WO2024005036A1 - 炭化タングステン粉末 - Google Patents

炭化タングステン粉末 Download PDF

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Publication number
WO2024005036A1
WO2024005036A1 PCT/JP2023/023878 JP2023023878W WO2024005036A1 WO 2024005036 A1 WO2024005036 A1 WO 2024005036A1 JP 2023023878 W JP2023023878 W JP 2023023878W WO 2024005036 A1 WO2024005036 A1 WO 2024005036A1
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WIPO (PCT)
Prior art keywords
tungsten carbide
tungsten
powder
crystal grains
vanadium
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PCT/JP2023/023878
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English (en)
French (fr)
Japanese (ja)
Inventor
貴彦 牧野
志賢 青木
直樹 岩井
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Kyocera Corp
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Kyocera Corp
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Priority to JP2024530897A priority Critical patent/JPWO2024005036A1/ja
Publication of WO2024005036A1 publication Critical patent/WO2024005036A1/ja
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/90—Carbides
    • C01B32/914—Carbides of single elements
    • C01B32/949—Tungsten or molybdenum carbides

Definitions

  • the disclosed embodiments relate to tungsten carbide powder.
  • tungsten carbide is a component of superhard alloys such as cemented carbide, is used together with cobalt, niobium, etc., and is often used in cutting tools and the like.
  • the metal tungsten contained in tungsten carbide has a high melting point, it is used in a variety of applications such as heating elements, structural members, catalysts for the petrochemical industry, environmental equipment, wiring for ceramic wiring boards, and heat dissipation materials. ing. In order to effectively utilize these resources, a method of recycling tungsten from waste materials (scrap) has been devised (see Patent Document 1).
  • the tungsten carbide powder of the present disclosure includes powder whose main component is tungsten carbide crystal grains.
  • the secondary ion intensity of vanadium ( The intensity ratio (V/W) between V) and the secondary ion strength (W) of tungsten is 0.05 or more.
  • FIG. 1 is a diagram showing the structure of tungsten carbide crystal grains according to an embodiment.
  • FIG. 2 is a flowchart illustrating an example of a procedure of a tungsten carbide generation process according to the embodiment.
  • FIG. 3 is a flowchart illustrating an example of the procedure of the tungsten carbide generation process in the reference example.
  • FIG. 4 is a diagram showing the depth distribution of the intensity ratio (V/W) between the secondary ion strength (V) of vanadium and the secondary ion strength (W) of tungsten in tungsten carbide powder.
  • tungsten carbide is a component of superhard alloys such as cemented carbide, is used together with cobalt, niobium, etc., and is often used in cutting tools and the like.
  • the metal tungsten contained in tungsten carbide has a high melting point, it is used in a variety of applications such as heating elements, structural members, catalysts for the petrochemical industry, environmental equipment, wiring for ceramic wiring boards, and heat dissipation materials. ing. In order to effectively utilize these resources, methods have been devised to recycle tungsten from waste materials (scrap).
  • the tungsten carbide powder according to the embodiment includes powder whose main component is tungsten carbide crystal grains 1 (see FIG. 1).
  • the tungsten carbide powder according to the embodiment includes powder consisting of tungsten carbide crystal grains 1 and inevitable impurities.
  • the intensity ratio (V/W) between the secondary ion strength (V) of vanadium and the secondary ion strength (W) of tungsten may be 0.05 or more.
  • cemented carbide since it is possible to generate cemented carbide by low-temperature firing, cemented carbide can be efficiently produced. Further, in the embodiment, since the crystals are finely densified when producing the cemented carbide, a cemented carbide with a small amount of deformation can be obtained.
  • the secondary ion strength (V) of vanadium and the tungsten may be 0.30 or more.
  • cemented carbide can be produced more efficiently. Furthermore, in the embodiment, a cemented carbide with even less deformation can be obtained.
  • FIG. 1 is a diagram showing the structure of tungsten carbide crystal grains 1 according to an embodiment.
