Zirconia composition and method for producing the same

Abstract

To provide a calcined body that is processed easier than a conventional calcined body and where differences in hardness between production lots are suppressed.SOLUTION: A calcined body comprises: at least one first transition metal element selected from the group consisting of manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), molybdenum (Mo), technetium (Tc), ruthenium (Ru), rhodium (Rh), palladium (Pd), and silver (Ag); a coloring element of at least one of a lanthanoid rare earth element and a second transition metal element different in kind from the first transition metal element; and zirconia containing a stabilizing element. A content of the first transition metal element is 100 mass.ppm or more, a content of the second transition metal element is less than 100 mass.ppm, and an absolute value of a difference in hardness relative to a hardness of a calcined body obtained from a commercially available powder is 10 HV or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to zirconia-based compositions and methods for making 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 are strong but difficult to process. Therefore, when obtaining sintered bodies with complex shapes such as dental prostheses, so-called calcined bodies (semi-sintered bodies, pre-sintered bodies) are used, which are obtained by heat-treating zirconia compacts (compact powders) below the sintering temperature and have a strength suitable for processing. The calcined bodies are then machined into the desired shape using CAD / CAM, and then sintered to produce the sintered bodies.

[0003] To obtain a sintered body having the color tone of natural teeth, there is a method (the so-called immersion method) in which a calcined body of zirconia is immersed in a coloring solution and then sintered (for example, Patent Document 1). Calcined bodies colored by the immersion method suffer from uneven coloring due to differences in the degree of penetration of the coloring solution between the surface and the interior of the calcined body. In addition, with the immersion method, it is difficult to obtain a fine color tone that matches the color tone of each patient's natural teeth.

[0004] On the other hand, a method (so-called powder mixing method) is known in which a coloring component and zirconia are mixed in powder form to obtain a powder composition, which is then molded and calcined, and the calcined body containing the coloring component at the time of calcination is sintered (Patent Document 2). The calcined body obtained by the powder mixing method has extremely small color unevenness compared to the calcined body obtained by the immersion method, and it is also easy to finely adjust the color tone of the resulting sintered body. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] European Patent Application Publication No. 3892254 [Patent Document 2] U.S. Patent No. 9,428,422 Summary of the Invention [Problem to be solved by the invention]

[0006] The color tone of the sintered body obtained from the calcined body is determined by adjusting the composition, particularly the type and content of the coloring component. Meanwhile, even trace amounts of coloring components affect the thermal shrinkage behavior of the zirconia composition. Therefore, zirconia compositions with different compositions exhibit different thermal shrinkage behaviors. As a result, calcined bodies that produce sintered bodies with different color tones have different hardnesses. Calcined bodies with different hardnesses impose different loads on processing tools, requiring skilled processing techniques. Furthermore, the higher the hardness, the more difficult it is to process the calcined body.

[0007] In addition to differences in processing characteristics due to differences in composition, calcined bodies obtained by calcining a molded body containing a coloring component may have different hardnesses between production lots, even if the calcined bodies have the same composition. By applying different calcination conditions depending on the composition (color tone) of the calcined body, differences in hardness due to differences in composition can be suppressed to some extent. However, changing the calcination conditions depending on the composition of the calcined body is not preferable because it complicates the process of producing the calcined body. Furthermore, for calcined bodies with the same composition, differences in hardness between production lots cannot be suppressed even if multiple calcination conditions are applied.

[0008] In view of these problems, an object of the present disclosure is to provide at least one of a calcined body that is easier to process than conventional calcined bodies and in which differences in hardness between production lots are suppressed, a method for producing the same, a sintered body obtained by the method, and a zirconia composition that is a raw material for such a calcined body. [Means for solving the problem]

[0009] The present inventors have conducted detailed studies on the thermal shrinkage behavior and composition of zirconia compositions that serve as precursors to calcined bodies. As a result, they have found that, among coloring components, transition metal elements have a significant effect on the thermal shrinkage behavior of zirconia compositions. Furthermore, they have found that controlling the state of transition metal elements at a certain content or higher can change the thermal shrinkage behavior without essentially changing the composition. As a result, they have found a calcined body that exhibits a color tone equivalent to that of a sintered body obtained from a conventional calcined body, while suppressing differences in hardness between production lots. They have also found a zirconia composition that serves as a precursor to such a calcined body.

[0010] That is, the present invention is as defined in the claims, and the gist of the present disclosure is as follows. [1] One or more first transition metal elements selected from the group consisting of manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), molybdenum (Mo), technetium (Tc), ruthenium (Ru), rhodium (Rh), palladium (Pd) and silver (Ag); At least one coloring element selected from the group consisting of a lanthanide rare earth element and a second transition metal element different in type from the first transition metal element; and zirconia containing a stabilizing element, The content of the first transition metal element is 100 ppm by mass or more, The content of the second transition metal element is less than 100 ppm by mass, and When the characteristic X-rays of the zirconium element and the characteristic X-rays of the first transition metal element are measured, the ratio of the intensity of the characteristic X-rays of the first transition metal element to the intensity of the characteristic X-rays of the zirconium element is 0.05 or more at 3% or less of all measurement points; and The zirconia composition satisfies at least one of the following characteristics: when the characteristic X-rays of the zirconium element and the characteristic X-rays of the first transition metal element are measured, the distribution width of the ratio of the intensity of the characteristic X-rays of the first transition metal element to the intensity of the characteristic X-rays of the zirconium element is 0.3 or less. [2] The zirconia composition according to [1] above, wherein, when the characteristic X-rays of the zirconium element and the characteristic X-rays of the first transition metal element are measured, the distribution width of the ratio of the intensity of the characteristic X-rays of the first transition metal element to the intensity of the characteristic X-rays of the zirconium element is 0.3 or less. [3] The zirconia composition according to [1] or [2] above, wherein, when the characteristic X-rays of the zirconium element and the characteristic X-rays of the first transition metal element are measured, the ratio of the intensity of the characteristic X-rays of the first transition metal element to the intensity of the characteristic X-rays of the zirconium element is 0.05 or more at 3% or less of all measurement points. [4] The zirconia composition according to any one of [1] to [3] above, wherein the second transition metal element is one or more transition metal elements selected from the group consisting of manganese, iron, cobalt, nickel, copper, molybdenum, technetium, ruthenium, rhodium, palladium, and silver. [5] The zirconia composition according to any one of [1] to [4] above, wherein the lanthanoid rare earth element is one or more selected from the group consisting of praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), erbium (Er), and ytterbium (Yb). [6] The zirconia composition according to any one of [1] to [5] above, wherein the lanthanoid rare earth element is a lanthanoid rare earth element solid-solved in zirconia. [7] The zirconia composition according to any one of [1] to [6] above, wherein the content of the lanthanoid rare earth element is 1.0 mass % or less. [8] The zirconia composition according to any one of [1] to [7] above, further comprising one or more third transition metal elements selected from the group consisting of titanium (Ti), vanadium (V) and niobium (Nb). [9] The zirconia composition according to any one of [1] to [8] above, which contains one or more selected from the group consisting of alumina (Al2O3), silica (SiO2) and germania (Ge2O3).

[10] BET specific surface area is 8m 2 / g or more 15m 2The zirconia composition according to any one of [1] to [9] above, wherein the zirconia composition has a viscosity of 1000 MPa or less.

[11] The zirconia composition according to any one of [1] to

[10] above, wherein the zirconia composition is in the form of a powder.

[12] 3.0±0.1 g of the zirconia composition was charged into a mold having a diameter of 25 mm, and after uniaxial pressing at a pressure of 49 MPa, CIP treatment was performed at a pressure of 196 MPa. The measured density was 3.2 g / cm 3 The zirconia composition according to

[11] above.

[13] The zirconia composition according to any one of [1] to

[10] above, wherein the zirconia composition is a molded body.

[14] The zirconia composition according to

[13] above, having a Vickers hardness of 11.0 or more.

[15] A method for producing a calcined body, comprising a step of calcining the zirconia composition according to any one of [1] to

[14] above.

[16] A method for producing a sintered body, comprising a step of sintering the calcined body obtained by the production method according to

[15] above. [Effects of the Invention]

[0011] The present disclosure makes it possible to provide at least one of a calcined body that is easier to process than conventional calcined bodies and in which differences in hardness between production lots are suppressed, a method for producing the same, a sintered body obtained by the method, and a zirconia composition that is a raw material for such a calcined body. DETAILED DESCRIPTION OF THE INVENTION

[0012] The zirconia composition of the present disclosure will be described with reference to an example embodiment. The terms used in this embodiment are as follows:

[0013] 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, a molded body, a calcined body, and a sintered body. The term "zirconia composition" refers to a composition containing zirconia as a main component, and further refers to a composition essentially consisting of zirconia. This composition may contain components other than zirconia. Preferably, the zirconia composition in this embodiment is a composition that can serve as a precursor for a calcined body.

[0014] A "powder" is a composition that is an aggregate of powder particles (primary particles and / or secondary particles) and has fluidity. A "zirconia powder" is a powder whose main component is zirconia and is essentially composed of zirconia. A "powder composition" is a composition composed of powders with different characteristics, and in particular, a composition containing powders with different compositions.

[0015] "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.

[0016] 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."

[0017] 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.

[0018] 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.

[0019] A "major component" is a component that becomes the main phase (matrix, base material, parent phase) in the composition of the composition, and preferably 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, and also 100 mass% or less or less than 100 mass%, preferably 75 mass% or more and 100 mass% or less, or 95 mass% or more and less than 100 mass%.

[0020] The "stabilizing element" is an element that stabilizes the crystalline phase of zirconia by dissolving in zirconia.

[0021] "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:

[0022] 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).

[0023] In this embodiment, the "air atmosphere" refers to a nitrogen atmosphere mainly composed of nitrogen and oxygen, with an oxygen concentration of 18 to 23% by volume, which may contain moisture.

[0024] 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 laser diffraction / scattering particle size distribution analyzer (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.

[0025] The "average granule particle size" is the D50 in the volume particle size distribution of a granular powder measured by a dry method, and can be measured using a general laser diffraction / scattering particle size distribution analyzer (e.g., MT3100II, manufactured by Microtrack Bell). The measurement sample is the granular powder in a slowly agglomerated state, and is not subjected to dispersion treatment such as ultrasonic treatment.

[0026] 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).

[0027] 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 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.

[0028] The term "XRD peak" refers to a peak having a peak top at 2θ detected in the XRD pattern obtained in the above-described XRD measurement. In this embodiment, "not having an XRD peak" means that the XRD peak is not detected in the above-described XRD measurement.

[0029] The XRD peaks corresponding to the respective crystal planes of zirconia are XRD peaks having peak tops at the following 2θ positions.

[0030] 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° 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.

[0031] 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 in the above-mentioned XRD measurement, and is calculated by the following formula.

[0032] f T+C =[I t (111)+I c(111)] / [I m (111)+I m (11-1)+I t (111)+I c (111)] In the above equation, f T+C is the tetragonal and cubic crystal 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°.

[0033] 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).

[0034] "Measured density" is the density of the sample volume [cm 3 ] to the mass [g] [g / cm 3 ]. The mass can be determined by weighing the sample. For the green body and calcined body, the volume can be determined by shape measurement, and for the sintered body, the volume can be determined by the Archimedes method in accordance with JIS R 1634. The Archimedes method uses ion-exchanged water as the solvent, and pretreatment can be performed by boiling. The measured densities of the green body, calcined body, and sintered body are referred to as the "green body density," "calcined body density," and "sintered body density," respectively.

[0035] "Vickers hardness" is a value measured using a common Vickers tester (for example, a Q30A model 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 diagonal length thus obtained can be used to calculate the Vickers hardness using the following formula:

[0036] 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°).

[0037] The conditions for measuring the Vickers hardness are as follows.

[0038] Measurement sample: Disc-shaped with a thickness of 3.0±0.5mm Measurement load: 1kgf Prior to measurement, the surface of the sample to be measured is polished with #800 waterproof abrasive paper to remove any irregularities exceeding 0.1 mm as pretreatment. Measurements are taken at 10 points on the sample, and the average value is taken as the Vickers hardness.

[0039] "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. The measurement sample is a disk-shaped sintered body having a thickness of 1.0±0.1 mm and a surface roughness Ra≦0.02 μm on both sides, and the measurement device is a haze meter equipped with a D65 light source (for example, Haze Meter NDH4000, manufactured by Nippon Denshoku Co., Ltd.).

[0040] "Color tone (L * , a * , b *) is a value measured using the SCI method with 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. Specific measurement conditions for color tone include the following when measuring with a white calibration plate placed as the background of the measurement sample (so-called white background measurement). The color tone of a sintered compact can be measured by cutting any part of the sintered compact horizontally and processing it to a thickness of 1.0±0.1 mm.

[0041] Light source: D65 light source Viewing angle: 2° Measurement method: SCI Lightness L * is an index of brightness and has a value between 0 and 100. * and b * is an index that indicates color tone and has a value between -100 and 100. * is an index of vividness.

[0042] "Three-point bending strength" is a value measured by 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 support distance of 30 mm, and the measurement is performed by applying a load horizontally to the specimen.

[0043] "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 temperature at which sintering of zirconia progresses (hereinafter also referred to as "sintering temperature") without applying any external force to the object to be sintered during sintering.

[0044] "Atmospheric pressure firing" is a method in which the object is heated at a temperature below the sintering temperature without applying any external force to the object during heat treatment.

