Method for manufacturing film-coated structure and film-coated structure

Abstract

To provide a method for manufacturing a film-coated structure and a film-coated structure, regardless of size and shape of a substrate.SOLUTION: A method for manufacturing a film-coated structure having a metal-carbon composite film on a carbon substrate includes: an applying step of applying a metal compound-containing material onto the carbon substrate; and a heating step of forming the metal-carbon composite film on the carbon substrate by heating the carbon substrate on which the material has been applied. In the film-coated structure of the present invention in which the metal-carbon composite film is formed on the carbon substrate, the metal-carbon composite film is formed by heating the metal compound-containing material applied onto the carbon substrate.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a coated structure and a coated structure. [Background technology]

[0002] For components that require heat resistance or reactivity resistance (for example, oxidation resistance or chemical resistance), the heat resistance or reactivity resistance can be improved and the lifespan of the component can be extended by forming a protective film of a metal compound or the like on the surface of the substrate.

[0003] For example, when forming a tantalum carbide layer as a protective film on the surface of a carbon substrate, a CVD apparatus is generally used, as disclosed in Patent Document 1. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2004 / 009515 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the size and shape of the substrate on which a protective film can be formed is predetermined for each CVD device, and depending on the size and shape of the substrate, it was not possible to form a protective film on the surface.In addition, the process of forming a protective film on the surface of a substrate using a CVD device took a considerable amount of time.

[0006] In view of the above problems, the present invention provides a method for producing a coated structure and a coated structure that can be produced regardless of the size and shape of the substrate. [Means for solving the problem]

[0007] The method for producing a coated structure of the present invention, which has been made to solve the above-mentioned problems, is a method for producing a coated structure having a metal-carbon composite coating on a carbon substrate, and is characterized by comprising: a coating step of coating the carbon substrate with a metal compound-containing material; and a heating step of heating the coated carbon substrate to form a metal-carbon composite coating on the carbon substrate. In the present specification, the term "metal-carbon composite coating" refers to a coating in which a metal element and a carbon element are bonded together, such as a metal carbide alone or a carbon-containing material containing a metal carbide. The coating may also include a coating in which a metal compound other than a metal carbide is dispersed in a carbon-containing material, i.e., a coating in which the metal element and the carbon element are not bonded together but are mixed or dispersed together. Examples of metal compounds other than metal carbides include metal oxides, metal nitrides, metal sulfides, and metal hydroxides.

[0008] Here, the coated structure produced by the method for producing a coated structure of the present invention has a metal-carbon composite coating on a carbon substrate. For example, the coated structure may have a metal-carbon composite coating on at least one side (e.g., the surface) of the carbon substrate, or may have a metal-carbon composite coating on the entire peripheral surface of the carbon substrate, and further includes a carbon substrate having a metal-carbon composite coating on only a portion of one side of the carbon substrate.

[0009] First, in the coating step according to the method for producing a coated structure of the present invention, a material containing a metal compound is coated onto a carbon substrate.

[0010] The carbon substrate used in the method for producing a coated structure of the present invention may be a substrate made of carbon only, a substrate containing carbon as the main component with a carbon content of 50% by mass or more, or a substrate with a multilayer structure in which the outermost layer is made of carbon only or contains carbon as the main component with a carbon content of 50% by mass or more. It is particularly preferable that the carbon substrate is a substrate made of carbon only.

[0011] The size and shape of the carbon substrate are not particularly limited as long as they can be heated in a static furnace used in the heating step described below. Specific examples of the carbon substrate include crucibles, furnace materials, electrodes, fibers, filtration devices, filters, protective tubes, heater tubes, burner nozzles, and fire-resistant jigs.

[0012] Examples of the carbon material of the carbon substrate include fullerene, carbon nanotube, carbon nanofiber, graphene, graphene oxide, carbon nanohorn, diamond, hyperdiamond, and carbon fiber.

[0013] The carbon material may be composed of only carbon or other materials containing carbon. Furthermore, the structure of the carbon material may be a uniform structure or a non-uniform structure. The uniform structure may be hollow or porous. The non-uniform structure may be, for example, an island-in-the-sea structure, a multi-layer structure, a hollow structure, or a porous structure.

[0014] Furthermore, the carbon material may be in the form of a powder, a plate, a film, a fiber, or the like, and may be in the form of a molded product thereof, i.e., a mixture, a multilayer body, a pressed powder body, a sintered body, a fiber bundle, a nonwoven body, or a woven material (plain weave, twill weave, satin weave, basket weave).

[0015] The carbon material is particularly preferably a fibrous material, and specific examples include metal fibers (steel fibers, etc.), ceramic fibers (metal oxide fibers, metal carbide fibers, metal nitride fibers, silicon carbide fibers, glass fibers, etc.), and polymer fibers (natural polymer fibers, polysaccharide fibers, cellulose fibers, artificial polymer fibers, resin fibers, carbon fibers, etc.).

[0016] The metal compound-containing material used in the method for producing a coated structure of the present invention is characterized by containing a compound of at least one metal element selected from Ti, Nb, Mo, Hf, Ta, W, Zr, and Si. Examples of the metal compound-containing material include those containing a compound of at least one metal element selected from Ti, Nb, Mo, Hf, Ta, W, Zr, and Si. Specific examples include peroxo complex metal compounds containing at least one metal element selected from Ti, Nb, Mo, Hf, Ta, W, Zr, and Si (e.g., peroxohydroxy acid complex metal compounds, peroxocitrate complex metal compounds, and peroxoammonium complex metal compounds), metal hydroxides, hydroxy acid complex metal compounds (e.g., ammonium oxalate complex metal compounds), and polyacids, but are not limited to these compounds. Furthermore, the metal compound-containing material may contain a metal element, a metalloid element, or a nonmetal element other than at least one metal element selected from Ti, Nb, Mo, Hf, Ta, W, Zr, and Si. Examples include B and P.

[0017] When the metal compound-containing material is a peroxo complex metal compound, even if the substrate does not contain carbon, by heating the substrate coated with the peroxo complex metal compound, the metal element contained in the peroxo complex metal compound reacts with carbon to form a metal carbide. Similarly, when the metal compound-containing material is a hydroxy acid complex metal compound, the metal element contained in the hydroxy acid complex metal compound reacts with carbon to form a metal carbide.

[0018] The content of the metal compound-containing material is preferably adjusted depending on the metal element and the type of carbon substrate, and is more preferably more than 0% by mass and not more than 40% by mass, even more preferably 0.1% by mass to 30% by mass, particularly preferably 0.2% by mass to 30% by mass, and particularly preferably 0.3% by mass to 15% by mass. When the metal compound-containing material contains multiple metal elements selected from Ti, Nb, Mo, Hf, Ta, W, Zr, and Si, the total value of the mass fractions of the metal elements is preferably within the above-mentioned range.

[0019] Here, the content of the metal compound-containing material may be calculated by diluting the metal compound-containing material appropriately with dilute hydrochloric acid as necessary, and measuring the mass fraction in terms of metal using ICP optical emission spectrometry (AG-5110 manufactured by Agilent Technologies) in accordance with JIS K0116:2014.

[0020] The method for producing a coated structure of the present invention is characterized in that the content of a compound of at least one metal element selected from Ti, Nb, Mo, Hf, Ta, W, Zr, and Si in the metal compound-containing material used is more than 0 mass% and 35 mass% or less, calculated as metal. The content of at least one metal element compound selected from Ti, Nb, Mo, Hf, Ta, W, Zr, and Si in the metal compound-containing material is preferably adjusted depending on the metal element and the type of carbon-based substrate. It is more preferably more than 0% by mass and less than 35% by mass, even more preferably 0.03% by mass to 25% by mass, particularly preferably 0.06% by mass to 25% by mass, and particularly preferably 0.1% by mass to 15% by mass. When the metal compound-containing material contains multiple metal elements selected from Ti, Nb, Mo, Hf, Ta, W, Zr, and Si, the total mass fraction of each metal element is preferably within the above-mentioned range. In this specification, "metal equivalent" refers to Ti equivalent, Nb equivalent, Mo equivalent, Hf equivalent, Ta equivalent, W equivalent, Zr equivalent, and Si equivalent. The metal compound-containing material may also contain metal elements, semimetal elements, or nonmetal elements other than at least one metal element selected from Ti, Nb, Mo, Hf, Ta, W, Zr, and Si, such as B and P.

[0021] The metal compound-containing material used in the method for producing a coated structure of the present invention is characterized by containing a Ta compound. The metal compound-containing material preferably contains a Ta compound, since it reacts with the carbon contained on the carbon substrate and facilitates the carbonization reaction.Specific examples of the Ta compound include tantalum peroxocitrate compounds, tantalum hydroxide, and polyoxotantalate.

[0022] When the metal compound-containing material is a tantalum peroxocitrate compound, even if the substrate does not contain carbon, by heating the substrate to which the tantalum peroxocitrate compound has been applied, the tantalum contained in the tantalum peroxocitrate compound reacts with carbon to form tantalum carbide.

[0023] Furthermore, when the metal compound-containing material is a tantalum hydroxide, the tantalum concentration in the metal compound-containing material may 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, or 5% by mass or more and 10% by mass or less.

[0024] Here, when the metal compound-containing material is tantalum hydroxide, the tantalum content in the metal compound-containing material is calculated by appropriately diluting the metal compound-containing material with dilute hydrochloric acid as needed, and measuring the tantalum mass fraction in tantalum equivalent using ICP optical emission spectrometry (manufactured by Agilent Technologies: AG-5110) in accordance with JIS K0116:2014.

[0025] The metal compound-containing material used in the method for producing a coated structure of the present invention may also contain a resin. If the metal compound-containing material contains a resin, it is preferable in that the resin is uniformly compatible with the metal compound and acts to adhere to the carbon substrate, thereby improving film-forming properties and adhesion to the carbon substrate.

[0026] Examples of the resin contained in the metal compound-containing material include polyolefin compounds and polyvinyl compounds.

[0027] Furthermore, the metal compound-containing material used in the method for producing a coated structure of the present invention may have a resin content of 0.1% by mass or more and 60% by mass or less when the metal compound-containing material is taken as 100% by mass. The resin content in the metal compound-containing material of the present invention is preferably 0.1% by mass or more and 60% by mass or less, since it can prevent fine metal compounds from aggregating after drying and improve the wettability of the metal compound-containing material to the carbon substrate. The resin content may be 0.15% by mass or more and 40% by mass or less, 0.2% by mass or more and 30% by mass or less, or 0.25% by mass or more and 20% by mass or less.

[0028] Furthermore, the metal compound-containing material used in the method for producing a coated structure of the present invention may contain, as a surfactant, at least one surfactant selected from the group consisting of nonionic surfactants, cationic surfactants, and anionic surfactants. Examples of surfactants include olefin resins having an amine group, carboxyl group, hydroxyl group, phosphoric acid, sulfonic acid group or unsaturated fatty acid as a functional group on the side chain, acetylene glycol compounds, polyoxyalkylene, polyoxyethylene, polyoxypropylene, etc.

