Method for producing metal carbide, metal carbide powder, and metal carbide intermediate dispersion

Abstract

This method for producing a metal carbide is a method for producing a powder-shaped metal carbide using a complex polymerization method, the method comprising: a complexing step for mixing a metal hydroxide and a basic compound to produce a first mixed solution, adding hydrogen peroxide to the first mixed solution to produce a second mixed solution, and reacting the first mixed solution with the second mixed solution; adding an organic acid to the second mixed solution to generate a metal carbide precursor; a carbonization step for generating a metal carbide by firing the metal carbide precursor; and a pulverization step in which the metal carbide is pulverized to form a metal carbonized powder. The metal carbide powder according to the present invention has a specific surface area of 1 m2 / g or more and a roundness of 0.78 or more as determined by a BET method. Furthermore, the metal carbide intermediate dispersion of the present invention comprises a metal compound, a basic compound, hydrogen peroxide, and an organic acid, and the particle diameter (D50) of particles in the metal carbide intermediate dispersion as determined by particle diameter distribution measurement using a dynamic light scattering method is 1,000 nm or less.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a metal carbide, a metal carbide powder, and a metal carbide intermediate dispersion liquid. Background Art

[0002] Metal carbides such as tantalum carbide and niobium carbide are widely used as raw materials for superhard cutting tools such as cutting tools, chips, cutters, drills, and dies, that is, additives such as tungsten carbide. In manufacturing high-quality superhard cutting tools, good mixing performance with tungsten carbide is required. As tantalum carbide used as an additive, Patent Document 1 discloses a tantalum carbide powder with less powder aggregation, fine and uniform particles, and a small oxygen content that is stoichiometrically combined with carbon.

[0003] In addition, when forming a film of a metal carbide on the surface of a carbon or ceramic substrate, it functions as a protective film, and this protective film suppresses the thermal decomposition of the substrate, for example, protects against oxidation during heating of a carbon material.

[0004] Prior Art Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2008-31016 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] However, it is considered that if the particles are extremely fine, the fluidity and mixing property will deteriorate due to aggregation and the like. In addition, regarding the method for manufacturing a metal carbide by heat-treating (firing method) and granulating a mixture of a metal oxide and carbon black as disclosed in Patent Document 1, the roundness of the manufactured tantalum carbide powder and tantalum-niobium composite powder becomes low. Furthermore, after granulation, a pulverization step is performed, whereby the roundness is further reduced. In this way, a metal carbide with extremely fine particles and low roundness has poor fluidity, so the mixing property with raw materials for superhard cutting tools such as tungsten carbide deteriorates, and thus a homogeneous superhardened material cannot be formed, and the performance of superhard tools manufactured from such raw materials deteriorates.

[0008] In addition, when forming a film on the surface of a substrate, if the roundness and fluidity are high, it is also easy to form a uniform film on the surface of the substrate.

[0009] In view of the above problems, the present invention provides a method for manufacturing a metal carbide, a metal carbide powder, and a metal carbide intermediate dispersion liquid having high roundness and high fluidity.

[0010] Means for Solving the Problems

[0011] The manufacturing method of the metal carbide of the present invention completed to solve the above problems is characterized in that it is a manufacturing method of a powdery metal carbide using a complex polymerization method, and it has the following steps: a complexation step: mixing a metal hydroxide and a basic compound to generate a first mixed solution, adding hydrogen peroxide to the first mixed solution to generate a second mixed solution, and further adding an organic acid to the second mixed solution to generate a metal carbide precursor; a carbonization step: generating a metal carbide by firing the metal carbide precursor; and a pulverization step: pulverizing the metal carbide to form a metal carbide powder.

[0012] It should be noted that for the sake of convenience of explanation, hereinafter, the manufacturing method of the metal carbide of the present invention having a pulverization step of pulverizing the metal carbide to form a metal carbide powder will be referred to as the manufacturing method of the metal carbide powder of the present invention for explanation.

[0013] In the complexation step of the manufacturing method of the metal carbide powder of the present invention, first, the metal hydroxide described below and a basic compound are mixed to generate a first mixed solution.

[0014] The metal hydroxide is preferably a hydroxide such as tantalum, niobium, titanium, tungsten, molybdenum, and zirconium. The metal hydroxide is particularly preferably tantalum hydroxide or niobium hydroxide.

[0015] For example, tantalum hydroxide is preferably adjusted to contain 1 to 100 g / L of tantalum in terms of Ta2O5 conversion by adding water (such as pure water). At this time, if the tantalum concentration is 1 g / L or more in terms of Ta2O5 conversion, it becomes a tantalum acid compound hydrate that is easily soluble in water, so it is preferred. Considering productivity, it is more preferably 10 g / L or more, and further preferably 20 g / L or more. On the other hand, if the tantalum concentration is 100 g / L or less in terms of Ta2O5 conversion, it becomes a tantalum acid compound hydrate that is easily soluble in water, so it is preferred. In order to more surely synthesize a tantalum acid compound hydrate that is easily soluble in water, it is more preferably 90 g / L or less, further preferably 80 g / L or less, and particularly preferably 70 g / L or less. In addition, niobium hydroxide is also preferably adjusted to contain 1 to 100 g / L of niobium in terms of Nb2O5 conversion.

[0016] The basic compound is preferably one or more compounds selected from ammonia, sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide, and organic nitrides. As the organic nitride, for example, amine compounds, quaternary ammonium compounds, guanidine compounds, azole compounds, etc. can be cited. Amine compounds or quaternary ammonium compounds are preferred, and methylamine, dimethylamine, tetramethylammonium hydroxide (TMAH), and tetraethylammonium hydroxide (TEAH) are more preferred. In addition, the basic compound may also be a basic solution obtained by dissolving the basic compound. As the basic solution, an aqueous basic solution is particularly preferred, and ammonia water is preferred among them.

[0017] The content of the basic compound in the first mixed solution is preferably greater than 0% by mass and less than 50% by mass, more preferably 0.01% by mass or more and 4% by mass or less. From the viewpoints of reactivity and dispersibility, a relatively large content of the basic compound is preferred. On the other hand, since it is a volatile component, a low content is preferred from the viewpoint of suppressing volatilization when forming a film in subsequent steps. Typically, the content of the basic compound can also be 0.1% by mass or more, 0.5% by mass or more, 1% by mass or more, 2% by mass or more, 3% by mass or more, 5% by mass or more, 8% by mass or more, 10% by mass or more. On the other hand, the content of the basic compound can also be 30% by mass or less, 25% by mass or less, 20% by mass or less, 10% by mass or less.

[0018] The content of the basic compound in the first mixed solution can be represented by the molar ratio of the basic compound to the metal hydroxide. The molar ratio of the basic compound to the metal hydroxide is preferably greater than 0 and less than or equal to 100, more preferably 0.001 or more and 100 or less, further preferably 0.01 or more and 50 or less, particularly preferably 0.1 or more and 30 or less, and more particularly preferably 4 or more and 20 or less. Typically, the molar ratio of the basic compound to the metal hydroxide can also be 0.005 or more, 0.05 or more, 0.5 or more. On the other hand, the molar ratio of the basic compound to the metal hydroxide can also be 15 or less, 10 or less, 8 or less, 5 or less, 4 or less, 3 or less, 2 or less, 1 or less, 0.5 or less, 0.1 or less.

[0019] Here, the basic compound in the molar ratio of the basic compound to the metal hydroxide represents the content of the basic compound in the first mixed solution. In addition, in the case of containing two or more basic compounds, the content of the basic compound is the total content of the two or more basic compounds. On the other hand, the metal hydroxide in the molar ratio of the basic compound to the metal hydroxide represents the content of the metal hydroxide in the first mixed solution in terms of the metal atom. In addition, in the case of containing two or more metal hydroxides, the content of the metal hydroxide in terms of the metal atom is the total content of the two or more metal hydroxides in terms of the metal atom.

[0020] For example, when the mixed metal hydroxide is tantalum hydroxide, the molar ratio of the basic compound / Ta is preferably greater than 0 and less than or equal to 100, more preferably 0.001 or more and 100 or less, still more preferably 0.01 or more and 50 or less, particularly preferably 0.1 or more and 30 or less, and even more particularly preferably 4 or more and 20 or less. Typically, the molar ratio of the basic compound / Ta can also be 0.005 or more, 0.05 or more, 0.5 or more. On the other hand, the molar ratio of the basic compound / Ta can also be 15 or less, 10 or less, 8 or less, 5 or less, 4 or less, 3 or less, 2 or less, 1 or less, 0.5 or less, 0.1 or less.

[0021] In addition, when the mixed metal hydroxide is niobium hydroxide, the molar ratio of the basic compound / Nb is preferably greater than 0 and less than or equal to 100, more preferably 0.001 or more and 100 or less, still more preferably 0.01 or more and 50 or less, particularly preferably 0.1 or more and 30 or less, and even more particularly preferably 4 or more and 20 or less. Typically, the molar ratio of the basic compound / Ta can also be 0.005 or more, 0.05 or more, 0.5 or more. On the other hand, the molar ratio of the basic compound / Nb can also be 15 or less, 10 or less, 8 or less, 5 or less, 4 or less, 3 or less, 2 or less, 1 or less, 0.5 or less, 0.1 or less.

[0022] Furthermore, when the mixed metal hydroxide is niobium hydroxide and tantalum hydroxide, the molar ratio of the basic compound to niobium and tantalum: basic compound / (Nb + Ta) is preferably greater than 0 and less than or equal to 100, more preferably 0.001 or more and 100 or less, still more preferably 0.01 or more and 50 or less, particularly preferably 0.1 or more and 30 or less, and even more particularly preferably 4 or more and 20 or less. Typically, the molar ratio of the basic compound / (Nb + Ta) can also be 0.005 or more, 0.05 or more, 0.5 or more. On the other hand, the molar ratio of the basic compound / (Nb + Ta) can also be 15 or less, 10 or less, 8 or less, 5 or less, 4 or less, 3 or less, 2 or less, 1 or less, 0.5 or less, 0.1 or less.

[0023] In addition, when the basic compound is ammonia, the ammonia content in the first mixed solution is preferably greater than 0% by mass and less than 50% by mass, more preferably 0.01% by mass or more and 4% by mass or less. From the viewpoints of reactivity and dispersibility, a relatively large ammonia content is preferred. On the other hand, since it is a volatile component, a low content is preferred from the viewpoint of suppressing volatilization when forming a film in subsequent steps. Typically, the ammonia content can also be 0.1% by mass or more, 0.5% by mass or more, 1% by mass or more, 2% by mass or more, 3% by mass or more, 5% by mass or more, 8% by mass or more, 10% by mass or more. On the other hand, the ammonia content can also be 30% by mass or less, 25% by mass or less, 20% by mass or less, 10% by mass or less.

[0024] The content of ammonia in the first mixed solution can be represented by the molar ratio of NH3 / metal hydroxide. The molar ratio of NH3 / metal hydroxide is preferably greater than 0 and less than or equal to 100, more preferably 0.001 or more and 100 or less, further preferably 0.01 or more and 50 or less, particularly preferably 0.1 or more and 30 or less, and more particularly preferably 4 or more and 20 or less. Typically, the molar ratio of NH3 / metal hydroxide can also be 0.005 or more, 0.05 or more, 0.5 or more. On the other hand, the molar ratio of NH3 / metal hydroxide can also be 15 or less, 10 or less, 8 or less, 5 or less, 4 or less, 3 or less, 2 or less, 1 or less, 0.5 or less, 0.1 or less.

[0025] When the mixed metal hydroxide is tantalum hydroxide, the molar ratio of NH3 / Ta is preferably greater than 0 and less than or equal to 100, more preferably 0.001 or more and 100 or less, further preferably 0.01 or more and 50 or less, particularly preferably 0.1 or more and 30 or less, and more particularly preferably 4 or more and 20 or less. Typically, the molar ratio of NH3 / Ta can also be 0.005 or more, 0.05 or more, 0.5 or more. On the other hand, the molar ratio of NH3 / Ta can also be 15 or less, 10 or less, 8 or less, 5 or less, 4 or less, 3 or less, 2 or less, 1 or less, 0.5 or less, 0.1 or less.

[0026] In addition, when the mixed metal hydroxide is niobium hydroxide, the molar ratio of NH3 / Nb is preferably greater than 0 and less than or equal to 100, more preferably 0.001 or more and 100 or less, further preferably 0.01 or more and 50 or less, particularly preferably 0.1 or more and 30 or less, and more particularly preferably 4 or more and 20 or less. Typically, the molar ratio of NH3 / Ta can also be 0.005 or more, 0.05 or more, 0.5 or more. On the other hand, the molar ratio of NH3 / Nb can also be 15 or less, 10 or less, 8 or less, 5 or less, 4 or less, 3 or less, 2 or less, 1 or less, 0.5 or less, 0.1 or less.

[0027] Furthermore, when the mixed metal hydroxides are niobium hydroxide and tantalum hydroxide, the molar ratio of ammonia to niobium and tantalum: NH3 / (Nb + Ta) is preferably greater than 0 and less than or equal to 100, more preferably 0.001 or more and 100 or less, still more preferably 0.01 or more and 50 or less, particularly preferably 0.1 or more and 30 or less, and even more particularly preferably 4 or more and 20 or less. Typically, the molar ratio of NH3 / (Nb + Ta) can also be 0.005 or more, 0.05 or more, 0.5 or more. On the other hand, the molar ratio of NH3 / (Nb + Ta) can also be 15 or less, 10 or less, 8 or less, 5 or less, 4 or less, 3 or less, 2 or less, 1 or less, 0.5 or less, 0.1 or less.

[0028] Examples of the solvent used in the complexation step in the method for producing the metal carbide powder of the present invention include water, organic solvents, and mixed solvents thereof. In addition, examples of the organic solvent include alcohol solvents, ketone solvents, ether solvents, ester solvents, aromatic hydrocarbon solvents, aliphatic hydrocarbon solvents, etc., and may also be a solvent formed by mixing the above organic solvents with pure water. In addition, examples of the alcohol solvent include alcohols having 5 or less carbon atoms (methanol, ethanol, n-propanol, isopropanol, butanol, ethylene glycol, propylene glycol), acetone, high-boiling solvents, etc. It is preferred that the above solvents are miscible with water.

[0029] Examples of the high-boiling solvent include polyol solvents and glycol solvents. Examples of the polyol solvent include glycerol (boiling point: 290 °C), 1,6-hexanediol (boiling point: 250 °C), 1,7-heptanediol (boiling point: 259 °C), etc. In addition, examples of the glycol solvent include ethylene glycol (boiling point: 197.3 °C), propylene glycol (boiling point: 188.2 °C), diethylene glycol (boiling point: 244.3 °C), triethylene glycol (boiling point: 287.4 °C), oligoethylene glycol (boiling point: 287 °C to 460 °C), polyethylene glycol (PEG) (boiling point: 460 °C or higher), polyethylene glycol (PEG)-polypropylene glycol (PPG) copolymer (boiling point: 460 °C or higher), diethylene glycol monohexyl ether (boiling point: 260 °C), polyoxyalkylene monoalkyl ether (boiling point: 260 °C or higher), polyoxyethylene sorbitan monolaurate (boiling point: 321 °C or higher), other anionic fluorosurfactants (boiling point: 180 °C or higher), amphoteric fluorosurfactants (boiling point: 180 °C or higher), nonionic fluorosurfactants (boiling point: 180 °C or higher), amine oxides (boiling point: 180 °C or higher), etc. The above boiling points are the boiling points at 1 atmospheric pressure.

[0030] In addition, the solvent used in the complexation step in the method for manufacturing the metal carbide powder of the present invention may also be a solvent to which a resin such as a polyolefin-based compound or a polyvinyl-based compound is added. Further, as the resin added to the solvent, an anionic water-soluble resin and / or a non-ionic water-soluble resin may also be used.

[0031] Here, a cationic water-soluble resin has a positive charge in water at pH = 7 in the polymer, and is, for example, a resin having any one of functional groups such as an amino group, an imino group, a tertiary amino group, a quaternary ammonium group, and a hydrazino group. Further, an anionic water-soluble resin has a negative charge in water at pH = 7 in the polymer, and is, for example, a resin having any one of functional groups such as a carboxyl group, a sulfo group, a sulfate group, and a phosphate group. Moreover, a non-ionic water-soluble resin does not conform to the above-described cationic water-soluble resin or anionic water-soluble resin, and is, for example, a resin having any one of functional groups such as a hydroxyl group, an ether group, and an amide group in the polymer.

