Powder composition

Abstract

To provide at least one of the following: a powder composition and its production method capable of obtaining a temporarily sintered body having similar processing characteristics without requiring the application of different molding and sintering conditions for each composition; a temporarily sintered body obtained from the powder composition and its production method; and uses thereof.SOLUTION: A powder composition, comprising zirconia that contains (i) two or more of solid solutions between zirconia and lanthanide rare earth elements and (ii) transition metal elements other than zirconium and hafnium, the balance being zirconia stabilized with only one or more of the following: yttrium, calcium and magnesium, wherein the solid solutions between zirconia and lanthanide rare earth elements are different in the kind of lanthanoid rare earth elements contained therein, and wherein the content of transitional metal elements is 1500 ppm or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This disclosure primarily relates to powder compositions comprising zirconia and their applications. [Background technology]

[0002] Due to its high aesthetic appeal based on its mechanical properties and translucency, zirconia is used in dental prostheses such as crowns and bridges. Dental prostheses are manufactured by calcining a molded zirconia body (compacted zirconia) to create a calcined body (also called a semi-sintered body, pre-sintered body, or blank), which is then ground using a CAD / CAM system. Therefore, the calcined body is required to have mechanical properties suitable for machining. For example, Patent Document 1 discloses that a Vickers hardness of 25 to 150 is suitable for machining.

[0003] Furthermore, as shown by dental color charts (e.g., the Vita Classical Shade Guide), the shade of natural teeth varies from patient to patient and from tooth to tooth. To impart a shade to dental restorations that is similar to the shade of natural teeth, pre-colored calcined bodies are used. Colored calcined bodies are usually produced by calcining a molded body of a composition in which pigment and zirconia are uniformly mixed (the so-called powder mixing method; for example, Patent Documents 1 and 2). In the powder mixing method, the composition is adjusted to achieve the desired shade by changing the type and amount of pigment, and then a powder composition in which the pigment and zirconia powder are uniformly mixed is obtained. This is then molded and calcined to obtain a uniformly colored calcined body. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International release 2014 / 022643 [Patent Document 2] U.S. Patent No. 9962247 [Patent Document 3] International release 2016 / 019114 [Overview of the project] [Problems that the invention aims to solve]

[0005] Incidentally, calcined bodies differ not only in color but also in processing characteristics depending on their composition. On the other hand, machining of calcined bodies is performed under the same conditions regardless of their composition. Therefore, in the powder mixing method, variations in processing characteristics due to compositional differences were suppressed by applying different manufacturing conditions (molding conditions and calcination conditions) for each composition. Due to the need to change manufacturing conditions in this way, the productivity of calcined bodies varied greatly depending on the composition.

[0006] This disclosure aims to provide at least one of the following: a powder composition and a method for producing the same, which can produce calcined bodies having similar processing characteristics without requiring the application of different molding and calcination conditions for each composition; a calcined body obtained from the powder composition and a method for producing it; and applications thereof. Preferably, another objective is to provide at least one of the following: a method for producing a calcined body that can reduce variations in productivity; a calcined body obtained thereby; and applications thereof. [Means for solving the problem]

[0007] The present invention is as claimed, and the gist of this disclosure is as follows: [1] A powder composition comprising two or more zirconias in which lanthanide rare earth elements are solid-solved, and a transition metal element other than zirconium and hafnium, the remainder being stabilized with only one or more selected from the group of yttrium, calcium and magnesium, wherein each of the zirconias in which lanthanide rare earth elements are solid-solved contains a different lanthanide rare earth element, and the content of the transition metal element is 1500 ppm or less. [2] The powder composition according to [1], wherein at least one of the zirconia in which the lanthanide rare earth elements are solid-dissolved is zirconia in which one or more elements selected from the group consisting of praseodymium, samarium, terbium, dysprodium, holonium, and thulium are solid-dissolved. [3] The powder composition according to [1] or [2] above, wherein at least one of the zirconia in which the lanthanide rare earth element is solid-dissolved is zirconia in which one or more selected from the group consisting of neodymium and erbium are solid-dissolved. [4] The powder composition according to any one of [1] to [3] above, wherein at least one of the zirconia in which the lanthanide rare earth element is solid-solved is zirconia stabilized with one or more selected from the group consisting of yttrium, calcium and magnesium. [5] The powder composition according to any one of [1] to [4] above, wherein the transition metal element is one or more selected from the group consisting of manganese, cobalt, and titanium. [6] The powder composition according to any one of [1] to [5] above, wherein the transition metal element is included as one or more selected from the group consisting of oxides, hydroxides, oxyhydroxides, chlorides, sulfates, and nitrates. [7] The powder composition according to any one of [1] to [6] above, wherein the remainder is zirconia stabilized solely with yttrium. [8] A powder composition according to any one of [1] to [7] above, wherein the iron content is 100 ppm or less. [9] A powder composition containing alumina, according to any one of [1] to [8] above.

[10] The powder composition according to any one of [1] to [9] above, comprising granular particles composed of a transition metal element other than zirconium and hafnium, and zirconia stabilized with only one or more elements selected from the group consisting of yttrium, calcium, and magnesium.

[11] BET specific surface area is 5m 2 / g or more 15m 2 A powder composition according to any one of the above [1] to

[10] , wherein the amount is less than or equal to / g.

[12] A method for producing a calcined body, characterized by using any one of the powder compositions described in [1] to

[11] above.

[13] A method for producing a sintered body, characterized by using the powder composition described in any one of [1] to

[12] above.

[14] A calcined body composed of fused particles of transition metal compounds other than zirconium and hafnium, zirconia in which two or more lanthanide rare earth elements are solid-solved, and zirconia stabilized with only one or more selected from the group of yttrium, calcium and magnesium, wherein the content of transition metal elements other than zirconium and hafnium is 1500 ppm or less.

[15] A method for manufacturing a sintered body, characterized by using the calcined body described in

[14] above. [Effects of the Invention]

[0008] This disclosure provides at least one of the following: a powder composition and a method for producing the same, which can produce calcined bodies having similar processing characteristics without requiring the application of different molding and calcination conditions for each composition; a calcined body obtained from the powder composition and a method for producing it; and applications thereof. Furthermore, preferably, it is also possible to provide at least one of the following: a method for producing a calcined body that can reduce variations in productivity; a calcined body obtained thereby; and applications thereof. [Modes for carrying out the invention]

[0009] The powder composition of this disclosure will be described below with reference to an example of its embodiment.

[0010] This embodiment is a powder composition comprising two or more types of zirconia in which lanthanide rare earth elements are solid-solved, and a transition metal element other than zirconium and hafnium, with the remainder being stabilized by only one or more elements selected from the group of yttrium, calcium and magnesium, wherein each of the zirconia in which the lanthanide rare earth elements are solid-solved contains a different lanthanide rare earth element, and the content of the transition metal element is 1500 ppm or less.

[0011] The powder composition of this embodiment contains two or more types of zirconia in which lanthanide rare earth elements are solid-dissolved (hereinafter also referred to as "lanthanide solid-dissolved zirconia" or "Ln solid-dissolved ZrO2," and zirconia in which erbium is solid-dissolved, etc., are also referred to as "erbium solid-dissolved zirconia" or "Er solid-dissolved ZrO2," etc.). The lanthanide rare earth elements are solid-dissolved in the zirconia and exist within the zirconia crystal. Therefore, the crystal of Ln solid-dissolved ZrO2 itself exhibits a color derived from the lanthanide rare earth elements. Furthermore, in the powder composition of this embodiment, the lanthanide rare earth elements are solid-dissolved in the zirconia in the powder state (i.e., in a state where no heat treatment such as calcination that causes thermal shrinkage after zirconia molding has been performed). Therefore, unlike powder compositions (mixed powders) that are mixtures of lanthanide rare earth compound powders and zirconia powders, the powder composition of this embodiment does not contain aggregated particles of lanthanide rare earth compounds with a particle size of 0.5 μm or larger. Furthermore, unlike molded bodies or calcined bodies obtained by immersion in a colored liquid containing lanthanide rare earth elements, the powder composition of this embodiment exhibits very little non-uniform distribution and segregation of lanthanide rare earth elements that would cause abnormal growth of zirconia crystal particles during sintering. As a result, aggregated particles are less likely to form, and a calcined body with uniform hardness can be obtained regardless of the lanthanide rare earth element content.

[0012] The powder composition of this embodiment contains two or more Ln-solid-solution ZrO2 compounds, and each Ln-solid-solution ZrO2 compound contains a different lanthanide rare earth element in solid solution. By including two or more Ln-solid-solution ZrO2 compounds containing different lanthanide rare earth elements in solid solution, the composition of the powder composition of this embodiment can be made such that a sintered body exhibiting a desired color tone suitable for dental prostheses and a calcined precursor body can be obtained.

[0013] The powder composition of this embodiment may contain two or more types of Ln-Soluble ZrO2, and may contain three or more types or four or more types. The powder composition of this embodiment may contain any types of Ln-Soluble ZrO2 necessary for reproducing the color tone of natural teeth, and may contain five or fewer types as an example. For example, the powder composition of this embodiment may contain two types of zirconia in which different lanthanide rare earth elements are dissolved; in other words, it may contain two types of zirconia in which lanthanide rare earth elements are dissolved, and the zirconia in which different lanthanide rare earth elements are dissolved.

[0014] Ln solid-solution ZrO2 is zirconia in which one element selected from the group of praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holonium (Ho), erbium (Er), thulium (Tm), and ytterbium (Yb) is solid-solution, and furthermore, praseodymium, neodymium, samarium, terbium, Preferably, the zirconia is in which one selected from the group consisting of dysprosodium, holonium, erbium, and thulium is dissolved in solid solution; further preferably, the zirconia is in which one selected from the group consisting of praseodymium, neodymium, terbium, and erbium is dissolved in solid solution; further preferably, the zirconia is in which one selected from the group consisting of praseodymium, terbium, and erbium is dissolved in solid solution; and further preferably, the zirconia is in which at least one of terbium and erbium is dissolved in solid solution. As a result, the powder composition of this embodiment contains two or more elements selected from the group consisting of praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprodium, holonium, erbium, thulium, and ytterbium, further comprising two or more elements selected from the group consisting of praseodymium, neodymium, samarium, terbium, dysprodium, holonium, erbium, and thulium, further comprising two or more elements selected from the group consisting of praseodymium, neodymium, terbium, and erbium, further comprising two or more elements selected from the group consisting of praseodymium, terbium, and erbium, and further comprising terbium and erbium. Note that each Ln-solid-solution ZrO2 may contain two or more lanthanide rare earth elements in solid solution.

[0015] The lanthanide rare earth element content of each Ln solid solution ZrO2 is arbitrary and should be equivalent to the lanthanide rare earth element content of each lanthanide solid solution powder described later.

[0016] The powder composition of this embodiment preferably contains zirconia in which one or more selected from the group of praseodymium, samarium, terbium, dysprodium, holonium, and thulium are solid-dissolved, further containing zirconia in which at least one of praseodymium and terbium is solid-dissolved, and further containing zirconia in which terbium is solid-dissolved (hereinafter also referred to as "yellow lanthanide solid-dissolved zirconia" or "yellow Ln solid-dissolved ZrO2"). By including yellow Ln solid-dissolved ZrO2 as Ln solid-dissolved ZrO2, that is, by including yellow Ln solid-dissolved ZrO2 as Ln solid-dissolved ZrO2, it becomes easier to finely adjust the yellowish tooth color in particular.

[0017] The powder composition of this embodiment preferably contains zirconia in which one or more elements selected from the group consisting of neodymium and erbium are solid-dissolved, and more preferably contains zirconia in which erbium is solid-dissolved (hereinafter also referred to as "red lanthanide solid-dissolved zirconia" or "red Ln solid-dissolved ZrO2"). By including red Ln solid-dissolved ZrO2 as Ln solid-dissolved ZrO2, that is, by including red Ln solid-dissolved ZrO2, it becomes easier to finely adjust the shade of teeth, especially reddish ones.

[0018] The powder composition of this embodiment preferably contains yellow Ln-solid-solution ZrO2 and red Ln-solid-solution ZrO2, and more preferably the Ln-solid-solution ZrO2 contained in the powder composition of this embodiment is yellow Ln-solid-solution ZrO2 and red Ln-solid-solution ZrO2.

[0019] The powder composition of this embodiment may contain Ln-Soluble ZrO2 stabilized with one or more elements selected from the group consisting of yttrium (Y), calcium (Ca), and magnesium (Mg) (hereinafter also referred to as "stabilizing elements"), preferably yttrium, and it is preferable that at least one of the Ln-Soluble ZrO2 is zirconia stabilized with a stabilizing element (hereinafter also referred to as "stabilized Ln-Soluble ZrO2"). Since lanthanide rare earth elements have the function of stabilizing zirconia, as the amount increases, the stabilizing function and the color development also become stronger. Because the Ln-Soluble ZrO2 is zirconia stabilized with a stabilizing element and a lanthanide rare earth element, the stabilizing effect can be adjusted without changing the color development of the Ln-Soluble ZrO2 by adjusting the content of the stabilizing element. Note that the Ln-Soluble ZrO2 may be zirconia stabilized only with a lanthanide rare earth element. For convenience, the stabilizing element in this embodiment does not include a lanthanide rare earth element.

[0020] The amount of stabilizing elements in stabilized Ln solid-solution ZrO2 should be such that the zirconia is partially stabilized. For example, the yttrium content in yttrium-stabilized Ln solid-solution ZrO2 (Y-stabilized Ln solid-solution ZrO2) can be 1.5 mol% or more, 2 mol% or more, 3 mol% or more, 3.3 mol% or more, 3.5 mol% or more, or 3.6 mol% or more, and also 6.5 mol% or less, 6 mol% or less, 5.5 mol% or less, 5.2 mol% or less, or 4.5 mol% or less. The amount of stabilizing elements in stabilized Ln solid-solution ZrO2 can be determined as the ratio [mol%] of the stabilizing elements in oxide equivalent to the total [mol] of zirconia (ZrO2), lanthanide rare earth elements in oxide equivalent, and stabilizing elements in oxide equivalent in the Ln solid-solution ZrO2. Note that each stabilizing element can be converted to its oxide equivalent, with yttrium being Y2O3, calcium being CaO, and magnesium being MgO.

[0021] The powder composition of this embodiment preferably contains at least yellow stabilized Ln solid-solution ZrO2 and red stabilized Ln solid-solution ZrO2. Furthermore, it is preferable that the stabilized Ln-solubilated ZrO2 contained in the powder composition of this embodiment is a zirconia in which at least one of praseodymium and terbium is dissolved, and a zirconia in which at least one of neodymium and erbium is dissolved; furthermore, a Tb-solubilated ZrO2 and an Er-solubilated ZrO2; even further, a zirconia in which at least one of praseodymium and terbium is dissolved, and which is stabilized with a stabilizing element, as well as at least one of praseodymium and terbium, and a zirconia in which at least one of neodymium and erbium is dissolved; and even further, a zirconia in which terbium is dissolved, and which is stabilized with yttrium and terbium, and a zirconia in which only erbium is dissolved (i.e., a Y-stabilized Tb-solubilated ZrO2 and an Er-solubilated ZrO2).

[0022] Ln-soluble ZrO2 is preferably in powder form, and it is preferable that the powder composition of this embodiment contains stabilized Ln-soluble ZrO2 as a powder.

[0023] The powder composition of this embodiment contains transition metal elements other than zirconium and hafnium (hereinafter also referred to as "coloring metal elements"). For convenience, in this embodiment, the transition metal elements do not include lanthanide rare earth elements. This makes it easier to finely adjust the shade to which lanthanide rare earth elements do not easily produce color. The coloring metal elements are preferably elements that make it easier to obtain grayish tooth shades, and further preferably are transition metal elements other than iron (Fe), and further preferably one or more selected from the group consisting of manganese (Mn), cobalt (Co), and titanium (Ti), and further preferably two or more selected from the group consisting of manganese, cobalt, and titanium, and further preferably at least one of manganese and cobalt and titanium, and further preferably cobalt and titanium, and at least titanium is included.

[0024] The form of the colored metal element contained in the powder composition of this embodiment is arbitrary, and any compound containing a colored metal element is acceptable. Examples include the colored metal element being included as one or more selected from the group of oxides, hydroxides, oxyhydroxides, chlorides, sulfates, and nitrates, or as one or more selected from the group of oxides, hydroxides, and oxyhydroxides, or as oxides. Manganese may be included as one or more selected from the group of MnO, MnO2, Mn3O4, Mn(OH)2, MnOOH, MnCl2, MnSO4, Mn(NO3)2, and Mn(COOH)2, or as one or more selected from the group of MnO, MnO2, Mn3O4, Mn(OH)2, and MnOOH, or as one or more selected from the group of MnO, MnO2, and Mn3O4. Cobalt may be included as one or more selected from the group CoO, CoO2, Co3O4, Co(OH)2, CoOOH, CoCl2, CoSO4, Co(NO3)2, and CoCOOH, or more as one or more selected from the group CoO2, Co3O4, Co(OH)2, and CoOOH, or more as at least one of CoO2 and Co3O4, or more as Co3O4. Titanium may be included as one or more selected from the group TiO2, Ti(OH)2, TiOOH, TiCl2, TiSO4, Ti(NO3)2, and TiCOOH, or more as one or more selected from the group TiO2, Ti(OH)2, and TiOOH, or more as TiO2. The powder composition of this embodiment may contain two or more of the above-mentioned colored metal element compounds.

