Classifications

• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
  • C04B41/009—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone characterised by the material treated
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/64—Burning or sintering processes
  • C04B35/645—Pressure sintering
  • C04B35/6455—Hot isostatic pressing
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
  • C04B41/45—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
  • C04B41/50—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials
  • C04B41/5025—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials with ceramic materials
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
  • C04B41/45—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
  • C04B41/52—Multiple coating or impregnating multiple coating or impregnating with the same composition or with compositions only differing in the concentration of the constituents, is classified as single coating or impregnation
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
  • C04B41/80—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone of only ceramics
  • C04B41/81—Coating or impregnation
  • C04B41/85—Coating or impregnation with inorganic materials
  • C04B41/87—Ceramics
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
  • C04B41/80—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone of only ceramics
  • C04B41/81—Coating or impregnation
  • C04B41/89—Coating or impregnation for obtaining at least two superposed coatings having different compositions

Definitions

• the present invention relates to a method for efficiently producing a ceramic sintered body having a dense ceramic film on the surface.
• Ceramic is a material that is expected to be superior to metal in heat resistance, corrosion resistance, wear resistance, etc.
• examples of such ceramics include aluminum, silicon nitride, silicon carbide, and partially stabilized zirconia. It is known that by forming a different type of ceramic film on the surface of a sintered body of these materials, a new function can be added to the properties of the sintered body itself. I have.
• alumina is coated on the surface of a sintered body of silicon nitride by CVD.
• Silicon nitride itself has excellent strength and toughness, but easily reacts with iron. For this reason, the use of iron mesh materials as cutting tools was limited.
• aluminum coating prevents the reaction between silicon nitride and iron, and extends the life of cutting tools.
• Such a method of forming a heterogeneous ceramic film on the surface of a ceramic includes the above-described method using CVD or PVD, and a method using a metal polymer. There is a method of applying the liquid to the surface of the sintered body and sintering it. Coating on the surface of sintered body by CVD Then, a dense film is obtained. However, the coating speed is low and coating is time-consuming. Furthermore, it is difficult to uniformly form a film on a product having a complicated shape, and it is difficult to apply the film to a large product. PVD has similar problems.
• a ceramic film examples include dispersing a ceramic powder, a hydroxide solution, a metal polymer liquid, a paste, and a solution on the surface of the sintered body. It is applied by spraying, brushing, dipping, etc., dried, thermally decomposed and sintered. Also, a method of spraying ceramic powder is known. These methods have less restrictions on shape and dimensions than CVD and PVD. However, there are drawbacks common to these methods. In other words, the formed film blocks the pores, and in many cases, the atmospheric gas comes into contact with the underlying sintered body through the pores, and the purpose of the coating is to improve the oxidation resistance, for example. It cannot be reached.
• a known molding method such as uniaxial pressing, CIP, extrusion, slurry injection, injection molding, etc. is applied to the raw material powder of the ceramic sintered body.
• a compact is obtained by applying various sintering methods.
• a sintering method for example, a low-pressure sintering method is known in which sintering is performed under vacuum, normal pressure, and a pressure of 10 atm. This one In the method, pores usually remain, and it is also known that HIP treatment is applied to the pores to achieve densification.
• a ceramic powder such as a dispersion of a ceramic powder, a solution of a hydroxide, a liquid of a gold polymer, a paste, or a solution is added to the sintered body obtained in this manner.
• the ceramic film precursor is applied by spraying, brushing, dipping, etc., and dried, thermally decomposed, and sintered to form a ceramic film.
• This ceramic membrane contains a considerable amount of porosity to varying degrees.
• This ceramic sintered body having a porous ceramic film is encapsulated in a glass or high-melting-point metal (tantalum, niobium, etc.) capsule, and the HIP is added to it. And remove the capsule. In this way, a ceramic sintered body having a dense ceramic film is obtained.
• a glass or high-melting-point metal tantalum, niobium, etc.
• the above object is achieved by heating at least a portion of the surface of a porous ceramic material obtained by a known method to which a new function is to be imparted.