[0045] [Zirconia composition] This embodiment relates to a composition comprising one or more first transition metal elements selected from the group consisting of manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), molybdenum (Mo), technetium (Tc), ruthenium (Ru), rhodium (Rh), palladium (Pd), and silver (Ag); a coloring element selected from at least one of a lanthanide rare earth element and a second transition metal element different in type from the first transition metal element; and zirconia containing a stabilizing element, The content of the first transition metal element is 100 ppm by mass or more, The content of the second transition metal element is less than 100 ppm by mass, and When the characteristic X-rays of the zirconium element and the characteristic X-rays of the first transition metal element are measured, the ratio of the intensity of the characteristic X-rays of the first transition metal element to the intensity of the characteristic X-rays of the zirconium element is 0.05 or more at 3% or less of all measurement points; and The zirconia composition satisfies at least one of the following conditions: when the characteristic X-rays of the zirconium element and the first transition metal element are measured, the distribution width of the ratio of the intensity of the characteristic X-rays of the first transition metal element to the intensity of the characteristic X-rays of the zirconium element is 0.3 or less. The first transition metal element (hereinafter also referred to as "element M1") has the function of coloring zirconia, forming the base of the color tone, and is the transition metal element contained in a large amount in the zirconia composition of this embodiment, preferably the transition metal element contained most abundantly in the zirconia composition of this embodiment. The element M1 has a significant effect on the thermal shrinkage behavior of the zirconia composition and is prone to segregation after sintering. However, by satisfying the configuration of the zirconia composition of this embodiment, the effect of the element M1 on the thermal shrinkage behavior is significantly suppressed, and as a result, the zirconia composition of this embodiment can be used as a precursor for a calcined body with suppressed differences in mechanical strength between production lots.

[0046] The zirconia composition of the present embodiment is a zirconia composition that can serve as a precursor of a calcined body, and is preferably at least one of a zirconia powder and a zirconia molded body. The zirconia composition of the present embodiment may be a zirconia molded body or a zirconia powder.

[0047] The zirconia composition of this embodiment contains stabilizing element-containing zirconia. The stabilizing element-containing zirconia is preferably zirconia in which a stabilizing element is dissolved (stabilizing element-dissolved zirconia). Therefore, the zirconia composition of this embodiment may be considered as a stabilizing element-containing zirconia composition, or even as a stabilizing element-dissolved zirconia composition.

[0048] The stabilizing element may be any element that dissolves in zirconia without coloring the zirconia, and may be one or more selected from the group consisting of yttrium (Y), calcium (Ca), and magnesium (Mg), with yttrium being preferred.

[0049] The content of the stabilizing element in the zirconia composition 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") may be any amount that stabilizes the zirconia crystal phase into a crystal phase mainly composed of tetragonal crystals, or further into a crystal phase composed of tetragonal and cubic crystals, and can be 2.0 mol% to 8.0 mol%. When the stabilizing element is yttrium, the stabilizing element amount (yttrium amount) may be 2.6 mol% to 3.1 mol%, 3.6 mol% to 3.9 mol% or more, and may be 6.0 mol% to 5.6 mol%, 5.4 mol% to 4.3 mol%, or 4.1 mol% or less, and is preferably 2.6 mol% to 6.0 mol%, 3.6 mol% to 5.4 mol%, or 3.9 mol% to 4.1 mol%.

[0050] In this embodiment, the amount of the stabilizing element is the molar ratio [mol%] of the stabilizing element converted to its oxide relative to the total of zirconia, the stabilizing element converted to its oxide, and the lanthanoid rare earth element. The stabilizing elements are converted to their oxides as follows: yttrium is Y2O3, calcium is CaO, and magnesium is MgO.

[0051] The zirconia composition of this embodiment preferably does not contain an undissolved stabilizing element. The absence of an undissolved stabilizing element can be confirmed by the absence of an XRD peak attributable to a compound of the stabilizing element in the XRD pattern. However, the presence of an undissolved stabilizing element is acceptable as long as the effect of the zirconia composition of this embodiment is exhibited, i.e., the presence of an undissolved stabilizing element to the extent that an XRD peak attributable to a compound of the stabilizing element is not confirmed in the XRD pattern.

[0052] The zirconia composition of this embodiment contains one or more M1 elements selected from the group consisting of manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), molybdenum (Mo), technetium (Tc), ruthenium (Ru), rhodium (Rh), palladium (Pd), and silver (Ag). The M1 element is a transition metal element that has the function of coloring zirconia and is prone to segregation after sintering. The M1 element functions as a coloring component (main coloring component) that affects the base color tone of the sintered body obtained from the zirconia composition of this embodiment. In order to obtain a sintered body with a color tone suitable for use as a dental prosthetic material, it is preferable that the zirconia composition of this embodiment contains 100 ppm by mass or more of one transition metal element, i.e., contains only one M1 element. On the other hand, when two or more transition metal elements are contained in an amount of 100 ppm by mass or more, for convenience, the transition metal element contained most abundantly among the transition metal elements may be referred to as the M1 element, and the other M1 elements may be referred to as the first' transition metal element (M1' element), the first" transition metal element (M1" element), etc.

[0053] The content of the M1 element in the zirconia composition of this embodiment (amount of M1 element) is 100 ppm by mass or more, and the higher the content, the stronger the color tone derived from the M1 element. The amount of M1 element is, for example, 150 ppm by mass or more, 300 ppm by mass or more, or 500 ppm by mass or more, and 0.2% by mass or less (2000 ppm by mass or less), 0.15% by mass or less, 0.12% by mass or less, or 0.1% by mass or less (1000 ppm by mass or less). The specific amount of M1 element may be adjusted appropriately depending on the desired color tone. For example, the amount of M1 element to achieve a color tone suitable for dental prosthetic materials may be 100 ppm by mass or more and 1500 ppm by mass or less, 100 ppm by mass or more and 1000 ppm by mass or less, or 100 ppm by mass or more and 500 ppm by mass or less.

[0054] The amount of M1 element in this embodiment is the mass ratio [mass ppm] of the M1 element converted into an oxide relative to the total mass of zirconia and the metal element converted into an oxide (hereinafter also referred to as "metal element mass").

[0055] The type of M1 element may be appropriately selected depending on the desired color tone, and examples thereof include one or more selected from the group consisting of manganese, iron, cobalt, nickel, copper, molybdenum, and silver, one or more selected from the group consisting of manganese, iron, cobalt, nickel, and copper, one or more selected from the group consisting of manganese, iron, and nickel, at least one of manganese and iron, at least one of iron and nickel, and iron. The M1 element may be manganese, iron, cobalt, nickel, copper, molybdenum, or silver, or may be manganese, iron, cobalt, or nickel, or may be nickel or iron. For example, to obtain a sintered body having a gray-based color tone, the M1 element is manganese; to obtain a sintered body having a yellow-based color tone, the M1 element is iron; to obtain a sintered body having a blue-based color tone, the M1 element is cobalt; and to obtain a sintered body having a green-based color tone, the M1 element is nickel.

[0056] The zirconia composition of this embodiment may contain the M1 element in any form, such as at least one selected from the group consisting of oxide, hydroxide, oxyhydroxide, halide, sulfate, nitrate, and acetate, at least one selected from the group consisting of oxide, hydroxide, oxyhydroxide, and chloride, at least one selected from oxide and oxyhydroxide, or even oxide.

[0057] The zirconia composition of this embodiment satisfies at least one of the following: when the characteristic X-rays of the zirconium element and the characteristic X-rays of the M1 element are measured, the ratio of the intensity of the characteristic X-rays of the M1 element to the intensity of the characteristic X-rays of the zirconium element (hereinafter also referred to as the "X-ray intensity ratio") at measurement points where the ratio of the intensity of the characteristic X-rays of the M1 element to the intensity of the characteristic X-rays of the zirconium element is 0.05 or more is 3% or less of all measurement points (i.e., the ratio of the number of measurement points where the X-ray intensity ratio is 0.05 or more is 3% or less); and when the characteristic X-rays of the zirconium element and the characteristic X-rays of the first transition metal element are measured, the distribution width of the ratio of the intensity of the characteristic X-rays of the first transition metal element to the intensity of the characteristic X-rays of the zirconium element is 0.3 or less. Satisfying this configuration is believed to significantly reduce the localization of the M1 element. This is believed to suppress localized, rapid thermal shrinkage due to the non-uniform presence of the M1 element, reduce the hardness of the resulting calcined body, and suppress variation in thermal shrinkage behavior due to differences in production lots. As a result, the difference in hardness between production lots of the calcined bodies obtained from the zirconia composition of this embodiment can be suppressed.

[0058] The proportion of measurement points with an X-ray intensity ratio of 0.05 or more to all measurement points (hereinafter also referred to as "high intensity proportion") is preferably 3% or less, 2% or less, 0.5% or less, 0.1% or less, or 0.05% or less. The high intensity proportion may be 0% or more, more than 0%, or 0.01% or more, and is preferably 0% to 3%, more than 0% to 3%, or 0.01% to 0.5%.

[0059] In a zirconia composition that satisfies the intensity ratio range described below, the high-intensity ratio may be any value, and examples of the high-intensity ratio include 0% or more and less than 100%, 50% or more and 99.5% or less, and 80% or more and 99.5% or less.

[0060] The zirconia composition of this embodiment preferably does not have coarse aggregates of the M1 element, and the proportion of measurement points at which the X-ray intensity ratio is 0.1 or greater relative to all measurement points (hereinafter also referred to as the "coarse intensity proportion") is preferably 10% or less, 8% or less, 5% or less, 0.5% or less, 0.3% or less, 0.1% or less, or 0.01% or less. The coarse intensity proportion may be 0% or greater or greater than 0%, and is preferably 0% or greater but 10%, greater than 0% but 10%, or greater than 0% but 5%. When the M1 element is iron, the coarse intensity proportion can be, for example, 0% or greater but 0.5%, or 0% or greater but 0.01%.

[0061] The distribution width of the X-ray intensity ratio of the zirconia composition of this embodiment (i.e., the absolute value of the difference between the maximum intensity ratio (described later) and the minimum intensity ratio (described later); hereinafter, also referred to as "intensity ratio range") is preferably 0.3 or less, 0.2 or less, 0.15 or less, 0.12 or less, 0.1 or less, or 0.08 or less. This makes it easier for the resulting calcined body to have more uniform hardness.

[0062] A narrow intensity ratio range means that the X-ray intensity ratio values at all measurement points are equivalent, i.e., the M1 element is present in a more uniform state in the composition. This suppresses localized, rapid thermal shrinkage resulting from the non-uniform presence of the M1 element, reducing the hardness of the resulting calcined body and suppressing variations in thermal shrinkage behavior due to differences in production lots. Therefore, the zirconia composition of this embodiment preferably has the intensity ratio range described above, instead of or in addition to a high-intensity ratio of 3% or less. By exhibiting such an intensity ratio range for the zirconia composition of this embodiment, the effect of the M1 element on the thermal shrinkage behavior of the zirconia composition becomes more uniform. The intensity ratio range may be greater than 0, 0.01 or greater, 0.04 or greater, or 0.05 or greater. Examples of the intensity ratio range include greater than 0 and 0.3 or less, greater than 0 and 0.2 or less, 0.01 or greater and 0.1 or less, or 0.04 or greater and 0.08 or less.

[0063] The intensity ratio range tends to become larger as the amount of the stabilizing element increases and as the amount of the M1 element increases.

[0064] On the other hand, in a zirconia composition in which the proportion of measurement points where the X-ray intensity ratio is 0.05 or more is 3% or less of all measurement points, the intensity ratio range may be any range, but it is preferable that the proportion of measurement points where the X-ray intensity ratio is 0.05 or more is 3% or less of all measurement points, and that the intensity ratio range is 0.3 or less.

[0065] The maximum value of the X-ray intensity ratio (hereinafter also referred to as "maximum intensity ratio") of the zirconia composition of this embodiment is preferably 0.3 or less, 0.2 or less, or 0.1 or less. When the maximum intensity ratio is in this range, the influence of coarse aggregated particles of the M1 element on the thermal shrinkage behavior of the zirconia composition tends to be smaller. The maximum intensity ratio of the zirconia composition of this embodiment may be 0.04 or more, or 0.05 or more. Preferred maximum intensity ratios include 0.04 or more and 0.3 or less, 0.04 or more and 0.2 or less, or 0.05 or more and 0.1 or less.

[0066] The minimum value of the X-ray intensity ratio of the zirconia composition of this embodiment (hereinafter also referred to as "minimum intensity ratio") can be, for example, 0 or more, more than 0, or 0.001 or more, and can be 0.05 or less, 0.04 or less, 0.01 or less, or 0.002 or less, for example, 0 or more and 0.01 or less, 0 or more and 0.002 or less, or more than 0 and 0.002 or less.

[0067] In the zirconia composition of this embodiment, the characteristic X-rays of zirconium element and the characteristic X-rays of M1 element may be measured using a field emission wavelength dispersive electron probe microanalyzer (hereinafter also referred to as "FE-EPMA") under the following conditions.

[0068] Accelerating voltage: 15 kV Irradiation current: 50nA Beam diameter: 1 μm Capture time: 50 msec Magnification: 500x Analysis area: 256.0μm×256.0μm For the measurement, a general FE-EPMA device (for example, JXA-iHP200F, manufactured by JEOL Ltd.) is used, and the analysis area is divided into 65,500±100 grid regions, each of which is used as a measurement point. In this embodiment, FE-EPMA measurement is performed on multiple locations (preferably 5±3 locations) of the same sample, and the high intensity ratio, coarse intensity ratio, maximum intensity ratio, minimum intensity ratio, and intensity ratio range are determined for each location, and the average values thereof are used as the values in this embodiment.