[0025] The powder composition of this embodiment is zirconia stabilized with only one or more elements selected from the group consisting of yttrium, calcium, and magnesium (hereinafter also referred to as "stabilized zirconia" or "stabilized ZrO2," and zirconia stabilized with only yttrium is also referred to as "yttrium-stabilized zirconia" or "Y-stabilized ZrO2," etc.). Stabilized zirconia is particularly zirconia that contains stabilizing elements and does not contain solid solutions of elements that cause zirconia to exhibit color, such as lanthanide rare earth elements. It is more preferable that the stabilized ZrO2 is zirconia stabilized with only yttrium.

[0026] In the powder composition of this embodiment, "residue" refers to the main component (matrix, parent phase) of the powder composition. Therefore, the powder composition of this embodiment may be considered as a powder composition mainly composed of zirconia stabilized with only one or more elements selected from the group consisting of yttrium, calcium, and magnesium, and containing two or more types of zirconia in which lanthanide rare earth elements are solid-solved, as well as transition metal elements other than zirconium and hafnium.

[0027] The amount of stabilizing elements contained in stabilized zirconia should be such that the crystalline phase of the zirconia is partially stabilized. When the stabilizing element is yttrium, the molar ratio of yttrium converted to Y2O3 (i.e., {Y2O3[mol] / (ZrO2+Y2O3)[mol]}×100) to the total of zirconia (ZrO2) and yttrium converted to Y2O3 in the yttrium-stabilized zirconia should be 2.7 mol% or more, 3 mol% or more, 3.3 mol% or more, 3.5 mol% or more, or 3.6 mol% or more, and also 6.5 mol% or less, 6 mol% or less, 5.5 mol% or less, 5.2 mol% or less, or 4.5 mol% or less.

[0028] The powder composition of this embodiment contains a colored metal element content of 1500 ppm or less (0.15 mass% or less), preferably 1200 ppm or less, 1000 ppm or less, 800 ppm or less, 750 ppm or less, or 700 ppm or less. Since the powder composition of this embodiment contains a colored metal element, the content of the colored metal element is greater than 0 ppm, and preferably 5 ppm or more, 10 ppm or more, or 40 ppm or more. If the colored metal element exceeds this range, when the powder composition of this embodiment is calcined, the colored metal element will not be uniformly dissolved or dispersed in the zirconia, resulting in a concentration gradient of the colored metal element in the calcined body, particle precipitation, etc., and the calcined body will become non-uniform. Non-uniform calcined bodies are prone to defects during processing such as chipping and breakage, and the processing characteristics will vary greatly depending on the composition. In other words, the amount of colored metal elements should be such that, when the powder composition of this embodiment is calcined, it is uniformly dissolved or dispersed in zirconia, and the resulting color is suitable for use as a dental prosthetic material.

[0029] Among transition metal elements, iron (Fe) tends to form segregated or aggregated particles, and the resulting calcined body tends to have a high hardness. Therefore, it is preferable that the powder composition of this embodiment does not contain iron (i.e., the iron content is 0 ppm), but it may contain iron if it does not affect the processing characteristics. Examples of iron content include 0 ppm or more, greater than 0 ppm, or 1 ppm or more, and also 500 ppm or less, 100 ppm or less, 50 ppm or less, 10 ppm or less, or 5 ppm or less. In this embodiment, the iron content is the mass ratio of iron in terms of Fe2O3 to the mass of the powder composition in terms of oxide.

[0030] The powder composition of this embodiment may contain alumina. The alumina content of the powder composition of this embodiment may be 0% by mass or more, greater than 0% by mass, 0.005% by mass or more, 0.01% by mass or more, or 0.03% by mass or more, and may also be 0.2% by mass or less, 0.1% by mass or less, or 0.06% by mass or less. Furthermore, the powder composition of this embodiment may not contain alumina (i.e., the alumina content may be 0% by mass). In this embodiment, the alumina content is the mass ratio (mass%) of alumina (Al2O3) to the mass of the powder composition when converted to oxide.

[0031] The powder composition of this embodiment may contain two or more Ln-soluble ZrO2, a colored metal element, and alumina as an option, with the remainder being stabilized ZrO2 (i.e., it may be a powder composition containing two or more Ln-soluble ZrO2, a colored metal element, and alumina as an option, with stabilized ZrO2 as the main component). However, since it is an unavoidable impurity, it may also contain hafnia (HfO2). The hafnia content varies greatly depending on the starting materials and manufacturing method used in the production of zirconia, but for example, it can be exemplified as 2.0% by mass or less.

[0032] In this embodiment, when calculating values ​​that use the amount of zirconia (ZrO2), such as composition and density, hafnia can be treated as zirconia for calculation purposes.

[0033] As long as the content of the colored metal element is within the range described above, the Ln-soluble ZrO2, colored metal element, and stabilized ZrO2 contained in the powder composition of this embodiment may be adjusted in type and content according to the desired color tone of the dental prosthesis.

[0034] For example, the Ln-solid-solution ZrO2 in this embodiment is included such that the lanthanide rare earth element content of the powder composition is 0.01 mol% or more, 0.02 mol% or more, or 0.03 mol% or more, and also 0.7 mol% or less, 0.6 mol% or less, or 0.5 mol% or less.

[0035] The content of lanthanide rare earth elements in the powder composition of this embodiment is the ratio of lanthanide rare earth elements (in oxide equivalent) [mol] to the total [mol] of zirconia (ZrO2), lanthanide rare earth elements (in oxide equivalent), and stabilizing elements (in oxide equivalent).

[0036] Furthermore, the oxide equivalents of each lanthanide rare earth element are calculated using praseodymium as Pr6O 11 Neodymium can be represented as Nd2O3, promethium as Pm2O3, samarium as Sm2O3, europium as Eu2O3, gadolinium as Gd2O3, terbium as Tb4O7, dysprosium as Dy2O3, holmium as Ho2O3, erbium as Er2O3, thulium as Tm2O3, and ytterbium as Yb2O3.

[0037] The powder composition of this embodiment preferably contains lanthanide solid-solution zirconia such that the ratio [mol / mol] of the total amount of neodymium and erbium to the total amount [mol] of praseodymium, samarium, terbium, dysprodium, holonium, and thulium (hereinafter also referred to as the "lanthanide ratio") is 3 or more, 60 or less, and more preferably 5 or more, 48 or less. The visible color of the sintered body changes depending on its translucency. For example, to achieve a yellowish tooth color (e.g., a color corresponding to B1-B4 in the Vita Classical Shade Guide; the same applies hereinafter), the lanthanide ratio should be between 10 and 30. To achieve a reddish tooth color (e.g., a color corresponding to A1-A4 in the Vita Classical Shade Guide; the same applies hereinafter), the lanthanide ratio should be between 15 and 55, or even between 20 and 48. To achieve a grayish tooth color (e.g., a color corresponding to C1-C4 in the Vita Classical Shade Guide; the same applies hereinafter), the lanthanide ratio should be between 3 and 35, or even between 5 and 30. To achieve a dark brown tooth color (e.g., a color corresponding to D2-D4 in the Vita Classical Shade Guide; the same applies hereinafter), the lanthanide ratio should be between 1 and 30.

[0038] The powder composition of this embodiment exhibits different color tones depending on the lanthanide rare earth elements it contains. Therefore, even if the lanthanide ratio is the same, the resulting sintered body will exhibit different color tones depending on the combination of lanthanide rare earth elements.

[0039] The content of stabilizing elements in the powder composition of this embodiment may be any amount depending on the content ratio of lanthanide solid-solution zirconia and stabilized zirconia. For example, the yttrium content of the powder composition of this embodiment may be 2.7 mol% or more, 3 mol% or more, 3.3 mol% or more, 3.5 mol% or more, or 3.6 mol% or more, and may also be 6.5 mol% or less, 6 mol% or less, 5.5 mol% or less, 5.2 mol% or less, or 4.5 mol% or less.

[0040] The content of Ln-soluble ZrO2 in the powder composition of this embodiment varies depending on the amount of lanthanide rare earth elements dissolved in each Ln-soluble ZrO2, and should be any amount that results in the above-mentioned content of lanthanide rare earth elements. Examples of the Ln-soluble ZrO2 content in the powder composition of this embodiment include 5% by mass or more and 50% by mass or less. Furthermore, for a yellowish tooth color, it may be 5% by mass or more, 50% by mass or less or 30% by mass or less; for a reddish tooth color, it may be 5% by mass or more and 46% by mass or less; for a grayish tooth color, it may be 5% by mass or more, 95% by mass or less or 50% by mass or less; and for a dark brown tooth color, it may be 15% by mass or more and 30% by mass or less. The content [mass%] of each Ln-soluble ZrO2 in the powder composition of this embodiment is determined from the mass ratio of each Ln-soluble ZrO2 [g] to the powder composition [g].

[0041] Thus, the proportion of Ln-soluble ZrO2 contained in the powder composition of this embodiment can be any proportion corresponding to the desired color tone. For example, increasing the proportion of Tb-soluble ZrO2 can strengthen the yellowish color tone, and increasing the proportion of Er-soluble ZrO2 can strengthen the reddish color tone.

[0042] For example, the content of coloring metal elements in reddish tooth shades may be 50 ppm or more or 70 ppm or more, and 750 ppm or less, 500 ppm or less, or 200 ppm or less; the content of coloring metal elements in yellowish tooth shades may be 50 ppm or more or 70 ppm or more, and 300 ppm or less, or 200 ppm or less; the content of coloring metal elements in grayish tooth shades may be 100 ppm or more or 200 ppm or more, and 1100 ppm or less, 950 ppm or less, 800 ppm or less, 500 ppm or less, or 300 ppm or less; and the content of coloring metal elements in dark brown tooth shades may be 150 ppm or more or 200 ppm or more, and 500 ppm or less, 400 ppm or less, or 250 ppm or less.

[0043] In this embodiment, the content of the colored metal element is the total mass ratio of the colored metal element, converted to oxides, to the mass of the powder composition, converted to oxides. The oxide equivalents for manganese, cobalt, and titanium can be MnO2, Co3O4, and TiO2, respectively.

[0044] When two or more colored metallic elements are included, the ratio of each colored metallic element is arbitrary. For example, when cobalt and titanium are included as colored metallic elements, the ratio of cobalt (Co) to titanium (Ti) [mol / mol] can be between 0.01 and 1.0, or even between 0.1 and 0.3.

[0045] If the powder composition of this embodiment contains Y-stabilized Pr-soluble ZrO2, Tb-soluble ZrO2, Er-soluble ZrO2, cobalt oxide, manganese oxide, titanium oxide, and alumina, with the remainder being Y-stabilized ZrO2 (i.e., a powder composition containing yttrium-stabilized praseodymium-soluble zirconia, terbium-soluble zirconia, erbium-soluble zirconia, cobalt oxide, manganese oxide, titanium oxide, and alumina, with yttrium-stabilized zirconia as the main component), then the composition of the powder composition is (Pr6O 11It may be regarded as (Pr6O + Tb4O7 + Er2O3 + Co3O4 + TiO2 + MnO2 + Al2O3 + Y2O3 + ZrO2). In this composition, Y2O3 is the sum of Y2O3 contained in Y-stabilized Pr-doped ZrO2 and the balance, that is, Y2O3 contained in Y-stabilized ZrO2. Also, ZrO2 in this composition is the sum of ZrO2 contained in Y-stabilized Pr-doped ZrO2, ZrO2 contained in Tb-doped ZrO2, ZrO2 contained in Er-doped ZrO2, and the balance, that is, ZrO2 contained in the main component (Y-stabilized ZrO2) of the powder composition. Further, in the powder composition, the content [mol%] of the lanthanoid rare earth element is obtained from {(Pr6O 11 +Tb4O7+Er2O3)[mol] / (Pr6O 11 +Tb4O7+Er2O3+Y2O3+ZrO2)[mol]}×100, the content [mol%] of the stabilizing element is obtained from {Y2O3[mol] / (Pr6O 11 +Tb4O7+Er2O3+Y2O3+ZrO2)[mol]}×100, the content [ppm] of the coloring metal element is obtained from {(TiO2+Co3O4+MnO2)[g] / (Pr6O 11 +Tb4O7+Er2O3+Co3O4+TiO2+MnO2+Al2O3+Y2O3+ZrO2)[g]}×10 6 and the content [mass%] of alumina is obtained from {Al2O3[g] / (Pr6O 11 +Tb4O7+Er2O3+Co3O4+TiO2+MnO2+Al2O3+Y2O3+ZrO2)[g]}×100. The lanthanoid ratio [mol / mol] is obtained from {(Er2O3)[mol] / (Pr6O 11 +Tb4O7)[mol]}. The same applies when the powder composition contains a binder. Furthermore, the content [mass%] of each Ln-doped ZrO2 in the powder composition is obtained from the mass ratio of each Ln-doped ZrO2 [g] to the powder composition [g].

[0046] The powder composition of this embodiment may contain transition metal elements, lanthanide rare earth elements, and stabilizing elements that are not solid-dissolved in zirconia, as long as their effect is not impaired. However, it is preferable that these elements are not included, and it is even more preferable that the powder X-ray diffraction (hereinafter also referred to as "XRD") pattern does not have XRD peaks corresponding to transition metal compounds, lanthanide rare earth compounds, or stabilizing element compounds.

[0047] The following conditions can be used as XRD measurement conditions in this embodiment. Radiation source: CuKα radiation (λ=0.15418nm) Measurement mode: Continuous scan Scan speed: 4° / min Measurement range: 2θ = 26° ~ 33° Acceleration voltage / current: 40mA / 40kV Divergence vertical limiting slit: 10mm Divergence / Induction Slit: 1° Light-receiving slit: open Detector: Semiconductor detector (D / teX Ultra) Filter: Ni filter Goniometer radius: 185mm

[0048] XRD measurements can be performed using a standard X-ray diffractometer (e.g., Ultima IV, manufactured by RIGAKU).

[0049] The crystalline phase of the powder composition of this embodiment preferably consists of a zirconia crystalline phase, and may consist solely of a zirconia crystalline phase. Furthermore, the crystalline phase of the powder of this embodiment preferably contains at least one of tetragonal zirconia and cubic zirconia, and more preferably contains at least one of tetragonal zirconia and cubic zirconia, along with monoclinic zirconia. The proportion of monoclinic zirconia in the crystalline phase of the powder composition of this embodiment (hereinafter also referred to as "monoclinic ratio") is 0% or more, greater than 0%, 3% or more, or 5% or more, and can also be 40% or less, 35% or less, 25% or less, 15% or less, 10% or less, or 8% or less. In addition, crystalline phases other than monoclinic zirconia in the crystalline phase of the powder composition of this embodiment may be considered as tetragonal zirconia and cubic zirconia.

[0050] The crystalline phase can be confirmed by XRD measurement under the conditions described above. The XRD peaks corresponding to each crystal plane of zirconia are those with peak tops at the following 2θ.

[0051] XRD peak corresponding to the monoclinic zirconia (111) plane: 2θ = 31 ± 0.5° XRD peak corresponding to the monoclinic zirconia (11-1) plane: 2θ = 28 ± 0.5° XRD peak corresponding to the tetragonal zirconia (111) plane: 2θ = 30 ± 0.5° XRD peak corresponding to the cubic zirconia (111) plane: 2θ = 30 ± 0.5° The monoclinic fraction is a value that can be determined from the XRD pattern of the powder composition using the following formula. f M =[1-{[It(111)+Ic(111)] / [Im(111)+Im(11-1) +It(111)+Ic(111)]}]×100

[0052] In the above equation, f Mθ is the monoclinic fraction [%], It(111) is the area intensity of the XRD peak corresponding to the tetragonal zirconia (111) plane, Ic(111) is the area intensity of the XRD peak corresponding to the cubic zirconia (111) plane, Im(111) is the area intensity of the XRD peak corresponding to the monoclinic zirconia (111) plane, and Im(11-1) is the area intensity of the XRD peak corresponding to the monoclinic zirconia (11-1) plane. The XRD peaks corresponding to the tetragonal zirconia (111) plane and the XRD peaks corresponding to the cubic zirconia (111) plane are measured as a single overlapping peak (hereinafter also referred to as the "main XRD peak"). Therefore, It(111)+Ic(111) in the above equation corresponds to the area intensity of a single XRD peak with its peak top at 2θ=30±0.5°.

[0053] The area intensity of each crystal plane can be determined by profile fitting the XRD pattern after smoothing and background removal using a segmented pseudo-Voigt function. The analysis of the XRD pattern, including smoothing, background removal, and area intensity calculation, can be performed using an analysis program included with the X-ray diffractometer (for example, the integrated powder X-ray analysis software PDXL Ver.2.2, manufactured by RIGAKU).

