Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23B—TURNING; BORING
  • B23B27/00—Tools for turning or boring machines; Tools of a similar kind in general; Accessories therefor
  • B23B27/14—Cutting tools of which the bits or tips or cutting inserts are of special material
  • B23B27/148—Composition of the cutting inserts
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C29/00—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides
  • C22C29/02—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides
  • C22C29/06—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides based on carbides, but not containing other metal compounds
  • C22C29/08—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides based on carbides, but not containing other metal compounds based on tungsten carbide
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
  • C23C14/0605—Carbon
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
  • C23C14/24—Vacuum evaporation
  • C23C14/32—Vacuum evaporation by explosion; by evaporation and subsequent ionisation of the vapours, e.g. ion-plating
  • C23C14/325—Electric arc evaporation
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
  • C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
  • C23C16/26—Deposition of carbon only
  • C23C16/27—Diamond only
  • C23C16/271—Diamond only using hot filaments
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
  • B22F2005/001—Cutting tools, earth boring or grinding tool other than table ware
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23B—TURNING; BORING
  • B23B2224/00—Materials of tools or workpieces composed of a compound including a metal
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C1/00—Making non-ferrous alloys
  • C22C1/04—Making non-ferrous alloys by powder metallurgy
  • C22C1/05—Mixtures of metal powder with non-metallic powder
  • C22C1/051—Making hard metals based on borides, carbides, nitrides, oxides or silicides; Preparation of the powder mixture used as the starting material therefor

Definitions

• This disclosure relates to cemented carbide and cutting tools.
• cemented carbide alloys have been used as cutting tool materials, comprising a first hard phase primarily composed of tungsten carbide (WC), a second hard phase primarily composed of a compound containing multiple metal elements including tungsten and one or more elements selected from carbon, nitrogen, oxygen, and boron, and a binder phase primarily composed of an iron-group element.
• WC tungsten carbide
• second hard phase primarily composed of a compound containing multiple metal elements including tungsten and one or more elements selected from carbon, nitrogen, oxygen, and boron
• a binder phase primarily composed of an iron-group element.
• the cemented carbide of the present disclosure is a cemented carbide consisting of a first hard phase, a plurality of second hard phases, and a binder phase, the first hard phase is composed of a plurality of tungsten carbide particles;
• the particle diameter D10 of the tungsten carbide particles is 0.40 ⁇ m or more,
• the tungsten carbide particles have a particle size D90 of 2.00 ⁇ m or less
• the second hard phase is composed of at least one first compound selected from the group consisting of TaNbC, TaNbN, TaNbCN, TiCN, TiNbC, TiNbN, and TiNbCN;
• the cemented carbide contains the second hard phase in an amount of 0.30 vol% or more and 1.60 vol% or less, In a cross section of the cemented carbide, the average circularity of the second hard phase is 0.10 or more and 0.32 or less, the standard deviation of the circularity is 0.094 or more and 0.130 or less,
• the binder phase contains 50% by mass
• FIG. 1 is a diagram illustrating a typical example of the configuration of the cemented carbide according to the first embodiment.
• FIG. 2 is a schematic cross-sectional view of a cutting tool according to a second embodiment.
• FIG. 3 is a diagram illustrating an example of a cutting tool according to the second embodiment.
• the present disclosure therefore aims to provide a cemented carbide alloy that, when used as a cutting tool material, enables the cutting tool to have a longer life, even when machining aluminum, and a cutting tool equipped with the same.
• the cemented carbide of the present disclosure is a cemented carbide consisting of a first hard phase, a plurality of second hard phases, and a binder phase, the first hard phase is composed of a plurality of tungsten carbide particles;
• the particle diameter D10 of the tungsten carbide particles is 0.40 ⁇ m or more,
• the tungsten carbide particles have a particle size D90 of 2.00 ⁇ m or less
• the second hard phase is composed of at least one first compound selected from the group consisting of TaNbC, TaNbN, TaNbCN, TiCN, TiNbC, TiNbN, and TiNbCN;
• the cemented carbide contains the second hard phase in an amount of 0.30 vol% or more and 1.60 vol% or less, In a cross section of the cemented carbide, the average circularity of the second hard phase is 0.10 or more and 0.32 or less, the standard deviation of the circularity is 0.094 or more
• This disclosure makes it possible to provide a cemented carbide alloy that, when used as a cutting tool material, enables the tool to have a longer life, even when machining aluminum.
