Powder and its manufacturing method

Abstract

To provide at least one out of powders, a manufacturing method thereof, a calcined body obtained from the powders, a sintered body, and manufacturing methods for them; the powders including zirconia as a principal component and at least a transition metal element, and from which a calcined body being able to be obtained, the calcined body having mechanical characteristics more suitable for calcination processing.SOLUTION: Powders of zirconia include a stabilizing element and a transition metal element, where a difference between a minimum value and a maximum value of transition metal element / zirconium is less than 0.25 in a frequency distribution of element ratio in which the transition metal element / zirconium is plotted at 0.005 intervals.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to zirconia-based powders and methods for producing the same. [Background technology]

[0002] Zirconia (ZrO2; zirconium dioxide) sintered bodies containing coloring components are used in a wide range of applications, including mobile electronic device components, decorative materials, and dental prostheses. Zirconia sintered bodies have high strength and are difficult to process. Therefore, when obtaining sintered bodies with complex shapes, such as dental prostheses, a molded body (compacted powder) containing zirconia and coloring components is first heat-treated below the sintering temperature to obtain a zirconia body with strength suitable for processing, known as a calcined body (semi-sintered body, pre-sintered body). The calcined body is then machined into the desired shape using CAD / CAM, and the machined calcined body is then sintered to produce the sintered body.

[0003] Lanthanide rare earth elements and transition metal elements are the main coloring components for zirconia. Transition metal elements are widely used as coloring components because they are inexpensive and can easily produce sintered bodies with the desired color tone.

[0004] For example, Patent Document 1 considers molding a powder containing a transition metal compound made of iron or cobalt as a coloring component and zirconia, and sintering the molded powder, in order to obtain a sintered body having a color suitable for dental prostheses.

[0005] Furthermore, Patent Document 2 considers immersing a porous calcined body in a coloring solution containing iron ions and sintering it in order to obtain a sintered body having a color suitable for dental prostheses. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] U.S. Patent No. 9,428,422 [Patent Document 2] European Patent Application Publication No. 3892254 Summary of the Invention [Problem to be solved by the invention]

[0007] In the method disclosed in Patent Document 2, the coloring component is gradually impregnated from the surface to the interior. Therefore, the concentration of the coloring component is high on the surface of the calcined body and low in the interior, and the coloring component is contained in the calcined body at a gradient concentration from the surface to the interior. As a result, the resulting sintered body tends to have different color tones between the surface and the interior. Furthermore, if a calcined body that has already been processed is reprocessed, the color tone of the resulting sintered body may be visually perceived as different from the color tone before reprocessing. In contrast, the method disclosed in Patent Document 1 can produce calcined bodies and sintered bodies in which the coloring component is contained almost uniformly from the surface to the interior of the calcined body. Therefore, the calcined body obtained from the powder in Patent Document 1 is suitable for calcined body processing, and the color tone change before and after reprocessing is smaller than that of the calcined body obtained in Patent Document 2. However, with recent improvements in processing technology, fine processing has become common, and as a result, calcined bodies with more uniform processing characteristics than the calcined bodies obtained from the powder in Patent Document 1 are desired.

[0008] An object of the present disclosure is to provide a powder containing zirconia as a main component and also containing at least a transition metal element, which powder can be used to obtain a calcined body having mechanical properties suitable for calcined body processing, a method for producing the powder, and at least one of a calcined body and a sintered body obtained from the powder, and methods for producing these. Another object of the present disclosure is to provide a powder of colored zirconia that is suitable as a raw material for a calcined body with excellent processability, and at least one of a method for producing the powder, and further to provide at least one of a calcined body and a sintered body obtained from the powder. [Means for solving the problem]

[0009] In the present disclosure, the workability of calcined bodies containing zirconia as a main component and a transition metal element was investigated. As a result, the workability of calcined bodies containing zirconia as a main component and a transition metal element was found to be reduced not only because sintering shrinkage was accelerated but also because the sintering shrinkage progressed non-uniformly compared to calcined bodies of zirconia not containing the transition metal element. Furthermore, the workability of calcined bodies was found to be reduced by controlling the dispersibility of the transition metal element in the powder and by controlling the dispersibility of the transition metal element in the powder. Furthermore, the workability of calcined bodies containing zirconia as a main component and a transition metal element was found to be reduced ...

[0010] That is, the present invention is as defined in the claims, and the gist of the present disclosure is as follows. [1] Zirconia powder containing a stabilizing element and a transition metal element, in which the difference between the minimum and maximum values ​​of the transition metal element / zirconium ratio in the frequency distribution plotted at intervals of 0.005 is less than 0.25. [2] The powder according to [1] above, wherein the transition metal element is one or more selected from the group consisting of titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), niobium (Nb), vanadium (V), molybdenum (Mo), technetium (Tc), ruthenium (Ru), rhodium (Rh), palladium (Pd), and silver (Ag). [3] The powder according to [1] or [2] above, wherein the stabilizing element is one or more selected from the group consisting of yttrium (Y), calcium (Ca), magnesium (Mg), terbium (Tb) and erbium (Er). [4] The powder according to any one of [1] to [3] above, which contains one or more selected from the group consisting of alumina (Al2O3), silica (SiO2) and germania (GeO2). [5] The powder according to any one of [1] to [4] above, wherein the total frequency of transition metal elements / zirconium of 0.05 or more in the frequency distribution is 2.5% or less. [6] BET specific surface area is 8m 2 / g or more 15m 2 The powder according to any one of [1] to [5] above, wherein the solubility is 0.01% or less. [7] Lightly packed bulk density of 1.10 g / cm 3 More than 1.40g / cm 3 The powder according to any one of [1] to [6] above, which is: [8] The powder according to any one of [1] to [7] above, wherein 3.0 g of the powder is filled into a mold having a diameter of 25 mm, uniaxially pressed at a pressure of 49 MPa, and then subjected to CIP treatment at a pressure of 196 MPa to obtain a disk-shaped compact, which is then calcined under the following conditions to form a calcined body; the shrinkage rate calculated from the following formula is less than 4.0%. Calcining temperature: 1000℃ Pre-baking time: 1 hour Heating rate: 50°C / hour Calcination atmosphere: air Cooling rate: 300℃ / hour Shrinkage rate [%] = {(25 - diameter of calcined body) [mm] / 25 [mm]} x 100 ···(1) [9] The powder according to any one of [1] to [8] above, which is a granular powder.

[0011]

[10] A method for producing the powder according to any one of [1] to [8] above, comprising the steps of drying a composition containing hydrated zirconia, a stabilizing element source, a transition metal element source, and a solvent to obtain a dry powder, and heat-treating the dry powder at a temperature lower than the sintering temperature to obtain a calcined powder.

[11] The production method according to

[10] above, wherein the transition metal element source is at least one of an oxide and a chloride of one or more elements selected from the group consisting of titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), niobium (Nb), molybdenum (Mo), technetium (Tc), ruthenium (Ru), rhodium (Rh), palladium (Pd), and silver (Ag).

[12] The method according to

[10] or

[11] above, wherein the heat treatment temperature is 1200°C or less.

[13] A molded body containing the powder according to any one of [1] to [9] above.

[14] A method for producing a calcined body, comprising a step of calcining the molded body according to

[13] above.

[15] A method for producing a sintered body, comprising a step of sintering at least one of a molded body containing the powder according to any one of [1] to [9] above, and a calcined body obtained by calcining the molded body. [Effects of the Invention]

[0012] The present disclosure can provide a powder containing zirconia as a main component and also containing at least a transition metal element, which can yield a calcined body having mechanical properties more suitable for calcined body processing, a method for producing the powder, and at least one of a calcined body and a sintered body obtained from the powder, and methods for producing these.It can also provide a powder of colored zirconia that is suitable as a raw material for a calcined body with excellent processability, and at least one of a method for producing the powder, and further provide at least one of a calcined body and a sintered body obtained from the powder. [Brief explanation of the drawings]

[0013] [Figure 1] Schematic diagram showing the arrangement of calcined bodies during sintering in Measurement Example 1 [Figure 2] Element frequency distribution (histogram) of the powder of Example 1 [Figure 3] Element frequency distribution (histogram) of the powder of Comparative Example 1 [Figure 4]Elemental mapping of iron in Example 1 [Figure 5] Elemental mapping of iron in Comparative Example 1 [Figure 6] Elemental mapping of cobalt in Example 2 [Figure 7] Elemental mapping of manganese in Example 3 [Figure 8] Elemental mapping of nickel in Example 4 [Figure 9] Elemental mapping of iron in Example 8 [Figure 10] Iron elemental mapping in Example 9 DETAILED DESCRIPTION OF THE INVENTION

[0014] The powder of the present disclosure will be described with reference to an example embodiment. The terms used in this embodiment are as follows:

[0015] The term "composition" refers to a substance having a specific composition, and includes, for example, one or more selected from the group consisting of powder, molded body, calcined body, and sintered body. The term "zirconia composition" refers to a composition containing zirconia as a main component, and further refers to a composition consisting essentially of zirconia.

[0016] The term "powder" refers to a composition that is an aggregate of powder particles (primary particles and / or secondary particles) and has fluidity. The term "zirconia powder" refers to a powder whose main component is zirconia and is essentially composed of zirconia.

[0017] "Granular powder" refers to a composition that is an aggregate of powder particle agglomerates (granular particles) and has fluidity, particularly a composition in which the powder particles are in a loosely aggregated state. "Zirconia granular powder" refers to a granular powder whose main component is zirconia, and is essentially composed of zirconia.

[0018] A "green body" is a composition having a certain shape composed of powder particles agglomerated by physical force, and in particular, a composition in a state in which the composition has not been subjected to heat treatment after imparting the shape (e.g., after molding). A "zirconia green body" is a green body whose main component is zirconia, and is essentially made of zirconia. The term "green body" is also used interchangeably with "green body."

[0019] The term "calcined body" refers to a composition having a certain shape and composed of fused particles, which is heat-treated at a temperature below the sintering temperature. The term "zirconia calcined body" refers to a calcined body containing zirconia as the main component, and essentially consisting of zirconia.

[0020] A "sintered body" is a composition having a certain shape and composed of crystal grains, and is a composition in a state in which it has been heat-treated at a temperature equal to or higher than the sintering temperature. A "zirconia sintered body" is a sintered body whose main component is zirconia, and is a sintered body essentially consisting of zirconia.

[0021] A "major component" is a component that becomes the main phase (matrix, base material, parent phase) in the composition of the composition, and preferably a component that accounts for a mass percentage of the composition of 75 mass% or more, 85 mass% or more, 90 mass% or more, 95 mass% or more, 98 mass% or more, or 99 mass% or more, or 100 mass% or less or less than 100 mass%.

[0022] The "stabilizing element" is an element that stabilizes the crystalline phase of zirconia by dissolving in zirconia.

[0023] "BET specific surface area" is the specific surface area [m2] measured by the BET multipoint method (5 points) using nitrogen as the adsorption gas in accordance with JIS R 1626. 2 / g], and in particular the BET specific surface area measured under the following conditions:

[0024] Adsorption medium: N2 Adsorption temperature: -196℃ Pretreatment conditions: Degassing in air at 250°C for at least 1 hour The BET specific surface area can be measured using a general specific surface area measuring device (for example, Tristar II 3020, manufactured by Shimadzu Corporation).

[0025] The "average particle size" is D50 in the volume particle size distribution of a powder measured by a wet method, and can be measured using a common device (e.g., MT3300EXII, manufactured by Microtrac-Bell). The measurement sample may be prepared by dispersing powder, from which slow agglomerates have been removed by a dispersion treatment such as ultrasonication, in pure water to form a slurry. When measuring the volume particle size distribution by a wet method, it is preferable to measure the slurry at a pH of 3.0 to 6.0.

[0026] The "average granule particle size" is the D50 in the volume particle size distribution of granular powder measured by the dry method, and can be measured using a general instrument (e.g., MT3100II, manufactured by Microtrac-Bell). The measurement sample is granular powder in a slowly agglomerated state, without undergoing dispersion treatment such as ultrasonic treatment.

[0027] The "bulk density" is the density measured by a method conforming to JIS R 1628.

[0028] The "average crystal grain size" is the average diameter of the crystal grains constituting the sintered body, and is obtained by observing the surface of the sintered body with a scanning electron microscope (hereinafter also referred to as "SEM") and performing image analysis of the SEM observation image.

[0029] SEM observation for measuring the average crystal grain size can be performed using a general scanning electron microscope (for example, JSM-IT500LA, manufactured by JEOL Ltd.). SEM observation can be performed by appropriately setting the observation magnification so that the number of crystal grains to be analyzed (crystal grains whose grain boundaries are observed continuously in the SEM observation image (described below)) is 450±50. To suppress variations in the observed crystal grains due to differences in the SEM observation location, the average crystal grain size can be determined from the SEM observation image for 2 or more, or even 3 to 5, so that the total number of observed crystal grains is the above-mentioned number of crystal grains. The conditions for SEM observation can be as follows: Accelerating voltage: 15 kV Irradiation current: 40nA Observation magnification: 5000x to 10000x

[0030] Image analysis of the SEM observation image can be performed using image analysis software (for example, Mac-View Ver. 5, manufactured by MOUNTECH). Specifically, crystal grains in which the crystal grain boundaries are observed without interruption in the SEM observation image are extracted, and the area [μm 2 ] is calculated. The diameter [μm] of a circle having the same area as the calculated area is converted, and the obtained diameter (Heywood diameter; hereinafter also referred to as "equivalent circle diameter") can be regarded as the grain size of each crystal grain. The average value of the equivalent circle diameters of the extracted crystal grains can be used as the average grain size of the sintered body.

