Coated tools and cutting tools

Abstract

The coated tool of the present invention has a substrate and a coating. The substrate contains a plurality of boron nitride particles. The coating is located on the substrate. In addition, when the hardness is measured by changing the indentation load of the indenter from the surface of the coating and pressing the indenter to a depth of 20% of the coating, the maximum hardness difference, which is the difference between the maximum hardness and the minimum hardness in the hardness, is 4 GPa or more.

Description

Technical Field

[0001] The invention relates to a coated tool and a cutting tool. Background Art

[0002] As a tool used for cutting such as turning and milling, there is known a coated tool in which the surface of a substrate such as cemented carbide, cermet, or ceramic is coated with a coating film to improve wear resistance and the like (see Patent Document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent No. 5160231 Summary of the invention

[0006] In a coated tool of one embodiment of the present invention, the coated tool of the present invention has a substrate and a coating. The substrate contains a plurality of boron nitride particles. The coating is located on the substrate. In addition, when the hardness is measured from the surface of the coating while changing the indentation load of the indenter and pressing the indenter to a depth of 20% of the coating, the maximum hardness difference, which is the difference between the maximum hardness and the minimum hardness in the hardness, is 4 GPa or more. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a perspective view showing an example of a coated tool according to the embodiment.

[0008] Figure 2 It is a side cross-sectional view showing an example of a coated tool according to the embodiment.

[0009] Figure 3 This is a cross-sectional view showing an example of a coating layer according to an embodiment.

[0010] Figure 4 yes Figure 3 A schematic enlarged view of section H is shown.

[0011] Figure 5 This is a front view showing an example of a cutting tool according to an embodiment.

[0012] Figure 6 This is a table showing the composition of each sample.

[0013] Figure 7 This is a table showing the results of the indentation hardness test on cBN without a metal layer and cBN with a metal layer.

[0014] Figure 8 It is a graph showing the results of an indentation hardness test on cBN without a metal layer and cBN with a metal layer.

[0015] Fig. 9This is a graph showing changes in the residual stress of the coating layer when the film thickness of the metal layer is changed.

[0016] Fig.10 This is a table showing the results of scratch tests and peel tests on cBN without a metal layer and cBN with a metal layer. DETAILED DESCRIPTION

[0017] Hereinafter, the method for implementing the coated tool and the cutting tool of the present invention (hereinafter, described as "embodiment") will be described in detail with reference to the accompanying drawings. In addition, the coated tool and the cutting tool of the present invention are not limited to this embodiment. In addition, each embodiment can be appropriately combined within the scope that the processing content does not conflict. In addition, in each of the following embodiments, the same symbol is added to the same part, and repeated description is omitted.

[0018] In addition, in the embodiments shown below, there are cases where expressions such as "certain", "orthogonal", "perpendicular" or "parallel" are used, but these expressions do not need to be "certain", "orthogonal", "perpendicular" or "parallel" in a strict sense. That is, the above expressions allow for deviations in, for example, manufacturing accuracy and setting accuracy.

[0019] In the above-mentioned prior art, there is room for further improvement in improving the bonding between the coating and the substrate.

[0020] The present invention has been proposed in view of the above circumstances, and provides a coated tool and a cutting tool capable of improving the bonding between a coating and a substrate.

[0021] <Coated tools>

[0022] Figure 1 1 is a perspective view showing an example of a coated tool according to an embodiment of the present invention. Figure 1 As shown, the coated tool 1 of the embodiment has a blade body 2 and a cutting edge portion 3. In the embodiment, the coated tool 1, for example, has an upper surface and a lower surface (with Figure 1 The shape of the surface (the surface intersecting the Z axis shown) is a hexahedral shape of a parallelogram.

[0023] (Blade body 2)

[0024] The blade body 2 is formed of, for example, cemented carbide. Cemented carbide contains W (tungsten), specifically WC (tungsten carbide). In addition, cemented carbide may also contain Ni (nickel) and Co (cobalt). In addition, the blade body 2 may also be formed of cermet. Cermet, for example, contains Ti (titanium), specifically TiC (titanium carbide) or TiN (titanium nitride). In addition, cermet may also contain Ni or Co.

[0025] A support surface 4 for mounting the cutting edge 3 is provided at the corner of the blade body 2. In addition, a through hole 5 is provided in the center of the blade body 2, which passes through the blade body 2 from top to bottom. A bolt 75 (see FIG. 1 ) for mounting the coated tool 1 on the tool holder 70 described later is inserted into the through hole 5. Figure 5 ).

