Sintered bodies and cutting tools

Abstract

To provide a sintered body and a cutting tool having excellent wear resistance, heat resistance and chipping resistance under high-speed machining.SOLUTION: There is provided a sintered body which contains hard particles mainly composed of TiN, TiC, TiCN, or (Ti, M) (C, N) (M is one or more elements selected from Groups 4 to 6 of the Periodic Table (excluding Ti element)) and a binder phase containing at least one of Co and Ni. The binder phase further contains at least one selected from Re, Ru, Mo and W. When the ratio of the total content (mass%) of Re, Ru, Mo and W to the total content (mass%) of Co, Ni, Re, Ru, Mo and W in the surface region from the surface to a depth of 20 μm is defined as Bs and the ratio of total content (mass%) of Re, Ru, Mo and W to the total content (mass%) of Co, Ni, Re, Ru, Mo and W in the internal region inside from the surface region is defined as Bi, the sintered body satisfies the following relational expression (1): Bs / Bi≥1.1 (1).SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a sintered body and a cutting tool.

Background Art

[0002] Cutting tools are known which use, as a base material, cemented carbide or cermet including a hard phase containing tungsten carbide or titanium carbonitride as a main component and a binder phase containing an iron group element as a main component (see, for example, Patent Document 1).

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] Incidentally, cutting tools having a base material of cemented carbide or cermet are generally excellent in fracture resistance, but are poor in heat resistance and not suitable for high-speed machining. Therefore, for cermet, a configuration is known that achieves improved heat resistance by controlling the amount of the metal binder phase on the surface. However, merely reducing the amount of the binder phase on the surface does not lead to suppression of wear, plastic deformation, and the like in a high-speed machining region. On the other hand, there is a demand for a technology for high-speed machining of steel materials with high cutting resistance. The present disclosure has been made in view of the above circumstances, and an object of the present disclosure is to provide a sintered body and a cutting tool that are excellent in wear resistance, heat resistance, and fracture resistance under high-speed machining. The present disclosure can be implemented as the following embodiments.

Means for Solving the Problem

[0005] [1] Hard particles containing, as a main component, TiN, TiC, TiCN, or (Ti, M)(C, N) (where M is one or more elements selected from elements belonging to Groups 4 to 6 of the periodic table excluding the Ti element), and A bonded phase comprising at least one of Co and Ni, A sintered body containing, The bonded phase further comprises at least one selected from Re, Ru, Mo, and W. In the surface region of the sintered body up to a depth of 20 μm from the surface, Bs is defined as the ratio (mass%) of the total content (mass%) of Re, Ru, Mo, and W to the total content (mass%) of Co, Ni, Re, Ru, Mo, and W. In the internal region of the sintered body, which is inside the surface region, the ratio of the total content (mass%) of Re, Ru, Mo, and W to the total content (mass%) of Co, Ni, Re, Ru, Mo, and W is defined as Bi. A sintered body that satisfies the following relation (1). Bs / Bi≧1.1 …(1)

[0006] [2] In the surface region of the sintered body, the content of the binder phase (mass%) relative to the total content (mass%) of the hard particles, the binder phase, and the dispersed particles is Ms. In the internal region of the sintered body, the content of the binder phase (mass%) relative to the total content (mass%) of the hard particles, the binder phase, and the dispersed particles is defined as Mi. A sintered body according to claim 1 that satisfies the following relation (2). 0.5 ≤ Ms / Mi ≤ 0.8 …(2)

[0007] [3] A cutting tool using the sintered body described in [1] or [2].