[0031] The term "powder X-ray diffraction pattern" refers to an XRD pattern obtained by powder X-ray diffraction (hereinafter also referred to as "XRD") measurement of a composition under the following conditions, followed by smoothing and background removal processing using an analysis program attached to the X-ray diffractometer (e.g., integrated powder X-ray analysis software PDXL Ver. 2.2, manufactured by RIGAKU Corporation). Radiation source: CuKα radiation (λ=0.15418nm) Measurement mode: Continuous scan Scan speed: 2° / min Measurement range: 2θ=26°~33° 2θ=72°~76° Accelerating voltage / current: 40mA / 40kV Divergence vertical limit slit: 10mm Divergence / entrance slit: 1° Receiving slit: open Detector: Semiconductor detector (D / teX Ultra) Filter: Ni filter Goniometer radius: 185mm

[0032] XRD measurement can be performed using a general X-ray diffractometer (e.g., Ultima IV, manufactured by RIGAKU Corporation). The surface of the calcined body can be polished using sandpaper with a grit size of #400 in accordance with JIS R 6001-2, and then lapped using a diamond abrasive with a grit size of 3 μm to prepare a measurement sample, and the surface after lapping can be measured by XRD. The surface of the sintered body can be polished to a surface roughness Ra≦0.02 μm to prepare a measurement sample, and the surface after polishing can be measured by XRD.

[0033] The term "XRD peak" refers to a peak having a peak top at 2θ detected in the XRD pattern obtained by the above-described XRD measurement. In this embodiment, "not having an XRD peak" means that the XRD peak is not detected in the XRD pattern obtained by the above-described XRD measurement.

[0034] Examples of XRD peaks corresponding to the crystal planes of zirconia include XRD peaks having peak tops at the following 2θ positions. XRD peak corresponding to the monoclinic (111) plane: 2θ=31±0.5° XRD peak corresponding to the monoclinic (11-1) plane: 2θ=28±0.5° XRD peak corresponding to tetragonal (111) plane: 2θ=30±0.5° XRD peak corresponding to cubic (111) plane: 2θ=30±0.5°

[0035] The XRD peak corresponding to the tetragonal (111) plane and the XRD peak corresponding to the cubic (111) plane are measured as a single overlapping peak.

[0036] The "T+C phase ratio" is the ratio of the area intensity of the XRD peaks of tetragonal and cubic zirconia to the total area intensity of the XRD peaks of tetragonal, cubic, and monoclinic zirconia in the XRD pattern obtained by the above-mentioned XRD measurement, and the "M phase ratio" is the ratio of the area intensity of the XRD peak of monoclinic zirconia to the total area intensity of the XRD peaks of tetragonal, cubic, and monoclinic zirconia in the XRD pattern obtained by the above-mentioned XRD measurement, and these can be calculated using the following equations.

[0037] f T+C =[I t (111)+I c (111)] / [I m (111)+I m (11-1)+I t (111)+I c (111)] f M =1-f T+C In the above equation, f T+C is the T+C phase ratio, f M is the M phase ratio, I t (111) is the area intensity of the tetragonal (111) plane, I c (111) is the area intensity of the cubic (111) plane, I m (111) is the area intensity of the monoclinic (111) plane, I m (11-1) is the area intensity of the monoclinic (11-1) plane, and I t (111)+I c (111) corresponds to the area intensity of the XRD peak having a peak top at 2θ=30±0.5°.

[0038] The area intensity of each XRD peak is a value obtained by analyzing the XRD pattern using an analysis program attached to the X-ray diffractometer (for example, integrated powder X-ray analysis software PDXL Ver. 2.2, manufactured by RIGAKU Corporation).

[0039] "Measured density" is the density of the sample volume [cm 3 ] to the mass [g] [g / cm 3 The mass is determined by weighing the sample, and the volume is determined by measuring the shape of the compact and calcined body, while the volume is determined by Archimedes' method according to JIS R 1634 for the sintered body. The Archimedes' method uses ion-exchanged water as the solvent, and the pretreatment may be performed by boiling.

[0040] "Total light transmittance" is the ratio [%] of transmitted light (total of direct transmitted light and diffuse transmitted light) to incident light, measured in accordance with JIS K 7361-1 for a measurement sample with a thickness of 1.0±0.1 mm. The measurement sample is a disk-shaped sintered body with a thickness of 1.0±0.1 mm and a surface roughness Ra≦0.02 μm on both sides, and the measurement device can be a haze meter equipped with a D65 light source (for example, Haze Meter NDH4000, manufactured by Nippon Denshoku Co., Ltd.).

[0041] "Color tone (L * , a * , b * ) and "Saturation C * " is a value obtained using a spectrophotometer (e.g., CM-700d, manufactured by Konica Minolta) equipped with an illumination and light-receiving optical system that conforms to geometric condition c of JIS Z 8722, and using values ​​measured using the SCI method. A specific measurement method is to place a zero calibration box on the measurement sample and measure under the following conditions (so-called black background measurement). Light source: D65 light source Viewing angle: 2° Measurement method: SCI

[0042] The color tone of the sintered body can be measured by cutting out any part of the sintered body horizontally and processing it to a thickness of 1.0±0.1 mm to obtain a measurement sample.

[0043] "Lightness L *" is an index showing brightness and has a value between 0 and 100. * " and "Hue b * " is an index showing the color tone, and has a value between -100 and 100. "Saturation C * " is an index of vividness, and hue a * and b * From C * ={(a * ) 2 +(b * ) 2} 0.5 It is calculated by:

[0044] The "three-point bending strength" is a value measured using a method conforming to JIS R 1601. The measurement sample is a columnar specimen with a width of 4 mm, a thickness of 3 mm, and a length of 45 mm, with a distance between supports of 30 mm, and the measurement is performed by applying a load horizontally to the specimen.

[0045] "Vickers hardness" is an index of workability, and is measured using a common Vickers tester (e.g., Q30A, manufactured by Qness) equipped with a square pyramidal diamond indenter. The measurement is performed by statically pressing the indenter into the surface of the test sample and measuring the diagonal length of the indentation mark formed on the surface of the test sample. The obtained diagonal length can be used to calculate the Vickers hardness using the following formula.

[0046] Hv=F / {d 2 / 2sin(α / 2)} In the above formula, Hv is Vickers hardness (HV), F is the measurement load (1 kgf), d is the diagonal length of the indentation mark (mm), and α is the facing angle of the indenter (136°).

[0047] The conditions for measuring the Vickers hardness are as follows. Measurement sample: Disc-shaped with a thickness of 3.0±0.5mm Measurement load: 1kgf

[0048] Prior to measurement, the measurement surface of the sample is polished with #800 waterproof abrasive paper to remove irregularities exceeding 0.1 mm, which serves as pretreatment.

[0049] "Atmospheric pressure sintering" is a method of sintering an object to be sintered (such as a compact or calcined body) by heating the object to a temperature equal to or higher than the sintering temperature without applying an external force to the object during sintering.

[0050] <Powder> The powder of this embodiment is a zirconia powder containing a stabilizing element and a transition metal element, in which the difference between the minimum and maximum values ​​of the transition metal element / zirconium ratio is less than 0.25 in a frequency distribution of the element ratio in which the transition metal element / zirconium ratio is plotted at intervals of 0.005, and is a colored zirconia powder colored by the transition metal element.

[0051] The powder of this embodiment is a zirconia powder containing a stabilizing element and a transition metal element, and may be considered as a powder containing zirconia, a stabilizing element, and a transition metal element and containing zirconia as a main component, or further as a zirconia powder containing a stabilizing element and a transition metal element. The powder of this embodiment is preferably a powder of stabilizing element-dissolved zirconia containing a transition metal element.

[0052] The powder of this embodiment is a zirconia powder, i.e., a powder containing zirconia as a main component. In the powder of this embodiment, the zirconia is preferably zirconia in which a stabilizing element is dissolved (hereinafter, also referred to as "stabilizing element dissolved zirconia").

[0053] Zirconia may contain inevitable impurities such as hafnia (HfO2), etc. In the calculation of values ​​based on the composition, such as the composition and density, in this embodiment, hafnia may be considered as zirconia.

[0054] The powder of this embodiment contains a stabilizing element. Examples of the stabilizing element include rare earth elements, specifically one or more elements selected from the group consisting of yttrium (Y), calcium (Ca), magnesium (Mg), terbium (Tb), and erbium (Er). The stabilizing element is preferably one or more elements selected from the group consisting of yttrium, terbium, and erbium. The stabilizing element is preferably an element that does not affect the color tone of zirconia, specifically one or more elements selected from the group consisting of yttrium, calcium, and magnesium, with yttrium being even more preferred.

[0055] It is preferable that at least a portion of the stabilizing element is solid-dissolved in zirconia, and it is more preferable that the stabilizing element is solid-dissolved in zirconia (i.e., the powder of this embodiment does not contain any undissolved stabilizing element). However, the powder of this embodiment may contain a stabilizing element undissolved in zirconia as long as the effect of the powder of this embodiment is exhibited.

[0056] In this embodiment, the absence of an undissolved stabilizing element can be confirmed by the absence of an XRD peak derived from a compound of the stabilizing element in the XRD pattern.

[0057] The amount of the stabilizing element in the powder of this embodiment (hereinafter also referred to as the "stabilizing element amount," or when the stabilizing element is yttrium or the like, also referred to as the "yttrium amount," etc.) may be an amount that partially stabilizes the zirconia crystal phase, and may be an amount that causes zirconia to have a crystal phase with tetragonal and cubic crystals as the main phases. The stabilizing element amount may be, for example, 2 mol% or more or 2.5 mol% or more and 15 mol% or less or 7.5 mol% or less, and preferably 2 mol% or more and 15 mol% or less, 2.5 mol% or more and 15 mol% or less, or 3.5 mol% or more and 5.9 mol% or less. When the stabilizing element is yttrium, the stabilizing element amount (yttrium amount) may be 3 mol% or more, 3.3 mol% or more, 3.5 mol% or more, or 3.6 mol% or more, and may be 6.5 mol% or less, 6 mol% or less, 5.5 mol% or less, or 5.2 mol% or less. Preferred amounts of the stabilizing element, which facilitate more uniform dispersion of the transition metal element, include 2 mol% to 6.5 mol%, 3 mol% to 6.5 mol%, 3.3 mol% to 6 mol%, 3.5 mol% to 5.5 mol%, 3.6 mol% to 5.1 mol%, and 4.8 mol% to 5.5 mol%.

[0058] The amount of stabilizing element can be calculated as the ratio [mol%] of the stabilizing element converted to oxide to the total [mol] of zirconia and the stabilizing element converted to oxide. The oxide equivalents of each stabilizing element are Y2O3 for yttrium, CaO for calcium, MgO for magnesium, Tb4O7 for terbium, and Er2O3 for erbium. Examples include:

[0059] The powder of this embodiment contains a transition metal element. The transition metal element in the powder of this embodiment particularly refers to a transition metal element contained in the powder as a coloring component. As a result, a sintered body obtained from the powder of this embodiment exhibits a desired color tone derived from the transition metal element, particularly a color tone that is difficult to achieve with lanthanide rare earth elements, etc.

[0060] The transition metal element contained in the powder of this embodiment is a transition metal element capable of coloring zirconia, preferably a transition metal element other than zirconium and hafnium, more preferably at least one of a 3d transition metal element (3d transition element) and a 4d transition metal element (4d transition element) other than zirconium, even more preferably a 3d transition metal element, and even more preferably a 3d transition metal element other than vanadium. For convenience, in this embodiment, the transition metal element does not include lanthanoid rare earth elements, and refers to a transition metal element other than lanthanoid rare earth elements. Specific examples of the transition metal element include one or more selected from the group consisting of titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), niobium (Nb), vanadium (V), molybdenum (Mo), technetium (Tc), ruthenium (Ru), rhodium (Rh), palladium (Pd), and silver (Ag). Preferably, the transition metal element is one or more selected from the group consisting of titanium, chromium, manganese, iron, cobalt, nickel, and copper. More preferably, the transition metal element is one or more selected from the group consisting of titanium, manganese, iron, and cobalt. Still more preferably, the transition metal element is one or more selected from the group consisting of titanium, iron, and manganese. At least one of iron and titanium is even more preferable, and iron is particularly preferable.

[0061] For example, when obtaining a sintered body exhibiting a yellowish color, the transition metal element may be one or more selected from the group consisting of chromium, iron, and vanadium, with iron being preferred. Furthermore, when obtaining a sintered body exhibiting a greenish color, the transition metal element may be nickel. When obtaining a sintered body exhibiting a grayish color, the transition metal element may be manganese. When obtaining a sintered body exhibiting a blueish color, the transition metal element may be cobalt. To obtain a sintered body exhibiting a color tone suitable for dental prostheses, the transition metal element contained in the powder of this embodiment may be one or more selected from the group consisting of nickel, cobalt, manganese, and iron, or may be nickel, cobalt, manganese, or iron, or may be one or more selected from the group consisting of cobalt, manganese, and iron, or may be cobalt, manganese, or iron, or may be at least one of cobalt and iron, or may be cobalt or iron, with iron being preferred.

[0062] Since the crystalline phase of zirconia is likely to transform in an air atmosphere, when the powder of this embodiment contains vanadium (V), the content thereof may be 0 mass% or more and 0.005 mass% or less, or even more than 0 mass% and 0.005 mass% or less, and it is preferable that the powder does not contain vanadium (below the measurement limit).

