Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23B—TURNING; BORING
  • B23B27/00—Tools for turning or boring machines; Tools of a similar kind in general; Accessories therefor
  • B23B27/14—Cutting tools of which the bits or tips or cutting inserts are of special material
  • B23B27/148—Composition of the cutting inserts
• • 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
  • C23C16/02—Pretreatment of the material to be coated
  • C23C16/0272—Deposition of sub-layers, e.g. to promote the adhesion of the main coating
• • 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
  • C23C28/044—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
• • 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
  • C23C30/00—Coating with metallic material characterised only by the composition of the metallic material, i.e. not characterised by the coating process
  • C23C30/005—Coating with metallic material characterised only by the composition of the metallic material, i.e. not characterised by the coating process on hard metal substrates
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23B—TURNING; BORING
  • B23B2228/00—Properties of materials of tools or workpieces, materials of tools or workpieces applied in a specific manner
  • B23B2228/10—Coatings
  • B23B2228/105—Coatings with specified thickness

Definitions

• This disclosure relates to cutting tools.
• Cutting tools have been used for cutting work, the cutting tools including a substrate and a coating disposed on the substrate, the coating including a first layer made of ⁇ -Al 2 O 3 (Patent Document 1, Non-Patent Document 1).
• the cutting tool of the present disclosure comprises: 1.
• a cutting tool comprising a substrate and a coating disposed on the substrate,
• the coating comprises a first layer;
• the first layer is made of ⁇ -Al 2 O 3 ;
• the thickness of the first layer is 2 ⁇ m or more and 15 ⁇ m or less;
• N2/N1 of the number N2 of second grain boundaries that are grain boundaries having an absolute value of an angle of 15° or less with respect to a line perpendicular to the virtual line L1 at the position where the first grain boundary intersects with the virtual line L1 to the number N1 of first grain boundaries crossed by the virtual line L1 that is equidistant from the interface of the first layer on the surface side of the coating and
• FIG. 1 is a schematic cross-sectional view illustrating one embodiment of a cutting tool according to the present disclosure.
• Figure 2 is a schematic cross-sectional view of an example of a CVD (Chemical Vapor Deposition) apparatus used in manufacturing the cutting tool of the present disclosure.
• FIG. 3 is an enlarged view of region III in FIGS.
• FIG. 4 is an enlarged view of region IV in FIGS.
• FIG. 5 is a schematic cross-sectional view illustrating another embodiment of the cutting tool of the present disclosure.
• the object of this disclosure is to provide a cutting tool with excellent tool life.
• the cutting tool of the present disclosure is 1.
• a cutting tool comprising a substrate and a coating disposed on the substrate, the coating comprises a first layer;
• the first layer is made of ⁇ -Al 2 O 3 ;
• the thickness of the first layer is 2 ⁇ m or more and 15 ⁇ m or less;
• N1 of first grain boundaries intersected by a virtual line L1 that is equidistant from the interface of the first layer on the surface side of the first layer or the surface side of the coating of the first layer and the interface of the first layer on the substrate side is a ratio N2/N1 of the number N2 of second grain boundaries that are grain boundaries having an absolute value of an angle of 15° or less with respect to a line perpendicular to the virtual line L1 at a position where the first grain boundary intersects with the virtual line L1 to the number N1 of first grain boundaries
• the ratio N4/N3 of the number N4 of fourth grain boundaries, which are grain boundaries that form angles with a line perpendicular to the virtual line L2 at positions where the third grain boundaries intersect with the virtual line L2, is 15° or less, and the ratio N2/N1 satisfies the relationship of the following formula 1: 0.1 ⁇ (N2/N1)-(N4/N3) ⁇ 0.40 Formula 1
• This disclosure makes it possible to provide cutting tools with excellent tool life.
• the number N3 and the number N5 of fifth grain boundaries which are grain boundaries among the third grain boundaries and which have an absolute value of an angle with respect to a line perpendicular to the virtual line L2 of 45° or less at a position where the third grain boundary intersects with the virtual line L2, may satisfy the relationship of the following formula 2: (N5/N3)>0.96 Formula 2 This can provide a cutting tool with a longer tool life.
• the thickness of the first layer is less than 8 ⁇ m
• the surface of the first layer or the surface of the first layer located at the interface with the coating on the surface side may have a surface roughness Ra of 0.03 ⁇ m or more and 0.2 ⁇ m or less, thereby making it possible to provide a cutting tool having a longer tool life.
• the thickness of the first layer is 8 ⁇ m or more
• the surface of the first layer or the surface of the first layer located at the interface with the coating on the surface side may have a surface roughness Ra of 0.05 ⁇ m or more and 0.2 ⁇ m or less, thereby making it possible to provide a cutting tool having a longer tool life.