[0029] Furthermore, the metal compound-containing material used in the method for producing a coated structure of the present invention may have a surfactant content of 0.001% by mass or more and 10% by mass or less when the metal compound-containing material is taken as 100% by mass. The resin content in the metal compound-containing material of the present invention is preferably 0.001% by mass or more and 10% by mass or less, since it can improve the wettability of the metal compound-containing material to the substrate. The resin content may be 0.01% by mass or more and 5% by mass or less, 0.05% by mass or more and 3% by mass or less, or 0.1% by mass or more and 1% by mass or less.

[0030] The metal compound-containing material used in the method for producing a coated structure of the present invention may also contain a carbon material. If the metal compound-containing material contains a carbon material, the carbon material becomes a carbonized component during carbonization, which is preferable in that carbonization is improved.

[0031] Furthermore, the metal compound-containing material used in the method for producing a coated structure of the present invention may be a solution, sol, or gel. The metal compound-containing material contains a metal compound, and more specifically, it may be liquefied by applying shear stress. That is, the metal compound-containing material may be in a liquid, sol, gel, or semi-solid state under normal conditions, and may be applied to a carbon substrate. Furthermore, the gel may have a viscosity of 200 mPa·s or more at 25°C as measured by a rotating cylinder method.

[0032] In addition, the metal compound-containing material used in the method for producing a coated structure of the present invention is preferably a solution, which can be easily applied to a carbon substrate. Furthermore, the metal compound-containing material used in the method for producing a coated structure of the present invention is preferably one that contains water as a solvent, from the viewpoint of reducing the environmental load.

[0033] The metal compound-containing material used in the method for producing a coated structure of the present invention is characterized in that the maximum light transmittance in the wavelength range of 500 nm to 700 nm is 70%T or more. The metal compound-containing material used in the method for producing a coated structure of the present invention preferably has a maximum light transmittance of 70%T or more in the wavelength region of 500 nm to 700 nm, resulting in high dispersibility and excellent uniformity of the liquid components. The maximum light transmittance in the wavelength region of 500 nm to 700 nm is more preferably 72%T or more, even more preferably 74%T or more, particularly preferably 76%T or more, even particularly preferably 78%T or more, and even particularly preferably 80%T or more. The light transmittance in the wavelength region of 500 nm to 700 nm may be 80%T. Note that, due to measurement error or the like, the measured light transmittance may exceed 100%T. However, since the theoretical upper limit is 100%T, if the measured value exceeds 100%T, it is considered to be 100%T.

[0034] Here, the light transmittance in the wavelength region of 500 nm to 700 nm is measured using a spectrophotometer under the following light transmittance measurement conditions for the metal compound-containing material used in the method for producing a coated structure of the present invention.

[0035] =Light transmittance measurement conditions= Measurement equipment: UV-Vis-NIR spectrophotometer UH4150 (Hitachi High-Tech Science Corporation) Measurement mode: Wavelength scan Data mode: %T (transparent) Measurement wavelength range: 200nm to 2000nm Scan speed: 600nm / min Sampling interval: 2nm

[0036] On the other hand, when the metal compound-containing material used in the method for producing a coated structure of the present invention contains a Si compound, the light transmittance in the wavelength region of 500 nm to 700 nm can be determined by placing 3 g of the metal compound-containing material containing a Si compound adjusted to room temperature (25°C) in a measurement cell (light path length 1 cm) and measuring the ultraviolet-visible absorption spectrum (UV-Vis absorption spectrum) in accordance with JIS K 0115, 2004 "General rules for absorptiometric analysis methods" under the following light transmittance measurement conditions (including Si).

[0037] =Light transmittance measurement conditions (including Si)= Measurement equipment: U-2900 spectrophotometer (Hitachi High-Tech Corporation) Measurement mode: Wavelength scan Data mode: %T (transparent) Measurement wavelength range: 200nm to 1000nm Scan speed: 200nm / min Sampling interval: 1nm Cell length: 10mm Measurement cell: Disposable square cell for particle size (manufactured by Otsuka Electronics Co., Ltd.)

[0038] The metal compound-containing material used in the method for producing a coated structure of the present invention is characterized in that the particle diameter (D50) of the particles in the metal compound-containing material measured by dynamic light scattering is 3000 nm or less. The particle diameter (D50) of the particles in the metal compound-containing material used in the method for producing a coated structure of the present invention is preferably 3000 nm or less from the viewpoint of stability over time, more preferably 2000 nm or less, and may be 1000 nm or less, 500 nm or less, 400 nm or less, 300 nm or less, 100 nm or less, 50 nm or less, 30 nm or less, 20 nm or less, 10 nm or less, 5 nm or less, 3 nm or less, or 2 nm or less. On the other hand, the particle diameter (D50) is preferably 0.1 nm or more, more preferably 0.5 nm or more, even more preferably 0.7 nm or more, and particularly preferably 1 nm or more. Typically, the particle diameter (D50) is 0.6 nm or more and 200 nm or less.

[0039] Dynamic light scattering is a method for measuring the light scattering intensity from particles undergoing Brownian motion by irradiating a solution such as a suspension with light such as a laser beam. The particle size and distribution are then determined from the temporal fluctuations of this intensity. Specifically, particle size distribution was evaluated using a zeta potential, particle size, and molecular weight measurement system (Otsuka Electronics Co., Ltd.: ELSZ-2000ZS) in accordance with JIS Z 8828:2019 "Particle Size Analysis - Dynamic Light Scattering." If necessary, the sample was diluted 1000 times with pure water. Just before measurement, the sample was filtered through an 11 μm pore filter and ultrasonicated for 3 minutes in an ultrasonic cleaner (AS ONE Corporation: VS-100III) to remove dust and other particles. The liquid temperature of the sample was adjusted to 25°C. The particle size (D50) is the median diameter (D50), which is the particle size at 50% of the cumulative distribution curve.

[0040] The metal compound-containing material used in the method for producing a coated structure of the present invention is characterized by having a pH of 6.5 or more and 13.5 or less. The pH of the metal compound-containing material used in the method for producing a coated structure of the present invention is preferably 6.5 or higher, as this provides good solubility. The pH of the metal compound-containing material is more preferably 7.0 or higher, even more preferably 7.5 or higher, and particularly preferably 8.0 or higher. The pH of the metal compound-containing material may be 8.5 or higher, 9.0 or higher, 9.5 or higher, 10.0 or higher, 10.5 or higher, or 11.0 or higher. On the other hand, the pH of the metal compound-containing material is preferably 13.5 or lower, more preferably 13.0 or lower, and even more preferably 12.5 or lower.

[0041] Here, the pH of the metal compound-containing material used in the method for producing a coated structure of the present invention is measured by immersing an electrode (HORIBA: Standard ToupH electrode 9615S-10D) of a pH meter (HORIBA: Glass electrode type hydrogen ion concentration indicator D-51) in the metal compound-containing material and confirming that the liquid temperature has stabilized at 25°C.

[0042] In the coating step according to the method for producing a coated structure of the present invention, the metal compound-containing material is coated onto the carbon substrate by the coating method described below.

[0043] Specific examples of the method for applying the metal compound-containing material onto the carbon substrate include spraying, inkjet coating, dispenser coating, nozzle coating, slit coating, die coating, roll coating, spin coating, blade coating, knife coating, wire bar coating, screen printing, and brush coating.

[0044] Next, in the heating step according to the method for producing a coated structure of the present invention, the carbon substrate coated with the metal compound-containing material is heated to form a metal-carbon composite coating on the carbon substrate. By heating the carbon substrate coated with the metal compound-containing material, the metal compound-containing material reacts with the carbon contained in the carbon substrate, i.e., a carbonization reaction occurs, and a metal-carbon composite coating is formed on the carbon substrate.

[0045] Specifically, a carbon substrate coated with a metal compound-containing material is placed in a static furnace and heated in an inert atmosphere, such as an argon or nitrogen atmosphere. The metal element in the metal compound-containing material reacts with the carbon present on the coated surface of the carbon substrate (carbonization reaction) to form a metal carbide, forming a metal-carbon composite coating on the carbon substrate. The heating step may be performed under reduced pressure or in a vacuum. Preferably, the heating temperature in the heating step is 1000°C or higher and 3500°C or lower, and the heating time is 0.5 hours or higher and 2 hours or lower.

[0046] Furthermore, when the metal compound-containing material is a peroxo complex metal compound, by heating the carbon substrate to which the peroxo complex metal compound has been applied, the metal element contained in the peroxo complex metal compound reacts with carbon to form a metal carbide, and a metal-carbon composite coating can be formed on the carbon substrate.

[0047] The heating temperature in the heating step is preferably 1000°C or higher and 3500°C or lower, since this ensures a reliable reaction between the carbon of the carbon substrate and the metal compound. The heating temperature in the heating step is more preferably 1400°C or higher and 2000°C or lower, even more preferably 1500°C or higher and 1900°C or lower, and particularly preferably 1550°C or higher and 1800°C or lower.

[0048] The heating time in the heating step is preferably 0.5 hours or more and 2 hours or less in order to sufficiently synthesize the carbide, more preferably 1 hour or more and 1.5 hours or less, and even more preferably 1.2 hours or more and 1.4 hours or less.

[0049] The method for producing a coated structure of the present invention may further include a drying step between the coating step and the heating step in the method for producing a coated structure of the present invention described above.

[0050] It is preferable to place the carbon substrate coated with the metal compound-containing material in a static furnace and dry it at a drying temperature of 100° C. for 1 hour, since this allows excess impurities such as moisture to be removed.

[0051] The drying temperature in the drying step is more preferably 110°C or higher and 400°C or lower, even more preferably 120°C or higher and 300°C or lower, and particularly preferably 130°C or higher and 200°C or lower.

[0052] The drying time in the drying step is preferably 0.2 hours or more and 3 hours or less, more preferably 0.3 hours or more and 2 hours or less, and even more preferably 0.4 hours or more and 1 hour or less.

[0053] Furthermore, the method for producing a coated structure of the present invention may include a step of cooling the metal-carbon composite coating formed by the heating step. The metal-carbon composite coating formed by the heating step may be cooled to room temperature.

[0054] Specifically, the coated structure having the metal-carbon composite coating formed on the carbon substrate is removed from the static furnace and allowed to cool to room temperature.

[0055] By the method for producing a coated structure of the present invention described above, a coated structure having a metal-carbon composite coating formed on a carbon substrate can be produced.

[0056] The method for producing the coated structure of the present invention is not limited to the above-mentioned production method, but may be the following production method.

[0057] The method for producing a coated structure of the present invention is a method for producing a coated structure having a metal-carbon composite coating on a carbon substrate, and is characterized by comprising an immersion step of immersing the carbon substrate in a metal compound-containing material, and a heating step of heating the immersed carbon substrate to form a metal-carbon composite coating on the carbon substrate. The carbon substrate and metal compound-containing material used in this method for producing a coated structure of the present invention are the same as the carbon substrate and metal compound-containing material used in the method for producing a coated structure of the present invention described above, and therefore detailed description thereof will be omitted.

