WO2023120371A1 - ジルコニア焼結体とその製造方法 - Google Patents

ジルコニア焼結体とその製造方法 Download PDF

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WO2023120371A1
WO2023120371A1 PCT/JP2022/046221 JP2022046221W WO2023120371A1 WO 2023120371 A1 WO2023120371 A1 WO 2023120371A1 JP 2022046221 W JP2022046221 W JP 2022046221W WO 2023120371 A1 WO2023120371 A1 WO 2023120371A1
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sintered body
zirconia
zirconia sintered
heating
yttria
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French (fr)
Japanese (ja)
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瑛 川合
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Hitachi Construction Machinery Co Ltd
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KCM Corp
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Priority to JP2023569375A priority patent/JP7475563B2/ja
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    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/48—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on zirconium or hafnium oxides, zirconates, zircon or hafnates
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
    • A61C13/00—Dental prostheses; Making same
    • A61C13/08—Artificial teeth; Making same
    • A61C13/083—Porcelain or ceramic teeth
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
    • A61C13/00—Dental prostheses; Making same
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
    • A61C13/00—Dental prostheses; Making same
    • A61C13/01—Palates or other bases or supports for the artificial teeth; Making same
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
    • A61C13/00—Dental prostheses; Making same
    • A61C13/08—Artificial teeth; Making same
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
    • A61C13/00—Dental prostheses; Making same
    • A61C13/225—Fastening prostheses in the mouth
    • A61C13/26—Dentures without palates; Partial dentures, e.g. bridges
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    • C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
    • C04B35/62605—Treating the starting powders individually or as mixtures
    • C04B35/62645—Thermal treatment of powders or mixtures thereof other than sintering
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    • C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
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    • C04B2235/3231—Refractory metal oxides, their mixed metal oxides, or oxide-forming salts thereof
    • C04B2235/3244—Zirconium oxides, zirconates, hafnium oxides, hafnates, or oxide-forming salts thereof
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Definitions

  • the present invention relates to a zirconia sintered body and its manufacturing method.
  • This application claims priority based on Japanese Patent Application No. 2021-206405 filed on December 20, 2021 and Japanese Patent Application No. 2022-142199 filed on September 7, 2022. and the entire contents of that application are incorporated herein by reference.
  • a zirconia sintered body in which a small amount of yttria (Y 2 O 3 ) is dissolved is a dental restorative material (for example, It is widely used as a biomaterial for dentures, dental prostheses, etc.
  • Patent Document 1 discloses a translucent zirconia sintered body containing more than 4.0 mol % and 6.5 mol % or less of yttria and less than 0.1 wt % of alumina. Since this zirconia sintered body has a high sintered body density and excellent translucency, it is said that it has both translucency and strength particularly suitable for dentures for anterior teeth.
  • zirconia containing 2 to 4 mol % of yttria as a stabilizer and less than 0.1 wt % of alumina as an additive has a relative density of 99.8% or more and a thickness of 1.5%.
  • a translucent zirconia sintered body characterized by a total light transmittance at 0 mm of 35% or more and a crystal grain size of 0.20 to 0.45 ⁇ m is disclosed.
  • This zirconia sintered body has a high sintered body density and strength, and is excellent in translucency, so it is said to be excellent as a fired body used as a mill blank such as a denture material or an orthodontic bracket.
  • Patent Document 3 2.5 to 3.5 mol% of yttria and 0.05 to 0.3% by weight of alumina are contained, the tetragonal crystal ratio is 90% by weight or more, and the sample thickness is 1.0 mm discloses a translucent zirconia sintered body having a light transmittance of 30% or more at a wavelength of 600 nm. It is said that this zirconia sintered body is excellent in strength and toughness, and is also excellent in hydrothermal deterioration resistance.
  • the properties required may differ depending on the type of tooth to be restored.
  • dentures for anterior teeth are required to have a predetermined strength or more and excellent translucency
  • dentures for posterior teeth are required to have excellent strength and a predetermined or more translucency. obtain. Therefore, it is desirable that the zirconia sintered body used as a dental restorative material is excellent in both strength and translucency.
  • the present invention has been made in view of the circumstances described above, and its main purpose is to provide a zirconia sintered body having excellent strength and translucency. Another object of the present invention is to provide a manufacturing method for realizing such a zirconia sintered body. Another object of the present invention is to provide a dental restorative material containing such a zirconia sintered body.
  • the present inventors investigated and found that a partially stabilized zirconia presintered body having a predetermined yttria and/or ytterbia (Yb 2 O 3 ) concentration was heated to a temperature of 1600 ° C. or higher by microwave heating.
  • zirconia firing having excellent strength and translucency that is even better than the translucency of the translucent zirconia sintered bodies disclosed in Patent Documents 1 to 3. It was found that a solid body was obtained.
  • a zirconia sintered body having excellent strength and translucency can be manufactured.
  • the heating method of the microwave heating is multimode. Thereby, heating can be performed while suppressing the generation of plasma. As a result, cracking of the zirconia sintered body is suppressed, and a zirconia sintered body having excellent strength and translucency can be produced.
  • the microwave heating is performed in an oxidizing atmosphere.
  • the zirconia sintered body can be suppressed from darkening, so that a zirconia sintered body having excellent strength and translucency as well as excellent aesthetics can be produced.
  • the microwave heating is performed in an atmosphere with an oxygen concentration of 30 vol% or more and 100 vol% or less.
  • the zirconia sintered body can be effectively prevented from darkening, so that a zirconia sintered body having excellent aesthetics, strength, and translucency can be produced.
  • the SiC susceptors are arranged to sandwich the preliminary sintered body from both sides in a predetermined direction.
  • the sintering inside the preliminary sintered body can proceed more favorably, so that a zirconia sintered body having superior strength and translucency can be produced.
  • the zirconia may contain granular particles.
  • the shape stability of the molded product can be improved, and workability and handleability can be improved.
  • the present disclosure provides a zirconia sintered body.
  • This zirconia sintered body can be produced by any one of the production methods described above.
  • the zirconia sintered body disclosed herein contains zirconia and yttria and/or ytterbia. The ratio is 3 mol % or more and 4.4 mol % or less.
  • This zirconia sintered body has a biaxial bending strength of 800 MPa or more measured according to JIS T 6526, and a total light transmittance of 44.5 for a D65 light source in the thickness direction of a 1 mm thick test piece. % or more.
  • This zirconia sintered body achieves excellent strength and translucency.
  • the zirconia sintered body further contains alumina, and the proportion of the alumina is 0.15% by mass or less when the entire zirconia sintered body is taken as 100% by mass.
