JP2014128837A - Surface-coated cutting tool with hard coating layer exerting excellent anti-chipping properties - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface-coated cutting tool exerting excellent anti-chipping properties and defect resistance in high-speed intermittent cutting.SOLUTION: A hard coating layer contains at least Ti/Al composite carbonitride layers of an average layer thickness of 1-20 μm formed by chemical vapor deposition. When the composite carbonitride layer is expressed by a composition formula (TiAl)(CN), the inclusion ratio x, by atomic ratio, of Al and the inclusion ratio y, by atomic ratio, of C meet the conditions 0.80≤x≤0.95 and 0.005≤y≤0.05, respectively. There are provided a plurality of fragmentation layers of an average layer thickness of 1-10 nm which fragment the layer thickness direction within the layer and are present in a density of 10-50 layers per 1 μm layer thickness in the layer thickness direction. When the fragmentation layers are expressed by a composition formula (TiAl)(CN), the inclusion ratio x, by atomic ratio, of Al and the inclusion ratio y, by atomic ratio, of C meet the conditions 0.50≤x≤0.70 and 0.005≤y<0.05, respectively.

Description

  The present invention provides high chipping resistance with an excellent hard coating layer in high-speed intermittent cutting of various steels and cast irons that are accompanied by high heat generation and intermittent and impact loads are applied to the cutting edge. The present invention relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) that exhibits excellent cutting performance over the course of use.

Conventionally, in general, tungsten carbide (hereinafter referred to as WC) based cemented carbide, titanium carbonitride (hereinafter referred to as TiCN) based cermet or cubic boron nitride based ultra high pressure sintered body (hereinafter referred to as cBN), etc. A composite nitride of Ti and Al (hereinafter referred to as (Ti, Al) N) layer, carbonitride (hereinafter referred to as (Ti) , Al) a coating tool formed by coating a hard coating layer formed of a composite compound layer of Ti and Al composed of one or more of the layers (shown by CN) is known. It is known that it is used for cutting various steels and cast irons.
However, the above-mentioned coated tool has problems that chipping and chipping are likely to occur under cutting conditions in which a heavy load is applied to the cutting edge, and the tool life is short-lived. Proposals have been made.

  For example, in Patent Document 1, in a coated tool in which a hard coating layer made of (Al, Ti) N is deposited on the surface of a tool base, the hard coating layer is made of granular crystals (Al, Ti) N. The thin layer A and the thin layer B composed of columnar crystals (Al, Ti) N are configured as an alternately laminated structure, and each of the thin layer A and the thin layer B has a layer thickness of 0.05 to 2 μm. A coated tool is disclosed in which the crystal grain size is 30 nm or less, and the crystal grain size of the columnar crystals is 50 to 500 nm.

In Patent Documents 2 and 3, a hard coating layer including a plurality of layers formed by chemical vapor deposition is formed on the surface of a tool base, and the main layers are Ti _1-x Al _x N, Ti _1-x. Made of Al _x C, and / or Ti _1-x Al _x CN, 0.65 ≦ x ≦ 0.9, and a TiCN layer or an Al ₂ O ₃ layer is disposed above or below the main layer. A coated tool is disclosed.

Furthermore, Patent Document 4 discloses that Ti _x Al _1-x N and Ti _y Al _1-y N (0 ≦ x <0.5, 0.5 <) composed of Ti, Al, and N as the hard coating layer. Two types of compounds (A, B) consisting of y ≦ 1) are alternately and repeatedly laminated, the repeated lamination period λ is 0.5 to 20 nm, and the total film thickness is 0.5 to 10 μm. A coated tool in which a laminate is coated on the surface of a tool base is disclosed.

JP2011-224715A Special table 2011-516722 gazette Special table 2011-513594 gazette JP-A-7-97679

  In recent years, there is a strong demand for labor saving and energy saving in cutting, and with this, coated tools are increasingly used under more severe conditions. For example, Patent Documents 1 to 4 show the above. Even when a coated tool is used for high-speed interrupted cutting with high heat generation and more intermittent and impact loads on the cutting edge, the thermal conductivity of the hard coating layer is high and heat shielding Since the effect is not sufficient and the toughness is not sufficient, chipping and chipping are likely to occur at the cutting edge due to high load during cutting, and as a result, the service life is reached in a relatively short time. is there.

