Carbide alloys and coated tools and cutting tools using the same

Abstract

A non-limiting example of a cemented carbide according to the present disclosure comprises a hard phase that contains W and C, a binder phase that is composed of one or more iron group metals, and an aggregate phase that contains Zr and Nb at an atomic ratio Nb / (Zr + Nb) of less than 0.38. A non-limiting example of a coated tool according to the present disclosure comprises the above-described cemented carbide and a coating layer that is arranged on the surface of the cemented carbide. A non-limiting example of a cutting tool according to the present disclosure is provided with: a holder which extends from a first end to a second end, while having a pocket on the first end side; and the above-described coated tool that is arranged in the pocket.

Description

Cross-reference to related applications

[0007] , , , [Figure 2] , [Figure 1] , , , ,

[0001] This application claims the priority of Japanese Patent Application No. 2022-032394 filed on March 3, 2022, and incorporates the entire disclosure of the previous application herein for reference.

Technical Field

[0002] This disclosure relates to cemented carbide, coated tools using the same, and cutting tools.

Background Art

[0003] Cemented carbide containing WC (tungsten carbide) as a hard phase is used for substrates in coated tools and the like, and is utilized in cutting tools such as end mills. For example, Japanese Patent No. 5424935 (Patent Document 1) describes that by having ZrO2 phase (zirconia phase) scattered on the surface of a substrate made of cemented carbide, peeling of the coating layer due to the difference in thermal expansion between the substrate and the coating layer can be suppressed.

Summary of the Invention

[0004] A cemented carbide according to a non-limiting aspect of the present disclosure includes a hard phase containing W and C, a binder phase composed of one or more iron-group metals, and an agglomerated phase containing Zr and Nb and having an atomic ratio of Nb / (Zr + Nb) less than 0.38.

[0005] A coated tool according to a non-limiting aspect of the present disclosure has the above cemented carbide and a coating layer located on the surface of the cemented carbide.

[0006] A cutting tool according to a non-limiting aspect of the present disclosure includes a holder extending from a first end to a second end and having a pocket on the first end side, and the above coated tool located in the pocket.

Brief Description of the Drawings

[0007] [Figure 1] It is a schematic diagram showing a cross section of a cemented carbide according to a non-limiting aspect of the present disclosure. [Figure 2]This is a perspective view showing one aspect of a coating tool, not limited to this disclosure. [Figure 3] This is a cross-sectional view showing the vicinity of the surface of one coated tool, not limited to this disclosure. [Figure 4] This is a cross-sectional view showing the vicinity of the surface of one coated tool, not limited to this disclosure. [Figure 5] This is a perspective view showing one aspect of a cutting tool, not limited to this disclosure. [Modes for carrying out the invention]

[0008] <Carbide alloy> The following describes in detail, with reference to drawings, a cemented carbide alloy 1, which is not limited to this disclosure. However, for the sake of clarity, only the main components necessary for describing the embodiments are shown in simplified form in the drawings below. Therefore, cemented carbide alloy 1 may have any components not shown in the drawings. Also, the dimensions of the components in the drawings do not faithfully represent the dimensions of the actual components or the dimensional ratios of each component. These points also apply to the coated tools and cutting tools described later.

[0009] The cemented carbide 1 may contain a hard phase 3, a binding phase 5, and an aggregated phase 7, as shown in the example (not limited to) in Figure 1.

[0010] Hard phase 3 may contain W (tungsten) and C (carbon). In other words, hard phase 3 may contain WC. Hard phase 3 may contain WC as its main component. "Main component" may mean the component with the largest mass percentage value compared to other components.

[0011] The bonding phase 5 may consist of one or more iron group metals such as Co (cobalt) and Ni (nickel). The bonding phase 5 may consist of at least one of Co and Ni. The bonding phase 5 can function as a phase that bonds adjacent hard phases 3. The bonding phase 5 may consist only of iron group metals, or it may contain some additives and / or impurities. Specifically, the bonding phase 5 may contain 95% by mass or more of iron group metals, and may contain 5% by mass or less of additives and / or impurities.

