WO2015005364A1 - Coated cutting tool - Google Patents

Coated cutting tool Download PDF

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Publication number
WO2015005364A1
WO2015005364A1 PCT/JP2014/068245 JP2014068245W WO2015005364A1 WO 2015005364 A1 WO2015005364 A1 WO 2015005364A1 JP 2014068245 W JP2014068245 W JP 2014068245W WO 2015005364 A1 WO2015005364 A1 WO 2015005364A1
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WO
WIPO (PCT)
Prior art keywords
layer
cutting tool
lower layer
coated cutting
crack
Prior art date
Application number
PCT/JP2014/068245
Other languages
French (fr)
Japanese (ja)
Inventor
雄亮 平野
高橋　欣也
Original Assignee
株式会社タンガロイ
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 株式会社タンガロイ filed Critical 株式会社タンガロイ
Priority to JP2015526364A priority Critical patent/JP6296058B2/en
Publication of WO2015005364A1 publication Critical patent/WO2015005364A1/en

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
    • C23C16/30—Deposition of compounds, mixtures or solid solutions, e.g. borides, carbides, nitrides
    • C23C16/36—Carbonitrides
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
    • C23C16/30—Deposition of compounds, mixtures or solid solutions, e.g. borides, carbides, nitrides
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
    • C23C16/30—Deposition of compounds, mixtures or solid solutions, e.g. borides, carbides, nitrides
    • C23C16/34—Nitrides
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
    • C23C16/30—Deposition of compounds, mixtures or solid solutions, e.g. borides, carbides, nitrides
    • C23C16/40—Oxides
    • C23C16/403—Oxides of aluminium, magnesium or beryllium
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
    • C23C28/04—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings of inorganic non-metallic material
    • C23C28/042—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings of inorganic non-metallic material including a refractory ceramic layer, e.g. refractory metal oxides, ZrO2, rare earth oxides
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
    • C23C28/04—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings of inorganic non-metallic material
    • C23C28/044—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings of inorganic non-metallic material coatings specially adapted for cutting tools or wear applications

Definitions

  • the present invention relates to a coated cutting tool.
  • a coated cutting tool in which a coating layer composed of multiple layers is deposited by chemical vapor deposition with a total film thickness of 3 to 20 ⁇ m is used for cutting of steel, cast iron, and the like.
  • Patent Document 2 a technique for improving the tool life of the cutting tool is known (e.g., see Patent Document 2 ).
  • the tool disclosed in Patent Document 1 has a problem that the crack resistance is inferior because the crack depth reaches from the surface of the coating to the interface of the substrate.
  • the tool disclosed in Patent Document 2 has a problem that chipping resistance is inferior because the tensile residual stress in the coating is still high.
  • the tool disclosed in Patent Document 3 has a problem that a medium used for shot peening remains in the coating and chipping occurs from the medium. Furthermore, since the process from film formation to shot peening is repeated twice, there is a problem of high cost.
  • the present invention has been made in order to solve these problems, and provides a coated cutting tool having excellent chipping resistance and chipping resistance and having a long tool life by suppressing crack growth occurring in the coated cutting tool. The purpose is to do.
  • the present inventors have conducted research on extending the tool life of the coated cutting tool. With the following configuration, the chipping resistance and chipping resistance can be improved. The knowledge that the lifetime can be extended was obtained.
  • the gist of the present invention is as follows. (1) In a coated cutting tool including a substrate and a coating layer formed on the surface of the substrate, The covering layer has an upper layer and a lower layer, The lower layer is formed on the surface of the substrate, and includes at least one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, and Si, and C, N, B And one or more compounds composed of at least one element selected from the group consisting of O and O, and the average value X of the crack spacing of the lower layer is 10 to 80 ⁇ m, The upper layer is formed on the surface of the lower layer, includes an aluminum oxide layer, and an average value Z of crack intervals of the aluminum oxide layer is 20 to 100 ⁇ m, Coated cutting tool satisfying the relationship of 0 ⁇ ZX ⁇ 90.
  • coated cutting tool according to (1) wherein an average value X of crack intervals in the lower layer and an average value Z of crack intervals in the aluminum oxide layer satisfy a relationship of 20 ⁇ ZX ⁇ 75.
  • a diffusion layer in which components of the substrate are diffused into the lower layer is formed on the substrate side of the lower layer, and an average layer thickness Td of the diffusion layer and an average layer thickness T of the lower layer are formed.
  • coated cutting tool of u satisfies a relation of 0.1 ⁇ T d / T u ⁇ 0.8 (1) or (2).
  • the component of the base material diffused in the lower layer is at least one element selected from the group consisting of W, Co, Ni, Ti, Ta, Nb, Mo, Cr, V, and Zr (1
  • the entire coating layer has an average layer thickness of 3 to 30 ⁇ m,
  • the lower layer has an average layer thickness of 1.5 to 20 ⁇ m;
  • the upper layer is an intermediate layer made of a compound composed of an element composed of Ti and Al and at least one element selected from the group consisting of C, N, and O on the surface in contact with the lower layer.
  • the coated cutting tool of the present invention includes a substrate and a coating layer formed on the surface of the substrate.
  • Specific examples of the coated cutting tool include a cutting edge exchangeable cutting insert for milling or turning, a drill, an end mill, and the like.
  • the substrate of the present invention examples include cemented carbide, cermet, ceramics, cubic boron nitride sintered body, diamond sintered body, and high speed steel.
  • the base material is a cemented carbide or cermet because it is excellent in wear resistance and fracture resistance.
  • these base materials may have a modified surface.
  • a de- ⁇ layer may be formed on the surface, or in the case of cermet, a surface hardened layer may be formed, and even if the surface is modified in this way, the present invention The effect of is shown.
  • the coating layer of the present invention has an upper layer and a lower layer.
  • the average thickness of the entire coating layer is preferably 3 to 30 ⁇ m. If it is less than 3 ⁇ m, the abrasion resistance may be inferior, and if it exceeds 30 ⁇ m, the adhesion to the substrate and the fracture resistance may be reduced. Among these, the thickness is more preferably 3 to 20 ⁇ m.
  • the lower layer of the present invention is formed on the surface of the substrate, and includes at least one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W and Si, and C, N, It is composed of one or more layers of a compound composed of at least one element selected from the group consisting of B and O.
  • the lower layer of the present invention is a compound composed of at least one element selected from the group consisting of Ti, Zr and Cr and at least one element selected from the group consisting of C, N, B and O. Preferably there is.
  • at least one of the lower layers of the present invention is made of TiCN because of excellent wear resistance and fracture resistance.
  • the lower layer of the present invention is preferably provided with a lowermost layer made of TiN on the surface in contact with the base material, since it has excellent adhesion.
  • the average layer thickness of the lowermost layer is preferably 0.05 to 1 ⁇ m.
  • the average layer thickness of the lower layer of the present invention is preferably 1.5 to 20 ⁇ m. If the average layer thickness of the lower layer is less than 1.5 ⁇ m, the wear resistance may be inferior during high-speed cutting, and if it exceeds 20 ⁇ m, the adhesion to the substrate and the fracture resistance may be reduced. Among these, 2.5 to 15 ⁇ m is more preferable.
  • the average value X of the crack interval of the lower layer of the present invention is 10 to 80 ⁇ m.
  • the average value X of the crack interval of the lower layer is less than 10 ⁇ m, the crack of the lower layer and the crack generated during the cutting process are likely to be connected, so that the chipping resistance is lowered. Since high tensile stress remains at the interface, the toughness of the lower layer is lowered and the fracture resistance is lowered.
  • the thickness is more preferably 10 to 60 ⁇ m.
  • the adhesion between the substrate and the coating layer is improved, and the coating layer is further cut during the cutting process.
  • chipping resistance is improved, which is preferable.
  • the average layer thickness T u of the mean layer thickness T d and the lower layer of the diffusion layer is preferably satisfies the relationship 0.1 ⁇ T d / T u ⁇ 0.8.
  • the component of the base material that diffuses into the diffusion layer is preferably at least one element selected from the group consisting of W, Co, Ni, Ti, Ta, Nb, Mo, Cr, V, and Zr. Among them, it is preferable that the component of the base material diffusing into the diffusion layer is Co because the toughness at the interface between the crystal grain boundaries of the lower layer is improved and the effect of suppressing the progress of cracks is high.
  • the upper layer of the present invention is formed on the surface of the lower layer, and at least one of the upper layers of the present invention includes an aluminum oxide layer (hereinafter referred to as an Al 2 O 3 layer).
  • the crystal type of the Al 2 O 3 layer is not particularly limited, and examples include ⁇ -type, ⁇ -type, ⁇ -type, ⁇ -type, ⁇ -type, ⁇ -type, pseudo- ⁇ -type, ⁇ -type, and ⁇ -type.
  • the crystalline form of the Al 2 O 3 layer is preferably a ⁇ type excellent adhesion to the high temperature stable ⁇ -type, or the intermediate layer and the Al 2 O 3 layer.
  • the Al 2 O 3 layer is an ⁇ -type Al 2 O 3 layer, chipping and chipping are less likely to occur.
  • the average layer thickness of the upper layer of the present invention is preferably 1 to 15 ⁇ m. If the average layer thickness of the upper layer is less than 1 ⁇ m, the crater wear resistance on the rake face may be reduced, and if it exceeds 15 ⁇ m, peeling tends to occur and the chipping resistance may be reduced. Among these, the thickness is more preferably 2 to 10 ⁇ m.
  • the upper layer of the present invention may be composed of only an Al 2 O 3 layer, but an element composed of Ti and Al and a group composed of C, N, and O between the Al 2 O 3 layer and the lower layer. It is preferable to include an intermediate layer composed of a compound composed of at least one element selected from the above, because the adhesiveness is excellent. Among these, TiAlCNO is preferable. The average layer thickness of the intermediate layer is preferably 0.05 to 1 ⁇ m. Further, the upper layer of the present invention may include a surface layer on the surface side of the Al 2 O 3 layer. The surface layer is preferably any one of Ti carbide, nitride, and carbonitride because the coated cutting tool can be easily identified after cutting. Among these, Ti nitride (that is, a compound represented by TiN) is more preferable because the color is most clear.
