JP2022171411A - Cutting tool - Google Patents

Abstract

To provide a cutting tool having excellent abrasion resistance and defect resistance.SOLUTION: A cutting tool includes: a base material 10; and a coat 11 disposed on the base material 10. The coat 11 includes a hard particle layer. The hard particle layer is formed of multiple hard particles including titanium, silicon, carbon, and nitrogen. In the hard particle, a concentration of the silicon cyclically changes along a first direction set in the hard particle. An orientation of the hard particle layer is (420) orientation. An average cycle width of the concentration of the silicon ranges 3 nm to 50 nm.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to cutting tools.

Conventionally, a cutting tool having a TiSiCN film formed on a substrate has been developed in order to improve the wear resistance of the cutting tool.

US Pat. No. 5,300,001 discloses a nanocomposite coating comprising a nanocrystalline layer of TiC _x N _1-x and a second phase of amorphous SiC _x N _y produced by thermal CVD.

Non-Patent Document 1 discloses a TiSiCN film having a nanocomposite structure formed by the PVD method.

Japanese Patent Application Publication No. 2015-505902

Shinya Imamura et al. , "Properties and cutting performance of AlTiCrN/TiSiCN bilayer coatings deposited by cathodic-arc ion plating", Surface and Coatings Technology, 202, (2007), 820-825

In recent years, there has been an increasing demand for reducing manufacturing costs, and cutting tools with a long tool life are being demanded.

Accordingly, an object of the present disclosure is to provide a cutting tool having a long tool life.

A cutting tool of the present disclosure comprises a substrate and a coating disposed on the substrate,
The coating comprises a hard particle layer,
The hard particle layer consists of a plurality of hard particles containing titanium, silicon, carbon and nitrogen,
In the hard particles, the concentration of the silicon periodically changes along a first direction set in the hard particles,
The orientation of the hard particle layer is the (420) orientation of the cutting tool.

According to the present disclosure, it is possible to provide a cutting tool with long tool life.

FIG. 1 is a schematic diagram showing an example of a cross section of a cutting tool according to Embodiment 1. FIG. FIG. 2 is a schematic diagram showing another example of the cross section of the cutting tool according to Embodiment 1. FIG. FIG. 3 is a schematic diagram showing another example of the cross section of the cutting tool according to Embodiment 1. FIG. 4 is a schematic diagram showing another example of the cross section of the cutting tool according to Embodiment 1. FIG. 5 is a diagram schematically showing an example of a bright-field transmission electron microscope (BF-STEM) image (observation magnification: 100,000 times) of a cross section of the hard phase particle layer of the cutting tool according to Embodiment 1. FIG. 6 is a diagram schematically showing an example of a bright-field transmission electron microscope (BF-STEM) image (observation magnification: 2,000,000 times) of a cross section of the hard phase particle layer of the cutting tool according to Embodiment 1. FIG. 7 is an example of a graph showing the results of line analysis of hard particles of the cutting tool according to Embodiment 1. FIG. FIG. 8 is a schematic cross-sectional view of an example of a CVD apparatus used for manufacturing a cutting tool according to Embodiment 2. FIG.

[Description of Embodiments of the Present Disclosure]
First, the embodiments of the present disclosure are listed and described.
(1) A cutting tool of the present disclosure comprises a substrate and a coating disposed on the substrate,
The coating comprises a hard particle layer,
The hard particle layer consists of a plurality of hard particles containing titanium, silicon, carbon and nitrogen,
In the hard particles, the concentration of the silicon periodically changes along a first direction set in the hard particles,
The orientation of the hard particle layer is the (420) orientation of the cutting tool.

According to the present disclosure, cutting tools can have a long tool life.

(2) In the hard particles, the percentage of the number of silicon atoms A _Si to the sum of the number of titanium atoms A _Ti and the number of silicon atoms A _Si {A _Si /(A _Si +A _Ti )}× The average of 100 is preferably 1% or more and 20% or less.

According to this, the tool life of the cutting tool is further improved.

(3) It is preferable that the average period width of the concentration of silicon is 3 nm or more and 50 nm or less. According to this, the tool life of the cutting tool is further improved.

(4) The thickness of the hard particle layer is preferably 1 μm or more and 20 μm or less. According to this, the tool life of the cutting tool is further improved.

(5) the substrate is made of a cemented carbide containing tungsten carbide and cobalt;
The content of cobalt in the cemented carbide is preferably 6% by mass or more and 11% by mass or less.

According to this, the tool life of the cutting tool is further improved.

[Details of the embodiment of the present disclosure]
A specific example of the cutting tool of the present disclosure will be described below with reference to the drawings. In the drawings of this disclosure, the same reference numerals represent the same or equivalent parts. Also, dimensional relationships such as length, width, thickness, and depth are appropriately changed for clarity and simplification of the drawings, and do not necessarily represent actual dimensional relationships.

In this specification, the notation of the form "A to B" means the upper and lower limits of the range (that is, from A to B). and the unit of B are the same.

In the present specification, when a compound or the like is represented by a chemical formula, when the atomic ratio is not particularly limited, it includes any conventionally known atomic ratio, and should not necessarily be limited only to the stoichiometric range. For example, when "TiSiCN" is described, the ratio of the number of atoms constituting TiSiCN includes all conventionally known atomic ratios.

[Embodiment 1: Cutting tool]
A cutting tool of one embodiment of the present disclosure (hereinafter also referred to as "this embodiment") is a cutting tool comprising a base material and a coating disposed on the base material,
The coating comprises a hard particle layer,
The hard particle layer consists of a plurality of hard particles containing titanium, silicon, carbon and nitrogen,
In the hard particles, the silicon concentration varies periodically along a first direction set in the hard particles,
The orientation of the hard particle layer is a (420) orientation cutting tool.

The cutting tool of this embodiment can have a long tool life. The reason for this is presumed to be as follows (i) to (iii).

(i) In the cutting tool of the present embodiment, the coating contains a hard particle layer composed of a plurality of hard particles containing titanium, silicon, carbon and nitrogen. Hard particles containing titanium, silicon, carbon and nitrogen have high hardness. Therefore, the hard particle layer made of the hard particles has high hardness and excellent wear resistance.