[0069] The zirconia composition of this embodiment contains at least one coloring element (hereinafter also referred to as a "secondary coloring component") selected from the group consisting of a lanthanoid rare earth element and a second transition metal element (hereinafter also referred to as an "M2 element") that is different from the M1 element. The secondary coloring component is a coloring component for adjusting the color tone, and by including the secondary coloring component in the zirconia composition in addition to the M1 element, the color tone of the resulting sintered body can be adjusted. Depending on the desired color tone, the secondary coloring component may be only a lanthanoid rare earth element, only an M2 element, or both a lanthanoid rare earth element and an M2 element.

[0070] The transition metal element M2 is a transition metal element different from the M1 element contained in the composition of this embodiment, has the function of coloring zirconia, and is a transition metal element that is likely to segregate after sintering. The M2 element is preferably one or more selected from the group consisting of manganese, iron, cobalt, nickel, copper, molybdenum, technetium, ruthenium, rhodium, palladium, and silver, and is more preferably a transition metal element different from the M1 element. The M2 element is more preferably one or more selected from the group consisting of manganese, iron, cobalt, nickel, copper, molybdenum, technetium, ruthenium, rhodium, palladium, and silver, even more preferably one or more selected from the group consisting of manganese, iron, cobalt, nickel, copper, molybdenum, and silver, even more preferably one or more selected from the group consisting of manganese, iron, cobalt, nickel, and copper, even more preferably one or more selected from the group consisting of manganese, cobalt, and nickel, even more preferably at least one of manganese and cobalt, and even more preferably cobalt.

[0071] It is preferable that the M2 element is different from the M1 element and is manganese, iron, cobalt, nickel, copper, molybdenum, or silver, further different from the M1 element and is manganese, iron, cobalt, nickel, or copper, still further different from the M1 element and is manganese, cobalt, or nickel, or still further different from the M1 element and is manganese or cobalt.

[0072] The content of the M2 element (amount of M2 element) is less than 100 ppm by mass, and preferably 80 ppm by mass or less, 70 ppm by mass or less, or 50 ppm by mass or less. Such a content significantly reduces the effect of the M2 element on the thermal shrinkage behavior of the zirconia composition. The zirconia composition of this embodiment does not need to contain the M2 element (i.e., the content of the M2 element may be 0 ppm by mass). Therefore, the amount of the M2 element in the zirconia composition of this embodiment only needs to be 0 ppm by mass or more. On the other hand, the zirconia composition of this embodiment may contain the M2 element, and the content thereof may be more than 0 ppm by mass, 3 ppm by mass or more, 10 ppm by mass or more, 20 ppm by mass or more, or 35 ppm by mass or more; for example, more than 0 ppm by mass and less than 100 ppm by mass, more than 0 ppm by mass and 80 ppm by mass or less, or more than 0 ppm by mass and 50 ppm by mass or less. Furthermore, the amount of the M2 element may be more than 0 ppm by mass and not more than 10 ppm by mass, or more than 0 ppm by mass and not more than 5 ppm by mass.

[0073] The amount of M2 element in this embodiment is the mass ratio [ppm by mass] of the M2 element converted to its oxide relative to the mass of the metal element.

[0074] The oxide equivalents of the transition metal elements are Mn3O4 for manganese, Fe2O3 for iron, Co3O4 for cobalt, NiO for nickel, CuO for copper, Molybdenum for Mo2O3, Tc2O3 for technetium, Ruthenium for RuO2, Rhodium for RhO2, Palladium for Pd2O3, and Ag2O for silver.

[0075] The lanthanoid rare earth element is preferably one or more selected from the group consisting of praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), erbium (Er), and ytterbium (Yb), more preferably one or more selected from the group consisting of praseodymium, neodymium, terbium, and erbium, even more preferably one or more selected from the group consisting of praseodymium, terbium, and erbium, even more preferably at least one of terbium and erbium, and particularly preferably erbium.

[0076] Lanthanoid rare earth elements are thought to have a smaller effect on the thermal shrinkage behavior of zirconia compositions than transition metal elements. Therefore, the content of the lanthanoid rare earth elements is preferably 1.0 mass% or less, 0.85 mass% or less, 0.6 mass% or less, or 0.15 mass% or less. The zirconia composition of this embodiment may not contain a lanthanoid rare earth element (i.e., the content of the lanthanoid rare earth element may be 0 mass% or 0 mass% or more). On the other hand, the zirconia composition of this embodiment may contain a lanthanoid rare earth element, and the content may be greater than 0 mass%, 0.01 mass% or more, or 0.05 mass% or more. For example, 0 mass% to 1.0 mass%, 0 mass% to 0.15 mass%, or 0.05 mass% to 0.15 mass%. Lanthanoid rare earth elements also function as stabilizing elements. However, in this embodiment, for convenience, lanthanoid rare earth elements are considered not to be included in the stabilizing elements.

[0077] The content of the lanthanoid rare earth element may be determined as the ratio [mass %] of the lanthanoid rare earth element [g] converted to its oxide relative to the mass [g] of the zirconia and metal element.

[0078] The oxide equivalents of the lanthanide rare earth elements are praseodymium and PrO 11 , neodymium may be Nd2O3, samarium may be Sm2O3, europium may be Eu2O3, gadolinium may be Gd2O3, terbium may be Tb4O7, erbium may be Er2O3, and ytterbium may be Yb2O3.

[0079] The zirconia composition of the present embodiment may contain the secondary coloring component in any form, such as at least one selected from the group consisting of oxide, hydroxide, oxyhydroxide, halide, sulfate, nitrate, and acetate, at least one selected from the group consisting of oxide, hydroxide, oxyhydroxide, and chloride, at least one selected from oxide and oxyhydroxide, or even oxide.

[0080] When the secondary coloring component is a lanthanoid rare earth element, the lanthanoid rare earth element is preferably solid-dissolved in zirconia (substituting for zirconium cations) because this makes it easier to suppress abnormal grain growth during sintering. The zirconia composition of this embodiment preferably contains zirconia in which a lanthanoid rare earth element is solid-dissolved (hereinafter also referred to as "lanthanoid solid-dissolved zirconia") instead of or in addition to the lanthanoid rare earth element. In particular, the zirconia composition of this embodiment more preferably contains the lanthanoid rare earth element only as lanthanoid solid-dissolved zirconia, and more preferably does not contain a compound containing a lanthanoid rare earth element, such as a lanthanoid rare earth oxide.

[0081] In this embodiment, the absence of a compound containing a lanthanoid rare earth element can be determined by the absence of particulate lanthanoid rare earth elements observed by FE-EPMA.

[0082] The zirconia composition of this embodiment may contain one or more third transition metal elements (hereinafter also referred to as "M3 elements") selected from the group consisting of titanium (Ti), vanadium (V), and niobium (Nb), preferably at least one of titanium and vanadium, and more preferably titanium. The M3 element is a transition metal element that is less likely to segregate after sintering. By including the M3 element in addition to or instead of the secondary coloring component, changes in the thermal shrinkage behavior of the zirconia composition can be suppressed, and the color tone of the resulting sintered body can be easily fine-tuned.

[0083] The zirconia composition of this embodiment contains the M3 element, and the content thereof may be 1.0 mass% or less, 0.5 mass% or less, or 0.3 mass% or less, or may be greater than 0 mass% or greater than 0.1 mass%. The zirconia composition of this embodiment may not contain the M3 element (i.e., the content of the M3 element may be 0 mass% or greater than 0 mass%). The content of the M3 element (amount of the M3 element) of this embodiment can be 0 mass% or more and 1.0 mass% or less, 0 mass% or more and 0.5 mass% or less, or 0 mass% or more and 0.05 mass% or less. When the zirconia composition contains the M3 element, the content can be greater than 0 mass% and 1.0 mass% or less, greater than 0 mass% and 0.5 mass% or less, or greater than 0 mass% and 0.05 mass% or less.

[0084] The content of M3 element can be calculated as the mass ratio (mass %) of M3 element (g) converted to oxide relative to the mass (g) of zirconia and metal element. The oxide equivalents are TiO2 for titanium, V2O5 for vanadium, and Nb2O3 for niobium.

[0085] The zirconia composition of this embodiment may contain the M3 element in any form. For example, the M3 element may be contained as at least one selected from the group consisting of oxide, hydroxide, oxyhydroxide, halide, sulfate, nitrate, and acetate, or as at least one selected from the group consisting of oxide, hydroxide, oxyhydroxide, and chloride, or as at least one of oxide and oxyhydroxide, or as oxide. Furthermore, the M3 element may be partially or entirely dissolved in zirconia (or may be substituted for zirconium cations).

[0086] The zirconia composition of this embodiment may contain one or more components selected from the group consisting of alumina (Al2O3), silica (SiO2), and germania (Ge2O3) (hereinafter also referred to as "additive components"), and may further contain alumina. The inclusion of trace amounts of additive components facilitates densification at low temperatures. When additive components are included, their content may be greater than 0 mass%, 0.005 mass% or more, or 0.01 mass% or more, and may be 0.25 mass% or less, 0.2 mass% or less, 0.1 mass% or less, or 0.06 mass% or less. Furthermore, the zirconia composition of this embodiment may not contain additive components (i.e., the content of the additive components may be 0 mass% or 0 mass% or more).

[0087] The content of the additional component may be determined as the mass ratio [mass %] of the additional component (Al2O3, SiO2 or Ge2O3) [g] to the mass [g] of the metal element.

[0088] The zirconia composition of this embodiment preferably does not contain impurities, but may contain hafnia (HfO2), an inevitable impurity of zirconia. The content of hafnia as an inevitable impurity varies greatly depending on the raw material ore and the production method, but can be, for example, 2.0 mass% or less. In calculating values based on the composition, such as density, in this embodiment, hafnia may be considered as zirconia (ZrO2).

[0089] The zirconia composition of this embodiment may contain a binder. The inclusion of a binder improves operability (handling) and shape retention. The binder may be any binder that can be used for granulating or molding ceramics, and is preferably an organic binder. Examples of organic binders include one or more selected from the group consisting of polyvinyl alcohol, polyvinyl butyrate, wax, and acrylic resins, preferably at least one of polyvinyl alcohol and an 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 binders include one or more selected from the group consisting of AS-1100, AS-1800, and AS-2000 (all product names, manufactured by Toagosei Co., Ltd.).

[0090] The binder content 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.

[0091] For example, the composition of an yttrium-stabilized zirconia composition containing iron as the M1 element, cobalt as the M2 element, erbium as the lanthanoid rare earth element, titanium as the M3 element, aluminum (alumina) as an additional component, and a binder can be determined as follows.

[0092] Metal element mass [g]: Y2O3+Er2O3+ZrO2+Al2O3+Fe2O3+Co3O4+TiO2 Stabilizing element amount [mol%]: {(Y2O3+Er2O3) / (Y2O3+Er2O3+ZrO2)}×100 Erbium content [mass%]: {Er2O3 / (Y2O3+Er2O3+ZrO2 +Al2O3+Fe2O3+Co3O4+TiO2)}×100 Iron content [mass%]: {Fe2O3 / (Y2O3+Er2O3+ZrO2 +Al2O3+Fe2O3+Co3O4+TiO2)}×100 Cobalt content [mass%]: {Co3O4 / (Y2O3+Er2O3+ZrO2 +Al2O3+Fe2O3+Co3O4+TiO2)}×100 Titanium content [mass%]: {TiO2 / (Y2O3+Er2O3+ZrO2 +Al2O3+Fe2O3+Co3O4+TiO2)}×100 Alumina content [mass%]: {Al2O3 / (Y2O3+Er2O3+ZrO2 +Al2O3+Fe2O3+Co3O4+TiO2)}×100 The binder content can be calculated as follows:

[0093] {(W1-W2) / W1}×100 In the above formula, W1 is the mass [g] of the zirconia composition before heat treatment in the air at 250° C. or higher and 400° C. or lower, and W2 is the mass [g] of the zirconia composition before heat treatment in the air at 250° C. or higher and 400° C. or lower. Note that, because the calculation methods differ, the total content of the zirconia composition including the binder does not necessarily appear to be 100% by mass.

[0094] The BET specific surface area of the zirconia composition of this embodiment is 8 m 2 / g or more or 10m 2 / g or more, and 15m 2 / g or less, 11m 2 / g or less or 10.5m 2 / g or less, and 2 / g or more 15m 2 / g or less, 10m 2 / g or more 11m 2 / g or less, or 10m 2 / g or more 10.5m 2 / g or less is preferable.

[0095] The average particle size of the zirconia composition of this embodiment is 0.35 μm or more, or 0.4 μm or more, and 0.55 μm or less, or 0.5 μm or less, and is preferably 0.35 μm or more and 0.55 μm or less, or 0.4 μm or more and 0.5 μm or less.

[0096] The T+C phase ratio of the zirconia composition of this embodiment is 50% or more, 55% or more, 60% or more, 70% or more, 80% or more, or 85% or more, and may be 100% or less, 99% or less, 95% or less, 92% or less, or 90% or less, and is preferably 50% or more and 100% or less, 70% or more and 95% or less, or 85% or more and 92% or less.