[0008] A cutting tool having a sintered body as described in [4], [1], or [2] as a base material, and a coating layer on the surface of the base material. [Effects of the Invention]

[0009] This disclosure provides a sintered body that exhibits excellent wear resistance, heat resistance, and fracture resistance under high-speed machining conditions. By including a hard phase mainly composed of Ti compounds, which have excellent reactivity resistance to iron (Fe) and hardness, a sintered body with excellent wear resistance is obtained. Furthermore, by having a binder phase containing at least one selected from Re, Ru, Mo, and W, the heat resistance of the binder phase itself can be improved. As a result, a sintered body with excellent wear resistance and resistance to plastic deformation can be obtained even under high-speed machining. In high-speed machining, the component ratio of the binder phase contributes to improving the wear resistance and resistance to plastic deformation of the sintered body, and the more high-melting-point metal components such as Re, Ru, Mo, and W are included in the binder phase, the better the wear resistance and resistance to plastic deformation of the sintered body becomes. On the other hand, there is a concern that if the amount of Re, Ru, Mo, and W is excessive, the fracture resistance of the sintered body will decrease. Therefore, in the surface region of the sintered body up to a depth of 20 μm from the surface, Bs is the ratio of the total content (mass%) of Re, Ru, Mo, and W to the total content (mass%) of Co, Ni, Re, Ru, Mo, and W, and in the internal region inside the surface region of the sintered body, Bi is the ratio of the total content (mass%) of Re, Ru, Mo, and W to the total content (mass%) of Co, Ni, Re, Ru, Mo, and W, and by satisfying the relationship Bs / Bi ≥ 1.1, it is possible to achieve both chipping resistance, wear resistance, and plastic deformation resistance of the sintered body. If, in the surface region of a sintered body, Ms is the ratio of the binder phase content (mass%) to the total content (mass%) of hard particles, binder phase, and dispersed particles, and Mi is the ratio of the binder phase content (mass%) to the total content (mass%) of hard particles, binder phase, and dispersed particles in the internal region of the sintered body, and the relationship 0.5 ≤ Ms / Mi ≤ 0.8 is satisfied, then it is possible to achieve both fracture resistance, wear resistance, and plastic deformation resistance in the sintered body. This is because not only the components of the binder phase but also the amount of binder phase contribute to cutting performance; specifically, the smaller the amount of binder phase, the better the wear resistance and plastic deformation resistance of the sintered body, but on the other hand, the lower the fracture resistance. By using the sintered body of this disclosure as a cutting tool, a cutting tool with excellent wear resistance and fracture resistance can be provided. When a coating layer is formed on the surface of a cutting tool, the surface can be hardened and oxidation of the substrate covered by the coating layer can be suppressed, thereby further improving the wear resistance of the cutting tool. [Brief explanation of the drawing]

[0010] [Figure 1] This is a perspective view of an example of a sintered body (cutting tool). [Figure 2] This is a cross-sectional view along line AA in Figure 1. [Figure 3] This is an explanatory diagram illustrating the cross-section of a sintered body. [Figure 4] This is an explanatory diagram illustrating the region used for compositional analysis in the cross-section of the sintered body. [Modes for carrying out the invention]

[0011] The following provides a detailed explanation of this disclosure. In this specification, when numerical ranges are described using "~", unless otherwise specified, both the lower limit and the upper limit are included. For example, the description "10~20" includes both the lower limit "10" and the upper limit "20". In other words, "10~20" has the same meaning as "10 or more and 20 or less".

[0012] 1. Sintered body (1) Structure of the sintered body The sintered body comprises hard particles mainly composed of TiN, TiC, TiCN, or (Ti, M)(C, N) (where M is one or more elements selected from groups 4-6 of the periodic table (excluding Ti)), and a bonding phase containing at least one of Co (cobalt) and Ni (nickel). The bonding phase further contains at least one selected from Re (rhenium), Ru (ruthenium), Mo (molybdenum), and W (tungsten).