  • the present disclosure also provides a dental restorative material containing the zirconia sintered body disclosed herein.
  • the zirconia sintered body disclosed herein is excellent in strength and translucency, and therefore can be suitably used as a dental restorative material.
  • FIG. 1 is a flow chart showing an outline of an embodiment of a method for producing a zirconia sintered body.
  • FIG. 2 is a schematic diagram showing an example of a method of microwave heating a pre-sintered body.
  • the zirconia sintered body disclosed here contains at least zirconia (ZrO 2 ) and at least one of yttria (Y 2 O 3 ) and ytterbia (Yb 2 O 3 ). That is, the zirconia sintered body disclosed herein has a mode containing both yttria and ytterbia, a mode containing yttria but not containing ytterbia, and a mode containing ytterbia but not containing yttria.
  • a zirconia sintered body contains zirconia as a main component.
  • "containing zirconia as a main component” means that zirconia accounts for the largest proportion of the compounds constituting the zirconia sintered body.
  • the proportion of zirconia is, for example, 70% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and may be 95% by mass or more.
  • a high proportion of zirconia improves the strength and toughness of the zirconia sintered body.
  • the yttria and/or ytterbia contained in the zirconia sintered body is typically contained as a stabilizer, and is contained as at least part of the partially stabilized zirconia partially dissolved in the zirconia.
  • Zirconia typically has one of the monoclinic, tetragonal, and cubic crystal phases. Partially stabilized zirconia has a higher proportion of tetragonal crystals at room temperature, resulting in improved strength and toughness. do. In addition, partially stabilized zirconia suppresses variations in the crystal phase, thereby improving translucency.
  • the proportion of yttria and/or ytterbia is 3 mol%.
  • 4.4 mol % or more and may be, for example, 3 mol % or more and 4.2 mol % or less, 3.5 mol % or more and 4.2 mol % or less, or 3.5 mol % or more and 4 mol % or less. With such a ratio, the balance of the crystal phases of zirconia can be suitably adjusted, and both excellent strength and translucency can be achieved.
  • the proportion of yttria and/or ytterbia may be 3 mol % or more and 3.5 mol % or less, or 3 mol % or more and less than 3.5 mol %.
  • translucency is generally low, but the zirconia sintered body disclosed herein can achieve excellent translucency.
  • yttria and/or ytterbia may all dissolve in zirconia, or may contain yttria and/or ytterbia in a solid solution state that does not dissolve in zirconia.
  • the zirconia sintered body may further contain alumina (Al 2 O 3 ). Abnormal grain growth is suppressed in the zirconia sintered body containing alumina, so that the strength and translucency of the zirconia sintered body can be improved. In addition, since the low-temperature deterioration resistance is improved, the strength and translucency of the zirconia sintered body can be maintained for a long period of time. On the other hand, since alumina remains as an impurity inside the sintered body and acts as a light scattering factor, the alumina content should not be too high.
  • the content of alumina is preferably 0.15% by mass or less, preferably 0.125% by mass or less, for example, 0.1% by mass, when the entire zirconia sintered body is 100% by mass. Below, it may be 0.05 mass % or less.
  • the zirconia sintered body may contain a conventionally known coloring agent to the extent that the strength and translucency are not significantly impaired.
  • coloring agents include transition metal elements and lanthanoid rare earth elements. Examples of such elements include iron, nickel, cobalt, manganese, niobium, praseodymium, neodymium, europium, gadolinium, and erbium.
  • the coloring agent may be, for example, 2% by mass or less, 1% by mass or less, or 0.5% by mass or less with respect to the entire zirconia sintered body.
  • the zirconia sintered body may contain elements that can be unavoidably mixed. Examples include hafnium, magnesium, silicon and titanium. The total content of these elements is preferably 2.5% by mass or less, more preferably 2% by mass or less, for example 1.8% by mass or less in terms of oxides.
  • FIG. 1 is a flow chart showing an overview of the method for producing a zirconia sintered body.
  • the method for producing a zirconia sintered body disclosed here includes a compact preparation step S10 of preparing a compact containing zirconia and yttria and/or ytterbia, and heating the compact to obtain a preliminary sintered body. It may include a heating step S20 and a second heating step S30 of heating the temporary sintered body by microwave heating to obtain a zirconia sintered body.
  • the molded body preparation step S10 includes preparing a material (hereinafter also referred to as a "molded body material”) that constitutes the molded body (hereinafter also referred to as a "molded body material preparation step”) and molding the molded body material ( hereinafter also referred to as “forming step”).
  • a material hereinafter also referred to as a "molded body material”
  • molded body material preparation step a material that constitutes the molded body
  • forming step hereinafter also referred to as “forming step”.
  • the zirconia raw material is prepared.
  • Zirconia raw materials are not particularly limited, but for example, zirconium salts or hydrates thereof can be used.
  • Zirconium salts include, for example, zirconium oxychloride, zirconium chloride, zirconium sulfate, and zirconium nitrate. These may be used individually by 1 type, and may use 2 or more types together.
  • a zirconia sol is prepared by preparing an aqueous solution of zirconia raw materials and performing a hydrolysis reaction.
  • the hydrolysis reaction can be carried out by adding an alkali metal hydroxide, an alkaline earth metal hydroxide, an aqueous ammonia solution, or the like to such an aqueous solution.
  • alkali metal hydroxides that can be used include lithium hydroxide, sodium hydroxide, potassium hydroxide, etc.
  • alkaline earth metal hydroxides that can be used include magnesium hydroxide, calcium hydroxide, and the like. be able to.
  • yttria and/or ytterbia or raw materials thereof are added (or mixed) to the zirconia sol (ZrO 2 ⁇ nH 2 O) obtained by hydrolysis.
  • the source of yttria is a yttrium-containing compound that can be converted to yttria by firing.
  • yttrium-containing compounds include yttrium chloride and yttrium nitrate.
  • the raw material of ytterbium may be a ytterbium-containing compound that can be turned into ytterbia by firing.
  • Examples of ytterbium-containing compounds include ytterbium chloride and ytterbium nitrate.
  • the ratio of yttria and/or ytterbia to be added is the same as the ratio of yttria and/or ytterbia in the zirconia sintered body described above.
  • the ratio of yttria and/or ytterbia is 3 mol% or more and 4.4 mol% or less, for example, 3 mol% or more and 4.4 mol% or less, when the total of zirconia added and yttria and/or ytterbia added is 100 mol%.
  • the proportion of yttria and/or ytterbia may be 3 mol % or more and 3.5 mol % or less, or 3 mol % or more and less than 3.5 mol %.
  • the ratio of yttria and/or ytterbia described above can be the ratio of yttria and/or ytterbia in the compact described later.
