Cemented carbide, coated tool, and cutting tool

Abstract

A cemented carbide according to a non-limiting aspect of the present disclosure has a hard phase containing W and C, and a binder phase containing Co. Ta and Zr are in solid solution in the binder phase. The peak intensity of the (110) plane of CoZr in an X-ray diffraction analysis is denoted as P1, the peak intensity of the (200) plane of CoZr is denoted as P2, and the peak intensity of the (111) plane of Co is denoted as P3. The magnitude relationship between P1 and P2 is P2 < P1. The ratio (P1 / P3) of P1 to P3 is 1-2. The ratio (P2 / P3) of P2 to P3 is 0.5-1.5.

Description

Cemented carbide, coated tools and cutting tools CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to Japanese Patent Application No. 2024-040152, filed on March 14, 2024, the entire disclosure of which is incorporated herein by reference.

[0002] The present disclosure relates to cemented carbides, coated tools and cutting tools.

[0003] Cemented carbide containing tungsten carbide (WC) or the like is used as a substrate in coated tools and is utilized in cutting tools, etc. One example of such a cemented carbide is the cemented carbide disclosed in Japanese Patent Laid-Open Publication No. 4-120274 (Patent Document 1). The cemented carbide disclosed in Patent Document 1 contains one or more of Ti, Ta, Nb, V, Cr, Mo, Al, B, and Si dissolved in a binder phase.

[0004] One non-limiting aspect of the cemented carbide disclosed herein is a cemented carbide having a hard phase containing W and C and a binder phase containing Co. Ta and Zr are dissolved in the binder phase. In X-ray diffraction analysis, the peak intensity in the (110) plane of CoZr is designated as P1, the peak intensity in the (200) plane of CoZr is designated as P2, and the peak intensity in the (111) plane of Co is designated as P3. The magnitude relationship between P1 and P2 is P2<P1. The ratio of P1 to P3 (P1 / P3) is 1 to 2. The ratio of P2 to P3 (P2 / P3) is 0.5 to 1.5.

[0005] Fig. 1 is a perspective view showing a non-limiting one-sided cemented carbide (coated tool) of the present disclosure; Fig. 2 is a cross-sectional view showing the vicinity of the surface of a non-limiting one-sided coated tool of the present disclosure; Fig. 3 is a cross-sectional view showing the vicinity of the surface of a non-limiting one-sided coated tool of the present disclosure; Fig. 4 is a perspective view showing a non-limiting one-sided cutting tool of the present disclosure.

[0006] <Cemented Carbide> Hereinafter, one aspect of the cemented carbide 1 of the present disclosure will be described in detail with reference to the drawings. However, for the sake of convenience, the figures referred to below show only the main components necessary for explaining the embodiment in a simplified form. Therefore, the cemented carbide 1 may include optional components not shown in the figures referred to. Furthermore, the dimensions of the components in the figures do not faithfully represent the actual dimensions of the components and the dimensional ratios of each component.

[0007] In one non-limiting example shown in FIG. 1, the cemented carbide 1 may have a hard phase and a binder phase.

[0008] The hard phase may contain W (tungsten) and C (carbon). The hard phase may contain W and C as the main component. "Main component" means the component having the largest mass% value compared to other components. Specifically, the top two mass% values ​​of the components contained in the hard phase may be W and C. The hard phase may contain W and C in the form of WC.

[0009] The binder phase may contain Co (cobalt). The binder phase may contain Co as a main component. That is, Co may have the largest mass % value among the components contained in the binder phase. The binder phase may function as a phase that bonds adjacent hard phases.

[0010] Here, the binder phase may contain Ta (tantalum) and Zr (zirconium) as a solid solution, i.e., the binder phase may be a CoTaZr phase.

[0011] In X-ray diffraction (XRD) analysis, the peak intensity of the CoZr (110) plane may be designated as P1. In addition, in XRD analysis, the peak intensity of the CoZr (200) plane may be designated as P2. In XRD analysis, the peak intensity of the Co (111) plane may be designated as P3.