(ii) In the hard particles of the cutting tool of the present embodiment, the concentration of silicon periodically changes along the first direction set in the hard particles. According to this, strain occurs in the hard particles, the hardness of the hard particles and the hard particle layer increases, and the wear resistance of the cutting tool improves. In addition, the composition change in the hard particles suppresses the propagation of cracks and improves the chipping resistance of the cutting tool.

(iii) In the cutting tool of the present embodiment, the orientation of the hard particle layer is (420) orientation. When the orientation of the hard particle layer is the (420) orientation, the hardness of the hard particle layer is improved due to the high twin crystal density. Cutting tools containing the hard particle layer exhibit excellent wear resistance, especially in tool steel cutting. This is a finding newly discovered by the inventors of the present invention.

<Configuration of cutting tool>
As shown in FIG. 1 , the cutting tool 1 of this embodiment includes a substrate 10 and a coating 14 placed on the substrate 10 . In FIG. 1, the coating 14 consists of the hard particle layer 11 only. The coating 14 preferably covers at least a portion of the substrate involved in cutting, and more preferably covers the entire surface of the substrate. The portion involved in cutting of the substrate means a region within 500 μm from the ridgeline of the cutting edge on the surface of the substrate. It would not depart from the scope of the present disclosure if portions of the substrate were not coated with this coating or if the composition of the coating varied.

The coating can include other layers in addition to the hard particle layer. For example, as shown in cutting tool 21 in FIG. 2 , coating 24 can further include underlayer 12 disposed between substrate 10 and hard-particle layer 11 in addition to hard-particle layer 11 . .

As shown in cutting tool 31 of FIG. 3 , coating 34 may include hard particle layer 11 and underlayer 12 as well as outermost layer 13 disposed on hard particle layer 11 .

As shown in the cutting tool 41 of FIG. 4, the coating 45 may include the hard particle layer 11, the base layer 12 having a two-layer structure of the first base layer 12A and the second base layer 12B, and the outermost layer 13. can.

<Types of cutting tools>
Cutting tools of the present disclosure include, for example, drills, end mills (e.g., ball end mills), indexable cutting inserts for drills, indexable cutting inserts for end mills, indexable cutting inserts for milling, indexable cutting inserts for turning. It can be a cutting tip, metal saw, gear cutting tool, reamer, tap, or the like.

<Base material>
The substrate 10 includes a rake face and a flank, and any conventionally known substrate of this type can be used. For example, cemented carbide (for example, WC-based cemented carbide containing tungsten carbide and cobalt, the cemented carbide may contain carbonitrides such as Ti, Ta, Nb), cermet (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.

Among these various substrates, a substrate made of a cemented carbide containing tungsten carbide and cobalt and having a cobalt content in the cemented carbide of 6% by mass or more and 11% by mass or less is preferable. According to this, it has an excellent balance of hardness and strength at high temperatures, and has excellent properties as a base material for cutting tools for the above applications. When a WC-based cemented carbide is used as the substrate, its structure may contain free carbon, an abnormal layer called η phase or ε phase, and the like.

Further, the substrate may have a modified surface. For example, in the case of cemented carbide, a β-free layer may be formed on the surface, and in the case of cermet, a hardened surface layer may be formed. The substrate exhibits the desired effect even if its surface has been modified.

If the cutting tool is an indexable cutting tip or the like, the substrate may or may not have a chip breaker. The shape of the cutting edge ridgeline is sharp edge (the ridge where the rake face and the flank face intersect), honing (sharp edge with radius), negative land (chamfering), or a combination of honing and negative land. Any of them, such as a combination thereof, can be adopted.

<Structure of coating>
The coating of this embodiment includes a hard particle layer. The coating of this embodiment may contain other layers as long as it contains the hard particle layer. Other layers include, for example, an underlying layer and an outermost layer. The details of the hard particle layer, underlayer and outermost layer will be described later.

The thickness of the entire coating of the present embodiment is preferably 1 μm or more and 30 μm or less. When the thickness of the entire coating is 1 μm or more, excellent abrasion resistance can be obtained. On the other hand, when the thickness of the entire coating is 30 μm or less, it is possible to suppress the occurrence of peeling or breakage of the coating when a large stress is applied between the coating and the substrate during intermittent machining.

The thickness of the coating is measured, for example, by obtaining a cross-sectional sample parallel to the normal direction of the surface of the substrate and observing this sample with a scanning transmission electron microscope (STEM). Scanning transmission electron microscopes include JEM-2100F (trademark) manufactured by JEOL Ltd., for example. The measurement conditions are an acceleration voltage of 200 kV and a current of 0.3 nA.

As used herein, the term "thickness" means an average thickness. Specifically, the observation magnification of the cross-sectional sample is 1000 times, and a rectangular measurement field of (100 μm in the direction parallel to the substrate surface) × (distance including the entire thickness of the coating) is set in the electron microscope image, Ten thickness widths are measured in the field of view, and the average value is defined as "thickness". The thickness (average thickness) of each layer described below is similarly measured and calculated.

As long as the measurement is performed on the same sample, there is almost no variation in the measurement results even if the measurement field of view is changed and the measurement is performed multiple times. It is

<Hard particle layer>
The hard particle layer consists of a plurality of hard particles including titanium (Ti), silicon (Si), carbon (C) and nitrogen (N). The hard particles include TiSiCN particles composed of titanium, silicon, carbon and nitrogen. TiSiCN particles can contain unavoidable impurities other than titanium, silicon, carbon and nitrogen as long as they do not affect the effects of the present disclosure. Even if the inevitable impurities include, for example, amorphous phases and intermetallic compounds (eg, TiSi ₂ , Co ₂ Si, etc.), they do not deviate from the scope of the present disclosure as long as the effects of the present disclosure are exhibited.

(hard particles)
In the hard particles, the concentration of silicon varies periodically along the first direction set in the hard particles. In this specification, the first direction is defined as a direction specified by methods (A1) to (A4) below.

(A1) A cutting tool is cut out with a diamond wire along the normal line of the rake face of the substrate to expose the cross section of the hard particle layer. At this time, the sample to be measured is prepared as a slice sample processed using an ion slicer or the like.