• a precursor that converts to a membrane is applied by a known method, and then a precursor that converts to a gas-impermeable membrane by heating is applied to the entire surface of the porous body by a known method.
• This is achieved by subjecting the porous body to HIP and then removing the gas-impermeable membrane.
• FIG. 1 is a process chart showing the outline of the method of the present invention.
• FIG. 2 is a diagram for explaining the flow of processing in the embodiment, and FIG.
• FIG. 4 is a process chart showing an outline of an example of a conventional method.
• the material of the ceramic porous body used in the present invention includes nitrides such as silicon nitride, aluminum nitride, and boron nitride, silicon carbide, chromium carbide, and carbonized carbon.
• Carbides such as boron, borides such as titanium diboride and zirconia diboride, oxides such as alumina, zirconium andFNe, carbonitrides and acids Includes nitrides, composite oxides, etc.
• the porous body is formed by molding a powder of the above-mentioned material by a known molding method such as uniaxial pressing, cIp, m-injection molding, injection molding, etc., and then, if necessary, performs resin and pre-sintering.
• This porous body is heated to about 1350 ° C in an atmosphere containing a nitriding gas to form a metal silicon powder, like a reaction-sintered silicon nitride. It may be converted to silicon nitride.
• a nitriding gas like a reaction-sintered silicon nitride. It may be converted to silicon nitride.
• -New functions to be added to sintered ceramic porous bodies are provided for the purpose of, for example, compensating for the defects of the sintered bodies or providing different properties. Depending on the type of binder used, heat resistance, abrasion resistance, impact resistance, toughness, etc., and corrosion resistance to specific materials are enhanced.
• Precursors that are converted into ceramic films by heating include aggregates of ceramic particles such as metal oxides, nitrides, carbides, borides, and the like, or polysilicon. Includes metal polymers such as lan, polycarbosilane, polysilazane, and metal alkoxide hydrolysis products. From these, a precursor that is converted into a ceramic film having desired characteristics is selected.
• the aggregates of the ceramic particles include, for example, powders of corresponding materials as precursors of stabilized zirconium, titanium nitride, chromium carbide, and titanium diboride films. Can be used.
• a metal polymer for example, polysilylene styrene or polycarbonate silane can be used as a precursor of silicon carbide.
• Inorganic polysilazane can be used as a precursor of silicon nitride, and polymethylsilazane can be used as a precursor of a composite of silicon carbide and silicon nitride.
• a hydrolysis reaction product of a metal alcohol for example, when water is added to an ethanol solution of tetraethoxysilane, hydrolysis and polycondensation reaction occur.
• Po Li-mer is formed containing an OC z H 5 or a OH.
• This metal polymer can be used as a precursor of silica.
• a composite ceramic film may be produced by mixing different types of precursors.
• a known method for example, JP-A-63-173675 is applied to apply this precursor to the surface of a porous ceramic material.
• the application method may be spraying, brushing, dipping, or the like.
• it is necessary to make the precursor liquid or paste beforehand.
• ceramic powder it is necessary to preliminarily have a process of dispersing in a liquid to form a dispersion.
• the dispersion liquid reacts with water, alcohols such as methanol, ethanol, and isopropanol, and precursors that are converted to ceramic films such as acetone. Anything that can be volatilized without volatilization may be used.
• the organic by-Nda amount good c dispersant even in the pace preparative like increase is O Ray phosphate, glyceryl Li down bets the Rio is milled by wet one preparative and base Nze emission scan Ruch O phosphate, ⁇ I O Organic dispersants, anionic dispersants, positive ion dispersants, and amphoteric ion dispersants.
• ⁇ Organic binders include polyvinyl alcohol and polydisperse. Vinyl butyral, methyl cellulose, cellulose, cellulose, cellulose, cellulose, wax, wax, acrylic India-Low molecular weight polyethylene, etc. In the case of a metal polymer that is solid at room temperature, it can be applied as a liquid by dissolving it in a solvent.