[0063] The content of the transition metal element in the powder of this embodiment (hereinafter also referred to as the "transition metal amount," and when the transition metal element is iron or the like, also referred to as the "iron amount," etc.) may be an amount that does not cause precipitation of crystal particles of the transition metal compound in the sintered body obtained from the powder of this embodiment, and may be, for example, more than 0% by mass, 0.01% by mass or more, 0.04% by mass or more, or 0.1% by mass or more, and 3% by mass or less, 2% by mass or less, less than 2% by mass, 1% by mass or less, or 0.5% by mass or less. Preferred transition metal amounts include more than 0% by mass but not more than 3% by mass, 0.01% by mass or more but not more than 3% by mass, 0.04% by mass or more but not more than 2% by mass, 0.04% by mass or more but not more than 2% by mass, 0.04% by mass or more but not more than 1% by mass, or 0.1% by mass or more but not more than 2% by mass.

[0064] For example, the iron content of the powder of this embodiment is 0.01% by mass or more or 0.1% by mass or more, and 3% by mass or less, 2% by mass or less, 1% by mass or less, or 0.5% by mass or less, with preferred iron contents being 0.01% by mass or more and 3% by mass or less, 0.1% by mass or more and 3% by mass or less, 0.1% by mass or more and 2% by mass or less, or 0.1% by mass or more and 0.5% by mass or less, and the cobalt content, nickel content, and manganese content of the powder of this embodiment are 0.01% by mass or more or 0.03% by mass or more, and 1% by mass or less, 0.5% by mass or less, or 0.1% by mass or less, with preferred contents being 0.01% by mass or more and 0.5% by mass or less, or 0.03% by mass or more and 0.1% by mass or less.

[0065] The amount of transition metal can be calculated as the mass ratio (mass%) of the transition metal element (g) converted to its oxide to the total mass (g) of zirconia, the stabilizing element (converted to its oxide), and the metal element (converted to its oxide). The oxide equivalents of the transition metal elements are as follows: titanium (TiO2), chromium (Cr2O3), manganese (Mn3O4), iron (Fe2O3), cobalt (Co3O4), nickel (NiO), copper (CuO), niobium (Nb2O3), vanadium (V2O5), molybdenum (Mo2O3), technetium (Tc2O3), ruthenium (RuO2), rhodium (RhO2), palladium (Pd2O3), and silver (Ag2O).

[0066] In the powder of this embodiment, in a frequency distribution of element ratios (hereinafter simply referred to as "element frequency distribution") in which the transition metal element / zirconium ratio is plotted at intervals of 0.005, the difference between the minimum and maximum value of the transition metal element / zirconium ratio is less than 0.25, and is preferably 0.2 or less, 0.16 or less, 0.12 or less, 0.11 or less, or 0.1 or less. Since the powder of this embodiment is mainly composed of zirconia, the zirconia is dispersed almost uniformly. On the other hand, the amount of transition metal element required for coloring zirconia, particularly for coloring zirconia used as a dental prosthetic material, is extremely small relative to the amount of zirconia. Although small amounts of transition metal elements tend to aggregate, the difference between the minimum and maximum values ​​of M / Zr (hereinafter referred to as the "M / Zr range"; when the transition metal element is iron, for example, it is also referred to as the "Fe / Zr range," etc.) satisfying the above-mentioned value is believed to result in the transition metal elements being contained in a more uniformly dispersed state than in conventional zirconia powders containing transition metal elements as coloring components. This is believed to suppress aggregation of the transition metal elements when the powder of this embodiment is heat-treated compared to conventional powders. As a result, a calcined body having a hardness suitable for processing (especially CAD / CAM processing for dental prosthetic materials) can be obtained. Furthermore, localized hard regions are less likely to occur in the resulting calcined body, resulting in a calcined body exhibiting more uniform processability. While the smaller the M / Zr range, the more uniform the transition metal elements are, and the powder of this embodiment has a certain range of distribution of the transition metal elements (i.e., the minimum and maximum values ​​of M / Zr are different). Therefore, the M / Zr range can be greater than 0, 0.03 or greater, or 0.06 or greater. Preferred M / Zr ranges include more than 0 and less than 0.25, more than 0 and 0.2 or less, 0.03 to 0.16, 0.03 to 0.12, 0.03 to 0.1 or less, or 0.06 to 0.1 or less.

[0067] To avoid segregation of the transition metal elements, the powder of this embodiment preferably has little excessive aggregation of the transition metal elements, and the maximum value of M / Zr in the element frequency distribution is, for example, 0.3 or less, 0.2 or less, 0.1 or less, or 0.08 or less. However, since the detection sensitivity for each element in the EPMA measurement described below differs, the maximum value of M / Zr may vary depending on the type of transition metal element. For example, when the transition metal element is iron, the maximum value of M / Zr (Fe / Zr) can be 0.03 to 0.2, 0.05 to 0.12, or 0.05 to 0.1, for example. Similarly, when the transition metal element is cobalt, the maximum value of M / Zr (Co / Zr) can be 0.03 or more and 0.2 or less, or 0.1 or more and 0.15 or less; when the transition metal element is manganese, the maximum value of M / Zr (Mn / Zr) can be 0.03 or more and 0.2 or less, or 0.05 or more and 0.12 or less; and when the transition metal element is nickel, the maximum value of M / Zr (Ni / Zr) can be 0.03 or more and 0.2 or less, or 0.12 or more and 0.18 or less.

[0068] Similarly, when the transition metal element is iron, the total frequency of elements with an M / Zr ratio of 0.05 or more (hereinafter also referred to as the "high metal frequency") in the element frequency distribution is 2.5% or less, and preferably 2% or less, 1.5% or less, 1.0% or less, 0.5% or less, 0.1% or less, or 0.05% or less. The high metal frequency may be 0% or more, more than 0%, or 0.02% or more. When the transition metal element is iron, by having the high metal frequency in this range, the calcined body obtained from the powder of this embodiment does not become too hard and has a hardness more suitable for processing. When the transition metal element is iron, preferred high metal frequencies include 0% to 2.5%, 0% to 1.5%, 0% to 0.1%, more than 0% to 0.1%, or more than 0% to 0.05%.

[0069] When the transition metal element is iron, the powder of this embodiment has, in its element frequency distribution, a total frequency where M / Zr is less than 0.005 (hereinafter also referred to as "low metal frequency") of 6.5% or less or 5% or less, and may also be 0% or more, more than 0%, or 3% or more, since this makes it easier for the resulting calcined body to have more uniform mechanical properties. Preferably, the total frequency is 0% or more and 6.5% or less, 0% or more and 5% or less, or more than 0% and 5% or less.

[0070] The element frequency distribution in this embodiment is a distribution obtained from the EPMA spectrum of the powder, and is obtained from element mapping of the transition metal elements and zirconium by EPMA measurement.

[0071] Specifically, the element frequency distribution can be determined by the following method. First, the SEM observation image of the powder of this embodiment is divided into 50,000 to 66,000 regions, and each of the resulting regions is designated as a measurement point. The characteristic X-rays of zirconium and transition metal elements are measured at each measurement point to obtain an element mapping. Next, the ratio (M / Zr) of the intensity of the characteristic X-rays of the transition metal element (M) to the intensity of the characteristic X-rays of zirconium (Zr) at each measurement point is determined. From the determined M / Zr, a histogram is created in which the classes are M / Zr, the class width (maximum and minimum values ​​of M / Zr in each class) is 0.005, and the frequency (frequency) is the number of measurement points corresponding to each class, and this histogram is designated as the element frequency distribution. Specifically, M / Zr can be divided into classes from 0 to the maximum value of M / Zr, with class widths in 0.005 intervals, such as 0 or more and less than 0.005, 0.005 or more and less than 0.010, etc., and the histogram obtained by plotting the frequency of each class can be used as the element frequency distribution.

[0072] The conditions for SEM observation and EPMA in measuring the element frequency distribution are as follows: Accelerating voltage: 15 kV Irradiation current: 50nA Beam diameter: 1 μm Capture time: 50 msec Magnification: 5000x

[0073] For SEM observation and EPMA measurement, a scanning electron microscope equipped with an electron beam microanalyzer (for example, EPMA1610 manufactured by Shimadzu Corporation or JXA-iHP200F manufactured by JEOL Ltd.) can be used. Resin-embedded powder (powder particles) is used as the measurement sample, and the cross section obtained by cutting it can be observed with SEM and measured with EPMA. To obtain accurate elemental mapping, the powder (powder particles) used as the measurement sample is preferably granular powder (granular particles).

[0074] The M / Zr range is the absolute value of the difference between the maximum M / Zr value and the minimum M / Zr value in the element frequency distribution. The maximum M / Zr value is the smallest M / Zr value in the class next to the class with the maximum M / Zr in the element frequency distribution. For example, if the M / Zr of the maximum class is 0.100 or more and less than 0.105, the minimum value of the next class (0.105 or more and less than 0.110), 0.105, corresponds to the maximum M / Zr. On the other hand, the minimum M / Zr value is the minimum M / Zr value in the smallest class in the element frequency distribution. For example, if the M / Zr of the smallest class is 0 or more and less than 0.005, 0 corresponds to the minimum M / Zr value, and if the M / Zr of the smallest class is 0.005 or more and less than 0.010, 0.005 corresponds to the minimum M / Zr value.

[0075] The high metal concentration is the percentage (%) of the total frequency (total number of measurement points) in the class where M / Zr is 0.05 or more (the number of measurement points where M / Zr is 0.05 or more), and the low metal concentration is the percentage (%) of the total frequency (total number of measurement points) in the class where M / Zr is less than 0.005 (the number of measurement points where M / Zr is less than 0.005) in the element frequency distribution. Therefore, the high metal frequency can be considered as the percentage of the number of measurement points in element mapping by EPMA measurement where the intensity of the characteristic X-rays of transition metal elements relative to the characteristic X-rays of zirconium is 0.05 or more, and the low metal frequency can be considered as the percentage of the number of measurement points in element mapping by EPMA measurement where the intensity of the characteristic X-rays of transition metal elements relative to the characteristic X-rays of zirconium is less than 0.005.

[0076] To adjust the sinterability, the powder of this embodiment may contain one or more elements selected from the group consisting of alumina (Al2O3), silica (SiO2), and germania (GeO2) (hereinafter also referred to as "additive component"), and may further contain alumina. The addition of the additive component can lower the sintering temperature. The content of the additive component (hereinafter also referred to as "additive component amount," and when the additive component is alumina or the like, also referred to as "alumina amount," etc.) can be adjusted appropriately depending on the desired sinterability, and may be 0% by mass or more, more than 0% by mass, 0.005% by mass or more, 0.01% by mass or more, or 0.03% by mass or more, or less than 0.2% by mass, less than 0.15% by mass, less than 0.1% by mass, or 0.08% by mass or less. Preferable amounts of the added component include 0% by mass or more and less than 0.2% by mass, 0% by mass or more and 0.08% by mass or less, 0% by mass or more and 0.04% by mass or less, 0% by mass or more and 0.08% by mass or less, more than 0% by mass but less than 0.2% by mass, or 0.005% by mass or more and 0.08% by mass or less.

[0077] The amount of the added component may be determined as the ratio [mass %] of the added component [g] converted to oxide to the total [g] of zirconia, the stabilizing element converted to oxide, and the metal element converted to oxide.

[0078] The powder of this embodiment may contain a binder. The inclusion of a binder enhances the shape retention of the compact (green compact) obtained by molding the powder of this embodiment. The binder may be any known binder used in ceramic molding, and is preferably an organic binder. The organic binder is at least one selected from the group consisting of polyvinyl alcohol, polyvinyl butyrate, wax, and acrylic resin, preferably at least one selected from polyvinyl alcohol and acrylic resin, and more preferably an acrylic resin. In this embodiment, the acrylic resin is a polymer containing at least one of an acrylic acid ester and a methacrylic acid ester. Specific examples of the acrylic resin include at least one selected from the group consisting of polyacrylic acid, polymethacrylic acid, acrylic acid copolymers, and methacrylic acid copolymers, as well as derivatives thereof. Specific examples of the acrylic resin binder include acrylic resins used for ceramic powders, and at least one selected from the group consisting of AS-1100, AS-1800, and AS-2000 (all product names, manufactured by Toagosei Co., Ltd.).

[0079] The binder content in the powder may be any amount that allows the powder to exhibit the desired shape retention, but the mass ratio of the binder to the mass of the powder is, for example, 0.5% by mass or more or 1% by mass or more, and 10% by mass or less or 5% by mass or less, and is preferably 0.5% by mass or more and 10% by mass or less, or 1% by mass or more and 4% by mass or less.

[0080] For example, when the powder of this embodiment is a zirconia powder containing yttrium and erbium as stabilizing elements, iron and cobalt as transition metal elements, and alumina as an additive component, its composition can be determined as follows. Stabilizing element amount [mol%]={(Y2O3+Er2O3) / (Y2O3+Er2O3+ ZrO2)}×100, Amount of yttrium [mol%] = {Y2O3 / (Y2O3+Er2O3+ZrO2)} × 100, Erbium content [mol%] = {Er2O3 / (Y2O3+Er2O3+ZrO2)} × 100, Transition metal amount [mass%]={(Fe2O3+Co3O4) / (Y2O3+Er2O3+Z rO2+Al2O3+Fe2O3+Co3O4}×100, Iron amount [mass%]={Fe2O3 / (Y2O3+Er2O3+ZrO2+Al2O3+F e2O3+Co3O4}×100, Cobalt content [mass%] = {Co3O4 / (Y2O3 + Er2O3 + ZrO2 + Al2O 3 + Fe2O3 + Co3O4} × 100, and Added component amount (alumina amount) = {Al2O3 / (Y2O3+Er2O3+ZrO2+Al 2O3+Fe2O3+Co3O4}×100

[0081] The binder content [mass %] is calculated from the mass of the powder of this embodiment before and after heat treatment in air at 250° C. to 400° C. by [{(mass of powder before heat treatment)−(mass of powder after heat treatment)} / (mass of powder before heat treatment)] × 100. The amounts of stabilizing elements, transition metals, and additive components in the powder containing the binder can also be calculated by the above-mentioned method.