  • the average value Z of crack intervals of the Al 2 O 3 layer constituting the upper layer of the present invention is 20 to 100 ⁇ m.
  • the average value of the crack interval of the Al 2 O 3 layer is less than 20 ⁇ m, the crack of the Al 2 O 3 layer and the crack generated on the surface of the coating layer during cutting are likely to be connected, so that the chipping resistance is reduced.
  • the thickness exceeds 100 ⁇ m, high tensile residual stress remains in the Al 2 O 3 layer, so that the fracture resistance decreases.
  • the thickness is more preferably 35 to 85 ⁇ m.
  • the average value X of the crack interval of the lower layer in the coating layer of the present invention and the average value Z of the crack interval of the Al 2 O 3 layer have a relationship of 0 ⁇ ZX ⁇ 90, Since there are few cracks reaching the material, the fracture resistance is improved. Further, since the residual stress generated at the interface between the lower layer and the upper layer is reduced, the adhesion is excellent and the chipping resistance is improved. Among these, it is more preferable to have a relationship of 20 ⁇ ZX ⁇ 75.
  • Method of forming coating layer examples include the following methods.
  • the lower TiN layer has a raw material gas composition of TiCl 4 : 5.0 to 10.0 mol%, N 2 : 20 to 60 mol%, H 2 : remaining, temperature: 850 to 920 ° C., pressure: 100 to It can be formed by a chemical vapor deposition method of 350 hPa.
  • the lower TiCN layer has a raw material gas composition of TiCl 4 : 10 to 15 mol%, CH 3 CN: 1 to 3 mol%, N 2 : 0 to 20 mol%, H 2 : remaining, temperature: 850 to 920 ° C., pressure : It can be formed by a chemical vapor deposition method of 60 to 80 hPa.
  • the ZrCN layer has a raw material gas composition of ZrCl 4 : 1.6 to 4.1 mol%, N 2 : 20.0 to 40.0 mol%, CH 4 : 2.0 to 5.5 mol%, H 2 : remaining, It can be formed by a chemical vapor deposition method at a temperature of 880 to 950 ° C. and a pressure of 55 to 85 hPa.
  • the CrCN layer has a raw material gas composition of CrCl 4 : 2.1 to 5.0 mol%, N 2 : 11.6 to 28.0 mol%, CH 4 : 2.5 to 4.5 mol%, H 2 : the rest, It can be formed by a chemical vapor deposition method at a temperature of 980 to 1050 ° C. and a pressure of 80 to 120 hPa.
  • the ⁇ -type Al 2 O 3 layer has a raw material gas composition of AlCl 3 : 2.1 to 5.0 mol%, CO 2 : 2.5 to 4.0 mol%, HCl: 2.0 to 3.0 mol%, H 2 S: 0.28 to 0.45 mol%, H 2 : remaining, temperature: 900 to 1000 ° C., pressure: 60 to 80 hPa, can be formed by chemical vapor deposition.
  • the ⁇ -type Al 2 O 3 layer has a raw material gas composition of AlCl 3 : 2.1 to 5.0 mol%, CO 2 : 3.0 to 6.0 mol%, CO: 3.0 to 5.5 mol%, HCl: It can be formed by a chemical vapor deposition method with 3.0 to 5.0 mol%, H 2 S: 0.3 to 0.5 mol%, H 2 : the rest, temperature: 900 to 1000 ° C., pressure: 60 to 80 hPa. it can.
  • the TiAlCNO layer has a raw material gas composition of TiCl 4 : 3.0 to 5.0 mol%, AlCl 3 : 1.0 to 2.0 mol%, CO: 0.4 to 1.0 mol%, N 2 : 30 to 40 mol% , H 2 : the remainder, temperature: 975 to 1025 ° C., pressure: 90 to 110 hPa.
  • the TiAlCO layer has a raw material gas composition of TiCl 4 : 0.5 to 1.5 mol%, AlCl 3 : 3.0 to 5.0 mol%, CO: 2.0 to 4.0 mol%, H 2 : remaining, temperature : 975 to 1025 ° C., pressure: 60 to 100 hPa.
  • the upper TiN layer is composed of TiCl 4 : 7.0 to 10.0 mol%, N 2 : 25 to 50 mol%, H 2 : remaining, temperature: 970 to 1030 ° C., pressure: 120 to 200 hPa. Can be formed under the following conditions.
  • the upper TiCN layer has a raw material gas composition of TiCl 4 : 5.5 to 8.0 mol%, N 2 : 5.0 to 15.0 mol%, CH 3 CN: 0.5 to 1.5 mol%, H 2 :
  • the rest can be formed under the conditions of temperature: 970 to 1030 ° C. and pressure: 70 to 120 hPa.
  • the coating layer can be formed by the following method.
  • the temperature in the chamber is lowered to 200 to 400 ° C. and maintained for 1 hour or longer, thereby generating cracks in the lower layer.
  • the atmosphere in the chamber is not particularly limited, and may be a vacuum atmosphere of 30 hPa or less, and may be adjusted to a pressure of 50 to 750 hPa in a hydrogen gas, argon gas, or nitrogen gas atmosphere.
  • the diffusion layer is formed by performing the following heat treatment. That is, after forming the upper layer, the temperature in the chamber is raised to 1020 to 1100 ° C. and held for 1 to 7 hours, whereby the components of the base material diffuse into the lower layer.
  • the thickness of the diffusion layer can be controlled by adjusting the temperature in the chamber and the holding time.
  • the atmosphere in the chamber is not particularly limited, and when the pressure is adjusted to 50 to 1020 hPa in a vacuum atmosphere of 30 hPa or less, hydrogen gas, argon gas or nitrogen gas atmosphere, a coated cutting tool having a diffusion layer is obtained. Can do.
  • the average value X of the crack interval of the lower layer and the average value Z of the crack interval of the Al 2 O 3 layer are further increased.
  • dry shot blasting conditions are such that the projection material is projected at a projection speed of 50 to 80 m / sec and a projection time of 0.5 to 3 minutes so that the projection angle is 30 to 90 ° with respect to the surface of the coating layer. It is good to project.
  • the dry shot blasting medium is preferably made of a material such as Al 2 O 3 or ZrO 2 having an average particle size of 100 to 150 ⁇ m.
  • the thickness of each layer should be measured from the cross-sectional structure of the coated cutting tool using an optical microscope, scanning electron microscope (SEM), field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), etc. Can do.
  • the layer thickness of the coated cutting tool may be determined by measuring three or more layer thicknesses of each layer in the vicinity of the position of 50 ⁇ m from the cutting edge toward the center of the rake face of the coated cutting tool.
  • the composition of each layer can be measured from the cross-sectional structure of the coated cutting tool of the present invention using an energy dispersive X-ray spectrometer (EDS), a wavelength dispersive X-ray spectrometer (WDS), or the like.
  • EDS energy dispersive X-ray spectrometer
  • WDS wavelength dispersive X-ray spectrometer
  • Examples of the method for measuring the crack interval of the Al 2 O 3 layer include the following methods.
  • the surface can be mirror-polished in a direction parallel to the surface of the substrate until the Al 2 O 3 layer is exposed, and cracks can be easily observed using SEM, FE-SEM, or the like.
  • the mirror-polished surface is photographed with an SEM at a magnification of 400 to 5000 times.
  • Several straight lines are drawn on the obtained photograph to determine the distance between the crack and the intersection of the straight lines, and this is used as the crack interval. At least 50 crack intervals can be obtained, and an average value of the crack intervals can be obtained from these values.
  • Examples of the method for measuring the crack interval of the lower layer include the following methods.
  • the mirror polishing is performed in a direction parallel to the surface of the base material until the lower layer for measuring the crack interval is exposed, and etching is performed with hydrofluoric acid, the crack can be easily observed.
  • a photomicrograph is taken with an optical microscope at a magnification of 75 to 150 times on the mirror-polished surface.
  • Several straight lines are drawn on the obtained photomicrograph to determine the distance between the crack and the intersection of the straight lines, and this is taken as the crack interval. At least 50 crack intervals can be obtained, and an average value of the crack intervals can be obtained from these values.
  • the thickness of the diffusion layer of the lower layer is determined by mirror-polishing the cross section of the coating layer in the direction perpendicular to the surface of the substrate of the coated cutting tool of the present invention, and using a SEM, FE-SEM, etc. It can measure by observing.
  • the thickness of the diffusion layer of the lower layer is measured by measuring the thickness of the diffusion layer of the lower layer at three or more locations in the vicinity of the position of 50 ⁇ m from the cutting edge toward the center of the rake face of the coated cutting tool. Find the value.
  • the composition of the base material diffused into the lower layer is analyzed using the energy dispersive X-ray spectrometer (EDS) or wavelength dispersive X-ray spectrometer (WDS) from the cross-sectional structure of the coated cutting tool of the present invention. It can be measured by doing.
  • EDS energy dispersive X-ray spectrometer
  • WDS wavelength dispersive X-ray spectrometer
  • the coated cutting tool of the present invention is excellent in chipping resistance and chipping resistance, it has an effect that the tool life can be extended as compared with the prior art.
  • a cemented carbide cutting insert of 91.5WC-0.5TiC-1.8TaC-0.2NbC-6.0Co (more than mass%) in the shape of JIS standard CNMG120408 was prepared. After round honing was performed on the cutting edge ridge line portion of the base material with a SiC brush, the surface of the base material was washed. Next, the base material was charged into an external heat chemical vapor deposition apparatus, and a coating layer was formed on the surface of the base material so as to have the composition and average layer thickness of the coating layer shown in Table 1.
  • ( ⁇ ) in the crystal type of the aluminum oxide layer (Al 2 O 3 layer) represents an ⁇ -type Al 2 O 3 layer
  • ( ⁇ ) represents a ⁇ -type Al 2 O 3 layer.