• the cemented carbide may contain 0.08% by mass or more and 0.5% by mass or less of chromium.
• Chromium is derived from chromium carbide ( Cr3C2 ), which is used as a grain growth inhibitor in the production of cemented carbide.
• cemented carbide contains chromium within the above range, the hardness of the cemented carbide is improved, and the life of cutting tools using the cemented carbide is further improved.
• the binder phase may contain one or both of iron and nickel.
• the cutting tool of the present disclosure is a cutting tool comprising the cemented carbide alloy described in any one of (1) to (3) above.
• This disclosure makes it possible to provide cutting tools with long lifespans, even when machining aluminum.
• the cutting tool may further include a substrate made of the cemented carbide alloy and a coating formed on the substrate. This further improves the life of the cutting tool.
• a substrate made of the cemented carbide alloy and a cutting edge member fixed to the substrate may be provided. This further improves the life of the cutting tool.
• the cutting edge member may be made of cubic boron nitride sintered body or diamond. This further improves the life of the cutting tool.
• a ⁇ B means greater than or equal to A and less than or equal to B. If no unit is specified for A and only a unit is specified for B, the units for A and B are the same.
• a cemented carbide 4 is a cemented carbide 4 comprising a first hard phase 1, a plurality of second hard phases 2, and a binder phase 3,
• the first hard phase 1 is composed of a plurality of tungsten carbide particles,
• the particle diameter D10 of the tungsten carbide particles is 0.40 ⁇ m or more,
• the particle size D90 of the tungsten carbide particles is 2.00 ⁇ m or less
• the second hard phase 2 is made of at least one first compound selected from the group consisting of TaNbC, TaNbN, TaNbCN, TiCN, TiNbC, TiNbN, and TiNbCN;
• the cemented carbide 4 contains a second hard phase 2 in an amount of 0.30 vol% or more and 1.60 vol% or less, In the cross section of the cemented carbide 4, the average circularity of the second hard phase
• the cemented carbide of embodiment 1 When used as a cutting tool material, the cemented carbide of embodiment 1 enables the cutting tool to have a longer life, even when machining aluminum. The reason for this is not clear, but is presumed to be as follows.
• the average circularity of the second hard phase in the cross section of the cemented carbide is 0.10 or more and 0.32 or less, and the standard deviation of the circularity is 0.094 or more and 0.130 or less.
• the cross section of the second hard phase is not a perfect circle, and the perimeter of the second hard phase is longer than when the cross section of the second hard phase is a perfect circle. Therefore, the shape of the second hard phase is not a perfect sphere (a perfect sphere), and the surface area of the second hard phase is also larger than when the second hard phase is a perfect sphere. This improves the adhesion between the first hard phase, the second hard phase, and the binder phase. Therefore, cutting tools using the cemented carbide of embodiment 1 as a cutting tool material can suppress the expansion of tool damage caused by welding, even when machining aluminum, and can have a long tool life.
• the cemented carbide of the first embodiment is composed of a first hard phase, a plurality of second hard phases, and a binder phase.
• the cemented carbide may contain impurities as long as the effects of the present disclosure are not impaired. That is, the cemented carbide may be composed of a first hard phase, a plurality of second hard phases, a binder phase, and impurities. Examples of impurities include iron (Fe), molybdenum (Mo), calcium (Ca), silicon (Si), and sulfur (S).
• the impurity content of the cemented carbide (when there are two or more types of impurities, the total content of these impurities) may be 0% by mass or more and less than 0.1% by mass.
• the impurity content of the cemented carbide is measured by inductively coupled plasma emission spectroscopy (ICP optical emission spectroscopy). Shimadzu Corporation's "ICPS-8100" (trademark) can be used as the measuring device.
• the content of the second hard phase in the cemented carbide of embodiment 1 is 0.30% by volume or more and 1.60% by volume or less. This improves the adhesion resistance, heat resistance, and wear resistance of the cemented carbide.
• the content of the second hard phase in the cemented carbide may also be 0.40% by volume or more and 1.50% by volume or less, or 0.50% by volume or more and 1.40% by volume or less.