[0082] The powder of this embodiment has an XRD peak of zirconia in its XRD pattern. Furthermore, the powder of this embodiment preferably has no XRD peaks other than those of zirconia in its XRD pattern, i.e., the XRD pattern preferably has only XRD peaks of zirconia. The powder of this embodiment more preferably has no XRD peaks of transition metal element compounds in its XRD pattern, and even more preferably has no XRD peaks of either stabilizing element compounds or transition metal element compounds in its XRD pattern.

[0083] The XRD peaks of zirconia in the XRD pattern of the powder of this embodiment may be XRD peaks of at least one of tetragonal, cubic, and monoclinic zirconia, and preferably have XRD peaks of at least tetragonal and cubic zirconia, and mainly include XRD peaks of tetragonal and cubic zirconia.

[0084] The T+C phase ratio of the powder of this embodiment may be 50% or more (0.5 or more), 55% or more, 60% or more, 90% or more, or 92% or more, and may be 99% or less (0.99 or less) or 95% or less. Preferred T+C phase ratios include 50% or more and 99% or less, 90% or more and 99% or less, or 92% or more and 99% or less.

[0085] The proportion of monoclinic crystals in the zirconia crystal phase in the powder of this embodiment (hereinafter also referred to as the "M phase proportion") is a value such that the sum of the T+C phase proportion and the M phase proportion is 1 (100%), and may be greater than 1% or greater than 5%, or may be less than 50%, less than 45%, less than 40%, or less than 10%.

[0086] The BET specific surface area of ​​the powder of this embodiment is 8m 2 / g or more, 9m 2 / g or more, 9.5m 2 / g or more or 10m 2 / g or more, and 15m 2 / g or less, 14m 2 / g or less or 13m 2 / g or less. A calcined body having a hardness suitable for CAD / CAM processing for producing dental prosthetic materials can be easily obtained, and therefore a preferred BET specific surface area is 8 m 2 / g or more 15m 2 / g or less, 9m 2 / g or more 14m 2 / g or less, 10m 2 / g or more 13m 2 / g or less, or 10m 2 / g or more 12m 2 / g or less.

[0087] The powder of this embodiment may have an average particle size of 0.35 μm or more, or 0.4 μm or more, and 0.55 μm or less, or 0.5 μm or less. Preferred average particle sizes are, for example, 0.35 μm or more and 0.55 μm or less, or 0.4 μm or more and 0.5 μm or less.

[0088] The powder of this embodiment has a loose bulk density of 1.10 g / cm 3 or more than 1.15g / cm 3 It is sufficient if it is 1.40 g / cm or more. 3 Less than or equal to 1.35g / cm 3 The preferred bulk density is 1.10 g / cm 3 More than 1.40g / cm 3 Below 1.20g / cm 3 More than 1.30g / cm 3 or less, or 1.25 g / cm 3 More than 1.30g / cm 3 The following are included:

[0089] The powder of this embodiment may be a powder containing at least one of powder particles and granular particles, or may be a powder containing granular particles as the main component. The primary particles and secondary particles constituting the powder particles may have any shape, and examples thereof include one or more shapes selected from the group consisting of amorphous, approximately spherical, and approximately polygonal.

[0090] The powder of this embodiment is preferably a granular powder. Granular powders improve moldability and operability. Granular powders having an average granule particle size of 30 μm or more and 80 μm or less, and even 40 μm or more and 50 μm or less, can be exemplified.

[0091] Compared to conventional zirconia powders containing transition metal elements, the powder of this embodiment preferably suppresses shrinkage during calcination, i.e., during heat treatment below the sintering temperature, despite containing a transition metal element. 3.0 g of the powder is filled into a mold having a diameter of 25 mm, uniaxially pressed at a pressure of 49 MPa, and then subjected to CIP treatment at a pressure of 196 MPa to obtain a disk-shaped molded body, which is then calcined under the following conditions to form a calcined body. In this case, the shrinkage rate calculated from the following formula is preferably less than 4.0%, and more preferably 3.9% or less, and even more preferably 3.7% or less. Calcining temperature: 1000℃ Pre-baking time: 1 hour Heating rate: 50°C / hour Calcination atmosphere: air Cooling rate: 300℃ / hour

[0092] Shrinkage rate [%] = {(25 - diameter of calcined body) [mm] / 25 [mm]} x 100 ···(1) The calcined body thus obtained has a disk shape with a diameter of 25 mm or less and a thickness of 2±0.5 mm. In formula (1), the diameter of the calcined body can be measured by a known method, and the average value of the values ​​obtained by measuring the length of the disk in the diametric direction at four points using a vernier caliper can be used.

[0093] The powder of this embodiment may have a shrinkage rate of 3.0% or more, 3.3% or more, or 3.5% or more. Preferred shrinkage rates are 3.0% or more and less than 4.0%, 3.3% or more and 3.9% or less, or 3.5% or more and 3.9% or less, for example.

[0094] The powder of this embodiment can be used in known applications of zirconia powder, and can be used, for example, as a precursor of a sintered body used for one or more applications selected from the group consisting of structural materials, optical materials, decorative materials, dental materials, communication materials, and biomaterials, and is further suitable as a precursor of a dental material, or a precursor of a dental prosthetic material, or a precursor for at least one of dental prosthetic materials such as a crown and a bridge.

[0095] <Powder manufacturing method> The powder of this embodiment may be produced by any method as long as it has the above-described configuration. A preferred method for producing the powder of this embodiment includes a step of drying a composition containing hydrated zirconia, a stabilizing element source, a transition metal element source, and a solvent to obtain a dried powder, and a step of heat-treating the dried powder at a temperature lower than the sintering temperature to obtain a calcined powder.

[0096] The manufacturing method of this embodiment includes a step of drying a composition containing hydrated zirconia, a stabilizing element source, a transition metal element source, and a solvent to obtain a dry powder (hereinafter also referred to as the "drying step"). This removes the water of hydration and the solvent of hydrated zirconia (ZrO2·nH2O; where n is an integer) from the composition, yielding a dry powder (zirconia powder containing a stabilizing element source and a transition metal element source, i.e., a powder containing a stabilizing element source and a transition metal element source and composed mainly of zirconia).

[0097] In the drying process, hydrated zirconia is allowed to coexist with a stabilizing element source and a transition metal element source, and then dried. This significantly suppresses the formation of sparingly soluble transition metal element compounds associated with the formation of hydrated zirconia, unlike the process of mixing a hydrated zirconia precursor with a transition metal element source to produce hydrated zirconia. Therefore, even when the transition metal element source is present in an amount of 0.05 mass% or more, or even 0.1 mass% or more, aggregation of sparingly soluble transition metal elements is unlikely to occur, resulting in a calcined body with uniform processability. The dried powder obtained through the drying process is believed to have very little localization of the stabilizing element and the transition metal element. Furthermore, the transition metal element can be allowed to coexist with zirconia prior to the solid solution of the stabilizing element in zirconia by heat treatment. These factors significantly suppress the aggregation of the transition metal element in the dry powder, compared to a dry powder obtained by mixing a transition metal element source with a dry powder consisting of a stabilizing element source and zirconia.

[0098] The drying step is performed using a composition (hereinafter also referred to as a "raw material composition") containing hydrated zirconia, a stabilizing element source, a transition metal element source, and a solvent. The amounts of hydrated zirconia, stabilizing element, and transition metal element contained in the raw material composition may be the same as those in the powder composition described above.

[0099] The content of the stabilizing element source in the raw material composition can be, for example, 2 mol% or more or 2.5 mol% or more and 15 mol% or less or 7.5 mol% or less, and preferably 2 mol% to 15 mol%, 2.5 mol% to 15 mol%, or 3.5 mol% to 5.9 mol%. For example, when the stabilizing element source is an yttrium source, the amount of the stabilizing element source (yttrium source amount) can be 3 mol% to 3.3 mol%, 3.5 mol% to 3.6 mol% or more and 6.5 mol% to 6 mol%, 5.5 mol% to 5.2 mol% or less. Preferred amounts of the stabilizing element source include 2 mol% to 6.5 mol%, 3 mol% to 6.5 mol%, 3 mol% to 6.5 mol%, 3.3 mol% to 6 mol%, 3.5 mol% to 5.5 mol%, 3.6 mol% to 5.1 mol%, or 4.8 mol% to 5.5 mol%.

[0100] The content of the transition metal element source in the raw material composition can be, for example, more than 0% by mass, 0.01% by mass or more, 0.04% by mass or more, or 0.1% by mass or more, and 3% by mass or less, 2% by mass or less, less than 2% by mass, 1% by mass or less, or 0.5% by mass or less. Preferred transition metal amounts include more than 0% by mass and 3% by mass or less, 0.01% by mass or more and 3% by mass or less, 0.04% by mass or more and 2% by mass or less, 0.04% by mass or more and 2% by mass or less, or 0.1% by mass or more and 2% by mass or less.

[0101] The pH of the raw material composition is preferably 7 or less, more preferably 1 or more or 3 or more, and more preferably 7 or less or 5 or less, in order to make it easier to disperse hydrated zirconia.

[0102] The hydrated zirconia is preferably hydrated zirconia obtained by one or more methods selected from the group consisting of hydrolysis, coprecipitation, and neutralization of a zirconium salt, more preferably hydrated zirconia obtained by hydrolysis, and even more preferably hydrated zirconia obtained by hydrolysis. Examples of the zirconium salt to be subjected to hydrolysis or the like include one or more selected from the group consisting of zirconium oxychloride, zirconyl nitrate, zirconium chloride, and zirconium sulfate, and zirconium oxychloride is preferred.

[0103] The hydrated zirconia is preferably contained in the raw material composition as a hydrated zirconia sol.

[0104] The stabilizing element source (hereinafter, when the stabilizing element is yttrium or the like, it may be referred to as an "yttrium source" or the like) may be at least any one of a salt and a compound containing the stabilizing element, and may be one or more selected from the group consisting of oxides, hydroxides, oxyhydroxides, halides, carbonates, sulfates, nitrates, and acetates containing the stabilizing element. It is preferable that the stabilizing element source be at least one selected from the group consisting of oxides, hydroxides, oxyhydroxides, and chlorides containing the stabilizing element, and more preferably at least any one of hydroxides and chlorides containing the stabilizing element. Furthermore, the stabilizing element source may be a solution containing at least any one of the salts and compounds of the stabilizing element. The solvent in the solution may be at least any one of alcohol and water, and preferably water.

[0105] Examples of the yttrium source include one or more selected from the group consisting of yttrium oxide, yttrium hydroxide, yttrium oxyhydroxide, yttrium chloride, yttrium carbonate, yttrium sulfate, yttrium nitrate, and yttrium acetate, further one or more selected from the group consisting of yttrium oxide, yttrium hydroxide, yttrium oxyhydroxide, and yttrium chloride, and further at least one of yttrium oxide and yttrium chloride.

[0106] Examples of the erbium source include one or more selected from the group consisting of erbium oxide, erbium hydroxide, erbium oxyhydroxide, erbium chloride, erbium carbonate, erbium sulfate, erbium nitrate, and erbium acetate, further one or more selected from the group consisting of erbium oxide, erbium hydroxide, erbium oxyhydroxide, and erbium chloride, and further at least one of erbium oxide and erbium chloride.

[0107] Examples of the terbium source include one or more selected from the group consisting of terbium oxide, terbium hydroxide, terbium oxyhydroxide, terbium chloride, terbium carbonate, terbium sulfate, terbium nitrate, and terbium acetate, further one or more selected from the group consisting of terbium oxide, terbium hydroxide, terbium oxyhydroxide, and terbium chloride, and further at least one of terbium oxide and terbium chloride.

[0108] Examples of calcium sources include one or more selected from the group consisting of calcium oxide, calcium hydroxide, calcium oxyhydroxide, calcium chloride, calcium carbonate, calcium sulfate, calcium nitrate, and calcium acetate, further one or more selected from the group consisting of calcium oxide, calcium hydroxide, calcium oxyhydroxide, and calcium chloride, and further at least one of calcium oxide and calcium chloride.

[0109] Examples of the magnesium source include one or more selected from the group consisting of magnesium oxide, magnesium hydroxide, magnesium oxyhydroxide, magnesium chloride, magnesium carbonate, magnesium sulfate, magnesium nitrate, and magnesium acetate, further one or more selected from the group consisting of magnesium oxide, magnesium hydroxide, magnesium oxyhydroxide, and magnesium chloride, and further at least one of magnesium oxide and magnesium chloride.

[0110] The raw material composition includes a transition metal element source (hereinafter, when the transition metal element is iron or the like, it is also referred to as an "iron source" or the like). The transition metal element included in the transition metal element source may be any of the transition metal elements described above. This suppresses coarse aggregation of the transition metal element compared to when the transition metal element source is mixed with zirconia powder or zirconia powder containing a stabilizing element.

[0111] The transition metal element source may be at least one of a salt and a compound of a transition metal element that dissolves in the solvent of the raw material composition. Examples of the transition metal element source include at least one selected from the group consisting of oxides, hydroxides, oxyhydroxides, halides, carbonates, sulfates, nitrates, and acetates of the transition metal elements. Preferably, the transition metal element source is at least one selected from the group consisting of hydroxides, oxyhydroxides, chlorides, and acetates of the transition metal elements, and more preferably at least one of the oxides and chlorides of the transition metal elements. Furthermore, the transition metal element source may be a solution containing at least one of the salts and compounds of the transition metal elements. The solvent for the solution may be at least one of alcohol and water, and preferably water. The transition metal element source may be a salt or compound containing at least one of a 3d transition metal element and a 4d transition metal element other than zirconium. For example, the transition metal element source may be at least one selected from the group consisting of titanium sources, chromium sources, manganese sources, iron sources, cobalt sources, nickel sources, and copper sources, and more preferably titanium sources, chromium sources, manganese sources, iron sources, cobalt sources, nickel sources, and copper sources. Preferred transition metal sources include one or more selected from the group consisting of a manganese source, an iron source, a cobalt source, and a nickel source, further including at least one of a manganese source, an iron source, a cobalt source, or a nickel source, further including at least one of a cobalt source and an iron source, further including a cobalt source and an iron source, and further including an iron source.