[0058] First, in the immersion step according to the method for producing a coated structure of the present invention, the carbon substrate is immersed in a material containing a metal compound.

[0059] Specifically, the carbon substrate is immersed in a container filled with the metal compound-containing material, thereby impregnating the carbon substrate with the metal compound-containing material. The immersion time in the immersion step is preferably 0.1 to 1 hour, more preferably 0.2 to 0.9 hours. The immersion step may be performed at room temperature, or may be heated and then cooled to room temperature.

[0060] Furthermore, the immersion step in the method for producing a coated structure of the present invention is preferably carried out under reduced pressure or in vacuum, in that the carbon substrate is immersed in the metal compound-containing material, which makes it easier for the carbon substrate to be impregnated with the metal compound-containing material and enables the immersion time in the immersion step to be shortened.

[0061] Specifically, a container filled with the metal compound-containing material in which the carbon substrate is immersed is placed in a pressure reducing device and placed under reduced pressure or vacuum, which makes it easier for the metal compound-containing material to be impregnated into the carbon substrate.

[0062] The degree of vacuum in the pressure reducing device is preferably 0.05 MPa or less, more preferably 0.04 MPa or less, even more preferably 0.03 MPa or less, and particularly preferably 0.02 MPa or less. The immersion time in the immersion step under reduced pressure or vacuum is preferably 0.1 hour to 0.5 hours, more preferably 0.2 hour to 0.4 hours.

[0063] Furthermore, when a metal-carbon composite coating is formed only on one surface of a carbon substrate, for example, on the surface, only the surface of the carbon substrate is immersed in the metal compound-containing material, whereas when a metal-carbon composite coating is formed on the entire circumferential surface of the carbon substrate, the entire circumferential surface of the carbon substrate is immersed in the metal compound-containing material.

[0064] Next, in the heating step according to the method for producing a coated structure of the present invention, the carbon substrate impregnated with the metal compound-containing material is heated to form a metal-carbon composite coating on the carbon substrate. By heating the carbon substrate impregnated with the metal compound-containing material, the metal element in the metal compound-containing material reacts with the carbon present in the carbon substrate impregnated with the metal compound-containing material (carbonization reaction) to form a metal carbide, and a metal-carbon composite coating is formed on the carbon substrate.

[0065] Here, when the metal compound-containing material is a metal peroxocitrate compound, by heating the carbon substrate impregnated with the metal peroxocitrate compound, the metal element contained in the metal peroxocitrate compound reacts with carbon to form a metal carbide, and a metal-carbon composite coating can be formed on the carbon substrate.

[0066] The heating step in the method for producing a coated structure of the present invention is characterized in that the temperature is 1000° C. or higher and 3500° C. or lower, and the heating time is 0.5 hours or higher and 2 hours or lower.

[0067] The heating temperature in the heating step is preferably 1000°C or higher and 3500°C or lower, since this ensures a reliable reaction between the carbon of the carbon substrate and the metal compound. The heating temperature in the heating step is more preferably 1400°C or higher and 2000°C or lower, even more preferably 1500°C or higher and 1900°C or lower, and particularly preferably 1550°C or higher and 1800°C or lower.

[0068] The heating time in the heating step is preferably 0.5 hours or more and 2 hours or less in order to sufficiently synthesize the carbide, more preferably 1 hour or more and 1.5 hours or less, and even more preferably 1.2 hours or more and 1.4 hours or less.

[0069] The method for producing a coated structure of the present invention may further include a drying step between the immersion step and the heating step in the method for producing a coated structure of the present invention described above.

[0070] It is preferable to place the carbon substrate impregnated with the metal compound-containing material in a static furnace and dry it at a drying temperature of 100° C. for 1 hour, since this makes it possible to remove excess impurities such as moisture.

[0071] The drying temperature in the drying step is more preferably 110°C or higher and 400°C or lower, even more preferably 120°C or higher and 300°C or lower, and particularly preferably 130°C or higher and 200°C or lower.

[0072] The drying time in the drying step is preferably 0.2 hours or more and 3 hours or less, more preferably 0.3 hours or more and 2 hours or less, and even more preferably 0.4 hours or more and 1 hour or less.

[0073] Furthermore, the method for producing a coated structure of the present invention may include a step of cooling the metal-carbon composite coating formed by the heating step. The metal-carbon composite coating formed by the heating step may be cooled to room temperature.

[0074] The metal-carbon composite coating formed on a carbon substrate produced by the above-described method for producing a coated structure of the present invention may be in a state in which a metal element and carbon are present, and preferably the metal element content is more than 0% by mass and not more than 80% by mass, and the carbon content is more than 0% by mass and not more than 50% by mass. The mass fractions of the metal element and carbon in the metal-carbon composite coating can be measured, for example, by semi-quantitative analysis using energy dispersive X-ray analysis (EDX) of the metal-carbon composite coating portion on a cross-sectional sample of the substrate.

[0075] Furthermore, while the metal elements in the metal-carbon composite coating are present in large amounts on the coating surface, the carbon content derived from the carbon substrate increases the closer to the carbon substrate. When a substance containing a metal compound is applied, the metal elements are more likely to be present on the surface of the metal-carbon composite coating. On the other hand, when a substance containing a metal compound is impregnated, the content of the metal elements inside the metal-carbon composite coating is relatively higher than when the substance is applied.

[0076] Furthermore, the metal-carbon composite coating formed on the carbon substrate produced by the method for producing a coated structure of the present invention can be confirmed to be a carbide from the peaks in the X-ray diffraction pattern obtained by X-ray diffraction measurement under the following X-ray diffraction measurement conditions and X-ray diffraction analysis conditions.

[0077] =X-ray diffraction measurement conditions= Equipment: MiniFlex II (Rigaku Corporation) Measurement range (2θ): 5 to 90° Sampling width: 0.02° Scan speed: 2.0° / min ·X-ray: CuKα ray Voltage: 30kV ·Current: 15mA Divergence slit: 1.25° Scattering slit: 1.25° Receiving slit: 0.3 mm

[0078] =X-ray diffraction analysis conditions= Use the Rigaku data analysis software PDXL2. · Smooth the peak with b-spline to clarify the peak top.

[0079] Furthermore, if the thickness of the metal-carbon composite coating formed on the carbon substrate produced by the method for producing a coated structure of the present invention is 300 nm or less, this is preferable because cracks in the film and peeling of the film itself are less likely to occur. The thickness of the metal-carbon composite coating may be 100 nm or less. This is because if cracks occur in the metal-carbon composite coating, the carbon substrate is oxidized and is more likely to be released as carbon dioxide, which makes it easier for the carbon in the carbon substrate to decrease. On the other hand, if the thickness of the metal-carbon composite coating is 1 nm or more, this is preferable because the carbon substrate can be sufficiently protected. The thickness of the metal-carbon composite coating may be 10 nm or more.

[0080] The coated structure of the present invention is a coated structure in which a metal-carbon composite coating is formed on a carbon substrate, and is characterized in that the metal-carbon composite coating is formed by heating the carbon substrate to which a metal compound-containing substance has been applied or impregnated. The coated structure of the present invention has a metal-carbon composite coating formed on a carbon substrate, regardless of the size or shape of the carbon substrate, thereby improving the heat resistance and reactivity resistance and extending the life of the carbon substrate. Furthermore, the coated structure of the present invention has a metal-carbon composite coating with a uniform thickness on the carbon substrate, regardless of the size or shape of the carbon substrate.

[0081] Furthermore, in the coating structure of the present invention, if the thickness of the metal-carbon composite coating formed on the carbon substrate is 300 nm or less, cracks in the coating and peeling of the coating itself are unlikely to occur.

[0082] Furthermore, the metal compound-containing material for a metal-carbon composite coating of the present invention is a metal compound-containing material for a metal-carbon composite coating formed on a carbon substrate, and is characterized in that it reacts with the carbon substrate to form a metal-carbon composite coating. The metal compound-containing material for a metal-carbon composite coating of the present invention is applied to or immersed in a carbon substrate, and by heating the carbon substrate, the metal element in the metal compound-containing material reacts (carbonization reaction) with carbon present on the coating surface of the carbon substrate to which the metal compound-containing material has been applied, thereby forming a metal carbide and a metal-carbon composite coating.

[0083] Forming a metal-carbon composite coating on a carbon substrate can improve corrosion resistance against the following liquids and gases: hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, hydrofluoric acid, sodium chloride, acetic acid, oxalic acid, ammonia water, sodium hydroxide, potassium hydroxide, water vapor, hydrogen sulfide gas, ammonia gas, hydrogen gas, fluorine gas, chlorine gas, nitrogen oxide gas (NOx), and sulfur oxide gas (SOx).

[0084] Furthermore, the metal compound-containing material for use in the metal-carbon composite coating of the present invention may contain a compound of at least one metal element selected from Ti, Nb, Mo, Hf, Ta, W, Zr, and Si. Specific examples include peroxo complex metal compounds (e.g., peroxohydroxy acid complex metal compounds, peroxocitrate complex metal compounds, and peroxoammonium complex metal compounds) containing at least one metal element selected from Ti, Nb, Mo, Hf, Ta, W, Zr, and Si, metal hydroxides, hydroxy acid complex metal compounds (e.g., ammonium oxalate complex metal compounds), and polyacids, but are not limited to these compounds. Furthermore, the metal compound-containing material may contain a metal element, a metalloid element, or a nonmetal element other than at least one metal element selected from Ti, Nb, Mo, Hf, Ta, W, Zr, and Si. Examples include B and P.

[0085] When the metal compound-containing material for the metal-carbon composite coating of the present invention is a peroxo complex metal compound, even if the substrate does not contain carbon, by heating the substrate to which the peroxo complex metal compound is applied, the metal element contained in the peroxo complex metal compound reacts with carbon to form a metal carbide. Similarly, when the metal compound-containing material is a hydroxy acid complex metal compound, the metal element contained in the hydroxy acid complex metal compound reacts with carbon to form a metal carbide.

[0086] Furthermore, the metal compound-containing material for the metal-carbon composite coating of the present invention preferably contains a Ta compound, since it reacts with the carbon contained on the carbon substrate and facilitates the carbonization reaction.Specific examples of the Ta compound include tantalum peroxocitrate compounds, tantalum hydroxide, and polyoxotantalate.

[0087] When the metal compound-containing material for the metal-carbon composite coating of the present invention is a tantalum peroxocitrate compound, even if the substrate does not contain carbon, by heating the substrate to which the tantalum peroxocitrate compound has been applied, the tantalum contained in the tantalum peroxocitrate compound will react with carbon to form tantalum carbide.