• the binder phase content of the cemented carbide of embodiment 1 is 8.0 vol% or more and 12.0 vol% or less. This improves the strength of the cemented carbide.
• the binder phase content of the cemented carbide may also be 8.1 vol% or more and 11.9 vol% or less, or 8.2 vol% or more and 11.8 vol% or less.
• the content of the first hard phase in the cemented carbide of embodiment 1 is the value obtained by subtracting the volumes of the second hard phase and binder phase from 100% by volume of the entire cemented carbide.
• the methods for measuring the content of the first hard phase, the content of the second hard phase, and the content of the binder phase of the cemented carbide are as follows.
• a cemented carbide alloy is cut out at an arbitrary position to expose a cross section, which is then polished to a mirror finish using a cross section polisher (manufactured by JEOL Ltd.).
• the machined surface of the cemented carbide is photographed using a scanning electron microscope (SEM) (Hitachi High-Technologies Corporation, "S-3400N” (trademark)) to obtain a backscattered electron image.
• SEM scanning electron microscope
• Six backscattered electron images are prepared. Each of the six backscattered electron images captures a different area. The location of the image can be set as desired.
• the observation conditions are a magnification of 5000x and an accelerating voltage of 10 kV.
• SEM-EDX energy dispersive X-ray analyzer
• (D1) The six backscattered electron images obtained in (B1) above are imported into a computer using image analysis software (ImageJ, version 1.51j8: https://imagej.nih.gov/ij/) and binarized to obtain six binarized images. After the images are imported, the binarization process is performed under conditions preset in the image analysis software by pressing the "Make Binary" button on the computer screen.
• the first region consisting of the first hard phase and the second region consisting of the second and third hard phases can be distinguished by the shade of color. For example, in the binarized image, the first hard phase is shown as a black region, and the second and third hard phases are shown as white regions.
• a rectangular measurement field of view measuring 25.3 ⁇ m x 17.6 ⁇ m is set in each of the six images after binarization.
• the area percentage (area %) of the first hard phase, second hard phase, and binder phase is measured for each of the six measurement fields, with the area of the entire measurement field being used as the denominator.
• the average area percentage (area %) of the first hard phase for the six measurement fields, the average area percentage (area %) of the second hard phase for the six measurement fields, and the average area percentage (area %) of the binder phase for the six measurement fields correspond to the first hard phase content (volume %), second hard phase content (volume %), and binder phase content (volume %) of the cemented carbide, respectively.
• the first hard phase is composed of a plurality of tungsten carbide particles (hereinafter also referred to as "WC particles").
• the tungsten carbide particles include not only “pure WC particles (including WC containing no impurity elements and WC with impurity elements below the detection limit)" but also "WC particles containing impurities therein, as long as the effects of the present disclosure are not impaired.”
• impurities include iron (Fe), molybdenum (Mo), and sulfur (S).
• the tungsten carbide particles have a particle size D10 of 0.40 ⁇ m or more and a particle size D90 of 2.00 ⁇ m or less, which results in a cemented carbide having high hardness and improving the wear resistance of a cutting tool containing the cemented carbide.
• the D10 of the tungsten carbide particles may be 0.42 ⁇ m or more, or 0.44 ⁇ m or more.
• the D90 of the particle size of the tungsten carbide particles may be 1.98 ⁇ m or less, or 1.96 ⁇ m or less.
• the D10 and D90 of tungsten carbide particles refer to the D10 (circle equivalent diameter at which the cumulative number-based frequency is 10%) and D90 (circle equivalent diameter at which the cumulative number-based frequency is 90%) of the equivalent area circle diameter (Heywood diameter) of the tungsten carbide particles in the cross section of the cemented carbide, respectively.
• the method for measuring D10 and D90 of tungsten carbide particles is as follows.
• (A2) Six binarized images are obtained using the same method as the method for measuring the content of the first hard phase, etc., of cemented carbide. Furthermore, to remove noise, the "Despeckle” button on the computer screen is pressed once, followed by the "Watershed” button. The grain boundaries of the first hard phase (tungsten particles) are also identified on the binarized images using the conditions preset in the image analysis software. The equivalent diameter of a circle with an area of 0.002 ⁇ m2 or more of tungsten carbide particles is measured by pressing "Analyze Particle" on the computer screen.