[0112] Examples of titanium sources include one or more selected from the group consisting of titanium oxide (TiO2), titanium hydroxide (Ti(OH)2), titanium oxyhydroxide (TiOOH), titanium chloride (II) (TiCl2), titanium chloride (III) (TiCl3), titanium chloride (IV) (TiCl4), titanium sulfate (TiSO4), titanium nitrate (Ti(NO3)2), and titanium acetate (TiCOOH).

[0113] Examples of chromium sources include one or more selected from the group consisting of chromium oxide (II) (CrO), chromium oxide (III) (CrO), chromium dioxide (CrO), trichromium tetroxide (CrO), chromium oxyhydroxide (CrOOH), chromium chloride (II) (CrCl), chromium chloride (III) (CrCl), chromium carbonate (Cr(CO)), chromium sulfate (CrSO), chromium nitrate (Cr(NO)), and chromium acetate (Cr(COOH)). Examples of chromium sources include at least one selected from the group consisting of chromium hydroxide and chromium acetate.

[0114] Examples of manganese sources include one or more selected from the group consisting of manganese (II) oxide (MnO), manganese (III) oxide (MnO), manganese dioxide (MnO), trimanganese tetroxide (MnO), manganese hydroxide (Mn(OH)), manganese oxyhydroxide (MnOOH), manganese chloride (MnCl), manganese carbonate (MnCO), manganese sulfate (MnSO), manganese nitrate (Mn(NO)), and manganese acetate (Mn(COOH)), further one or more selected from the group consisting of manganese oxide, manganese dioxide, trimanganese tetroxide, manganese hydroxide, and manganese acetate, and further one or more selected from the group consisting of manganese dioxide, trimanganese tetroxide, and manganese hydroxide, and further trimanganese tetroxide.

[0115] The iron source may be, for example, one or more selected from the group consisting of iron oxide (II) (FeO), iron oxide (III) (Fe2O3), iron tetroxide (Fe3O4), iron hydroxide (II) (Fe(OH)2), iron hydroxide (III) (Fe(OH)3), iron chloride (II) (FeCl2), iron chloride (III) (FeCl3), and iron carbonate (FeCO3). Preferably, the iron source is one or more selected from the group consisting of iron hydroxide (III), iron hydroxide (II), iron chloride (III), and iron chloride (II), and more preferably iron chloride (III).

[0116] Examples of the cobalt source include one or more selected from the group consisting of cobalt(II) oxide (CoO), cobalt(IV) oxide (CoO), tricobalt tetroxide (CoO), cobalt hydroxide (Co(OH)), cobalt oxyhydroxide (CoOOH), cobalt chloride (CoCl), cobalt carbonate (CoCO), cobalt sulfate (CoSO), cobalt nitrate (Co(NO)), and cobalt acetate (CoCOOH). Of these, one or more selected from the group consisting of cobalt(II) oxide, cobalt(IV) oxide, and tricobalt tetroxide is preferred, and tricobalt tetroxide is more preferred.

[0117] The nickel source may, for example, be one or more selected from the group consisting of nickel oxide (II) (NiO), nickel oxide (IV) (NiO2), nickel trioxide (Ni3O4), nickel hydroxide (Ni(OH)2), nickel oxyhydroxide (NiOOH), nickel chloride (NiCl2), nickel carbonate (NiCO3), nickel sulfate (NiSO4), nickel nitrate (Ni(NO3)2), and nickel acetate (NiNIOH). Of these, one or more selected from the group consisting of nickel oxide (II), nickel oxide (IV), and nickel hydroxide is preferred, and nickel oxide (II) is more preferred.

[0118] Examples of the copper source include one or more selected from the group consisting of copper (II) oxide (CuO), copper (IV) oxide (CuO), copper trioxide (CuO), copper hydroxide (Cu(OH)), copper oxyhydroxide (CuOOH), copper chloride (CuCl), copper carbonate (CuCO), copper sulfate (CuSO), copper nitrate (Cu(NO)), and copper acetate (CuCUOH).

[0119] The raw material composition may be any composition containing a solvent, in which hydrated zirconia, a stabilizing element source, and a transition metal element source are dispersed, and may be considered as a so-called hydrated zirconia solution, an aqueous hydrated zirconia solution, or even a hydrated zirconia slurry.

[0120] The solvent may be any solvent in which hydrated zirconia can be dispersed, and may be at least one of a polar solvent and a nonpolar solvent. At least one of an alcohol and water, preferably at least one of ethanol and water, or even water, is preferred. Examples of water contained in the raw material composition include at least one of pure water and ion-exchanged water. Furthermore, in the drying step, a solution containing hydrated zirconia obtained by one or more methods selected from the group consisting of hydrolysis, coprecipitation, and neutralization of a zirconium salt and a solvent for the hydrated zirconia may be used as the hydrated zirconia and solvent.

[0121] The raw material composition may be produced by any method that allows for uniform mixing of hydrated zirconia, a stabilizing element source, and a transition metal element source. Examples of such methods include: (1) mixing hydrated zirconia, a stabilizing element source, a transition metal element source, and a solvent; (2) mixing a hydrated zirconia solution with a stabilizing element source and a transition metal element source; (3) mixing a hydrated zirconia solution with a solution containing a stabilizing element source and a solution containing a transition metal element source; (4) mixing a hydrated zirconia solution with a solution containing a stabilizing element source and a transition metal element source; and (5) mixing a hydrated zirconia solution with a solution containing a stabilizing element source and a transition metal element source. As a method for producing the raw material composition, which is likely to result in high dispersibility of the transition metal element source, a method including a step of mixing a hydrated zirconia solution, a solution containing a transition metal element source, and a stabilizing element source, and a method including a step of mixing a hydrated zirconia solution obtained by hydrolyzing a zirconium salt, a solution containing a transition metal element source, and a stabilizing element source can be given as a preferable method.

[0122] The drying method in the drying step may be any method that can remove the solvent and the water of hydration of the hydrous zirconia from the raw material composition. The drying conditions include the following: Dry atmosphere: Air atmosphere, preferably air circulating atmosphere Drying temperature: 150°C or higher, 160°C or higher, or 180°C or higher, and 210℃ or less, 200℃ or less, or 190℃ or less

[0123] The drying time of the raw material composition may be appropriately set depending on the amount of the raw material composition to be subjected to the drying step and the characteristics of the drying oven, and may be, for example, 5 hours or more or 10 hours or more, and 75 hours or less or 50 hours or less.

[0124] Preferred drying conditions are: Dry atmosphere: Air Drying temperature: 160℃ or higher and 200℃ or lower Examples include:

[0125] The manufacturing method of this embodiment includes a step of heat-treating the dried powder at a temperature lower than the sintering temperature to obtain a calcined powder (hereinafter also referred to as the "powder calcination step"). The powder calcination step allows the stabilizing element to efficiently dissolve in zirconia. In addition, by undergoing this thermal history before forming into a compact (compressed powder), aggregation of the transition metal element during heat treatment after compaction is suppressed.

[0126] In the powder calcination step, the dried composition is heat-treated at a heat treatment temperature below the sintering temperature. The heat treatment temperature may be any temperature that promotes the dissolution of the stabilizing element into zirconia, and any temperature below the sintering temperature may be applied depending on the desired BET specific surface area. The higher the heat treatment temperature, the lower the BET specific surface area tends to be. Examples of such heat treatment temperatures include 1200°C or lower, less than 1200°C, and 1150°C or lower. To further promote the dissolution of the stabilizing element into zirconia, the heat treatment temperature is preferably 1000°C or higher, 1025°C or higher, or 1050°C or higher. To prevent local aggregation of the transition metal element during sintering, the heat treatment temperature is preferably 1025°C or higher, 1075°C or higher, or 1100°C or higher.

[0127] The heat treatment conditions other than the heat treatment temperature may be set so as to promote the solid solution of the stabilizing element in zirconia, and the following conditions can be exemplified. Heat treatment atmosphere: oxidizing atmosphere, preferably air atmosphere; Heat treatment temperature: 1000°C or higher, over 1000°C, 1025°C or higher, 1050°C or higher, or 1100°C or higher, and 1200℃ or less or 1150℃ or less

[0128] The air atmosphere is, for example, a nitrogen atmosphere mainly composed of nitrogen and oxygen, with an oxygen concentration of 18 to 23% by volume, and may contain moisture.

[0129] The heat treatment time may be adjusted as appropriate depending on the amount of dry powder to be subjected to the heat treatment and the characteristics of the heat treatment furnace used, but examples include 30 minutes or more or 1 hour or more and 10 hours or less or 5 hours or less.

[0130] Preferred heat treatment conditions are as follows: Heat treatment atmosphere: Air Heat treatment temperature: 1075°C to 1150°C, or 1100°C to 1150°C Examples include:

[0131] The calcined powder obtained in the powder calcination step may be used as the powder of this embodiment.

[0132] The manufacturing method of this embodiment may, if necessary, include at least one of a step of pulverizing the calcined powder (hereinafter also referred to as the "pulverizing step") and a step of granulating the calcined powder to obtain granular powder (hereinafter also referred to as the "granulation step").

[0133] In the pulverization step, the calcined powder is pulverized. This allows the particle size of the powder to be adjusted. The pulverization can be performed by any method that allows the calcined powder to have the desired particle size, and can be at least one of dry pulverization and wet pulverization. Due to high pulverization efficiency, wet pulverization is preferred, as well as pulverization using one or more devices selected from the group consisting of a vibration mill, a ball mill, and a bead mill, and further pulverization using a ball mill and a bead mill, and further ball milling is preferred.

[0134] The pulverization time may be appropriately set depending on the amount of calcined powder to be subjected to the pulverization step and the pulverization method. The longer the pulverization time, the smaller the particle size becomes until equilibrium is reached.

[0135] Instead of or in addition to the drying step, the calcined powder and the source of the additive component may be mixed in at least one of the pulverization step and the granulation step, or the calcined powder and the source of the additive component may be mixed in the pulverization step.

[0136] When producing a powder containing an additive component such as alumina, the additive component and / or its precursor (hereinafter also referred to as the "additive component source," and when the additive component source is alumina or the like, also referred to as the "alumina source," etc.) may be mixed in one or more steps selected from the group consisting of a drying step, a powder calcination step, a pulverization step, and a granulation step. It is preferable to mix the additive component source into at least one of the raw material composition to be subjected to the drying step and the calcined powder to be subjected to the pulverization step, and it is more preferable to mix the additive component source into the calcined powder to be subjected to the pulverization step.

[0137] Examples of sources of the additive component include the additive component, its hydrate and sol, and one or more selected from the group consisting of hydroxides, halides, sulfates, nitrates, and acetates containing one or more selected from the group consisting of aluminum (Al), silicon (Si), and germanium (Ge).

[0138] The alumina source may be at least one selected from the group consisting of alumina, hydrated alumina, alumina sol, aluminum hydroxide, aluminum chloride, aluminum nitrate, and aluminum sulfate, with alumina being preferred.

[0139] The amount of the additive component source contained in the raw material composition may be the same as the amount of the additive component described above, for example, 0% by mass or more, more than 0% by mass, 0.005% by mass or more, 0.01% by mass or more, or 0.03% by mass or more, and less than 0.2% by mass, less than 0.15% by mass, less than 0.1% by mass, or 0.08% by mass or less. Preferred amounts of the additive component source include 0% by mass or more and less than 0.2% by mass, 0% by mass or more and less than 0.1% by mass, or more than 0.08% by mass or less.

[0140] The amount of the source of the additional component may be determined as the ratio [mass %] of the additional component [g] calculated as an oxide to the total [g] of zirconia, the stabilizing element calculated as an oxide, and the metal element calculated as an oxide in the raw material composition.

[0141] In the granulation step, the calcined powder (or the calcined powder after the pulverization step, if a pulverization step is included) is granulated to obtain a granulated powder. This makes it possible to control the flowability of the powder and further improve the moldability of the powder. Granulation can be performed by any granulation method that allows the powder to slowly aggregate to form a granulated powder, and an example of this is spray granulation.

[0142] In the spray granulation method, the calcined powder (or the calcined powder after the pulverization step, if any) is dispersed in a solvent to obtain a slurry, which is then granulated. If necessary, the slurry may contain the above-mentioned binder to obtain a granular powder exhibiting the desired moldability.

[0143] <Calcined and sintered bodies> The powder of this embodiment can be used as a precursor for at least one of a calcined body and a sintered body.

[0144] The calcined body is obtained by a method for producing a calcined body, which includes a step of calcining a molded body containing the powder of this embodiment (hereinafter also referred to as the "calcining step"). The sintered body is obtained by a method for producing a sintered body, which includes a step of sintering at least one of a molded body containing the powder of this embodiment and a calcined body obtained by calcining the molded body (hereinafter also referred to as the "sintering step").

[0145] The molded body to be subjected to at least one of the calcination process and the sintering process (hereinafter also referred to as the "calcination process, etc.") is a molded body containing the powder of this embodiment, or further a molded body whose main component is the powder of this embodiment, and is preferably a molded body made of the powder of this embodiment.