[0097] When the zirconia composition of this embodiment is in the form of a powder (hereinafter also referred to as "powder of this embodiment"), the powder may be a granular powder, which tends to improve flowability and moldability.

[0098] The average granule particle size of the granular powder is 30 μm or more, or 40 μm or more, and can be 100 μm or less, or 50 μm or less, and is preferably 40 μm or more and 50 μm or less.

[0099] The bulk density of the powder of this embodiment is 1.10 g / cm 3 More than 1.15g / cm 3 or more than 1.20g / cm 3 It must be equal to or greater than 1.40 g / cm 3 Below, 1.35g / cm 3 or less than 1.30g / cm 3 and 1.15 g / cm 3 More than 1.40g / cm 3 or less, or 1.20 g / cm 3 More than 1.30g / cm 3 It is preferable that:

[0100] The zirconia powder of this embodiment is filled into a mold with a diameter of 25 mm, subjected to uniaxial pressing at a pressure of 49 MPa, and then subjected to CIP treatment at a pressure of 196 MPa. The density of the powder is 3.2 g / cm3 or more than 3.3g / cm 3 It is sufficient if it is 3.5g / cm or more. 3 Less than or equal to 3.4g / cm 3 In particular, when 3.0±0.1 g of the zirconia powder of this embodiment is filled into a mold having a diameter of 25 mm, uniaxially press-molded under a pressure of 49 MPa, and then subjected to CIP treatment under a pressure of 196 MPa, the measured density is 3.2 g / cm 3 or more than 3.3g / cm 3 and 3.5 g / cm 3 Less than or equal to 3.4g / cm 3 The following are listed: 3 More than 3.5g / cm 3 or less than 3.3 g / cm 3 More than 3.4g / cm 3 The following is preferred:

[0101] Furthermore, when the zirconia composition of this embodiment is in the form of a molded body (hereinafter also referred to as "molded body of this embodiment"), the measured density thereof may be the same as the above-mentioned measured density, and may be 3.2 g / cm. 3 or more than 3.3g / cm 3 and 3.5 g / cm 3 Less than or equal to 3.4g / cm 3 The following can be exemplified: 3.2 g / cm 3 More than 3.5g / cm 3 or less than 3.3 g / cm 3 More than 3.4g / cm 3 The following is preferred:

[0102] The shape of the molded body of this embodiment may be any shape as long as it is similar to the shape of the target calcined body, and may be, for example, one or more shapes selected from the group consisting of disk, cylinder, cube, rectangular parallelepiped, polyhedron, cone, sphere, and approximately spherical, or even the shape of a dental prosthetic material.

[0103] The molded article of this embodiment may have a hardness that makes it less susceptible to breakage during handling, and examples of such hardness include a Vickers hardness of 10.0 HV or more, 11.0 HV or more, or 11.5 HV or more, and 14.0 HV or less, 13.0 HV or less, or 12.0 HV or less, such as 10.0 HV or more and 14.0 HV or less, 11.0 HV or more and 13.0 HV or less, or 11.5 HV or more and 12.0 HV or less. When the Vickers hardness is 11.0 or more, defects during handling are less likely to occur.

[0104] The compact of this embodiment is obtained by compacting the powder of this embodiment, but values measured by FE-EPMA such as high strength ratio, composition, BET specific surface area, etc. do not change before and after compaction.

[0105] The zirconia composition of the present embodiment can be used for known applications of zirconia, but is preferably used as a precursor for at least one of a sintered body and a calcined body, and is preferably used as at least one of a dental material and a precursor thereof.

[0106] [Method of producing zirconia composition] The method for producing the zirconia composition of the present embodiment may be any method that can produce a zirconia composition that satisfies the above-described configuration.

[0107] A preferred method for producing the zirconia composition of the present embodiment in the form of powder includes a zirconia powder containing one or more M1 elements selected from the group consisting of manganese, iron, cobalt, nickel, copper, molybdenum, technetium, ruthenium, rhodium, palladium, and silver, and zirconia containing a stabilizing element, wherein, when the characteristic X-rays of the zirconium element and the characteristic X-rays of the M1 element are measured, the ratio of the intensity of the characteristic X-rays of the M1 element to the intensity of the characteristic X-rays of the zirconium element is 0.05 or more at 2% or less of all measurement points; and A zirconia powder containing at least one coloring element selected from the group consisting of a lanthanoid rare earth element and an M2 element different in type from the M1 element, and zirconia, a mixing step of mixing the zirconia composition and the zirconia powder so that the content of the M1 element is 100 ppm by mass or more and the content of the M2 element is less than 100 ppm by mass.

[0108] In the mixing step, a zirconia powder (hereinafter also referred to as "raw material powder 1") containing one or more M1 elements selected from the group consisting of manganese, iron, cobalt, nickel, copper, molybdenum, technetium, ruthenium, rhodium, palladium, and silver, and stabilizing element-containing zirconia, where the ratio of the characteristic X-ray intensity of the M1 element to the characteristic X-ray intensity of the zirconium element is 0.05 or greater at 2% or less of all measurement points, is mixed with a zirconia powder (hereinafter also referred to as "raw material powder 2") containing at least one coloring element selected from the group consisting of a lanthanide rare earth element and an M2 element different from the M1 element, and zirconia. Unlike the case where a mixed powder is obtained by directly mixing zirconia powder with a compound of the M1 element, the manufacturing method of this embodiment uses zirconia containing the M1 element and the like as a starting material. This makes it easier to make the M1 element and coloring element more uniform, even when dry mixing or other simple mixing methods are used.

[0109] The raw material powder 1 contains an M1 element. The M1 element contained in the raw material powder 1 may be the same as the M1 element in the zirconia composition of the present embodiment.

[0110] In order to ensure that the content of the M1 element in the zirconia composition obtained by the mixing step is 100 ppm by mass or more, the content of the M1 element in the raw material powder 1 may be the same as the amount of the M1 element in the zirconia composition of the present embodiment described above, but may be, for example, more than 0.01% by mass (more than 100 ppm by mass), 0.05% by mass or more (500 ppm by mass or more), or 0.1% by mass or more (1000 ppm by mass or more), or 0.3% by mass or less (3000 ppm by mass or more), 0.25% by mass or less (2500 ppm by mass or less), or 0.2% by mass or less (2000 ppm by mass or less).

[0111] When the characteristic X-rays of zirconium and M1 are measured in raw material powder 1, the ratio of the intensity of the characteristic X-rays of M1 to the intensity of the characteristic X-rays of zirconium (X-ray intensity ratio) of the measurement points where the ratio is 0.05 or more (high intensity ratio) is 2% or less of all measurement points. By satisfying this high intensity ratio, it is thought that aggregation of M1 element also in raw material powder 1 will be reduced.

[0112] The high strength ratio in raw material powder 1 is 2% or less, 1% or less, or 0.1% or less, and can be exemplified as 0% or more, more than 0%, or 0.01% or more, and can be exemplified as 0% or more and 2% or less, more than 0% and 1% or less, or 0.01% or more and 0.1% or less.

[0113] The raw material powder 1 preferably does not have coarse agglomerates of the M1 element, and the proportion of measurement points where the X-ray intensity ratio is 0.1 or more (coarse intensity proportion) is preferably 0.5% or less, 0.1% or less, or 0.05% or less. The coarse intensity proportion may be 0% or more or more than 0%, and is preferably 0% or more and 0.5% or less, or 0% or more and 0.05% or less.

[0114] The measurement of the characteristic X-rays of zirconium element and the characteristic X-rays of M1 element in the raw material powder 1 of this embodiment may be performed by FE-EPMA in the same manner as the zirconia composition of this embodiment, except that the following conditions are met.

[0115] Accelerating voltage: 15 kV Irradiation current: 50nA Beam diameter: 1 μm Capture time: 50 msec Magnification: 5000x Analysis area: 45.32μm×45.32μm The maximum value (maximum intensity ratio) of the X-ray intensity ratio of raw material powder 1 is preferably 0.9 or less, 0.5 or less, or 0.2 or less. When the X-ray intensity ratio is within this range, aggregation of the M1 element is less likely to occur in the zirconia composition of this embodiment. The maximum intensity ratio of raw material powder 1 may be 0.05 or more or 0.08 or more, and examples thereof include 0.05 to 0.9 or 0.08 to 0.2.

[0116] The minimum intensity ratio of the X-ray intensity ratio of the raw material powder 1 can be, for example, 0 or more or more than 0, and may be 0.01 or less, 0 or more and 0.01 or less, or more than 0 and 0.01 or less.

[0117] For the same reasons as for the intensity ratio range in the zirconia composition of this embodiment, the distribution width (intensity ratio range) of the X-ray intensity ratio of raw material powder 1 is 0.9 or less, 0.5 or less, or 0.2 or less, and may be greater than 0 or greater than 0.01, for example, greater than 0 and less than 0.9, or greater than 0.01 and less than 0.2.

[0118] The raw material powder 1 contains zirconia containing a stabilizing element. The type and content of the stabilizing element may be the same as those of the zirconia containing a stabilizing element contained in the zirconia composition of the present embodiment.

[0119] The raw material powder 2 contains at least one coloring element (secondary coloring component) selected from the group consisting of a lanthanoid rare earth element and an M2 element different from the M1 element. The secondary coloring component contained in the raw material powder 2 may be the same as that contained in the zirconia composition of the present embodiment.

[0120] The content of the M2 element in the raw material powder 2 may be the same as the amount of the M2 element in the zirconia composition of the present embodiment described above, and may be, for example, 800 ppm by mass or less, 500 ppm by mass or less, or 100 ppm by mass or less, or may be more than 0 ppm by mass, 10 ppm by mass or more, or 30 ppm by mass or more. The preferred content of the lanthanoid rare earth element contained in the raw material powder 2 may be the same as the content of the lanthanoid rare earth element in the zirconia composition of the present embodiment described above, but examples thereof include 4 mass% or more, 6 mass% or more, or 8 mass% or more, and 20 mass% or less, 15 mass% or less, 12 mass% or less, or 10 mass% or less.

[0121] Raw material powder 2 contains zirconia. When the secondary coloring component is an element M2, the zirconia is preferably zirconia containing a stabilizing element. On the other hand, when the secondary coloring component is a lanthanoid rare earth element, the zirconia is preferably lanthanoid rare earth element-doped zirconia.

[0122] When the zirconia contained in the raw material powder 2 is zirconia containing a stabilizing element, the type and content of the stabilizing element may be the same as those of the zirconia containing a stabilizing element contained in the zirconia composition of this embodiment.

[0123] When the zirconia contained in raw material powder 2 is zirconia containing a stabilizing element, the amounts of the stabilizing element in raw material powders 1 and 2 are preferably the same, and for example, the difference in the amount of the stabilizing element between raw material powders 1 and 2 is 1.5 mol% or less or 1.0 mol% or less, or 0 mol% or more or more than 0 mol%. On the other hand, when raw material powder 2 contains a lanthanoid rare earth element, the difference in the amount of the stabilizing element between raw material powders 1 and 2 is equal to the amount of the stabilizing element in raw material powder 1.

[0124] In order to achieve the desired contents of the M1 element and coloring element, it is preferable to further mix a stabilizing element-containing zirconia powder (hereinafter also referred to as "raw material powder 3") that does not contain a transition metal element or a lanthanoid rare earth element in addition to raw material powder 1 and raw material powder 2 in the mixing step.

[0125] The raw material powder 3 is a stabilizing element-containing zirconia powder that does not contain transition metal elements or lanthanoid rare earth elements, and is preferably an yttrium-containing zirconia powder that does not contain transition metal elements or lanthanoid rare earth elements.

[0126] The amount of the stabilizing element in the raw material powder 3 may be the same as the type and content of the stabilizing element in the raw material powder 1 and the zirconia composition of this embodiment.

[0127] In the mixing step, an M3 element source may be supplied in addition to the raw material powders 1 to 3. Examples of the M3 element source include at least one of a salt and a compound containing one or more selected from the group consisting of titanium, vanadium, and niobium, and examples thereof include at least one selected from the group consisting of oxides, hydroxides, oxyhydroxides, halides, carbonates, sulfates, nitrates, and acetates containing one or more selected from the group consisting of titanium, vanadium, and niobium, preferably at least one selected from the group consisting of oxides, hydroxides, oxyhydroxides, chlorides, and acetates containing one or more selected from the group consisting of titanium, vanadium, and niobium, and more preferably at least one of oxides and hydroxides containing one or more selected from the group consisting of titanium, vanadium, and niobium.

[0128] 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 (Ti(SO4)2), titanium nitrate (Ti(NO3)2), and titanium acetate (Ti(CH3COO)4).

[0129] Examples of the vanadium source include one or more selected from the group consisting of vanadium oxide (VO), vanadium pentoxide (VO), vanadium hydroxide (V(OH)), vanadium oxyhydroxide (VO(OH)), vanadium(III) chloride (VCl), vanadium sulfate (V(SO)), and vanadium acetate (V(CHCOO)).

[0130] As a source of niobium, for example, from the group of niobium oxide (Nb2O5), vanadium hydroxide (V(OH)5), niobium(V) chloride (Nb15) and niobium acetate (V(CH3COO)3) There are one or more choices.

[0131] The M3 element source may be mixed so that the zirconia composition obtained by the mixing step has a content of the M3 element equivalent to the content of the M3 element in the zirconia composition of the present embodiment described above.

[0132] In addition to the M3 element source, or instead of the M3 element source, at least one of the raw material powders 1 to 3 may contain the M3 element.