• this measurement method does not employ manual adjustment.
• binarization is performed by pressing the "Make Binary" button.
• the reason for measuring the equivalent-area circle diameter of tungsten carbide particles with an area of 0.002 ⁇ m2 or more is that the inventors have confirmed through measurements that particles with an area of less than 0.002 ⁇ m2 often correspond to noise that is mistakenly detected as tungsten carbide particles in image analysis.
• the second hard phase comprises at least one first compound selected from the group consisting of TaNbC, TaNbN, TaNbCN, TiCN, TiNbC, TiNbN, and TiNbCN. This improves the adhesion resistance, heat resistance, and wear resistance of the cemented carbide.
• the ratio of the total number of Ta, Nb, and Ti atoms to the total number of C and N atoms of each of TaNbC, TaNbN, TaNbCN, TiCN, TiNbC, TiNbN, and TiNbCN is not limited to 1:1, and may include any conventionally known ratio as long as it does not impair the effects of the present disclosure.
• the second hard phase may consist of one first compound selected from the group consisting of TaNbC, TaNbCN, TiCN, and TiNbCN.
• the second hard phase may contain metal elements such as tungsten (W), chromium (Cr), and cobalt (Co) to the extent that the effects of the present disclosure are not impaired.
• the total content of W, Cr, and Co in the second hard phase may be 0% by mass or more and less than 0.1% by mass.
• the contents of W, Cr, and Co in the second hard phase are measured by ICP optical emission spectrometry.
• the composition of the second hard phase is measured as follows.
• (A3) An arbitrary position of the cemented carbide is thinned using an ion slicer (apparatus: IB09060CIS (trademark) manufactured by JEOL Ltd.) to prepare a sample with a thickness of 30 to 100 nm.
• the acceleration voltage of the ion slicer is 6 kV for thinning and 2 kV for finishing.
• STEM-HAADF high-angle annular dark field
• the imaging area for the STEM-HAADF image is set to the center of the sample, i.e., a position that does not include areas with properties clearly different from the bulk portion, such as near the surface of the cemented carbide (a position where the entire imaging area is the bulk portion of the cemented carbide).
• the measurement condition is an acceleration voltage of 200 kV.
• the cemented carbide of embodiment 1 includes a plurality of second hard phases.
• Each second hard phase is composed of one first compound particle or an aggregate of a plurality of first compound particles.
• the plurality of first compound particles may be composed of one type of first compound particle or two or more types of first compound particles.
• the average circularity of the second hard phase is 0.10 or more and 0.32 or less, and the standard deviation of the circularity is 0.094 or more and 0.130 or less.
• the average circularity of the second hard phase may be 0.15 or more and 0.31 or less, or 0.17 or more and 0.30 or less.
• the standard deviation of the circularity may be 0.100 or more and 0.127 or less, or 0.110 or more and 0.124 or less.
• the average circularity of the second hard phase means the arithmetic average of the circularities of multiple second hard phases in the cross section of the cemented carbide.
• circularity is the value obtained by dividing the equivalent circular perimeter of the second hard phase in the cross section of the cemented carbide by the actual perimeter (actual perimeter) (equivalent circular perimeter/actual perimeter). A smaller circularity value indicates that the shape of the second hard phase in the cross section of the cemented carbide is more different from a perfect circle.
• the method for measuring the average circularity and standard deviation of the circularity of the second hard phase in the cross section of the cemented carbide is as follows.
• a position of the cemented carbide is cut out to expose a cross section.
• the cross section is polished using a cross-section polisher.
• the polished surface of the cemented carbide is photographed using an SEM to obtain a backscattered electron image.
• the observation conditions are a magnification of 1000x and an accelerating voltage of 10 kV.
• SEM-EDX energy dispersive X-ray analyzer
• C4 The backscattered electron image in which the second hard phases are identified is imported into a computer using image analysis software (Mac-View Version.5 (trademark) manufactured by Mountech Co., Ltd.), and the circularity of each second hard phase is measured under the following conditions. Acquisition mode: Color difference Detection tolerance: 32, Detection accuracy: 0.5 Scanning: Density 10 x 1 time High cut: Enabled [110] Low cut: Inverted [150]
• (D4) Identify three visual fields in which 30 or more second hard phases can be confirmed. Measure the average circularity and standard deviation of the circularity of the second hard phases based on all the second hard phases in the three visual fields.