[0032] Moreover, these resins may be resins containing one or more water-soluble homopolymers selected from the group consisting of acrylic polymers, urethane polymers, styrene polymers, olefin polymers, amide polymers, silicone polymers, epoxy polymers, vinyl chloride polymers, and vinyl acetate polymers and / or water-soluble copolymers formed from two or more of the above polymers. Particularly preferred are resins containing one or more water-soluble homopolymers of acrylic polymers, styrene polymers, and olefin polymers and / or water-soluble copolymers formed from two or more of the above polymers.

[0033] Next, in the complexation step in the method for manufacturing the metal carbide powder of the present invention, hydrogen peroxide described below is added to the generated first mixed solution to generate a second mixed solution.

[0034] The content of hydrogen peroxide in the second mixed solution is preferably greater than 0% by mass and less than or equal to 35% by mass, more preferably 0.001% by mass or more and 30% by mass or less, further preferably 0.01% by mass or more and 25% by mass or less, and particularly preferably 0.1% by mass or more and 20% by mass or less. Typically, the content of this hydrogen peroxide may also be 0.005% by mass or more, 0.05% by mass or more, 0.5% by mass or more, 1% by mass or more, 2% by mass or more, 4% by mass or more. On the other hand, the content of this hydrogen peroxide may also be 10% by mass or less, 5% by mass or less, 3% by mass or less, 1% by mass or less.

[0035] The content of hydrogen peroxide in the second mixture can be expressed by the molar ratio of H2O2 to metal hydroxide. The molar ratio of hydrogen peroxide to metal hydroxide, H2O2 / metal hydroxide, is preferably greater than 0 and less than or equal to 10, more preferably 0.001 or more and 3 or less, and still more preferably 0.01 or more and 1 or less. Typically, the molar ratio H2O2 / metal hydroxide can also be 0.005 or more, 0.05 or more, 0.5 or more. On the other hand, the molar ratio H2O2 / metal hydroxide can also be 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less.

[0036] Here, H2O2 in the molar ratio H2O2 / metal hydroxide represents the content of H2O2 in the second mixture. On the other hand, the metal hydroxide in the molar ratio H2O2 / metal hydroxide represents the content of the metal hydroxide in the second mixture in terms of metal atoms. Additionally, in the case of containing two or more metal hydroxides, the content of the metal hydroxide in terms of metal atoms is the total content of the above two or more metal hydroxides in terms of metal atoms.

[0037] Specifically, when the mixed metal hydroxide is tantalum hydroxide, the molar ratio of hydrogen peroxide to tantalum, H2O2 / Ta, is preferably greater than 0 and less than or equal to 10, more preferably 0.001 or more and 3 or less, and still more preferably 0.01 or more and 1 or less. Typically, the molar ratio H2O2 / Ta can also be 0.005 or more, 0.05 or more, 0.5 or more. On the other hand, the molar ratio H2O2 / Ta can also be 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less.

[0038] In addition, when the mixed metal hydroxide is niobium hydroxide, the molar ratio of hydrogen peroxide to niobium, H2O2 / Nb, is preferably greater than 0 and less than or equal to 10, more preferably 0.001 or more and 3 or less, and still more preferably 0.01 or more and 1 or less. Typically, the molar ratio H2O2 / Nb can also be 0.005 or more, 0.05 or more, 0.5 or more. On the other hand, the molar ratio H2O2 / Nb can also be 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less.

[0039] Furthermore, when the mixed metal hydroxides are niobium hydroxide and tantalum hydroxide, the molar ratio of hydrogen peroxide to niobium and tantalum, H2O2 / (Nb + Ta), is preferably greater than 0 and less than or equal to 10, more preferably 0.001 or more and 3 or less, and still more preferably 0.01 or more and 1 or less. Typically, the molar ratio H2O2 / (Nb + Ta) can also be 0.005 or more, 0.05 or more, 0.5 or more. On the other hand, the molar ratio H2O2 / (Nb + Ta) can also be 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less.

[0040] Here, regarding the addition of hydrogen peroxide, the complexation reaction easily proceeds by adding it under alkaline conditions. Therefore, before adding hydrogen peroxide, a metal hydroxide and an alkaline compound can be mixed to form a first mixed solution as an alkaline mixed solution.

[0041] Then, in the complexation step of the method for manufacturing the metal carbide powder of the present invention, an organic acid described below is added to the generated second mixed solution to form a metal carbide precursor.

[0042] Examples of the organic acid include carboxylic acids, polyfunctional carboxylic acids, hydroxycarboxylic acids, and amino acids. Examples of the carboxylic acid include butyric acid, formic acid, acetic acid, lauric acid, oleic acid, linoleic acid, benzoic acid, etc. Examples of the polyfunctional carboxylic acid include oxalic acid, succinic acid, malonic acid, maleic acid, glutaric acid, citric acid, etc. Examples of the hydroxycarboxylic acid include lactic acid, gluconic acid, tartaric acid, malic acid, etc. Examples of the amino acid include alanine, arginine, aspartic acid, ethylenediaminetetraacetic acid, etc. Organic acids that do not contain nitrogen atoms are particularly preferred. For example, carboxylic acids, polyfunctional carboxylic acids, and hydroxycarboxylic acids are preferred, and citric acid, tartaric acid, and lactic acid are more preferred. Additionally, polyfunctional carboxylic acids are more preferred, and citric acid, which is an organic acid that does not contain nitrogen atoms and is a polyfunctional carboxylic acid, is most preferred. Various isomers (structural isomers, optical isomers, etc.) of the above compounds may also be included in the organic acid. Furthermore, one or more of the above compounds may be used as the organic acid.

[0043] The content of the organic acid in the metal carbide precursor is preferably greater than 0% by mass and less than 100% by mass, more preferably 1% by mass or more and 40% by mass or less, and still more preferably 3% by mass or more and 15% by mass or less. Typically, the content of the organic acid can also be 0.1% by mass or more, 0.5% by mass or more, 2% by mass or more, 5% by mass or more, 8% by mass or more, 10% by mass or more. On the other hand, the content of the organic acid can also be 30% by mass or less, 25% by mass or less, 20% by mass or less, 10% by mass or less. Here, when the organic acid added to the second mixed solution is a mixture of two or more organic acids, the content of the organic acid is the total content of the two or more organic acids added.

[0044] The content of the organic acid in the metal carbide precursor can be represented by the molar ratio of the organic acid to the metal hydroxide. It is preferred to add the organic acid in such a way that the molar ratio of the organic acid to the metal hydroxide: organic acid / metal hydroxide is greater than 0 and less than or equal to 500. From the viewpoints of the stability of the metal carbide precursor and cost reduction, it is more preferably 0.01 or more and 100 or less, further preferably 0.1 or more and 9 or less, and particularly preferably 0.1 or more and 6 or less. Typically, the molar ratio: organic acid / metal hydroxide can also be 0.005 or more, 0.5 or more, 1 or more, 2 or more, 3 or more, 5 or more. On the other hand, the molar ratio: organic acid / metal hydroxide can also be 200 or less, 50 or less, 40 or less, 30 or less, 20 or less, 10 or less, 8 or less, 5 or less.

[0045] Here, the organic acid in the molar ratio: organic acid / metal hydroxide represents the content of the organic acid in the metal carbide precursor. In addition, in the case of containing two or more organic acids, the content of the organic acid is the total content of the above two or more organic acids. On the other hand, the metal hydroxide in the molar ratio: organic acid / metal hydroxide represents the content of the metal hydroxide in the metal carbide precursor in terms of the metal atom conversion. In addition, in the case of containing two or more metal hydroxides, the content of the metal hydroxide in terms of the metal atom conversion is the total content of the above two or more metal hydroxides in terms of the metal atom conversion.

[0046] For example, when the mixed metal hydroxide is tantalum hydroxide, it is preferred to add the organic acid so that the molar ratio of the organic acid to tantalum: organic acid / Ta is greater than 0 and less than or equal to 500. From the viewpoints of the stability of the metal carbide precursor and cost reduction, it is more preferably 0.01 or more and 100 or less, further preferably 0.1 or more and 9 or less, and particularly preferably 0.1 or more and 6 or less. Typically, the molar ratio: organic acid / Ta can also be 0.005 or more, 0.5 or more, 1 or more, 2 or more, 3 or more, 5 or more. On the other hand, the molar ratio: organic acid / Ta can also be 200 or less, 50 or less, 40 or less, 30 or less, 20 or less, 10 or less, 8 or less, 5 or less.

[0047] In addition, when the mixed metal hydroxide is niobium hydroxide, an organic acid is preferably added so that the molar ratio of the organic acid to niobium: organic acid / Nb is greater than 0 and less than or equal to 500. From the viewpoints of the stability of the metal carbide precursor and cost reduction, it is more preferably 0.01 or more and 100 or less, further preferably 0.1 or more and 9 or less, and particularly preferably 0.1 or more and 6 or less. Typically, the molar ratio: organic acid / Nb can also be 0.005 or more, 0.5 or more, 1 or more, 2 or more, 3 or more, 5 or more. On the other hand, the molar ratio: organic acid / Nb can also be 200 or less, 50 or less, 40 or less, 30 or less, 20 or less, 10 or less, 8 or less, 5 or less.

[0048] Furthermore, when the mixed metal hydroxides are niobium hydroxide and tantalum hydroxide, an organic acid is preferably added so that the molar ratio of the organic acid to niobium and tantalum: organic acid / (Nb + Ta) is greater than 0 and less than or equal to 500. From the viewpoints of the stability of the metal carbide precursor and cost reduction, it is more preferably 0.01 or more and 100 or less, further preferably 0.1 or more and 9 or less, and particularly preferably 0.1 or more and 6 or less. Typically, the molar ratio: organic acid / (Nb + Ta) can also be 0.005 or more, 0.5 or more, 1 or more, 2 or more, 3 or more, 5 or more. On the other hand, the molar ratio: organic acid / (Nb + Ta) can also be 200 or less, 50 or less, 40 or less, 30 or less, 20 or less, 10 or less, 8 or less, 5 or less.

[0049] The complexation step in the method for manufacturing the metal carbide powder of the present invention described above does not require heating and can thus be carried out at room temperature (25°C).

[0050] It is speculated that at least a part of the metal carbide precursor generated in this way forms a peroxo complex containing a metal element derived from the metal hydroxide.

[0051] Next, in the carbonization step of the method for manufacturing the metal carbide powder of the present invention, a metal carbide is generated by firing the metal carbide precursor.

[0052] The metal carbide precursor generated by the complexation step in the method for manufacturing the metal carbide powder of the present invention is placed in a stationary furnace and fired in the atmosphere at a firing temperature of 1000°C or more and 1900°C or less for a firing time of 1 hour or more and 12 hours or less to generate a metal carbide.

[0053] Then, in the pulverization step of the method for manufacturing the metal carbide powder of the present invention, the metal carbide is pulverized to form a metal carbide powder.

[0054] The metal carbide formed by the carbonization step in the method for manufacturing metal carbide powder of the present invention is pulverized using a ball mill, a jet mill, a cutter mill, etc., thereby forming the metal carbide powder of the present invention. It should be noted that the undersize part (fine particle side) obtained by classifying the pulverized metal carbide powder through a sieve or the like may be used as the metal carbide powder of the present invention. The oversize part (coarse particle side) may also be pulverized again and classified before use. The sieve used for classification is preferably one with a pore size of 30 to 1000 μm.

[0055] Regarding the metal carbide powder (sample) of the present invention formed by the above-described method for manufacturing metal carbide powder of the present invention, it can be confirmed that it is a carbide from the peaks of the X-ray diffraction pattern obtained by performing powder X-ray diffraction measurement according to the following X-ray diffraction measurement conditions and X-ray diffraction analysis conditions.

[0056] =X-ray diffraction measurement conditions=

[0057] ·Apparatus: MiniFlexII (manufactured by Rigaku Corporation)

[0058] ·Measurement range (2θ): 5 to 90°

[0059] ·Sampling width: 0.02°

[0060] ·Scanning speed: 2.0° / min

[0061] ·X-ray: CuKα ray

[0062] ·Voltage: 30 kV

[0063] ·Current: 15 mA

[0064] ·Divergence slit: 1.25°

[0065] ·Scattering slit: 1.25°

[0066] ·Receiving slit: 0.3 mm

[0067] =X-ray diffraction analysis conditions=

[0068] ·Use the data analysis software PDXL2 manufactured by Rigaku Corporation.

[0069] ·In order to clarify the peak top, the peak is smoothed with a b-spline curve.

[0070] In addition, the fluidity of the metal carbide powder of the present invention formed by the above-described method for manufacturing the metal carbide powder of the present invention can be determined in the following manner. A sample of the metal carbide powder of the present invention is put into an A.B.D powder property measuring instrument manufactured by Tsutsui Rikagaku Kogyo Co., Ltd. provided with a filter having a pore diameter of 850 μm or 1000 μm, the filter is vibrated for 1 minute, and the sample passing through the filter is recovered. Then, the recovered amount of the sample is measured, and the recovery rate is calculated by recovery rate = recovered amount (g) / 10 g × 100, whereby the fluidity of the metal carbide powder of the present invention can be determined.

[0071] By performing each step in the above-described method for manufacturing the metal carbide powder of the present invention, the metal carbide powder of the present invention can be manufactured. In addition, the metal carbide powder of the present invention can also be manufactured by performing the following steps in addition to the above-described steps.

[0072] The method for manufacturing the metal carbide powder of the present invention may also include a drying step of drying the metal carbide precursor.

[0073] By drying the metal carbide precursor generated through the complexation step using the drying method described below, the excess hydrogen peroxide and ammonia contained in the metal carbide precursor can be removed.

[0074] By removing the excess hydrogen peroxide in the metal carbide precursor, changes in the solution caused by the volatilization of hydrogen peroxide can be suppressed, and it becomes easier to use from the viewpoints of safety and regulations. Specifically, if the content of hydrogen peroxide in the metal carbide precursor is 6% by mass or less, it is easily exempted from the Poisonous and Deleterious Substances Control Law, and thus it becomes easier to use from the viewpoints of safety and storage methods. In addition, by removing the excess ammonia contained in the metal carbide precursor, it also becomes easier to use from the viewpoints of safety and operation.

[0075] As an example of the drying step in the method for manufacturing the metal carbide powder of the present invention, the heating temperature in the drying step may be less than 100°C.

[0076] If the heating temperature in the drying step is 25°C or higher and less than 100°C, the components of the excess hydrogen peroxide and ammonia contained in the metal carbide precursor volatilize, and thus a peroxy complex powder in the form of a white powder is obtained. It should be noted that the heating temperature is more preferably 90°C or lower. In addition, the heating time may be 1 hour or longer and 100 hours or shorter, and is preferably 5 hours or longer and 20 hours or shorter.

[0077] In addition, as another example of the drying step in the method for manufacturing the metal carbide powder of the present invention, the heating temperature in the drying step may be 100°C or higher.

[0078] If the heating temperature in the drying step is 100 °C or higher and 200 °C or lower, the excess hydrogen peroxide and ammonia components contained in the metal carbide precursor volatilize, thereby obtaining a peroxo complex powder as a greenish-white powder. It should be noted that the heating temperature is more preferably 110 °C or higher. In addition, the heating time can be 1 hour or longer and 100 hours or shorter, preferably 5 hours or longer and 20 hours or shorter.

[0079] Furthermore, as another example of the drying step in the method for manufacturing the metal carbide powder of the present invention, if the drying method is vacuum drying without heating, a peroxo complex powder as a white powder is obtained. In addition, the heating time can be 1 hour or longer and 100 hours or shorter, preferably 5 hours or longer and 20 hours or shorter. It should be noted that in the case of vacuum drying, the excess hydrogen peroxide and ammonia components contained in the metal carbide precursor are not removed and remain.

[0080] In addition, the method for manufacturing the metal carbide powder of the present invention may also have a pulverization step: pulverizing the metal carbide precursor dried by the above drying step.

[0081] The dried metal carbide precursor, that is, the peroxo complex powder obtained through the above respective drying steps, is pulverized using a ball mill, a jet mill, a shredder, or the like. This is preferable from the following viewpoint: by pulverizing the peroxo complex powder, the peroxo complex powder becomes easily soluble in pure water in the dissolution step.