• the absolute value of the compressive residual stress of the first layer may be 1.5 GPa or more and 4.0 GPa or less. This makes it possible to provide a cutting tool with a longer tool life.
• the orientation index TC(0 0 12) of the first layer may be greater than 4.5. This makes it possible to provide a cutting tool with a longer tool life.
• notations in the format "A-B" refer to the upper and lower limits of a range (i.e., greater than or equal to A and less than or equal to B). If no unit is specified for A and only a unit is specified for B, the units for A and B are the same.
• FIG. 1 is a schematic cross-sectional view illustrating one embodiment of the cutting tool according to the present disclosure.
• Fig. 3 is an enlarged view of region III in Fig. 1 and Fig. 5.
• Fig. 4 is an enlarged view of region IV in Fig. 1 and Fig. 5.
• Fig. 5 is a schematic cross-sectional view illustrating another embodiment of the cutting tool according to the present disclosure.
• a cutting tool 10 comprising a substrate 1 and a coating 2 disposed on the substrate 1,
• the coating 2 comprises a first layer 3,
• the first layer 3 is made of ⁇ -Al 2 O 3 ,
• the thickness of the first layer 3 is 2 ⁇ m or more and 15 ⁇ m or less,
• the ratio N2/N1 of the number N2 of second grain boundaries which are grain boundaries whose absolute value of the angle with a line perpendicular to the imaginary line L1 at the position where the first grain boundary intersects with the imaginary line L1 is 15° or less, to the number N1 of first grain boundaries crossed by an imaginary line L1 that is equidistant from the surface S1 of the first layer 3 or the interface of the first layer 3 on the surface side of the coating 2 and the interface I1 of the first layer 3 on the substrate 1 side, is 0.60 or more; In the cross section taken along the normal to the
• the present disclosure makes it possible to provide a cutting tool 10 with excellent tool life.
• a cutting tool 10 includes a substrate 1 and a coating 2 disposed on the substrate 1.
• the coating 2 preferably covers the entire surface of the substrate 1, but it does not depart from the scope of this embodiment even if a portion of the substrate 1 is not coated with the coating 2 or if the coating 2 has a partially different configuration.
• the coating 2 is preferably disposed so as to cover at least the surface of the portion of the substrate 1 involved in cutting.
• the portion of the substrate 1 involved in cutting refers to the region of the substrate 1 surrounded by the cutting edge ridge and an imaginary surface that is, depending on the size and shape of the substrate 1, a distance from the cutting edge ridge toward the substrate 1 along a perpendicular to the tangent to the cutting edge ridge, for example, 5 mm, 3 mm, 2 mm, 1 mm, or 0.5 mm.
• the cutting tool 10 of this embodiment can be suitably used as a cutting tool 10 for drills, end mills, indexable cutting tips for drills, indexable cutting tips for end mills, indexable cutting tips for milling, indexable cutting tips for turning, metal saws, gear cutting tools, reamers, taps, and the like.
• any conventionally known substrate 1 of this type can be used as the substrate 1.
• cemented carbide WC-based cemented carbide, cemented carbide containing WC and Co, cemented carbide containing carbonitrides of Ti, Ta, Nb, etc.
• cermet mainly composed of TiC, TiN, TiCN, etc.
• high-speed steel ceramics (titanium carbide, silicon carbide, silicon nitride, aluminum nitride, aluminum oxide, etc.), cubic boron nitride sintered body, or diamond sintered body is preferred.
• WC-based cemented carbide and cermet particularly TiCN-based cermet.
• These substrates 1 have an excellent balance of hardness and strength, especially at high temperatures, and when used as the substrate 1 of a cutting tool 10, they can contribute to extending the life of the cutting tool 10.
• the coating 2 includes a first layer 3.
• the coating 2 may consist solely of the first layer 3, or may include layers other than the first layer 3 ("other layers" described below) as long as the effects of the present disclosure are not impaired.
• the thickness of the coating 2 may be 7 ⁇ m or more and 25 ⁇ m or less, or 10 ⁇ m or more and 15 ⁇ m or less. If the thickness of the coating 2 is less than 7 ⁇ m, the coating 2 is too thin, which tends to shorten the life of the cutting tool 10. On the other hand, if the thickness of the coating 2 exceeds 25 ⁇ m, chipping of the coating 2 is likely to occur in the early stages of cutting, which tends to shorten the life of the cutting tool 10.
• the thickness of the coating 2 can be measured by observing a cross section of the coating 2 along the normal direction to the surface of the coating 2 using a scanning electron microscope (SEM). Specifically, the cross section sample is observed at a magnification of 5,000 to 10,000 times, and the observation area is 100 to 500 ⁇ m2 . The thickness width is measured at any three points in any one field of view, and the average value is taken as the "thickness.” The same applies to the thickness of each layer described below unless otherwise specified.