  From the above viewpoint, the present inventors have excellent hard coating layers even when they are used for high-speed intermittent cutting that involves generation of high heat and an intermittent / impact load acts on the cutting edge. In order to develop a coated tool that has toughness and heat shielding effect, and as a result, exhibits excellent chipping resistance and fracture resistance over long-term use, we have conducted intensive research on a composite carbonitride layer of Ti and Al. As a result, the following knowledge was obtained.

That is, the hard coating layer includes at least one conventional (Ti, Al) N layer and / or (Ti, Al) CN layer and has one or more layers having a predetermined total average layer thickness. In the case where a composite compound layer of Ti and Al is formed, the composite compound layer of Ti and Al is formed in a columnar shape in the vertical direction as a substrate. Therefore, wear resistance and thermal conductivity are improved. On the other hand, the higher the anisotropy of the composite compound layer of Ti and Al, the lower the toughness and the heat shielding effect. As a result, the chipping resistance and chipping resistance are reduced, and sufficient resistance over a long period of use. It was not possible to exhibit wear and to satisfy the tool life.
Therefore, the present inventors conducted extensive research on the (Ti, Al) CN layer that constitutes the hard coating layer. By relaxing the anisotropy of the (Ti, Al) CN layer and improving the toughness and heat shielding effect, The present inventors have found a novel finding that the chipping resistance and chipping resistance of the hard coating layer can be improved.

Specifically, when the composite carbonitride layer contained at least in the hard coating layer is represented by a composition formula: (Ti _1-x Al _x ) (C _y N _1-y ), it occupies the total amount of Ti and Al. The Al content ratio x and the C content ratio y in the total amount of C and N (where x and y are atomic ratios) are 0.80 ≦ x ≦ 0.95 and 0.001 ≦ y, respectively. In addition to satisfying .ltoreq.0.01, the presence of a plurality of thin, low chlorine concentration dividing layers that divide the layer thickness direction in the layer alleviates the anisotropy of the (Ti, Al) CN layer, and improves toughness and The heat shielding effect is enhanced.

The (Ti, Al) CN layer having the above-described configuration can be formed by, for example, the following chemical vapor deposition method.
(A) Film formation process On the surface of the tool base, the reaction gas composition (volume%) is TiCl ₄ : 1.5 to 2.5%, Al (CH ₃ ) ₃ : 1.0 to 3.0%, AlCl _{3. : 6.0~10.0%, NH 3: 2.0~5.0} %, N 2: 6.0~7.0%, C 2 H 4: 0~1.0%, Ar: 0~ 10.0%, H ₂ : remaining, reaction atmosphere pressure: 2 to 5 kPa, reaction atmosphere temperature: 750 to 900 ° C., and by performing a thermal CVD method for a predetermined time, (Ti , Al) CN layer is formed.
(B) Pulse process In the course of the film formation process of (a), the addition amount of Al (CH ₃ ) ₃ and AlCl ₃ is changed to Al (CH ₃ ) ₃ : 4.0 to 6.0% in a predetermined cycle. AlCl ₃ : A pulse process changed to 0 to 1.0% is sandwiched for a predetermined time.

  Usually, in the physical vapor deposition method, it is difficult to form a cubic structure when the Al content ratio x in the total amount of Al and Ti in the TiAlCN layer exceeds 0.5. According to the finding, even when the Al content ratio x in the total amount of Al and Ti in the TiAlCN layer is 0.80 ≦ x ≦ 0.95 and Al-rich, a stable cubic crystal structure can be formed. It was. Furthermore, the Al content ratio x in the total amount of Al and Ti in the TiAlCN layer of the dividing layer is 0.50 ≦ x ≦ 0.70, the average layer thickness is 1 to 10 nm, and the cycle is 10 to 50 layers / When μm, that is, the average interval is 20 to 100 nm, it was used for high-speed intermittent cutting of steel and cast iron in which fracture resistance and chipping resistance were improved and intermittent and impact loads acted on the cutting edge. Even in this case, it has been found that the hard coating layer can exhibit excellent cutting performance over a long period of use.