[0012] The magnitude relationship between P1 and P2 may be P2<P1. The ratio of P1 to P3 (P1 / P3) may be 1 to 2. The ratio of P2 to P3 (P2 / P3) may be 0.5 to 1.5. In these cases, the strength of the binder phase is likely to be improved, and accordingly, chipping resistance and fracture resistance are likely to be improved. Therefore, the cemented carbide 1 has high chipping resistance and fracture resistance.

[0013] The ratio (P1 / P3) may be 1 to 1.3. The ratio (P2 / P3) may be 0.5 to 1. In these cases, the fracture resistance is likely to be improved.

[0014] The ratio (P1 / P3) may be 1.4 to 2. The ratio (P2 / P3) may be 1.1 to 1.5. In these cases, chipping resistance is likely to be improved.

[0015] The peak intensity (P1) on the (110) plane of CoZr may be the peak intensity at an XRD diffraction angle (2θ) of 40.1°. The peak intensity (P2) on the (200) plane of CoZr may be the peak intensity at an XRD diffraction angle (2θ) of 58.0°. The peak intensity (P3) on the (111) plane of Co may be the peak intensity at an XRD diffraction angle (2θ) of 44.2°.

[0016] The XRD analysis conditions may be set, for example, as follows: Apparatus: Rigaku MiniFlex600 Tube: CuKα Tube voltage: 40 kV Tube current: 15 mA Measurement method: 2θ scan Range: 30-80 Step: 0.02 Speed: 10 deg / min

[0017] The binder phase does not need to contain Nb as a solid solution, which tends to improve fracture resistance.

[0018] The cemented carbide 1 may further have a β phase. The β phase may contain Zr. The β phase may be an aggregated phase in which Zr is aggregated. When the cemented carbide 1 further has a β phase, chipping resistance and fracture resistance are likely to be improved.

[0019] The compositions of the hard phase, binder phase, and β phase may be measured, for example, by energy dispersive X-ray spectroscopy (EDS). The measurement may be performed using an EDS attached to an electron microscope. Examples of electron microscopes include a scanning electron microscope (SEM) and a transmission electron microscope (TEM).

[0020] <Method for Manufacturing Cemented Carbide> Next, a method for manufacturing one aspect of the cemented carbide according to the present disclosure will be described.

[0021] First, WC powder, Co powder, TaC powder, NbC powder, ZrC powder, or the like may be prepared as raw material powder.

[0022] The proportion of Co powder may be 5 to 15 mass %, the proportion of TaC powder may be 0.1 to 4 mass %, the proportion of NbC powder may be 0 to 3 mass %, the proportion of ZrC powder may be 0.4 to 2 mass %, and the remainder may be WC powder.

[0023] The proportion of TaC powder can be set to be greater than the proportion of ZrC powder.In this case, the magnitude relationship between P1 and P2 is likely to be P2<P1.In addition, if the above composition is used, the ratio (P1 / P3) and the ratio (P2 / P3) are likely to be in the numerical range described above.

[0024] When the ratio of ZrC powder is 0.3 to 2 mass %, the β phase is easily formed.

[0025] The average particle size of the raw material powder may be appropriately selected from the range of 0.1 to 10 μm, and may be a value measured by a microtrack method.

[0026] The prepared raw material powders may be mixed and molded to obtain a molded body. Examples of molding methods include press molding, slip casting, extrusion molding, and cold isostatic pressing.

[0027] The obtained compact may be subjected to a binder removal treatment and then fired. The firing may be carried out in a non-oxidizing atmosphere such as a vacuum, an argon atmosphere, or a nitrogen atmosphere. The firing temperature may be 1450 to 1600°C. The firing time may be 0.5 to 3 hours. After firing, the compact may be cooled to obtain a cemented carbide.

[0028] The above manufacturing method is one example of a method for manufacturing a cemented carbide, and it goes without saying that the cemented carbide is not limited to those manufactured by the above manufacturing method.