• the thickness of the precursor layer to be converted into a ceramic film varies depending on the functions required of the ceramic film, but is usually about 10 to 500 liters in dry thickness. This layer thickness can be adjusted by the concentration of the precursor of the liquid to be applied, and if necessary, the coating and drying may be repeated to apply the coating again.Also, the precursor to be converted into a ceramic film
• the layer is not limited to one debris but may be a plurality of debris.
• Drying after application may be air drying, and may be performed by heating, May go. Needless to say, when an organic binder is added and a film is formed by utilizing its thermal decomposition, the organic binder must be heated to a temperature at which the organic binder can be thermally decomposed.
• the precursor that is converted into a gas-impermeable membrane used in the present invention is an aggregate of particles, which is softened by heating to block pores between grains, and to a film that does not substantially pass gas.
• various glass powders can be used.
• glass materials include quartz glass, glass with high calcium acid, glass with borosilicate, aluminum silicate glass, and soda quartz glass. Quartz glass softens at 1550 ⁇ : 1650. High-silicate glass softens at about 1500. Aluminosilicate glass softens at 900-950. Boric acid glass softens at 800-850.
• This glass powder may be a powder obtained by adding a refractory metal or ceramic powder to the glass to increase the softening temperature. For example, it can be converted into a highly viscous polishing liquid that contains crystal grains when heated as a mixed powder of ceramics such as Italy, aluminum, and silica. Good.
• a known method can be applied in the same manner as the above-described precursor to be converted to a ceramic film.
• the coating thickness may be sufficient to seal the HIP porous body with gas, and usually 50 to 1000 jrai in dry thickness.
• a precursor for ceramic film and a precursor for capsule are formed on the porous body, but additional films for other purposes are added.
• additional films for other purposes are added.
• a layer that prevents a strong bond between the two layers caused by heating may be sandwiched.
• a precursor for encapsulation of a high-silicate glass powder on a precursor for a ceramic film of silicon nitride powder Separate layers of boron nitride powder are formed on both layers.
• the heating temperature is the temperature at which the precursor that converts to a gas impermeable membrane is converted to an impermeable membrane. This temperature is set to a value equal to or higher than the degree of the hood where gas generation is terminated when the precursor that is converted to a ceramic film is accompanied by gas generation due to thermal decomposition. Before converting to a thick film, the softening point must be selected so that it does not flow down at the temperature at which the densification of the B-body proceeds. Heating up to the formation of an impermeable film is preferably performed in an atmosphere of an inert gas such as argon gas or nitrogen gas or under vacuum suction.
• an inert gas such as argon gas or nitrogen gas or under vacuum suction.
• the porous body may be heated in air.
• the heating of the porous body may be performed in an inert gas atmosphere or under vacuum suction.
• the heating step can be performed in a HIP device. It is not preferable to perform the heating process under high pressure, and the pressure when performing the pressurization is suitably 10 kg / cm z (gauge pressure) or less.
• the heating time is determined to be necessary to form a gas-impermeable membrane, and varies depending on the dimensions of the porous body, the degree of heating, the type of precursor, etc., but is usually about 0.5 to 3 hours. is there.
• the step of forming the gas impermeable membrane can be performed separately from the HIP processing apparatus, but it is convenient to perform it as a pre-process in the HIP apparatus.
• HIP is applied by a known method.
• the temperature used is usually about 1000 to 2300, the pressure is about 1000 to 3000 atm, and the holding time is about 0.5 to 3 hours.
• the pressurizing medium may be argon, nitrogen, or the like.
• the gas-impermeable membrane may be formed according to a known method. For example, it can be used for sand blasting, applying impact, brushing, and dropping.
• waste made of materials that are difficult to sinter or that have low strength even after sintering are interposed.
• boron nitride is effective for this purpose.
• a precursor layer that converts to a ceramic film is formed on the surface of the porous body, and a precursor layer that converts to a gas-impermeable film is formed, and the gas-impermeable layer is formed.
• Fig. 2 shows the processing flow common to the four examples.
• Three types of coating layers are formed on the surface of the porous body5, the first layer consisting of a precursor that converts to a ceramic film, and the second layer nitriding to facilitate removal of the third layer.