(A2) Observe the processed flake sample with a bright-field transmission electron microscope (BF-STEM) at a magnification of 100,000 to identify one hard particle. FIG. 5 is a diagram schematically showing an example of a BF-STEM image (observation magnification: 100,000 times) of the hard particle layer of this embodiment. Next, one identified hard particle is observed at a magnification of 2,000,000 times to obtain a BF-STEM image. FIG. 6 is a diagram schematically showing an example of a BF-STEM image (observation magnification: 2,000,000 times) of one hard particle identified in FIG.

(A3) In the BF-STEM image (observation magnification: 2,000,000 times), the layer shown in black (hereinafter also referred to as “first unit layer”) and the layer shown in gray (hereinafter, “second unit layer”) A region (hereinafter, also referred to as a “laminated region”) in which two unit layers” are alternately laminated substantially in parallel is specified. The first unit layer shown in black is a region with a high silicon content, and the second unit layer shown in gray is a region with a low silicon content.

(A4) Identify the stacking direction of the first unit layer (black layer) and the second unit layer (gray layer) in the stacking region specified above. Specifically, the stacking orientation of the first unit layer and the second unit layer is superimposed on the electron beam diffraction pattern of the selected visual field region, and the stacking orientation is specified using the orientation indicated by the diffraction spots. In FIG. 6, the lamination direction of the first unit layer and the second unit layer is indicated by an arrow from a circle S to a circle E. As shown in FIG. In this specification, the stacking direction is defined as the first direction.

From the above, in this specification, the first direction can also be defined as a direction along the stacking direction in the hard particles.

In the hard particle layer of the present embodiment, the line along the first direction intersects the interface between the substrate and the coating at a predetermined angle of 45° or more and 90° or less.

In the present specification, it is confirmed by the following method that the concentration of silicon in the hard particles periodically changes along the first direction set in the hard particles.
(B1) In the above BF-STEM image (observation magnification: 2,000,000 times), line analysis is performed along the first direction by EDX (Energy Dispersive X-ray Spectroscopy) attached to the SEM. Then, the content A _Ti of titanium based on the number of atoms and the content A _Ti of silicon based on the number of atoms are measured. The beam diameter for line analysis is 0.5 nm or less, the scan interval is 0.5 nm, and the length of line analysis is 50 nm.

(B2) For the line analysis result, the X axis is the distance (nm) along the first direction from the starting point of the line analysis, and the Y axis is the number of silicon atoms A _Si and the number of titanium atoms A _Ti . A graph shown in a coordinate system of the percentage of silicon atoms A _Si ({A _Si /(A _Si +A _Ti )}×100) (%) is obtained. The graph shows the percentage of the number of silicon atoms A _Si to the sum of the number of silicon atoms A _Si and the number of titanium atoms A _Ti as the distance along the first direction (X-axis) increases from the starting point of the line analysis. (Y-axis) changes.

Line analysis was performed on the arrow from circle mark S to circle mark E in the BF-STEM image of FIG. 6, and a graph obtained from the result is shown in FIG. In FIG. 7, the X-axis indicates the distance (nm) along the first direction from the starting point of the line analysis, and the Y-axis indicates the total number of silicon atoms A _Si and titanium atoms A _Ti . The percentage of the number A _Si ({A _Si /(A _Si +A _Ti )}×100) (%) is shown.

(B3) A line L1 indicating the average value of {A _Si /(A _Si +A _Ti )}×100 is drawn on the above graph. In FIG. 7, the line L1 indicates the average value e1 of {A _Si /(A _Si +A _Ti )}×100.

(B4) In the above graph, the region where the value of {A _Si /(A _Si +A _Ti )} × 100 is larger than the line L1 (hereinafter also referred to as “first A region”) and the {A _Si / (A _Si + A _Ti )} × 100 If the regions with a small value (hereinafter also referred to as "first B region") are alternately present along the first direction, in the hard particles , along a first direction set in the hard particles, the concentration of silicon is determined to vary periodically. Here, the region where {A _Si /(A _Si +A _Ti )}×100 is the same as the average value is defined as the first A region.

In FIG. 7 , the first A region is, for example, c1 or more and c2 or less, c3 or more and c4 or less, c5 or more and c6 or less, c7 or more and c8 or less, c9 or more and c10 or less, or c11 along the first direction from the start point of the line analysis. It is an area of c12 or less (distance greater than c13 is omitted). In FIG. 7, the 2A region is, for example, the distance along the first direction from the start point of the line analysis is more than c2 and less than c3, more than c4 and less than c5, more than c6 and less than c7, more than c8 and less than c9, more than c10 and less than c11, c12 It is the area of super-c13 and below.

In each 1st A region, from the point closest to the starting point of the line analysis, the value of {A _Si / (A _Si +A _Ti )} × 100 increases from the average value as the distance from the starting point of the line analysis increases. It is preferred to increase to a maximum value within the first A region and then decrease to an average value.

The above-mentioned increase in the 1st A region is not limited to a monotonous increase, and in the middle of the increase, the average value of the values of {A _Si /(A _Si +A _Ti )}×100 and the maximum value in the 1st A region There may be a reduction of up to 50% of the difference. In addition, the above-mentioned decrease in the first A region is not limited to a monotonous decrease, and during the decrease, the average value of the values of {A _Si /(A _Si +A _Ti )}×100 and the maximum value in the first A region There may be an increase of up to 50% of the difference from

In each 1B region, from the point closest to the starting point of the line analysis, the value of {A _Si / (A _Si +A _Ti )} × 100 increases from the average value as the distance from the starting point of the line analysis increases. Preferably, it decreases to a minimum value within the 1B region and then increases to an average value.

The above decrease in the 1B region is not limited to a monotonous decrease, and in the middle of the decrease, the average value of the values of {A _Si /(A _Si +A _Ti )}×100 and the minimum value in the 1B region There may be an increase of up to 50% of the difference. In addition, the above- _mentioned increase in the _1B region is not limited to a _monotonous increase. There may be a reduction of up to 50% of the difference between

For example, in FIG. 7, in the first A region where the distance along the first direction from the starting point of the line analysis is c1 or more and c2 or less, the value a1 of {A _Si /(A _Si +A _Ti )}×100 at P1 is the first A Maximum value in the region. In the first A region, the value of {A _Si /(A _Si +A _Ti )}×100 increases from the average e1 to It increases to the maximum value a1 and then decreases from the maximum value a1 to the average value e1. In FIG. 7, in the 1B region where the distance along the first direction from the starting point of the line analysis is more than c2 and less than c3, the value b1 of {A _Si / (A _Si +A _Ti )} × 100 in B1 is within the 1B region is the minimum value of In the 1B region, the value of {A _Si /(A _Si +A _Ti )}×100 increases from the average value e1 to It decreases to the minimum value b1 and then increases from the minimum value b1 to the average value e1.