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 coated on the surface of a tool base composed of tungsten carbide-based cemented carbide, titanium carbonitride-based cermet, or cubic boron nitride-based ultrahigh-pressure sintered body ,
(A) The hard coating layer includes at least a composite carbonitride layer of Ti and Al having an average layer thickness of 1 to 20 μm formed by a chemical vapor deposition method,
(B) When the composite carbonitride layer is expressed by a composition formula: (Ti _1-x Al _x ) (C _y N _1-y ), the Al content ratio x and C in the total amount of Ti and Al The proportion of C in the total amount of N and N (where x and y are atomic ratios) satisfies 0.80 ≦ x ≦ 0.95 and 0.005 ≦ y ≦ 0.05, respectively. And having a plurality of thin dividing faults dividing the layer thickness direction in the layer,
(C) The dividing layer has an average layer thickness of 1 to 10 nm, 10 to 50 layers per 1 μm in the layer thickness direction of the composite carbonitride layer, and a composition formula: (Ti _1-x Al _x ) When expressed by (C _y N _1-y ), the Al content ratio x in the total amount of Ti and Al and the C content ratio y in the total amount of C and N (where x and y are atoms) Ratio) satisfies 0.50 ≦ x ≦ 0.70 and 0.005 ≦ y ≦ 0.05, respectively.
A surface-coated cutting tool characterized by that.
(2) The surface covering according to (1), wherein the content ratio z (where z is an atomic ratio) of Cl in the total amount of atoms constituting the dividing layer is z ≦ 0.01. Cutting tools.
(3) The surface-coated cutting according to (1) or (2), wherein the composite carbonitride layer is formed by a chemical vapor deposition method containing at least trimethylaluminum as a reaction gas component. tool. "
It has the characteristics.

  The present invention will be described in detail below.

Average composition and average layer thickness of the composite carbonitride layer of Ti and Al constituting the hard layer _{((Ti 1-x Al x} ) (C y N 1-y) layer):
The composite carbonitride layer of Ti and Al constituting the hard coating layer is represented by the composition formula: (Ti _1-x Al _x ) (C _y N _1-y ), and Al occupies the total amount of Ti and Al. When the content ratio x (atomic ratio) is less than 0.80, the high-temperature hardness is insufficient and wear resistance decreases, while when the x (atomic ratio) value exceeds 0.95 However, since the cubic structure cannot be maintained due to the relative decrease in the Ti content, the high-temperature strength is reduced, and chipping and defects are likely to occur. Therefore, the value of x (atomic ratio) is 0.80 or more. It is necessary to set it to 0.95 or less.
When the ((Ti _1-x Al _x ) (C _y N _1-y ) layer having the above composition is formed by vapor deposition by the PVD method, the crystal structure becomes a hexagonal crystal. Since it is formed by vapor deposition, a (Ti _1-x Al _x ) (C _y N _1-y ) layer having the above composition can be obtained while maintaining the cubic structure, so that Al is highly concentrated. Despite being contained in the film, the film hardness hardly decreases.
Further, in the (Ti _1-x Al _x ) (C _y N _1-y ) layer, the C component improves the hardness of the layer, while the N component has an effect of improving the high temperature strength of the layer. However, when the content ratio y (atomic ratio) of the C component is less than 0.005, high hardness cannot be obtained. On the other hand, when y (atomic ratio) exceeds 0.05, the high-temperature strength decreases. , Y (atomic ratio) was set to 0.005 or more and 0.05 or less.
The (Ti _1-x Al _x ) (C _y N _1-y ) layer has an average layer thickness of less than 1 μm, and cannot sufficiently secure the adhesion to the substrate. If the thickness exceeds 20 μm, it becomes easy to cause thermoplastic deformation by high-speed milling with high heat generation, which causes uneven wear. Therefore, the total average layer thickness is set to 1 to 20 μm.

  In the present invention, in addition to the structure of the hard coating layer, when the hard coating layer has a dividing layer that satisfies the following conditions, the coarse particles of the composite carbonitride having a cubic structure constituting the hard coating layer As a result, it exhibits excellent wear resistance and chipping resistance.