[0012] The aggregated phase 7 can also be called the so-called β phase. The aggregated phase 7 can function as a phase that imparts heat resistance to the cemented carbide 1.

[0013] Here, the aggregated phase 7 may contain Zr (zirconium) and Nb (niobium). That is, the aggregated phase 7 may be a phase in which at least Zr and Nb are aggregated. Also, the atomic ratio of Nb / (Zr+Nb) in the aggregated phase 7 may be less than 0.38. When Zr is present in greater quantities than Nb in such a ratio in the aggregated phase 7, the heat resistance of cemented carbide 1 tends to improve. Therefore, cemented carbide 1 has high heat resistance.

[0014] Furthermore, the lower limit of the atomic ratio of Nb / (Zr+Nb) may be greater than 0. Specifically, this lower limit may be 0.02. Nb is a component intentionally added to improve heat resistance. Also, the value of the atomic ratio of Nb / (Zr+Nb) may be an average value.

[0015] The aggregated phase 7 may contain Zr in a proportion of 1 to 10 atomic percent (at%). Furthermore, the aggregated phase 7 may contain Nb in a proportion of 0.5 to 3 atomic percent.

[0016] In addition to Zr and Nb, the condensed phase 7 may further contain C, Ti (titanium), Co, Ta (tantalum), and W. The condensed phase 7 may have the highest atomic ratio of C.

[0017] Elemental analysis when calculating the atomic ratio or the like may be performed, for example, by energy dispersive X-ray spectroscopy (EDS). The elemental analysis may be performed by cross-sectional observation using EDS attached to an electron microscope. Examples of the electron microscope may include a scanning electron microscope (SEM) and a transmission electron microscope (TEM).

[0018] The agglomerated phase 7 may contain the first agglomerated phase 9. The first agglomerated phase 9 may have an atomic ratio of Nb / (Zr + Nb) of 0.25 or less. In this case, the heat resistance of the cemented carbide 1 is likely to be improved.

[0019] The first agglomerated phase 9 may have an atomic ratio of Nb / (Zr + Nb) of 0.2 or less. In this case, an improvement in heat resistance can be expected. Also, in the form of a coated tool, the wear resistance is likely to be improved. The first agglomerated phase 9 may have an atomic ratio of Nb / (Zr + Nb) of 0.05 or more.

[0020] The agglomerated phase 7 may further contain a second agglomerated phase 11 and a third agglomerated phase 13. The second agglomerated phase 11 may have an atomic ratio of Nb / (Zr + Nb) greater than 0.3 and not more than 0.34. The third agglomerated phase 13 may have an atomic ratio of Nb / (Zr + Nb) greater than 0.34 and less than 0.38. In these cases, the heat resistance of the cemented carbide 1 is likely to be improved.

[0021] The average particle size of the first agglomerated phase 9 may be smaller than the average particle sizes of the second agglomerated phase 11 and the third agglomerated phase 13. In this case, the heat resistance of the cemented carbide 1 is likely to be improved.

[0022] The average particle size of the third agglomerated phase 13 may be smaller than the average particle size of the second agglomerated phase 11. In this case, the heat resistance of the cemented carbide 1 is likely to be improved.

[0023] The average particle size of the second agglomerated phase 11 may be larger than the average particle size of the first agglomerated phase 9 and the average particle size of the third agglomerated phase 13. In this case, the heat resistance of the cemented carbide 1 is likely to be improved.

[0024] The average particle size of the first agglomerated phase 9 is not limited to a specific size. This also applies to the average particle size of the second agglomerated phase 11 and the average particle size of the third agglomerated phase 13. The average particle size of the first agglomerated phase 9 may be 0.5 to 4 μm. The average particle size of the second agglomerated phase 11 may be 1.5 to 5 μm. The average particle size of the third agglomerated phase 13 may be 1 to 4.5 μm.