As long as it is confirmed by the above method that the concentration of silicon in the hard particles periodically changes along the first direction set in the hard particles, it is confirmed that the effects of the present disclosure are exhibited. ing.

({A _Si /(A _Si +A _Ti )}×100)
In the hard particles of the present embodiment, the average of the percentage {A _Si /(A _Si +A _Ti )}×100 of the number of silicon atoms A _Si with respect to the sum of the number of titanium atoms A _Ti and the number A _Si of silicon atoms is preferably 1% or more and 20% or less.
According to this, the wear resistance and chipping resistance of the cutting tool are further improved, and the tool life is further improved.

The above {A _Si /(A _Si +A _Ti )}×100 is more preferably 1% or more and 10% or less, still more preferably 1% or more and 5% or less, from the viewpoint of improving film hardness and toughness.

In this specification, the average of {A _Si /(A _Si +A _Ti )}×100 in the hard particles means {A _Si /(A _Si +A _Ti )}× mean of 100 values.

The maximum value of {A _Si /(A _Si +A _Ti )}×100 in the hard particles is preferably 1.5% or more and 40% or less, and 1.5% or more and 20% or less, from the viewpoint of improving film hardness and toughness. More preferably 1.5% or more and 10% or less. In the present specification, the "maximum value of {A _Si /(A _Si +A _Ti )}×100 in hard particles" is a value calculated by the following method. First, the maximum value of {A _Si /(A _Si +A _Ti )}×100 is measured in each first A region existing in the region where the line analysis was performed in the hard particles. The average of the maximum values in each first A region corresponds to the "maximum value of {A _Si /(A _Si +A _Ti )}×100 in hard particles". The minimum value of {A _Si /(A _Si +A _Ti )}×100 in the hard particles can be calculated by replacing the maximum value with the minimum value in the method for calculating the maximum value.

The difference between the maximum value and the minimum value of {A _Si /(A _Si +A _Ti )}×100 is preferably 1% or more and 38% or less, more preferably 1% or more and 20% or less, from the viewpoint of improving film hardness and toughness. It is preferably 1% or more and 8% or less.

As long as the same sample is measured, there is almost no variation in the measurement results even if the line analysis of hard particles is performed multiple times by changing the measurement point, and even if the measurement point is set arbitrarily, it will not be arbitrarily. It has been confirmed that it will not.

(Average cycle width of silicon concentration)
The average period width of the concentration of silicon in the first direction set in the hard particles of the present embodiment is preferably 3 nm or more and 50 nm or less. According to this, the wear resistance and chipping resistance are improved, and the tool life is improved. The lower limit of the period width of the silicon concentration is preferably 3 nm or more, more preferably 4 nm or more, and even more preferably 5 nm or more, from the viewpoint of improving chipping resistance. The upper limit of the period width of the silicon concentration is preferably 50 nm or less, more preferably 30 nm or less, and even more preferably 10 nm or less from the viewpoint of improving wear resistance. The periodic width of the silicon concentration is more preferably 4 nm or more and 30 nm or less, and further preferably 5 nm or more and 10 nm or less.

In this specification, the method for measuring the period width of the silicon concentration is as follows. A lamination region is set by the same method as (A1) to (A3) above. A Fourier transform is performed on the laminated region to obtain a Fourier transform image. In the Fourier transform image, the periodicity within the layered region appears as spots. The period width is calculated by calculating the reciprocal of the distance between the spot and the center of the image showing maximum intensity in the Fourier transform image.

As long as the measurement is performed on the same sample, there is almost no variation in the measurement results even if the measurement is performed multiple times by changing the measurement points in the hard particles. Confirmed.

The periodic width obtained by the above Fourier transform corresponds to the distance along the first direction between the positions where {A _Si /(A _Si +A _Ti )}×100 existing in the adjacent first A region is the maximum value. . The distance along the first direction between positions where {A _Si /(A _Si +A _Ti )}×100 existing in the adjacent first A regions is the maximum value is the distance between P1 and P2 in FIG. d1, distance d2 between P2 and P3, distance d3 between P3 and P4, distance d4 between P4 and P5, distance d5 between P5 and P6, distance between P6 and P7. corresponds to d6.

(Particle size of hard particles)
The particle size of the hard particles of the present embodiment is preferably, for example, 10 nm or more and 1000 nm or less. According to this, excellent chipping resistance can be obtained. The particle size of the hard particles is more preferably 10 nm or more and 700 nm or less, and even more preferably 10 nm or more and 500 nm or less.

The method for measuring the particle size is as follows. The substrate and the film formed on the substrate are processed with an FIB processing material so that the cross section can be seen, and the cross section is observed with an FE-SEM (Field Emission Scanning Electron Microscope). At that time, by observing as a backscattered electron image, portions having the same crystal orientation are observed with the same contrast, and this same contrast portion is regarded as one hard particle.

Next, a straight line of arbitrary length (preferably equivalent to 400 μm) parallel to the surface of the substrate is drawn at an arbitrary point on the hard particle layer on the image thus obtained. Then, the number of hard particles included in the straight line is measured, and the diameter of the hard particles is obtained by dividing the length of the straight line by the number of hard particles.

(Orientation of hard particle layer)
In this embodiment, the orientation of the hard particle layer is (420) orientation. In the present specification, "the orientation of the hard particle layer is (420) orientation" means that the orientation index TC (hkl) defined by the following formula (1) is the (420) plane in the hard particle layer means that the orientation index TC (420) of is greater than the orientation index of other crystal orientation planes. Here, the other crystal orientation planes are the (111) plane, (200) plane, (220) plane, (311) plane, (331) plane, (422) plane and (511) plane.