[0013] (2) Hard particles The hard particles are mainly composed of TiN, TiC, TiCN, or (Ti, M)(C, N) (where M is one or more elements selected from elements belonging to groups 4 to 6 of the periodic table, excluding titanium (Ti)). Here, the term "main component" means that the Ti compound accounts for 60% by volume or more when the total volume of the hard particles is 100% by volume. M is preferably at least one element selected from Ta (tantalum), Nb (niobium), W (tungsten), V (vanadium), Cr (chromium), Zr (zirconium), Mo (molybdenum), and Hf (hafnium). Among these, at least one element selected from Ta (tantalum), Nb (niobium), and W (tungsten) is more preferred, and Ta and / or Nb is even more preferred. There is no particular limitation on the composition ratio of elements constituting the hard particles. The hard particles may be single-composition particles, or may be particles containing a plurality of components (e.g., particles with a core-rim structure). There is no particular limitation on the composition ratio of elements constituting TiC, TiN, TiCN, and (Ti, M)(C, N). For example, the ratio of C and N in TiCN is not lim ited, and C and N may be present in a non-stoichiometric ratio. Only one type of hard particles may be present, or a plurality of types of hard particles may be present. The presence of a plurality of types means that (Ti, M)(C, N) particles with different elements M coexist, and also means that (Ti, M)(C, N) particles having the same element M but different composition ratios of Ti, M, C, and N constituting the particles coexist. From the viewpoint of resistance to reaction with iron contained in a work material, the ratio expressed by (XN / (XC+XN)), where XC is the carbon composition ratio and XN is the nitrogen composition ratio, is preferably in the range of 0.10 to 0.90, more preferably in the range of 0.20 to 0.80, and even more preferably in the range of 0.30 to 0.70. From the viewpoint of hardness, the ratio expressed by (XTi / (XTi+XM)), where XTi is the titanium composition ratio and XM is the composition ratio of the metal element M, is preferably in the range of 0.40 to 0.95, more preferably in the range of 0.50 to 0.95, and even more preferably in the range of 0.70 to 0.95. The content (volume%) of each substance in the sintered body can be calculated by determining the content of each element through fluorescent X-ray analysis or the like.

[0014] The content of the hard particles in the sintered body is not particularly limited. From the viewpoint of improving wear resistance and plastic deformation resistance, when the total volume of the hard particles, the binding phase and the dispersed particles described below is defined as 100% by volume, the content of the hard particles is preferably 70% by volume or more and 95% by volume or less, more preferably 75% by volume or more and 90% by volume or less, and still more preferably 80% by volume or more and 85% by volume or less.

[0015] (3) Binder Phase The binder phase contains at least one of Co and Ni. When the binder phase contains at least one of Co and Ni, the bonding between the hard particles and between the dispersed particles described below can be strengthened. Therefore, the wear resistance and fracture resistance of the sintered body can be improved.

[0016] The binder phase further contains at least one selected from Re, Ru, Mo and W. This can improve the heat resistance of the binder phase itself. As a result, the decrease in hardness at high temperatures can be suppressed, and the high-temperature softening of the binder phase can be suppressed. Therefore, the sintered body is less prone to compositional deformation.

[0017] It is preferable that the binder phase contains Co, Re and Mo. Mo forms a solid solution in the hard particles, and can serve as an intermediate layer between the hard particles and the binder phase to improve the fracture resistance of the sintered body. Furthermore, Mo is a high-melting-point metal. In addition, further adding Re to the binder phase can further suppress the high-temperature softening of the binder phase. Therefore, the sintered body is less prone to plastic deformation.

[0018] From the viewpoint of improving wear resistance and plastic deformation resistance, when the total volume of the hard particles, the binder phase and the dispersed particles described below is defined as 100% by volume, the content of the binder phase in the sintered body is preferably 3% by volume or more and 12% by volume or less, and more preferably 5% by volume or more and 8% by volume or less.