[0082] In addition, the method for manufacturing the metal carbide of the present invention is characterized in that it is a method for manufacturing a film-shaped metal carbide using a complex polymerization method, and it has the following steps: a complexation step: mixing a metal hydroxide and a basic compound to form a first mixed solution, adding hydrogen peroxide to the first mixed solution to form a second mixed solution, and further adding an organic acid to the second mixed solution to form a metal carbide precursor; a dissolution step: generating a metal carbide intermediate in which the metal carbide precursor is dispersed in pure water; and a carbonization step: forming a metal carbide film containing a metal carbide on the substrate by coating the metal carbide intermediate on the substrate and firing it.

[0083] It should be noted that for the sake of convenience in explanation, the method for manufacturing the metal carbide of the present invention having a carbonization step of forming a metal carbide film containing a metal carbide on a substrate is described as the method for manufacturing the metal carbide film of the present invention.

[0084] In the complexation step of the method for manufacturing a metal carbide film of the present invention, a metal hydroxide is mixed with an alkaline compound to form a first mixed solution, hydrogen peroxide is added to the first mixed solution to form a second mixed solution, and then an organic acid is added to the second mixed solution to form a metal carbide precursor.

[0085] In the complexation step of the method for manufacturing a metal carbide film of the present invention, the metal carbide precursor formed is preferably in the state of a transparent solution without precipitation from the viewpoint of forming a uniform film. The particle size of the metal carbide precursor is preferably small, and from the viewpoint of stability over time, it is preferably 1000 nm or less, more preferably 500 nm or less, and particularly preferably 100 nm or less. Typically, the particle size can also be 900 nm or less, 800 nm or less, 700 nm or less, 600 nm or less, 400 nm or less, 300 nm or less, 200 nm or less, 50 nm or less, 30 nm or less, 20 nm or less, 10 nm or less, 6 nm or less, 2 nm or less, 1 nm or less, 0.6 nm or less. On the other hand, the particle size of the particles is preferably 1 nm or more, more preferably 2 nm or more, further preferably 6 nm or more, and particularly preferably 10 nm or more. Furthermore, it can also be 100 nm or more, 200 nm or more, 300 nm or more, 400 nm or more, 500 nm or more. Typically, the particle size is 10 nm or more and 800 nm or less.

[0086] Typically, the particle size of the metal carbide precursor is 10 nm or more and 800 nm or less. It should be noted that from the viewpoint of forming a thick film, it can also be an aqueous dispersion in which the metal carbide precursor precipitates.

[0087] The particle size of the metal carbide precursor formed in the complexation step of the method for manufacturing a metal carbide film of the present invention is the particle size (D50) measured by measuring the particle size distribution using the dynamic light scattering method.

[0088] Here, the dynamic light scattering method is the following method: by irradiating light such as a laser onto a solution such as a suspension solution, measuring the light scattering intensity from a particle group performing Brownian motion, and obtaining the particle size and distribution from the temporal change in this intensity. Specifically, the evaluation method of the particle size distribution is implemented in accordance with JIS Z 8828:2019 "Particle Size Analysis - Dynamic Light Scattering Method" using a Zeta potential / particle size / molecular weight measurement system (manufactured by Otsuka Electronics Co., Ltd.: ELSZ-2000ZS). Additionally, a sample diluted 1000-fold with pure water as needed is used as the measurement sample. In order to remove dust, etc. in the measurement sample just before measurement, the measurement sample is filtered through a filter with a pore size of 11 μm, and ultrasonic treatment is performed for 3 minutes using an ultrasonic cleaner (manufactured by AS ONE Corporation: VS-100III). Furthermore, the liquid temperature of the measurement sample is adjusted to 25°C. It should be noted that the particle size (D50) refers to the median particle size (D50), which is the particle size representing the 50% cumulative value of the cumulative distribution curve.

[0089] It should be noted that regarding the complexation step in the manufacturing method of the metal carbide film of the present invention, except for the above points, it is the same as the complexation step in the manufacturing method of the metal carbide powder of the present invention, so detailed description is omitted.

[0090] In the dissolution step in the manufacturing method of the metal carbide film of the present invention, a metal carbide intermediate in which a metal carbide precursor is dispersed in pure water is generated.

[0091] Pure water is added to the metal carbide precursor obtained through the complexation step in the manufacturing method of the metal carbide film of the present invention, and it is stirred for 10 minutes, thereby generating a metal carbide intermediate. It is preferably adjusted to a content that is easily coatable when the metal carbide intermediate of the present invention is coated on a substrate in the subsequent carbonization step. The solid content of the metal carbide intermediate of the present invention is preferably adjusted to 1% by mass or more and 70% by mass or less. It should be noted that the dissolution step does not require heating and can thus be carried out at room temperature (25°C).

[0092] The solid content of the metal carbide intermediate of the present invention is preferably adjusted according to the type and material of the substrate, more preferably 2% by mass or more and 65% by mass or less, further preferably 4% by mass or more and 60% by mass or less, particularly preferably 5% by mass or more and 55% by mass or less, and most preferably 10% by mass or more and 50% by mass or less.

[0093] In addition, in the case of using tantalum hydroxide as the metal hydroxide, the tantalum content in the metal carbide intermediate of the present invention can typically be 5% by mass or more and 30% by mass or less, 5% by mass or more and 25% by mass or less, 5% by mass or more and 20% by mass or less, 5% by mass or more and 15% by mass or less, 5% by mass or more and 10% by mass or less.

[0094] Here, the tantalum content in the metal carbide intermediate of the present invention is obtained by appropriately diluting the intermediate with dilute hydrochloric acid as needed, using ICP emission analysis (manufactured by Agilent Technologies: AG-5110), and measuring and calculating the Ta mass fraction in terms of Ta in accordance with JIS K0116:2014.

[0095] In addition, in the case of using niobium hydroxide as the metal hydroxide, the niobium content in the metal carbide intermediate of the present invention can typically be 5% by mass or more and 30% by mass or less, 5% by mass or more and 25% by mass or less, 5% by mass or more and 20% by mass or less, 5% by mass or more and 15% by mass or less, 5% by mass or more and 10% by mass or less.

[0096] The niobium content in the metal carbide intermediate of the present invention is the same as the above-mentioned tantalum content, and the Nb mass fraction in terms of Nb can be measured and calculated.

[0097] It should be noted that regarding the dissolution step, if the solid content is appropriate when the metal carbide precursor is coated on the substrate, there is no need to add pure water to the metal carbide precursor obtained in the complexation step to adjust the solid content.

[0098] In the carbonization step of the method for manufacturing a metal carbide film of the present invention, a metal carbide film containing a metal carbide is formed on the substrate by coating the metal carbide intermediate on the substrate and firing it. Examples of the substrate include crucibles, furnace materials, electrodes, fibers, filtration devices, filters, protective tubes, heater tubes, burner nozzles, refractory tools, etc. In addition, examples of the material include carbon, metal, and ceramic. Examples of the metal include metal carbides, metal oxides, metal nitrides, etc.

[0099] Specifically, the metal carbide intermediate obtained through the dissolution step in the method for manufacturing a metal carbide film of the present invention is filtered using a filter with a pore size of 1 μm, for example, and coated on the surface of a substrate using a brush or the like. Then, the substrate coated with the metal carbide intermediate is placed in a stationary furnace and fired in the atmosphere at a firing temperature of 1000 °C or higher and 1900 °C or lower for a firing time of 1 hour or longer and 12 hours or shorter, thereby forming a metal carbide film on the surface of the substrate. It should be noted that, in addition to the method of coating on the surface of the substrate using a brush or the like, it may also be a method of spraying on the surface of the substrate or a method of immersing the substrate in a container filled with the metal carbide intermediate.

[0100] By performing each of the above steps in the method for manufacturing a metal carbide film of the present invention, the metal carbide film of the present invention can be manufactured. In addition, the metal carbide film of the present invention can also be manufactured by performing the following steps in addition to the above steps.

[0101] In the method for manufacturing a metal carbide film of the present invention, as a pre-step of the dissolution step for generating a metal carbide intermediate in which a metal carbide precursor is dispersed in pure water, a drying step may also be included: drying the metal carbide precursor generated through the complexation step.

[0102] By drying the metal carbide precursor generated through the complexation step using the above drying method, excess hydrogen peroxide and ammonia contained in the metal carbide precursor can be removed.

[0103] By removing excess hydrogen peroxide in the metal carbide precursor, when the metal carbide intermediate generated by adding pure water to the metal carbide precursor is coated on the surface of the substrate in the carbonization step, foaming will not occur and it can be coated evenly. In addition, by removing excess ammonia contained in the metal carbide precursor, it becomes easier to use in terms of safety and operation.

[0104] It should be noted that the drying step in the method for manufacturing a metal carbide film of the present invention is the same as the drying step in the method for manufacturing a metal carbide powder of the present invention described above, so detailed description is omitted.

[0105] In addition, similar to the method for manufacturing a metal carbide powder of the present invention described above, the method for manufacturing a metal carbide film of the present invention may also include a pulverization step: pulverizing the metal carbide precursor dried through the above drying step. It should be noted that the pulverization step in the method for manufacturing a metal carbide film of the present invention is the same as the pulverization step in the method for manufacturing a metal carbide powder of the present invention described above, so description is omitted.

[0106] In addition, the method for manufacturing a metal carbide precursor of the present invention is characterized in that it is a method for manufacturing a metal carbide precursor for generating a metal carbide using a complex polymerization method, and it has the following steps: mixing a metal hydroxide and a basic compound to generate a first mixed solution, adding hydrogen peroxide to the first mixed solution to generate a second mixed solution, and further adding an organic acid to the second mixed solution to generate a metal carbide precursor.

[0107] It should be noted that the complexation step in the method for manufacturing a metal carbide precursor of the present invention is the same as the complexation step in the method for manufacturing a metal carbide of the present invention described above, so detailed description is omitted.

[0108] In addition, the method for manufacturing a metal carbide precursor of the present invention may also have a drying step: drying the metal carbide precursor generated through the above complexation step.

[0109] Here, the drying step in the method for manufacturing a metal carbide precursor of the present invention is the same as the drying step in the method for manufacturing a metal carbide of the present invention described above, so description is omitted.

[0110] In addition, the method for manufacturing a metal carbide intermediate of the present invention is characterized in that it is a method for manufacturing a metal carbide intermediate for generating a metal carbide using a complex polymerization method, and it has the following steps: a complexation step: mixing a metal hydroxide and a basic compound to generate a first mixed solution, adding hydrogen peroxide to the first mixed solution to generate a second mixed solution, and further adding an organic acid to the second mixed solution to generate a metal carbide precursor; and a dissolution step: generating a metal carbide intermediate in which the above metal carbide precursor is dispersed in pure water.

[0111] It should be noted that the complexation step and the dissolution step in the method for manufacturing a metal carbide intermediate of the present invention are the same as the complexation step and the dissolution step in the method for manufacturing a metal carbide of the present invention described above, so detailed description is omitted.

[0112] In addition, the method for manufacturing a metal carbide intermediate of the present invention may also have a drying step: drying the metal carbide precursor generated through the above complexation step.

[0113] Here, the drying step in the method for manufacturing a metal carbide intermediate of the present invention is the same as the drying step in the method for manufacturing a metal carbide of the present invention described above, so description is omitted.

[0114] In addition, the method for manufacturing a metal carbide intermediate of the present invention is the same as the drying step in the method for manufacturing a metal carbide of the present invention described above, and the heating temperature in the drying step can be less than 100°C.

[0115] In addition, the method for manufacturing the metal carbide intermediate of the present invention is the same as the drying step in the method for manufacturing the metal carbide of the present invention described above, and the heating temperature in the drying step can be 100°C or higher.

[0116] Furthermore, the method for manufacturing the metal carbide intermediate of the present invention is the same as the drying step in the method for manufacturing the metal carbide of the present invention described above, and it can also be vacuum drying without heating.

[0117] In addition, the method for manufacturing the metal carbide intermediate of the present invention is characterized in that it has a pulverization step: pulverizing the above-mentioned metal carbide precursor dried by the above-mentioned drying step.

[0118] Here, the pulverization step in the method for manufacturing the metal carbide intermediate of the present invention is the same as the pulverization step in the method for manufacturing the metal carbide of the present invention described above, so the description is omitted.

[0119] In addition, the metal carbide powder of the present invention is characterized in that the specific surface area obtained by the BET method is 1 m 2 / g or more, and the roundness is 0.78 or more.

[0120] If the specific surface area of the metal carbide powder of the present invention obtained by the BET method is 1 m 2 / g or more, and the roundness is 0.78 or more, then even if it is an extremely fine particle, it has high fluidity.

[0121] From the viewpoints of reducing the space ratio in the powder packing layer and increasing the reactivity with other substances when used as an additive, the specific surface area of the metal carbide powder of the present invention obtained by the BET method is preferably 1 m 2 / g or more. In addition, the specific surface area of the metal carbide powder of the present invention obtained by the BET method is more preferably 2 m 2 / g or more, and further preferably 4 m 2 / g or more.

[0122] Here, the specific surface area of the metal carbide powder of the present invention obtained by the BET method can be measured in accordance with JIS Z8830 using a fully automatic specific surface area measuring device (Macsorb HM-1230 type).

[0123] In addition, from the viewpoints of reducing the space ratio in the powder packing layer and increasing the reactivity with other substances when used as an additive, the roundness of the metal carbide powder of the present invention is preferably 0.78 or more. The roundness of the metal carbide powder of the present invention is more preferably 0.8 or more, and further preferably 0.9 or more. On the other hand, the upper limit of the roundness is not particularly limited as long as it is 1 or less.

[0124] Here, the roundness of the metal carbide powder of the present invention is calculated by "roundness = 1 / major axis × minor axis", and the arithmetic mean of the roundness of multiple particles is taken as the "roundness". Here, the "major axis" and "minor axis" are calculated in the following manner. Using a scanning electron microscope (SEM) (manufactured by Hitachi High-Technologies Corporation: S-4800), the SEM image of the primary particles of the metal carbide powder of the present invention is measured at a magnification capable of measuring the primary particles of the metal carbide powder of the present invention. Then, using ImageJ of image analysis software, the "major axis" and "minor axis" of 20 randomly selected particles are measured.

[0125] In addition, it is preferable that the primary particle diameter of the metal carbide powder of the present invention obtained by the BET method is 0.7 μm or less, and the roundness is 0.78 or more.

[0126] If the primary particle diameter of the metal carbide powder of the present invention obtained by the BET method is 0.7 μm or less, and the roundness is 0.78 or more, then even if it is an extremely fine particle, it has high fluidity.

[0127] From the viewpoints of reducing the space ratio in the powder packing layer and increasing the reactivity with other substances when used as an additive, the primary particle diameter of the metal carbide powder of the present invention obtained by the BET method is preferably 0.7 μm or less. The primary particle diameter of the metal carbide powder of the present invention obtained by the BET method is more preferably 0.4 μm or less, and further preferably 0.2 μm or less.

[0128] Here, the primary particle diameter D of the metal carbide powder of the present invention obtained by the BET method is calculated by the following formula (1).

[0129]

[0130] In formula (1), "D" represents the primary particle diameter (μm) of the metal carbide powder of the present invention, "S" represents the specific surface area (m 2 / g) obtained by the BET method, and "ρ" represents the density (g / cm 3 ) of the metal carbide of the present invention. For example, the density of tantalum carbide (TaC) is 13.9 (g / cm 3 ), and the density of niobium carbide (NbC) is 8.57 (g / cm 3 ).

[0131] In addition, the metal carbide powder of the present invention preferably contains tantalum carbide, niobium carbide, titanium carbide, tungsten carbide, molybdenum carbide, zirconium carbide, etc., and more preferably contains tantalum carbide or niobium carbide.

[0132] In addition, from the viewpoint of no residual hydrogen peroxide in the metal carbide powder of the present invention, regarding the metal carbide powder of the present invention, the chlorine content in the above-mentioned metal carbide powder is preferably 100 ppm or less. Regarding the metal carbide powder of the present invention, the chlorine content in the above-mentioned metal carbide powder is more preferably 50 ppm or less, and further preferably 25 ppm or less. It should be noted that in this specification, unless otherwise specified, "ppm" refers to "mass ppm".