In equation (1), I( _hkl ) and I( _hxkylz ) are the measured diffraction intensity of the _{( hkl} ) plane and the measured diffraction of the _{( hxkylz} ) plane, respectively. I ₀ (hkl) and I ₀ (h _x k yl _z ) are TiC (card number: _32-1383 ) and TiN of the (hkl) plane according to the JCPDS (Joint Committee on Powder Diffraction Standards) database, respectively. (Card number: _38-1420 ), and the average powder diffraction intensity of TiC and TiN on the (h _x k yl _z ) plane according to the JCPDS database, (hkl) and (h _x k _y l _z ) are the 8 Show any of the faces.

The orientation index TC (420) of the hard particle layer of the present embodiment is preferably 3.5 or more, more preferably 5 or more, more preferably 6 or more, from the viewpoint of improving hardness and improving wear resistance in tool steel cutting. preferable. Although the upper limit of the value of the orientation index TC (420) is not limited, it may be set to 8 or less because the number of reflecting surfaces used in the calculation is 8. The value of the orientation index TC (420) is preferably 3.5 or more and 8 or less, more preferably 5 or more and 8 or less, and even more preferably 6 or more and 8 or less.

The orientation index TC (420) is determined by XRD measurement under the following conditions. Specifically, X-ray diffraction measurement (apparatus: SmartLab (registered trademark) manufactured by Rigaku Co., Ltd.) is performed on an arbitrary point in the hard particle layer, and the (420) plane obtained based on the above formula (1) is defined as the orientation index TC (420) in the hard particle layer. In selecting the above-mentioned "arbitrary one point", points that seem to show an abnormal value are excluded.

(Conditions for X-ray diffraction measurement)
X-ray output: 45kV, 200mA
X-ray source, wavelength: CuKα, 1.541862 Å
Detector: D/teX Ultra 250
Scan axis: 2θ/θ
Length limiting slit width: 2.0 mm
Scan mode: CONTINUOUS
Scan speed: 20°/min.

As long as the measurement is performed on the same sample, there is almost no variation in the measurement results even if the measurement is performed multiple times by changing the measurement location in the hard particle layer. has been confirmed.

<Other layers>
The coating can contain other layers besides the hard particle layer, as described above. As shown in FIGS. 2 to 4, the other layers include an underlying layer 12, an outermost layer 13, and the like.

(Underlayer)
The underlayer is positioned between the substrate and the hard particle layer. For example, a TiN layer can be used as the underlying layer. By arranging a TiN layer, a TiC layer, a TiCN layer, and a TiBN layer immediately above the substrate as the underlying layer, the adhesion between the substrate and the coating can be enhanced. Also, by using an Al ₂ O ₃ layer as the underlayer, the oxidation resistance of the coating can be enhanced. The average thickness of the underlayer is preferably 0.1 μm or more and 20 μm or less. According to this, the coating can have excellent wear resistance and chipping resistance.

The underlayer can consist of one layer. Further, as shown in FIG. 4, the underlying layer 12 can have a two-layer structure consisting of a first underlying layer 12A and a second underlying layer 12B. When the underlayer has a two-layer structure, it is preferable to combine a TiN layer and a TiCN layer. Since the TiCN layer has excellent wear resistance, it can impart more suitable wear resistance to the coating. The average thickness of the first underlayer is preferably 0.1 μm or more and 20 μm or less, more preferably 0.1 μm or more and 19 μm or less. The average thickness of the second underlayer is preferably 1 μm or more and 20 μm or less, more preferably 1 μm or more and 19.9 μm or less.

(outermost layer)
The outermost layer is a layer arranged on the surface side of the coating. However, it may not be formed at the cutting edge ridge. The outermost layer is arranged directly above the hard particle layer when no other layer is formed on the hard particle layer. The outermost layer is preferably composed mainly of Ti (titanium) carbide, nitride or boride. Also, by using an Al ₂ O ₃ layer as the outermost layer, the oxidation resistance of the coating can be enhanced.

The phrase "mainly composed of Ti carbide, nitride or boride" means containing 90% by mass or more of Ti carbide, nitride or boride. Moreover, it means that it preferably consists of any one of carbide, nitride and boride of Ti except for inevitable impurities.

Among Ti carbides, nitrides, and carbonitrides, it is particularly preferable to form the outermost layer using a Ti nitride (ie, a compound represented by TiN) as a main component. Among these compounds, TiN has the clearest color (exhibits a gold color), so it has the advantage of facilitating identification of the corners of the cutting tip after use for cutting (identification of used portions). The outermost layer is preferably a TiN layer.

The outermost layer preferably has an average thickness of 0.05 μm or more and 1 μm or less. According to this, the adhesion between the outermost layer and the adjacent layers is improved.

<Embodiment 2: Manufacturing method of cutting tool>
An example of the method for manufacturing the cutting tool of this embodiment will be described with reference to FIG. FIG. 8 is a schematic cross-sectional view of an example of a CVD apparatus used for manufacturing the cutting tool of this embodiment.

(Preparation of base material)
Prepare the substrate. The details of the substrate have already been described and will not be repeated.

(Formation of film)
Next, a coating is formed on the substrate using, for example, the CVD apparatus shown in FIG. A plurality of substrate setting jigs 52 holding substrates 10 can be installed in the CVD apparatus 50, and these are covered with a reaction vessel 53 made of heat-resistant alloy steel. A temperature control device 54 is arranged around the reaction container 53 , and the temperature inside the reaction container 53 can be controlled by the temperature control device 54 .

An introduction pipe 56 having two introduction ports 55 and 57 is arranged in the CVD apparatus 50 . The introduction pipe 56 is arranged so as to pass through a region where the base material setting jig 52 is arranged, and a plurality of through holes are formed in a portion near the base material setting jig 52 . In the introduction pipe 56 , the gases introduced into the pipe from the introduction ports 55 and 57 are introduced into the reaction vessel 53 through different through-holes without being mixed in the introduction pipe 56 . This introduction tube 56 can rotate around its axis. An exhaust pipe 59 is arranged in the CVD apparatus 50 , and the exhaust gas can be discharged to the outside from an exhaust port 60 of the exhaust pipe 59 . The jigs and the like in the reaction vessel 53 are generally made of graphite.

When the coating includes an underlayer and/or an outermost layer, these layers can be formed by conventionally known methods.