  • Inventive products 1 to 19 and comparative products 2 to 5 were evacuated until a vacuum of 50 hPa or less was formed after forming the lower layer. Next, the temperature in the chamber was lowered to 250 ° C. and held for 3 hours or more to cool. After cooling, the temperature was raised to a temperature for forming the upper layer, and then the upper layer was formed. For comparative products 1 and 6 to 9, after forming the lower layer, the upper layer was formed by a conventional chemical vapor deposition method.
  • Inventive products 1 to 19 and comparative products 1, 2, 4, and 6 to 9 were subjected to dry shot blasting after forming a coating layer on the surface of the substrate.
  • the dry shot blasting conditions were such that the projection material was projected at a projection speed of 65 m / sec and a projection time of 0.5 to 3 minutes so that the projection angle was 45 ° with respect to the surface of the coating layer.
  • Al 2 O 3 having an average particle size of 150 ⁇ m was used as a dry shot blasting medium.
  • the layer thickness of each layer of the obtained sample was determined by measuring three cross sections near the position of 50 ⁇ m from the cutting edge of the coated cutting tool toward the center of the rake face with an SEM, and obtaining the average value.
  • the thickness of the diffusion layer is determined by observing the cross-section near the position of 50 ⁇ m from the cutting edge of the coated cutting tool toward the center with a SEM, and measuring the thickness of the diffusion layer at three locations, and calculating the average value. Asked.
  • the base material component diffused into the lower layer was measured by line analysis using EDS in the direction parallel to the interface between the base material and the coating layer at the center thickness position of the average thickness of the diffusion layer.
  • the average value X of the crack interval of the lower layer of the obtained sample and the average value Z of the crack interval of the aluminum oxide layer were determined as follows. First, the surface of the coated cutting tool was mirror-polished until the aluminum oxide layer was exposed, and the mirror-polished surface was photographed with an SEM at a magnification of 400 times. Ten straight lines were drawn on the obtained photograph to determine the distance between the crack and the intersection of the straight lines, and this was taken as the crack interval. For each sample, five inserts were prepared, the crack intervals at 10 locations were determined, and the average value Z of the crack intervals of the aluminum oxide layer was determined from these values. Next, mirror polishing was performed until the lower layer was exposed, and the mirror polishing surface was etched with hydrofluoric acid.
  • FC200 hardness: H B 240
  • the shape of the work material is a disc-shaped center with a diameter of 180 mm and a thickness of 60 mm, with a hole with a diameter of 60 mm, and four convex parts from the center to the outer diameter side (the edge of the convex part and the adjacent convex part The angle formed by the edge is 80 °).
  • end face cutting was performed on the work material under the following cutting conditions.
  • Table 3 shows the number of workpieces and the state of damage up to the tool life in the cutting test.
  • inventive products 1 to 19 were significantly superior in fracture resistance because none of the fractures occurred in the test conditions for evaluating fracture resistance.
  • the inventive product has a much longer tool life than the comparative product because the number of processing until reaching the tool life is larger.

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Abstract

Provided is a coated cutting tool which is suppressed in growth of a crack occurred in the coated cutting tool, thereby having excellent chipping resistance, excellent fracture resistance and a long service life. A coated cutting tool which comprises a base and a coating layer that is formed on the surface of the base, and wherein the coating layer has an upper layer and a lower layer. The lower layer is formed on the surface of the base, and is configured of one or more layers of a compound that is formed of at least one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W and Si and at least one element selected from the group consisting of C, N, B and O. The average value (X) of crack intervals in the lower layer is 10-80 μm. The upper layer is formed on the surface of the lower layer, and contains an aluminum oxide layer. The average value (Z) of crack intervals in the aluminum oxide layer is 20-100 μm, and X and Z satisfy the relational expression Z - X > 0.

Description

被覆切削工具Coated cutting tool
　本発明は、被覆切削工具に関するものである。 The present invention relates to a coated cutting tool.
　従来、超硬合金からなる基材の表面に、例えば、Ｔｉの炭化物、窒化物、炭窒化物、炭酸化物および炭窒酸化物、並びに酸化アルミニウムの中の１種の単層または２種以上の複層からなる被覆層を、化学蒸着法により、３～２０μｍの総膜厚で蒸着形成してなる被覆切削工具が、鋼や鋳鉄などの切削加工に用いられていることは良く知られている。 Conventionally, on the surface of a substrate made of cemented carbide, for example, one single layer or two or more kinds of Ti carbide, nitride, carbonitride, carbonate and carbonitride, and aluminum oxide It is well known that a coated cutting tool in which a coating layer composed of multiple layers is deposited by chemical vapor deposition with a total film thickness of 3 to 20 μm is used for cutting of steel, cast iron, and the like. .
　通常、炭化タングステン基超硬合金の表面に被膜を形成すると、被膜に引張応力が残留するために、被覆切削工具の破壊強度が低下して欠損し易くなるとされている。これまで、被膜形成後、ショットピーニング等によりクラックを発生させることにより、引張残留応力を開放することが提案され、かなりの効果が得られている（例えば、特許文献１参照）。 Usually, when a film is formed on the surface of a tungsten carbide-based cemented carbide, tensile stress remains in the film, so that the fracture strength of the coated cutting tool is reduced and the chip tends to be broken. So far, it has been proposed to release the tensile residual stress by generating a crack by shot peening or the like after the coating is formed, and a considerable effect has been obtained (for example, see Patent Document 1).
　また、被覆層の特性を改善するため、Ａｌ２Ｏ３層形成後の冷却時に発生するクラックを無くすことで、切削工具の切削寿命を向上する技術が知られている（例えば、特許文献２参照）。 Moreover, to improve the properties of the coating layer, by eliminating the cracks generated during cooling after the Al 2 O 3 layer formed, a technique for improving the tool life of the cutting tool is known (e.g., see Patent Document 2 ).
　さらに、基材側下方部分の被膜に高密度クラックを有し、表面側上方部分の被膜低密度クラックを有した切削工具が知られている（例えば、特許文献３参照）。 Furthermore, a cutting tool having a high-density crack in the coating on the lower part on the substrate side and a coating low-density crack on the upper part on the surface side is known (for example, see Patent Document 3).
特開平５－１１６００３号公報Japanese Patent Laid-Open No. 5-116003 特開平７－２１６５４９号公報JP 7-216549 A 特開平６－２４６５１２号公報JP-A-6-246512
　近年の切削加工では高速化、高送り化および深切込み化が顕著となり、従来よりも工具寿命が低下する傾向が見られるようになってきた。この様な背景により、上記特許文献１に開示された工具であっても、クラックの深さが被膜の表面から基材の界面まで達しているため、耐欠損性が劣るという問題があった。また、特許文献２で開示された工具は、依然として被膜中の引張残留応力が高いため、耐チッピング性が劣るという問題点があった。さらに、特許文献３で開示された工具は、ショットピーニングに使用するメディアが被膜中に残留し、そのメディアを起点にチッピングが生じるという問題があった。さらに、被膜の形成からショットピーニングまでの工程を２回繰り返すため、コストが高いという問題があった。本発明は、これらの問題を解決するためになされたものであり、被覆切削工具に生じるクラック進展の抑制により、優れた耐チッピング性および耐欠損性を持ち、工具寿命の長い被覆切削工具を提供することを目的とする。 In recent years, high speed, high feed, and deep cutting have become prominent in cutting, and the tool life has been declining compared to the past. Due to such a background, even the tool disclosed in Patent Document 1 has a problem that the crack resistance is inferior because the crack depth reaches from the surface of the coating to the interface of the substrate. Moreover, the tool disclosed in Patent Document 2 has a problem that chipping resistance is inferior because the tensile residual stress in the coating is still high. Furthermore, the tool disclosed in Patent Document 3 has a problem that a medium used for shot peening remains in the coating and chipping occurs from the medium. Furthermore, since the process from film formation to shot peening is repeated twice, there is a problem of high cost. The present invention has been made in order to solve these problems, and provides a coated cutting tool having excellent chipping resistance and chipping resistance and having a long tool life by suppressing crack growth occurring in the coated cutting tool. The purpose is to do.
　本発明者らは、上述の観点から、被覆切削工具の工具寿命の延長について研究を重ねたところ、以下の構成にすると、耐チッピング性および耐欠損性を向上させることができ、その結果、工具寿命を延長することができるという知見を得た。 From the above point of view, the present inventors have conducted research on extending the tool life of the coated cutting tool. With the following configuration, the chipping resistance and chipping resistance can be improved. The knowledge that the lifetime can be extended was obtained.
　すなわち、本発明の要旨は以下の通りである。
（１）基材と、該基材の表面に形成された被覆層とを含む被覆切削工具において、
　前記被覆層は、上部層と下部層とを有し、
　前記下部層は前記基材の表面に形成され、Ｔｉ、Ｚｒ、Ｈｆ、Ｖ、Ｎｂ、Ｔａ、Ｃｒ、Ｍｏ、ＷおよびＳｉからなる群より選ばれる少なくとも１種の元素と、Ｃ、Ｎ、ＢおよびＯからなる群より選ばれる少なくとも１種の元素とで構成される化合物の１層または２層以上から構成され、前記下部層のクラック間隔の平均値Ｘが１０～８０μｍであり、
　前記上部層は前記下部層の表面に形成され、酸化アルミニウム層を含み、前記酸化アルミニウム層のクラック間隔の平均値Ｚが２０～１００μｍであり、
　０＜Ｚ－Ｘ＜９０の関係を満たす被覆切削工具。
（２）前記下部層のクラック間隔の平均値Ｘと前記酸化アルミニウム層のクラック間隔の平均値Ｚとが２０＜Ｚ－Ｘ＜７５の関係を満たす（１）の被覆切削工具。
（３）前記下部層の前記基材側には、前記基材の成分が前記下部層に拡散した拡散層が形成され、前記拡散層の平均層厚Ｔｄと前記下部層の平均層厚Ｔｕは０．１≦Ｔｄ／Ｔｕ≦０．８の関係を満たす（１）または（２）の被覆切削工具。
（４）前記下部層に拡散した前記基材の成分は、Ｗ、Ｃｏ、Ｎｉ、Ｔｉ、Ｔａ、Ｎｂ、Ｍｏ、Ｃｒ、ＶおよびＺｒからなる群より選ばれる少なくとも１種の元素である（１）～（３）のいずれかの被覆切削工具。
（５）前記被覆層全体の層厚が３～３０μｍの平均層厚を有し、
　前記下部層の層厚が１．５～２０μｍの平均層厚を有し、
　前記上部層の層厚が１～１５μｍの平均層厚を有する前記下部層の層厚が１．５～２０μｍの平均層厚を有する（１）～（４）のいずれかの被覆切削工具。
　（６）前記上部層は、前記下部層と接する表面に、ＴｉとＡｌからなる元素と、Ｃ、ＮおよびＯからなる群より選ばれる少なくとも１種の元素とで構成される化合物からなる中間層を含む（１）～（５）のいずれかの被覆切削工具。
　（７）前記基材は、超硬合金またはサーメットのいずれかである（１）～（６）のいずれかの被覆切削工具。 That is, the gist of the present invention is as follows.