Average layer thickness of split faults in Ti and Al composite carbonitride layers:
When the average thickness of the dividing layer is 1 to 10 nm, the effect is remarkably exhibited. The reason for this is that if the average layer thickness of the dividing fault is less than 1 nm, the dividing fault does not sufficiently exert the effect of suppressing the coarsening of the composite carbonitride, so the dividing fault has an improved toughness and chipping resistance. The effect is not fully demonstrated. On the other hand, if the average layer thickness of the dividing layer exceeds 10 nm, the cubic crystal structure is completely divided, and as a result, the high hardness of the cubic crystal structure cannot be maintained. Accordingly, the average layer thickness of the dividing fault is set to 1 to 10 nm.

Average composition of splitting in a composite carbonitride layer of Ti and Al:
When the dividing line is represented by a composition formula: (Ti _1-x Al _x ) (C _y N _1-y ), the value of the Al content ratio x (atomic ratio) in the total amount of Ti and Al is 0. .50 to 0.70 makes it possible to make a significant difference between the lattice constant of the base tissue and the lattice constant of the dividing fault, and as a result, suppress coarsening of the base tissue. it can. On the other hand, if the value of x (atomic ratio) exceeds 0.70, there is no significant difference between the lattice constant of the matrix structure and the lattice constant of the split layer structure, and coarsening of the matrix structure is not possible. The action of the fault to suppress is not fully demonstrated. If x is smaller than 0.50, oxidation resistance at high temperatures cannot be maintained.
The C component improves the hardness of the layer, while the N component has the effect of improving the high-temperature strength of the layer. However, when the C component content ratio y (atomic ratio) is less than 0.005, the C component is high. On the other hand, when y (atomic ratio) exceeds 0.05, the strength at high temperature decreases, so the value of y (atomic ratio) is set to 0.005 or more and 0.05 or less. It was.

Period of split faults in Ti and Al composite carbonitride layers:
When the dividing line has 10 to 50 layers per 1 μm in the layer thickness direction, the above-described action of the dividing line to enhance toughness and chipping resistance is further exhibited. The reason is that if the dividing layer is less than 10 layers per 1 μm, the effect of improving the toughness is not sufficiently exhibited, while if it exceeds 50 layers, the hardness is lowered and the flank wear resistance is lowered.

Cl concentration in the dividing fault in the composite carbonitride layer of Ti and Al:
When the hard coating layer is formed by the chemical vapor deposition method, a trace amount of Cl due to the reaction gas component is contained in the layer. However, if the average chlorine content is 1 atomic% or less, the hard coating layer does not become brittle and does not adversely affect the properties of the hard coating layer. In the case where the low-concentration chlorine-containing layer has a film structure existing at intervals of 10 to 50 layers / μm toward the surface side of the layer, the hard coating layer not only has lubricity but also improves chipping resistance. I found out. Therefore, in the present invention, the hard coating layer is controlled by reducing the content ratio of AlCl ₃ which is a reaction gas when forming the dividing line, and controlling the Cl content ratio in the dividing line to 1 atomic% or less. Succeeded in improving the lubricity and chipping resistance.
FIG. 1 shows a schematic diagram of a longitudinal section of a composite carbonitride layer of Ti and Al constituting the hard coating layer of the present invention.

The present invention relates to a surface-coated cutting tool in which a hard coating layer is coated on the surface of a tool base composed of any of tungsten carbide-based cemented carbide, titanium carbonitride-based cermet, or cubic boron nitride-based ultrahigh-pressure sintered body. (A) The hard coating layer is composed of a composite carbonitride layer of Ti and Al having an average layer thickness of 1 to 20 μm formed by chemical vapor deposition, and (b) the composite carbonitride layer has a composition formula : (Ti _1-x Al _x ) (C _y N _1-y ), the content ratio x of Al in the total amount of Ti and Al and the content ratio y of C in the total amount of C and N ( However, x and y are both atomic ratios) satisfying 0.80 ≦ x ≦ 0.95 and 0.005 ≦ y ≦ 0.05, respectively, and a plurality of layers dividing the layer thickness direction in the layer (C) the split layer has an average layer thickness of 1 to 10 nm. Yes, when there are 10 to 50 layers per 1 μm in the thickness direction of the composite carbonitride layer and the composition formula is represented by (Ti _1-x Al _x ) (C _y N _1-y ), Ti and Al The content ratio x of Al in the total amount of C and the content ratio y of C in the total amount of C and N (where x and y are atomic ratios) are 0.50 ≦ x ≦ 0.70, respectively. Since it comprised so that 0.005 <= y <= 0.05, the coarsening of the composite carbonitride which has the cubic structure which comprises a hard coating layer can be suppressed by a dividing layer. As a result, excellent wear resistance and chipping resistance can be exhibited, and excellent cutting performance can be maintained over a long period of time.