The hard particle layer can be formed by the following method using the above CVD apparatus. Specifically, a first raw material gas containing Ti and Si is introduced from the inlet 55 into the inlet pipe 56 , and a second raw material gas containing C and N is introduced from the inlet 57 into the inlet pipe 56 . The first source gas can include, for example, _TiCl4 gas and _SiCl4 gas. The second source gas can contain, for example, CH ₃ CN gas. Note that each of the first source gas and the second source gas can contain a carrier gas (H ₂ gas, N ₂ gas, Ar gas, or the like). Hereinafter, the total of the first raw material gas and the second raw material gas in the reaction vessel is referred to as reaction gas.

A plurality of through holes are opened on the upper side of the introduction pipe 56 in the figure. The introduced first raw material gas (or first mixed gas consisting of first raw material gas and carrier gas) and second raw material gas (or second mixed gas consisting of second raw material gas and carrier gas) are different from each other. It is ejected into the reaction container 53 from the through hole. At this time, the introduction tube 56 rotates about its axis as indicated by the rotating arrow in the figure. Therefore, the first raw material gas (or first mixed gas) and the second raw material gas (or second mixed gas) are uniformly mixed as a mixed gas, and the substrate 10 set on the substrate setting jig 52 is jetted toward the surface of

During the formation of the hard particle layer, the total gas flow rate of the reactant gas can be, for example, 10-80 L/min. Here, the "total gas flow rate" indicates the total volumetric flow rate introduced into the CVD furnace per unit time, assuming that the gas under standard conditions (0° C., 1 atm) is an ideal gas.

The ratio of TiCl ₄ gas and CH ₃ CN gas in the reaction gas is always constant during the formation of the hard particle layer. The proportion of TiCl ₄ gas in the reaction gas can be, for example, 0.4-1.0% by volume. The proportion of CH ₃ CN gas in the reaction gas can be, for example, 0.5-0.85% by volume. More preferably, the proportion of CH ₃ CN gas in the reaction gas is 0.63 to 0.85% by volume. By adjusting the ratio of the CH ₃ CN gas and the pressure inside the reaction vessel 53, which will be described later, the hard particle layer can be oriented in the (420) orientation. The CH ₃ CN gas flow rate obtained by the above CH ₃ CN gas ratio is greater than that employed in conventional TiSiCN layer formation, and the pressure in reaction vessel 53 is higher than that employed in conventional TiSiCN layer formation. lower than it was.

The ratio of _SiCl4 gas in the reaction gas is periodically changed by adjusting the introduction amount of _SiCl4 gas. Specifically, the length of one cycle of change in the introduction amount of SiCl ₄ gas is t (seconds), and the range of change in the proportion of SiCl ₄ gas in the reaction gas is r1 (% by volume) to r2 (% by volume). ), the ratio of SiCl ₄ gas gradually increases from r1 (volume %) to r2 (volume %) from the start of film formation to the middle point of one cycle (t/2 (seconds)), followed by From the middle point (t/2 (seconds)) to the final point (t (seconds)) of one cycle, SiCl ₄ gas is gradually reduced from r2 (vol%) to r1 ( _vol %). Adjust the amount of gas introduced. This cycle is repeated until the hard particle layer reaches a desired thickness. The proportion of carrier gas ₍ e.g., H2 gas) in the reaction gas varies with the change in the proportion of _SiCl4 gas such that the total gas flow remains constant. By adjusting the length t (seconds) of one period, the period width (nm) of the concentration of silicon in the hard particles can be controlled. The value of A _Si /(A _Si +A _Ti ) in the hard particles can be controlled by adjusting the minimum value r1 and the maximum value r2 of the ratio range of SiCl ₄ gas in the reaction gas.

In this step, the temperature of the substrate 10 is preferably in the range of 750 to 900° C., and the pressure inside the reaction vessel 53 is preferably in the range of 0.1 to 13 kPa. The thickness of the hard particle layer can be controlled by adjusting the flow rate of the raw material gas and the film formation time.

Next, the base material 10 with the film formed thereon is cooled. The cooling rate does not exceed, for example, 5° C./min, and the cooling rate slows as the temperature of the substrate 10 decreases.

In addition to the above steps, a heat treatment step such as annealing, and a surface treatment step such as surface grinding and shot blasting can be performed.

The cutting tool of Embodiment 1 can be obtained by the manufacturing method described above.

EXAMPLES This embodiment will be described in more detail with reference to Examples. However, this embodiment is not limited by these examples.

<Preparation of base material>
Base material K, base material L and base material M shown in Table 1 below were prepared. Specifically, first, raw material powders having the composition (% by mass) shown in Table 1 were uniformly mixed to obtain a mixed powder. "Remainder" in Table 1 indicates that WC accounts for the remainder of the composition (% by mass). Next, after pressure molding the mixed powder into the shape of CNMG120408 (exchangeable cutting tip manufactured by Sumitomo Electric Hardmetal Co., Ltd.), it is sintered at 1300 to 1500 ° C. for 1 to 2 hours to obtain a cemented carbide product. Base material K, base material L and base material M were obtained. Base material K, base material L and base material M all have a base material shape of CNMG120408.

<Formation of film>
A film was formed on the surface of the base material K, base material L, or base material M obtained above. Specifically, using the CVD apparatus shown in FIG. 8, the substrate was set in a substrate setting jig, and a thermal CVD method was performed to form a film on the substrate. Table 2 shows the composition of the coating of each sample.

In Table 2, the base layer is a layer that is in direct contact with the surface of the base material, the hard particle layer is a layer formed on the base layer, and the outermost layer is a layer formed on the hard particle layer and is attached to the outside. This is the exposed layer. In addition, the descriptions of the compounds in the underlayer column and the outermost layer column in Table 2 are the compounds constituting the underlayer and outermost layer in Table 2, and the numbers in parentheses on the right side of the compounds mean the thickness of the layer. there is Also, when two compounds (for example, "TiN (0.5)-TiCN (3.0)") are described in one column of Table 2, the left side ("TiN (0.5) ”) means that the compound is a layer located on the side closer to the substrate, and the compound on the right side (“TiCN (3.0)”) is a layer located on the far side from the substrate. The numbers in parentheses indicate the thickness of each layer. The descriptions of a to p and w to z of the hard particle layer in Table 2 indicate that the layers are formed under the formation conditions a to p and the formation conditions w to z in Table 4. The numbers refer to layer thicknesses. In addition, the column indicated by "-" in Table 2 means that no layer exists.