(1) In a coated cutting tool including a substrate and a coating layer formed on the surface of the substrate,
The covering layer has an upper layer and a lower layer,
The lower layer is formed on the surface of the substrate, and includes at least one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, and Si, and C, N, B And one or more compounds composed of at least one element selected from the group consisting of O and O, and the average value X of the crack spacing of the lower layer is 10 to 80 μm,
The upper layer is formed on the surface of the lower layer, includes an aluminum oxide layer, and an average value Z of crack intervals of the aluminum oxide layer is 20 to 100 μm,
Coated cutting tool satisfying the relationship of 0 <ZX <90.
(2) The coated cutting tool according to (1), wherein an average value X of crack intervals in the lower layer and an average value Z of crack intervals in the aluminum oxide layer satisfy a relationship of 20 <ZX <75.
(3) A diffusion layer in which components of the substrate are diffused into the lower layer is formed on the substrate side of the lower layer, and an average layer thickness Td of the diffusion layer and an average layer thickness T of the lower layer are formed. coated cutting tool of u satisfies a relation of 0.1 ≦ T d / T u ≦ 0.8 (1) or (2).
(4) The component of the base material diffused in the lower layer is at least one element selected from the group consisting of W, Co, Ni, Ti, Ta, Nb, Mo, Cr, V, and Zr (1 The coated cutting tool according to any one of) to (3).
(5) The entire coating layer has an average layer thickness of 3 to 30 μm,
The lower layer has an average layer thickness of 1.5 to 20 μm;
The coated cutting tool according to any one of (1) to (4), wherein the upper layer has an average layer thickness of 1 to 15 μm and the lower layer has an average layer thickness of 1.5 to 20 μm.
(6) The upper layer is an intermediate layer made of a compound composed of an element composed of Ti and Al and at least one element selected from the group consisting of C, N, and O on the surface in contact with the lower layer. A coated cutting tool according to any one of (1) to (5).
(7) The coated cutting tool according to any one of (1) to (6), wherein the base material is either cemented carbide or cermet.
＜被覆切削工具＞
　本発明の被覆切削工具は、基材とその基材の表面に形成された被覆層とを含む。被覆切削工具の種類として、具体的には、フライス加工用または旋削加工用刃先交換型切削インサート、ドリル、エンドミルなどを挙げることができる。 <Coated cutting tool>
The coated cutting tool of the present invention includes a substrate and a coating layer formed on the surface of the substrate. Specific examples of the coated cutting tool include a cutting edge exchangeable cutting insert for milling or turning, a drill, an end mill, and the like.
＜基材＞
　本発明の基材は、例えば、超硬合金、サーメット、セラミックス、立方晶窒化硼素焼結体、ダイヤモンド焼結体および高速度鋼などを挙げることができる。その中でも、基材が超硬合金またはサーメットであると、耐摩耗性および耐欠損性に優れるので、さらに好ましい。 <Base material>
Examples of the substrate of the present invention include cemented carbide, cermet, ceramics, cubic boron nitride sintered body, diamond sintered body, and high speed steel. Among these, it is more preferable that the base material is a cemented carbide or cermet because it is excellent in wear resistance and fracture resistance.
　なお、これらの基材は、その表面が改質されたものであっても差し支えない。例えば、超硬合金の場合はその表面に脱β層が形成されていたり、サーメットの場合には表面硬化層が形成されていてもよく、このように表面が改質されていても、本発明の効果は示される。 It should be noted that these base materials may have a modified surface. For example, in the case of cemented carbide, a de-β layer may be formed on the surface, or in the case of cermet, a surface hardened layer may be formed, and even if the surface is modified in this way, the present invention The effect of is shown.
　＜被覆層＞
　本発明の被覆層は、上部層と下部層とを有する。被覆層全体の平均層厚は、３～３０μｍであることが好ましい。３μｍ未満であると、耐摩耗性に劣る場合があり、３０μｍを超えると、基材との密着性および耐欠損性が低下する場合がある。その中でも、３～２０μｍであるとさらに好ましい。 <Coating layer>
The coating layer of the present invention has an upper layer and a lower layer. The average thickness of the entire coating layer is preferably 3 to 30 μm. If it is less than 3 μm, the abrasion resistance may be inferior, and if it exceeds 30 μm, the adhesion to the substrate and the fracture resistance may be reduced. Among these, the thickness is more preferably 3 to 20 μm.
＜下部層＞
　本発明の下部層は基材の表面に形成され、Ｔｉ、Ｚｒ、Ｈｆ、Ｖ、Ｎｂ、Ｔａ、Ｃｒ、Ｍｏ、ＷおよびＳｉからなる群より選ばれる少なくとも１種の元素と、Ｃ、Ｎ、ＢおよびＯからなる群より選ばれる少なくとも１種の元素とで構成される化合物の１層または２層以上から構成されるものである。 <Lower layer>
The lower layer of the present invention is formed on the surface of the substrate, and includes at least one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W and Si, and C, N, It is composed of one or more layers of a compound composed of at least one element selected from the group consisting of B and O.
　本発明の下部層は、Ｔｉ、ＺｒおよびＣｒからなる群より選ばれる少なくとも１種の元素と、Ｃ、Ｎ、ＢおよびＯからなる群より選ばれる少なくとも１種の元素とで構成される化合物であると好ましい。また、本発明の下部層の少なくとも１層は、ＴｉＣＮからなると、耐摩耗性および耐欠損性に優れるため好ましい。さらに、本発明の下部層は、基材と接する表面にＴｉＮからなる最下層を備えると密着性に優れるため、好ましい。前記最下層の平均層厚は、０．０５～１μｍであることが好ましい。 The lower layer of the present invention is a compound composed of at least one element selected from the group consisting of Ti, Zr and Cr and at least one element selected from the group consisting of C, N, B and O. Preferably there is. In addition, it is preferable that at least one of the lower layers of the present invention is made of TiCN because of excellent wear resistance and fracture resistance. Further, the lower layer of the present invention is preferably provided with a lowermost layer made of TiN on the surface in contact with the base material, since it has excellent adhesion. The average layer thickness of the lowermost layer is preferably 0.05 to 1 μm.
　本発明の下部層の平均層厚は、１．５～２０μｍであることが好ましい。下部層の平均層厚が、１．５μｍ未満では、高速切削時に耐摩耗性に劣る場合があり、２０μｍを超えると、基材との密着性および耐欠損性が低下する場合がある。その中でも、２．５～１５μｍであるとさらに好ましい。 The average layer thickness of the lower layer of the present invention is preferably 1.5 to 20 μm. If the average layer thickness of the lower layer is less than 1.5 μm, the wear resistance may be inferior during high-speed cutting, and if it exceeds 20 μm, the adhesion to the substrate and the fracture resistance may be reduced. Among these, 2.5 to 15 μm is more preferable.
　本発明の下部層のクラック間隔の平均値Ｘは１０～８０μｍである。下部層のクラック間隔の平均値Ｘが、１０μｍ未満であると下部層のクラックと切削加工中に発生した亀裂とがつながりやすいため、耐チッピング性が低下し、８０μｍを超えると基材と被覆層との界面に高い引張応力が残留しているため、下部層の靱性が低下し、耐欠損性が低下する。その中でも、１０～６０μｍであるとさらに好ましい。 The average value X of the crack interval of the lower layer of the present invention is 10 to 80 μm. When the average value X of the crack interval of the lower layer is less than 10 μm, the crack of the lower layer and the crack generated during the cutting process are likely to be connected, so that the chipping resistance is lowered. Since high tensile stress remains at the interface, the toughness of the lower layer is lowered and the fracture resistance is lowered. Among these, the thickness is more preferably 10 to 60 μm.
