JP7087596B2 - Cutting tools - Google Patents

Description

The present invention relates to a cutting tool.

As a product that requires high hardness, for example, there is a cutting tool. Cemented carbide, cermet and the like are known as hard materials (sintered bodies) used in such products.

Here, cutting tools and the like are often exposed to high temperatures, and at high temperatures, wear of the sintered body is accelerated, and it may not be possible to achieve the life of the desired length of the product. Therefore, the sintered body used for cutting tools and the like is required to have wear resistance at high temperatures.

In order to impart wear resistance to cemented carbide at high temperatures, for example, Patent Document 1 (Japanese Unexamined Patent Publication No. 2014-20889) describes a sintered body containing a phase composed of hard particles such as tungsten carbide (WC). Is disclosed. Further, Patent Document 2 (Japanese Unexamined Patent Publication No. 9-125229) discloses a technique for forming a film having excellent wear resistance at high temperatures on a cemented carbide.

Japanese Unexamined Patent Publication No. 2014-208888 Japanese Unexamined Patent Publication No. 9-125229

However, recently, there is an increasing need for processing difficult-to-cut materials such as heat-resistant alloys, and improvement in cutting speed is also required. For this reason, cutting tools are being used in higher temperature environments. Even if an excellent coating as in Patent Document 1 is applied, if the cemented carbide is plastically deformed at a high temperature, the coating tends to peel off, for example, softening of the bonded phase (metal cobalt, etc.) in the sintered body, etc. As a result, the wear resistance is rapidly reduced, and the cemented carbide reaches the end of its life soon. Therefore, the technique of Patent Document 1 is not sufficient for such a need. Therefore, it is desired to further improve the plastic deformation resistance of the base material of the sintered body itself at high temperatures.

Therefore, an object of the present disclosure is to provide a cutting tool having improved plastic deformation resistance at high temperatures.

The cutting tool according to one aspect of the present disclosure includes a sintered body including a first hard phase and a bonded phase. The first hard phase consists of WC. The bonded phase contains a first metal consisting of at least one selected from Co and Ni as a main component, and further contains a second metal consisting of at least one selected from Al and W, and C.

According to the above, it is possible to provide a cutting tool having improved plastic deformation resistance at high temperatures.

FIG. 1 is a reference diagram relating to the evaluation of cutting edge damage of a cutting tool after use. FIG. 2 is a cross-sectional view taken along the line AA'of FIG.

[Explanation of Embodiments of the present disclosure]
First, embodiments of the present disclosure will be listed and described.

In this specification, the notation in the form of "A to B" means the upper and lower limits of the range (that is, A or more and B or less), and there is no description of the unit in A and the unit is described only in B. , The unit of A and the unit of B are the same.

[1] The cutting tool according to one aspect of the present disclosure includes a sintered body including a first hard phase and a bonded phase. The first hard phase consists of WC. The bonded phase contains a first metal consisting of at least one selected from Co and Ni as a main component, and further contains a second metal consisting of at least one selected from Al and W, and C. The sintered body has improved plastic deformation resistance at high temperatures. By improving the plastic deformation resistance of the sintered body at high temperatures, it is possible to extend the life of the cutting tool.

[2] The bound phase preferably contains a compound phase represented by the following formula.
(Co, Ni) _x (Al, W) _y C _z
[In the formula, (Co, Ni) is at least one selected from Co and Ni, (Al, W) is at least one selected from Al and W, and x, y and z are atomic weight ratios. Is. ] As a result, the sintered body is further suppressed from being strained at a high temperature, and is less likely to be plastically deformed.

[3] It is preferable that x is 0.65 or more and 0.95 or less, y is 0.04 or more and 0.30 or less, and z is 0.003 or more and 0.15 or less. This is because the plastic deformation resistance of the sintered body at high temperature is improved.

[4] It is preferable that x is 0.75 or more and 0.85 or less, y is 0.08 or more and 0.26 or less, and z is 0.01 or more and 0.085 or less. This is because the plastic deformation resistance of the sintered body at high temperature is improved.

[5] It is preferable that x is 0.77 or more and 0.83 or less, y is 0.14 or more and 0.20 or less, and z is 0.015 or more and 0.045 or less. This is because the plastic deformation resistance of the sintered body at high temperature is improved.