[0025] The measurement of the average particle size of the first agglomerated phase 9 may be performed by image analysis. In that case, the equivalent circle diameter may be used as the average particle size of the first agglomerated phase 9. The measurement of the average particle size of the first agglomerated phase 9 may be performed according to the following procedure. First, using SEM, the cross-section of the cemented carbide 1 may be observed at a magnification of 3000 to 5000 times, and an SEM image may be obtained. At least 50 or more of the first agglomerated phases 9 in this SEM image may be specified and extracted. Then, the average particle size of the first agglomerated phase 9 may be determined by calculating the equivalent circle diameter using image analysis software ImageJ (1.52). The measurement of the average particle size of the second agglomerated phase 11 and the average particle size of the third agglomerated phase 13 may be performed in the same procedure as the average particle size of the first agglomerated phase 9.

[0026] <Method for manufacturing cemented carbide> Next, a method for manufacturing a cemented carbide according to a non-limiting aspect of the present disclosure will be described by taking the case of manufacturing the cemented carbide 1 as an example.

[0027] First, as raw material powders, WC powder, Co powder, TiC powder, ZrC powder, NbC powder, TaC powder, etc. may be prepared.

[0028] The proportion of Co powder may be 4 to 15% by mass (wt%). The proportion of TiC powder may be 0.5 to 5% by mass. The proportion of ZrC powder may be 0.2 to 5% by mass. The proportion of NbC powder may be 0.1 to 3% by mass. The proportion of TaC powder may be 0.1 to 5% by mass. The remainder may be WC powder. The proportion of ZrC powder may be set higher than the proportion of NbC powder.

[0029] The average particle size of the raw material powder may be appropriately selected within the range of 0.1 to 10 μm. The average particle size of the raw material powder may also be the value measured by the microtrac method.

[0030] The prepared raw material powders may be mixed and molded to obtain a molded body. Examples of molding methods include press molding, slip molding, extrusion molding, and cold isostatic press molding.

[0031] The resulting molded body 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, argon atmosphere, or nitrogen atmosphere. The firing temperature may be 1450 to 1600°C. The firing time may be 0.5 to 3 hours.

[0032] The cemented carbide 1 may be obtained by cooling after firing. In this case, the cooling process may include conditions for keeping the temperature in the range of 900 to 1400°C for 0.25 to 2 hours. When such keeping (keeping temperature and keeping time) is included in the cooling process, an aggregated phase 7 with an atomic ratio of Nb / (Zr+Nb) of less than 0.38 is easily formed. Furthermore, an aggregated phase 7 containing a first aggregated phase 9, a second aggregated phase 11, and a third aggregated phase 13 is easily formed.

[0033] The above manufacturing method is merely one example of a method for producing cemented carbide 1. Therefore, it goes without saying that cemented carbide 1 is not limited to those produced by the above manufacturing method.

[0034] <Covered Tools> Next, a coated tool 101, not limited to this disclosure, will be described using Figures 2 to 4, with the case having the above-mentioned cemented carbide 1 as an example.

[0035] The coated tool 101 may have a cemented carbide 1 and a coating layer 103 located on the surface 15 of the cemented carbide 1, as shown in the example (not limited to) in Figures 2 to 4. The coated tool 101 may also have the cemented carbide 1 as its base material. When the coated tool 101 has the cemented carbide 1, wear due to heat is suppressed because the cemented carbide 1 has high heat resistance. Therefore, the wear resistance of the cemented carbide 1 (base material) is high, and combined with the wear resistance of the coating layer 103, the durability of the coated tool 101 is high.

[0036] The coating layer 103 may be located on the entire surface 15 of the cemented carbide 1, or only on a portion of it. That is, the coating layer 103 may be located on at least a portion of the surface 15 of the cemented carbide 1.

[0037] The coating layer 103 may be formed by chemical vapor deposition (CVD). In other words, the coating layer 103 may be a CVD film. Furthermore, the coating layer 103 may be a PVD film formed by physical vapor deposition (PVD).

[0038] The coating layer 103 may be a single layer or a structure in which multiple layers are laminated. Examples of the composition of the coating layer 103 include TiCN (titanium carbonitride), Al2O3 (alumina), and TiN (titanium nitride).

[0039] The coating layer 103 may have a TiCN layer 105 and an Al2O3 layer 107 in that order from the cemented carbide 1, as shown in the example not limited to Figure 3. 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.