[0133] Here, the chlorine content in the metal carbide powder of the present invention can be measured by combustion ion chromatography. Specifically, an appropriate amount of the sample is collected on a ceramic plate, and the sample is heated in an argon (Ar) atmosphere at 1000 °C for 10 minutes by a combustion ion chromatograph (manufactured by Nittoseiko Analytech Co., Ltd.: AQF-2100H), and the amount of chlorine generated is measured, whereby the chlorine content in the metal carbide powder of the present invention can be determined.

[0134] In addition, from the viewpoint of no residual basic compounds such as ammonia water in the metal carbide powder of the present invention, regarding the metal carbide powder of the present invention, the nitrogen content in the above-mentioned metal carbide powder is preferably 1000 ppm or less. Regarding the metal carbide powder of the present invention, the nitrogen content in the above-mentioned metal carbide powder is more preferably 800 ppm or less, and further preferably 500 ppm or less. Typically, the nitrogen content in the above-mentioned metal carbide powder can also be 500 ppm or less, 250 ppm or less, 100 ppm or less, 50 ppm or less, 25 ppm or less.

[0135] Here, the nitrogen content in the metal carbide powder of the present invention can be measured by the thermal conductivity method using an oxygen and nitrogen analyzer (manufactured by LECO Corporation: ON836). Specifically, an appropriate amount of the sample can be sealed in a Ni capsule, and the nitrogen content in the metal carbide powder of the present invention can be determined by the thermal conductivity method using this oxygen and nitrogen analyzer.

[0136] In addition, the metal carbide powder of the present invention may also contain components derived from metal hydroxides, such as components derived from tantalum or tantalum hydroxide, or components other than components derived from niobium or niobium hydroxide (referred to as "other components") within a range that does not hinder their effects. Examples of other components include Li, Mg, Si, Ca, Mn, Ni, Cu, Zn, Sr, Ba, etc. However, it is not limited to these. The content of other components in the metal carbide powder of the present invention is preferably less than 5% by mass in terms of elemental conversion (metal element conversion or non-metal element conversion), more preferably less than 4% by mass, and further preferably less than 3% by mass. It should be noted that it is assumed that the metal carbide powder of the present invention contains inevitable impurities that are not intentionally added. The content of inevitable impurities is preferably less than 0.01% by mass.

[0137] In addition, the cemented carbide tool of the present invention is characterized by containing the metal carbide powder of the present invention described above.

[0138] Since the cemented carbide tool of the present invention contains the metal carbide powder of the present invention, even if it is extremely fine, it has high fluidity, high miscibility with tungsten carbide, excellent subsequent reactivity, and properties such as defect resistance, plastic deformation resistance, and abrasion resistance required for cemented carbide tools.

[0139] In addition, the metal carbide intermediate dispersion of the present invention is characterized by having a metal compound, a basic compound, hydrogen peroxide, and an organic acid, and the particle size (D50) of the particles in the metal carbide intermediate dispersion obtained by measuring the particle size distribution using the dynamic light scattering method is 1000 nm or less.

[0140] The metal compound is preferably a hydroxide, chloride, or alkoxide of tantalum, niobium, titanium, zirconium, hafnium, bismuth, molybdenum, or tungsten.

[0141] In addition, the metal compound is more preferably a metal hydroxide. Examples of the metal hydroxide include hydroxides of tantalum, niobium, titanium, zirconium, hafnium, bismuth, molybdenum, and tungsten, and tantalum hydroxide and / or niobium hydroxide are particularly preferred.

[0142] The basic compound is preferably at least one basic compound selected from ammonia, sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide, and organic nitrides. In addition, examples of the organic nitride include amine compounds, quaternary ammonium compounds, guanidine compounds, and azole compounds. Amine compounds or quaternary ammonium compounds are preferred, and methylamine, dimethylamine, tetramethylammonium hydroxide (TMAH), and tetraethylammonium hydroxide (TEAH) are more preferred. Ammonia is particularly preferred as the basic compound.

[0143] The content of the basic compound in the metal carbide intermediate dispersion of the present invention is preferably greater than 0% by mass and less than 50% by mass, more preferably 0.01% by mass or more and 4% by mass or less. From the viewpoints of reactivity and dispersibility, a larger content of the basic compound is preferred. On the other hand, since it is a volatile component, a lower content is preferred from the viewpoint of suppressing volatilization when forming a film in subsequent steps. Typically, the content of the basic compound can also be 0.1% by mass or more, 0.5% by mass or more, 1% by mass or more, 2% by mass or more, 3% by mass or more, 5% by mass or more, 8% by mass or more, 10% by mass or more. On the other hand, the content of the basic compound can also be 30% by mass or less, 25% by mass or less, 20% by mass or less, 10% by mass or less.

[0144] The content of the basic compound in the metal carbide intermediate dispersion of the present invention can be represented by the molar ratio of the basic compound to the metal compound. The molar ratio of the basic compound to the metal compound is preferably greater than 0 and less than or equal to 100, more preferably 0.001 or more and 100 or less, further preferably 0.01 or more and 150 or less, particularly preferably 0.1 or more and 30 or less, and even more particularly preferably 4 or more and 20 or less. Typically, the molar ratio of the basic compound to the metal compound can also be 0.005 or more, 0.05 or more, 0.5 or more. On the other hand, the molar ratio of the basic compound to the metal compound can also be 15 or less, 10 or less, 8 or less, 5 or less, 4 or less, 3 or less, 2 or less, 1 or less, 0.5 or less, 0.1 or less.

[0145] Here, the basic compound in the molar ratio of the basic compound to the metal compound represents the content of the basic compound in the metal carbide intermediate dispersion of the present invention. In addition, when there are two or more basic compounds contained in the metal carbide intermediate dispersion of the present invention, the content of the basic compound is the total content of the two or more basic compounds. On the other hand, the metal compound in the molar ratio of the basic compound to the metal compound represents the content of the metal compound in the metal carbide intermediate dispersion of the present invention in terms of the metal atoms. In addition, when there are two or more metal compounds contained in the metal carbide intermediate dispersion of the present invention, the content of the metal compound in terms of the metal atoms is the total content of the two or more metal compounds in terms of the metal atoms.

[0146] When the metal compound contained in the metal carbide intermediate dispersion of the present invention is tantalum hydroxide, the molar ratio of the basic compound / Ta is preferably greater than 0 and less than or equal to 100, more preferably 0.001 or more and 100 or less, still more preferably 0.01 or more and 50 or less, particularly preferably 0.1 or more and 30 or less, and even more particularly preferably 4 or more and 20 or less. Typically, the molar ratio of the basic compound / Ta can also be 0.005 or more, 0.05 or more, 0.5 or more. On the other hand, the molar ratio of the basic compound / Ta can also be 15 or less, 10 or less, 8 or less, 5 or less, 4 or less, 3 or less, 2 or less, 1 or less, 0.5 or less, 0.1 or less.

[0147] In addition, when the metal compound contained in the metal carbide intermediate dispersion of the present invention is niobium hydroxide, the molar ratio of the basic compound / Nb is preferably greater than 0 and less than or equal to 100, more preferably 0.001 or more and 100 or less, still more preferably 0.01 or more and 50 or less, particularly preferably 0.1 or more and 30 or less, and even more particularly preferably 4 or more and 20 or less. Typically, the molar ratio of the basic compound / Ta can also be 0.005 or more, 0.05 or more, 0.5 or more. On the other hand, the molar ratio of the basic compound / Nb can also be 15 or less, 10 or less, 8 or less, 5 or less, 4 or less, 3 or less, 2 or less, 1 or less, 0.5 or less, 0.1 or less.

[0148] Furthermore, when the metal compound contained in the metal carbide intermediate dispersion of the present invention is niobium hydroxide and tantalum hydroxide, the molar ratio of the basic compound to niobium and tantalum: basic compound / (Nb + Ta) is preferably greater than 0 and less than or equal to 100, more preferably 0.001 or more and 100 or less, still more preferably 0.01 or more and 50 or less, particularly preferably 0.1 or more and 30 or less, and even more particularly preferably 4 or more and 20 or less. Typically, the molar ratio of the basic compound / (Nb + Ta) can also be 0.005 or more, 0.05 or more, 0.5 or more. On the other hand, the molar ratio of the basic compound / (Nb + Ta) can also be 15 or less, 10 or less, 8 or less, 5 or less, 4 or less, 3 or less, 2 or less, 1 or less, 0.5 or less, 0.1 or less.

[0149] When the basic compound is ammonia, for example, the ammonia content is preferably greater than 0% by mass and less than 50% by mass, more preferably 0.01% by mass or more and 4% by mass or less. From the viewpoints of reactivity and dispersibility, a relatively large ammonia content is preferred. On the other hand, since it is a volatile component, a low content is preferred from the viewpoint of suppressing volatilization when forming a film in subsequent steps. Typically, the ammonia content can also be 0.1% by mass or more, 0.5% by mass or more, 1% by mass or more, 2% by mass or more, 3% by mass or more, 5% by mass or more, 8% by mass or more, 10% by mass or more. On the other hand, the ammonia content can also be 30% by mass or less, 25% by mass or less, 20% by mass or less, 10% by mass or less.

[0150] The content of ammonia contained in the metal carbide intermediate dispersion of the present invention can be represented by the molar ratio of NH3 / metal compound. The molar ratio of NH3 / metal compound is preferably greater than 0 and less than or equal to 100, more preferably 0.001 or more and 100 or less, still more preferably 0.01 or more and 50 or less, particularly preferably 0.1 or more and 30 or less, and even more particularly preferably 4 or more and 20 or less. Typically, the molar ratio of NH3 / metal compound can also be 0.005 or more, 0.05 or more, 0.5 or more. On the other hand, the molar ratio of NH3 / metal compound can also be 15 or less, 10 or less, 8 or less, 5 or less, 4 or less, 3 or less, 2 or less, 1 or less, 0.5 or less, 0.1 or less.

[0151] When the metal compound contained in the metal carbide intermediate dispersion of the present invention is tantalum hydroxide, the molar ratio of NH3 / Ta is preferably greater than 0 and less than or equal to 100, more preferably 0.001 or more and 100 or less, still more preferably 0.01 or more and 50 or less, particularly preferably 0.1 or more and 30 or less, and even more particularly preferably 4 or more and 20 or less. Typically, the molar ratio of NH3 / Ta can also be 0.005 or more, 0.05 or more, 0.5 or more. On the other hand, the molar ratio of NH3 / Ta can also be 15 or less, 10 or less, 8 or less, 5 or less, 4 or less, 3 or less, 2 or less, 1 or less, 0.5 or less, 0.1 or less.

[0152] In addition, when the metal compound contained in the metal carbide intermediate dispersion of the present invention is niobium hydroxide, the molar ratio of NH3 / Nb is preferably greater than 0 and less than or equal to 100, more preferably 0.001 or more and 100 or less, still more preferably 0.01 or more and 50 or less, particularly preferably 0.1 or more and 30 or less, and even more particularly preferably 4 or more and 20 or less. Typically, the molar ratio of NH3 / Ta can also be 0.005 or more, 0.05 or more, 0.5 or more. On the other hand, the molar ratio of NH3 / Nb can also be 15 or less, 10 or less, 8 or less, 5 or less, 4 or less, 3 or less, 2 or less, 1 or less, 0.5 or less, 0.1 or less.

[0153] Furthermore, when the metal compounds contained in the metal carbide intermediate dispersion of the present invention are niobium hydroxide and tantalum hydroxide, the molar ratio of ammonia to niobium and tantalum: NH3 / (Nb + Ta) is preferably greater than 0 and less than or equal to 100, more preferably 0.001 or more and 100 or less, still more preferably 0.01 or more and 50 or less, particularly preferably 0.1 or more and 30 or less, and even more particularly preferably 4 or more and 20 or less. Typically, the molar ratio of NH3 / (Nb + Ta) can also be 0.005 or more, 0.05 or more, 0.5 or more. On the other hand, the molar ratio of NH3 / (Nb + Ta) can also be 15 or less, 10 or less, 8 or less, 5 or less, 4 or less, 3 or less, 2 or less, 1 or less, 0.5 or less, 0.1 or less.

[0154] It should be noted that regarding the basic compound contained in the metal carbide intermediate dispersion of the present invention, by replenishing the solvent volatilized due to heating or the like after preparing the metal carbide intermediate dispersion, the amount of the basic compound can be reduced.

[0155] The content of hydrogen peroxide in the metal carbide intermediate dispersion of the present invention is preferably greater than 0% by mass and less than or equal to 35% by mass, more preferably 0.001% by mass or more and 30% by mass or less, still more preferably 0.01% by mass or more and 25% by mass or less, particularly preferably 0.1% by mass or more and 20% by mass or less. Typically, the content of this hydrogen peroxide can also be 0.005% by mass or more, 0.05% by mass or more, 0.5% by mass or more, 1% by mass or more, 2% by mass or more, 4% by mass or more. On the other hand, the content of this hydrogen peroxide can also be 10% by mass or less, 5% by mass or less, 3% by mass or less, 1% by mass or less.

[0156] The content of hydrogen peroxide in the metal carbide intermediate dispersion of the present invention can be represented by the molar ratio of H2O2 / metal compound. The molar ratio of hydrogen peroxide to metal compound, H2O2 / metal compound, is preferably greater than 0 and less than or equal to 10, more preferably 0.001 or more and 3 or less, and still more preferably 0.01 or more and 1 or less. Typically, the molar ratio H2O2 / metal compound can also be 0.005 or more, 0.05 or more, 0.5 or more. On the other hand, the molar ratio H2O2 / metal compound can also be 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less.

[0157] Here, H2O2 in the molar ratio H2O2 / metal compound represents the content of H2O2 in the metal carbide intermediate dispersion of the present invention. On the other hand, the metal compound in the molar ratio H2O2 / metal compound represents the content of the metal compound in the metal carbide intermediate dispersion of the present invention in terms of metal atoms. In addition, when there are two or more metal compounds contained in the metal carbide intermediate dispersion of the present invention, the content of the metal compound in terms of metal atoms is the total content of the above two or more metal compounds in terms of metal atoms.

[0158] When the metal compound contained in the metal carbide intermediate dispersion of the present invention is, for example, tantalum hydroxide, the molar ratio of hydrogen peroxide to tantalum, H2O2 / Ta, is preferably greater than 0 and less than or equal to 10, more preferably 0.001 or more and 3 or less, and still more preferably 0.01 or more and 1 or less. Typically, the molar ratio H2O2 / Ta can also be 0.005 or more, 0.05 or more, 0.5 or more. On the other hand, the molar ratio H2O2 / Ta can also be 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less.

[0159] In addition, when the metal compound contained in the metal carbide intermediate dispersion of the present invention is, for example, niobium hydroxide, the molar ratio of hydrogen peroxide to niobium, H2O2 / Nb, is preferably greater than 0 and less than or equal to 10, more preferably 0.001 or more and 3 or less, and still more preferably 0.01 or more and 1 or less. Typically, the molar ratio H2O2 / Nb can also be 0.005 or more, 0.05 or more, 0.5 or more. On the other hand, the molar ratio H2O2 / Nb can also be 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less.

[0160] Furthermore, when the metal compounds contained in the metal carbide intermediate dispersion of the present invention are, for example, niobium hydroxide and tantalum hydroxide, the molar ratio of hydrogen peroxide to niobium and tantalum, H2O2 / (Nb+Ta), is preferably greater than 0 and less than or equal to 10, more preferably 0.001 or more and 3 or less, and still more preferably 0.01 or more and 1 or less. Typically, the molar ratio H2O2 / (Nb+Ta) may also be 0.005 or more, 0.05 or more, 0.5 or more. On the other hand, the molar ratio H2O2 / (Nb+Ta) may also be 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less.

[0161] It should be noted that, from the viewpoint of safety (volatility, volatility caused by reaction with other materials), the content of hydrogen peroxide is preferably small. On the other hand, with the above content and molar ratio of hydrogen peroxide, good dispersibility can be obtained.