[6] The sintered body preferably further contains a second hard phase. The second hard phase is selected from one or more metals selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo and W, and 1 selected from the group consisting of nitrogen, carbon, boron and oxygen. It is composed of a compound consisting of more than a kind of element and a solid solution of the compound (excluding WC). Here, the volume of the first hard phase is larger than the volume of the second hard phase. This is because the inclusion of the second hard phase further improves the plastic deformation resistance of the sintered body at high temperatures.

[7] The ratio of the mass of O to the mass of C contained in the sintered body is preferably less than 0.015. This is because the improvement of the plastic deformation resistance of the sintered body at a high temperature is further improved.

[8] The oxygen content in the sintered body is preferably less than 0.1% by mass. This is because the improvement of the plastic deformation resistance of the sintered body at a high temperature is further improved.

[9] The coupled phase preferably has a lattice constant of 3.65 Å or more and 4.0 Å or less. This is because the plastic deformation resistance of the sintered body at high temperature is further improved.

[10] The WC preferably has an average particle size of 0.1 μm or more and 5 μm or less. This is because the plastic deformation resistance of the sintered body at high temperature is further improved.

[11] The content of the bonded phase in the sintered body is preferably 2% by mass or more and less than 10% by mass. This is because the plastic deformation resistance of the sintered body at high temperature is further improved.

[12] The sintered body preferably does not contain alumina. This is because the plastic deformation resistance of the sintered body at high temperature is further improved.

[Details of Embodiments of the present disclosure]
Hereinafter, embodiments of the present disclosure (hereinafter referred to as “the present embodiment”) will be described. However, the following description does not limit this disclosure. Further, when a compound or the like is represented by a chemical formula in the present specification, it is intended to include all conventionally known atomic ratios when the atomic ratio is not particularly limited, and is not necessarily limited to those in the stoichiometric range.

<Cutting tool>
The cutting tool according to this embodiment includes the following sintered body. The cutting tools include drills, end mills, replaceable cutting tips for drills, replaceable cutting tips for end mills, replaceable cutting tips for milling, replaceable cutting tips for turning, metal saws, and gear cutting tools. , Reamers, taps, etc. can be exemplified.

Further, the surface of the sintered body may be provided with a coating film. This makes it possible to impart the characteristics of the coating in the cutting tool.

As the coating film, it is preferable to use a coating film having a coefficient of thermal expansion of 7 × 10 ^-6 / K or more and 9 × 10 ^-6 / K or less, and Ti, Al, Cr, Si, Hf, Zr, Mo, Nb, Ta. , V and W are more preferably composed of one or more metal nitrides or carbon nitrides selected from the group.

Further, the coating film preferably has an oxidation resistance of 1000 ° C. or higher. Here, "having an oxidation resistance of 1000 ° C. or higher" means that the coating layer is evaluated in the atmosphere by a thermal analysis-differential thermal analysis (TG / DTA: Thermogravimetry / Differential Thermal Analysis) device. It means that the temperature at which the weight increase occurs is 1000 ° C. or higher. Preferable examples of the composition constituting such an oxidation-resistant coating layer include AlTiSiN, AlCrN, TiZrSiN, CrTaN, HfWSiN, CrAlN and the like.

The film as described above can be formed by either the PVD method or the CVD method, but it is preferably formed by the PVD method. In this case, it is possible to form a film that is more dense and less likely to crack. In particular, it is preferable to use the cathode arc ion plating method in that the adhesion between the coating film and the sintered body is significantly improved.

<Sintered body>
The sintered body according to the present embodiment includes a first hard phase and a bonded phase. The sintered body may contain components other than these as long as they are contained. The first hard phase consists of WC.

The bonded phase contains a first metal consisting of at least one selected from Co and Ni as a main component, and further contains a second metal consisting of at least one selected from Al and W, and C. The "main component" means the component having the largest blending ratio (mass%) among the components constituting the bonded phase. As described above, the sintered body contains C in the bonded phase. For this reason, the solid solution strengthening improves the plastic deformation resistance of the bonded phase, makes it difficult for the coating film applied to the sintered body to peel off, and improves the wear resistance of the cutting tool at high temperatures.

Further, in a cemented carbide composed of a hard phase and a bonded phase, the bonded phase is composed of a heat-resistant alloy (Co-based superalloy, Ni-based superalloy, etc.) instead of metal Co. Heat-resistant alloys are materials used in parts used at high temperatures, such as jet engines and gas turbines, and have excellent heat resistance at high temperatures.