• SEM scanning electron microscope
• the first layer 3 is made of ⁇ -Al 2 O 3.
• “Made of ⁇ -Al 2 O 3” means that the first layer 3 may be made of only ⁇ -Al 2 O 3 , or may contain inevitable impurities in addition to ⁇ -Al 2 O 3 , as long as the effects of the present disclosure are not impaired.
• the inevitable impurities include chlorine atoms (Cl) and sulfur atoms (S).
• the total content of the inevitable impurities in the first layer 3 may be, for example, 0% by mass or more and 0.10% by mass or less, or 0.01% by mass or more and 0.05% by mass or less.
• the first layer 3 is made of ⁇ -Al 2 O 3 is identified by X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDX).
• XRD X-ray diffraction
• EDX energy dispersive X-ray analysis
• SIMS secondary ion mass spectrometry
• the thickness of the first layer 3 is 2 ⁇ m or more and 15 ⁇ m or less.
• the thickness of the first layer 3 may be 3 ⁇ m or more and 14 ⁇ m or less, 4 ⁇ m or more and 13 ⁇ m or less, or 5 ⁇ m or more and 12 ⁇ m or less.
• the thickness of the first layer 3 is less than 8 ⁇ m, and the surface S1 of the first layer 3 or the surface of the first layer 3 located at the interface with the coating 2 on the surface side may have a surface roughness Ra of 0.03 ⁇ m or more and 0.2 ⁇ m or less. This makes it easier to impart uniform compressive residual stress to the cutting tool 10 by the blasting treatment, thereby imparting better chipping resistance and thereby providing the cutting tool 10 with a longer tool life.
• the surface roughness Ra may be 0.03 ⁇ m or more and 0.15 ⁇ m or less, or 0.03 ⁇ m or more and 0.1 ⁇ m or less.
• the thickness of the first layer 3 is 8 ⁇ m or more, and the surface roughness Ra of the surface S1 of the first layer 3 or the surface of the first layer 3 located at the interface on the surface side of the coating 2 may be 0.05 ⁇ m or more and 0.2 ⁇ m or less. This makes it easier to impart uniform compressive residual stress to the cutting tool 10 by blasting, thereby imparting better chipping resistance and therefore better tool life to the cutting tool 10.
• the surface roughness Ra may be 0.05 ⁇ m or more and 0.18 ⁇ m or less, or 0.06 ⁇ m or more and 0.15 ⁇ m or less.
• Surface roughness Ra is measured in accordance with JIS B0601:2001 on a cross section of the cutting edge R along the normal direction to the interface between the substrate 1 and coating 2. More specifically, first, an image is obtained of the cross section of the cutting edge R along the normal direction to the interface between the substrate 1 and coating 2 using an SEM at 1000x magnification, including the surface S1 of the first layer 3 or the surface located at the interface on the surface side of the coating 2 of the first layer 3. Next, an arbitrary rectangular observation field of 10 ⁇ m x 10 ⁇ m is identified in the image at 10,000x magnification.
• the surface S1 of the first layer 3 or the surface located at the interface on the surface side of the coating 2 of the first layer 3 is assumed to pass through any pair of opposing sides.
• image analysis software (ImageJ, version 1.51j8: https://imagej.nih.gov/ij/) is used to extract interface contour information for the observation field, thereby determining the arithmetic mean roughness of the surface S1 of the first layer 3 or the surface located at the interface on the surface side of the coating 2 of the first layer 3 in the observation field.
• the arithmetic mean roughness of the surface S1 of the first layer 3 or the surface located at the interface on the surface side of the coating 2 of the first layer 3 is determined for any other four observation fields in the image.
• the surface roughness Ra is determined by calculating the average value of the arithmetic mean roughness of the surface S1 of the first layer 3 or the surface located at the interface on the surface side of the coating 2 of the first layer 3 in a total of five observation fields. It has been confirmed that there is no variation in measurement results even if the measurement location is arbitrarily selected, as long as the same first layer 3 is measured.
• the ratio N2/N1 may be 0.60 or more and 1.0 or less, 0.7 or more and 1.0 or less, or 0.8 or more and 1.0 or less.
• D1 and D2 the distance between the surface S1 of the first layer 3 or the interface of the first layer 3 on the surface side of the coating 2 and the virtual line L1
• D2 the distance between the virtual line L1 and the interface I1 of the first layer 3 on the substrate 1 side
• D1 and D2 The distance from the surface S1 of the first layer 3 or the interface of the first layer 3 on the surface side of the coating 2 and the interface I1 of the first layer 3 on the substrate 1 side are equal.
• a grain boundary where the absolute value of the angle with a line perpendicular to virtual line L1 at the intersection of the first grain boundary and virtual line L1 is 15° or less is a concept that encompasses both a grain boundary GB ( Figure 3) that slopes downward to the right with respect to the line ( Figure 4) at the "intersection position.”