[0029] <Coated Tool> Next, a non-limiting one-sided coated tool 101 of the present disclosure will be described with reference to the drawings, taking as an example a case where the coated tool has the above-described cemented carbide 1 .

[0030] 1 to 3, the coated tool 101 may have a cemented carbide 1 and a coating layer 103 located on the surface 3 of the cemented carbide 1. The coated tool 101 may have the cemented carbide 1 as a substrate. When the coated tool 101 has the cemented carbide 1, the cemented carbide 1 has high chipping resistance and fracture resistance, which tends to improve cutting performance such as interrupted cutting performance. Therefore, the coated tool 101 has high durability.

[0031] The coating layer 103 may be located on the entire surface 3 of the cemented carbide 1, or may be located on only a portion of the surface 3. In other words, the coating layer 103 may be located on at least a portion of the surface 3 of the cemented carbide 1.

[0032] The coating layer 103 may be formed by a chemical vapor deposition (CVD) method. In other words, the coating layer 103 may be a CVD film. Note that the coating layer 103 may also be a physical vapor deposition (PVD) film formed by a PVD method.

[0033] The coating layer 103 may be a single layer or a laminate of multiple layers, and may include, for example, TiCN (titanium carbonitride), AlO (alumina), and TiN (titanium nitride).

[0034] 2, the coating layer 103 may have, in order from the cemented carbide 1 side, a TiCN layer 105 and an Al2O3 layer 107. The TiCN layer 105 may be in contact with the cemented carbide 1. The Al2O3 layer 107 may be in contact with the TiCN layer 105.

[0035] 3, the coating layer 103 may have, in order from the cemented carbide 1 side, a TiN layer 109, a TiCN layer 105, and an Al2O3 layer 107. The TiN layer 109 may be in contact with the cemented carbide 1. The TiCN layer 105 may be in contact with the TiN layer 109. The Al2O3 layer 107 may be in contact with the TiCN layer 105.

[0036] The coating layer 103 is not limited to a specific thickness. For example, the TiCN layer 105 may have an average thickness of about 1 to 15 μm. The Al2O3 layer 107 may have an average thickness of about 1 to 15 μm. The TiN layer 109 may have an average thickness of about 0.1 to 5 μm. The thickness of the coating layer 103 may be measured by cross-sectional observation using an electron microscope. For example, the thickness may be measured at 10 or more measurement points at any position on each layer, and the average value may be calculated.

[0037] 1 shows a cutting insert as a non-limiting example of the coated tool 101. Note that the form of the coated tool 101 is not limited to the cutting insert.

[0038] The coated tool 101 may have a first surface 111 (top surface), a second surface 113 (side surface) adjacent to the first surface 111 , and a cutting edge 115 located at the intersection of the first surface 111 and the second surface 113 .

[0039] The first surface 111 may be a rake face. The first surface 111 may be a rake face entirely, or only a portion of the first surface 111 may be a rake face. For example, a region of the first surface 111 along the cutting edge 115 may be a rake face.

[0040] The second surface 113 may be a flank. The second surface 113 may be a flank entirely, or only a portion thereof may be a flank. For example, a region of the second surface 113 along the cutting edge 115 may be a flank.

[0041] The cutting edge 115 may be located over the entire intersection of the first surface 111 and the second surface 113, or may be located over only a portion of this intersection. The cutting edge 115 can be used to cut a workpiece when the coated tool 101 is used to manufacture a machined product.

[0042] The coated tool 101 may have a through hole 117. The through hole 117 can be used to attach a screw, a clamp member, or the like when fixing the coated tool 101 to a holder. The through hole 117 may be formed from the first surface 111 to a surface (lower surface) located opposite the first surface 111, or may open in these surfaces. Note that there is no problem even if the through holes 117 are configured to open in opposing regions of the second surface 113.

[0043] The coated tool 101 may have a rectangular plate shape. However, the shape of the coated tool 101 is not limited to a rectangular plate shape. For example, the first surface 111 may have a triangular, pentagonal, hexagonal, or circular shape.