The first hard phase and the bonded phase are preferably contained in a dispersed state in the sintered body. This improves the plastic deformation resistance of the sintered body at high temperatures. Here, the dispersed state means that the first hard phase and the bonded phase are in contact with each other and exist in the sintered body in a state where the contact between the phases of the same type is relatively small.

The bound phase preferably contains a compound phase represented by the following formula.
(Co, Ni) _x (Al, W) _y C _z
[In the formula, (Co, Ni) is at least one selected from Co and Ni, (Al, W) is at least one selected from Al and W, and x, y and z are atomic weight ratios. Is. ]
Such a sintered body is formed in the bonded phase [in the matrix phase (γ phase) composed of the first metal (Co, Ni) and the second metal (Al, W)] in (Co, Ni) _x (Al, W) By including the compound _phase represented by _yCz , strain is suppressed and plastic deformation is less likely to occur.

It is preferable that x is 0.65 or more and 0.95 or less, y is 0.04 or more and 0.30 or less, and z is 0.003 or more and 0.15 or less. This is because the plastic deformation resistance of the sintered body at high temperature is improved.

It is preferable that x is 0.75 or more and 0.85 or less, y is 0.08 or more and 0.26 or less, and z is 0.01 or more and 0.085 or less. This is because the plastic deformation resistance of the sintered body at high temperature is improved.

It is preferable that x is 0.77 or more and 0.83 or less, y is 0.14 or more and 0.20 or less, and z is 0.015 or more and 0.045 or less. This is because the plastic deformation resistance of the sintered body at high temperature is improved.

The sintered body preferably further contains a second hard phase. The second hard phase is selected from one or more metals selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo and W, and 1 selected from the group consisting of nitrogen, carbon, boron and oxygen. It is composed of a compound consisting of more than a kind of element and a solid solution of the compound (excluding WC). Here, the volume of the first hard phase is larger than the volume of the second hard phase.

By including the second hard phase, the sintered body is further solid-solved and strengthened, and has excellent plastic deformation resistance. Since the bonded phase has a higher affinity with the first hard phase than the second hard phase, the volume ratio of the first hard phase is larger than that of the second hard phase, so that the plasticity resistance of the sintered body is deformed. More improvement is expected.

The ratio of the mass of O to the mass of C contained in the sintered body (O / C ratio) is preferably less than 0.015. When this range is exceeded, alumina (Al ₂ O ₃ ) is precipitated in the bonded phase, the composition in the bonded phase changes, and the compound phase of (Co, Ni) _x (Al, W) _{yC z} is sufficient. There is a possibility that the precipitating property will not be deposited and the plastic deformability of the sintered body will be reduced. Therefore, it is preferable that alumina does not precipitate. When the O / C ratio is in the above range, improvement in the plastic deformation resistance of the sintered body is expected.

The oxygen content in the sintered body is preferably less than 0.1% by mass. When the oxygen content is 0.1% by mass or more, alumina precipitates, the composition in the bonded phase changes, and the compound phase of (Co, _Ni ) _x (Al, W) _yCz is sufficiently precipitated. There is a possibility that the plastic deformability of the sintered body will be reduced. Therefore, it is preferable that alumina does not precipitate. When the oxygen content is in the above range, improvement in the plastic deformation resistance of the sintered body is expected.

The coupled phase preferably has a lattice constant of 3.65 Å or more and 4.0 Å or less. When the lattice constant of the bonded phase is 3.65 Å or more, C is solid-dissolved and strain is generated, so that the plastic deformation resistance is improved at a higher temperature. If the lattice constant of the bonded phase is larger than 4.0 Å, the strain may increase, cracks may occur in the bonded phase, and the plastic deformation resistance may decrease. Therefore, when the lattice constant of the bonded phase is within the above range, the effect of improving the plastic deformation resistance of the sintered body is further expected.

The WC preferably has an average particle size of 0.1 μm or more and 5 μm or less. When the average particle size is 0.1 μm or less, the hard phase tends to move, and the plastic deformation resistance may decrease. On the other hand, when the average particle size is 5 μm or more, the bonded phase may become thick and a pool of bonded phases may occur, resulting in a decrease in plastic deformation resistance. Therefore, when the average particle size of the WC is in the above range, the effect of improving the plastic deformation resistance of the sintered body is expected more.