[0026] (Cutting edge 3)

[0027] The cutting edge portion 3 is integrated with the insert body 2 by being mounted on the support surface 4 of the insert body 2 .

[0028] The cutting edge portion 3 has a first surface 6 (here, the upper surface) and a second surface 7 (here, the side surface) continuous with the first surface 6. In the embodiment, the first surface 6 functions as a "front face" for scraping off chips generated by cutting, and the second surface 7 functions as a "flank face". The cutting edge 8 is located at least a portion of the ridgeline where the first surface 6 and the second surface 7 intersect, and the coated tool 1 cuts the workpiece by contacting the workpiece with the cutting edge 8.

[0029] Reference Figure 2 , the structure of the cutting edge portion 3 is described. Figure 2 1 is a side sectional view showing an example of a coated tool according to an embodiment of the present invention. Figure 2 As shown, the cutting edge portion 3 has a base body 10 and a coating 20 .

[0030] (Substrate 10)

[0031] The substrate 10 contains a plurality of boron nitride particles. In the embodiment, the substrate 10 is a cubic boron nitride (cBN) sintered body, containing a plurality of cubic boron nitride particles. In addition, in the embodiment, the substrate 10 may also have a binding phase containing TiN, Al, Al2O3, etc. between the plurality of boron nitride particles. The plurality of boron nitride particles are firmly bonded by such a binding phase. In addition, the substrate 10 does not necessarily have to have a binding phase.

[0032] A substrate 30, for example, formed of cemented carbide or cermet, may also be provided on the lower surface of the matrix 10. In this case, the matrix 10 is bonded to the support surface 4 of the blade body 2 via the substrate 30 and the bonding material 40. The bonding material 40 is, for example, brazing material. In the portion other than the support surface 4 of the blade body 2, the matrix 10 may also be bonded to the blade body 2 via the bonding material 40.

[0033] (Coating 20)

[0034] The coating layer 20 is applied to the substrate 10 for the purpose of improving the wear resistance and heat resistance of the cutting edge 3. Figure 2In the example of , the coating 20 covers the blade body 2 and the cutting edge 3 as a whole. The coating 20 only needs to be located at least on the substrate 10. When the coating 20 is located on the upper surface of the substrate 10 corresponding to the first surface 6 of the cutting edge 3, the wear resistance and heat resistance of the first surface 6 are high. When the coating 20 is located on the side surface of the substrate 10 corresponding to the second surface 7 of the cutting edge 3, the wear resistance and heat resistance of the second surface 7 are high.

[0035] Here, refer to Figure 3 , the specific structure of the coating layer 20 is described. Figure 3 It is a cross-sectional view showing an example of the coating layer 20 according to the embodiment.

[0036] like Figure 3 As shown, the coating 20 has a hard layer 21. The hard layer 21 is a layer having better wear resistance than the metal layer 22 described later. The hard layer 21 has one or more metal nitride layers. The hard layer 21 may also be a single layer. Figure 3 In addition, the hard layer 21 may include a stacked portion 23 in which a plurality of metal nitride layers are stacked, and a third metal nitride layer 24 located on the stacked portion 23. The structure of the hard layer 21 will be described later.

[0037] (Metal layer 22)

[0038] In addition, the coating layer 20 has a metal layer 22. The metal layer 22 is located between the substrate 10 and the hard layer 21. Specifically, the metal layer 22 is in contact with the upper surface of the substrate 10 on one side (here, the lower surface), and is in contact with the lower surface of the hard layer 21 on the other side (here, the upper surface).

[0039] The metal layer 22 has a higher bonding property with the substrate 10 than the hard layer 21. Examples of metal elements having such properties include Zr, V, Cr, W, Al, Si, and Y. The metal layer 22 contains at least one of the above metal elements.

[0040] In addition, Ti, Zr, V, Cr, and Al are not used as the metal layer 22. This is because they all have low melting points and low oxidation resistance, so they are not suitable for use on cutting tools. In addition, Hf, Nb, Ta, and Mo have low bonding properties with the substrate 10. However, in the alloy containing Ti, Zr, V, Cr, Ta, Nb, Hf, and Al, there is no such limitation.

[0041] The metal layer 22 may be an Al—Cr alloy layer containing an Al—Cr alloy. Since such a metal layer 22 has particularly high bonding properties with the substrate 10 , it has a high effect of improving bonding properties between the substrate 10 and the coating layer 20 .