[0054] The powder composition of this embodiment may have a crystallite size of 300 nm or more, 350 nm or more, or 370 nm or more, and 450 nm or less, or 400 nm or less.

[0055] In this embodiment, the crystallite size of the powder composition may be the crystallite size of zirconia determined from the main XRD peak. The crystallite size of the powder composition is a value calculated from the following formula. D = κλ / βcosθ

[0056] In the above equation, D is the crystallite size (Å), κ is the Scherrer constant (κ=1), λ is the wavelength of the measured X-ray (λ=0.15418 nm when CuKα is used as the source), β is the full width at half maximum (FWHM) of the main XRD peak (°), and θ is the Bragg angle of the main XRD peak. The FWHM of the main XRD peak is the value obtained by profile fitting the XRD pattern after smoothing and background removal using a divided pseudo-Voigt function. Analysis of the XRD pattern, including smoothing, background removal, and profile fitting, can be performed using an analysis program attached to the X-ray diffractometer (for example, the integrated powder X-ray analysis software PDXL Ver.2.2, manufactured by RIGAKU).

[0057] The powder composition of this embodiment has a BET specific surface area of ​​5 m². 2 / g or more 15m 2 One example is that it is less than / g, 7m 2 / g or more, 9m 2 / g or more, 9.5m 2 / g or more or 10m 2 It is preferable that it be 13m or more, and also 13m 2 / g or less, 12m 2 / g or less or 11m 2 It is preferable that the value be less than or equal to / g.

[0058] In this embodiment, the BET specific surface area is the BET specific surface area measured in accordance with JIS Z 8830, and can be measured by the BET single-point method using the carrier gas method with nitrogen as the adsorption gas. The following conditions can be exemplified as specific measurement conditions for the BET specific surface area.

[0059] Adsorption medium: N2 Adsorption temperature: -196℃ Pretreatment conditions: Treatment in air at 250°C for 30 minutes. BET specific surface area can be measured using a general-purpose instrument (e.g., FlowSorb III2305, manufactured by Shimadzu Corporation).

[0060] The powder composition of this embodiment preferably has an average particle size of 0.2 μm or more, 0.3 μm or more, or 0.4 μm or more, and more preferably 0.7 μm or less, 0.6 μm or less, or 0.5 μm or less.

[0061] In this embodiment, the average particle size is the D in the volume particle size distribution of the powder composition measured by the wet method. 50 This is the median diameter and can be measured using general equipment. The sample to be measured should be a slurry obtained by dispersing a powder composition, from which slow aggregation has been removed by dispersion treatment such as ultrasonic treatment, in pure water. The following are preferred methods and conditions for measuring the average particle size. Measuring device: MT3300EXII Calculation mode: HRA Particle refractive index: 2.17 Solvent refractive index: 1.333 Particle shape: non-spherical Measurement sample: Slurry of powder composition (solvent: pure water)

[0062] The powder composition of this embodiment may optionally contain a binder. The moldability can be adjusted by including a binder. The binder is one or more selected from the group consisting of polyvinyl alcohol, polyvinyl butyrate, wax, and acrylic resin, preferably one or more of polyvinyl alcohol and acrylic resin, and more preferably an acrylic resin. In this embodiment, the acrylic resin is a polymer containing at least one of acrylic acid esters and methacrylic acid esters. Specific examples of acrylic resins include one or more selected from the group consisting of polyacrylic acid, polymethacrylic acid, acrylic acid copolymers, and methacrylic acid copolymers, as well as derivatives thereof.

[0063] The powder composition of this embodiment preferably contains granular particles, and more preferably is a granular powder. In this embodiment, "granular particles" are particles in which secondary particles of powder have slowly aggregated due to physical force, and preferably have a particle size of 25 μm or more, more preferably 25 μm to 180 μm, and even more preferably 25 μm to 125 μm. The granular particles may contain a binder such as an acrylic resin as needed. "Granular powder" is a powder mainly composed of granular particles, and preferably is a powder composed of granular particles. The inclusion of granular particles or being a granular powder in the powder composition of this embodiment improves operability (handling).

[0064] Furthermore, the powder composition of this embodiment preferably contains granular particles composed of transition metal elements other than zirconium and hafnium (colored metal elements) and zirconia stabilized with only one or more elements selected from the group consisting of yttrium, calcium, and magnesium (stabilized zirconia). The presence of colored metal elements and stabilized zirconia as granular particles promotes the diffusion of colored metal elements and solid solution into stabilized zirconia during heat treatment, further suppressing the precipitation of colored metal element compounds.

[0065] Furthermore, the powder composition of this embodiment is a granular powder comprising two or more granular particles composed of Ln-solubilated ZrO2, and transition metal elements other than zirconium and hafnium, with the remainder being stabilized ZrO2 (i.e., granular particles composed of powder particles mainly consisting of zirconia stabilized with only one or more elements selected from the group of yttrium, calcium, and magnesium, and comprising two or more granular particles composed of zirconia in which lanthanide rare earth elements are solid-solved, and transition metal elements other than zirconium and hafnium). Preferably, the granular powder consists of two or more granular particles composed of Ln-solubilated ZrO2, and granular particles containing transition metal elements other than zirconium and hafnium, with the remainder being stabilized ZrO2 (i.e., two or more granular particles composed of zirconia in which lanthanide rare earth elements are solid-solved, and granular particles mainly composed of zirconia stabilized with only one or more selected from the group consisting of yttrium, calcium, and magnesium, containing transition metal elements other than zirconium and hafnium).

[0066] If the powder composition of this embodiment contains alumina, it is sufficient that the alumina is uniformly dispersed in the powder composition. For example, the alumina may be contained in at least one type of granular particle, contained in all of the granular particles, or composed solely of alumina, or in any other form.

[0067] The average granule size in the powder composition of this embodiment is 20 μm or more, 30 μm or more, or 40 μm or more, and can also be 100 μm or less, 80 μm or less, 60 μm or less, or 50 μm or less. The average granule size can be determined by a mechanical sieving method using a general rotap-type sieve shaker (e.g., sieve shaker S-1, manufactured by Teraoka Co., Ltd.), and is the granule size that represents 50% by mass on the cumulative granule size curve plotted between the granule size and its mass ratio. In the mechanical sieving method, sieves with mesh openings of 125 μm, 106 μm, 90 μm, 75 μm, 63 μm, 45 μm, 38 μm, and 25 μm can be used in order, in accordance with JIS Z 8801. The following conditions can be given for the mechanical sieving method. Oscillating speed: 300 rpm Swing amplitude: 25mm Standard hammer strokes: 150 rpm Shaking time: 30 minutes

[0068] Prior to measurement, it is preferable to lightly loosen the granular sample so that it can pass through a sieve with a mesh size of 125 μm or less.

[0069] The cumulative granule size curve is obtained by plotting the granule size and its mass ratio, assuming that the granule size of the powder composition remaining on each sieve after shaking is equivalent to the granule size of the smallest opening diameter through which the granule particles passed (for example, assuming that the granule size of the granule particles that passed through a sieve with a mesh size of 90 μm and remained on a sieve with a mesh size of 75 μm is 90 μm).

[0070] The powder composition of this embodiment can be manufactured using industrial methods, such as uniaxial compression molding, CIP treatment, and equivalent molding methods, as well as calcination methods in air at 950°C to less than 1200°C, and calcination methods in air at 950°C to 1100°C for 0.5 hours to 10 hours, to obtain calcined bodies suitable as precursors for dental prostheses.

[0071] Next, a method for producing the powder composition of this embodiment will be described.

[0072] The method for producing the powder composition of this embodiment is arbitrary as long as a powder composition satisfying the above-described configuration can be obtained. A preferred method for producing the powder composition is a method for producing a powder composition that includes a step (hereinafter also referred to as the "mixing step") in which two or more zirconia powders in which lanthanide rare earth elements are solid-solved, a powder of a transition metal compound other than zirconium and hafnium, and a zirconia powder stabilized with only one or more selected from the group of yttrium, calcium and magnesium, so that the content of the transition metal elements is 1500 ppm or less, wherein each of the zirconia powders in which lanthanide rare earth elements are solid-solved contains a different lanthanide rare earth element.

[0073] In the mixing process, two or more types of zirconia powder in which lanthanide rare earth elements are solid-solved (hereinafter also referred to as "lanthanide solid-solution powder" or "Ln solid-solution powder," and if the lanthanide is erbium, etc., it is also referred to as "erbium solid-solution powder" or "Er solid-solution powder," etc.), powder of a transition metal compound other than zirconium and hafnium (hereinafter also referred to as "colored metal powder"), and zirconia powder stabilized with only one or more elements selected from the group consisting of yttrium, calcium, and magnesium (hereinafter also referred to as "stabilized powder") are provided.

[0074] The Ln solid solution powder, colored metal powder, and stabilizing powder (hereinafter collectively referred to as "raw material powders") preferably have similar physical properties to the powder composition of this embodiment, and it is more preferable that the Ln solid solution powder and stabilizing powder, which make up a large proportion of the powder composition of this embodiment, have similar physical properties to each other. On the other hand, it is preferable that the colored metal powder also has similar physical properties to these, but since it makes up a small proportion of the powder composition of this embodiment and its influence is small, its physical properties may differ from those of the other raw material powders.

[0075] The following are examples of preferred physical properties of Ln solid solution powder and stabilized powder. BET specific surface area: 5m 2 / g or more, 9m 2 / g or more, 9.5m2 / g or more or 10m 2 / g or more, 15m 2 / g or less, 13m 2 / g or less, 12m 2 / g or less or 11m 2 / g or less, Average particle size: 0.2 μm or larger, 0.3 μm or larger, or 0.4 μm or larger, 0.7 μm or less, 0.6 μm or less, or 0.5 μm or less

[0076] The difference between the maximum and minimum BET specific surface area of ​​the Ln solid solution powder and the stabilized powder used in the mixing process (hereinafter also referred to as the "BET difference") is 0m 2 / g or more, 0m 2 / g or more than 0.1m 2 / g or more, and 3.5m 2 / g or less, 2.0m 2 / g or less, 0.7m 2 / g or less, 0.5m 2 / g or less or 0.3m 2 One characteristic is that the amount is less than or equal to / g. Another characteristic is that the difference between the maximum and minimum average particle size of the raw material powder (hereinafter also referred to as "particle size difference") is 0 μm or more, greater than 0 μm, or 0.05 μm or more, and 0.5 μm or less, 0.3 μm or less, or 0.1 μm or less. The smaller the BET difference and particle size difference, the more uniform the physical properties of the powder composition of this embodiment tend to be.

[0077] The Ln solid-solution powder can be any zirconia powder in which a lanthanide rare earth element exhibiting a desired color is dissolved. Examples include zirconia powder in which one or more elements selected from the group consisting of praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holonium, erbium, thulium, and ytterbium are dissolved. Preferably, the zirconia powder contains one or more elements selected from the group of rhubium, erbium, and thulium in solid solution; further, the zirconia powder contains one or more elements selected from the group of praseodymium, neodymium, terbium, and erbium in solid solution; and further, the zirconia powder contains at least one of terbium and erbium in solid solution (hereinafter, the zirconia powder containing erbium in solid solution, etc., will also be referred to as "erbium solid solution powder" or "Er solid solution powder," etc.).

[0078] The Ln solid solution powder consists of two or more types, each containing a different lanthanide rare earth element in solid solution. It can consist of three or more types, four or more types, or up to five types.

[0079] At least one of the Ln solid solution powders may be stabilized with one or more elements selected from the group consisting of yttrium, calcium, and magnesium (stabilizing elements), preferably yttrium.

[0080] The Ln solid-solution powder contained in the powder composition of this embodiment preferably contains a zirconia powder in which at least one of praseodymium and terbium is solid-solution and a stabilizing element, as well as a zirconia powder stabilized with at least one of praseodymium and terbium, and a zirconia powder in which at least one of neodymium and erbium is solid-solution. It is more preferable to include a zirconia powder in which terbium is solid-solution and stabilized with yttrium and terbium (Y-stabilized Tb solid-solution ZrO2), and a zirconia powder in which only erbium is solid-solution (Er solid-solution ZrO2).

[0081] The content of lanthanide rare earth elements in each Ln solid solution powder is arbitrary and can be determined as the ratio of the lanthanide rare earth elements (in oxide terms) [mol] to the total [mol] of zirconia, lanthanide rare earth elements (in oxide terms), and stabilizing elements in the Ln solid solution powder. For example, the terbium content in the Tb solid solution powder can be ({Tb4O7 [mol] / (Tb4O7 + ZrO2) [mol]} × 100) [mol%], which can be 0.0005 mol% or more, 0.005 mol% or more, or 0.03 mol% or more, or 0.10 mol% or less, 0.06 mol% or less, or 0.05 mol% or less. Furthermore, the terbium content in the Y-stabilized Tb solid solution powder ({Tb4O7[mol] / (Tb4O7+ZrO2+Y2O3)[mol]}×100)[mol%] can be 0.0005 mol% or more, 0.002 mol% or more, 0.005 mol% or more, or 0.03 mol% or more, and also 0.10 mol% or less, 0.06 mol% or less, or 0.05 mol% or less.

[0082] Furthermore, examples of erbium content in Er solid-solution powders include ({Er2O3[mol] / (Er2O3+ZrO2)[mol]}×100)[mol%] being 1.5 mol% or more, 2.0 mol% or more, or 3.3 mol% or more, and also being 6 mol% or less, 5.0 mol% or less, or 4.5 mol% or less.

[0083] The praseodymium content in Pr solid solution powder ({Pr6O 11 [mol] / (Pr6O 11 Assuming {+ZrO2)[mol]}×100)[mol%], the content is 0.05 mol% or more, 0.07 mol% or more, or 0.1 mol% or more, and also 1.0 mol% or less, 0.6 mol% or less, 0.5 mol% or less, or 0.4 mol% or less. Furthermore, the praseodymium content in the Y-stabilized Pr solid solution powder is ({Pr6O 11 [mol] / (Pr6O 11Assuming the concentration is (+ZrO2+Y2O3)[mol] × 100)[mol%], examples include 0.05 mol% or more, 0.07 mol% or more, or 0.1 mol% or more, and also 1.2 mol% or less, 1.0 mol% or less, or 0.8 mol% or less.

[0084] Examples of neodymium content in Nd solid solution powders include ({Nd2O3[mol] / (Nd2O3+ZrO2)[mol]}×100)[mol%] being 0.05 mol% or more, 0.07 mol% or more, or 0.1 mol% or more, and also being 2.0 mol% or less, 1.8 mol% or less, or 1.6 mol% or less. Similarly, examples of neodymium content in Y-stabilized Nd solid solution powders include ({Nd2O3[mol] / (Nd2O3+ZrO2+Y2O3)[mol]}×100)[mol%] being 0.05 mol% or more, 0.07 mol% or more, or 0.1 mol% or more, and also being 2.0 mol% or less, 1.8 mol% or less, or 1.6 mol% or less.

[0085] If the Ln solid solution powder contains a stabilizing element, the amount of the stabilizing element is arbitrary. If the stabilizing element is yttrium, the yttrium content can be expressed as the ratio of yttrium [mol] converted to Y2O3 to the total [mol] of zirconia (ZrO2), lanthanide rare earth elements converted to oxides, and yttrium converted to Y2O3 in the Ln solid solution powder, and may be 1.5 mol% or more, 2 mol% or more, 3 mol% or more, 3.3 mol% or more, 3.5 mol% or more, or 7 mol% or more, or 6.5 mol% or less, 6 mol% or less, 5.5 mol% or less, or 5.2 mol% or less.

[0086] The stabilizing powder is zirconia powder stabilized with only one or more elements selected from the group consisting of yttrium, calcium, and magnesium. Preferably, the stabilizing powder is zirconia powder that contains elements that have the function of stabilizing zirconia and does not contain solid solutions of lanthanide rare earth elements that have the function of coloring zirconia. More preferably, the stabilizing powder is zirconia powder stabilized with yttrium alone.

[0087] The amount of stabilizing elements contained in the stabilizing powder should be such that the zirconia is partially stabilized. When the stabilizing element is yttrium, the molar ratio of yttrium converted to Y2O3 (i.e., {Y2O3[mol] / (ZrO2+Y2O3)[mol]}×100[mol%]) to the total of zirconia (ZrO2) and yttrium converted to Y2O3 in the stabilizing powder should be 2.7 mol% or more, 3 mol% or more, 3.3 mol% or more, 3.5 mol% or more, or 7 mol% or more, and also 6.5 mol% or less, 6 mol% or less, 5.5 mol% or less, 5.2 mol% or less, or 4.5 mol% or less.

[0088] The method for producing Ln solid solution powder and stabilized powder is arbitrary and includes, for example, a method in which a mixture of at least one of a stabilizing element source and a lanthanide source and zirconia sol is heat-treated at 950°C to 1250°C, and then pulverized.

[0089] The stabilizing element source is a compound containing a stabilizing element, and may include one or more selected from the group consisting of oxides, hydroxides, oxyhydroxides, halides, sulfates, and nitrates of the stabilizing element, further, one or more selected from the group consisting of oxides, hydroxides, and chlorides of the stabilizing element, and further, at least one of the oxides and chlorides of the stabilizing element, and further, chlorides.