[0088] Furthermore, if the metal compound-containing material for a metal-carbon composite coating of the present invention contains a resin, the resin is uniformly miscible with the metal compound and acts to adhere to the carbon substrate, thereby improving film-forming properties and adhesion to the carbon substrate. Specific examples of the resin contained in the metal compound-containing material include polyolefin compounds and polyvinyl compounds.

[0089] Furthermore, the metal compound-containing material for the metal-carbon composite coating of the present invention may be a solution, a sol, or a gel. The metal compound-containing material is a material that contains a metal compound, and more specifically, is a material that can be liquefied by applying shear stress. In other words, the metal compound-containing material may be in a liquid, sol, gel, or semi-solid state under normal conditions, and may be any material that can be applied to a carbon substrate.

[0090] Furthermore, when the metal compound-containing material for a metal-carbon composite coating of the present invention is in the form of a solution, it can be easily applied to a carbon substrate, which is preferable. Furthermore, when the metal compound-containing material for a metal-carbon composite coating of the present invention contains water as a solvent, it is preferable from the viewpoint of reducing the environmental load.

[0091] Furthermore, it is preferable that the metal compound-containing material for a metal-carbon composite coating of the present invention has a maximum light transmittance of 70%T or more in the wavelength region of 500 nm to 700 nm, since this results in high dispersibility and excellent uniformity of the components in the liquid. The maximum light transmittance in the wavelength region of 500 nm to 700 nm is more preferably 72%T or more, even more preferably 74%T or more, particularly preferably 76%T or more, even particularly preferably 78%T or more, and even particularly preferably 80%T or more. The light transmittance in the wavelength region of 500 nm to 700 nm may be 80%T.

[0092] Furthermore, in terms of stability over time, the metal compound-containing material for a metal-carbon composite coating of the present invention preferably has a particle diameter (D50) of 3000 nm or less, more preferably 2000 nm or less, and may even be 1000 nm or less, 500 nm or less, 400 nm or less, or 300 nm or less, as measured by dynamic light scattering. Meanwhile, the particle diameter (D50) is preferably 0.1 nm or more, more preferably 0.5 nm or more, even more preferably 0.7 nm or more, and particularly preferably 1 nm or more. Typically, the particle diameter (D50) is 0.6 nm or more and 200 nm or less.

[0093] Furthermore, the pH of the metal compound-containing material for use in the metal-carbon composite coating of the present invention is preferably 6.5 or higher, as this provides good solubility. The pH of the metal compound-containing material is more preferably 7.0 or higher, even more preferably 7.5 or higher, and particularly preferably 8.0 or higher. The pH of the metal compound-containing material may be 8.5 or higher, 9.0 or higher, 9.5 or higher, 10.0 or higher, 10.5 or higher, or 11.0 or higher. On the other hand, the pH of the metal compound-containing material is preferably 13.5 or lower, more preferably 13.0 or lower, and even more preferably 12.5 or lower.

[0094] Furthermore, the metal compound-containing material for use in a metal-carbon composite coating according to the present invention may contain components other than those derived from the metal compound (referred to as "other components"), provided that the effects of the material are not impaired. Examples of other components include, but are not limited to, Li, Mg, Si, Ca, Ti, Mn, Ni, Cu, Zn, Sr, Zr, Mo, Ba, W, Bi, and B. The content of other components in the metal compound-containing material is preferably less than 5% by mass, more preferably less than 4% by mass, and even more preferably less than 3% by mass. It is anticipated that the metal compound-containing material may contain unintended, unavoidable impurities. The content of unavoidable impurities is preferably less than 0.01% by mass.

[0095] In this specification, when "X to Y" (X and Y are any numbers) is expressed, unless otherwise specified, it means "X or more and Y or less," and also includes the meaning "preferably larger than X" or "preferably smaller than Y." Furthermore, when "X or more" (X is any number) or "Y or less" (Y is any number), it also includes the meaning "preferably larger than X" or "preferably smaller than Y." [Effects of the Invention]

[0096] The method for producing a coated structure of the present invention can produce a coated structure having a uniform metal-carbon composite coating on a carbon substrate, regardless of the size or shape of the substrate. [Brief explanation of the drawings]

[0097] [Figure 1] 1 is a table showing physical property values ​​of the coated structures according to Examples 1 to 10 of the present invention, the carbon substrates according to Comparative Examples 1, 3, and 4, and the coated structure according to Comparative Example 2. [Figure 2] 1 is a table showing physical property values ​​of the carbon substrates according to Examples 11 to 17 of the present invention and Comparative Examples 5 and 6. [Figure 3] 1 is a table showing physical property values ​​of the coated structures according to Examples 18 and 19 of the present invention and the carbon substrate according to Comparative Example 7. BEST MODE FOR CARRYING OUT THE INVENTION

[0098] The coated structure according to the embodiment of the present invention will be further described below with reference to the following examples, although the present invention is not limited to these examples.

[0099] Example 1 A tantalum peroxocitrate solution was applied to the entire surface of a carbon substrate (length x width x thickness: 50 mm x 50 mm x 3 mm) using a brush (the amount applied was 0.0075 g). Next, the carbon substrate coated with the tantalum peroxocitrate solution was placed in an electric furnace and dried for 10 minutes in the electric furnace heated to 110°C. Thereafter, it was heated for 1 hour in an Ar atmosphere in the electric furnace heated to 1500°C. Then, it was cooled to room temperature to obtain a coated structure according to Example 1.

[0100] The tantalum peroxocitrate solution used in Example 1 was obtained as follows.

[0101] A first mixed solution was obtained by stirring and mixing 200 g of tantalum hydroxide and 92 g of 25 mass% ammonia water for 10 minutes. Then, 220 g of 35 mass% hydrogen peroxide water was further 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 tantalum peroxocitrate solution used in Example 1. The tantalum concentration of the tantalum peroxocitrate solution used in Example 1 was 18% in terms of Ta2O5 and 14.3% in terms of Ta.

[0102] The tantalum peroxocitrate solution used in Example 1 was a clear solution without precipitate immediately after production, and remained a clear solution without precipitate even 7 days after production. The Ta2O5-equivalent concentration of the tantalum peroxocitrate solution used in Example 1 after 7 days of production was 175 g / L. Furthermore, the average particle size of the tantalum peroxocitrate solution used in Example 1 after 7 days of production, as measured by dynamic light scattering, was 625.2 nm.

[0103] On the other hand, the carbon substrate used in Example 1 was an extrusion-molded carbon substrate (a graphite flat plate extrusion material, manufactured by Tokyo Tanso Kogyo Co., Ltd.), but is not limited to extrusion molding.

[0104] Example 2 A tantalum peroxocitrate solution was applied to the entire surface of a carbon substrate (length × width × thickness: 50 mm × 50 mm × 3 mm) using a brush. Next, the carbon substrate coated with the tantalum peroxocitrate solution was placed in an electric furnace and dried in the electric furnace heated to 110°C for 10 minutes. The tantalum peroxocitrate solution was again applied to the entire surface of the dried carbon substrate using a brush, and then dried in the electric furnace heated to 110°C for 10 minutes. This process was repeated two more times. That is, the process of coating the tantalum peroxocitrate solution on the carbon substrate and drying was repeated three times (the total coating amount for all three times was 0.0225 g). Thereafter, the carbon substrate was heated in an Ar atmosphere in an electric furnace heated to 1500°C for 1 hour. Then, the carbon substrate was cooled to room temperature to obtain a coated structure according to Example 2.

[0105] The tantalum peroxocitrate solution used in Example 2 is the same as the tantalum peroxocitrate solution used in Example 1, and therefore a detailed description thereof will be omitted. In addition, the carbon substrate used in Example 2 is the same as the carbon substrate used in Example 1, and therefore a detailed description thereof will be omitted.

[0106] Example 3 A tantalic acid aqueous solution (containing resin) was applied to the entire surface of a carbon substrate (length x width x thickness: 50 mm x 50 mm x 3 mm) using a brush (the amount applied was 0.0075 g). Next, the carbon substrate coated with the tantalic acid aqueous solution (containing resin) was placed in an electric furnace and dried for 10 minutes in the electric furnace heated to 110°C. Thereafter, it was heated for 1 hour in an Ar atmosphere in the electric furnace heated to 1500°C. Then, by cooling to room temperature, a coated structure according to Example 3 was obtained.

[0107] The aqueous tantalic acid solution (containing a resin) used in Example 3 was obtained as follows.

[0108] 137.9 g of tantalum hydroxide (manufactured by Mitsui Mining & Smelting Co., Ltd., Ta2O5 concentration 66 mass%) was dissolved in 120 g of 55 mass% hydrofluoric acid aqueous solution, and 849 mL of ion-exchanged water was added to obtain an aqueous tantalum fluoride solution (Ta2O5 concentration 8.2 mass%).

[0109] To 1,000 g of this tantalum fluoride aqueous solution, 27.5 g of hydrogen peroxide solution (H2O2 concentration 35 mass %) was added (H2O2 / Ta molar ratio = 0.76), and the mixture was stirred for 5 minutes to obtain an aqueous tantalum compound solution.

[0110] 1,000 g of this tantalum compound aqueous solution was added to 6.82 L of ammonia water (NH concentration 25% by mass) over a period of less than 10 minutes (NH / Ta molar ratio = 245, NH / HF molar ratio = 30.7) to obtain a reaction solution (pH 11). This reaction solution was a slurry of tantalum acid compound hydrate, in other words, a slurry of tantalum-containing precipitate.

[0111] The reaction solution was then decanted using a centrifuge and washed until the amount of liberated fluoride ions was 100 mg / L or less, yielding a tantalum-containing precipitate from which the fluoride ions had been removed, using aqueous ammonia as the washing liquid.

[0112] The tantalum-containing precipitate from which the fluoride ions had been removed was then diluted with pure water to obtain a tantalum-containing precipitate slurry. A portion of this tantalum-containing precipitate slurry was dried at 110°C for 24 hours and then fired at 1,000°C for 4 hours to produce Ta2O5, and the Ta2O5 concentration in the tantalum-containing precipitate slurry was calculated from its weight.

[0113] The tantalum-containing precipitate slurry diluted with pure water, 5% by mass of dimethylamine as an organic nitrogen compound, and pure water were mixed so that the final mixture had a tantalum concentration of 5% by mass in terms of Ta2O5 and a weight ratio of Ta2O5 / organic nitrogen compound of 1.0, thereby obtaining an aqueous tantalic acid solution. The pH of the aqueous tantalic acid solution was 12.0.

[0114] A neutralized salt of a polyolefin-based polymer copolymer (Zaixen A manufactured by Sumitomo Seika Chemicals Co., Ltd.) was added to the resulting tantalic acid aqueous solution, and the mixture was stirred at 25°C for 30 minutes to obtain the tantalic acid aqueous solution (containing resin) used in Example 3. The tantalum concentration of the tantalic acid aqueous solution (containing resin) used in Example 3 was 5% in terms of Ta2O5, or 4.1% in terms of Ta. The content of the resin component contained in the tantalic acid aqueous solution (containing resin) used in Example 3 was 0.025% by mass, where the tantalic acid aqueous solution was taken as 100% by mass.