• the average circularity and standard deviation of the circularity of the second hard phases measured above correspond to the average circularity and standard deviation of the circularity of the second hard phases in the cross section of the cemented carbide.
• the binder phase contains 50% by mass or more of cobalt, which allows the cemented carbide to have excellent toughness.
• the cobalt content of the binder phase may be 50% by mass or more and 100% by mass or less, 60% by mass or more and 90% by mass or less, or 70% by mass or more and 80% by mass or less.
• the method for measuring the cobalt content of the binder phase is as follows.
• the region where the binder phase exists is identified in the element mapping image using the same methods as steps (A1) to (E1) of the method for measuring the content of the first hard phase, etc., of the cemented carbide described above.
• a rectangular measurement field of view measuring 24.9 ⁇ m x 18.8 ⁇ m is set in the element mapping image.
• the cobalt content is measured in the region where the binder phase exists in the measurement field.
• the average of the cobalt contents in the regions where the binder phase exists in the six measurement fields corresponds to the cobalt content of the binder phase.
• the binder phase may contain iron (Fe), nickel (Ni), etc., to the extent that the effects of the present disclosure are not impaired.
• the binder phase may contain cobalt and one or both of nickel and iron.
• the binder phase may consist of cobalt and one or both of nickel and iron.
• the cemented carbide of embodiment 1 may contain 0.08% by mass or more and 0.5% by mass or less of chromium.
• the chromium content of the cemented carbide may be 0.10% by mass or more and 0.48% by mass or less, or 0.12% by mass or more and 0.46% by mass or less.
• the chromium content of the cemented carbide is measured by ICP atomic emission spectrometry.
• the cemented carbide of the first embodiment can be produced through, for example, a preparation step, a mixing step, a molding step, a sintering step, and a cooling step.
• raw material powders are prepared.
• raw material powders include WC powder, TaNbC powder, TaNbN powder, TaNbCN powder, TiCN powder, TiNbC powder, TiNbN powder, TiNbCN powder, NbC powder, Ta2O5 powder, TiO2 powder, Co powder, Ni powder, and Fe powder.
• These raw material powders are appropriately selected based on the target composition of the cemented carbide.
• Chromium carbide ( Cr3C2 ) powder may be prepared as a grain growth inhibitor.
• the average particle size of the tungsten carbide (WC) powder is 1.0 ⁇ m or more and 1.8 ⁇ m or less.
• the TaNbC powder, TaNbN powder, TaNbCN powder, TiCN powder, TiNbC powder, TiNbN powder, TiNbCN powder, NbC powder, Ta2O5 powder, and TiO2 powder have an average particle size of 1 ⁇ m or more and 2 ⁇ m or less. These powders are raw material powders for the second hard phase.
• the average particle size of the Co powder, Ni powder, and Fe powder may be 0.1 ⁇ m or more and 5 ⁇ m or less.
• the average particle size of the raw material powders mentioned above is determined by the Fischer method.
• ⁇ Mixing process> In the mixing process, the raw material powders are mixed in a predetermined ratio to obtain a mixed powder. The mixing ratio of each raw material powder is adjusted appropriately depending on the target cemented carbide composition. A bead mill is used for mixing. The mixing conditions are a bead diameter of 1 mm, a rotation speed of 2800 rpm, and a mixing time of 6 to 24 hours.
• the mixed powder is molded into a desired shape to obtain a molded body.
• the molding method and molding conditions are not particularly limited and may be any commonly used method and conditions.
• ⁇ Sintering process> the compact is first heated to 1450 to 1520°C and held there for 120 minutes.
• the heating rate above 1000°C is 5°C/min.
• the pressure here can be vacuum or N2 (flow rate 2 L/min, partial pressure 5 kPa).
• the compact is cooled to 1200°C at a temperature drop rate of -4.5 to -5.5°C/min to obtain a cemented carbide intermediate.
• the cemented carbide intermediate is subjected to HIP (Hot Isostatic Pressing). Specifically, the cemented carbide intermediate is subjected to a temperature of 1320°C and a pressure of 10 MPa for 60 minutes using Ar gas as the pressure medium. The cemented carbide intermediate is then slowly cooled to obtain the cemented carbide of embodiment 1.