It is a schematic diagram of the longitudinal cross-section of the composite carbonitride layer of Ti and Al which comprises the hard coating layer 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, TaC powder, NbC powder, Cr ₃ C ₂ powder and Co powder all having an average particle diameter of 1 to 3 μm are prepared. After blending into the composition shown, adding wax, mixing with ball mill in acetone for 24 hours, drying under reduced pressure, press-molding into a green compact of a predetermined shape at a pressure of 98 MPa, and this green compact was vacuumed at 5 Pa. Medium: Sintered in vacuum at a predetermined temperature within the range of 1370 to 1470 ° C. for 1 hour. After sintering, the cutting edge is subjected to honing of R: 0.07 mm. WC base cemented carbide tool bases A to D each having an insert shape 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, and after the sintering, the cutting edge portion was subjected to a honing process of R: 0.07 mm. Tool bases a to d made of TiCN-based cermet having an insert shape of standard / CNMG120408 were formed.

Next, a normal chemical vapor deposition apparatus is used on the surfaces of the tool bases A to D and the tool bases a to d, and (a) a hard coating layer is shown in the upper part of the film formation types A to E in Table 4. Under the film forming process formation conditions, a composite carbonitride layer of Ti and Al having a target layer thickness (μm) and a target composition shown in Table 5 is formed by vapor deposition.
(B) At this time, during the formation of the composite carbonitride layer of Ti and Al, the pulse process formation conditions shown in the lower stages of the film formation types A to E in Table 4 are sandwiched for a predetermined time with a predetermined period. Thus, a dividing layer having the target layer thickness, period (number of layers per 1 μm in the layer thickness direction) and target composition shown in Table 5 is formed.
The coated tools 1 to 10 of the present invention shown in Table 5 were produced by the steps (a) and (b).
In addition, about this invention coated tools 1-8, the lower layer and / or the upper layer were formed on the formation conditions shown in Table 3.

About the hard coating layer of the said coating tools 1-10 of this invention, when a longitudinal cross-section was observed using the scanning electron microscope (magnification 20000 times), as shown in the film | membrane structural schematic diagram shown in FIG. 1, in a TiAlCN layer A membrane structure with a dividing fault was confirmed.

Further, for comparison purposes, on the surfaces of the tool bases A to D and the tool bases a to d, the conditions shown in the film formation types F to J in Table 4 and the target layer thickness (μm) and target composition shown in Table 6 are used. The composite carbonitride layer of Ti and Al was formed by vapor deposition in the same manner as the coated tools 1 to 10 of the present invention. At this time, comparative coating tools 1 to 10 shown in Table 6 were produced by forming no dividing line or forming a dividing line that deviates from the dividing line condition in the present invention described above.
In addition, about the comparison coating tools 1-8, the lower layer and / or the upper layer were formed on the formation conditions shown in Table 3.

  Further, the thicknesses of the hard coating layers of the inventive coated tools 1 to 10 and the comparative coated tools 1 to 10 were measured at five locations using a scanning electron microscope (magnification 5000 times), and the average was taken. Thickness. As a result, all showed the average layer thickness substantially the same as the target layer thickness shown in Table 5 and Table 6.