[0162] Examples of the organic acid include carboxylic acids, polyfunctional carboxylic acids, hydroxycarboxylic acids, and amino acids. Examples of the carboxylic acid include butyric acid, formic acid, acetic acid, lauric acid, oleic acid, linoleic acid, benzoic acid, etc. Examples of the polyfunctional carboxylic acid include oxalic acid, succinic acid, malonic acid, maleic acid, glutaric acid, citric acid, etc. Examples of the hydroxycarboxylic acid include lactic acid, gluconic acid, tartaric acid, malic acid, etc. Examples of the amino acid include alanine, arginine, aspartic acid, ethylenediaminetetraacetic acid, etc. Organic acids that do not contain nitrogen atoms are particularly preferred, for example, carboxylic acids, polyfunctional carboxylic acids, and hydroxycarboxylic acids are preferred, and citric acid, tartaric acid, and lactic acid are more preferred. Additionally, polyfunctional carboxylic acids are more preferred, and citric acid, which is an organic acid that does not contain nitrogen atoms and is a polyfunctional carboxylic acid, is most preferred. Various isomers (structural isomers, optical isomers, etc.) of the above compounds may also be included in the organic acid. Furthermore, one or more of the above compounds may be used as the organic acid.

[0163] The content of the organic acid is preferably greater than 0% by mass and less than 100% by mass, more preferably 1% by mass or more and 40% by mass or less, and still more preferably 3% by mass or more and 15% by mass or less. Typically, the content of the organic acid may also be 0.1% by mass or more, 0.5% by mass or more, 2% by mass or more, 5% by mass or more, 8% by mass or more, 10% by mass or more. On the other hand, the content of the organic acid may also be 30% by mass or less, 25% by mass or less, 20% by mass or less, 10% by mass or less. Here, when two or more organic acids are contained in the metal carbide intermediate dispersion of the present invention, the content of the organic acid is the total content of the two or more organic acids.

[0164] The content of the organic acid in the metal carbide intermediate dispersion of the present invention can be represented by the molar ratio of the organic acid to the metal compound. It is preferred to add an organic acid so that the molar ratio of the organic acid to the metal compound: organic acid / metal compound is greater than 0 and less than or equal to 500. From the viewpoints of the stability of the metal carbide intermediate dispersion of the present invention and cost reduction, it is more preferably 0.01 or more and 100 or less, further preferably 0.1 or more and 9 or less, and particularly preferably 0.1 or more and 6 or less. Typically, the molar ratio: organic acid / metal compound can also be 0.005 or more, 0.5 or more, 1 or more, 2 or more, 3 or more, 5 or more. On the other hand, the molar ratio: organic acid / metal compound can also be 200 or less, 50 or less, 40 or less, 30 or less, 20 or less, 10 or less, 8 or less, 5 or less.

[0165] Here, the organic acid in the molar ratio: organic acid / metal compound represents the content of the organic acid in the metal carbide intermediate dispersion of the present invention. In addition, when there are two or more kinds of organic acids contained in the metal carbide intermediate dispersion of the present invention, the content of the organic acid is the total content of the above two or more kinds of organic acids. On the other hand, the metal compound in the molar ratio: organic acid / metal compound represents the content of the metal compound in the metal carbide intermediate dispersion of the present invention in terms of the metal atom conversion. In addition, when there are two or more kinds of metal compounds contained in the metal carbide intermediate dispersion of the present invention, the content of the metal compound in terms of the metal atom conversion is the total content of the above two or more kinds of metal compounds in terms of the metal atom conversion.

[0166] When the metal hydroxide contained in the metal carbide intermediate dispersion of the present invention is tantalum hydroxide, it is preferred to add an organic acid so that the molar ratio of the organic acid to tantalum: organic acid / Ta is greater than 0 and less than or equal to 500. From the viewpoints of the stability of the metal carbide intermediate dispersion of the present invention and cost reduction, it is more preferably 0.01 or more and 100 or less, further preferably 0.1 or more and 9 or less, and particularly preferably 0.1 or more and 6 or less. Typically, the molar ratio: organic acid / Ta can also be 0.005 or more, 0.5 or more, 1 or more, 2 or more, 3 or more, 5 or more. On the other hand, the molar ratio: organic acid / Ta can also be 200 or less, 50 or less, 40 or less, 30 or less, 20 or less, 10 or less, 8 or less, 5 or less.

[0167] In addition, in the case of niobium hydroxide contained in the metal carbide intermediate dispersion of the present invention, it is preferable to add an organic acid so that the molar ratio of the organic acid to niobium: organic acid / Nb is greater than 0 and less than or equal to 500. From the viewpoints of the stability and cost reduction of the metal carbide intermediate dispersion of the present invention, it is more preferably 0.01 or more and 100 or less, further preferably 0.1 or more and 9 or less, and particularly preferably 0.1 or more and 6 or less. Typically, the molar ratio: organic acid / Nb can also be 0.005 or more, 0.5 or more, 1 or more, 2 or more, 3 or more, 5 or more. On the other hand, the molar ratio: organic acid / Nb can also be 200 or less, 50 or less, 40 or less, 30 or less, 20 or less, 10 or less, 8 or less, 5 or less.

[0168] Furthermore, when the metal hydroxide contained in the metal carbide intermediate dispersion of the present invention is niobium hydroxide and tantalum hydroxide, it is preferable to add an organic acid so that the molar ratio of the organic acid to niobium and tantalum: organic acid / (Nb + Ta) is greater than 0 and less than or equal to 500. From the viewpoints of the stability and cost reduction of the metal carbide intermediate dispersion of the present invention, it is more preferably 0.01 or more and 100 or less, further preferably 0.1 or more and 9 or less, and particularly preferably 0.1 or more and 6 or less. Typically, the molar ratio: organic acid / (Nb + Ta) can also be 0.005 or more, 0.5 or more, 1 or more, 2 or more, 3 or more, 5 or more. On the other hand, the molar ratio: organic acid / (Nb + Ta) can also be 200 or less, 50 or less, 40 or less, 30 or less, 20 or less, 10 or less, 8 or less, 5 or less.

[0169] Furthermore, the metal carbide intermediate dispersion of the present invention may also have water, an organic solvent, and a mixed solvent thereof as a solvent. In addition, examples of the organic solvent include: alcohol solvents, ketone solvents, ether solvents, ester solvents, aromatic hydrocarbon solvents, aliphatic hydrocarbon solvents, etc., and it may also be a solvent obtained by mixing these organic solvents with pure water. In addition, examples of the alcohol solvent include: alcohols having 5 or less carbon atoms (methanol, ethanol, n-propanol, isopropanol, butanol, ethylene glycol, propylene glycol), high-boiling solvents, acetone, etc. It is preferable that the above solvents are miscible with water. Examples of the high-boiling solvent include: polyol solvents, glycol solvents. From the viewpoint of maintaining high dispersibility, the solvent contained in the metal carbide intermediate dispersion of the present invention is preferably water.

[0170] In addition, the solvent may also be a solvent added with a resin such as a polyolefin-based compound or a polyvinyl-based compound. In addition, as the resin added to the solvent, it may also be an anionic water-soluble resin and / or a non-ionic water-soluble resin.

[0171] As described above, the metal carbide intermediate dispersion of the present invention contains a metal compound, a basic compound, hydrogen peroxide, and an organic acid, and it is speculated that at least a part of them forms a peroxy complex containing a metal element derived from the metal compound.

[0172] In addition, regarding the metal carbide intermediate dispersion of the present invention, from the viewpoint of stability over time, the particle size (D50) of the particles in the above-mentioned metal carbide intermediate dispersion obtained by measuring the particle size distribution using the dynamic light scattering method is preferably 1000 nm or less, more preferably 500 nm or less, and particularly preferably 100 nm or less. Typically, the particle size (D50) can also be 900 nm or less, 800 nm or less, 700 nm or less, 600 nm or less, 400 nm or less, 300 nm or less, 200 nm or less, 50 nm or less, 30 nm or less, 20 nm or less, 10 nm or less, 6 nm or less, 2 nm or less, 1 nm or less, 0.6 nm or less. On the other hand, the particle size (D50) of the particles in the metal carbide intermediate dispersion of the present invention is preferably 1 nm or more, more preferably 2 nm or more, further preferably 6 nm or more, and particularly preferably 10 nm or more. Moreover, it can also be 100 nm or more, 200 nm or more, 300 nm or more, 400 nm or more, 500 nm or more. Typically, the particle size (D50) of the particles in the metal carbide intermediate dispersion of the present invention is 10 nm or more and 800 nm or less.

[0173] Specifically, the evaluation method of the particle size distribution is carried out in accordance with JIS Z 8828:2019 "Particle Size Analysis - Dynamic Light Scattering Method" using a Zeta potential / particle size / molecular weight measurement system (manufactured by Otsuka Electronics Co., Ltd.: ELSZ-2000ZS). In addition, a sample diluted 1000 times with pure water as needed is used as the measurement sample. In order to remove dust and the like in the measurement sample immediately before measurement, the measurement sample is filtered through a filter with a pore size of 11 μm, and ultrasonic treatment is carried out for 3 minutes using an ultrasonic cleaner (manufactured by ASONE Corporation: VS-100III). Furthermore, the liquid temperature of the measurement sample is adjusted to 25°C. It should be noted that the particle size (D50) of the particles in the metal carbide intermediate dispersion of the present invention refers to the median particle size (D50), which is the particle size representing the 50% cumulative value of the cumulative distribution curve. In addition, in this specification, unless otherwise specified, "particle size (D50)" includes all of the following particle sizes (D50): the particle size (D50) of the particles in the metal carbide intermediate dispersion of the present invention adjusted to a liquid temperature of 25°C immediately after generation; and the particle size (D50) of the particles in the metal carbide intermediate dispersion after standing for 2 weeks or 3 weeks from the date of generating the metal carbide intermediate dispersion in a thermostat set at room temperature of 25°C.

[0174] In addition, the metal carbide intermediate dispersion of the present invention is characterized in that it contains a metal compound, a basic compound, hydrogen peroxide, and an organic acid, and the maximum value of the light transmittance in the wavelength range of 350 nm to 750 nm of the above metal carbide intermediate dispersion is 70% or more.

[0175] In addition, the metal carbide intermediate dispersion of the present invention contains a metal compound, a basic compound, hydrogen peroxide, and an organic acid as described above. It should be noted that the metal carbide intermediate dispersion of the present invention may also contain water, an organic solvent, or a mixed solvent thereof as a solvent as described above.

[0176] In addition, from the viewpoint of high dispersion and excellent uniformity of the components in the liquid, the maximum value of the light transmittance in the wavelength range of 350 nm to 750 nm of the metal carbide intermediate dispersion of the present invention is preferably 70% or more. The maximum value of the light transmittance in the wavelength range of 350 nm to 750 nm is more preferably 85% or more, further preferably 90% or more, and most preferably 100%. Typically, the maximum value of the light transmittance may be 72% or more, 74% or more, 76% or more, 78% or more, 80% or more, 90% or more, 98% or more, or 99% or more.

[0177] In addition, the light transmittance of the metal carbide intermediate dispersion of the present invention at any one or more wavelengths among 350 nm, 450 nm, 550 nm, 650 nm, and 750 nm is preferably 70% or more, more preferably 85% or more, further preferably 90% or more, and most preferably 100%. Typically, the light transmittance at any one or more wavelengths among 350 nm, 450 nm, 550 nm, 650 nm, and 750 nm may be 72% or more, 74% or more, 76% or more, 78% or more, 80% or more, 90% or more, 98% or more, or 99% or more.

[0178] Furthermore, the light transmittance of the metal carbide intermediate dispersion of the present invention in the wavelength range of 350 nm to 750 nm is preferably 70% or more, more preferably 85% or more, further preferably 90% or more, and most preferably 100%. Typically, the light transmittance in the wavelength range of 350 nm to 750 nm may be 72% or more, 74% or more, 76% or more, 78% or more, 80% or more, 90% or more, 98% or more, or 99% or more.

[0179] It should be noted that due to measurement errors and the like, the measured value of the above-mentioned light transmittance may be greater than 100%, but the theoretical upper limit is 100%. Therefore, when the measured value is greater than 100%, it is regarded as 100%. In this way, the liquid in a state where the maximum value of the light transmittance of the metal carbide intermediate dispersion liquid of the present invention in the wavelength range of 350 nm to 750 nm is 70% or more is denoted as the "metal carbide intermediate dispersion liquid" of the present invention. In addition, in this specification, unless otherwise specified, the "light transmittance" includes all of the following light transmittances: the light transmittance of the metal carbide intermediate dispersion liquid of the present invention adjusted to a liquid temperature of 25 °C immediately after generation; and the light transmittance of the metal carbide intermediate dispersion liquid after standing for 2 weeks or 3 weeks from the date of generation of the metal carbide intermediate dispersion liquid of the present invention in a thermostat set at room temperature of 25 °C.

[0180] Here, the above-mentioned light transmittance is measured for the metal carbide intermediate dispersion liquid of the present invention using a spectrophotometer according to the following transmittance measurement conditions.

[0181] = Light transmittance measurement conditions =

[0182] · Measuring device: UV / Visible / Near-Infrared Spectrophotometer Model UH4150 (manufactured by Hitachi High-Tech Science Corporation)

[0183] · Measurement mode: Wavelength scanning

[0184] · Data mode: %T (transmission)

[0185] · Measurement wavelength range: 200 nm to 2000 nm

[0186] · Scanning speed: 600 nm / min

[0187] · Sampling interval: 2 nm

[0188] It should be noted that the "dispersion liquid" in the present invention is not limited to a solute dispersed or mixed in a solvent in a single-molecule state, and also includes aggregates in which multiple molecules are attracted by intermolecular interactions, such as (1) polymer molecules, (2) solvated molecules, (3) molecular clusters, (4) colloidal particles, etc. dispersed in a solvent.

[0189] In addition, the metal carbide intermediate dispersion liquid of the present invention is characterized in that the pH is 3.0 or more and 10.0 or less.

[0190] From the perspective of the stability of the polyacid ions contained in the dispersion, the pH of the metal carbide intermediate dispersion of the present invention is preferably 3.0 or more and 10.0 or less. The pH of the metal carbide intermediate dispersion of the present invention is more preferably 4.0 or more and 7.0 or less, and further preferably 4.7 or more and 6.5 or less. Typically, the pH can be 5.0 or more, can be 6.0 or more, or can be 6.5 or more. On the other hand, the pH can be 9.0 or less, or can be 8.0 or less. It should be noted that in this specification, unless otherwise specified, "pH" refers to all of the following pH values: the pH of the metal carbide intermediate dispersion of the present invention adjusted to a liquid temperature of 25 °C immediately after generation; and the pH of the metal carbide intermediate dispersion after standing for 2 weeks or 3 weeks from the date of generation of the metal carbide intermediate dispersion of the present invention in a thermostat set at room temperature of 25 °C.

[0191] Here, regarding the measurement of the pH of the metal carbide intermediate dispersion of the present invention, the electrode of a pH meter (manufactured by HORIBA: glass electrode type hydrogen ion concentration indicator D-51) (manufactured by HORIBA: standard ToupH electrode 9615S-10D) is immersed in the metal carbide intermediate dispersion of the present invention, and the measurement is carried out after confirming that the liquid temperature is stable at 25 °C.

[0192] In addition, the metal carbide intermediate dispersion of the present invention is characterized in that the molar ratio of the above organic acid to the above metal compound is greater than 0 and less than or equal to 500, the molar ratio of the above hydrogen peroxide to the above metal compound is greater than 0 and less than or equal to 10, and the molar ratio of the above basic compound to the above metal compound is greater than 0 and less than or equal to 100.

[0193] From the perspective of the stability and dispersibility of the metal carbide intermediate dispersion of the present invention, in the metal carbide intermediate dispersion of the present invention, the molar ratio of the above organic acid to the above metal compound is preferably greater than 0 and less than or equal to 500, the molar ratio of the above hydrogen peroxide to the above metal compound is preferably greater than 0 and less than or equal to 10, and the molar ratio of the above basic compound to the above metal compound is preferably greater than 0 and less than or equal to 100.

[0194] The molar ratio of the organic acid to the metal compound is preferably greater than 0 and less than or equal to 500, more preferably 0.01 to 100, further preferably 0.1 to 9, and particularly preferably 0.1 to 6. The molar ratio of the hydrogen peroxide to the metal compound is preferably greater than 0 and less than or equal to 10, more preferably 0.001 to 3, and further preferably 0.01 to 1. The molar ratio of the basic compound to the metal compound is preferably greater than 0 and less than or equal to 100, more preferably 0.001 to 100, further preferably 0.01 to 50, particularly preferably 0.1 to 30, and more particularly preferably 4 to 20.