• a grain boundary where the absolute value of the angle with a line perpendicular to virtual line L1 at the intersection of the first grain boundary and virtual line L1 is 15° or less refers to a grain boundary where angle ⁇ in Figure 3 is 15° or less and a grain boundary where angle ⁇ in Figure 4 is 15° or less.
• the number N3 of third grain boundaries intersected by an imaginary line L2 that is 0.5 ⁇ m away from the surface S1 of the first layer 3 or the interface of the first layer 3 on the surface side of the coating 2 toward the substrate 1 may be such that the number N4 of fourth grain boundaries, which are grain boundaries whose absolute value of an angle with a line perpendicular to the imaginary line L2 at the intersection of the third grain boundaries and the imaginary line L2 is 15° or less, may be a ratio N4/N3 of 0.4 to 0.9. This allows the cutting tool 10 to have a longer tool life.
• the ratio N4/N3 may be 0.45 to 0.80, 0.50 to 0.75, or 0.55 to 0.70.
• a grain boundary at the position where the third grain boundary and the virtual line L2 intersect, the absolute value of the angle with respect to the line perpendicular to the virtual line L2 is 15° or less is a concept that encompasses both a grain boundary that slopes downward to the right with respect to the line at the "intersection position" and a grain boundary that slopes upward to the right with respect to the line.
• the ratio N2/N1 and the ratio N4/N3 can be determined by the following method.
• A1 A color map is created based on the crystal orientation of each crystal grain by performing electron backscatter diffraction image analysis using a field emission scanning microscope on a cross section of the first layer 3 along the normal direction of the interface between the coating 2 and the substrate 1.
• B1 Based on the color map created in (A1), the areas where ⁇ -Al 2 O 3 is present are colored white and the other areas are colored black to obtain a first image.
• a moving average filter with a size of 15 ⁇ 15 pixels is applied to the interface I1 on the substrate 1 side of the first layer 3 and the surface S1 of the first layer 3 or the interface on the surface side of the coating 2 of the first layer 3 to smooth the first image, followed by Otsu's binarization.
• each column of pixels in the first image after Otsu's binarization is observed in order from the substrate 1 side, and the area where the color changes from black to white is identified as the interface I1 on the substrate 1 side of the first layer 3.
• the interface is fitted with a linear equation to obtain a line L3.
• each column of pixels in the first image that has been binarized by Otsu's method is observed in order from the surface side of the coating 2, and the point where the color changes from black to white is identified as the surface S1 of the first layer 3 or the interface on the surface side of the coating 2 of the first layer 3.
• a line L4 is obtained that is parallel to the line L3 and has the smallest sum of squares of the error at the "surface S1 of the first layer 3 or the interface on the surface side of the coating 2 of the first layer 3.”
• a line that is equidistant from the line L3 and the line L4 is obtained as a virtual line L1.
• a line that is 0.5 ⁇ m away from the line L4 toward the substrate 1 is obtained as a virtual line L2.
• C1 Based on the color map created in (A1), the grain boundaries are colored black and the other areas are colored white, and an image is output to obtain a second image.
• D1 By superimposing the second image and the first image, the locations in the second image corresponding to the virtual line L1 obtained in (B1) and the locations corresponding to the virtual line L2 obtained in (B1) are identified.
• the coordinates of the grain boundary are calculated by image processing for any one rectangular field of view (field of view size: 40 ⁇ m ⁇ 25 ⁇ m) using as a reference a straight line parallel to the interface I1 on the substrate 1 side of the first layer 3. Based on the coordinates, the inclination of the grain boundary (in other words, the angle of the grain boundary) is determined.
• N3 of third grain boundaries crossed by the virtual line L2 and the number N4 of fourth grain boundaries which are grain boundaries that have an absolute value of an angle with respect to a line perpendicular to the virtual line L2 of 15° or less at the position where the third grain boundary and the virtual line L2 intersect, are identified.
• N4 is divided by N3 to determine the ratio N4/N3.
• ratio N2/N1 and ratio N4/N3 satisfy the relationship of the following formula 1.
• 0.1 ⁇ (N2/N1)-(N4/N3) ⁇ 0.40 Formula 1 This can impart excellent chipping resistance to the cutting tool 10.
• "(N2/N1)-(N4/N3)" may be 0.1 or more and 0.35 or less, 0.1 or more and 0.30 or less, or 0.1 or more and 0.20 or less.
• the number N3 and the number N5 of fifth grain boundaries which are grain boundaries among the third grain boundaries and which have an absolute value of an angle with respect to a line perpendicular to the virtual line L2 of 45° or less at a position where the third grain boundary intersects with the virtual line L2, may satisfy the relationship of the following formula 2.