[0042] When the metal layer 22 is an Al-Cr alloy layer, the content of Al in the metal layer 22 may be greater than the content of Cr in the metal layer 22. For example, the composition ratio (atomic %) of Al to Cr in the metal layer 22 may be 70:30. By achieving such a composition ratio, the bonding between the substrate 10 and the metal layer 22 is higher.

[0043] The metal layer 22 may contain components other than the above-mentioned metal elements (Zr, V, Cr, W, Al, Si, Y). However, from the viewpoint of bonding with the substrate 10, the metal layer 22 may contain the above-mentioned metal elements in a total amount of at least 95 atomic %. More preferably, the metal layer 22 contains the above-mentioned metal elements in a total amount of at least 98 atomic %. For example, when the metal layer 22 is an Al-Cr alloy layer, the metal layer 22 may contain at least Al and Cr in a total amount of at least 95 atomic %. In addition, the metal layer 22 may also contain at least Al and Cr in a total amount of at least 98 atomic %. In addition, the proportion of metal components in the metal layer 22 can be determined, for example, by analysis using EDS (energy dispersive radiation spectrometer).

[0044] In addition, since Ti has poor wettability with the substrate 10 in the embodiment, the metal layer 22 preferably contains as little Ti as possible from the viewpoint of improving bonding with the substrate 10. Specifically, the content of Ti in the metal layer 22 is preferably 15 atomic % or less.

[0045] Thus, in the coated tool 1 of the embodiment, the metal layer 22 having higher wettability with the substrate 10 than the hard layer 21 is provided between the substrate 10 and the hard layer 21, so that the bonding between the substrate 10 and the coating 20 can be improved. In addition, since the bonding between the metal layer 22 and the hard layer 21 is also high, it is also difficult for the hard layer 21 to peel off from the metal layer 22.

[0046] In addition, cBN used as the substrate 10 is an insulator, and there is room for improvement in the bonding between cBN as an insulator and a film formed by PVD (physical vapor deposition). In contrast, in the coated tool 1 of the embodiment, by providing a conductive metal layer 22 on the surface of the substrate 10, the bonding between the hard layer 21 formed by PVD and the metal layer 22 is high.

[0047] (Hard layer 21)

[0048] Next, refer to Figure 4 The structure of the hard layer 21 will be described. Figure 4 yes Figure 3 A schematic enlarged view of section H is shown.

[0049] like Figure 4As shown, the hard layer 21 includes a stacked portion 23 located on the metal layer 22 , and a third metal nitride layer 24 located on the stacked portion 23 .

[0050] The laminated portion 23 includes a plurality of first metal nitride layers 23a and a plurality of second metal nitride layers 23b. The laminated portion 23 has a structure in which the first metal nitride layers 23a and the second metal nitride layers 23b are alternately laminated.

[0051] The thickness of the first metal nitride layer 23a and the second metal nitride layer 23b is 50 nm or less, respectively. Thus, by forming the first metal nitride layer 23a and the second metal nitride layer 23b thin, the residual stress of the first metal nitride layer 23a and the second metal nitride layer 23b is small. Thus, for example, the first metal nitride layer 23a and the second metal nitride layer 23b are unlikely to peel off or crack, and thus the durability of the coating layer 20 is high.

[0052] The first metal nitride layer 23 a is a layer in contact with the metal layer 22 , and the second metal nitride layer 23 b is formed on the first metal nitride layer 23 a .

[0053] The first metal nitride layer 23 a and the second metal nitride layer 23 b may contain the metal included in the metal layer 22 .

[0054] For example, the metal layer 22 contains two kinds of metals (herein, "first metal" and "second metal"). In this case, the first metal nitride layer 23a contains nitrides of the first metal and the third metal. The third metal is a metal not contained in the metal layer 22. In addition, the second metal nitride layer 23b contains nitrides of the first metal and the second metal.

[0055] For example, in the embodiment, the metal layer 22 may contain Al and Cr. In this case, the first metal nitride layer 23a may also contain Al. Specifically, the first metal nitride layer 23a may be an AlTiN layer containing AlTiN which is a nitride of Al and Ti. In addition, the second metal nitride layer 23b may be an AlCrN layer containing AlCrN which is a nitride of Al and Cr.