The content of the bonded phase in the sintered body is preferably 2% by mass or more and less than 10% by mass. If the content of the bonded phase is less than 2% by mass, the sinterability is lowered and plastic deformation may occur. When the content of the bonded phase is more than 10% by mass, the bonded phase may become thick and the plastic deformation resistance may decrease. Therefore, when the content of the bonded phase in the sintered body is within the above range, the effect of improving the plastic deformation resistance of the sintered body is further expected.

The sintered body contains a hard phase (first hard phase and second hard phase) and a bonded phase (alloy powder), and a hard phase (first hard phase and second hard phase) or a bonded phase. The volume content, the average particle size of the WC (first hard phase), the composition of the bound phase, and the like can be confirmed as follows.

First, a sample containing an arbitrary cross section of the sintered body is prepared. A focused ion beam device, a cross-section polisher device, or the like can be used to prepare the cross section. Next, the processed cross section is imaged with a SEM (Scanning Electron Microscope) at a magnification of 10000 to obtain an electronic image for 10 fields of view. Next, element mapping is performed for a predetermined region (12 μm × 9 μm) in each electronic image using the attached EPMA (Electron Probe Micro-Analysis) or EDX (Energy Dispersive X-ray spectroscopy).

Based on the obtained element mapping, the region containing WC is set as the first hard phase, the region does not contain WC, and the region contains the first metal (Ni, Co) and the second metal (Al, W) and C. The region is the binding phase. This confirms that the sintered body contains a hard phase (first hard phase and second hard phase) and a bonded phase. Further, the composition of the bonded phase and the ratio (volume%) of the bonded phase in the sintered body are determined from the element mapping. Depending on the sintering conditions, there may be pores in addition to the hard phase and the bonded phase.

Further, the image analysis software (“Mac-View I”, manufactured by Mountech Co., Ltd.) calculates the average particle size of WC scattered in the sintered body. The value is an average value of the results analyzed in 10 fields of view.

Further, the composition of the compounds constituting the hard phase (first hard phase and the second hard phase) and the respective proportions (% by mass) of the WC (first hard phase) and the compound are obtained by pulverizing the sintered body and emitting ICP light. It can be confirmed by determining the content ratio of each element in the pulverized product by the spectroscopic analysis method and calculating the composition ratio of each component based on this.

The content ratio of WC in the sintered body is relatively high, and therefore, there are many regions where the WCs are adjacent to each other. Adjacent WCs can be distinguished from each other by the result of element mapping and the backscattered electron image obtained from the SEM image. This is because the difference in color (shading) due to the difference in the crystal orientation of each WC is observed in the backscattered electron image.

<Manufacturing of sintered body>
In one embodiment of the present disclosure, first, a first metal (Co, Ni) and a second metal (Al, W) are used as raw materials, and a bonded phase is prepared by atomization, arc melting, plasma treatment, or the like.

When preparing the bonded phase powder, V, Ti, Nb, Ta, B, C or the like may be added in addition to the first metal (Co, Ni) and the second metal (Al, W). ..

The obtained bonded phase is pulverized by, for example, a bead mill, a ball mill, a jet mill, or the like to obtain a bonded phase powder. The average particle size of the bound phase powder is preferably 0.3 to 3 μm. Examples of the beads or balls used in the bead mill or ball mill include beads or balls made of alumina, silicon nitride, or cemented carbide having a particle size of 0.1 to 3 mm, and examples of the dispersion medium include ethanol, acetone, and liquid nitrogen. And so on. The processing time by the bead mill or the ball mill is, for example, 30 minutes to 200 hours. The slurry obtained by a bead mill or a ball mill is dried in a vacuum, for example, so as not to be oxidized. As another method, when pulverizing with a jet mill, the bonded phase powder can also be obtained by using argon gas as the pulverizing gas source. At this time, the amount of oxygen in the obtained bonded phase powder is not particularly limited, but is preferably 6% by mass or less.

Next, the obtained bonded phase powder is mixed with a separately prepared WC powder and, if necessary, a second hard phase powder by an attritor, a ball mill, a mortar and the like. At this time, an appropriate amount of C is added in consideration of the amount of C contained in the bound phase.

The mixing is carried out, for example, in an argon atmosphere in a closed state or a state close to closed. This can prevent the powder from oxidizing during mixing. From the viewpoint of uniformly dispersing the bonded phase in the sintered body (hard material), the mixing time is preferably 6 to 20 hours.