• N5/N3 (N5/N3)>0.96 Formula 2 This makes it possible to reduce the number of third grain boundaries in the surface region of the first layer coating where the absolute value of the angle between the third grain boundary and virtual line L2 and a line perpendicular to virtual line L2 exceeds 45° (i.e., grain boundaries with a large absolute value of the angle), thereby suppressing the occurrence of coating breakdown and coating peeling when subjected to strong blasting, thereby providing a longer tool life to the cutting tool 10.
• "N5/N3" may be greater than 0.96 and less than or equal to 1.00, may be 0.97 or greater and 1.00 or less, or may be 0.98 or greater and 1.00 or less.
• N5/N3 can be determined using the following method. It can be determined in the same way as N4/N3, except that it determines the number N5 of fifth grain boundaries, which are grain boundaries whose absolute angle with respect to a line perpendicular to virtual line L2 is 45° or less, and that it finds the ratio N5/N3 by dividing N5 by N3. It has been confirmed that, as long as measurements are taken on the same first layer 3, there is no variation in the measurement results even if the measurement location is arbitrarily selected.
• All of the third grain boundaries may have an angle of less than 45° relative to a line perpendicular to imaginary line L2 at the position where the third grain boundary intersects with imaginary line L2. This allows for a longer tool life to be imparted to the cutting tool 10.
• the third grain boundaries may not include grain boundaries having an angle of 45° or more relative to a line perpendicular to imaginary line L2 at the position where the third grain boundary intersects with imaginary line L2. This allows for a longer tool life to be imparted to the cutting tool 10.
• the absolute value of the compressive residual stress of the first layer 3 may be 1.5 GPa or more and 4.0 GPa or less. This can provide the cutting tool 10 with a longer tool life.
• the compressive residual stress of the first layer 3 is a type of internal stress (intrinsic strain) present throughout the first layer 3 and is expressed as a negative (-) value (unit: GPa is used in this embodiment). Therefore, a high compressive residual stress refers to a large absolute value of the value, and a low compressive residual stress refers to a small absolute value of the value.
• an absolute value of the compressive residual stress of 1.5 GPa or more and 4.0 GPa or less means that the compressive residual stress related to the first layer 3 is -4.0 GPa or more and -1.5 GPa or less.
• the absolute value of the compressive residual stress of the first layer 3 may be 1.8 GPa or more and 3.5 GPa or less, or 2.0 GPa or more and 3.0 GPa or less.
• the compressive residual stress of the first layer 3 can be measured using an X-ray residual stress device by the sin2 ⁇ method (see pages 54-66 of "X-ray Stress Measurement Methods" (Japan Society for Materials Science, published by Yokendo Co., Ltd. in 1981)).
• the orientation index TC(0 0 12) of the first layer 3 may be greater than 4.5. This further improves the strength of the ⁇ -Al 2 O 3 crystal grains, thereby further improving the wear resistance and providing the cutting tool 10 with a longer tool life.
• the orientation index TC(0 0 12) of the first layer 3 may be greater than 4.5 and equal to or less than 8.0, equal to or greater than 5.0 and equal to or less than 7.9, or equal to or greater than 6.0 and equal to or less than 7.9.
• the orientation index TC(0 0 12) of the first layer 3 refers to the orientation index TC(0 0 12) of the (0 0 12) plane in the first layer 3, among the orientation indexes TC(hkl) defined by the following formula 3.
• Equation 3 I(hkl) represents the X-ray diffraction intensity of the (hkl) reflection plane, and I 0 (hkl) represents the standard intensity according to ICDD PDF card number 00-010-0173. Furthermore, n in Equation 3 represents the number of reflections used in the calculation, which is 8 in this embodiment.
• the (hkl) planes used for reflection are (012), (104), (110), (0 0 12), (113), (214), (116), and (300).
• ICDD registered trademark
• PDF registered trademark
• orientation index TC (0 0 12) of the first layer 3 in this embodiment can be expressed by the following equation 4.
• the orientation index TC(0 0 12) of the first layer 3 is greater than 4.5
• the value obtained by substituting TC(0 0 12) into formula 3 above to obtain formula 4 is greater than 4.5.
• TC(hkl) The above-described measurement of TC(hkl) is possible by analysis using an X-ray diffraction apparatus.
• TC(hkl) can be measured, for example, using Rigaku Corporation's SmartLab (registered trademark) (scan speed: 21.7°/min, step: 0.01°, scan range: 15 to 140°) under the following conditions.
• XRD results the measurement results of TC(hkl) using an X-ray diffraction apparatus are referred to as "XRD results.”