[0195] Here, the molar ratio of the organic acid to the metal compound, the molar ratio of hydrogen peroxide to the metal compound, and the molar ratio of the basic compound to the metal compound can be obtained by calculating the contents of the metal compound, the organic acid, the hydrogen peroxide, and the basic compound using the following measurement methods.

[0196] The content of the metal compound in the metal carbide intermediate dispersion of the present invention can be calculated by appropriately diluting the dispersion with dilute hydrochloric acid as needed, using ICP emission analysis (manufactured by Agilent Technologies: AG-5110), and measuring the mass fraction of metal atoms in terms of metal atoms in the metal compound according to JIS K0116:2014.

[0197] Examples of the measurement method for the content of the organic acid in the metal carbide intermediate dispersion of the present invention include gas chromatography (GC), liquid chromatography (LC), mass spectrometry (MS), gas chromatography - mass spectrometry (GC-MS), liquid chromatography - mass spectrometry (LC-MS), and the like.

[0198] Regarding the hydrogen peroxide content in the metal carbide intermediate dispersion of the present invention, for example, by using the standard addition method and measuring the relative intensity of the absorbance of the standard solution of hydrogen peroxide, the hydrogen peroxide content in the dispersion can be confirmed. Specifically, it is found that in the wavelength region where the absorbance change accompanied by the formation of a peroxo complex is observed from the ultraviolet-visible absorption spectra of the standard solution with a known concentration, for example, a standard solution containing 1% by mass of hydrogen peroxide and the standard solution without added hydrogen peroxide, if the difference in absorbance between the standard solution without added hydrogen peroxide and the sample with an unknown hydrogen peroxide concentration in this wavelength region is less than 1%, it can be confirmed that the sample with an unknown hydrogen peroxide concentration substantially does not contain hydrogen peroxide. When the dispersion contains hydrogen peroxide, hydrogen peroxide reacts with the polyacid of the metal element to form a peroxo complex. Therefore, by confirming the difference in absorbance of the standard solution without added hydrogen peroxide as described above, it can be confirmed that the dispersion does not contain hydrogen peroxide. In addition to the above standard addition method, there are also the following methods: for example, using a commercially available hydrogen peroxide measurement kit, adding a reagent that undergoes a color reaction with hydrogen peroxide to the dispersion and measuring its color development; and also adding a reagent that undergoes a fluorescence reaction with hydrogen peroxide to the dispersion and measuring its luminescence, thereby performing qualitative and quantitative analysis of the hydrogen peroxide in the dispersion.

[0199] Examples of the method for measuring the content of the basic compound, such as ammonia content, in the metal carbide intermediate dispersion of the present invention include: a method of adding sodium hydroxide to the dispersion and distilling and separating ammonia, and quantifying the ammonia content with an ion meter; a method of quantifying the N2 component in the vaporized sample with a thermal conductivity analyzer; the Kjeldahl method, etc. A method of quantifying the ammonia content with an ion meter is particularly preferred. In addition, examples of the method for measuring the content of the organic nitride include: gas chromatography (GC), ion chromatography, gas chromatography-mass spectrometry (GC-MS), etc. For example, the content of the organic nitride selected from one or more of sodium hydroxide, potassium hydroxide, lithium hydroxide, and calcium hydroxide can be measured by ICP emission analysis in accordance with JIS K0116:2014.

[0200] The molar ratio of the organic acid to the metal compound, the molar ratio of hydrogen peroxide to the metal compound, and the molar ratio of the basic compound to the metal compound can be calculated from the metal compound content, organic acid content, hydrogen peroxide content, and basic compound content calculated in this way.

[0201] In addition, the metal carbide intermediate dispersion of the present invention is characterized in that the tantalum content in terms of Ta in the metal carbide intermediate dispersion is 0.4% by mass or more, or the niobium content in terms of Nb is 0.35% by mass or more.

[0202] From the viewpoint of increasing the film thickness of the metal carbide film during film formation, it is preferred that the tantalum content in terms of Ta in the metal carbide intermediate dispersion of the present invention is 0.4% by mass or more, or the niobium content in terms of Nb is 0.35% by mass or more. In addition, the tantalum content in terms of Ta in the metal carbide intermediate dispersion of the present invention is more preferably 10% by mass or more, and further preferably 20% by mass or more. In addition, the niobium content in terms of Nb in the metal carbide intermediate dispersion of the present invention is more preferably 20% by mass or more, and further preferably 30% by mass or more.

[0203] As described above, the tantalum content or niobium content in the metal carbide intermediate dispersion of the present invention can be measured and calculated by ICP emission analysis (manufactured by Agilent Technologies: AG-5110) in accordance with JIS K0116:2014 to obtain the Ta mass fraction in terms of Ta or the Nb mass fraction in terms of Nb.

[0204] It should be noted that in this specification, when expressed as "X to Y" (where X and Y are arbitrary numbers), unless otherwise specified, it includes the meaning of "X or more and Y or less", and also includes the meaning of "preferably greater than X" or "preferably less than Y". In addition, when expressed as "X or more" (where X is an arbitrary number) or "Y or less" (where Y is an arbitrary number), it also includes the meaning of "preferably greater than X" or "preferably less than Y".

[0205] Advantages of the Invention

[0206] The method for manufacturing a metal carbide of the present invention can manufacture metal carbide powder with extremely fine particles and high fluidity. In addition, the metal carbide of the present invention exhibits high fluidity even when it is in the form of extremely fine particles. Furthermore, the metal carbide intermediate dispersion liquid of the present invention is a dispersion liquid with high dispersibility and does not precipitate even after a long time. BRIEF DESCRIPTION OF THE DRAWINGS

[0207] Figure 1 It is a list of physical property values of the metal carbide intermediate dispersion liquids of Examples 3 to 10 and Comparative Examples 8 to 10.

[0208] Figure 2 It is a list of measurement results of the metal carbide intermediate dispersion liquids of Examples 3 to 10 and Comparative Examples 8 to 10. DETAILED DESCRIPTION OF THE INVENTION

[0209] Hereinafter, the metal carbide according to the embodiment of the present invention will be further described with reference to the following Examples 1 and 2 and Comparative Examples 1 to 7. However, the following examples do not limit the present invention.

[0210] (Example 1)

[0211] 200 g of tantalum hydroxide and 92 g of 25% by mass ammonia water were stirred and mixed for 10 minutes to obtain a first mixed solution. Then, 220 g of 35% by mass hydrogen peroxide solution was added to the first mixed solution and stirred for 10 minutes to obtain a second mixed solution. Then, 79 g of citric acid was added to the second mixed solution and stirred for 10 minutes to obtain a peroxy complex aqueous dispersion liquid of Example 1 containing tantalum, which is the metal carbide precursor of Example 1.

[0212] The obtained peroxy complex aqueous dispersion liquid of Example 1 was a transparent solution without precipitation immediately after its production, and was also a transparent solution without precipitation 7 days after production. In addition, the concentration of the peroxy complex dispersion liquid of Example 1 in terms of Ta2O5 was 175 g / L 7 days after production. Furthermore, the average particle diameter of the peroxy complex aqueous dispersion liquid of Example 1 obtained by the dynamic light scattering method was 625.2 nm 7 days after production.

[0213] Then, a powdery metal carbide and a film-shaped metal carbide are produced from the peroxy complex aqueous dispersion of Example 1.

[0214] First, the peroxy complex aqueous dispersion of Example 1 is placed in a stationary furnace and heated and dried at a heating temperature of 110 °C for 12 hours to obtain a tantalum-containing peroxy complex powder. Further, the tantalum-containing peroxy complex powder is filled into a carbon crucible and then placed in a high-temperature vacuum furnace, and fired at a firing temperature of 1500 °C for 1 hour under the atmosphere to obtain tantalum carbide. Then, the obtained tantalum carbide is pulverized using a ball mill or the like to obtain the powdery metal carbide of Example 1, i.e., tantalum carbide powder. Regarding the tantalum carbide powder of Example 1, from the results of XRD measurement obtained according to the above X-ray diffraction measurement conditions and X-ray diffraction analysis conditions, peaks are observed in the range of 2θ = 33° to 90°, and thus it is confirmed to be tantalum carbide (TaC, ICDD Card No. 00-019-1292).

[0215] Next, the peroxy complex aqueous dispersion of Example 1 is coated on a carbon black substrate, and the carbon black substrate coated with the peroxy complex aqueous dispersion of Example 1 is placed in a stationary furnace and dried at a heating temperature of 110 °C for 10 minutes. Then, the carbon black substrate coated with the dried peroxy complex aqueous dispersion of Example 1 is placed in a high-temperature vacuum furnace and fired at a firing temperature of 1600 °C for 60 minutes under the atmosphere to obtain the film-shaped metal carbide of Example 1, i.e., tantalum carbide film. Regarding the tantalum carbide film of Example 1, from the results of XRD measurement obtained according to the above X-ray diffraction measurement conditions and X-ray diffraction analysis conditions, peaks are observed in the range of 2θ = 33 to 90°, and thus it is confirmed to be a single phase of tantalum carbide (TaC, ICDD Card No. 00-019-1292).

[0216] (Example 2)

[0217] 100 g of niobium hydroxide, 153 g of 25 mass% ammonia water, and 365 g of 35 mass% hydrogen peroxide water are mixed and stirred for 10 minutes to obtain a mixed solution. Then, 87.6 g of citric acid is added to the mixed solution and stirred for 10 minutes to obtain a peroxy complex dispersion containing niobium, which is the metal carbide precursor of Example 2.

[0218] The obtained peroxy complex dispersion of Example 2 is a transparent solution without precipitation immediately after production, and is also a transparent solution without precipitation 7 days after production. In addition, the concentration of the peroxy complex dispersion of Example 2 7 days after production in terms of Nb2O5 is 133 g / L. Further, the average particle diameter of the peroxy complex dispersion of Example 2 obtained by the dynamic light scattering method 7 days after production is 540 nm.

[0219] Then, a metal carbide in powder form and a metal carbide in film form are produced from the peroxy complex aqueous dispersion of Example 2.

[0220] First, the peroxy complex dispersion of Example 2 is placed in a stationary furnace and heated and dried at a heating temperature of 110 °C for 12 hours to obtain a niobium-containing peroxy complex powder. Furthermore, the niobium-containing peroxy complex powder is filled into a carbon crucible and then placed in a high-temperature vacuum furnace, and fired at a firing temperature of 1500 °C for 1 hour in the atmosphere to obtain niobium carbide. Then, the obtained niobium carbide is pulverized using a ball mill or the like to obtain the niobium carbide powder of the metal carbide of Example 2. Regarding the niobium carbide powder of Example 2, from the results of XRD measurement obtained according to the above X-ray diffraction measurement conditions and X-ray diffraction analysis conditions, peaks are observed in the range of 2θ = 33° to 90°, and thus it is confirmed to be niobium carbide (TaNb, PDF Card No. 01-076-7071).

[0221] Next, the peroxy complex aqueous dispersion of Example 2 is coated on a carbon black substrate, and the carbon black substrate coated with the peroxy complex aqueous dispersion of Example 2 is placed in a stationary furnace and dried at a heating temperature of 110 °C for 10 minutes. Then, the carbon black substrate coated with the dried peroxy complex aqueous dispersion of Example 1 is placed in a high-temperature vacuum furnace and fired at a firing temperature of 1600 °C for 60 minutes in the atmosphere to obtain the niobium carbide film, which is the metal carbide in film form of Example 2. Regarding the niobium carbide film of Example 2, from the results of XRD measurement obtained according to the above X-ray diffraction measurement conditions and X-ray diffraction analysis conditions, peaks are observed in the range of 2θ = 33° to 90°, and thus it is confirmed to be niobium carbide (TaNb, PDF Card No. 01-076-7071).

[0222] (Comparative Example 1)

[0223] Weigh 120 kg of tantalum oxide and 22 kg of carbon black using a platform scale and stir and mix them for 5 minutes using a vertical mixer to obtain a mixed powder.

[0224] The mixed powder is filled into carbon containers (2 kg / each) and supplied to a resistance-heated hydrogen furnace at a rate of 2 each 3 hours, and fired at a temperature of 1700 °C for 14 hours to perform primary carbonization and obtain a primary carbide.

[0225] The primary carbide is filled into a carbon crucible (100 kg / each), placed in a high-frequency induction heating vacuum furnace, and fired at a temperature of 1800 °C for 5 hours to obtain a secondary carbide.

[0226] The secondary carbides cooled to room temperature in a high-frequency induction heating type vacuum furnace were taken out from a carbon crucible and coarsely crushed using a jaw crusher to make them into lumps with a diameter of 2 cm or less.

[0227] After coarse crushing, the coarsely crushed secondary carbides were finely crushed for 20 hours using a ball mill filled with iron balls of 20 - 50 mmφ.

[0228] Then, the undersize fraction (fine particle side) obtained by classifying the finely crushed secondary carbides through a vibrating sieve was collected, and thus the metal carbide of Comparative Example 1, i.e., powdered tantalum carbide, was obtained.

[0229] (Comparative Example 2)

[0230] In Comparative Example 2, the coarsely crushed secondary carbides were finely crushed using a jet mill, an air classifier with a set air velocity of 2.5 m 3 / min and a sample feeding rate of 10 kg / hour. Except for this, the same manufacturing method as in Comparative Example 1 was carried out to obtain the metal carbide of Comparative Example 2, i.e., powdered tantalum carbide.

[0231] (Comparative Example 3)

[0232] In Comparative Example 3, tantalum oxide was changed to niobium oxide, and the addition amount of carbon black was made 13 kg. Except for this, the same manufacturing method as in Comparative Example 1 was carried out to obtain the metal carbide of Comparative Example 3, i.e., powdered niobium carbide.

[0233] (Comparative Example 4)

[0234] 50 g of tantalum pentachloride was dissolved in a small amount of methanol, water was added, and then 25 mass% ammonia water was added to obtain a precipitate of tantalum hydrate Ta2O5·nH2O. After washing this precipitate with water to remove chloride ions, 12.57 g of citric acid and 46 g of 25 mass% ammonia water were added and mixed, then 109 g of 35 mass% hydrogen peroxide solution was added and stirred for 10 minutes to obtain a metal carbide precursor of Comparative Example 4, i.e., a peroxy complex dispersion containing tantalum.

[0235] The obtained peroxy complex dispersion of Comparative Example 4 was a transparent solution with a white precipitate just after manufacture, and also a transparent solution with a white precipitate 7 days after manufacture. In addition, the concentration of the dispersion obtained by separating the white precipitate from the peroxy complex dispersion of Comparative Example 4 7 days after manufacture in terms of Ta2O5 was 39 g / L. Furthermore, the peroxy complex dispersion of Comparative Example 4 7 days after manufacture produced a white precipitate, and it was difficult to measure the average particle size by the dynamic light scattering method.

[0236] Then, in the same manner as in Example 1, the peroxy complex dispersion of Comparative Example 4 was placed in a stationary furnace and heated and dried at a heating temperature of 110°C for 12 hours to obtain a dry powder. The obtained dry powder was filled into a carbon crucible and then placed in a high-temperature vacuum furnace, and fired at a firing temperature of 1500°C for 1 hour under the atmosphere to obtain a fired powder. It should be noted that the obtained fired powder was confirmed by XRD measurement according to the above X-ray diffraction measurement conditions and X-ray diffraction analysis conditions, and as a result, no peak was found in the range of 2θ = 33° to 90°, confirming that no carbonization reaction occurred.

[0237] (Comparative Example 5)

[0238] In Comparative Example 5, 37.4 g of lactic acid was used instead of citric acid in Comparative Example 4, and the same manufacturing method as in Comparative Example 4 was carried out to obtain the peroxy complex dispersion of Comparative Example 5.

[0239] The obtained peroxy complex dispersion of Comparative Example 5 was a transparent solution with white precipitate immediately after production, and was also a transparent solution with white precipitate 7 days after production. In addition, the concentration of the dispersion obtained by separating the white precipitate from the peroxy complex dispersion of Comparative Example 5 7 days after production by a centrifuge in terms of Ta2O5 was 2 g / L. Furthermore, the peroxy complex dispersion of Comparative Example 5 7 days after production produced white precipitate, and it was difficult to measure the average particle size by the dynamic light scattering method.

