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
• • 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

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;
• the first layer includes a plurality of grain boundaries connecting an interface of the first layer close to the substrate and an interface of the first layer close to the surface of the first layer or a surface of the coating, and at least one of the grain boundaries, a first grain boundary, has a plurality of straight line segments and three or more bending points connecting two adjacent straight line segments;
• a crossing angle A1 at the bending point closest to the interface close to the substrate of the first layer and a crossing angle A2 next closest to the bending point are each 90° or more and 150° or less
• FIG. 1 is a schematic cross-sectional view illustrating one embodiment of a cutting tool according to the present disclosure.
• FIG. 2 is an enlarged view of region II in FIG.
• Figure 3 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.
• CVD Chemical Vapor Deposition
• a cutting tool that includes a substrate and a coating disposed on the substrate.
• the coating includes a first layer made of ⁇ -Al 2 O 3 and having a thickness of 2 ⁇ m to 15 ⁇ m.
• the first layer includes a plurality of grain boundaries connecting an interface of the first layer close to the substrate with a surface of the first layer or an interface of the first layer close to the surface of the coating.
• At least one of the grain boundaries, the first grain boundary has a plurality of straight line segments and three or more bending points connecting two adjacent straight line segments.
• it has been difficult to impart excellent "wear resistance” due to the coarsening of particles in the region near the surface of the first coating layer. Therefore, there is a demand for cutting tools that combine excellent "wear resistance” and excellent “chipping resistance” to provide excellent tool life.
• the present disclosure therefore aims to provide a cutting tool with excellent tool life, particularly in turning.
• 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;
• the first layer includes a plurality of grain boundaries connecting an interface of the first layer close to the substrate and an interface of the first layer close to a surface of the first layer or a surface of the coating, and at least one of the grain boundaries, a first grain boundary, has a plurality of straight line segments and three or more bending points connecting two adjacent straight line segments,
• a crossing angle A1 at the bending point closest to the interface close to the substrate of the first layer and a crossing angle A2 next closest to the bending point are each 90° or more and 150° or less,
• This disclosure makes it possible to provide cutting tools with excellent tool life, particularly in turning operations.
• the average distance D1 between two adjacent bending points at the first grain boundary along the normal to the interface between the substrate and the coating may be 0.05 ⁇ m or more and 4 ⁇ m or less. This makes it possible to provide a cutting tool with a longer tool life, particularly in turning.
• the thickness of the first layer may be less than 8 ⁇ m, and the surface of the first layer or the surface of the first layer located at the interface close to the surface of the coating may have a surface roughness Ra of 0.03 ⁇ m or more and 0.2 ⁇ m or less. This makes it possible to provide a cutting tool with a longer tool life, particularly in turning.
• 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 close to the surface of the coating may have a surface roughness Ra of 0.05 ⁇ m or more and 0.2 ⁇ m or less, thereby providing a cutting tool with a longer tool life, particularly in turning.
• 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, particularly in turning.
• 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.
• Figure 2 is an enlarged view of region II in Figure 1.
• 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 first layer 3 includes a plurality of grain boundaries GB connecting an interface I1 of the first layer 3 close to the substrate 1 and a surface S1 of the first layer 3 or an interface of the first layer 3 close to the surface of the coating 2, and at least one of the grain boundaries GB, a first grain boundary GB1, has a plurality of straight line segments and three or more bending points connecting two adjacent straight line segments, In the first grain boundary GB1, a crossing angle A1 at the bending point closest to the interface I1 close to the substrate 1 of the first layer 3 and a crossing angle A2 next closest thereto
• the first layer 3 in a cross section taken along the normal to the interface between the substrate 1 and the coating 2, includes a plurality of grain boundaries GB connecting the interface I1 of the first layer 3 close to the substrate 1 and the surface S1 of the first layer 3 or the interface of the first layer 3 close to the surface of the coating 2, and at least one of the grain boundaries GB, the first grain boundary GB1, has a plurality of straight line segments and three or more bending points connecting two adjacent straight line segments, and in the first grain boundary GB1, the intersection angle A1 at the bending point closest to the interface I1 of the first layer 3 close to the substrate 1 and the second closest intersection angle A2 and A2 are each 90° or more and 150° or less, and in the first grain boundary GB1, the crossing angle A4 at the bend point closest to the interface close to the surface S1 of the first layer 3 or the surface of the coating 2 of the first layer 3 and the next-closest crossing angle A3 are each 120° or more and less than 180°, and in the first grain boundary GB1, the intersection angle
• 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 the surface of at least a portion of the substrate 1 that is involved in cutting.