• Characteristic X-ray Cu-K ⁇ Tube voltage: 45 kV Tube current: 200mA
• Filter Multilayer mirror
• Optical system Focusing method
• X-ray diffraction method ⁇ -2 ⁇ method
• X-rays are irradiated onto the rake face of a cutting tool. Since the rake face is usually uneven, while the flank face is flat, it is preferable to irradiate the flank face with X-rays to eliminate disturbance factors.
• the value of the orientation index TC(hkl) of the first layer 3 on the flank face of the substrate is the same as the value of TC(hkl) of the first layer 3 on the rake face of the substrate.
• the base layer is a layer in contact with the substrate 1.
• the surface layer is a layer located on the surface of the coating 2.
• the intermediate layer is a layer disposed between the base layer and the first layer 3 or a layer disposed between the first layer 3 and the surface layer.
• the underlayer may be made of TiN or TiCN.
• “Made of TiN or TiCN” means that the underlayer may be made of only TiN or TiCN, or may contain inevitable impurities in addition to TiN or TiCN. Examples of inevitable impurities include chlorine atoms (Cl), oxygen atoms (O), cobalt atoms (Co), tungsten atoms (W), nickel atoms (Ni), and boron atoms (B).
• the total content of inevitable impurities in the underlayer may be, for example, 0% by mass or more and 1.0% by mass or less, or 0.3% by mass or more and 0.6% by mass or less.
• the underlayer is composed of TiN or TiCN is determined using X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDX).
• XRD X-ray diffraction
• EDX energy dispersive X-ray analysis
• SIMS secondary ion mass spectrometry
• the thickness of the underlayer may be 0.1 ⁇ m or more and 2.0 ⁇ m or less, 0.5 ⁇ m or more and 1.5 ⁇ m or less, or 0.8 ⁇ m or more and 1.3 ⁇ m or less.
• the intermediate layer may be made of TiCN.
• “Made of TiCN” means that the intermediate layer may be made of only TiCN, or may contain inevitable impurities in addition to TiCN. Examples of inevitable impurities include chlorine atoms (Cl), oxygen atoms (O), cobalt atoms (Co), tungsten atoms (W), nickel atoms (Ni), and boron atoms (B).
• the total content of inevitable impurities in the intermediate layer may be, for example, 0% by mass or more and 1.0% by mass or less, or 0.3% by mass or more and 0.6% by mass or less.
• the intermediate layer is made of TiCN is determined using X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDX).
• XRD X-ray diffraction
• EDX energy dispersive X-ray analysis
• SIMS secondary ion mass spectrometry
• the thickness of the intermediate layer may be 2.0 ⁇ m or more and 10 ⁇ m or less, or 4.0 ⁇ m or more and 8.0 ⁇ m or less.
• the surface layer may be made of TiN.
• “Made of TiN” means that the surface layer may consist of only TiN, or may contain inevitable impurities in addition to TiN. Examples of inevitable impurities include chlorine atoms (Cl), oxygen atoms (O), cobalt atoms (Co), tungsten atoms (W), nickel atoms (Ni), and boron atoms (B).
• the total content of inevitable impurities in the surface layer may be, for example, 0% by mass or more and 1.0% by mass or less, or 0.1% by mass or more and 0.4% by mass or less.
• the surface layer is made of TiN is measured using X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDX).
• XRD X-ray diffraction
• EDX energy dispersive X-ray analysis
• SIMS secondary ion mass spectrometry
• the thickness of the surface layer may be 0.5 ⁇ m or more and 3.0 ⁇ m or less, or 1.0 ⁇ m or more and 2.5 ⁇ m or less.
• Fig. 2 is a schematic cross-sectional view of an example of a CVD apparatus used in manufacturing the cutting tool according to the present disclosure.
• the cutting tool manufacturing method of this embodiment is the same as the cutting tool manufacturing method of embodiment 1, and includes a first step of preparing a substrate 1 and a second step of forming a coating on the substrate 1, the second step including step 2a of forming a first layer by a CVD method. Details of each step are described below.
• a substrate 1 is prepared.
• the substrate 1 described in the first embodiment can be used.
• a commercially available substrate 1 may be used, or it may be manufactured using a general powder metallurgy method.
• a general powder metallurgy method for example, WC powder and Co powder are mixed using a ball mill or the like to obtain a mixed powder.
• the mixed powder is then dried and molded into a desired shape to obtain a green body.
• the green body is then sintered to obtain a WC-Co-based cemented carbide (sintered body).
• the sintered body is subjected to a desired cutting edge processing such as honing, thereby producing a substrate 1 made of a WC-Co-based cemented carbide.
• Substrates 1 other than those described above can also be prepared as long as they are conventionally known as this type of substrate 1.
• a coating is formed on the substrate 1 to obtain a cutting tool.
• the coating is formed using, for example, a CVD apparatus 50 shown in FIG. 2 .