[0056] Thus, the first metal nitride layer 23a containing the metal contained in the metal layer 22 is located on the metal layer 22, so that the metal layer 22 and the hard layer 21 have high bonding properties. Therefore, since the hard layer 21 is difficult to be peeled off from the metal layer 22, the durability of the coating layer 20 is high.

[0057] The first metal nitride layer 23a, i.e., the AlTiN layer, has excellent wear resistance, for example, in addition to its bonding property with the above-mentioned metal layer 22. In addition, the second metal nitride layer 23b, i.e., the AlCrN layer, has excellent heat resistance and oxidation resistance, for example. In this way, the coating 20 includes the first metal nitride layer 23a and the second metal nitride layer 23b having different compositions, so that the properties such as wear resistance and heat resistance of the hard layer 21 can be controlled. Thus, the tool life of the coated tool 1 can be extended. For example, in the hard layer 21 of the embodiment, the heat resistance possessed by AlCrN can be maintained, and mechanical properties such as bonding property and wear resistance with the metal layer 22 can be improved.

[0058] Furthermore, the laminated portion 23 may be formed by, for example, an arc ion plating method (AIP method). The AIP method is a method of forming a metal nitride (here, AlTiN and AlCrN) by evaporating a target metal (here, an AlTi target and an AlCr target) and combining it with N2 in a vacuum atmosphere by arc discharge. Furthermore, the metal layer 22 may also be formed by the AIP method.

[0059] The third metal nitride layer 24 may be located on the stacked portion 23. Specifically, the third metal nitride layer 24 is in contact with the second metal nitride layer 23b in the stacked portion 23. The third metal nitride layer 24 is, for example, a metal nitride layer (AlTiN layer) containing Ti and Al, similarly to the first metal nitride layer 23a.

[0060] The thickness of the third metal nitride layer 24 may be thicker than the thickness of the first metal nitride layer 23a and the second metal nitride layer 23b. Specifically, when the thickness of the first metal nitride layer 23a and the second metal nitride layer 23b is 50 nm or less, the thickness of the third metal nitride layer 24 may be 1 μm or more. For example, the thickness of the third metal nitride layer 24 may be 1.2 μm.

[0061] Thus, for example, when the friction coefficient of the third metal nitride layer 24 is low, the anti-sticking property of the coated tool 1 can be improved. Also, for example, when the hardness of the third metal nitride layer 24 is high, the wear resistance of the coated tool 1 can be improved. Also, for example, when the oxidation start temperature of the third metal nitride layer 24 is high, the oxidation resistance of the coated tool 1 can be improved.

[0062] In addition, the thickness of the third metal nitride layer 24 may be thicker than the thickness of the laminated portion 23. Specifically, in the embodiment, when the thickness of the laminated portion 23 is 0.5 μm or less, the thickness of the third metal nitride layer 24 may be 1 μm or more. For example, when the thickness of the laminated portion 23 is 0.3 μm, the thickness of the third metal nitride layer 24 may be 1.2 μm. In this way, by making the third metal nitride layer 24 thicker than the laminated portion 23, the above-mentioned anti-adhesion property, wear resistance, etc. can be improved more.

[0063] The thickness of the metal layer 22 may be, for example, not less than 0.1 μm and less than 0.6 μm. That is, the metal layer 22 may be thicker than the first metal nitride layer 23 a and the second metal nitride layer 23 b and thinner than the stacked portion 23 .

[0064] <Cutting tools>

[0065] Next, refer to Figure 5 , the structure of a cutting tool including the coated tool 1 will be described. Figure 5 This is a front view showing an example of a cutting tool according to an embodiment.

[0066] like Figure 5 As shown, a cutting tool 100 according to the embodiment includes a coated tool 1 and a tool holder 70 for fixing the coated tool 1 .

[0067] The handle 70 is from the first end ( Figure 5 ) toward the second end ( Figure 5 The handle 70 is made of, for example, steel or cast iron. Among these components, it is particularly preferred to use steel with high toughness.

[0068] The tool holder 70 has a slot 73 at the end of the first end. The slot 73 is a portion for mounting the coated tool 1, and has a support surface intersecting the rotation direction of the cut material and a limiting side surface inclined relative to the support surface. A threaded hole for tightening a bolt 75 described later is provided on the support surface.

[0069] The coated tool 1 is located in the slot 73 of the tool holder 70 and is mounted on the tool holder 70 by means of a bolt 75. That is, the bolt 75 is inserted into the through hole 5 of the coated tool 1, and the front end of the bolt 75 is inserted into the bolt hole formed on the support surface of the slot 73 to tighten the threaded parts. Figure 1 ) is mounted on the shank 70 in a manner that protrudes outward from the shank 70.