  • a powder mainly composed of tungsten carbide crystal grains 1 includes a combined body 2 having a plurality of tungsten carbide crystal grains 1.
  • the atomic ratio of vanadium may be 1 (at%) or less in the grain boundaries 1b of the plurality of tungsten carbide crystal grains 1 in the combined body 2.
  • Tungsten carbide crystal grains 1 have the property that grain growth is reduced in areas with a high vanadium content. 1b tends to be the starting point for grain growth.
  • the outermost surface 1a of the tungsten carbide crystal grains 1 has a relatively high vanadium content as described above, it is difficult to become a starting point for grain growth.
  • the combined body 2 has a mixture of places that are likely to become the starting point of grain growth and places that are difficult to start grain growth.
  • a mixed structure of coarse grains and fine grains is likely to be formed.
  • FIG. 2 is a flowchart illustrating an example of a procedure for producing tungsten carbide powder according to the embodiment. As shown in FIG. 2, in the tungsten carbide powder production process according to the embodiment, first, cemented carbide scrap was prepared.
  • Cemented carbide which is a type of superhard alloy, is mainly composed of composite carbides such as tungsten metal and tungsten carbide, and has a binder phase of iron, nickel, cobalt, etc., and optionally contains TiC, TaC, NbC, etc. as additive components. Contains VC, Cr3C2 , etc.
  • Materials to be treated containing cemented carbide include, for example, cutting tools (cutting inserts, drills, end mills, etc.), molds (forming rolls, molds, etc.), civil engineering and mining tools (oil drilling tools, rock crushing tools, etc.).
  • the prepared cemented carbide scrap was oxidized and roasted to obtain a mixture of tungsten oxide (WO 3 ) and cobalt tungstate (CoWO 4 ). Then, the obtained mixture was refluxed with an aqueous sodium hydroxide (NaOH) solution and extracted, thereby obtaining a tungsten compound solution containing sodium tungstate (Na 2 WO 4 ).
  • the adsorbent in the present disclosure is not limited to containing lysine, but may also include alanine, cystine, methionine, tyrosine, valine, glutamic acid, histidine ( Histidine), Proline, Threonine, Asparagine, Glycine, Isoleucine, Ornithine, Arginine, Serine, Citrulline and Cystathionine ( Cystathionine).
  • the total amount of the first amino acid salt added in the adsorbent is 0.2 (mol) to 1.1 (mol) per 1 (mol) of the metal component of the tungsten compound. Add in proportions. This allows a large amount of tungsten compounds to be adsorbed with a small amount of adsorbent.
  • the total amount of the first amino acid salt added is, for example, 10 (g/l) to 300 (g/l) with respect to the tungsten compound solution. This prevents the viscosity of the solution from increasing, making it difficult for the recovery efficiency of the metal compound to decrease. In particular, when the adsorbent is made of an amino acid salt, the viscosity of the solution does not increase easily and the workability is good.
  • the temperature may be adjusted depending on the activity of the free amino acid, and usually room temperature is sufficient.
  • the tungsten compound solution containing the adsorbent may be adjusted using hydrochloric acid or the like so that the zeta potential of the free amino acid becomes positive. This allows the adsorbent to adsorb tungsten compound ions, which are anions.
  • the pH of the solution may be less than 7 (acidic).
  • the free amino acid is glutamic acid, the preferred pH is 1.5 or less.
  • the recovery rate of the tungsten compound can be increased.
  • the step of adjusting the pH of the solution or the step of adding an adsorbent into the solution containing the metal compound may be performed first.
  • the recovery efficiency of the adsorbent is higher if the adsorption reaction takes place within 1 hour. That is, if the adsorption reaction exceeds 1 hour, part of the adsorbed metal compound may be desorbed from the free amino acid.
  • the adsorbent on which the tungsten compound ions were adsorbed was filtered using a means such as a filter.
  • the filtered adsorbent was washed in the order of acid washing and pure water washing as necessary.
  • the filtered adsorbent may be washed with warm water of 40 (° C.) or higher instead of acid washing.