[0044] The coated tool 101 is not limited to a specific size. For example, the length of one side of the first surface 111 may be set to approximately 3 to 20 mm. Furthermore, the height from the first surface 111 to the surface (lower surface) located on the opposite side of the first surface 111 may be set to approximately 5 to 20 mm.

[0045] <Method for Manufacturing a Coated Tool> Next, a method for manufacturing a non-limiting one-sided coated tool according to the present disclosure will be described.

[0046] A coated tool may be obtained by forming a coating layer on the surface of the cemented carbide by a CVD method.

[0047] The TiCN layer may be formed as follows. First, a mixed gas containing 0.1 to 10 volume percent titanium tetrachloride (TiCl4) gas, 10 to 60 volume percent nitrogen (N2) gas, 0.1 to 15 volume percent methane (CH4) gas, and the remainder hydrogen (H2) gas may be prepared as the reaction gas composition. This mixed gas may then be introduced into a chamber, and the temperature may be set to 800 to 1100°C and the pressure may be set to 5 to 30 kPa to form the TiCN layer.

[0048] The Al2O3 layer may be formed as follows. First, a mixed gas containing 0.5 to 5 volume percent aluminum trichloride (AlCl3) gas, 0.5 to 3.5 volume percent hydrogen chloride (HCl) gas, 0.5 to 5 volume percent carbon dioxide (CO2) gas, 0.5 volume percent or less hydrogen sulfide (HS) gas, and the remainder hydrogen (H2) gas may be prepared as the reaction gas composition. This mixed gas may then be introduced into a chamber, and the temperature may be set to 930 to 1010°C and the pressure may be set to 5 to 10 kPa to form the Al2O3 layer.

[0049] The TiN layer may be formed as follows. First, a mixed gas containing 0.1 to 10 volume percent titanium tetrachloride (TiCl4) gas, 10 to 60 volume percent nitrogen (N2) gas, and the remainder hydrogen (H2) gas may be prepared as the reaction gas composition. This mixed gas may then be introduced into a chamber, and the temperature may be set to 800 to 1010°C and the pressure may be set to 10 to 85 kPa to form the TiN layer.

[0050] The above-described manufacturing method is merely an example of a method for manufacturing a coated tool, and it goes without saying that the coated tool is not limited to one manufactured by the above-described manufacturing method.

[0051] <Cutting Tool> Next, a non-limiting one-sided cutting tool 201 of the present disclosure will be described with reference to the drawings, taking as an example a case where the cutting tool 201 includes the coated tool 101 described above.

[0052] The cutting tool 201 may include a holder 203 and a coated tool 101, as in a non-limiting example shown in Fig. 4. The holder 203 may extend from a first end 203a to a second end 203b and may have a pocket 205 on the side of the first end 203a. The coated tool 101 may be located in the pocket 205. When the cutting tool 201 includes the coated tool 101, stable cutting is possible due to the high durability of the coated tool 101.

[0053] The cutting tool 201 may be for machining stainless steel. The cemented carbide 1 contained in the coated tool 101 is likely to be effective when used for machining stainless steel. The above configuration can also be rephrased as the cemented carbide 1 being for machining stainless steel. Examples of stainless steel include SUS304 and SUS316.

[0054] The pocket 205 may be a portion to which the coated tool 101 is attached. The pocket 205 may be open at the outer circumferential surface of the holder 203 and at the end surface on the side of the first end 203a.

[0055] The coated tool 101 may be attached to the pocket 205 so that at least a part of the cutting edge 115 protrudes from the holder 203. Alternatively, the coated tool 101 may be attached to the pocket 205 by a screw 207. That is, the coated tool 101 may be attached to the pocket 205 by inserting the screw 207 into the through hole 117 of the coated tool 101, inserting the tip of the screw 207 into a threaded hole formed in the pocket 205, and fixing the screw 207 to the threaded hole. At this time, the lower surface of the coated tool 101 may be in direct contact with the pocket 205, or a sheet may be sandwiched between the coated tool 101 and the pocket 205.