[0146] The shape of the molded body may be one or more selected from the group consisting of disk, cube, rectangular parallelepiped, polyhedron, approximately polyhedron, cylinder, and cone, or any other shape depending on the purpose and use.

[0147] The measured density of the compact is 2.4 g / cm 3 or more than 3.1g / cm 3 and 3.7 g / cm 3 Less than or equal to 3.5g / cm 3 For example, the measured density of the compact to be subjected to the calcination step is 2.4 g / cm 3 More than 3.7g / cm 3 or less than 3.2 g / cm 3 More than 3.5g / cm 3 The following are included:

[0148] The green compact can be produced by a production method including a step of compacting the powder of this embodiment. The compacting method may be any compacting method capable of compacting the powder of this embodiment, and examples thereof include one or more methods selected from the group consisting of uniaxial pressing, cold isostatic pressing (hereinafter also referred to as "CIP"), slip casting, sheet molding, slip casting, and injection molding. One or more methods selected from the group consisting of slip casting, injection molding, uniaxial pressing, and CIP are preferred. For simplicity, the compacting method is preferably at least one of uniaxial pressing and CIP, and more preferably a method in which the powder of this embodiment is uniaxially pressed and the resulting primary green compact is CIP-treated. The pressure in uniaxial pressing is 15 MPa or more and 150 MPa or less, and the pressure in CIP is 90 MPa or more and 400 MPa or less.

[0149] The calcined body may be any composition in which a compact is heat-treated at a temperature below the sintering temperature, and is a composition having a fixed shape composed of fused particles of the powder of this embodiment. The calcined body obtained from the powder of this embodiment is less susceptible to temperature variations in the sintering furnace than calcined bodies obtained from conventional powders. As a result, even when multiple calcined bodies are sintered at once, the difference in color tone between the resulting sintered bodies tends to be small. For example, the chroma C between sintered bodies obtained by sintering the calcined bodies in the same lot is * The color difference is 0 or more and 0.1 or less, 0 or more and 0.08 or less, more than 0 and 0.08 or less, or 0.01 or more and 0.07 or less.

[0150] The measured density of the calcined body was 2.3 g / cm 3 or more than 3.0g / cm 3 and 3.6 g / cm 3 Less than or equal to 3.4g / cm 3 The preferred measured density of the calcined body is 3.0 g / cm. 3 More than 3.4g / cm 3 or less than 3.3 g / cm 3 More than 3.4g / cm 3 The following can be given as examples.

[0151] The Vickers hardness of the calcined body is 20HV (=kgf / mm 2 ) or more, 25HV or more, 30HV or more, or 50HV or more, and 70HV or less, 65HV or less, or 60HV or less. In order to have suitable processability when subjected to CAD / CAM processing for dental prosthetic materials, preferred Vickers hardness is 50HV or more and 70HV or less, 50HV or more and 65HV or less, or 50HV or more and 60HV or less.

[0152] The crystalline phase of the calcined body preferably has at least one of tetragonal and cubic crystals as the main phase.

[0153] The calcination method may be any method that can produce a calcined body having the desired properties. The following methods and conditions can be exemplified. Calcination atmosphere: an atmosphere other than a reducing atmosphere, preferably an oxidizing atmosphere, more preferably an air atmosphere Calcination temperature: 800°C or higher, 900°C or higher, or 950°C or higher, and 1200℃ or less, 1150℃ or less, or 1100℃ or less Heating rate: 10°C / hour or more or 30°C / hour or more, and 120℃ / hour or less or 80℃ / hour or less

[0154] The holding time at the calcination temperature (hereinafter also referred to as "calcination time") may be adjusted appropriately depending on the size and amount of the molded body to be subjected to calcination and the characteristics of the calcination furnace, and may be, for example, 0.5 hours or more, 1 hour or more, and 7 hours or less, or 3 hours or less.

[0155] Preferable calcination conditions are as follows: Calcination atmosphere: Air Calcining temperature: 900℃ or higher and 1100℃ or lower Examples include:

[0156] The sintered body is obtained by sintering at least one of a compact and a calcined body (hereinafter also referred to as "a compact, etc.").

[0157] The total light transmittance of the sintered body may be any value that allows visual recognition of the desired color tone, and examples thereof include 10% or more, 15% or more, or 25% or more, and 40% or less, 35% or less, or 30% or less.

[0158] The color tone of the sintered body may be any desired color tone, and the color tone that is visually recognized varies depending on the light transmittance, but examples thereof include one or more colors selected from the group consisting of yellow, green, gray, and blue. For example, as a yellow color tone within the above-mentioned range of total light transmittance, the following L * , a * and b * Examples of color tones that satisfy the above criteria include: L * : 55 or more, 60 or more, or 63 or more, and 85 or less, 80 or less, or 77 or less a * : -5 or more, -4 or more, or -3 or more, and 7 or less, 6 or less, or 5 or less b * : 5 or more, 6 or more, or 7 or more, and 35 or less, 30 or less, or 25 or less

[0159] The three-point bending strength of the sintered body is, for example, 550 MPa or more, 600 MPa or more, or 800 MPa or more, and 1250 MPa or less, less than 1200 MPa, less than 1100 MPa, or 1000 MPa or less. Since the sintered body can be used as a dental prosthetic material, the three-point bending strength is preferably 600 MPa or more and 1200 MPa or less.

[0160] Any sintering method can be applied as long as the sintering of the molded body etc. progresses, and at least one sintering method selected from the group consisting of pressure sintering, vacuum sintering and atmospheric sintering may be used. However, when producing a sintered body suitable for a dental prosthesis, atmospheric sintering is preferred. An atmospheric sintered body can be obtained by atmospheric sintering.

[0161] The conditions for atmospheric sintering are exemplified as follows. Heat treatment atmosphere: an atmosphere other than a reducing atmosphere, preferably an oxidizing atmosphere, More preferably, the air atmosphere Heat treatment temperature: over 1200°C, 1300°C or more, or 1400°C or more, and 1600℃ or less, 1550℃ or less, or 1500℃ or less

[0162] The holding time at the heat treatment temperature may be set arbitrarily depending on the size and amount of the molded body to be sintered, the heat treatment temperature, and the characteristics of the sintering furnace, and may be, for example, 30 minutes or more, 1 hour or more, and 5 hours or less, 3 hours or less, or 2.5 hours or less.

[0163] The rate of temperature rise to the heat treatment temperature is, for example, 50° C. / hour or more, 100° C. / hour or more, or 150° C. / hour or more, and 800° C. / hour or less, or 700° C. / hour or less.

[0164] When sintering is performed using a sintering furnace capable of sintering in a short time, the holding time at the heat treatment temperature is, for example, 1 minute or more or 5 minutes or more, and 1 hour or less or 30 minutes or less. In this case, the rate of temperature rise to the heat treatment temperature is, for example, 30°C / min or more or 50°C / min or more, and, for example, 300°C / min or 250°C / min. <Additional Notes> The gist of the present disclosure may be considered to be any one or more selected from the following groups [1'] to [14']. [1'] A zirconia powder containing a stabilizing element and a transition metal element, wherein 3.0 g of the powder is filled into a mold having a diameter of 25 mm, uniaxially pressed at a pressure of 49 MPa, and then subjected to CIP treatment at a pressure of 196 MPa to obtain a disk-shaped compact, which is then calcined under the following conditions to form a calcined body. The calcined body has a shrinkage rate calculated from the following formula of less than 4.0%. Calcining temperature: 1000℃ Pre-baking time: 1 hour Heating rate: 50°C / hour Calcination atmosphere: air Cooling rate: 300℃ / hour Shrinkage rate [%] = {(25 - diameter of calcined body) [mm] / 25 [mm]} x 100 ···(1) [2'] The powder according to the above [1'], wherein the transition metal element is at least one of a 3d transition metal element and a 4d transition metal element other than zirconium. [3'] The powder according to the above [1'], wherein the transition metal element is nickel, cobalt, manganese or iron. [4'] The powder according to [1'] above, wherein the transition metal element is iron. [5'] The powder according to any one of [1'] to [4'] above, wherein the content of the transition metal element is more than 0 mass%, 0.01 mass% or more, or 0.04 mass% or more. [6'] The powder according to any one of [1'] to [5'] above, wherein the stabilizing element is yttrium (Y). [7'] The powder according to any one of the above [1'] to [6'], wherein the content of the stabilizing element is 3.5 mol % or more and 5.5 mol % or less. [8'] BET specific surface area is 8m 2 / g or more 15m 2 The powder according to any one of [1'] to [7'] above, wherein the solubility is 0.01% or less. [9'] Lightly packed bulk density is 1.10 g / cm 3 More than 1.40g / cm3 The powder according to any one of the above [1'] to [8'], which is as follows: [10'] The powder according to any one of [1'] to [9'] above, which is a granular powder. [11'] The powder according to any one of the above [1'] to [10'], wherein in a frequency distribution of element ratios in which the transition metal element / zirconium ratio is plotted at intervals of 0.005, the difference between the minimum and maximum values ​​of the transition metal element / zirconium ratio is less than 0.25. [12'] A method for producing a powder according to any one of the above [1'] to [11'], comprising the steps of drying a composition containing hydrated zirconia, a stabilizing element source, a transition metal element source, and a solvent in an air atmosphere at a drying temperature of 160°C to 200°C to obtain a dry powder, and heat-treating the dried powder at 1200°C or less to obtain a calcined powder, wherein the stabilizing element source is an yttrium source, the transition metal element source is a salt or compound containing at least one of a 3d transition metal element and a 4d transition metal element other than zirconium, and the solvent is water. [13'] A molded body comprising the powder according to any one of [1'] to [11'] above. [14'] A method for producing a calcined body, comprising a step of calcining the molded body according to [13'] above. [15'] A method for producing a sintered body, comprising a step of sintering at least one of a molded body containing the powder according to any one of [1'] to [11'] above and a calcined body obtained by calcining the molded body. [Example]

[0165] The present disclosure will be described in detail below with reference to examples, but the present disclosure is not limited to these examples.

[0166] (composition analysis) The composition was measured by ICP analysis. As a pretreatment for the analysis, the sample powder was heat-treated in air at 1000°C for 1 hour.

[0167] (BET specific surface area) The BET specific surface area was measured using an automatic specific surface area measuring device (device name: Tristar II 3020, manufactured by Shimadzu Corporation) by the BET 5-point method in accordance with JIS R 1626. The measurement conditions are shown below. Adsorption medium: N2 Adsorption temperature: -196℃ Pretreatment conditions: Degassing in air at 250°C for at least 1 hour

[0168] (Average particle size) The average particle size was measured by particle size distribution measurement using a Microtrac particle size distribution analyzer (device name: MT3300EXII, manufactured by Microtrac Bell) using the laser diffraction / scattering method. The measurement conditions are as follows:

[0169] Light source: Semiconductor laser (wavelength: 780 nm) Voltage: 3mW Measurement sample: crushed slurry Refractive index of zirconia: 2.17 Refractive index of solvent (water): 1.333 Calculation mode: HRA As a pretreatment, the sample powder was suspended in distilled water to form a slurry, which was then dispersed for 3 minutes using an ultrasonic homogenizer (device name: US-150T, manufactured by Nippon Seiki Seisakusho).

[0170] (Measured density) Measured density [g / cm 3 ] is the sample volume [cm 3 The mass was calculated from the mass [g] relative to the mass [g] of the sample. The mass was determined by weighing the sample. For the green body and the calcined body, the volume was determined by shape measurement, and for the sintered body, the volume was determined by the Archimedes method in accordance with JIS R 1634. The Archimedes method used ion-exchanged water as the solvent, and pretreatment was performed by boiling.

[0171] (shrinkage rate) The powder shrinkage rate was measured using a calcined disk having a diameter of 25 mm or less and a thickness of 2±0.5 mm, which was produced by filling 3.0 g of the powder into a mold having a diameter of 25 mm, uniaxially pressing it at a pressure of 49 MPa, and then performing CIP treatment at a pressure of 196 MPa to obtain a disk-shaped compact. The calcined disk was calcined under the following conditions. Calcining temperature: 1000℃ Pre-baking time: 1 hour Heating rate: 50°C / hour Calcination atmosphere: air Cooling rate: 300℃ / hour;

[0172] Shrinkage rate [%] = {(25 - diameter of calcined body) [mm] / 25 [mm]} x 100 ···(1) The diameter of the calcined body was determined by measuring the length of the disk in the diametric direction at four points using a vernier caliper and averaging the values ​​obtained.

[0173] (Total light transmittance) The total light transmittance was measured using a haze meter (device name: NDH4000, manufactured by Nippon Denshoku Co., Ltd.) with a D65 light source according to the method in accordance with JIS K 7361-1. The measurement sample was a disk-shaped sintered body with a thickness of 1.0±0.1 mm, which had been polished on both sides to a surface roughness of Ra≦0.02 μm.

[0174] (color tone) The color tone was measured using a spectrophotometer (device name: CM-700d, manufactured by Konica Minolta) in SCI mode using a D65 light source. The measurement sample was a circular sintered body with a thickness of 1.0 ± 0.1 mm, polished on both sides to a surface roughness of Ra ≦ 0.02 μm. The measurement sample was placed on a black plate, and both polished surfaces were used as evaluation surfaces. The color tone (L * , a * and b * ) was measured (so-called black background measurement). * and b * to saturation C * asked for.

[0175] (three-point bending strength) The three-point bending strength was measured according to JIS R 1601. The measurement sample was a columnar shape with a width of 4 mm, a thickness of 3 mm, and a length of 45 mm. The measurement was performed with a support distance of 30 mm and a load applied horizontally to the measurement sample.