Moreover, about this invention coated tool 1-10 and comparative coated tool 1-10, using the same scanning electron microscope (50000 times magnification), the layer space | interval of each division | segmentation fault which exists in a hard coating layer is measured five places. As an average value, the average interval of each fault was obtained, and the number of faults existing in the layer thickness direction of 1 μm was obtained. The values are shown in Tables 5 and 6.
Moreover, about the average layer thickness, average Al content rate x, average C content rate y, and average chlorine content z of a composite carbonitride layer and each partial fault, secondary ion mass spectrometry (SIMS, Secondary-Ion-Mass- (Spectroscope). The ion beam was irradiated in the range of 70 μm × 70 μm from the sample surface side, and the concentration in the depth direction was measured for the components emitted by the sputtering action. From the relationship between the depth direction and the Al content ratio x, the C content ratio y, and the chlorine content z of the Ti and Al composite carbonitride layer thus obtained, the Al content ratio x and the C and N Measurement points where the content ratio y of C in the total amount (where x and y are atomic ratios) satisfy 0.50 ≦ x ≦ 0.70 and 0.005 ≦ y <0.05, respectively The measurement results at the split fault, and the average layer thickness, average Al content ratio x, average C content ratio y, and average chlorine content of each split fault from the section in which measurements at the split fault are continuously obtained in the depth direction z was determined. Further, the average Al content ratio x, the average C content ratio y and the average chlorine content z of the hard coating layer are the Al content ratio x, the C content ratio y and the chlorine content in the depth direction of the composite carbonitride layer of Ti and Al. It was determined by averaging the results across the concentration profile for the quantity z. Furthermore, regarding the crystal structure of the TiAlCN layer constituting the hard coating layer of the present coated tool 1-10 and comparative coated tool 1-10, using an X-ray diffractometer, JCPDS00-038-1420 TiN and JCPDS00-046-1200 AlN And was investigated by comparing the diffraction angle. Tables 5 and 6 show the results.

Next, a cutting test was carried out under the conditions shown in Table 7 for the inventive coated tools 1 to 10 and the comparative coated tools 1 to 10, and the flank wear width of the cutting edge was measured in any cutting test.
Table 8 shows the measurement results.

From the results shown in Table 5 and Table 8, the coated tools 1 to 10 of the present invention are a composite carbonitride layer of Ti and Al having an average layer thickness of 1 to 20 μm in which the hard coating layer is formed by chemical vapor deposition. The composite carbonitride layer containing at least, when represented by the composition formula: (Ti _1-x Al _x ) (C _y N _1-y ), the Al content ratio x and C in the total amount of Ti and Al The proportion of C in the total amount of N and N (where x and y are atomic ratios) satisfies 0.80 ≦ x ≦ 0.95 and 0.005 ≦ y ≦ 0.05, respectively. In addition, the layer has a plurality of thin dividing lines that divide the layer thickness direction in the layer, the dividing layer has an average layer thickness of 1 to 10 nm, and 10 to 50 layers per 1 μm in the layer thickness direction of the composite carbonitride layer. and, and, the composition _{formula: (Ti 1-x Al x} ) if (C _{y N 1-y)} expressed in, Ti and Al The Al content ratio x in the total amount and the C content ratio y (where x and y are atomic ratios) in the total amount of C and N are 0.50 ≦ x ≦ 0.70, 0, respectively. By satisfying .005 ≦ y <0.05, coarsening of the composite carbonitride layer having a cubic structure constituting the hard coating layer can be suppressed by dividing lines, and as a result, excellent It is apparent that excellent cutting performance can be maintained over a long period of time with excellent wear resistance and chipping resistance.

  On the other hand, the composite carbonitride layer having a cubic structure constituting the hard coating layer does not have a dividing line, or even if it has a comparative coated tool 1 to 1 that does not satisfy a predetermined condition As for No. 10, when it is 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 life is shortened due to occurrence of chipping, chipping, etc. is there.