[0090] Specific stabilizing element sources include, for example, one or more selected from the group consisting of yttrium oxide, yttrium hydroxide, yttrium chloride, yttrium bromide, yttrium boride, yttrium iodide, yttrium sulfate, and yttrium nitrate; one or more selected from the group consisting of calcium oxide, calcium hydroxide, calcium chloride, calcium bromide, calcium boride, calcium iodide, calcium sulfate, and calcium nitrate; and one or more selected from the group consisting of magnesium oxide, magnesium hydroxide, magnesium chloride, magnesium bromide, magnesium boride, magnesium iodide, magnesium sulfate, and magnesium nitrate. Preferred stabilizing element sources include one or more selected from the group consisting of yttrium oxide, yttrium hydroxide, yttrium oxyhydroxide, yttrium chloride, yttrium bromide, yttrium boride, yttrium iodide, yttrium sulfate, and yttrium nitrate; further, one or more selected from the group consisting of yttrium oxide, yttrium hydroxide, yttrium chloride, and yttrium bromide; further, one or more selected from the group consisting of yttrium oxide, yttrium hydroxide, and yttrium chloride; further, at least one of yttrium oxide and yttrium chloride; and further, yttrium chloride.

[0091] The lanthanide source is a compound containing lanthanide rare earth elements, and may include one or more selected from the group of oxides, hydroxides, oxyhydroxides, halides, sulfates, and nitrates of lanthanide rare earth elements, and further, one or more selected from the group of oxides, hydroxides, and chlorides of lanthanide rare earth elements, and further, at least one of the oxides and chlorides of lanthanide rare earth elements, and further, chlorides.

[0092] Examples of lanthanide sources include one or more oxides, hydroxides, oxyhydroxides, halides, sulfates, and nitrates containing one or more selected from the group consisting of praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprodium, holonium, erbium, thulium, and ytterbium. Examples of lanthanide sources containing erbium (hereinafter, lanthanide sources containing erbium, etc., are also referred to as "erbium sources") include one or more selected from the group consisting of erbium oxide, erbium hydroxide, erbium oxyhydroxide, erbium chloride, erbium bromide, erbium boride, erbium iodide, erbium sulfate, and erbium nitrate, one or more selected from the group consisting of erbium oxide, erbium hydroxide, and erbium chloride, and further, erbium oxide and erbium chloride, and further, erbium chloride. Examples of terbium sources include one or more selected from the group consisting of terbium oxide, terbium hydroxide, terbium chloride, terbium bromide, terbium boride, terbium iodide, terbium sulfate, and terbium nitrate, and more specifically, one or more selected from the group consisting of terbium oxide, terbium hydroxide, and terbium chloride, and further, terbium oxide and terbium chloride, and even further, terbium chloride. Similar compounds can be used for lanthanide sources containing other lanthanide rare earth elements, with at least one of oxides and chlorides, and more preferably chlorides.

[0093] The zirconia sol is preferably obtained by either a hydrothermal synthesis method or a hydrolysis method, and more preferably by a hydrolysis method. The zirconia sol may also be in a hydrated state.

[0094] In the production of Ln solid solution powder, a lanthanide source and, if necessary, a stabilizing element source should be mixed with zirconia sol. On the other hand, in the production of stabilized powder, a stabilizing element source should be mixed with zirconia sol. This yields a mixture.

[0095] The mixing method can be any known method by which the stabilizing element source or lanthanide source is uniformly mixed with zirconia. The mixing method can be at least one of wet mixing or dry mixing, and more preferably wet mixing. In the case of wet mixing, the solvent can be at least one of water and alcohol, and more preferably a solvent containing at least ethanol, and more preferably ethanol.

[0096] The resulting mixture is heat-treated at 950°C or above, or 1000°C or above, and 1250°C or below, or 1200°C or below. As the heat treatment temperature increases, the BET specific surface area tends to decrease. Therefore, in order to achieve the desired BET specific surface area, the heat treatment temperature, as well as the heat treatment time and heating / cooling rate, should be appropriately set within the above temperature range, depending on the processing volume, the heat treatment method used, and the heat treatment furnace.

[0097] Ln solid solution powder and stabilized powder are obtained by grinding the heat-treated mixture, respectively. The grinding method can be any known method that results in a desired particle size for the resulting powder. The grinding method can be at least one of wet grinding and dry grinding, or more preferably wet grinding. In the case of wet grinding, the solvent can be at least one of water and alcohol, with alcohol being preferred. The grinding time varies depending on the grinding method and the amount of powder being ground. As the amount of powder being ground increases and the grinding time increases, the particle size of the resulting powder composition tends to decrease until equilibrium is reached, so the grinding conditions should be adjusted appropriately according to the desired particle size.

[0098] By appropriately adjusting the heat treatment temperature and grinding time, the BET specific surface area and powder particle size can be adjusted.

[0099] The colored metal powder is a powder of a transition metal compound other than zirconium and hafnium (a powder of a compound of a colored metal element), and may be included as is in the powder composition of this embodiment. Preferably, the colored metal powder is a powder of at least one of the oxides, hydroxides, oxyhydroxides, chlorides, sulfates, and nitrates of a colored metal element, and more preferably, a powder of at least one of the oxides, hydroxides, and oxyhydroxides. For example, as a colored metal powder in which the colored metal element is manganese, examples include one or more powders selected from the group MnO, MnO2, Mn3O4, Mn(OH)2, MnOOH, MnCl2, MnSO4, Mn(NO3)2, and Mn(COOH)2, more preferably one or more powders selected from the group MnO, MnO2, Mn3O4, Mn(OH)2, and MnOOH, and more preferably one or more powders selected from the group MnO, MnO2, and Mn3O4. Examples of colored metal powders in which the colored metal element is cobalt include one or more powders selected from the group consisting of CoO, CoO2, Co3O4, Co(OH)2, CoOOH, CoCl2, CoSO4, Co(NO3)2, and CoCOOH, as well as one or more powders selected from the group consisting of CoO2, Co3O4, Co(OH)2, and CoOOH, and as well as powders of at least one of CoO2 and Co3O4. Examples of colored metal powders in which the colored metal element is titanium include one or more powders selected from the group consisting of TiO2, Ti(OH)2, TiOOH, TiCl2, TiSO4, Ti(NO3)2, and TiCOOH, as well as one or more powders selected from the group consisting of TiO2, Ti(OH)2, and TiOOH, and as well as powders of TiO2.

[0100] The amount of colored metal powder should be such that the content of colored metal elements in the powder composition obtained by the mixing process is 1500 ppm or less. The amount of colored metal elements can be any amount such that the content is 1500 ppm or less, for example, greater than 0 ppm, 5 ppm or more, 10 ppm or more, or 40 ppm or more, and also 1500 ppm or less, 1200 ppm or less, 1000 ppm or less, 800 ppm or less, 750 ppm or less, or 700 ppm or less.

[0101] In the mixing process, in addition to the raw material powder, an alumina source may be provided as needed. The alumina source may be at least one of alumina and its precursors, and examples include at least one of alumina and aluminum hydroxide, or alumina alone. The amount of alumina source should be equivalent to the amount of alumina in the target powder composition. The alumina source may be contained in at least one of the Ln solid solution powder and the stabilized powder.

[0102] In the mixing process, it is preferable that the mixture does not contain iron compound powder. However, it may contain iron as an unavoidable impurity in each raw material powder.

[0103] The mixing method in the mixing process involves mixing the raw material powders and, if necessary, an alumina source, so that the content of transition metal elements is 1500 ppm or less. By appropriately selecting the type and amount of each raw material powder to be mixed, a desired powder composition can be obtained. For example, to obtain a sintered body with a low saturation color tone (for example, a color tone corresponding to A1-A2, B1-B2, C1-C2, or D2 in the Vita Classical Shade Guide), a high proportion of stabilizing powder can be added during mixing. Similarly, examples include using a lanthanide solid solution powder containing zirconia powder in which at least one of neodymium and erbium is solid-solved, preferably zirconia powder in which erbium is solid-solved, to obtain a sintered body having a reddish tooth color, and mixing it in a high proportion; using a lanthanide solid solution powder containing praseodymium and terbium in a solid-solution form to obtain a sintered body having a yellowish tooth color, and mixing it in a high proportion; and using a colored metal powder in a high proportion to obtain a sintered body having a grayish tooth color.

[0104] The mixing method is arbitrary and can be either dry mixing or wet mixing. For example, dry mixing is preferred when mixing efficiency is important, while wet mixing is preferred when high uniformity is important.

[0105] The method for producing the powder composition of this embodiment may include at least one of the following steps: a step of granulating the raw material powders prior to the mixing step, and a step of granulating the powder composition after the mixing step. It is preferable to include a step of granulating each raw material powder prior to the mixing step (hereinafter, the former will also be referred to as the "pre-granulation step" and the latter as the "post-granulation step," and these together will also be referred to as the "granulation step").

[0106] If a pre-granulation step is performed, a granular powder containing each raw material powder may be used in the mixing step instead of or in addition to each raw material powder. In this case, the granular powder used in the mixing step may be, for example, granular powder of zirconia (Ln solid-solution ZrO2) in which lanthanide rare earth elements are solid-solutioned, granular powder of zirconia (stabilized Ln solid-solution ZrO2) in which lanthanide rare earth elements are solid-solutioned and stabilized with stabilizing elements and lanthanide rare earth elements, granular powder of transition metal compounds other than zirconium and hafnium, granular powder of zirconia (stabilized ZrO2) stabilized with only one or more selected from the group consisting of yttrium, calcium and magnesium, zirconium and hafnium Examples include granular zirconia powder containing transition metal compounds other than zirconium and hafnium, with the remainder being stabilized by one or more elements selected from the group of yttrium, calcium, and magnesium (i.e., granular powder composed of powder mainly consisting of zirconia containing transition metal compounds other than zirconium and hafnium, and stabilized by one or more elements selected from the group of yttrium, calcium, and magnesium), and one or more selected from the group of Ln-soluble ZrO2 granular powders containing transition metal compounds other than zirconium and hafnium. Furthermore, it is preferable to provide granular powder containing at least a compound of a colored metal element, with the remainder being stabilized by granular zirconia particles (i.e., granular particles composed of powder mainly consisting of zirconia containing a compound of a colored metal element and stabilized by stabilizing elements).

[0107] The average particle size of each granular powder obtained in the pre-granulation step is preferably the same as the average particle size of the powder composition of this embodiment. Furthermore, while it is preferable that the average particle sizes of each granular powder are similar, the difference between the maximum and minimum values ​​of the average particle sizes of each granular powder may be 0 μm or more, greater than 0 μm, or 1 μm or more, and may also be 10 μm or less, 8 μm or less, or 5 μm or less.

[0108] If a post-granulation step is included, the powder composition obtained in the mixing step can be granulated.

[0109] The granulation method in the granulation process can be any method by which secondary particles of the powder (raw material powder or powder composition) slowly aggregate to form granular particles. Examples of granulation methods include one or more selected from the group consisting of spray drying, stirring granulation, and extrusion granulation, and more specifically, 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 granular powder. The solvent can be at least one of water and alcohol. Additionally, if necessary, a binder such as acrylic resin may be mixed into the slurry before spray-drying and granulation. For example, when the granular particles are made of zirconia stabilized with a transition metal element other than zirconium and hafnium, with the remainder being one or more elements selected from the group of yttrium, calcium, and magnesium (i.e., zirconia stabilized with a transition metal element other than zirconium and hafnium, with the main component being one or more elements selected from the group of yttrium, calcium, and magnesium), a stabilizing powder, a colored metal powder, and a solvent are mixed to form a slurry, which is then spray-dried. In the spray-drying method, the particle size of the resulting granular particles tends to be larger as the concentration of powder in the slurry increases. Therefore, the particle size of the granular particles obtained by spray-drying can be adjusted by appropriately adjusting the concentration of powder in the slurry.

[0110] Next, a method for producing a calcined body using the powder composition of this embodiment will be described.

[0111] A calcined body can be produced by a method for producing a calcined body, which includes the step of calcining a molded body composed of the powder composition of this embodiment.

[0112] The molded body subjected to the calcination process (hereinafter also referred to as the "calcination process") of the molded body composed of the powder composition of this embodiment is a compacted powder, and more specifically, a compacted powder in which the powder composition of this embodiment has physically aggregated and maintains a certain shape.

[0113] The molded body may have any shape suitable for the application. Examples of molded body shapes include one or more selected from the group consisting of cubes, rectangular prisms, polyhedra, columnar shapes, cylindrical shapes, disc shapes, spherical shapes, and approximately spherical shapes. In addition, considering thermal shrinkage due to calcination, a shape similar to the shape of the target calcined body, such as a disc shape used in CAD / CAM processing, may be used.

[0114] The molded body has a measured density of 2.75 g / cm³. 3 or more, or 3.10 g / cm³ 3 That's all, and also 3.50 g / cm³ 3 The following or 3.40 g / cm³ 3 The following can be cited: Such measured densities correspond to a relative density of 45% to 58%.

[0115] The measured density is the density [g / cm³] obtained from the mass obtained from mass measurement, relative to the volume obtained from the dimensions obtained from dimensional measurement. 3 ]

[0116] The method for manufacturing the molded body is arbitrary, and any molding method that can form a compacted powder from the powder composition of this embodiment is acceptable. Examples of molding methods include one or more selected from the group consisting of uniaxial press, cold isostatic press (hereinafter also referred to as "CIP"), slip casting, sheet molding, slurry casting, and injection molding. For simplicity, the molding method is preferably at least one of slip casting, injection molding, uniaxial press, and CIP, or more preferably at least one of uniaxial press and CIP, or even more preferably a method in which CIP is performed after uniaxial press. Examples of uniaxial press pressures include 15 MPa to 150 MPa, and examples of CIP pressures include 90 MPa to 400 MPa. The density of the resulting molded body tends to increase as the molding pressure increases.

[0117] In the calcination process, a calcined body is obtained by calcining the molded body. Unlike the molded body (compacted powder), the calcined body is composed of fused particles. The fused particles have the structure of the initial sintering stage, and the calcined body has a structure in which the particles form neckings with each other while retaining some of the shape of the powder particles of the powder composition of this embodiment. As a result, the calcined body has mechanical properties suitable for machining.

[0118] In the calcination process, calcination can be performed at a temperature below the sintering temperature of zirconia. In this embodiment, even if the same heat treatment conditions are applied to molded bodies of powder compositions with different compositions, calcined bodies exhibiting similar processing characteristics can be obtained. Therefore, calcined bodies can be manufactured by simultaneously heat-treating molded bodies with different compositions, further improving the efficiency of calcined body production. Furthermore, from the viewpoint of calcined body production efficiency, it is preferable to obtain calcined bodies by atmospheric pressure firing. The following conditions can be used as calcination conditions, but the conditions should be set appropriately depending on the amount of molded bodies to be calcined and the characteristics of the calcination furnace used. Calcination atmosphere: Oxidizing atmosphere, preferably air atmosphere Calcination temperature: 900°C or higher, 950°C or higher, or 1000°C or higher, Below 1200℃, 1150℃ or below, or 1100℃ or below Pre-cooking time: 0.5 hours or more, 1 hour or more, or 2 hours or more, 9 hours or less, 6 hours or less, or 4 hours or less

[0119] In this embodiment, "atmospheric pressure firing" refers to a method of heating the workpiece without applying external force during heat treatment, and in particular, a method of heating the workpiece at a temperature below the sintering temperature without applying external force during the calcination process.

[0120] The calcination process yields a calcined body (hereinafter also referred to as "the calcined body of this embodiment") composed of fused particles of transition metal compounds other than zirconium and hafnium, zirconia in which two or more lanthanide rare earth elements are solid-solved, and zirconia stabilized with only one or more elements selected from the group consisting of yttrium, calcium, and magnesium, wherein the content of transition metal elements other than zirconium and hafnium is 1500 ppm or less.

[0121] In this embodiment, the calcined body is preferably in which the colored metal elements are uniformly dispersed or solid-dissolved in the zirconia. Alternatively, a portion of the colored metal elements may be solid-dissolved in the zirconia. An example of a state in which the colored metal elements are uniformly dispersed in the zirconia is that it does not contain aggregated particles of compounds containing colored metal elements with a particle size of 0.5 μm or larger.

[0122] The calcined body only needs to have a hardness suitable for CAD / CAM machining, for example, a Vickers hardness of 25-150 HV (= kgf / mm²). 2 ) is one example. The calcined body of this embodiment preferably has a Vickers hardness of 30 HV or more or 35 HV or more, and more preferably 70 HV or less, 60 HV or less, or 50 HV or less.

[0123] In particular, it is preferable that calcined bodies of this embodiment have similar Vickers hardness when obtained under similar manufacturing conditions (molding conditions and calcination conditions), and it is preferable that the difference in Vickers hardness between such calcined bodies is 12 HV or less, 7 HV or less, or 5 HV or less. This makes it easier to obtain calcined bodies that exhibit similar processing characteristics under the same processing conditions. It is preferable that the difference in Vickers hardness due to differences in composition (hereinafter also referred to as "hardness difference") in the calcined bodies of this embodiment is small, and examples of differences in Vickers hardness between calcined bodies due to differences in composition include 0 HV or more, greater than 0 HV, 1 HV or more, or 2 HV or more.