  • the zirconia sol when the zirconia sol is mixed with the yttria raw material and/or the ytterbia raw material, the amount of yttria and/or ytterbia obtained by firing these raw materials falls within the range of the ratio of yttria and/or ytterbia described above. You should do it like this.
  • yttrium chloride YCl 3
  • X mol X is a positive number
  • yttria raw material 0.5 X mol of yttria (Y 2 O 3 ) can be obtained.
  • yttrium chloride should be mixed so that the amount of substance is doubled.
  • a dry powder in which the raw materials are uniformly dispersed can be obtained.
  • the drying method is not particularly limited, and for example, natural drying, air drying, hot air drying, drying by heating using a heating furnace, vacuum drying, suction drying, freeze drying, etc. can be appropriately selected.
  • calcined powder containing yttria and/or ytterbia partially stabilized zirconia can be obtained.
  • the calcination temperature is not particularly limited, but can be, for example, 800°C to 1200°C, preferably 1000°C to 1200°C.
  • the yttria raw material can be oxidized to yttria and the ytterbia raw material can be oxidized to ytterbia by such calcination.
  • a conventionally known heating device can be used as a heating device for calcination, and examples of the heating device include an electric furnace, a muffle furnace, a tunnel heating furnace, a microwave firing furnace, and the like.
  • the pulverization method is not particularly limited, and for example, pulverization can be performed using a known pulverizer (eg, ball mill, etc.).
  • a known pulverizer eg, ball mill, etc.
  • the ball mill it is preferable to use, for example, zirconia balls having a diameter of about 0.1 mm to 5 mm.
  • the powder after pulverization is sorted into a desired particle size.
  • a zirconia powder having a desired particle size can be obtained by using a mesh sieve, and the size of the opening of the mesh may be appropriately selected according to the desired particle size.
  • a preferred average particle size of the zirconia powder used as the material for the molded body is, for example, 100 nm to 300 nm, more preferably 150 nm to 200 nm. With an average particle size within this range, sinterability is high, and strength and translucency can be improved.
  • the term "average particle size" refers to a particle size ( D50 ) corresponding to a cumulative 50% from the fine particle side in a volume-based particle size distribution measured by a laser diffraction/light scattering method. say. For such measurement, for example, a particle size distribution analyzer LA950V2 (manufactured by HORIBA, Ltd.) can be used.
  • the zirconia powder produced as described above mainly contains yttria and/or ytterbia partially stabilized zirconia particles.
  • the proportion of the yttria and/or ytterbia partially stabilized zirconia particles in the zirconia powder is 50 number % or more, preferably 60 number % or more, 70 number % or more, 80 number % or more, 90 number % or more, 95 number % or more. It can be number % or more.
  • the zirconia powder may contain fully stabilized zirconia.
  • the zirconia powder may contain zirconia particles in which yttria and/or ytterbia are not solid-dissolved. Additionally, the zirconia powder may contain yttria and/or ytterbia particles.
  • zirconia powder can be obtained as a compact material, but the compact material is not limited to such zirconia powder.
  • an aluminum compound may be mixed with the zirconia powder.
  • the aluminum compound can be oxidized to alumina by heating in the first heating step S20 and/or the second heating step S30. Therefore, assuming that all of the aluminum contained in the aluminum compound is oxidized to alumina, the amount of the aluminum compound to be mixed may be determined so as to match the content of alumina in the zirconia sintered body described above.
  • the aluminum compound alumina powder, alumina sol, hydrated alumina, aluminum hydroxide, aluminum chloride, aluminum nitrate, aluminum sulfate and the like can be used.
  • a zirconia powder in which the aluminum compound is suitably dispersed can be obtained by drying the slurry.
  • the average particle size of the aluminum compound is preferably about the same as or smaller than that of the zirconia powder.
  • the average particle diameter of the aluminum compound is, for example, preferably 300 nm or less, more preferably 200 nm or less, and may be 150 nm or less and 100 nm or less (eg, 20 nm to 50 nm).
  • the aluminum compound can be suitably dispersed in the zirconia powder. Therefore, alumina can be distributed more uniformly in the zirconia sintered body, and abnormal grain growth in the zirconia sintered body can be suitably suppressed.
  • the molding material can be suitably used not only in the form of powder but also in the form of granules.
  • the average particle size of the granular molding material can be, for example, 10 ⁇ m to 100 ⁇ m, 20 ⁇ m to 90 ⁇ m, 40 ⁇ m to 80 ⁇ m. By making it granular, shape stability can be improved, and handleability and workability can be improved. In addition, since the residual stress during molding is relaxed, the generation of hot spots due to the difference in powder density during microwave heating can be suppressed.
  • a zirconia sintered body is obtained by heating with microwaves, even granules having an average particle size larger than that of powder can be suitably heated to the inside of the granules. As a result, a zirconia sintered body having excellent strength and translucency can be produced.
  • the method for producing the granular compact material is not particularly limited, but for example, it can be produced by spray drying zirconia powder.
  • zirconia powder may contain an aluminum compound and may further contain a binder.
  • the binder may be a component that burns through at the heating temperature of the first heating step or the second heating step, which will be described later.
  • binders include acrylic resins, epoxy resins, phenol resins, amine resins, alkyd resins, and cellulose polymers. Among them, it is preferable to contain an acrylic resin. By containing the acrylic resin, the adhesion between the zirconia powders is enhanced, and zirconia granules can be suitably produced. In addition, the shape stability of the molded body is enhanced, and the molded body can be stably held.
  • acrylic resin a polymer containing an alkyl (meth)acrylate as a main monomer (a component that accounts for 50% by mass or more of the total monomer), or a sub-monomer having copolymerizability between the main monomer and the main monomer.
  • the content of the binder is, for example, 10% by mass or less, preferably 5% by mass or less, when the entire powder used for spray drying is taken as 100% by mass. Also, if the amount of binder is too small, the effect of the binder may be insufficient. Therefore, the content of the binder may be, for example, 0.5% by mass or more, and may be 1% by mass or more.
  • the method of molding the molded material is not particularly limited, and for example, pressure molding, injection molding, extrusion molding, casting molding, etc. can be employed.
  • pressure molding for example, cold isostatic pressing (CIP), hot isostatic pressing (HIP), and the like are preferably employed.
  • CIP or HIP a compact having high homogeneity and high density can be produced.
  • first heating step S20 the compact is preliminarily sintered by heating the compact to obtain a preliminarily sintered compact.
  • Such heating can remove components such as moisture, binders, and impurities that may be contained in the compact.