　本発明の下部層の基材側には、基材の成分が下部層に拡散した拡散層が形成されると、基材と被覆層との密着性が向上し、さらに切削加工中に被覆層の表面に発生した亀裂が下部層で進展するのを抑制するため、耐チッピング性が向上するので好ましい。拡散層の平均層厚Ｔｄと下部層の平均層厚Ｔｕとの関係Ｔｄ／Ｔｕが０．１未満であると、基材と下部層との密着性が低くなる傾向があり、切削加工中に発生した亀裂の進展を下部層で抑制する効果が得られない。拡散層の平均層厚Ｔｄと下部層の平均層厚Ｔｕとの関係Ｔｄ／Ｔｕが０．８を超えると、下部層と上部層との密着性が低くなる傾向があり、耐チッピング性が低下する。このため、拡散層の平均層厚Ｔｄと下部層の平均層厚Ｔｕは０．１≦Ｔｄ／Ｔｕ≦０．８の関係を満たすと好ましい。また、拡散層に拡散する基材の成分は、Ｗ、Ｃｏ、Ｎｉ、Ｔｉ、Ｔａ、Ｎｂ、Ｍｏ、Ｃｒ、ＶおよびＺｒからなる群より選ばれる少なくとも１種の元素であると好ましい。その中でも、拡散層に拡散する基材の成分がＣｏであると、下部層の結晶粒界の界面の靱性が向上し、亀裂の進展を抑制する効果が高いため好ましい。 When the diffusion layer in which the components of the substrate are diffused into the lower layer is formed on the substrate side of the lower layer of the present invention, the adhesion between the substrate and the coating layer is improved, and the coating layer is further cut during the cutting process. In order to suppress the crack generated on the surface of the metal from progressing in the lower layer, chipping resistance is improved, which is preferable. When the relationship T d / T u between the average layer thickness T d of the diffusion layer and the average layer thickness T u of the lower layer is less than 0.1, the adhesion between the substrate and the lower layer tends to be low, The effect of suppressing the progress of cracks generated during the cutting process at the lower layer cannot be obtained. When the relationship T d / T u and the average layer thickness T u of the mean layer thickness T d and the lower layer of the diffusion layer is more than 0.8, there is a tendency that adhesion between the lower layer and the upper layer is lowered, resistance Chipping properties are reduced. Accordingly, the average layer thickness T u of the mean layer thickness T d and the lower layer of the diffusion layer is preferably satisfies the relationship 0.1 ≦ T d / T u ≦ 0.8. The component of the base material that diffuses into the diffusion layer is preferably at least one element selected from the group consisting of W, Co, Ni, Ti, Ta, Nb, Mo, Cr, V, and Zr. Among them, it is preferable that the component of the base material diffusing into the diffusion layer is Co because the toughness at the interface between the crystal grain boundaries of the lower layer is improved and the effect of suppressing the progress of cracks is high.
＜上部層＞
　本発明の上部層は、下部層の表面に形成され、本発明の上部層の少なくとも１層は、酸化アルミニウム層（以下、Ａｌ２Ｏ３層）を含む。Ａｌ２Ｏ３層の結晶型は特に限定されず、α型、β型、δ型、γ型、κ型、χ型、擬τ型、η型およびρ型等が挙げられる。これらの中でも、Ａｌ２Ｏ３層の結晶型は、高温で安定なα型、または中間層とＡｌ２Ｏ３層との密着性に優れるκ型であると好ましい。特に、高速切削など切削に関与する領域が高温になる場合において、Ａｌ２Ｏ３層がα型Ａｌ２Ｏ３層であると、欠損やチッピングを起こしにくくなる。 <Upper layer>
The upper layer of the present invention is formed on the surface of the lower layer, and at least one of the upper layers of the present invention includes an aluminum oxide layer (hereinafter referred to as an Al 2 O 3 layer). The crystal type of the Al 2 O 3 layer is not particularly limited, and examples include α-type, β-type, δ-type, γ-type, κ-type, χ-type, pseudo-τ-type, η-type, and ρ-type. Among these, the crystalline form of the Al 2 O 3 layer is preferably a κ type excellent adhesion to the high temperature stable α-type, or the intermediate layer and the Al 2 O 3 layer. In particular, when the region involved in cutting such as high-speed cutting is at a high temperature, if the Al 2 O 3 layer is an α-type Al 2 O 3 layer, chipping and chipping are less likely to occur.
　本発明の上部層の平均層厚は、１～１５μｍであることが好ましい。上部層の平均層厚が１μｍ未満では、すくい面における耐クレータ摩耗性が低下する場合があり、１５μｍを超えると、剥離が生じやすくなり、耐欠損性が低下する場合がある。その中でも、２～１０μｍであるとさらに好ましい。 The average layer thickness of the upper layer of the present invention is preferably 1 to 15 μm. If the average layer thickness of the upper layer is less than 1 μm, the crater wear resistance on the rake face may be reduced, and if it exceeds 15 μm, peeling tends to occur and the chipping resistance may be reduced. Among these, the thickness is more preferably 2 to 10 μm.
　本発明の上部層は、Ａｌ２Ｏ３層だけで構成されてもよいが、Ａｌ２Ｏ３層と下部層との間に、ＴｉとＡｌからなる元素と、Ｃ、ＮおよびＯからなる群より選ばれる少なくとも１種の元素とで構成される化合物からなる中間層を含むと、密着性に優れるため、好ましい。その中でも、ＴｉＡｌＣＮＯであると好ましい。中間層の平均層厚は、０．０５～１μｍであることが好ましい。また、本発明の上部層は、Ａｌ２Ｏ３層より表面側に表面層を含んでもよい。表面層は、Ｔｉの炭化物、窒化物、および炭窒化物のいずれかであると、切削使用後の被覆切削工具の識別が容易となるため、好ましい。その中でも、Ｔｉの窒化物（すなわちＴｉＮで表される化合物）であると、色彩が最も明瞭であるため、さらに好ましい。 The upper layer of the present invention may be composed of only an Al 2 O 3 layer, but an element composed of Ti and Al and a group composed of C, N, and O between the Al 2 O 3 layer and the lower layer. It is preferable to include an intermediate layer composed of a compound composed of at least one element selected from the above, because the adhesiveness is excellent. Among these, TiAlCNO is preferable. The average layer thickness of the intermediate layer is preferably 0.05 to 1 μm. Further, the upper layer of the present invention may include a surface layer on the surface side of the Al 2 O 3 layer. The surface layer is preferably any one of Ti carbide, nitride, and carbonitride because the coated cutting tool can be easily identified after cutting. Among these, Ti nitride (that is, a compound represented by TiN) is more preferable because the color is most clear.
　本発明の上部層を構成するＡｌ２Ｏ３層のクラック間隔の平均値Ｚは、２０～１００μｍである。Ａｌ２Ｏ３層のクラック間隔の平均値が２０μｍ未満であると、Ａｌ２Ｏ３層のクラックと切削加工中に被覆層の表面に発生した亀裂とがつながりやすいため、耐チッピング性が低下する。一方、１００μｍを超えると、Ａｌ２Ｏ３層に高い引張残留応力が残留しているため、耐欠損性が低下する。その中でも、３５～８５μｍであるとさらに好ましい。 The average value Z of crack intervals of the Al 2 O 3 layer constituting the upper layer of the present invention is 20 to 100 μm. When the average value of the crack interval of the Al 2 O 3 layer is less than 20 μm, the crack of the Al 2 O 3 layer and the crack generated on the surface of the coating layer during cutting are likely to be connected, so that the chipping resistance is reduced. . On the other hand, when the thickness exceeds 100 μm, high tensile residual stress remains in the Al 2 O 3 layer, so that the fracture resistance decreases. Among these, the thickness is more preferably 35 to 85 μm.
　本発明の被覆層における下部層のクラック間隔の平均値ＸとＡｌ２Ｏ３層のクラック間隔の平均値Ｚとが、０＜Ｚ－Ｘ＜９０の関係を有すると、上部層の表面から基材まで到達するクラックが少ないため、耐欠損性が向上する。また、下部層と上部層との界面に生じる残留応力が小さくなるため、密着性に優れ、耐チッピング性が向上する。その中でも、２０＜Ｚ－Ｘ＜７５の関係を有すると、さらに好ましい。 When the average value X of the crack interval of the lower layer in the coating layer of the present invention and the average value Z of the crack interval of the Al 2 O 3 layer have a relationship of 0 <ZX <90, Since there are few cracks reaching the material, the fracture resistance is improved. Further, since the residual stress generated at the interface between the lower layer and the upper layer is reduced, the adhesion is excellent and the chipping resistance is improved. Among these, it is more preferable to have a relationship of 20 <ZX <75.
〔被覆層の形成方法〕
　本発明の被覆切削工具における被覆層を構成する各層の形成方法として、例えば、以下の方法を挙げることができる。 [Method of forming coating layer]
Examples of the method for forming each layer constituting the coating layer in the coated cutting tool of the present invention include the following methods.
　例えば、下部層のＴｉＮ層は、原料ガス組成をＴｉＣｌ４：５．０～１０．０ｍｏｌ％、Ｎ２：２０～６０ｍｏｌ％、Ｈ２：残りとし、温度：８５０～９２０℃、圧力：１００～３５０ｈＰａとする化学蒸着法で形成することができる。 For example, the lower TiN layer has a raw material gas composition of TiCl 4 : 5.0 to 10.0 mol%, N 2 : 20 to 60 mol%, H 2 : remaining, temperature: 850 to 920 ° C., pressure: 100 to It can be formed by a chemical vapor deposition method of 350 hPa.
　下部層のＴｉＣＮ層は、原料ガス組成をＴｉＣｌ４：１０～１５ｍｏｌ％、ＣＨ３ＣＮ：１～３ｍｏｌ％、Ｎ２：０～２０ｍｏｌ％、Ｈ２：残りとし、温度：８５０～９２０℃、圧力：６０～８０ｈＰａとする化学蒸着法で形成することができる。 The lower TiCN layer has a raw material gas composition of TiCl 4 : 10 to 15 mol%, CH 3 CN: 1 to 3 mol%, N 2 : 0 to 20 mol%, H 2 : remaining, temperature: 850 to 920 ° C., pressure : It can be formed by a chemical vapor deposition method of 60 to 80 hPa.
　ＺｒＣＮ層は、原料ガス組成をＺｒＣｌ４：１．６～４．１ｍｏｌ％、Ｎ２：２０．０～４０．０ｍｏｌ％、ＣＨ４：２．０～５．５ｍｏｌ％、Ｈ２：残りとし、温度：８８０～９５０℃、圧力：５５～８５ｈＰａとする化学蒸着法で形成することができる。 The ZrCN layer has a raw material gas composition of ZrCl 4 : 1.6 to 4.1 mol%, N 2 : 20.0 to 40.0 mol%, CH 4 : 2.0 to 5.5 mol%, H 2 : remaining, It can be formed by a chemical vapor deposition method at a temperature of 880 to 950 ° C. and a pressure of 55 to 85 hPa.