[0176] (Vickers hardness) Vickers hardness was measured using a Vickers tester (device name: Q30A, manufactured by Qness) under the following conditions: an indenter was statically pressed into the surface of the test sample, and the diagonal length of the indentation mark formed on the surface of the test sample was measured. The diagonal length obtained was used to calculate the Vickers hardness using the above-mentioned formula.

[0177] Measurement sample: Disc-shaped with a thickness of 3.0±0.5mm Measurement load: 1kgf Prior to the measurement, the calcined sample was ground to a depth of 0.1 mm with #800 waterproof abrasive paper.

[0178] (Element frequency distribution) The element frequency distribution was determined from the EPMA spectrum obtained using a wavelength dispersive electron microanalyzer (instrument name: EPMA1610, manufactured by Shimadzu Corporation) or a field emission wavelength dispersive electron microanalyzer (instrument name: JXA-iHP200F, manufactured by JEOL Ltd.) under the following conditions: Accelerating voltage: 15 kV Irradiation current: 50nA Beam diameter: 1 μm Capture time: 50 msec Magnification: 5000x Analysis area: 45.32μm×45.32μm~51.20μm×51.20μm

[0179] The powder sample was embedded in epoxy resin and then cut by ion milling. The cross section of the powder exposed after cutting was used as the observation surface, and gold (Au) was vapor-deposited onto this to prepare the measurement sample.

[0180] For the EPMA spectrum, the SEM observation image was divided into regions from 50,000 to 66,000, and each region was used as a measurement point. The M / Zr ratio was calculated from the intensities of characteristic X-rays of zirconium and transition metal elements (M) in the EPMA spectrum at each measurement point. The obtained M / Zr frequencies were plotted as described above to obtain an element frequency distribution. From the obtained element frequency distribution, the M / Zr range, minimum M / Zr value, maximum M / Zr value, high metal frequency, and low metal frequency were determined.

[0181] (Standard sample) A sintered body was prepared as a standard sample using commercially available zirconia powder. 3.0 g of commercially available zirconia powder (product name: Zpex, manufactured by Tosoh Corporation) was weighed out, filled into a mold with a diameter of 25 mm, and uniaxially pressed at a pressure of 19.6 MPa. After that, a CIP process was performed at a pressure of 196 MPa to obtain a disk-shaped compact.

[0182] The resulting molded body was calcined under the following conditions to obtain a calcined body. Calcining temperature: 1000℃ Pre-baking time: 1 hour Heating rate: 50°C / hour Calcination atmosphere: air Cooling rate: 300℃ / hour

[0183] The obtained calcined body was sintered under the following conditions to obtain a sintered body having a total light transmittance of 42%, which was used as a standard sample. Sintering method: Atmospheric pressure sintering Sintering temperature: 1450℃ Sintering time: 2 hours Heating rate: 600°C / hour Sintering atmosphere: Air

[0184] Example 1 A mixed aqueous solution was obtained by adding and mixing yttrium chloride to 5 L of an aqueous solution of hydrated zirconia obtained by hydrolyzing an aqueous solution of zirconium oxychloride so that the yttrium concentration was 4.0 mol%. After mixing, an aqueous solution of iron (III) chloride with an FeCl concentration of 45 mass% was added and mixed to the mixed aqueous solution so that the iron concentration was 0.2 mass% in terms of FeO, thereby obtaining a raw material composition (aqueous sol solution).

[0185] The raw material composition was dried at 180°C in an air atmosphere to remove moisture, and the resulting dried powder was fired at 1125°C in an air atmosphere to obtain a calcined powder (a powder of yttrium-containing zirconia containing 0.2 mass% of iron and having an yttrium content of 4.0 mol%).

[0186] The calcined powder (199.9 g), α-alumina powder (0.1 g), and pure water were mixed and ground in a ball mill using zirconia balls (2 mm diameter) as grinding media to obtain a slurry. An acrylic resin was added to the slurry so that the binder mass ratio relative to the powder mass in the slurry was 3 mass%, and the mixture was then spray-dried at 180°C in an air atmosphere to obtain a granular powder consisting of yttria-containing zirconia powder containing 3 mass% acrylic resin, 0.2 mass% iron, and 0.05 mass% alumina, with an yttrium content of 4.0 mol%, which was designated as the powder of this example.

[0187] 3.0 g of the obtained granular powder was filled into a mold having a diameter of 25 mm, and uniaxially pressed at a pressure of 49 MPa, and then subjected to CIP treatment at a pressure of 196 MPa to obtain a disk-shaped compact (green compact).

[0188] The measured density of the obtained compact was 3.32 g / cm 3 The compact was calcined under the following conditions to obtain the calcined body of this example. Calcining temperature: 1000℃ Pre-baking time: 1 hour Heating rate: 50°C / hour Calcination atmosphere: air Cooling rate: 300℃ / hour

[0189] Example 2 A granular powder consisting of yttria-containing zirconia powder containing 3 mass% of acrylic resin, 0.05 mass% of cobalt, and 0.05 mass% of alumina, and having an yttrium content of 4.0 mol%, was obtained in the same manner as in Example 1, except that tricobalt tetroxide was added instead of iron so that the cobalt concentration was 0.05 mass% in terms of Co3O4, and the calcination temperature was set to 1140°C. This was used as the powder of this example.

[0190] A compact and a calcined body were obtained in the same manner as in Example 1, except that the powder of this example was used. The measured density of the obtained compact was 3.30 g / cm. 3 It was.

[0191] Example 3 A granular powder consisting of yttria-containing zirconia powder containing 3 mass% of acrylic resin, 0.05 mass% of manganese, and 0.05 mass% of alumina, and having an yttrium content of 4.0 mol%, was obtained in the same manner as in Example 1, except that trimanganese tetroxide (Mn3O4) was added instead of iron so that the manganese concentration was 0.05 mass% in terms of Mn3O4, and the calcination temperature was set to 1140°C. This was used as the powder of this example.

[0192] A compact and a calcined body were obtained in the same manner as in Example 1, except that the powder of this example was used. The measured density of the obtained compact was 3.30 g / cm. 3 It was.

[0193] Example 4 A granular powder consisting of yttria-containing zirconia powder containing 3 mass% of acrylic resin, 0.05 mass% of nickel, and 0.05 mass% of alumina and having an yttrium content of 4.0 mol% was obtained in the same manner as in Example 1, except that nickel oxide (NiO) was added instead of iron chloride so that the nickel concentration was 0.05 mass% in terms of NiO, and the calcination temperature was set to 1140°C. This was used as the powder of this example.

[0194] A compact and a calcined body were obtained in the same manner as in Example 1, except that the powder of this example was used. The measured density of the obtained compact was 3.30 g / cm. 3 It was.

[0195] Comparative Example 1 A raw material composition was obtained in the same manner as in Example 1, except that no aqueous iron (III) chloride solution was added and the calcination temperature was set to 1175°C, and then this was dried and calcined to obtain a calcined powder.

[0196] The obtained calcined powder was mixed with iron (III) oxide hydroxide in a ball mill to obtain an yttria-containing zirconia powder containing 0.2 mass % of iron and 4.0 mol % of yttrium.

[0197] A granular powder consisting of yttria-containing zirconia powder containing 3 mass% of acrylic resin, 0.2 mass% of iron, and 0.05 mass% of alumina and having an yttrium content of 4.0 mol% was obtained in the same manner as in Example 1, except that 199.9 g of the obtained powder was used, and this was designated as the powder of this comparative example.

[0198] A compact and a calcined body were obtained in the same manner as in Example 1, except that the powder of this comparative example was used. The measured density of the obtained compact was 3.33 g / cm 3 It was.

[0199] Comparative Example 2 An yttria-containing zirconia powder containing 3 mass% of acrylic resin, 0.05 mass% of cobalt, and 0.05 mass% of alumina and having an yttrium content of 4.0 mol% was obtained in the same manner as in Comparative Example 1, except that tricobalt tetroxide (Co3O4) was used instead of iron oxide (III) hydroxide so that the cobalt content was 0.05 mass% in terms of Co3O4. This powder was designated as the powder of this Comparative Example.

[0200] A compact and a calcined body were obtained in the same manner as in Example 1, except that the powder of this comparative example was used. The measured density of the obtained compact was 3.30 g / cm 3 It was.

[0201] Comparative Example 3 An yttria-containing zirconia powder containing 3 mass% of acrylic resin, 0.05 mass% of manganese, and 0.05 mass% of alumina and having an yttrium content of 4.0 mol% was obtained in the same manner as in Comparative Example 1, except that manganese tetroxide (Mn3O4) was used instead of iron oxide (III) hydroxide so that the manganese content was 0.05 mass% calculated as Mn3O4. This powder was designated as the powder of this Comparative Example.

[0202] A compact and a calcined body were obtained in the same manner as in Example 1, except that the powder of this comparative example was used. The measured density of the obtained compact was 3.30 g / cm 3 It was.

[0203] The evaluation results of the powders of the Examples and Comparative Examples are shown in Tables 1 and 2.

[0204] [Table 1]

[0205] It was confirmed that Example 1 and Comparative Example 1, which contain iron as the transition metal element, Example 2 and Comparative Example 2, which contain cobalt as the transition metal element, and Example 3 and Comparative Example 3, which contain manganese as the transition metal element, each have similar powder properties.

[0206] Furthermore, the calcined bodies of the comparative examples had a larger shrinkage rate than the calcined bodies of the examples, demonstrating that calcination led to greater densification. This confirms that the powders of the examples had less thermal shrinkage during calcination than the powders of the comparative examples.

[0207] [Table 2]

[0208] From the above table, it can be seen that the powders of Examples 1 to 4 all have an M / Zr range of less than 0.25, or even 0.2 or less, and the transition metal elements are more uniformly dispersed than in the powders of the comparative examples. Furthermore, element mapping (iron mapping) of the powder transition metal element (iron) of Example 1 shows a nearly uniform distribution ( FIG. 4 ), confirming the absence of iron agglomerates. On the other hand, element mapping (iron mapping) of the powder transition metal element of Comparative Example 1 confirms numerous irregularly shaped spots, confirming the presence of iron agglomerates ( FIG. 5 ). Furthermore, similar to iron, it can be seen that cobalt ( FIG. 6 , Example 2), manganese ( FIG. 7 , Example 3), and nickel ( FIG. 8 , Example 4) are each uniformly distributed.

[0209] Table 3 shows the evaluation results of the calcined bodies of the examples and comparative examples.

[0210] [Table 3]

[0211] From the above table, it can be seen that the Vickers hardness of the calcined body obtained from the powder of the Example is 65 Hv or less, which is lower than the Vickers hardness of the calcined body obtained from the powder of Comparative Example 1. This shows that the powder of the Example can produce a calcined body with high workability.

[0212] Measurement example 1 (preparation of sintered body) Five calcined bodies were prepared in each of the examples and comparative examples using the same method. The calcined bodies were placed in an alumina sagger as shown in Figure 1 and placed in a sintering furnace, and sintered under the following conditions to obtain five sintered bodies for each example. Sintering method: Atmospheric pressure sintering Sintering temperature: 1500℃ Sintering time: 2 hours Heating rate: 600°C / hour Sintering atmosphere: Air

[0213] The results for the obtained sintered bodies are shown in the table below. The total light transmittance in the table below indicates the ratio of the total light transmittance of the example (or comparative example) to the value of the standard sample. Each value in the table below is the average value of five sintered bodies.

[0214] [Table 4]

[0215] Comparisons between Example 1 and Comparative Example 1, Example 2 and Comparative Example 2, and Example 3 and Comparative Example 3 confirm that the obtained sintered bodies all exhibit similar aesthetic properties and mechanical strength.

[0216] Next, the saturation C of five sintered bodies of the example and the comparative example was measured. * The standard deviation is shown in the table below.

[0217] [Table 5]

[0218] From the above table, the sintered body of the example is C compared to the sintered body of the comparative example. * The standard deviation of the sintering furnace is small. It was confirmed that the color change due to the temperature distribution (temperature unevenness) was small, and it was confirmed that sintered bodies exhibiting similar aesthetic properties could be produced with high reproducibility from the powders and calcined bodies of the examples.

[0219] Example 5 A granular powder consisting of yttria-containing zirconia powder containing 3 mass% of acrylic resin and 0.18 mass% of iron and having an yttrium content of 5.2 mol% was obtained in the same manner as in Example 1, except that yttrium chloride was added so that the yttrium concentration was 5.2 mol%, an iron (III) chloride aqueous solution with an FeCl concentration of 45 mass% was added to the mixed aqueous solution so that the iron concentration was 0.18 mass% in terms of Fe2O3, and no α-alumina powder was used. This was used as the powder of this example.

[0220] A compact and a calcined body were obtained in the same manner as in Example 1, except that the powder of this example was used. The measured density of the obtained compact was 3.30 g / cm. 3 It was.

[0221] Example 6 A granular powder consisting of yttria-containing zirconia powder containing 3 mass% of acrylic resin and 0.21 mass% of iron and having an yttrium content of 5.2 mol% was obtained in the same manner as in Example 1, except that yttrium chloride was added so that the yttrium concentration was 5.2 mol%, an iron (III) chloride aqueous solution with an FeCl concentration of 45 mass% was added to the mixed aqueous solution so that the iron concentration was 0.21 mass% in terms of Fe2O3, and no α-alumina powder was used. This was used as the powder of this example.

[0222] A compact and a calcined body were obtained in the same manner as in Example 1, except that the powder of this example was used. The measured density of the obtained compact was 3.30 g / cm. 3 It was.

