are lowered, the average layer thickness is set to 2 to 25 μm.

  Furthermore, in addition to the above-described configuration, the present invention exhibits a further excellent effect when it has the following conditions.

That is, the aluminum oxide layer of the upper layer has a carbon content of 0.1 to 5 at% and a chlorine content of 0.05 at in a depth region corresponding to 5 to 10% of the average layer thickness from the surface side. %, And the surface roughness Ra is a structure having a flat surface structure in the range of 0.05 to 0.2 μm, the initial conformability is improved and the occurrence of chipping is prevented. If the depth region is less than 5%, the desired excellent initial conformability cannot be ensured. If the depth region exceeds 10%, the wear resistance over a long period of use, which is a feature of the aluminum oxide layer, is secured. Can not do it. Further, if the carbon content is 0.1 at% or less in the depth region on the surface side, the lubrication effect of carbon is not exhibited, so that sufficient initial conformability cannot be obtained, and if it exceeds 5 at%, The hardness in the depth region is lowered, the progress of local wear is promoted, and the desired wear resistance cannot be ensured. Further, if the chlorine content exceeds 0.05 at% in the depth region on the surface side, embrittlement occurs in the depth region, and chipping is likely to occur. Further, if the surface roughness Ra is out of the range of 0.05 to 0.2 μm, the effect of suppressing the occurrence of welding to the surface-coated tool at the time of cutting is not exhibited immediately after the start of cutting, so that sufficient chipping resistance is exhibited. Not.
Further, the upper layer has two phases having different carbon and chlorine contents in a depth region corresponding to 5 to 10% of the average layer thickness from the surface side, and the two phases are divided into a region A phase and a region. Assuming that it is the B phase, α _C / β _C which is the ratio of the average carbon content α _C of the region A phase and the average carbon content β _C of the region B phase is 5 or more, and the average chlorine content of the region B phase When β _Cl / α _Cl, which is a ratio of β _{Cl to} the average chlorine content α _Cl of the region A phase, is 5 or more, the carbon content is relatively high and the chlorine content is relatively low. By forming the region, the reduction in hardness is prevented while exhibiting the lubrication effect of carbon, and as a result, the initial conformability is improved and excellent wear resistance is exhibited. However, α _C / β _C, which is the ratio of the average carbon content α _C of the region A phase and the average carbon content β _C of the region B phase, is less than 5, and the average chlorine content β _{Cl of} the region B phase is If β _Cl / α _Cl, which is a ratio to the average chlorine content α _{Cl in the} region A phase, is less than 5, the above characteristics cannot be obtained.

Outermost amorphous aluminum oxide layer:
The present invention exerts a desired effect by the above-described hard coating layer composed of the lower layer and the upper layer, but by further forming an amorphous aluminum oxide layer as the outermost layer on the upper layer, the initial stage is further improved. The conformability is improved and the occurrence of chipping is further prevented.
The outermost layer is made of an amorphous aluminum oxide layer, and if the average layer thickness is less than 0.5 μm, the effect of improving chipping resistance due to the high toughness of amorphous aluminum oxide cannot be exhibited. Since the layer thickness of the aluminum oxide layer having the α-type crystal structure constituting the film becomes too thin and sufficient wear resistance cannot be maintained, the average layer thickness is determined to be 0.5 to 5 μm.
At this time, the surface of the outermost layer has a structure having a flat surface structure with a surface roughness Ra in the range of 0.05 to 0.2 μm, thereby further improving the initial conformability and further preventing the occurrence of chipping. Is done.

Formation of top layer aluminum oxide:
The upper layer aluminum oxide of the present invention can be formed by performing chemical vapor deposition under the following conditions.
A predetermined total consisting of one or more of a Ti carbide layer, a nitride layer, a carbonitride layer, a carbonate layer and a carbonitride oxide layer on the surface of the tool substrate using a normal vapor deposition method. After forming a lower layer composed of a Ti compound layer having an average layer thickness,
Reaction gas composition (volume%):
AlCl ₃ : 2.0 to 3.0%,
CO _2: 4.0~6.0%,
HCl: 2.0-3.0%
H ₂ S: 0.1 to 0.5%, H ₂ : remaining,
Reaction atmosphere pressure: 6-8 kPa,
Reaction atmosphere temperature: 900-1000 ° C
Then, an aluminum oxide layer having an α-type crystal structure corresponding to 90 to 95% of a predetermined average layer thickness is formed by performing chemical vapor deposition.