[0124] One indicator of hardness difference is the value obtained by measuring the Vickers hardness of calcined bodies obtained by molding and calcining a powder composition having a composition that can produce sintered bodies having color tones corresponding to A2 and C4 in the Vita Classical Shade, respectively, under the following conditions, and taking the absolute value of the difference (hereinafter also referred to as "hardness difference (A2 / C4)"). (Molding conditions) Molding method: Uniaxial pressing and CIP treatment Uniaxial pressing pressure: 49±3MPa CIP pressure: 196±5MPa (Calibration conditions) Callibration method: Firing at atmospheric pressure Atmosphere: Atmospheric atmosphere Baking time: 1000℃ x 2 hours Heating rate: 50±5℃ / hour Cooling rate: 300±10℃ / hour

[0125] Another indicator of hardness difference is the absolute difference in Vickers hardness between a calcined body (hereinafter also referred to as "A1 calcined body") obtained by molding and calcining a powder composition having a composition that can produce a sintered body having a color tone corresponding to A1 in the Vita Classical Shade under the above conditions, and a calcined body (hereinafter also referred to as "X calcined body" depending on the color tone of the calcined body, and if the color tone is B1, etc., it will also be referred to as "B1 calcined body") obtained by molding and calcining a powder composition having a composition that can produce a sintered body having a different color tone under the above conditions (hereinafter also referred to as "X calcined body" depending on the color tone of the calcined body, and if the color tone is B1, etc., it will also be referred to as "B1 calcined body"). (hereinafter also referred to as "hardness difference (A1)").

[0126] Even if the yttrium content (amount of stabilizing element) changes, there is little effect on the Vickers hardness values ​​of the A1 calcined body and the X calcined body. However, the yttrium content of the calcined body used to evaluate the hardness difference (A1) should be between 2.8 mol% and 6.0 mol%, further between 4.0 mol% and 4.5 mol%, and even further between 4.2 mol%.

[0127] As a calcined body used for evaluating the hardness difference (A1), a specific example is a calcined body obtained by filling a mold with a powder composition having a yttrium content of 4.244 mol%, an erbium content of 0.053 mol%, a terbium content of 0.002 mol%, a cobalt content of 15 ppm, and a titanium content of 75 ppm, with the remainder being Y-stabilized ZrO2, then performing uniaxial compression molding at a pressure of 49 MPa, followed by CIP treatment at a pressure of 196 MPa to obtain a molded body, and finally heat-treating the molded body in an air atmosphere at a calcination temperature of 1000°C for a calcination time of 2 hours.

[0128] The hardness difference (A1) is preferably small, and more preferably 11HV or less, 9HV or less, 7HV or less, or 5HV or less. This makes it easier to obtain calcined bodies that exhibit similar processing characteristics under the same processing conditions. Examples of calcined bodies in this embodiment include those with a hardness difference (A1) of 0HV or more, greater than 0HV, 1HV or more, or 2HV or more.

[0129] The hardness difference (A1) is the absolute value of the difference between the Vickers hardness of each calcined material (A2, A3, A3.5, A4, B1, B2, B3, B4, C1, C2, C3, C4, D2, D3, or D4) and the Vickers hardness of the A1 calcined material.

[0130] In this embodiment, the Vickers hardness can be measured using a standard Vickers tester (e.g., Q30A, Qness) equipped with a diamond square pyramidal indenter. The measurement is performed by statically pressing the indenter into the surface of the sample and visually measuring the diagonal length of the indentation formed on the surface of the sample. Using the obtained diagonal length, the Vickers hardness can be calculated from the following formula.

[0131] Hv=F / {d 2 / 2sin(α / 2)} In the above equation, Hv is the Vickers hardness (HV), F is the measured load (1 kgf), d is the diagonal length of the indentation (mm), and α is the angle of the indenter (136°).

[0132] The following conditions can be used to measure Vickers hardness.

[0133] Measurement sample: Disc-shaped object with a thickness of 3.0 ± 0.5 mm Measured load: 1 kgf Prior to measurement, the sample should be pre-treated by polishing the measurement surface with #800 grit waterproof abrasive paper to remove any irregularities exceeding 0.1 mm.

[0134] The calcined material of this embodiment has a measured density of 2.75 g / cm³. 3 or more, or 3.10 g / cm³ 3 That's all, and also 3.50 g / cm³ 3 The following or 3.40 g / cm³ 3 The following can be cited. Such measured densities correspond to a relative density of 45% to 58%. Note that since the calcined material has hardly undergone densification due to thermal shrinkage, it may be equivalent to the measured density of the molded material.

[0135] A sintered body can be manufactured using at least one of the powder composition and the calcined body of this embodiment.

[0136] A sintered body can be obtained by a method for manufacturing a sintered body, which includes the step of sintering at least one of the powder composition of this embodiment and the calcined body of this embodiment. When manufacturing a sintered body directly from the powder composition of this embodiment, it is possible to mold it into a body and then sinter it.

[0137] The sintering method can be one or more known sintering methods selected from the group consisting of atmospheric pressure sintering, pressure sintering, and vacuum sintering. The sintering method is preferably one suitable for the manufacture of dental prosthesis materials, and specifically, it may be a sintering method that does not involve pressure sintering or vacuum sintering, a sintering method that includes at least atmospheric pressure sintering, or even one that consists solely of atmospheric pressure sintering. From at least one of the powder composition and the calcined body of this embodiment (hereinafter also referred to as "the powder composition, etc. of this embodiment"), a zirconia sintered body suitable for dental prostheses can be obtained as a so-called atmospheric pressure sintered body, even if the sintering method is atmospheric pressure sintering only. In this embodiment, "atmospheric pressure sintering" refers to a method of sintering by heating without applying external force to the material to be sintered during sintering.

[0138] The following conditions are examples of sintering conditions in atmospheric pressure sintering, but the conditions should be adjusted according to the amount of molded body and calcined body to be sintered, and the characteristics of the sintering furnace. Sintering temperature: 1200°C or higher, 1300°C or higher, 1400°C or higher, 1430°C or higher, 1450°C or higher, or 1500°C or higher, Below 1650℃, below 1580℃, or below 1560℃ Heating rate: 50°C / hour or more, 100°C / hour or more, 150°C / hour or more, and 500°C / min or less or 300°C / min or less Sintering time: 0.1 hours or more, 0.5 hours or more, or 1 hour or more, 5 hours or less, 3 hours or less, or 2 hours or less Sintering atmosphere: At least one of an oxygen atmosphere and / or an air atmosphere, preferably an air atmosphere.

[0139] The time required for the entire sintering process, from the start of heating to the end of cooling, can be any time between 10 minutes and 10 hours. Furthermore, the molded body (or calcined body) may be placed in a preheated firing furnace and sintered therein. In this embodiment, the atmospheric environment consists mainly of nitrogen and oxygen, with an oxygen concentration of approximately 18-23% by volume.

[0140] By sintering at least one of the powder composition of this embodiment and the calcined body of this embodiment, a sintered body (hereinafter also referred to as "the sintered body of this embodiment") is obtained, which is composed of zirconia crystal particles in which lanthanide rare earth elements are solid-dissolved, and zirconia crystal particles in which transition metal elements other than zirconium and hafnium are solid-dissolved, and which are stabilized with only one or more elements selected from the group consisting of yttrium, calcium, and magnesium, wherein the zirconia in which the lanthanide rare earth elements are solid-dissolved contains two or more types of zirconia in which different lanthanide rare earth elements are solid-dissolved, and the content of the transition metal elements is 1500 ppm or less.

[0141] The sintered body of this embodiment preferably has a color tone similar to that of a dental color 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 the Vita Classical Shades.

[0142] As a representative color tone in this embodiment, see L in Table 1. * a * b * The color tones of the color system are listed in Table 2. Also, preferred L * a * b * Examples of color tones within a color system are provided. However, since the perceived color tone differs depending on the translucency of the sintered body, the color tone values ​​may vary even for sintered bodies belonging to the same color classification.

[0143] [Table 1]

[0144] [Table 2]

[0145] In this embodiment, the color tone of the sintered body is measured in SCI mode using a general spectrophotometer (e.g., CM-700d, manufactured by Konica Minolta), with a D65 light source and a white calibration plate as the background. The measurement sample should be a disc-shaped sintered body with a thickness of 1 ± 0.02 mm and a surface roughness Ra ≤ 0.02 μm on both sides.

[0146] The sintered body of this embodiment preferably has light transmittance suitable for use as a dental prosthetic material, and this value may vary depending on the color tone. For example, with a sample thickness of 1 mm (moreover 1 ± 0.1 mm), the total light transmittance to a D65 light source may be 15% or more, 20% or more, 25% or more, or 30% or more, and also 47% or less, 45% or less, 42% or less, or 39% or less.

[0147] The total light transmittance is measured using a general haze meter (e.g., NDH4000, manufactured by Nippon Denshoku Co., Ltd.) and according to the method compliant with JIS K 7361-1.

[0148] In this embodiment, it is preferable that the sintered body has strength suitable for use as a dental prosthetic material. Such strength is preferably 800 MPa or more or 850 MPa or more as a three-point bending strength, and also preferably 1200 MPa or less, 1000 MPa or less, or 900 MPa or less.

[0149] In this embodiment, the three-point bending strength is measured according to the method conforming to JIS R 1601. The measurement sample is a column shape 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 in the horizontal direction to the measurement sample.

[0150] The sintered body of this embodiment can be applied to known uses of zirconia sintered bodies, but in particular, it can be used as a dental material, and more specifically, as a dental prosthesis. Examples of dental prostheses include crowns, bridges, inlays, onlays, and veneers. [Examples]

[0151] The embodiment will be described below using examples. However, this embodiment is not limited to these examples.

[0152] (Crystalline phase and monoclinic ratio) The crystalline phase of the powder composition was identified by XRD measurement using an X-ray diffractometer (instrument name: Ultima IV, manufactured by RIGAKU Corporation) under the following conditions.

[0153] Radiation source: CuKα radiation (λ=0.15418nm) Measurement mode: Continuous scan Scan speed: 4° / min Measurement range: 2θ = 26° ~ 33° Acceleration voltage / current: 40mA / 40kV Divergence vertical limiting slit: 10mm Divergence / Induction Slit: 1° Light-receiving slit: open Detector: Semiconductor detector (D / teX Ultra) Filter: Ni filter Goniometer radius: 185mm Crystalline layers were identified using the analysis program included with the X-ray diffractometer (program name: Integrated Powder X-ray Analysis Software PDXL Ver.2.2, manufactured by RIGAKU Corporation). Smoothing and background removal processes were performed, and the processed XRD patterns were profile-fitted using a segmented pseudo-Voigt function.

[0154] The monoclinic fraction was determined from the XRD pattern after the above processing using the following formula.

[0155] fM =[1-{[It(111)+Ic(111)] / [Im(111)+Im(11-1) +It(111)+Ic(111)]」×100 (crystallite size) The crystallite size of the powder composition was determined using the main XRD peak in the XRD pattern obtained by the same method and process as for (crystal phase and monoclinic fraction), and was calculated using the following formula.

[0156] D = κλ / βcosθ (density measurement) The density of the molded and calcined bodies was determined from the mass measured by mass measurement and the volume determined by dimensional measurement. For dimensional measurement, a disc-shaped sample was used, and the diameter of the upper end, the diameter of the lower end, and the thickness were measured at four points each using calipers. The volume was then calculated from the average thickness and the average diameter of the upper and lower ends.

[0157] The density of the sintered body was measured according to the method specified in JIS R 1634.

[0158] (Average particle size) The average granule size was defined as the granule size that corresponds to 50% by mass on the cumulative granule size curve plotted between the granule size and its mass percentage, obtained by mechanical sieving using a rotary sieve shaker (device name: Sieve Shaker S-1, manufactured by Teraoka Corporation) under the following conditions.

[0159] Oscillating speed: 300 rpm Swing amplitude: 25mm Standard hammer strokes: 150 rpm Shaking time: 30 minutes In the mechanical sieving method, sieves with mesh sizes of 125 μm, 106 μm, 90 μm, 75 μm, 63 μm, 45 μm, 38 μm, and 25 μm were stacked in order, in accordance with JIS Z 8801. The cumulative granule size curve was created by plotting the granule size of the powder composition remaining in each mesh size sieve after shaking, assuming that it was equivalent to the granule size of the sieve with the mesh size above it, and then plotting the granule size against its mass ratio.

[0160] (Vickers hardness) Vickers hardness was determined using a Vickers hardness tester (device name: Q30A, manufactured by Qness) under the following conditions: the indenter was statically pressed into the surface of the sample, and the diagonal length of the indentation formed on the sample surface was visually measured. The obtained diagonal length was then used to calculate the Vickers hardness using the Vickers hardness formula described above.

[0161] Measurement sample: Disc-shaped object with a thickness of 3.0 ± 0.5 mm Measured load: 1 kgf Prior to the measurement, the sample used was a calcined body whose measurement surface had been polished to a thickness of 0.1 mm with #800 grit waterproof abrasive paper.

[0162] (Hardness difference (A2 / C4)) The hardness difference (A2 / C4) was determined by measuring the Vickers hardness of calcined bodies obtained by molding and calcining powder compositions having compositions that can produce sintered bodies with color tones corresponding to A2 and C4 in the Vita Classical Shade, respectively, under the following conditions, and taking the absolute value of the difference. (Molding conditions) Molding method: Uniaxial pressing and CIP treatment Uniaxial pressing pressure: 49±3MPa CIP pressure: 196±5MPa (Calibration conditions) Callibration method: Firing at atmospheric pressure Atmosphere: Atmospheric atmosphere Baking time: 1000℃ x 2 hours Heating rate: 50±5℃ / hour Cooling rate: 300±10℃ / hour

[0163] (Hardness difference (A1)) The hardness difference (A1) was determined by measuring the Vickers hardness of A2, A3, A3.5, A4, B1, B2, B3, B4, C1, C2, C3, C4, D2, D3, or D4 calcined bodies and taking the absolute value of the difference between their Vickers hardness and that of the A1 calcined body. The calcined body from Example 3 was used as the A1 calcined body.

[0164] (Total light transmittance) Total light transmittance was measured using a haze meter (device name: NDH4000, manufactured by Nippon Denshoku Co., Ltd.) in accordance with JIS K 7361-1. A D65 light source was used as the light source.

[0165] The sample used for measurement was a disc-shaped sintered body sample with a diameter of 25 mm and a thickness of 1 mm, which had been polished on both sides to achieve a surface roughness of Ra ≤ 0.02 μm.

[0166] (Three-point bending strength) The three-point bending strength was measured according to the method conforming to JIS R 1601. The sample used for measurement was a column with a width of 4 mm, a thickness of 3 mm, and a length of 45 mm. The measurement was performed by applying a load horizontally to the sample with a support distance of 30 mm.

[0167] (color tone) Color tones were measured using a spectrophotometer (device name: CM-700d, manufactured by Konica Minolta) with a D65 light source in SCI mode. The measurement was performed using a white calibration plate as the background, a so-called white-background measurement. The sample used was a 1 mm thick, disc-shaped sintered body that had been polished on both sides to achieve a surface roughness of Ra ≤ 0.02 μm.

[0168] Example 1 (Yttrium-stabilized zirconia powder) A zirconia sol obtained by hydrolyzing an aqueous solution of zirconium oxychloride was mixed with yttrium chloride to a concentration of 4.3 mol% in terms of Y2O3. The mixture was then dried in air at 180°C and calcined at 1160°C for 2 hours. After calcination, it was dried in air at 110°C. 199.9 g of the dried calcined material, 0.1 g of α-alumina powder, and pure water were mixed in a ball mill to obtain a slurry containing yttrium-stabilized zirconia powder. The slurry was then portioned out and dried in air at 110°C to obtain yttrium-stabilized zirconia powder. The BET specific surface area was evaluated, and it was found to be 10.1 m². 2The particle size and average particle diameter were 0.45 μm / g. To the obtained slurry, an acrylic acid-based binder was added and mixed so that the mass ratio of the binder to the mass of powder in the slurry was 3% by mass. The slurry was spray-dried in air at 180°C to obtain a granular powder (hereinafter also referred to as "Y(4.3) stabilized ZrO2 granular powder") containing 3% by mass of the acrylic acid-based binder, 0.05% by mass of alumina, and the remainder being 4.3 mol% of yttrium-stabilized zirconia. The average granular particle size of this granular powder was 44 μm.

[0169] (Yttrium-stabilized terbium-solution zirconia powder) A slurry containing yttrium-stabilized terbium-solution zirconia powder was obtained by adding yttrium chloride to the zirconia sol so that the yttrium concentration was 4.3 mol% in terms of Y2O3, and terbium oxide (III, IV) to the terbium concentration was 0.04 mol% in terms of Tb4O7, respectively, in the same manner as for yttrium-stabilized zirconia powder. The obtained yttrium-stabilized terbium-solution zirconia powder had a BET specific surface area of ​​10.2 m². 2 The particle size per g and the average particle diameter were 0.44 μm.