• the temperature drop rate during slow cooling can be any general condition and is not particularly limited.
• the above mixing conditions are employed to facilitate crushing and shearing of the raw material powder. Furthermore, the heating rate at 1000°C or higher is controlled to 5°C/min, the sintering temperature is set to 1450 to 1520°C, which is higher than typical sintering temperatures, and the heating rate is controlled to -4.5 to -5.5°C/min.
• a cutting tool according to one embodiment of the present disclosure is a cutting tool comprising the cemented carbide of Embodiment 1.
• the cemented carbide of Embodiment 1 may constitute the entire tool or a part of the tool.
• Examples of cutting tools in which the cemented carbide of Embodiment 1 constitutes a part of the cutting tool include a cutting tool comprising an arbitrary substrate and a cutting edge member made of the cemented carbide of Embodiment 1 fixed to the substrate, and a cutting tool comprising a substrate made of the cemented carbide of Embodiment 1 and an arbitrary cutting edge member fixed to the substrate.
• the cutting tool of embodiment 2 has a long tool life even when machining aluminum. The reason for this is not clear, but is presumed to be as follows.
• the cutting tool of embodiment 2 which uses the cemented carbide of embodiment 1 as its cutting tool material, can suppress the expansion of tool damage caused by welding, even when machining aluminum, and can have a long tool life.
• the type of cutting tool is not particularly limited.
• Examples of cutting tools include cutting tools, drills, end mills, indexable cutting inserts for milling, indexable cutting inserts for turning, metal saws, gear cutting tools, reamers, taps, etc.
• the cutting tool 10 of embodiment 2 can demonstrate excellent effects, particularly in the case of end mills.
• the substrate 5 of the cutting tool 10 shown in Figure 2 is made of the cemented carbide of embodiment 1.
• the cutting tool of embodiment 2 may include a substrate 5 made of the cemented carbide of embodiment 1, and a coating 6 provided on the substrate 5.
• the coating may be disposed so as to cover the entire surface of the substrate, or may be disposed so as to cover only a portion of the surface.
• the coating may be disposed so as to cover only a portion of the substrate, it may be disposed so as to cover at least the surface of the portion of the substrate that is involved in cutting.
• the portion of the substrate that is involved in cutting refers to an area of the substrate that is within 0.5 mm of the cutting edge.
• the coating may be composed of a compound of one or more elements selected from the group consisting of metal elements of Groups 4, 5, and 6 of the periodic table, aluminum (Al), and silicon (Si), and one or more elements selected from the group consisting of carbon, nitrogen, oxygen, and boron. Examples include TiCN, Al2O3 , TiAlN, TiN, TiC, and AlCrN.
• the coating may also be composed of cubic boron nitride (cBN), diamond-like carbon, or diamond.
• the diamond may be either single crystal diamond or polycrystalline diamond.
• the coating may be single-layer or multi-layer.
• the thickness of the coating may be 0.1 ⁇ m or more and 20 ⁇ m or less, or 0.5 ⁇ m or more and 15 ⁇ m or less.
• the coating can be formed on the substrate using a gas-phase method such as chemical vapor deposition (CVD) or physical vapor deposition (PVD).
• CVD chemical vapor deposition
• PVD physical vapor deposition
• CVD chemical vapor deposition
• the cutting tool of embodiment 2 may include a substrate made of the cemented carbide of embodiment 1 and a cutting edge member fixed to the substrate.
• the cutting edge member may be made of cubic boron nitride sintered body or diamond.
• the diamond may be a single crystal diamond or a polycrystalline diamond.
• a cutting tool includes a substrate made of the cemented carbide of embodiment 1 and a coating provided on the substrate, The coating is made of diamond-like carbon.
• Each sample of cemented carbide was prepared according to the following procedure. ⁇ Preparation process> The raw material powders prepared were WC powder, TaNbC powder (average particle size: 1 ⁇ m), TiCN powder (average particle size: 1 ⁇ m), NbC powder (average particle size: 1 ⁇ m), Ta2O5 powder (average particle size: 1 ⁇ m), TiO2 powder (average particle size: 1 ⁇ m), Cr3C2 powder (average particle size: 1 ⁇ m), Co powder (average particle size: 1 ⁇ m), Ni powder (average particle size: 1 ⁇ m), and Fe powder (average particle size: 1 ⁇ m).
