Sintered bodies and cutting tools

Abstract

To provide a sintered body and a cutting tool having excellent wear 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 Mo and W. The sintered body contains an intermetallic compound of Co and / or Ni and Mo and / or W.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 using, as a base material, cemented carbide or cermet including a hard phase mainly composed of tungsten carbide or titanium carbonitride and a binder phase mainly composed of an iron group element are known (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, cutting tools using cemented carbide or cermet as a base material generally have excellent chipping resistance. However, since a relatively low melting point metal such as Co or Ni is used in the binder phase, plastic deformation of the tool may occur under high-speed machining. Therefore, such cutting tools are not suitable for high-speed machining. Thus, by using a high melting point material in the binder phase, the wear resistance can be improved so that plastic deformation does not occur even under high-speed machining. However, considering the application to tools used in various machining methods, an improvement in chipping resistance is also required. The present disclosure has been made in view of the above circumstances, and an object thereof is to provide a sintered body and a cutting tool excellent in wear resistance and chipping resistance under high-speed machining. The present disclosure can be realized in the following forms.

Means for Solving the Problems

[0005] 〔1〕Hard particles mainly composed of TiN, TiC, TiCN, or (Ti, M)(C, N) (M is one or more selected from elements belonging to Groups 4 to 6 of the periodic table (excluding the Ti element)), 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 Mo and W. A sintered body containing an intermetallic compound of Co and / or Ni and Mo and / or W.

[0006] [2] The bonding phase is It contains only Co from Co and Ni, only Mo from Mo and W, and also contains Re. The Co content is between 45% by mass and 90% by mass. The Mo content is between 5% by mass and 50% by mass. The Re content is between 5% by mass and 50% by mass. The sintered body according to [1], wherein the total content of Co, Mo, and Re is 100% by mass.

[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, with a coating layer formed on the surface of the base material. [Effects of the Invention]

[0009] According to this disclosure, it is possible to provide a sintered body with excellent wear resistance and fracture resistance under high-speed machining conditions. By including a hard phase mainly composed of a Ti compound, which has excellent reactivity resistance to iron (Fe) and hardness, a sintered body with excellent wear resistance is obtained. Furthermore, by including at least one selected from Mo and W in the binder phase mainly composed of Co or Ni, 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 processing. In addition, by including an intermetallic compound of Co and / or Ni and Mo and / or W, the sintered body becomes a sintered body with excellent resistance to plastic deformation. If the binder phase contains only Co from among Co and Ni, only Mo from among Mo and W, and also contains Re, and the total content of Co, Mo, and Re is taken as 100%, then the Co content is 45% by mass or more and 90% by mass or less, the Mo content is 5% by mass or more and 50% by mass or less, and the Re content is 5% by mass or more and 50% by mass or less, then wear resistance and resistance to plastic deformation can be improved. 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. [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 Mo (molybdenum) and W (tungsten). The sintered body contains intermetallic compounds of Co and / or Ni and Mo and / or W.

[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 groups 4-6 of the periodic table (excluding titanium)). Here, "main component" means that when the hard particles are 100% by volume, the Ti compound accounts for 60% or more 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. The composition ratio of the elements constituting the hard particles is not particularly limited. The hard particles may be single-composition particles or particles containing multiple components (e.g., particles with a core-rim structure). The composition ratios of the elements constituting TiC, TiN, TiCN, and (Ti, M)(C, N) are not particularly limited. For example, the ratio of C and N in TiCN is not limited, C and N may be in non-stoichiometric ratios, and there may be only one type of hard particle or multiple types. The presence of multiple types means that (Ti, M)(C, N) particles with different element M exist together, as well as (Ti, M)(C, N) particles with the same element M but different composition ratios of Ti, M, C, and N constituting the particle. Note that, from the perspective of the reactivity resistance to iron contained in the workpiece, the composition ratio XC of carbon and the composition ratio XN of nitrogen preferably fall within the range of 0.10 to 0.90, more preferably within the range of 0.20 to 0.80, and even more preferably within the range of 0.30 to 0.70 in the ratio represented by (XN / (XC + XN)). From the perspective of hardness, the composition ratio XTi of titanium and the composition ratio XM of the metal element M preferably fall within the range of 0.40 to 0.95, more preferably within the range of 0.50 to 0.95, and even more preferably within the range of 0.70 to 0.95 in the ratio represented by (XTi / (XTi + XM)). The content rate (volume %) of each substance in the sintered body can be calculated by determining the amount of each element by means of fluorescent X-ray analysis or the like.