[0019] (4) Configurations of Surface Region and Internal Region of Sintered Body The surface region of the sintered body is defined as the area from the surface to a depth of 20 μm. In the surface region of the sintered body, Bs is defined as the ratio (mass%) of the total content (mass%) of Re, Ru, Mo, and W to the total content (mass%) of Co, Ni, Re, Ru, Mo, and W. If the mass%) content (mass%) of Co, Ni, Re, Ru, Mo, and W in the surface region of the sintered body is expressed as Rs(Co), Rs(Ni), Rs(Re), Rs(Ru), Rs(Mo), and Rs(W), then Bs = (Rs(Re) + Rs(Ru) + Rs(Mo) + Rs(W)) / (Rs(Co) + Rs(Ni) + Rs(Re) + Rs(Ru) + Rs(Mo) + Rs(W)). The region inside the surface region of a sintered body is defined as the internal region. In the internal region, Bi is defined as the ratio (mass%) of the total content (mass%) of Re, Ru, Mo, and W to the total content (mass%) of Co, Ni, Re, Ru, Mo, and W. If the mass%) content (mass%) of Co, Ni, Re, Ru, Mo, and W in the internal region is expressed as Ri(Co), Ri(Ni), Ri(Re), Ri(Ru), Ri(Mo), and Ri(W), then Bi = (Ri(Re) + Ri(Ru) + Ri(Mo) + Ri(W)) / (Ri(Co) + Ri(Ni) + Ri(Re) + Ri(Ru) + Ri(Mo) + R(W)). Bs and Bi satisfy the following relationship (1). Bs / Bi≧1.1 …(1) By satisfying the above relationship (1) between Bs and Bi, Bs can be made larger than Bi, thereby achieving a balance between fracture resistance, wear resistance, and plastic deformation resistance of the sintered body.

[0020] In the surface region of a sintered body, Ms is defined as the percentage of the binder phase relative to the total percentage of hard particles and binder phase (mass%). If the percentages of hard particles and binder phase in the surface region of the sintered body are expressed as Rs (hard particles), Rs (binder phase), and Rs (dispersed particles), respectively, then Ms = Rs (binder phase) / (Rs (hard particles) + Rs (binder phase) + Rs (dispersed particles)). In the internal region, let Mi be the percentage of the binder phase relative to the total percentage of hard particles and the binder phase (mass%). If we express the percentages of hard particles and the binder phase in the internal region as Ri(hard particles), Ri(binder phase), and Ri(dispersed particles), respectively, then Mi = Ri(binder phase) / (Ri(hard particles) + Ri(binder phase) + Ri(dispersed particles)). Ms and Mi satisfy the following relationship (2). 0.5 ≤ Ms / Mi ≤ 0.8 …(2) When Ms and Mi satisfy the above relationship (2), it is possible to achieve both fracture resistance, wear resistance, and plastic deformation resistance in the sintered body. This is because not only the constituent components of the bonding phase but also the amount of bonding phase contribute to cutting performance; specifically, the smaller the amount of bonding phase, the better the wear resistance and plastic deformation resistance, but on the other hand, the lower the fracture resistance.

[0021] In a sintered body, the ratio of the total content (mass%) of Re, Ru, Mo, and W to the total content (mass%) of Co, Ni, Re, Ru, Mo, and W changes continuously. In a sintered body, the content (mass%) of the binder phase to the total content (mass%) of hard particles, binder phase, and dispersed particles changes continuously.

[0022] (5) Dispersed particles The sintered body may contain, in addition to the hard particles described above, independent particles (dispersed particles) that do not form solid solutions with the hard particles. The inclusion of dispersed particles in the sintered body hinders the movement of hard particles under high-temperature and high-load environments, thus contributing to improved resistance to plastic deformation. The dispersed particles are preferable because they contain chemically stable Al, which improves wear resistance. The Al-containing dispersed particles are dispersed within the sintered body and suppress the grain growth of the hard particles. Hereinafter, particles containing Al will also be referred to as dispersed particles. Examples of dispersed particles include particles composed of one or more of the following: Al nitrides, oxides, and oxynitrides. For example, it is shown that they consist of one or more of the following: AlN particles (aluminum nitride particles), Al2O3 particles (aluminum oxide particles), and AlON particles (aluminum oxynitride particles).