• the portion of the substrate 1 that is involved in cutting refers to the region of the substrate 1 that is 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, of, 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 (arithmetic mean) 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 ⁇ -Al 2 O 3 in the first layer 3 can be considered to exist as particles.
• a grain boundary GB which will be described later, refers to the interface between a particle and an adjacent particle.
• 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 close to the surface of the coating 2 may have a surface roughness Ra of 0.03 ⁇ m or more and 0.2 ⁇ m or less. This makes it possible to suppress localized fracture during surface treatment of the coating 2 and facilitates the imparting of uniform residual stress, thereby providing the cutting tool 10 with a longer tool life, particularly in turning.
• 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 S1 of the first layer 3, or the surface of the first layer 3 located at the interface close to the surface of the coating 2, may have a surface roughness Ra of 0.05 ⁇ m or more and 0.2 ⁇ m or less. This makes it possible to suppress localized fracture during surface treatment of the coating 2 and makes it easier to impart uniform residual stress, thereby providing the cutting tool 10 with a longer tool life, particularly in turning.
• 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 (arithmetic mean) 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. Note that it has been confirmed that there is no variation in the measurement results even if the measurement location is arbitrarily selected, as long as the measurement is performed on the same first layer 3.
• the first layer 3 includes multiple grain boundaries GB connecting the interface I1 of the first layer 3 close to the substrate 1 with the surface S1 of the first layer 3 or with an interface of the first layer 3 close to the surface of the coating 2. At least one of the grain boundaries GB, the first grain boundary GB1, has multiple straight line segments and three or more bending points connecting two adjacent straight line segments. These features improve the "chipping resistance" of the first layer 3.
• the crossing angle A1 at the bending point closest to the interface I1 of the first layer 3 close to the substrate 1 and the second-closest crossing angle A2 are each 90° or greater and 150° or less.
• the crossing angle A4 at the bending point closest to the interface close to the surface S1 of the first layer 3 or the surface of the coating 2 of the first layer 3 and the second-closest crossing angle A3 are each 120° or greater and less than 180°.
• the average X1 of the crossing angles A1 and A2 and the average X2 of the crossing angles A3 and A4 satisfy the relationship of Formula 1.
• the upper limit of each of the crossing angles A4 and A3 may be 175° or less, or may be 170° or less.
• the ratio N2/N1 which is the ratio of the number N2 of first grain boundaries GB1 to the number N1 of grain boundaries GB, is 0.2 or greater. This provides the first layer 3 with excellent wear resistance and excellent chipping resistance.
• the upper limit of the ratio N2/N1 may be 1.0 or less, or 0.7 or less.
• the ratio N2/N1 may be 0.3 or greater and 1.0 or less, 0.4 or greater and 1.0 or less, or 0.5 or greater and 1.0 or less.
• the ratio N2/N1 can be determined by the following method.
• (a1) A color map is created based on the crystal orientation of each particle (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 grain boundary GB of any one particle (crystal particle) is colored white and the other areas are colored black, thereby outputting the image to obtain a first image.
• (c1) Observe the pixels in each column in the first image in order from the left edge of the image, and identify the point where the color first changes from black to white as "any one grain boundary GB connecting the interface I1 close to the substrate of the first layer and the surface S1 of the first layer or an interface close to the surface of the coating of the first layer.”
• (d1) For each pixel in each column of the grain boundary GB in the first image identified in (c1), a rectangular area of 15 ⁇ 15 pixels (i.e., 0.3 ⁇ m ⁇ 0.3 ⁇ m) centered on the pixel is fitted with a linear equation to obtain the angle of the grain boundary GB at each pixel.