• the CVD apparatus 50 includes a plurality of substrate setting jigs 52 for holding the substrate 1 and a heat-resistant alloy steel reactor 53 that covers the substrate setting jigs 52.
• a temperature control device 54 for controlling the temperature inside the reactor 53 is provided around the reactor 53.
• the reactor 53 is provided with a gas inlet pipe having a gas inlet.
• the gas inlet pipe extends vertically in the internal space of the reactor 53 in which the substrate setting jigs 52 are placed, and is rotatable about the vertical axis.
• the gas inlet pipe is also provided with a plurality of ejection holes (through holes) for ejecting gas into the reactor 53.
• the first layer that constitutes the coating can be formed as follows.
• the second step includes step 2a, in which the first layer is formed by a CVD method. If the coating includes the "other layer” described in embodiment 1, the second step can further include a step of forming the "other layer.”
• the "other layer” can be formed by a conventionally known method.
• Step 2a Step of forming first layer by CVD method>
• the first layer is formed by a CVD method. More specifically, the substrate 1 is first placed in a substrate setting jig 52, and a source gas for the first layer is introduced into the reaction vessel 53 from a gas inlet pipe while controlling the temperature and pressure in the reaction vessel 53 within predetermined ranges. In this way, the first layer is formed on the substrate 1.
• the CVD device 50 is equipped with a nozzle 56 having two inlets 55, 57.
• the nozzle 56 is positioned so that it penetrates the area in which the substrate setting jig 52 is placed.
• the nozzle 56 has multiple injection holes (a first injection hole 61, a second injection hole 62, a third injection hole (not shown), and a fourth injection hole (not shown)) formed in the portion of the nozzle 56 near the substrate setting jig 52.
• the gases introduced into the nozzle 56 from the inlets 55 and 57 are not mixed inside the nozzle 56 either, but are introduced into the reaction vessel 53 via different injection holes.
• the nozzle 56 can rotate around its own axis.
• An exhaust pipe 59 is also provided in the CVD apparatus 50, and the exhaust gas can be discharged to the outside through the exhaust port 60 of the exhaust pipe 59.
• the fixtures and other equipment inside the reaction vessel 53 are typically made of graphite.
• a mixed gas of AlCl 3 , HCl, CO 2 , H 2 S, and H 2 is used as the source gas.
• film formation is performed under the following conditions (condition 1) of the mixed gas composition, mixed gas flow rate (i.e., total gas flow rate), mixed gas temperature, and mixed gas pressure.
• Condition 1 AlCl 3 : 2.0 vol % to 4.0 vol % HCl: 2.0 vol % to 4.0 vol % CO 2 : 3.0 vol % to 5.0 vol % H 2 S: 0.20 vol % to 0.60 vol % H 2 : remaining temperature: 950° C. to 1020° C. pressure: 5 kPa to 100 kPa
• the conditions of the mixed gas composition, mixed gas temperature, and mixed gas pressure are set as shown in “Condition 2A” below, and in the third injection hole and the fourth injection hole, the conditions of the mixed gas composition, mixed gas temperature, and mixed gas pressure are set as shown in “Condition 2B” below, and film formation is performed.
• the diameter ⁇ of the injection hole can be, for example, 1.5 mm/2.5 mm. Note that, here, "the diameter ⁇ of the injection hole is 1.5 mm/2.5 mm" can be rephrased as meaning that the minor axis of the injection hole is 1.5 mm and the major axis of the injection hole is 2.5 mm, with respect to the injection hole located in a cross section perpendicular to the longitudinal direction of the nozzle 56.
• the rotation speed of the nozzle 56 can be set to 1.0 rpm or more and 8.0 rpm or less.
• the deposition time for the first layer can be adjusted as needed. By adjusting the deposition time for the first layer as needed, the thickness of the first layer can be controlled.
• the second step may include a surface treatment step such as surface grinding or blasting.
• step 2a film formation is performed under the above-mentioned "Condition 1,” and then film formation is performed under a combination of the above-mentioned “Condition 2A” and “Condition 2B.”
• This allows the crystal growth direction to be freely controlled by combining conditions for different crystal growth directions, so that, in a cross section along the normal to the interface between the substrate 1 and the coating, the number N1 of first grain boundaries crossed by a virtual line L1 that is equidistant from the interface of the first layer on the surface of the first layer or the surface side of the coating of the first layer and the interface of the first layer on the substrate 1 side is occupied by the number N2 of second grain boundaries that are grain boundaries whose absolute value of the angle with a line perpendicular to the virtual line L1 is 15° or less at the position where the first grain boundary intersects with the virtual line L1.