Examples of the ball used in the ball mill include balls made of alumina, silicon nitride or cemented carbide having a diameter of 3 mm, and examples of the dispersion medium include ethanol, acetone, liquid nitrogen and the like. The processing time by the ball mill is, for example, 3 to 20 hours. A mixed powder can be obtained by, for example, drying the slurry obtained by mixing in a vacuum.

The obtained mixed powder is placed in, for example, a cemented carbide mold (Ta capsule or the like) and pressed to obtain a pressure molded product. The press pressure is preferably 10 MPa to 16 GPa, for example 100 MPa. Next, the pressure molded product is sintered under a hydrogen atmosphere. The sintering temperature is preferably 1000 to 1800 ° C. The sintering time is, for example, about 1 hour. Here, for example, by setting the keep time at 400 ° C. to 30 minutes to 5 hours at the time of sintering, C contained in the molded product is desorbed, and finally the mass of C contained in the sintered body is obtained. The ratio of the mass of O to the mass (C / O ratio) is controlled to be a desired value. As a result, the first hard phase (WC) and the bonded phase are densely sintered, and a sintered body having improved plastic deformation resistance at high temperatures can be formed.

Further, the cooling rate after sintering is set to, for example, 2 to 20 ° C./min. As a result, the compound phase represented by the following formula is precipitated.
(Co, Ni) _x (Al, W) _y C _z
[In the formula, (Co, Ni) is the first metal, (Al, W) is the second metal, and x, y and z are atomic weight ratios. ]
Then, for example, a sintered body (alloy) can be obtained by performing a hot isostatic pressing (HIP: Hot Isostatic Pressing) treatment at 1400 ° C. under the condition of 1000 atm for 1 hour.

The average particle size (particle size) of WC is preferably 0.1 to 10 μm, and the content of WC in the sintered body (hard material) is preferably 50 to 99% by volume. This is because it is expected that the plasticity deformability of the obtained sintered body will be higher in the case of such a particle size range and a composition range. The average particle size of WC can be measured by the method using the above-mentioned element mapping and image analysis software.

Further, the sintered body of the present embodiment may contain unavoidable impurities (B, N, O, etc.) as long as the effects of the present disclosure are not impaired. Further, the sintered body of the present embodiment may contain an abnormal layer called a free carbon or an η phase in its structure.

Hereinafter, the present disclosure will be described in more detail with reference to examples, but the present disclosure is not limited thereto.

(Making a sintered body)
<Examples 1 to 31>
A metal powder was mixed with a composition of 42.5Co-40Ni-10W-7.5Al (atomic%), and a bonded phase was prepared by an atomizing method. In Examples 1 to 31, the same metal powder was used.

The obtained bonded phase was pulverized by a closed bead mill pulverizer using a carbide ball having a particle size of 1 μm. At this time, pulverization was performed in an argon atmosphere so that the slurry would not be oxidized. The obtained slurry was dried in vacuum to obtain a bound phase powder.

The obtained bonded phase powder and the hard particles (first hard phase and second hard phase) and carbon (C) powder having the compositions shown in Table 1 were combined with a ball made of cemented carbide having a diameter of 3.5 mm. Together with ethanol, it was poured into an attritor under an argon atmosphere and mixed. The mixing time of the attritor is as shown in Table 1. The obtained slurry was dried in vacuum to obtain a mixed powder.

The mixed powder was filled in a mold made of cemented carbide and pressed at a pressure of 100 MPa to obtain a pressure molded product.

This pressure molded product was sintered at 1450 ° C. for 1 hour. At this time, by setting the keep time of 400 ° C. in a hydrogen atmosphere as shown in Table 1, C contained in the molded product is desorbed, and finally the O / C ratio contained in the sintered body is shown in Table 2. It was controlled to be. Further, the cooling rate was adjusted as shown in Table 1. As a result, a compound phase represented by (Co, _Ni ) _x (Al, W) _yCz was precipitated.

Then, a sintered body (hard material) was obtained by performing a hot isostatic pressing (HIP: Hot Isostatic Pressing) treatment at 1400 ° C. under the condition of 1000 atm for 1 hour.