[0070] In the embodiment, the example is a cutting tool for so-called turning. As turning, for example, inner diameter processing, outer diameter processing and slotting processing can be listed. In addition, the cutting tool is not limited to turning. For example, the cutting tool for milling can also use the coated tool 1.

[0071] For example, the cutting process of the workpiece includes: (1) a step of rotating the workpiece; (2) a step of bringing the cutting edge 8 of the coated tool 1 into contact with the rotating workpiece to cut the workpiece; and (3) a step of separating the coated tool 1 from the workpiece. Representative examples of the material of the workpiece include carbon steel, alloy steel, stainless steel, cast iron, or nonferrous metals.

[0072] (Example 1: Indentation hardness test)

[0073] The inventors of the present application conducted an indentation hardness test on a sample having a coating formed on a substrate containing boron nitride particles. The substrate is formed of a plurality of cubic boron nitride particles and a binder phase containing TiN. The substrate contains about 25% by volume of the binder phase.

[0074] The samples were of the following two types.

[0075] (1) Sample in which a coating layer having a metal layer is formed on cBN (hereinafter referred to as "cBN having a metal layer")

[0076] (2) Sample in which a coating layer without a metal layer is formed on cBN (hereinafter referred to as “cBN without a metal layer”)

[0077] Reference Figure 6 , the specific composition of each sample is described. Figure 6 This is a table showing the composition of each sample.

[0078] like Figure 6 As shown, there is a metal layer cBN, and a coating layer formed of a metal layer and a hard layer is provided on a substrate formed of cBN. Specifically, a metal layer is provided on a substrate, and a hard layer is provided on the metal layer. On the other hand, there is no metal layer cBN, and a coating layer formed of a hard layer is provided on a substrate formed of cBN.

[0079] The metal layer of cBN contains Al and Cr. The specific composition of such a metal layer is Al 70 Cr 30 That is, the metal layer contains 70 atomic % of Al and 30 atomic % of Cr. In addition, the thickness of the metal layer is 0.2 μm.

[0080] The hard layer of cBN with a metal layer and cBN without a metal layer comprises a first metal nitride layer, a second metal nitride layer and a third metal nitride layer. The first metal nitride layer and the second metal nitride layer are alternately stacked. In addition, the third metal nitride layer is located on the alternately stacked first metal nitride layer and the second metal nitride layer.

[0081] exist Figure 6 The ratio of only metal components in the first metal nitride layer described as TiAlNbWSiN is 42 atomic %, Al is 48 atomic %, Nb is 3 atomic %, W is 4 atomic %, and Si is 3 atomic %. In addition, the first metal nitride layer contains approximately 100 atomic % of N relative to 100 atomic % of the metal components. The thickness of one first metal nitride layer is 50 nm.

[0082] exist Figure 6 The ratio of only the metal components of the second metal nitride layer described as AlCrN in FIG. 1 is 70 atomic % of Al and 30 atomic % of Cr. In addition, the second metal nitride layer contains approximately 100 atomic % of N relative to 100 atomic % of the metal components. The thickness of one second metal nitride layer is 50 nm.

[0083] The total thickness of the plurality of first metal nitride layers and the plurality of second metal nitride layers was 0.5 μm.

[0084] The composition of the third metal nitride layer is the same as that of the first metal nitride layer. The thickness of the third metal nitride layer is 2 μm.

[0085] The results of the indentation hardness test on this sample are shown in Figure 7 and Figure 8 middle. Figure 7 This is a table showing the results of the indentation hardness test on cBN without a metal layer and cBN with a metal layer. Figure 8 2 is a graph showing the results of the same experiment.

[0086] In addition, this test was performed using a micro-indentation hardness tester "ENT-1100b / a" (manufactured by Elionix Corporation).

[0087] Before measuring the hardness, measure the thickness of the coating in a cross section of the substrate that is orthogonal to the surface of the substrate. The thickness of the coating is 2.7 μm when there is a metal layer. When there is no metal layer, the thickness of the coating is 2.5 μm. From the surface of the coating, press the indenter into an amount of 20% of the thickness of the coating. The indenter presses into the coating surface approximately 0.02 μm at a time. This indentation depth can be deepened by increasing the indentation load. In other words, increasing the indentation depth by 0.02 μm at a time is equivalent to increasing the indentation load by approximately 5 mN at a time.