[0133] In the mixing step, in addition to the raw material powders 1 to 3, a source of an additive component may be provided.

[0134] The additive component source may be at least one of a salt and a compound containing one or more selected from the group consisting of aluminum, silicon, and germanium, and may be one or more selected from the group consisting of oxides, hydroxides, oxyhydroxides, halides, carbonates, sulfates, nitrates, and acetates containing one or more selected from the group consisting of aluminum, silicon, and germanium. Preferred additive component sources include one or more selected from the group consisting of alumina, silica, and germania, and more preferably alumina.

[0135] The source of the additive component may be mixed so that the zirconia composition obtained by the mixing step has a content equivalent to that of the additive component in the zirconia composition of the present embodiment described above.

[0136] In addition to the additive component source, or instead of the additive component source, at least one of the raw material powders 1 to 3 may contain an additive component.

[0137] The raw material powders 1 to 3 may contain a binder. The inclusion of a binder improves operability (handling) and shape retention. The binder and its content may be the same as the binder contained in the zirconia composition of the present embodiment described above.

[0138] Each of the starting materials, such as raw material powders 1 to 3, preferably has similar physical properties to the zirconia powder of this embodiment, and each of the starting materials preferably has similar physical properties to each other. The physical properties of each starting material include the following.

[0139] The BET specific surface area of each starting material is 8 m 2 / g or more or 10m 2 / g or more, and 15m 2 / g or less, 12m 2 / g or less, 11m 2 / g or less or 10.5m 2 / g or less, and 2 / g or more 15m 2 / g or less, or 10m 2 / g or more 12m 2 For example, it can be exemplified as being / g or less.

[0140] The average particle size of each starting material is preferably 0.35 μm or more or 0.4 μm or more, and more preferably 0.55 μm or less or 0.5 μm or less, 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.

[0141] The T+C phase ratio of each starting material is preferably 50% or more, 55% or more, or 60% or more, and is preferably 100% or less, 99% or less, 95% or less, 92% or less, or 90% or less.

[0142] Each starting material is preferably a granular powder, and the average particle size of the granular powder may be 30 μm or more or 40 μm or more, and may be 100 μm or less or 50 μm or less, and is preferably 30 μm or more and 100 μm or less, or 40 μm or more and 50 μm or less.

[0143] In the mixing step, the starting materials may be mixed so that the content of the M1 element is 100 ppm by mass or more and the content of the M2 element is less than 100 ppm by mass, and the amounts may be mixed so that the contents of the M1 and coloring elements are equivalent to those of the zirconia composition of the present embodiment described above.

[0144] The mixing method may be any method that can homogenize the starting materials, and may be at least either dry mixing or wet mixing, or may be dry mixing. In the production method of this embodiment, zirconia powders that already contain the M1 element and coloring components are mixed together, so that localization of the M1 element is unlikely to occur even when a simple mixing method such as shaking or stirring is used.

[0145] The mixing ratio of each starting material may be any desired ratio depending on the desired content of the M1 element, etc., and the desired color tone. For example, the starting materials may be mixed in the following ratios so that the total is 100% by mass.

[0146] Raw material powder 1: 15% by mass or more, 18% by mass or more, or 20% by mass or more, 80% by mass or less, 75% by mass or less, or 70% by mass or less Raw material powder 2 containing M2 element :0 mass% or more, more than 0 mass%, 1 mass% or more, 3 mass% or more, or 5 mass% or more, 30% by mass or less, 20% by mass or less, or 18% by mass or less Raw material powder containing lanthanide rare earth elements 2 :0 mass% or more, more than 0 mass%, 0.5 mass% or more, 0.8 mass% or more, or 1 mass% or more, 10% by mass or less, 8% by mass or less, or 3% by mass or less, Raw material powder 3: 15% by mass or more, 18% by mass or more, or 20% by mass or more, 80% by mass or less, 75% by mass or less, or 70% by mass or less M3 element source: 0 mass% or more, more than 0 mass%, 0.05 mass% or more, 0.10 mass% or more, or 0.20 mass% or more, 1.0% by mass or less, 0.8% by mass or less or 0.7% by mass or less Additive ingredient source: 0% by mass or more, more than 0% by mass, 0.003% by mass or more, or 0.01% by mass or more, 0.1% by mass or less, 0.08% by mass or less or 0.06% by mass or less When the zirconia composition of the present embodiment is in the form of a molded body (compressed powder), a preferred production method is a method for producing a zirconia composition (zirconia molded body) that includes a molding step of molding the zirconia powder obtained by the above-mentioned mixing step. The molding method may be any method capable of forming a green compact from a zirconia composition (zirconia powder), 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, with at least one of uniaxial pressing and CIP being more preferred, and a method in which a zirconia composition is uniaxially pressed and the resulting primary compact is subjected to CIP. The pressure in the uniaxial pressing may be, for example, 15 MPa or more or 90 MPa or more, and 400 MPa or less or 150 MPa or less.

[0147] [Method of manufacturing raw material powder] A preferred method for producing raw material powder 1 includes a step of drying a slurry containing hydrated zirconia, a stabilizing element source, and an M1 element source to obtain a dry powder, and a step of heat-treating the dried powder at a temperature below the sintering temperature. When powdered zirconia is mixed with the M1 element source, localization of the M1 element is likely to occur. The localized M1 element, even if below the detection limit, significantly affects the thermal shrinkage behavior of the resulting zirconia composition. In contrast, mixing zirconia with the M1 element source at the powder precursor stage is thought to suppress localization of the M1 element, which could affect the shrinkage behavior of the zirconia composition. Raw material powder 1 is preferably a powder obtained from a solution containing a zirconia precursor and the M1 element, a powder whose precursor is at least one of a hydrolyzate and a coprecipitate obtained from a solution containing hydrated zirconia and the M1 element, or a powder whose precursor is a hydrolyzate obtained from a solution containing hydrated zirconia and the M1 element.

[0148] In the step of drying a solution containing hydrated zirconia, a stabilizing element source, and an M1 element source to obtain a dry powder (hereinafter also referred to as the "precursor synthesis step"), a solution containing hydrated zirconia, a stabilizing element source, and an M1 element source (hereinafter also referred to as the "raw material solution") is provided. The contents of hydrated zirconia, the stabilizing element source, and the M1 element source contained in the raw material solution may be the same as those in the composition of the raw material powder 1 described above.

[0149] The pH of the raw material solution is preferably 7 or less or 5 or less, as this makes it easier to disperse hydrated zirconia, and may be 1 or more or 3 or more.

[0150] The hydrated zirconia is zirconia in a hydrated state (ZrO2·nH2O, where n is an integer), and is preferably a hydrated zirconia sol. The hydrated zirconia is preferably hydrated zirconia obtained by one or more methods selected from the group consisting of hydrolysis, coprecipitation, and neutralization of zirconium salts, and is preferably hydrated zirconia obtained by hydrolysis, and is preferably hydrated zirconia obtained by hydrolysis or coprecipitation of one or more methods selected from the group consisting of zirconium oxychloride, zirconyl nitrate, zirconium chloride, and zirconium sulfate, and is preferably hydrated zirconia obtained by hydrolysis or coprecipitation of zirconium oxychloride.

[0151] 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 examples thereof include one or more selected from the group consisting of oxides, hydroxides, oxyhydroxides, halides, carbonates, sulfates, nitrates, and acetates containing the stabilizing element. It is more preferable that it is at least any one of oxides, hydroxides, and chlorides containing the stabilizing element, and even more preferable that it is a chloride containing the stabilizing element.

[0152] 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, with yttrium chloride being preferred.

[0153] 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.

[0154] 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.

[0155] The M1 element source (hereinafter, when the M1 element is iron or the like, it will also be referred to as "iron source" or the like) may be at least any one of a salt and a compound containing the M1 element, and examples thereof include one or more selected from the group consisting of oxides, hydroxides, oxyhydroxides, halides, carbonates, sulfates, nitrates, and acetates containing the M1 element, more preferably at least any one of oxides, hydroxides, and chlorides containing the M1 element, and even more preferably an oxide containing the M1 element. Main M1 sources include the following:

[0156] Examples of the manganese source include one or more selected from the group consisting of manganese oxide (II) (MnO), manganese oxide (III) (Mn2O3), manganese dioxide (MnO2), manganese tetroxide (Mn3O4), manganese hydroxide (Mn(OH)2), manganese oxyhydroxide (MnOOH), manganese chloride (MnCl2), manganese carbonate (MnCO3), manganese sulfate (MnSO4), manganese nitrate (Mn(NO3)2), and manganese acetate (Mn(COOH)2), and further include at least one of manganese hydroxide and manganese acetate.

[0157] 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), and is preferably one or more selected from the group consisting of iron hydroxide (III), iron hydroxide (II), iron chloride (III), and iron chloride (II).

[0158] 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 (Co(CHOO)).

[0159] The nickel source may, for example, be one or more selected from the group consisting of nickel (II) oxide (NiO), nickel (IV) oxide (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 (Ni(CH3COO)2).

[0160] Examples of the copper source include one or more selected from the group consisting of copper (II) oxide (CuO), copper (IV) oxide (CuO2), copper trioxide (Cu3O4), copper hydroxide (Cu(OH)2), copper oxyhydroxide (CuOOH), copper chloride (CuCl2), copper carbonate (CuCO3), copper sulfate (CuSO4), copper nitrate (Cu(NO3)2), and copper acetate (Cu(CH3COO)2).

[0161] The solvent contained in the raw material solution may be at least one of a polar solvent and a nonpolar solvent as long as it disperses hydrated zirconia. It is preferably at least one of alcohol and water, more preferably at least one of ethanol and water, or even more preferably water. Examples of water contained in the raw material composition include at least one of pure water and ion-exchanged water. Alternatively, 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.

[0162] When the raw material powder 1 contains an M3 element, the raw material solution may contain the above-mentioned M3 element source.

[0163] The raw material solution can be obtained by any method as long as it allows hydrated zirconia, a stabilizing element source, and an M1 element source to be uniformly mixed. Examples of methods for producing the raw material solution include (1) a method of mixing hydrated zirconia, a stabilizing element source, an M1 element source, and a solvent, (2) a method of mixing a hydrated zirconia solution with a stabilizing element source and an M1 element source, and (3) a method of mixing a hydrated zirconia solution with a solution containing a stabilizing element source and a solution containing an M1 element source. Preferred mixing methods include a production method comprising a step of mixing a hydrated zirconia solution with a solution containing an M1 element source and a stabilizing element source, as well as a production method comprising a step of mixing a hydrated zirconia solution obtained by hydrolyzing a zirconium salt with a solution containing an M1 element source and a stabilizing element source.

[0164] The drying method in the drying step may be any known method that removes the solvent and hydrated water of zirconia from the raw material solution. This results in a dry powder. Any drying method may be selected depending on the concentration and amount of the raw material solution to be subjected to the drying step. The following drying conditions may also be used:

[0165] 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 The drying method and drying time of the raw material solution may be appropriately determined depending on the amount of raw material solution to be treated and the type and characteristics of the drying furnace. The drying time may be 5 hours or more, 10 hours or more, and 75 hours or less, or 50 hours or less.

[0166] The method for producing the raw material powder 1 includes a heat treatment step in which the dried powder is heat treated at a temperature below the sintering temperature. This heat treatment efficiently dissolves the stabilizing element in zirconia, yielding the raw material powder 1. In addition, by undergoing this thermal history before forming into a compact (green compact), aggregation of the M1 element during heat treatment after compacting is further suppressed.

[0167] The heat treatment temperature in the heat treatment is a temperature that promotes the dissolution of the stabilizing element into zirconia, and any temperature below the sintering temperature may be applied so as to obtain the desired BET specific surface area. The higher the heat treatment temperature, the lower the BET specific surface area tends to be. Examples of 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, 1050°C or higher, or 1100°C or higher.

[0168] 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.

[0169] Heat treatment atmosphere: oxidizing atmosphere, preferably air atmosphere; Heat treatment temperature: 1000°C or higher, 1025°C or higher, or 1050°C or higher, and 1200℃ or less or 1150℃ or less 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 type and 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.

[0170] When the raw material powder 1 contains an additional component, the aforementioned source of the additional component may be mixed with the heat-treated raw material powder 1. The mixing method may be a known method, and may be carried out simultaneously with the pulverization step described below. The amount of the source of the additional component contained in the raw material powder 1 may be the same as the amount of the aforementioned additional component.

[0171] In order to adjust the particle size of the raw material powder 1, the manufacturing method of the raw material powder 1 may include a step of pulverizing the powder (hereinafter also referred to as the "pulverizing step"). The pulverization may be performed by any method that allows the powder to have a desired particle size, and may be at least one of dry pulverization and wet pulverization. Due to high pulverization efficiency, wet pulverization is preferred, and further pulverization using one or more selected from the group consisting of a vibration mill, a ball mill, and a bead mill, or even pulverization using a ball mill and a bead mill is preferred.

[0172] 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. As the pulverization time increases, the particle size decreases until it reaches an equilibrium size.

[0173] In order to control the flowability of the powder or improve its moldability, the manufacturing method of the raw material powder 1 may include a step of granulating the powder to obtain granulated powder (hereinafter also referred to as the "granulation step"). Granulation may be any method in which secondary particles of the powder slowly aggregate to form granulated particles. Examples of the granulation method include one or more selected from the group consisting of spray drying, agitation granulation, and extrusion granulation, and further include spray drying. In the spray drying method, the powder to be granulated is dispersed in a solvent to form a slurry, which is then spray-dried to obtain granulated powder. The solvent may be at least one of water and alcohol. If necessary, a binder such as an acrylic resin may be mixed with the slurry, followed by spray drying to obtain granules.