[0115] Here, the added neutralized salt of polyolefin-based polymer copolymer was weighed so that, when the total amount of the neutralized salt of polyolefin-based polymer copolymer was taken as 100% by mass, the resin component was 25% by mass, ammonia water was less than 1% by mass, and the remainder was pure water.

[0116] On the other hand, the carbon substrate used in Example 3 is the same as the carbon substrate used in Example 1, and therefore a detailed description thereof will be omitted.

[0117] Example 4 A tantalic acid aqueous solution (containing a resin) was applied to the entire surface of a carbon substrate (length × width × thickness: 50 mm × 50 mm × 3 mm) using a brush. Next, the carbon substrate coated with the tantalic acid aqueous solution (containing a resin) was placed in an electric furnace and dried in the electric furnace heated to 110°C for 10 minutes. The dried carbon substrate was again coated with the tantalic acid aqueous solution (containing a resin) using a brush, and then dried in an electric furnace heated to 110°C for 10 minutes. This process was repeated two more times. That is, the process of coating the tantalic acid aqueous solution (containing a resin) on the carbon substrate and drying it was repeated three times (the total coating amount for all three times was 0.0225 g). Thereafter, the carbon substrate was heated in an electric furnace heated to 1500°C for 1 hour under an Ar atmosphere. Then, the coated structure according to Example 4 was obtained by cooling to room temperature.

[0118] Furthermore, the tantalic acid aqueous solution (containing a resin) used in Example 4 is the same as the tantalic acid aqueous solution (containing a resin) used in Example 3, and therefore a detailed description thereof will be omitted.

[0119] On the other hand, the carbon substrate used in Example 4 is the same as the carbon substrate used in Example 1, and therefore a detailed description thereof will be omitted.

[0120] Example 5 A tantalic acid compound-containing liquid was applied to the entire surface of a carbon substrate (length x width x thickness: 50 mm x 50 mm x 3 mm) using a brush (the amount applied was 0.0075 g). Next, the carbon substrate coated with the tantalic acid compound-containing liquid was placed in an electric furnace and dried for 10 minutes in the electric furnace heated to 110°C. Thereafter, it was heated for 1 hour in an Ar atmosphere in the electric furnace heated to 1500°C. Then, by cooling to room temperature, a coated structure according to Example 5 was obtained.

[0121] The tantalic acid compound-containing liquid used in Example 5 was obtained as follows.

[0122] 100 g of tantalum hydroxide (Ta2O5 concentration 99.9 mass%) manufactured by Mitsui Mining & Smelting Co., Ltd. was dissolved in 100 g of 55 mass% hydrofluoric acid aqueous solution, and 100 mL of ion-exchanged water was added to obtain an aqueous tantalum fluoride solution (Ta2O5 concentration 33.3 mass%).

[0123] To 100 g of this aqueous tantalum fluoride solution, 1000 mL of aqueous ammonia (NH3 concentration: 25 mass %) was added to obtain a fluorine-containing tantalum hydrate cake.

[0124] Next, this fluorine-containing tantalum hydrate cake was decanted using a centrifuge and washed with dilute ammonia water until the amount of liberated fluoride ions was 100 mg / L or less, thereby obtaining a tantalum-containing precipitate from which the fluoride ions had been removed. At this time, ammonia water was used as the washing liquid.

[0125] The tantalum concentration of the obtained tantalum-containing precipitate was determined by collecting a portion of the tantalum-containing precipitate, drying it at 110°C for 24 hours, and then firing it at 1000°C for 4 hours to produce Ta2O5. The weight of the Ta2O5 produced in this manner was measured, and the Ta2O5 (tantalum oxide, oxide equivalent) concentration of the tantalum-containing precipitate calculated from the weight was 50 mass%. The Ta (tantalum, metal equivalent) concentration of the tantalum-containing precipitate was calculated to be 40.9 mass%.

[0126] Then, 50 g of 10 mass% triethylamine and 317 g of pure water were added to the resulting tantalum-containing precipitate and stirred for 10 minutes to obtain a tantalum-containing mixed solution. Subsequently, 83 g of 35 mass% hydrogen peroxide was added to the tantalum-containing mixed solution so that the final tantalum concentration was 5 mass% in terms of oxide (Ta2O5 equivalent), 4.1 mass% in terms of metal (Ta equivalent), and 6.8 mass% in terms of hydrogen peroxide. The mixture was stirred for 30 minutes to obtain the tantalum acid compound-containing solution used in Example 5. The tantalum concentration of the tantalum acid compound-containing solution used in Example 5 was 5% in terms of Ta2O5 equivalent and 4.1% in terms of Ta equivalent. No precipitates or sediments were observed in the tantalum acid compound-containing solution used in Example 5. The pH of the tantalum acid compound-containing solution used in Example 5 was 11.0.

[0127] On the other hand, the carbon substrate used in Example 5 was the same as the carbon substrate used in Example 1, and therefore a detailed description thereof will be omitted.

[0128] Example 6 A tantalic acid compound-containing liquid (containing resin) was applied to the entire surface of a carbon substrate (length x width x thickness: 50 mm x 50 mm x 3 mm) using a brush (the amount applied was 0.0075 g). Next, the carbon substrate coated with the tantalic acid compound-containing liquid (containing resin) was placed in an electric furnace and dried for 10 minutes in the electric furnace heated to 110°C. Thereafter, it was heated for 1 hour in an Ar atmosphere in the electric furnace heated to 1500°C. Then, by cooling to room temperature, a coated structure according to Example 6 was obtained.

[0129] The tantalic acid compound-containing liquid (including resin) used in Example 6 was obtained by adding a polyolefin polymer copolymer neutralization salt (Zaixen A manufactured by Sumitomo Seika Chemicals Co., Ltd.) to the tantalic acid compound-containing liquid used in Example 5 and stirring at 25°C for 30 minutes. The tantalum concentration of the tantalic acid compound-containing liquid (including resin) used in Example 6 was 5% in terms of Ta2O5, or 4.1% in terms of Ta. The content of the resin component in the tantalic acid compound-containing liquid (including resin) used in Example 6 was 0.025% by mass, where the tantalic acid compound-containing liquid (including resin) was taken as 100% by mass.

[0130] The polyolefin-based polymer copolymer neutralized salt added in Example 6 was the same as the polyolefin-based polymer copolymer neutralized salt used in Example 3, and therefore a detailed description thereof will be omitted.

[0131] On the other hand, the carbon substrate used in Example 6 was the same as the carbon substrate used in Example 1, and therefore a detailed description thereof will be omitted.

[0132] Example 7 In Example 7, a carbon substrate (length x width x thickness: 25 mm x 25 mm x 3 mm) was used, and the tantalum concentration of the tantalum peroxocitrate solution used in Example 7 was 1% in terms of Ta2O5, which was adjusted to 0.8% in terms of Ta, and a coated structure according to Example 7 was obtained by carrying out the same manufacturing method as in Example 1. The amount of the tantalum peroxocitrate solution used in Example 7 to be applied was 0.054 g.

[0133] Example 8 In Example 8, a carbon substrate (length x width x thickness: 25 mm x 25 mm x 3 mm) was used, and the tantalum concentration of the tantalum peroxocitrate solution used in Example 8 was 5% in terms of Ta2O5, which was adjusted to 4.1% in terms of Ta, and a coated structure according to Example 8 was obtained by carrying out the same manufacturing method as in Example 1. The amount of the tantalum peroxocitrate solution applied in Example 8 was 0.113 g.

[0134] Example 9 In Example 9, a carbon substrate (length x width x thickness: 25 mm x 25 mm x 3 mm) was used, and the tantalum concentration of the tantalum peroxocitrate solution used in Example 9 was 20% in terms of Ta2O5, which was adjusted to 16.4% in terms of Ta, and a coated structure according to Example 9 was obtained by carrying out the same manufacturing method as in Example 1. The amount of the tantalum peroxocitrate solution used in Example 9 to be applied was 0.174 g.

[0135] Example 10 In Example 10, a coated structure according to Example 10 was obtained by carrying out the same manufacturing method as in Example 1, except that the carbon substrate (length x width x thickness: 25 mm x 25 mm x 3 mm) was a CIP material (a graphite flat plate CIP material manufactured by Tokyo Tanso Kogyo Co., Ltd.), and the tantalum concentration of the tantalum peroxocitrate solution used in Example 10 was 20% in terms of Ta2O5, adjusted to 16.4% in terms of Ta. The amount of the tantalum peroxocitrate solution applied in Example 10 was 0.2 g.

[0136] Example 11 A tantalic acid aqueous solution (containing resin) was applied to the entire surface of a carbon substrate (length x width x thickness: 25 mm x 25 mm x 10 mm) using a brush (the amount applied was 3.04 g). Next, the carbon substrate coated with the tantalic acid aqueous solution (containing resin) was placed in an electric furnace and dried for 10 minutes in the electric furnace heated to 110°C. Thereafter, it was heated for 1 hour in an Ar atmosphere in the electric furnace heated to 1500°C. Then, by cooling to room temperature, a coated structure according to Example 11 was obtained.

[0137] The tantalum acid aqueous solution (containing a resin) used in Example 11 was obtained by carrying out the same production method as in Example 3, except that the tantalum concentration of the tantalum acid aqueous solution (containing a resin) used in Example 11 was 1% in terms of Ta2O5, and was adjusted to 0.8% in terms of Ta.

[0138] The polyolefin-based polymer copolymer neutralized salt added in Example 11 was the same as the polyolefin-based polymer copolymer neutralized salt used in Example 3, and therefore a detailed description thereof will be omitted.

[0139] On the other hand, the carbon substrate used in Example 11 was a heat insulating material (Kureka Felt GF-210, manufactured by Kureha Corporation).

[0140] Example 12 A tantalum peroxocitrate solution (containing a surfactant) was applied to the entire surface of a carbon substrate (length x width x thickness: 25 mm x 25 mm x 10 mm) using a brush (the amount applied was 1.99 g). Next, the carbon substrate coated with the tantalum peroxocitrate solution (containing a surfactant) was placed in an electric furnace and dried for 10 minutes in the electric furnace heated to 110°C. Thereafter, it was heated for 1 hour in an Ar atmosphere in the electric furnace heated to 1500°C. Then, the coated structure according to Example 12 was obtained by cooling to room temperature.

[0141] The tantalum peroxocitrate solution (containing a surfactant) used in Example 12 was obtained as follows.

[0142] A first mixture was obtained by stirring 200 g of tantalum hydroxide and 92 g of 25 mass % ammonia water for 10 minutes. 220 g of 35 mass % hydrogen peroxide water was then added to the first mixture and stirred for 10 minutes to obtain a second mixture. 79 g of citric acid was then added to the second mixture and stirred for 10 minutes to obtain a tantalum peroxocitrate solution.