• (f1) When the grain boundary GB identified in (c1) has multiple straight line segments and three or more bending points connecting two adjacent straight line segments, the crossing angle A1 at the bending point closest to the interface I1 close to the substrate of the first layer and the crossing angle A2 closest to the next bending point are identified in order from the substrate side of the first layer. Also, the crossing angle A4 at the bending point closest to the interface close to the surface S1 of the first layer or the surface of the coating of the first layer and the crossing angle A3 closest to the next bending point are identified in order from the interface side close to the surface S1 of the first layer or the surface of the coating of the first layer. (g1) Calculate the average X1 by dividing the sum of the crossing angles A1 and A2 specified in (f1) by 2.
• (h1) For "any other at least 17 grain boundaries GB connecting an interface I1 close to the substrate of the first layer and an interface close to the surface S1 of the first layer or the surface of the coating of the first layer," (f1) to (g1) are performed to identify the crossing angle A1, the crossing angle A2, the crossing angle A3, the crossing angle A4, the average X1, and the average X2 for each of the other any other at least 17 grain boundaries GB.
• the crossing angles A1 and A2 are each 90° or more and 150° or less, the crossing angles A4 and A3 are each 120° or more and less than 180°, and the average X1 and average X2 satisfy the relationship of Formula 1.
• the number of grain boundaries GB i.e., first grain boundaries GB1 is divided by the number of grain boundaries GB (i.e., 18 or more) to specify the "proportion N2/N1 of the number N2 of first grain boundaries GB1 to the number N1 of grain boundaries GB.”
• the average distance D1 between two adjacent bending points along the normal to the interface between the substrate 1 and the coating 2 may be 0.05 ⁇ m or more and 4 ⁇ m or less. This makes it easier to improve the flexural strength of the coating 2, thereby providing the cutting tool 10 with a longer tool life, particularly in turning.
• the average distance D1 may be 0.06 ⁇ m or more and 3 ⁇ m or less, 0.07 ⁇ m or more and 2 ⁇ m or less, or 0.08 ⁇ m or more and 1 ⁇ m or less.
• the average distance D1 can be determined by the following method. (a2) Using the same method as in (a1) to (g1) above, the crossing angle A1, the crossing angle A2, the average X1, and the average X2 at the grain boundary GB are identified, thereby identifying any one first grain boundary GB1.
• the average distance D1 can be determined by dividing the sum of the average distances between two adjacent bending points along the normal to the interface between the substrate and the coating for each of a total of five first grain boundaries GB1 by 5.
• 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 grains in the first layer 3 (in other words, the ⁇ -Al 2 O 3 grains (crystal grains)), thereby further improving the wear resistance of the first layer 3. As a result, the cutting tool 10 can be endowed with a longer tool life, particularly in turning.
• 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, equal to or greater than 6.0 and equal to or less than 7.9, or equal to or greater than 6.0 and equal to or less than 7.7.
• 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 2.
• I(hkl) represents the X-ray diffraction intensity of the (hkl) reflection plane
• I 0 (hkl) represents the standard intensity according to ICDD PDF card number 00-010-0173.
• n in Equation 2 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 formula 3.
• 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 equation 2 above to obtain equation 3 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. 3 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.
• Step I the film formation time for the (001) film formation is 5 to 180 minutes, and the rotation speed of the nozzle for the (001) film formation is 0.5 to 4 rpm. Also, in Step I, the film formation time for the (110) film formation is 5 to 180 minutes, and the rotation speed of the nozzle for the (110) film formation is 0.5 to 6 rpm.
• Step II the film formation time for the (001) film formation is 4 to 90 minutes, and the rotation speed of the nozzle for the (001) film formation is 0.2 to 2 rpm. Furthermore, in step II, the film formation time for the (110) film formation is 4 to 90 minutes, and the rotation speed of the nozzle for the (110) film formation is 0.4 to 4 rpm.
• the rotation speed of the nozzle for the (001) film formation in step I is 0.1 rpm or more faster than the rotation speed of the nozzle for the (001) film formation in step II.
• (rotation speed of the nozzle for the (001) film formation in step I) - (rotation speed of the nozzle for the (001) film formation in step II) is 0.1 rpm or more.
• the rotation speed of the nozzle for the (001) film formation in step I may be 0.5 rpm or more faster, or may be 1 rpm or more faster, than the rotation speed of the nozzle for the (001) film formation in step II.
• the rotation speed of the nozzle for the (110) film formation in step I is 0.1 rpm or more faster than the rotation speed of the nozzle for the (110) film formation in step II.