[0174] The raw material powders 2 and 3 may be produced by any method.

[0175] For example, raw material powder 2 containing an M2 element source can be produced by a method similar to that of raw material powder 1, except that an M2 element source is used instead of the M1 element source, or by a production method in which zirconia powder not containing a coloring component is mixed with at least one of a compound and a salt containing the M2 element.

[0176] Furthermore, raw material powder 2 containing a lanthanoid rare earth element can be produced by a method similar to that for producing raw material powder 1, except that a lanthanoid rare earth element source is used instead of the stabilizing element source and the M1 element source.

[0177] The lanthanoid rare earth element source may be at least one of a salt and a compound containing a lanthanoid rare earth element, and examples thereof include one or more selected from the group consisting of oxides, hydroxides, oxyhydroxides, halides, carbonates, sulfates, nitrates, and acetates containing a lanthanoid rare earth element. At least one of oxides, hydroxides, and chlorides containing a lanthanoid rare earth element is more preferred, and an oxide containing a lanthanoid rare earth element is even more preferred.

[0178] Furthermore, for example, raw material powder 3 can be produced by the same method as raw material powder 1, except that the M1 element source is not used. [Calcined body and its manufacturing method] The zirconia composition of the present embodiment can be used as a precursor of a calcined body, and can be subjected to a method for producing a calcined body, which includes a step of calcining the zirconia composition of the present embodiment (hereinafter also referred to as a "calcining step").

[0179] By calcining the zirconia composition, a calcined body (hereinafter also referred to as "calcined body of this embodiment") is obtained.

[0180] The calcination in the calcination step may be a heat treatment at a temperature lower than the sintering temperature of zirconia, and is preferably atmospheric pressure calcination. The calcination method may be any method that can obtain a calcined body having the desired properties, and the following methods and conditions can be exemplified.

[0181] Calcination atmosphere: an atmosphere other than a reducing atmosphere, preferably an oxidizing atmosphere; More preferably, the 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 200℃ / hour or less or 150℃ / hour or less The time for which the zirconia composition is held at the calcination temperature (hereinafter also referred to as the "calcination time") may be appropriately adjusted depending on the shape, size, and amount of the zirconia composition to be calcined, as well as the type and performance of the calcination furnace. The calcination time may be, for example, 0.5 hours or more or 1 hour or more, and may be 7 hours or less or 3 hours or less.

[0182] When the zirconia composition of the present embodiment contains a binder, the binder may be removed during heating to the calcination temperature. Alternatively, a step of removing the binder, a so-called degreasing step, may be performed prior to the calcination step. Any method for removing the binder may be used, and may be appropriately selected depending on the shape and size of the zirconia composition, as well as the degreasing method and properties. An example of the method for removing the binder is heat treatment in an air atmosphere at 400°C or higher and lower than 800°C.

[0183] The calcined body of this embodiment differs from powders and compacts (compressed powders) in that it is composed of fused particles. The fused particles have a structure at the initial stage of sintering, and the calcined body has a structure in which the particles form a necking while retaining some of the shape of the powder particles contained in the zirconia composition of this embodiment. This gives the calcined body mechanical properties suitable for machining.

[0184] The shape of the calcined body of this embodiment may be any shape depending on the intended purpose, etc. Examples of the shape of the calcined body include one or more selected from the group consisting of disk, columnar, cubic, rectangular parallelepiped, polyhedral, spherical, and approximately spherical shapes, and the shape of a dental prosthesis.

[0185] The measured density of the calcined body of this embodiment (calcined body density) is 2.8 g / cm 3 or more than 3.2g / cm 3 and 3.5 g / cm 3 Less than or equal to 3.4g / cm 3 It is noted that it is less than 2.8g / cm 3 More than 3.5g / cm 3 or less than 3.2gcm 3 More than 3.4g / cm 3 It is preferable that the density is equal to or less than 1000. Since densification hardly progresses in the calcined body, the density of the calcined body may be equal to the measured density of the green body (green body density).

[0186] The calcined body of this embodiment may have a hardness suitable for CAD / CAM machining, for example, a Vickers hardness of 25 HV or more and 150 HV or less (25 kgf / mm 2 More than 150kgf / mm 2 The calcined body of this embodiment preferably has a Vickers hardness of 30HV or more, 40HV or more, or 45HV or more, and 70HV or less, 60HV or less, 55HV or less, or 50HV or less.

[0187] It is preferable that the variation in Vickers hardness between calcined bodies produced under the same conditions from the zirconia composition of the present embodiment having the same composition is small, and the standard deviation of Vickers hardness between the calcined bodies is preferably 4 HV or less or 3 HV or less. Although it is preferable that the standard deviation of Vickers hardness is small, it can be 0 HV or more or exceed 0 HV.

[0188] Furthermore, it is preferable that the calcined body of this embodiment has a small difference in hardness due to compositional differences. For example, the absolute value of the difference (hereinafter simply referred to as "hardness difference") between the hardness of a calcined body obtained from a commercially available powder (product name: Zpex4, manufactured by Tosoh Corporation) under the following molding and calcination conditions and the hardness of a calcined body obtained from the zirconia composition of this embodiment under the same molding and calcination conditions is preferably 10 HV or less, 9 HV or less, 7 HV or less, 6 HV or less, or 5 HV or less. The smaller the hardness difference, the more preferable it is, and examples of the hardness difference include 0 HV or more, more than 0 HV, 1 HV or more, or 2 HV or more. Examples of the hardness difference of the calcined body of this embodiment include 0 HV or more and 10 HV or less, more than 0 HV and 9 HV or less, or 2 HV or more and 5 HV or less. (Molding conditions) Molding method: Uniaxial pressure and CIP treatment Uniaxial pressure: 49±3MPa CIP pressure: 196±5MPa (Press firing conditions) Press firing method: Normal pressure firing Atmosphere: Air Firing temperature: 1000℃ Baking time: 1 hour Heating rate: 50±5℃ / hour Cooling rate: 300±10℃ / hour

[0189] The calcined body of this embodiment can be used for known applications, such as use as a calcined body for dental prostheses, and further use as a dental mill blank. [Sintered body and its manufacturing method] At least one of the zirconia composition and the calcined body of this embodiment can be used as a precursor of a sintered body, and at least one of the zirconia composition and the calcined body of this embodiment can be used in a method for producing a sintered body, which includes a step of sintering at least one of the zirconia composition and the calcined body of this embodiment (hereinafter also referred to as a "sintering step").

[0190] A sintered body (hereinafter also referred to as "the sintered body of this embodiment") is obtained by sintering at least one of the zirconia composition and the calcined body.

[0191] As the sintering method in the sintering step, any sintering method that promotes densification of zirconia can be applied. As the sintering method, one or more sintering methods selected from the group consisting of pressure sintering, vacuum sintering, and atmospheric sintering are preferred, atmospheric sintering is more preferred, and atmospheric sintering in an air atmosphere is even more preferred. By atmospheric sintering, a sintered body can be obtained as an atmospheric sintered body.

[0192] Preferable conditions for atmospheric sintering include the following.

[0193] Sintering atmosphere: an atmosphere other than a reducing atmosphere, preferably an oxidizing atmosphere, More preferably, the air atmosphere 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 Heating rate: 50°C / hour or more, 100°C / hour or more, or 150°C / hour or more, and 800℃ / hour or less or 700℃ / hour or less The holding time at the treatment temperature (hereinafter also referred to as "sintering time") may be adjusted appropriately depending on the shape, size, and amount of the zirconia composition to be sintered, as well as the type and performance of the sintering furnace. The sintering time may be, for example, 0.5 hours or more or 1 hour or more, or may be 5 hours or less or 3 hours or less.

[0194] Other preferred sintering conditions include the following. Sintering atmosphere: an atmosphere other than a reducing atmosphere, preferably an oxidizing atmosphere, More preferably, the air atmosphere 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 Temperature rise rate: 30 ° C. / min or more or 50 ° C. / min or more, and 300℃ / min or less or 250℃ / min or less Sintering time: 1 minute or more or 5 minutes or more, and 1 hour or less or 0.5 hours or less

[0195] The sintered body of this embodiment may have a composition similar to that of the zirconia composition and the calcined body described above.

[0196] The sintered body of this embodiment preferably has a color tone similar to any one of the colors of a dental shade sample, and more preferably has a color tone of A1, A2, A3, A3.5, A4, B1, B2, B3, B4, C1, C2, C3, C4, D2, D3, or D4 of a dental shade sample (e.g., Vita Classical Shade Guide).

[0197] The color tone of a sintered body varies depending on its translucency. For example, the color tone of a dental color sample for a sintered body with a total light transmittance of 24 to 44% is calculated by L. * a * b * When expressed in a color system, the following color tones can be exemplified.

[0198] [Table 1]

[0199] The sintered body of this embodiment preferably has a strength that allows it to be used as a dental prosthesis, and the three-point bending strength is preferably 550 MPa or more, 600 MPa or more, or 800 MPa or more. The three-point bending strength can be, for example, less than 1200 MPa, less than 1100 MPa, or 1000 MPa or less, and is preferably 550 MPa or more but less than 1200 MPa, or 800 MPa or more but 1000 MPa.

[0200] The sintered body of this embodiment may have translucency that provides aesthetics equivalent to those of natural teeth. Such total light transmittance may be 10% or more, 15% or more, or 25% or more, and 40% or less, 35% or less, or 30% or less, and is preferably 10% or more and 40% or less, 15% or more and 35% or less, or 25% or more and 30% or less.

[0201] Furthermore, it is preferable that the sintered body of this embodiment has a small difference in total light transmittance due to differences in composition. For example, the ratio (hereinafter also referred to as "transmittance ratio") of the total light transmittance of a sintered body obtained from the zirconia composition of this embodiment under the following molding, calcination, and sintering conditions to the total light transmittance of a sintered body obtained from a commercially available powder (product name: Zpex4, manufactured by Tosoh Corporation) under the same molding, calcination, and sintering conditions can be 0.5 or more, 0.6 or more, or 0.7 or more. A smaller transmittance ratio is preferable, but the darker the sintered body, the higher the transmittance ratio tends to be. Therefore, the transmittance ratio can be, for example, 1.0 or less or 0.9 or less, and preferably 0.5 to 1.0 or 0.7 to 0.9. (Molding conditions) Molding method: Uniaxial pressure and CIP treatment Uniaxial pressure: 49±3MPa CIP pressure: 196±5MPa (Press firing conditions) Press firing method: Normal pressure firing Atmosphere: Air Firing temperature: 1000℃ Baking time: 1 hour Heating rate: 50±5℃ / hour Cooling rate: 300±10℃ / hour (Sintering conditions) Sintering method: Atmospheric pressure sintering Atmosphere: Air Processing temperature: 1450℃ Sintering time: 2 hours Heating rate: 600±20℃ / hour Cooling rate: 600±50℃ / hour

[0202] The sintered body of the present embodiment can be applied to known uses of zirconia, and can be used, for example, as a structural material, an optical material, a dental material, a decorative material, and an exterior material for electronic devices, and is preferably used as a dental material, and further as a dental prosthesis.

[0203] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments. For example, the present disclosure also includes any combination of the constituent elements specifically described in the above-described embodiments, as well as any combination of upper and lower limit values within a numerical range. Furthermore, the present disclosure also includes any combination of the upper and / or lower limit values replaced with values from the examples described below. [Example]

[0204] The present embodiment will be described in detail below with reference to examples, but the present embodiment is not limited to these examples.

[0205] (composition analysis) The composition of 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.

[0206] (BET specific surface area) The BET specific surface area was measured by the BET multipoint method (5 points) using an automatic specific surface area measuring device (device name: Tristar II 3020, manufactured by Shimadzu Corporation) in accordance with JIS R 1626 under the following conditions. Adsorption medium: N2 Adsorption temperature: -196℃ Pretreatment conditions: Degassing in air at 250°C for at least 1 hour

[0207] (Crystal phase, tetragonal + cubic crystal ratio) The crystalline phase was identified by XRD measurement using an X-ray diffractometer (device name: Ultima IV, manufactured by RIGAKU Corporation) under the following conditions.

[0208] 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 The crystalline phases were identified by smoothing and background removal using the analysis program attached to the X-ray diffractometer (program name: Integrated Powder X-ray Analysis Software PDXL Ver. 2.2, manufactured by RIGAKU Corporation), and then profile fitting the processed XRD patterns using a split pseudo-Voigt function.

[0209] The tetragonal + cubic phase ratio (T + C phase ratio) was determined from the XRD patterns of the powder composition of this embodiment, the calcined body, and the sintered body, using the above formula.

[0210] (Average particle size) The average granule particle size was measured by particle size distribution measurement using a Microtrac particle size distribution analyzer (device name: MT3100II, manufactured by Microtrac Bell) using the laser diffraction / scattering method. The measurement conditions were as follows:

[0211] Light source: Semiconductor laser (wavelength: 780 nm) Voltage: 3mW Refractive index of zirconia: 2.17 Calculation mode: MT3000 The measurement sample was not subjected to any dispersion treatment such as ultrasonic treatment, and the granular powder in a slowly agglomerated state was used as is.