[0143] A surfactant was then added to the obtained tantalum peroxocitrate solution, and the mixture was stirred at 25°C for 30 minutes to obtain the tantalum peroxocitrate solution (containing a surfactant) used in Example 12. The tantalum concentration of the tantalum peroxocitrate solution (containing a surfactant) used in Example 12 was 1% in terms of Ta2O5, and 0.8% in terms of Ta. The content of the surfactant contained in the tantalum peroxocitrate solution (containing a surfactant) used in Example 12 was 0.025% by mass, where the tantalum peroxocitrate solution was taken as 100% by mass.

[0144] The surfactant added here is a polyoxyethylene-added acetylene glycol surfactant.

[0145] On the other hand, the carbon substrate used in Example 12 was the same as the carbon substrate used in Example 11, and therefore a detailed description thereof will be omitted.

[0146] Example 13 A tantalum peroxocitrate solution (containing a surfactant) was applied to the entire surface of a carbon substrate (length x width x thickness: 25 mm x 25 mm x 10 mm) using a brush (the amount applied was 2.22 g). Next, the carbon substrate coated with the tantalum peroxocitrate solution (containing a surfactant) was placed in an electric furnace and dried for 10 minutes in the electric furnace heated to 110°C. Thereafter, it was heated for 1 hour in an Ar atmosphere in the electric furnace heated to 1500°C. Then, the coated structure according to Example 13 was obtained by cooling to room temperature.

[0147] The tantalum peroxocitrate solution (containing a surfactant) used in Example 13 was obtained by carrying out a production method similar to that of Example 12, except that the tantalum concentration of the tantalum peroxocitrate solution (containing a surfactant) used in Example 13 was 5% in terms of Ta2O5, and was adjusted to 4.1% in terms of Ta.

[0148] Furthermore, the surfactant used in Example 13 was the same as that used in Example 12, and therefore a detailed description thereof will be omitted.

[0149] On the other hand, the carbon substrate used in Example 13 was the same as the carbon substrate used in Example 11, and therefore a detailed description thereof will be omitted.

[0150] Example 14 A tantalum peroxocitrate solution (containing a surfactant) was applied to the entire surface of a carbon substrate (length x width: 50 mm x 50 mm) using a brush (the amount applied was 0.44 g). Next, the carbon substrate coated with the tantalum peroxocitrate solution (containing a surfactant) was placed in an electric furnace and dried for 10 minutes in the electric furnace heated to 110°C. Thereafter, it was heated for 1 hour in an Ar atmosphere in the electric furnace heated to 1500°C. Then, by cooling to room temperature, a coated structure according to Example 14 was obtained.

[0151] The tantalum peroxocitrate solution (containing a surfactant) used in Example 14 was obtained by carrying out a production method similar to that of Example 12, except that the tantalum concentration of the tantalum peroxocitrate solution (containing a surfactant) used in Example 14 was 5% in terms of Ta2O5, and was adjusted to 4.1% in terms of Ta.

[0152] Furthermore, the surfactant used in Example 14 was the same as that used in Example 12, and therefore a detailed description thereof will be omitted.

[0153] On the other hand, the carbon substrate used in Example 14 was cloth (MUTEKI carbon cloth carbon (carbon fiber) manufactured by MUGE).

[0154] Example 15 A tantalum peroxocitrate solution was applied to the entire surface of a carbon substrate (length x width: 50 mm x 50 mm) using a brush (the amount applied was 0.34 g). Next, the carbon substrate coated with the tantalum peroxocitrate solution was placed in an electric furnace and dried for 10 minutes in the electric furnace heated to 110°C. Thereafter, it was heated for 1 hour in an Ar atmosphere in the electric furnace heated to 1500°C. Then, by cooling to room temperature, a coated structure according to Example 15 was obtained.

[0155] The tantalum peroxocitrate solution used in Example 15 was the same as the tantalum peroxocitrate solution used in Example 8, and therefore a detailed description thereof will be omitted.

[0156] On the other hand, the carbon substrate used in Example 15 was the same as the carbon substrate used in Example 14, and therefore a detailed description thereof will be omitted.

[0157] Example 16 A tantalum peroxocitrate solution was applied to the entire surface of a carbon substrate (length x width: 50 mm x 50 mm) using a brush (the amount applied was 0.75 g). Next, the carbon substrate coated with the tantalum peroxocitrate solution was placed in an electric furnace and dried for 10 minutes in the electric furnace heated to 110°C. Thereafter, it was heated for 1 hour in an Ar atmosphere in the electric furnace heated to 1500°C. Then, by cooling to room temperature, a coated structure according to Example 16 was obtained.

[0158] The tantalum peroxocitrate solution used in Example 16 was the same as the tantalum peroxocitrate solution used in Example 9, and therefore a detailed description thereof will be omitted.

[0159] On the other hand, the carbon substrate used in Example 16 was the same as the carbon substrate used in Example 14, and therefore a detailed description thereof will be omitted.

[0160] Example 17 The metal acid compound mixture was applied to the entire surface of a carbon substrate (length x width: 50 mm x 50 mm) using a brush (the amount applied was 0.5 g). Next, the carbon substrate coated with the metal acid compound mixture was placed in an electric furnace and dried for 10 minutes in the electric furnace heated to 110°C. Thereafter, it was heated for 1 hour in an Ar atmosphere in the electric furnace heated to 1500°C. Then, by cooling to room temperature, a coated structure according to Example 17 was obtained.

[0161] The metal acid compound mixed solution used in Example 17 was a mixed solution prepared by adjusting the concentration of each of a tantalic acid aqueous solution, a niobic acid aqueous solution, a titanic acid aqueous solution, and a zirconium aqueous solution to 1% and a hafnic acid aqueous solution and a silicic acid aqueous solution to 0.2% when the metal acid compound mixed solution was taken as 100%. The metal acid compound mixed solution used in Example 17 was obtained as follows.

[0162] The tantalic acid aqueous solution contained in the metal acid compound mixed solution used in Example 17 was obtained in the same manner as the tantalic acid aqueous solution used in Example 3.

[0163] The aqueous niobic acid solution used in Example 17 was obtained as follows.

[0164] 100 g of niobium pentoxide was dissolved in 200 g of a 55 mass % aqueous solution of hydrofluoric acid, and 830 mL of ion-exchanged water was added to obtain an aqueous solution of niobium fluoride (Nb2O5=8.84 mass %).

[0165] 200 mL of this niobium fluoride aqueous solution was added to 1 L of ammonia water (NH concentration 25 mass %) over a period of less than 1 minute (NH / NbO molar ratio = 177.9, NH / HF molar ratio = 12.2) to obtain a reaction solution (pH 11). This reaction solution was a slurry of niobium acid compound hydrate, in other words, a slurry of niobium-containing precipitates.

[0166] The reaction solution was then decanted using a centrifuge and washed with aqueous ammonia until the amount of liberated fluoride ions reached 100 mg / L or less to obtain a niobium-containing precipitate from which the fluoride ions had been removed.

[0167] The niobium-containing precipitate from which the fluoride ions had been removed was then diluted with pure water to obtain a slurry. A portion of this niobium-containing precipitate slurry was dried at 110°C for 24 hours and then calcined at 1000°C for 4 hours to produce Nb2O5, and the Nb2O5 concentration in the niobium-containing precipitate slurry was calculated from its weight.

[0168] Then, pure water was added to the niobium-containing precipitate slurry diluted with pure water, and a 50 mass% aqueous dimethylamine solution was added as an organic nitrogen compound so that the dimethylamine concentration was 7.2 mass%, thereby adjusting the Nb2O5 solid concentration to 24.0 mass%. This slurry was stirred for 48 hours to obtain the aqueous niobic acid solution used in Example 17. The pH of the aqueous niobic acid solution used in Example 17 was 11.0.

[0169] The titanic acid aqueous solution used in Example 17 was obtained as follows.

[0170] 33.3 g of titanyl sulfate (manufactured by Teika Corporation, TiO2 concentration 33.3 mass%, sulfuric acid concentration 51.1 mass%) was added to 66.7 g of ion-exchanged water and allowed to stand at 90°C or higher for 1 hour to dissolve, thereby obtaining an aqueous titanyl sulfate solution (titanium concentration (TiO2 equivalent) 11 mass%, sulfuric acid 17 mass%, pH 1 or less).

[0171] 100 g of this titanyl sulfate aqueous solution was added to 100 g of 50% by mass dimethylamine (6.4 moles of amine per mole of sulfuric acid in the titanyl sulfate aqueous solution) over a period of less than 1 minute. The mixture was then stirred for 15 minutes to obtain a neutralized reaction solution (pH 12). This neutralized reaction solution was a slurry of titanium-containing materials, in other words, a slurry of titanium-containing precipitates.

[0172] Next, the neutralized reaction solution was decanted using a centrifuge and washed until the sulfuric acid concentration in the supernatant was 100 mg / L or less, to obtain a titanium-containing precipitate from which sulfuric acid had been removed. At this time, ammonia water was used as the washing liquid.

[0173] A portion of this titanium-containing precipitate was fired at 1,000°C for 4 hours to produce TiO2, and the TiO2 concentration in the titanium-containing precipitate was calculated from its mass, which was found to be 11.0 mass%.

[0174] Then, 45 g of this titanium-containing precipitate was mixed with 5 g of tetramethylammonium hydroxide pentahydrate (TMAH concentration 50% by mass) (0.443 mol per mol of Ti in the titanium-containing precipitate), and the mixture was shaken for 24 hours using a paint shaker to obtain the titanic acid aqueous solution used in Example 12. The titanium concentration of the titanic acid aqueous solution used in Example 17 was 8% in terms of TiO2 and 4.8% in terms of Ti. The pH of the titanic acid aqueous solution used in Example 17 was 13.7.

[0175] The aqueous zirconate solution used in Example 17 was prepared as follows.

[0176] 3.01 g (0.01 mol) of zirconium sulfate monohydrate was dissolved in 2.50 g (0.014 mol) of 55 mass % aqueous sulfuric acid solution, and 25 g of ion-exchanged water and 2.5 g (0.026 mol) of 35 mass % aqueous hydrogen peroxide solution were added (H2O2 / ZrO2 molar ratio = 2.6), to obtain an aqueous zirconium sulfate solution containing 4.3 mass % zirconium in terms of ZrO2.

[0177] Next, the entire amount of the zirconium sulfate aqueous solution was added to 100 g (1.47 mol) of ammonia water (NH3 concentration 25 mass%) in less than 1 minute (NH3 / ZrO2 molar ratio = 147, NH3 / SO4 2- A reaction solution was obtained by a reverse neutralization reaction (molar ratio = 43). This reaction solution was a slurry of a zirconate compound hydrate, in other words, a slurry of a zirconium-containing precipitate.

[0178] The reaction solution was decanted using a centrifuge and washed until the conductivity reached 500 μS / cm or less, yielding a zirconium-containing precipitate from which the sulfur content had been removed. In this case, aqueous ammonia was used as the washing liquid.