[0014] The content rate of the hard particles in the sintered body is not particularly limited. From the perspective of enhancing the wear resistance and plastic deformation resistance, when the total of the hard particles, the binder phase, and the dispersion particles described later is 100 volume %, it is preferable that the hard particles be 65 volume % or more and 95 volume % or less, more preferably that the hard particles be 75 volume % or more and 90 volume % or less, and even more preferably that the hard particles be 80 volume % or more and 85 volume % or less.

[0015] (3) Binder phase The binder phase contains at least one of Co and Ni. By including at least one of Co and Ni in the binder phase, the bonding between particles in the hard particles and the dispersion particles described later can be strengthened. Therefore, the wear resistance and defect resistance of the sintered body can be enhanced.

[0016] The binder phase further contains at least one selected from Mo and W. By including these, the high-temperature softening of the binder phase can be suppressed, so that the sintered body becomes difficult to undergo compositional deformation.

[0017] (4) Requirements regarding the binder phase The binder phase preferably contains only Co from among Co and Ni, only Mo from among Mo and W, and further preferably contains Re. Mo is dissolved in the hard particles and can enhance the fracture resistance of the sintered body as an intermediate layer between the hard particles and the binder phase. Furthermore, by further including Re, a high-melting-point metal, in the binder phase, high-temperature softening of the binder phase can be further suppressed. As a result, the sintered body becomes less susceptible to plastic deformation.

[0018] When the total content of Co, Mo, and Re is set to 100% by mass, it is preferable that the Co content is 45% to 90% by mass, the Mo content is 5% to 50% by mass, and the Re content is 5% to 50% by mass. This configuration can improve the wear resistance and plastic deformation resistance of the sintered body. In addition to Co and Mo, other impurities may be included in the binder phase.

[0019] By increasing the Co content to 45% by mass or more, fracture resistance can be improved. By increasing the Mo content to 5% by mass or more, plastic deformation resistance and wear resistance can be improved. By decreasing the Mo content to 50% by mass or less, fracture resistance can be improved. Mo is the source of Co3Mo, which will be described later. By increasing the Re content to 5% by mass or more, plastic deformation resistance and wear resistance can be improved. By decreasing the Re content to 50% by mass or less, fracture resistance can be improved.

[0020] From the viewpoint of improving wear resistance and resistance to plastic deformation, when the total of hard particles, binder phase, and dispersed particles (described later) is taken as 100% by volume, it is preferable that the binder phase is 3% to 10% by volume, and more preferably that the binder phase is 5% to 8% by volume.

[0021] (5) Intermetallic compounds The intermetallic compounds include Co and / or Ni and Mo and / or W. Specifically, the intermetallic compounds are compounds of Co and Mo, compounds of Co and W, compounds of Ni and Mo, compounds of Ni and W, compounds of Co, Ni and Mo, compounds of Co, Ni and W, compounds of Co, Mo and W, compounds of Ni, Mo and W, and compounds of Co, Ni, Mo and W. Co3Mo and Co3W are preferred as the intermetallic compounds. The sintered body can have improved resistance to plastic deformation by containing such intermetallic compounds.