  • impurities were removed by washing with pure water until the electrical conductivity of the washing filtrate became 500 ( ⁇ S/m) or less. This makes it possible to improve the quality of the tungsten compound and recover it.
  • the washed adsorbent was compressed by means such as a compressor. Then, the required amount of ammonium vanadate powder was added to the compressed adsorbent.
  • the amount of ammonium vanadate powder added is preferably, for example, 0.1 (wt%) to 10.0 (wt%) based on the dry weight of the adsorbent containing tungsten. Note that if the necessary amount of vanadium is contained in the cemented carbide scrap that is the raw material, it is not necessary to add ammonium vanadate powder.
  • the water absorption rate of the adsorbent after pressing is preferably 40 (%) or more.
  • the ammonium vanadate powder added to the compressed adsorbent can be well dissolved in the adsorbent.
  • the adsorbent on which the tungsten compound ions have been adsorbed is dried and further incinerated at a temperature of 300 (°C) or higher in the air to oxidize the tungsten compound and remove organic components including the adsorbent and additives. did.
  • tungsten oxide powder (WO 3 ) was obtained.
  • the obtained tungsten oxide powder was heat treated at a temperature of 800 (°C) to 950 (°C) in a reducing atmosphere (for example, hydrogen gas atmosphere) to reduce the tungsten oxide compound.
  • a reducing atmosphere for example, hydrogen gas atmosphere
  • metallic tungsten (W) was obtained.
  • the obtained tungsten metal was carbonized to obtain tungsten carbide powder (WC) according to the embodiment.
  • FIG. 3 is a flowchart illustrating an example of a procedure for producing tungsten carbide powder in a reference example. As shown in FIG. 3, in the step of producing tungsten carbide powder in the reference example, scraps of cemented carbide were first prepared.
  • the prepared cemented carbide scrap was oxidized and roasted to obtain a mixture of tungsten oxide (WO 3 ) and cobalt tungstate (CoWO 4 ). Then, the obtained mixture was extracted with an aqueous sodium hydroxide (NaOH) solution to obtain a tungsten compound solution containing sodium tungstate ( Na2WO4 ).
  • NaOH sodium hydroxide
  • the obtained tungsten compound solution was ion-exchanged with an ion exchange resin or the like to produce an aqueous solution of ammonium tungstate ((NH 4 ) 2 WO 4 ).
  • the resulting aqueous solution was then heated and concentrated to crystallize a tungsten compound as ammonium paratungstate (APT).
  • tungsten oxide powder (WO 3 ) was obtained.
  • the obtained tungsten oxide powder was heat treated in a reducing atmosphere to reduce the tungsten oxide compound.
  • metallic tungsten (W) was obtained.
  • the obtained tungsten metal was carbonized to obtain a tungsten carbide powder (WC) of a reference example.
  • the obtained tungsten carbide powders of the embodiment and reference example were analyzed by TOF-SIMS (Time-Of-Flight Secondary Ion Mass Spectrometry). Specifically, the depth distribution of tungsten and vanadium in the tungsten carbide powders of the embodiment and the reference example was measured by TOF-SIMS.
  • the TOF-SIMS measurement conditions are as follows.
  • the tungsten carbide powders of the embodiment and the reference example were fixed, and the powder surface was measured at a 100 ( ⁇ m) square.
  • the measuring device is TOF. manufactured by ION-TOF.
  • SIMS5 Bi (bismuth) was selected as the primary ion source, and elemental analysis in the depth direction was measured.
  • FIG. 4 is a diagram showing the depth distribution of the intensity ratio (V/W) between the secondary ion strength (V) of vanadium and the secondary ion strength (W) of tungsten in tungsten carbide powder.
  • the strength is low in at least a part of the region from the outermost surface 1a (see FIG. 1) of the tungsten carbide crystal grains 1 to 5 (nm) in the depth direction. It can be seen that the ratio (V/W) is not 0.05 or more.