[0088] In this test, if the indenter is pressed to a depth of 20% of the coating thickness, the hardness near the surface of the substrate can be measured basically from the surface of the coating. In the present invention, the so-called hardness of the coating is the hardness obtained by pressing the indenter to a depth of 20% of the coating while changing the indentation load from the surface of the coating. In the indentation hardness test, the deeper the indentation depth, the harder the area deeper from the coating surface can be measured.

[0089] exist Figure 8 In the figure, the blank circles represent the measurement results of cBN with a metal layer, and the black triangles represent the measurement results of cBN without a metal layer. Figure 8 As shown, it can be seen that the cBN with a metal layer has a higher hardness overall than the cBN without a metal layer. This increase in hardness is significant in the area below the indentation depth of 300nm. The hardness below the indentation depth of 300nm represents the hardness of the hard layer. It can be seen that the cBN with a metal layer has a higher hardness than the cBN without a metal layer.

[0090] For this, refer to Fig. 9 Provide explanation. Fig. 9 This is a graph showing changes in the residual stress of the coating layer when the film thickness of the metal layer is changed.

[0091] exist Fig. 9 In the figure, the residual stress of the coating is measured based on the warpage of a stainless steel plate on which a coating having a metal layer is formed. Fig. 9 The results for a film thickness of 0 μm show the residual stress of a coating without a metal layer, that is, a coating with only a hard layer. In addition, the results for film thicknesses of 0.2 μm, 0.4 μm, and 0.6 μm show the residual stress of a coating with a metal layer.

[0092] like Fig. 9 As shown, it can be seen that the residual stress of the coating with a metal layer is higher than that of the coating without a metal layer. The higher the residual stress, the higher the hardness of the coating. Therefore, it can be seen that the hardness of the coating is improved by forming a metal layer.

[0093] As one of the reasons why the residual stress of the coating layer increases under the action of the metal layer, it is believed that there are the following reasons, for example. That is, in PVD coating, a bias is applied to the object to be filmed (cBN, cemented carbide, etc.) to form a metal layer, and more ions are attracted to the object to be filmed when the bias is applied. As a result, it is believed that a large residual stress occurs in the coating layer with a metal layer compared to the coating layer without a metal layer.

[0094] When the thickness of the metal layer was 0.6 μm, peeling of the coating occurred and the residual stress decreased. Based on these results, the thickness of the metal layer is preferably 0.1 μm or more and less than 0.6 μm.

[0095] In addition, if Figure 8 As shown in the figure, the cBN with metal layer has a hardness valley near the indentation depth of 300nm. This is a feature not seen in the cBN without metal layer. As mentioned above, the hardness near the indentation depth of 300nm indicates the hardness of the metal layer. Since the metal layer is softer than the hard layer, it is believed that this hardness valley can be caused.

[0096] exist Figure 6 In the measurement results shown, the difference between the maximum hardness and the minimum hardness of cBN without a metal layer (hereinafter referred to as "maximum hardness difference") is less than 4 GPa, while the maximum hardness difference of cBN with a metal layer is more than 4 GPa. Specifically, the maximum hardness difference of cBN with a metal layer is more than 8 GPa.

[0097] Thus, the coated tool with a maximum hardness difference of 4 GPa or more has a portion with high hardness and a portion with low hardness, and the difference is more than 4 GPa. First, in the case of such a structure, the case where the portion with low hardness is located far from the substrate relative to the portion with high hardness is described. For example, when a large impact is applied to the coated tool by repeated intermittent processing, the portion with low hardness is located closer to the surface of the coated tool relative to the portion with high hardness, so this portion is easy to absorb the impact and is not easy to break.

[0098] Next, the case where the portion with high hardness is located farther from the substrate than the portion with low hardness is described. In this case, continuous processing is performed. That is, the portion with high hardness is located closer to the surface of the coated tool, so the wear resistance is excellent, and the impact is absorbed by the portion with low hardness, so the wear resistance and impact resistance are excellent.

[0099] In addition, the metal layer cBN has the maximum hardness on the surface side of the coating layer. Specifically, the indentation depth of the maximum hardness is smaller than the indentation depth of the minimum hardness.

[0100] Thus, the metal layer cBN has the maximum hardness on the surface side. In other words, by providing the metal layer, the hardness of the coating surface side can be increased. Therefore, the life of the coated tool can be extended.