[0240] Then, in the same manner as in Example 1, the peroxy complex dispersion of Comparative Example 5 was placed in a stationary furnace and heated and dried at a heating temperature of 110°C for 12 hours to obtain a dry powder. The obtained dry powder was filled into a carbon crucible and then placed in a high-temperature vacuum furnace, and fired at a firing temperature of 1500°C for 1 hour under the atmosphere to obtain a fired powder. It should be noted that the obtained fired powder was confirmed by XRD measurement according to the above X-ray diffraction measurement conditions and X-ray diffraction analysis conditions, and as a result, no peak was found in the range of 2θ = 33° to 90°, confirming that no carbonization reaction occurred.

[0241] (Comparative Example 6)

[0242] In Comparative Example 6, 92.3 g of tartaric acid was used instead of citric acid in Comparative Example 4, and the same manufacturing method as in Comparative Example 4 was carried out to obtain the peroxy complex dispersion of Comparative Example 6.

[0243] The obtained peroxy complex dispersion of Comparative Example 6 was a transparent solution with white precipitate just after its production, and also a transparent solution with white precipitate 7 days after production. In addition, the concentration of the dispersion obtained by separating the white precipitate from the peroxy complex dispersion of Comparative Example 6 7 days after production by a centrifuge, in terms of Ta2O5, was <1 g / L. Furthermore, the peroxy complex dispersion of Comparative Example 6 7 days after production produced white precipitate, and it was difficult to measure the average particle size by the dynamic light scattering method.

[0244] Then, in the same manner as in Example 1, the peroxy complex dispersion of Comparative Example 6 was placed in a stationary furnace and heated and dried at a heating temperature of 110°C for 12 hours to obtain a dried powder. The obtained dried powder was filled into a carbon crucible, and then placed in a high-temperature vacuum furnace and fired at a firing temperature of 1500°C for 1 hour under the atmosphere to obtain a fired powder. It should be noted that the obtained fired powder was confirmed by XRD measurement according to the above X-ray diffraction measurement conditions and X-ray diffraction analysis conditions. As a result, no peak was found in the range of 2θ = 33° to 90°, and it was confirmed that no carbonization reaction occurred.

[0245] (Comparative Example 7)

[0246] In Comparative Example 7, 120.2 g of EDTA (ethylenediaminetetraacetic acid) was used instead of citric acid in Comparative Example 4, and the same production method as in Comparative Example 4 was carried out to obtain the peroxy complex dispersion of Comparative Example 7.

[0247] The obtained peroxy complex dispersion of Comparative Example 7 was a transparent solution with white precipitate just after its production, and also a transparent solution with white precipitate 7 days after production. In addition, the concentration of the dispersion obtained by separating the white precipitate from the peroxy complex dispersion of Comparative Example 7 7 days after production by a centrifuge, in terms of Ta2O5, was <1 g / L. Furthermore, the peroxy complex dispersion of Comparative Example 7 7 days after production produced white precipitate, and it was difficult to measure the average particle size by the dynamic light scattering method.

[0248] Then, in the same manner as in Example 1, the peroxy complex dispersion of Comparative Example 7 was placed in a stationary furnace and heated and dried at a heating temperature of 110°C for 12 hours to obtain a dried powder. The obtained dried powder was filled into a carbon crucible, and then placed in a high-temperature vacuum furnace and fired at a firing temperature of 1500°C for 1 hour under the atmosphere to obtain a fired powder. It should be noted that the obtained fired powder was confirmed by XRD measurement according to the above X-ray diffraction measurement conditions and X-ray diffraction analysis conditions. As a result, no peak was found in the range of 2θ = 33° to 90°, and it was confirmed that no carbonization reaction occurred.

[0249] Next, the metal carbide intermediate dispersion of the embodiment of the present invention will be further described by Examples 3 to 10 and Comparative Examples 8 to 10 below. However, the following examples do not limit the present invention.

[0250] (Example 3)

[0251] 200 g of tantalum hydroxide and 92 g of 25% by mass ammonia water were stirred and mixed for 10 minutes to obtain a first mixed solution. Thereafter, 220 g of 35% by mass hydrogen peroxide water was added to the first mixed solution and stirred for 10 minutes to obtain a second mixed solution. Then, 79 g of citric acid was added to the second mixed solution and stirred for 10 minutes to obtain the metal carbide intermediate dispersion of Example 3. It should be noted that the metal carbide intermediate dispersion of Example 3 is the same dispersion as the peroxy complex aqueous dispersion of Example 1 which is the metal carbide precursor of Example 1 containing tantalum.

[0252] The content in terms of Ta in the obtained metal carbide intermediate dispersion of Example 3 was 0.050 mol (the content in terms of Ta was 18.800% by mass). In addition, the hydrogen peroxide content was 0.009 mol (0.3% by mass), the ammonia content was 0.2 mol (3.6% by mass). Furthermore, the organic acid (citric acid) content was 0.07 mol (14% by mass). Then, the remainder was water.

[0253] (Example 4)

[0254] 200 g of niobium hydroxide, 100 g of 25% by mass ammonia water and 235 g of 35% by mass hydrogen peroxide water were mixed and stirred for 10 minutes to obtain a mixed solution. Thereafter, 75 g of citric acid was added to the mixed solution and stirred for 10 minutes to obtain the metal carbide intermediate dispersion of Example 4.

[0255] The content in terms of Nb in the obtained metal carbide intermediate dispersion of Example 4 was 0.020 mol (the content in terms of Nb was 3.495% by mass). In addition, the hydrogen peroxide content was 0.009 mol (0.3% by mass), the ammonia content was 0.2 mol (3.6% by mass). Furthermore, the organic acid (citric acid) content was 0.07 mol (14% by mass). Then, the remainder was water.

[0256] (Example 5)

[0257] Example 5 was obtained by adding 79 g of citric acid and 5 g of lactic acid to the second mixed solution obtained by the same production method as in Example 3 and stirring for 10 minutes to obtain the metal carbide intermediate dispersion of Example 5.

[0258] The content in terms of Ta in the obtained metal carbide intermediate dispersion of Example 5 was 0.010 mol (the content in terms of Ta was 4.095% by mass). In addition, the hydrogen peroxide content was 0.009 mol (0.3% by mass), and the ammonia content was 0.2 mol (3.6% by mass). Furthermore, the total content of organic acids (citric acid, lactic acid) was 0.08 mol (15% by mass), and the details of this total content were that the citric acid content was 0.07 mol (14% by mass) and the lactic acid content was 0.010 mol (1% by mass). Then, the remainder was water.

[0259] (Example 6)

[0260] Example 6 was obtained by adding 58 g of tartaric acid to the second mixed solution obtained by the same production method as in Example 3 and stirring for 10 minutes to obtain the metal carbide intermediate dispersion of Example 6.

[0261] The content in terms of Ta in the obtained metal carbide intermediate dispersion of Example 6 was 0.010 mol (the content in terms of Ta was 4.095% by mass). In addition, the hydrogen peroxide content was 0.009 mol (0.3% by mass), and the ammonia content was 0.2 mol (3.6% by mass). Furthermore, the content of the organic acid (tartaric acid) was 0.09 mol (14% by mass). Then, the remainder was water.

[0262] (Example 7)

[0263] 200 g of niobium hydroxide, 100 g of 25% by mass ammonia water, and 235 g of 35% by mass hydrogen peroxide water were mixed and stirred for 10 minutes to obtain a mixed solution. Then, 75 g of citric acid and 5 g of lactic acid were added to the mixed solution and stirred for 10 minutes to obtain the metal carbide intermediate dispersion of Example 7.

[0264] The content in terms of Nb in the obtained metal carbide intermediate dispersion of Example 7 was 0.015 mol (the content in terms of Nb was 3.495% by mass). In addition, the hydrogen peroxide content was 0.009 mol (0.3% by mass), and the ammonia content was 0.2 mol (3.6% by mass). Furthermore, the total content of organic acids (citric acid, lactic acid) was 0.08 mol (15% by mass), and the details of this total content were that the citric acid content was 0.07 mol (14% by mass) and the lactic acid content was 0.010 mol (1% by mass). Then, the remainder was water.

[0265] (Example 8)

[0266] Example 8 was obtained by adding 75 g of citric acid and 5 g of tartaric acid to the mixed solution obtained by the same production method as in Example 7 and stirring for 10 minutes to obtain the metal carbide intermediate dispersion of Example 8.

[0267] The content in terms of Nb in the obtained metal carbide intermediate dispersion of Example 8 was 0.015 mol (the content in terms of Nb was 3.495 mass%). In addition, the hydrogen peroxide content was 0.009 mol (0.3 mass%), and the ammonia content was 0.2 mol (3.6 mass%). Furthermore, the total content of organic acids (citric acid, tartaric acid) was 0.076 mol (15 mass%), and the details of this total content were that the citric acid content was 0.07 mol (14 mass%) and the tartaric acid content was 0.006 mol (1 mass%). Then, the remainder was water.

[0268] (Example 9)

[0269] 100 g of tantalum hydroxide, 100 g of niobium hydroxide, and 100 g of 25 mass% ammonia water were stirred and mixed for 10 minutes to obtain a first mixed solution. Thereafter, 235 g of 35 mass% hydrogen peroxide water was added to the first mixed solution and stirred for 10 minutes to obtain a second mixed solution. Then, 79 g of citric acid was added to the second mixed solution and stirred for 10 minutes to obtain the metal carbide intermediate dispersion of Example 9.

[0270] The total content in terms of Nb and in terms of Ta in the obtained metal carbide intermediate dispersion of Example 9 was 0.025 mol (the total content in terms of Nb and in terms of Ta was 7.590 mass%), and the details of this total content were that the content in terms of Nb was 0.015 mol (the content in terms of Nb was 3.495 mass%) and the content in terms of Ta was 0.010 mol (the content in terms of Ta was 4.095 mass%). In addition, the hydrogen peroxide content was 0.009 mol (0.3 mass%), and the ammonia content was 0.2 mol (3.6 mass%). Furthermore, the content of the organic acid (citric acid) was 0.07 mol (14 mass%). Then, the remainder was water.

[0271] (Example 10)

[0272] Example 10 was obtained by adding 79 g of citric acid, 5 g of tartaric acid, and 5 g of lactic acid to the second mixed solution obtained by the same production method as in Example 9 and stirring for 10 minutes to obtain the metal carbide intermediate dispersion of Example 10.

[0273] The total content in terms of Nb and in terms of Ta in the obtained metal carbide intermediate dispersion of Example 10 is 0.025 mol (the total content in terms of Nb and in terms of Ta is 7.590% by mass). The details of the total content are that the content in terms of Nb is 0.015 mol (the content in terms of Nb is 3.495% by mass), and the content in terms of Ta is 0.010 mol (the content in terms of Ta is 4.05% by mass). In addition, the hydrogen peroxide content is 0.009 mol (0.3% by mass), and the ammonia content is 0.2 mol (3.6% by mass). Furthermore, the total content of organic acids (citric acid, lactic acid, tartaric acid) is 0.086 mol (16% by mass). The details of the total content are that the citric acid content is 0.07 mol (14% by mass), the lactic acid content is 0.010 mol (1% by mass), and the tartaric acid content is 0.006 mol (1% by mass). Then, the remaining part is water.

[0274] (Comparative Example 8)

[0275] Dissolve 50 g of tantalum pentachloride in a small amount of methanol, add water, and then add 25% by mass ammonia water to obtain a precipitate of tantalum hydrate Ta2O5·nH2O. After washing the precipitate with water to remove chloride ions, add 12.57 g of citric acid and 46 g of 25% by mass ammonia water and mix them. Then, add 109 g of 35% by mass hydrogen peroxide solution and stir for 10 minutes to obtain the metal carbide intermediate dispersion of Comparative Example 8. It should be noted that the metal carbide intermediate dispersion of Comparative Example 8 is the same dispersion as the peroxy complex dispersion of Comparative Example 4.

[0276] The content in terms of Ta in the obtained metal carbide intermediate dispersion of Comparative Example 8 is 0.009 mol (the content in terms of Ta is 3.276% by mass). In addition, the hydrogen peroxide content is 0.009 mol (0.3% by mass). Furthermore, the content of organic acid (citric acid) is 0.07 mol (14% by mass). Then, the remaining part is water.

[0277] (Comparative Example 9)

[0278] In Comparative Example 9, 37.4 g of lactic acid was used instead of citric acid in Comparative Example 8, and the same manufacturing method as in Comparative Example 8 was carried out to obtain the metal carbide intermediate dispersion of Comparative Example 9. It should be noted that the metal carbide intermediate dispersion of Comparative Example 9 is the same dispersion as the peroxy complex dispersion of Comparative Example 5.

[0279] The content in terms of Ta in the obtained metal carbide intermediate dispersion of Comparative Example 9 was 0.009 mol (the content in terms of Ta was 0.164% by mass). In addition, the hydrogen peroxide content was 0.009 mol (0.3% by mass). Furthermore, the content of the organic acid (lactic acid) was 0.2 mol (15% by mass). Then, the remainder was water.

[0280] (Comparative Example 10)

[0281] In Comparative Example 10, 92.3 g of tartaric acid was used instead of citric acid in Comparative Example 8, and otherwise, the same production method as in Comparative Example 8 was carried out to obtain the metal carbide intermediate dispersion of Comparative Example 10. It should be noted that the metal carbide intermediate dispersion of Comparative Example 10 was the same dispersion as the peroxy complex dispersion of Comparative Example 6.

[0282] The content in terms of Ta in the obtained metal carbide intermediate dispersion of Comparative Example 10 was 0.001 mol (the content in terms of Ta was 0.082% by mass). In addition, the hydrogen peroxide content was 0.009 mol (0.3% by mass). Furthermore, the content of the organic acid (tartaric acid) was 0.1 mol (15% by mass). Then, the remainder was water.

[0283] Then, the following physical property values were measured for the metal carbides of Examples 1 and 2 and Comparative Examples 1 to 3. The measured physical property values and the measurement methods of the physical property values are shown below, and the measurement results are shown in Table 1. It should be noted that as a result of XRD measurement, the fired powders of Comparative Examples 4 to 7 were not carbides, so the following physical property values were not measured.

[0284] <Elemental analysis>

[0285] As needed, the sample was appropriately diluted with hydrofluoric acid and nitric acid, and the Ta mass fraction in terms of Ta and the Nb mass fraction in terms of Nb were measured by ICP emission analysis (manufactured by Agilent Technologies: AG-5110).

[0286] <Specific surface area>

[0287] For each sample of the powdery metal carbides of Examples 1 and 2 and Comparative Examples 1 to 3, the specific surface area was measured by the BET method in accordance with JIS Z8830 using a fully automatic specific surface area measuring device (Macsorb HM-1230 type).

[0288] <Primary particle size>

[0289] For each sample of the powdery metal carbides of Examples 1 and 2 and Comparative Examples 1 to 3, the above specific surface area and the carbide density (for example, the density of tantalum carbide was 13.9 [g / cm3 , the density of niobium carbide is 8.57 [g / cm 3 ) Substitute the above into formula (1) to calculate the primary particle size.

[0290] <Roundness>

[0291] For each sample of the powdery metal carbide of Example 1, 2 and Comparative Examples 1 to 3, using a scanning electron microscope (SEM) (manufactured by Hitachi High-Technologies Corporation: S-4800), measure the SEM image of the primary particles at a magnification of 10,000 times or more and 100,000 times or less that can measure these primary particles. Furthermore, using ImageJ of image analysis software, measure the "major axis" and "minor axis" of 20 randomly selected particles. Calculate the roundness from the measured "major axis" and "minor axis", and take the arithmetic mean of the roundness of multiple particles as the "roundness".

[0292] <Chlorine content measurement>

[0293] Collect an appropriate amount of the powdery metal carbide of Example 1, 2 and Comparative Examples 1 to 3 on a ceramic plate, and heat the sample under the conditions of argon (Ar) atmosphere, 1000 °C, and 10 minutes by a combustion ion chromatograph (manufactured by Nittoseiko Analytech Co., Ltd.: AQF-2100H), and measure the amount of chlorine generated, thereby obtaining the chlorine content in each metal carbide powder.

[0294] <Nitrogen content measurement>

[0295] Seal an appropriate amount of the powdery metal carbide of Example 1, 2 and Comparative Examples 1 to 3 in a Ni capsule, and use an oxygen and nitrogen analyzer (manufactured by LECO Corporation: ON836) to obtain the nitrogen content in each metal carbide powder by the thermal conductivity method.