  • pre-sintering can reduce voids that may exist in the molded body, thereby preventing cracks that may occur during sintering by heating at a higher temperature and at a higher speed.
  • Temporary sintering can be performed at a heating temperature of, for example, 800°C to 1200°C, preferably 1000°C to 1100°C. The time for preliminary sintering may vary depending on the shape, size, composition, etc. of the compact, and may be adjusted as appropriate.
  • Heating for temporary sintering can be performed by a known method, and for example, a heating device such as a muffle furnace, an electric furnace, or a microwave firing furnace can be used.
  • the rate of temperature increase in the heating in the first heating step S20 is not particularly limited. ) can be 50° C./h to 150° C./h. As a result, rapid sintering can be prevented, and the occurrence of cracks can be suppressed.
  • the temporary sintered body obtained in the first heating step S20 is sintered by microwave heating to obtain a zirconia sintered body.
  • microwave heating the inner side of the pre-sintered body can be rapidly heated, so the difference between the progress of sintering on the surface side of the pre-sintered body and the progress of sintering on the inner side is small.
  • voids inside the zirconia sintered body can be further reduced. Thereby, the strength and translucency of the zirconia sintered body can be improved.
  • An embodiment of the second heating step S30 will be described below with reference to the drawings.
  • the method of microwave heating is not limited to the following examples.
  • FIG. 2 is a schematic diagram showing an example of a method of microwave heating a pre-sintered body. Note that the dimensional relationships (length, width, thickness, etc.) in FIG. 2 do not reflect the actual dimensional relationships.
  • the directions of up, down, left, and right are indicated by arrows U, D, L, and R, respectively, in the figure.
  • the orientations of up, down, left, and right are merely defined for convenience of explanation, and do not limit the installation form.
  • the microwave heating device 10 has a partition wall 12 and a heating space 14 .
  • a heat-insulating container 20 is installed in the heating space 14 , and a susceptor 40 and a presintered body 50 are housed in a housing space 22 of the heat-insulating container 20 .
  • a gas supplier 30 is connected to the accommodation space 22 of the heat insulating container 20 .
  • the radiation thermometer 60 is installed at a remote position outside the microwave heating device 10 .
  • the microwave heating device 10 has a heating space 14 surrounded by partition walls 12 .
  • the heating space 14 is a space that accommodates an object to be heated by microwaves.
  • the side wall, ceiling and/or bottom wall of the heating space 14 has a microwave irradiating part, and the object housed in the heating space 14 can be irradiated with microwaves and heated.
  • the microwave may have a frequency conventionally used for microwave heating, and for example, a microwave with a frequency of 0.3 GHz to 3 GHz (eg, 2.45 GHz) can be used.
  • the partition wall 12 insulates the heating space 14 of the microwave heating device 10 from the outside, and commercially available microwave devices can be used.
  • the heating space 14 side of the partition wall 12 may be lined with a heat insulating material.
  • the partition wall 12 is provided with a through hole 16 for measuring the temperature of the object in the heating space 14 .
  • the through hole 16 penetrates so as to connect the heating space 14 and the outside of the microwave heating device 10 .
  • a transparent heat-resistant member for example, quartz glass
  • the microwave heating device 10 having such a configuration, for example, ⁇ -Reactor EX or ⁇ -Reactor Mx manufactured by Shikoku Keisoku Kogyo Co., Ltd. can be used.
  • the heat insulating container 20 has an accommodation space 22 capable of accommodating the susceptor 40 and the preliminary sintered body 50 therein.
  • the heat-insulating container 20 communicates the storage space 22 and the heating space 14 with a gas introduction hole 24 for connecting the storage space 22 and the gas supplier 30 . It has a gas exhaust hole 26 and a through hole 28 for measuring the temperature of the object to be heated in the housing space 22 .
  • the heat-insulating container 20 is a rectangular parallelepiped box-shaped container, but its shape is not particularly limited, and may be cylindrical, prismatic, or the like, for example.
  • the heat insulating container 20 is designed to be separable into a lid portion and a case portion, so that an object to be heated can be easily taken in and out of the accommodation space 22. Designed. Ceramic fibers such as alumina-silica fibers, for example, can be used as the material of the heat-insulating container 20 .
  • the gas introduction hole 24 is a through hole that communicates the housing space 22 and the heating space 14, and is designed so that a pump 32 connected to the gas supplier 30 can be inserted. Thereby, a desired gas can be supplied to the accommodation space 22 and the atmosphere in the accommodation space 22 can be controlled.
  • the gas discharge hole 26 is a through hole that communicates the accommodation space 22 and the heating space 14, and is designed so that the accommodation space 22 is not sealed. As a result, as the firing of the temporary sintered body 50 progresses, the oxygen in the accommodation space 22 is consumed, and it is possible to prevent the accommodation space 22 from becoming a reducing atmosphere. Also, the gas discharge hole 26 can prevent the gas supplied from the gas introduction hole 24 from remaining in the housing space 22 . Although one gas discharge hole 26 is provided in FIG. 2, a plurality (two or more) thereof may be provided. Moreover, in this embodiment, the gas discharge hole 26 is provided in the wall facing the wall in which the gas introduction hole 24 is provided, but the position of the gas discharge hole 26 is not particularly limited. Although the diameter of the gas discharge hole 26 is not particularly limited, it can be, for example, about 5 mm to 50 mm, or for example, about 5 mm to 20 mm.
  • a through-hole 28 is provided on the upper side of the heat-insulated container 20 to allow the accommodation space 22 and the heating space 14 to communicate with each other. Further, the through holes 28 and the through holes 16 of the microwave heating device 10 are arranged in a straight line. Thereby, the temperature of the object to be heated arranged in the housing space 22 can be measured by the radiation thermometer 60 installed outside the microwave heating device 10 .
  • the through-hole 28 is not particularly limited as long as it is provided with a size that allows the temperature of the object to be heated to be measured by the radiation thermometer 60.
  • the diameter of the through-hole 28 is about 5 mm to 10 mm. be able to.
  • the gas discharge hole 26 and the through hole 28 are respectively provided. Therefore, a configuration in which only one of them is provided may be used.
  • the gas supplier 30 can supply a desired gas to the accommodation space 22 of the heat insulating container 20 via the pump 32 to adjust the atmosphere of the accommodation space 22 .
  • the gas supplier 30 can be appropriately changed according to the desired gas, and a commercially available gas supplier (for example, an oxygen supplier) can be used without particular limitation.
  • a blower or the like may be employed as the gas supply device 30 .
  • microwave heating is preferably performed in an oxidizing atmosphere.
  • the oxidizing atmosphere include an air atmosphere and an atmosphere having a higher oxygen concentration than the air atmosphere.