• WC powders were prepared from A.L.M.T.
• TaNbC powder was prepared from H.C. "TaNbC 67/33" manufactured by Starck was prepared so as to have an average particle size of 1 ⁇ m.
• ⁇ Mixing process> The raw material powders were mixed in a bead mill or attritor in the proportions shown in Table 1 to obtain mixed powders.
• the mixing conditions for the "bead mill” were a bead diameter of 1 mm, a rotation speed of 2800 rpm, and a mixing time of 6 hours.
• the mixing conditions for the "attritor” were a rotation speed of 250 rpm, and a mixing time of 1 hour.
• the cemented carbide intermediate was subjected to HIP treatment. Specifically, the cemented carbide intermediate was subjected to a temperature of 1320°C and a pressure of 10 MPa for 60 minutes using Ar gas as the pressure medium. It was then slowly cooled to obtain each cemented carbide sample.
• ⁇ D10 and D90 of particle size of tungsten carbide particles The particle sizes D10 and D90 of the tungsten carbide particles were measured for each cemented carbide sample. The specific measurement method is as described in embodiment 1. The results are shown in the "D10” and “D90” columns of "First hard phase” under "Cemented carbide” in Table 3.
• composition of the second hard phase in each cemented carbide sample was measured.
• the specific measurement method is as described in embodiment 1.
• the results are shown in the "Composition” column of "Second Hard Phase” in "Cemented Carbide” in Table 3.
• composition of binder phase The composition of the binder phase and the cobalt content of the binder phase were measured for each cemented carbide sample. The specific measurement method is as described in embodiment 1. The results are shown in the "Composition” and “Co Content” columns of "Binder Phase” under "Cemented Carbide” in Table 3.
• a diamond-like carbon coating was formed on the substrate using the PVD method.
• the specific coating method is as follows: The substrate was attached to the substrate holder inside the coating equipment. While argon gas was introduced into the coating equipment at a flow rate of 5 cc/min, a triangular prism-shaped target made of sintered graphite ("IG-510" manufactured by Toyo Tanso Co., Ltd.) was evaporated and ionized using vacuum arc discharge (cathode current 120 A). A voltage of -100 V was applied to the substrate holder using a bias power supply, forming a 0.5 ⁇ m-thick diamond-like carbon coating on the substrate and producing a cutting tool.
• the substrate heater was set to a temperature of 150°C at the start of coating, and the substrate heater was alternately turned on and off every 30 minutes during coating.
• a polycrystalline diamond coating of 8 ⁇ m thick was formed on the substrate by the hot filament CVD method to obtain the cutting tool (end mill) of each sample.
• Each sample end mill was used to machine the side surface of aluminum (ADC12). Machining conditions were cutting speed Vc 400 m/min, table feed F 6000 mm/min, depth of cut (axial) ap 10 mm, depth of cut (radial) ae 2 mm, and dry machining. The amount of wear was measured after 40 m of machining. The lower the amount of wear, the longer the tool life is deemed to be. The results are shown in the “Wear Amount” column under "Cutting Test” in Table 3. "Chipping occurred” in this column indicates that chipping occurred on the cutting tool before 40 m of machining had been completed, and machining was discontinued.
• the cemented carbide alloys and cutting tools of Samples 1 to 20 correspond to Examples.
• the cemented carbide alloys and cutting tools of Samples 21 to 31 correspond to Comparative Examples. It was confirmed that the cutting tools of the Examples had a longer tool life than the cutting tools of the Comparative Examples. It was confirmed that the cutting tools of the Examples were capable of stable machining for long periods of time when used to machine aluminum. It is presumed that the cemented carbide alloys used as the material for the cutting tools of the Examples had improved adhesion between the first hard phase, second hard phase, and binder phase, and therefore, the expansion of tool damage caused by welding was suppressed even when machining aluminum.
• First hard phase 2.
• Second hard phase 3.
• Binding phase 4. Cemented carbide, 5.
• Base material 6. Coating, 10. Cutting tool.

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