[0170] 199.9 g of the yttrium-stabilized terbium-solubility zirconia powder, 0.1 g of α-alumina powder, and pure water were mixed in a ball mill to form a slurry. To the obtained slurry, an acrylic acid-based binder was added and mixed so that the mass ratio of the binder to the mass of powder in the slurry was 3% by mass. The slurry was spray-dried in air at 180°C to obtain a granular powder (hereinafter also referred to as "Y(4.3)-stabilized Tb-solubility ZrO2 granular powder") containing 3% by mass of the acrylic acid-based binder and 0.05% by mass of alumina, with the remainder being zirconia stabilized with 4.3 mol% yttrium and 0.04 mol% terbium in solid solution. The average granular particle size of this granular powder was 43 μm.

[0171] (Erbium solid solution zirconia powder) A slurry containing erbium-solution zirconia powder was obtained using the same method as for yttrium-stabilized zirconia powder, except that erbium oxide was added to the zirconia sol so that the erbium concentration was 4.4 mol% in terms of Er2O3, instead of yttrium chloride. The obtained erbium-solution zirconia powder had a BET specific surface area of ​​9.8 m². 2 The particle size per g and the average particle diameter were 0.45 μm.

[0172] 199.9 g of erbium-soluble zirconia powder, 0.1 g of α-alumina powder, and pure water were mixed in a ball mill to form a slurry. To the obtained slurry, an acrylic acid-based binder was added and mixed so that the mass ratio of the binder to the mass of powder in the slurry was 3% by mass. The slurry was spray-dried in air at 180°C to obtain a granular powder consisting of zirconia with 3% by mass of acrylic acid-based binder and 0.05% by mass of alumina, with the remainder being 4.4 mol% erbium-soluble zirconia (hereinafter also referred to as "Er(4.4)-soluble ZrO2 granular powder"). The average granular particle size of this granular powder was 42 μm.

[0173] (Granular powder containing cobalt oxide and titanium oxide) Cobalt oxide powder (Co3O4) and titanium oxide powder (TiO2) were used as colored metal powders. The yttrium-stabilized zirconia powder obtained in this example was separated and mixed with α-alumina powder, cobalt oxide powder, titanium oxide powder, and pure water in a ball mill to form a slurry. To the obtained slurry, an acrylic acid-based binder was added and mixed so that the mass ratio of the binder to the mass of powder in the slurry was 3% by mass. The slurry was spray-dried in air at 180°C to obtain a granular powder consisting of yttrium-stabilized zirconia containing 3% by mass of acrylic acid-based binder, 0.05% by mass of alumina, 0.06% by mass of tricobalt tetroxide, and 0.3% by mass of titanium oxide, with the remainder being 4.3 mol% (hereinafter also referred to as "Co-Ti-Y(4.3) stabilized ZrO2 granular powder"). The granular powder in question had an average granule size of 45 μm.

[0174] (Powder composition) The Y(4.3) stabilized ZrO2 granular powder, Y(4.3) stabilized Tb solid-solution ZrO2 granular powder, Er(4.4) solid-solution ZrO2 granular powder, and Co-Ti-Y(4.3) stabilized ZrO2 granular powder obtained in this example were filled into a 200 mL polypropylene container in a mass ratio of 85.6(85.55):6.5(6.45):3.5(3.50):4.5(4.50), and dry-mixed by stirring to obtain the powder composition of this example, which has the following composition and contains 144 ppm of colored metal elements.

[0175] Yttrium content: 4.154 mol% Erbium content: 0.146mol% Terbium content: 0.003 mol% Cobalt content: 24 ppm Titanium content: 120 ppm Alumina content: 0.05% by mass Zirconia content: Remainder The resulting powder composition has a BET specific surface area of ​​10.1 m². 2 The particle size was 0.45 μm, the average particle size was 380 nm, the monoclinic fraction was 6%, and the average granule size was 44 μm. Furthermore, the BET difference was 0.4 m for the Y(4.3) stabilized ZrO2 granular powder, Er(4.4) solid-solution ZrO2 granular powder, and Y(4.3) stabilized Tb solid-solution ZrO2 granular powder. 2 The particle size difference was 0.01 μm per g.

[0176] (Molded bodies, calcined bodies, and sintered bodies) 5.5 g of the obtained powder composition was filled into a mold with a diameter of 25 mm, subjected to uniaxial compression molding at a pressure of 49 MPa, and then treated with CIP at a pressure of 196 MPa to obtain a molded body (compacted powder).

[0177] The obtained molded body was calcined under the following conditions to obtain the calcined body of this embodiment. Calcining temperature: 1000℃ Pre-cooking time: 2 hours Heating rate: 50°C / hour Temporary combustion atmosphere: Atmospheric atmosphere Cooling rate: 300℃ / hour

[0178] The calcined body of this embodiment was sintered under the following conditions to obtain the sintered body of this embodiment. Sintering method: Atmospheric pressure sintering Sintering temperature: 1500℃ Sintering time: 2 hours Heating rate: 600°C / hour Sintering atmosphere: Atmospheric atmosphere

[0181] Example 3 The powder composition of this example was obtained in the same manner as in Example 1, except that Y(4.3) stabilized ZrO2 granular powder, Y(4.3) stabilized Tb solid-solution ZrO2 granular powder, Er(4.4) solid-solution ZrO2 granular powder, and Co-Ti-Y(4.3) stabilized ZrO2 granular powder were mixed in a mass ratio of 91.7:4.5:1.3:2.5, and having the following composition and a colored metal element content of 90 ppm.

[0182] Yttrium content: 4.244 mol% Erbium content: 0.053 mol% Terbium content: 0.002 mol% Cobalt content: 15 ppm Titanium content: 75 ppm Alumina content: 0.05% by mass Zirconia content: Remainder The resulting powder composition has a BET specific surface area of ​​10.1 m². 2 The sample size was 0.45 μm, with an average particle diameter of 0.45 μm, a crystallite size of 370 Å, a monoclinic fraction of 7%, and an average granule size of 44 μm.

[0183] Example 4 The powder composition of this example was obtained in the same manner as in Example 1, except that Y(4.3) stabilized ZrO2 granular powder, Y(4.3) stabilized Tb solid-solution ZrO2 granular powder, Er(4.4) solid-solution ZrO2 granular powder, and Co-Ti-Y(4.3) stabilized ZrO2 granular powder were mixed in a mass ratio of 77.0:15.0:3.0:5.0, and having the following composition and a colored metal element content of 180 ppm.

[0184] Yttrium content: 4.176 mol% Erbium content: 0.125 mol% Terbium content: 0.006 mol% Cobalt content: 30 ppm Titanium content: 150 ppm Alumina content: 0.05% by mass Zirconia content: Remainder The resulting powder composition has a BET specific surface area of ​​10.1 m². 2 / g, average particle size 0.45μ The crystallite size was 370 Å, monoclinic fraction was 7%, and average granule size was 44 μm.

[0185] Example 5 The powder composition of this example was obtained in the same manner as in Example 1, except that Y(4.3) stabilized ZrO2 granular powder, Y(4.3) stabilized Tb solid-solution ZrO2 granular powder, Er(4.4) solid-solution ZrO2 granular powder, and Co-Ti-Y(4.3) stabilized ZrO2 granular powder were mixed in a mass ratio of 64.9:22.5:5.1:7.5, and having the following composition and a colored metal element content of 270 ppm.

[0186] Yttrium content: 4.089 mol% Erbium content: 0.215 mol% Terbium content: 0.009 mol% Cobalt content: 45 ppm Titanium content: 225 ppm Alumina content: 0.05% by mass Zirconia content: Remainder The resulting powder composition has a BET specific surface area of ​​10.1 m². 2 The sample size was 0.45 μm, with an average particle diameter of 0.45 μm, a crystallite size of 370 Å, a monoclinic fraction of 7%, and an average granule size of 44 μm.

[0187] Example 6 The powder composition of this example was obtained in the same manner as in Example 1, except that Y(4.3) stabilized ZrO2 granular powder, Y(4.3) stabilized Tb solid-solution ZrO2 granular powder, Er(4.4) solid-solution ZrO2 granular powder, and Co-Ti-Y(4.3) stabilized ZrO2 granular powder were mixed in a mass ratio of 35.6:35.0:9.4:20.0, and having the following composition and a colored metal element content of 720 ppm.

[0188] Yttrium content: 3.917 mol% Erbium content: 0.395 mol% Terbium content: 0.014 mol% Cobalt content: 120 ppm Titanium content: 600 ppm Alumina content: 0.05% by mass Zirconia content: Remainder The resulting powder composition has a BET specific surface area of ​​10.1 m². 2 The sample size was 0.45 μm, with an average particle diameter of 0.45 μm, a crystallite size of 375 Å, a monoclinic fraction of 7%, and an average granule size of 44 μm.

[0189] Example 7 The powder composition of this example was obtained in the same manner as in Example 1, except that Y(4.3) stabilized ZrO2 granular powder, Y(4.3) stabilized Tb solid-solution ZrO2 granular powder, Er(4.4) solid-solution ZrO2 granular powder, and Co-Ti-Y(4.3) stabilized ZrO2 granular powder were mixed in a mass ratio of 90.6:6.0:0.9:2.5, and having the following composition and a colored metal element content of 90 ppm.

[0190] Yttrium content: 4.262 mol% Erbium content: 0.035 mol% Terbium content: 0.002 mol% Cobalt content: 15 ppm Titanium content: 75 ppm Alumina content: 0.05% by mass Zirconia content: Remainder The resulting powder composition has a BET specific surface area of ​​10.1 m². 2 The sample size was 0.45 μm, with an average particle diameter of 0.45 μm, a crystallite size of 370 Å, a monoclinic fraction of 7%, and an average granule size of 44 μm.

[0191] Example 8 The powder composition of this example was obtained in the same manner as in Example 1, except that Y(4.3) stabilized ZrO2 granular powder, Y(4.3) stabilized Tb solid-solution ZrO2 granular powder, Er(4.4) solid-solution ZrO2 granular powder, and Co-Ti-Y(4.3) stabilized ZrO2 granular powder were mixed in a mass ratio of 86.5:8.50:1.7:3.3, and having the following composition and a colored metal element content of 118 ppm.

[0192] Yttrium content: 4.227 mol% Erbium content: 0.071 mol% Terbium content: 0.003 mol% Cobalt content: 20 ppm Titanium content: 98 ppm Alumina content: 0.05% by mass Zirconia content: Remainder The resulting powder composition has a BET specific surface area of ​​10.1 m². 2 The sample size was 0.45 μm, with an average particle diameter of 0.45 μm, a crystallite size of 370 Å, a monoclinic fraction of 7%, and an average granule size of 44 μm.

[0193] Example 9 A powder composition of this example having the following composition and a content of colored metal elements of 226 ppm was obtained in the same manner as in Example 1, except that Y(4.3)-stabilized ZrO₂ particulate powder, Y(4.3)-stabilized Tb-solid-solution ZrO₂ particulate powder, Er(4.4)-solid-solution ZrO₂ particulate powder, and Co-Ti-Y(4.3)-stabilized ZrO₂ particulate powder were mixed so that the mass ratio was 79.4:11.5:2.8:6.3.

[0194] Yttrium content: 4.182 mol% Erbium content: 0.118 mol% Terbium content: 0.005 mol% Cobalt content: 38 ppm Titanium content: 188 ppm Alumina content: 0.05 mass% Zirconia content: the balance The obtained powder composition had a BET specific surface area of 10.1 m 2 / g, an average particle diameter of 0.45 μm, a crystallite diameter of 370 Å, a monoclinic ratio of 7%, and an average grain diameter of 44 μm.

[0195] Example 10 A powder composition of this example having the following composition and a content of colored metal elements of 270 ppm was obtained in the same manner as in Example 1, except that Y(4.3)-stabilized ZrO₂ particulate powder, Y(4.3)-stabilized Tb-solid-solution ZrO₂ particulate powder, Er(4.4)-solid-solution ZrO₂ particulate powder, and Co-Ti-Y(4.3)-stabilized ZrO₂ particulate powder were mixed so that the mass ratio was 64.5:25.0:3.0:7.5.

[0196] Yttrium content: 4.177 mol% Erbium content: 0.125 mol% Terbium content: 0.010 mol% Cobalt content: 45 ppm Titanium content: 225 ppm Alumina content: 0.05 mass% Zirconia content: the balance The resulting powder composition has a BET specific surface area of ​​10.1 m². 2 The sample size was 0.45 μm, with an average particle diameter of 0.45 μm, a crystallite size of 370 Å, a monoclinic fraction of 7%, and an average granule size of 44 μm.

[0197] Example 11 The powder composition of this example was obtained in the same manner as in Example 1, except that Y(4.3) stabilized ZrO2 granular powder, Y(4.3) stabilized Tb solid-solution ZrO2 granular powder, Er(4.4) solid-solution ZrO2 granular powder, and Co-Ti-Y(4.3) stabilized ZrO2 granular powder were mixed in a mass ratio of 86.2:5.0:1.3:7.5, and having the following composition and a colored metal element content of 270 ppm.

[0198] Yttrium content: 4.245 mol% Erbium content: 0.053 mol% Terbium content: 0.002 mol% Cobalt content: 45 ppm Titanium content: 225 ppm Alumina content: 0.05% by mass Zirconia content: Remainder The resulting powder composition has a BET specific surface area of ​​10.1 m². 2 The sample size was 0.45 μm, with an average particle diameter of 0.45 μm, a crystallite size of 370 Å, a monoclinic fraction of 7%, and an average granule size of 44 μm.

[0199] Example 12 The powder composition of this example was obtained in the same manner as in Example 1, except that Y(4.3) stabilized ZrO2 granular powder, Y(4.3) stabilized Tb solid-solution ZrO2 granular powder, Er(4.4) solid-solution ZrO2 granular powder, and Co-Ti-Y(4.3) stabilized ZrO2 granular powder were mixed in a mass ratio of 75.6:11.0:2.1:11.3, and having the following composition and a colored metal element content of 406 ppm.

[0200] Yttrium content: 4.211 mol% Erbium content: 0.089 mol% Terbium content: 0.004 mol% Cobalt content: 68 ppm Titanium content: 338 ppm Alumina content: 0.05% by mass Zirconia content: Remainder The resulting powder composition has a BET specific surface area of ​​10.1 m². 2 The sample size was 0.45 μm, with an average particle diameter of 0.45 μm, a crystallite size of 370 Å, a monoclinic fraction of 7%, and an average granule size of 44 μm.

[0201] Example 13 The powder composition of this example was obtained in the same manner as in Example 1, except that Y(4.3) stabilized ZrO2 granular powder, Y(4.3) stabilized Tb solid-solution ZrO2 granular powder, Er(4.4) solid-solution ZrO2 granular powder, and Co-Ti-Y(4.3) stabilized ZrO2 granular powder were mixed in a mass ratio of 61.2:20.0:1.3:17.5, and having the following composition and a colored metal element content of 630 ppm.

[0202] Yttrium content: 4.248 mol% Erbium content: 0.053 mol% Terbium content: 0.008 mol% Cobalt content: 105 ppm Titanium content: 525 ppm Alumina content: 0.05% by mass Zirconia content: Remainder The resulting powder composition has a BET specific surface area of ​​10.1 m². 2 The sample size was 0.45 μm, with an average particle diameter of 0.45 μm, a crystallite size of 370 Å, a monoclinic fraction of 7%, and an average granule size of 44 μm.

[0203] Example 14 A powder composition of this example having the following composition and a content of coloring metal elements of 450 ppm was obtained in the same manner as in Example 1, except that Y(4.3)-stabilized ZrO₂ particulate powder, Y(4.3)-stabilized Tb-doped ZrO₂ particulate powder, Er(4.4)-doped ZrO₂ particulate powder, and Co-Ti-Y(4.3)-stabilized ZrO₂ particulate powder were mixed so that the mass ratio was 69.5:15.0:3.0:12.5.

[0204] Yttrium content: 4.177 mol% Erbium content: 0.125 mol% Terbium content: 0.006 mol% Cobalt content: 75 ppm Titanium content: 375 ppm Alumina content: 0.05 mass% Zirconia content: the balance The obtained powder composition had a BET specific surface area of 10.1 m 2 / g, an average particle diameter of 0.45 μm, a crystallite diameter of 370 Å, a monoclinic ratio of 7%, and an average grain diameter of 44 μm.

[0205] Example 15 A powder composition of this example having the following composition and a content of coloring metal elements of 316 ppm was obtained in the same manner as in Example 1, except that Y(4.3)-stabilized ZrO₂ particulate powder, Y(4.3)-stabilized Tb-doped ZrO₂ particulate powder, Er(4.4)-doped ZrO₂ particulate powder, and Co-Ti-Y(4.3)-stabilized ZrO₂ particulate powder were mixed so that the mass ratio was 63.6:22.5:5.1:8.8.