  • the oxygen concentration is preferably 30 vol% or higher, and may be, for example, 50 vol% or higher, or 70 vol% or higher. Under such an oxidizing atmosphere, darkening of the zirconia sintered body can be further suppressed.
  • the upper limit of the oxygen concentration in the atmosphere is not particularly limited, and the oxygen concentration can be 100 vol % or less.
  • the oxygen concentration is, for example, preferably 95 vol% or less, more preferably 90 vol% or less. Note that such control to an oxidizing atmosphere may be performed in the accommodation space 22 of the heat insulating container 20 in which the presintered body 50 is installed.
  • the temporary sintered body 50 in order to control the oxidizing atmosphere, it is preferable to continue to supply the air or the gas containing the oxygen concentration to the accommodation space 22 (more specifically, the temporary sintered body 50). .
  • the air or the gas containing the oxygen concentration to the accommodation space 22 (more specifically, the temporary sintered body 50).
  • the gas supplied from the gas supplier 30 is discharged from the gas discharge hole 26 and/or the through hole 28 after flowing into the housing space 22 .
  • the susceptor 40 is a heating auxiliary member that can increase the efficiency of microwave heating by efficiently converting microwave energy into thermal energy. Specifically, since the susceptor 40 absorbs microwaves, the temperature of the susceptor 40 rises faster than that of the presintered body 50 , so heat conduction can assist the temperature rise of the presintered body 50 . When the pre-sintered body 50 reaches a high temperature, the pre-sintered body 50 itself easily absorbs microwaves and can behave as a microwave absorber. When the temporary sintered body 50 easily absorbs microwaves, the internal heating mechanism of the temporary sintered body 50 is easily accelerated by microwave heating. As a result, sintering of the interior of the preliminary sintered body 50 is promoted, voids are less likely to remain therein, and a zirconia sintered body having excellent strength and translucency can be produced.
  • the susceptors 40 be arranged so as to sandwich the pre-sintered body 50 from both sides in a predetermined direction.
  • the susceptors 40 are arranged on both sides (that is, upper and lower sides) of the temporary sintered body 50 in the vertical direction (vertical direction), or arranged on both sides of the temporary sintered body 50 in at least one horizontal direction. aspect etc. are mentioned.
  • both surfaces of the presintered body 50 in the predetermined direction are heated by the susceptor 40, so that the microwave absorption efficiency of the presintered body 50 can be increased in a shorter time.
  • the internal heating of the temporary sintered body 50 by microwave heating can be realized in a shorter time, so that a zirconia sintered body with reduced internal voids and excellent strength and translucency can be produced. can be done.
  • the susceptor 40 is typically placed in contact with the surface of the preliminary sintered body 50, but there may be a gap between the susceptor 40 and the surface of the preliminary sintered body 50. . Although such a gap is not particularly limited, it is preferably 3 mm or less, more preferably 2 mm or less, and still more preferably 1 mm or less.
  • the temporary sintered body 50 is not sealed by the susceptor 40 .
  • the temporary sintered body 50 is not sealed by the susceptor 40, oxygen around the temporary sintered body 50 can be prevented from being consumed and becoming a reducing atmosphere.
  • the susceptors 40 are not installed (open) on both sides in at least one direction different from the predetermined direction in which the susceptors 40 are arranged. This makes it easier for the microwaves to be directly absorbed by the preliminary sintered body 50, so that internal heating can be induced more uniformly from a lower temperature range.
  • the pre-sintered body 50 can be placed in the flow of gas supplied from the gas supplier 30, so that the surroundings of the pre-sintered body 50 The atmosphere can be better controlled.
  • the preliminary sintered body 50 is vertically sandwiched between two plate-shaped susceptors 40, and the preliminary sintered body 50 is covered with the susceptors 40 in the horizontal direction.
  • the susceptor 40 is not arranged in any horizontal direction of the temporary sintered body 50, microwaves are particularly easily absorbed by the temporary sintered body 50, and zirconia is excellent in strength and translucency. It becomes easy to manufacture a sintered compact.
  • a SiC susceptor whose main component is silicon carbide (SiC) is preferably employed as the susceptor 40 .
  • SiC silicon carbide
  • “mainly composed of SiC” means that SiC accounts for 50% by mass or more in the compound that constitutes the susceptor 40 .
  • Examples of SiC susceptors include single-crystal SiC, recrystallized SiC, reaction-sintered SiC, nitride-bonded SiC, oxide-bonded SiC, and silicon carbide fibers.
  • recrystallized SiC and silicon carbide fibers which are materials with relatively high porosity, can be preferably used.
  • recrystallized SiC is particularly preferable because it has excellent heat resistance.
  • the porosity of recrystallized SiC may be, for example, 10% to 90%, preferably 10% to 10%. 30%.
  • the porosity can be measured by a conventionally known method, for example, a mercury intrusion method.
  • the thickness of one sheet is preferably 1 mm to 4 mm, more preferably 2 mm to 3 mm. If the susceptor 40 is too thin, the strength of the susceptor can be reduced. Also, if the susceptor 40 is too thick, it is difficult to heat the susceptor 40, resulting in a slow temperature rise rate. Therefore, the strength of the susceptor 40 and the rate of temperature increase of the susceptor 40 are well balanced within the above thickness range. As a result, a zirconia sintered body having excellent strength and translucency can be more suitably produced.
  • one plate-shaped susceptor 40 is arranged above and below the preliminary sintered body 50, but in the case of the plate-shaped susceptor 40, if there are a plurality (two or more) of them,
  • the number is not particularly limited.
  • two or more susceptors 40 may be stacked on each of the upper side and the lower side of the preliminary sintered body 50 .
  • different numbers of susceptors 40 may be used above and below the temporary sintered body 50 .
  • the susceptor 40 is plate-shaped in this embodiment, the susceptor 40 is not particularly limited as long as it is arranged on both sides of the pre-sintered body 50 in a predetermined direction.
  • a box-shaped (for example, hexahedral) susceptor having through holes provided on a pair of opposing surfaces, a column-shaped susceptor (for example, a cylindrical or prismatic shape) can be used.
  • the radiation thermometer 60 can measure the temperature of an object without contact. As shown in FIG. 2, in this embodiment, the radiation thermometer 60 is installed at a position separate from the microwave heating device 10, and measures the surface temperature of the susceptor 40 above the preliminary sintered body 50. there is In this specification, the heating temperature in the microwave heating in the second heating step S30 refers to the temperature measured by the radiation thermometer 60. From the viewpoint of measuring the temperature change due to microwave heating more accurately, it is preferable to fix the radiation thermometer 60 at a predetermined position with a clamp or the like. As the radiation thermometer 60, for example, an OPTCTRF1MHSFVFC3 sensor manufactured by Optris (pseudo emissivity setting 1.0) can be used.