For example, in the cutting tool of Sample 1 in Table 2, a TiN layer with a thickness of 0.5 μm and a TiCN layer with a thickness of 3.0 μm are laminated in this order on the surface of the base material L to form a base layer. , A hard particle layer having a thickness of 6.0 μm formed under the formation condition a described later is formed thereon, and a coating having no outermost layer is formed on the hard particle layer, and the entire coating thickness is 9.5 μm.

The underlying layer and the outermost layer shown in Table 2 are layers formed by a conventionally known CVD method, and the formation conditions are as shown in Table 3. For example, the row of "TiN (underlying layer)" in Table 3 shows conditions for forming a TiN layer as an underlying layer. The description of the TiN layer (underlying layer) in Table 3 is that the substrate is placed in the reaction vessel of the CVD apparatus (reaction vessel internal pressure 6.7 kPa), the substrate is heated to a substrate temperature of 915 ° C., and the inside of the reaction vessel is by ejecting a mixed gas consisting of _2.0 vol% _TiCl4 gas, 39.7 vol% _N2 gas and the rest (58.3 vol%) H2 gas at a flow rate of 63.8 L/min into the meant to be formed. In addition, the thickness of each layer was controlled by the time during which each reaction gas was ejected.

The hard particle layer shown in Table 2 is formed under any one of formation conditions a to p and formation conditions w to z shown in Table 4.

(Formation condition a to formation condition p, and formation condition z)
In formation conditions a to formation conditions p and formation conditions z, first, the pressure inside the reaction vessel of the CVD apparatus was set to the pressure described in the column "Internal pressure of reaction vessel (kPa)" in Table 4, and the substrate temperature. Set to the temperature described in the column of "Substrate temperature (°C)" in Table 4. For example, in the formation condition a, the pressure inside the reaction vessel of the CVD apparatus is set to 4.5 kPa, and the substrate temperature is set to 850.degree.

Next, a reaction gas containing the components listed in the "Reaction gas composition (% by volume)" column of Table 4 is introduced into the reaction vessel to form a hard particle layer (TiSiCN layer) on the substrate. The total gas flow rate of the reaction gas is as shown in Table 4, "total gas flow rate (L/min)" column. "Total gas flow rate" indicates the total volumetric flow rate introduced into the CVD furnace per unit time, assuming that the gas under standard conditions (0° C., 1 atm) is an ideal gas.

The proportions of _TiCl4 gas, _CH3CN gas and _N2 gas in the reaction gas are always constant during the formation of the hard particle layer. The ratio of SiCl ₄ gas in the reaction gas changes within the ratio (% by volume) shown in the “Range” column, with the time (seconds) shown in the “Cycle” column of “SiCl ₄ ” in Table 4 as one cycle. Let Specifically, the ratio of SiCl ₄ gas at the start of film formation was set to the minimum value shown in the “Range” column, and the middle point (1 period/2 (seconds)), the proportion of _SiCl4 gas is gradually increased to the maximum value indicated in the "Range" column, followed by an intermediate time point (1 cycle/2 (seconds)) to the final time point of one cycle ( Up to one cycle (seconds), adjust the SiCl ₄ gas introduction rate so that the percentage of SiCl ₄ gas tapers off to the minimum value indicated in the "Range" column. This cycle is repeated until the hard particle layer reaches a desired thickness. The proportion of H2 gas is varied so that the _total gas flow rate remains constant as the proportion of _SiCl4 gas is varied.

For example, under formation condition a, the total gas flow rate of the reaction gas is 60.0 L/min. The proportion of _TiCl4 gas in the reaction gas is 0.70 vol%, the proportion of _CH3CN gas is 0.75 vol%, the proportion of _N2 gas is 8.90 vol%, and the proportion of these gases is hard constant during the formation of the particle layer. The ratio of SiCl ₄ gas in the reaction gas is varied in the range of 0.1 to 1.7% by volume with 7 seconds as one cycle. More specifically, the ratio of SiCl ₄ gas at the start of film formation is 0.1 vol%, and the ratio of SiCl ₄ gas is changed from 0.1 vol% to 1.7 vol% for 3.5 seconds from the start of film formation. SiCl ₄ gas was gradually increased to _vol % and then gradually decreased from 1.7 vol% to 0.1 vol% from 3.5 seconds to 7 seconds after the start of film formation. Adjust the amount of introduction of This is regarded as one cycle, and this cycle is repeated until the thickness of the hard particle layer reaches the thickness described in the "Hard particle layer" column of Table 1. The volume fraction of H2 gas is varied so that the _total gas flow rate remains constant according to the variation of the _SiCl4 gas fraction. In formation condition a, the average proportion of _SiCl4 gas in the reaction gas is 0.90 vol%.

The substrate is then cooled at a cooling rate of 5°C/min.

(Formation condition w)
A formation condition w is a conventional TiCN layer formation condition. Specifically, first, the pressure inside the reaction vessel of the CVD apparatus is set to 4.5 kPa, and the substrate temperature is set to 850.degree.

Next, a reaction gas (TiCl ₄ : 2.00% by volume, CH ₃ CN: 0.75% by volume, H ₂ gas: rest) to form a TiCN layer (hard particle layer) on the substrate. The composition of the reaction gas is constant during film formation. The total gas flow rate of the reaction gases is 60 L/min. The substrate is then cooled at a cooling rate of 5°C/min.

(Formation condition x)
The formation condition x is a condition for forming a hard particle layer (TiSiCN layer) using the PVD method disclosed in Patent Document 1.

(Formation condition y)
Formation condition y is a condition for forming a hard particle layer (TiSiCN layer) using the CVD method disclosed in Patent Document 2.

As described above, cutting tools of Samples 1 to 27 (corresponding to Examples) and Samples 1-1 to 1-5 (corresponding to Comparative Examples) were obtained.

<Characteristics of hard particle layer>
(Structure of hard particle layer)
The hard particle layer obtained under the forming conditions a to p and the forming condition z is composed of a plurality of hard particles made of TiSiCN, and along the first direction set in the hard particles, the concentration of silicon is It was confirmed that it changed periodically. Since a specific confirmation method is described in Embodiment 1, the description thereof will not be repeated.