[0022] (6) Particles containing Al (dispersed particles) The sintered body preferably contains dispersed particles containing Al (aluminum). The dispersed particles containing Al are dispersed within the sintered body and suppress the grain growth of hard particles. Hereinafter, the 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 5% to 20% by volume, and more preferably 5% to 10% by volume, when the entire sintered body is considered to be 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 powder (aluminum nitride powder) and Al2O3 powder (aluminum oxide powder) • Raw material powders such as Co powder, Ni powder, Re powder, Mo powder, and W powder.

[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 of the dried mixed powder, a sintered body 2 is produced by atmospheric firing. Atmospheric firing is performed under an Ar or N2 atmosphere. The formation of intermetallic compounds between Co and / or Ni and Mo and / or W is controlled by the cooling rate during firing.

[0029] 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.

[0030] 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.

[0031] 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 oxidation resistance and lubricity, Cr-based compounds (e.g., TiCrAlN, CrAlN) 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]

[0032] The present disclosure will be further described in detail below with reference to examples. Experimental Examples 1, 3, 5-19 are examples, while Experimental Examples 2 and 4 are comparative examples. In the table, experimental examples are indicated using "No.". Additionally, if an asterisk (*) is used, such as "*2", it indicates that it is a comparative example.

[0033] 1. Experimental Examples 1-19 Sintered bodies were prepared for each of Experimental Examples 1 to 19, and these sintered bodies were processed to create each of the cutting tools for Experimental Examples 1 to 19. In the compound compositions shown in Table 1, the total amount of the components included is 100% by volume. In Table 1, the compound plasticity of Experimental Example 1, "(Ti,Nb)(C,N)-9%AlN-5%(Co,Mo)", means that (Ti,Nb)(C,N), AlN, and (Co,Mo) are contained in amounts of 86% by volume, 9% by volume, and 5% by volume, respectively. In Table 1, Experimental Examples 1 and 2 do not list Re in their formulations, and therefore do not contain Re in their formulations. In Table 1, "Co / Ni" in the "Bond Phase Component Ratio" column means that either Co or Ni is included in the bond phase. Similarly, "Mo / W" means that either Mo or W is included in the bond phase. For example, in Experimental Example 1, Co is included in the bond phase, while in Experimental Example 11, Ni is included in the bond phase.

[0034] (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 Al2O3 powder: Average particle size 0.7μm 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 Mo powder: Average particle size 5.0μm or less W powder: Average particle size 5.0μm or less

[0035] (2) Preparation of sintered bodies (Experimental Examples 1-19) 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 followed by atmospheric firing. The atmospheric firing conditions were a firing temperature of 1550°C to 1750°C and an Ar or N2 atmosphere. For materials that were difficult to densify (Experimental Example 14), HIP treatment was performed as appropriate. The HIP treatment conditions were 1550°C, 150 MPa, and an Ar atmosphere. The composition (vol%), firing temperature, and heating rate for each experimental example are shown in Table 1.

[0036] The formation of intermetallic compounds between Co and / or Ni and Mo and / or W was controlled by the cooling rate during the primary calcination. Specifically, intermetallic compounds were formed by keeping the cooling rate to 15°C / min or less up to the calcination temperature of 1000°C.

[0037] [Table 1]

[0038] (3) Manufacturing of cutting tools The sintered bodies from Experimental Examples 1-19 were polished to the specified dimensions to create cutting tools. The sintered bodies from Experimental Examples 17-19 were coated.

[0039] (4) Confirmation of intermetallic compounds The obtained samples were subjected to XRD analysis on the tool surface (flank) to confirm the presence or absence of the intermetallic compounds mentioned above.

[0040] (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

[0041] (5.2) Rating The evaluation results are shown in Table 1. The following items were used as criteria for determining tool life, and the evaluation was based on the cutting distance until the tool reached the end of its life. A tool was deemed to have passed if no plastic deformation occurred by the time a cutting distance of 1 km was reached. Plastic deformation was determined to have occurred if the deformation of the cutting edge exceeded 0.10 mm, with the flank face as the reference surface. The amount of VB wear during machining over a cutting distance of 1 km was evaluated.