<Comparative Examples 1 and 2>
A mixed powder was obtained without adding the carbon (C) powder to the bound phase powder. The sintering conditions were vacuum and 1450 ° C. for 1 hour. The compounding ratio of the bonded phase and other sintering conditions were as shown in Table 1. A sintered body was obtained in the same manner as in Examples except for the above points.

<Comparative Example 3>
Instead of the metal powder of 42.5Co-40Ni-10W-7.5Al (atomic%), the metal Co powder having a particle size of 1.2 μm was used. The compounding ratio of the bound phase and the preparation conditions were as shown in Table 1. Other than that, a sintered body was obtained in the same manner as in Comparative Example 1.

<Evaluation of physical properties of sintered body>
The sintered body contains a hard phase (first hard phase and second hard phase) and a bonded phase (alloy powder), and contains a volume of the hard phase (first hard phase and second hard phase) or the bonded phase. The rate, the average particle size of WC, the composition of the bound phase and the like were measured in the same manner as in the method described in the above-described embodiment.

The amount of oxygen and the amount of C in the sintered body were measured by pulverizing the sintered body and ICP emission spectroscopic analysis.

The lattice constant of the bound phase was identified by EDS analysis and electron diffraction image in the limited field of view of TEM observation. As the TEM, JEM-2100F / Cs (manufactured by JEOL Ltd.) was used. CESCOR (manufactured by CEOS) was used as a Cs collector. As an EDS machine, a JED2300 Series dry SD60GV detector (manufactured by JEOL Ltd.) was used. The TEM observation conditions were an acceleration voltage of 200 kV and a probe size of 0.13 nm.

(Manufacturing of cutting tools)
The sintered body (hard material) obtained in each of the above Examples and Comparative Examples was cut by wire electric discharge machining and finished to produce a cutting tool having a tip nose R of 0.8 mm. The surface of the cutting tool was coated with a film (thickness: 3 μm) made of Al _0.6 Ti _0.35 Si _0.05 N by the PVD method.

<Evaluation of cutting tools>
For each of the cutting tools of each example and each comparative example produced above, a cutting test was performed on an NC lathe using Inconel (registered trademark) 718 (trade name, manufactured by Inconel) as a work material under the following cutting conditions. The amount of plastic deformation (μm) of the flank of the cutting tool after cutting 3 km was measured.
Cutting speed: 60m / min Cutting amount: 0.2mm
Feed amount: 0.1 mm / rev
Cutting oil: Yes

<Measuring method of plastic deformation of tool after cutting>
It was processed so that the cross section of the cutting edge of 0.1 mm could be observed from the cutting edge. A focused ion beam device, a cross-section polisher device, and the like were used for processing. The machined cross section was observed by SEM, and the amount of deformation (plastic deformation amount) plastically deformed by cutting from the side not affected by cutting was measured by the dimension measurement function attached to the SEM device (Figs. 1 and 1). 2). The measurement results are shown in the evaluation result column of Table 2.

From the results shown in Table 2, it can be seen that the cutting tools of the present disclosure, Examples 1 to 31, have improved plastic deformation resistance at high temperatures as compared with Comparative Examples. In addition, in the cutting tool of the comparative example, peeling of the coating film was confirmed.

Compared with Examples 1 to 11, the examples other than Examples 1 to 11 had further improved plastic deformation resistance. From this result, the binding phase is expressed in the formula:
(Co, Ni) _x (Al, W) _y C _z
[In the formula, (Co, Ni) is the first metal, (Al, W) is the second metal, and x, y and z are atomic weight ratios. ]
When the compound phase represented by is contained, x is 65 atomic% or more and 95 atomic% or less, y is 4 atomic% or more and 30 atomic% or less, and z is 0.3 atomic% or more and 15 atomic% or less. When the following, it can be seen that the plastic deformation resistance at high temperature is further improved. Further, when x is 75 atomic% or more and 85 atomic% or less, y is 8 atomic% or more and 26 atomic% or less, and z is 1.0 atomic% or more and 8.5 atomic% or less, at high temperature. It can be seen that the plastic deformation resistance is further improved. Further, when x is 77 atomic% or more and 83 atomic% or less, y is 14 atomic% or more and 20 atomic% or less, and z is 1.5 atomic% or more and 4.5 atomic% or less, the plastic deformation resistance at high temperature is high. Can be seen to be the most improved.