after that,
Reaction gas composition (volume%):
TMA: 0.1-0.5%
O _2: 5.0~10.0%,
Ar: remaining,
Reaction atmosphere pressure: 2 to 5 kPa,
Reaction atmosphere temperature: 820-950 ° C
In the depth region corresponding to 5 to 10% of the average layer thickness on the surface side of the aluminum oxide layer having the α-type crystal structure by performing chemical vapor deposition, the carbon content is 0.1 to An upper portion in which a surface region having a surface flat structure having a surface roughness of 5 at%, a chlorine content of 0.05 at% or less, and a surface roughness Ra in the range of 0.05 to 0.2 μm is formed. Form a layer.

Formation of the outermost amorphous aluminum oxide layer:
Reaction gas composition (volume%):
TMA: 2.0-5.0%,
O _2: 15.0~20.0%,
Ar: remaining,
Reaction atmosphere pressure: 5 to 8 kPa,
Reaction atmosphere temperature: 780-800 ° C
As described above, an amorphous aluminum oxide layer having a predetermined average layer thickness is formed by performing a chemical vapor deposition method at a relatively low reaction atmosphere temperature.

The coated tool of the present invention comprises a lower layer and an upper layer in which a hard coating layer is chemically vapor-deposited. (A) The lower layer includes a Ti carbide layer, a nitride layer, a carbonitride layer, a carbonate layer, and Ti compound layer comprising one or more of carbonitride oxide layers and having a total average layer thickness of 3 to 20 μm, (b) the upper layer has an average layer thickness of 2 to 25 μm The upper layer of (b) is a depth region corresponding to 5 to 10% of the average layer thickness from the surface side, and the carbon content is 0.1 to 5 at%. And having a flat surface structure with a chlorine content of 0.05 at% or less and a surface roughness Ra in the range of 0.05 to 0.2 μm, the hard coating layer has excellent initial conformability. High-speed intermittent cutting with intermittent and shocking high loads acting on the cutting edge Even with chipping resistance, excellent breakage resistance, resulting in maintaining a good cutting performance over a long period of use, in which the life of the coated tool is achieved.

It is a film | membrane structure schematic diagram which shows the film | membrane structure of this invention.

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

As raw material powders, WC powder, TiC powder, ZrC powder, VC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, TiN powder, and Co powder each having an average particle diameter of 1 to 3 μm are prepared. The raw material powder is blended in the blending composition shown in Table 1, added with wax, ball mill mixed in acetone for 24 hours, dried under reduced pressure, and press-molded into a green compact of a predetermined shape at a pressure of 98 MPa. The green compact is vacuum-sintered in a vacuum of 5 Pa at a predetermined temperature within a range of 1370 to 1470 ° C. for 1 hour. 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 · CNMG120212 were manufactured.

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. After sintering, the cutting edge portion was subjected to a honing process of R: 0.09 mm. Tool bases a to e made of TiCN-based cermet having an insert shape of standard / CNMG12041 were formed.

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 having the conditions shown in Table 3 and the layer configuration and target total layer thickness shown in Table 7 is formed by vapor deposition.
(B) Next, an upper layer made of an α-type aluminum oxide layer having the conditions shown in Table 4 and the target layer thickness shown in Table 7 is formed by vapor deposition.
(C) At this time, when the surface side of the α-type aluminum oxide layer is formed under the conditions A to O shown in Table 5, the content of carbon in the surface region is set to a predetermined amount by using TMA, and chlorine is used. The content of can be suppressed to a predetermined amount or less. Thereby, this invention coated tools 1-10 were produced.
(D) Further, for the coated tools 11 to 15 of the present invention, the outermost layer made of an amorphous aluminum oxide layer having the conditions shown in Table 6 and the target layer thickness shown in Table 7 is formed on the upper layer by vapor deposition. This was produced.

  For comparison purposes, the surfaces of the tool bases A to E and the tool bases a to e are the same as the coated tools 1 to 15 of the present invention under the conditions shown in Table 3 and the layer configuration and target layer thickness shown in Table 8. Then, a Ti compound layer as a lower layer of the hard coating layer was formed by vapor deposition. Next, as the upper layer, an upper layer made of an α-type aluminum oxide layer was formed by vapor deposition under the conditions shown in Table 4 and the target layer thickness shown in Table 8. At this time, the α-type aluminum oxide crystal structure is formed without using TMA during the formation of the upper layer. Thereby, the comparative coated tools 1-10 of Table 8 were produced. Further, the comparative coated tools 11 to 15 were prepared by vapor-depositing an outermost layer made of an amorphous aluminum oxide layer having the conditions shown in Table 6 and the target layer thickness shown in Table 8 on the upper layer. .