• the ratio N2/N1 is 0.60 or more, and the ratio N4/N3, which is the number N4 of fourth grain boundaries that are grain boundaries having an absolute value of an angle with a line perpendicular to virtual line L2 of 15° or less at the position where the third grain boundary intersects with virtual line L2, to the number N3 of third grain boundaries crossed by virtual line L2 that is 0.5 ⁇ m away from the surface of the first layer or the interface on the surface side of the coating of the first layer toward the substrate 1 in the cross section along the normal to the interface between the substrate 1 and the coating, and the ratio N2/N1 can satisfy the relationship of the following formula 1. 0.1 ⁇ (N2/N1)-(N4/N3) ⁇ 0.40 Formula 1
• the inventors have found, as a result of extensive research, that the cutting tool of the present disclosure can be realized by employing such a manufacturing method.
• all of the third grain boundaries may form angles of less than 45° with respect to a line perpendicular to the imaginary line L2 at positions where the third grain boundaries intersect with the imaginary line L2.
• the third grain boundary does not have to include a grain boundary that forms an angle of 45° or more with respect to a line perpendicular to the imaginary line L2 at the position where the third grain boundary intersects with the imaginary line L2.
• a turning tip (shape: CNMG120408N-GZ, manufactured by Sumitomo Electric Hardmetal Corp.) having the composition shown in Tables 11 and 12 was prepared.
• a first layer was formed on the surface of the intermediate layer by performing a CVD method (step 2a).
• a CVD method was performed under the conditions listed in Tables 3 and 4 (Step I).
• a CVD method was performed using the first and second injection holes under the conditions listed in Tables 5 and 6, and using the third and fourth injection holes under the conditions listed in Tables 7 and 8 to form the first layer (Step II).
• a "-" in all columns in Tables 5 to 8 indicates that the first layer was formed by performing only Step I.
• a "-" in none of Tables 5 and 6, but a "-" in all columns in Tables 7 and 8, indicates that the first and second injection holes were used in Step II, while the third and fourth injection holes were not.
• the total time for Steps I and II was adjusted so that the thickness of the first layer was as listed in Tables 13 and 14. Furthermore, when both Step I and Step II were performed, the ratio of the time spent on Step I to the time spent on Step II was set to 10:1.
• a surface layer was formed on the surface of the first layer by performing a CVD method under the conditions listed in Tables 9 and 10.
• the deposition time was adjusted so that the thickness of the surface layer would be as listed in Tables 15 and 16. If a "-" appears in all of the "Surface layer deposition conditions" columns in Tables 9 and 10, this means that no surface layer was formed.
• composition of the base layer of each sample cutting tool was determined by the method described in embodiment 1. The results obtained are shown in the "Composition” column of the "Base Layer” column in Tables 11 and 12. Note that when the names of components are listed in the "Composition” column of the “Base Layer” column in Tables 11 and 12, this means that the base layer is composed of the components listed in the “Composition” column of the “Base Layer” column in Tables 11 and 12.
• composition of the intermediate layer of each sample cutting tool was determined by the method described in embodiment 1. The results obtained are shown in the "Composition” column of the "Intermediate Layer” column in Tables 11 and 12.
• the name of a component is listed in the "Composition” column of the “Intermediate Layer” column in Tables 11 and 12, it means that the intermediate layer is composed of the component listed in the "Composition” column of the “Intermediate Layer” column in Tables 11 and 12.
• composition of the first layer of each sample cutting tool was determined by the method described in embodiment 1. The results obtained are shown in the "Composition” column of the "First Layer” column in Tables 13 and 14. Note that when component names are listed in the "Composition” column of the “First Layer” column in Tables 13 and 14, this means that the first layer is composed of the components listed in the "Composition” column of the “First Layer” column in Tables 13 and 14.
• composition of the surface layer of each sample cutting tool was determined by the method described in embodiment 1. The results obtained are shown in the "Composition” column of the "Surface Layer” column in Tables 15 and 16. When the "Composition” column of the “Surface Layer” column in Tables 15 and 16 lists the names of components, this means that the surface layer is composed of the components listed in the "Composition” column of the “Surface Layer” column in Tables 15 and 16.
• the cutting time in Cutting Test 1 is 210 seconds or more and the cutting distance in Cutting Test 2 is 2.5 km or more, it means that the cutting tool has excellent tool life.
• Cutting tools according to samples 1 to 20 correspond to examples.
• Cutting tools according to samples 101 to 112 correspond to comparative examples.
• the results of Cutting Test 1 and Cutting Test 2 in Table 18 show that cutting tools according to samples 1 to 20 have superior tool life compared to cutting tools according to samples 101 to 112.
• Substrate 1. Coating, 3. First layer, 4. Base layer, 10.
• Cutting tool 50.
• CVD apparatus 52.
• Substrate setting jig 53.
• Reaction vessel 54.
• Temperature control device 55, 57.
• Inlet 56.
• Nozzle 59.
• Exhaust pipe 60.
• Exhaust port 61.
• First injection hole 62. Second injection hole.

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