[0040] The coating layer 103 may have, in order from the cemented carbide 1, a TiN layer 109, a TiCN layer 105, and an Al2O3 layer 107, as shown in the example not limited to Figure 4. 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.

[0041] The coating layer 103 is not limited to a specific thickness. For example, the thickness of the TiCN layer 105 may be set to approximately 1 to 15 μm. The thickness of the Al2O3 layer 107 may be set to approximately 1 to 15 μm. The thickness of the TiN layer 109 may be set to approximately 0.1 to 5 μm. The thickness of the coating layer 103 may be measured by cross-sectional observation using an electron microscope. The thickness of the coating layer 103 may also be an average value. For example, the thickness may be measured at 10 or more measurement points at 1 μm intervals over a width of 10 μm or more at any position in each layer, and the average value may be calculated.

[0042] Figure 2 shows a cutting insert as an example of the coated tool 101, although this is not limited to the coated tool 101.

[0043] The coating 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 on at least a portion of the ridges of the first surface 111 and the second surface 113.

[0044] The first surface 111 may be a rake face. The entire surface of the first surface 111 may be a rake face, or only a part of it may be a rake face. For example, the portion of the first surface 111 along the cutting edge 115 may be a rake face.

[0045] The second surface 113 may be a relief surface. The entire surface of the second surface 113 may be a relief surface, or only a part of it may be a relief surface. For example, the area of ​​the second surface 113 along the cutting edge 115 may be a relief surface.

[0046] The cutting edge 115 may be located on a part of the ridge, or it may be located on the entire ridge. The cutting edge 115 can be used to cut the workpiece.

[0047] The coating tool 101 may have a through hole 117. The through hole 117 can be used to attach a fixing screw or clamp member when holding the coating tool 101 in a holder. The through hole 117 may be formed from the first surface 111 to the surface opposite the first surface 111 (the bottom surface), or it may open on these surfaces. There is no problem if the through hole 117 is configured to open in mutually opposing regions on the second surface 113.

[0048] The coating tool 101 may be rectangular in shape. However, the shape of the coating tool 101 is not limited to a rectangular shape. For example, the first surface 111 may be triangular, pentagonal, hexagonal, or circular.

[0049] The coating 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. Also, the height from the first surface 111 to the surface opposite to the first surface 111 (the bottom surface) may be set to approximately 5 to 20 mm.

[0050] <Method for manufacturing covered tools> Next, a method for manufacturing a coated tool, not limited to this disclosure, will be described using the case of manufacturing a coated tool 101 as an example.

[0051] A coated tool 101 may be obtained by forming a coating layer 103 on the surface 15 of the cemented carbide 1 using the CVD method.

[0052] The TiCN layer 105 may be deposited as follows. First, a mixed gas may be prepared as the reaction gas composition, consisting of 0.1 to 10 volume% titanium tetrachloride (TiCl4) gas, 10 to 60 volume% nitrogen (N2) gas, 0.1 to 15 volume% methane (CH4) gas, and the remainder being hydrogen (H2) gas. Then, this mixed gas may be introduced into a chamber, the temperature may be set to 800 to 1100°C and the pressure to 5 to 30 kPa, and the TiCN layer 105 may be deposited.

[0053] The Al2O3 layer 107 may be formed as follows. First, a mixed gas may be prepared as the reaction gas composition, consisting of 0.5 to 5 volume% aluminum trichloride (AlCl3) gas, 0.5 to 3.5 volume% hydrogen chloride (HCl) gas, 0.5 to 5 volume% carbon dioxide (CO2) gas, 0.5 volume% or less hydrogen sulfide (H2S) gas, and the remainder being hydrogen (H2) gas. Then, this mixed gas may be introduced into a chamber, the temperature may be set to 930 to 1010°C and the pressure to 5 to 10 kPa, and the Al2O3 layer 107 may be formed.