As the raw material powder, cBN powder, TiN powder, TiCN powder, TiC powder, Al powder, and Al ₂ O ₃ powder each having an average particle diameter in the range of 0.5 to 4 μm were prepared. The mixture is blended in the composition shown in FIG. 1, wet mixed with a ball mill for 80 hours, dried, and then pressed into a green compact having a diameter of 50 mm × thickness: 1.5 mm under a pressure of 120 MPa. The green compact is sintered in a vacuum atmosphere at a pressure of 1 Pa at a predetermined temperature within a range of 900 to 1300 ° C. for 60 minutes to obtain a presintered body for a cutting edge piece. In addition, Co: 8% by mass, WC: remaining composition, and diameter: 50 mm × thickness: 2 mm, superposed on a WC-based cemented carbide support piece with a normal super-high pressure Insert into the sintering machine and under normal conditions Pressure: 4 GPa, temperature: 1200 ° C. to 1400 ° C. at a predetermined temperature holding time: 0.8 hour sintering, and after sintering, the upper and lower surfaces are polished using a diamond grindstone, and wire discharge It is divided into predetermined dimensions by a processing apparatus, and further Co: 5 mass%, TaC: 5 mass%, WC: remaining composition and shape of JIS standard CNGA12041 (thickness: 4.76 mm × inscribed circle diameter: 12. The brazing part (corner part) of the WC-based cemented carbide insert body having a 7 mm 80 ° rhombus) has a composition consisting of Zr: 37.5%, Cu: 25%, Ti: the rest in mass%. After brazing using a brazing material of Ti-Zr-Cu alloy and having a predetermined dimension, the cutting edge is subjected to honing with a width of 0.13 mm and an angle of 25 °, followed by finishing polishing. ISO standard The tool substrate (a) to (k) two having the insert shape of NGA120412 were produced, respectively.

Next, at least (Ti _1-x Al _x ) is used on the surfaces of these tool substrates a to d under the conditions shown in Tables 3 and 4 by the same method as in Example 1 using a normal chemical vapor deposition apparatus. The coated tools 11 to 16 of the present invention were manufactured by vapor-depositing a hard coating layer including the (C _y N _1-y ) layer with a target layer thickness and a target composition shown in Table 10.
In addition, about this invention coated tools 13-16, the lower layer and / or the upper layer were formed on the formation conditions shown in Table 3.

Further, for the purpose of comparison, at least (Ti _1-x Al _x ) (C _y N ₁ ) is used on the surfaces of the tool bases a to d under the conditions shown in Tables 3 and 4 using a normal chemical vapor deposition apparatus. the hard coating layer containing _-y) layer by vapor deposited at a target layer thickness, and the target composition shown in Table 11, were prepared to compare coated tools 11-16.
In addition, similarly to this invention coating | coated tool 13-16, about the comparison coating tools 13-16, the lower layer and / or the upper layer were formed on the formation conditions shown in Table 3.

Moreover, the cross section of each component layer of this invention coated tool 11-16 and comparative coated tool 11-16 is measured using a scanning electron microscope (5000 times magnification), and the layer thickness of five points in an observation visual field is measured. When the average layer thickness was obtained by averaging, all showed the same average layer thickness as the target layer thickness shown in Table 10 and Table 11.

  Moreover, about the composite carbonitride layer of each of the present invention coated tools 11 to 16 and the comparative coated tools 11 to 16 and each split layer, the same method as the method shown in Example 1 was used, and the average layer thickness and the average Al The content ratio x, the average C content ratio y, the average chlorine content z, the average interval of the dividing faults, and the average layer thickness were determined. The results are shown in Table 10 and Table 11.

  Next, carburization shown below about this invention coated tools 11-16 and comparative coated tools 11-16 in the state where all the various coated tools were screwed to the tip of the tool steel tool with a fixing jig. A dry high-speed intermittent cutting test was performed on the quenched alloy steel, and the flank wear width of the cutting edge was measured.

Tool substrate: Cubic boron nitride-based ultra-high pressure sintered body,
Cutting test: Dry high-speed intermittent cutting of carburized and quenched alloy steel,
Work material: JIS · SCr420 (Hardness: HRC60) lengthwise equidistant four round grooved round bars,
Cutting speed: 210 m / min,
Cutting depth: 0.10 mm,
Feed: 0.10 mm / rev,
Cutting time: 4 minutes
Table 12 shows the results of the cutting test.