[0223] Example 7 A granular powder consisting of yttria-containing zirconia powder containing 3 mass% of acrylic resin and 0.23 mass% of iron and having an yttrium content of 5.2 mol% was obtained in the same manner as in Example 1, except that yttrium chloride was added so that the yttrium concentration was 5.2 mol%, an iron (III) chloride aqueous solution with an FeCl concentration of 45 mass% was added to the mixed aqueous solution so that the iron concentration was 0.23 mass% in terms of Fe2O3, and no α-alumina powder was used. This was used as the powder of this example.

[0224] A compact and a calcined body were obtained in the same manner as in Example 1, except that the powder of this example was used. The measured density of the obtained compact was 3.30 g / cm. 3 It was.

[0225] The evaluation results of the obtained powder are shown in Table 6, and the evaluation results of the calcined body are shown in Table 7.

[0226] Example 8 A granular powder consisting of yttria-containing zirconia powder containing 3 mass% of acrylic resin and 0.25 mass% of iron and having an yttrium content of 5.2 mol% was obtained in the same manner as in Example 1, except that yttrium chloride was added so that the yttrium concentration was 5.2 mol%, an iron (III) chloride aqueous solution having an FeCl concentration of 45 mass% was added to the mixed aqueous solution so that the iron concentration was 0.25 mass% in terms of FeO, and α-alumina powder was not used. This was used as the powder of this example.

[0227] A compact and a calcined body were obtained in the same manner as in Example 1, except that the powder of this example was used. The measured density of the obtained compact was 3.30 g / cm. 3 It was.

[0228] The powders of Examples 5 to 8 have an average particle size of 0.43 μm to 0.45 μm and a BET specific surface area of ​​10.6 to 10.9 m. 2 / g, average granule particle size 42μm~46μm, light bulk density 1.27~1.29g / cm 3 The T+C phase ratio was 95% and the shrinkage rate was 3.5%, and all the powders had similar powder properties.

[0229] Furthermore, the powder of Example 8 had an M / Zr range (Fe / Zr range) of 0.058, a maximum M / Zr value of 0.060, a high metal frequency of 0.04%, and a low metal frequency of 0.01%. The elemental mapping of iron in Example 8 is shown in Figure 9. The calcined bodies of Examples 5 to 9 had a more uniformly dispersed transition metal element (iron) than the calcined body of Comparative Example 1.

[0230] The evaluation results of the calcined bodies of Examples 5 to 8 are shown in the table below.

[0231] [Table 6]

[0232] From the table above, it can be seen that there is a tendency for Vickers hardness to increase with increasing transition metal element content, but the degree of increase is very small. On the other hand, the effect of the transition metal element content on the measured density and shrinkage rate was hardly confirmed.

[0233] Measurement example 2 (preparation of sintered body) Sintered bodies were produced and evaluated in the same manner as in Measurement Example 1, except that five calcined bodies were produced for each of the examples 5 to 8. The results are shown in the table below.

[0234] [Table 7]

[0235] From the table above, it can be seen that as the transition metal elements increase, the transmittance tends to decrease, and L * Decline and a * It can be seen that the color tone tends to become darker as the amount increases.

[0236] Next, the saturation C of the five sintered bodies of Examples 5 to 8 was measured. * The standard deviations of the above are shown in the table below together with the evaluation results of Comparative Example 1.

[0237] [Table 8]

[0238] From the above table, it can be seen that the variation in color tone due to the change in the content of the transition metal element is very small. In particular, although Examples 6 to 8 contain a larger amount of the transition metal element (iron) than Comparative Example 1, the color tone is C * It can be seen that the standard deviation of is small.

[0239] Example 9 A granular powder consisting of yttria-containing zirconia powder containing 3 mass% acrylic resin, 0.15 mass% iron, and 0.05 mass% alumina and having an yttrium content of 3.0 mol% was obtained in the same manner as in Example 1, except that yttrium chloride was added so that the yttrium concentration was 3.0 mol%, an iron (III) chloride aqueous solution with an FeCl concentration of 45 mass% was added to the mixed aqueous solution so that the iron concentration was 0.15 mass% in terms of Fe2O3, and the dried powder was fired in an air atmosphere at 1135°C. This was used as the powder of this example.

[0240] A compact and a calcined body were obtained in the same manner as in Example 1, except that the powder of this example was used. The measured density of the obtained compact was 3.31 g / cm 3 It was.

[0241] Example 10 A granular powder consisting of yttria-containing zirconia powder containing 3 mass% of acrylic resin and 0.25 mass% of iron and having an yttrium content of 4.8 mol% was obtained in the same manner as in Example 1, except that yttrium chloride was added so that the yttrium concentration was 4.8 mol%, an iron (III) chloride aqueous solution having an FeCl concentration of 45 mass% was added to the mixed aqueous solution so that the iron concentration was 0.25 mass% in terms of FeO, the dried powder was fired in an air atmosphere at 1095°C, and no α-alumina powder was used. This was used as the powder of this example.

[0242] A compact and a calcined body were obtained in the same manner as in Example 1, except that the powder of this example was used. The measured density of the obtained compact was 3.27 g / cm. 3 It was.

[0243] Example 11 A granular powder consisting of yttria-containing zirconia powder containing 3 mass% of acrylic resin and 0.25 mass% of iron and having an yttrium content of 5.0 mol% was obtained in the same manner as in Example 1, except that yttrium chloride was added so that the yttrium concentration was 5.0 mol%, an aqueous solution of iron (III) chloride with an FeCl concentration of 45 mass% was added to the mixed aqueous solution so that the iron concentration was 0.25 mass% in terms of FeO, the dried powder was fired in an air atmosphere at 1095°C, and no α-alumina powder was used. This was used as the powder of this example.

[0244] A compact and a calcined body were obtained in the same manner as in Example 1, except that the powder of this example was used. The measured density of the obtained compact was 3.27 g / cm. 3 It was.

[0245] Example 12 A granular powder consisting of yttria-containing zirconia powder containing 3 mass% of acrylic resin and 0.25 mass% of iron and having an yttrium content of 5.2 mol% was obtained in the same manner as in Example 1, except that yttrium chloride was added so that the yttrium concentration was 5.2 mol%, an iron (III) chloride aqueous solution with an FeCl concentration of 45 mass% was added to the mixed aqueous solution so that the iron concentration was 0.25 mass% in terms of FeO, the dried powder was fired in an air atmosphere at 1095°C, and no α-alumina powder was used. This was used as the powder of this example.

[0246] A compact and a calcined body were obtained in the same manner as in Example 1, except that the powder of this example was used. The measured density of the obtained compact was 3.27 g / cm. 3 It was.

[0247] Example 13 A granular powder consisting of yttria-containing zirconia powder containing 3 mass% of acrylic resin and 0.25 mass% of iron and having an yttrium content of 5.2 mol% was obtained in the same manner as in Example 1, except that yttrium chloride was added so that the yttrium concentration was 5.2 mol%, an iron (III) chloride aqueous solution with an FeCl concentration of 45 mass% was added to the mixed aqueous solution so that the iron concentration was 0.25 mass% in terms of FeO, the dried powder was fired in an air atmosphere at 1080°C, and no α-alumina powder was used. This was used as the powder of this example.

[0248] A compact and a calcined body were obtained in the same manner as in Example 1, except that the powder of this example was used. The measured density of the obtained compact was 3.26 g / cm. 3 It was.

[0249] Example 14 A granular powder consisting of yttria-containing zirconia powder containing 3 mass% of acrylic resin, 0.25 mass% of iron, and 0.05 mass% of alumina and having an yttrium content of 5.2 mol% was obtained in the same manner as in Example 1, except that yttrium chloride was added so that the yttrium concentration was 5.2 mol%, an iron (III) chloride aqueous solution having an FeCl concentration of 45 mass% was added to the mixed aqueous solution so that the iron concentration was 0.25 mass% in terms of FeO, and the dried powder was fired in an air atmosphere at 1100°C. This was used as the powder of this example.

[0250] A compact and a calcined body were obtained in the same manner as in Example 1, except that the powder of this example was used. The measured density of the obtained compact was 3.30 g / cm. 3 It was.

[0251] The powders of Examples 9 to 14 have an average particle size of 0.41 μm to 0.45 μm, an average granule size of 43 μm to 46 μm, and a loose bulk density of 1.26 to 1.28 g / cm 3 It was.

[0252] The evaluation results of the powders and calcined bodies of Examples 12 and 13 are shown in the table below together with the evaluation result of Example 8.

[0253] [Table 9]

[0254] From the above table, it can be seen that as the BET specific surface area of ​​the powder increases, the measured density and Vickers hardness of the resulting calcined body increase, and in addition, the increase in Vickers hardness is greater than the increase in the measured density.

[0255] Next, the evaluation results of the powders and calcined bodies of Examples 9 to 12 are shown in the table below.

[0256] [Table 10]

[0257] It can be seen that the calcined bodies of Examples 10 to 12 have higher Vickers hardness than the calcined body of Example 9. Since the difference in Vickers hardness between Example 9 and Examples 10 to 12 is about 6 HV, the difference in Vickers hardness is thought to be due to the influence of the BET specific surface area and the amount of transition metal (iron content). Furthermore, the Vickers hardness of the calcined bodies of Examples 10 to 12 was about the same, and the influence of the amount of stabilizing elements could not be confirmed.

[0258] The powder of Example 9 had an M / Zr range (Fe / Zr range) of 0.115, a maximum M / Zr value of 0.115, a high metal frequency of 0.06%, and a low metal frequency of 0.45%. The elemental mapping of iron in Example 9 is shown in Figure 10. The calcined bodies of Examples 9 to 14 had a more uniformly dispersed transition metal element (iron) than the calcined body of Comparative Example 1.

[0259] Measurement example 3 (preparation of sintered body) Sintered bodies were produced and evaluated in the same manner as in Measurement Example 1, except that five calcined bodies were produced for each of the examples 9 to 14. The results are shown in the table below.

[0260] [Table 11]

[0261] Next, the saturation C of the five sintered bodies of Examples 9 to 14 was measured. * The standard deviations of the above are shown in the table below together with the evaluation results of Comparative Example 1.

[0262] [Table 12]

[0263] Examples 9 to 14C * The standard deviations of were all smaller than and comparable to those of Comparative Example 1. This confirms that, regardless of the BET specific surface area of ​​the powder, the amount of stabilizing elements, and the presence or absence of alumina, the color tone reproducibility in relation to variations in sintering temperature is higher than that of conventional sintered bodies. [Explanation of symbols]

[0264] 1: Calcined body 2: Sack

Claims

1. The zirconia composition contains a stabilizing element and a transition metal element capable of coloring zirconia, and in a frequency distribution of element ratios in which the transition metal element capable of coloring zirconia / zirconium ratio is plotted at intervals of 0.005, the difference between the minimum and maximum values ​​of the transition metal element capable of coloring zirconia / zirconium ratio is less than 0.25, and the zirconia composition has a loose bulk density of 1.10 g / cm ３ 1.40g / cm or more ３ The powder is a zirconia powder as described below, wherein 3.0 g of the powder is filled into a mold having a diameter of 25 mm, uniaxially press-molded at a pressure of 49 MPa, and then subjected to CIP treatment at a pressure of 196 MPa to obtain a disk-shaped molded body, which is then calcined under the following conditions to form a calcined body, and the shrinkage rate calculated from the following formula is less than 4.0%. Calcining temperature: 1000℃ Pre-baking time: 1 hour Heating rate: 50°C / hour Calcination atmosphere: Air atmosphere Cooling rate: 300℃ / hour Shrinkage rate [%] = {(25 - diameter of calcined body) [mm] / 25 [mm]} × 100 (1)

2. 2. The powder according to claim 1, wherein in the frequency distribution, the total frequency of transition metal elements capable of coloring zirconia / zirconium less than 0.005 is 6.5% or less.

3. 3. The powder according to claim 1, wherein the total frequency of transition metal elements capable of coloring zirconia / zirconium of 0.05 or more in the frequency distribution is 2.5% or less.

4. 3. The powder according to claim 1, wherein the transition metal element capable of coloring the zirconia is one or more selected from the group consisting of titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), niobium (Nb), vanadium (V), molybdenum (Mo), technetium (Tc), ruthenium (Ru), rhodium (Rh), palladium (Pd), and silver (Ag).

5. 3. The powder according to claim 1, wherein the stabilizing element is one or more selected from the group consisting of yttrium (Y), calcium (Ca), magnesium (Mg), terbium (Tb), and erbium (Er).

6. Alumina (Al ２ O ３ ), silica (SiO ２ ) and germania (GeO ２ 3. The powder according to claim 1 or 2, comprising one or more selected from the group consisting of:

7. BET specific surface area is 8m ２ / g or more 15m ２ The powder according to claim 1 or 2, wherein the solubility is 1 / g or less.

8. 3. The powder according to claim 1, wherein in an XRD pattern obtained by the following XRD measurement, a ratio of the area intensity of the XRD peaks of tetragonal and cubic zirconia to the total area intensity of the XRD peaks of tetragonal, cubic and monoclinic zirconia is 50% or more and 99% or less. Radiation source: CuKα radiation (λ=0.15418nm) Measurement mode: Continuous scan Scan speed: 2° / min Measurement range: 2θ = 26° to 33° 2θ=72° to 76° Acceleration voltage / current: 40mA / 40kV Divergence vertical limit slit: 10 mm Divergence / entrance slit: 1° Receiving slit: open Detector: Semiconductor detector (D / teX Ultra) Filter: Ni filter Goniometer radius: 185 mm

9. 3. The powder according to claim 1 or 2, which is a granular powder.

10. A molded body comprising the powder according to claim 1 or 2.

11. A method for producing a calcined body, comprising the step of calcining the compact according to claim 10.

12. A method for producing a sintered body, comprising the step of sintering at least one of a molded body containing the powder according to claim 1 or 2 and a calcined body obtained by calcining the molded body.

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