  • the cemented carbide by increasing the vanadium concentration on the outermost surface 1a of the tungsten carbide crystal grains 1 and in the vicinity thereof, the cemented carbide can be efficiently produced as described above. Further, in the embodiment, by increasing the vanadium concentration at the outermost surface 1a of the tungsten carbide crystal grains 1 and its vicinity, a cemented carbide with a small amount of deformation can be obtained.
  • the strength is low in at least a part of the region from the outermost surface 1a (see FIG. 1) of the tungsten carbide crystal grains 1 to 5 (nm) in the depth direction. It can be seen that the ratio (V/W) is not 0.30 or more.
  • the cemented carbide can be produced more efficiently as described above. Further, in the embodiment, by further increasing the vanadium concentration at the outermost surface 1a of the tungsten carbide crystal grains 1 and its vicinity, a cemented carbide having a smaller amount of deformation can be obtained.
  • the atomic ratios of various elements within the tungsten carbide crystal grains 1 and the atomic ratios of various elements at the grain boundaries 1b were measured using STEM (Scanning Transmission). Measured using an Electron Microscope (scanning transmission electron microscope).
  • the inside of the tungsten carbide crystal grain 1 was measured at two locations, and the grain boundary 1b of the tungsten carbide crystal grain 1 was measured at three locations, and various elements within the grain and at the grain boundary 1b were measured. The average value of the atomic ratio was determined.
  • the STEM measurement conditions are as follows. First, as sample pretreatment, the sample was sliced into thin sections using the FIB method ( ⁇ -sampling method). Next, the thin sectioned sample was subjected to STEM observation using a scanning transmission electron microscope (JEM-ARM200F manufactured by JEOL Ltd.). The observation conditions were an accelerating voltage of 200 (kV) and a magnification accuracy of ⁇ 10 (%).
  • the analysis conditions are: acceleration voltage of 200 (kV), beam diameter of approximately 0.1 (nm ⁇ ), X-ray detector is a Si drift detector, energy resolution of approximately 140 (eV), and X-ray extraction angle of 21.9. (°), the solid angle was 0.98 (sr), and the acquisition time was 60 (seconds). Table 1 shows the STEM measurement results.
  • the atomic ratio of vanadium is 1 (at%) or less.
  • the temperature of the mixed powder is raised to 1400 (°C) to 1600 (°C) and the temperature is increased in two stages.
  • a tough cemented carbide can be produced.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Carbon And Carbon Compounds (AREA)
PCT/JP2023/023878 2022-06-30 2023-06-27 炭化タングステン粉末 Ceased WO2024005036A1 (ja)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002047506A (ja) * 2000-06-19 2002-02-15 Korea Inst Of Mach & Materials 粒子成長抑制剤を使用した炭化タングステン／コバルト系超硬合金の製造方法
JP2008106369A (ja) * 1996-10-02 2008-05-08 Umicore ＷＣ−Ｃｏ複合体に粒子成長阻止剤を配合する多段階法
US20140072469A1 (en) * 2012-09-10 2014-03-13 Kennametal Inc. Inert high hardness material for tool lens production
WO2019123764A1 (ja) * 2017-12-18 2019-06-27 住友電気工業株式会社 タングステン炭化物粉末、タングステン炭化物－コバルト金属複合粉末、および超硬合金

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008106369A (ja) * 1996-10-02 2008-05-08 Umicore ＷＣ−Ｃｏ複合体に粒子成長阻止剤を配合する多段階法
JP2002047506A (ja) * 2000-06-19 2002-02-15 Korea Inst Of Mach & Materials 粒子成長抑制剤を使用した炭化タングステン／コバルト系超硬合金の製造方法
US20140072469A1 (en) * 2012-09-10 2014-03-13 Kennametal Inc. Inert high hardness material for tool lens production
WO2019123764A1 (ja) * 2017-12-18 2019-06-27 住友電気工業株式会社 タングステン炭化物粉末、タングステン炭化物－コバルト金属複合粉末、および超硬合金

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