  • Microwave heating is, for example, preferably 1600° C. or higher (e.g., higher than 1600° C.), preferably 1620° C. or higher, more preferably 1650° C. or higher, further preferably 1700° C. or higher (e.g., higher than 1700° C.), and 1720° C.
  • the above are particularly preferred.
  • the mechanism is not particularly limited, it is estimated that by setting the microwave heating temperature to a high temperature of 1600 ° C or higher, the zirconia sintered body has a higher proportion of tetragonal crystals in the crystal phase, so that the strength is improved. be done.
  • the discontinuity of grain boundaries can be reduced by reducing variations in the crystal phase.
  • the microwave heating is suitable, for example, at 2000 ° C. or less, and for example, 1900 ° C. or less, 1800 ° C. or less, 1750 ° C. ° C. or lower and 1730 ° C. or lower.
  • the microwave heating can be 1600°C to 2000°C, preferably 1620°C to 1800°C, 1650°C to 1730°C.
  • the holding time of microwave heating is appropriately changed depending on the shape, size, composition, etc. of the preliminary sintered body 50, but can be, for example, about 1 minute to 20 minutes, or, for example, about 1 minute to 10 minutes. .
  • the holding time here does not include the heating time until reaching the micro-heating temperature.
  • the heating method of microwave heating is not particularly limited, and for example, both single mode and multimode can be used, but multimode is preferably adopted.
  • the single mode depending on the arrangement position, size, etc. of the temporary sintered body 50, plasma may be generated in the temporary sintered body 50, and cracks may occur in the zirconia sintered body.
  • the multimode concentration of the electromagnetic field in the heating space 14 is suppressed, so plasma is less likely to occur. This suppresses the occurrence of cracks in the zirconia sintered body, making it easier to manufacture a zirconia sintered body having excellent strength and translucency.
  • the temperature increase rate of microwave heating is not particularly limited because it is appropriately changed depending on the shape, size, composition, etc. of the temporary sintered body. It is preferably 500° C./min to 900° C./min. Thereby, a zirconia sintered body can be manufactured in a shorter time.
  • the temperature rise rate is, for example, 20°C/min to 50°C/min until the temperature reaches about 1100°C to 1200°C. This can reduce the occurrence of cracks due to rapid sintering of zirconia.
  • the temperature rise rate is, for example, 40°C/min to 60°C/min until the temperature reaches about 1600°C to 2000°C. As a result, the progress of sintering of the preliminary sintered body can be appropriately controlled, and a zirconia sintered body having higher strength and translucency can be produced.
  • the shape of the preliminary sintered body 50 is not particularly limited, but from the viewpoint of more uniform microwave sintering, it is preferably, for example, a disk shape.
  • the thickness of the temporary sintered body 50 is, for example, preferably 0.5 mm to 10 mm, more preferably 0.5 mm to 2 mm. Within this range, sintering by microwaves can be efficiently performed while maintaining the strength of the preliminary sintered body 50 .
  • the maximum diameter of the temporary sintered body 50 is, for example, preferably 10 mm to 60 mm, more preferably 10 mm to 20 mm. Within this range, sintering by microwaves can be performed more uniformly.
  • the zirconia sintered body manufactured in this way achieves excellent strength and translucency.
  • a zirconia sintered body may have a biaxial bending strength of 800 MPa or higher, preferably 850 MPa or higher, more preferably 900 MPa or higher, and even more preferably 1000 MPa or higher (eg, 1200 MPa or higher).
  • the upper limit of the biaxial bending strength is not particularly limited, but may be, for example, 1500 MPa or less, 1300 MPa or less, or 1250 MPa or less. In this specification, the biaxial bending strength is measured according to JIS T 6526.
  • the translucency of the zirconia sintered body disclosed herein is, for example, a total light transmittance of 44.5% or more, preferably 44.7% or more, more preferably 45% or more, and still more preferably 46%. or more, or even 46.5% or more.
  • the total light transmittance may be, for example, 55% or less, 51% or less.
  • total light transmittance refers to the total light transmittance for a D65 light source in the thickness direction of a disk-shaped test piece with a thickness of 1 mm.
  • the zirconia sintered body disclosed herein has both excellent strength and excellent translucency, it is suitable as a dental restorative material such as anterior dentures, posterior dentures, dental prostheses, and bridges. can be used.
  • Item 1 A method for producing a zirconia sintered body, comprising the following steps: A compact containing zirconia and yttria and/or ytterbia, wherein the proportion of yttria and/or ytterbia is 3 mol% or more when the total of zirconia and yttria and/or ytterbia is 100 mol%4 .4 mol% or less molded body preparation step of preparing a molded body, A first heating step of heating the molded body at 800° C. or higher and 1200° C.
  • a method for producing a zirconia sintered body comprising a second heating step of heating the temporary sintered body at 1600° C. or more and 2000° C. or less by microwave heating to obtain a zirconia sintered body.
  • Item 2 The method for producing a zirconia sintered body according to Item 1, wherein the heating method of the microwave heating is multimode.
  • Item 3 The method for producing a zirconia sintered body according to Item 1 or 2, wherein the microwave heating is performed in an oxidizing atmosphere.
  • Item 4 The method for producing a zirconia sintered body according to Item 3, wherein the microwave heating is performed in an atmosphere having an oxygen concentration of 30 vol% or more and 100 vol% or less.
  • Item 5 The method for producing a zirconia sintered body according to any one of Items 1 to 4, wherein in the second heating step, SiC susceptors are arranged to sandwich the temporary sintered body from both sides in a predetermined direction.
  • Item 6 The method for producing a zirconia sintered body according to any one of Items 1 to 5, wherein the zirconia contains granular particles.
  • Item 7 A zirconia sintered body containing zirconia and yttria and/or ytterbia, wherein the ratio of the yttria and/or ytterbia to the total of the zirconia and the yttria and/or ytterbia is 100 mol% is 3 mol% or more and 4.4 mol% or less,
  • the biaxial bending strength measured according to JIS T 6526 is 800 MPa or more
  • Item 8 The zirconia sintered body according to Item 7, further comprising alumina, wherein the proportion of the alumina is 0.15% by mass or less when the entire zirconia sintered body is taken as 100% by mass.
  • Item 9 A dental restorative material comprising the zirconia sintered body according to Item 7 or 8.
  • a zirconia sintered body containing zirconia and yttria and/or ytterbia wherein the zirconia and the yttria and/or Or when the total with ytterbia is 100 mol%, the ratio of the above yttria and/or ytterbia is 3 mol% or more and 3.5 mol% or less (for example, 3 mol% or more and less than 3.5 mol%).