Moreover, the cross section of each component layer of this invention coated tool 1-15 and comparative coated tool 1-15 was observed over multiple visual fields (5 points) using a scanning electron microscope (magnification 5000 times), and the average layer When the thickness was determined, all showed the average layer thickness substantially the same as the target layer thickness shown in Table 7 and Table 8.
In addition, the carbon content and the chlorine content in the upper layer of the hard coating layer were determined by secondary ion mass spectrometry (SIMS, Secondary-Ion-Mass-Spectroscopy). A Cs ion beam (Cs ⁺ ) was irradiated in a range of 70 μm × 70 μm from the sample surface side, the concentration of the component emitted by the sputtering action was measured in the depth direction, and calibrated using a standard sample. As a result, about this invention coated tool 1-15, the area | region whose chlorine content in the upper layer of a hard coating layer is 0.05 at% or less exists, and the depth of this area | region is 5-10 of average layer thickness. %. Table 7 shows the ratio of the region of the coated tools 1 to 15 of the present invention to the average layer thickness. Table 7 shows the average values in the depth direction of the carbon content and chlorine content in the regions of the coated tools 1 to 15 of the present invention. For the comparative coated tools 1 to 15, there was no region where the chlorine content was 0.05 at% or less. Table 8 shows the ratio of the depth of the analysis of the comparative coated tools 1 to 15 to the average layer thickness, and the average value in the depth direction of the carbon content and chlorine content of the analyzed surface region.
Moreover, about the outermost surface of this invention coated tool 1-15 and comparative coated tool 1-15, it measured according to JIS B-0601 (2001) using a laser microscope, and surface roughness Ra (arithmetic mean roughness) Asked. Tables 7 and 8 show the obtained surface roughness Ra.
Furthermore, about the cross section of this invention coated tool 1-15, a micro area | region is observed using a transmission electron microscope (magnification 200000 times), and the depth equivalent to 5-10% of the average layer thickness of the surface side of an upper layer When the surface area was analyzed from the cross-section side using energy dispersive X-ray spectroscopy (EDS), the content of carbon and chlorine in the present coated tools 1, 3, 4, 6 to 14 was Two different phases were observed. The two phases are defined as a region A phase and a region B phase, and for the two phases, quantitative analysis of the beam diameter 1 nm region is performed at five points in each phase, and the average of the five points is obtained. the average carbon content alpha _C and an average chlorine content alpha _Cl, the average carbon content beta _C and an average chlorine content beta _Cl regions B phase was measured. The content of carbon and chlorine determined by secondary ion mass spectrometry cannot be distinguished from the region A phase and the region B phase by the spatial resolution of secondary ion mass spectrometry. It is thought that it contains. When the energy dispersive X-ray spectroscopy of the transmission electron microscope is used, the composition of a minute region can be analyzed with high spatial resolution, so that the region A phase and the region B phase can be distinguished. However, in the case of energy dispersive X-ray spectroscopy of a transmission electron microscope, the absolute value includes an error due to the influence of sample contamination (contamination) in the body of the transmission electron microscope. Therefore, the present invention coated tools 1 to 15, the area A phase average carbon content alpha _C and the region B-phase average carbon content beta _C and which is the ratio alpha _{C /} beta _C of _an average chlorine content of the region B phase Comparison between samples is obtained by _obtaining β _Cl / α _Cl which is a ratio of the amount β _Cl to the average chlorine content α _Cl of the region A phase, and using the relative value of the region A phase and the region B phase in the same sample. Did.

Furthermore, about the outermost layer of this invention coated tool 11-15 which formed outermost layer, and comparative coated tool 11-15, it observed over a some visual field using a transmission electron microscope (magnification 200000 times), and outermost layer of As a result of performing electron beam diffraction on aluminum oxide, a diffraction image of the aluminum oxide crystal was not observed, and it was confirmed that the aluminum oxide was amorphous aluminum oxide.