[0101] Figure 7 Among the results shown, the "maximum hardness" is the maximum value of the hardness in the measurement range (the range from the surface of the coating to 20% of the depth of the coating), and the "minimum hardness" is the minimum value of the hardness in the above measurement range. The "maximum hardness load" is the indentation load of the indenter with the maximum hardness, and the "maximum hardness depth" is the indentation depth of the indenter with the maximum hardness. The "minimum hardness load" is the indentation load of the indenter with the minimum hardness, and the "minimum hardness depth" is the indentation depth of the indenter with the minimum hardness.

[0102] The "maximum hardness difference" is the difference between the maximum hardness and the minimum hardness. The "average hardness" is the average hardness in the measurement range.

[0103] The maximum hardness depth difference, that is, the difference between the maximum hardness depth and the minimum hardness depth of the cBN having the metal layer, may be 180 nm or more and 500 nm or less.

[0104] The maximum hardness depth difference is 180nm or more, in other words, the change in hardness is relatively gentle, and it can be said that the characteristics of the coated tool are unlikely to change drastically. In this case, it is not easy to break. In addition, the maximum hardness depth difference is 500nm or less, which means that the position indicating the maximum hardness is close to the position indicating the minimum hardness. Therefore, the effect is more significant when the maximum hardness difference is 4GPa or more.

[0105] The maximum hardness depth of the metal layer cBN is 80 nm or more and 200 nm or less. With such a structure, the wear resistance is excellent.

[0106] The minimum hardness depth of the metal layer cBN is 300 nm or more. With such a structure, chipping is unlikely to occur even in intermittent processing.

[0107] When the average hardness of the cBN with the metal layer is taken as the average hardness, the difference between the average hardness and the maximum hardness is 3.0 GPa or less. In other words, when such a structure is provided, the coating has a relatively high hardness as a whole, so the wear resistance is excellent.

[0108] In the cBN with a metal layer, the difference between the average hardness and the minimum hardness is 2.0 GPa or more. With such a structure, in other words, since the coating has a relatively high hardness as a whole, the wear resistance is excellent.

[0109] The maximum hardness is 25 GPa or more. With such high hardness, excellent wear resistance is achieved.

[0110] (Example 2: Scratch test and peel test)

[0111] In addition, the inventors of the present application conducted scratch tests and peel tests on the above-mentioned samples of cBN without a metal layer and cBN with a metal layer. The scratch test is evaluated by the size of the peel load. The larger the peel load, the more difficult it is to peel. In addition, the longer the peel time, the more difficult it is to peel.

[0112] The scratch test was performed under the conditions of a diamond indenter having a tip shape with R (radius of curvature) of 200 μm, a speed of 10 mm / min, and a load rate of 100 N per minute.

[0113] The peeling test was conducted on the quenched material of SCM415, using a sample with a tool shape of CNGA120408S01225, with a cutting speed of 150 m / min, a feed speed of 0.1 mm / turn, and a cutting depth of 0.2 mm, and the time until the hard layer peeled off was evaluated.

[0114] The peel load and peel time are shown in Fig.10 middle. Fig.10 TABLE 1 is a table showing the results of scratch tests and peel tests on cBN without a metal layer and cBN with a metal layer. Figure 8 As shown in the figure, the peeling load of cBN with metal layer is larger and the peeling time is significantly longer than that of cBN without metal layer. Fig.10 In the figure, "80>" means that the peel load is less than 80N, but close to 80N (at least 75N or more). Fig.10 In the figure, "40>" indicates that the peeling time is less than 40 minutes but close to 40 minutes (at least 35 minutes or more). Thus, the coating is less likely to peel off in the cBN with metal layer than in the cBN without metal layer, that is, the coating has high durability.

[0115] <Modification>

[0116] In the above embodiment, a coated tool 1 is described in which a substrate 10 formed of boron nitride particles or the like is mounted on a blade body 2 formed of cemented carbide or the like and coated with a coating 20. Without being limited thereto, the coated tool of the present invention may be, for example, a tool in which a substrate having a hexahedral shape with a parallelogram shape on the upper and lower surfaces is entirely a cubic boron nitride sintered body and a coating is formed on such a substrate.

[0117] In the above-mentioned embodiment, the example when the shape of the upper surface and the lower surface of the coated tool 1 is a parallelogram is shown, but the shape of the upper surface and the lower surface of the coated tool 1 may also be a rhombus or a square, etc. In addition, the shape of the upper surface and the lower surface of the coated tool 1 may also be a triangle, a pentagon, a hexagon, etc.