[0212] (Measured density) The masses of the compacts and the calcined bodies were measured with a balance, and the volumes were measured with calipers to determine the dimensions. The actual densities were calculated from the obtained masses and volumes, and were used as the compact density for the compacts and the calcined density for the calcined bodies.

[0213] (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.

[0214] Measurement sample: Disc-shaped with a thickness of 3.0±0.5mm Measurement load: 1kgf Load holding time: 5 seconds The Vickers hardness was measured on 10 compacts or calcined bodies prepared under the same conditions, and the average value was taken as the Vickers hardness. Prior to the measurement, the measurement surface of the measurement sample was polished with #800 waterproof abrasive paper to remove irregularities exceeding 0.1 mm as a pretreatment.

[0215] (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 used was a circular 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.

[0216] (color tone) Color tones were measured using a spectrophotometer (device name: CM-700d, manufactured by Konica Minolta) equipped with an illumination and light-receiving optical system conforming to geometric condition c of JIS Z 8722. The measurement conditions were as follows:

[0217] Light source: D65 light source Viewing angle: 10° Measurement method: SCI After cutting out a measurement sample from any part of the sintered body horizontally, both sides of the sample were mirror-polished to a diameter of 20 mm, a thickness of 1.0±0.1 mm, and a surface roughness (Ra) of 0.02 μm or less. The measurement sample was placed on a white plate, and both polished surfaces were used as evaluation surfaces. * , a * and b * ) was measured (measured against a white background). The effective area for color tone evaluation was 10 mm in diameter.

[0218] (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.

[0219] <Synthesis of raw material powder> Synthesis Example 1 Powders 1 to 9 were each synthesized by the following method. A hydrated zirconia aqueous solution obtained by hydrolyzing a zirconium oxychloride aqueous solution, an iron (III) chloride aqueous solution with an FeCl concentration of 45% by mass, and yttrium chloride were mixed to obtain the powder compositions shown in the table below to obtain raw material solutions. Each raw material solution was dried at 180°C in an air-circulating atmosphere to obtain dry powders, and then heat-treated in an air atmosphere at the temperatures shown in the table below to obtain calcined powders. 199.9 g of the obtained calcined powder and pure water were mixed in a ball mill, and then an acrylic resin and, if necessary, at least one of a slurry containing α-alumina powder and a slurry containing titanium oxide powder were added to obtain each slurry. The slurries were spray-dried in an air atmosphere at 180°C to obtain nine types of granular powders (powders 1 to 9).

[0220] Synthesis Example 2 A raw material solution having the powder composition shown in the table below was obtained in the same manner as in Synthesis Example 1, except that no aqueous iron(III) chloride solution was used. This was dried at 180°C in an air circulating atmosphere to obtain a dry powder, which was then heat-treated at 1175°C in an air atmosphere to obtain a calcined powder.

[0221] The calcined powder (199.9 g), α-alumina powder (0.1 g), iron oxyhydroxide (FeOOH) powder (0.45 g), and pure water were mixed in a ball mill, and then an acrylic resin was added to form a slurry. The slurry was spray-dried in the air at 180°C to obtain a granular powder (Powder 10).

[0222] The results of Synthesis Examples 1 and 2 are shown in the table below.

[0223] [Table 2]

[0224] Both Powders 1 and 10 contained iron, but Powder 1 had a high intensity ratio of 0.05%, a coarse intensity ratio of 0%, a maximum intensity ratio of 0.107, and a minimum X-ray intensity ratio of 0. In contrast, Powder 10 had a high intensity ratio of 2.04%, a coarse intensity ratio of 0.54%, a maximum intensity ratio of 0.901, and a minimum intensity ratio of 0.

[0225] Synthesis Example 3 A raw material solution having the powder composition shown in the table below was obtained in the same manner as in Synthesis Example 1, except that nickel oxide (NiO) powder was used instead of the iron (III) chloride aqueous solution. This was dried at 180°C in an air flow atmosphere to obtain a dry powder, which was then heat-treated at 1140°C in an air atmosphere to obtain a calcined powder.

[0226] The calcined powder (199.9 g), α-alumina powder (0.1 g), and pure water were mixed in a ball mill, and then an acrylic resin was added to form a slurry. The slurry was spray-dried in an air atmosphere at 180°C to obtain a granular powder (Powder 11).

[0227] Synthesis Example 4 A raw material solution was obtained in the same manner as in Synthesis Example 1, except that nickel oxide (NiO powder) was not used, so as to have the powder composition shown in the table below. This was dried at 180°C in an air circulating atmosphere to obtain a dry powder, which was then heat-treated at 1140°C in an air atmosphere to obtain a calcined powder.

[0228] The calcined powder (199.9 g), α-alumina powder (0.1 g), nickel oxide powder (0.1 g), and pure water were mixed in a ball mill, and then an acrylic resin was added to form a slurry. The slurry was spray-dried in an air atmosphere at 180°C to obtain a granular powder (Powder 12).

[0229] The results of Synthesis Examples 3 and 4 are shown in the table below.

[0230] [Table 3]

[0231] Synthesis Example 5 A raw material solution was prepared in the same manner as in Synthesis Example 1, except that tricobalt tetroxide (Co3O4) powder was used instead of the iron (III) chloride aqueous solution, so as to have the powder composition shown in the table below. This was dried at 180°C in an air circulating atmosphere to obtain a dry powder, which was then heat-treated at 1140°C in an air atmosphere to obtain a calcined powder.

[0232] 199.9 g of the calcined powder, 0.1 g of α-alumina powder, and pure water were mixed in a ball mill, and then an acrylic resin was added to form a slurry. The slurry was spray-dried in an air atmosphere at 180°C to obtain a granular powder (Powder 13).

[0233] Synthesis Example 6 Each raw material solution was obtained in the same manner as in Synthesis Example 1, except that no aqueous iron(III) chloride solution was used, so as to have the powder composition shown in the table below. This was dried at 180°C in an air circulating atmosphere to obtain a dry powder, which was then heat-treated in an air atmosphere at the calcination temperature shown in the table below to obtain each calcined powder.

[0234] 199.9 g of the calcined powder, 0.1 g of α-alumina powder, 0.1 g of cobalt oxide powder, and pure water were mixed in a ball mill, and then an acrylic resin was added to form a slurry. The slurry was spray-dried in an air atmosphere at 180°C to obtain granular powders (Powders 14 and 15).

[0235] Granular powder (powder 16) was also obtained in the same manner, except that 199.9 g of the calcined powder, 0.1 g of α-alumina powder, 0.08 g of cobalt oxide powder, 0.4 g of titanium oxide powder, and pure water were mixed in a ball mill.

[0236] The results of Synthesis Examples 5 and 6 are shown in the table below.

[0237] [Table 4]

[0238] Synthesis Example 7 A raw material solution was obtained in the same manner as in Synthesis Example 1, except that manganese tetroxide (MnO) powder was used instead of the iron (III) chloride aqueous solution, so as to have the powder composition shown in the table below. This was dried at 180°C in an air circulating atmosphere to obtain a dry powder, which was then heat-treated at 1140°C in an air atmosphere to obtain a calcined powder.

[0239] 199.9 g of the calcined powder, 0.1 g of α-alumina powder, and pure water were mixed in a ball mill, and then an acrylic resin was added to form a slurry. The slurry was spray-dried in an air atmosphere at 180°C to obtain a granular powder (Powder 17).

[0240] Synthesis Example 8 A raw material solution was obtained in the same manner as in Synthesis Example 1, except that trimanganese tetroxide powder was not used, so as to have the powder composition shown in the table below. This was dried at 180°C in an air circulating atmosphere to obtain a dry powder, which was then heat-treated at 1175°C in an air atmosphere to obtain a calcined powder.

[0241] The calcined powder (199.9 g), α-alumina powder (0.1 g), manganese dioxide powder (0.1 g), and purified water were mixed in a ball mill, and then an acrylic resin was added to form a slurry. The slurry was spray-dried in an air atmosphere at 180°C to obtain a granular powder (Powder 18).

[0242] The results of Synthesis Examples 7 and 8 are shown in the table below.

[0243] [Table 5]

[0244] Synthesis Example 9 Raw material solutions were prepared in the same manner as in Synthesis Example 1, except that no aqueous iron (III) chloride solution was used and that erbium oxide was used instead of yttrium chloride, so as to have the powder compositions shown in the table below. These were dried at 180°C in an air circulating atmosphere to obtain dry powders, which were then heat-treated in an air atmosphere at the calcination temperatures shown in the table below to obtain calcined powders.

[0245] The calcined powder (199.9 g), α-alumina powder (0.1 g), and pure water were mixed in a ball mill, and then an acrylic resin was added to form a slurry. The slurry was spray-dried in an air atmosphere at 180°C to obtain granular powders (powders 19 and 20). The results are shown in the table below.

[0246] [Table 6]

[0247] Synthesis Example 10 Raw material solutions were prepared in the same manner as in Synthesis Example 1, except that no aqueous iron(III) chloride solution was used, so as to obtain the powder compositions shown in the table below. These were dried at 180°C in an air circulating atmosphere to obtain dry powders, which were then heat-treated in an air atmosphere at the calcination temperatures shown in the table below to obtain calcined powders.

[0248] The calcined powder (199.9 g), α-alumina powder (0.1 g), and pure water were mixed in a ball mill, and then an acrylic resin was added to form a slurry. The slurry was spray-dried in an air atmosphere at 180°C to obtain granular powders (powders 21 and 23).

[0249] Furthermore, commercially available zirconia powder (product name: Zpex4, manufactured by Tosoh Corporation) was used as powder 22. The composition and physical properties of the granular powder are shown in the table below.

[0250] [Table 7]

[0251] Examples 1 to 7 and Comparative Examples 1 to 3 Each powder was filled into a 200 mL polypropylene container in the mass ratio shown in the table below, and the container was stirred to dry mix the powder to obtain a powder composition of each Example and Comparative Example. The results are shown in the table below.

[0252] [Table 8]

[0253] Examples 1 and 4 and Comparative Example 1 are powders having compositions corresponding to the sintered body having the color tone of dental shade sample C1. Examples 2 and 5 and Comparative Example 2 are powders having compositions corresponding to the sintered body having the color tone of dental shade sample C3. Examples 3 and 6 and Comparative Example 3 are powders having compositions corresponding to the sintered body having the color tone of dental shade sample C4.

[0254] The high strength ratio was 0% (0.002%) in Example 1, 0.02% in Example 2, and 0.03% in Example 3, confirming that the high strength ratio tends to increase as the Fe2O3 content increases. On the other hand, the high strength ratio in Comparative Example 3 was 3.06%, which was more than 100 times that of Example 3. Furthermore, the coarse strength ratio was 0% in all of Examples 1 to 3, while it was 0.38% in Comparative Example 3, confirming that the iron in Comparative Example 3 was more coagulated than in the Examples.

[0255] The maximum intensity ratio was 0.053 for Example 1, 0.054 for Example 2, 0.057 for Example 3, and 0.334 for Comparative Example 3, and the minimum intensity ratio was 0.001 for Example 1, 0 for Example 2, 0 for Example 3, and 0.002 for Comparative Example 3. From this, it was confirmed that the intensity ratio range was 0.052 for Example 1, 0.054 for Example 2, and 0.057 for Example 3, while the range was 0.332 for Comparative Example 3, and that the Comparative Example contained iron (M1 element) in various aggregated states compared to the Examples.

[0256] 3.0 g of each of the obtained powders was filled into a mold having a diameter of 25 mm, and subjected to uniaxial pressing at a pressure of 49 MPa, followed by CIP treatment at a pressure of 196 MPa to obtain disk-shaped compacts (green compacts). These compacts were calcined under the following conditions to obtain calcined compacts for each of the Examples and Comparative Examples.

[0257] Calcining temperature: 1000℃ Pre-baking time: 1 hour Heating rate: 50°C / hour Calcination atmosphere: air Cooling rate: 300℃ / hour The calcined bodies of Examples 1 and 4 and Comparative Example 1 were designated C1 calcined bodies, the calcined bodies of Examples 2 and 5 and Comparative Example 2 were designated C3 calcined bodies, and the calcined bodies of Examples 3 and 6 and Comparative Example 3 were designated C4 calcined bodies. The results are shown in the table below. Note that the compositions in the table below indicate the contents (in terms of oxides) of elements other than zirconia.

[0258] [Table 9]

[0259] Compared to the comparative example, the compacts of the examples had similar densities, but had high Vickers hardness of 11.5 HV or more, and it was confirmed that they were compacts that were less prone to defects.

[0260] Measurement example 1 The Vickers hardness of the calcined bodies of the Examples and Comparative Examples was measured. The results are shown in the table below. The Vickers hardness was measured for 10 calcined bodies obtained by repeating the procedures of each Example and Comparative Example. In addition, a calcined body was prepared in the same manner as in the Examples except that Powder 10 was used, and the difference in Vickers hardness (46.3 HV) between the calcined body obtained and the calcined body (hereinafter also referred to as the "reference calcined body") was shown as the hardness difference.

[0261] [Table 10]

[0262] It can be seen that the calcined bodies of the Examples and Comparative Examples have a tendency that the darker the color tone of the calcined body, from C1 to C4, the higher the Vickers hardness and the larger the standard deviation. Furthermore, it can be seen that the calcined bodies of the Examples have a lower Vickers hardness and a smaller standard deviation than the calcined bodies of the Comparative Examples in all color tones, and that the variation in hardness between production lots is suppressed.