[0056] Examples of materials for the holder 203 include steel and cast iron. When the material for the holder 203 is steel, the holder 203 has high toughness.

[0057] 4 illustrates a cutting tool 201 used for so-called turning. Examples of turning include inner diameter machining, outer diameter machining, and grooving. The cutting tool 201 (coated tool 101) is not limited to that used for turning. For example, there is no problem in using the coated tool 101 as a cutting tool 201 used for milling.

[0058] The foregoing has provided examples of the cemented carbide 1, the coated tool 101, and the cutting tool 201 of the present disclosure, which are not limited thereto. However, it goes without saying that the present disclosure is not limited to the above-described embodiments, and any other configurations may be used as long as they do not deviate from the gist of the present disclosure.

[0059] For example, in the above non-limiting embodiment, the cemented carbide 1 is used in the coated tool 101 and the cutting tool 201, but the cemented carbide 1 can also be used in other applications, such as wear-resistant parts such as sliding parts or dies, tools such as drilling tools and cutting tools, and impact-resistant parts.

[0060] The cemented carbide 1, the coated tool 101, and the cutting tool 201 may also have the following configurations: [1] The cemented carbide has a hard phase containing W and C and a binder phase containing Co, wherein Ta and Zr are solid-solved in the binder phase, and in X-ray diffraction analysis, the peak intensity in the (110) plane of CoZr is designated P1, the peak intensity in the (200) plane of CoZr is designated P2, and the peak intensity in the (111) plane of Co is designated P3, the magnitude relationship between P1 and P2 is P2<P1, the ratio of P1 to P3 (P1 / P3) is 1 to 2, and the ratio of P2 to P3 (P2 / P3) is 0.5 to 1.5. [2] The cemented carbide of [1] above does not need to have Nb solid-solved in the binder phase. [3] The coated tool may have the cemented carbide of [1] or [2] above and a coating layer located on the surface of the cemented carbide. [4] In the coated tool of [3] above, the coating layer may have, from the cemented carbide side, a TiCN layer and an Al2O3 layer. [5] In the coated tool of [3] above, the coating layer may have, from the cemented carbide side, a TiN layer, a TiCN layer, and an Al2O3 layer. [6] The cutting tool may include a holder extending from a first end to a second end and having a pocket on the first end side, and a coated tool of any one of [3] to [5] above located in the pocket. [7] The cutting tool of [6] above may be for machining stainless steel.

[0061] The present disclosure will be described in detail below with reference to examples, but the present disclosure is not limited to the following examples.

[0062] [Samples No. 1 to 3] <Preparation of cemented carbide> First, WC powder with an average particle size of 9 μm, Co powder with an average particle size of 1.5 μm, TaC powder with an average particle size of 0.9 μm, NbC powder with an average particle size of 1.1 μm, and ZrC powder with an average particle size of 1.5 μm were prepared as raw material powders. The average particle sizes of the raw material powders were measured by the Microtrack method.

[0063] Next, the raw material powders were mixed in the proportions of the compounded compositions shown in Table 1 and press-molded into a cutting tool shape (CNMG120408) to obtain a green body. The obtained green body was then subjected to a binder removal treatment and then fired in a non-oxidizing atmosphere. The firing temperature was set to 1570°C, the firing time was set to 1 hour, and an argon atmosphere was used as the non-oxidizing atmosphere. After firing, the product was cooled to obtain the cemented carbide shown in Table 1.

[0064] The composition of the obtained cemented carbide was measured by EDS. Specifically, cross-section observation was performed using an EDS attached to an SEM, with a magnification of 5,000 to 20,000 times, and the average value of measurements at five locations was measured. Five elements, namely, tungsten carbide, cobalt, titanium, carbon, and nitrogen, were selected for measurement by EDS.

[0065] As a result of EDS measurement, all of the obtained cemented carbides had a hard phase containing WC as a main component, a binder phase containing Co as a main component, and also had a β-phase, which was an agglomerated phase of Zr. Ta and Zr were solid-solved in the binder phase. The proportions of TaC and ZrC in the formulations shown in Table 1 may be regarded as the amounts of Ta and Zr dissolved in the binder phase.