Next, the cutting test was performed on the present coated tools 1 to 15 and the comparative coated tools 1 to 15 under the conditions shown in Table 9, and the flank wear width of the cutting edge was measured in any cutting test.
Table 10 shows the measurement results.

  From the results shown in Table 7 and Table 10, in the coated tool of the present invention, the aluminum oxide layer constituting the upper layer of the hard coating layer has an α-type crystal structure, and the average layer from the surface side of the upper layer The carbon content in the depth region corresponding to 5 to 10% of the thickness is 0.1 to 5 at%, the chlorine content is 0.05 at% or less, and the surface roughness Ra of the surface is 0. Even if it is used for high-speed intermittent cutting with high heat generation and intermittent / impact high load acting on the cutting edge, it is within the range of 0.05 to 0.2 μm. It is clear that it has excellent chipping resistance and chipping resistance, and as a result, exhibits excellent cutting performance over a long period of use.

  Furthermore, when an amorphous aluminum oxide layer having an average layer thickness of 0.5 to 5 μm was provided as the outermost layer on the upper layer, it was confirmed that the cutting performance was further improved.

  On the other hand, the carbon content in the depth region corresponding to 5 to 10% of the average layer thickness from the surface side of the upper layer of the hard coating layer is outside the range of 0.1 to 5 at%, and the chlorine content For the comparative coated tools 1 to 15 whose amount exceeds 0.05 at%, chipping, chipping, etc. when used for high-speed intermittent cutting with high heat generation and intermittent / impact high load acting on the cutting edge It is clear that the occurrence of a short life span.

  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 (4)

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,
The hard coating layer is composed of a lower layer and an upper layer chemically vapor-deposited,
(A) The lower layer is composed of one or more of a Ti carbide layer, a nitride layer, a carbonitride layer, a carbonate layer, and a carbonitride layer, and a total of 3 to 20 μm. A Ti compound layer having an average layer thickness;
(B) The upper layer is an aluminum oxide layer having an α-type crystal structure having an average layer thickness of 2 to 25 μm,
The upper layer (b) has a carbon content of 0.1 to 5 at% in a depth region corresponding to 5 to 10% of the average layer thickness of the upper layer from the surface side, and a chlorine content. A surface-coated cutting tool having a surface flat structure having a surface roughness Ra in a range of 0.05 to 0.2 μm and having a surface roughness Ra of 0.05 at% or less. The upper layer (b) has two phases having different carbon and chlorine contents in the depth region corresponding to 5 to 10% of the average layer thickness from the surface side. When the phase and the region B phase are set, the ratio of the average carbon content α _C of the region A phase and the average carbon content β _C of the region B phase is α _C / β _C is 5 or more, and the average of the region B phase the surface-coated cutting tool according to claim 1, characterized in that the ratio between the average chlorine content alpha _Cl chlorine content beta _Cl and the region a-phase beta _{Cl /} alpha _Cl is 5 or more. 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,
The hard coating layer comprises a lower layer, an upper layer and an outermost layer, which are chemically vapor-deposited,
(C) The lower layer is composed of one or more of a Ti carbide layer, a nitride layer, a carbonitride layer, a carbonate layer and a carbonitride layer, and a total of 3 to 20 μm. A Ti compound layer having an average layer thickness;
(D) The upper layer is an aluminum oxide layer having an α-type crystal structure having an average layer thickness of 2 to 25 μm,
(E) the outermost layer is an amorphous aluminum oxide layer having an average layer thickness of 0.5 to 5 μm;
The upper layer (d) has a carbon content of 0.1 to 5 at% in a depth region corresponding to 5 to 10% of the average layer thickness of the upper layer from the interface between the upper layer and the outermost layer. The content of chlorine is 0.05 at% or less, and the outermost layer of (e) has a surface flat structure having a surface roughness Ra in the range of 0.05 to 0.2 μm. A surface-coated cutting tool. The upper layer (d) has two different carbon and chlorine contents in a depth region corresponding to 5 to 10% of the average layer thickness of the upper layer from the interface between the upper layer and the outermost layer. If the two phases are the region A phase and the region B phase, α _C / β which is the ratio of the average carbon content α _C of the region A phase and the average carbon content β _C of the region B phase _C is 5 or more, and β _Cl / α _Cl which is a ratio of the average chlorine content β _Cl of the region B phase and the average chlorine content α _Cl of the region A phase is 5 or more. 3. The surface-coated cutting tool according to 3.