[0179] Furthermore, the zirconium-containing precipitate from which the sulfur content had been removed was diluted with pure water to obtain a zirconium-containing precipitate slurry from which the sulfur content had been removed. A portion of the zirconium-containing precipitate slurry from which the sulfur content had been removed was dried at 110°C for 24 hours and then fired at 1,000°C for 4 hours to produce ZrO2, and the ZrO2 concentration in the zirconium-containing precipitate slurry from which the sulfur content had been removed was calculated from the weight of the ZrO2.

[0180] The sulfur-removed zirconium-containing precipitate slurry diluted with pure water was mixed with 13.7 g (0.023 mol) of 15% by mass tetramethylammonium hydroxide (TMAH) and 28.5 g of ion-exchanged water (TMAH / ZrO molar ratio = 2.2) so that the zirconium concentration of the final mixture was 10% by mass in terms of ZrO and 7.2% by mass in terms of tetramethylammonium hydroxide (TMAH). The mixture was stirred and held at room temperature (25°C) for 1 hour to obtain the aqueous zirconate solution used in Example 11. The zirconium concentration of the aqueous zirconate solution used in Example 17 was 8% in terms of ZrO and 5.9% in terms of Zr. The pH of the aqueous zirconate solution used in Example 17 was 13.7.

[0181] The aqueous hafnic acid solution used in Example 17 was obtained as follows.

[0182] To 76.0 g of hafnium oxide (98% purity, powder, manufactured by Kojundo Kagaku Kenkyusho Co., Ltd.), 105.1 g of 55% by mass hydrofluoric acid and 796.9 g of pure water were added, heated to 80 ° C in a water bath, and stirred for 24 hours to dissolve the compound, obtaining a hydrofluoric acid solution of the hafnium compound. 60 g of this hafnium compound hydrofluoric acid solution was added to 2.2 g of 35% by mass hydrogen peroxide water to obtain a hafnium complex aqueous solution (H2O2 / Hf molar ratio = 1.0). After stirring for 5 minutes, this solution was gradually added to 377.2 g of 25% by mass ammonia water (NH3 / Hf molar ratio = 250). After stirring for 5 minutes, a neutralized reaction solution containing hafnium hydroxide was obtained as a precipitate.

[0183] Next, this neutralized reaction solution was decanted using a centrifuge, and a precipitate (containing hafnium hydroxide) was collected. The collected precipitate was mixed with 200 g of 25 mass % ammonia water to form a slurry, and then decanted again to collect the precipitate. This decantation and collection process of the precipitate (containing hafnium hydroxide) was repeated three times.

[0184] Then, 31.1 g of 25 mass % TMAH was added to the recovered precipitate (containing hafnium hydroxide) to obtain a mixed solution. Pure water was added to the mixed solution until the total weight reached 77.7 g, so that the final hafnium concentration was 6 mass % in terms of HfO2, and this mixed solution was stirred for 6 hours to obtain the hafnium acid aqueous solution used in Example 17. The pH of the hafnium acid aqueous solution used in Example 17 was 14.8.

[0185] The aqueous silicic acid solution used in Example 17 was obtained as follows.

[0186] In a 100 mL beaker, 11.0 g of tetraethoxysilane (TEOS, manufactured by Tokyo Ohka Kogyo Co., Ltd.), a silicon-containing raw material, was added with 0.1 g of acetic acid (manufactured by Hayashi Pure Chemical Industries, Ltd.), an acidic aqueous solution, 15 g of industrial ethanol (Solmix AP-7 (a mixed alcohol solvent containing 85.5 mass% ethanol, 9.6 mass% 1-propanol, 4.9 mass% 2-propanol, and 0.2 mass% or less water), manufactured by Toyo Petrochemical Co., Ltd.), and 8 g of pure water. The mixture was mixed at room temperature (25°C) for 20 hours while stirring with a stirrer tip, yielding 6 g of a dried silicon compound as a transparent precipitate.

[0187] Next, 2.6 g of 40% by mass methylamine (manufactured by Mitsubishi Gas Chemical Company, Inc.) and 8.9 g of pure water were added to 6 g of the obtained dried silicon compound, and the mixture was mixed at room temperature (25°C) for 10 hours while stirring with a stirrer tip to obtain the aqueous silicic acid solution used in Example 17.

[0188] The metal acid compound mixed solution used in Example 17 was obtained by adjusting the tantalic acid aqueous solution, niobic acid aqueous solution, titanic acid aqueous solution, zirconium aqueous solution, hafnic acid aqueous solution, and silicic acid aqueous solution so that the tantalic acid aqueous solution, niobic acid aqueous solution, titanic acid aqueous solution, and zirconium aqueous solution were each 1% and the hafnic acid aqueous solution and silicic acid aqueous solution were each 0.2%, when the metal acid compound mixed solution used in Example 17 was taken as 100%.

[0189] Example 18 A carbon substrate (length × width × thickness: 50 mm × 50 mm × 3 mm) was immersed in a 50 mL beaker with an aqueous zirconate solution (approximately 10 mL), and the aqueous zirconate solution was impregnated into the carbon substrate under reduced pressure (so-called vacuum impregnation) (the impregnated amount was 0.98 g). Next, the carbon substrate impregnated with the aqueous zirconate solution was placed in an electric furnace and dried for 60 minutes in an electric furnace heated to 100°C. Thereafter, it was heated for 1 hour in an Ar atmosphere in an electric furnace heated to 1500°C. The carbon substrate was then cooled to room temperature to obtain a coated structure according to Example 18.

[0190] The aqueous zirconate solution used in Example 18 was the same as the aqueous zirconate solution used in Example 17, and therefore a detailed description thereof will be omitted.

[0191] On the other hand, the carbon substrate used in Example 18 was the same as the carbon substrate used in Example 1, and therefore a detailed description thereof will be omitted.

[0192] Example 19 A carbon substrate (length x width x thickness: 50 mm x 50 mm x 3 mm) was immersed in a titanic acid aqueous solution (approximately 10 ml) in a 50 mL beaker, and the titanic acid aqueous solution was impregnated into the carbon substrate under reduced pressure (impregnated amount: 0.96 g). Next, the carbon substrate impregnated with the titanic acid aqueous solution was placed in an electric furnace and dried for 60 minutes in the electric furnace heated to 100°C. Thereafter, it was heated for 1 hour in an Ar atmosphere in the electric furnace heated to 1500°C. Then, it was cooled to room temperature to obtain a coated structure according to Example 19.

[0193] The titanic acid aqueous solution used in Example 19 was the same as that used in Example 17, and therefore a detailed description thereof will be omitted.

[0194] On the other hand, the carbon substrate used in Example 19 was the same as the carbon substrate used in Example 1, and therefore a detailed description thereof will be omitted.

[0195] (Comparative Example 1) Comparative Example 1 is a carbon substrate in which the surface of the carbon substrate used in Example 1 was processed by repeatedly applying discharge to the surface using a discharge electrode made of a tantalum electrode.

[0196] (Comparative Example 2) A polyolefin-based polymer copolymer neutralization salt (Zaixen A manufactured by Sumitomo Seika Chemicals Co., Ltd.) was applied to the entire surface of a carbon substrate (length x width x thickness: 50 mm x 50 mm x 3 mm) using a brush. Next, the carbon substrate coated with the polyolefin-based polymer copolymer neutralization salt was placed in an electric furnace and dried for 10 minutes in the electric furnace heated to 110°C. Thereafter, it was heated for 1 hour in an Ar atmosphere in the electric furnace heated to 1500°C. Then, by cooling to room temperature, a coated structure according to Comparative Example 2 was obtained.

[0197] The polyolefin-based polymer copolymer neutralized salt used in Comparative Example 2 was the same as the polyolefin-based polymer copolymer neutralized salt used in Example 3, and therefore detailed description thereof will be omitted.

[0198] On the other hand, the carbon substrate used in Comparative Example 2 was the same as the carbon substrate used in Example 1, and therefore a detailed description thereof will be omitted.

[0199] (Comparative Example 3) Since the carbon substrate used in Comparative Example 3 is the same as that used in Example 7, detailed description thereof will be omitted.

[0200] Comparative Example 4 Since the carbon substrate used in Comparative Example 4 is the same as that used in Example 10, detailed description thereof will be omitted.

[0201] (Comparative Example 5) Since the carbon substrate used in Comparative Example 5 is the same as that used in Example 11, detailed description thereof will be omitted.

[0202] (Comparative Example 6) Since the carbon substrate used in Comparative Example 6 is the same as that used in Example 14, detailed description thereof will be omitted.

[0203] (Comparative Example 7) Since the carbon substrate used in Comparative Example 7 is the same as that used in Example 1, detailed description thereof will be omitted.

[0204] The following physical property values ​​were measured and evaluation tests were conducted for the coated structures of Examples 1 to 19, the carbon substrates of Comparative Examples 1, 3 to 7, and the coated structure of Comparative Example 2. The methods for measuring the physical property values ​​and the test methods for the evaluation tests are described below. The physical property values ​​of the coated structures of Examples 1 to 10, the carbon substrates of Comparative Examples 1, 3 and 4, and the coated structure of Comparative Example 2 are shown in FIG. 1. The physical property values ​​of the coated structures of Examples 11 to 17 and the carbon substrates of Comparative Examples 5 and 6 are shown in FIG. 2. The physical property values ​​of the coated structures of Examples 18 and 19 and the carbon substrate of Comparative Example 7 are shown in FIG. 3.

[0205] <Elemental analysis> If necessary, the sample was diluted appropriately with dilute hydrochloric acid, and the mass fraction in terms of metal was measured using an ICP optical emission analyzer (Agilent Technologies: AG-5110) in accordance with JIS K0116:2014.

[0206] Dynamic Light Scattering The particle size distribution of the metal compound-containing materials used in Examples 1 to 19 was evaluated using a zeta potential, particle size, and molecular weight measurement system (Otsuka Electronics Co., Ltd.: ELSZ-2000) in accordance with JIS Z 8828:2019 "Particle size analysis - dynamic light scattering method." In addition, to remove dust and other particles from the solution to be measured immediately before measurement, the materials were filtered through a 2 μm pore size filter and subjected to ultrasonic treatment at 28 kHz for 3 minutes in an ultrasonic cleaner (AS ONE Corporation: VS-100III). The particle size (D50) refers to the median diameter (D50), which is the particle size that represents the 50% cumulative value of the cumulative distribution curve.

[0207] <Light transmittance measurement> 4 ml of the metal compound-containing material used in Examples 1 to 19 was placed in a quartz cell with an optical path length of 5.0 mm, and the light transmittance of the metal compound-containing material used in Examples 1 to 19 in the wavelength range of 500 nm to 700 nm was measured using a spectrophotometer according to the light transmittance measurement conditions described above or the light transmittance measurement conditions (including Si).

[0208] <Heat resistance test> The coated structures of Examples 1 to 19, the carbon substrates of Comparative Examples 1 and 3 to 7, and the coated structure of Comparative Example 2 were subjected to heat resistance tests under the following three test conditions.