[0066] The obtained cemented carbide was subjected to XRD analysis according to the method exemplified above, and P1, P2, P3, the ratio (P1 / P3), and the ratio (P2 / P3) were measured. The results are shown in the "XRD" column in Table 1. The ratio (P1 / P3) is shown in the "P1 / P3" column. The ratio (P2 / P3) is shown in the "P2 / P3" column.

[0067] P1 is the peak intensity at the (110) plane of CoZr, where the XRD diffraction angle (2θ) is 40.1°. P2 is the peak intensity at the (200) plane of CoZr, where the XRD diffraction angle (2θ) is 58.0°. P3 is the peak intensity at the (111) plane of Co, where the XRD diffraction angle (2θ) is 44.2°.

[0068] <Evaluation> A cutting test was conducted on the obtained cemented carbide. Specifically, a TiN layer with an average thickness of 1 μm, a TiCN layer with an average thickness of 10 μm, and an Al2O3 layer with an average thickness of 6 μm were formed on the cemented carbide (substrate) in this order by CVD to prepare a coated tool. Chipping evaluation and fracture evaluation were then conducted under the following conditions.

[0069] (Chipping evaluation) Machining mode: turning Cutting speed: 200 m / min Feed: 0.1 mm / rev Depth of cut: 0.5 mm Workpiece: SUS304 round bar with four grooves and a diameter of 200 Machining condition: WET

[0070] (Evaluation of chipping) Machining mode: turning Cutting speed: 150 m / min Feed: 0.25 mm / rev Depth of cut: 1 mm Workpiece: SUS316 hexagonal bar with a diameter of 200 Machining condition: WET

[0071] The test results are shown in Table 1. In Table 1, "Cutting time (min) until chipping occurs" refers to the time when the coating layer peels off and the exposed width of the substrate reaches 0.2 mm in the chipping evaluation. Also, "Number of impacts until fracture" refers to the number of impacts until the cutting edge fractures in the fracture evaluation.

[0072]

[0073] Compared with sample No. 3, samples Nos. 1 and 2 exhibited higher chipping resistance and fracture resistance.

[0074] DESCRIPTION OF SYMBOLS 1: Carbide alloy 3: Surface 101: Coated tool 103: Coating layer 105: TiCN layer 107: Al2O3 layer 109: TiN layer 111: First surface (upper surface) 113: Second surface (side surface) 115: Cutting edge 117: Through hole 201: Cutting tool 203: Holder 203a: First end 203b: Second end 205: Pocket 207: Screw

Claims

1. A cemented carbide having a hard phase containing W and C and a binder phase containing Co, wherein Ta and Zr are dissolved in the binder phase, and in X-ray diffraction analysis, the peak intensity in the (110) plane of CoZr is designated as P1, the peak intensity in the (200) plane of CoZr is designated as P2, and the peak intensity in the (111) plane of Co is designated as P3, the magnitude relationship between P1 and P2 is P2<P1, the ratio of P1 to P3 (P1 / P3) is 1 to 2, and the ratio of P2 to P3 (P2 / P3) is 0.5 to 1.

5.

2. The cemented carbide according to claim 1, wherein Nb is not dissolved in the binder phase.

3. A coated tool comprising the cemented carbide according to claim 1 or 2 and a coating layer located on the surface of the cemented carbide.

4. The coated tool according to claim 3, wherein the coating layer comprises a TiCN layer and an Al2O3 layer in this order from the cemented carbide side.

5. The coated tool according to claim 3, wherein the coating layer comprises, from the cemented carbide side, a TiN layer, a TiCN layer, and an Al2O3 layer in this order.

6. A cutting tool comprising: a holder extending from a first end to a second end and having a pocket on the side of said first end; and a coated tool according to any one of claims 3 to 5 located in said pocket.

7. The cutting tool according to claim 6, which is for machining stainless steel.

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