[0023] The dispersed particles are preferably AlN particles. AlN particles can increase the thermal conductivity and decrease the coefficient of thermal expansion of cutting tools made using sintered bodies. Therefore, by including AlN particles as dispersed particles, better wear resistance and fracture resistance can be achieved under high-speed machining conditions, improving tool life.

[0024] The content of dispersed particles is not particularly limited. Preferably, the content of dispersed particles is 2% to 25% by volume, and more preferably 5% to 10% by volume, when the entire sintered body is considered as 100% by volume. If the content of dispersed particles is within this range, diffusion wear under high-speed machining can be suppressed, thereby improving the wear resistance of the tool. Furthermore, even if the firing temperature during manufacturing is increased due to the higher melting point (heat resistance) of the binding phase, the grain growth of hard particles can be effectively suppressed, and the microstructure can be refined, thereby improving the wear resistance and fracture resistance of the tool.

[0025] 2. Method for manufacturing a sintered body The method for manufacturing the sintered body is not particularly limited. An example of a method for manufacturing the sintered body is shown below.

[0026] (1) Raw materials The following raw material powders are used as raw materials. ·Ti carbonitride raw material powder • One or more raw material powders selected from TaC powder (tantalum carbide powder), NbC powder (niobium carbide powder), and WC powder (tungsten carbide powder), or solid solution powders thereof. • Raw material powders such as AlN (aluminum nitride) and Al2O3 powder (aluminum oxide powder) Raw material powders such as Co powder, Ni powder, Re powder, Ru powder, Mo powder, W powder, etc.

[0027] (2) Preparation of the powder for calcination The raw material powders are weighed to the predetermined mixing ratio. The raw material powders, spheres (e.g., Al2O3 spheres), and solvent (e.g., acetone) are placed in a container (e.g., a resin pot) and mixed and ground. The resulting slurry is dried by water bath to obtain a dried mixed powder.

[0028] (3) Firing After press molding the dried mixed powder, a sintered body is produced by atmospheric firing. Atmospheric firing is performed under either an Ar atmosphere or an N2 atmosphere.

[0029] (4) Inclination treatment The resulting sintered body is subjected to gradient treatment (heat treatment). The gradient treatment is carried out under an Ar atmosphere or an N2 atmosphere. The Ms / Mi and Bs / Bi values ​​can be controlled by the compounding composition and heat treatment conditions (heat treatment temperature, ambient pressure). In particular, the amount of bonding phase can be reduced by heat treatment.

[0030] 3.Cutting tools As shown in Figures 1 and 2, the cutting tool 1 is made using the sintered body 2 described above. The shape of the cutting tool 1 is not particularly limited.

[0031] The sintered body 2 can be shaped and its surface finished by at least one of the following processing methods: cutting, grinding, and polishing, to become a cutting tool 1. Of course, if these finishing processes are unnecessary, the sintered body 2 can be used as a cutting tool 1 as is.

[0032] The cutting tool 1 may use a sintered body 2 as a base material, with a coating layer 7 formed on the surface of the base material. The coating layer 7 is not particularly limited, but preferably consists of at least one compound selected from titanium, zirconium, chromium, and aluminum carbides, nitrides, oxides, carbonitrides, carbonoxides, oxynitrides, and carbonitrides. When the coating layer 7 is formed, the surface hardness of the cutting tool 1 increases, and oxidation of the base material covered by the coating layer 7 is suppressed, thereby improving the wear resistance of the cutting tool 1. The at least one compound selected from titanium, zirconium, chromium, and aluminum carbides, nitrides, oxides, carbonitrides, carbonoxides, oxynitrides, and carbonitrides is not particularly limited, but TiN, TiAlN, TiCrAlN, and CrAlN are preferred examples. From the viewpoint of wear resistance, Ti-based compounds (e.g., TiCrAlN, TiAlN) are more preferred. The coating layer 7 may be a single layer or a laminated layer in which multiple layers of films are stacked. The thickness of the coating layer 7 is not particularly limited. From the viewpoint of wear resistance, the thickness of the coating layer 7 is preferably 0.02 μm or more and 30 μm or less. [Examples]

[0033] The present disclosure will be further described in detail below with reference to examples. Experimental Examples 1-11, 13, 14, 16, and 17 are examples, while Experimental Examples 12 and 15 are comparative examples. In the table, experimental examples are indicated using "No.". Additionally, if an asterisk (*) is present in the table, such as "*12", it indicates that it is a comparative example.