[0054] The TiN layer 109 may be deposited as follows. First, a mixed gas may be prepared as the reaction gas composition, consisting of 0.1 to 10 volume% titanium tetrachloride (TiCl4) gas, 10 to 60 volume% nitrogen (N2) gas, and the remainder being hydrogen (H2) gas. Then, this mixed gas may be introduced into a chamber, the temperature may be set to 800 to 1010°C and the pressure to 10 to 85 kPa, and the TiN layer 109 may be deposited.

[0055] The above manufacturing method is merely one example of a method for manufacturing the coating tool 101. Therefore, it goes without saying that the coating tool 101 is not limited to those manufactured by the above method.

[0056] <Cutting tools> Next, a cutting tool 201, not limited to this disclosure, will be described with reference to Figure 5, using the case in which it is equipped with the above-described coated tool 101 as an example.

[0057] The cutting tool 201 may include a holder 203 extending from a first end 203a toward a second end 203b and having a pocket 205 on the side of the first end 203a, as shown in an example not limited to Figure 5, and a coated tool 101 located in the pocket 205. When the cutting tool 201 includes a coated tool 101, stable cutting is possible due to the high durability of the coated tool 101.

[0058] The pocket 205 may be the portion into which the covering tool 101 is mounted. The pocket 205 may be open on the outer circumferential surface of the holder 203 and on the end face on the side of the first end 203a.

[0059] The covering tool 101 may be mounted in the pocket 205 such that the cutting edge 115 protrudes outward from the holder 203. Alternatively, the covering tool 101 may be mounted in the pocket 205 by a fixing screw 207. That is, the covering tool 101 may be mounted in the pocket 205 by inserting the fixing screw 207 into the through hole 117 of the covering tool 101 and inserting the tip of the fixing screw 207 into a screw hole formed in the pocket 205 and screwing the screw parts together. In this case, the lower surface of the covering tool 101 may be in direct contact with the pocket 205, or a sheet may be sandwiched between the covering tool 101 and the pocket 205.

[0060] The material of the holder 203 may include, for example, steel and cast iron. If the material of the holder 203 is steel, the toughness of the holder 203 is high.

[0061] In the example shown in Figure 5, a cutting tool 201 used in so-called turning operations is illustrated. Examples of turning operations include internal diameter machining, external diameter machining, and grooving. However, the use of the cutting tool 201 is not limited to turning operations. For example, there is no problem in using the cutting tool 201 in milling operations.

[0062] The above exemplifies one aspect of the cemented carbide 1, coated tool 101, and cutting tool 201 that are not limited to this disclosure. However, it goes without saying that this disclosure is not limited to the embodiments described above, and can be any form as long as it does not deviate from the gist of this disclosure.

[0063] For example, in the above-described, non-limiting embodiments, the case in which cemented carbide 1 is used for the coated tool 101 and the cutting tool 201 was explained as an example, but cemented carbide 1 can be applied to other applications as well. Other applications include, for example, wear-resistant parts such as sliding parts and molds, tools such as drilling tools and cutting tools, and impact-resistant parts.

[0064] The present disclosure will be described in detail below with reference to examples, but the present disclosure is not limited to the following examples. [Examples]

[0065] [Samples No. 1-4] <Manufacturing of cemented carbide> First, the following raw material powders were prepared: WC powder with an average particle size of 3 μm, Co powder with an average particle size of 1.5 μm, TiC powder with an average particle size of 1 μm, ZrC powder with an average particle size of 1 μm, NbC powder with an average particle size of 1 μm, and TaC powder with an average particle size of 1 μm. The average particle size of the raw material powders was measured using the microtrac method.

[0066] Next, the raw material powders were mixed so that the composition of the aggregated phase in the sintered body matched the composition shown in Table 1, and the mixture was press-molded into the shape of a cutting tool (CNMG120408) to obtain a molded body. The obtained molded body was subjected to a binder removal treatment and then fired at a temperature of 1450-1600°C for 0.5-2 hours. After firing, it was cooled under the cooling conditions shown in Table 2 to obtain a cemented carbide consisting of a sintered body containing the aggregated phase with the composition shown in Table 1.

[0067] Elemental analysis was performed using EDS. Specifically, cross-sectional observation was conducted using an EDS attached to a SEM. Three arbitrary points were measured at magnifications ranging from 5000 to 20000x, and the average value was calculated. From this average value, the atomic ratio Nb / (Zr+Nb) was calculated.