[0296] <Flowability test 1>

[0297] Put 10 g of the powder sample of the powdery metal carbide of Example 1, 2 and Comparative Examples 1 to 3 into an A.B.D powder property measuring instrument manufactured by Tsutsui Rika Kikai Co., Ltd. equipped with a filter with a pore size of 850 μm, vibrate the filter for 1 minute, and recover the powder sample passing through the filter. Then, measure the recovery amount of the powder sample, and calculate the recovery rate from the recovery rate = recovery amount (g) / 10 g × 100. It should be noted that the supply adjustment dial for adjusting the vibration of the filter is set to "8" for this operation.

[0298] <Flowability test 2>

[0299] Change the pore diameter of the filter of the A.B.D powder property measuring instrument manufactured by Tsutsui Rikagaku Kikai Co., Ltd. to 1000 μm, and perform measurement in the same manner as in Fluidity Test 1 to calculate the recovery rate.

[0300] <Mixing property evaluation>

[0301] For the mixed samples (10 g in total) of the powdered metal carbide and tungsten carbide (manufactured by Nippon Shinku Metal Co., Ltd., particle size 0.8 μm) of Examples 1 and 2 and Comparative Examples 1 to 3, which are weighed so that the molar ratio of the two is 1:1, put them into a 100-ml wide-mouth PP bottle, and stir and mix for 1 minute using a paint shaker (frequency: 50 Hz). Then, using a spatula, take 5-point samples of the stirred and mixed sample and analyze the Ta or Nb mass fraction of each sample. When the difference between the maximum and minimum values of the Ta or Nb analysis values at 5 points after stirring and mixing for 1 minute is 0.5 mass% or less, it is regarded as having excellent mixing property and evaluated as "○", and when the difference between the maximum and minimum values of the Ta or Nb analysis values at 5 points after stirring and mixing for 1 minute is greater than 0.5 mass%, it is regarded as having poor mixing property and evaluated as "×".

[0302] In addition, for the metal carbide intermediate dispersions of Examples 3 to 10 and Comparative Examples 8 to 10, the following physical property values were measured. The measured physical property values and the measurement methods of the physical property values are shown below, and the measurement results are shown in Figure 1 、 Figure 2 。

[0303] <Particle size distribution measurement (dynamic light scattering method)>

[0304] The evaluation of the particle size distribution is carried out by the dynamic light scattering method according to JIS Z 8828:2019 using a Zeta potential / particle size / molecular weight measurement system (manufactured by Otsuka Electronics Co., Ltd.: ELSZ-2000). In addition, in order to remove dust and the like in the metal carbide intermediate dispersions of Examples 3 to 10 and Comparative Examples 8 to 10 to be measured just before measurement, the dispersion is filtered with a filter having a pore diameter of 1 μm. Furthermore, D50 represents the particle size at which 50% is reached in terms of volume fraction. Then, if the measured particle size (D50) is 1 nm or more and 500 nm or less, it is evaluated as "〇〇 (excellent)", if the particle size (D50) is greater than 500 nm and 1000 nm or less, it is evaluated as "〇 (good)", and if the particle size (D50) is greater than 1000 nm, it is evaluated as "× (poor)". Figure 2 "Initial" refers to the metal carbide intermediate dispersions of Examples 3 to 10 and Comparative Examples 8 to 10 just after generation. In addition, Figure 2"2 weeks later" or "3 weeks later" refers to the metal carbide intermediate dispersion after standing for 2 weeks or 3 weeks from the date of generating the metal carbide intermediate dispersions of Examples 3 to 10 and Comparative Examples 8 to 10 in a thermostat set at room temperature of 25°C. It should be noted that since the metal carbide intermediate dispersions of Comparative Examples 8 to 10 are suspension solutions, the particle size (D50) cannot be measured.

[0305] <Transmittance measurement>

[0306] 3 ml of the metal carbide intermediate dispersions of Examples 3 to 10 and Comparative Examples 8 to 10 were placed into a glass cuvette. The transmittance of the metal carbide intermediate dispersions of Examples 3 to 10 and Comparative Examples 8 to 10 in the wavelength range of 350 nm to 750 nm (specifically, the transmittance at wavelengths of 350 nm, 450 nm, 550 nm, 650 nm, and 750 nm) was measured using a spectrophotometer according to the above transmittance measurement conditions. Then, if the measured transmittance is 85% or more and 100% or less, it is evaluated as "〇〇 (excellent)"; if the transmittance is 70% or more and less than 85%, it is evaluated as "〇 (good)"; if the transmittance is less than 70%, it is evaluated as "× (poor)". When the transmittance is greater than 100%, it is regarded as 100%. Figure 2 "Initial" refers to the metal carbide intermediate dispersions of Examples 3 to 10 and Comparative Examples 8 to 10 just after generation. Additionally, Figure 2 "2 weeks later" or "3 weeks later" refers to the metal carbide intermediate dispersion after standing for 2 weeks or 3 weeks from the date of generating the metal carbide intermediate dispersions of Examples 3 to 10 and Comparative Examples 8 to 10 in a thermostat set at room temperature of 25°C. It should be noted that since the metal carbide intermediate dispersions of Comparative Examples 8 to 10 are suspension solutions, the particle size (D50) cannot be measured.

[0307] <pH measurement>

[0308] The electrode of a pH meter (manufactured by HORIBA: glass electrode type hydrogen ion concentration indicator D-51) (manufactured by HORIBA: standard ToupH electrode 9615S-10D) was immersed in the metal carbide intermediate dispersions of Examples 3 to 10 and Comparative Examples 8 to 10. After confirming that the liquid temperature was stable at 25°C, the pH was measured. Figure 2 "Initial" refers to the metal carbide intermediate dispersions of Examples 3 to 10 and Comparative Examples 8 to 10 just after generation. Additionally, Figure 2 "2 weeks later" or "3 weeks later" refers to the metal carbide intermediate dispersion after standing for 2 weeks or 3 weeks from the date of generating the metal carbide intermediate dispersions of Examples 3 to 10 and Comparative Examples 8 to 10 in a thermostat set at room temperature of 25°C.

[0309] [Table 1]

[0310]

[0311] As shown in Table 1, the specific surface area of the metal carbides of Examples 1 and 2 obtained by the BET method is 1 m 2 / g or more, and the roundness is 0.78 or more. Therefore, they are extremely fine particles and have high fluidity.

[0312] The primary particle size of the metal carbides of Examples 1 and 2 obtained by the BET method is 0.7 μm or less, and the roundness is 0.78 or more. Therefore, they are extremely fine particles and have high fluidity.

[0313] Regarding the metal carbides of Examples 1 and 2, the chlorine content in the metal carbide powder is 25 ppm or less. Therefore, it does not contain hydrogen peroxide. For example, when the metal carbides of Examples 1 and 2 are coated on the surface of a crucible to form a film, no foaming occurs and it is easy to coat evenly.

[0314] Regarding the metal carbides of Examples 1 and 2, the nitrogen content in the metal carbide powder is 1000 ppm or less. Therefore, it does not contain ammonia components, which is preferable in terms of safety / operation.

[0315] As Figure 1 and Figure 2 shown, regarding the metal carbide intermediate dispersions of Examples 3 to 10, if they have a metal compound, a basic compound, hydrogen peroxide, and an organic acid, and the particle size (D50) of the particles in the metal carbide intermediate dispersion obtained by measuring the particle size distribution using the dynamic light scattering method is 1000 nm or less, it is a dispersion with high dispersibility and no precipitation will occur even after a long time. In addition, since the metal carbide intermediate dispersions of Examples 3 to 10 have a metal compound, a basic compound, hydrogen peroxide, and an organic acid, the maximum value of the light transmittance of the metal carbide intermediate dispersion at wavelengths of 350 nm or more and 750 nm or less is 70% or more. Therefore, the dispersibility is high and the uniformity of the components in the dispersion is excellent.

[0316] The pH of the metal carbide intermediate dispersions of Examples 3 to 10 is 3.0 or more and 10.0 or less. Therefore, the polyacid ions contained in the dispersion are stable.

[0317] Regarding the metal carbide intermediate dispersions of Examples 3 to 10, the molar ratio of the organic acid to the metal compound: Figure 1 as shown, the organic acid / (Nb + Ta) is greater than 0 and less than or equal to 500, and the molar ratio of hydrogen peroxide to the metal compound: Figure 1 as shown, the hydrogen peroxide / (Nb + Ta) is greater than 0 and less than or equal to 10, and the molar ratio of the basic compound to the metal compound:Figure 1 The ammonia / (Nb + Ta) shown is greater than 0 and less than or equal to 100, and thus has excellent stability and dispersibility.

[0318] Regarding the metal carbide intermediate dispersions of Examples 3 to 10, the tantalum content in terms of Ta in the metal carbide intermediate dispersion is 0.4% by mass or more, or the niobium content in terms of Nb is 0.35% by mass or more, and thus it is preferable from the viewpoint of increasing the film thickness of the metal carbide film during film formation.

[0319] In addition, the metal carbide intermediate dispersions of Examples 3 to 10 are fired to obtain metal carbide powders that are extremely fine particles and have high fluidity.

[0320] Furthermore, the metal carbide intermediate dispersions of Examples 3 to 10 are coated on a substrate and fired to obtain a metal carbide film.

[0321] The invention disclosed in this specification, in addition to the configurations of each invention and embodiment, also includes, within the applicable range: those obtained by changing the above-mentioned partial configurations into other configurations disclosed in this specification and specifying them; or those obtained by adding other configurations disclosed in this specification to the above-mentioned configurations and specifying them; or those obtained by deleting the above-mentioned partial configurations within the limit of obtaining partial effects and conceptually generalizing them.

[0322] Industrial Applicability

[0323] The metal carbide of the present invention is extremely fine particles and has high fluidity, and thus is preferably used as an additive for the raw material of a superhard tool. Specifically, the metal carbide of the present invention does not require an excessive mixing step with the raw material of the superhard tool, and in addition, does not require long-time heating during firing, and thus can reduce the energy cost. In addition, it is possible to suppress the occurrence rate of defective products in which a homogeneous superhard tool cannot be formed due to poor miscibility with the raw material of the superhard tool, and thus it is possible to reduce waste and also reduce the energy cost in the treatment of waste. Through the above aspects, it is possible to achieve the sustainable management and efficient advantages of natural resources, as well as decarbonization (carbon neutrality).

Claims

1. A method for manufacturing a powdered metal carbide, characterized in that, It is a method for manufacturing a metal carbide in powder form using a complex polymerization method, which has the following steps: Complexation step: A metal hydroxide is mixed with a basic compound to form a first mixed solution, hydrogen peroxide is added to the first mixed solution to form a second mixed solution, and then an organic acid is added to the second mixed solution to form a metal carbide precursor; Carbide formation step: The metal carbide precursor is fired to form a metal carbide; and Pulverization step: The metal carbide is pulverized to form metal carbide powder.

2. A method for manufacturing a film-shaped metal carbide, characterized in that, It is a method for manufacturing a metal carbide in film form using a complex polymerization method, which has the following steps: Complexation step: A metal hydroxide is mixed with a basic compound to form a first mixed solution, hydrogen peroxide is added to the first mixed solution to form a second mixed solution, and then an organic acid is added to the second mixed solution to form a metal carbide precursor; Dissolution step: A metal carbide intermediate in which the metal carbide precursor is dispersed in pure water is formed; and Carbide formation step: The metal carbide intermediate is coated on a substrate and fired to form a metal carbide film containing a metal carbide on the substrate.

3. The manufacturing method of the metal carbide according to claim 1 or 2, characterized in that, It has a drying step: The metal carbide precursor generated by the complexation step is dried.

4. The manufacturing method of the metal carbide according to claim 3, characterized in that, It has a pulverization step: The metal carbide precursor dried by the drying step is pulverized.

5. The manufacturing method of the metal carbide according to claim 1 or 2, characterized in that, The metal hydroxide is tantalum hydroxide or niobium hydroxide.

6. A method for manufacturing a metal carbide precursor, characterized in that, It is a method for manufacturing a metal carbide precursor for generating a metal carbide using a complex polymerization method, which has the following steps: A metal hydroxide is mixed with a basic compound to form a first mixed solution, hydrogen peroxide is added to the first mixed solution to form a second mixed solution, and then an organic acid is added to the second mixed solution to form the metal carbide precursor.

7. The manufacturing method of the metal carbide precursor according to claim 6, characterized in that, It has a drying step: The metal carbide precursor generated by the complexation step is dried.

8. The manufacturing method of the metal carbide precursor according to claim 6, characterized in that, The metal hydroxide is tantalum hydroxide or niobium hydroxide.

9. A method for manufacturing a metal carbide intermediate, characterized in that, It is a method for manufacturing a metal carbide intermediate for generating a metal carbide using a complex polymerization method, which has the following steps: Complexation step: A metal hydroxide is mixed with a basic compound to form a first mixed solution, hydrogen peroxide is added to the first mixed solution to form a second mixed solution, and then an organic acid is added to the second mixed solution to form the metal carbide precursor; and Dissolution step: A metal carbide intermediate in which the metal carbide precursor is dispersed in pure water is formed.

10. The manufacturing method of the metal carbide intermediate according to claim 9, characterized in that, It has a drying step: The metal carbide precursor generated by the complexation step is dried.

11. The manufacturing method of the metal carbide intermediate according to claim 10, wherein It has a pulverization step: The metal carbide precursor dried by the drying step is pulverized.

12. The manufacturing method of the metal carbide intermediate according to claim 9, characterized in that, The metal hydroxide is tantalum hydroxide or niobium hydroxide.

13. A metal carbide powder, characterized in that, Its specific surface area obtained by the BET method is 1 m 2 / g or more, and the roundness is 0.78 or more.

14. A metal carbide powder, characterized in that, Its primary particle size obtained by the BET method is 0.7 μm or less, and its roundness is 0.78 or more.

15. The metal carbide powder according to claim 13 or 14, characterized in that, The metal carbide powder contains niobium carbide or tantalum carbide.

16. The metal carbide powder according to claim 13 or 14, characterized in that, The chlorine content in the metal carbide powder is 25 ppm or less.

17. The metal carbide powder according to claim 13 or 14, characterized in that, The nitrogen content in the metal carbide powder is 1000 ppm or less.

18. A superhard tool, characterized in that, It contains the metal carbide powder described in claim 13 or 14.

19. A metal carbide intermediate dispersion, characterized in that, It has a metal compound, an alkaline compound, hydrogen peroxide and an organic acid. The particle size (D50) of the particles in the metal carbide intermediate dispersion obtained by measuring the particle size distribution using the dynamic light scattering method is 1000 nm or less.

20. A metal carbide intermediate dispersion, characterized in that, It has a metal compound, an alkaline compound, hydrogen peroxide and an organic acid, and the maximum value of the light transmittance of the metal carbide intermediate dispersion at a wavelength of 350 nm or more and 750 nm or less is 70% or more.

21. The metal carbide intermediate dispersion according to claim 19 or 20, characterized in that, The metal compound is a metal hydroxide.

22. The metal carbide intermediate dispersion liquid according to claim 19 or 20, characterized in that, The organic acid is citric acid, tartaric acid or lactic acid.

23. The metal carbide intermediate dispersion according to claim 21, wherein The metal hydroxide is tantalum hydroxide and / or niobium hydroxide.

24. The metal carbide intermediate dispersion according to claim 19 or 20, having a pH of 3.0 or more and 10.0 or less.

25. The metal carbide intermediate dispersion according to claim 19 or 20, characterized in that, The molar ratio of the organic acid to the metal compound is greater than 0 and less than or equal to 500, the molar ratio of the hydrogen peroxide to the metal compound is greater than 0 and less than or equal to 10, and the molar ratio of the alkaline compound to the metal compound is greater than 0 and less than or equal to 100.

26. The metal carbide intermediate dispersion liquid according to claim 19 or 20, characterized in that, The solvent of the metal carbide intermediate dispersion is water.

27. The metal carbide intermediate dispersion according to claim 19 or 20, characterized in that, The tantalum content in terms of Ta in the metal carbide intermediate dispersion is 0.4% by mass or more, or the niobium content in terms of Nb is 0.35% by mass or more.

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