• step I the rotation speed of the nozzle for (110) film formation in step I
• step II the rotation speed of the nozzle for (110) film formation in step II
• the rotation speed of the nozzle for (110) film formation in step I may be 0.5 rpm or more faster than the rotation speed of the nozzle for (110) film formation in step II, or may be 1 rpm or more faster.
• the total number of (001) film formations in step I and the total number of (110) film formations in step II is 2 or more, and the total number of (110) film formations in step I and the total number of (110) film formations in step II is 2 or more.
• the (001) film formation is performed by injecting the mixed gas from the first injection hole 61 and the second injection hole 62, and the (110) film formation is performed by injecting the mixed gas from the third injection hole (not shown) and the fourth injection hole (not shown).
• the (001) film formation may be started, or the (110) film formation may be started.
• the thickness of the first layer can be adjusted by appropriately adjusting the number of times the (001) film is formed and the number of times the (110) film is formed.
• the second step may include a surface treatment step such as surface grinding or blasting.
• step 2a (001) film formation, in which the film formation time is 4 to 180 minutes and the nozzle rotation speed is 0.5 to 4 rpm, and (110) film formation, in which the film formation time is 4 to 180 minutes and the nozzle rotation speed is 0.5 to 6 rpm, are alternately performed (step I), and then (001) film formation, in which the film formation time is 4 to 90 minutes and the nozzle rotation speed is 0.2 to 2 rpm, and (110) film formation, in which the film formation time is 4 to 90 minutes and the nozzle rotation speed is 0.4 to 4 rpm, are alternately performed (step II).
• the (001) film formation is performed by injecting the mixed gas from the first and second injection holes, and the (110) film formation is performed by injecting the mixed gas from the third and fourth injection holes.
• the rotation speed of the nozzle for (001) film formation in step I is faster by 0.1 rpm or more than the rotation speed of the nozzle for (001) film formation in step II, and the rotation speed of the nozzle for (110) film formation in step I is faster by 0.1 rpm or more than the rotation speed of the nozzle for (110) film formation in step II.
• the total number of (001) film formations in step I and the number of (001) film formations in step II is 2 or more, and the total number of (110) film formations in step I and the number of (110) film formations in step II is 2 or more.
• the crossing angle at the grain boundary can be kept relatively small in a region close to the substrate of the first layer, while the crossing angle at the grain boundary can be made relatively large in a region close to the surface of the coating of the first layer. Therefore, the crossing angles A1, A2, A3, A4, the average X1 of the crossing angles A1 and A2, and the average X2 of the crossing angles A3 and A4 can each be adjusted within a desired range, and the ratio N2/N1 of the number N2 of first grain boundaries to the number N1 of grain boundaries can be adjusted within a desired range.
• the present 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.
• a turning tip (shape: CNMG120408N-GZ, manufactured by Sumitomo Electric Hardmetal Corp.) having the following composition was prepared. (Composition of the substrate) Co content: 6.0% by mass TaC content: 1.5% by mass WC content: remaining
• ⁇ Second process ⁇ A first layer was formed on the surface of the substrate by performing a CVD method (step 2a). First, for samples 1 to 19, 101, 102, and 104, (001) film formation was performed for the film formation time as shown in Table 1, and the conditions for the nozzle rotation speed were as shown in Table 1, and (110) film formation was performed for the film formation time as shown in Table 1, and the conditions for the nozzle rotation speed were as shown in Table 1. These were alternately performed the number of times shown in the "Number of repetitions [times]" column in Table 1 (step I).
• step I and step II started with the (001) film formation. Furthermore, “(Nozzle rotation speed for the (001) film formation in step I) - (Nozzle rotation speed for the (001) film formation in step II)” and “(Nozzle rotation speed for the (110) film formation in step I) - (Nozzle rotation speed for the (110) film formation in step II)” were as shown in Table 3.
• 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 Table 4. Note that when a component name is listed in the “Composition” column of the “First Layer” column in Table 4, it means that the first layer is composed of the component represented by that component name.
• Cutting tools according to samples 1 to 19 correspond to examples.
• Cutting tools according to samples 101 to 104 correspond to comparative examples.
• the results of Cutting Test 1 and Cutting Test 2 in Table 4 show that cutting tools according to samples 1 to 19 have superior tool life compared to cutting tools according to samples 101 to 104.

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