　ＣｒＣＮ層は、原料ガス組成をＣｒＣｌ４：２．１～５．０ｍｏｌ％、Ｎ２：１１．６～２８．０ｍｏｌ％、ＣＨ４：２．５～４．５ｍｏｌ％、Ｈ２：残りとし、温度：９８０～１０５０℃、圧力：８０～１２０ｈＰａとする化学蒸着法で形成することができる。 The CrCN layer has a raw material gas composition of CrCl 4 : 2.1 to 5.0 mol%, N 2 : 11.6 to 28.0 mol%, CH 4 : 2.5 to 4.5 mol%, H 2 : the rest, It can be formed by a chemical vapor deposition method at a temperature of 980 to 1050 ° C. and a pressure of 80 to 120 hPa.
　α型Ａｌ２Ｏ３層は、原料ガス組成をＡｌＣｌ３：２．１～５．０ｍｏｌ％、ＣＯ２：２．５～４．０ｍｏｌ％、ＨＣｌ：２．０～３．０ｍｏｌ％、Ｈ２Ｓ：０．２８～０．４５ｍｏｌ％、Ｈ２：残りとし、温度：９００～１０００℃、圧力：６０～８０ｈＰａとする化学蒸着法で形成することができる。 The α-type Al 2 O 3 layer has a raw material gas composition of AlCl 3 : 2.1 to 5.0 mol%, CO 2 : 2.5 to 4.0 mol%, HCl: 2.0 to 3.0 mol%, H 2 S: 0.28 to 0.45 mol%, H 2 : remaining, temperature: 900 to 1000 ° C., pressure: 60 to 80 hPa, can be formed by chemical vapor deposition.
　κ型Ａｌ２Ｏ３層は、原料ガス組成をＡｌＣｌ３：２．１～５．０ｍｏｌ％、ＣＯ２：３．０～６．０ｍｏｌ％、ＣＯ：３．０～５．５ｍｏｌ％、ＨＣｌ：３．０～５．０ｍｏｌ％、Ｈ２Ｓ：０．３～０．５ｍｏｌ％、Ｈ２：残りとし、温度：９００～１０００℃、圧力：６０～８０ｈＰａとする化学蒸着法で形成することができる。 The κ-type Al 2 O 3 layer has a raw material gas composition of AlCl 3 : 2.1 to 5.0 mol%, CO 2 : 3.0 to 6.0 mol%, CO: 3.0 to 5.5 mol%, HCl: It can be formed by a chemical vapor deposition method with 3.0 to 5.0 mol%, H 2 S: 0.3 to 0.5 mol%, H 2 : the rest, temperature: 900 to 1000 ° C., pressure: 60 to 80 hPa. it can.
　ＴｉＡｌＣＮＯ層は、原料ガス組成をＴｉＣｌ４：３．０～５．０ｍｏｌ％、ＡｌＣｌ３：１．０～２．０ｍｏｌ％、ＣＯ：０．４～１．０ｍｏｌ％、Ｎ２：３０～４０ｍｏｌ％、Ｈ２：残りとし、温度：９７５～１０２５℃、圧力：９０～１１０ｈＰａとする化学蒸着法で形成することができる。 The TiAlCNO layer has a raw material gas composition of TiCl 4 : 3.0 to 5.0 mol%, AlCl 3 : 1.0 to 2.0 mol%, CO: 0.4 to 1.0 mol%, N 2 : 30 to 40 mol% , H 2 : the remainder, temperature: 975 to 1025 ° C., pressure: 90 to 110 hPa.
　ＴｉＡｌＣＯ層は、原料ガス組成をＴｉＣｌ４：０．５～１．５ｍｏｌ％、ＡｌＣｌ３：３．０～５．０ｍｏｌ％、ＣＯ：２．０～４．０ｍｏｌ％、Ｈ２：残りとし、温度：９７５～１０２５℃、圧力：６０～１００ｈＰａとする化学蒸着法で形成することができる。 The TiAlCO layer has a raw material gas composition of TiCl 4 : 0.5 to 1.5 mol%, AlCl 3 : 3.0 to 5.0 mol%, CO: 2.0 to 4.0 mol%, H 2 : remaining, temperature : 975 to 1025 ° C., pressure: 60 to 100 hPa.
　上部層のＴｉＮ層は、原料ガス組成をＴｉＣｌ４：７．０～１０．０ｍｏｌ％、Ｎ２：２５～５０ｍｏｌ％、Ｈ２：残りとし、温度：９７０～１０３０℃、圧力：１２０～２００ｈＰａとする条件で形成することができる。 The upper TiN layer is composed of TiCl 4 : 7.0 to 10.0 mol%, N 2 : 25 to 50 mol%, H 2 : remaining, temperature: 970 to 1030 ° C., pressure: 120 to 200 hPa. Can be formed under the following conditions.
　上部層のＴｉＣＮ層は、原料ガス組成をＴｉＣｌ４：５．５～８．０ｍｏｌ％、Ｎ２：５．０～１５．０ｍｏｌ％、ＣＨ３ＣＮ：０．５～１．５ｍｏｌ％、Ｈ２：残りとし、温度：９７０～１０３０℃、圧力：７０～１２０ｈＰａとする条件で形成することができる。 The upper TiCN layer has a raw material gas composition of TiCl 4 : 5.5 to 8.0 mol%, N 2 : 5.0 to 15.0 mol%, CH 3 CN: 0.5 to 1.5 mol%, H 2 : The rest can be formed under the conditions of temperature: 970 to 1030 ° C. and pressure: 70 to 120 hPa.
　下部層のクラック間隔の平均値ＸとＡｌ２Ｏ３層のクラック間隔の平均値ＺとがＺ－Ｘ＞０を満たすために、以下の方法によって被覆層を形成することができる。 In order that the average value X of the crack interval of the lower layer and the average value Z of the crack interval of the Al 2 O 3 layer satisfy Z−X> 0, the coating layer can be formed by the following method.
　すなわち、下部層を８５０～１０５０℃の温度で形成した後に、チャンバ内の温度を２００～４００℃に下げ、１時間以上保持することで、下部層にクラックを発生させることができる。このとき、チャンバ内の雰囲気は特に限定されず、３０ｈＰａ以下の真空雰囲気であってもよく、水素ガス、アルゴンガスまたは窒素ガス雰囲気で５０～７５０ｈＰａの圧力となるように調整してもよい。冷却して保持した後、上部層を形成する温度まで上昇し、従来公知の形成条件で上部層を形成すると、０＜Ｚ－Ｘ＜９０の関係を満たした被覆切削工具が得られる。 That is, after the lower layer is formed at a temperature of 850 to 1050 ° C., the temperature in the chamber is lowered to 200 to 400 ° C. and maintained for 1 hour or longer, thereby generating cracks in the lower layer. At this time, the atmosphere in the chamber is not particularly limited, and may be a vacuum atmosphere of 30 hPa or less, and may be adjusted to a pressure of 50 to 750 hPa in a hydrogen gas, argon gas, or nitrogen gas atmosphere. After cooling and holding, when the temperature is raised to the temperature for forming the upper layer and the upper layer is formed under the conventionally known formation conditions, a coated cutting tool satisfying the relationship of 0 <ZX <90 is obtained.
　拡散層は、以下の熱処理を施すことで形成される。すなわち、上部層を形成した後、チャンバ内の温度を１０２０～１１００℃に昇温し、１～７時間保持することで、基材の成分が下部層に拡散する。拡散層の厚さは、チャンバ内の温度と保持時間を調節することで制御することができる。チャンバ内の雰囲気は特に限定されず、３０ｈＰａ以下の真空雰囲気、水素ガス、アルゴンガスまたは窒素ガス雰囲気で５０～１０２０ｈＰａの圧力となるように調整すると、拡散層が形成された被覆切削工具を得ることができる。 The diffusion layer is formed by performing the following heat treatment. That is, after forming the upper layer, the temperature in the chamber is raised to 1020 to 1100 ° C. and held for 1 to 7 hours, whereby the components of the base material diffuse into the lower layer. The thickness of the diffusion layer can be controlled by adjusting the temperature in the chamber and the holding time. The atmosphere in the chamber is not particularly limited, and when the pressure is adjusted to 50 to 1020 hPa in a vacuum atmosphere of 30 hPa or less, hydrogen gas, argon gas or nitrogen gas atmosphere, a coated cutting tool having a diffusion layer is obtained. Can do.
　基材の表面に被覆層を形成した後、乾式ショットブラスト、湿式ショットブラストまたはショットピーニングを施すと、下部層のクラック間隔の平均値ＸとＡｌ２Ｏ３層のクラック間隔の平均値Ｚをさらに容易に制御できるため、好ましい。例えば、乾式ショットブラストの条件は、被覆層の表面に対して投射角度が３０～９０°になるように、投射材を５０～８０ｍ／ｓｅｃの投射速度、０．５～３分の投射時間で投射するとよい。乾式ショットブラストのメディアは、平均粒径１００～１５０μｍのＡｌ２Ｏ３やＺｒＯ２などの材質であると好ましい。 After forming a coating layer on the surface of the substrate, when dry shot blasting, wet shot blasting or shot peening is performed, the average value X of the crack interval of the lower layer and the average value Z of the crack interval of the Al 2 O 3 layer are further increased. This is preferable because it can be easily controlled. For example, dry shot blasting conditions are such that the projection material is projected at a projection speed of 50 to 80 m / sec and a projection time of 0.5 to 3 minutes so that the projection angle is 30 to 90 ° with respect to the surface of the coating layer. It is good to project. The dry shot blasting medium is preferably made of a material such as Al 2 O 3 or ZrO 2 having an average particle size of 100 to 150 μm.
　各層の層厚は、被覆切削工具の断面組織から光学顕微鏡、走査型電子顕微鏡（ＳＥＭ）、電界放射型走査電子顕微鏡（ＦＥ－ＳＥＭ）、透過型電子顕微鏡（ＴＥＭ）などを用いて測定することができる。なお、被覆切削工具の層厚は、刃先から被覆切削工具のすくい面の中心部に向かって５０μｍの位置の近傍において、各層の層厚を３箇所以上測定し、その平均値を求めるとよい。各層の組成は、本発明の被覆切削工具の断面組織からエネルギー分散型Ｘ線分光器（ＥＤＳ）や波長分散型Ｘ線分光器（ＷＤＳ）などを用いて測定することができる。 The thickness of each layer should be measured from the cross-sectional structure of the coated cutting tool using an optical microscope, scanning electron microscope (SEM), field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), etc. Can do. The layer thickness of the coated cutting tool may be determined by measuring three or more layer thicknesses of each layer in the vicinity of the position of 50 μm from the cutting edge toward the center of the rake face of the coated cutting tool. The composition of each layer can be measured from the cross-sectional structure of the coated cutting tool of the present invention using an energy dispersive X-ray spectrometer (EDS), a wavelength dispersive X-ray spectrometer (WDS), or the like.