[0206] Yttrium content: 4.089 mol% Erbium content: 0.215 mol% Terbium content: 0.009 mol% Cobalt content: 53 ppm Titanium content: 263 ppm Alumina content: 0.05 mass% Zirconia content: the balance The resulting powder composition has a BET specific surface area of ​​10.1 m². 2 The sample size was 0.45 μm, with an average particle diameter of 0.45 μm, a crystallite size of 370 Å, a monoclinic fraction of 7%, and an average granule size of 44 μm.

[0207] Example 16 The powder composition of this example was obtained in the same manner as in Example 1, except that Y(4.3) stabilized ZrO2 granular powder, Y(4.3) stabilized Tb solid-solution ZrO2 granular powder, Er(4.4) solid-solution ZrO2 granular powder, and Co-Ti-Y(4.3) stabilized ZrO2 granular powder were mixed in a mass ratio of 71.5:17.5:1.7:9.3, and having the following composition and a colored metal element content of 334 ppm.

[0208] Yttrium content: 4.229 mol% Erbium content: 0.071 mol% Terbium content: 0.007 mol% Cobalt content: 56 ppm Titanium content: 278 ppm Alumina content: 0.05% by mass Zirconia content: Remainder The resulting powder composition has a BET specific surface area of ​​10.1 m². 2 The sample size was 0.45 μm, with an average particle diameter of 0.45 μm, a crystallite size of 370 Å, a monoclinic fraction of 7%, and an average granule size of 44 μm.

[0209] Example 17 (Yttrium-stabilized zirconia powder) Except for adding yttrium chloride to the zirconia sol so that the yttrium concentration was 2.9 mol% in terms of Y2O3, and firing at 1100°C for 2 hours, a granular powder (hereinafter also referred to as "Y(2.9) stabilized ZrO2 granular powder 1") was obtained in the same manner as the yttrium-stabilized zirconia powder of Example 1, containing 3% by mass of an acrylic acid-based binder and 0.05% by mass of alumina, with the remainder being 2.9 mol% yttrium-stabilized zirconia powder. Evaluating the yttrium-stabilized zirconia powder in the same manner as in Example 1, the BET specific surface area was found to be 13.0 m². 2 The particle size and average particle diameter were 0.45 μm. The granular powder had an average granule size of 44 μm.

[0210] (Powder composition) The powder composition of this example was obtained in the same manner as in Example 1, except that Y(2.9) stabilized ZrO2 granular powder 1, Y(4.3) stabilized Tb solid-solution ZrO2 granular powder, Er(4.4) solid-solution ZrO2 granular powder, and Co-Ti-Y(4.3) stabilized ZrO2 granular powder were mixed in a mass ratio of 87.3:7.5:2.0:3.2, and the powder composition of this example having the following composition and a colored metal element content of 118 ppm was obtained.

[0211] Yttrium content: 3.025 mol% Erbium content: 0.083 mol% Terbium content: 0.003 mol% Cobalt content: 20 ppm Titanium content: 98 ppm Alumina content: 0.05% by mass Zirconia content: Remainder The resulting powder composition has a BET specific surface area of ​​12.6 m². 2 The average particle size was 0.45 μm, the crystallite size was 360 Å, the monoclinic fraction was 31%, and the average granule size was 44 μm.

[0212] Example 18 The powder composition of this example was obtained in the same manner as in Example 1, except that Y(2.9) stabilized ZrO2 granular powder 1, Y(4.3) stabilized Tb solid-solution ZrO2 granular powder, Er(4.4) solid-solution ZrO2 granular powder, and Co-Ti-Y(4.3) stabilized ZrO2 granular powder were mixed in a mass ratio of 61.2:20.0:1.3:17.5, and having the following composition and a colored metal element content of 630 ppm.

[0213] Yttrium content: 3.410 mol% Erbium content: 0.053 mol% Terbium content: 0.008 mol% Cobalt content: 105 ppm Titanium content: 525 ppm Alumina content: 0.05% by mass Zirconia content: Remainder The resulting powder composition has a BET specific surface area of ​​11.8 m². 2 The sample size was 0.45 μm, with an average particle diameter of 0.45 μm, a crystallite size of 370 Å, a monoclinic fraction of 24%, and an average granule size of 44 μm.

[0214] Example 19 The powder composition of this example was obtained in the same manner as in Example 1, except that Y(2.9) stabilized ZrO2 granular powder 1, Y(4.3) stabilized Tb solid-solution ZrO2 granular powder, Er(4.4) solid-solution ZrO2 granular powder, and Co-Ti-Y(4.3) stabilized ZrO2 granular powder were mixed in a mass ratio of 24.0:45.0:4.3:26.7, and having the following composition and a colored metal element content of 960 ppm.

[0215] Yttrium content: 3.844 mol% Erbium content: 0.178 mol% Terbium content: 0.018 mol% Cobalt content: 160 ppm Titanium content: 800 ppm Alumina content: 0.05% by mass Zirconia content: Remainder The resulting powder composition has a BET specific surface area of ​​10.6 m². 2 The sample size was 0.45 μm, with an average particle diameter of 0.45 μm, a crystallite size of 370 Å, a monoclinic fraction of 13%, and an average granule size of 44 μm.

[0216] Example 20 (Yttrium-stabilized zirconia powder) Except for adding yttrium chloride to the zirconia sol so that the yttrium concentration was 2.9 mol% in terms of Y2O3, and firing at 1175°C for 2 hours, a granular powder (hereinafter also referred to as "Y(2.9) stabilized ZrO2 granular powder 2") was obtained in the same manner as the yttrium-stabilized zirconia powder of Example 1, containing 3% by mass of an acrylic acid-based binder and 0.05% by mass of alumina, with the remainder being 2.9 mol% yttrium-stabilized zirconia powder. Evaluating the yttrium-stabilized zirconia powder in the same manner as in Example 1, the BET specific surface area was found to be 10.1 m². 2 The particle size and average particle diameter were 0.45 μm. The granular powder had an average granule size of 44 μm.

[0217] (Powder composition) The powder composition of this example was obtained in the same manner as in Example 1, except that Y(2.9) stabilized ZrO2 granular powder 2, Y(4.3) stabilized Tb solid-solution ZrO2 granular powder, Er(4.4) solid-solution ZrO2 granular powder, and Co-Ti-Y(4.3) stabilized ZrO2 granular powder were mixed in a mass ratio of 87.3:7.5:2.0:3.2, and the powder composition of this example having the following composition and a colored metal element content of 118 ppm was obtained.

[0218] Yttrium content: 3.025 mol% Erbium content: 0.083 mol% Terbium content: 0.003 mol% Cobalt content: 20 ppm Titanium content: 98 ppm Alumina content: 0.05% by mass Zirconia content: Remainder The resulting powder composition has a BET specific surface area of ​​10.1 m².2 The sample size was 0.45 μm, with an average particle diameter of 0.45 μm, a crystallite size of 370 Å, a monoclinic fraction of 30%, and an average granule size of 44 μm.

[0219] Example 21 The powder composition of this example was obtained in the same manner as in Example 1, except that Y(2.9) stabilized ZrO2 granular powder 2, Y(4.3) stabilized Tb solid-solution ZrO2 granular powder, Er(4.4) solid-solution ZrO2 granular powder, and Co-Ti-Y(4.3) stabilized ZrO2 granular powder were mixed in a mass ratio of 61.2:20.0:1.3:17.5, and having the following composition and a colored metal element content of 630 ppm.

[0220] Yttrium content: 3.410 mol% Erbium content: 0.053 mol% Terbium content: 0.008 mol% Cobalt content: 105 ppm Titanium content: 525 ppm Alumina content: 0.05% by mass Zirconia content: Remainder The resulting powder composition has a BET specific surface area of ​​10.1 m². 2 The sample size was 0.45 μm, with an average particle diameter of 0.45 μm, a crystallite size of 370 Å, a monoclinic fraction of 20%, and an average granule size of 44 μm.

[0221] Example 22 The powder composition of this example was obtained in the same manner as in Example 1, except that Y(2.9) stabilized ZrO2 granular powder 2, Y(4.3) stabilized Tb solid-solution ZrO2 granular powder, Er(4.4) solid-solution ZrO2 granular powder, and Co-Ti-Y(4.3) stabilized ZrO2 granular powder were mixed in a mass ratio of 24.0:45.0:4.3:26.7, and having the following composition and a colored metal element content of 960 ppm.

[0222] Yttrium content: 3.844 mol% Erbium content: 0.178 mol% Terbium content: 0.018 mol% Cobalt content: 160 ppm Titanium content: 800 ppm Alumina content: 0.05% by mass Zirconia content: Remainder The resulting powder composition has a BET specific surface area of ​​10.1 m². 2 The sample size was 0.45 μm, with an average particle diameter of 0.45 μm, a crystallite size of 370 Å, a monoclinic fraction of 13%, and an average granule size of 44 μm.

[0223] Example 23 (Yttrium-stabilized zirconia powder) Except for adding yttrium chloride to the zirconia sol so that the yttrium concentration was 5.3 mol% in terms of Y2O3, and firing at 1175°C for 2 hours, a zirconia powder stabilized with 5.3 mol% yttrium was obtained in the same manner as the yttrium-stabilized zirconia powder of Example 1. Evaluating the yttrium-stabilized zirconia powder in the same manner as in Example 1, the BET specific surface area was found to be 10.0 m². 2 The yttrium-stabilized zirconia powder obtained had a particle size of 0.45 μm / g and an average particle diameter of 0.45 μm. The yttrium-stabilized zirconia powder obtained contained 3% by mass of an acrylic acid-based binder and 0.05% by mass of alumina, with the remainder being 5.3 mol% yttrium-stabilized zirconia (hereinafter also referred to as "Y(5.3) stabilized ZrO2 granular powder"). The average granular particle size of this granular powder was 44 μm.

[0224] (Powder composition) The powder composition of this example was obtained in the same manner as in Example 1, except that Y(5.3) stabilized ZrO2 granular powder, Y(4.3) stabilized Tb solid-solution ZrO2 granular powder, Er(4.4) solid-solution ZrO2 granular powder, and Co-Ti-Y(4.3) stabilized ZrO2 granular powder were mixed in a mass ratio of 74.9:16.5:3.1:5.5, and having the following composition and a colored metal element content of 198 ppm.

[0225] Yttrium content: 4.945 mol% Erbium content: 0.130 mol% Terbium content: 0.007 mol% Cobalt content: 33 ppm Titanium content: 165 ppm Alumina content: 0.05 mass% Zirconia content: the balance The obtained powder composition had a BET specific surface area of 10.1 m 2 / g, an average particle diameter of 0.45 μm, a crystallite diameter of 390 Å, a monoclinic ratio of 2%, and an average agglomerate diameter of 44 μm.

[0226] Example 24 A powder composition of this Example having the following composition and a content of coloring metal elements of 648 ppm was obtained in the same manner as in Example 1, except that Y(5.3) stabilized ZrO2 particle powder, Y(4.3) stabilized Tb solid-solution ZrO2 particle powder, Er(4.4) solid-solution ZrO2 particle powder, and Co-Ti-Y(4.3) stabilized ZrO2 particle powder were mixed so that the mass ratio became 61.1:20.3:0.6:18.0.

[0227] Yttrium content: 4.905 mol% Erbium content: 0.026 mol% Terbium content: 0.008 mol% Cobalt content: 108 ppm Titanium content: 540 ppm Alumina content: 0.05 mass% Zirconia content: the balance The obtained powder composition had a BET specific surface area of 10.1 m 2 / g, an average particle diameter of 0.45 μm, a crystallite diameter of 380 Å, a monoclinic ratio of 3%, and an average agglomerate diameter of 44 μm.

[0228] Example 25 The powder composition of this example was obtained in the same manner as in Example 1, except that Y(5.3) stabilized ZrO2 granular powder, Y(4.3) stabilized Tb solid-solution ZrO2 granular powder, Er(4.4) solid-solution ZrO2 granular powder, and Co-Ti-Y(4.3) stabilized ZrO2 granular powder were mixed in a mass ratio of 35.4:36.4:2.2:26.0, and having the following composition and a colored metal element content of 936 ppm.

[0229] Yttrium content: 4.577 mol% Erbium content: 0.093 mol% Terbium content: 0.015 mol% Cobalt content: 156 ppm Titanium content: 780 ppm Alumina content: 0.05% by mass Zirconia content: Remainder The resulting powder composition has a BET specific surface area of ​​10.1 m². 2 The sample size was 0.45 μm, with an average particle diameter of 0.45 μm, a crystallite size of 380 Å, a monoclinic fraction of 5%, and an average granule size of 44 μm.

[0230] Example 26 (Titanium dioxide-containing yttrium-stabilized neodymium-solution zirconia powder) Except for adding yttrium chloride to the zirconia sol so that the yttrium concentration was 1.6 mol% (based on Y2O3) and neodymium oxide to the zirconia sol so that the neodymium concentration was 1.5 mol% (based on Nd2O3), and then calcining at 1120°C for 2 hours, a zirconia powder stabilized with 1.6 mol% yttrium and containing 1.5 mol% neodymium in solid solution was obtained using the same method as in Example 1. Evaluating the powder using the same method as in Example 1, the BET specific surface area was found to be 10.1 m². 2The particle size and average particle diameter were 0.45 μm. Except for mixing the obtained powder, alumina powder, titanium oxide powder, and pure water in a ball mill, a granular powder (hereinafter also referred to as "Ti-Y(1.6) stabilized Nd solid-solution ZrO2 granular powder") was obtained in the same manner as the yttrium-stabilized zirconia powder of Example 1, containing 3% by mass of an acrylic acid binder, 0.05% by mass of alumina, and 0.1% by mass of titanium oxide, with the remainder being stabilized with 1.6 mol% yttrium and 1.5 mol% neodymium solid-solution zirconia. The average granular particle size of this granular powder was 44 μm.

[0231] (Powder composition) The powder composition of this example was obtained in the same manner as in Example 1, except that Y(4.3) stabilized ZrO2 granular powder, Y(4.3) stabilized Tb solid-solution ZrO2 granular powder, Er(4.4) solid-solution ZrO2 granular powder, and Ti-Y(1.6) stabilized Nd solid-solution ZrO2 granular powder were mixed in a mass ratio of 87.9:7.5:3.1:1.5, and having the following composition and a colored metal element content of 15 ppm.

[0232] Yttrium content: 4.127 mol% Erbium content: 0.132 mol% Terbium content: 0.003 mol% Neodymium content: 0.023 mol% Titanium content: 15 ppm Alumina content: 0.05% by mass Zirconia content: Remainder The obtained powder composition had a BET specific surface area of ​​10.1 m² / g, an average particle size of 0.45 μm, a crystallite size of 370 Å, a monoclinic fraction of 7%, and an average granule size of 44 μm.

[0233] Example 27 The powder composition of this example was obtained in the same manner as in Example 1, except that Y(4.3) stabilized ZrO2 granular powder, Y(4.3) stabilized Tb solid-solution ZrO2 granular powder, Er(4.4) solid-solution ZrO2 granular powder, and Ti-Y(1.6) stabilized Nd solid-solution ZrO2 granular powder were mixed in a mass ratio of 39.5:38.4:3.2:18.9, and having the following composition and a colored metal element content of 189 ppm.

[0234] Yttrium content: 3.667 mol% Erbium content: 0.135 mol% Terbium content: 0.016 mol% Neodymium content: 0.288 mol% Titanium content: 189 ppm Alumina content: 0.05% by mass Zirconia content: Remainder The resulting powder composition has a BET specific surface area of ​​10.1 m². 2 The sample size was 0.45 μm, with an average particle diameter of 0.45 μm, a crystallite size of 370 Å, a monoclinic fraction of 10%, and an average granule size of 44 μm.

[0237] Example 29 (Yttrium-stabilized praseodymium-solution zirconia powder) Yttrium chloride and praseodymium concentrations are adjusted so that the yttrium concentration is 1.6 mol% in Y2O3 equivalent. 11 Except for adding praseodymium oxide to the zirconia sol to a converted amount of 0.76 mol% and firing at 1120°C for 2 hours, a granular powder (hereinafter also referred to as "Y(1.6) stabilized Pr solid-solution ZrO2 granular powder") was obtained in the same manner as the yttrium-stabilized zirconia powder of Example 1, containing 3% by mass of an acrylic acid-based binder and 0.05% by mass of alumina, with the remainder being stabilized by 1.6 mol% yttrium and containing 0.76 mol% praseodymium in solid solution. The powder was evaluated in the same manner as in Example 1, and the BET specific surface area was found to be 10.0 m². 2 / g and the average particle diameter was 0.45 μm. The obtained powder, the granular powder, had an average grain diameter of 43 μm.

[0238] (Powder composition) A powder composition of this Example having the following composition and a content of colored metal elements of 550 ppm was obtained in the same manner as in Example 1, except that Y(4.3) stabilized ZrO2 granular powder, Er(4.4) solid-solution ZrO2 granular powder, Co-Ti-Y(4.3) stabilized ZrO2 granular powder and Y(1.6) stabilized Pr solid-solution ZrO2 granular powder were mixed so that the mass ratio became 82.5:1.0:15.3:1.2.