[0118] The shape of the coated tool 1 may be positive or negative. The positive type is a type in which the side surface is inclined relative to the central axis passing through the center of the upper surface and the center of the lower surface of the coated tool 1, and the negative type is a type in which the side surface is parallel to the above central axis.

[0119] In the above embodiment, an example in which the substrate 10 contains particles of cubic boron nitride (cBN) is described. However, the substrate disclosed in the present application may contain particles of, for example, hexagonal boron nitride (hBN), rhombohedral boron nitride (rBN), wurtzite boron nitride (wBN), etc.

[0120] In the above-mentioned embodiment, the coated tool 1 is described as being used for cutting processing. However, the coated tool of the present application can also be applied to tools other than cutting tools, such as excavation tools and bladed objects.

[0121] More effects and variations can be easily derived by those skilled in the art. Therefore, the broader aspects of the present invention are not limited by the specific details and representative embodiments described and described above. Therefore, various changes can be made without departing from the spirit or scope of the overall inventive concept defined by the additional claim range and its equivalents.

[0122] Explanation of symbols

[0123] 1 Coated tools

[0124] 2 Blade body

[0125] 3 Cutting edge

[0126] 4 Support surface

[0127] 5 Through holes

[0128] 6 Page 1

[0129] 7 Page 2

[0130] 8 Cutting edge

[0131] 10 Matrix

[0132] 20 Coating

[0133] 21 Hard layer

[0134] 22 Metal Layer

[0135] 23 Lamination

[0136] 23a First metal nitride layer

[0137] 23b Second metal nitride layer

[0138] 24 Third metal nitride layer

[0139] 30 substrate

[0140] 40 Jointing material

[0141] 70 Handle

[0142] 73 Card slot

[0143] 75 Bolt

[0144] 100 Cutting tools

Claims

1. A coated tool comprising: a substrate containing a plurality of boron nitride particles, and a coating located on the substrate, The coating comprises: Hard layer; a metal layer located between the substrate and the hard layer, The hard layer includes: a stacked portion located on the metal layer and formed by alternately stacking a first metal nitride layer and a second metal nitride layer; and a third metal nitride layer located on the stacked portion. The metal layer contains Al and Cr, the first metal nitride layer contains AlTiN, the second metal nitride layer contains AlCrN, and the third metal nitride layer contains AlTiN. The thickness of the metal layer is thinner than the thickness of the laminated portion, and the thickness of the third metal nitride layer is thicker than the thickness of the laminated portion. When the hardness is measured by pressing the indenter to a depth of 20% of the coating layer from the surface of the coating layer while changing the indentation load of the indenter, the maximum hardness difference, which is the difference between the maximum hardness and the minimum hardness among the hardnesses, is 4 GPa or more.

2. The coated tool according to claim 1, wherein: The maximum hardness difference is greater than 8 GPa.

3. The coated tool according to claim 1, wherein: When the depth of the maximum hardness is the maximum hardness depth and the depth of the minimum hardness is the minimum hardness depth, the maximum hardness depth is shallower than the minimum hardness depth.

4. The coated tool according to claim 3, wherein: The difference between the maximum hardness depth and the minimum hardness depth is greater than or equal to 180 nm and less than or equal to 500 nm.

5. The coated tool according to claim 3, wherein: The maximum hardness depth is greater than or equal to 80 nm and less than or equal to 200 nm.

6. The coated tool according to any one of claims 3 to 5, wherein: The minimum hardness depth is greater than 300 nm.

7. The coated tool according to any one of claims 1 to 5, wherein: The hardness has an average hardness, and the difference between the average hardness and the minimum hardness is 2.0 GPa or more.

8. The coated tool according to any one of claims 1 to 5, wherein: The maximum hardness is above 25 GPa.

9. The coated tool according to any one of claims 1 to 5, wherein: The metal layer contains 95 atomic % or more of Al and Cr in total.

10. The coated tool according to any one of claims 1 to 5, wherein: The matrix has a binder phase between the boron nitride particles.

11. The coated cutting tool according to any one of claims 1 to 5, wherein: Having a support body formed of cemented carbide or cermet, The base body is located on the support body.

12. A cutting tool, wherein: have: A rod-shaped handle with a slot at the end; The coated cutting tool according to any one of claims 1 to 11 is located in the groove.

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