　Ａｌ２Ｏ３層のクラック間隔の測定方法として、例えば、以下の方法を挙げることができる。Ａｌ２Ｏ３層が露出するまで基材の表面に対して平行な方向に鏡面研磨し、ＳＥＭ、ＦＥ－ＳＥＭなどを用いてクラックを容易に観察することができる。鏡面研磨面を、４００～５０００倍の倍率でＳＥＭにて写真を撮影する。得られた写真に数本の直線を引き、クラックとその直線の交点間の距離を求め、それをクラック間隔とする。少なくとも５０箇所のクラック間隔を求め、それらの値からクラック間隔の平均値を求めることができる。 Examples of the method for measuring the crack interval of the Al 2 O 3 layer include the following methods. The surface can be mirror-polished in a direction parallel to the surface of the substrate until the Al 2 O 3 layer is exposed, and cracks can be easily observed using SEM, FE-SEM, or the like. The mirror-polished surface is photographed with an SEM at a magnification of 400 to 5000 times. Several straight lines are drawn on the obtained photograph to determine the distance between the crack and the intersection of the straight lines, and this is used as the crack interval. At least 50 crack intervals can be obtained, and an average value of the crack intervals can be obtained from these values.
　下部層のクラック間隔の測定方法として、例えば、以下の方法を挙げることができる。クラック間隔を測定する下部層が露出するまで基材の表面に対して平行な方向に鏡面研磨し、フッ硝酸にてエッチングすると、クラックを容易に観察することができる。フッ硝酸を完全に除去した後に、鏡面研磨面を、７５～１５０倍の倍率で光学顕微鏡にて光顕写真を撮影する。得られた光顕写真に数本の直線を引き、クラックとその直線の交点間の距離を求め、それをクラック間隔とする。少なくとも５０箇所のクラック間隔を求め、それらの値からクラック間隔の平均値を求めることができる。 Examples of the method for measuring the crack interval of the lower layer include the following methods. When the mirror polishing is performed in a direction parallel to the surface of the base material until the lower layer for measuring the crack interval is exposed, and etching is performed with hydrofluoric acid, the crack can be easily observed. After completely removing the hydrofluoric acid, a photomicrograph is taken with an optical microscope at a magnification of 75 to 150 times on the mirror-polished surface. Several straight lines are drawn on the obtained photomicrograph to determine the distance between the crack and the intersection of the straight lines, and this is taken as the crack interval. At least 50 crack intervals can be obtained, and an average value of the crack intervals can be obtained from these values.
　下部層の拡散層の厚さは、本発明の被覆切削工具の基材の表面に対して垂直な方向における被覆層の断面を鏡面研磨し、ＳＥＭおよびＦＥ－ＳＥＭなどを用いて、反射電子像を観察することで測定することができる。なお、下部層の拡散層の厚さは、刃先から被覆切削工具のすくい面の中心部に向かって５０μｍの位置の近傍において、下部層の拡散層の厚さを３箇所以上測定し、その平均値を求めるとよい。下部層に拡散した基材の組成は、本発明の被覆切削工具の断面組織からエネルギー分散型Ｘ線分光器（ＥＤＳ）や波長分散型Ｘ線分光器（ＷＤＳ）などを用いて拡散層を分析することで測定することができる。 The thickness of the diffusion layer of the lower layer is determined by mirror-polishing the cross section of the coating layer in the direction perpendicular to the surface of the substrate of the coated cutting tool of the present invention, and using a SEM, FE-SEM, etc. It can measure by observing. The thickness of the diffusion layer of the lower layer is measured by measuring the thickness of the diffusion layer of the lower layer at three or more locations in the vicinity of the position of 50 μm from the cutting edge toward the center of the rake face of the coated cutting tool. Find the value. The composition of the base material diffused into the lower layer is analyzed using the energy dispersive X-ray spectrometer (EDS) or wavelength dispersive X-ray spectrometer (WDS) from the cross-sectional structure of the coated cutting tool of the present invention. It can be measured by doing.
　本発明の被覆切削工具は、耐チッピング性および耐欠損性に優れるので、従来よりも工具寿命を延長できるという効果を奏する。 Since the coated cutting tool of the present invention is excellent in chipping resistance and chipping resistance, it has an effect that the tool life can be extended as compared with the prior art.
　以下、実施例を挙げて本発明を説明するが、本発明はこれらに限定されるものではない。 Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited thereto.
　基材として、ＪＩＳ規格ＣＮＭＧ１２０４０８形状の９１．５ＷＣ－０．５ＴｉＣ－１．８ＴａＣ－０．２ＮｂＣ－６．０Ｃｏ（以上質量％）組成の超硬合金製切削インサートを用意した。この基材の切れ刃稜線部にＳｉＣブラシにより丸ホーニングを施した後、基材の表面を洗浄した。次に基材を外熱式化学蒸着装置に装入し、表１に示す被覆層の構成と平均層厚になるように基材表面に被覆層を形成した。なお、表１の酸化アルミニウム層（Ａｌ２Ｏ３層）の結晶型における（α）はα型Ａｌ２Ｏ３層を表し、（κ）はκ型Ａｌ２Ｏ３層を表す。 As a base material, a cemented carbide cutting insert of 91.5WC-0.5TiC-1.8TaC-0.2NbC-6.0Co (more than mass%) in the shape of JIS standard CNMG120408 was prepared. After round honing was performed on the cutting edge ridge line portion of the base material with a SiC brush, the surface of the base material was washed. Next, the base material was charged into an external heat chemical vapor deposition apparatus, and a coating layer was formed on the surface of the base material so as to have the composition and average layer thickness of the coating layer shown in Table 1. In Table 1, (α) in the crystal type of the aluminum oxide layer (Al 2 O 3 layer) represents an α-type Al 2 O 3 layer, and (κ) represents a κ-type Al 2 O 3 layer.
　発明品１～１９、比較品２～５については、下部層を形成した後に、５０ｈＰａ以下の真空になるまで真空引きした。次に、チャンバ内の温度を２５０℃に下げ、３時間以上保持して冷却した。冷却後、上部層を形成する温度まで昇温した後、上部層を形成した。なお、比較品１、６～９については、下部層を形成した後、従来通りの化学蒸着法で上部層を形成した。 Inventive products 1 to 19 and comparative products 2 to 5 were evacuated until a vacuum of 50 hPa or less was formed after forming the lower layer. Next, the temperature in the chamber was lowered to 250 ° C. and held for 3 hours or more to cool. After cooling, the temperature was raised to a temperature for forming the upper layer, and then the upper layer was formed. For comparative products 1 and 6 to 9, after forming the lower layer, the upper layer was formed by a conventional chemical vapor deposition method.
　発明品１～１７、１９、比較品１～６、８、９については、上部層を形成した後、チャンバ内の温度を１０３０℃に昇温し、窒素ガスの雰囲気でチャンバ内の圧力が２００ｈＰａとなるように制御し、表１の拡散層厚となるように、１～７時間保持した。 Inventive products 1 to 17, 19 and comparative products 1 to 6, 8, and 9, after forming the upper layer, the temperature in the chamber was raised to 1030 ° C., and the pressure in the chamber was 200 hPa in a nitrogen gas atmosphere. And was held for 1 to 7 hours so that the thickness of the diffusion layer shown in Table 1 was obtained.
　発明品１～１９、比較品１、２、４、６～９については、基材の表面に被覆層を形成した後、乾式ショットブラストを施した。乾式ショットブラストの条件は、被覆層の表面に対して投射角度が４５°になるように、投射材を６５ｍ／ｓｅｃの投射速度、０．５～３分の投射時間で投射した。乾式ショットブラストのメディアは、平均粒径１５０μｍのＡｌ２Ｏ３を用いた。 Inventive products 1 to 19 and comparative products 1, 2, 4, and 6 to 9 were subjected to dry shot blasting after forming a coating layer on the surface of the substrate. The dry shot blasting conditions were such that the projection material was projected at a projection speed of 65 m / sec and a projection time of 0.5 to 3 minutes so that the projection angle was 45 ° with respect to the surface of the coating layer. Al 2 O 3 having an average particle size of 150 μm was used as a dry shot blasting medium.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-I000002
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-I000002
　得られた試料の各層の層厚は、被覆切削工具の刃先からすくい面の中心部に向かって５０μｍの位置の近傍の断面を、ＳＥＭで３箇所測定し、その平均値を求めた。拡散層の層厚は、被覆切削工具の刃先から中心部に向かって５０μｍの位置の近傍の断面を、ＳＥＭで反射電子像を観察し、拡散層の厚さを３箇所測定し、平均値を求めた。また、下部層に拡散した基材成分は、拡散層の平均層厚の中心の厚さの位置を、基材と被覆層との界面と平行な方向にＥＤＳを用いて線分析により測定した。 The layer thickness of each layer of the obtained sample was determined by measuring three cross sections near the position of 50 μm from the cutting edge of the coated cutting tool toward the center of the rake face with an SEM, and obtaining the average value. The thickness of the diffusion layer is determined by observing the cross-section near the position of 50 μm from the cutting edge of the coated cutting tool toward the center with a SEM, and measuring the thickness of the diffusion layer at three locations, and calculating the average value. Asked. Moreover, the base material component diffused into the lower layer was measured by line analysis using EDS in the direction parallel to the interface between the base material and the coating layer at the center thickness position of the average thickness of the diffusion layer.