[0239] Yttrium content: 4.225 mol% Erbium content: 0.042 mol% Praseodymium content: 0.012 mol% Cobalt content: 92 ppm Titanium content: 458 ppm Alumina content: 0.05 mass% Zirconia content: the balance The obtained powder composition had a BET specific surface area of 10.1 m 2 / g, an average particle diameter of 0.45 μm, a crystallite diameter of 370 Å, a monoclinic ratio of 8% and an average grain diameter of 44 μm.

[0240] Example 30 A powder composition of this Example having the following composition and a content of colored metal elements of 550 ppm was obtained in the same manner as in Example 1, except that Y(4.3) stabilized ZrO2 granular powder, Er(4.4) solid-solution ZrO2 granular powder, Co-Ti-Y(4.3) stabilized ZrO2 granular powder and Y(1.6) stabilized Pr solid-solution ZrO2 granular powder were mixed so that the mass ratio became 81.8:0.9:15.3:2.0.

[0241] Yttrium content: 4.210 mol% Erbium content: 0.036 mol% Praseodymium content: 0.020 mol% Cobalt content: 92 ppm Titanium content: 458 ppm Alumina content: 0.05% by mass Zirconia content: Remainder The resulting powder composition has a BET specific surface area of ​​10.1 m². 2 The sample size was 0.45 μm, with an average particle diameter of 0.45 μm, a crystallite size of 370 Å, a monoclinic fraction of 9%, and an average granule size of 44 μm.

[0242] Example 31 The powder composition of this example was obtained in the same manner as in Example 1, except that Y(4.3) stabilized ZrO2 granular powder, Er(4.4) solid-solution ZrO2 granular powder, Co-Ti-Y(4.3) stabilized ZrO2 granular powder, and Y(1.6) stabilized Pr solid-solution ZrO2 granular powder were mixed in a mass ratio of 56.3:1.2:39.5:3.0, and having the following composition and a colored metal element content of 1079 ppm.

[0243] Yttrium content: 4.173 mol% Erbium content: 0.050 mol% Praseodymium content: 0.030 mol% Cobalt content: 229 ppm Titanium content: 850 ppm Alumina content: 0.05% by mass Zirconia content: Remainder The resulting powder composition has a BET specific surface area of ​​10.1 m². 2 The sample size was 0.45 μm, with an average particle diameter of 0.45 μm, a crystallite size of 370 Å, a monoclinic fraction of 10%, and an average granule size of 44 μm.

[0244] (Molded bodies, calcined bodies, and sintered bodies) Molded bodies (compacted powders), calcined bodies, and sintered bodies were obtained in the same manner as in Example 1, except that the powder compositions obtained in Examples 2 to 31 were used.

[0245] Comparative Example 1 (Yttrium-stabilized zirconia powder) Using a method similar to that of the yttrium-stabilized zirconia powder in Example 1, a granular powder (Y(4.3) stabilized ZrO2 granular powder) was obtained consisting of zirconia stabilized with yttrium, containing 0.05% by mass of alumina and the remainder being 4.3 mol%.

[0246] (Erbium solid solution zirconia powder) Using a method similar to that of the erbium-solution zirconia powder in Example 1, a granular powder (Er(4.4) solid-solution ZrO2 granular powder) was obtained consisting of zirconia in which erbium is solid-solved, with the remainder being 4.4 mol% alumina.

[0247] (Cobalt oxide granules powder) Cobalt oxide powder (Co3O4) was used as the colored metal powder. A portion of the yttrium-stabilized zirconia powder obtained in this comparative example was taken out and mixed with α-alumina powder, cobalt oxide, and pure water in a ball mill to form a slurry. To the obtained slurry, an acrylic acid-based binder was added and mixed so that the mass ratio of the binder to the mass of powder in the slurry was 3% by mass. The slurry was spray-dried in air at 180°C to obtain a granular powder (hereinafter also referred to as "Co-Y(4.3) stabilized ZrO2 granular powder") containing 3% by mass of acrylic acid-based binder, 0.05% by mass of alumina, and 0.06% by mass of cobalt oxide, with the remainder being 4.3 mol% yttrium-stabilized zirconia. The average granule size of the obtained granular powder was 44 μm.

[0248] (Iron oxide granules powder) Iron oxide (Fe2O3) powder was used as the colored metal powder. A portion of the yttrium-stabilized zirconia powder obtained in this comparative example was taken out and mixed with α-alumina powder, iron oxide, and pure water in a ball mill to form a slurry. To the obtained slurry, an acrylic acid-based binder was added and mixed so that the mass ratio of the binder to the mass of powder in the slurry was 3% by mass. The slurry was spray-dried in air at 180°C to obtain a granular powder (hereinafter also referred to as "Fe-Y(4.3) stabilized ZrO2 granular powder") containing 3% by mass of acrylic acid-based binder, 0.05% by mass of alumina, and 0.2% by mass of iron oxide, with the remainder being 4.3 mol% yttrium-stabilized zirconia. The average granule size of the obtained granular powder was 46 μm.

[0249] (Powder composition) Y(4.3) stabilized ZrO2 granular powder, Er(4.4) solid-solution ZrO2 granular powder, Co-Y(4.3) stabilized ZrO2 granular powder, and Fe-Y(4.3) stabilized ZrO2 granular powder were filled into a 200 mL polypropylene container in a mass ratio of 85.6(85.55):6.5(6.45):3.5(3.50):4.5(3.50), and the mixture was dry-mixed by stirring to obtain the powder composition of this example, which has the following composition and contains 700 ppm of colored metal elements.

[0250] Yttrium content: 4.166 mol% Erbium content: 0.126 mol% Iron content: 700 ppm Cobalt content: 0 ppm Alumina content: 0.05% by mass Zirconia content: Remainder The resulting powder composition has a BET specific surface area of ​​10.1 m². 2 The sample size was 0.45 μm, with an average particle diameter of 0.45 μm, a crystallite size of 370 nm, a monoclinic fraction of 7%, and an average granule size of 45 μm.

[0251] (Molded bodies, calcined bodies, and sintered bodies) Molded bodies (compacted powder bodies), calcined bodies, and sintered bodies were obtained in the same manner as in Example 1, except that the obtained powder composition was used.

[0252] Comparative Example 2 The powder composition of this comparative example was obtained in the same manner as in Comparative Example 1, except that Y(4.3) stabilized ZrO2 granular powder, Er(4.4) solid-solution ZrO2 granular powder, Co-Y(4.3) stabilized ZrO2 granular powder, and Fe-Y(4.3) stabilized ZrO2 granular powder were dry-mixed in a mass ratio of 19.7(19.65):1.1(1.08):15.3(15.27):64.0(64.00). The powder composition of this comparative example had the following composition and a colored metal element content of 1372 ppm.

[0253] Yttrium content: 4.257 mol% Erbium content: 0.042 mol% Iron content: 1280 ppm Cobalt content: 92 ppm Alumina content: 0.05% by mass Zirconia content: Remainder The resulting powder composition has a BET specific surface area of ​​10.1 m². 2 The sample size was 0.45 μm, with an average particle diameter of 0.45 μm, a crystallite size of 370 nm, a monoclinic fraction of 7%, and an average granule size of 45 μm.

[0254] Comparative Example 3 (Terbium oxide granule powder) A portion of the yttrium-stabilized zirconia powder obtained in Comparative Example 1 was taken out and mixed with α-alumina powder, terbium oxide powder, and pure water in a ball mill to form a slurry. To the obtained slurry, an acrylic acid-based binder was added and mixed so that the mass ratio of the binder to the mass of powder in the slurry was 3% by mass. The slurry was spray-dried in air at 180°C to obtain a granular powder consisting of yttrium-stabilized zirconia containing 3% by mass of the acrylic acid-based binder, 0.05% by mass of alumina, and 0.04 mol% (0.24% by mass) of terbium oxide, with the remainder being 4.3 mol% (hereinafter also referred to as "Tb-Y(4.3) stabilized ZrO2 granular powder"). This granular powder had an average granule size of 45 μm and contained terbium as an oxide; however, the terbium was not solid-dissolved in the zirconia.

[0255] (Granular powder containing cobalt oxide and titanium oxide) Cobalt oxide powder (Co3O4) and titanium oxide powder (TiO2) were used as colored metal powders. A portion of the yttrium-stabilized zirconia powder obtained in Comparative Example 1 was taken out and mixed with α-alumina powder, cobalt oxide powder, titanium oxide powder, and pure water in a ball mill to form a slurry. An acrylic acid-based binder was added to the obtained slurry and mixed so that the mass ratio of the binder to the mass of powder in the slurry was 3% by mass. The slurry was spray-dried in air at 180°C to obtain a granular powder consisting of 3% by mass of acrylic acid-based binder, 0.05% by mass of alumina, 0.06% by mass of tricobalt tetroxide, and 0.30% by mass of titanium oxide, with the remainder being 4.3 mol% of yttrium-stabilized zirconia (hereinafter also referred to as "Co-Ti-Y(4.3) stabilized ZrO2 granular powder"). The granular powder in question had an average granule size of 45 μm.

[0256] (Powder composition) A powder composition for this comparative example was obtained in the same manner as in Example 1, except that Y(4.3) stabilized ZrO2 granular powder, Er(4.4) solid-solution ZrO2 granular powder, Tb-Y(4.3) stabilized ZrO2 granular powder, and Co-Ti-Y(4.3) stabilized ZrO2 granular powder were mixed in a mass ratio of 85.6:3.5:6.4:4.5, and having the following composition and a colored metal element content of 144 ppm.

[0257] Yttrium content: 4.154 mol% Erbium content: 0.146mol% Terbium content: 0.003mol% (0.02% by mass) Cobalt content: 24 ppm Titanium content: 120 ppm Alumina content: 0.05% by mass Zirconia content: Remainder The resulting powder composition has a BET specific surface area of ​​10.1 m². 2 The sample size was 0.45 μm, with an average particle diameter of 0.45 μm, a crystallite size of 370 Å, a monoclinic fraction of 7%, and an average granule size of 44 μm.

[0258] Comparative Example 4 The powder composition of this comparative example was obtained in the same manner as in Comparative Example 1, except that Y(4.3) stabilized ZrO2 granular powder, Er(4.4) solid-solution ZrO2 granular powder, Tb-Y(4.3) stabilized ZrO2 granular powder, and Co-Ti-Y(4.3) stabilized ZrO2 granular powder were dry-mixed in a mass ratio of 61.2:1.3:20.0:17.5, and having the following composition and a colored metal element content of 630 ppm.

[0259] Yttrium content: 4.248 mol% Erbium content: 0.053 mol% Terbium content: 0.008mol% (0.05% by mass) Cobalt content: 105 ppm Titanium content: 525 ppm Alumina content: 0.05% by mass Zirconia content: Remainder The resulting powder composition has a BET specific surface area of ​​10.1 m². 2 The sample size was 0.45 μm, with an average particle diameter of 0.45 μm, a crystallite size of 370 nm, a monoclinic fraction of 7%, and an average granule size of 45 μm.

[0260] Comparative Example 5 A powder composition for this comparative example was obtained in the same manner as in Comparative Example 1, except that Y(4.3) stabilized ZrO2 granular powder, Er(4.4) solid-solution ZrO2 granular powder, Tb-Y(4.3) stabilized ZrO2 granular powder, and Co-Ti-Y(4.3) stabilized ZrO2 granular powder were dry-mixed in a mass ratio of 22.5:6.5:46.0:25.0. The powder composition for this comparative example had the following composition and a colored metal element content of 900 ppm.

[0261] Yttrium content: 4.039 mol% Erbium content: 0.273 mol% Terbium content: 0.019mol% (0.11% by mass) Cobalt content: 150 ppm Titanium content: 750 ppm Alumina content: 0.05% by mass Zirconia content: Remainder The resulting powder composition has a BET specific surface area of ​​10.1 m². 2 The sample size was 0.45 μm, with an average particle diameter of 0.45 μm, a crystallite size of 370 nm, a monoclinic fraction of 7%, and an average granule size of 45 μm.

[0262] (Molded bodies, calcined bodies, and sintered bodies) Molded bodies (compacted powders), calcined bodies, and sintered bodies were obtained in the same manner as in Example 1, except that the powder compositions obtained in Comparative Examples 2 to 5 were used.

[0263] The results for the powder compositions and calcined bodies obtained in the examples and comparative examples are shown in the table below.

[0264] [Table 3]

[0265] [Table 4]

[0266] The examples and comparative examples are calcined bodies obtained under identical conditions, except for the different powder compositions used. All had a Vickers hardness suitable for CAD / CAM processing. However, while the hardness difference (A2 / C4) of Examples 1 (color: A2) and 2 (color: C4) was 5, the hardness difference (A2 / C4) of Comparative Examples 1 (color: A2) and 2 (color: C4) was 14, confirming that the processing characteristics of the comparative examples differed significantly depending on the color.

[0267] Furthermore, Examples 1 and 2, 4 through 16 have a hardness difference (A1) of 5 or less, confirming that they have similar processing characteristics regardless of color difference. Examples 17 through 31 have a hardness difference (A1) of 9 or less, confirming that they have similar processing characteristics regardless of color difference. On the other hand, Comparative Examples 1 and 2 have a hardness difference (A1) of 12 and 26, respectively, confirming that the processing characteristics differ depending on the color difference. Comparative Examples 3 through 5 have a large hardness difference (A1), confirming that the processing characteristics differ depending on the color difference.

[0268] Next, the characteristics of the sintered bodies obtained in the examples and comparative examples are shown in the table below.

[0269] [Table 5]

[0270] From the table above, it can be confirmed that both Example 1 and Comparative Example 1 have a color tone corresponding to A2, and both Example 2 and Comparative Example 2 have a color tone corresponding to C4. Furthermore, it can be confirmed that all of them have a bending strength of 1000 MPa or more, indicating that they possess mechanical strength suitable for use as dental prosthetic materials.

[0271] Furthermore, it can be confirmed that Examples 3 to 16 each have the color tones of Vita Classical Shades A1, A3, A3.5, A4, B1, B2, B3, B4, C1, C2, C3, D2, D3, or D4. It can also be confirmed that Examples 17 to 31 each have the color tones of Vita Classical Shades A2, B3, C3, or C4.

Claims

1. Two or more types of zirconia in which a lanthanide rare earth element selected from the group consisting of praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holonium, erbium, thulium, and ytterbium is solid-solved, Zirconia containing transition metal elements other than zirconium and hafnium, with the remainder being stabilized by one or more elements selected from the group consisting of yttrium, calcium, and magnesium, The powder composition is characterized in that the zirconia in which the lanthanide rare earth elements are solid-dissolved contains different lanthanide rare earth elements, and the content of the transition metal elements is 1500 ppm or less.

2. The powder composition according to claim 1, wherein at least one of the zirconia in which the lanthanide rare earth elements are solid-dissolved is zirconia in which one or more elements selected from the group consisting of praseodymium, samarium, terbium, dysprodium, holonium, and thulium are solid-dissolved.

3. The powder composition according to claim 1 or 2, wherein at least one of the zirconia in which the lanthanide rare earth elements are solid-dissolved is zirconia in which one or more elements selected from the group consisting of neodymium and erbium are solid-dissolved.

4. The powder composition according to any one of claims 1 to 3, wherein at least one of the zirconia in which the lanthanide rare earth element is solid-solved is zirconia stabilized with one or more selected from the group consisting of yttrium, calcium, and magnesium.

5. The powder composition according to any one of claims 1 to 4, wherein the transition metal element is one or more selected from the group consisting of manganese, cobalt, and titanium.

6. The powder composition according to any one of claims 1 to 5, wherein the transition metal element is included as one or more selected from the group consisting of oxides, hydroxides, oxyhydroxides, chlorides, sulfates, and nitrates.

7. The powder composition according to any one of claims 1 to 6, wherein the remainder is zirconia stabilized solely with yttrium.

8. The powder composition according to any one of claims 1 to 7, wherein the iron content is 100 ppm or less.

9. A powder composition according to any one of claims 1 to 8, comprising alumina.

10. The powder composition according to any one of claims 1 to 9, comprising granular particles composed of a transition metal element other than zirconium and hafnium, and zirconia stabilized with only one or more elements selected from the group consisting of yttrium, calcium, and magnesium.

11. BET specific surface area is 5 m ２ / g or more 15m ２ The powder composition according to any one of claims 1 to 10, wherein the amount is less than or equal to / g.

12. A method for producing a calcined body, characterized by using the powder composition described in any one of claims 1 to 11.

13. A method for producing a sintered body, characterized by using the powder composition described in any one of claims 1 to 12.

14. A calcined body composed of fused particles of transition metal compounds other than zirconium and hafnium, zirconia in which two or more lanthanide rare earth elements are solid-solved, and zirconia stabilized with only one or more selected from the group of yttrium, calcium, and magnesium, wherein the content of transition metal elements other than zirconium and hafnium is 1500 ppm or less, and the lanthanide rare earth element is one selected from the group of praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprodium, holonium, erbium, thulium, and ytterbium.

15. A method for manufacturing a sintered body, characterized by using the calcined body described in claim 14.

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