[0034] 1. Experimental Examples 1-17 Each of the sintered bodies in Experimental Examples 1 to 17 was prepared, and these sintered bodies were processed to create each of the cutting tools in Experimental Examples 1 to 17. In the formulations shown in Table 1, the total amount of the components included is 100% by volume. In Table 1, the formulation "(Ti,Nb)(C,N)-9%AlN-8%(Co,Re,Mo)" for Experimental Example 3 means that (Ti,Nb)(C,N), AlN, and (Co,Re,Mo) are contained in amounts of 83% by volume, 9% by volume, and 8% by volume, respectively.

[0035] (1) Raw material powder The following raw material powders were used. Ti carbonitride raw material powder: Average particle size 1.5μm or less NbC powder: average particle size 1.5μm or less AlN powder: average particle size 0.7μm or less Co powder: Average particle size 5.0μm or less Ni powder: Average particle size 5.0μm or less Re powder: Average particle size 5.0μm or less Ru powder: Average particle size 5.0μm or less Mo powder: Average particle size 5.0μm or less W powder: Average particle size 5.0μm or less

[0036] (2) Preparation of sintered bodies (Experimental Examples 1-17) A mixed powder was prepared using the raw material powder, and acetone was added to the mixed powder and ground and mixed for 72 hours. After grinding and mixing, the obtained slurry was dried in a water bath to remove the acetone and prepare a dried mixed powder. Using the obtained dried mixed powder, a sintered body was produced by press molding and atmospheric firing. The atmospheric firing conditions were a firing temperature of 1500°C to 1750°C for 2 hours under an Ar atmosphere. The obtained sintered body was subjected to a gradient treatment. The gradient treatment conditions were a firing temperature of 1400°C to 1500°C, 70 Pa to 270 Pa under an Ar atmosphere. The Ms / Mi and Bs / Bi values ​​were controlled by the compound composition and the heat treatment conditions of the gradient treatment (heat treatment temperature, ambient pressure). Table 1 shows the composition (volume %), bond phase component ratio (mass %), and gradient conditions for each experimental example.

[0037] [Table 1]

[0038] [Table 2]

[0039] (3) Evaluation of the surface and internal regions of the sintered body For the sintered bodies of Experimental Examples 1 to 17, cross-sections including the outermost layer were cut out, mirror-finished, and then the composition was analyzed using an electron beam microanalyzer (EPMA). For example, as shown in Figure 3, sintered body 2 was cut, and cross-section 5 of one of the divided pieces (cross-section 5 of sintered body 2) was used for analysis. Figure 4 is an explanatory diagram showing cross-section 5 of sintered body 2 and a magnified part thereof. In cross-section 5, the region overlapping one edge 5A and 1 mm away from the other edge 5B was defined as region A. In region A, a 20 μm × 20 μm region AR1 overlapping one edge 5A and a region AR2 1 mm away from one edge 5A were used for analysis. Specifically, the amounts of Ti, Nb, Co, Ni, Re, Ru, Mo, and W were measured, and the content (mass%) of each of Ti, Nb, Co, Ni, Re, Ru, Mo, and W in the sintered body was calculated. Then, the Bs / Bi and Ms / Mi values ​​were evaluated.