　得られた試料の下部層のクラック間隔の平均値Ｘおよび酸化アルミニウム層のクラック間隔の平均値Ｚは、以下の通りに求めた。まず被覆切削工具の表面を酸化アルミニウム層が露出するまで鏡面研磨し、その鏡面研磨面を４００倍の倍率でＳＥＭにて写真を撮影した。得られた写真に１０本の直線を引き、クラックとその直線の交点間の距離を求め、それをクラック間隔とした。各試料について、５個のインサートを用意し、それぞれ１０箇所のクラック間隔を求め、それらの値から酸化アルミニウム層のクラック間隔の平均値Ｚを求めた。次に下部層が露出するまで鏡面研磨し、その鏡面研磨面をフッ硝酸にてエッチングした。フッ硝酸を完全に除去した後に、鏡面研磨面を７５倍の倍率で光学顕微鏡にて光顕写真を撮影した。得られた光顕写真に数本の直線を引き、クラックとその直線の交点間の距離を求め、それをクラック間隔とした。各試料について、５個のインサートを用意し、それぞれ１０箇所のクラック間隔を求め、それらの値から下部層のクラック間隔の平均値Ｘを求めた。下部層および酸化アルミニウム層のクラック間隔の平均値を表２に示す。 The average value X of the crack interval of the lower layer of the obtained sample and the average value Z of the crack interval of the aluminum oxide layer were determined as follows. First, the surface of the coated cutting tool was mirror-polished until the aluminum oxide layer was exposed, and the mirror-polished surface was photographed with an SEM at a magnification of 400 times. Ten straight lines were drawn on the obtained photograph to determine the distance between the crack and the intersection of the straight lines, and this was taken as the crack interval. For each sample, five inserts were prepared, the crack intervals at 10 locations were determined, and the average value Z of the crack intervals of the aluminum oxide layer was determined from these values. Next, mirror polishing was performed until the lower layer was exposed, and the mirror polishing surface was etched with hydrofluoric acid. After completely removing the fluorinated nitric acid, a photomicrograph was taken with an optical microscope at a magnification of 75 times on the mirror-polished surface. Several lines were drawn on the obtained photomicrograph to determine the distance between the crack and the intersection of the lines, and this was taken as the crack interval. For each sample, 5 inserts were prepared, 10 crack intervals were determined for each sample, and an average value X of crack intervals in the lower layer was determined from these values. Table 2 shows the average value of the crack interval between the lower layer and the aluminum oxide layer.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　得られた試料を用いて、耐欠損性を評価した。ＦＣ２００（硬さ：ＨＢ２４０）を被削材に使用した。被削材の形状は、直径１８０ｍｍ×厚さ６０ｍｍの円盤状の中心に直径６０ｍｍの穴があり、中心から外径側に向かって４本の凸部（凸部の縁と隣の凸部の縁がなす角度は８０°である。）が設けられた形状とした。切削試験では、下記の切削条件で被削材に対して端面切削を行った。 Using the obtained sample, the fracture resistance was evaluated. FC200 (hardness: H B 240) was used as the work material. The shape of the work material is a disc-shaped center with a diameter of 180 mm and a thickness of 60 mm, with a hole with a diameter of 60 mm, and four convex parts from the center to the outer diameter side (the edge of the convex part and the adjacent convex part The angle formed by the edge is 80 °). In the cutting test, end face cutting was performed on the work material under the following cutting conditions.
［切削試験条件］
切削速度：４５０ｍ／ｍｉｎ、
送り：０．３０ｍｍ／ｒｅｖ、
切り込み：２．０ｍｍ、
クーラント：有り、
評価項目：試料が欠損または最大逃げ面摩耗幅が０．３ｍｍに至ったときを工具寿命とし、工具寿命までの加工枚数を測定した。 [Cutting test conditions]
Cutting speed: 450 m / min,
Feed: 0.30mm / rev,
Cutting depth: 2.0 mm
Coolant: Yes,
Evaluation item: When the sample was missing or the maximum flank wear width reached 0.3 mm, the tool life was determined, and the number of workpieces up to the tool life was measured.
　切削試験の工具寿命までの加工枚数および損傷状態を表３に示した。 Table 3 shows the number of workpieces and the state of damage up to the tool life in the cutting test.
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　表３に示されるように、発明品１～１９は、耐欠損性を評価する試験条件において、いずれも欠損が生じていないことから、大幅に耐欠損性が優れることが分かった。また、発明品は比較品よりも工具寿命に至るまでの加工数が多いため、工具寿命が大幅に長いことが分かる。 As shown in Table 3, it was found that the inventive products 1 to 19 were significantly superior in fracture resistance because none of the fractures occurred in the test conditions for evaluating fracture resistance. In addition, it can be seen that the inventive product has a much longer tool life than the comparative product because the number of processing until reaching the tool life is larger.

Claims (7)

  1. 　基材と、該基材の表面に形成された被覆層とを含む被覆切削工具において、
    　前記被覆層は、上部層と下部層とを有し、
    　前記下部層は前記基材の表面に形成され、Ｔｉ、Ｚｒ、Ｈｆ、Ｖ、Ｎｂ、Ｔａ、Ｃｒ、Ｍｏ、ＷおよびＳｉからなる群より選ばれる少なくとも１種の元素と、Ｃ、Ｎ、ＢおよびＯからなる群より選ばれる少なくとも１種の元素とで構成される化合物の１層または２層上から構成され、前記下部層のクラック間隔の平均値Ｘが１０～８０μｍであり、
    　前記上部層は前記下部層の表面に形成され、酸化アルミニウム層を含み、前記酸化アルミニウム層のクラック間隔の平均値Ｚが２０～１００μｍであり、
    　０＜Ｚ－Ｘ＜９０の関係を満たす被覆切削工具。     In a coated cutting tool comprising a substrate and a coating layer formed on the surface of the substrate,
    The covering layer has an upper layer and a lower layer,
    The lower layer is formed on the surface of the substrate, and includes at least one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, and Si, and C, N, B And one or two layers of a compound composed of at least one element selected from the group consisting of O and O, and the average value X of the crack interval of the lower layer is 10 to 80 μm,
    The upper layer is formed on the surface of the lower layer, includes an aluminum oxide layer, and an average value Z of crack intervals of the aluminum oxide layer is 20 to 100 μm,
    Coated cutting tool satisfying the relationship of 0 <ZX <90.
  2. 　前記下部層のクラック間隔の平均値Ｘと前記酸化アルミニウム層のクラック間隔の平均値Ｚとが２０＜Ｚ－Ｘ＜７５の関係を満たす請求項１に記載の被覆切削工具。 The coated cutting tool according to claim 1, wherein an average value X of crack intervals in the lower layer and an average value Z of crack intervals in the aluminum oxide layer satisfy a relationship of 20 <Z-X <75.
  3. 　前記下部層の前記基材側には、前記基材の成分が前記下部層に拡散した拡散層が形成され、前記拡散層の平均層厚Ｔｄと前記下部層の平均層厚Ｔｕは０．１≦Ｔｄ／Ｔｕ≦０．８の関係を満たす請求項１または請求項２に記載の被覆切削工具。 To the substrate side of the lower layer, the diffusion layer component of the base material is diffused into the lower layer is formed, the average layer thickness T u of the lower layer and the average thickness T d of the diffusing layer 0 The coated cutting tool according to claim 1 or 2, wherein a relationship of 0.1 ≦ Td / Tu ≦ 0.8 is satisfied.
  4. 　前記下部層に拡散した前記基材の成分は、Ｗ、Ｃｏ、Ｎｉ、Ｔｉ、Ｔａ、Ｎｂ、Ｍｏ、Ｃｒ、ＶおよびＺｒからなる群より選ばれる少なくとも１種の元素である請求項１～３のいずれか１項に記載の被覆切削工具。 The component of the base material diffused in the lower layer is at least one element selected from the group consisting of W, Co, Ni, Ti, Ta, Nb, Mo, Cr, V and Zr. The coated cutting tool according to any one of the above.
  5. 　前記被覆層全体の層厚が３～３０μｍの平均層厚を有し、
    　前記下部層の層厚が１．５～２０μｍの平均層厚を有し、
    　前記上部層の層厚が１～１５μｍの平均層厚を有する請求項１～４のいずれか１項に記載の被覆切削工具。     The overall coating layer has an average layer thickness of 3 to 30 μm,
    The lower layer has an average layer thickness of 1.5 to 20 μm;
    5. The coated cutting tool according to claim 1, wherein the upper layer has an average layer thickness of 1 to 15 μm.
  6. 　前記上部層は、前記下部層と接する表面に、ＴｉとＡｌからなる元素と、Ｃ、ＮおよびＯからなる群より選ばれる少なくとも１種の元素とで構成される化合物からなる中間層を含む請求項１～５のいずれか１項に記載の被覆切削工具。 The upper layer includes, on a surface in contact with the lower layer, an intermediate layer made of a compound composed of an element composed of Ti and Al and at least one element selected from the group consisting of C, N, and O. Item 6. The coated cutting tool according to any one of Items 1 to 5.
  7. 　前記基材は、超硬合金またはサーメットのいずれかである請求項１～６のいずれか１項に記載の被覆切削工具。 The coated cutting tool according to any one of claims 1 to 6, wherein the substrate is one of cemented carbide or cermet.
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Publication number Priority date Publication date Assignee Title
JP2017013211A (en) * 2015-07-06 2017-01-19 三菱マテリアル株式会社 Surface coating and cutting tool
WO2018123980A1 (en) * 2016-12-26 2018-07-05 京セラ株式会社 Cutting insert
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JP2018183864A (en) * 2017-04-21 2018-11-22 株式会社タンガロイ Coated cutting tool
KR20190063382A (en) * 2017-11-29 2019-06-07 가부시키가이샤 탕가로이 Coated Cutting Tool
KR102191383B1 (en) * 2017-11-29 2020-12-15 가부시키가이샤 탕가로이 Coated Cutting Tool
US10974324B2 (en) 2017-11-29 2021-04-13 Tungaloy Corporation Coated cutting tool

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