  • the biaxial bending strength measured according to the method may be 800 MPa or more, and the total light transmittance for a D65 light source in the thickness direction of a test piece having a thickness of 1 mm may be at least 44.5% or more. Furthermore, the biaxial bending strength may be 900 MPa or higher, or 1000 MPa or higher. According to the production method disclosed herein, even if the proportion of yttria and/or ytterbia is 3.5 mol% or less, excellent total light transmittance can be achieved, and zirconia sintered with excellent strength and translucency can be a body.
  • a zirconia sintered body containing zirconia and yttria and/or ytterbia wherein the zirconia and the yttria and/or Or when the total with ytterbia is 100 mol%, the ratio of yttria and/or ytterbia is 3.5 mol% or more and 4.2 mol% or less, where the biaxial bending strength measured according to JIST 6526 is 800 MPa or more, and the total light transmittance for a D65 light source in the thickness direction of a 1 mm thick test piece can be at least 46% or more.
  • a zirconia sintered body having a ratio of yttria and/or ytterbia in the above range can realize excellent translucency, and a zirconia sintered body having excellent strength and translucency. can do.
  • Yttria was mixed with a zirconia sol produced by hydrolyzing a zirconium oxychloride solution. At this time, yttria was made to be 3 mol % with respect to the total of zirconia and yttria. After drying the mixture, it was calcined at 1200° C. for 2 hours to obtain a partially stabilized zirconia powder. This zirconia powder was pulverized with a ball mill using zirconia balls of 1 mm in diameter and screened through a mesh sieve to obtain a zirconia powder having an average particle size of 150 nm to 200 nm as a molding material.
  • This zirconia powder was filled in a disk-shaped mold, and after applying a pressure of 0.78 MPa, the molded body was removed from the mold and subjected to CIP molding at 196 MPa. After that, the obtained molded body was heated at 1100° C. for 2 hours to obtain a preliminary sintered body. The heating rate at this time was 120°C/h up to 800°C and 100°C/h up to 1100°C.
  • the pre-sintered body was placed on a plate-like SiC susceptor with a thickness of 2 mm, and the plate-like SiC susceptor with a thickness of 2 mm was placed on the pre-sintered body, and then housed in a heat insulating container.
  • the heat insulating container used had the same structure as the heat insulating container 20 shown in FIG. Then, the insulated container was installed in the microwave heating device.
  • the SiC susceptor used recrystallized SiC.
  • As the microwave heating device ⁇ -Reactor EX manufactured by Shikoku Keisoku Kogyo Co., Ltd. was used.
  • M1O2 silent manufactured by Kobe Medicare Co., Ltd.
  • M1O2 silent manufactured by Kobe Medicare Co., Ltd.
  • microwave heating was started, and the temperature was raised to 1000 ° C. at 600 ° C./min, to 1100 ° C. at 20 ° C./min, and to 1730 ° C. at 50 ° C./min. °C for 1 minute.
  • the microwave heating was stopped and the mixture was allowed to cool naturally to room temperature.
  • the microwave heating method was multimode.
  • an OPTCTRF1MHSFVFC3 sensor manufactured by Optris was used to measure the temperature of the SiC susceptor on the upper side of the preliminary sintered body.
  • Example 2 The production method of Example 1 was changed so that the yttria concentration was 3.5 mol %. Also, the calcination conditions for obtaining the partially stabilized zirconia powder were changed to 1120° C. for 4 hours. Furthermore, alumina powder having an average particle size of 30 nm was mixed with the partially stabilized zirconia powder so as to be 0.05% by mass. A zirconia sintered body of Example 2 was produced in the same manner as in Example 1 except for these.
  • Example 3 The production method of Example 1 was changed so that the yttria concentration was 4.2 mol %. Also, the calcination conditions for obtaining the partially stabilized zirconia powder were changed to 1110° C. for 4 hours. Further, the heating rate of the microwave heating was 900°C/min up to 1050°C and 40°C/min up to 1730°C. A zirconia sintered body of Example 3 was produced in the same manner as in Example 1 except for these.
  • Example 4 The production method of Example 3 was changed in that the partially stabilized zirconia powder was mixed with alumina powder having an average particle size of 30 nm so as to be 0.05% by mass. A zirconia sintered body of Example 4 was produced in the same manner as in Example 3 except for these.
  • Example 5 The production method of Example 1 was changed so that the yttria concentration was 5.0 mol %. Also, the calcination conditions for obtaining the partially stabilized zirconia powder were changed to 1120° C. for 4 hours. Furthermore, alumina powder having an average particle size of 30 nm was mixed with the partially stabilized zirconia powder so as to be 0.02% by mass. In addition, the heating rate of microwave heating was 900°C/min up to 1250°C, 5°C/min up to 1550°C, and 40°C/min up to 1730°C. A zirconia sintered body of Example 5 was produced in the same manner as in Example 1 except for these.
  • Example 6 The production method of Example 1 was changed so that the yttria concentration was 4.2 mol %. Also, the calcination conditions for obtaining the partially stabilized zirconia powder were changed to 1110° C. for 4 hours. Further, the partially stabilized zirconia powder was mixed with 0.125% by mass of alumina powder having an average particle size of 30 nm, and further mixed with 3% by mass of a polyacrylic binder as a binder. Then, the mixture was granulated by spray drying to obtain zirconia granules having an average particle size of 70 ⁇ m.
  • Example 6 Using such zirconia granules as a compact material, a pre-sintered body was obtained in the same manner as in Example 1, and then the heating rate of microwave heating was 600 ° C./min up to 1150 ° C., 20 ° C./min up to 1200 ° C., It was carried out at 40°C/min up to 1730°C.
  • a zirconia sintered body of Example 6 was produced in the same manner as in Example 1 except for these operations.
  • Example 7 The production method of Example 1 was changed so that the yttria concentration was 4.2 mol %. Also, the calcination conditions for obtaining the partially stabilized zirconia powder were changed to 1110° C. for 4 hours. Further, the heating rate of microwave heating was 900° C./min up to 1050° C. and 40° C./min up to 1650° C., and held at 1650° C. for 3 minutes. A zirconia sintered body of Example 7 was produced in the same manner as in Example 1 except for these.
  • Example 8 The production method of Example 1 was changed so that the yttria concentration was 3.5 mol %. Also, the calcination conditions for obtaining the partially stabilized zirconia powder were changed to 1110° C. for 4 hours. Furthermore, the heating rate of microwave heating was 500° C./min up to 1050° C. and 50° C./min up to 1620° C., and held at 1620° C. for 1 minute. A zirconia sintered body of Example 8 was produced in the same manner as in Example 1 except for these.