• the third layer consists of a precursor that converts to a gas impermeable membrane. After converting the third layer into a gas-impermeable membrane, HIP is applied to densify the porous body and the first layer. Next, the second layer and the third eyebrow are opened to obtain a sintered body having a ceramic film.
• the porous body thus obtained was charged into an HI ⁇ apparatus and subjected to HI ⁇ treatment under HI ⁇ processing conditions shown in FIG.
• the solid line represents temperature and the dotted line represents pressure.
• the porous body was heated up to 1300 with vacuum suction, and nitrogen gas at lkg / cii (hereinafter all indicated by gauge pressure) was supplied. Then, the porous body was heated up to 1000 and kept at that temperature for 1 hour. Subsequently, gas injection was started while maintaining the pressure at 1000, and the gas pressure was increased to 1700 kg / dE. Et al., Allowed to reach 2000 kg / cm z 1700 and carried out concurrently with the step-up and heated and held for 2 hours. Thereafter, decompression and cooling were performed, and the HIP treatment was completed.
• the sintered body thus obtained had a dense titanium nitride film on the surface.
• the coating thickness was 25-30 / ra rush.
• the density of the sintered body was 99.3% of the theoretical density.
• the outer layer consisting of% Ce was formed and this was used as the first layer.
• a second layer of boron nitride and a third layer of glass of high-silicic acid were formed, and similarly subjected to HIP treatment to remove the second and third extensions.
• a sintered body (theoretical density ratio: 99.4%) was obtained with a suitable zircon your film (25-30 / m thick).
• Example 2 In the same manner as in Example 1, an eyebrow composed of 50% by weight of Cr 3 C 2 50% by weight of Si 3 N 4 and an outer layer composed of 100% by weight of Cr 3 C 2 were formed on the porous silicon nitride. This was the first layer. Furthermore, a second layer of boron nitride and a third layer of calcium silicate were formed, and the HIP treatment was applied to remove the second and third layers. A sintered body (99.2% of theoretical density) having a chromium film (25 to 30 thickness) was obtained.
• Example 1 An inner layer consisting of Example 1 50% by weight nitride Kei-containing porous body in the same hand ⁇ and Po Li Shi La styrene les emissions 46 wt% S i 3 N, 4 wt% A1 2 0 3, 93 wt% Po Li Shi la scan switch les down, which was used as a first layer to form a 7 wt% A1 2 0 3 or et ing outer layer.
• a second layer of boron nitride and a third S of silicate glass were formed, and the HIP treatment was applied to remove the second and third eyebrows.
• a sintered body (theoretical density ratio 99.6%) with a thin film of silicon carbide (25-30 jtnn thickness) was obtained. Table 1 summarizes the conditions and results of the above four examples.
• Table 1 Example 1 2 3 4 Porous body Silicon nitride
• a ceramic sintered body having on its surface a dense film of a ceramic different from the ceramic constituting the sintered body main body is extremely produced. It can be obtained efficiently in a short process.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Ceramic Engineering (AREA)
• Materials Engineering (AREA)
• Structural Engineering (AREA)
• Organic Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Manufacturing & Machinery (AREA)
• Ceramic Products (AREA)
• Compositions Of Oxide Ceramics (AREA)
• Powder Metallurgy (AREA)
• Separation Using Semi-Permeable Membranes (AREA)

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• 1989
  • 1989-04-18 JP JP1096459A patent/JPH02279575A/ja active Granted
• 1990
  • 1990-04-17 US US07/623,452 patent/US5250242A/en not_active Expired - Fee Related
  • 1990-04-17 EP EP19900905685 patent/EP0419682A4/en not_active Withdrawn
  • 1990-04-17 WO PCT/JP1990/000500 patent/WO1990012770A1/ja not_active Ceased
  • 1990-12-13 GB GB9028199A patent/GB2249495B/en not_active Expired
  • 1990-12-14 SE SE9004003A patent/SE9004003L/xx not_active Application Discontinuation

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