When the hard particle (TiCN) layer obtained under formation condition w was observed with a bright-field transmission electron microscope (BF-STEM), the structure was uniform and no periodic change was confirmed.

When the hard particle layers obtained under formation conditions x and y were observed with a bright-field transmission electron microscope (BF-STEM), a nanocomposite structure was confirmed. The hard particle layer was (200) oriented.

({A _Si /(A _Si +A _Ti )}×100)
The maximum, minimum and average values of {A _Si /(A _Si +A _Ti )}×100 were measured for the hard particles obtained under each formation condition. Since the specific measuring method is as described in Embodiment 1, the description thereof will not be repeated. The results are shown in Table 5 as “maximum {A _Si / (A _Si + A _Ti )} × 100 (%)”, “minimum {A _Si / (A _Si + A _Ti )} × 100 (%)” and “average {A _Si /(A _Si +A _Ti ) (%)” column. The notation of "-" indicates that no measurement was performed.

(periodic width of silicon concentration)
For the hard particles obtained under each formation condition, the average period width of the silicon concentration in the first direction set in the hard particles was measured. Since the specific measuring method is as described in Embodiment 1, the description thereof will not be repeated. The results are shown in the "Average Periodic Width (nm)" column of Table 5. The notation of "-" indicates that no measurement was performed.

(orientation)
The orientation of the hard particle layer obtained under each formation condition was measured. A specific method for measuring the orientation of the hard particle layer is described in Embodiment 1, so description thereof will not be repeated. In each hard particle layer, among the orientation indices TC (hkl), the orientation plane with the largest orientation index is shown in the "orientation plane" column of Table 5, and the orientation index TC (hkl) of the orientation plane is indicated as " Orientation Index TC (hkl) of Oriented Surface” column.

In the hard particle layers obtained under formation conditions a to p and w, the (420) plane had the largest orientation index TC(420). Therefore, the orientation of the hard particle layers obtained under formation conditions a to p and w was (420) orientation. For example, the orientation index TC (420) of the hard particle layer obtained under the forming condition a was 4.4.

In the hard particle layers obtained under forming conditions x to z, the orientation index TC(200) of the (200) plane was the largest. Therefore, the orientation of the hard particle layer obtained under formation conditions x to z was (200) orientation.

<Cutting test 1>
Using the cutting tools of Samples 1 to 27 and Samples 1-1 to 1-5, continuous cutting of tool steel (SKD11) was performed under the following cutting conditions, and the flank wear amount (Vb) was 0.3 mm. The cutting time was measured until it became A longer cutting time indicates better wear resistance and longer tool life. Also, the final damage morphology of the cutting edge was observed. In the final damage morphology, "normal wear" means a damage morphology consisting only of wear (having a smooth worn surface) without causing chipping, chipping, etc., and indicates excellent chipping resistance. Table 6 shows the results.

<Cutting conditions>
Work material: SKD11 round bar circumference cutting Peripheral speed: 100m/min
Feed rate: 0.15mm/rev
Cutting depth: 1.0mm
Cutting Fluid: None.

(Evaluation 1)
It was confirmed that Sample 1-Sample 27 (Example) is superior in wear resistance in continuous cutting of tool steel and has a longer tool life than Sample 1-1 through Sample 1-5 (Comparative Example). In addition, it was confirmed that Sample 1-Sample 27 had normal wear as the final damage type and maintained excellent fracture resistance equivalent to that of conventional hard particle layers (Samples 1-1 to 1-5). was done.

<Cutting test 2>
Using the cutting tools of Samples 1 to 27 and Samples 1-1 to 1-5, intermittent cutting of tool steel (SK5) was performed under the following cutting conditions, and the number of impacts until the cutting tool fractured was measured. , the chipping resistance of the cutting tool was evaluated. Here, a defect means a defect of 300 μm or more. The greater the number of impacts until fracture, the better the fracture resistance. Table 7 shows the results. In Table 7, "no chipping" means that cutting was performed up to 2000 impacts, but no chipping occurred.

<Cutting conditions>
Work material: SK5 plate peripheral cutting Peripheral speed: 100m/min
Feed rate: 0.15mm/rev
Cutting depth: 1.5mm
Cutting Fluid: None.

(Evaluation 2)
It was confirmed that Sample 1-Sample 27 (Example) is superior in chipping resistance in interrupted cutting of tool steel and has a longer tool life than Sample 1-1 through Sample 1-5 (Comparative Example).

Although the embodiments and examples of the present disclosure have been described as above, it is planned from the beginning to appropriately combine the configurations of the above-described embodiments and examples and to modify them in various ways.

The embodiments and examples disclosed this time are illustrative in all respects and should not be considered restrictive. The scope of the present invention is indicated by the scope of the claims rather than the above-described embodiments and examples, and is intended to include meanings equivalent to the scope of the claims and all modifications within the scope.

Reference Signs List 1, 21, 31, 41 Cutting tool 10 Base material 11 Hard particle layer 12, 12A, 12B Base layer 13 Outermost layer 14, 24, 34, 45 Coating 50 CVD device 52 Base material setting jig 53 Reaction vessel 54 Temperature control device 55, 57 Inlet 56 Inlet pipe 59 Exhaust pipe 60 Exhaust port

Claims (5)

A cutting tool comprising a substrate and a coating disposed on the substrate,
The coating comprises a hard particle layer,
The hard particle layer consists of a plurality of hard particles containing titanium, silicon, carbon and nitrogen,
In the hard particles, the concentration of the silicon periodically changes along a first direction set in the hard particles,
The cutting tool, wherein the orientation of the hard particle layer is (420) orientation. In the hard particles, the average of the percentage {A _Si /(A _Si +A _Ti )}×100 of the number of silicon atoms A _Si to the sum of the number of titanium atoms A _Ti and the number A _Si of silicon atoms is 1% or more and 20% or less,
The cutting tool according to claim 1. The cutting tool according to claim 1 or 2, wherein the average period width of the concentration of silicon is 3 nm or more and 50 nm or less. The cutting tool according to any one of claims 1 to 3, wherein the hard particle layer has a thickness of 1 µm or more and 20 µm or less. The base material is made of a cemented carbide containing tungsten carbide and cobalt,
The cutting tool according to any one of claims 1 to 4, wherein the cobalt content in the cemented carbide is 6% by mass or more and 11% by mass or less.

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