[0040] For example, in Experiment Example 3, Bs = (Rs(Re) + Rs(Mo)) / (Rs(Co) + Rs(Re) + Rs(Mo)) and Bi = (Ri(Re) + Ri(Mo)) / (Ri(Co) + Ri(Re) + Ri(Mo)). Also, Ms = (Rs(Co) + Rs(Re) + Rs(Mo)) / (Rs(Ti) + Rs(Nb) + Rs(Co) + Rs(Re) + Rs(Mo)) and Mi = (Ri(Co) + Ri(Re) + Ri(Mo)) / (Ri(Ti) + Ri(Nb) + Ri(Co) + Ri(Re) + Ri(Mo)).

[0041] (4) Fabrication of cutting tools The sintered bodies from Experimental Examples 1-17 were polished to the specified dimensions to produce cutting tools.

[0042] (5) Abrasion resistance performance evaluation test for carbon steel (5.1) Test conditions Cutting tests were conducted using each cutting tool. The test conditions were as follows: • Chip shape: CNMN120408T00520 ·Work material: S45C (JIS) ·Cutting speed: 500m / min • Cutting depth: 3.0 mm Feed rate: 0.4mm / rev. • Cutting environment: Dry cutting test

[0043] (5.2) Rating The evaluation results are shown in Table 2 above. In Table 2, "OK" in the "Bs / Bi≧1.1" column under "Material Properties" means that Bs and Bi satisfy the relationship Bs / Bi≧1.1, while "NG" means that Bs and Bi do not satisfy the relationship Bs / Bi≧1.1. The following criteria were used to evaluate the lifespan, based on the cutting distance until the end of the tool's life. A tool was deemed acceptable if no chipping or plastic deformation occurred after a cutting distance of 1 km. Plastic deformation was determined to have occurred if the deformation of the cutting edge exceeded 0.10 mm, using the flank as the reference surface. The amount of VB wear during machining over a cutting distance of 1 km was evaluated.

[0044] (6) Evaluation results (6.1) Composition of the bonded phase Experimental Examples 1-5 were compared and examined. Experimental Examples 1 and 3, which contained Co, Re, and Mo in the binder phase, showed no plastic deformation, and the VB wear was 0.08 mm and 0.05 mm, respectively. Experimental Example 2, which contained Co and Mo in the binder phase, showed no plastic deformation, and the VB wear was 0.09 mm. Experimental Example 4, which contained Ni, Ru, and Mo in the binder phase, showed no plastic deformation, and the VB wear was 0.07 mm. Experimental Example 5, which contained Co, Re, and W in the binder phase, showed no plastic deformation, and the VB wear was 0.09 mm. Furthermore, Experimental Examples 9-11, which had different component composition ratios in the binder phase, showed no plastic deformation. The VB wear amounts were 0.07 mm, 0.05 mm, and 0.15 mm, respectively. Experimental examples 1 to 5 all met the following requirements (a) and (b) and were deemed acceptable. Requirement (a): The bonding phase includes at least one selected from Re, Ru, Mo, and W. Requirement (b): Bs / Bi ≥ 1.1 Experimental Examples 1-5 and 9-11 demonstrated high wear resistance and high resistance to plastic deformation by satisfying the above requirements (a) and (b).

[0045] Experimental examples 11 and 12 were compared. Experimental example 11, which contained Co, Re, and Mo in the binder phase, satisfied the above requirements (a) and (b), and there was no plastic deformation. Experimental example 12, which contained Co, Re, and Mo in the binder phase, satisfied the above requirement (a) but did not satisfy requirement (b), and plastic deformation occurred. Experimental example 11 showed improved resistance to plastic deformation by satisfying the above requirements (a) and (b).

[0046] (6.2) About the composition of the sintered body Experimental examples 3, 6-8 were compared and examined. Experimental example 3, with an Ms / Mi ratio of 0.64, met requirement (c) below and had a VB wear of 0.05 mm. Experimental example 6, with an Ms / Mi ratio of 0.51, met requirement (c) below and had a VB wear of 0.04 mm. Experimental example 7, with an Ms / Mi ratio of 0.79, met requirement (c) below and had a VB wear of 0.08 mm. Experimental example 8, with an Ms / Mi ratio of 0.85, did not meet requirement (c) below and had a VB wear of 0.18 mm. ·Requirement (c)0.5≦Ms / Mi≦0.8 Experimental examples 3, 6, and 7 showed improved wear resistance by satisfying requirement (c) above.