[0042] (6) Evaluation results (6.1) Presence or absence of intermetallic compounds Experimental Examples 1 and 2 were compared. Experimental Example 2, which lacked an intermetallic compound, underwent plastic deformation and was deemed unsatisfactory. Experimental Example 1, which contained an intermetallic compound, did not undergo plastic deformation and was deemed satisfactory. Experimental Example 2, which did not contain an intermetallic compound, showed inferior resistance to plastic deformation, while Experimental Example 1, which contained an intermetallic compound, showed improved resistance to plastic deformation.

[0043] (6.2) Composition of the bonded phase Experimental examples 1, 3, and 5-7 were compared. Experimental example 1, which did not contain Re in the binding phase, had a wear amount of 0.13 mm. Experimental examples 3, 5-7, which contained Re in the binding phase and met the following requirement (a), had a wear amount of 0.04 mm to 0.08 mm. Requirement (a): When the total content of Co, Mo, and Re is set to 100% by mass, the content of Co is 45% by mass or more and 90% by mass or less, the content of Mo is 5% by mass or more and 50% by mass or less, and the content of Re is 5% by mass or more and 50% by mass or less. By including Re in the binding phase and satisfying the above requirement (a), plastic deformation does not occur, and tool wear is reduced. (6.3) Regarding the presence or absence of dispersed particles Experimental examples 5, 8-13 were compared and examined. Experimental example 8, which did not contain dispersed particles (particles containing Al), had a wear amount of 0.15 mm. Experimental examples 5 and 13, which contained dispersed particles, had wear amounts of 0.04 mm and 0.07 mm, respectively. The sintered body showed reduced tool wear due to the inclusion of dispersed particles containing Al. Experimental Example 5, where the dispersed particles were AlN particles, showed a wear of 0.04 mm. Experimental Example 13, where the dispersed particles were Al2O3 particles, showed a wear of 0.07 mm. Including AlN particles as dispersed particles improved wear resistance compared to using Al2O3 particles. Experimental examples 5, 9, and 12, where the dispersed particle content was 9 vol%, 5 vol%, and 20 vol%, respectively, when the entire sintered body was considered as 100 vol%, showed wear amounts of 0.04 mm, 0.05 mm, and 0.09 mm, respectively. High wear resistance was observed when the dispersed particle content was between 5 vol% and 20 vol%. (6.4) Regarding the components of the bonded phase Experimental Example 9, which contained Co, Re, and Mo in the binder phase, showed a wear of 0.05 mm. Experimental Example 10, which contained Co, Re, and W in the binder phase, showed a wear of 0.10 mm. Experimental Example 11, which contained Ni, Re, and Mo in the binder phase, showed a wear of 0.09 mm. The sintered body showed high wear resistance regardless of whether it contained Co or Ni in the binder phase component. The sintered body showed high wear resistance regardless of whether it contained Mo or W in the binder phase component. (6.5) Regarding the amount of the bonded phase When the total of hard particles, binder phase, and dispersed particles is considered to be 100 volume%, experimental examples 3,14-16, where the binder phase was 5 volume%, 3 volume%, 8 volume%, and 10 volume%, respectively, showed wear amounts of 0.08 mm, 0.04 mm, 0.13 mm, and 0.16 mm. A binder phase of 3 volume% to 10 volume% demonstrated sufficient tool performance (high wear resistance).

[0044] Experimental examples 1, 3, 5-19 demonstrated 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.

[0045] 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]

[0046] 1...Cutting tools 2 ... Sintered body 7...Covering layer

Claims

1. 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 the element Ti)), A bonded phase containing Co and Mo, A sintered body containing, The aforementioned bonded phase is It contains an intermetallic compound of Co and Mo, and Re. The Co content is between 45% by mass and 90% by mass. The Mo content is between 5% by mass and 50% by mass. The Re content is between 5% by mass and 50% by mass. A sintered body having a total content of 100% by mass of Co, Mo, and Re.

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

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

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