From the results of Example 31, it can be seen that when the sintered body contains the second hard phase, the plastic deformation resistance is improved. Further, from the results of Examples 12 and 13, even when the sintered body contains the second hard phase, the plasticity resistance at a high temperature is particularly high when the volume of the first hard phase is larger than the volume of the second hard phase. It can be seen that the deformability is improved.

From the results of Examples 14 and 15, it can be seen that when the ratio of the mass of O to the mass of C contained in the sintered body (O / C ratio) is small, the plastic deformation resistance at high temperature is further improved. .. Further, from the results of Examples 16 and 17, it can be seen that the plastic deformation resistance at high temperature is further improved when the oxygen content (alloy oxygen content) in the sintered body is small. This is thought to be because alumina is likely to precipitate when the O / C ratio is large or the amount of alloy oxygen is large.

From the results of Examples 18 and 19 and the results of Examples 29 and 30, when the lattice constant of the bonded phase is 3.65 Å or more and 4.0 Å or less, the plastic deformation resistance of the sintered body at high temperature is high. It turns out to be more improved. If the lattice constant of the bonded phase is small, the solid solution strengthening by C will be small, and if the lattice constant of the bonded phase is too large, the strain due to the solid solution of C will be large, and cracks will occur in the bonded phase and defects will easily occur. It is thought that this is because.

From the results of Examples 20 and 21 and the results of Examples 27 and 28, when the average particle size of WC is 0.1 μm or more and 5 μm or less, the plastic deformation resistance of the sintered body at high temperature is further improved. You can see that it does. It is considered that this is because when the average particle size of WC is small, the toughness of the sintered body is lowered and chipping is likely to occur. On the other hand, if the average particle size of the WC is too large, the strength of the sintered body is lowered and defects are likely to occur.

From the results of Examples 22 to 26, it can be seen that when the content of the bonded phase is 2% by mass or more and less than 10% by mass, the plastic deformation resistance of the sintered body at high temperature is most improved. This is because if the content of the bonded phase is too low, the toughness of the sintered body is lowered and defects are likely to occur, and if the content of the bonded phase is too high, the plastic deformation resistance of the sintered body is likely to be lowered. it is conceivable that.

The embodiments and examples disclosed this time should be considered to be exemplary in all respects and not restrictive. The scope of the present disclosure is shown by the scope of claims rather than the embodiments described above, and is intended to include the meaning equivalent to the scope of claims and all modifications within the scope.

Claims (9)

A cutting tool containing a sintered body containing a first hard phase and a coupled phase.
The first hard phase consists of WC.
The bonded phase contains a first metal consisting of at least one selected from Co and Ni as a main component, and further contains a second metal consisting of at least one selected from Al and W, and C. fruit,
The bound phase contains a compound phase represented by the following formula.
(Co, Ni) _x (Al, W) _y C _z
[In the formula, (Co, Ni) is at least one selected from Co and Ni, (Al, W) is at least one selected from Al and W, and x, y and z are atomic weight ratios. Is. ]
A cutting tool in which x is 0.75 or more and 0.85 or less, y is 0.08 or more and 0.26 or less, and z is 0.01 or more and 0.085 or less . The cutting tool according to claim 1 , wherein x is 0.77 or more and 0.83 or less, y is 0.14 or more and 0.20 or less, and z is 0.015 or more and 0.045 or less. .. The sintered body further contains a second hard phase.
The second hard phase is selected from the group consisting of one or more metals selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo and W, and the group consisting of nitrogen, carbon, boron and oxygen. It consists of one or more elements and a compound consisting of, or a solid solution of the compound (excluding WC).
The cutting tool according to claim 1 or 2, wherein the volume of the first hard phase is larger than the volume of the second hard phase. The cutting tool according to any one of claims 1 to 3 , wherein the ratio of the mass of O to the mass of C contained in the sintered body is less than 0.015. The cutting tool according to any one of claims 1 to 4 , wherein the oxygen content in the sintered body is less than 0.1% by mass. The cutting tool according to any one of claims 1 to 5 , wherein the coupled phase has a lattice constant of 3.65 Å or more and 4.0 Å or less. The cutting tool according to any one of claims 1 to 6 , wherein the WC has an average particle size of 0.1 μm or more and 5 μm or less. The cutting tool according to any one of claims 1 to 7 , wherein the content of the bonded phase in the sintered body is 2% by mass or more and less than 10% by mass. The cutting tool according to any one of claims 1 to 8 , wherein the sintered body does not contain alumina.

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