[0068] Furthermore, EDS measurements revealed that all obtained cemented carbides contained a hard phase with W and C as the main components, and a bonding phase consisting of ferrous metals (Co). In addition, samples No. 3 and 4 contained agglomerated phases whose atomic ratio of Nb / (Zr+Nb) differed from the numerical range of the first to third agglomerated phases, but for convenience, they were listed in the columns for the first to third agglomerated phases in Tables 1 and 2.

[0069] <Rating> The resulting cemented carbide alloy was subjected to cutting performance evaluation. Specifically, a 1 μm thick TiN layer, a 10 μm thick TiCN layer, and a 5 μm thick Al2O3 layer were deposited onto the cemented carbide (substrate) in that order using the CVD method to create coated tools. After this, cutting performance evaluations were performed under the following conditions. Note that the thickness of each layer is the average value.

[0070] Machining method: Turning Cutting speed: 300m / min Feed rate: 0.3mm / rev Cutting depth: 2mm Workpiece material: SCM435 φ200 round bar Processing condition: WET

[0071] The evaluation results are shown in Table 2. Note that "amount of wear on the flank surface" in Table 2 refers to the amount of wear on the flank surface of the cutting edge during machining.

[0072] [Table 1]

[0073] [Table 2]

[0074] Samples No. 1 and 2 showed significantly improved stability compared to samples No. 3 and 4.

[0075] Furthermore, the average particle size of the first to third aggregated phases in samples No. 1 and 2 was measured using the image analysis described above, and the relationship between the average particle size of the first to third aggregated phases was second aggregated phase > third aggregated phase > first aggregated phase. [Explanation of Symbols]

[0076] 1. Carbide alloy 3...Hard phase 5...bonded phase 7...Agglomerated phase 9...first aggregate phase 11...Second aggregated phase 13...Third aggregate phase 15...Surface 101... Covered Tools 103...Covering layer 105...TiCN layer 107...Al2O3 layer 109...TiN layer 111...1st surface (top surface) 113...2nd side (side) 115...cutting blade 117... Through hole 201...cutting tools 203...Holder 203a...1st end 203b...2nd end 205... pocket 207... Fixing screws

Claims

1. A hard phase consisting of WC, A bonded phase consisting of one or more iron group metals, It consists of an aggregated phase containing Zr and Nb, with an atomic ratio of Nb / (Zr+Nb) of less than 0.

38. The composition is as follows: Co (4-15 mass), TiC (0.5-5 mass%), ZrC (0.2-5 mass%), NbC (0.1-3 mass%), TaC (0.1-5 mass%), and the remainder being WC (Washcloth). The aforementioned aggregated phase is A first aggregated phase in which the atomic ratio of Nb / (Zr+Nb) is 0.2 or less, A second aggregated phase having an atomic ratio of Nb / (Zr+Nb) greater than 0.3 and less than or equal to 0.34, A cemented carbide alloy containing a third aggregated phase in which the atomic ratio of Nb / (Zr+Nb) is greater than 0.34 and less than 0.

38.

2. The cemented carbide according to claim 1, wherein the average particle size of the first aggregated phase is smaller than the average particle size of the second aggregated phase and the average particle size of the third aggregated phase.

3. The cemented carbide according to claim 1 or 2, wherein the average particle size of the third aggregated phase is smaller than the average particle size of the second aggregated phase.

4. A cemented carbide according to claim 1 or 2, A coated tool having a coating layer located on the surface of the cemented carbide.

5. The aforementioned coating layer consists of, in order from the cemented carbide side, a TiCN layer and an Al layer. 2 O 3 A coating tool according to claim 4, having a layer.

6. The coating layer consists of, in order from the cemented carbide side, a TiN layer, a TiCN layer, and an Al layer. 2 O 3 A coating tool according to claim 4, having a layer.

7. A holder extending from a first end toward a second end, with a pocket on the first end side, A cutting tool comprising the covering tool described in claim 4, located in the aforementioned pocket.

Images