[0263] Furthermore, among the calcined bodies C1 to C4, the Vickers hardness of the calcined bodies of Examples was 47.3HV to 50.8HV, with a hardness difference of 5HV or less, while the Vickers hardness of the calcined bodies of Comparative Examples was 53.4HV to 65.8HV, with a hardness difference of more than 10HV.

[0264] Furthermore, the difference in hardness between the calcined body obtained from the commercially available zirconia powder and the Examples was 1.0HV to 4.5HV, or 5HV or less, whereas the Comparative Examples had a large difference in hardness of 7.1HV to 19.5HV, or 7HV or more, and it can be confirmed that the difference increases as the color tone becomes darker.

[0265] <Preparation of sintered body> The calcined bodies of the examples and comparative examples, as well as the reference calcined body, were sintered under the following conditions to obtain sintered bodies.

[0266] Sintering method: Atmospheric pressure sintering Sintering temperature: 1500℃ Sintering time: 2 hours Heating rate: 600°C / hour Sintering atmosphere: Air Of the obtained sintered bodies, the sintered bodies of Examples 1 and 4 and Comparative Example 1 were designated as C1 sintered bodies, the sintered bodies of Examples 2 and 5 and Comparative Example 2 were designated as C3 sintered bodies, and the sintered bodies of Examples 3 and 6 and Sintering Example 3 were designated as C4 sintered bodies. In addition, the sintered body obtained from the reference calcined body was designated as the reference sintered body. The results are shown in the table below. In the table below, the transmittance ratio indicates the total light transmittance of each sintered body relative to the total light transmittance of the reference sintered body (42%).

[0267] [Table 11]

[0268] The sintered bodies of the Examples and Comparative Examples had similar transmittance ratios and color tones. This confirmed that the calcined bodies of the Examples could produce sintered bodies having color tones and total light transmittances equivalent to those of conventional sintered bodies.

[0269] Examples 7 to 12 Each powder was filled into a 200 mL polypropylene container in the mass ratio shown in the table below, and the container was stirred to dry mix the powder, thereby obtaining a powder composition for each of the Examples and Comparative Examples.

[0270] The obtained powder composition was molded and calcined in the same manner as in Example 1 to obtain calcined bodies of Examples 7 to 12. The results for the powder composition are shown in Table 12, and the results for the molded body and calcined body are shown in Table 13. The compositions in Table 13 indicate the contents of components other than zirconia.

[0271] [Table 12]

[0272] The high strength ratio was 0.01% (0.005%) for Example 7, 0.01% (0.011%) for Example 8, 0.01% (0.014) for Example 9, 0.03% for Example 10, and 0.06% for Example 11. This confirmed that the high strength ratio tends to increase with increasing Fe2O3 content. Furthermore, the coarse strength ratio was 0% for all Examples 7 to 11.

[0273] The maximum intensity ratio was 0.012 for Example 7, 0.015 for Example 8, and 0.015 for Example 9, and was 0.057 for Example 10 and 0.128 for Example 11. The minimum intensity ratio was 0 for all of Examples 7 to 11, and the intensity ratio range was 0.012 for Example 7, 0.015 for Example 8, and 0.015 for Example 9. As the amount of stabilizing element increased, the high intensity proportion tended to increase and the intensity ratio range tended to widen.

[0274] [Table 13]

[0275] Measurement example 2 The Vickers hardness of the calcined body was measured, and sintered bodies were produced and evaluated in the same manner as in Measurement Example 1. Table 14 shows the measurement results of Vickers hardness, and Table 15 shows the evaluation results of the sintered bodies.

[0276] [Table 14]

[0277] The calcined bodies of Examples 7 to 12 all exhibited Vickers hardnesses comparable to those of Examples 1 to 6, and the effect of the content of the stabilizing element (yttrium) on Vickers hardness could not be confirmed.

[0278] [Table 15]

[0279] It was confirmed that an increase in the content of the stabilizing element (yttrium) reduced the three-point bending strength and increased the transmittance.

[0280] Examples 13 and 14 Each powder was filled into a 200 mL polypropylene container in the mass ratio shown in the table below, and the container was stirred to dry mix the powder, thereby obtaining a powder composition for each of the Examples and Comparative Examples.

[0281] The obtained powder composition was molded and calcined in the same manner as in Example 1 to obtain calcined bodies of Examples 13 and 14. The results for the powder composition are shown in Table 16, and the results for the molded body and calcined body are shown in Table 17. The compositions in Table 17 indicate the contents of components other than zirconia.

[0282] [Table 16]

[0283] [Table 17]

[0284] Although Powders 5 and 6 have different iron contents, it was confirmed that by changing the mixing ratio, powder compositions and compacts having similar physical properties could be obtained.

[0285] Measurement example 3 The Vickers hardness of the calcined body was measured, and the sintered body was produced and evaluated in the same manner as in Measurement Example 1. Table 18 shows the measurement results of Vickers hardness, and Table 19 shows the evaluation results of the sintered body.

[0286] [Table 18]

[0287] [Table 19]

[0288] From Examples 13 and 14, it was found that the calcined bodies made from powder compositions with different mixing ratios had similar properties. It was confirmed that a calcined body and a sintered body were obtained.

[0289] Examples 15 to 17 Each powder was filled into a 200 mL polypropylene container in the mass ratio shown in the table below, and the container was stirred to dry mix the powder, thereby obtaining a powder composition for each of the Examples and Comparative Examples.

[0290] The obtained powder composition was molded and calcined in the same manner as in Example 1 to obtain calcined bodies of Examples 15 and 17. The results for the powder composition are shown in Table 20, and the results for the molded body and calcined body are shown in Table 21. The compositions in Table 21 indicate the contents of components other than zirconia.

[0291] [Table 20]

[0292] Powder 8 has a higher BET specific surface area than the other powders, and it was confirmed that increasing its mixing ratio increases the BET specific surface area of the resulting powder composition.

[0293] [Table 21]

[0294] Measurement example 4 The Vickers hardness of the calcined body was measured, and sintered bodies were produced and evaluated in the same manner as in Measurement Example 1. Table 22 shows the measurement results of Vickers hardness, and Table 23 shows the evaluation results of the sintered bodies.

[0295] [Table 22]

[0296] It can be confirmed that the calcined bodies obtained in Examples 15 to 17 have higher Vickers hardnesses and smaller standard deviations than those obtained in Examples 10 to 12.

[0297] [Table 23]

[0298] Comparing Examples 10 to 12 with Examples 15 to 17, it was confirmed that sintered bodies having similar color tones could be obtained regardless of the BET specific surface area of the powder composition.

[0299] Example 18 Each powder was filled into a 200 mL polypropylene container in the mass ratio shown in the table below, and the container was stirred to dry mix the powder, thereby obtaining a powder composition for each of the Examples and Comparative Examples.

[0300] The obtained powder composition was molded and calcined in the same manner as in Example 1 to obtain a calcined body of Example 18. The results for the powder composition are shown in Table 24, and the results for the molded body and calcined body are shown in Table 25. The composition in Table 25 indicates the content (in terms of oxide) of elements other than zirconia.

[0301] [Table 24]

[0302] In Example 18, the high strength ratio was 0.07%, the coarse strength ratio was 0%, the maximum strength ratio was 0.148, and the minimum strength ratio was 0.003, and the strength ratio range was 0.145.

[0303] [Table 25]

[0304] Measurement example 5 The Vickers hardness of the calcined body was measured, and the sintered body was produced and evaluated in the same manner as in Measurement Example 1. The measurement results of Vickers hardness are shown in Table 26, and the evaluation results of the sintered body are shown in Table 27.

[0305] [Table 26]

[0306] [Table 27]

[0307] In Examples 12 and 18, in which the alumina content was 0.05% by mass or less, the calcined bodies had similar Vickers hardness regardless of the alumina content. In addition, the obtained sintered bodies had similar color tone, three-point bending strength, and transmittance.

[0308] Examples 19 to 24 and Comparative Examples 4 to 6 Each powder was filled into a 200 mL polypropylene container in the mass ratio shown in the table below, and the container was stirred to dry mix the powder, thereby obtaining a powder composition for each of the Examples and Comparative Examples.

[0309] The resulting powder compositions were molded and calcined in the same manner as in Example 1 to obtain calcined bodies for each Example and Comparative Example. The results for the powder compositions are shown in Table 28, and the results for the molded bodies and calcined bodies are shown in Table 29. The compositions in Table 29 indicate the contents (in terms of oxides) of elements other than zirconia.

[0310] [Table 28]

[0311] The high strength ratio was 99.24% for Example 22 and 99.33% for Example 24. The coarse strength ratio was 5.64 for Example 22 and 6.66 for Example 24.

[0312] The maximum intensity ratio was 0.127 for Example 22 and 0.140 for Example 24, and the minimum intensity ratio was 0.036 for Example 22 and 0.032 for Example 24. From this, it was confirmed that the intensity ratio range was 0.091 for Example 22 and 0.108 for Example 24, and that the intensity ratio range tended to be wider compared to when the M1 element was iron.

[0313] [Table 29]

[0314] Compared with the comparative examples, the molded bodies of the examples had a high Vickers hardness of 11.0 HV or more, and it was confirmed that the molded bodies were less prone to defects.

[0315] Measurement example 6 The Vickers hardness of the calcined body was measured, and sintered bodies were produced and evaluated in the same manner as in Measurement Example 1. Table 30 shows the measurement results of Vickers hardness, and Table 31 shows the evaluation results of the sintered bodies.

[0316] [Table 30]

[0317] Among the calcined bodies that yielded sintered bodies exhibiting similar color tones, the calcined bodies of the Examples had lower hardness than the calcined bodies of the Comparative Examples, and the difference in hardness was also small.In addition, it was confirmed that the standard deviation was small, and the variation in hardness between lots was also small.

[0318] [Table 31]

[0319] It was confirmed that sintered bodies exhibiting similar color tones were obtained from the calcined bodies of both the Examples and Comparative Examples.

[0320] Examples 25 to 30 and Comparative Examples 7 to 9 Each powder was filled into a 200 mL polypropylene container in the mass ratio shown in the table below, and the container was stirred to dry mix the powder, thereby obtaining a powder composition for each of the Examples and Comparative Examples.

[0321] The resulting powder compositions were molded and calcined in the same manner as in Example 1 to obtain calcined bodies for each Example and Comparative Example. The results for the powder compositions are shown in Table 32, and the results for the molded bodies and calcined bodies are shown in Table 33. The compositions in Table 33 indicate the contents (in terms of oxides) of elements other than zirconia.

[0322] [Table 32]

[0323] In Example 27, the high strength ratio was 99.42%, the coarse strength ratio was 4.51%, the maximum strength ratio was 0.125, and the minimum strength ratio was 0.033, and the strength ratio range was 0.092.

[0324] [Table 33]

[0325] Compared with the comparative examples, the molded bodies of the examples all had a high Vickers hardness of 11.0 HV or more, and it was confirmed that the molded bodies were less prone to defects.

[0326] Measurement example 7 The Vickers hardness of the calcined body was measured, and the sintered body was produced and evaluated in the same manner as in Measurement Example 1. The measurement results of Vickers hardness are shown in Table 34, and the evaluation results of the sintered body are shown in Table 35.

[0327] [Table 34]

[0328] Among the calcined bodies that yielded sintered bodies exhibiting similar color tones, the calcined bodies of the Examples had lower hardness than the calcined bodies of the Comparative Examples, and the difference in hardness was also small.In addition, it was confirmed that the standard deviation was small, and the variation in hardness between lots was also small.

[0329] [Table 35]

[0330] It was confirmed that sintered bodies exhibiting similar color tones were obtained from the calcined bodies of both the Examples and Comparative Examples.

Claims

1. one or more first transition metal elements selected from the group consisting of manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), molybdenum (Mo), technetium (Tc), ruthenium (Ru), rhodium (Rh), palladium (Pd), and silver (Ag); a coloring element selected from the group consisting of a lanthanoid rare earth element and one or more transition metal elements selected from the group consisting of manganese, iron, cobalt, nickel, copper, molybdenum, technetium, ruthenium, rhodium, palladium, and silver, and a second transition metal element different in type from the first transition metal element; and zirconia containing a stabilizing element, The content of the first transition metal element is 100 ppm by mass or more, The content of the second transition metal element is less than 100 ppm by mass, and A calcined body having an absolute difference in hardness of 10 HV or less compared to the hardness of a calcined body obtained from a commercially available powder (product name: Zpex4, manufactured by Tosoh Corporation) under the following molding and calcination conditions. (Molding conditions) Molding method: Uniaxial pressing and CIP treatment Uniaxial pressure: 49±3 MPa CIP pressure: 196±5MPa (Pre-firing conditions) Pre-firing method: Normal pressure firing Atmosphere: Air Firing temperature: 1000°C Baking time: 1 hour Temperature rise rate: 50±5°C / hour Cooling rate: 300±10℃ / hour

2. The measured density is 2.8 g / cm ３ The calcined body according to claim 1, wherein the calcined body is as described above.

3. 3. The calcined body according to claim 1, having a Vickers hardness of 25 HV or more and 150 HV or less.

4. 3. The calcined body according to claim 1, wherein the lanthanoid rare earth element is a lanthanoid rare earth element solid-solved in zirconia.

5. 3. The calcined body according to claim 1, wherein the content of the lanthanoid rare earth element is 1.0 mass % or less.

6. The calcined body according to claim 1 or 2, wherein the content of the third transition metal element is more than 0 mass % and not more than 1.0 mass %.

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

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