[0047] (6.3) Regarding the amount of bonded phase Experimental Examples 3, 13-15 were compared and examined. In Experimental Example 3, where the binder phase composition ratio was 8 volume%, there was no plastic deformation and the VB wear amount was 0.05 mm. In Experimental Example 13, where the binder phase composition ratio was 10 volume%, there was no plastic deformation and the VB wear amount was 0.13 mm. In Experimental Example 14, where the binder phase composition ratio was 12 volume%, there was no plastic deformation and the VB wear amount was 0.15 mm. In Experimental Example 15, where the binder phase composition ratio was 12 volume%, plastic deformation occurred. Experimental Examples 3, 13, and 14 satisfied the above requirements (b) and (c), while Experimental Example 15 did not satisfy the above requirements (b) and (c). When the above requirements (b) and (c) were satisfied, sufficient tool performance (high wear resistance) was shown when the binder phase was in the range of 8 volume% to 12 volume%.

[0048] (6.4) About coatings Experiments 7, 16, and 17 were compared. In Experiment 7, where the sintered body was not coated, the VB wear was 0.08 mm. In Experiment 16, where the sintered body was coated, the VB wear was 0.05 mm. In Experiment 17, where the sintered body was coated, the VB wear was 0.07 mm. In Experiments 16 and 17, the wear resistance of the tool was improved by coating the sintered body.

[0049] (6.5) Summary Experimental examples 1-7, 9-11, 13, 14, 16, and 17 showed that sintered bodies and cutting tools exhibited excellent wear resistance and fracture resistance under high-speed machining conditions. Such cutting tools can improve the cutting speed in steel processing and increase the efficiency of machining.

[0050] This disclosure is not limited to the embodiments detailed above, and various modifications or changes are possible within the scope of the claims of this disclosure. [Explanation of symbols]

[0051] 1...Cutting tools 2 ... Sintered body 5 ... cross-section 5A ... one side edge 5B ...the other edge 7...Covering layer A,AR1,AR2…area

Claims

1. Hard particles mainly composed of TiN, TiC, TiCN, or (Ti, M)(C, N)(M is Ta and / or Nb), A bonded phase comprising at least one of Co and Ni, A sintered body containing, The bonded phase further comprises at least one selected from Re, Ru, Mo, and W. In the surface region of the sintered body from the surface down to a depth of 20 μm, the ratio of the total content (mass%) of Re, Ru, Mo, and W to the total content (mass%) of Co, Ni, Re, Ru, Mo, and W is defined as Bs. In the internal region of the sintered body from a depth of 1 mm from the surface to 20 μm below, Bi is defined as the ratio (mass%) of the total content (mass%) of Re, Ru, Mo, and W to the total content (mass%) of Co, Ni, Re, Ru, Mo, and W. Bs is 0.89 or less, and Bi is 0.05 or more. A sintered body that satisfies the following relation (1). Bs / Bi≧1.1…(1)

2. In the surface region of the sintered body, the content of the binder phase (mass%) relative to the total content (mass%) of the hard particles, the binder phase, and the dispersed particles is defined as Ms. In the internal region of the sintered body, the content of the binder phase (mass%) relative to the total content (mass%) of the hard particles, the binder phase, and the dispersed particles is defined as Mi. A sintered body according to claim 1 that satisfies the following relation (2). 0.5 ≤ Ms / Mi ≤ 0.8 …(2)

3. A cutting tool using the sintered body described in claim 1 or claim 2.

4. A cutting tool having a sintered body according to claim 1 or claim 2 as a base material, and a coating layer on the surface of the base material.

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