[0209] <Heat resistance test 1> First, the weights of the coated structures according to Examples 1 to 17, the carbon substrates according to Comparative Examples 1, 3 to 6, and the coated structure according to Comparative Example 2 before heat resistance test 1 (hereinafter referred to as "weight before test 1") were measured. Next, the coated structures according to Examples 1 to 17, the carbon substrates according to Comparative Examples 1, 3 to 6, and the coated structure according to Comparative Example 2 were placed in a tubular furnace and fired in an air atmosphere at a heating temperature of 700°C for a heating time of 90 minutes. The fired coated structures according to Examples 1 to 17, the carbon substrates according to Comparative Examples 1, 3 to 6, and the coated structure according to Comparative Example 2 were removed from the tubular furnace, and the weights after heat resistance test 1 (hereinafter referred to as "weight after test 1") were measured. Then, for the coated structures according to Examples 1 to 17, the carbon substrates according to Comparative Examples 1, 3 to 6, and the coated structure according to Comparative Example 2, the weight change (attenuation rate) during heat resistance test 1 was calculated from the weights before test 1 and the weights after test 1 using the following formula (1):

[0210]

number

[0211] Table 1 shows the test results of heat resistance test 1 for the coated structures of Examples 1 to 10, the carbon substrates of Comparative Examples 1, 3, and 4, and the coated structure of Comparative Example 2. Table 2 shows the test results of heat resistance test 1 for the coated structures of Examples 11 to 17 and the carbon substrates of Comparative Examples 6 and 7.

[0212] <Heat resistance test 2> The weights of the coated structures of Examples 5 and 6, the carbon substrate of Comparative Example 1, and the coated structure of Comparative Example 2 before heat resistance test 2 (hereinafter referred to as "weight before test 2") were measured. Next, the coated structures of Examples 5 and 6, the carbon substrate of Comparative Example 1, and the coated structure of Comparative Example 2 were placed in a tubular furnace and fired at 700°C for 90 minutes in a 5% by volume O2-95% by volume N2 mixed gas atmosphere. The fired coated structures of Examples 5 to 6, the carbon substrate of Comparative Example 1, and the coated structure of Comparative Example 2 were removed from the tubular furnace, and the weights after heat resistance test 2 (hereinafter referred to as "weight after test 2") were measured. Then, the weight change (decay rate) in heat resistance test 2 for the coated structures of Examples 5 and 6, the carbon substrate of Comparative Example 1, and the coated structure of Comparative Example 2 was calculated from the weights before test 2 and the weights after test 2 using the following formula (2):

[0213]

number

[0214] Table 3 shows the test results of the heat resistance test 2 for the coated structures of Examples 5 and 6, the carbon substrate of Comparative Example 1, and the coated structure of Comparative Example 2.

[0215] <Heat resistance test 3> First, the weights of the coated structures of Examples 18 and 19 and the carbon substrate of Comparative Example 7 before heat resistance test 3 (hereinafter referred to as "weight before test 3") were measured. Next, the coated structures of Examples 18 and 19 and the carbon substrate of Comparative Example 7 were placed in a tubular furnace and fired in an air atmosphere at a heating temperature of 600°C for 180 minutes. The fired coated structures of Examples 18 and 19 and the carbon substrate of Comparative Example 7 were removed from the tubular furnace, and the weights after heat resistance test 3 (hereinafter referred to as "weight after test 3") were measured. Then, for the coated structures of Examples 18 and 19 and the carbon substrate of Comparative Example 7, the weight change (decay rate) in heat resistance test 3 was calculated from the weights before test 3 and the weights after test 3 using the following formula (3):

[0216]

number

[0217] The test results of the heat resistance test 3 for the coated structures according to Examples 18 and 19 and the carbon substrate according to Comparative Example 7 are shown in Table 4.

[0218] [Table 1]

[0219] [Table 2]

[0220] [Table 3]

[0221] [Table 4]

[0222] The coated structures of Examples 1 to 17 have a uniform metal-carbon composite coating on the carbon substrate by applying a metal compound-containing material onto the carbon substrate and then heating the carbon substrate to which the metal compound-containing material has been applied.

[0223] The coated structures of Examples 18 and 19 have a uniform metal-carbon composite coating on the carbon substrate, which is formed by immersing the carbon substrate in a material containing a metal compound and then heating the immersed carbon substrate.

[0224] The attenuation rates in Heat Resistance Test 1 for the coated structures according to Examples 1 to 6 were 10% or less, meaning that no weight loss due to oxidation of the carbon substrate was observed, and the metal-carbon composite coating formed on the carbon substrate improved the heat resistance of the carbon substrate. On the other hand, the attenuation rates in Heat Resistance Test 1 for the carbon substrate according to Comparative Example 1 and the coated structure according to Comparative Example 2 were 15.8% and 17.1%, respectively.

[0225] The attenuation rates in Heat Resistance Test 1 for the coated structures according to Examples 7 to 9 were slightly reduced compared to the attenuation rate in Heat Resistance Test 1 for the carbon substrate according to Comparative Example 3. Furthermore, the attenuation rate in Heat Resistance Test 1 for the coated structure according to Example 10 was reduced to less than half of the attenuation rate in Heat Resistance Test 1 for the carbon substrate according to Comparative Example 4.

[0226] The attenuation rates in Heat Resistance Test 1 for the coated structures according to Examples 11 to 13 were smaller than the attenuation rate in Heat Resistance Test 1 for the carbon substrate according to Comparative Example 5. Furthermore, the attenuation rates in Heat Resistance Test 1 for the coated structures according to Examples 14 to 17 were significantly smaller than the attenuation rate in Heat Resistance Test 1 for the carbon substrate according to Comparative Example 6.

[0227] Furthermore, the attenuation rates in Heat Resistance Test 2 for the coated structures of Examples 5 and 6 were 2% or less, indicating that no weight loss due to oxidation of the carbon substrate was observed, and the heat resistance of the carbon substrate was improved by the metal-carbon composite coating formed on the carbon substrate. On the other hand, the attenuation rates in Heat Resistance Test 2 for the carbon substrate of Comparative Example 1 and the coated structure of Comparative Example 2 were 2.7% and 2.7%, respectively.

[0228] The attenuation rates of the coated structures according to Examples 18 and 19 in Heat Resistance Test 3 were slightly reduced compared to the attenuation rate of the carbon substrate according to Comparative Example 7 in Heat Resistance Test 3.

[0229] The results of the above-mentioned heat resistance tests 1 to 3 show that the heat resistance of the carbon substrate can be improved by the metal-carbon composite coating formed on the carbon substrate, regardless of the type of metal element contained in the metal-carbon composite coating or the size and type of the carbon substrate.

[0230] The inventions disclosed in this specification include, in addition to the configurations of each invention and embodiment, those specified by changing these partial configurations to other configurations disclosed in this specification, to the extent applicable, or those specified by adding other configurations disclosed in this specification to these configurations, or those specified as higher-level concepts specified by deleting these partial configurations to the extent that partial effects can be obtained. [Industrial Applicability]

[0231] The method for producing a coated structure according to the present invention is suitable as a method for producing a coated structure because it can form a uniform metal-carbon composite coating on a carbon substrate regardless of the size or shape of the substrate. Specifically, the method for producing a coated structure according to the present invention can form a uniform metal-carbon composite coating on a carbon substrate, thereby improving heat resistance and reactivity resistance and extending the life of the carbon substrate, thereby reducing waste and reducing energy costs for waste disposal. Furthermore, the method for producing a coated structure according to the present invention can form a uniform metal-carbon composite coating on a carbon substrate by applying a metal compound-containing material to the carbon substrate, or by immersing the carbon substrate in the metal compound-containing material and heating it, thereby reducing energy costs. Furthermore, the coated structure according to the present invention is suitable as a coated structure because it forms a uniform metal-carbon composite coating on a carbon substrate regardless of the size or shape of the substrate. Specifically, the coated structure according to the present invention has a uniform metal-carbon composite coating on the carbon substrate, thereby improving heat resistance and reactivity resistance and extending the life of the carbon substrate, thereby reducing waste and reducing energy costs for waste disposal. These points will lead to the sustainable management of natural resources and efficient utilization, as well as achieving carbon neutrality.

Claims

1. A method for producing a coated structure having a metal-carbon composite coating on a carbon substrate, comprising: a coating step of coating a metal compound-containing material onto the carbon substrate; a heating step of heating the coated carbon substrate to form a metal-carbon composite coating on the carbon substrate; A method for producing a coated structure, comprising:

2. A method for producing a coated structure having a metal-carbon composite coating on a carbon substrate, comprising: an immersion step of immersing the carbon substrate in a metal compound-containing material; a heating step of heating the immersed carbon substrate to form a metal-carbon composite coating on the carbon substrate; A method for producing a coated structure, comprising:

3. 3. The method for producing a coated structure according to claim 2, wherein the immersion step comprises impregnating the carbon substrate with the material containing a metal compound under reduced pressure or in vacuum.

4. 4. The method for producing a coated structure according to claim 1, further comprising a drying step between the coating step or the immersion step and the heating step.

5. 4. The method for producing a coated structure according to claim 1, wherein the metal compound-containing substance contains a compound of at least one metal element selected from the group consisting of Ti, Nb, Mo, Hf, Ta, W, Zr, and Si.

6. 6. The method for producing a coated structure according to claim 5, wherein the content of a compound of at least one metal element selected from Ti, Nb, Mo, Hf, Ta, W, Zr, and Si in the metal compound-containing material is more than 0 mass % and not more than 35 mass % in terms of metal.

7. 6. The method for producing a coated structure according to claim 5, wherein the metal compound-containing material contains a Ta compound.

8. 4. The method for producing a coated structure according to claim 1, wherein the metal compound-containing material has a maximum light transmittance of 70%T or more in the wavelength region of 500 nm to 700 nm.

9. 4. The method for producing a coated structure according to claim 1, wherein the metal compound-containing material has a particle diameter (D50) of 3000 nm or less as measured by a dynamic light scattering method.

10. 4. The method for producing a coated structure according to claim 1, wherein the metal compound-containing material has a pH of 6.5 or more and 13.5 or less.

11. 4. The method for manufacturing a coated structure according to claim 1, wherein the heating step is performed at a heating temperature of 1000° C. or more and 3500° C. or less for a heating time of 0.5 hours or more and 2 hours or less.

12. 12. The method for manufacturing a coated structure according to claim 11, wherein the heating step is performed at a heating temperature of 1400° C. or higher and 2000° C. or lower.

13. A coated structure in which a metal-carbon composite coating is formed on a carbon substrate, The metal-carbon composite coating is formed by heating the carbon substrate coated or impregnated with a metal compound-containing material.

14. 1. A metal compound-containing composition for a metal-carbon composite coating formed on a carbon substrate, comprising: A metal compound-containing material for a metal-carbon composite coating, which reacts with the carbon substrate to form a metal-carbon composite coating.

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