From the results shown in Table 12, the coated tools 11 to 16 of the present invention have a hard coating layer composed of a composite carbonitride layer of Ti and Al having an average layer thickness of 1 to 20 μm formed by chemical vapor deposition. When the composite carbonitride layer is expressed by the composition formula: (Ti _1-x Al _x ) (C _y N _1-y ), the Al content ratio x and the total content of C and N in the total amount of Ti and Al The content ratio y of C in the amount (where x and y are atomic ratios) satisfy 0.80 ≦ x ≦ 0.95 and 0.005 ≦ y ≦ 0.05, respectively, And having a plurality of thin dividing lines that divide the layer thickness direction, the dividing layer has an average layer thickness of 1 to 10 nm, 10 to 50 layers per 1 μm in the layer thickness direction of the composite carbonitride layer, and _{formula: (Ti 1-x Al x} ) when expressed (C _{y N 1-y),} the occupied total amount of Ti and Al The content ratio x of l and the content ratio y of C in the total amount of C and N (where x and y are atomic ratios) are 0.50 ≦ x ≦ 0.70 and 0.005 ≦ y, respectively. By satisfying <0.05, coarsening of the composite carbonitride having a cubic structure constituting the hard coating layer can be suppressed by a dividing layer, and as a result, excellent wear resistance and It is clear that chipping resistance can be exhibited and excellent cutting performance can be maintained over a long period of time.

  On the other hand, the comparative coating tools 11 to 16 in which the composite carbonitride layer of Ti and Al constituting the hard coating layer does not have a dividing line or does not satisfy the predetermined condition even if it has it. With regard to, it is clear that when it is used for high-speed intermittent cutting with high heat generation and intermittent / impact high loads on the cutting edge, it will reach the end of its life in a short time due to the occurrence of chipping, chipping, etc. .

  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 (5)

In a surface-coated cutting tool in which a hard coating layer is coated on the surface of a tool base composed of tungsten carbide-based cemented carbide, titanium carbonitride-based cermet, or cubic boron nitride-based ultrahigh-pressure sintered body,
(A) The hard coating layer includes at least a composite carbonitride layer of Ti and Al having an average layer thickness of 1 to 20 μm formed by a chemical vapor deposition method,
(B) When the composite carbonitride layer is expressed by a composition formula: (Ti _1-x Al _x ) (C _y N _1-y ), the Al content ratio x and C in the total amount of Ti and Al The proportion of C in the total amount of N and N (where x and y are atomic ratios) satisfies 0.80 ≦ x ≦ 0.95 and 0.005 ≦ y ≦ 0.05, respectively. And having a plurality of thin dividing faults dividing the layer thickness direction in the layer,
(C) The dividing layer has an average layer thickness of 1 to 10 nm, 10 to 50 layers per 1 μm in the layer thickness direction of the composite carbonitride layer, and a composition formula: (Ti _1-x Al _x ) When expressed by (C _y N _1-y ), the Al content ratio x in the total amount of Ti and Al and the C content ratio y in the total amount of C and N (where x and y are atoms) Ratio) satisfies 0.50 ≦ x ≦ 0.70 and 0.005 ≦ y <0.05, respectively.
A surface-coated cutting tool characterized by that.   2. The surface-coated cutting tool according to claim 1, wherein a Cl content ratio z (where z is an atomic ratio) occupying the total amount of atoms constituting the split layer is z ≦ 0.01. A carbide of Ti between a tool base composed of any of the above-mentioned tungsten carbide-based cemented carbide, titanium carbonitride-based cermet or cubic boron nitride-based ultra-high pressure sintered body and the above-mentioned Ti and Al composite carbonitride layer A Ti compound layer composed of one or more of a layer, a nitride layer, a carbonitride layer, a carbonate layer and a carbonitride layer, and having a total average layer thickness of 0.1 to 20 μm The surface-coated cutting tool according to claim 1, wherein the surface-coated cutting tool is present. The surface-coated cutting tool according to any one of claims 1 to 3, wherein the hard coating layer includes an aluminum oxide layer having an average layer thickness of 1 to 25 µm. The surface-coated cutting tool according to claim 1 or 2, wherein the composite carbonitride layer is formed by chemical vapor deposition containing at least trimethylaluminum as a reaction gas component.