  • Yttrium chloride and ytterbium chloride were mixed with a zirconia sol produced by hydrolyzing a zirconia oxychloride solution.
  • yttrium chloride is converted to yttria
  • ytterbium chloride is converted to ytterbia
  • yttrium chloride and chloride are added so that yttria is 1.8 mol% and ytterbia is 2.4 mol% with respect to the total of zirconia, yttria, and ytterbia.
  • Ytterbium was mixed. After drying the mixture, it was calcined at 1120° C. for 4 hours to obtain a partially stabilized zirconia powder.
  • This zirconia powder was pulverized with a ball mill using zirconia balls of 1 mm in diameter and screened through a mesh sieve to obtain a zirconia powder having an average particle size of 150 nm to 200 nm as a molding material.
  • This powder was mixed with alumina powder having an average particle size of 30 nm so as to be 0.05% by mass.
  • This zirconia powder was filled in a disk-shaped mold, and after applying a pressure of 0.78 MPa, the molded body was removed from the mold and subjected to CIP molding at 196 MPa. After that, the obtained molded body was heated at 1100° C. for 2 hours to obtain a preliminary sintered body.
  • the heating rate at this time was 120°C/h up to 800°C and 100°C/h up to 1100°C. Thereafter, microwave heating was performed in the same manner as in Example 1 to obtain a zirconia sintered body of Example 9. However, the microwave heating conditions were changed to 900° C./min up to 1050° C., 40° C./min up to 1730° C., and then maintaining at 1730° C. for 1 minute.
  • Example 10 The manufacturing method of Example 9 was changed so that ytterbium chloride was mixed so that the ytterbium concentration was 4.2 mol %. Yttrium chloride was not mixed. Also, the calcination conditions for obtaining partially stabilized zirconia powder were changed to 1100° C. for 4 hours. A zirconia sintered body of Example 10 was produced in the same manner as in Example 9 except for these.
  • Example 11 The production method of Example 10 was changed so that the ytterbia concentration was 3.0 mol %. Also, the calcination conditions for obtaining the partially stabilized zirconia powder were changed to 1110° C. for 4 hours. Also, in Example 11, no alumina powder was mixed. Furthermore, the heating rate of microwave heating was changed to 600° C./min up to 1100° C. and 50° C./min up to 1700° C., and held at 1700° C. for 1 minute. A zirconia sintered body of Example 11 was produced in the same manner as in Example 10 except for these.
  • the zirconia sintered body produced in each example was processed into a disk-shaped test piece with a thickness of 1 mm, and both sides of the test piece were mirror-polished using a 0.5 ⁇ m diamond slurry as an abrasive.
  • the total light transmittance of the D65 light source was measured at .
  • a haze meter NDH4000 manufactured by Nippon Denshoku Industries was used. Table 1 shows the results.
  • Examples 1 to 11 had a total light transmittance of 44.5% or more (specifically, 44.7% or more), indicating that excellent translucency was achieved. .
  • Examples 1 to 4 and 6 to 11 have a biaxial bending strength of 800 MPa or more, demonstrating excellent strength. That is, according to the manufacturing method disclosed herein, it is possible to realize a zirconia sintered body having excellent strength (biaxial bending strength of 800 MPa or more) and translucency (total light transmittance of 44.5% or more). Recognize.
  • yttria and/or ytterbia 3 mol% or more and 3.5 mol% or less, in addition to excellent strength (biaxial bending strength of 800 MPa or more), excellent Translucency (total light transmittance of 44.5% or more) is realized.
  • a partially stabilized zirconia sintered body with a relatively low proportion of yttria sintered in a kiln or the like (for example, 3.5 mol% or less) has a high strength but a low total light transmittance. There is a trade-off relationship.
  • the zirconia sintered body disclosed herein can increase the total light transmittance even when the ratio of yttria and/or ytterbia is relatively low.
  • the zirconia sintered bodies disclosed herein excellent strength is achieved even when the proportion of yttria and/or ytterbia is relatively high.
  • the zirconia sintered body in which the proportion of yttria and/or ytterbia is 3.5 mol% or more and 4.2 mol% or less realizes a total light transmittance of 46% or more, which is particularly excellent transparency. Conceivable.
  • Example 6 it can be seen that a zirconia sintered body having excellent translucency and strength can be realized even when granular zirconia powder is used as the material for the compact.

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JP7578866B1 (ja) * 2023-06-02 2024-11-06 共立マテリアル株式会社 ジルコニア焼結体とその製造方法
WO2024247873A1 (ja) * 2023-06-02 2024-12-05 共立マテリアル株式会社 ジルコニア焼結体とその製造方法
WO2025063305A1 (ja) * 2023-09-22 2025-03-27 クラレノリタケデンタル株式会社 ジルコニア仮焼体及びその製造方法
WO2025063304A1 (ja) * 2023-09-22 2025-03-27 クラレノリタケデンタル株式会社 ジルコニア仮焼体及びその製造方法
JPWO2025063306A1 (https=) * 2023-09-22 2025-03-27

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US20070023971A1 (en) * 2004-09-01 2007-02-01 Subrata Saha Method of microwave processing ceramics and microwave hybrid heating system for same
JP2018052806A (ja) * 2016-09-21 2018-04-05 東ソー株式会社 ジルコニア焼結体及びその製造方法

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US20070023971A1 (en) * 2004-09-01 2007-02-01 Subrata Saha Method of microwave processing ceramics and microwave hybrid heating system for same
JP2018052806A (ja) * 2016-09-21 2018-04-05 東ソー株式会社 ジルコニア焼結体及びその製造方法

Cited By (6)

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Publication number Priority date Publication date Assignee Title
JP7578866B1 (ja) * 2023-06-02 2024-11-06 共立マテリアル株式会社 ジルコニア焼結体とその製造方法
WO2024247873A1 (ja) * 2023-06-02 2024-12-05 共立マテリアル株式会社 ジルコニア焼結体とその製造方法
WO2025063305A1 (ja) * 2023-09-22 2025-03-27 クラレノリタケデンタル株式会社 ジルコニア仮焼体及びその製造方法
WO2025063304A1 (ja) * 2023-09-22 2025-03-27 クラレノリタケデンタル株式会社 ジルコニア仮焼体及びその製造方法
JPWO2025063306A1 (https=) * 2023-09-22 2025-03-27
JP7791367B2 (ja) 2023-09-22 2025-12-23 クラレノリタケデンタル株式会社 ジルコニア仮焼体

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